Handle mesh load failure without crashing

author: sfan5 <sfan5@live.de> 2021-03-12 19:30:56 +0100
committer: sfan5 <sfan5@live.de> 2021-03-12 20:56:02 +0100
commit: cff35cf0b328635b2c77c024343f8e7f2d016990 (patch)
tree: a347f326ca6fa00b75f8a23f1be5ea08b7b49134 /src/mapsector.h
parent: f213376b35795982edbdeb2caeb7ca9495b3848e (diff)
download: minetest-cff35cf0b328635b2c77c024343f8e7f2d016990.tar.gz
minetest-cff35cf0b328635b2c77c024343f8e7f2d016990.tar.bz2
minetest-cff35cf0b328635b2c77c024343f8e7f2d016990.zip
0 files changed, 0 insertions, 0 deletions
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 9d5cf7d2c..f62a8626b 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -61,6 +61,13 @@ configure_file(
 )
 
 set(common_SRCS
+	mapgen.cpp
+	content_inventory.cpp
+	content_nodemeta.cpp
+	content_craft.cpp
+	content_mapblock.cpp
+	content_mapnode.cpp
+	auth.cpp
 	collision.cpp
 	nodemetadata.cpp
 	serverobject.cpp
@@ -95,10 +102,11 @@ set(common_SRCS
 # Client sources
 set(minetest_SRCS
 	${common_SRCS}
+	mapblock_mesh.cpp
+	farmesh.cpp
 	keycode.cpp
 	clouds.cpp
 	clientobject.cpp
-	guiFurnaceMenu.cpp
 	guiMainMenu.cpp
 	guiKeyChangeMenu.cpp
 	guiMessageMenu.cpp
@@ -125,6 +133,7 @@ include_directories(
 	${CMAKE_BUILD_TYPE}
 	${PNG_INCLUDE_DIR}
 	"${PROJECT_SOURCE_DIR}/jthread"
+	"${PROJECT_SOURCE_DIR}/sqlite"
 )
 
 set(EXECUTABLE_OUTPUT_PATH ../bin)
@@ -143,6 +152,7 @@ if(BUILD_CLIENT)
 		${PLATFORM_LIBS}
 		${CLIENT_PLATFORM_LIBS}
 		jthread
+		sqlite3
 	)
 endif(BUILD_CLIENT)
 
@@ -153,6 +163,7 @@ if(BUILD_SERVER)
 		${ZLIB_LIBRARIES}
 		${PLATFORM_LIBS}
 		jthread
+		sqlite3
 	)
 endif(BUILD_SERVER)
 
@@ -181,21 +192,22 @@ else()
 	# Probably GCC
 	
 	if(WARN_ALL)
-		set(WARNING_FLAGS "-Wall")
+		set(RELEASE_WARNING_FLAGS "-Wall")
 	else()
-		set(WARNING_FLAGS "")
+		set(RELEASE_WARNING_FLAGS "")
 	endif()
-
+	
 	if(NOT APPLE)
 		set(WARNING_FLAGS "${WARNING_FLAGS} -Wno-unused-but-set-variable")
 	endif()
+	
 	if(APPLE)
 		set(CMAKE_OSX_ARCHITECTURES i386 CACHE STRING "do not build for 64-bit" FORCE)
 		set(ARCH i386)
 	endif()
-	
-	set(CMAKE_CXX_FLAGS_RELEASE "-DNDEBUG ${WARNING_FLAGS} -O3 -ffast-math -Wall -fomit-frame-pointer -pipe -funroll-loops")
-	set(CMAKE_CXX_FLAGS_DEBUG "-g -O1 -Wall")
+
+	set(CMAKE_CXX_FLAGS_RELEASE "-DNDEBUG ${RELEASE_WARNING_FLAGS} ${WARNING_FLAGS} -O3 -ffast-math -Wall -fomit-frame-pointer -pipe -funroll-loops")
+	set(CMAKE_CXX_FLAGS_DEBUG "-g -O1 -Wall ${WARNING_FLAGS}")
 
 	if(USE_GPROF)
 		set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -pg")
@@ -242,5 +254,6 @@ endif(BUILD_SERVER)
 # Subdirectories
 
 add_subdirectory(jthread)
+add_subdirectory(sqlite)
 
 #end
diff --git a/src/auth.cpp b/src/auth.cpp
new file mode 100644
index 000000000..5d61243c6
--- /dev/null
+++ b/src/auth.cpp
@@ -0,0 +1,264 @@
+/*
+Minetest-c55
+Copyright (C) 2011 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "auth.h"
+#include <fstream>
+#include <jmutexautolock.h>
+//#include "main.h" // for g_settings
+#include <sstream>
+#include "strfnd.h"
+#include "debug.h"
+
+// Convert a privileges value into a human-readable string,
+// with each component separated by a comma.
+std::string privsToString(u64 privs)
+{
+	std::ostringstream os(std::ios_base::binary);
+	if(privs & PRIV_BUILD)
+		os<<"build,";
+	if(privs & PRIV_TELEPORT)
+		os<<"teleport,";
+	if(privs & PRIV_SETTIME)
+		os<<"settime,";
+	if(privs & PRIV_PRIVS)
+		os<<"privs,";
+	if(privs & PRIV_SHOUT)
+		os<<"shout,";
+	if(os.tellp())
+	{
+		// Drop the trailing comma. (Why on earth can't
+		// you truncate a C++ stream anyway???)
+		std::string tmp = os.str();
+		return tmp.substr(0, tmp.length() -1);
+	}
+	return os.str();
+}
+
+// Converts a comma-seperated list of privilege values into a
+// privileges value. The reverse of privsToString(). Returns
+// PRIV_INVALID if there is anything wrong with the input.
+u64 stringToPrivs(std::string str)
+{
+	u64 privs=0;
+	Strfnd f(str);
+	while(f.atend() == false)
+	{
+		std::string s = trim(f.next(","));
+		if(s == "build")
+			privs |= PRIV_BUILD;
+		else if(s == "teleport")
+			privs |= PRIV_TELEPORT;
+		else if(s == "settime")
+			privs |= PRIV_SETTIME;
+		else if(s == "privs")
+			privs |= PRIV_PRIVS;
+		else if(s == "shout")
+			privs |= PRIV_SHOUT;
+		else
+			return PRIV_INVALID;
+	}
+	return privs;
+}
+
+AuthManager::AuthManager(const std::string &authfilepath):
+		m_authfilepath(authfilepath),
+		m_modified(false)
+{
+	m_mutex.Init();
+	
+	try{
+		load();
+	}
+	catch(SerializationError &e)
+	{
+		dstream<<"WARNING: AuthManager: creating "
+				<<m_authfilepath<<std::endl;
+	}
+}
+
+AuthManager::~AuthManager()
+{
+	save();
+}
+
+void AuthManager::load()
+{
+	JMutexAutoLock lock(m_mutex);
+	
+	dstream<<"AuthManager: loading from "<<m_authfilepath<<std::endl;
+	std::ifstream is(m_authfilepath.c_str(), std::ios::binary);
+	if(is.good() == false)
+	{
+		dstream<<"AuthManager: failed loading from "<<m_authfilepath<<std::endl;
+		throw SerializationError("AuthManager::load(): Couldn't open file");
+	}
+
+	for(;;)
+	{
+		if(is.eof() || is.good() == false)
+			break;
+
+		// Read a line
+		std::string line;
+		std::getline(is, line, '\n');
+
+		std::istringstream iss(line);
+		
+		// Read name
+		std::string name;
+		std::getline(iss, name, ':');
+
+		// Read password
+		std::string pwd;
+		std::getline(iss, pwd, ':');
+
+		// Read privileges
+		std::string stringprivs;
+		std::getline(iss, stringprivs, ':');
+		u64 privs = stringToPrivs(stringprivs);
+		
+		// Store it
+		AuthData ad;
+		ad.pwd = pwd;
+		ad.privs = privs;
+		m_authdata[name] = ad;
+	}
+
+	m_modified = false;
+}
+
+void AuthManager::save()
+{
+	JMutexAutoLock lock(m_mutex);
+	
+	dstream<<"AuthManager: saving to "<<m_authfilepath<<std::endl;
+	std::ofstream os(m_authfilepath.c_str(), std::ios::binary);
+	if(os.good() == false)
+	{
+		dstream<<"AuthManager: failed saving to "<<m_authfilepath<<std::endl;
+		throw SerializationError("AuthManager::save(): Couldn't open file");
+	}
+	
+	for(core::map<std::string, AuthData>::Iterator
+			i = m_authdata.getIterator();
+			i.atEnd()==false; i++)
+	{
+		std::string name = i.getNode()->getKey();
+		if(name == "")
+			continue;
+		AuthData ad = i.getNode()->getValue();
+		os<<name<<":"<<ad.pwd<<":"<<privsToString(ad.privs)<<"\n";
+	}
+
+	m_modified = false;
+}
+
+bool AuthManager::exists(const std::string &username)
+{
+	JMutexAutoLock lock(m_mutex);
+	
+	core::map<std::string, AuthData>::Node *n;
+	n = m_authdata.find(username);
+	if(n == NULL)
+		return false;
+	return true;
+}
+
+void AuthManager::set(const std::string &username, AuthData ad)
+{
+	JMutexAutoLock lock(m_mutex);
+	
+	m_authdata[username] = ad;
+
+	m_modified = true;
+}
+
+void AuthManager::add(const std::string &username)
+{
+	JMutexAutoLock lock(m_mutex);
+	
+	m_authdata[username] = AuthData();
+
+	m_modified = true;
+}
+
+std::string AuthManager::getPassword(const std::string &username)
+{
+	JMutexAutoLock lock(m_mutex);
+	
+	core::map<std::string, AuthData>::Node *n;
+	n = m_authdata.find(username);
+	if(n == NULL)
+		throw AuthNotFoundException("");
+	
+	return n->getValue().pwd;
+}
+
+void AuthManager::setPassword(const std::string &username,
+		const std::string &password)
+{
+	JMutexAutoLock lock(m_mutex);
+	
+	core::map<std::string, AuthData>::Node *n;
+	n = m_authdata.find(username);
+	if(n == NULL)
+		throw AuthNotFoundException("");
+	
+	AuthData ad = n->getValue();
+	ad.pwd = password;
+	n->setValue(ad);
+
+	m_modified = true;
+}
+
+u64 AuthManager::getPrivs(const std::string &username)
+{
+	JMutexAutoLock lock(m_mutex);
+	
+	core::map<std::string, AuthData>::Node *n;
+	n = m_authdata.find(username);
+	if(n == NULL)
+		throw AuthNotFoundException("");
+	
+	return n->getValue().privs;
+}
+
+void AuthManager::setPrivs(const std::string &username, u64 privs)
+{
+	JMutexAutoLock lock(m_mutex);
+	
+	core::map<std::string, AuthData>::Node *n;
+	n = m_authdata.find(username);
+	if(n == NULL)
+		throw AuthNotFoundException("");
+	
+	AuthData ad = n->getValue();
+	ad.privs = privs;
+	n->setValue(ad);
+
+	m_modified = true;
+}
+
+bool AuthManager::isModified()
+{
+	JMutexAutoLock lock(m_mutex);
+	return m_modified;
+}
+
+
diff --git a/src/auth.h b/src/auth.h
new file mode 100644
index 000000000..62dced2a3
--- /dev/null
+++ b/src/auth.h
@@ -0,0 +1,101 @@
+/*
+Minetest-c55
+Copyright (C) 2011 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#ifndef AUTH_HEADER
+#define AUTH_HEADER
+
+#include <string>
+#include <jthread.h>
+#include <jmutex.h>
+#include "common_irrlicht.h"
+#include "exceptions.h"
+
+// Player privileges. These form a bitmask stored in the privs field
+// of the player, and define things they're allowed to do. See also
+// the static methods Player::privsToString and stringToPrivs that
+// convert these to human-readable form.
+const u64 PRIV_BUILD = 1;            // Can build - i.e. modify the world
+const u64 PRIV_TELEPORT = 2;         // Can teleport
+const u64 PRIV_SETTIME = 4;          // Can set the time
+const u64 PRIV_PRIVS = 8;            // Can grant and revoke privileges
+const u64 PRIV_SERVER = 16;          // Can manage the server (e.g. shutodwn
+                                     // ,settings)
+const u64 PRIV_SHOUT = 32;           // Can broadcast chat messages to all
+                                     // players
+
+// Default privileges - these can be overriden for new players using the
+// config option "default_privs" - however, this value still applies for
+// players that existed before the privileges system was added.
+const u64 PRIV_DEFAULT = PRIV_BUILD|PRIV_SHOUT;
+const u64 PRIV_ALL = 0x7FFFFFFFFFFFFFFFULL;
+const u64 PRIV_INVALID = 0x8000000000000000ULL;
+
+// Convert a privileges value into a human-readable string,
+// with each component separated by a comma.
+std::string privsToString(u64 privs);
+
+// Converts a comma-seperated list of privilege values into a
+// privileges value. The reverse of privsToString(). Returns
+// PRIV_INVALID if there is anything wrong with the input.
+u64 stringToPrivs(std::string str);
+
+struct AuthData
+{
+	std::string pwd;
+	u64 privs;
+
+	AuthData():
+		privs(PRIV_DEFAULT)
+	{
+	}
+};
+
+class AuthNotFoundException : public BaseException
+{
+public:
+	AuthNotFoundException(const char *s):
+		BaseException(s)
+	{}
+};
+
+class AuthManager
+{
+public:
+	AuthManager(const std::string &authfilepath);
+	~AuthManager();
+	void load();
+	void save();
+	bool exists(const std::string &username);
+	void set(const std::string &username, AuthData ad);
+	void add(const std::string &username);
+	std::string getPassword(const std::string &username);
+	void setPassword(const std::string &username,
+			const std::string &password);
+	u64 getPrivs(const std::string &username);
+	void setPrivs(const std::string &username, u64 privs);
+	bool isModified();
+private:
+	JMutex m_mutex;
+	std::string m_authfilepath;
+	core::map<std::string, AuthData> m_authdata;
+	bool m_modified;
+};
+
+#endif
+
diff --git a/src/base64.cpp b/src/base64.cpp
index 2a863d161..0dfba5013 100644
--- a/src/base64.cpp
+++ b/src/base64.cpp
@@ -71,9 +71,10 @@ std::string base64_encode(unsigned char const* bytes_to_encode, unsigned int in_
 
     for (j = 0; (j < i + 1); j++)
       ret += base64_chars[char_array_4[j]];
-
-    while((i++ < 3))
-      ret += '=';
+	
+	// Don't pad it with =
+    /*while((i++ < 3))
+      ret += '=';*/
 
   }
 
diff --git a/src/client.cpp b/src/client.cpp
index 5869dc77b..e86b3a4f8 100644
--- a/src/client.cpp
+++ b/src/client.cpp
@@ -39,10 +39,12 @@ void * MeshUpdateThread::Thread()
 		QueuedMeshUpdate *q = m_queue_in.pop();
 		if(q == NULL)
 		{
-			sleep_ms(50);
+			sleep_ms(3);
 			continue;
 		}
 
+		ScopeProfiler sp(&g_profiler, "mesh make");
+
 		scene::SMesh *mesh_new = NULL;
 		mesh_new = makeMapBlockMesh(q->data);
 
@@ -218,12 +220,12 @@ void Client::step(float dtime)
 				g_settings.getFloat("client_delete_unused_sectors_timeout");
 	
 			// Delete sector blocks
-			/*u32 num = m_env.getMap().deleteUnusedSectors
+			/*u32 num = m_env.getMap().unloadUnusedData
 					(delete_unused_sectors_timeout,
 					true, &deleted_blocks);*/
 			
 			// Delete whole sectors
-			u32 num = m_env.getMap().deleteUnusedSectors
+			u32 num = m_env.getMap().unloadUnusedData
 					(delete_unused_sectors_timeout,
 					false, &deleted_blocks);
 
@@ -306,8 +308,14 @@ void Client::step(float dtime)
 			SharedBuffer<u8> data(2+1+PLAYERNAME_SIZE+PASSWORD_SIZE);
 			writeU16(&data[0], TOSERVER_INIT);
 			writeU8(&data[2], SER_FMT_VER_HIGHEST);
+
 			memset((char*)&data[3], 0, PLAYERNAME_SIZE);
 			snprintf((char*)&data[3], PLAYERNAME_SIZE, "%s", myplayer->getName());
+
+			/*dstream<<"Client: password hash is \""<<m_password<<"\""
+					<<std::endl;*/
+
+			memset((char*)&data[23], 0, PASSWORD_SIZE);
 			snprintf((char*)&data[23], PASSWORD_SIZE, "%s", m_password.c_str());
 
 			// Send as unreliable
@@ -610,6 +618,13 @@ void Client::ProcessData(u8 *data, u32 datasize, u16 sender_peer_id)
 		// to be processed even if the serialisation format has
 		// not been agreed yet, the same as TOCLIENT_INIT.
 		m_access_denied = true;
+		m_access_denied_reason = L"Unknown";
+		if(datasize >= 4)
+		{
+			std::string datastring((char*)&data[2], datasize-2);
+			std::istringstream is(datastring, std::ios_base::binary);
+			m_access_denied_reason = deSerializeWideString(is);
+		}
 		return;
 	}
 
@@ -780,7 +795,9 @@ void Client::ProcessData(u8 *data, u32 datasize, u16 sender_peer_id)
 		*/
 
 		//m_env.getClientMap().updateMeshes(block->getPos(), getDayNightRatio());
-		
+		/*
+			Add it to mesh update queue and set it to be acknowledged after update.
+		*/
 		addUpdateMeshTaskWithEdge(p, true);
 	}
 	else if(command == TOCLIENT_PLAYERPOS)
diff --git a/src/client.h b/src/client.h
index f661838ce..a1b1c66b4 100644
--- a/src/client.h
+++ b/src/client.h
@@ -385,6 +385,11 @@ public:
 		return m_access_denied;
 	}
 
+	inline std::wstring accessDeniedReason()
+	{
+		return m_access_denied_reason;
+	}
+
 private:
 	
 	// Virtual methods from con::PeerHandler
@@ -440,10 +445,13 @@ private:
 	
 	std::string m_password;
 	bool m_access_denied;
+	std::wstring m_access_denied_reason;
 
 	InventoryContext m_inventory_context;
 
 	Queue<ClientEvent> m_client_event_queue;
+
+	friend class FarMesh;
 };
 
 #endif // !SERVER
diff --git a/src/clientserver.h b/src/clientserver.h
index 256aed362..7972762c0 100644
--- a/src/clientserver.h
+++ b/src/clientserver.h
@@ -24,6 +24,9 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #define PROTOCOL_ID 0x4f457403
 
+#define PASSWORD_SIZE 28       // Maximum password length. Allows for
+                               // base64-encoded SHA-1 (27+\0).
+
 enum ToClientCommand
 {
 	TOCLIENT_INIT = 0x10,
@@ -154,6 +157,8 @@ enum ToClientCommand
 	TOCLIENT_ACCESS_DENIED = 0x35,
 	/*
 		u16 command
+		u16 reason_length
+		wstring reason
 	*/
 };
 
diff --git a/src/clouds.cpp b/src/clouds.cpp
index 70d19fde5..122beedac 100644
--- a/src/clouds.cpp
+++ b/src/clouds.cpp
@@ -58,8 +58,8 @@ void Clouds::OnRegisterSceneNode()
 {
 	if(IsVisible)
 	{
-		SceneManager->registerNodeForRendering(this, scene::ESNRP_SOLID);
 		//SceneManager->registerNodeForRendering(this, scene::ESNRP_TRANSPARENT);
+		SceneManager->registerNodeForRendering(this, scene::ESNRP_SOLID);
 	}
 
 	ISceneNode::OnRegisterSceneNode();
diff --git a/src/content_craft.cpp b/src/content_craft.cpp
new file mode 100644
index 000000000..069e68300
--- /dev/null
+++ b/src/content_craft.cpp
@@ -0,0 +1,586 @@
+/*
+Minetest-c55
+Copyright (C) 2010-2011 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "content_craft.h"
+#include "inventory.h"
+#include "content_mapnode.h"
+#include "player.h"
+
+/*
+	items: actually *items[9]
+	return value: allocates a new item, or returns NULL.
+*/
+InventoryItem *craft_get_result(InventoryItem **items)
+{
+	// Wood
+	{
+		ItemSpec specs[9];
+		specs[0] = ItemSpec(ITEM_MATERIAL, CONTENT_TREE);
+		if(checkItemCombination(items, specs))
+		{
+			return new MaterialItem(CONTENT_WOOD, 4);
+		}
+	}
+
+	// Stick
+	{
+		ItemSpec specs[9];
+		specs[0] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		if(checkItemCombination(items, specs))
+		{
+			return new CraftItem("Stick", 4);
+		}
+	}
+
+	// Fence
+	{
+		ItemSpec specs[9];
+		specs[3] = ItemSpec(ITEM_CRAFT, "Stick");
+		specs[4] = ItemSpec(ITEM_CRAFT, "Stick");
+		specs[5] = ItemSpec(ITEM_CRAFT, "Stick");
+		specs[6] = ItemSpec(ITEM_CRAFT, "Stick");
+		specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
+		specs[8] = ItemSpec(ITEM_CRAFT, "Stick");
+		if(checkItemCombination(items, specs))
+		{
+			return new MaterialItem(CONTENT_FENCE, 2);
+		}
+	}
+
+	// Sign
+	{
+		ItemSpec specs[9];
+		specs[0] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		specs[1] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		specs[2] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		specs[3] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		specs[4] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		specs[5] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
+		if(checkItemCombination(items, specs))
+		{
+			//return new MapBlockObjectItem("Sign");
+			return new MaterialItem(CONTENT_SIGN_WALL, 1);
+		}
+	}
+
+	// Torch
+	{
+		ItemSpec specs[9];
+		specs[0] = ItemSpec(ITEM_CRAFT, "lump_of_coal");
+		specs[3] = ItemSpec(ITEM_CRAFT, "Stick");
+		if(checkItemCombination(items, specs))
+		{
+			return new MaterialItem(CONTENT_TORCH, 4);
+		}
+	}
+
+	// Wooden pick
+	{
+		ItemSpec specs[9];
+		specs[0] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		specs[1] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		specs[2] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		specs[4] = ItemSpec(ITEM_CRAFT, "Stick");
+		specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
+		if(checkItemCombination(items, specs))
+		{
+			return new ToolItem("WPick", 0);
+		}
+	}
+
+	// Stone pick
+	{
+		ItemSpec specs[9];
+		specs[0] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
+		specs[1] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
+		specs[2] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
+		specs[4] = ItemSpec(ITEM_CRAFT, "Stick");
+		specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
+		if(checkItemCombination(items, specs))
+		{
+			return new ToolItem("STPick", 0);
+		}
+	}
+
+	// Steel pick
+	{
+		ItemSpec specs[9];
+		specs[0] = ItemSpec(ITEM_CRAFT, "steel_ingot");
+		specs[1] = ItemSpec(ITEM_CRAFT, "steel_ingot");
+		specs[2] = ItemSpec(ITEM_CRAFT, "steel_ingot");
+		specs[4] = ItemSpec(ITEM_CRAFT, "Stick");
+		specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
+		if(checkItemCombination(items, specs))
+		{
+			return new ToolItem("SteelPick", 0);
+		}
+	}
+
+	// Mese pick
+	{
+		ItemSpec specs[9];
+		specs[0] = ItemSpec(ITEM_MATERIAL, CONTENT_MESE);
+		specs[1] = ItemSpec(ITEM_MATERIAL, CONTENT_MESE);
+		specs[2] = ItemSpec(ITEM_MATERIAL, CONTENT_MESE);
+		specs[4] = ItemSpec(ITEM_CRAFT, "Stick");
+		specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
+		if(checkItemCombination(items, specs))
+		{
+			return new ToolItem("MesePick", 0);
+		}
+	}
+
+	// Wooden shovel
+	{
+		ItemSpec specs[9];
+		specs[1] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		specs[4] = ItemSpec(ITEM_CRAFT, "Stick");
+		specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
+		if(checkItemCombination(items, specs))
+		{
+			return new ToolItem("WShovel", 0);
+		}
+	}
+
+	// Stone shovel
+	{
+		ItemSpec specs[9];
+		specs[1] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
+		specs[4] = ItemSpec(ITEM_CRAFT, "Stick");
+		specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
+		if(checkItemCombination(items, specs))
+		{
+			return new ToolItem("STShovel", 0);
+		}
+	}
+
+	// Steel shovel
+	{
+		ItemSpec specs[9];
+		specs[1] = ItemSpec(ITEM_CRAFT, "steel_ingot");
+		specs[4] = ItemSpec(ITEM_CRAFT, "Stick");
+		specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
+		if(checkItemCombination(items, specs))
+		{
+			return new ToolItem("SteelShovel", 0);
+		}
+	}
+
+	// Wooden axe
+	{
+		ItemSpec specs[9];
+		specs[0] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		specs[1] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		specs[3] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		specs[4] = ItemSpec(ITEM_CRAFT, "Stick");
+		specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
+		if(checkItemCombination(items, specs))
+		{
+			return new ToolItem("WAxe", 0);
+		}
+	}
+
+	// Stone axe
+	{
+		ItemSpec specs[9];
+		specs[0] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
+		specs[1] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
+		specs[3] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
+		specs[4] = ItemSpec(ITEM_CRAFT, "Stick");
+		specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
+		if(checkItemCombination(items, specs))
+		{
+			return new ToolItem("STAxe", 0);
+		}
+	}
+
+	// Steel axe
+	{
+		ItemSpec specs[9];
+		specs[0] = ItemSpec(ITEM_CRAFT, "steel_ingot");
+		specs[1] = ItemSpec(ITEM_CRAFT, "steel_ingot");
+		specs[3] = ItemSpec(ITEM_CRAFT, "steel_ingot");
+		specs[4] = ItemSpec(ITEM_CRAFT, "Stick");
+		specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
+		if(checkItemCombination(items, specs))
+		{
+			return new ToolItem("SteelAxe", 0);
+		}
+	}
+
+	// Wooden sword
+	{
+		ItemSpec specs[9];
+		specs[1] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		specs[4] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
+		if(checkItemCombination(items, specs))
+		{
+			return new ToolItem("WSword", 0);
+		}
+	}
+
+	// Stone sword
+	{
+		ItemSpec specs[9];
+		specs[1] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
+		specs[4] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
+		specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
+		if(checkItemCombination(items, specs))
+		{
+			return new ToolItem("STSword", 0);
+		}
+	}
+
+	// Steel sword
+	{
+		ItemSpec specs[9];
+		specs[1] = ItemSpec(ITEM_CRAFT, "steel_ingot");
+		specs[4] = ItemSpec(ITEM_CRAFT, "steel_ingot");
+		specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
+		if(checkItemCombination(items, specs))
+		{
+			return new ToolItem("SteelSword", 0);
+		}
+	}
+
+	// Rail
+	{
+		ItemSpec specs[9];
+		specs[0] = ItemSpec(ITEM_CRAFT, "steel_ingot");
+		specs[1] = ItemSpec(ITEM_CRAFT, "Stick");
+		specs[2] = ItemSpec(ITEM_CRAFT, "steel_ingot");
+		specs[3] = ItemSpec(ITEM_CRAFT, "steel_ingot");
+		specs[4] = ItemSpec(ITEM_CRAFT, "Stick");
+		specs[5] = ItemSpec(ITEM_CRAFT, "steel_ingot");
+		specs[6] = ItemSpec(ITEM_CRAFT, "steel_ingot");
+		specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
+		specs[8] = ItemSpec(ITEM_CRAFT, "steel_ingot");
+		if(checkItemCombination(items, specs))
+		{
+			return new MaterialItem(CONTENT_RAIL, 15);
+		}
+	}
+
+	// Chest
+	{
+		ItemSpec specs[9];
+		specs[0] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		specs[1] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		specs[2] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		specs[3] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		specs[5] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		specs[6] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		specs[7] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		specs[8] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		if(checkItemCombination(items, specs))
+		{
+			return new MaterialItem(CONTENT_CHEST, 1);
+		}
+	}
+
+	// Furnace
+	{
+		ItemSpec specs[9];
+		specs[0] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
+		specs[1] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
+		specs[2] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
+		specs[3] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
+		specs[5] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
+		specs[6] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
+		specs[7] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
+		specs[8] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
+		if(checkItemCombination(items, specs))
+		{
+			return new MaterialItem(CONTENT_FURNACE, 1);
+		}
+	}
+
+	// Steel block
+	{
+		ItemSpec specs[9];
+		specs[0] = ItemSpec(ITEM_CRAFT, "steel_ingot");
+		specs[1] = ItemSpec(ITEM_CRAFT, "steel_ingot");
+		specs[2] = ItemSpec(ITEM_CRAFT, "steel_ingot");
+		specs[3] = ItemSpec(ITEM_CRAFT, "steel_ingot");
+		specs[4] = ItemSpec(ITEM_CRAFT, "steel_ingot");
+		specs[5] = ItemSpec(ITEM_CRAFT, "steel_ingot");
+		specs[6] = ItemSpec(ITEM_CRAFT, "steel_ingot");
+		specs[7] = ItemSpec(ITEM_CRAFT, "steel_ingot");
+		specs[8] = ItemSpec(ITEM_CRAFT, "steel_ingot");
+		if(checkItemCombination(items, specs))
+		{
+			return new MaterialItem(CONTENT_STEEL, 1);
+		}
+	}
+
+	// Sandstone
+	{
+		ItemSpec specs[9];
+		specs[3] = ItemSpec(ITEM_MATERIAL, CONTENT_SAND);
+		specs[4] = ItemSpec(ITEM_MATERIAL, CONTENT_SAND);
+		specs[6] = ItemSpec(ITEM_MATERIAL, CONTENT_SAND);
+		specs[7] = ItemSpec(ITEM_MATERIAL, CONTENT_SAND);
+		if(checkItemCombination(items, specs))
+		{
+			return new MaterialItem(CONTENT_SANDSTONE, 1);
+		}
+	}
+
+	// Clay
+	{
+		ItemSpec specs[9];
+		specs[3] = ItemSpec(ITEM_CRAFT, "lump_of_clay");
+		specs[4] = ItemSpec(ITEM_CRAFT, "lump_of_clay");
+		specs[6] = ItemSpec(ITEM_CRAFT, "lump_of_clay");
+		specs[7] = ItemSpec(ITEM_CRAFT, "lump_of_clay");
+		if(checkItemCombination(items, specs))
+		{
+			return new MaterialItem(CONTENT_CLAY, 1);
+		}
+	}
+
+	// Brick
+	{
+		ItemSpec specs[9];
+		specs[3] = ItemSpec(ITEM_CRAFT, "clay_brick");
+		specs[4] = ItemSpec(ITEM_CRAFT, "clay_brick");
+		specs[6] = ItemSpec(ITEM_CRAFT, "clay_brick");
+		specs[7] = ItemSpec(ITEM_CRAFT, "clay_brick");
+		if(checkItemCombination(items, specs))
+		{
+			return new MaterialItem(CONTENT_BRICK, 1);
+		}
+	}
+
+	// Paper
+	{
+		ItemSpec specs[9];
+		specs[3] = ItemSpec(ITEM_MATERIAL, CONTENT_PAPYRUS);
+		specs[4] = ItemSpec(ITEM_MATERIAL, CONTENT_PAPYRUS);
+		specs[5] = ItemSpec(ITEM_MATERIAL, CONTENT_PAPYRUS);
+		if(checkItemCombination(items, specs))
+		{
+			return new CraftItem("paper", 1);
+		}
+	}
+
+	// Book
+	{
+		ItemSpec specs[9];
+		specs[1] = ItemSpec(ITEM_CRAFT, "paper");
+		specs[4] = ItemSpec(ITEM_CRAFT, "paper");
+		specs[7] = ItemSpec(ITEM_CRAFT, "paper");
+		if(checkItemCombination(items, specs))
+		{
+			return new CraftItem("book", 1);
+		}
+	}
+
+	// Book shelf
+	{
+		ItemSpec specs[9];
+		specs[0] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		specs[1] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		specs[2] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		specs[3] = ItemSpec(ITEM_CRAFT, "book");
+		specs[4] = ItemSpec(ITEM_CRAFT, "book");
+		specs[5] = ItemSpec(ITEM_CRAFT, "book");
+		specs[6] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		specs[7] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		specs[8] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
+		if(checkItemCombination(items, specs))
+		{
+			return new MaterialItem(CONTENT_BOOKSHELF, 1);
+		}
+	}
+
+	return NULL;
+}
+
+void craft_set_creative_inventory(Player *player)
+{
+	player->resetInventory();
+	
+	// Give some good tools
+	{
+		InventoryItem *item = new ToolItem("MesePick", 0);
+		void* r = player->inventory.addItem("main", item);
+		assert(r == NULL);
+	}
+	{
+		InventoryItem *item = new ToolItem("SteelPick", 0);
+		void* r = player->inventory.addItem("main", item);
+		assert(r == NULL);
+	}
+	{
+		InventoryItem *item = new ToolItem("SteelAxe", 0);
+		void* r = player->inventory.addItem("main", item);
+		assert(r == NULL);
+	}
+	{
+		InventoryItem *item = new ToolItem("SteelShovel", 0);
+		void* r = player->inventory.addItem("main", item);
+		assert(r == NULL);
+	}
+
+	/*
+		Give materials
+	*/
+	
+	// CONTENT_IGNORE-terminated list
+	u8 material_items[] = {
+		CONTENT_TORCH,
+		CONTENT_COBBLE,
+		CONTENT_MUD,
+		CONTENT_STONE,
+		CONTENT_SAND,
+		CONTENT_SANDSTONE,
+		CONTENT_CLAY,
+		CONTENT_BRICK,
+		CONTENT_TREE,
+		CONTENT_LEAVES,
+		CONTENT_CACTUS,
+		CONTENT_PAPYRUS,
+		CONTENT_BOOKSHELF,
+		CONTENT_GLASS,
+		CONTENT_FENCE,
+		CONTENT_RAIL,
+		CONTENT_MESE,
+		CONTENT_WATERSOURCE,
+		CONTENT_CLOUD,
+		CONTENT_CHEST,
+		CONTENT_FURNACE,
+		CONTENT_SIGN_WALL,
+		CONTENT_IGNORE
+	};
+	
+	u8 *mip = material_items;
+	for(u16 i=0; i<PLAYER_INVENTORY_SIZE; i++)
+	{
+		if(*mip == CONTENT_IGNORE)
+			break;
+
+		InventoryItem *item = new MaterialItem(*mip, 1);
+		player->inventory.addItem("main", item);
+
+		mip++;
+	}
+
+#if 0
+	assert(USEFUL_CONTENT_COUNT <= PLAYER_INVENTORY_SIZE);
+	
+	// add torch first
+	InventoryItem *item = new MaterialItem(CONTENT_TORCH, 1);
+	player->inventory.addItem("main", item);
+	
+	// Then others
+	for(u16 i=0; i<USEFUL_CONTENT_COUNT; i++)
+	{
+		// Skip some materials
+		if(i == CONTENT_WATER || i == CONTENT_TORCH
+			|| i == CONTENT_COALSTONE)
+			continue;
+
+		InventoryItem *item = new MaterialItem(i, 1);
+		player->inventory.addItem("main", item);
+	}
+#endif
+
+	/*// Sign
+	{
+		InventoryItem *item = new MapBlockObjectItem("Sign Example text");
+		void* r = player->inventory.addItem("main", item);
+		assert(r == NULL);
+	}*/
+}
+
+void craft_give_initial_stuff(Player *player)
+{
+	{
+		InventoryItem *item = new ToolItem("SteelPick", 0);
+		void* r = player->inventory.addItem("main", item);
+		assert(r == NULL);
+	}
+	{
+		InventoryItem *item = new MaterialItem(CONTENT_TORCH, 99);
+		void* r = player->inventory.addItem("main", item);
+		assert(r == NULL);
+	}
+	{
+		InventoryItem *item = new ToolItem("SteelAxe", 0);
+		void* r = player->inventory.addItem("main", item);
+		assert(r == NULL);
+	}
+	{
+		InventoryItem *item = new ToolItem("SteelShovel", 0);
+		void* r = player->inventory.addItem("main", item);
+		assert(r == NULL);
+	}
+	{
+		InventoryItem *item = new MaterialItem(CONTENT_COBBLE, 99);
+		void* r = player->inventory.addItem("main", item);
+		assert(r == NULL);
+	}
+	/*{
+		InventoryItem *item = new MaterialItem(CONTENT_MESE, 6);
+		void* r = player->inventory.addItem("main", item);
+		assert(r == NULL);
+	}
+	{
+		InventoryItem *item = new MaterialItem(CONTENT_COALSTONE, 6);
+		void* r = player->inventory.addItem("main", item);
+		assert(r == NULL);
+	}
+	{
+		InventoryItem *item = new MaterialItem(CONTENT_WOOD, 6);
+		void* r = player->inventory.addItem("main", item);
+		assert(r == NULL);
+	}
+	{
+		InventoryItem *item = new CraftItem("Stick", 4);
+		void* r = player->inventory.addItem("main", item);
+		assert(r == NULL);
+	}
+	{
+		InventoryItem *item = new ToolItem("WPick", 32000);
+		void* r = player->inventory.addItem("main", item);
+		assert(r == NULL);
+	}
+	{
+		InventoryItem *item = new ToolItem("STPick", 32000);
+		void* r = player->inventory.addItem("main", item);
+		assert(r == NULL);
+	}*/
+	/*// and some signs
+	for(u16 i=0; i<4; i++)
+	{
+		InventoryItem *item = new MapBlockObjectItem("Sign Example text");
+		bool r = player->inventory.addItem("main", item);
+		assert(r == true);
+	}*/
+	/*// Give some other stuff
+	{
+		InventoryItem *item = new MaterialItem(CONTENT_TREE, 999);
+		bool r = player->inventory.addItem("main", item);
+		assert(r == true);
+	}*/
+}
+
diff --git a/src/content_craft.h b/src/content_craft.h
new file mode 100644
index 000000000..7a8b4659a
--- /dev/null
+++ b/src/content_craft.h
@@ -0,0 +1,38 @@
+/*
+Minetest-c55
+Copyright (C) 2010-2011 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#ifndef CONTENT_CRAFT_HEADER
+#define CONTENT_CRAFT_HEADER
+
+class InventoryItem;
+class Player;
+
+/*
+	items: actually *items[9]
+	return value: allocates a new item, or returns NULL.
+*/
+InventoryItem *craft_get_result(InventoryItem **items);
+
+void craft_set_creative_inventory(Player *player);
+
+// Called when give_initial_stuff setting is used
+void craft_give_initial_stuff(Player *player);
+
+#endif
+
diff --git a/src/content_inventory.cpp b/src/content_inventory.cpp
new file mode 100644
index 000000000..357c8ef26
--- /dev/null
+++ b/src/content_inventory.cpp
@@ -0,0 +1,108 @@
+/*
+Minetest-c55
+Copyright (C) 2010-2011 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "content_inventory.h"
+#include "inventory.h"
+#include "serverobject.h"
+#include "content_mapnode.h"
+
+bool item_material_is_cookable(u8 content)
+{
+	if(content == CONTENT_TREE)
+		return true;
+	else if(content == CONTENT_COBBLE)
+		return true;
+	else if(content == CONTENT_SAND)
+		return true;
+	return false;
+}
+
+InventoryItem* item_material_create_cook_result(u8 content)
+{
+	if(content == CONTENT_TREE)
+		return new CraftItem("lump_of_coal", 1);
+	else if(content == CONTENT_COBBLE)
+		return new MaterialItem(CONTENT_STONE, 1);
+	else if(content == CONTENT_SAND)
+		return new MaterialItem(CONTENT_GLASS, 1);
+	return NULL;
+}
+
+std::string item_craft_get_image_name(const std::string &subname)
+{
+	if(subname == "Stick")
+		return "stick.png";
+	else if(subname == "paper")
+		return "paper.png";
+	else if(subname == "book")
+		return "book.png";
+	else if(subname == "lump_of_coal")
+		return "lump_of_coal.png";
+	else if(subname == "lump_of_iron")
+		return "lump_of_iron.png";
+	else if(subname == "lump_of_clay")
+		return "lump_of_clay.png";
+	else if(subname == "steel_ingot")
+		return "steel_ingot.png";
+	else if(subname == "clay_brick")
+		return "clay_brick.png";
+	else if(subname == "rat")
+		return "rat.png";
+	else
+		return "cloud.png"; // just something
+}
+
+ServerActiveObject* item_craft_create_object(const std::string &subname,
+		ServerEnvironment *env, u16 id, v3f pos)
+{
+	if(subname == "rat")
+	{
+		ServerActiveObject *obj = new RatSAO(env, id, pos);
+		return obj;
+	}
+
+	return NULL;
+}
+
+s16 item_craft_get_drop_count(const std::string &subname)
+{
+	if(subname == "rat")
+		return 1;
+
+	return -1;
+}
+
+bool item_craft_is_cookable(const std::string &subname)
+{
+	if(subname == "lump_of_iron" || subname == "lump_of_clay")
+		return true;
+		
+	return false;
+}
+
+InventoryItem* item_craft_create_cook_result(const std::string &subname)
+{
+	if(subname == "lump_of_iron")
+		return new CraftItem("steel_ingot", 1);
+	else if(subname == "lump_of_clay")
+		return new CraftItem("clay_brick", 1);
+
+	return NULL;
+}
+
diff --git a/src/content_inventory.h b/src/content_inventory.h
new file mode 100644
index 000000000..54aa2151a
--- /dev/null
+++ b/src/content_inventory.h
@@ -0,0 +1,41 @@
+/*
+Minetest-c55
+Copyright (C) 2010-2011 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#ifndef CONTENT_INVENTORY_HEADER
+#define CONTENT_INVENTORY_HEADER
+
+#include "common_irrlicht.h" // For u8, s16
+#include <string>
+
+class InventoryItem;
+class ServerActiveObject;
+class ServerEnvironment;
+
+bool           item_material_is_cookable(u8 content);
+InventoryItem* item_material_create_cook_result(u8 content);
+
+std::string         item_craft_get_image_name(const std::string &subname);
+ServerActiveObject* item_craft_create_object(const std::string &subname,
+		ServerEnvironment *env, u16 id, v3f pos);
+s16                 item_craft_get_drop_count(const std::string &subname);
+bool                item_craft_is_cookable(const std::string &subname);
+InventoryItem*      item_craft_create_cook_result(const std::string &subname);
+
+#endif
+
diff --git a/src/content_mapblock.cpp b/src/content_mapblock.cpp
new file mode 100644
index 000000000..9ef0599d1
--- /dev/null
+++ b/src/content_mapblock.cpp
@@ -0,0 +1,1076 @@
+/*
+Minetest-c55
+Copyright (C) 2010-2011 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "content_mapblock.h"
+#include "content_mapnode.h"
+#include "main.h" // For g_settings and g_texturesource
+#include "mineral.h"
+
+#ifndef SERVER
+// Create a cuboid.
+//  material  - the material to use (for all 6 faces)
+//  collector - the MeshCollector for the resulting polygons
+//  pa        - texture atlas pointer for the material
+//  c         - vertex colour - used for all
+//  pos       - the position of the centre of the cuboid
+//  rz,ry,rz  - the radius of the cuboid in each dimension
+//  txc       - texture coordinates - this is a list of texture coordinates
+//              for the opposite corners of each face - therefore, there
+//              should be (2+2)*6=24 values in the list. Alternatively, pass
+//              NULL to use the entire texture for each face. The order of
+//              the faces in the list is top-backi-right-front-left-bottom
+//              If you specified 0,0,1,1 for each face, that would be the
+//              same as passing NULL.
+void makeCuboid(video::SMaterial &material, MeshCollector *collector,
+	AtlasPointer* pa, video::SColor &c,
+	v3f &pos, f32 rx, f32 ry, f32 rz, f32* txc)
+{
+	f32 tu0=pa->x0();
+	f32 tu1=pa->x1();
+	f32 tv0=pa->y0();
+	f32 tv1=pa->y1();
+	f32 txus=tu1-tu0;
+	f32 txvs=tv1-tv0;
+
+	video::S3DVertex v[4] =
+	{
+		video::S3DVertex(0,0,0, 0,0,0, c, tu0, tv1),
+		video::S3DVertex(0,0,0, 0,0,0, c, tu1, tv1),
+		video::S3DVertex(0,0,0, 0,0,0, c, tu1, tv0),
+		video::S3DVertex(0,0,0, 0,0,0, c, tu0, tv0)
+	};
+
+	for(int i=0;i<6;i++)
+	{
+		switch(i)
+		{
+			case 0:	// top
+				v[0].Pos.X=-rx; v[0].Pos.Y= ry; v[0].Pos.Z=-rz;
+				v[1].Pos.X=-rx; v[1].Pos.Y= ry; v[1].Pos.Z= rz;
+				v[2].Pos.X= rx; v[2].Pos.Y= ry; v[2].Pos.Z= rz;
+				v[3].Pos.X= rx; v[3].Pos.Y= ry, v[3].Pos.Z=-rz;
+				break;
+			case 1: // back
+				v[0].Pos.X=-rx; v[0].Pos.Y= ry; v[0].Pos.Z=-rz;
+				v[1].Pos.X= rx; v[1].Pos.Y= ry; v[1].Pos.Z=-rz;
+				v[2].Pos.X= rx; v[2].Pos.Y=-ry; v[2].Pos.Z=-rz;
+				v[3].Pos.X=-rx; v[3].Pos.Y=-ry, v[3].Pos.Z=-rz;
+				break;
+			case 2: //right
+				v[0].Pos.X= rx; v[0].Pos.Y= ry; v[0].Pos.Z=-rz;
+				v[1].Pos.X= rx; v[1].Pos.Y= ry; v[1].Pos.Z= rz;
+				v[2].Pos.X= rx; v[2].Pos.Y=-ry; v[2].Pos.Z= rz;
+				v[3].Pos.X= rx; v[3].Pos.Y=-ry, v[3].Pos.Z=-rz;
+				break;
+			case 3: // front
+				v[0].Pos.X= rx; v[0].Pos.Y= ry; v[0].Pos.Z= rz;
+				v[1].Pos.X=-rx; v[1].Pos.Y= ry; v[1].Pos.Z= rz;
+				v[2].Pos.X=-rx; v[2].Pos.Y=-ry; v[2].Pos.Z= rz;
+				v[3].Pos.X= rx; v[3].Pos.Y=-ry, v[3].Pos.Z= rz;
+				break;
+			case 4: // left
+				v[0].Pos.X=-rx; v[0].Pos.Y= ry; v[0].Pos.Z= rz;
+				v[1].Pos.X=-rx; v[1].Pos.Y= ry; v[1].Pos.Z=-rz;
+				v[2].Pos.X=-rx; v[2].Pos.Y=-ry; v[2].Pos.Z=-rz;
+				v[3].Pos.X=-rx; v[3].Pos.Y=-ry, v[3].Pos.Z= rz;
+				break;
+			case 5: // bottom
+				v[0].Pos.X= rx; v[0].Pos.Y=-ry; v[0].Pos.Z= rz;
+				v[1].Pos.X=-rx; v[1].Pos.Y=-ry; v[1].Pos.Z= rz;
+				v[2].Pos.X=-rx; v[2].Pos.Y=-ry; v[2].Pos.Z=-rz;
+				v[3].Pos.X= rx; v[3].Pos.Y=-ry, v[3].Pos.Z=-rz;
+				break;
+		}
+
+		if(txc!=NULL)
+		{
+			v[0].TCoords.X=tu0+txus*txc[0]; v[0].TCoords.Y=tv0+txvs*txc[3];
+			v[1].TCoords.X=tu0+txus*txc[2]; v[1].TCoords.Y=tv0+txvs*txc[3];
+			v[2].TCoords.X=tu0+txus*txc[2]; v[2].TCoords.Y=tv0+txvs*txc[1];
+			v[3].TCoords.X=tu0+txus*txc[0]; v[3].TCoords.Y=tv0+txvs*txc[1];
+			txc+=4;
+		}
+
+		for(u16 i=0; i<4; i++)
+			v[i].Pos += pos;
+		u16 indices[] = {0,1,2,2,3,0};
+		collector->append(material, v, 4, indices, 6);
+
+	}
+
+}
+#endif
+
+#ifndef SERVER
+void mapblock_mesh_generate_special(MeshMakeData *data,
+		MeshCollector &collector)
+{
+	// 0ms
+	//TimeTaker timer("mapblock_mesh_generate_special()");
+
+	/*
+		Some settings
+	*/
+	bool new_style_water = g_settings.getBool("new_style_water");
+	bool new_style_leaves = g_settings.getBool("new_style_leaves");
+	//bool smooth_lighting = g_settings.getBool("smooth_lighting");
+	bool invisible_stone = g_settings.getBool("invisible_stone");
+	
+	float node_water_level = 1.0;
+	if(new_style_water)
+		node_water_level = 0.85;
+	
+	v3s16 blockpos_nodes = data->m_blockpos*MAP_BLOCKSIZE;
+
+	// Flowing water material
+	video::SMaterial material_water1;
+	material_water1.setFlag(video::EMF_LIGHTING, false);
+	material_water1.setFlag(video::EMF_BACK_FACE_CULLING, false);
+	material_water1.setFlag(video::EMF_BILINEAR_FILTER, false);
+	material_water1.setFlag(video::EMF_FOG_ENABLE, true);
+	material_water1.MaterialType = video::EMT_TRANSPARENT_VERTEX_ALPHA;
+	AtlasPointer pa_water1 = g_texturesource->getTexture(
+			g_texturesource->getTextureId("water.png"));
+	material_water1.setTexture(0, pa_water1.atlas);
+
+	// New-style leaves material
+	video::SMaterial material_leaves1;
+	material_leaves1.setFlag(video::EMF_LIGHTING, false);
+	//material_leaves1.setFlag(video::EMF_BACK_FACE_CULLING, false);
+	material_leaves1.setFlag(video::EMF_BILINEAR_FILTER, false);
+	material_leaves1.setFlag(video::EMF_FOG_ENABLE, true);
+	material_leaves1.MaterialType = video::EMT_TRANSPARENT_ALPHA_CHANNEL_REF;
+	AtlasPointer pa_leaves1 = g_texturesource->getTexture(
+			g_texturesource->getTextureId("leaves.png"));
+	material_leaves1.setTexture(0, pa_leaves1.atlas);
+
+	// Glass material
+	video::SMaterial material_glass;
+	material_glass.setFlag(video::EMF_LIGHTING, false);
+	material_glass.setFlag(video::EMF_BILINEAR_FILTER, false);
+	material_glass.setFlag(video::EMF_FOG_ENABLE, true);
+	material_glass.MaterialType = video::EMT_TRANSPARENT_ALPHA_CHANNEL_REF;
+	AtlasPointer pa_glass = g_texturesource->getTexture(
+			g_texturesource->getTextureId("glass.png"));
+	material_glass.setTexture(0, pa_glass.atlas);
+
+	// Wood material
+	video::SMaterial material_wood;
+	material_wood.setFlag(video::EMF_LIGHTING, false);
+	material_wood.setFlag(video::EMF_BILINEAR_FILTER, false);
+	material_wood.setFlag(video::EMF_FOG_ENABLE, true);
+	material_wood.MaterialType = video::EMT_TRANSPARENT_ALPHA_CHANNEL_REF;
+	AtlasPointer pa_wood = g_texturesource->getTexture(
+			g_texturesource->getTextureId("wood.png"));
+	material_wood.setTexture(0, pa_wood.atlas);
+
+	// General ground material for special output
+	// Texture is modified just before usage
+	video::SMaterial material_general;
+	material_general.setFlag(video::EMF_LIGHTING, false);
+	material_general.setFlag(video::EMF_BILINEAR_FILTER, false);
+	material_general.setFlag(video::EMF_FOG_ENABLE, true);
+	material_general.MaterialType = video::EMT_TRANSPARENT_ALPHA_CHANNEL_REF;
+
+
+	// Papyrus material
+	video::SMaterial material_papyrus;
+	material_papyrus.setFlag(video::EMF_LIGHTING, false);
+	material_papyrus.setFlag(video::EMF_BILINEAR_FILTER, false);
+	material_papyrus.setFlag(video::EMF_FOG_ENABLE, true);
+	material_papyrus.MaterialType = video::EMT_TRANSPARENT_ALPHA_CHANNEL_REF;
+	AtlasPointer pa_papyrus = g_texturesource->getTexture(
+			g_texturesource->getTextureId("papyrus.png"));
+	material_papyrus.setTexture(0, pa_papyrus.atlas);
+	for(s16 z=0; z<MAP_BLOCKSIZE; z++)
+	for(s16 y=0; y<MAP_BLOCKSIZE; y++)
+	for(s16 x=0; x<MAP_BLOCKSIZE; x++)
+	{
+		v3s16 p(x,y,z);
+
+		MapNode n = data->m_vmanip.getNodeNoEx(blockpos_nodes+p);
+		
+		/*
+			Add torches to mesh
+		*/
+		if(n.d == CONTENT_TORCH)
+		{
+			video::SColor c(255,255,255,255);
+
+			// Wall at X+ of node
+			video::S3DVertex vertices[4] =
+			{
+				video::S3DVertex(-BS/2,-BS/2,0, 0,0,0, c, 0,1),
+				video::S3DVertex(BS/2,-BS/2,0, 0,0,0, c, 1,1),
+				video::S3DVertex(BS/2,BS/2,0, 0,0,0, c, 1,0),
+				video::S3DVertex(-BS/2,BS/2,0, 0,0,0, c, 0,0),
+			};
+
+			v3s16 dir = unpackDir(n.dir);
+
+			for(s32 i=0; i<4; i++)
+			{
+				if(dir == v3s16(1,0,0))
+					vertices[i].Pos.rotateXZBy(0);
+				if(dir == v3s16(-1,0,0))
+					vertices[i].Pos.rotateXZBy(180);
+				if(dir == v3s16(0,0,1))
+					vertices[i].Pos.rotateXZBy(90);
+				if(dir == v3s16(0,0,-1))
+					vertices[i].Pos.rotateXZBy(-90);
+				if(dir == v3s16(0,-1,0))
+					vertices[i].Pos.rotateXZBy(45);
+				if(dir == v3s16(0,1,0))
+					vertices[i].Pos.rotateXZBy(-45);
+
+				vertices[i].Pos += intToFloat(p + blockpos_nodes, BS);
+			}
+
+			// Set material
+			video::SMaterial material;
+			material.setFlag(video::EMF_LIGHTING, false);
+			material.setFlag(video::EMF_BACK_FACE_CULLING, false);
+			material.setFlag(video::EMF_BILINEAR_FILTER, false);
+			//material.MaterialType = video::EMT_TRANSPARENT_ALPHA_CHANNEL;
+			material.MaterialType
+					= video::EMT_TRANSPARENT_ALPHA_CHANNEL_REF;
+
+			if(dir == v3s16(0,-1,0))
+				material.setTexture(0,
+						g_texturesource->getTextureRaw("torch_on_floor.png"));
+			else if(dir == v3s16(0,1,0))
+				material.setTexture(0,
+						g_texturesource->getTextureRaw("torch_on_ceiling.png"));
+			// For backwards compatibility
+			else if(dir == v3s16(0,0,0))
+				material.setTexture(0,
+						g_texturesource->getTextureRaw("torch_on_floor.png"));
+			else
+				material.setTexture(0, 
+						g_texturesource->getTextureRaw("torch.png"));
+
+			u16 indices[] = {0,1,2,2,3,0};
+			// Add to mesh collector
+			collector.append(material, vertices, 4, indices, 6);
+		}
+		/*
+			Signs on walls
+		*/
+		if(n.d == CONTENT_SIGN_WALL)
+		{
+			u8 l = decode_light(n.getLightBlend(data->m_daynight_ratio));
+			video::SColor c(255,l,l,l);
+				
+			float d = (float)BS/16;
+			// Wall at X+ of node
+			video::S3DVertex vertices[4] =
+			{
+				video::S3DVertex(BS/2-d,-BS/2,-BS/2, 0,0,0, c, 0,1),
+				video::S3DVertex(BS/2-d,-BS/2,BS/2, 0,0,0, c, 1,1),
+				video::S3DVertex(BS/2-d,BS/2,BS/2, 0,0,0, c, 1,0),
+				video::S3DVertex(BS/2-d,BS/2,-BS/2, 0,0,0, c, 0,0),
+			};
+
+			v3s16 dir = unpackDir(n.dir);
+
+			for(s32 i=0; i<4; i++)
+			{
+				if(dir == v3s16(1,0,0))
+					vertices[i].Pos.rotateXZBy(0);
+				if(dir == v3s16(-1,0,0))
+					vertices[i].Pos.rotateXZBy(180);
+				if(dir == v3s16(0,0,1))
+					vertices[i].Pos.rotateXZBy(90);
+				if(dir == v3s16(0,0,-1))
+					vertices[i].Pos.rotateXZBy(-90);
+				if(dir == v3s16(0,-1,0))
+					vertices[i].Pos.rotateXYBy(-90);
+				if(dir == v3s16(0,1,0))
+					vertices[i].Pos.rotateXYBy(90);
+
+				vertices[i].Pos += intToFloat(p + blockpos_nodes, BS);
+			}
+
+			// Set material
+			video::SMaterial material;
+			material.setFlag(video::EMF_LIGHTING, false);
+			material.setFlag(video::EMF_BACK_FACE_CULLING, false);
+			material.setFlag(video::EMF_BILINEAR_FILTER, false);
+			material.setFlag(video::EMF_FOG_ENABLE, true);
+			//material.MaterialType = video::EMT_TRANSPARENT_ALPHA_CHANNEL;
+			material.MaterialType
+					= video::EMT_TRANSPARENT_ALPHA_CHANNEL_REF;
+
+			material.setTexture(0, 
+					g_texturesource->getTextureRaw("sign_wall.png"));
+
+			u16 indices[] = {0,1,2,2,3,0};
+			// Add to mesh collector
+			collector.append(material, vertices, 4, indices, 6);
+		}
+		/*
+			Add flowing water to mesh
+		*/
+		else if(n.d == CONTENT_WATER)
+		{
+			bool top_is_water = false;
+			MapNode ntop = data->m_vmanip.getNodeNoEx(blockpos_nodes + v3s16(x,y+1,z));
+			if(ntop.d == CONTENT_WATER || ntop.d == CONTENT_WATERSOURCE)
+				top_is_water = true;
+			
+			u8 l = 0;
+			// Use the light of the node on top if possible
+			if(content_features(ntop.d).param_type == CPT_LIGHT)
+				l = decode_light(ntop.getLightBlend(data->m_daynight_ratio));
+			// Otherwise use the light of this node (the water)
+			else
+				l = decode_light(n.getLightBlend(data->m_daynight_ratio));
+			video::SColor c(WATER_ALPHA,l,l,l);
+			
+			// Neighbor water levels (key = relative position)
+			// Includes current node
+			core::map<v3s16, f32> neighbor_levels;
+			core::map<v3s16, u8> neighbor_contents;
+			core::map<v3s16, u8> neighbor_flags;
+			const u8 neighborflag_top_is_water = 0x01;
+			v3s16 neighbor_dirs[9] = {
+				v3s16(0,0,0),
+				v3s16(0,0,1),
+				v3s16(0,0,-1),
+				v3s16(1,0,0),
+				v3s16(-1,0,0),
+				v3s16(1,0,1),
+				v3s16(-1,0,-1),
+				v3s16(1,0,-1),
+				v3s16(-1,0,1),
+			};
+			for(u32 i=0; i<9; i++)
+			{
+				u8 content = CONTENT_AIR;
+				float level = -0.5 * BS;
+				u8 flags = 0;
+				// Check neighbor
+				v3s16 p2 = p + neighbor_dirs[i];
+				MapNode n2 = data->m_vmanip.getNodeNoEx(blockpos_nodes + p2);
+				if(n2.d != CONTENT_IGNORE)
+				{
+					content = n2.d;
+
+					if(n2.d == CONTENT_WATERSOURCE)
+						level = (-0.5+node_water_level) * BS;
+					else if(n2.d == CONTENT_WATER)
+						level = (-0.5 + ((float)n2.param2 + 0.5) / 8.0
+								* node_water_level) * BS;
+
+					// Check node above neighbor.
+					// NOTE: This doesn't get executed if neighbor
+					//       doesn't exist
+					p2.Y += 1;
+					n2 = data->m_vmanip.getNodeNoEx(blockpos_nodes + p2);
+					if(n2.d == CONTENT_WATERSOURCE || n2.d == CONTENT_WATER)
+						flags |= neighborflag_top_is_water;
+				}
+				
+				neighbor_levels.insert(neighbor_dirs[i], level);
+				neighbor_contents.insert(neighbor_dirs[i], content);
+				neighbor_flags.insert(neighbor_dirs[i], flags);
+			}
+
+			//float water_level = (-0.5 + ((float)n.param2 + 0.5) / 8.0) * BS;
+			//float water_level = neighbor_levels[v3s16(0,0,0)];
+
+			// Corner heights (average between four waters)
+			f32 corner_levels[4];
+			
+			v3s16 halfdirs[4] = {
+				v3s16(0,0,0),
+				v3s16(1,0,0),
+				v3s16(1,0,1),
+				v3s16(0,0,1),
+			};
+			for(u32 i=0; i<4; i++)
+			{
+				v3s16 cornerdir = halfdirs[i];
+				float cornerlevel = 0;
+				u32 valid_count = 0;
+				for(u32 j=0; j<4; j++)
+				{
+					v3s16 neighbordir = cornerdir - halfdirs[j];
+					u8 content = neighbor_contents[neighbordir];
+					// Special case for source nodes
+					if(content == CONTENT_WATERSOURCE)
+					{
+						cornerlevel = (-0.5+node_water_level)*BS;
+						valid_count = 1;
+						break;
+					}
+					else if(content == CONTENT_WATER)
+					{
+						cornerlevel += neighbor_levels[neighbordir];
+						valid_count++;
+					}
+					else if(content == CONTENT_AIR)
+					{
+						cornerlevel += -0.5*BS;
+						valid_count++;
+					}
+				}
+				if(valid_count > 0)
+					cornerlevel /= valid_count;
+				corner_levels[i] = cornerlevel;
+			}
+
+			/*
+				Generate sides
+			*/
+
+			v3s16 side_dirs[4] = {
+				v3s16(1,0,0),
+				v3s16(-1,0,0),
+				v3s16(0,0,1),
+				v3s16(0,0,-1),
+			};
+			s16 side_corners[4][2] = {
+				{1, 2},
+				{3, 0},
+				{2, 3},
+				{0, 1},
+			};
+			for(u32 i=0; i<4; i++)
+			{
+				v3s16 dir = side_dirs[i];
+
+				/*
+					If our topside is water and neighbor's topside
+					is water, don't draw side face
+				*/
+				if(top_is_water &&
+						neighbor_flags[dir] & neighborflag_top_is_water)
+					continue;
+
+				u8 neighbor_content = neighbor_contents[dir];
+				
+				// Don't draw face if neighbor is not air or water
+				if(neighbor_content != CONTENT_AIR
+						&& neighbor_content != CONTENT_WATER)
+					continue;
+				
+				bool neighbor_is_water = (neighbor_content == CONTENT_WATER);
+				
+				// Don't draw any faces if neighbor is water and top is water
+				if(neighbor_is_water == true && top_is_water == false)
+					continue;
+				
+				video::S3DVertex vertices[4] =
+				{
+					/*video::S3DVertex(-BS/2,0,BS/2, 0,0,0, c, 0,1),
+					video::S3DVertex(BS/2,0,BS/2, 0,0,0, c, 1,1),
+					video::S3DVertex(BS/2,0,BS/2, 0,0,0, c, 1,0),
+					video::S3DVertex(-BS/2,0,BS/2, 0,0,0, c, 0,0),*/
+					video::S3DVertex(-BS/2,0,BS/2, 0,0,0, c,
+							pa_water1.x0(), pa_water1.y1()),
+					video::S3DVertex(BS/2,0,BS/2, 0,0,0, c,
+							pa_water1.x1(), pa_water1.y1()),
+					video::S3DVertex(BS/2,0,BS/2, 0,0,0, c,
+							pa_water1.x1(), pa_water1.y0()),
+					video::S3DVertex(-BS/2,0,BS/2, 0,0,0, c,
+							pa_water1.x0(), pa_water1.y0()),
+				};
+				
+				/*
+					If our topside is water, set upper border of face
+					at upper border of node
+				*/
+				if(top_is_water)
+				{
+					vertices[2].Pos.Y = 0.5*BS;
+					vertices[3].Pos.Y = 0.5*BS;
+				}
+				/*
+					Otherwise upper position of face is corner levels
+				*/
+				else
+				{
+					vertices[2].Pos.Y = corner_levels[side_corners[i][0]];
+					vertices[3].Pos.Y = corner_levels[side_corners[i][1]];
+				}
+				
+				/*
+					If neighbor is water, lower border of face is corner
+					water levels
+				*/
+				if(neighbor_is_water)
+				{
+					vertices[0].Pos.Y = corner_levels[side_corners[i][1]];
+					vertices[1].Pos.Y = corner_levels[side_corners[i][0]];
+				}
+				/*
+					If neighbor is not water, lower border of face is
+					lower border of node
+				*/
+				else
+				{
+					vertices[0].Pos.Y = -0.5*BS;
+					vertices[1].Pos.Y = -0.5*BS;
+				}
+				
+				for(s32 j=0; j<4; j++)
+				{
+					if(dir == v3s16(0,0,1))
+						vertices[j].Pos.rotateXZBy(0);
+					if(dir == v3s16(0,0,-1))
+						vertices[j].Pos.rotateXZBy(180);
+					if(dir == v3s16(-1,0,0))
+						vertices[j].Pos.rotateXZBy(90);
+					if(dir == v3s16(1,0,-0))
+						vertices[j].Pos.rotateXZBy(-90);
+
+					vertices[j].Pos += intToFloat(p + blockpos_nodes, BS);
+				}
+
+				u16 indices[] = {0,1,2,2,3,0};
+				// Add to mesh collector
+				collector.append(material_water1, vertices, 4, indices, 6);
+			}
+			
+			/*
+				Generate top side, if appropriate
+			*/
+			
+			if(top_is_water == false)
+			{
+				video::S3DVertex vertices[4] =
+				{
+					/*video::S3DVertex(-BS/2,0,-BS/2, 0,0,0, c, 0,1),
+					video::S3DVertex(BS/2,0,-BS/2, 0,0,0, c, 1,1),
+					video::S3DVertex(BS/2,0,BS/2, 0,0,0, c, 1,0),
+					video::S3DVertex(-BS/2,0,BS/2, 0,0,0, c, 0,0),*/
+					video::S3DVertex(-BS/2,0,BS/2, 0,0,0, c,
+							pa_water1.x0(), pa_water1.y1()),
+					video::S3DVertex(BS/2,0,BS/2, 0,0,0, c,
+							pa_water1.x1(), pa_water1.y1()),
+					video::S3DVertex(BS/2,0,-BS/2, 0,0,0, c,
+							pa_water1.x1(), pa_water1.y0()),
+					video::S3DVertex(-BS/2,0,-BS/2, 0,0,0, c,
+							pa_water1.x0(), pa_water1.y0()),
+				};
+				
+				// This fixes a strange bug
+				s32 corner_resolve[4] = {3,2,1,0};
+
+				for(s32 i=0; i<4; i++)
+				{
+					//vertices[i].Pos.Y += water_level;
+					//vertices[i].Pos.Y += neighbor_levels[v3s16(0,0,0)];
+					s32 j = corner_resolve[i];
+					vertices[i].Pos.Y += corner_levels[j];
+					vertices[i].Pos += intToFloat(p + blockpos_nodes, BS);
+				}
+
+				u16 indices[] = {0,1,2,2,3,0};
+				// Add to mesh collector
+				collector.append(material_water1, vertices, 4, indices, 6);
+			}
+		}
+		/*
+			Add water sources to mesh if using new style
+		*/
+		else if(n.d == CONTENT_WATERSOURCE && new_style_water)
+		{
+			//bool top_is_water = false;
+			bool top_is_air = false;
+			MapNode n = data->m_vmanip.getNodeNoEx(blockpos_nodes + v3s16(x,y+1,z));
+			/*if(n.d == CONTENT_WATER || n.d == CONTENT_WATERSOURCE)
+				top_is_water = true;*/
+			if(n.d == CONTENT_AIR)
+				top_is_air = true;
+			
+			/*if(top_is_water == true)
+				continue;*/
+			if(top_is_air == false)
+				continue;
+
+			u8 l = decode_light(n.getLightBlend(data->m_daynight_ratio));
+			video::SColor c(WATER_ALPHA,l,l,l);
+			
+			video::S3DVertex vertices[4] =
+			{
+				/*video::S3DVertex(-BS/2,0,-BS/2, 0,0,0, c, 0,1),
+				video::S3DVertex(BS/2,0,-BS/2, 0,0,0, c, 1,1),
+				video::S3DVertex(BS/2,0,BS/2, 0,0,0, c, 1,0),
+				video::S3DVertex(-BS/2,0,BS/2, 0,0,0, c, 0,0),*/
+				video::S3DVertex(-BS/2,0,BS/2, 0,0,0, c,
+						pa_water1.x0(), pa_water1.y1()),
+				video::S3DVertex(BS/2,0,BS/2, 0,0,0, c,
+						pa_water1.x1(), pa_water1.y1()),
+				video::S3DVertex(BS/2,0,-BS/2, 0,0,0, c,
+						pa_water1.x1(), pa_water1.y0()),
+				video::S3DVertex(-BS/2,0,-BS/2, 0,0,0, c,
+						pa_water1.x0(), pa_water1.y0()),
+			};
+
+			for(s32 i=0; i<4; i++)
+			{
+				vertices[i].Pos.Y += (-0.5+node_water_level)*BS;
+				vertices[i].Pos += intToFloat(p + blockpos_nodes, BS);
+			}
+
+			u16 indices[] = {0,1,2,2,3,0};
+			// Add to mesh collector
+			collector.append(material_water1, vertices, 4, indices, 6);
+		}
+		/*
+			Add leaves if using new style
+		*/
+		else if(n.d == CONTENT_LEAVES && new_style_leaves)
+		{
+			/*u8 l = decode_light(n.getLightBlend(data->m_daynight_ratio));*/
+			u8 l = decode_light(undiminish_light(n.getLightBlend(data->m_daynight_ratio)));
+			video::SColor c(255,l,l,l);
+
+			for(u32 j=0; j<6; j++)
+			{
+				video::S3DVertex vertices[4] =
+				{
+					/*video::S3DVertex(-BS/2,-BS/2,BS/2, 0,0,0, c, 0,1),
+					video::S3DVertex(BS/2,-BS/2,BS/2, 0,0,0, c, 1,1),
+					video::S3DVertex(BS/2,BS/2,BS/2, 0,0,0, c, 1,0),
+					video::S3DVertex(-BS/2,BS/2,BS/2, 0,0,0, c, 0,0),*/
+					video::S3DVertex(-BS/2,-BS/2,BS/2, 0,0,0, c,
+						pa_leaves1.x0(), pa_leaves1.y1()),
+					video::S3DVertex(BS/2,-BS/2,BS/2, 0,0,0, c,
+						pa_leaves1.x1(), pa_leaves1.y1()),
+					video::S3DVertex(BS/2,BS/2,BS/2, 0,0,0, c,
+						pa_leaves1.x1(), pa_leaves1.y0()),
+					video::S3DVertex(-BS/2,BS/2,BS/2, 0,0,0, c,
+						pa_leaves1.x0(), pa_leaves1.y0()),
+				};
+
+				if(j == 0)
+				{
+					for(u16 i=0; i<4; i++)
+						vertices[i].Pos.rotateXZBy(0);
+				}
+				else if(j == 1)
+				{
+					for(u16 i=0; i<4; i++)
+						vertices[i].Pos.rotateXZBy(180);
+				}
+				else if(j == 2)
+				{
+					for(u16 i=0; i<4; i++)
+						vertices[i].Pos.rotateXZBy(-90);
+				}
+				else if(j == 3)
+				{
+					for(u16 i=0; i<4; i++)
+						vertices[i].Pos.rotateXZBy(90);
+				}
+				else if(j == 4)
+				{
+					for(u16 i=0; i<4; i++)
+						vertices[i].Pos.rotateYZBy(-90);
+				}
+				else if(j == 5)
+				{
+					for(u16 i=0; i<4; i++)
+						vertices[i].Pos.rotateYZBy(90);
+				}
+
+				for(u16 i=0; i<4; i++)
+				{
+					vertices[i].Pos += intToFloat(p + blockpos_nodes, BS);
+				}
+
+				u16 indices[] = {0,1,2,2,3,0};
+				// Add to mesh collector
+				collector.append(material_leaves1, vertices, 4, indices, 6);
+			}
+		}
+		/*
+			Add glass
+		*/
+		else if(n.d == CONTENT_GLASS)
+		{
+			u8 l = decode_light(undiminish_light(n.getLightBlend(data->m_daynight_ratio)));
+			video::SColor c(255,l,l,l);
+
+			for(u32 j=0; j<6; j++)
+			{
+				video::S3DVertex vertices[4] =
+				{
+					video::S3DVertex(-BS/2,-BS/2,BS/2, 0,0,0, c,
+						pa_glass.x0(), pa_glass.y1()),
+					video::S3DVertex(BS/2,-BS/2,BS/2, 0,0,0, c,
+						pa_glass.x1(), pa_glass.y1()),
+					video::S3DVertex(BS/2,BS/2,BS/2, 0,0,0, c,
+						pa_glass.x1(), pa_glass.y0()),
+					video::S3DVertex(-BS/2,BS/2,BS/2, 0,0,0, c,
+						pa_glass.x0(), pa_glass.y0()),
+				};
+
+				if(j == 0)
+				{
+					for(u16 i=0; i<4; i++)
+						vertices[i].Pos.rotateXZBy(0);
+				}
+				else if(j == 1)
+				{
+					for(u16 i=0; i<4; i++)
+						vertices[i].Pos.rotateXZBy(180);
+				}
+				else if(j == 2)
+				{
+					for(u16 i=0; i<4; i++)
+						vertices[i].Pos.rotateXZBy(-90);
+				}
+				else if(j == 3)
+				{
+					for(u16 i=0; i<4; i++)
+						vertices[i].Pos.rotateXZBy(90);
+				}
+				else if(j == 4)
+				{
+					for(u16 i=0; i<4; i++)
+						vertices[i].Pos.rotateYZBy(-90);
+				}
+				else if(j == 5)
+				{
+					for(u16 i=0; i<4; i++)
+						vertices[i].Pos.rotateYZBy(90);
+				}
+
+				for(u16 i=0; i<4; i++)
+				{
+					vertices[i].Pos += intToFloat(p + blockpos_nodes, BS);
+				}
+
+				u16 indices[] = {0,1,2,2,3,0};
+				// Add to mesh collector
+				collector.append(material_glass, vertices, 4, indices, 6);
+			}
+		}
+		/*
+			Add fence
+		*/
+		else if(n.d == CONTENT_FENCE)
+		{
+			u8 l = decode_light(undiminish_light(n.getLightBlend(data->m_daynight_ratio)));
+			video::SColor c(255,l,l,l);
+
+			const f32 post_rad=(f32)BS/10;
+			const f32 bar_rad=(f32)BS/20;
+			const f32 bar_len=(f32)(BS/2)-post_rad;
+
+			// The post - always present
+			v3f pos = intToFloat(p+blockpos_nodes, BS);
+			f32 postuv[24]={
+					0.4,0.4,0.6,0.6,
+					0.35,0,0.65,1,
+					0.35,0,0.65,1,
+					0.35,0,0.65,1,
+					0.35,0,0.65,1,
+					0.4,0.4,0.6,0.6};
+			makeCuboid(material_wood, &collector,
+				&pa_wood, c, pos,
+				post_rad,BS/2,post_rad, postuv);
+
+			// Now a section of fence, +X, if there's a post there
+			v3s16 p2 = p;
+			p2.X++;
+			MapNode n2 = data->m_vmanip.getNodeNoEx(blockpos_nodes + p2);
+			if(n2.d == CONTENT_FENCE)
+			{
+				pos = intToFloat(p+blockpos_nodes, BS);
+				pos.X += BS/2;
+				pos.Y += BS/4;
+				f32 xrailuv[24]={
+					0,0.4,1,0.6,
+					0,0.4,1,0.6,
+					0,0.4,1,0.6,
+					0,0.4,1,0.6,
+					0,0.4,1,0.6,
+					0,0.4,1,0.6};
+				makeCuboid(material_wood, &collector,
+					&pa_wood, c, pos,
+					bar_len,bar_rad,bar_rad, xrailuv);
+
+				pos.Y -= BS/2;
+				makeCuboid(material_wood, &collector,
+					&pa_wood, c, pos,
+					bar_len,bar_rad,bar_rad, xrailuv);
+			}
+
+			// Now a section of fence, +Z, if there's a post there
+			p2 = p;
+			p2.Z++;
+			n2 = data->m_vmanip.getNodeNoEx(blockpos_nodes + p2);
+			if(n2.d == CONTENT_FENCE)
+			{
+				pos = intToFloat(p+blockpos_nodes, BS);
+				pos.Z += BS/2;
+				pos.Y += BS/4;
+				f32 zrailuv[24]={
+					0,0.4,1,0.6,
+					0,0.4,1,0.6,
+					0,0.4,1,0.6,
+					0,0.4,1,0.6,
+					0,0.4,1,0.6,
+					0,0.4,1,0.6};
+				makeCuboid(material_wood, &collector,
+					&pa_wood, c, pos,
+					bar_rad,bar_rad,bar_len, zrailuv);
+				pos.Y -= BS/2;
+				makeCuboid(material_wood, &collector,
+					&pa_wood, c, pos,
+					bar_rad,bar_rad,bar_len, zrailuv);
+
+			}
+
+		}
+#if 1
+		/*
+			Add stones with minerals if stone is invisible
+		*/
+		else if(n.d == CONTENT_STONE && invisible_stone && n.getMineral() != MINERAL_NONE)
+		{
+			for(u32 j=0; j<6; j++)
+			{
+				// NOTE: Hopefully g_6dirs[j] is the right direction...
+				v3s16 dir = g_6dirs[j];
+				/*u8 l = 0;
+				MapNode n2 = data->m_vmanip.getNodeNoEx(blockpos_nodes + dir);
+				if(content_features(n2.d).param_type == CPT_LIGHT)
+					l = decode_light(n2.getLightBlend(data->m_daynight_ratio));
+				else
+					l = 255;*/
+				u8 l = 255;
+				video::SColor c(255,l,l,l);
+				
+				// Get the right texture
+				TileSpec ts = n.getTile(dir);
+				AtlasPointer ap = ts.texture;
+				material_general.setTexture(0, ap.atlas);
+				video::S3DVertex vertices[4] =
+ 				{
+					/*video::S3DVertex(-BS/2,-BS/2,BS/2, 0,0,0, c, 0,1),
+					video::S3DVertex(BS/2,-BS/2,BS/2, 0,0,0, c, 1,1),
+					video::S3DVertex(BS/2,BS/2,BS/2, 0,0,0, c, 1,0),
+					video::S3DVertex(-BS/2,BS/2,BS/2, 0,0,0, c, 0,0),*/
+					video::S3DVertex(-BS/2,-BS/2,BS/2, 0,0,0, c,
+						ap.x0(), ap.y1()),
+					video::S3DVertex(BS/2,-BS/2,BS/2, 0,0,0, c,
+						ap.x1(), ap.y1()),
+					video::S3DVertex(BS/2,BS/2,BS/2, 0,0,0, c,
+						ap.x1(), ap.y0()),
+					video::S3DVertex(-BS/2,BS/2,BS/2, 0,0,0, c,
+						ap.x0(), ap.y0()),
+				};
+
+				if(j == 0)
+				{
+					for(u16 i=0; i<4; i++)
+						vertices[i].Pos.rotateXZBy(0);
+				}
+				else if(j == 1)
+				{
+					for(u16 i=0; i<4; i++)
+						vertices[i].Pos.rotateXZBy(180);
+				}
+				else if(j == 2)
+				{
+					for(u16 i=0; i<4; i++)
+						vertices[i].Pos.rotateXZBy(-90);
+				}
+				else if(j == 3)
+				{
+					for(u16 i=0; i<4; i++)
+						vertices[i].Pos.rotateXZBy(90);
+				}
+				else if(j == 4)
+
+				for(u16 i=0; i<4; i++)
+				{
+					vertices[i].Pos += intToFloat(p + blockpos_nodes, BS);
+				}
+
+				u16 indices[] = {0,1,2,2,3,0};
+				// Add to mesh collector
+				collector.append(material_general, vertices, 4, indices, 6);
+			}
+		}
+#endif
+		else if(n.d == CONTENT_PAPYRUS)
+		{
+			u8 l = decode_light(undiminish_light(n.getLightBlend(data->m_daynight_ratio)));
+			video::SColor c(255,l,l,l);
+
+			for(u32 j=0; j<4; j++)
+			{
+				video::S3DVertex vertices[4] =
+				{
+					video::S3DVertex(-BS/2,-BS/2,0, 0,0,0, c,
+						pa_papyrus.x0(), pa_papyrus.y1()),
+					video::S3DVertex(BS/2,-BS/2,0, 0,0,0, c,
+						pa_papyrus.x1(), pa_papyrus.y1()),
+					video::S3DVertex(BS/2,BS/2,0, 0,0,0, c,
+						pa_papyrus.x1(), pa_papyrus.y0()),
+					video::S3DVertex(-BS/2,BS/2,0, 0,0,0, c,
+						pa_papyrus.x0(), pa_papyrus.y0()),
+				};
+
+				if(j == 0)
+				{
+					for(u16 i=0; i<4; i++)
+						vertices[i].Pos.rotateXZBy(45);
+				}
+				else if(j == 1)
+				{
+					for(u16 i=0; i<4; i++)
+						vertices[i].Pos.rotateXZBy(-45);
+				}
+				else if(j == 2)
+				{
+					for(u16 i=0; i<4; i++)
+						vertices[i].Pos.rotateXZBy(135);
+				}
+				else if(j == 3)
+				{
+					for(u16 i=0; i<4; i++)
+						vertices[i].Pos.rotateXZBy(-135);
+				}
+
+				for(u16 i=0; i<4; i++)
+				{
+					vertices[i].Pos += intToFloat(p + blockpos_nodes, BS);
+				}
+
+				u16 indices[] = {0,1,2,2,3,0};
+				// Add to mesh collector
+				collector.append(material_papyrus, vertices, 4, indices, 6);
+			}
+		}
+		else if(n.d == CONTENT_RAIL)
+		{
+			u8 l = decode_light(n.getLightBlend(data->m_daynight_ratio));
+			video::SColor c(255,l,l,l);
+
+			bool is_rail_x [] = { false, false };  /* x-1, x+1 */
+			bool is_rail_z [] = { false, false };  /* z-1, z+1 */
+
+			MapNode n_minus_x = data->m_vmanip.getNodeNoEx(blockpos_nodes + v3s16(x-1,y,z));
+			MapNode n_plus_x = data->m_vmanip.getNodeNoEx(blockpos_nodes + v3s16(x+1,y,z));
+			MapNode n_minus_z = data->m_vmanip.getNodeNoEx(blockpos_nodes + v3s16(x,y,z-1));
+			MapNode n_plus_z = data->m_vmanip.getNodeNoEx(blockpos_nodes + v3s16(x,y,z+1));
+
+			if(n_minus_x.d == CONTENT_RAIL)
+				is_rail_x[0] = true;
+			if(n_plus_x.d == CONTENT_RAIL)
+				is_rail_x[1] = true;
+			if(n_minus_z.d == CONTENT_RAIL)
+				is_rail_z[0] = true;
+			if(n_plus_z.d == CONTENT_RAIL)
+				is_rail_z[1] = true;
+
+			float d = (float)BS/16;
+			video::S3DVertex vertices[4] =
+			{
+				video::S3DVertex(-BS/2,-BS/2+d,-BS/2, 0,0,0, c,
+					0, 1),
+				video::S3DVertex(BS/2,-BS/2+d,-BS/2, 0,0,0, c,
+					1, 1),
+				video::S3DVertex(BS/2,-BS/2+d,BS/2, 0,0,0, c,
+					1, 0),
+				video::S3DVertex(-BS/2,-BS/2+d,BS/2, 0,0,0, c,
+					0, 0),
+			};
+
+			video::SMaterial material_rail;
+			material_rail.setFlag(video::EMF_LIGHTING, false);
+			material_rail.setFlag(video::EMF_BACK_FACE_CULLING, false);
+			material_rail.setFlag(video::EMF_BILINEAR_FILTER, false);
+			material_rail.setFlag(video::EMF_FOG_ENABLE, true);
+			material_rail.MaterialType
+					= video::EMT_TRANSPARENT_ALPHA_CHANNEL_REF;
+
+			int adjacencies = is_rail_x[0] + is_rail_x[1] + is_rail_z[0] + is_rail_z[1];
+
+			// Assign textures
+			if(adjacencies < 2)
+				material_rail.setTexture(0, g_texturesource->getTextureRaw("rail.png"));
+			else if(adjacencies == 2)
+			{
+				if((is_rail_x[0] && is_rail_x[1]) || (is_rail_z[0] && is_rail_z[1]))
+					material_rail.setTexture(0, g_texturesource->getTextureRaw("rail.png"));
+				else
+					material_rail.setTexture(0, g_texturesource->getTextureRaw("rail_curved.png"));
+			}
+			else if(adjacencies == 3)
+				material_rail.setTexture(0, g_texturesource->getTextureRaw("rail_t_junction.png"));
+			else if(adjacencies == 4)
+				material_rail.setTexture(0, g_texturesource->getTextureRaw("rail_crossing.png"));
+
+			// Rotate textures
+			int angle = 0;
+
+			if(adjacencies == 1)
+			{
+				if(is_rail_x[0] || is_rail_x[1])
+					angle = 90;
+			}
+			else if(adjacencies == 2)
+			{
+				if(is_rail_x[0] && is_rail_x[1])
+					angle = 90;
+				else if(is_rail_x[0] && is_rail_z[0])
+					angle = 270;
+				else if(is_rail_x[0] && is_rail_z[1])
+					angle = 180;
+				else if(is_rail_x[1] && is_rail_z[1])
+					angle = 90;
+			}
+			else if(adjacencies == 3)
+			{
+				if(!is_rail_x[0])
+					angle=0;
+				if(!is_rail_x[1])
+					angle=180;
+				if(!is_rail_z[0])
+					angle=90;
+				if(!is_rail_z[1])
+					angle=270;
+			}
+
+			if(angle != 0) {
+				for(u16 i=0; i<4; i++)
+					vertices[i].Pos.rotateXZBy(angle);
+			}
+
+			for(s32 i=0; i<4; i++)
+			{
+				vertices[i].Pos += intToFloat(p + blockpos_nodes, BS);
+			}
+
+			u16 indices[] = {0,1,2,2,3,0};
+			collector.append(material_rail, vertices, 4, indices, 6);
+		}
+	}
+}
+#endif
+
diff --git a/src/guiFurnaceMenu.h b/src/content_mapblock.h
index ccc2e9dc0..438422014 100644
--- a/src/guiFurnaceMenu.h
+++ b/src/content_mapblock.h
@@ -1,6 +1,6 @@
 /*
 Minetest-c55
-Copyright (C) 2010 celeron55, Perttu Ahola <celeron55@gmail.com>
+Copyright (C) 2010-2011 celeron55, Perttu Ahola <celeron55@gmail.com>
 
 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
@@ -17,28 +17,15 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
-#ifndef GUIFURNACEMENU_HEADER
-#define GUIFURNACEMENU_HEADER
+#ifndef CONTENT_MAPBLOCK_HEADER
+#define CONTENT_MAPBLOCK_HEADER
 
-#include "guiInventoryMenu.h"
-
-class Client;
-
-class GUIFurnaceMenu : public GUIInventoryMenu
-{
-public:
-	GUIFurnaceMenu(
-			gui::IGUIEnvironment* env,
-			gui::IGUIElement* parent, s32 id,
-			IMenuManager *menumgr,
-			v3s16 nodepos,
-			Client *client
-			);
-private:
-	
-	v3s16 m_nodepos;
-	Client *m_client;
-};
+#ifndef SERVER
+	#include "mapblock_mesh.h"
+	#include "utility.h"
+void mapblock_mesh_generate_special(MeshMakeData *data,
+		MeshCollector &collector);
+#endif
 
 #endif
 
diff --git a/src/content_mapnode.cpp b/src/content_mapnode.cpp
new file mode 100644
index 000000000..2e7a240f3
--- /dev/null
+++ b/src/content_mapnode.cpp
@@ -0,0 +1,450 @@
+/*
+Minetest-c55
+Copyright (C) 2010-2011 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+// For g_settings
+#include "main.h"
+
+#include "content_mapnode.h"
+#include "mapnode.h"
+#include "content_nodemeta.h"
+
+// TODO: Get rid of these and set up some attributes like toughness,
+//       fluffyness, and a funciton to calculate time and durability loss
+//       (and sound? and whatever else) from them
+void setStoneLikeDiggingProperties(DiggingPropertiesList &list, float toughness);
+void setDirtLikeDiggingProperties(DiggingPropertiesList &list, float toughness);
+void setWoodLikeDiggingProperties(DiggingPropertiesList &list, float toughness);
+
+void content_mapnode_init()
+{
+	// Read some settings
+	bool new_style_water = g_settings.getBool("new_style_water");
+	bool new_style_leaves = g_settings.getBool("new_style_leaves");
+	bool invisible_stone = g_settings.getBool("invisible_stone");
+
+	u8 i;
+	ContentFeatures *f = NULL;
+
+	i = CONTENT_STONE;
+	f = &content_features(i);
+	f->setAllTextures("stone.png");
+	f->setInventoryTextureCube("stone.png", "stone.png", "stone.png");
+	f->param_type = CPT_MINERAL;
+	f->is_ground_content = true;
+	f->dug_item = std::string("MaterialItem ")+itos(CONTENT_COBBLE)+" 1";
+	setStoneLikeDiggingProperties(f->digging_properties, 1.0);
+	if(invisible_stone)
+		f->solidness = 0; // For debugging, hides regular stone
+	
+	i = CONTENT_GRASS;
+	f = &content_features(i);
+	f->setAllTextures("mud.png^grass_side.png");
+	f->setTexture(0, "grass.png");
+	f->setTexture(1, "mud.png");
+	f->param_type = CPT_MINERAL;
+	f->is_ground_content = true;
+	f->dug_item = std::string("MaterialItem ")+itos(CONTENT_MUD)+" 1";
+	setDirtLikeDiggingProperties(f->digging_properties, 1.0);
+	
+	i = CONTENT_GRASS_FOOTSTEPS;
+	f = &content_features(i);
+	f->setAllTextures("mud.png^grass_side.png");
+	f->setTexture(0, "grass_footsteps.png");
+	f->setTexture(1, "mud.png");
+	f->param_type = CPT_MINERAL;
+	f->is_ground_content = true;
+	f->dug_item = std::string("MaterialItem ")+itos(CONTENT_MUD)+" 1";
+	setDirtLikeDiggingProperties(f->digging_properties, 1.0);
+	
+	i = CONTENT_MUD;
+	f = &content_features(i);
+	f->setAllTextures("mud.png");
+	f->setInventoryTextureCube("mud.png", "mud.png", "mud.png");
+	f->param_type = CPT_MINERAL;
+	f->is_ground_content = true;
+	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
+	setDirtLikeDiggingProperties(f->digging_properties, 1.0);
+	
+	i = CONTENT_SAND;
+	f = &content_features(i);
+	f->setAllTextures("sand.png");
+	f->setInventoryTextureCube("sand.png", "sand.png", "sand.png");
+	f->param_type = CPT_MINERAL;
+	f->is_ground_content = true;
+	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
+	setDirtLikeDiggingProperties(f->digging_properties, 1.0);
+	
+	i = CONTENT_GRAVEL;
+	f = &content_features(i);
+	f->setAllTextures("gravel.png");
+	f->setInventoryTextureCube("gravel.png", "gravel.png", "gravel.png");
+	f->param_type = CPT_MINERAL;
+	f->is_ground_content = true;
+	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
+	setDirtLikeDiggingProperties(f->digging_properties, 1.75);
+	
+	i = CONTENT_SANDSTONE;
+	f = &content_features(i);
+	f->setAllTextures("sandstone.png");
+	f->setInventoryTextureCube("sandstone.png", "sandstone.png", "sandstone.png");
+	f->param_type = CPT_MINERAL;
+	f->is_ground_content = true;
+	f->dug_item = std::string("MaterialItem ")+itos(CONTENT_SAND)+" 1";
+	setDirtLikeDiggingProperties(f->digging_properties, 1.0);
+
+	i = CONTENT_CLAY;
+	f = &content_features(i);
+	f->setAllTextures("clay.png");
+	f->setInventoryTextureCube("clay.png", "clay.png", "clay.png");
+	f->param_type = CPT_MINERAL;
+	f->is_ground_content = true;
+	f->dug_item = std::string("CraftItem lump_of_clay 4");
+	setDirtLikeDiggingProperties(f->digging_properties, 1.0);
+
+	i = CONTENT_BRICK;
+	f = &content_features(i);
+	f->setAllTextures("brick.png");
+	f->setInventoryTextureCube("brick.png", "brick.png", "brick.png");
+	f->param_type = CPT_MINERAL;
+	f->is_ground_content = true;
+	f->dug_item = std::string("CraftItem clay_brick 4");
+	setStoneLikeDiggingProperties(f->digging_properties, 1.0);
+
+	i = CONTENT_TREE;
+	f = &content_features(i);
+	f->setAllTextures("tree.png");
+	f->setTexture(0, "tree_top.png");
+	f->setTexture(1, "tree_top.png");
+	f->param_type = CPT_MINERAL;
+	f->is_ground_content = true;
+	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
+	setWoodLikeDiggingProperties(f->digging_properties, 1.0);
+	
+	i = CONTENT_LEAVES;
+	f = &content_features(i);
+	f->light_propagates = true;
+	//f->param_type = CPT_MINERAL;
+	f->param_type = CPT_LIGHT;
+	f->is_ground_content = true;
+	if(new_style_leaves)
+	{
+		f->solidness = 0; // drawn separately, makes no faces
+		f->setInventoryTextureCube("leaves.png", "leaves.png", "leaves.png");
+	}
+	else
+	{
+		f->setAllTextures("[noalpha:leaves.png");
+	}
+	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
+	setWoodLikeDiggingProperties(f->digging_properties, 0.15);
+
+	i = CONTENT_CACTUS;
+	f = &content_features(i);
+	f->setAllTextures("cactus_side.png");
+	f->setTexture(0, "cactus_top.png");
+	f->setTexture(1, "cactus_top.png");
+	f->setInventoryTextureCube("cactus_top.png", "cactus_side.png", "cactus_side.png");
+	f->param_type = CPT_MINERAL;
+	f->is_ground_content = true;
+	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
+	setWoodLikeDiggingProperties(f->digging_properties, 0.75);
+
+	i = CONTENT_PAPYRUS;
+	f = &content_features(i);
+	f->setInventoryTexture("papyrus.png");
+	f->light_propagates = true;
+	f->param_type = CPT_LIGHT;
+	f->is_ground_content = true;
+	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
+	f->solidness = 0; // drawn separately, makes no faces
+	f->walkable = false;
+	setWoodLikeDiggingProperties(f->digging_properties, 0.25);
+
+	i = CONTENT_BOOKSHELF;
+	f = &content_features(i);
+	f->setAllTextures("bookshelf.png");
+	f->setTexture(0, "wood.png");
+	f->setTexture(1, "wood.png");
+	// FIXME: setInventoryTextureCube() only cares for the first texture
+	f->setInventoryTextureCube("bookshelf.png", "bookshelf.png", "bookshelf.png");
+	//f->setInventoryTextureCube("wood.png", "bookshelf.png", "bookshelf.png");
+	f->param_type = CPT_MINERAL;
+	f->is_ground_content = true;
+	setWoodLikeDiggingProperties(f->digging_properties, 0.75);
+
+	i = CONTENT_GLASS;
+	f = &content_features(i);
+	f->light_propagates = true;
+	f->param_type = CPT_LIGHT;
+	f->is_ground_content = true;
+	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
+	f->solidness = 0; // drawn separately, makes no faces
+	f->setInventoryTextureCube("glass.png", "glass.png", "glass.png");
+	setWoodLikeDiggingProperties(f->digging_properties, 0.15);
+
+	i = CONTENT_FENCE;
+	f = &content_features(i);
+	f->light_propagates = true;
+	f->param_type = CPT_LIGHT;
+	f->is_ground_content = true;
+	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
+	f->solidness = 0; // drawn separately, makes no faces
+	f->air_equivalent = true; // grass grows underneath
+	f->setInventoryTexture("item_fence.png");
+	setWoodLikeDiggingProperties(f->digging_properties, 0.75);
+
+	i = CONTENT_RAIL;
+	f = &content_features(i);
+	f->setInventoryTexture("rail.png");
+	f->light_propagates = true;
+	f->param_type = CPT_LIGHT;
+	f->is_ground_content = true;
+	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
+	f->solidness = 0; // drawn separately, makes no faces
+	f->air_equivalent = true; // grass grows underneath
+	f->walkable = false;
+	setDirtLikeDiggingProperties(f->digging_properties, 0.75);
+
+	// Deprecated
+	i = CONTENT_COALSTONE;
+	f = &content_features(i);
+	//f->translate_to = new MapNode(CONTENT_STONE, MINERAL_COAL);
+	f->setAllTextures("stone.png^mineral_coal.png");
+	f->is_ground_content = true;
+	setStoneLikeDiggingProperties(f->digging_properties, 1.5);
+	
+	i = CONTENT_WOOD;
+	f = &content_features(i);
+	f->setAllTextures("wood.png");
+	f->setInventoryTextureCube("wood.png", "wood.png", "wood.png");
+	f->is_ground_content = true;
+	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
+	setWoodLikeDiggingProperties(f->digging_properties, 0.75);
+	
+	i = CONTENT_MESE;
+	f = &content_features(i);
+	f->setAllTextures("mese.png");
+	f->setInventoryTextureCube("mese.png", "mese.png", "mese.png");
+	f->is_ground_content = true;
+	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
+	setStoneLikeDiggingProperties(f->digging_properties, 0.5);
+	
+	i = CONTENT_CLOUD;
+	f = &content_features(i);
+	f->setAllTextures("cloud.png");
+	f->setInventoryTextureCube("cloud.png", "cloud.png", "cloud.png");
+	f->is_ground_content = true;
+	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
+	
+	i = CONTENT_AIR;
+	f = &content_features(i);
+	f->param_type = CPT_LIGHT;
+	f->light_propagates = true;
+	f->sunlight_propagates = true;
+	f->solidness = 0;
+	f->walkable = false;
+	f->pointable = false;
+	f->diggable = false;
+	f->buildable_to = true;
+	f->air_equivalent = true;
+	
+	i = CONTENT_WATER;
+	f = &content_features(i);
+	f->setInventoryTextureCube("water.png", "water.png", "water.png");
+	f->param_type = CPT_LIGHT;
+	f->light_propagates = true;
+	f->solidness = 0; // Drawn separately, makes no faces
+	f->walkable = false;
+	f->pointable = false;
+	f->diggable = false;
+	f->buildable_to = true;
+	f->liquid_type = LIQUID_FLOWING;
+	f->liquid_alternative_flowing = CONTENT_WATER;
+	
+	i = CONTENT_WATERSOURCE;
+	f = &content_features(i);
+	//f->setInventoryTexture("water.png");
+	f->setInventoryTextureCube("water.png", "water.png", "water.png");
+	if(new_style_water)
+	{
+		f->solidness = 0; // drawn separately, makes no faces
+	}
+	else // old style
+	{
+		f->solidness = 1;
+
+		TileSpec t;
+		if(g_texturesource)
+			t.texture = g_texturesource->getTexture("water.png");
+		
+		t.alpha = WATER_ALPHA;
+		t.material_type = MATERIAL_ALPHA_VERTEX;
+		t.material_flags &= ~MATERIAL_FLAG_BACKFACE_CULLING;
+		f->setAllTiles(t);
+	}
+	f->param_type = CPT_LIGHT;
+	f->light_propagates = true;
+	f->walkable = false;
+	f->pointable = false;
+	f->diggable = false;
+	f->buildable_to = true;
+	f->liquid_type = LIQUID_SOURCE;
+	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
+	f->liquid_alternative_flowing = CONTENT_WATER;
+	
+	i = CONTENT_TORCH;
+	f = &content_features(i);
+	f->setInventoryTexture("torch_on_floor.png");
+	f->param_type = CPT_LIGHT;
+	f->light_propagates = true;
+	f->sunlight_propagates = true;
+	f->solidness = 0; // drawn separately, makes no faces
+	f->walkable = false;
+	f->wall_mounted = true;
+	f->air_equivalent = true;
+	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
+	f->light_source = LIGHT_MAX-1;
+	f->digging_properties.set("", DiggingProperties(true, 0.0, 0));
+	
+	i = CONTENT_SIGN_WALL;
+	f = &content_features(i);
+	f->setInventoryTexture("sign_wall.png");
+	f->param_type = CPT_LIGHT;
+	f->light_propagates = true;
+	f->sunlight_propagates = true;
+	f->solidness = 0; // drawn separately, makes no faces
+	f->walkable = false;
+	f->wall_mounted = true;
+	f->air_equivalent = true;
+	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
+	if(f->initial_metadata == NULL)
+		f->initial_metadata = new SignNodeMetadata("Some sign");
+	f->digging_properties.set("", DiggingProperties(true, 0.5, 0));
+	
+	i = CONTENT_CHEST;
+	f = &content_features(i);
+	f->param_type = CPT_FACEDIR_SIMPLE;
+	f->setAllTextures("chest_side.png");
+	f->setTexture(0, "chest_top.png");
+	f->setTexture(1, "chest_top.png");
+	f->setTexture(5, "chest_front.png"); // Z-
+	f->setInventoryTexture("chest_top.png");
+	//f->setInventoryTextureCube("chest_top.png", "chest_side.png", "chest_side.png");
+	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
+	if(f->initial_metadata == NULL)
+		f->initial_metadata = new ChestNodeMetadata();
+	setWoodLikeDiggingProperties(f->digging_properties, 1.0);
+	
+	i = CONTENT_FURNACE;
+	f = &content_features(i);
+	f->param_type = CPT_FACEDIR_SIMPLE;
+	f->setAllTextures("furnace_side.png");
+	f->setTexture(5, "furnace_front.png"); // Z-
+	f->setInventoryTexture("furnace_front.png");
+	//f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
+	f->dug_item = std::string("MaterialItem ")+itos(CONTENT_COBBLE)+" 6";
+	if(f->initial_metadata == NULL)
+		f->initial_metadata = new FurnaceNodeMetadata();
+	setStoneLikeDiggingProperties(f->digging_properties, 3.0);
+	
+	i = CONTENT_COBBLE;
+	f = &content_features(i);
+	f->setAllTextures("cobble.png");
+	f->setInventoryTextureCube("cobble.png", "cobble.png", "cobble.png");
+	f->param_type = CPT_NONE;
+	f->is_ground_content = true;
+	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
+	setStoneLikeDiggingProperties(f->digging_properties, 0.9);
+
+	i = CONTENT_MOSSYCOBBLE;
+	f = &content_features(i);
+	f->setAllTextures("mossycobble.png");
+	f->setInventoryTextureCube("mossycobble.png", "mossycobble.png", "mossycobble.png");
+	f->param_type = CPT_NONE;
+	f->is_ground_content = true;
+	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
+	setStoneLikeDiggingProperties(f->digging_properties, 0.8);
+	
+	i = CONTENT_STEEL;
+	f = &content_features(i);
+	f->setAllTextures("steel_block.png");
+	f->setInventoryTextureCube("steel_block.png", "steel_block.png",
+			"steel_block.png");
+	f->param_type = CPT_NONE;
+	f->is_ground_content = true;
+	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
+	setStoneLikeDiggingProperties(f->digging_properties, 5.0);
+	
+	// NOTE: Remember to add frequently used stuff to the texture atlas in tile.cpp
+	
+
+	/*
+		Add MesePick to everything
+	*/
+	for(u16 i=0; i<256; i++)
+	{
+		content_features(i).digging_properties.set("MesePick",
+				DiggingProperties(true, 0.0, 65535./1337));
+	}
+
+}
+
+void setStoneLikeDiggingProperties(DiggingPropertiesList &list, float toughness)
+{
+	list.set("",
+			DiggingProperties(true, 15.0*toughness, 0));
+	
+	list.set("WPick",
+			DiggingProperties(true, 1.3*toughness, 65535./30.*toughness));
+	list.set("STPick",
+			DiggingProperties(true, 0.75*toughness, 65535./100.*toughness));
+	list.set("SteelPick",
+			DiggingProperties(true, 0.50*toughness, 65535./333.*toughness));
+
+	/*list.set("MesePick",
+			DiggingProperties(true, 0.0*toughness, 65535./20.*toughness));*/
+}
+
+void setDirtLikeDiggingProperties(DiggingPropertiesList &list, float toughness)
+{
+	list.set("",
+			DiggingProperties(true, 0.75*toughness, 0));
+	
+	list.set("WShovel",
+			DiggingProperties(true, 0.4*toughness, 65535./50.*toughness));
+	list.set("STShovel",
+			DiggingProperties(true, 0.2*toughness, 65535./150.*toughness));
+	list.set("SteelShovel",
+			DiggingProperties(true, 0.15*toughness, 65535./400.*toughness));
+}
+
+void setWoodLikeDiggingProperties(DiggingPropertiesList &list, float toughness)
+{
+	list.set("",
+			DiggingProperties(true, 3.0*toughness, 0));
+	
+	list.set("WAxe",
+			DiggingProperties(true, 1.5*toughness, 65535./30.*toughness));
+	list.set("STAxe",
+			DiggingProperties(true, 0.75*toughness, 65535./100.*toughness));
+	list.set("SteelAxe",
+			DiggingProperties(true, 0.5*toughness, 65535./333.*toughness));
+}
+
+
diff --git a/src/content_mapnode.h b/src/content_mapnode.h
new file mode 100644
index 000000000..e53624c21
--- /dev/null
+++ b/src/content_mapnode.h
@@ -0,0 +1,62 @@
+/*
+Minetest-c55
+Copyright (C) 2010-2011 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#ifndef CONTENT_MAPNODE_HEADER
+#define CONTENT_MAPNODE_HEADER
+
+void content_mapnode_init();
+
+/*
+	Node content type IDs
+*/
+#define CONTENT_STONE 0
+#define CONTENT_GRASS 1
+#define CONTENT_WATER 2
+#define CONTENT_TORCH 3
+#define CONTENT_TREE 4
+#define CONTENT_LEAVES 5
+#define CONTENT_GRASS_FOOTSTEPS 6
+#define CONTENT_MESE 7
+#define CONTENT_MUD 8
+#define CONTENT_WATERSOURCE 9
+// Pretty much useless, clouds won't be drawn this way
+#define CONTENT_CLOUD 10
+#define CONTENT_COALSTONE 11
+#define CONTENT_WOOD 12
+#define CONTENT_SAND 13
+#define CONTENT_SIGN_WALL 14
+#define CONTENT_CHEST 15
+#define CONTENT_FURNACE 16
+//#define CONTENT_WORKBENCH 17
+#define CONTENT_COBBLE 18
+#define CONTENT_STEEL 19
+#define CONTENT_GLASS 20
+#define CONTENT_FENCE 21
+#define CONTENT_MOSSYCOBBLE 22
+#define CONTENT_GRAVEL 23
+#define CONTENT_SANDSTONE 24
+#define CONTENT_CACTUS 25
+#define CONTENT_BRICK 26
+#define CONTENT_CLAY 27
+#define CONTENT_PAPYRUS 28
+#define CONTENT_BOOKSHELF 29
+#define CONTENT_RAIL 30
+
+#endif
+
diff --git a/src/content_nodemeta.cpp b/src/content_nodemeta.cpp
new file mode 100644
index 000000000..681e2b925
--- /dev/null
+++ b/src/content_nodemeta.cpp
@@ -0,0 +1,321 @@
+/*
+Minetest-c55
+Copyright (C) 2010-2011 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "content_nodemeta.h"
+#include "inventory.h"
+#include "content_mapnode.h"
+
+/*
+	SignNodeMetadata
+*/
+
+// Prototype
+SignNodeMetadata proto_SignNodeMetadata("");
+
+SignNodeMetadata::SignNodeMetadata(std::string text):
+	m_text(text)
+{
+	NodeMetadata::registerType(typeId(), create);
+}
+u16 SignNodeMetadata::typeId() const
+{
+	return CONTENT_SIGN_WALL;
+}
+NodeMetadata* SignNodeMetadata::create(std::istream &is)
+{
+	std::string text = deSerializeString(is);
+	return new SignNodeMetadata(text);
+}
+NodeMetadata* SignNodeMetadata::clone()
+{
+	return new SignNodeMetadata(m_text);
+}
+void SignNodeMetadata::serializeBody(std::ostream &os)
+{
+	os<<serializeString(m_text);
+}
+std::string SignNodeMetadata::infoText()
+{
+	return std::string("\"")+m_text+"\"";
+}
+
+/*
+	ChestNodeMetadata
+*/
+
+// Prototype
+ChestNodeMetadata proto_ChestNodeMetadata;
+
+ChestNodeMetadata::ChestNodeMetadata()
+{
+	NodeMetadata::registerType(typeId(), create);
+	
+	m_inventory = new Inventory();
+	m_inventory->addList("0", 8*4);
+}
+ChestNodeMetadata::~ChestNodeMetadata()
+{
+	delete m_inventory;
+}
+u16 ChestNodeMetadata::typeId() const
+{
+	return CONTENT_CHEST;
+}
+NodeMetadata* ChestNodeMetadata::create(std::istream &is)
+{
+	ChestNodeMetadata *d = new ChestNodeMetadata();
+	d->m_inventory->deSerialize(is);
+	return d;
+}
+NodeMetadata* ChestNodeMetadata::clone()
+{
+	ChestNodeMetadata *d = new ChestNodeMetadata();
+	*d->m_inventory = *m_inventory;
+	return d;
+}
+void ChestNodeMetadata::serializeBody(std::ostream &os)
+{
+	m_inventory->serialize(os);
+}
+std::string ChestNodeMetadata::infoText()
+{
+	return "Chest";
+}
+bool ChestNodeMetadata::nodeRemovalDisabled()
+{
+	/*
+		Disable removal if chest contains something
+	*/
+	InventoryList *list = m_inventory->getList("0");
+	if(list == NULL)
+		return false;
+	if(list->getUsedSlots() == 0)
+		return false;
+	return true;
+}
+std::string ChestNodeMetadata::getInventoryDrawSpecString()
+{
+	return
+		"invsize[8,9;]"
+		"list[current_name;0;0,0;8,4;]"
+		"list[current_player;main;0,5;8,4;]";
+}
+
+/*
+	FurnaceNodeMetadata
+*/
+
+// Prototype
+FurnaceNodeMetadata proto_FurnaceNodeMetadata;
+
+FurnaceNodeMetadata::FurnaceNodeMetadata()
+{
+	NodeMetadata::registerType(typeId(), create);
+	
+	m_inventory = new Inventory();
+	m_inventory->addList("fuel", 1);
+	m_inventory->addList("src", 1);
+	m_inventory->addList("dst", 4);
+
+	m_step_accumulator = 0;
+	m_fuel_totaltime = 0;
+	m_fuel_time = 0;
+	m_src_totaltime = 0;
+	m_src_time = 0;
+}
+FurnaceNodeMetadata::~FurnaceNodeMetadata()
+{
+	delete m_inventory;
+}
+u16 FurnaceNodeMetadata::typeId() const
+{
+	return CONTENT_FURNACE;
+}
+NodeMetadata* FurnaceNodeMetadata::clone()
+{
+	FurnaceNodeMetadata *d = new FurnaceNodeMetadata();
+	*d->m_inventory = *m_inventory;
+	return d;
+}
+NodeMetadata* FurnaceNodeMetadata::create(std::istream &is)
+{
+	FurnaceNodeMetadata *d = new FurnaceNodeMetadata();
+
+	d->m_inventory->deSerialize(is);
+
+	int temp;
+	is>>temp;
+	d->m_fuel_totaltime = (float)temp/10;
+	is>>temp;
+	d->m_fuel_time = (float)temp/10;
+
+	return d;
+}
+void FurnaceNodeMetadata::serializeBody(std::ostream &os)
+{
+	m_inventory->serialize(os);
+	os<<itos(m_fuel_totaltime*10)<<" ";
+	os<<itos(m_fuel_time*10)<<" ";
+}
+std::string FurnaceNodeMetadata::infoText()
+{
+	//return "Furnace";
+	if(m_fuel_time >= m_fuel_totaltime)
+	{
+		InventoryList *src_list = m_inventory->getList("src");
+		assert(src_list);
+		InventoryItem *src_item = src_list->getItem(0);
+
+		if(src_item)
+			return "Furnace is out of fuel";
+		else
+			return "Furnace is inactive";
+	}
+	else
+	{
+		std::string s = "Furnace is active (";
+		s += itos(m_fuel_time/m_fuel_totaltime*100);
+		s += "%)";
+		return s;
+	}
+}
+void FurnaceNodeMetadata::inventoryModified()
+{
+	dstream<<"Furnace inventory modification callback"<<std::endl;
+}
+bool FurnaceNodeMetadata::step(float dtime)
+{
+	if(dtime > 60.0)
+		dstream<<"Furnace stepping a long time ("<<dtime<<")"<<std::endl;
+	// Update at a fixed frequency
+	const float interval = 2.0;
+	m_step_accumulator += dtime;
+	bool changed = false;
+	while(m_step_accumulator > interval)
+	{
+		m_step_accumulator -= interval;
+		dtime = interval;
+
+		//dstream<<"Furnace step dtime="<<dtime<<std::endl;
+		
+		InventoryList *dst_list = m_inventory->getList("dst");
+		assert(dst_list);
+
+		InventoryList *src_list = m_inventory->getList("src");
+		assert(src_list);
+		InventoryItem *src_item = src_list->getItem(0);
+		
+		// Start only if there are free slots in dst, so that it can
+		// accomodate any result item
+		if(dst_list->getFreeSlots() > 0 && src_item && src_item->isCookable())
+		{
+			m_src_totaltime = 3;
+		}
+		else
+		{
+			m_src_time = 0;
+			m_src_totaltime = 0;
+		}
+		
+		/*
+			If fuel is burning, increment the burn counters.
+			If item finishes cooking, move it to result.
+		*/
+		if(m_fuel_time < m_fuel_totaltime)
+		{
+			//dstream<<"Furnace is active"<<std::endl;
+			m_fuel_time += dtime;
+			m_src_time += dtime;
+			if(m_src_time >= m_src_totaltime && m_src_totaltime > 0.001
+					&& src_item)
+			{
+				InventoryItem *cookresult = src_item->createCookResult();
+				dst_list->addItem(cookresult);
+				src_list->decrementMaterials(1);
+				m_src_time = 0;
+				m_src_totaltime = 0;
+			}
+			changed = true;
+			continue;
+		}
+		
+		/*
+			If there is no source item or source item is not cookable, stop loop.
+		*/
+		if(src_item == NULL || m_src_totaltime < 0.001)
+		{
+			m_step_accumulator = 0;
+			break;
+		}
+		
+		//dstream<<"Furnace is out of fuel"<<std::endl;
+
+		InventoryList *fuel_list = m_inventory->getList("fuel");
+		assert(fuel_list);
+		InventoryItem *fuel_item = fuel_list->getItem(0);
+
+		if(ItemSpec(ITEM_MATERIAL, CONTENT_TREE).checkItem(fuel_item))
+		{
+			m_fuel_totaltime = 30;
+			m_fuel_time = 0;
+			fuel_list->decrementMaterials(1);
+			changed = true;
+		}
+		else if(ItemSpec(ITEM_MATERIAL, CONTENT_WOOD).checkItem(fuel_item))
+		{
+			m_fuel_totaltime = 30/4;
+			m_fuel_time = 0;
+			fuel_list->decrementMaterials(1);
+			changed = true;
+		}
+		else if(ItemSpec(ITEM_CRAFT, "Stick").checkItem(fuel_item))
+		{
+			m_fuel_totaltime = 30/4/4;
+			m_fuel_time = 0;
+			fuel_list->decrementMaterials(1);
+			changed = true;
+		}
+		else if(ItemSpec(ITEM_CRAFT, "lump_of_coal").checkItem(fuel_item))
+		{
+			m_fuel_totaltime = 40;
+			m_fuel_time = 0;
+			fuel_list->decrementMaterials(1);
+			changed = true;
+		}
+		else
+		{
+			//dstream<<"No fuel found"<<std::endl;
+			// No fuel, stop loop.
+			m_step_accumulator = 0;
+			break;
+		}
+	}
+	return changed;
+}
+std::string FurnaceNodeMetadata::getInventoryDrawSpecString()
+{
+	return
+		"invsize[8,9;]"
+		"list[current_name;fuel;2,3;1,1;]"
+		"list[current_name;src;2,1;1,1;]"
+		"list[current_name;dst;5,1;2,2;]"
+		"list[current_player;main;0,5;8,4;]";
+}
+
+
diff --git a/src/content_nodemeta.h b/src/content_nodemeta.h
new file mode 100644
index 000000000..84c3aed9d
--- /dev/null
+++ b/src/content_nodemeta.h
@@ -0,0 +1,92 @@
+/*
+Minetest-c55
+Copyright (C) 2010-2011 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#ifndef CONTENT_NODEMETA_HEADER
+#define CONTENT_NODEMETA_HEADER
+
+#include "nodemetadata.h"
+
+class Inventory;
+
+class SignNodeMetadata : public NodeMetadata
+{
+public:
+	SignNodeMetadata(std::string text);
+	//~SignNodeMetadata();
+	
+	virtual u16 typeId() const;
+	static NodeMetadata* create(std::istream &is);
+	virtual NodeMetadata* clone();
+	virtual void serializeBody(std::ostream &os);
+	virtual std::string infoText();
+
+	std::string getText(){ return m_text; }
+	void setText(std::string t){ m_text = t; }
+
+private:
+	std::string m_text;
+};
+
+class ChestNodeMetadata : public NodeMetadata
+{
+public:
+	ChestNodeMetadata();
+	~ChestNodeMetadata();
+	
+	virtual u16 typeId() const;
+	static NodeMetadata* create(std::istream &is);
+	virtual NodeMetadata* clone();
+	virtual void serializeBody(std::ostream &os);
+	virtual std::string infoText();
+	virtual Inventory* getInventory() {return m_inventory;}
+	virtual bool nodeRemovalDisabled();
+	virtual std::string getInventoryDrawSpecString();
+	
+private:
+	Inventory *m_inventory;
+};
+
+class FurnaceNodeMetadata : public NodeMetadata
+{
+public:
+	FurnaceNodeMetadata();
+	~FurnaceNodeMetadata();
+	
+	virtual u16 typeId() const;
+	virtual NodeMetadata* clone();
+	static NodeMetadata* create(std::istream &is);
+	virtual void serializeBody(std::ostream &os);
+	virtual std::string infoText();
+	virtual Inventory* getInventory() {return m_inventory;}
+	virtual void inventoryModified();
+	virtual bool step(float dtime);
+	virtual std::string getInventoryDrawSpecString();
+
+private:
+	Inventory *m_inventory;
+	float m_step_accumulator;
+	float m_fuel_totaltime;
+	float m_fuel_time;
+	float m_src_totaltime;
+	float m_src_time;
+};
+
+
+#endif
+
diff --git a/src/defaultsettings.cpp b/src/defaultsettings.cpp
index e2ace0fe2..74d323237 100644
--- a/src/defaultsettings.cpp
+++ b/src/defaultsettings.cpp
@@ -49,7 +49,7 @@ void set_default_settings()
 	g_settings.setDefault("wanted_fps", "30");
 	g_settings.setDefault("fps_max", "60");
 	g_settings.setDefault("viewing_range_nodes_max", "300");
-	g_settings.setDefault("viewing_range_nodes_min", "35");
+	g_settings.setDefault("viewing_range_nodes_min", "25");
 	g_settings.setDefault("screenW", "800");
 	g_settings.setDefault("screenH", "600");
 	g_settings.setDefault("address", "");
@@ -63,22 +63,28 @@ void set_default_settings()
 	g_settings.setDefault("enable_texture_atlas", "true");
 	g_settings.setDefault("texture_path", "");
 	g_settings.setDefault("video_driver", "opengl");
-	
 	g_settings.setDefault("free_move", "false");
 	g_settings.setDefault("continuous_forward", "false");
 	g_settings.setDefault("fast_move", "false");
+	g_settings.setDefault("invert_mouse", "false");
+	g_settings.setDefault("enable_farmesh", "false");
+	g_settings.setDefault("enable_clouds", "true");
+	g_settings.setDefault("invisible_stone", "false");
 
 	// Server stuff
 	g_settings.setDefault("enable_experimental", "false");
 	g_settings.setDefault("creative_mode", "false");
-	g_settings.setDefault("enable_damage", "false"); //TODO: Set to true
+	g_settings.setDefault("enable_damage", "false"); //TODO: Set to true when healing is possible
 	g_settings.setDefault("give_initial_stuff", "false");
+	g_settings.setDefault("default_password", "");
+	g_settings.setDefault("default_privs", "build, shout");
+	g_settings.setDefault("profiler_print_interval", "0");
 
 	g_settings.setDefault("objectdata_interval", "0.2");
 	g_settings.setDefault("active_object_range", "2");
-	g_settings.setDefault("max_simultaneous_block_sends_per_client", "1");
-	//g_settings.setDefault("max_simultaneous_block_sends_per_client", "2");
-	g_settings.setDefault("max_simultaneous_block_sends_server_total", "4");
+	//g_settings.setDefault("max_simultaneous_block_sends_per_client", "1");
+	g_settings.setDefault("max_simultaneous_block_sends_per_client", "2");
+	g_settings.setDefault("max_simultaneous_block_sends_server_total", "8");
 	g_settings.setDefault("max_block_send_distance", "8");
 	g_settings.setDefault("max_block_generate_distance", "8");
 	g_settings.setDefault("time_send_interval", "20");
@@ -86,5 +92,6 @@ void set_default_settings()
 	g_settings.setDefault("server_unload_unused_sectors_timeout", "60");
 	g_settings.setDefault("server_map_save_interval", "60");
 	g_settings.setDefault("full_block_send_enable_min_time_from_building", "2.0");
+	//g_settings.setDefault("dungeon_rarity", "0.025");
 }
 
diff --git a/src/environment.cpp b/src/environment.cpp
index 3ebfef0c5..e2c704259 100644
--- a/src/environment.cpp
+++ b/src/environment.cpp
@@ -21,6 +21,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "filesys.h"
 #include "porting.h"
 #include "collision.h"
+#include "content_mapnode.h"
 
 
 Environment::Environment():
@@ -426,7 +427,14 @@ void ServerEnvironment::deSerializePlayers(const std::string &savedir)
 			testplayer.deSerialize(is);
 		}
 
-		dstream<<"Loaded test player with name "<<testplayer.getName()<<std::endl;
+		if(!string_allowed(testplayer.getName(), PLAYERNAME_ALLOWED_CHARS))
+		{
+			dstream<<"Not loading player with invalid name: "
+					<<testplayer.getName()<<std::endl;
+		}
+
+		dstream<<"Loaded test player with name "<<testplayer.getName()
+				<<std::endl;
 		
 		// Search for the player
 		std::string playername = testplayer.getName();
@@ -571,6 +579,66 @@ void spawnRandomObjects(MapBlock *block)
 }
 #endif
 
+void ServerEnvironment::activateBlock(MapBlock *block, u32 additional_dtime)
+{
+	// Get time difference
+	u32 dtime_s = 0;
+	u32 stamp = block->getTimestamp();
+	if(m_game_time > stamp && stamp != BLOCK_TIMESTAMP_UNDEFINED)
+		dtime_s = m_game_time - block->getTimestamp();
+	dtime_s += additional_dtime;
+
+	// Set current time as timestamp (and let it set ChangedFlag)
+	block->setTimestamp(m_game_time);
+
+	//dstream<<"Block is "<<dtime_s<<" seconds old."<<std::endl;
+
+	// Activate stored objects
+	activateObjects(block);
+
+	// Run node metadata
+	bool changed = block->m_node_metadata.step((float)dtime_s);
+	if(changed)
+	{
+		MapEditEvent event;
+		event.type = MEET_BLOCK_NODE_METADATA_CHANGED;
+		event.p = block->getPos();
+		m_map->dispatchEvent(&event);
+
+		block->setChangedFlag();
+	}
+
+	// TODO: Do something
+	// TODO: Implement usage of ActiveBlockModifier
+
+	// Here's a quick demonstration
+	v3s16 p0;
+	for(p0.X=0; p0.X<MAP_BLOCKSIZE; p0.X++)
+	for(p0.Y=0; p0.Y<MAP_BLOCKSIZE; p0.Y++)
+	for(p0.Z=0; p0.Z<MAP_BLOCKSIZE; p0.Z++)
+	{
+		v3s16 p = p0 + block->getPosRelative();
+		MapNode n = block->getNodeNoEx(p0);
+#if 1
+		// Test something:
+		// Convert all mud under proper day lighting to grass
+		if(n.d == CONTENT_MUD)
+		{
+			if(dtime_s > 300)
+			{
+				MapNode n_top = block->getNodeNoEx(p0+v3s16(0,1,0));
+				if(content_features(n_top.d).air_equivalent &&
+						n_top.getLight(LIGHTBANK_DAY) >= 13)
+				{
+					n.d = CONTENT_GRASS;
+					m_map->addNodeWithEvent(p, n);
+				}
+			}
+		}
+#endif
+	}
+}
+
 void ServerEnvironment::step(float dtime)
 {
 	DSTACK(__FUNCTION_NAME);
@@ -686,8 +754,8 @@ void ServerEnvironment::step(float dtime)
 			MapBlock *block = m_map->getBlockNoCreateNoEx(p);
 			if(block==NULL)
 				continue;
-			
-			// Set current time as timestamp
+			// Set current time as timestamp (and let it set ChangedFlag)
+
 			block->setTimestamp(m_game_time);
 		}
 
@@ -707,23 +775,36 @@ void ServerEnvironment::step(float dtime)
 			MapBlock *block = m_map->getBlockNoCreateNoEx(p);
 			if(block==NULL)
 				continue;
-			
+
 			// Get time difference
 			u32 dtime_s = 0;
 			u32 stamp = block->getTimestamp();
 			if(m_game_time > stamp && stamp != BLOCK_TIMESTAMP_UNDEFINED)
 				dtime_s = m_game_time - block->getTimestamp();
 
-			// Set current time as timestamp
+			// Set current time as timestamp (and let it set ChangedFlag)
 			block->setTimestamp(m_game_time);
 
 			//dstream<<"Block is "<<dtime_s<<" seconds old."<<std::endl;
-			
+
 			// Activate stored objects
 			activateObjects(block);
 
+			// Run node metadata
+			bool changed = block->m_node_metadata.step((float)dtime_s);
+			if(changed)
+			{
+				MapEditEvent event;
+				event.type = MEET_BLOCK_NODE_METADATA_CHANGED;
+				event.p = p;
+				m_map->dispatchEvent(&event);
+
+				block->setChangedFlag();
+			}
+
 			// TODO: Do something
-			
+			// TODO: Implement usage of ActiveBlockModifier
+
 			// Here's a quick demonstration
 			v3s16 p0;
 			for(p0.X=0; p0.X<MAP_BLOCKSIZE; p0.X++)
@@ -736,7 +817,7 @@ void ServerEnvironment::step(float dtime)
 				// Convert all mud under proper day lighting to grass
 				if(n.d == CONTENT_MUD)
 				{
-					if(1)
+					if(dtime_s > 300)
 					{
 						MapNode n_top = block->getNodeNoEx(p0+v3s16(0,1,0));
 						if(content_features(n_top.d).air_equivalent &&
@@ -747,6 +828,22 @@ void ServerEnvironment::step(float dtime)
 						}
 					}
 				}
+				/*
+					Convert grass into mud if under something else than air
+				*/
+				else if(n.d == CONTENT_GRASS)
+				{
+					//if(myrand()%20 == 0)
+					{
+						MapNode n_top = block->getNodeNoEx(p0+v3s16(0,1,0));
+						if(n_top.d != CONTENT_AIR
+								&& n_top.d != CONTENT_IGNORE)
+						{
+							n.d = CONTENT_MUD;
+							m_map->addNodeWithEvent(p, n);
+						}
+					}
+				}
 			}
 		}
 	}
@@ -754,8 +851,10 @@ void ServerEnvironment::step(float dtime)
 	/*
 		Mess around in active blocks
 	*/
-	if(m_active_blocks_test_interval.step(dtime, 5.0))
+	if(m_active_blocks_nodemetadata_interval.step(dtime, 1.0))
 	{
+		float dtime = 1.0;
+
 		for(core::map<v3s16, bool>::Iterator
 				i = m_active_blocks.m_list.getIterator();
 				i.atEnd()==false; i++)
@@ -770,8 +869,41 @@ void ServerEnvironment::step(float dtime)
 				continue;
 			
 			// Set current time as timestamp
-			block->setTimestamp(m_game_time);
+			block->setTimestampNoChangedFlag(m_game_time);
+
+			// Run node metadata
+			bool changed = block->m_node_metadata.step(dtime);
+			if(changed)
+			{
+				MapEditEvent event;
+				event.type = MEET_BLOCK_NODE_METADATA_CHANGED;
+				event.p = p;
+				m_map->dispatchEvent(&event);
+
+				block->setChangedFlag();
+			}
+		}
+	}
+	if(m_active_blocks_test_interval.step(dtime, 10.0))
+	{
+		//float dtime = 10.0;
+
+		for(core::map<v3s16, bool>::Iterator
+				i = m_active_blocks.m_list.getIterator();
+				i.atEnd()==false; i++)
+		{
+			v3s16 p = i.getNode()->getKey();
 			
+			/*dstream<<"Server: Block ("<<p.X<<","<<p.Y<<","<<p.Z
+					<<") being handled"<<std::endl;*/
+
+			MapBlock *block = m_map->getBlockNoCreateNoEx(p);
+			if(block==NULL)
+				continue;
+			
+			// Set current time as timestamp
+			block->setTimestampNoChangedFlag(m_game_time);
+
 			/*
 				Do stuff!
 
@@ -784,6 +916,7 @@ void ServerEnvironment::step(float dtime)
 				Everything should bind to inside this single content
 				searching loop to keep things fast.
 			*/
+			// TODO: Implement usage of ActiveBlockModifier
 
 			v3s16 p0;
 			for(p0.X=0; p0.X<MAP_BLOCKSIZE; p0.X++)
@@ -792,11 +925,14 @@ void ServerEnvironment::step(float dtime)
 			{
 				v3s16 p = p0 + block->getPosRelative();
 				MapNode n = block->getNodeNoEx(p0);
-				// Test something:
-				// Convert mud under proper lighting to grass
+
+				/*
+					Test something:
+					Convert mud under proper lighting to grass
+				*/
 				if(n.d == CONTENT_MUD)
 				{
-					if(myrand()%10 == 0)
+					if(myrand()%20 == 0)
 					{
 						MapNode n_top = block->getNodeNoEx(p0+v3s16(0,1,0));
 						if(content_features(n_top.d).air_equivalent &&
@@ -807,6 +943,22 @@ void ServerEnvironment::step(float dtime)
 						}
 					}
 				}
+				/*
+					Convert grass into mud if under something else than air
+				*/
+				else if(n.d == CONTENT_GRASS)
+				{
+					//if(myrand()%20 == 0)
+					{
+						MapNode n_top = block->getNodeNoEx(p0+v3s16(0,1,0));
+						if(n_top.d != CONTENT_AIR
+								&& n_top.d != CONTENT_IGNORE)
+						{
+							n.d = CONTENT_MUD;
+							m_map->addNodeWithEvent(p, n);
+						}
+						}
+					}
 			}
 		}
 	}
@@ -941,49 +1093,8 @@ u16 getFreeServerActiveObjectId(
 u16 ServerEnvironment::addActiveObject(ServerActiveObject *object)
 {
 	assert(object);
-	if(object->getId() == 0)
-	{
-		u16 new_id = getFreeServerActiveObjectId(m_active_objects);
-		if(new_id == 0)
-		{
-			dstream<<"WARNING: ServerEnvironment::addActiveObject(): "
-					<<"no free ids available"<<std::endl;
-			delete object;
-			return 0;
-		}
-		object->setId(new_id);
-	}
-	if(isFreeServerActiveObjectId(object->getId(), m_active_objects) == false)
-	{
-		dstream<<"WARNING: ServerEnvironment::addActiveObject(): "
-				<<"id is not free ("<<object->getId()<<")"<<std::endl;
-		delete object;
-		return 0;
-	}
-	/*dstream<<"INGO: ServerEnvironment::addActiveObject(): "
-			<<"added (id="<<object->getId()<<")"<<std::endl;*/
-			
-	m_active_objects.insert(object->getId(), object);
-
-	// Add static object to active static list of the block
-	v3f objectpos = object->getBasePosition();
-	std::string staticdata = object->getStaticData();
-	StaticObject s_obj(object->getType(), objectpos, staticdata);
-	// Add to the block where the object is located in
-	v3s16 blockpos = getNodeBlockPos(floatToInt(objectpos, BS));
-	MapBlock *block = m_map->getBlockNoCreateNoEx(blockpos);
-	if(block)
-	{
-		block->m_static_objects.m_active.insert(object->getId(), s_obj);
-		object->m_static_exists = true;
-		object->m_static_block = blockpos;
-	}
-	else{
-		dstream<<"WARNING: Server: Could not find a block for "
-				<<"storing newly added static active object"<<std::endl;
-	}
-
-	return object->getId();
+	u16 id = addActiveObjectRaw(object, true);
+	return id;
 }
 
 /*
@@ -1086,6 +1197,58 @@ ActiveObjectMessage ServerEnvironment::getActiveObjectMessage()
 	************ Private methods *************
 */
 
+u16 ServerEnvironment::addActiveObjectRaw(ServerActiveObject *object,
+		bool set_changed)
+{
+	assert(object);
+	if(object->getId() == 0)
+	{
+		u16 new_id = getFreeServerActiveObjectId(m_active_objects);
+		if(new_id == 0)
+		{
+			dstream<<"WARNING: ServerEnvironment::addActiveObjectRaw(): "
+					<<"no free ids available"<<std::endl;
+			delete object;
+			return 0;
+		}
+		object->setId(new_id);
+	}
+	if(isFreeServerActiveObjectId(object->getId(), m_active_objects) == false)
+	{
+		dstream<<"WARNING: ServerEnvironment::addActiveObjectRaw(): "
+				<<"id is not free ("<<object->getId()<<")"<<std::endl;
+		delete object;
+		return 0;
+	}
+	/*dstream<<"INGO: ServerEnvironment::addActiveObjectRaw(): "
+			<<"added (id="<<object->getId()<<")"<<std::endl;*/
+			
+	m_active_objects.insert(object->getId(), object);
+
+	// Add static object to active static list of the block
+	v3f objectpos = object->getBasePosition();
+	std::string staticdata = object->getStaticData();
+	StaticObject s_obj(object->getType(), objectpos, staticdata);
+	// Add to the block where the object is located in
+	v3s16 blockpos = getNodeBlockPos(floatToInt(objectpos, BS));
+	MapBlock *block = m_map->getBlockNoCreateNoEx(blockpos);
+	if(block)
+	{
+		block->m_static_objects.m_active.insert(object->getId(), s_obj);
+		object->m_static_exists = true;
+		object->m_static_block = blockpos;
+
+		if(set_changed)
+			block->setChangedFlag();
+	}
+	else{
+		dstream<<"WARNING: Server: Could not find a block for "
+				<<"storing newly added static active object"<<std::endl;
+	}
+
+	return object->getId();
+}
+
 /*
 	Remove objects that satisfy (m_removed && m_known_by_count==0)
 */
@@ -1176,8 +1339,8 @@ void ServerEnvironment::activateObjects(MapBlock *block)
 			continue;
 		}
 		// This will also add the object to the active static list
-		addActiveObject(obj);
-		//u16 id = addActiveObject(obj);
+		addActiveObjectRaw(obj, false);
+		//u16 id = addActiveObjectRaw(obj, false);
 	}
 	// Clear stored list
 	block->m_static_objects.m_stored.clear();
@@ -1190,7 +1353,8 @@ void ServerEnvironment::activateObjects(MapBlock *block)
 		block->m_static_objects.m_stored.push_back(s_obj);
 	}
 	// Block has been modified
-	block->setChangedFlag();
+	// NOTE: No it has not really. Save I/O here.
+	//block->setChangedFlag();
 }
 
 /*
diff --git a/src/environment.h b/src/environment.h
index ac290f932..eac69d222 100644
--- a/src/environment.h
+++ b/src/environment.h
@@ -113,25 +113,6 @@ private:
 };
 
 /*
-	Active block modifier interface
-*/
-
-class ServerEnvironment;
-
-class ActiveBlockModifier
-{
-public:
-	ActiveBlockModifier(){};
-	virtual ~ActiveBlockModifier(){};
-	
-	virtual u32 getTriggerContentCount(){ return 1;}
-	virtual u8 getTriggerContent(u32 i) = 0;
-	virtual float getActiveInterval() = 0;
-	virtual u32 getActiveChance() = 0;
-	virtual void triggerEvent(ServerEnvironment *env, v3s16 p) = 0;
-};
-
-/*
 	The server-side environment.
 
 	This is not thread-safe. Server uses an environment mutex.
@@ -140,6 +121,7 @@ public:
 #include "serverobject.h"
 
 class Server;
+class ActiveBlockModifier;
 
 class ServerEnvironment : public Environment
 {
@@ -177,7 +159,8 @@ public:
 	void loadMeta(const std::string &savedir);
 
 	/*
-		ActiveObjects
+		External ActiveObject interface
+		-------------------------------------------
 	*/
 
 	ServerActiveObject* getActiveObject(u16 id);
@@ -214,7 +197,38 @@ public:
 	*/
 	ActiveObjectMessage getActiveObjectMessage();
 
+	/*
+		Activate objects and dynamically modify for the dtime determined
+		from timestamp and additional_dtime
+	*/
+	void activateBlock(MapBlock *block, u32 additional_dtime=0);
+
+	/*
+		ActiveBlockModifiers (TODO)
+		-------------------------------------------
+	*/
+
+	void addActiveBlockModifier(ActiveBlockModifier *abm);
+
 private:
+
+	/*
+		Internal ActiveObject interface
+		-------------------------------------------
+	*/
+
+	/*
+		Add an active object to the environment.
+
+		Called by addActiveObject.
+
+		Object may be deleted by environment immediately.
+		If id of object is 0, assigns a free id to it.
+		Returns the id of the object.
+		Returns 0 if not added and thus deleted.
+	*/
+	u16 addActiveObjectRaw(ServerActiveObject *object, bool set_changed);
+	
 	/*
 		Remove all objects that satisfy (m_removed && m_known_by_count==0)
 	*/
@@ -256,6 +270,7 @@ private:
 	ActiveBlockList m_active_blocks;
 	IntervalLimiter m_active_blocks_management_interval;
 	IntervalLimiter m_active_blocks_test_interval;
+	IntervalLimiter m_active_blocks_nodemetadata_interval;
 	// Time from the beginning of the game in seconds.
 	// Incremented in step().
 	u32 m_game_time;
@@ -263,6 +278,29 @@ private:
 	float m_game_time_fraction_counter;
 };
 
+/*
+	Active block modifier interface.
+
+	These are fed into ServerEnvironment at initialization time;
+	ServerEnvironment handles deleting them.
+*/
+
+class ActiveBlockModifier
+{
+public:
+	ActiveBlockModifier(){};
+	virtual ~ActiveBlockModifier(){};
+
+	//virtual core::list<u8> update(ServerEnvironment *env) = 0;
+	virtual u32 getTriggerContentCount(){ return 1;}
+	virtual u8 getTriggerContent(u32 i) = 0;
+	virtual float getActiveInterval() = 0;
+	// chance of (1 / return value), 0 is disallowed
+	virtual u32 getActiveChance() = 0;
+	// This is called usually at interval for 1/chance of the nodes
+	virtual void triggerEvent(ServerEnvironment *env, v3s16 p) = 0;
+};
+
 #ifndef SERVER
 
 #include "clientobject.h"
diff --git a/src/farmesh.cpp b/src/farmesh.cpp
new file mode 100644
index 000000000..72dbe11c2
--- /dev/null
+++ b/src/farmesh.cpp
@@ -0,0 +1,413 @@
+/*
+Part of Minetest-c55
+Copyright (C) 2011 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+/*
+	A quick messy implementation of terrain rendering for a long
+	distance according to map seed
+*/
+
+#include "farmesh.h"
+#include "constants.h"
+#include "debug.h"
+#include "noise.h"
+#include "map.h"
+#include "client.h"
+
+#include "mapgen.h"
+
+FarMesh::FarMesh(
+		scene::ISceneNode* parent,
+		scene::ISceneManager* mgr,
+		s32 id,
+		u64 seed,
+		Client *client
+):
+	scene::ISceneNode(parent, mgr, id),
+	m_seed(seed),
+	m_camera_pos(0,0),
+	m_time(0),
+	m_client(client),
+	m_render_range(20*MAP_BLOCKSIZE)
+{
+	dstream<<__FUNCTION_NAME<<std::endl;
+	
+	video::IVideoDriver* driver = mgr->getVideoDriver();
+
+	m_materials[0].setFlag(video::EMF_LIGHTING, false);
+	m_materials[0].setFlag(video::EMF_BACK_FACE_CULLING, true);
+	//m_materials[0].setFlag(video::EMF_BACK_FACE_CULLING, false);
+	m_materials[0].setFlag(video::EMF_BILINEAR_FILTER, false);
+	m_materials[0].setFlag(video::EMF_FOG_ENABLE, false);
+	//m_materials[0].setFlag(video::EMF_ANTI_ALIASING, true);
+	//m_materials[0].MaterialType = video::EMT_TRANSPARENT_VERTEX_ALPHA;
+	m_materials[0].setFlag(video::EMF_FOG_ENABLE, true);
+	
+	m_materials[1].setFlag(video::EMF_LIGHTING, false);
+	m_materials[1].setFlag(video::EMF_BACK_FACE_CULLING, false);
+	m_materials[1].setFlag(video::EMF_BILINEAR_FILTER, false);
+	m_materials[1].setFlag(video::EMF_FOG_ENABLE, false);
+	m_materials[1].setTexture
+			(0, driver->getTexture(getTexturePath("treeprop.png").c_str()));
+	m_materials[1].MaterialType = video::EMT_TRANSPARENT_ALPHA_CHANNEL_REF;
+	m_materials[1].setFlag(video::EMF_FOG_ENABLE, true);
+
+	m_box = core::aabbox3d<f32>(-BS*1000000,-BS*31000,-BS*1000000,
+			BS*1000000,BS*31000,BS*1000000);
+
+}
+
+FarMesh::~FarMesh()
+{
+	dstream<<__FUNCTION_NAME<<std::endl;
+}
+
+u32 FarMesh::getMaterialCount() const
+{
+	return FARMESH_MATERIAL_COUNT;
+}
+
+video::SMaterial& FarMesh::getMaterial(u32 i)
+{
+	return m_materials[i];
+}
+	
+
+void FarMesh::OnRegisterSceneNode()
+{
+	if(IsVisible)
+	{
+		//SceneManager->registerNodeForRendering(this, scene::ESNRP_TRANSPARENT);
+		SceneManager->registerNodeForRendering(this, scene::ESNRP_SOLID);
+		//SceneManager->registerNodeForRendering(this, scene::ESNRP_SKY_BOX);
+	}
+
+	ISceneNode::OnRegisterSceneNode();
+}
+
+#define MYROUND(x) (x > 0.0 ? (int)x : (int)x - 1)
+
+// Temporary hack
+struct HeightPoint
+{
+	float gh; // ground height
+	float ma; // mud amount
+	float have_sand;
+	float tree_amount;
+};
+core::map<v2s16, HeightPoint> g_heights;
+
+HeightPoint ground_height(u64 seed, v2s16 p2d)
+{
+	core::map<v2s16, HeightPoint>::Node *n = g_heights.find(p2d);
+	if(n)
+		return n->getValue();
+	HeightPoint hp;
+	s16 level = mapgen::find_ground_level_from_noise(seed, p2d, 3);
+	hp.gh = (level-4)*BS;
+	hp.ma = (4)*BS;
+	/*hp.gh = BS*base_rock_level_2d(seed, p2d);
+	hp.ma = BS*get_mud_add_amount(seed, p2d);*/
+	hp.have_sand = mapgen::get_have_sand(seed, p2d);
+	if(hp.gh > BS*WATER_LEVEL)
+		hp.tree_amount = mapgen::tree_amount_2d(seed, p2d);
+	else
+		hp.tree_amount = 0;
+	// No mud has been added if mud amount is less than 1
+	if(hp.ma < 1.0*BS)
+		hp.ma = 0.0;
+	//hp.gh -= BS*3; // Lower a bit so that it is not that much in the way
+	g_heights[p2d] = hp;
+	return hp;
+}
+
+void FarMesh::render()
+{
+	video::IVideoDriver* driver = SceneManager->getVideoDriver();
+
+	/*if(SceneManager->getSceneNodeRenderPass() != scene::ESNRP_TRANSPARENT)
+		return;*/
+	if(SceneManager->getSceneNodeRenderPass() != scene::ESNRP_SOLID)
+		return;
+	/*if(SceneManager->getSceneNodeRenderPass() != scene::ESNRP_SKY_BOX)
+		return;*/
+
+	driver->setTransform(video::ETS_WORLD, AbsoluteTransformation);
+	
+	//const s16 grid_radius_i = 12;
+	//const float grid_size = BS*50;
+	const s16 grid_radius_i = m_render_range/MAP_BLOCKSIZE;
+	const float grid_size = BS*MAP_BLOCKSIZE;
+	const v2f grid_speed(-BS*0, 0);
+	
+	// Position of grid noise origin in world coordinates
+	v2f world_grid_origin_pos_f(0,0);
+	// Position of grid noise origin from the camera
+	v2f grid_origin_from_camera_f = world_grid_origin_pos_f - m_camera_pos;
+	// The center point of drawing in the noise
+	v2f center_of_drawing_in_noise_f = -grid_origin_from_camera_f;
+	// The integer center point of drawing in the noise
+	v2s16 center_of_drawing_in_noise_i(
+		MYROUND(center_of_drawing_in_noise_f.X / grid_size),
+		MYROUND(center_of_drawing_in_noise_f.Y / grid_size)
+	);
+	// The world position of the integer center point of drawing in the noise
+	v2f world_center_of_drawing_in_noise_f = v2f(
+		center_of_drawing_in_noise_i.X * grid_size,
+		center_of_drawing_in_noise_i.Y * grid_size
+	) + world_grid_origin_pos_f;
+
+	for(s16 zi=-grid_radius_i; zi<grid_radius_i; zi++)
+	for(s16 xi=-grid_radius_i; xi<grid_radius_i; xi++)
+	{
+		/*// Don't draw very close to player
+		s16 dd = 3;
+		if(zi > -dd && zi < dd && xi > -dd && xi < dd)
+			continue;*/
+
+		v2s16 p_in_noise_i(
+			xi+center_of_drawing_in_noise_i.X,
+			zi+center_of_drawing_in_noise_i.Y
+		);
+		
+		// If sector was drawn, don't draw it this way
+		if(m_client->m_env.getClientMap().sectorWasDrawn(p_in_noise_i))
+			continue;
+
+		/*if((p_in_noise_i.X + p_in_noise_i.Y)%2==0)
+			continue;*/
+		/*if((p_in_noise_i.X/2 + p_in_noise_i.Y/2)%2==0)
+			continue;*/
+
+		v2f p0 = v2f(xi,zi)*grid_size + world_center_of_drawing_in_noise_f;
+		
+		/*double noise[4];
+		double d = 100*BS;
+		noise[0] = d*noise2d_perlin(
+				(float)(p_in_noise_i.X+0)*grid_size/BS/100,
+				(float)(p_in_noise_i.Y+0)*grid_size/BS/100,
+				m_seed, 3, 0.5);
+		
+		noise[1] = d*noise2d_perlin(
+				(float)(p_in_noise_i.X+0)*grid_size/BS/100,
+				(float)(p_in_noise_i.Y+1)*grid_size/BS/100,
+				m_seed, 3, 0.5);
+		
+		noise[2] = d*noise2d_perlin(
+				(float)(p_in_noise_i.X+1)*grid_size/BS/100,
+				(float)(p_in_noise_i.Y+1)*grid_size/BS/100,
+				m_seed, 3, 0.5);
+		
+		noise[3] = d*noise2d_perlin(
+				(float)(p_in_noise_i.X+1)*grid_size/BS/100,
+				(float)(p_in_noise_i.Y+0)*grid_size/BS/100,
+				m_seed, 3, 0.5);*/
+		
+		HeightPoint hps[5];
+		hps[0] = ground_height(m_seed, v2s16(
+				(p_in_noise_i.X+0)*grid_size/BS,
+				(p_in_noise_i.Y+0)*grid_size/BS));
+		hps[1] = ground_height(m_seed, v2s16(
+				(p_in_noise_i.X+0)*grid_size/BS,
+				(p_in_noise_i.Y+1)*grid_size/BS));
+		hps[2] = ground_height(m_seed, v2s16(
+				(p_in_noise_i.X+1)*grid_size/BS,
+				(p_in_noise_i.Y+1)*grid_size/BS));
+		hps[3] = ground_height(m_seed, v2s16(
+				(p_in_noise_i.X+1)*grid_size/BS,
+				(p_in_noise_i.Y+0)*grid_size/BS));
+		v2s16 centerpoint(
+				(p_in_noise_i.X+0)*grid_size/BS+MAP_BLOCKSIZE/2,
+				(p_in_noise_i.Y+0)*grid_size/BS+MAP_BLOCKSIZE/2);
+		hps[4] = ground_height(m_seed, centerpoint);
+		
+		float noise[5];
+		float h_min = BS*65535;
+		float h_max = -BS*65536;
+		float ma_avg = 0;
+		float h_avg = 0;
+		u32 have_sand_count = 0;
+		float tree_amount_avg = 0;
+		for(u32 i=0; i<5; i++)
+		{
+			noise[i] = hps[i].gh + hps[i].ma;
+			if(noise[i] < h_min)
+				h_min = noise[i];
+			if(noise[i] > h_max)
+				h_max = noise[i];
+			ma_avg += hps[i].ma;
+			h_avg += noise[i];
+			if(hps[i].have_sand)
+				have_sand_count++;
+			tree_amount_avg += hps[i].tree_amount;
+		}
+		ma_avg /= 5.0;
+		h_avg /= 5.0;
+		tree_amount_avg /= 5.0;
+
+		float steepness = (h_max - h_min)/grid_size;
+		
+		float light_f = noise[0]+noise[1]-noise[2]-noise[3];
+		light_f /= 100;
+		if(light_f < -1.0) light_f = -1.0;
+		if(light_f > 1.0) light_f = 1.0;
+		//light_f += 1.0;
+		//light_f /= 2.0;
+		
+		v2f p1 = p0 + v2f(1,1)*grid_size;
+		
+		bool ground_is_sand = false;
+		bool ground_is_rock = false;
+		bool ground_is_mud = false;
+		video::SColor c;
+		// Detect water
+		if(h_avg < WATER_LEVEL*BS && h_max < (WATER_LEVEL+5)*BS)
+		{
+			//c = video::SColor(255,59,86,146);
+			c = video::SColor(255,82,120,204);
+
+			/*// Set to water level
+			for(u32 i=0; i<4; i++)
+			{
+				if(noise[i] < BS*WATER_LEVEL)
+					noise[i] = BS*WATER_LEVEL;
+			}*/
+			light_f = 0;
+		}
+		// Steep cliffs
+		else if(steepness > 2.0)
+		{
+			c = video::SColor(255,128,128,128);
+			ground_is_rock = true;
+		}
+		// Basic ground
+		else
+		{
+			if(ma_avg < 2.0*BS)
+			{
+				c = video::SColor(255,128,128,128);
+				ground_is_rock = true;
+			}
+			else
+			{
+				if(h_avg <= 2.5*BS && have_sand_count >= 2)
+				{
+					c = video::SColor(255,210,194,156);
+					ground_is_sand = true;
+				}
+				else
+				{
+					/*// Trees if there are over 0.01 trees per MapNode
+					if(tree_amount_avg > 0.01)
+						c = video::SColor(255,50,128,50);
+					else
+						c = video::SColor(255,107,134,51);*/
+					c = video::SColor(255,107,134,51);
+					ground_is_mud = true;
+				}
+			}
+		}
+		
+		// Set to water level
+		for(u32 i=0; i<4; i++)
+		{
+			if(noise[i] < BS*WATER_LEVEL)
+				noise[i] = BS*WATER_LEVEL;
+		}
+
+		float b = m_brightness + light_f*0.1*m_brightness;
+		if(b < 0) b = 0;
+		if(b > 2) b = 2;
+		
+		c = video::SColor(255, b*c.getRed(), b*c.getGreen(), b*c.getBlue());
+		
+		driver->setMaterial(m_materials[0]);
+
+		video::S3DVertex vertices[4] =
+		{
+			video::S3DVertex(p0.X,noise[0],p0.Y, 0,0,0, c, 0,1),
+			video::S3DVertex(p0.X,noise[1],p1.Y, 0,0,0, c, 1,1),
+			video::S3DVertex(p1.X,noise[2],p1.Y, 0,0,0, c, 1,0),
+			video::S3DVertex(p1.X,noise[3],p0.Y, 0,0,0, c, 0,0),
+		};
+		u16 indices[] = {0,1,2,2,3,0};
+		driver->drawVertexPrimitiveList(vertices, 4, indices, 2,
+				video::EVT_STANDARD, scene::EPT_TRIANGLES, video::EIT_16BIT);
+
+		// Add some trees if appropriate
+		if(tree_amount_avg >= 0.0065 && steepness < 1.4
+				&& ground_is_mud == true)
+		{
+			driver->setMaterial(m_materials[1]);
+			
+			float b = m_brightness;
+			c = video::SColor(255, b*255, b*255, b*255);
+			
+			{
+				video::S3DVertex vertices[4] =
+				{
+					video::S3DVertex(p0.X,noise[0],p0.Y,
+							0,0,0, c, 0,1),
+					video::S3DVertex(p0.X,noise[0]+BS*MAP_BLOCKSIZE,p0.Y,
+							0,0,0, c, 0,0),
+					video::S3DVertex(p1.X,noise[2]+BS*MAP_BLOCKSIZE,p1.Y,
+							0,0,0, c, 1,0),
+					video::S3DVertex(p1.X,noise[2],p1.Y,
+							0,0,0, c, 1,1),
+				};
+				u16 indices[] = {0,1,2,2,3,0};
+				driver->drawVertexPrimitiveList(vertices, 4, indices, 2,
+						video::EVT_STANDARD, scene::EPT_TRIANGLES,
+						video::EIT_16BIT);
+			}
+			{
+				video::S3DVertex vertices[4] =
+				{
+					video::S3DVertex(p1.X,noise[3],p0.Y,
+							0,0,0, c, 0,1),
+					video::S3DVertex(p1.X,noise[3]+BS*MAP_BLOCKSIZE,p0.Y,
+							0,0,0, c, 0,0),
+					video::S3DVertex(p0.X,noise[1]+BS*MAP_BLOCKSIZE,p1.Y,
+							0,0,0, c, 1,0),
+					video::S3DVertex(p0.X,noise[1],p1.Y,
+							0,0,0, c, 1,1),
+				};
+				u16 indices[] = {0,1,2,2,3,0};
+				driver->drawVertexPrimitiveList(vertices, 4, indices, 2,
+						video::EVT_STANDARD, scene::EPT_TRIANGLES,
+						video::EIT_16BIT);
+			}
+		}
+	}
+
+	//driver->clearZBuffer();
+}
+
+void FarMesh::step(float dtime)
+{
+	m_time += dtime;
+}
+
+void FarMesh::update(v2f camera_p, float brightness, s16 render_range)
+{
+	m_camera_pos = camera_p;
+	m_brightness = brightness;
+	m_render_range = render_range;
+}
+
+
diff --git a/src/farmesh.h b/src/farmesh.h
new file mode 100644
index 000000000..0a30a8aef
--- /dev/null
+++ b/src/farmesh.h
@@ -0,0 +1,85 @@
+/*
+Part of Minetest-c55
+Copyright (C) 2010-2011 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#ifndef FARMESH_HEADER
+#define FARMESH_HEADER
+
+/*
+	A quick messy implementation of terrain rendering for a long
+	distance according to map seed
+*/
+
+#include "common_irrlicht.h"
+
+#define FARMESH_MATERIAL_COUNT 2
+
+class Client;
+
+class FarMesh : public scene::ISceneNode
+{
+public:
+	FarMesh(
+			scene::ISceneNode* parent,
+			scene::ISceneManager* mgr,
+			s32 id,
+			u64 seed,
+			Client *client
+	);
+
+	~FarMesh();
+
+	/*
+		ISceneNode methods
+	*/
+
+	virtual void OnRegisterSceneNode();
+
+	virtual void render();
+	
+	virtual const core::aabbox3d<f32>& getBoundingBox() const
+	{
+		return m_box;
+	}
+
+	virtual u32 getMaterialCount() const;
+
+	virtual video::SMaterial& getMaterial(u32 i);
+	
+	/*
+		Other stuff
+	*/
+
+	void step(float dtime);
+
+	void update(v2f camera_p, float brightness, s16 render_range);
+
+private:
+	video::SMaterial m_materials[FARMESH_MATERIAL_COUNT];
+	core::aabbox3d<f32> m_box;
+	float m_cloud_y;
+	float m_brightness;
+	u64 m_seed;
+	v2f m_camera_pos;
+	float m_time;
+	Client *m_client;
+	s16 m_render_range;
+};
+
+#endif
+
diff --git a/src/game.cpp b/src/game.cpp
index bbd0a22ef..5632c1805 100644
--- a/src/game.cpp
+++ b/src/game.cpp
@@ -25,11 +25,15 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "guiPasswordChange.h"
 #include "guiInventoryMenu.h"
 #include "guiTextInputMenu.h"
-#include "guiFurnaceMenu.h"
 #include "materials.h"
 #include "config.h"
 #include "clouds.h"
 #include "keycode.h"
+#include "farmesh.h"
+
+// TODO: Move content-aware stuff to separate file
+#include "content_mapnode.h"
+#include "content_nodemeta.h"
 
 /*
 	Setting this to 1 enables a special camera mode that forces
@@ -358,7 +362,7 @@ void draw_hotbar(video::IVideoDriver *driver, gui::IGUIFont *font,
 				core::rect<s32>(core::position2d<s32>(0,0),
 				core::dimension2di(heart_texture->getOriginalSize())),
 				NULL, colors, true);
-			p += v2s32(20,0);
+			p += v2s32(16,0);
 		}
 		if(halfheartcount % 2 == 1)
 		{
@@ -371,7 +375,7 @@ void draw_hotbar(video::IVideoDriver *driver, gui::IGUIFont *font,
 			driver->draw2DImage(heart_texture, rect,
 				core::rect<s32>(core::position2d<s32>(0,0), srcd),
 				NULL, colors, true);
-			p += v2s32(20,0);
+			p += v2s32(16,0);
 		}
 	}
 }
@@ -632,6 +636,10 @@ void update_skybox(video::IVideoDriver* driver,
 		skybox->remove();
 	}
 	
+	/*// Disable skybox if FarMesh is enabled
+	if(g_settings.getBool("enable_farmesh"))
+		return;*/
+	
 	if(brightness >= 0.5)
 	{
 		skybox = smgr->addSkyBoxSceneNode(
@@ -801,8 +809,9 @@ void the_game(
 	{
 		if(client.accessDenied())
 		{
-			error_message = L"Access denied. Check your password and try again.";
-			std::cout<<DTIME<<"Access denied."<<std::endl;
+			error_message = L"Access denied. Reason: "
+					+client.accessDeniedReason();
+			std::cout<<DTIME<<wide_to_narrow(error_message)<<std::endl;
 		}
 		else
 		{
@@ -851,8 +860,21 @@ void the_game(
 	
 	float cloud_height = BS*100;
 	Clouds *clouds = NULL;
-	clouds = new Clouds(smgr->getRootSceneNode(), smgr, -1,
-			cloud_height, time(0));
+	if(g_settings.getBool("enable_clouds"))
+	{
+		clouds = new Clouds(smgr->getRootSceneNode(), smgr, -1,
+				cloud_height, time(0));
+	}
+	
+	/*
+		FarMesh
+	*/
+
+	FarMesh *farmesh = NULL;
+	if(g_settings.getBool("enable_farmesh"))
+	{
+		farmesh = new FarMesh(smgr->getRootSceneNode(), smgr, -1, client.getMapSeed(), &client);
+	}
 
 	/*
 		Move into game
@@ -886,8 +908,8 @@ void the_game(
 	gui::IGUIStaticText *guitext_chat = guienv->addStaticText(
 			L"",
 			core::rect<s32>(0,0,0,0),
-			false, false); // Disable word wrap as of now
-			//false, true);
+			//false, false); // Disable word wrap as of now
+			false, true);
 	//guitext_chat->setBackgroundColor(video::SColor(96,0,0,0));
 	core::list<ChatLine> chat_lines;
 	
@@ -930,6 +952,9 @@ void the_game(
 	core::list<float> frametime_log;
 
 	float damage_flash_timer = 0;
+	s16 farmesh_range = 20*MAP_BLOCKSIZE;
+	
+	bool invert_mouse = g_settings.getBool("invert_mouse");
 
 	/*
 		Main loop
@@ -937,6 +962,10 @@ void the_game(
 
 	bool first_loop_after_window_activation = true;
 
+	// TODO: Convert the static interval timers to these
+	// Interval limiter for profiler
+	IntervalLimiter m_profiler_interval;
+
 	// Time is in milliseconds
 	// NOTE: getRealTime() causes strange problems in wine (imprecision?)
 	// NOTE: So we have to use getTime() and call run()s between them
@@ -1124,6 +1153,21 @@ void the_game(
 		}
 
 		/*
+			Profiler
+		*/
+		float profiler_print_interval =
+				g_settings.getFloat("profiler_print_interval");
+		if(profiler_print_interval != 0)
+		{
+			if(m_profiler_interval.step(0.030, profiler_print_interval))
+			{
+				dstream<<"Profiler:"<<std::endl;
+				g_profiler.print(dstream);
+				g_profiler.clear();
+			}
+		}
+
+		/*
 			Direct handling of user input
 		*/
 		
@@ -1189,10 +1233,12 @@ void the_game(
 			if(g_settings.getBool("free_move"))
 			{
 				g_settings.set("free_move","false");
+				chat_lines.push_back(ChatLine(L"free_move disabled"));
 			}
 			else
 			{
 				g_settings.set("free_move","true");
+				chat_lines.push_back(ChatLine(L"free_move enabled"));
 			}
 		}
 		else if(input->wasKeyDown(getKeySetting("keymap_fastmove")))
@@ -1200,10 +1246,12 @@ void the_game(
 			if(g_settings.getBool("fast_move"))
 			{
 				g_settings.set("fast_move","false");
+				chat_lines.push_back(ChatLine(L"fast_move disabled"));
 			}
 			else
 			{
 				g_settings.set("fast_move","true");
+				chat_lines.push_back(ChatLine(L"fast_move enabled"));
 			}
 		}
 
@@ -1355,7 +1403,11 @@ void the_game(
 		if((device->isWindowActive() && noMenuActive()) || random_input)
 		{
 			if(!random_input)
-				device->getCursorControl()->setVisible(false);
+			{
+				// Mac OSX gets upset if this is set every frame
+				if(device->getCursorControl()->isVisible())
+					device->getCursorControl()->setVisible(false);
+			}
 
 			if(first_loop_after_window_activation){
 				//std::cout<<"window active, first loop"<<std::endl;
@@ -1364,6 +1416,8 @@ void the_game(
 			else{
 				s32 dx = input->getMousePos().X - displaycenter.X;
 				s32 dy = input->getMousePos().Y - displaycenter.Y;
+				if(invert_mouse)
+					dy = -dy;
 				//std::cout<<"window active, pos difference "<<dx<<","<<dy<<std::endl;
 				
 				/*const float keyspeed = 500;
@@ -1384,7 +1438,9 @@ void the_game(
 			input->setMousePos(displaycenter.X, displaycenter.Y);
 		}
 		else{
-			device->getCursorControl()->setVisible(true);
+			// Mac OSX gets upset if this is set every frame
+			if(device->getCursorControl()->isVisible() == false)
+				device->getCursorControl()->setVisible(true);
 
 			//std::cout<<"window inactive"<<std::endl;
 			first_loop_after_window_activation = true;
@@ -1696,67 +1752,56 @@ void the_game(
 			{
 				std::cout<<DTIME<<"Ground right-clicked"<<std::endl;
 				
-				if(meta && meta->typeId() == CONTENT_SIGN_WALL && !random_input)
+				// If metadata provides an inventory view, activate it
+				if(meta && meta->getInventoryDrawSpecString() != "" && !random_input)
 				{
-					dstream<<"Sign node right-clicked"<<std::endl;
+					dstream<<DTIME<<"Launching custom inventory view"<<std::endl;
+					/*
+						Construct the unique identification string of the node
+					*/
+					std::string current_name;
+					current_name += "nodemeta:";
+					current_name += itos(nodepos.X);
+					current_name += ",";
+					current_name += itos(nodepos.Y);
+					current_name += ",";
+					current_name += itos(nodepos.Z);
 					
-					SignNodeMetadata *signmeta = (SignNodeMetadata*)meta;
-					
-					// Get a new text for it
+					/*
+						Create menu
+					*/
 
-					TextDest *dest = new TextDestSignNode(nodepos, &client);
-
-					std::wstring wtext =
-							narrow_to_wide(signmeta->getText());
+					core::array<GUIInventoryMenu::DrawSpec> draw_spec;
+					v2s16 invsize =
+						GUIInventoryMenu::makeDrawSpecArrayFromString(
+							draw_spec,
+							meta->getInventoryDrawSpecString(),
+							current_name);
 
-					(new GUITextInputMenu(guienv, guiroot, -1,
-							&g_menumgr, dest,
-							wtext))->drop();
-				}
-				else if(meta && meta->typeId() == CONTENT_CHEST && !random_input)
-				{
-					dstream<<"Chest node right-clicked"<<std::endl;
-					
-					//ChestNodeMetadata *chestmeta = (ChestNodeMetadata*)meta;
-
-					std::string chest_inv_id;
-					chest_inv_id += "nodemeta:";
-					chest_inv_id += itos(nodepos.X);
-					chest_inv_id += ",";
-					chest_inv_id += itos(nodepos.Y);
-					chest_inv_id += ",";
-					chest_inv_id += itos(nodepos.Z);
-					
 					GUIInventoryMenu *menu =
 						new GUIInventoryMenu(guienv, guiroot, -1,
-							&g_menumgr, v2s16(8,9),
+							&g_menumgr, invsize,
 							client.getInventoryContext(),
 							&client);
-
-					core::array<GUIInventoryMenu::DrawSpec> draw_spec;
-					
-					draw_spec.push_back(GUIInventoryMenu::DrawSpec(
-							"list", chest_inv_id, "0",
-							v2s32(0, 0), v2s32(8, 4)));
-					draw_spec.push_back(GUIInventoryMenu::DrawSpec(
-							"list", "current_player", "main",
-							v2s32(0, 5), v2s32(8, 4)));
-
 					menu->setDrawSpec(draw_spec);
-
 					menu->drop();
-
 				}
-				else if(meta && meta->typeId() == CONTENT_FURNACE && !random_input)
+				else if(meta && meta->typeId() == CONTENT_SIGN_WALL && !random_input)
 				{
-					dstream<<"Furnace node right-clicked"<<std::endl;
+					dstream<<"Sign node right-clicked"<<std::endl;
+					
+					SignNodeMetadata *signmeta = (SignNodeMetadata*)meta;
 					
-					GUIFurnaceMenu *menu =
-						new GUIFurnaceMenu(guienv, guiroot, -1,
-							&g_menumgr, nodepos, &client);
+					// Get a new text for it
 
-					menu->drop();
+					TextDest *dest = new TextDestSignNode(nodepos, &client);
+
+					std::wstring wtext =
+							narrow_to_wide(signmeta->getText());
 
+					(new GUITextInputMenu(guienv, guiroot, -1,
+							&g_menumgr, dest,
+							wtext))->drop();
 				}
 				else
 				{
@@ -1824,6 +1869,22 @@ void the_game(
 					0.05+brightness*0.95);
 		}
 		
+		/*
+			Update farmesh
+		*/
+		if(farmesh)
+		{
+			farmesh_range = draw_control.wanted_range * 10;
+			if(draw_control.range_all && farmesh_range < 500)
+				farmesh_range = 500;
+			if(farmesh_range > 1000)
+				farmesh_range = 1000;
+
+			farmesh->step(dtime);
+			farmesh->update(v2f(player_position.X, player_position.Z),
+					0.05+brightness*0.95, farmesh_range);
+		}
+		
 		// Store brightness value
 		old_brightness = brightness;
 
@@ -1833,11 +1894,19 @@ void the_game(
 		
 		if(g_settings.getBool("enable_fog") == true)
 		{
-			f32 range = draw_control.wanted_range*BS + MAP_BLOCKSIZE*BS*1.5;
-			if(draw_control.range_all)
-				range = 100000*BS;
-			if(range < 50*BS)
-				range = range * 0.5 + 25*BS;
+			f32 range;
+			if(farmesh)
+			{
+				range = BS*farmesh_range;
+			}
+			else
+			{
+				range = draw_control.wanted_range*BS + MAP_BLOCKSIZE*BS*1.5;
+				if(draw_control.range_all)
+					range = 100000*BS;
+				if(range < 50*BS)
+					range = range * 0.5 + 25*BS;
+			}
 
 			driver->setFog(
 				bgcolor,
@@ -1985,7 +2054,7 @@ void the_game(
 					10,
 					50,
 					screensize.X - 10,
-					50 + text_height*chat_lines.size()
+					50 + guitext_chat->getTextHeight()
 			);
 
 			guitext_chat->setRelativePosition(rect);
@@ -2034,7 +2103,7 @@ void the_game(
 			//driver->beginScene(false, true, bgcolor);
 			beginscenetime = timer.stop(true);
 		}
-
+		
 		//timer3.stop();
 		
 		//std::cout<<DTIME<<"smgr->drawAll()"<<std::endl;
@@ -2166,7 +2235,8 @@ void the_game(
 	/*
 		Drop stuff
 	*/
-	clouds->drop();
+	if(clouds)
+		clouds->drop();
 	
 	/*
 		Draw a "shutting down" screen, which will be shown while the map
diff --git a/src/guiFurnaceMenu.cpp b/src/guiFurnaceMenu.cpp
deleted file mode 100644
index 9a998ce73..000000000
--- a/src/guiFurnaceMenu.cpp
+++ /dev/null
@@ -1,58 +0,0 @@
-/*
-Minetest-c55
-Copyright (C) 2010 celeron55, Perttu Ahola <celeron55@gmail.com>
-
-This program is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-This program is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with this program; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
-*/
-
-#include "guiFurnaceMenu.h"
-#include "client.h"
-
-GUIFurnaceMenu::GUIFurnaceMenu(
-		gui::IGUIEnvironment* env,
-		gui::IGUIElement* parent, s32 id,
-		IMenuManager *menumgr,
-		v3s16 nodepos,
-		Client *client
-		):
-	GUIInventoryMenu(env, parent, id, menumgr, v2s16(8,9),
-			client->getInventoryContext(), client),
-	m_nodepos(nodepos),
-	m_client(client)
-{
-	std::string furnace_inv_id;
-	furnace_inv_id += "nodemeta:";
-	furnace_inv_id += itos(nodepos.X);
-	furnace_inv_id += ",";
-	furnace_inv_id += itos(nodepos.Y);
-	furnace_inv_id += ",";
-	furnace_inv_id += itos(nodepos.Z);
-
-	core::array<GUIInventoryMenu::DrawSpec> draw_spec;
-	draw_spec.push_back(GUIInventoryMenu::DrawSpec(
-			"list", furnace_inv_id, "fuel",
-			v2s32(2, 3), v2s32(1, 1)));
-	draw_spec.push_back(GUIInventoryMenu::DrawSpec(
-			"list", furnace_inv_id, "src",
-			v2s32(2, 1), v2s32(1, 1)));
-	draw_spec.push_back(GUIInventoryMenu::DrawSpec(
-			"list", furnace_inv_id, "dst",
-			v2s32(5, 1), v2s32(2, 2)));
-	draw_spec.push_back(GUIInventoryMenu::DrawSpec(
-			"list", "current_player", "main",
-			v2s32(0, 5), v2s32(8, 4)));
-	setDrawSpec(draw_spec);
-}
-
diff --git a/src/guiInventoryMenu.cpp b/src/guiInventoryMenu.cpp
index a4ba472f8..786a4dd22 100644
--- a/src/guiInventoryMenu.cpp
+++ b/src/guiInventoryMenu.cpp
@@ -21,6 +21,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "guiInventoryMenu.h"
 #include "constants.h"
 #include "keycode.h"
+#include "strfnd.h"
 
 void drawInventoryItem(video::IVideoDriver *driver,
 		gui::IGUIFont *font,
@@ -412,5 +413,85 @@ bool GUIInventoryMenu::OnEvent(const SEvent& event)
 	return Parent ? Parent->OnEvent(event) : false;
 }
 
+/*
+	Here is an example traditional set-up sequence for a DrawSpec list:
+
+	std::string furnace_inv_id = "nodemetadata:0,1,2";
+	core::array<GUIInventoryMenu::DrawSpec> draw_spec;
+	draw_spec.push_back(GUIInventoryMenu::DrawSpec(
+			"list", furnace_inv_id, "fuel",
+			v2s32(2, 3), v2s32(1, 1)));
+	draw_spec.push_back(GUIInventoryMenu::DrawSpec(
+			"list", furnace_inv_id, "src",
+			v2s32(2, 1), v2s32(1, 1)));
+	draw_spec.push_back(GUIInventoryMenu::DrawSpec(
+			"list", furnace_inv_id, "dst",
+			v2s32(5, 1), v2s32(2, 2)));
+	draw_spec.push_back(GUIInventoryMenu::DrawSpec(
+			"list", "current_player", "main",
+			v2s32(0, 5), v2s32(8, 4)));
+	setDrawSpec(draw_spec);
+
+	Here is the string for creating the same DrawSpec list (a single line,
+	spread to multiple lines here):
+	
+	GUIInventoryMenu::makeDrawSpecArrayFromString(
+			draw_spec,
+			"nodemetadata:0,1,2",
+			"invsize[8,9;]"
+			"list[current_name;fuel;2,3;1,1;]"
+			"list[current_name;src;2,1;1,1;]"
+			"list[current_name;dst;5,1;2,2;]"
+			"list[current_player;main;0,5;8,4;]");
+	
+	Returns inventory menu size defined by invsize[].
+*/
+v2s16 GUIInventoryMenu::makeDrawSpecArrayFromString(
+		core::array<GUIInventoryMenu::DrawSpec> &draw_spec,
+		const std::string &data,
+		const std::string &current_name)
+{
+	v2s16 invsize(8,9);
+	Strfnd f(data);
+	while(f.atend() == false)
+	{
+		std::string type = trim(f.next("["));
+		//dstream<<"type="<<type<<std::endl;
+		if(type == "list")
+		{
+			std::string name = f.next(";");
+			if(name == "current_name")
+				name = current_name;
+			std::string subname = f.next(";");
+			s32 pos_x = stoi(f.next(","));
+			s32 pos_y = stoi(f.next(";"));
+			s32 geom_x = stoi(f.next(","));
+			s32 geom_y = stoi(f.next(";"));
+			dstream<<"list name="<<name<<", subname="<<subname
+					<<", pos=("<<pos_x<<","<<pos_y<<")"
+					<<", geom=("<<geom_x<<","<<geom_y<<")"
+					<<std::endl;
+			draw_spec.push_back(GUIInventoryMenu::DrawSpec(
+					type, name, subname,
+					v2s32(pos_x,pos_y),v2s32(geom_x,geom_y)));
+			f.next("]");
+		}
+		else if(type == "invsize")
+		{
+			invsize.X = stoi(f.next(","));
+			invsize.Y = stoi(f.next(";"));
+			dstream<<"invsize ("<<invsize.X<<","<<invsize.Y<<")"<<std::endl;
+			f.next("]");
+		}
+		else
+		{
+			// Ignore others
+			std::string ts = f.next("]");
+			dstream<<"Unknown DrawSpec: type="<<type<<", data=\""<<ts<<"\""
+					<<std::endl;
+		}
+	}
 
+	return invsize;
+}
 
diff --git a/src/guiInventoryMenu.h b/src/guiInventoryMenu.h
index 10fb7a425..5336cae82 100644
--- a/src/guiInventoryMenu.h
+++ b/src/guiInventoryMenu.h
@@ -102,6 +102,12 @@ public:
 		v2s32 pos;
 		v2s32 geom;
 	};
+	
+	// See .cpp for format
+	static v2s16 makeDrawSpecArrayFromString(
+			core::array<GUIInventoryMenu::DrawSpec> &draw_spec,
+			const std::string &data,
+			const std::string &current_name);
 
 	GUIInventoryMenu(gui::IGUIEnvironment* env,
 			gui::IGUIElement* parent, s32 id,
diff --git a/src/guiKeyChangeMenu.cpp b/src/guiKeyChangeMenu.cpp
deleted file mode 100644
index 3e594aeca..000000000
--- a/src/guiKeyChangeMenu.cpp
+++ /dev/null
@@ -1,598 +0,0 @@
-/*
- Minetest-delta
- Copyright (C) 2010-11 celeron55, Perttu Ahola <celeron55@gmail.com>
- Copyright (C) 2011 Ciaran Gultnieks <ciaran@ciarang.com>
- Copyright (C) 2011 teddydestodes <derkomtur@schattengang.net>
-
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 2 of the License, or
- (at your option) any later version.
-
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- GNU General Public License for more details.
-
- You should have received a copy of the GNU General Public License along
- with this program; if not, write to the Free Software Foundation, Inc.,
- 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
- */
-
-#include "guiKeyChangeMenu.h"
-#include "debug.h"
-#include "serialization.h"
-#include "keycode.h"
-#include "main.h"
-#include <string>
-
-GUIKeyChangeMenu::GUIKeyChangeMenu(gui::IGUIEnvironment* env,
-		gui::IGUIElement* parent, s32 id, IMenuManager *menumgr) :
-	GUIModalMenu(env, parent, id, menumgr)
-{
-	activeKey = -1;
-	init_keys();
-}
-
-GUIKeyChangeMenu::~GUIKeyChangeMenu()
-{
-	removeChildren();
-}
-
-void GUIKeyChangeMenu::removeChildren()
-{
-	const core::list<gui::IGUIElement*> &children = getChildren();
-	core::list<gui::IGUIElement*> children_copy;
-	for (core::list<gui::IGUIElement*>::ConstIterator i = children.begin(); i
-			!= children.end(); i++)
-	{
-		children_copy.push_back(*i);
-	}
-	for (core::list<gui::IGUIElement*>::Iterator i = children_copy.begin(); i
-			!= children_copy.end(); i++)
-	{
-		(*i)->remove();
-	}
-}
-
-void GUIKeyChangeMenu::regenerateGui(v2u32 screensize)
-{
-	/*
-	 Remove stuff
-	 */
-	removeChildren();
-
-	/*
-	 Calculate new sizes and positions
-	 */
-
-	v2s32 size(620, 430);
-
-	core::rect < s32 > rect(screensize.X / 2 - size.X / 2,
-			screensize.Y / 2 - size.Y / 2, screensize.X / 2 + size.X / 2,
-			screensize.Y / 2 + size.Y / 2);
-
-	DesiredRect = rect;
-	recalculateAbsolutePosition(false);
-
-	v2s32 topleft(0, 0);
-
-	{
-		core::rect < s32 > rect(0, 0, 125, 20);
-		rect += topleft + v2s32(25, 3);
-		const wchar_t *text = L"KEYBINDINGS";
-		//gui::IGUIStaticText *t =
-		Environment->addStaticText(text, rect, false, true, this, -1);
-		//t->setTextAlignment(gui::EGUIA_CENTER, gui::EGUIA_UPPERLEFT);
-	}
-	v2s32 offset(25, 40);
-	// buttons
-
-	{
-		core::rect < s32 > rect(0, 0, 100, 20);
-		rect += topleft + v2s32(offset.X, offset.Y);
-		const wchar_t *text = L"Forward";
-		Environment->addStaticText(text, rect, false, true, this, -1);
-		//t->setTextAlignment(gui::EGUIA_CENTER, gui::EGUIA_UPPERLEFT);
-	}
-
-	{
-		core::rect < s32 > rect(0, 0, 100, 30);
-		rect += topleft + v2s32(offset.X + 105, offset.Y - 5);
-		this->forward = Environment->addButton(rect, this,
-				GUI_ID_KEY_FORWARD_BUTTON,
-				narrow_to_wide(KeyNames[key_forward]).c_str());
-	}
-
-	offset += v2s32(0, 25);
-	{
-		core::rect < s32 > rect(0, 0, 100, 20);
-		rect += topleft + v2s32(offset.X, offset.Y);
-		const wchar_t *text = L"Backward";
-		Environment->addStaticText(text, rect, false, true, this, -1);
-		//t->setTextAlignment(gui::EGUIA_CENTER, gui::EGUIA_UPPERLEFT);
-	}
-
-	{
-		core::rect < s32 > rect(0, 0, 100, 30);
-		rect += topleft + v2s32(offset.X + 105, offset.Y - 5);
-		this->backward = Environment->addButton(rect, this,
-				GUI_ID_KEY_BACKWARD_BUTTON,
-				narrow_to_wide(KeyNames[key_backward]).c_str());
-	}
-	offset += v2s32(0, 25);
-	{
-		core::rect < s32 > rect(0, 0, 100, 20);
-		rect += topleft + v2s32(offset.X, offset.Y);
-		const wchar_t *text = L"Left";
-		Environment->addStaticText(text, rect, false, true, this, -1);
-		//t->setTextAlignment(gui::EGUIA_CENTER, gui::EGUIA_UPPERLEFT);
-	}
-
-	{
-		core::rect < s32 > rect(0, 0, 100, 30);
-		rect += topleft + v2s32(offset.X + 105, offset.Y - 5);
-		this->left = Environment->addButton(rect, this, GUI_ID_KEY_LEFT_BUTTON,
-				narrow_to_wide(KeyNames[key_left]).c_str());
-	}
-	offset += v2s32(0, 25);
-	{
-		core::rect < s32 > rect(0, 0, 100, 20);
-		rect += topleft + v2s32(offset.X, offset.Y);
-		const wchar_t *text = L"Right";
-		Environment->addStaticText(text, rect, false, true, this, -1);
-		//t->setTextAlignment(gui::EGUIA_CENTER, gui::EGUIA_UPPERLEFT);
-	}
-
-	{
-		core::rect < s32 > rect(0, 0, 100, 30);
-		rect += topleft + v2s32(offset.X + 105, offset.Y - 5);
-		this->right = Environment->addButton(rect, this,
-				GUI_ID_KEY_RIGHT_BUTTON,
-				narrow_to_wide(KeyNames[key_right]).c_str());
-	}
-	offset += v2s32(0, 25);
-	{
-		core::rect < s32 > rect(0, 0, 100, 20);
-		rect += topleft + v2s32(offset.X, offset.Y);
-		const wchar_t *text = L"Use";
-		Environment->addStaticText(text, rect, false, true, this, -1);
-		//t->setTextAlignment(gui::EGUIA_CENTER, gui::EGUIA_UPPERLEFT);
-	}
-
-	{
-		core::rect < s32 > rect(0, 0, 100, 30);
-		rect += topleft + v2s32(offset.X + 105, offset.Y - 5);
-		this->use = Environment->addButton(rect, this, GUI_ID_KEY_USE_BUTTON,
-				narrow_to_wide(KeyNames[key_use]).c_str());
-	}
-	offset += v2s32(0, 25);
-	{
-		core::rect < s32 > rect(0, 0, 100, 20);
-		rect += topleft + v2s32(offset.X, offset.Y);
-		const wchar_t *text = L"Sneak";
-		Environment->addStaticText(text, rect, false, true, this, -1);
-		//t->setTextAlignment(gui::EGUIA_CENTER, gui::EGUIA_UPPERLEFT);
-	}
-
-	{
-		core::rect < s32 > rect(0, 0, 100, 30);
-		rect += topleft + v2s32(offset.X + 105, offset.Y - 5);
-		this->sneak = Environment->addButton(rect, this,
-				GUI_ID_KEY_SNEAK_BUTTON,
-				narrow_to_wide(KeyNames[key_sneak]).c_str());
-	}
-	offset += v2s32(0, 25);
-	{
-		core::rect < s32 > rect(0, 0, 100, 20);
-		rect += topleft + v2s32(offset.X, offset.Y);
-		const wchar_t *text = L"Jump";
-		Environment->addStaticText(text, rect, false, true, this, -1);
-		//t->setTextAlignment(gui::EGUIA_CENTER, gui::EGUIA_UPPERLEFT);
-	}
-
-	{
-		core::rect < s32 > rect(0, 0, 100, 30);
-		rect += topleft + v2s32(offset.X + 105, offset.Y - 5);
-		this->jump = Environment->addButton(rect, this, GUI_ID_KEY_JUMP_BUTTON,
-				narrow_to_wide(KeyNames[key_jump]).c_str());
-	}
-
-	offset += v2s32(0, 25);
-	{
-		core::rect < s32 > rect(0, 0, 100, 20);
-		rect += topleft + v2s32(offset.X, offset.Y);
-		const wchar_t *text = L"Inventory";
-		Environment->addStaticText(text, rect, false, true, this, -1);
-		//t->setTextAlignment(gui::EGUIA_CENTER, gui::EGUIA_UPPERLEFT);
-	}
-
-	{
-		core::rect < s32 > rect(0, 0, 100, 30);
-		rect += topleft + v2s32(offset.X + 105, offset.Y - 5);
-		this->inventory = Environment->addButton(rect, this,
-				GUI_ID_KEY_INVENTORY_BUTTON,
-				narrow_to_wide(KeyNames[key_inventory]).c_str());
-	}
-	offset += v2s32(0, 25);
-	{
-		core::rect < s32 > rect(0, 0, 100, 20);
-		rect += topleft + v2s32(offset.X, offset.Y);
-		const wchar_t *text = L"Chat";
-		Environment->addStaticText(text, rect, false, true, this, -1);
-		//t->setTextAlignment(gui::EGUIA_CENTER, gui::EGUIA_UPPERLEFT);
-	}
-
-	{
-		core::rect < s32 > rect(0, 0, 100, 30);
-		rect += topleft + v2s32(offset.X + 105, offset.Y - 5);
-		this->chat = Environment->addButton(rect, this, GUI_ID_KEY_CHAT_BUTTON,
-				narrow_to_wide(KeyNames[key_chat]).c_str());
-	}
-
-	//next col
-	offset = v2s32(250, 40);
-	{
-		core::rect < s32 > rect(0, 0, 100, 20);
-		rect += topleft + v2s32(offset.X, offset.Y);
-		const wchar_t *text = L"Toggle fly";
-		Environment->addStaticText(text, rect, false, true, this, -1);
-		//t->setTextAlignment(gui::EGUIA_CENTER, gui::EGUIA_UPPERLEFT);
-	}
-
-	{
-		core::rect < s32 > rect(0, 0, 100, 30);
-		rect += topleft + v2s32(offset.X + 105, offset.Y - 5);
-		this->fly = Environment->addButton(rect, this, GUI_ID_KEY_FLY_BUTTON,
-				narrow_to_wide(KeyNames[key_fly]).c_str());
-	}
-	offset += v2s32(0, 25);
-	{
-		core::rect < s32 > rect(0, 0, 100, 20);
-		rect += topleft + v2s32(offset.X, offset.Y);
-		const wchar_t *text = L"Toggle fast";
-		Environment->addStaticText(text, rect, false, true, this, -1);
-		//t->setTextAlignment(gui::EGUIA_CENTER, gui::EGUIA_UPPERLEFT);
-	}
-
-	{
-		core::rect < s32 > rect(0, 0, 100, 30);
-		rect += topleft + v2s32(offset.X + 105, offset.Y - 5);
-		this->fast = Environment->addButton(rect, this, GUI_ID_KEY_FAST_BUTTON,
-				narrow_to_wide(KeyNames[key_fast]).c_str());
-	}
-	offset += v2s32(0, 25);
-	{
-		core::rect < s32 > rect(0, 0, 100, 20);
-		rect += topleft + v2s32(offset.X, offset.Y);
-		const wchar_t *text = L"Range select";
-		Environment->addStaticText(text, rect, false, true, this, -1);
-		//t->setTextAlignment(gui::EGUIA_CENTER, gui::EGUIA_UPPERLEFT);
-	}
-
-	{
-		core::rect < s32 > rect(0, 0, 100, 30);
-		rect += topleft + v2s32(offset.X + 105, offset.Y - 5);
-		this->range = Environment->addButton(rect, this,
-				GUI_ID_KEY_RANGE_BUTTON,
-				narrow_to_wide(KeyNames[key_range]).c_str());
-	}
-
-	offset += v2s32(0, 25);
-	{
-		core::rect < s32 > rect(0, 0, 100, 20);
-		rect += topleft + v2s32(offset.X, offset.Y);
-		const wchar_t *text = L"Print stacks";
-		Environment->addStaticText(text, rect, false, true, this, -1);
-		//t->setTextAlignment(gui::EGUIA_CENTER, gui::EGUIA_UPPERLEFT);
-	}
-
-	{
-		core::rect < s32 > rect(0, 0, 100, 30);
-		rect += topleft + v2s32(offset.X + 105, offset.Y - 5);
-		this->dump = Environment->addButton(rect, this, GUI_ID_KEY_DUMP_BUTTON,
-				narrow_to_wide(KeyNames[key_dump]).c_str());
-	}
-	{
-		core::rect < s32 > rect(0, 0, 100, 30);
-		rect += topleft + v2s32(size.X - 100 - 20, size.Y - 40);
-		Environment->addButton(rect, this, GUI_ID_BACK_BUTTON, L"Save");
-	}
-	{
-		core::rect < s32 > rect(0, 0, 100, 30);
-		rect += topleft + v2s32(size.X - 100 - 20 - 100 - 20, size.Y - 40);
-		Environment->addButton(rect, this, GUI_ID_ABORT_BUTTON, L"Cancel");
-	}
-}
-
-void GUIKeyChangeMenu::drawMenu()
-{
-	gui::IGUISkin* skin = Environment->getSkin();
-	if (!skin)
-		return;
-	video::IVideoDriver* driver = Environment->getVideoDriver();
-
-	video::SColor bgcolor(140, 0, 0, 0);
-
-	{
-		core::rect < s32 > rect(0, 0, 620, 620);
-		rect += AbsoluteRect.UpperLeftCorner;
-		driver->draw2DRectangle(bgcolor, rect, &AbsoluteClippingRect);
-	}
-
-	gui::IGUIElement::draw();
-}
-
-bool GUIKeyChangeMenu::acceptInput()
-{
-	g_settings.set("keymap_forward", keycode_to_keyname(key_forward));
-	g_settings.set("keymap_backward", keycode_to_keyname(key_backward));
-	g_settings.set("keymap_left", keycode_to_keyname(key_left));
-	g_settings.set("keymap_right", keycode_to_keyname(key_right));
-	g_settings.set("keymap_jump", keycode_to_keyname(key_jump));
-	g_settings.set("keymap_sneak", keycode_to_keyname(key_sneak));
-	g_settings.set("keymap_inventory", keycode_to_keyname(key_inventory));
-	g_settings.set("keymap_chat", keycode_to_keyname(key_chat));
-	g_settings.set("keymap_rangeselect", keycode_to_keyname(key_range));
-	g_settings.set("keymap_freemove", keycode_to_keyname(key_fly));
-	g_settings.set("keymap_fastmove", keycode_to_keyname(key_fast));
-	g_settings.set("keymap_special1", keycode_to_keyname(key_use));
-	g_settings.set("keymap_print_debug_stacks", keycode_to_keyname(key_dump));
-	//clearKeyCache(); Y U NO SCOPE?!
-	return true;
-}
-void GUIKeyChangeMenu::init_keys()
-{
-	key_forward = getKeySetting("keymap_forward");
-	key_backward = getKeySetting("keymap_backward");
-	key_left = getKeySetting("keymap_left");
-	key_right = getKeySetting("keymap_right");
-	key_jump = getKeySetting("keymap_jump");
-	key_sneak = getKeySetting("keymap_sneak");
-	key_inventory = getKeySetting("keymap_inventory");
-	key_chat = getKeySetting("keymap_chat");
-	key_range = getKeySetting("keymap_rangeselect");
-	key_fly = getKeySetting("keymap_freemove");
-	key_fast = getKeySetting("keymap_fastmove");
-	key_use = getKeySetting("keymap_special1");
-	key_dump = getKeySetting("keymap_print_debug_stacks");
-}
-
-bool GUIKeyChangeMenu::resetMenu()
-{
-	if (activeKey >= 0)
-	{
-		switch (activeKey)
-		{
-		case GUI_ID_KEY_FORWARD_BUTTON:
-			this->forward->setText(
-					narrow_to_wide(KeyNames[key_forward]).c_str());
-			break;
-		case GUI_ID_KEY_BACKWARD_BUTTON:
-			this->backward->setText(
-					narrow_to_wide(KeyNames[key_backward]).c_str());
-			break;
-		case GUI_ID_KEY_LEFT_BUTTON:
-			this->left->setText(narrow_to_wide(KeyNames[key_left]).c_str());
-			break;
-		case GUI_ID_KEY_RIGHT_BUTTON:
-			this->right->setText(narrow_to_wide(KeyNames[key_right]).c_str());
-			break;
-		case GUI_ID_KEY_JUMP_BUTTON:
-			this->jump->setText(narrow_to_wide(KeyNames[key_jump]).c_str());
-			break;
-		case GUI_ID_KEY_SNEAK_BUTTON:
-			this->sneak->setText(narrow_to_wide(KeyNames[key_sneak]).c_str());
-			break;
-		case GUI_ID_KEY_INVENTORY_BUTTON:
-			this->inventory->setText(
-					narrow_to_wide(KeyNames[key_inventory]).c_str());
-			break;
-		case GUI_ID_KEY_CHAT_BUTTON:
-			this->chat->setText(narrow_to_wide(KeyNames[key_chat]).c_str());
-			break;
-		case GUI_ID_KEY_RANGE_BUTTON:
-			this->range->setText(narrow_to_wide(KeyNames[key_range]).c_str());
-			break;
-		case GUI_ID_KEY_FLY_BUTTON:
-			this->fly->setText(narrow_to_wide(KeyNames[key_fly]).c_str());
-			break;
-		case GUI_ID_KEY_FAST_BUTTON:
-			this->fast->setText(narrow_to_wide(KeyNames[key_fast]).c_str());
-			break;
-		case GUI_ID_KEY_USE_BUTTON:
-			this->use->setText(narrow_to_wide(KeyNames[key_use]).c_str());
-			break;
-		case GUI_ID_KEY_DUMP_BUTTON:
-			this->dump->setText(narrow_to_wide(KeyNames[key_dump]).c_str());
-			break;
-		}
-		activeKey = -1;
-		return false;
-	}
-	return true;
-}
-bool GUIKeyChangeMenu::OnEvent(const SEvent& event)
-{
-	if (event.EventType == EET_KEY_INPUT_EVENT && activeKey >= 0
-			&& event.KeyInput.PressedDown)
-	{
-		if (activeKey == GUI_ID_KEY_FORWARD_BUTTON)
-		{
-			this->forward->setText(
-					narrow_to_wide(KeyNames[event.KeyInput.Key]).c_str());
-			this->key_forward = event.KeyInput.Key;
-		}
-		else if (activeKey == GUI_ID_KEY_BACKWARD_BUTTON)
-		{
-			this->backward->setText(
-					narrow_to_wide(KeyNames[event.KeyInput.Key]).c_str());
-			this->key_backward = event.KeyInput.Key;
-		}
-		else if (activeKey == GUI_ID_KEY_LEFT_BUTTON)
-		{
-			this->left->setText(
-					narrow_to_wide(KeyNames[event.KeyInput.Key]).c_str());
-			this->key_left = event.KeyInput.Key;
-		}
-		else if (activeKey == GUI_ID_KEY_RIGHT_BUTTON)
-		{
-			this->right->setText(
-					narrow_to_wide(KeyNames[event.KeyInput.Key]).c_str());
-			this->key_right = event.KeyInput.Key;
-		}
-		else if (activeKey == GUI_ID_KEY_JUMP_BUTTON)
-		{
-			this->jump->setText(
-					narrow_to_wide(KeyNames[event.KeyInput.Key]).c_str());
-			this->key_jump = event.KeyInput.Key;
-		}
-		else if (activeKey == GUI_ID_KEY_SNEAK_BUTTON)
-		{
-			this->sneak->setText(
-					narrow_to_wide(KeyNames[event.KeyInput.Key]).c_str());
-			this->key_sneak = event.KeyInput.Key;
-		}
-		else if (activeKey == GUI_ID_KEY_INVENTORY_BUTTON)
-		{
-			this->inventory->setText(
-					narrow_to_wide(KeyNames[event.KeyInput.Key]).c_str());
-			this->key_inventory = event.KeyInput.Key;
-		}
-		else if (activeKey == GUI_ID_KEY_CHAT_BUTTON)
-		{
-			this->chat->setText(
-					narrow_to_wide(KeyNames[event.KeyInput.Key]).c_str());
-			this->key_chat = event.KeyInput.Key;
-		}
-		else if (activeKey == GUI_ID_KEY_RANGE_BUTTON)
-		{
-			this->range->setText(
-					narrow_to_wide(KeyNames[event.KeyInput.Key]).c_str());
-			this->key_range = event.KeyInput.Key;
-		}
-		else if (activeKey == GUI_ID_KEY_FLY_BUTTON)
-		{
-			this->fly->setText(
-					narrow_to_wide(KeyNames[event.KeyInput.Key]).c_str());
-			this->key_fly = event.KeyInput.Key;
-		}
-		else if (activeKey == GUI_ID_KEY_FAST_BUTTON)
-		{
-			this->fast->setText(
-					narrow_to_wide(KeyNames[event.KeyInput.Key]).c_str());
-			this->key_fast = event.KeyInput.Key;
-		}
-		else if (activeKey == GUI_ID_KEY_USE_BUTTON)
-		{
-			this->use->setText(
-					narrow_to_wide(KeyNames[event.KeyInput.Key]).c_str());
-			this->key_use = event.KeyInput.Key;
-		}
-		else if (activeKey == GUI_ID_KEY_DUMP_BUTTON)
-		{
-			this->dump->setText(
-					narrow_to_wide(KeyNames[event.KeyInput.Key]).c_str());
-			this->key_dump = event.KeyInput.Key;
-		}
-
-		activeKey = -1;
-		return true;
-	}
-	if (event.EventType == EET_GUI_EVENT)
-	{
-		if (event.GUIEvent.EventType == gui::EGET_ELEMENT_FOCUS_LOST
-				&& isVisible())
-		{
-			if (!canTakeFocus(event.GUIEvent.Element))
-			{
-				dstream << "GUIMainMenu: Not allowing focus change."
-						<< std::endl;
-				// Returning true disables focus change
-				return true;
-			}
-		}
-		if (event.GUIEvent.EventType == gui::EGET_BUTTON_CLICKED)
-		{
-			switch (event.GUIEvent.Caller->getID())
-			{
-			case GUI_ID_BACK_BUTTON: //back
-				acceptInput();
-				quitMenu();
-				return true;
-			case GUI_ID_ABORT_BUTTON: //abort
-				quitMenu();
-				return true;
-			case GUI_ID_KEY_FORWARD_BUTTON:
-				resetMenu();
-				activeKey = event.GUIEvent.Caller->getID();
-				this->forward->setText(L"press Key");
-				break;
-			case GUI_ID_KEY_BACKWARD_BUTTON:
-				resetMenu();
-				activeKey = event.GUIEvent.Caller->getID();
-				this->backward->setText(L"press Key");
-				break;
-			case GUI_ID_KEY_LEFT_BUTTON:
-				resetMenu();
-				activeKey = event.GUIEvent.Caller->getID();
-				this->left->setText(L"press Key");
-				break;
-			case GUI_ID_KEY_RIGHT_BUTTON:
-				resetMenu();
-				activeKey = event.GUIEvent.Caller->getID();
-				this->right->setText(L"press Key");
-				break;
-			case GUI_ID_KEY_USE_BUTTON:
-				resetMenu();
-				activeKey = event.GUIEvent.Caller->getID();
-				this->use->setText(L"press Key");
-				break;
-			case GUI_ID_KEY_FLY_BUTTON:
-				resetMenu();
-				activeKey = event.GUIEvent.Caller->getID();
-				this->fly->setText(L"press Key");
-				break;
-			case GUI_ID_KEY_FAST_BUTTON:
-				resetMenu();
-				activeKey = event.GUIEvent.Caller->getID();
-				this->fast->setText(L"press Key");
-				break;
-			case GUI_ID_KEY_JUMP_BUTTON:
-				resetMenu();
-				activeKey = event.GUIEvent.Caller->getID();
-				this->jump->setText(L"press Key");
-				break;
-			case GUI_ID_KEY_CHAT_BUTTON:
-				resetMenu();
-				activeKey = event.GUIEvent.Caller->getID();
-				this->chat->setText(L"press Key");
-				break;
-			case GUI_ID_KEY_SNEAK_BUTTON:
-				resetMenu();
-				activeKey = event.GUIEvent.Caller->getID();
-				this->sneak->setText(L"press Key");
-				break;
-			case GUI_ID_KEY_INVENTORY_BUTTON:
-				resetMenu();
-				activeKey = event.GUIEvent.Caller->getID();
-				this->inventory->setText(L"press Key");
-				break;
-			case GUI_ID_KEY_DUMP_BUTTON:
-				resetMenu();
-				activeKey = event.GUIEvent.Caller->getID();
-				this->dump->setText(L"press Key");
-				break;
-			case GUI_ID_KEY_RANGE_BUTTON:
-				resetMenu();
-				activeKey = event.GUIEvent.Caller->getID();
-				this->range->setText(L"press Key");
-				break;
-			}
-			//Buttons
-
-		}
-	}
-	return Parent ? Parent->OnEvent(event) : false;
-}
-
diff --git a/src/guiKeyChangeMenu.h b/src/guiKeyChangeMenu.h
deleted file mode 100644
index 389ce7aee..000000000
--- a/src/guiKeyChangeMenu.h
+++ /dev/null
@@ -1,133 +0,0 @@
-/*
- Minetest-delta
- Copyright (C) 2010-11 celeron55, Perttu Ahola <celeron55@gmail.com>
- Copyright (C) 2011 Ciaran Gultnieks <ciaran@ciarang.com>
- Copyright (C) 2011 teddydestodes <derkomtur@schattengang.net>
-
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 2 of the License, or
- (at your option) any later version.
-
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- GNU General Public License for more details.
-
- You should have received a copy of the GNU General Public License along
- with this program; if not, write to the Free Software Foundation, Inc.,
- 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
- */
-
-#ifndef GUIKEYCHANGEMENU_HEADER
-#define GUIKEYCHANGEMENU_HEADER
-
-#include "common_irrlicht.h"
-#include "utility.h"
-#include "modalMenu.h"
-#include "client.h"
-#include <string>
-
-static const char *KeyNames[] =
-	{ "-", "Left Button", "Right Button", "Cancel", "Middle Button", "X Button 1",
-			"X Button 2", "-", "Back", "Tab", "-", "-", "Clear", "Return", "-",
-			"-", "Shift", "Control", "Menu", "Pause", "Capital", "Kana", "-",
-			"Junja", "Final", "Kanji", "-", "Escape", "Convert", "Nonconvert",
-			"Accept", "Mode Change", "Space", "Priot", "Next", "End", "Home",
-			"Left", "Up", "Right", "Down", "Select", "Print", "Execute",
-			"Snapshot", "Insert", "Delete", "Help", "0", "1", "2", "3", "4", "5",
-			"6", "7", "8", "9", "-", "-", "-", "-", "-", "-", "-", "A", "B", "C",
-			"D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q",
-			"R", "S", "T", "U", "V", "W", "X", "Y", "Z", "Left Windows",
-			"Right Windows", "Apps", "-", "Sleep", "Numpad 0", "Numpad 1",
-			"Numpad 2", "Numpad 3", "Numpad 4", "Numpad 5", "Numpad 6", "Numpad 7",
-			"Numpad 8", "Numpad 9", "Numpad *", "Numpad +", "Numpad /", "Numpad -",
-			"Numpad .", "Numpad /", "F1", "F2", "F3", "F4", "F5", "F6", "F7", "F8",
-			"F9", "F10", "F11", "F12", "F13", "F14", "F15", "F16", "F17", "F18",
-			"F19", "F20", "F21", "F22", "F23", "F24", "-", "-", "-", "-", "-", "-",
-			"-", "-", "Num Lock", "Scroll Lock", "-", "-", "-", "-", "-", "-", "-",
-			"-", "-", "-", "-", "-", "-", "-", "Left Shift", "Right Shight",
-			"Left Control", "Right Control", "Left Menu", "Right Menu", "-", "-",
-			"-", "-", "-", "-", "-", "-", "-", "-", "-", "-", "-", "-", "-", "-",
-			"-", "-", "-", "-", "-", "Plus", "Comma", "Minus", "Period", "-", "-",
-			"-", "-", "-", "-", "-", "-", "-", "-", "-", "-", "-", "-", "-", "-",
-			"-", "-", "-", "-", "-", "-", "-", "-", "-", "-", "-", "-", "-", "-",
-			"-", "-", "-", "-", "-", "-", "-", "-", "-", "-", "-", "-", "-", "-",
-			"-", "-", "-", "-", "-", "-", "-", "-", "-", "-", "-", "Attn", "CrSel",
-			"ExSel", "Erase OEF", "Play", "Zoom", "PA1", "OEM Clear", "-" };
-	enum
-	{
-		GUI_ID_BACK_BUTTON = 101, GUI_ID_ABORT_BUTTON, GUI_ID_SCROLL_BAR,
-		//buttons
-		GUI_ID_KEY_FORWARD_BUTTON,
-		GUI_ID_KEY_BACKWARD_BUTTON,
-		GUI_ID_KEY_LEFT_BUTTON,
-		GUI_ID_KEY_RIGHT_BUTTON,
-		GUI_ID_KEY_USE_BUTTON,
-		GUI_ID_KEY_FLY_BUTTON,
-		GUI_ID_KEY_FAST_BUTTON,
-		GUI_ID_KEY_JUMP_BUTTON,
-		GUI_ID_KEY_CHAT_BUTTON,
-		GUI_ID_KEY_SNEAK_BUTTON,
-		GUI_ID_KEY_INVENTORY_BUTTON,
-		GUI_ID_KEY_DUMP_BUTTON,
-		GUI_ID_KEY_RANGE_BUTTON
-	};
-
-class GUIKeyChangeMenu: public GUIModalMenu
-{
-public:
-	GUIKeyChangeMenu(gui::IGUIEnvironment* env, gui::IGUIElement* parent,
-			s32 id, IMenuManager *menumgr);
-	~GUIKeyChangeMenu();
-
-	void removeChildren();
-	/*
-	 Remove and re-add (or reposition) stuff
-	 */
-	void regenerateGui(v2u32 screensize);
-
-	void drawMenu();
-
-	bool acceptInput();
-
-	bool OnEvent(const SEvent& event);
-
-private:
-
-	void init_keys();
-
-	bool resetMenu();
-
-	gui::IGUIButton *forward;
-	gui::IGUIButton *backward;
-	gui::IGUIButton *left;
-	gui::IGUIButton *right;
-	gui::IGUIButton *use;
-	gui::IGUIButton *sneak;
-	gui::IGUIButton *jump;
-	gui::IGUIButton *inventory;
-	gui::IGUIButton *fly;
-	gui::IGUIButton *fast;
-	gui::IGUIButton *range;
-	gui::IGUIButton *dump;
-	gui::IGUIButton *chat;
-
-	u32 activeKey;
-	u32 key_forward;
-	u32 key_backward;
-	u32 key_left;
-	u32 key_right;
-	u32 key_use;
-	u32 key_sneak;
-	u32 key_jump;
-	u32 key_inventory;
-	u32 key_fly;
-	u32 key_fast;
-	u32 key_range;
-	u32 key_chat;
-	u32 key_dump;
-};
-
-#endif
-
diff --git a/src/guiMainMenu.h b/src/guiMainMenu.h
index 6c028c6e5..87561f797 100644
--- a/src/guiMainMenu.h
+++ b/src/guiMainMenu.h
@@ -1,21 +1,21 @@
 /*
- Minetest-c55
- Copyright (C) 2010 celeron55, Perttu Ahola <celeron55@gmail.com>
+Minetest-c55
+Copyright (C) 2010 celeron55, Perttu Ahola <celeron55@gmail.com>
 
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 2 of the License, or
- (at your option) any later version.
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
 
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- GNU General Public License for more details.
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
 
- You should have received a copy of the GNU General Public License along
- with this program; if not, write to the Free Software Foundation, Inc.,
- 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
- */
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
 
 #ifndef GUIMAINMENU_HEADER
 #define GUIMAINMENU_HEADER
@@ -44,18 +44,19 @@ enum
 
 struct MainMenuData
 {
-	MainMenuData() :
+	MainMenuData():
 		// Client opts
-				fancy_trees(false), smooth_lighting(false),
-				// Server opts
-				creative_mode(false), enable_damage(false),
-				// Actions
-				delete_map(false)
-	{
-	}
+		fancy_trees(false),
+		smooth_lighting(false),
+		// Server opts
+		creative_mode(false),
+		enable_damage(false),
+		// Actions
+		delete_map(false)
+	{}
 
 	// These are in the native format of the gui elements
-
+	
 	// Client options
 	std::wstring address;
 	std::wstring port;
@@ -70,23 +71,20 @@ struct MainMenuData
 	bool delete_map;
 };
 
-class GUIMainMenu: public GUIModalMenu
+class GUIMainMenu : public GUIModalMenu
 {
 public:
-	GUIMainMenu(gui::IGUIEnvironment* env, gui::IGUIElement* parent, s32 id,
-			IMenuManager *menumgr, MainMenuData *data,
+	GUIMainMenu(gui::IGUIEnvironment* env,
+			gui::IGUIElement* parent, s32 id,
+			IMenuManager *menumgr,
+			MainMenuData *data,
 			IGameCallback *gamecallback);
 	~GUIMainMenu();
-
-	gui::IGUIEnvironment* env;
-	gui::IGUIElement* parent;
-	s32 id;
-	IMenuManager *menumgr;
-
+	
 	void removeChildren();
 	/*
-	 Remove and re-add (or reposition) stuff
-	 */
+		Remove and re-add (or reposition) stuff
+	*/
 	void regenerateGui(v2u32 screensize);
 
 	void drawMenu();
@@ -99,11 +97,16 @@ public:
 	}
 
 	bool OnEvent(const SEvent& event);
-
+	
 private:
 	MainMenuData *m_data;
 	bool m_accepted;
 	IGameCallback *m_gamecallback;
+
+	gui::IGUIEnvironment* env;
+	gui::IGUIElement* parent;
+	s32 id;
+	IMenuManager *menumgr;
 };
 
 #endif
diff --git a/src/guiMessageMenu.h b/src/guiMessageMenu.h
index 8f48b6626..82c40ce09 100644
--- a/src/guiMessageMenu.h
+++ b/src/guiMessageMenu.h
@@ -1,21 +1,21 @@
 /*
- Minetest-c55
- Copyright (C) 2010 celeron55, Perttu Ahola <celeron55@gmail.com>
+Minetest-c55
+Copyright (C) 2010 celeron55, Perttu Ahola <celeron55@gmail.com>
 
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 2 of the License, or
- (at your option) any later version.
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
 
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- GNU General Public License for more details.
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
 
- You should have received a copy of the GNU General Public License along
- with this program; if not, write to the Free Software Foundation, Inc.,
- 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
- */
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
 
 #ifndef GUIMESSAGEMENU_HEADER
 #define GUIMESSAGEMENU_HEADER
@@ -25,17 +25,19 @@
 #include "utility.h"
 #include <string>
 
-class GUIMessageMenu: public GUIModalMenu
+class GUIMessageMenu : public GUIModalMenu
 {
 public:
-	GUIMessageMenu(gui::IGUIEnvironment* env, gui::IGUIElement* parent, s32 id,
-			IMenuManager *menumgr, std::wstring message_text);
+	GUIMessageMenu(gui::IGUIEnvironment* env,
+			gui::IGUIElement* parent, s32 id,
+			IMenuManager *menumgr,
+			std::wstring message_text);
 	~GUIMessageMenu();
-
+	
 	void removeChildren();
 	/*
-	 Remove and re-add (or reposition) stuff
-	 */
+		Remove and re-add (or reposition) stuff
+	*/
 	void regenerateGui(v2u32 screensize);
 
 	void drawMenu();
@@ -43,13 +45,13 @@ public:
 	bool OnEvent(const SEvent& event);
 
 	/*
-	 true = ok'd
-	 */
+		true = ok'd
+	*/
 	bool getStatus()
 	{
 		return m_status;
 	}
-
+	
 private:
 	std::wstring m_message_text;
 	bool m_status;
diff --git a/src/guiPasswordChange.cpp b/src/guiPasswordChange.cpp
index 98b11b432..ec1cd029a 100644
--- a/src/guiPasswordChange.cpp
+++ b/src/guiPasswordChange.cpp
@@ -1,21 +1,19 @@
 /*
-Minetest-c55
-Copyright (C) 2010-11 celeron55, Perttu Ahola <celeron55@gmail.com>
+Part of Minetest-c55
+Copyright (C) 2011 celeron55, Perttu Ahola <celeron55@gmail.com>
 Copyright (C) 2011 Ciaran Gultnieks <ciaran@ciarang.com>
 
-This program is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-This program is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with this program; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+Permission to use, copy, modify, and distribute this software for any
+purpose with or without fee is hereby granted, provided that the above
+copyright notice and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
 
 #include "guiPasswordChange.h"
diff --git a/src/guiPasswordChange.h b/src/guiPasswordChange.h
index defac3113..1748baade 100644
--- a/src/guiPasswordChange.h
+++ b/src/guiPasswordChange.h
@@ -1,21 +1,19 @@
 /*
-Minetest-c55
+Part of Minetest-c55
 Copyright (C) 2010-11 celeron55, Perttu Ahola <celeron55@gmail.com>
 Copyright (C) 2011 Ciaran Gultnieks <ciaran@ciarang.com>
 
-This program is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-This program is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with this program; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+Permission to use, copy, modify, and distribute this software for any
+purpose with or without fee is hereby granted, provided that the above
+copyright notice and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
 
 #ifndef GUIPASSWORDCHANGE_HEADER
diff --git a/src/inventory.cpp b/src/inventory.cpp
index cb398a537..0c76ed845 100644
--- a/src/inventory.cpp
+++ b/src/inventory.cpp
@@ -28,6 +28,8 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include <sstream>
 #include "main.h"
 #include "serverobject.h"
+#include "content_mapnode.h"
+#include "content_inventory.h"
 
 /*
 	InventoryItem
@@ -110,36 +112,12 @@ ServerActiveObject* InventoryItem::createSAO(ServerEnvironment *env, u16 id, v3f
 
 bool MaterialItem::isCookable()
 {
-	if(m_content == CONTENT_TREE)
-	{
-		return true;
-	}
-	else if(m_content == CONTENT_COBBLE)
-	{
-		return true;
-	}
-	else if(m_content == CONTENT_SAND)
-	{
-		return true;
-	}
-	return false;
+	return item_material_is_cookable(m_content);
 }
 
 InventoryItem *MaterialItem::createCookResult()
 {
-	if(m_content == CONTENT_TREE)
-	{
-		return new CraftItem("lump_of_coal", 1);
-	}
-	else if(m_content == CONTENT_COBBLE)
-	{
-		return new MaterialItem(CONTENT_STONE, 1);
-	}
-	else if(m_content == CONTENT_SAND)
-	{
-		return new MaterialItem(CONTENT_GLASS, 1);
-	}
-	return NULL;
+	return item_material_create_cook_result(m_content);
 }
 
 /*
@@ -152,29 +130,8 @@ video::ITexture * CraftItem::getImage()
 	if(g_texturesource == NULL)
 		return NULL;
 	
-	std::string name;
+	std::string name = item_craft_get_image_name(m_subname);
 
-	if(m_subname == "Stick")
-		name = "stick.png";
-	else if(m_subname == "paper")
-		name = "paper.png";
-	else if(m_subname == "book")
-		name = "book.png";
-	else if(m_subname == "lump_of_coal")
-		name = "lump_of_coal.png";
-	else if(m_subname == "lump_of_iron")
-		name = "lump_of_iron.png";
-	else if(m_subname == "lump_of_clay")
-		name = "lump_of_clay.png";
-	else if(m_subname == "steel_ingot")
-		name = "steel_ingot.png";
-	else if(m_subname == "clay_brick")
-		name = "clay_brick.png";
-	else if(m_subname == "rat")
-		name = "rat.png";
-	else
-		name = "cloud.png";
-	
 	// Get such a texture
 	return g_texturesource->getTextureRaw(name);
 }
@@ -183,50 +140,35 @@ video::ITexture * CraftItem::getImage()
 ServerActiveObject* CraftItem::createSAO(ServerEnvironment *env, u16 id, v3f pos)
 {
 	// Special cases
-	if(m_subname == "rat")
-	{
-		ServerActiveObject *obj = new RatSAO(env, id, pos);
+	ServerActiveObject *obj = item_craft_create_object(m_subname, env, id, pos);
+	if(obj)
 		return obj;
-	}
 	// Default
-	else
-	{
-		return InventoryItem::createSAO(env, id, pos);
-	}
+	return InventoryItem::createSAO(env, id, pos);
 }
 
 u16 CraftItem::getDropCount()
 {
 	// Special cases
-	if(m_subname == "rat")
-		return 1;
+	s16 dc = item_craft_get_drop_count(m_subname);
+	if(dc != -1)
+		return dc;
 	// Default
-	else
-		return InventoryItem::getDropCount();
+	return InventoryItem::getDropCount();
 }
 
 bool CraftItem::isCookable()
 {
-	if(m_subname == "lump_of_iron" || m_subname == "lump_of_clay")
-	{
-		return true;
-	}
-	return false;
+	return item_craft_is_cookable(m_subname);
 }
 
 InventoryItem *CraftItem::createCookResult()
 {
-	if(m_subname == "lump_of_iron")
-	{
-		return new CraftItem("steel_ingot", 1);
-	}
-	else if(m_subname == "lump_of_clay")
-		return new CraftItem("clay_brick", 1);
-	return NULL;
+	return item_craft_create_cook_result(m_subname);
 }
 
 /*
-	MapBlockObjectItem
+	MapBlockObjectItem DEPRECATED
 	TODO: Remove
 */
 #ifndef SERVER
@@ -528,7 +470,7 @@ InventoryItem * InventoryList::addItem(u32 i, InventoryItem *newitem)
 	//setDirty(true);
 	
 	// If it is an empty position, it's an easy job.
-	InventoryItem *to_item = m_items[i];
+	InventoryItem *to_item = getItem(i);
 	if(to_item == NULL)
 	{
 		m_items[i] = newitem;
@@ -560,7 +502,7 @@ InventoryItem * InventoryList::addItem(u32 i, InventoryItem *newitem)
 bool InventoryList::itemFits(u32 i, InventoryItem *newitem)
 {
 	// If it is an empty position, it's an easy job.
-	InventoryItem *to_item = m_items[i];
+	InventoryItem *to_item = getItem(i);
 	if(to_item == NULL)
 	{
 		return true;
@@ -586,7 +528,7 @@ InventoryItem * InventoryList::takeItem(u32 i, u32 count)
 	
 	//setDirty(true);
 
-	InventoryItem *item = m_items[i];
+	InventoryItem *item = getItem(i);
 	// If it is an empty position, return NULL
 	if(item == NULL)
 		return NULL;
diff --git a/src/keycode.cpp b/src/keycode.cpp
index 993426053..f014914d0 100644
--- a/src/keycode.cpp
+++ b/src/keycode.cpp
@@ -1,24 +1,25 @@
 /*
- Minetest-c55
- Copyright (C) 2010-2011 celeron55, Perttu Ahola <celeron55@gmail.com>
+Minetest-c55
+Copyright (C) 2010-2011 celeron55, Perttu Ahola <celeron55@gmail.com>
 
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 2 of the License, or
- (at your option) any later version.
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
 
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- GNU General Public License for more details.
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
 
- You should have received a copy of the GNU General Public License along
- with this program; if not, write to the Free Software Foundation, Inc.,
- 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
- */
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
 
 #include "keycode.h"
 #include "main.h" // For g_settings
+
 #define CHECKKEY(x){if(strcmp(name, #x)==0) return irr::x;}
 
 irr::EKEY_CODE keyname_to_keycode(const char *name)
@@ -209,9 +210,10 @@ std::string keycode_to_keyname(s32 keycode)
 {
 	return KeyNames[keycode];
 }
+
 /*
- Key config
- */
+	Key config
+*/
 
 // A simple cache for quicker lookup
 core::map<std::string, irr::EKEY_CODE> g_key_setting_cache;
@@ -220,7 +222,7 @@ irr::EKEY_CODE getKeySetting(const char *settingname)
 {
 	core::map<std::string, irr::EKEY_CODE>::Node *n;
 	n = g_key_setting_cache.find(settingname);
-	if (n)
+	if(n)
 		return n->getValue();
 	irr::EKEY_CODE c = keyname_to_keycode(g_settings.get(settingname).c_str());
 	g_key_setting_cache.insert(settingname, c);
@@ -231,4 +233,3 @@ void clearKeyCache()
 {
 	g_key_setting_cache.clear();
 }
-
diff --git a/src/keycode.h b/src/keycode.h
index 614f2e584..9c62004d8 100644
--- a/src/keycode.h
+++ b/src/keycode.h
@@ -29,5 +29,6 @@ irr::EKEY_CODE keyname_to_keycode(const char *name);
 irr::EKEY_CODE getKeySetting(const char *settingname);
 std::string keycode_to_keyname(s32 keycode);
 void clearCache();
+
 #endif
 
diff --git a/src/main.cpp b/src/main.cpp
index f67d53475..41da310f4 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -89,6 +89,17 @@ SUGG: Make a system for pregenerating quick information for mapblocks, so
 	  that the client can show them as cubes before they are actually sent
 	  or even generated.
 
+SUGG: Erosion simulation at map generation time
+	- Simulate water flows, which would carve out dirt fast and
+	  then turn stone into gravel and sand and relocate it.
+	- How about relocating minerals, too? Coal and gold in
+	  downstream sand and gravel would be kind of cool
+	  - This would need a better way of handling minerals, mainly
+		to have mineral content as a separate field. the first
+		parameter field is free for this.
+	- Simulate rock falling from cliffs when water has removed
+	  enough solid rock from the bottom
+
 Gaming ideas:
 -------------
 
@@ -172,7 +183,15 @@ TODO: A setting for enabling bilinear filtering for textures
 
 TODO: Better control of draw_control.wanted_max_blocks
 
-TODO: Block mesh generator to tile properly on smooth lighting
+TODO: Further investigate the use of GPU lighting in addition to the
+      current one
+
+TODO: Artificial (night) light could be more yellow colored than sunlight.
+      - This is technically doable.
+	  - Also the actual colors of the textures could be made less colorful
+	    in the dark but it's a bit more difficult.
+
+SUGG: Somehow make the night less colorful
 
 Configuration:
 --------------
@@ -198,6 +217,9 @@ TODO: Don't update all meshes always on single node changes, but
 
 FIXME: When disconnected to the menu, memory is not freed properly
 
+TODO: Investigate how much the mesh generator thread gets used when
+      transferring map data
+
 Server:
 -------
 
@@ -214,11 +236,20 @@ FIXME: Server sometimes goes into some infinite PeerNotFoundException loop
 
 FIXME: The new optimized map sending doesn't sometimes send enough blocks
        from big caves and such
+FIXME: Block send distance configuration does not take effect for some reason
+
+TODO: Map saving should be done by EmergeThread
+
+SUGG: Map unloading based on sector reference is not very good, it keeps
+	unnecessary stuff in memory. I guess. Investigate this.
+
+TODO: When block is placed and it has param_type==CPT_FACEDIR_SIMPLE, set
+      the direction accordingly.
 
 Environment:
 ------------
 
-TODO: A list of "active blocks" in which stuff happens.
+TODO: A list of "active blocks" in which stuff happens. (+=done)
 	+ Add a never-resetted game timer to the server
 	+ Add a timestamp value to blocks
 	+ The simple rule: All blocks near some player are "active"
@@ -260,31 +291,24 @@ SUGG: MovingObject::move and Player::move are basically the same.
 	- NOTE: There is a simple move implementation now in collision.{h,cpp}
 	- NOTE: MovingObject will be deleted (MapBlockObject)
 
+TODO: Add a long step function to objects that is called with the time
+      difference when block activates
+
 Map:
 ----
 
 TODO: Mineral and ground material properties
       - This way mineral ground toughness can be calculated with just
 	    some formula, as well as tool strengths
+	  - There are TODOs in appropriate files: material.h, content_mapnode.h
 
 TODO: Flowing water to actually contain flow direction information
       - There is a space for this - it just has to be implemented.
 
-SUGG: Erosion simulation at map generation time
-	- Simulate water flows, which would carve out dirt fast and
-	  then turn stone into gravel and sand and relocate it.
-	- How about relocating minerals, too? Coal and gold in
-	  downstream sand and gravel would be kind of cool
-	  - This would need a better way of handling minerals, mainly
-		to have mineral content as a separate field. the first
-		parameter field is free for this.
-	- Simulate rock falling from cliffs when water has removed
-	  enough solid rock from the bottom
-
 SUGG: Try out the notch way of generating maps, that is, make bunches
       of low-res 3d noise and interpolate linearly.
 
-Mapgen v2:
+Mapgen v2 (the current one):
 * Possibly add some kind of erosion and other stuff
 * Better water generation (spread it to underwater caverns but don't
   fill dungeons that don't touch big water masses)
@@ -293,25 +317,66 @@ Mapgen v2:
   the other chunk making nasty straight walls when the other chunk
   is generated. Fix it. Maybe just a special case if the ground is
   flat?
+* Consider not updating this one and make a good mainly block-based
+  generator
+
+SUGG: Make two "modified states", one that forces the block to be saved at
+	the next save event, and one that makes the block to be saved at exit
+	time.
+
+TODO: Add a not_fully_generated flag to MapBlock, which would be set for
+	blocks that contain eg. trees from neighboring generations but haven't
+	been generated itself. This is required for the future generator.
 
 Misc. stuff:
 ------------
-* Move digging property stuff from material.{h,cpp} to mapnode.cpp
-  - ...Or maybe move content_features to material.{h,cpp}?
+- Make sure server handles removing grass when a block is placed (etc)
+    - The client should not do it by itself
+- Block cube placement around player's head
+- Protocol version field
+- Consider getting some textures from cisoun's texture pack
+	- Ask from Cisoun
+- Make sure the fence implementation and data format is good
+	- Think about using same bits for material for fences and doors, for
+	example
+- Finish the ActiveBlockModifier stuff and use it for something
+- Move mineral to param2, increment map serialization version, add conversion
+
+TODO: Add a per-sector database to store surface stuff as simple flags/values
+      - Light?
+	  - A building?
+	  And at some point make the server send this data to the client too,
+	  instead of referring to the noise functions
+	  - Ground height
+	  - Surface ground type
+	  - Trees?
+
+TODO: Restart irrlicht completely when coming back to main menu from game.
+	- This gets rid of everything that is stored in irrlicht's caches.
+
+TODO: Merge bahamada's audio stuff (clean patch available)
+
+TODO: Merge spongie's chest/furnace direction (by hand)
+
+TODO: Merge key configuration menu (no clean patch available)
 
 Making it more portable:
 ------------------------
  
 Stuff to do before release:
 ---------------------------
-- Player default privileges and default password
-- Chat privilege
-- Some simple block-based dynamic stuff in the world (finish the
-  ActiveBlockModifier stuff)
-- Protocol version field
-- Consider getting some textures from cisoun's texture pack
-- Add a long step function to objects that is called with the time
-  difference when block activates
+
+Fixes to the current release:
+-----------------------------
+
+Stuff to do after release:
+---------------------------
+
+Doing currently:
+----------------
+
+TODO: Use MapBlock::resetUsageTimer() in appropriate places
+      (on client and server)
 
 ======================================================================
 
@@ -377,6 +442,9 @@ Settings g_settings;
 // This is located in defaultsettings.cpp
 extern void set_default_settings();
 
+// Global profiler
+Profiler g_profiler;
+
 /*
 	Random stuff
 */
@@ -427,7 +495,14 @@ std::ostream *derr_client_ptr = &dstream;
 class TimeGetter
 {
 public:
-	TimeGetter(IrrlichtDevice *device):
+	virtual u32 getTime() = 0;
+};
+
+// A precise irrlicht one
+class IrrlichtTimeGetter: public TimeGetter
+{
+public:
+	IrrlichtTimeGetter(IrrlichtDevice *device):
 		m_device(device)
 	{}
 	u32 getTime()
@@ -439,8 +514,18 @@ public:
 private:
 	IrrlichtDevice *m_device;
 };
+// Not so precise one which works without irrlicht
+class SimpleTimeGetter: public TimeGetter
+{
+public:
+	u32 getTime()
+	{
+		return porting::getTimeMs();
+	}
+};
 
 // A pointer to a global instance of the time getter
+// TODO: why?
 TimeGetter *g_timegetter = NULL;
 
 u32 getTimeMs()
@@ -995,6 +1080,15 @@ void drawMenuBackground(video::IVideoDriver* driver)
 int main(int argc, char *argv[])
 {
 	/*
+		Initialization
+	*/
+
+	// Set locale. This is for forcing '.' as the decimal point.
+	std::locale::global(std::locale("C"));
+	// This enables printing all characters in bitmap font
+	setlocale(LC_CTYPE, "en_US");
+
+	/*
 		Parse command line
 	*/
 	
@@ -1057,22 +1151,29 @@ int main(int argc, char *argv[])
 		disable_stderr = true;
 #endif
 
-	// Initialize debug streams
-	debugstreams_init(disable_stderr, DEBUGFILE);
-	// Initialize debug stacks
-	debug_stacks_init();
-
-	DSTACK(__FUNCTION_NAME);
-
 	porting::signal_handler_init();
 	bool &kill = *porting::signal_handler_killstatus();
 	
+	// Initialize porting::path_data and porting::path_userdata
 	porting::initializePaths();
+
 	// Create user data directory
 	fs::CreateDir(porting::path_userdata);
 	
-	// C-style stuff initialization
-	initializeMaterialProperties();
+	// Initialize debug streams
+#ifdef RUN_IN_PLACE
+	std::string debugfile = DEBUGFILE;
+#else
+	std::string debugfile = porting::path_userdata+"/"+DEBUGFILE;
+#endif
+	debugstreams_init(disable_stderr, debugfile.c_str());
+	// Initialize debug stacks
+	debug_stacks_init();
+
+	DSTACK(__FUNCTION_NAME);
+
+	// Init material properties table
+	//initializeMaterialProperties();
 
 	// Debug handler
 	BEGIN_DEBUG_EXCEPTION_HANDLER
@@ -1090,20 +1191,11 @@ int main(int argc, char *argv[])
 	// Initialize default settings
 	set_default_settings();
 	
-	// Set locale. This is for forcing '.' as the decimal point.
-	std::locale::global(std::locale("C"));
-	// This enables printing all characters in bitmap font
-	setlocale(LC_CTYPE, "en_US");
-
 	// Initialize sockets
 	sockets_init();
 	atexit(sockets_cleanup);
 	
 	/*
-		Initialization
-	*/
-
-	/*
 		Read config file
 	*/
 	
@@ -1188,7 +1280,7 @@ int main(int argc, char *argv[])
 		port = 30000;
 	
 	// Map directory
-	std::string map_dir = porting::path_userdata+"/map";
+	std::string map_dir = porting::path_userdata+"/world";
 	if(cmd_args.exists("map-dir"))
 		map_dir = cmd_args.get("map-dir");
 	else if(g_settings.exists("map-dir"))
@@ -1199,6 +1291,9 @@ int main(int argc, char *argv[])
 	{
 		DSTACK("Dedicated server branch");
 
+		// Create time getter
+		g_timegetter = new SimpleTimeGetter();
+		
 		// Create server
 		Server server(map_dir.c_str());
 		server.start(port);
@@ -1281,7 +1376,7 @@ int main(int argc, char *argv[])
 	device = device;
 	
 	// Create time getter
-	g_timegetter = new TimeGetter(device);
+	g_timegetter = new IrrlichtTimeGetter(device);
 	
 	// Create game callback for menus
 	g_gamecallback = new MainGameCallback(device);
@@ -1349,7 +1444,6 @@ int main(int argc, char *argv[])
 		Preload some textures and stuff
 	*/
 
-	init_content_inventory_texture_paths();
 	init_mapnode(); // Second call with g_texturesource set
 	init_mineral();
 
@@ -1488,13 +1582,22 @@ int main(int argc, char *argv[])
 				g_settings.set("creative_mode", itos(menudata.creative_mode));
 				g_settings.set("enable_damage", itos(menudata.enable_damage));
 				
-				// Check for valid parameters, restart menu if invalid.
+				// NOTE: These are now checked server side; no need to do it
+				//       here, so let's not do it here.
+				/*// Check for valid parameters, restart menu if invalid.
 				if(playername == "")
 				{
 					error_message = L"Name required.";
 					continue;
 				}
-				
+				// Check that name has only valid chars
+				if(string_allowed(playername, PLAYERNAME_ALLOWED_CHARS)==false)
+				{
+					error_message = L"Characters allowed: "
+							+narrow_to_wide(PLAYERNAME_ALLOWED_CHARS);
+					continue;
+				}*/
+
 				// Save settings
 				g_settings.set("name", playername);
 				g_settings.set("address", address);
diff --git a/src/main.h b/src/main.h
index fcf150f87..450525c26 100644
--- a/src/main.h
+++ b/src/main.h
@@ -28,6 +28,10 @@ extern Settings g_settings;
 #include "tile.h"
 extern ITextureSource *g_texturesource;
 
+// Global profiler
+#include "profiler.h"
+extern Profiler g_profiler;
+
 // Debug streams
 
 #include <fstream>
diff --git a/src/map.cpp b/src/map.cpp
index fc674d263..0de9cf18e 100644
--- a/src/map.cpp
+++ b/src/map.cpp
@@ -28,6 +28,16 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "mineral.h"
 #include "noise.h"
 #include "serverobject.h"
+#include "content_mapnode.h"
+#include "mapgen.h"
+
+extern "C" {
+	#include "sqlite3.h"
+}
+/*
+	SQLite format specification:
+	- Initially only replaces sectors/ and sectors2/
+*/
 
 /*
 	Map
@@ -81,8 +91,6 @@ MapSector * Map::getSectorNoGenerateNoExNoLock(v2s16 p)
 {
 	if(m_sector_cache != NULL && p == m_sector_cache_p){
 		MapSector * sector = m_sector_cache;
-		// Reset inactivity timer
-		sector->usage_timer = 0.0;
 		return sector;
 	}
 	
@@ -97,15 +105,11 @@ MapSector * Map::getSectorNoGenerateNoExNoLock(v2s16 p)
 	m_sector_cache_p = p;
 	m_sector_cache = sector;
 
-	// Reset inactivity timer
-	sector->usage_timer = 0.0;
 	return sector;
 }
 
 MapSector * Map::getSectorNoGenerateNoEx(v2s16 p)
 {
-	//JMutexAutoLock lock(m_sector_mutex); // Bulk comment-out
-
 	return getSectorNoGenerateNoExNoLock(p);
 }
 
@@ -244,15 +248,15 @@ void Map::unspreadLight(enum LightBank bank,
 
 		// Get node straight from the block
 		MapNode n = block->getNode(relpos);
-		
+
 		u8 oldlight = j.getNode()->getValue();
-		
+
 		// Loop through 6 neighbors
 		for(u16 i=0; i<6; i++)
 		{
 			// Get the position of the neighbor node
 			v3s16 n2pos = pos + dirs[i];
-			
+
 			// Get the block where the node is located
 			v3s16 blockpos = getNodeBlockPos(n2pos);
 
@@ -272,12 +276,12 @@ void Map::unspreadLight(enum LightBank bank,
 				{
 					continue;
 				}
-				
+
 				// Calculate relative position in block
 				v3s16 relpos = n2pos - blockpos * MAP_BLOCKSIZE;
 				// Get node straight from the block
 				MapNode n2 = block->getNode(relpos);
-				
+
 				bool changed = false;
 
 				//TODO: Optimize output by optimizing light_sources?
@@ -314,7 +318,7 @@ void Map::unspreadLight(enum LightBank bank,
 							light_sources.remove(n2pos);
 						}*/
 					}
-					
+
 					/*// DEBUG
 					if(light_sources.find(n2pos) != NULL)
 						light_sources.remove(n2pos);*/
@@ -345,7 +349,7 @@ void Map::unspreadLight(enum LightBank bank,
 			<<blockchangecount<<" times"
 			<<" for "<<from_nodes.size()<<" nodes"
 			<<std::endl;*/
-	
+
 	if(unlighted_nodes.size() > 0)
 		unspreadLight(bank, unlighted_nodes, light_sources, modified_blocks);
 }
@@ -383,7 +387,7 @@ void Map::spreadLight(enum LightBank bank,
 
 	if(from_nodes.size() == 0)
 		return;
-	
+
 	u32 blockchangecount = 0;
 
 	core::map<v3s16, bool> lighted_nodes;
@@ -397,7 +401,7 @@ void Map::spreadLight(enum LightBank bank,
 	MapBlock *block = NULL;
 	// Cache this a bit, too
 	bool block_checked_in_modified = false;
-	
+
 	for(; j.atEnd() == false; j++)
 	//for(; j != from_nodes.end(); j++)
 	{
@@ -405,7 +409,7 @@ void Map::spreadLight(enum LightBank bank,
 		//v3s16 pos = *j;
 		//dstream<<"pos=("<<pos.X<<","<<pos.Y<<","<<pos.Z<<")"<<std::endl;
 		v3s16 blockpos = getNodeBlockPos(pos);
-		
+
 		// Only fetch a new block if the block position has changed
 		try{
 			if(block == NULL || blockpos != blockpos_last){
@@ -437,7 +441,7 @@ void Map::spreadLight(enum LightBank bank,
 		for(u16 i=0; i<6; i++){
 			// Get the position of the neighbor node
 			v3s16 n2pos = pos + dirs[i];
-			
+
 			// Get the block where the node is located
 			v3s16 blockpos = getNodeBlockPos(n2pos);
 
@@ -457,12 +461,12 @@ void Map::spreadLight(enum LightBank bank,
 				{
 					continue;
 				}
-				
+
 				// Calculate relative position in block
 				v3s16 relpos = n2pos - blockpos * MAP_BLOCKSIZE;
 				// Get node straight from the block
 				MapNode n2 = block->getNode(relpos);
-				
+
 				bool changed = false;
 				/*
 					If the neighbor is brighter than the current node,
@@ -512,7 +516,7 @@ void Map::spreadLight(enum LightBank bank,
 			<<blockchangecount<<" times"
 			<<" for "<<from_nodes.size()<<" nodes"
 			<<std::endl;*/
-	
+
 	if(lighted_nodes.size() > 0)
 		spreadLight(bank, lighted_nodes, modified_blocks);
 }
@@ -539,7 +543,7 @@ v3s16 Map::getBrightestNeighbour(enum LightBank bank, v3s16 p)
 		v3s16(0,-1,0), // bottom
 		v3s16(-1,0,0), // left
 	};
-	
+
 	u8 brightest_light = 0;
 	v3s16 brightest_pos(0,0,0);
 	bool found_something = false;
@@ -565,7 +569,7 @@ v3s16 Map::getBrightestNeighbour(enum LightBank bank, v3s16 p)
 
 	if(found_something == false)
 		throw InvalidPositionException();
-		
+
 	return brightest_pos;
 }
 
@@ -584,7 +588,7 @@ s16 Map::propagateSunlight(v3s16 start,
 	for(; ; y--)
 	{
 		v3s16 pos(start.X, y, start.Z);
-		
+
 		v3s16 blockpos = getNodeBlockPos(pos);
 		MapBlock *block;
 		try{
@@ -628,31 +632,31 @@ void Map::updateLighting(enum LightBank bank,
 {
 	/*m_dout<<DTIME<<"Map::updateLighting(): "
 			<<a_blocks.size()<<" blocks."<<std::endl;*/
-	
+
 	//TimeTaker timer("updateLighting");
-	
+
 	// For debugging
 	//bool debug=true;
 	//u32 count_was = modified_blocks.size();
-	
+
 	core::map<v3s16, MapBlock*> blocks_to_update;
 
 	core::map<v3s16, bool> light_sources;
-	
+
 	core::map<v3s16, u8> unlight_from;
-		
+
 	core::map<v3s16, MapBlock*>::Iterator i;
 	i = a_blocks.getIterator();
 	for(; i.atEnd() == false; i++)
 	{
 		MapBlock *block = i.getNode()->getValue();
-		
+
 		for(;;)
 		{
 			// Don't bother with dummy blocks.
 			if(block->isDummy())
 				break;
-		
+
 			v3s16 pos = block->getPos();
 			modified_blocks.insert(pos, block);
 
@@ -665,14 +669,14 @@ void Map::updateLighting(enum LightBank bank,
 			for(s16 x=0; x<MAP_BLOCKSIZE; x++)
 			for(s16 y=0; y<MAP_BLOCKSIZE; y++)
 			{
-				
+
 				try{
 					v3s16 p(x,y,z);
 					MapNode n = block->getNode(v3s16(x,y,z));
 					u8 oldlight = n.getLight(bank);
 					n.setLight(bank, 0);
 					block->setNode(v3s16(x,y,z), n);
-					
+
 					// Collect borders for unlighting
 					if(x==0 || x == MAP_BLOCKSIZE-1
 					|| y==0 || y == MAP_BLOCKSIZE-1
@@ -696,7 +700,7 @@ void Map::updateLighting(enum LightBank bank,
 							<<std::endl;
 				}
 			}
-			
+
 			if(bank == LIGHTBANK_DAY)
 			{
 				bool bottom_valid = block->propagateSunlight(light_sources);
@@ -715,7 +719,7 @@ void Map::updateLighting(enum LightBank bank,
 				// Invalid lighting bank
 				assert(0);
 			}
-				
+
 			/*dstream<<"Bottom for sunlight-propagated block ("
 					<<pos.X<<","<<pos.Y<<","<<pos.Z<<") not valid"
 					<<std::endl;*/
@@ -730,7 +734,7 @@ void Map::updateLighting(enum LightBank bank,
 			{
 				assert(0);
 			}
-			
+
 		}
 	}
 
@@ -739,7 +743,7 @@ void Map::updateLighting(enum LightBank bank,
 		TimeTaker timer("unspreadLight");
 		unspreadLight(bank, unlight_from, light_sources, modified_blocks);
 	}
-	
+
 	if(debug)
 	{
 		u32 diff = modified_blocks.size() - count_was;
@@ -751,7 +755,7 @@ void Map::updateLighting(enum LightBank bank,
 		TimeTaker timer("spreadLight");
 		spreadLight(bank, light_sources, modified_blocks);
 	}
-	
+
 	if(debug)
 	{
 		u32 diff = modified_blocks.size() - count_was;
@@ -759,10 +763,10 @@ void Map::updateLighting(enum LightBank bank,
 		dstream<<"spreadLight modified "<<diff<<std::endl;
 	}
 #endif
-	
+
 	{
 		//MapVoxelManipulator vmanip(this);
-		
+
 		// Make a manual voxel manipulator and load all the blocks
 		// that touch the requested blocks
 		ManualMapVoxelManipulator vmanip(this);
@@ -772,14 +776,14 @@ void Map::updateLighting(enum LightBank bank,
 		{
 			MapBlock *block = i.getNode()->getValue();
 			v3s16 p = block->getPos();
-			
+
 			// Add all surrounding blocks
 			vmanip.initialEmerge(p - v3s16(1,1,1), p + v3s16(1,1,1));
 
 			/*
 				Add all surrounding blocks that have up-to-date lighting
 				NOTE: This doesn't quite do the job (not everything
-				      appropriate is lighted)
+					  appropriate is lighted)
 			*/
 			/*for(s16 z=-1; z<=1; z++)
 			for(s16 y=-1; y<=1; y++)
@@ -795,7 +799,7 @@ void Map::updateLighting(enum LightBank bank,
 					continue;
 				vmanip.initialEmerge(p, p);
 			}*/
-			
+
 			// Lighting of block will be updated completely
 			block->setLightingExpired(false);
 		}
@@ -824,7 +828,7 @@ void Map::updateLighting(core::map<v3s16, MapBlock*> & a_blocks,
 {
 	updateLighting(LIGHTBANK_DAY, a_blocks, modified_blocks);
 	updateLighting(LIGHTBANK_NIGHT, a_blocks, modified_blocks);
-	
+
 	/*
 		Update information about whether day and night light differ
 	*/
@@ -845,7 +849,7 @@ void Map::addNodeAndUpdate(v3s16 p, MapNode n,
 	/*PrintInfo(m_dout);
 	m_dout<<DTIME<<"Map::addNodeAndUpdate(): p=("
 			<<p.X<<","<<p.Y<<","<<p.Z<<")"<<std::endl;*/
-	
+
 	/*
 		From this node to nodes underneath:
 		If lighting is sunlight (1.0), unlight neighbours and
@@ -883,7 +887,7 @@ void Map::addNodeAndUpdate(v3s16 p, MapNode n,
 	{
 		try{
 			MapNode bottomnode = getNode(bottompos);
-			
+
 			if(bottomnode.d == CONTENT_GRASS
 					|| bottomnode.d == CONTENT_GRASS_FOOTSTEPS)
 			{
@@ -928,9 +932,9 @@ void Map::addNodeAndUpdate(v3s16 p, MapNode n,
 		MapBlock * block = getBlockNoCreate(blockpos);
 		assert(block != NULL);
 		modified_blocks.insert(blockpos, block);
-		
+
 		assert(isValidPosition(p));
-			
+
 		// Unlight neighbours of node.
 		// This means setting light of all consequent dimmer nodes
 		// to 0.
@@ -949,11 +953,11 @@ void Map::addNodeAndUpdate(v3s16 p, MapNode n,
 	{
 		n.setLight(LIGHTBANK_DAY, LIGHT_SUN);
 	}
-	
+
 	/*
 		Set the node on the map
 	*/
-	
+
 	setNode(p, n);
 
 	/*
@@ -966,13 +970,13 @@ void Map::addNodeAndUpdate(v3s16 p, MapNode n,
 		NodeMetadata *meta = meta_proto->clone();
 		setNodeMetadata(p, meta);
 	}
-	
+
 	/*
 		If node is under sunlight and doesn't let sunlight through,
 		take all sunlighted nodes under it and clear light from them
 		and from where the light has been spread.
 		TODO: This could be optimized by mass-unlighting instead
-		      of looping
+			  of looping
 	*/
 	if(node_under_sunlight && !content_features(n.d).sunlight_propagates)
 	{
@@ -980,7 +984,7 @@ void Map::addNodeAndUpdate(v3s16 p, MapNode n,
 		for(;; y--){
 			//m_dout<<DTIME<<"y="<<y<<std::endl;
 			v3s16 n2pos(p.X, y, p.Z);
-			
+
 			MapNode n2;
 			try{
 				n2 = getNode(n2pos);
@@ -1006,7 +1010,7 @@ void Map::addNodeAndUpdate(v3s16 p, MapNode n,
 	for(s32 i=0; i<2; i++)
 	{
 		enum LightBank bank = banks[i];
-		
+
 		/*
 			Spread light from all nodes that might be capable of doing so
 		*/
@@ -1043,13 +1047,13 @@ void Map::addNodeAndUpdate(v3s16 p, MapNode n,
 		{
 
 		v3s16 p2 = p + dirs[i];
-		
+
 		MapNode n2 = getNode(p2);
 		if(content_liquid(n2.d))
 		{
 			m_transforming_liquid.push_back(p2);
 		}
-		
+
 		}catch(InvalidPositionException &e)
 		{
 		}
@@ -1064,14 +1068,14 @@ void Map::removeNodeAndUpdate(v3s16 p,
 	/*PrintInfo(m_dout);
 	m_dout<<DTIME<<"Map::removeNodeAndUpdate(): p=("
 			<<p.X<<","<<p.Y<<","<<p.Z<<")"<<std::endl;*/
-	
+
 	bool node_under_sunlight = true;
-	
+
 	v3s16 toppos = p + v3s16(0,1,0);
 
 	// Node will be replaced with this
 	u8 replace_material = CONTENT_AIR;
-	
+
 	/*
 		If there is a node at top and it doesn't have sunlight,
 		there will be no sunlight going down.
@@ -1096,7 +1100,7 @@ void Map::removeNodeAndUpdate(v3s16 p,
 	for(s32 i=0; i<2; i++)
 	{
 		enum LightBank bank = banks[i];
-	
+
 		/*
 			Unlight neighbors (in case the node is a light source)
 		*/
@@ -1119,11 +1123,11 @@ void Map::removeNodeAndUpdate(v3s16 p,
 	MapNode n;
 	n.d = replace_material;
 	setNode(p, n);
-	
+
 	for(s32 i=0; i<2; i++)
 	{
 		enum LightBank bank = banks[i];
-	
+
 		/*
 			Recalculate lighting
 		*/
@@ -1175,7 +1179,7 @@ void Map::removeNodeAndUpdate(v3s16 p,
 	for(s32 i=0; i<2; i++)
 	{
 		enum LightBank bank = banks[i];
-	
+
 		// Get the brightest neighbour node and propagate light from it
 		v3s16 n2p = getBrightestNeighbour(bank, p);
 		try{
@@ -1215,13 +1219,13 @@ void Map::removeNodeAndUpdate(v3s16 p,
 		{
 
 		v3s16 p2 = p + dirs[i];
-		
+
 		MapNode n2 = getNode(p2);
 		if(content_liquid(n2.d))
 		{
 			m_transforming_liquid.push_back(p2);
 		}
-		
+
 		}catch(InvalidPositionException &e)
 		{
 		}
@@ -1355,19 +1359,19 @@ void Map::timerUpdate(float dtime)
 	for(; si.atEnd() == false; si++)
 	{
 		MapSector *sector = si.getNode()->getValue();
-		sector->usage_timer += dtime;
+
+		core::list<MapBlock*> blocks;
+		sector->getBlocks(blocks);
+		for(core::list<MapBlock*>::Iterator i = blocks.begin();
+				i != blocks.end(); i++)
+		{
+			(*i)->incrementUsageTimer(dtime);
+		}
 	}
 }
 
 void Map::deleteSectors(core::list<v2s16> &list, bool only_blocks)
 {
-	/*
-		Wait for caches to be removed before continuing.
-		
-		This disables the existence of caches while locked
-	*/
-	//SharedPtr<JMutexAutoLock> cachelock(m_blockcachelock.waitCaches());
-
 	core::list<v2s16>::Iterator j;
 	for(j=list.begin(); j!=list.end(); j++)
 	{
@@ -1394,12 +1398,47 @@ void Map::deleteSectors(core::list<v2s16> &list, bool only_blocks)
 	}
 }
 
-u32 Map::deleteUnusedSectors(float timeout, bool only_blocks,
+u32 Map::unloadUnusedData(float timeout, bool only_blocks,
 		core::list<v3s16> *deleted_blocks)
 {
-	//JMutexAutoLock lock(m_sector_mutex); // Bulk comment-out
-
 	core::list<v2s16> sector_deletion_queue;
+
+	core::map<v2s16, MapSector*>::Iterator si = m_sectors.getIterator();
+	for(; si.atEnd() == false; si++)
+	{
+		MapSector *sector = si.getNode()->getValue();
+
+		bool all_blocks_deleted = true;
+
+		core::list<MapBlock*> blocks;
+		sector->getBlocks(blocks);
+		for(core::list<MapBlock*>::Iterator i = blocks.begin();
+				i != blocks.end(); i++)
+		{
+			MapBlock *block = (*i);
+
+			if(block->getUsageTimer() > timeout)
+			{
+				// Save if modified
+				if(block->getModified() != MOD_STATE_CLEAN)
+					saveBlock(block);
+				// Unload
+				sector->removeBlock(block);
+				delete block;
+			}
+			else
+			{
+				all_blocks_deleted = false;
+			}
+		}
+
+		if(all_blocks_deleted)
+		{
+			sector_deletion_queue.push_back(si.getNode()->getKey());
+		}
+	}
+
+#if 0
 	core::map<v2s16, MapSector*>::Iterator i = m_sectors.getIterator();
 	for(; i.atEnd() == false; i++)
 	{
@@ -1410,7 +1449,7 @@ u32 Map::deleteUnusedSectors(float timeout, bool only_blocks,
 		if(sector->usage_timer > timeout)
 		{
 			sector_deletion_queue.push_back(i.getNode()->getKey());
-			
+
 			if(deleted_blocks != NULL)
 			{
 				// Collect positions of blocks of sector
@@ -1425,6 +1464,8 @@ u32 Map::deleteUnusedSectors(float timeout, bool only_blocks,
 			}
 		}
 	}
+#endif
+
 	deleteSectors(sector_deletion_queue, only_blocks);
 	return sector_deletion_queue.getSize();
 }
@@ -1443,7 +1484,7 @@ void Map::transformLiquids(core::map<v3s16, MapBlock*> & modified_blocks)
 
 	u32 loopcount = 0;
 	u32 initial_size = m_transforming_liquid.size();
-	
+
 	/*if(initial_size != 0)
 		dstream<<"transformLiquids(): initial_size="<<initial_size<<std::endl;*/
 
@@ -1455,17 +1496,17 @@ void Map::transformLiquids(core::map<v3s16, MapBlock*> & modified_blocks)
 		v3s16 p0 = m_transforming_liquid.pop_front();
 
 		MapNode n0 = getNode(p0);
-		
+
 		// Don't deal with non-liquids
 		if(content_liquid(n0.d) == false)
 			continue;
 
 		bool is_source = !content_flowing_liquid(n0.d);
-		
+
 		u8 liquid_level = 8;
 		if(is_source == false)
 			liquid_level = n0.param2 & 0x0f;
-		
+
 		// Turn possible source into non-source
 		u8 nonsource_c = make_liquid_flowing(n0.d);
 
@@ -1508,7 +1549,7 @@ void Map::transformLiquids(core::map<v3s16, MapBlock*> & modified_blocks)
 					s8 n2_liquid_level = 8;
 					if(n2_is_source == false)
 						n2_liquid_level = n2.param2 & 0x07;
-					
+
 					s8 new_liquid_level = -1;
 					if(from_top)
 					{
@@ -1531,7 +1572,7 @@ void Map::transformLiquids(core::map<v3s16, MapBlock*> & modified_blocks)
 				{
 				}
 			} //for
-			
+
 			/*
 				If liquid level should be something else, update it and
 				add all the neighboring water nodes to the transform queue.
@@ -1550,7 +1591,7 @@ void Map::transformLiquids(core::map<v3s16, MapBlock*> & modified_blocks)
 					n0.param2 = new_liquid_level_max;
 					setNode(p0, n0);
 				}
-				
+
 				// Block has been modified
 				{
 					v3s16 blockpos = getNodeBlockPos(p0);
@@ -1558,7 +1599,7 @@ void Map::transformLiquids(core::map<v3s16, MapBlock*> & modified_blocks)
 					if(block != NULL)
 						modified_blocks.insert(blockpos, block);
 				}
-				
+
 				/*
 					Add neighboring non-source liquid nodes to transform queue.
 				*/
@@ -1576,20 +1617,20 @@ void Map::transformLiquids(core::map<v3s16, MapBlock*> & modified_blocks)
 					{
 
 					v3s16 p2 = p0 + dirs[i];
-					
+
 					MapNode n2 = getNode(p2);
 					if(content_flowing_liquid(n2.d))
 					{
 						m_transforming_liquid.push_back(p2);
 					}
-					
+
 					}catch(InvalidPositionException &e)
 					{
 					}
 				}
 			}
 		}
-		
+
 		// Get a new one from queue if the node has turned into non-water
 		if(content_liquid(n0.d) == false)
 			continue;
@@ -1615,7 +1656,7 @@ void Map::transformLiquids(core::map<v3s16, MapBlock*> & modified_blocks)
 			// anywhere except down
 			if(liquid_level == 0 && to_bottom == false)
 				continue;
-			
+
 			u8 liquid_next_level = 0;
 			// If going to bottom
 			if(to_bottom)
@@ -1631,7 +1672,7 @@ void Map::transformLiquids(core::map<v3s16, MapBlock*> & modified_blocks)
 
 			bool n2_changed = false;
 			bool flowed = false;
-			
+
 			v3s16 p2 = p0 + dirs_to[i];
 
 			MapNode n2 = getNode(p2);
@@ -1651,7 +1692,7 @@ void Map::transformLiquids(core::map<v3s16, MapBlock*> & modified_blocks)
 				u8 n2_liquid_level = 8;
 				if(n2_is_source == false)
 					n2_liquid_level = n2.param2 & 0x07;
-				
+
 				if(to_bottom)
 				{
 					flowed = true;
@@ -1680,27 +1721,27 @@ void Map::transformLiquids(core::map<v3s16, MapBlock*> & modified_blocks)
 				n2.d = nonsource_c;
 				n2.param2 = liquid_next_level;
 				setNode(p2, n2);
-				
+
 				n2_changed = true;
 				flowed = true;
 			}
-			
+
 			//dstream<<"[2] n2.param="<<(int)n2.param<<std::endl;
 
 			if(n2_changed)
 			{
 				m_transforming_liquid.push_back(p2);
-				
+
 				v3s16 blockpos = getNodeBlockPos(p2);
 				MapBlock *block = getBlockNoCreateNoEx(blockpos);
 				if(block != NULL)
 					modified_blocks.insert(blockpos, block);
 			}
-			
+
 			// If n2_changed to bottom, don't flow anywhere else
 			if(to_bottom && flowed && !is_source)
 				break;
-				
+
 			}catch(InvalidPositionException &e)
 			{
 			}
@@ -1796,13 +1837,9 @@ ServerMap::ServerMap(std::string savedir):
 	m_map_metadata_changed(true)
 {
 	dstream<<__FUNCTION_NAME<<std::endl;
-	
-	//m_chunksize = 64;
-	//m_chunksize = 16; // Too slow
-	m_chunksize = 8; // Takes a few seconds
-	//m_chunksize = 4;
-	//m_chunksize = 2;
-	
+
+	//m_chunksize = 8; // Takes a few seconds
+
 	m_seed = (((u64)(myrand()%0xffff)<<0)
 			+ ((u64)(myrand()%0xffff)<<16)
 			+ ((u64)(myrand()%0xffff)<<32)
@@ -1811,17 +1848,17 @@ ServerMap::ServerMap(std::string savedir):
 	/*
 		Experimental and debug stuff
 	*/
-	
+
 	{
 	}
-	
+
 	/*
 		Try to load map; if not found, create a new one.
 	*/
 
 	m_savedir = savedir;
 	m_map_saving_enabled = false;
-	
+
 	try
 	{
 		// If directory exists, check contents and load if possible
@@ -1839,20 +1876,24 @@ ServerMap::ServerMap(std::string savedir):
 				try{
 					// Load map metadata (seed, chunksize)
 					loadMapMeta();
+				}
+				catch(FileNotGoodException &e){
+					dstream<<DTIME<<"WARNING: Could not load map metadata"
+							//<<" Disabling chunk-based generator."
+							<<std::endl;
+					//m_chunksize = 0;
+				}
 
+				/*try{
 					// Load chunk metadata
 					loadChunkMeta();
 				}
 				catch(FileNotGoodException &e){
-					dstream<<DTIME<<"WARNING: Server: Could not load "
-							<<"metafile(s). Disabling chunk-based "
-							<<"generation."<<std::endl;
+					dstream<<DTIME<<"WARNING: Could not load chunk metadata."
+							<<" Disabling chunk-based generator."
+							<<std::endl;
 					m_chunksize = 0;
-				}
-			
-				/*// Load sector (0,0) and throw and exception on fail
-				if(loadSectorFull(v2s16(0,0)) == false)
-					throw LoadError("Failed to load sector (0,0)");*/
+				}*/
 
 				/*dstream<<DTIME<<"Server: Successfully loaded chunk "
 						"metadata and sector (0,0) from "<<savedir<<
@@ -1883,7 +1924,7 @@ ServerMap::ServerMap(std::string savedir):
 	}
 
 	dstream<<DTIME<<"INFO: Initializing new map."<<std::endl;
-	
+
 	// Create zero sector
 	emergeSector(v2s16(0,0));
 
@@ -1894,7 +1935,7 @@ ServerMap::ServerMap(std::string savedir):
 ServerMap::~ServerMap()
 {
 	dstream<<__FUNCTION_NAME<<std::endl;
-	
+
 	try
 	{
 		if(m_map_saving_enabled)
@@ -1914,7 +1955,8 @@ ServerMap::~ServerMap()
 		dstream<<DTIME<<"Server: Failed to save map to "<<m_savedir
 				<<", exception: "<<e.what()<<std::endl;
 	}
-	
+
+#if 0
 	/*
 		Free all MapChunks
 	*/
@@ -1924,1776 +1966,48 @@ ServerMap::~ServerMap()
 		MapChunk *chunk = i.getNode()->getValue();
 		delete chunk;
 	}
-}
-
-/*
-	Some helper functions for the map generator
-*/
-
-s16 find_ground_level(VoxelManipulator &vmanip, v2s16 p2d)
-{
-	v3s16 em = vmanip.m_area.getExtent();
-	s16 y_nodes_max = vmanip.m_area.MaxEdge.Y;
-	s16 y_nodes_min = vmanip.m_area.MinEdge.Y;
-	u32 i = vmanip.m_area.index(v3s16(p2d.X, y_nodes_max, p2d.Y));
-	s16 y;
-	for(y=y_nodes_max; y>=y_nodes_min; y--)
-	{
-		MapNode &n = vmanip.m_data[i];
-		if(content_walkable(n.d))
-			break;
-			
-		vmanip.m_area.add_y(em, i, -1);
-	}
-	if(y >= y_nodes_min)
-		return y;
-	else
-		return y_nodes_min;
-}
-
-s16 find_ground_level_clever(VoxelManipulator &vmanip, v2s16 p2d)
-{
-	v3s16 em = vmanip.m_area.getExtent();
-	s16 y_nodes_max = vmanip.m_area.MaxEdge.Y;
-	s16 y_nodes_min = vmanip.m_area.MinEdge.Y;
-	u32 i = vmanip.m_area.index(v3s16(p2d.X, y_nodes_max, p2d.Y));
-	s16 y;
-	for(y=y_nodes_max; y>=y_nodes_min; y--)
-	{
-		MapNode &n = vmanip.m_data[i];
-		if(content_walkable(n.d)
-				&& n.d != CONTENT_TREE
-				&& n.d != CONTENT_LEAVES)
-			break;
-			
-		vmanip.m_area.add_y(em, i, -1);
-	}
-	if(y >= y_nodes_min)
-		return y;
-	else
-		return y_nodes_min;
-}
-
-void make_tree(VoxelManipulator &vmanip, v3s16 p0)
-{
-	MapNode treenode(CONTENT_TREE);
-	MapNode leavesnode(CONTENT_LEAVES);
-
-	s16 trunk_h = myrand_range(3, 6);
-	v3s16 p1 = p0;
-	for(s16 ii=0; ii<trunk_h; ii++)
-	{
-		if(vmanip.m_area.contains(p1))
-			vmanip.m_data[vmanip.m_area.index(p1)] = treenode;
-		p1.Y++;
-	}
-	
-	// p1 is now the last piece of the trunk
-	p1.Y -= 1;
-
-	VoxelArea leaves_a(v3s16(-2,-2,-2), v3s16(2,2,2));
-	//SharedPtr<u8> leaves_d(new u8[leaves_a.getVolume()]);
-	Buffer<u8> leaves_d(leaves_a.getVolume());
-	for(s32 i=0; i<leaves_a.getVolume(); i++)
-		leaves_d[i] = 0;
-	
-	// Force leaves at near the end of the trunk
-	{
-		s16 d = 1;
-		for(s16 z=-d; z<=d; z++)
-		for(s16 y=-d; y<=d; y++)
-		for(s16 x=-d; x<=d; x++)
-		{
-			leaves_d[leaves_a.index(v3s16(x,y,z))] = 1;
-		}
-	}
-	
-	// Add leaves randomly
-	for(u32 iii=0; iii<7; iii++)
-	{
-		s16 d = 1;
-
-		v3s16 p(
-			myrand_range(leaves_a.MinEdge.X, leaves_a.MaxEdge.X-d),
-			myrand_range(leaves_a.MinEdge.Y, leaves_a.MaxEdge.Y-d),
-			myrand_range(leaves_a.MinEdge.Z, leaves_a.MaxEdge.Z-d)
-		);
-		
-		for(s16 z=0; z<=d; z++)
-		for(s16 y=0; y<=d; y++)
-		for(s16 x=0; x<=d; x++)
-		{
-			leaves_d[leaves_a.index(p+v3s16(x,y,z))] = 1;
-		}
-	}
-	
-	// Blit leaves to vmanip
-	for(s16 z=leaves_a.MinEdge.Z; z<=leaves_a.MaxEdge.Z; z++)
-	for(s16 y=leaves_a.MinEdge.Y; y<=leaves_a.MaxEdge.Y; y++)
-	for(s16 x=leaves_a.MinEdge.X; x<=leaves_a.MaxEdge.X; x++)
-	{
-		v3s16 p(x,y,z);
-		p += p1;
-		if(vmanip.m_area.contains(p) == false)
-			continue;
-		u32 vi = vmanip.m_area.index(p);
-		if(vmanip.m_data[vi].d != CONTENT_AIR)
-			continue;
-		u32 i = leaves_a.index(x,y,z);
-		if(leaves_d[i] == 1)
-			vmanip.m_data[vi] = leavesnode;
-	}
-}
-
-void make_papyrus(VoxelManipulator &vmanip, v3s16 p0)
-{
-	MapNode papyrusnode(CONTENT_PAPYRUS);
-
-	s16 trunk_h = myrand_range(2, 3);
-	v3s16 p1 = p0;
-	for(s16 ii=0; ii<trunk_h; ii++)
-	{
-		if(vmanip.m_area.contains(p1))
-			vmanip.m_data[vmanip.m_area.index(p1)] = papyrusnode;
-		p1.Y++;
-	}
-}
-
-void make_cactus(VoxelManipulator &vmanip, v3s16 p0)
-{
-	MapNode cactusnode(CONTENT_CACTUS);
-
-	s16 trunk_h = 3;
-	v3s16 p1 = p0;
-	for(s16 ii=0; ii<trunk_h; ii++)
-	{
-		if(vmanip.m_area.contains(p1))
-			vmanip.m_data[vmanip.m_area.index(p1)] = cactusnode;
-		p1.Y++;
-	}
-}
-
-/*
-	Noise functions. Make sure seed is mangled differently in each one.
-*/
-
-// Amount of trees per area in nodes
-double tree_amount_2d(u64 seed, v2s16 p)
-{
-	double noise = noise2d_perlin(
-			0.5+(float)p.X/250, 0.5+(float)p.Y/250,
-			seed+2, 5, 0.66);
-	double zeroval = -0.3;
-	if(noise < zeroval)
-		return 0;
-	else
-		return 0.04 * (noise-zeroval) / (1.0-zeroval);
-}
-
-#define AVERAGE_MUD_AMOUNT 4
-
-double base_rock_level_2d(u64 seed, v2s16 p)
-{
-	// The base ground level
-	double base = (double)WATER_LEVEL - (double)AVERAGE_MUD_AMOUNT
-			+ 20. * noise2d_perlin(
-			0.5+(float)p.X/500., 0.5+(float)p.Y/500.,
-			(seed>>32)+654879876, 6, 0.6);
-	
-	/*// A bit hillier one
-	double base2 = WATER_LEVEL - 4.0 + 40. * noise2d_perlin(
-			0.5+(float)p.X/250., 0.5+(float)p.Y/250.,
-			(seed>>27)+90340, 6, 0.69);
-	if(base2 > base)
-		base = base2;*/
-#if 1
-	// Higher ground level
-	double higher = (double)WATER_LEVEL + 25. + 35. * noise2d_perlin(
-			0.5+(float)p.X/250., 0.5+(float)p.Y/250.,
-			seed+85039, 5, 0.69);
-	//higher = 30; // For debugging
-
-	// Limit higher to at least base
-	if(higher < base)
-		higher = base;
-		
-	// Steepness factor of cliffs
-	double b = 1.0 + 1.0 * noise2d_perlin(
-			0.5+(float)p.X/250., 0.5+(float)p.Y/250.,
-			seed-932, 7, 0.7);
-	b = rangelim(b, 0.0, 1000.0);
-	b = pow(b, 5);
-	b *= 7;
-	b = rangelim(b, 3.0, 1000.0);
-	//dstream<<"b="<<b<<std::endl;
-	//double b = 20;
-
-	// Offset to more low
-	double a_off = -0.2;
-	// High/low selector
-	/*double a = 0.5 + b * (a_off + noise2d_perlin(
-			0.5+(float)p.X/500., 0.5+(float)p.Y/500.,
-			seed-359, 6, 0.7));*/
-	double a = (double)0.5 + b * (a_off + noise2d_perlin(
-			0.5+(float)p.X/250., 0.5+(float)p.Y/250.,
-			seed-359, 5, 0.60));
-	// Limit
-	a = rangelim(a, 0.0, 1.0);
-
-	//dstream<<"a="<<a<<std::endl;
-	
-	double h = base*(1.0-a) + higher*a;
-#else
-	double h = base;
-#endif
-	return h;
-}
-
-double get_mud_add_amount(u64 seed, v2s16 p)
-{
-	return ((float)AVERAGE_MUD_AMOUNT + 3.0 * noise2d_perlin(
-			0.5+(float)p.X/200, 0.5+(float)p.Y/200,
-			seed+91013, 3, 0.55));
-}
-
-/*
-	Adds random objects to block, depending on the content of the block
-*/
-void addRandomObjects(MapBlock *block)
-{
-	for(s16 z0=0; z0<MAP_BLOCKSIZE; z0++)
-	for(s16 x0=0; x0<MAP_BLOCKSIZE; x0++)
-	{
-		bool last_node_walkable = false;
-		for(s16 y0=0; y0<MAP_BLOCKSIZE; y0++)
-		{
-			v3s16 p(x0,y0,z0);
-			MapNode n = block->getNodeNoEx(p);
-			if(n.d == CONTENT_IGNORE)
-				continue;
-			if(content_features(n.d).liquid_type != LIQUID_NONE)
-				continue;
-			if(content_features(n.d).walkable)
-			{
-				last_node_walkable = true;
-				continue;
-			}
-			if(last_node_walkable)
-			{
-				// If block contains light information
-				if(content_features(n.d).param_type == CPT_LIGHT)
-				{
-					if(n.getLight(LIGHTBANK_DAY) <= 3)
-					{
-						if(myrand() % 300 == 0)
-						{
-							v3f pos_f = intToFloat(p+block->getPosRelative(), BS);
-							pos_f.Y -= BS*0.4;
-							ServerActiveObject *obj = new RatSAO(NULL, 0, pos_f);
-							std::string data = obj->getStaticData();
-							StaticObject s_obj(obj->getType(),
-									obj->getBasePosition(), data);
-							// Add some
-							block->m_static_objects.insert(0, s_obj);
-							block->m_static_objects.insert(0, s_obj);
-							block->m_static_objects.insert(0, s_obj);
-							block->m_static_objects.insert(0, s_obj);
-							block->m_static_objects.insert(0, s_obj);
-							block->m_static_objects.insert(0, s_obj);
-							delete obj;
-						}
-						if(myrand() % 300 == 0)
-						{
-							v3f pos_f = intToFloat(p+block->getPosRelative(), BS);
-							pos_f.Y -= BS*0.4;
-							ServerActiveObject *obj = new Oerkki1SAO(NULL,0,pos_f);
-							std::string data = obj->getStaticData();
-							StaticObject s_obj(obj->getType(),
-									obj->getBasePosition(), data);
-							// Add one
-							block->m_static_objects.insert(0, s_obj);
-							delete obj;
-						}
-					}
-				}
-			}
-			last_node_walkable = false;
-		}
-	}
-	block->setChangedFlag();
-}
-
-#define VMANIP_FLAG_DUNGEON VOXELFLAG_CHECKED1
-
-/*
-	This is the main map generation method
-*/
-
-void makeChunk(ChunkMakeData *data)
-{
-	if(data->no_op)
-		return;
-	
-	s16 y_nodes_min = data->y_blocks_min * MAP_BLOCKSIZE;
-	s16 y_nodes_max = data->y_blocks_max * MAP_BLOCKSIZE + MAP_BLOCKSIZE - 1;
-	s16 h_blocks = data->y_blocks_max - data->y_blocks_min + 1;
-	u32 relative_volume = (u32)data->sectorpos_base_size*MAP_BLOCKSIZE
-			*(u32)data->sectorpos_base_size*MAP_BLOCKSIZE
-			*(u32)h_blocks*MAP_BLOCKSIZE;
-	v3s16 bigarea_blocks_min(
-		data->sectorpos_bigbase.X,
-		data->y_blocks_min,
-		data->sectorpos_bigbase.Y
-	);
-	v3s16 bigarea_blocks_max(
-		data->sectorpos_bigbase.X + data->sectorpos_bigbase_size - 1,
-		data->y_blocks_max,
-		data->sectorpos_bigbase.Y + data->sectorpos_bigbase_size - 1
-	);
-	s16 lighting_min_d = 0-data->max_spread_amount;
-	s16 lighting_max_d = data->sectorpos_base_size*MAP_BLOCKSIZE
-			+ data->max_spread_amount-1;
-
-	// Clear all flags
-	data->vmanip.clearFlag(0xff);
-
-	TimeTaker timer_generate("makeChunk() generate");
-
-	// Maximum height of the stone surface and obstacles.
-	// This is used to disable cave generation from going too high.
-	s16 stone_surface_max_y = 0;
-
-	/*
-		Generate general ground level to full area
-	*/
-	{
-	// 22ms @cs=8
-	TimeTaker timer1("Generating ground level");
-
-#if 0
-	NoiseBuffer noisebuf1;
-	//NoiseBuffer noisebuf2;
-	{
-		v3f minpos_f(
-			data->sectorpos_bigbase.X*MAP_BLOCKSIZE,
-			y_nodes_min,
-			data->sectorpos_bigbase.Y*MAP_BLOCKSIZE
-		);
-		v3f maxpos_f = minpos_f + v3f(
-			data->sectorpos_bigbase_size*MAP_BLOCKSIZE,
-			y_nodes_max-y_nodes_min,
-			data->sectorpos_bigbase_size*MAP_BLOCKSIZE
-		);
-		v3f samplelength_f = v3f(4.0, 4.0, 4.0);
-
-		TimeTaker timer("noisebuf.create");
-		
-		noisebuf1.create(data->seed+25104, 6, 0.60, 200.0,
-				minpos_f.X, minpos_f.Y, minpos_f.Z,
-				maxpos_f.X, maxpos_f.Y, maxpos_f.Z,
-				samplelength_f.X, samplelength_f.Y, samplelength_f.Z);
-		/*noisebuf1.create(data->seed+25104, 3, 0.60, 25.0,
-				minpos_f.X, minpos_f.Y, minpos_f.Z,
-				maxpos_f.X, maxpos_f.Y, maxpos_f.Z,
-				samplelength_f.X, samplelength_f.Y, samplelength_f.Z);
-		noisebuf2.create(data->seed+25105, 4, 0.50, 200.0,
-				minpos_f.X, minpos_f.Y, minpos_f.Z,
-				maxpos_f.X, maxpos_f.Y, maxpos_f.Z,
-				samplelength_f.X, samplelength_f.Y, samplelength_f.Z);*/
-	}
-
-	for(s16 x=0; x<data->sectorpos_bigbase_size*MAP_BLOCKSIZE; x++)
-	for(s16 z=0; z<data->sectorpos_bigbase_size*MAP_BLOCKSIZE; z++)
-	{
-		// Node position
-		v2s16 p2d = data->sectorpos_bigbase*MAP_BLOCKSIZE + v2s16(x,z);
-		
-		// Ground height at this point
-		float surface_y_f = 0.0;
-
-		// Use perlin noise for ground height
-		surface_y_f = base_rock_level_2d(data->seed, p2d);
-		//surface_y_f = base_rock_level_2d(data->seed, p2d);
-		
-		// Convert to integer
-		s16 surface_y = (s16)surface_y_f;
-		
-		// Log it
-		if(surface_y > stone_surface_max_y)
-			stone_surface_max_y = surface_y;
-
-		/*
-			Fill ground with stone
-		*/
-		{
-			// Use fast index incrementing
-			v3s16 em = data->vmanip.m_area.getExtent();
-			u32 i = data->vmanip.m_area.index(v3s16(p2d.X, y_nodes_min, p2d.Y));
-			for(s16 y=y_nodes_min; y<=y_nodes_max; y++)
-			{
-				// Skip if already generated.
-				// This is done here because there might be a cave at
-				// any point in ground, which could look like it
-				// wasn't generated.
-				if(data->vmanip.m_data[i].d != CONTENT_AIR)
-					break;
-
-				/*s16 noiseval = 50.0 * noise3d_perlin(
-						0.5+(float)p2d.X/100.0,
-						0.5+(float)y/100.0,
-						0.5+(float)p2d.Y/100.0,
-						data->seed+123, 5, 0.5);*/
-				double noiseval = 64.0 * noisebuf1.get(p2d.X, y, p2d.Y);
-				/*double noiseval = 30.0 * noisebuf1.get(p2d.X, y, p2d.Y);
-				noiseval *= MYMAX(0, -0.2 + noisebuf2.get(p2d.X, y, p2d.Y));*/
-				
-				//if(y < surface_y + noiseval)
-				if(noiseval > 0)
-				//if(noiseval > y)
-					data->vmanip.m_data[i].d = CONTENT_STONE;
-
-				data->vmanip.m_area.add_y(em, i, 1);
-			}
-		}
-	}
-#endif
-	
-#if 1
-	for(s16 x=0; x<data->sectorpos_bigbase_size*MAP_BLOCKSIZE; x++)
-	for(s16 z=0; z<data->sectorpos_bigbase_size*MAP_BLOCKSIZE; z++)
-	{
-		// Node position
-		v2s16 p2d = data->sectorpos_bigbase*MAP_BLOCKSIZE + v2s16(x,z);
-		
-		/*
-			Skip of already generated
-		*/
-		/*{
-			v3s16 p(p2d.X, y_nodes_min, p2d.Y);
-			if(data->vmanip.m_data[data->vmanip.m_area.index(p)].d != CONTENT_AIR)
-				continue;
-		}*/
-
-		// Ground height at this point
-		float surface_y_f = 0.0;
-
-		// Use perlin noise for ground height
-		surface_y_f = base_rock_level_2d(data->seed, p2d);
-		
-		/*// Experimental stuff
-		{
-			float a = highlands_level_2d(data->seed, p2d);
-			if(a > surface_y_f)
-				surface_y_f = a;
-		}*/
-
-		// Convert to integer
-		s16 surface_y = (s16)surface_y_f;
-		
-		// Log it
-		if(surface_y > stone_surface_max_y)
-			stone_surface_max_y = surface_y;
-
-		/*
-			Fill ground with stone
-		*/
-		{
-			// Use fast index incrementing
-			v3s16 em = data->vmanip.m_area.getExtent();
-			u32 i = data->vmanip.m_area.index(v3s16(p2d.X, y_nodes_min, p2d.Y));
-			for(s16 y=y_nodes_min; y<surface_y && y<=y_nodes_max; y++)
-			{
-				// Skip if already generated.
-				// This is done here because there might be a cave at
-				// any point in ground, which could look like it
-				// wasn't generated.
-				if(data->vmanip.m_data[i].d != CONTENT_AIR)
-					break;
-
-				data->vmanip.m_data[i].d = CONTENT_STONE;
-
-				data->vmanip.m_area.add_y(em, i, 1);
-			}
-		}
-	}
-#endif
-	
-	}//timer1
-
-	/*
-		Randomize some parameters
-	*/
-	
-	//s32 stone_obstacle_count = 0;
-	/*s32 stone_obstacle_count =
-			rangelim((1.0+noise2d(data->seed+897,
-			data->sectorpos_base.X, data->sectorpos_base.Y))/2.0 * 30, 0, 100000);*/
-	
-	//s16 stone_obstacle_max_height = 0;
-	/*s16 stone_obstacle_max_height =
-			rangelim((1.0+noise2d(data->seed+5902,
-			data->sectorpos_base.X, data->sectorpos_base.Y))/2.0 * 30, 0, 100000);*/
-
-	/*
-		Loop this part, it will make stuff look older and newer nicely
-	*/
-	const u32 age_loops = 2;
-	for(u32 i_age=0; i_age<age_loops; i_age++)
-	{ // Aging loop
-	/******************************
-		BEGINNING OF AGING LOOP
-	******************************/
-
-#if 1
-	{
-	// 24ms @cs=8
-	//TimeTaker timer1("caves");
-
-	/*
-		Make caves
-	*/
-	u32 caves_count = relative_volume / 400000;
-	u32 bruises_count = relative_volume * stone_surface_max_y / 40000000;
-	if(stone_surface_max_y < WATER_LEVEL)
-		bruises_count = 0;
-	/*u32 caves_count = 0;
-	u32 bruises_count = 0;*/
-	for(u32 jj=0; jj<caves_count+bruises_count; jj++)
-	{
-		s16 min_tunnel_diameter = 3;
-		s16 max_tunnel_diameter = 5;
-		u16 tunnel_routepoints = 20;
-		
-		v3f main_direction(0,0,0);
-
-		bool bruise_surface = (jj > caves_count);
-
-		if(bruise_surface)
-		{
-			min_tunnel_diameter = 5;
-			max_tunnel_diameter = myrand_range(10, 20);
-			/*min_tunnel_diameter = MYMAX(0, stone_surface_max_y/6);
-			max_tunnel_diameter = myrand_range(MYMAX(0, stone_surface_max_y/6), MYMAX(0, stone_surface_max_y/2));*/
-			
-			/*s16 tunnel_rou = rangelim(25*(0.5+1.0*noise2d(data->seed+42,
-					data->sectorpos_base.X, data->sectorpos_base.Y)), 0, 15);*/
-
-			tunnel_routepoints = 5;
-		}
-		else
-		{
-		}
-
-		// Allowed route area size in nodes
-		v3s16 ar(
-			data->sectorpos_base_size*MAP_BLOCKSIZE,
-			h_blocks*MAP_BLOCKSIZE,
-			data->sectorpos_base_size*MAP_BLOCKSIZE
-		);
-
-		// Area starting point in nodes
-		v3s16 of(
-			data->sectorpos_base.X*MAP_BLOCKSIZE,
-			data->y_blocks_min*MAP_BLOCKSIZE,
-			data->sectorpos_base.Y*MAP_BLOCKSIZE
-		);
-
-		// Allow a bit more
-		//(this should be more than the maximum radius of the tunnel)
-		//s16 insure = 5; // Didn't work with max_d = 20
-		s16 insure = 10;
-		s16 more = data->max_spread_amount - max_tunnel_diameter/2 - insure;
-		ar += v3s16(1,0,1) * more * 2;
-		of -= v3s16(1,0,1) * more;
-		
-		s16 route_y_min = 0;
-		// Allow half a diameter + 7 over stone surface
-		s16 route_y_max = -of.Y + stone_surface_max_y + max_tunnel_diameter/2 + 7;
-
-		/*// If caves, don't go through surface too often
-		if(bruise_surface == false)
-			route_y_max -= myrand_range(0, max_tunnel_diameter*2);*/
-
-		// Limit maximum to area
-		route_y_max = rangelim(route_y_max, 0, ar.Y-1);
-
-		if(bruise_surface)
-		{
-			/*// Minimum is at y=0
-			route_y_min = -of.Y - 0;*/
-			// Minimum is at y=max_tunnel_diameter/4
-			//route_y_min = -of.Y + max_tunnel_diameter/4;
-			//s16 min = -of.Y + max_tunnel_diameter/4;
-			s16 min = -of.Y + 0;
-			route_y_min = myrand_range(min, min + max_tunnel_diameter);
-			route_y_min = rangelim(route_y_min, 0, route_y_max);
-		}
-
-		/*dstream<<"route_y_min = "<<route_y_min
-				<<", route_y_max = "<<route_y_max<<std::endl;*/
-
-		s16 route_start_y_min = route_y_min;
-		s16 route_start_y_max = route_y_max;
-
-		// Start every 2nd cave from surface
-		bool coming_from_surface = (jj % 2 == 0 && bruise_surface == false);
-
-		if(coming_from_surface)
-		{
-			route_start_y_min = -of.Y + stone_surface_max_y + 10;
-		}
-		
-		route_start_y_min = rangelim(route_start_y_min, 0, ar.Y-1);
-		route_start_y_max = rangelim(route_start_y_max, route_start_y_min, ar.Y-1);
-
-		// Randomize starting position
-		v3f orp(
-			(float)(myrand()%ar.X)+0.5,
-			(float)(myrand_range(route_start_y_min, route_start_y_max))+0.5,
-			(float)(myrand()%ar.Z)+0.5
-		);
-
-		MapNode airnode(CONTENT_AIR);
-		
-		/*
-			Generate some tunnel starting from orp
-		*/
-		
-		for(u16 j=0; j<tunnel_routepoints; j++)
-		{
-			if(j%7==0 && bruise_surface == false)
-			{
-				main_direction = v3f(
-					((float)(myrand()%20)-(float)10)/10,
-					((float)(myrand()%20)-(float)10)/30,
-					((float)(myrand()%20)-(float)10)/10
-				);
-				main_direction *= (float)myrand_range(1, 3);
-			}
-
-			// Randomize size
-			s16 min_d = min_tunnel_diameter;
-			s16 max_d = max_tunnel_diameter;
-			s16 rs = myrand_range(min_d, max_d);
-			
-			v3s16 maxlen;
-			if(bruise_surface)
-			{
-				maxlen = v3s16(rs*7,rs*7,rs*7);
-			}
-			else
-			{
-				maxlen = v3s16(rs*4, myrand_range(1, rs*3), rs*4);
-			}
-
-			v3f vec;
-			
-			if(coming_from_surface && j < 3)
-			{
-				vec = v3f(
-					(float)(myrand()%(maxlen.X*2))-(float)maxlen.X,
-					(float)(myrand()%(maxlen.Y*1))-(float)maxlen.Y,
-					(float)(myrand()%(maxlen.Z*2))-(float)maxlen.Z
-				);
-			}
-			else
-			{
-				vec = v3f(
-					(float)(myrand()%(maxlen.X*2))-(float)maxlen.X,
-					(float)(myrand()%(maxlen.Y*2))-(float)maxlen.Y,
-					(float)(myrand()%(maxlen.Z*2))-(float)maxlen.Z
-				);
-			}
-			
-			vec += main_direction;
-
-			v3f rp = orp + vec;
-			if(rp.X < 0)
-				rp.X = 0;
-			else if(rp.X >= ar.X)
-				rp.X = ar.X-1;
-			if(rp.Y < route_y_min)
-				rp.Y = route_y_min;
-			else if(rp.Y >= route_y_max)
-				rp.Y = route_y_max-1;
-			if(rp.Z < 0)
-				rp.Z = 0;
-			else if(rp.Z >= ar.Z)
-				rp.Z = ar.Z-1;
-			vec = rp - orp;
-
-			for(float f=0; f<1.0; f+=1.0/vec.getLength())
-			{
-				v3f fp = orp + vec * f;
-				v3s16 cp(fp.X, fp.Y, fp.Z);
-
-				s16 d0 = -rs/2;
-				s16 d1 = d0 + rs - 1;
-				for(s16 z0=d0; z0<=d1; z0++)
-				{
-					//s16 si = rs - MYMAX(0, abs(z0)-rs/4);
-					s16 si = rs - MYMAX(0, abs(z0)-rs/7);
-					for(s16 x0=-si; x0<=si-1; x0++)
-					{
-						s16 maxabsxz = MYMAX(abs(x0), abs(z0));
-						//s16 si2 = rs - MYMAX(0, maxabsxz-rs/4);
-						s16 si2 = rs - MYMAX(0, maxabsxz-rs/7);
-						//s16 si2 = rs - abs(x0);
-						for(s16 y0=-si2+1+2; y0<=si2-1; y0++)
-						{
-							s16 z = cp.Z + z0;
-							s16 y = cp.Y + y0;
-							s16 x = cp.X + x0;
-							v3s16 p(x,y,z);
-							/*if(isInArea(p, ar) == false)
-								continue;*/
-							// Check only height
-							if(y < 0 || y >= ar.Y)
-								continue;
-							p += of;
-							
-							//assert(data->vmanip.m_area.contains(p));
-							if(data->vmanip.m_area.contains(p) == false)
-							{
-								dstream<<"WARNING: "<<__FUNCTION_NAME
-										<<":"<<__LINE__<<": "
-										<<"point not in area"
-										<<std::endl;
-								continue;
-							}
-							
-							// Just set it to air, it will be changed to
-							// water afterwards
-							u32 i = data->vmanip.m_area.index(p);
-							data->vmanip.m_data[i] = airnode;
-
-							if(bruise_surface == false)
-							{
-								// Set tunnel flag
-								data->vmanip.m_flags[i] |= VMANIP_FLAG_DUNGEON;
-							}
-						}
-					}
-				}
-			}
-
-			orp = rp;
-		}
-	
-	}
-
-	}//timer1
-#endif
-
-#if 1
-	{
-	// 46ms @cs=8
-	//TimeTaker timer1("ore veins");
-
-	/*
-		Make ore veins
-	*/
-	for(u32 jj=0; jj<relative_volume/1000; jj++)
-	{
-		s16 max_vein_diameter = 3;
-
-		// Allowed route area size in nodes
-		v3s16 ar(
-			data->sectorpos_base_size*MAP_BLOCKSIZE,
-			h_blocks*MAP_BLOCKSIZE,
-			data->sectorpos_base_size*MAP_BLOCKSIZE
-		);
-
-		// Area starting point in nodes
-		v3s16 of(
-			data->sectorpos_base.X*MAP_BLOCKSIZE,
-			data->y_blocks_min*MAP_BLOCKSIZE,
-			data->sectorpos_base.Y*MAP_BLOCKSIZE
-		);
-
-		// Allow a bit more
-		//(this should be more than the maximum radius of the tunnel)
-		s16 insure = 3;
-		s16 more = data->max_spread_amount - max_vein_diameter/2 - insure;
-		ar += v3s16(1,0,1) * more * 2;
-		of -= v3s16(1,0,1) * more;
-		
-		// Randomize starting position
-		v3f orp(
-			(float)(myrand()%ar.X)+0.5,
-			(float)(myrand()%ar.Y)+0.5,
-			(float)(myrand()%ar.Z)+0.5
-		);
-
-		// Randomize mineral
-		u8 mineral;
-		if(myrand()%3 != 0)
-			mineral = MINERAL_COAL;
-		else
-			mineral = MINERAL_IRON;
-
-		/*
-			Generate some vein starting from orp
-		*/
-
-		for(u16 j=0; j<2; j++)
-		{
-			/*v3f rp(
-				(float)(myrand()%ar.X)+0.5,
-				(float)(myrand()%ar.Y)+0.5,
-				(float)(myrand()%ar.Z)+0.5
-			);
-			v3f vec = rp - orp;*/
-			
-			v3s16 maxlen(5, 5, 5);
-			v3f vec(
-				(float)(myrand()%(maxlen.X*2))-(float)maxlen.X,
-				(float)(myrand()%(maxlen.Y*2))-(float)maxlen.Y,
-				(float)(myrand()%(maxlen.Z*2))-(float)maxlen.Z
-			);
-			v3f rp = orp + vec;
-			if(rp.X < 0)
-				rp.X = 0;
-			else if(rp.X >= ar.X)
-				rp.X = ar.X;
-			if(rp.Y < 0)
-				rp.Y = 0;
-			else if(rp.Y >= ar.Y)
-				rp.Y = ar.Y;
-			if(rp.Z < 0)
-				rp.Z = 0;
-			else if(rp.Z >= ar.Z)
-				rp.Z = ar.Z;
-			vec = rp - orp;
-
-			// Randomize size
-			s16 min_d = 0;
-			s16 max_d = max_vein_diameter;
-			s16 rs = myrand_range(min_d, max_d);
-			
-			for(float f=0; f<1.0; f+=1.0/vec.getLength())
-			{
-				v3f fp = orp + vec * f;
-				v3s16 cp(fp.X, fp.Y, fp.Z);
-				s16 d0 = -rs/2;
-				s16 d1 = d0 + rs - 1;
-				for(s16 z0=d0; z0<=d1; z0++)
-				{
-					s16 si = rs - abs(z0);
-					for(s16 x0=-si; x0<=si-1; x0++)
-					{
-						s16 si2 = rs - abs(x0);
-						for(s16 y0=-si2+1; y0<=si2-1; y0++)
-						{
-							// Don't put mineral to every place
-							if(myrand()%5 != 0)
-								continue;
-
-							s16 z = cp.Z + z0;
-							s16 y = cp.Y + y0;
-							s16 x = cp.X + x0;
-							v3s16 p(x,y,z);
-							/*if(isInArea(p, ar) == false)
-								continue;*/
-							// Check only height
-							if(y < 0 || y >= ar.Y)
-								continue;
-							p += of;
-							
-							assert(data->vmanip.m_area.contains(p));
-							
-							// Just set it to air, it will be changed to
-							// water afterwards
-							u32 i = data->vmanip.m_area.index(p);
-							MapNode *n = &data->vmanip.m_data[i];
-							if(n->d == CONTENT_STONE)
-								n->param = mineral;
-						}
-					}
-				}
-			}
-
-			orp = rp;
-		}
-	
-	}
-
-	}//timer1
-#endif
-
-#if 1
-	{
-	// 15ms @cs=8
-	TimeTaker timer1("add mud");
-
-	/*
-		Add mud to the central chunk
-	*/
-	
-	for(s16 x=0; x<data->sectorpos_base_size*MAP_BLOCKSIZE; x++)
-	for(s16 z=0; z<data->sectorpos_base_size*MAP_BLOCKSIZE; z++)
-	{
-		// Node position in 2d
-		v2s16 p2d = data->sectorpos_base*MAP_BLOCKSIZE + v2s16(x,z);
-		
-		// Randomize mud amount
-		s16 mud_add_amount = get_mud_add_amount(data->seed, p2d) / 2.0;
-
-		// Find ground level
-		s16 surface_y = find_ground_level_clever(data->vmanip, p2d);
-
-		/*
-			If topmost node is grass, change it to mud.
-			It might be if it was flown to there from a neighboring
-			chunk and then converted.
-		*/
-		{
-			u32 i = data->vmanip.m_area.index(v3s16(p2d.X, surface_y, p2d.Y));
-			MapNode *n = &data->vmanip.m_data[i];
-			if(n->d == CONTENT_GRASS)
-				*n = MapNode(CONTENT_MUD);
-				//n->d = CONTENT_MUD;
-		}
-
-		/*
-			Add mud on ground
-		*/
-		{
-			s16 mudcount = 0;
-			v3s16 em = data->vmanip.m_area.getExtent();
-			s16 y_start = surface_y+1;
-			u32 i = data->vmanip.m_area.index(v3s16(p2d.X, y_start, p2d.Y));
-			for(s16 y=y_start; y<=y_nodes_max; y++)
-			{
-				if(mudcount >= mud_add_amount)
-					break;
-					
-				MapNode &n = data->vmanip.m_data[i];
-				n = MapNode(CONTENT_MUD);
-				//n.d = CONTENT_MUD;
-				mudcount++;
-
-				data->vmanip.m_area.add_y(em, i, 1);
-			}
-		}
-
-	}
-
-	}//timer1
-#endif
-
-#if 1
-	{
-	// 340ms @cs=8
-	TimeTaker timer1("flow mud");
-
-	/*
-		Flow mud away from steep edges
-	*/
-
-	// Limit area by 1 because mud is flown into neighbors.
-	s16 mudflow_minpos = 0-data->max_spread_amount+1;
-	s16 mudflow_maxpos = data->sectorpos_base_size*MAP_BLOCKSIZE+data->max_spread_amount-2;
-
-	// Iterate a few times
-	for(s16 k=0; k<3; k++)
-	{
-
-	for(s16 x=mudflow_minpos;
-			x<=mudflow_maxpos;
-			x++)
-	for(s16 z=mudflow_minpos;
-			z<=mudflow_maxpos;
-			z++)
-	{
-		// Invert coordinates every 2nd iteration
-		if(k%2 == 0)
-		{
-			x = mudflow_maxpos - (x-mudflow_minpos);
-			z = mudflow_maxpos - (z-mudflow_minpos);
-		}
-
-		// Node position in 2d
-		v2s16 p2d = data->sectorpos_base*MAP_BLOCKSIZE + v2s16(x,z);
-		
-		v3s16 em = data->vmanip.m_area.getExtent();
-		u32 i = data->vmanip.m_area.index(v3s16(p2d.X, y_nodes_max, p2d.Y));
-		s16 y=y_nodes_max;
-
-		for(;; y--)
-		{
-			MapNode *n = NULL;
-			// Find mud
-			for(; y>=y_nodes_min; y--)
-			{
-				n = &data->vmanip.m_data[i];
-				//if(content_walkable(n->d))
-				//	break;
-				if(n->d == CONTENT_MUD || n->d == CONTENT_GRASS)
-					break;
-					
-				data->vmanip.m_area.add_y(em, i, -1);
-			}
-
-			// Stop if out of area
-			//if(data->vmanip.m_area.contains(i) == false)
-			if(y < y_nodes_min)
-				break;
-
-			/*// If not mud, do nothing to it
-			MapNode *n = &data->vmanip.m_data[i];
-			if(n->d != CONTENT_MUD && n->d != CONTENT_GRASS)
-				continue;*/
-
-			/*
-				Don't flow it if the stuff under it is not mud
-			*/
-			{
-				u32 i2 = i;
-				data->vmanip.m_area.add_y(em, i2, -1);
-				// Cancel if out of area
-				if(data->vmanip.m_area.contains(i2) == false)
-					continue;
-				MapNode *n2 = &data->vmanip.m_data[i2];
-				if(n2->d != CONTENT_MUD && n2->d != CONTENT_GRASS)
-					continue;
-			}
-
-			// Make it exactly mud
-			n->d = CONTENT_MUD;
-			
-			/*s16 recurse_count = 0;
-	mudflow_recurse:*/
-
-			v3s16 dirs4[4] = {
-				v3s16(0,0,1), // back
-				v3s16(1,0,0), // right
-				v3s16(0,0,-1), // front
-				v3s16(-1,0,0), // left
-			};
-
-			// Theck that upper is air or doesn't exist.
-			// Cancel dropping if upper keeps it in place
-			u32 i3 = i;
-			data->vmanip.m_area.add_y(em, i3, 1);
-			if(data->vmanip.m_area.contains(i3) == true
-					&& content_walkable(data->vmanip.m_data[i3].d) == true)
-			{
-				continue;
-			}
-
-			// Drop mud on side
-			
-			for(u32 di=0; di<4; di++)
-			{
-				v3s16 dirp = dirs4[di];
-				u32 i2 = i;
-				// Move to side
-				data->vmanip.m_area.add_p(em, i2, dirp);
-				// Fail if out of area
-				if(data->vmanip.m_area.contains(i2) == false)
-					continue;
-				// Check that side is air
-				MapNode *n2 = &data->vmanip.m_data[i2];
-				if(content_walkable(n2->d))
-					continue;
-				// Check that under side is air
-				data->vmanip.m_area.add_y(em, i2, -1);
-				if(data->vmanip.m_area.contains(i2) == false)
-					continue;
-				n2 = &data->vmanip.m_data[i2];
-				if(content_walkable(n2->d))
-					continue;
-				/*// Check that under that is air (need a drop of 2)
-				data->vmanip.m_area.add_y(em, i2, -1);
-				if(data->vmanip.m_area.contains(i2) == false)
-					continue;
-				n2 = &data->vmanip.m_data[i2];
-				if(content_walkable(n2->d))
-					continue;*/
-				// Loop further down until not air
-				do{
-					data->vmanip.m_area.add_y(em, i2, -1);
-					// Fail if out of area
-					if(data->vmanip.m_area.contains(i2) == false)
-						continue;
-					n2 = &data->vmanip.m_data[i2];
-				}while(content_walkable(n2->d) == false);
-				// Loop one up so that we're in air
-				data->vmanip.m_area.add_y(em, i2, 1);
-				n2 = &data->vmanip.m_data[i2];
-
-				// Move mud to new place
-				*n2 = *n;
-				// Set old place to be air
-				*n = MapNode(CONTENT_AIR);
-
-				// Done
-				break;
-			}
-		}
-	}
-	
-	}
-
-	}//timer1
-#endif
-
-#if 1
-	{
-	// 50ms @cs=8
-	TimeTaker timer1("add water");
-
-	/*
-		Add water to the central chunk (and a bit more)
-	*/
-	
-	for(s16 x=0-data->max_spread_amount;
-			x<data->sectorpos_base_size*MAP_BLOCKSIZE+data->max_spread_amount;
-			x++)
-	for(s16 z=0-data->max_spread_amount;
-			z<data->sectorpos_base_size*MAP_BLOCKSIZE+data->max_spread_amount;
-			z++)
-	{
-		// Node position in 2d
-		v2s16 p2d = data->sectorpos_base*MAP_BLOCKSIZE + v2s16(x,z);
-		
-		// Find ground level
-		//s16 surface_y = find_ground_level(data->vmanip, p2d);
-
-		/*
-			If ground level is over water level, skip.
-			NOTE: This leaves caves near water without water,
-			which looks especially crappy when the nearby water
-			won't start flowing either for some reason
-		*/
-		/*if(surface_y > WATER_LEVEL)
-			continue;*/
-
-		/*
-			Add water on ground
-		*/
-		{
-			v3s16 em = data->vmanip.m_area.getExtent();
-			u8 light = LIGHT_MAX;
-			// Start at global water surface level
-			s16 y_start = WATER_LEVEL;
-			u32 i = data->vmanip.m_area.index(v3s16(p2d.X, y_start, p2d.Y));
-			MapNode *n = &data->vmanip.m_data[i];
-
-			for(s16 y=y_start; y>=y_nodes_min; y--)
-			{
-				n = &data->vmanip.m_data[i];
-				
-				// Stop when there is no water and no air
-				if(n->d != CONTENT_AIR && n->d != CONTENT_WATERSOURCE
-						&& n->d != CONTENT_WATER)
-				{
-
-					break;
-				}
-				
-				// Make water only not in caves
-				if(!(data->vmanip.m_flags[i]&VMANIP_FLAG_DUNGEON))
-				{
-					n->d = CONTENT_WATERSOURCE;
-					//n->setLight(LIGHTBANK_DAY, light);
-
-					// Add to transforming liquid queue (in case it'd
-					// start flowing)
-					v3s16 p = v3s16(p2d.X, y, p2d.Y);
-					data->transforming_liquid.push_back(p);
-				}
-				
-				// Next one
-				data->vmanip.m_area.add_y(em, i, -1);
-				if(light > 0)
-					light--;
-			}
-		}
-
-	}
-
-	}//timer1
-#endif
-	
-	} // Aging loop
-	/***********************
-		END OF AGING LOOP
-	************************/
-
-#if 1
-	{
-	//TimeTaker timer1("convert mud to sand");
-
-	/*
-		Convert mud to sand
-	*/
-	
-	//s16 mud_add_amount = myrand_range(2, 4);
-	//s16 mud_add_amount = 0;
-	
-	/*for(s16 x=0; x<data->sectorpos_base_size*MAP_BLOCKSIZE; x++)
-	for(s16 z=0; z<data->sectorpos_base_size*MAP_BLOCKSIZE; z++)*/
-	for(s16 x=0-data->max_spread_amount+1;
-			x<data->sectorpos_base_size*MAP_BLOCKSIZE+data->max_spread_amount-1;
-			x++)
-	for(s16 z=0-data->max_spread_amount+1;
-			z<data->sectorpos_base_size*MAP_BLOCKSIZE+data->max_spread_amount-1;
-			z++)
-	{
-		// Node position in 2d
-		v2s16 p2d = data->sectorpos_base*MAP_BLOCKSIZE + v2s16(x,z);
-		
-		// Determine whether to have sand here
-		double sandnoise = noise2d_perlin(
-				0.5+(float)p2d.X/500, 0.5+(float)p2d.Y/500,
-				data->seed+59420, 3, 0.50);
-
-		bool have_sand = (sandnoise > -0.15);
-
-		if(have_sand == false)
-			continue;
-
-		// Determine whether to have clay in the sand here
-		double claynoise = noise2d_perlin(
-				0.5+(float)p2d.X/500, 0.5+(float)p2d.Y/500,
-				data->seed+4321, 6, 0.95);
-
-		bool have_clay = have_sand && (claynoise > 1.25);
-
-		// Find ground level
-		s16 surface_y = find_ground_level_clever(data->vmanip, p2d);
-		
-		if(surface_y > WATER_LEVEL + 2)
-			continue;
-
-		{
-			v3s16 em = data->vmanip.m_area.getExtent();
-			s16 y_start = surface_y;
-			u32 i = data->vmanip.m_area.index(v3s16(p2d.X, y_start, p2d.Y));
-			u32 not_sand_counter = 0;
-			for(s16 y=y_start; y>=y_nodes_min; y--)
-			{
-				MapNode *n = &data->vmanip.m_data[i];
-				if(n->d == CONTENT_MUD || n->d == CONTENT_GRASS)
-				{
-					if(have_clay && (surface_y == WATER_LEVEL))
-						n->d = CONTENT_CLAY;
-					else
-						n->d = CONTENT_SAND;
-				}
-				else
-				{
-					not_sand_counter++;
-					if(not_sand_counter > 3)
-						break;
-				}
-
-				data->vmanip.m_area.add_y(em, i, -1);
-			}
-		}
-
-	}
-
-	}//timer1
-#endif
-
-#if 1
-	{
-	// 1ms @cs=8
-	//TimeTaker timer1("generate trees");
-
-	/*
-		Generate some trees
-	*/
-	{
-		// Divide area into parts
-		s16 div = 8;
-		s16 sidelen = data->sectorpos_base_size*MAP_BLOCKSIZE / div;
-		double area = sidelen * sidelen;
-		for(s16 x0=0; x0<div; x0++)
-		for(s16 z0=0; z0<div; z0++)
-		{
-			// Center position of part of division
-			v2s16 p2d_center(
-				data->sectorpos_base.X*MAP_BLOCKSIZE + sidelen/2 + sidelen*x0,
-				data->sectorpos_base.Y*MAP_BLOCKSIZE + sidelen/2 + sidelen*z0
-			);
-			// Minimum edge of part of division
-			v2s16 p2d_min(
-				data->sectorpos_base.X*MAP_BLOCKSIZE + sidelen*x0,
-				data->sectorpos_base.Y*MAP_BLOCKSIZE + sidelen*z0
-			);
-			// Maximum edge of part of division
-			v2s16 p2d_max(
-				data->sectorpos_base.X*MAP_BLOCKSIZE + sidelen + sidelen*x0 - 1,
-				data->sectorpos_base.Y*MAP_BLOCKSIZE + sidelen + sidelen*z0 - 1
-			);
-			// Amount of trees
-			u32 tree_count = area * tree_amount_2d(data->seed, p2d_center);
-			// Put trees in random places on part of division
-			for(u32 i=0; i<tree_count; i++)
-			{
-				s16 x = myrand_range(p2d_min.X, p2d_max.X);
-				s16 z = myrand_range(p2d_min.Y, p2d_max.Y);
-				s16 y = find_ground_level(data->vmanip, v2s16(x,z));
-				// Don't make a tree under water level
-				if(y < WATER_LEVEL - 1)
-					continue;
-				// Don't make a tree so high that it doesn't fit
-				if(y > y_nodes_max - 6)
-					continue;
-				v3s16 p(x,y,z);
-				{
-					u32 i = data->vmanip.m_area.index(v3s16(p));
-					MapNode *n = &data->vmanip.m_data[i];
-					if(n->d != CONTENT_MUD && n->d != CONTENT_GRASS && n->d != CONTENT_SAND)
-						continue;
-					// Papyrus grows only on mud and in water
-					if(n->d == CONTENT_MUD && y == WATER_LEVEL - 1)
-					{
-						p.Y++;
-						make_papyrus(data->vmanip, p);
-					}
-					// Don't make a tree under water level
-					if(y < WATER_LEVEL)
-						continue;
-					// Trees grow only on mud and grass
-					if(n->d == CONTENT_MUD || n->d == CONTENT_GRASS)
-					{
-						p.Y++;
-						make_tree(data->vmanip, p);
-					}
-					// Cactii grow only on sand
-					else if(n->d == CONTENT_SAND)
-					{
-						p.Y++;
-						make_cactus(data->vmanip, p);
-					}
-				}
-			}
-		}
-		/*u32 tree_max = relative_area / 60;
-		//u32 count = myrand_range(0, tree_max);
-		for(u32 i=0; i<count; i++)
-		{
-			s16 x = myrand_range(0, data->sectorpos_base_size*MAP_BLOCKSIZE-1);
-			s16 z = myrand_range(0, data->sectorpos_base_size*MAP_BLOCKSIZE-1);
-			x += data->sectorpos_base.X*MAP_BLOCKSIZE;
-			z += data->sectorpos_base.Y*MAP_BLOCKSIZE;
-			s16 y = find_ground_level(data->vmanip, v2s16(x,z));
-			// Don't make a tree under water level
-			if(y < WATER_LEVEL)
-				continue;
-			v3s16 p(x,y+1,z);
-			// Make a tree
-			make_tree(data->vmanip, p);
-		}*/
-	}
-
-	}//timer1
-#endif
-
-#if 1
-	{
-	// 19ms @cs=8
-	//TimeTaker timer1("grow grass");
-
-	/*
-		Grow grass
-	*/
-
-	/*for(s16 x=0-4; x<data->sectorpos_base_size*MAP_BLOCKSIZE+4; x++)
-	for(s16 z=0-4; z<data->sectorpos_base_size*MAP_BLOCKSIZE+4; z++)*/
-	for(s16 x=0-data->max_spread_amount;
-			x<data->sectorpos_base_size*MAP_BLOCKSIZE+data->max_spread_amount;
-			x++)
-	for(s16 z=0-data->max_spread_amount;
-			z<data->sectorpos_base_size*MAP_BLOCKSIZE+data->max_spread_amount;
-			z++)
-	{
-		// Node position in 2d
-		v2s16 p2d = data->sectorpos_base*MAP_BLOCKSIZE + v2s16(x,z);
-		
-		/*
-			Find the lowest surface to which enough light ends up
-			to make grass grow.
-
-			Basically just wait until not air and not leaves.
-		*/
-		s16 surface_y = 0;
-		{
-			v3s16 em = data->vmanip.m_area.getExtent();
-			u32 i = data->vmanip.m_area.index(v3s16(p2d.X, y_nodes_max, p2d.Y));
-			s16 y;
-			// Go to ground level
-			for(y=y_nodes_max; y>=y_nodes_min; y--)
-			{
-				MapNode &n = data->vmanip.m_data[i];
-				if(n.d != CONTENT_AIR
-						&& n.d != CONTENT_LEAVES)
-					break;
-				data->vmanip.m_area.add_y(em, i, -1);
-			}
-			if(y >= y_nodes_min)
-				surface_y = y;
-			else
-				surface_y = y_nodes_min;
-		}
-		
-		u32 i = data->vmanip.m_area.index(p2d.X, surface_y, p2d.Y);
-		MapNode *n = &data->vmanip.m_data[i];
-		if(n->d == CONTENT_MUD)
-			n->d = CONTENT_GRASS;
-	}
-
-	}//timer1
-#endif
-
-	/*
-		Initial lighting (sunlight)
-	*/
-
-	core::map<v3s16, bool> light_sources;
-
-	{
-	// 750ms @cs=8, can't optimize more
-	TimeTaker timer1("initial lighting");
-
-	// NOTE: This is no used... umm... for some reason!
-#if 0
-	/*
-		Go through the edges and add all nodes that have light to light_sources
-	*/
-	
-	// Four edges
-	for(s16 i=0; i<4; i++)
-	// Edge length
-	for(s16 j=lighting_min_d;
-			j<=lighting_max_d;
-			j++)
-	{
-		s16 x;
-		s16 z;
-		// +-X
-		if(i == 0 || i == 1)
-		{
-			x = (i==0) ? lighting_min_d : lighting_max_d;
-			if(i == 0)
-				z = lighting_min_d;
-			else
-				z = lighting_max_d;
-		}
-		// +-Z
-		else
-		{
-			z = (i==0) ? lighting_min_d : lighting_max_d;
-			if(i == 0)
-				x = lighting_min_d;
-			else
-				x = lighting_max_d;
-		}
-		
-		// Node position in 2d
-		v2s16 p2d = data->sectorpos_base*MAP_BLOCKSIZE + v2s16(x,z);
-
-		{
-			v3s16 em = data->vmanip.m_area.getExtent();
-			s16 y_start = y_nodes_max;
-			u32 i = data->vmanip.m_area.index(v3s16(p2d.X, y_start, p2d.Y));
-			for(s16 y=y_start; y>=y_nodes_min; y--)
-			{
-				MapNode *n = &data->vmanip.m_data[i];
-				if(n->getLight(LIGHTBANK_DAY) != 0)
-				{
-					light_sources.insert(v3s16(p2d.X, y, p2d.Y), true);
-				}
-				//NOTE: This is broken, at least the index has to
-				// be incremented
-			}
-		}
-	}
-#endif
-
-#if 1
-	/*
-		Go through the edges and apply sunlight to them, not caring
-		about neighbors
-	*/
-	
-	// Four edges
-	for(s16 i=0; i<4; i++)
-	// Edge length
-	for(s16 j=lighting_min_d;
-			j<=lighting_max_d;
-			j++)
-	{
-		s16 x;
-		s16 z;
-		// +-X
-		if(i == 0 || i == 1)
-		{
-			x = (i==0) ? lighting_min_d : lighting_max_d;
-			if(i == 0)
-				z = lighting_min_d;
-			else
-				z = lighting_max_d;
-		}
-		// +-Z
-		else
-		{
-			z = (i==0) ? lighting_min_d : lighting_max_d;
-			if(i == 0)
-				x = lighting_min_d;
-			else
-				x = lighting_max_d;
-		}
-		
-		// Node position in 2d
-		v2s16 p2d = data->sectorpos_base*MAP_BLOCKSIZE + v2s16(x,z);
-		
-		// Loop from top to down
-		{
-			u8 light = LIGHT_SUN;
-			v3s16 em = data->vmanip.m_area.getExtent();
-			s16 y_start = y_nodes_max;
-			u32 i = data->vmanip.m_area.index(v3s16(p2d.X, y_start, p2d.Y));
-			for(s16 y=y_start; y>=y_nodes_min; y--)
-			{
-				MapNode *n = &data->vmanip.m_data[i];
-				if(light_propagates_content(n->d) == false)
-				{
-					light = 0;
-				}
-				else if(light != LIGHT_SUN
-					|| sunlight_propagates_content(n->d) == false)
-				{
-					if(light > 0)
-						light--;
-				}
-				
-				n->setLight(LIGHTBANK_DAY, light);
-				n->setLight(LIGHTBANK_NIGHT, 0);
-				
-				if(light != 0)
-				{
-					// Insert light source
-					light_sources.insert(v3s16(p2d.X, y, p2d.Y), true);
-				}
-				
-				// Increment index by y
-				data->vmanip.m_area.add_y(em, i, -1);
-			}
-		}
-	}
-#endif
-
-	/*for(s16 x=0; x<data->sectorpos_base_size*MAP_BLOCKSIZE; x++)
-	for(s16 z=0; z<data->sectorpos_base_size*MAP_BLOCKSIZE; z++)*/
-	/*for(s16 x=0-data->max_spread_amount+1;
-			x<data->sectorpos_base_size*MAP_BLOCKSIZE+data->max_spread_amount-1;
-			x++)
-	for(s16 z=0-data->max_spread_amount+1;
-			z<data->sectorpos_base_size*MAP_BLOCKSIZE+data->max_spread_amount-1;
-			z++)*/
-#if 1
-	/*
-		This has to be 1 smaller than the actual area, because
-		neighboring nodes are checked.
-	*/
-	for(s16 x=lighting_min_d+1;
-			x<=lighting_max_d-1;
-			x++)
-	for(s16 z=lighting_min_d+1;
-			z<=lighting_max_d-1;
-			z++)
-	{
-		// Node position in 2d
-		v2s16 p2d = data->sectorpos_base*MAP_BLOCKSIZE + v2s16(x,z);
-		
-		/*
-			Apply initial sunlight
-		*/
-		{
-			u8 light = LIGHT_SUN;
-			bool add_to_sources = false;
-			v3s16 em = data->vmanip.m_area.getExtent();
-			s16 y_start = y_nodes_max;
-			u32 i = data->vmanip.m_area.index(v3s16(p2d.X, y_start, p2d.Y));
-			for(s16 y=y_start; y>=y_nodes_min; y--)
-			{
-				MapNode *n = &data->vmanip.m_data[i];
-
-				if(light_propagates_content(n->d) == false)
-				{
-					light = 0;
-				}
-				else if(light != LIGHT_SUN
-					|| sunlight_propagates_content(n->d) == false)
-				{
-					if(light > 0)
-						light--;
-				}
-				
-				// This doesn't take much time
-				if(add_to_sources == false)
-				{
-					/*
-						Check sides. If side is not air or water, start
-						adding to light_sources.
-					*/
-					v3s16 dirs4[4] = {
-						v3s16(0,0,1), // back
-						v3s16(1,0,0), // right
-						v3s16(0,0,-1), // front
-						v3s16(-1,0,0), // left
-					};
-					for(u32 di=0; di<4; di++)
-					{
-						v3s16 dirp = dirs4[di];
-						u32 i2 = i;
-						data->vmanip.m_area.add_p(em, i2, dirp);
-						MapNode *n2 = &data->vmanip.m_data[i2];
-						if(
-							n2->d != CONTENT_AIR
-							&& n2->d != CONTENT_WATERSOURCE
-							&& n2->d != CONTENT_WATER
-						){
-							add_to_sources = true;
-							break;
-						}
-					}
-				}
-				
-				n->setLight(LIGHTBANK_DAY, light);
-				n->setLight(LIGHTBANK_NIGHT, 0);
-				
-				// This doesn't take much time
-				if(light != 0 && add_to_sources)
-				{
-					// Insert light source
-					light_sources.insert(v3s16(p2d.X, y, p2d.Y), true);
-				}
-				
-				// Increment index by y
-				data->vmanip.m_area.add_y(em, i, -1);
-			}
-		}
-	}
 #endif
-
-	}//timer1
-
-	// Spread light around
-	{
-		TimeTaker timer("makeChunk() spreadLight");
-		data->vmanip.spreadLight(LIGHTBANK_DAY, light_sources);
-	}
-	
-	/*
-		Generation ended
-	*/
-
-	timer_generate.stop();
 }
 
-//###################################################################
-//###################################################################
-//###################################################################
-//###################################################################
-//###################################################################
-//###################################################################
-//###################################################################
-//###################################################################
-//###################################################################
-//###################################################################
-//###################################################################
-//###################################################################
-//###################################################################
-//###################################################################
-//###################################################################
-
-void ServerMap::initChunkMake(ChunkMakeData &data, v2s16 chunkpos)
+void ServerMap::initBlockMake(mapgen::BlockMakeData *data, v3s16 blockpos)
 {
-	if(m_chunksize == 0)
-	{
-		data.no_op = true;
-		return;
-	}
-
-	data.no_op = false;
+	/*dstream<<"initBlockMake(): ("<<blockpos.X<<","<<blockpos.Y<<","
+			<<blockpos.Z<<")"<<std::endl;*/
 
-	// The distance how far into the neighbors the generator is allowed to go.
-	s16 max_spread_amount_sectors = 2;
-	assert(max_spread_amount_sectors <= m_chunksize);
-	s16 max_spread_amount = max_spread_amount_sectors * MAP_BLOCKSIZE;
-
-	s16 y_blocks_min = -4;
-	s16 y_blocks_max = 3;
-
-	v2s16 sectorpos_base = chunk_to_sector(chunkpos);
-	s16 sectorpos_base_size = m_chunksize;
-
-	v2s16 sectorpos_bigbase =
-			sectorpos_base - v2s16(1,1) * max_spread_amount_sectors;
-	s16 sectorpos_bigbase_size =
-			sectorpos_base_size + 2 * max_spread_amount_sectors;
-	
-	// Check limits
-	const s16 limit = MAP_GENERATION_LIMIT / MAP_BLOCKSIZE;
-	if(sectorpos_bigbase.X < -limit
-	|| sectorpos_bigbase.X + sectorpos_bigbase_size >= limit
-	|| sectorpos_bigbase.Y < -limit
-	|| sectorpos_bigbase.Y + sectorpos_bigbase_size >= limit)
-	{
-		data.no_op = true;
-		return;
-	}
-
-	data.seed = m_seed;
-	data.chunkpos = chunkpos;
-	data.y_blocks_min = y_blocks_min;
-	data.y_blocks_max = y_blocks_max;
-	data.sectorpos_base = sectorpos_base;
-	data.sectorpos_base_size = sectorpos_base_size;
-	data.sectorpos_bigbase = sectorpos_bigbase;
-	data.sectorpos_bigbase_size = sectorpos_bigbase_size;
-	data.max_spread_amount = max_spread_amount;
+	data->no_op = false;
+	data->seed = m_seed;
+	data->blockpos = blockpos;
 
 	/*
-		Create the whole area of this and the neighboring chunks
+		Create the whole area of this and the neighboring blocks
 	*/
 	{
-		TimeTaker timer("initChunkMake() create area");
+		//TimeTaker timer("initBlockMake() create area");
 		
-		for(s16 x=0; x<sectorpos_bigbase_size; x++)
-		for(s16 z=0; z<sectorpos_bigbase_size; z++)
+		for(s16 x=-1; x<=1; x++)
+		for(s16 z=-1; z<=1; z++)
 		{
-			v2s16 sectorpos = sectorpos_bigbase + v2s16(x,z);
+			v2s16 sectorpos(blockpos.X+x, blockpos.Z+z);
+			// Sector metadata is loaded from disk if not already loaded.
 			ServerMapSector *sector = createSector(sectorpos);
 			assert(sector);
 
-			for(s16 y=y_blocks_min; y<=y_blocks_max; y++)
+			for(s16 y=-1; y<=1; y++)
 			{
-				v3s16 blockpos(sectorpos.X, y, sectorpos.Y);
 				MapBlock *block = createBlock(blockpos);
 
 				// Lighting won't be calculated
-				//block->setLightingExpired(true);
+				block->setLightingExpired(true);
 				// Lighting will be calculated
-				block->setLightingExpired(false);
+				//block->setLightingExpired(false);
 
 				/*
 					Block gets sunlight if this is true.
 
 					This should be set to true when the top side of a block
 					is completely exposed to the sky.
-
-					Actually this doesn't matter now because the
-					initial lighting is done here.
 				*/
-				block->setIsUnderground(y != y_blocks_max);
+				block->setIsUnderground(false);
 			}
 		}
 	}
@@ -3702,195 +2016,147 @@ void ServerMap::initChunkMake(ChunkMakeData &data, v2s16 chunkpos)
 		Now we have a big empty area.
 
 		Make a ManualMapVoxelManipulator that contains this and the
-		neighboring chunks
+		neighboring blocks
 	*/
 	
-	v3s16 bigarea_blocks_min(
-		sectorpos_bigbase.X,
-		y_blocks_min,
-		sectorpos_bigbase.Y
-	);
-	v3s16 bigarea_blocks_max(
-		sectorpos_bigbase.X + sectorpos_bigbase_size - 1,
-		y_blocks_max,
-		sectorpos_bigbase.Y + sectorpos_bigbase_size - 1
-	);
+	v3s16 bigarea_blocks_min = blockpos - v3s16(1,1,1);
+	v3s16 bigarea_blocks_max = blockpos + v3s16(1,1,1);
 	
-	data.vmanip.setMap(this);
+	data->vmanip = new ManualMapVoxelManipulator(this);
+	//data->vmanip->setMap(this);
+
 	// Add the area
 	{
-		TimeTaker timer("initChunkMake() initialEmerge");
-		data.vmanip.initialEmerge(bigarea_blocks_min, bigarea_blocks_max);
+		//TimeTaker timer("initBlockMake() initialEmerge");
+		data->vmanip->initialEmerge(bigarea_blocks_min, bigarea_blocks_max);
 	}
-	
+
+	// Data is ready now.
 }
 
-MapChunk* ServerMap::finishChunkMake(ChunkMakeData &data,
+MapBlock* ServerMap::finishBlockMake(mapgen::BlockMakeData *data,
 		core::map<v3s16, MapBlock*> &changed_blocks)
 {
-	if(data.no_op)
+	v3s16 blockpos = data->blockpos;
+	/*dstream<<"finishBlockMake(): ("<<blockpos.X<<","<<blockpos.Y<<","
+			<<blockpos.Z<<")"<<std::endl;*/
+
+	if(data->no_op)
+	{
+		dstream<<"finishBlockMake(): no-op"<<std::endl;
 		return NULL;
+	}
+
+	/*dstream<<"Resulting vmanip:"<<std::endl;
+	data->vmanip.print(dstream);*/
 	
 	/*
 		Blit generated stuff to map
+		NOTE: blitBackAll adds nearly everything to changed_blocks
 	*/
 	{
 		// 70ms @cs=8
-		//TimeTaker timer("generateChunkRaw() blitBackAll");
-		data.vmanip.blitBackAll(&changed_blocks);
+		//TimeTaker timer("finishBlockMake() blitBackAll");
+		data->vmanip->blitBackAll(&changed_blocks);
 	}
-
-	/*
-		Update day/night difference cache of the MapBlocks
-	*/
-	{
-		for(core::map<v3s16, MapBlock*>::Iterator i = changed_blocks.getIterator();
-				i.atEnd() == false; i++)
-		{
-			MapBlock *block = i.getNode()->getValue();
-			block->updateDayNightDiff();
-		}
-	}
-
+#if 1
+	dstream<<"finishBlockMake: changed_blocks.size()="
+			<<changed_blocks.size()<<std::endl;
+#endif
 	/*
 		Copy transforming liquid information
 	*/
-	while(data.transforming_liquid.size() > 0)
+	while(data->transforming_liquid.size() > 0)
 	{
-		v3s16 p = data.transforming_liquid.pop_front();
+		v3s16 p = data->transforming_liquid.pop_front();
 		m_transforming_liquid.push_back(p);
 	}
+	
+	/*
+		Get central block
+	*/
+	MapBlock *block = getBlockNoCreateNoEx(data->blockpos);
+	assert(block);
 
 	/*
-		Add random objects to blocks
+		Set is_underground flag for lighting with sunlight
 	*/
-	{
-		for(s16 x=0; x<data.sectorpos_base_size; x++)
-		for(s16 z=0; z<data.sectorpos_base_size; z++)
-		{
-			v2s16 sectorpos = data.sectorpos_base + v2s16(x,z);
-			ServerMapSector *sector = createSector(sectorpos);
-			assert(sector);
 
-			for(s16 y=data.y_blocks_min; y<=data.y_blocks_max; y++)
-			{
-				v3s16 blockpos(sectorpos.X, y, sectorpos.Y);
-				MapBlock *block = createBlock(blockpos);
-				addRandomObjects(block);
-			}
-		}
-	}
+	block->setIsUnderground(mapgen::block_is_underground(data->seed, blockpos));
 
 	/*
-		Create chunk metadata
+		Add sunlight to central block.
+		This makes in-dark-spawning monsters to not flood the whole thing.
+		Do not spread the light, though.
 	*/
-
-	for(s16 x=-1; x<=1; x++)
-	for(s16 y=-1; y<=1; y++)
-	{
-		v2s16 chunkpos0 = data.chunkpos + v2s16(x,y);
-		// Add chunk meta information
-		MapChunk *chunk = getChunk(chunkpos0);
-		if(chunk == NULL)
-		{
-			chunk = new MapChunk();
-			m_chunks.insert(chunkpos0, chunk);
-		}
-		//chunk->setIsVolatile(true);
-		if(chunk->getGenLevel() > GENERATED_PARTLY)
-			chunk->setGenLevel(GENERATED_PARTLY);
-	}
+	/*core::map<v3s16, bool> light_sources;
+	bool black_air_left = false;
+	block->propagateSunlight(light_sources, true, &black_air_left);*/
 
 	/*
-		Set central chunk non-volatile
+		NOTE: Lighting and object adding shouldn't really be here, but
+		lighting is a bit tricky to move properly to makeBlock.
+		TODO: Do this the right way anyway.
 	*/
-	MapChunk *chunk = getChunk(data.chunkpos);
-	assert(chunk);
-	// Set non-volatile
-	//chunk->setIsVolatile(false);
-	chunk->setGenLevel(GENERATED_FULLY);
-	
+
 	/*
-		Save changed parts of map
+		Update lighting
 	*/
-	save(true);
-	
-	return chunk;
-}
 
+	core::map<v3s16, MapBlock*> lighting_update_blocks;
+	// Center block
+	lighting_update_blocks.insert(block->getPos(), block);
 #if 0
-// NOTE: Deprecated
-MapChunk* ServerMap::generateChunkRaw(v2s16 chunkpos,
-		core::map<v3s16, MapBlock*> &changed_blocks,
-		bool force)
-{
-	DSTACK(__FUNCTION_NAME);
+	// All modified blocks
+	for(core::map<v3s16, MapBlock*>::Iterator
+			i = changed_blocks.getIterator();
+			i.atEnd() == false; i++)
+	{
+		lighting_update_blocks.insert(i.getNode()->getKey(),
+				i.getNode()->getValue());
+	}
+#endif
+	updateLighting(lighting_update_blocks, changed_blocks);
+	
+	/*
+		Add random objects to block
+	*/
+	mapgen::add_random_objects(block);
 
 	/*
-		Don't generate if already fully generated
+		Go through changed blocks
 	*/
-	if(force == false)
+	for(core::map<v3s16, MapBlock*>::Iterator i = changed_blocks.getIterator();
+			i.atEnd() == false; i++)
 	{
-		MapChunk *chunk = getChunk(chunkpos);
-		if(chunk != NULL && chunk->getGenLevel() == GENERATED_FULLY)
-		{
-			dstream<<"generateChunkRaw(): Chunk "
-					<<"("<<chunkpos.X<<","<<chunkpos.Y<<")"
-					<<" already generated"<<std::endl;
-			return chunk;
-		}
+		MapBlock *block = i.getNode()->getValue();
+		assert(block);
+		/*
+			Update day/night difference cache of the MapBlocks
+		*/
+		block->updateDayNightDiff();
+		/*
+			Set block as modified
+		*/
+		block->raiseModified(MOD_STATE_WRITE_NEEDED);
 	}
 
-	dstream<<"generateChunkRaw(): Generating chunk "
-			<<"("<<chunkpos.X<<","<<chunkpos.Y<<")"
-			<<std::endl;
-	
-	TimeTaker timer("generateChunkRaw()");
-
-	ChunkMakeData data;
-	
-	// Initialize generation
-	initChunkMake(data, chunkpos);
+	/*
+		Set central block as generated
+	*/
+	block->setGenerated(true);
 	
-	// Generate stuff
-	makeChunk(&data);
-
-	// Finalize generation
-	MapChunk *chunk = finishChunkMake(data, changed_blocks);
-
 	/*
-		Return central chunk (which was requested)
+		Save changed parts of map
+		NOTE: Will be saved later.
 	*/
-	return chunk;
-}
+	//save(true);
 
-// NOTE: Deprecated
-MapChunk* ServerMap::generateChunk(v2s16 chunkpos1,
-		core::map<v3s16, MapBlock*> &changed_blocks)
-{
-	dstream<<"generateChunk(): Generating chunk "
-			<<"("<<chunkpos1.X<<","<<chunkpos1.Y<<")"
-			<<std::endl;
-	
-	/*for(s16 x=-1; x<=1; x++)
-	for(s16 y=-1; y<=1; y++)*/
-	for(s16 x=-0; x<=0; x++)
-	for(s16 y=-0; y<=0; y++)
-	{
-		v2s16 chunkpos0 = chunkpos1 + v2s16(x,y);
-		MapChunk *chunk = getChunk(chunkpos0);
-		// Skip if already generated
-		if(chunk != NULL && chunk->getGenLevel() == GENERATED_FULLY)
-			continue;
-		generateChunkRaw(chunkpos0, changed_blocks);
-	}
+	/*dstream<<"finishBlockMake() done for ("<<blockpos.X<<","<<blockpos.Y<<","
+			<<blockpos.Z<<")"<<std::endl;*/
 	
-	assert(chunkNonVolatile(chunkpos1));
-
-	MapChunk *chunk = getChunk(chunkpos1);
-	return chunk;
+	return block;
 }
-#endif
 
 ServerMapSector * ServerMap::createSector(v2s16 p2d)
 {
@@ -3908,7 +2174,12 @@ ServerMapSector * ServerMap::createSector(v2s16 p2d)
 	/*
 		Try to load it from disk (with blocks)
 	*/
-	if(loadSectorFull(p2d) == true)
+	//if(loadSectorFull(p2d) == true)
+
+	/*
+		Try to load metadata from disk
+	*/
+	if(loadSectorMeta(p2d) == true)
 	{
 		ServerMapSector *sector = (ServerMapSector*)getSectorNoGenerateNoEx(p2d);
 		if(sector == NULL)
@@ -3945,127 +2216,25 @@ ServerMapSector * ServerMap::createSector(v2s16 p2d)
 	return sector;
 }
 
-#if 0
-MapSector * ServerMap::emergeSector(v2s16 p2d,
-		core::map<v3s16, MapBlock*> &changed_blocks)
-{
-	DSTACK("%s: p2d=(%d,%d)",
-			__FUNCTION_NAME,
-			p2d.X, p2d.Y);
-	
-	/*
-		Check chunk status
-	*/
-	v2s16 chunkpos = sector_to_chunk(p2d);
-	/*bool chunk_nonvolatile = false;
-	MapChunk *chunk = getChunk(chunkpos);
-	if(chunk && chunk->getIsVolatile() == false)
-		chunk_nonvolatile = true;*/
-	bool chunk_nonvolatile = chunkNonVolatile(chunkpos);
-
-	/*
-		If chunk is not fully generated, generate chunk
-	*/
-	if(chunk_nonvolatile == false)
-	{
-		// Generate chunk and neighbors
-		generateChunk(chunkpos, changed_blocks);
-	}
-	
-	/*
-		Return sector if it exists now
-	*/
-	MapSector *sector = getSectorNoGenerateNoEx(p2d);
-	if(sector != NULL)
-		return sector;
-	
-	/*
-		Try to load it from disk
-	*/
-	if(loadSectorFull(p2d) == true)
-	{
-		MapSector *sector = getSectorNoGenerateNoEx(p2d);
-		if(sector == NULL)
-		{
-			dstream<<"ServerMap::emergeSector(): loadSectorFull didn't make a sector"<<std::endl;
-			throw InvalidPositionException("");
-		}
-		return sector;
-	}
-
-	/*
-		generateChunk should have generated the sector
-	*/
-	//assert(0);
-	
-	dstream<<"WARNING: ServerMap::emergeSector: Cannot find sector ("
-			<<p2d.X<<","<<p2d.Y<<" and chunk is already generated. "
-			<<std::endl;
-
-#if 0
-	dstream<<"WARNING: Creating an empty sector."<<std::endl;
-
-	return createSector(p2d);
-	
-#endif
-	
-#if 1
-	dstream<<"WARNING: Forcing regeneration of chunk."<<std::endl;
-
-	// Generate chunk
-	generateChunkRaw(chunkpos, changed_blocks, true);
-
-	/*
-		Return sector if it exists now
-	*/
-	sector = getSectorNoGenerateNoEx(p2d);
-	if(sector != NULL)
-		return sector;
-	
-	dstream<<"ERROR: Could not get sector from anywhere."<<std::endl;
-	
-	assert(0);
-#endif
-	
-	/*
-		Generate directly
-	*/
-	//return generateSector();
-}
-#endif
-
 /*
-	NOTE: This is not used for main map generation, only for blocks
-	that are very high or low
+	This is a quick-hand function for calling makeBlock().
 */
 MapBlock * ServerMap::generateBlock(
 		v3s16 p,
-		MapBlock *original_dummy,
-		ServerMapSector *sector,
-		core::map<v3s16, MapBlock*> &changed_blocks,
-		core::map<v3s16, MapBlock*> &lighting_invalidated_blocks
+		core::map<v3s16, MapBlock*> &modified_blocks
 )
 {
-	DSTACKF("%s: p=(%d,%d,%d)",
-			__FUNCTION_NAME,
-			p.X, p.Y, p.Z);
-
-	// If chunks are disabled
-	/*if(m_chunksize == 0)
-	{
-		dstream<<"ServerMap::generateBlock(): Chunks disabled -> "
-				<<"not generating."<<std::endl;
-		return NULL;
-	}*/
+	DSTACKF("%s: p=(%d,%d,%d)", __FUNCTION_NAME, p.X, p.Y, p.Z);
 	
 	/*dstream<<"generateBlock(): "
 			<<"("<<p.X<<","<<p.Y<<","<<p.Z<<")"
 			<<std::endl;*/
 	
-	MapBlock *block = original_dummy;
+	TimeTaker timer("generateBlock");
+	
+	//MapBlock *block = original_dummy;
 			
 	v2s16 p2d(p.X, p.Z);
-	s16 block_y = p.Y;
 	v2s16 p2d_nodes = p2d * MAP_BLOCKSIZE;
 	
 	/*
@@ -4078,603 +2247,73 @@ MapBlock * ServerMap::generateBlock(
 	}
 
 	/*
-		If block doesn't exist, create one.
-		If it exists, it is a dummy. In that case unDummify() it.
-
-		NOTE: This already sets the map as the parent of the block
+		Create block make data
 	*/
-	if(block == NULL)
-	{
-		block = sector->createBlankBlockNoInsert(block_y);
-	}
-	else
-	{
-		// Remove the block so that nobody can get a half-generated one.
-		sector->removeBlock(block);
-		// Allocate the block to contain the generated data
-		block->unDummify();
-	}
-	
-#if 0
+	mapgen::BlockMakeData data;
+	initBlockMake(&data, p);
+
 	/*
-		Generate a completely empty block
+		Generate block
 	*/
-	for(s16 z0=0; z0<MAP_BLOCKSIZE; z0++)
-	for(s16 x0=0; x0<MAP_BLOCKSIZE; x0++)
 	{
-		for(s16 y0=0; y0<MAP_BLOCKSIZE; y0++)
-		{
-			MapNode n;
-			n.d = CONTENT_AIR;
-			block->setNode(v3s16(x0,y0,z0), n);
-		}
+		TimeTaker t("mapgen::make_block()");
+		mapgen::make_block(&data);
 	}
-#else
-	/*
-		Generate a proper block
-	*/
-	
-	u8 water_material = CONTENT_WATERSOURCE;
-	
-	s32 lowest_ground_y = 32767;
-	s32 highest_ground_y = -32768;
-	
-	for(s16 z0=0; z0<MAP_BLOCKSIZE; z0++)
-	for(s16 x0=0; x0<MAP_BLOCKSIZE; x0++)
-	{
-		//dstream<<"generateBlock: x0="<<x0<<", z0="<<z0<<std::endl;
-
-		//s16 surface_y = 0;
-
-		s16 mud_add_amount = get_mud_add_amount(m_seed, p2d_nodes+v2s16(x0,z0));
 
-		s16 surface_y = base_rock_level_2d(m_seed, p2d_nodes+v2s16(x0,z0))
-				+ mud_add_amount;
-		// If chunks are disabled
-		if(m_chunksize == 0)
-			surface_y = WATER_LEVEL + 1;
-
-		if(surface_y < lowest_ground_y)
-			lowest_ground_y = surface_y;
-		if(surface_y > highest_ground_y)
-			highest_ground_y = surface_y;
-
-		s32 surface_depth = AVERAGE_MUD_AMOUNT;
-		
-		for(s16 y0=0; y0<MAP_BLOCKSIZE; y0++)
-		{
-			s16 real_y = block_y * MAP_BLOCKSIZE + y0;
-			MapNode n;
-			/*
-				Calculate lighting
-				
-				NOTE: If there are some man-made structures above the
-				newly created block, they won't be taken into account.
-			*/
-			if(real_y > surface_y)
-				n.setLight(LIGHTBANK_DAY, LIGHT_SUN);
-
-			/*
-				Calculate material
-			*/
-
-			// If node is over heightmap y, it's air or water
-			if(real_y > surface_y)
-			{
-				// If under water level, it's water
-				if(real_y < WATER_LEVEL)
-				{
-					n.d = water_material;
-					n.setLight(LIGHTBANK_DAY,
-							diminish_light(LIGHT_SUN, WATER_LEVEL-real_y+1));
-					/*
-						Add to transforming liquid queue (in case it'd
-						start flowing)
-					*/
-					v3s16 real_pos = v3s16(x0,y0,z0) + p*MAP_BLOCKSIZE;
-					m_transforming_liquid.push_back(real_pos);
-				}
-				// else air
-				else
-					n.d = CONTENT_AIR;
-			}
-			// Else it's ground or caves (air)
-			else
-			{
-				// If it's surface_depth under ground, it's stone
-				if(real_y <= surface_y - surface_depth)
-				{
-					n.d = CONTENT_STONE;
-				}
-				else
-				{
-					// It is mud if it is under the first ground
-					// level or under water
-					if(real_y < WATER_LEVEL || real_y <= surface_y - 1)
-					{
-						n.d = CONTENT_MUD;
-					}
-					else
-					{
-						n.d = CONTENT_GRASS;
-					}
-
-					//n.d = CONTENT_MUD;
-					
-					/*// If under water level, it's mud
-					if(real_y < WATER_LEVEL)
-						n.d = CONTENT_MUD;
-					// Only the topmost node is grass
-					else if(real_y <= surface_y - 1)
-						n.d = CONTENT_MUD;
-					else
-						n.d = CONTENT_GRASS;*/
-				}
-			}
-
-			block->setNode(v3s16(x0,y0,z0), n);
-		}
-	}
-	
 	/*
-		Calculate some helper variables
+		Blit data back on map, update lighting, add mobs and whatever this does
 	*/
-	
-	// Completely underground if the highest part of block is under lowest
-	// ground height.
-	// This has to be very sure; it's probably one too strict now but
-	// that's just better.
-	bool completely_underground =
-			block_y * MAP_BLOCKSIZE + MAP_BLOCKSIZE < lowest_ground_y;
-
-	bool some_part_underground = block_y * MAP_BLOCKSIZE <= highest_ground_y;
-
-	bool mostly_underwater_surface = false;
-	if(highest_ground_y < WATER_LEVEL
-			&& some_part_underground && !completely_underground)
-		mostly_underwater_surface = true;
+	finishBlockMake(&data, modified_blocks);
 
 	/*
-		Get local attributes
+		Get central block
 	*/
-
-	//dstream<<"generateBlock(): Getting local attributes"<<std::endl;
-
-	float caves_amount = 0.5;
+	MapBlock *block = getBlockNoCreateNoEx(p);
+	assert(block);
 
 #if 0
-	{
-		/*
-			NOTE: BEWARE: Too big amount of attribute points slows verything
-			down by a lot.
-			1 interpolation from 5000 points takes 2-3ms.
-		*/
-		//TimeTaker timer("generateBlock() local attribute retrieval");
-		v2s16 nodepos2d = p2d * MAP_BLOCKSIZE;
-		PointAttributeList *list_caves_amount = m_padb.getList("caves_amount");
-		caves_amount = list_caves_amount->getInterpolatedFloat(nodepos2d);
-	}
-#endif
-
-	//dstream<<"generateBlock(): Done"<<std::endl;
-
 	/*
-		Generate caves
+		Check result
 	*/
-
-	// Initialize temporary table
-	const s32 ued = MAP_BLOCKSIZE;
-	bool underground_emptiness[ued*ued*ued];
-	for(s32 i=0; i<ued*ued*ued; i++)
-	{
-		underground_emptiness[i] = 0;
-	}
-	
-	// Fill table
-#if 1
+	bool erroneus_content = false;
+	for(s16 z0=0; z0<MAP_BLOCKSIZE; z0++)
+	for(s16 y0=0; y0<MAP_BLOCKSIZE; y0++)
+	for(s16 x0=0; x0<MAP_BLOCKSIZE; x0++)
 	{
-		/*
-			Initialize orp and ors. Try to find if some neighboring
-			MapBlock has a tunnel ended in its side
-		*/
-
-		v3f orp(
-			(float)(myrand()%ued)+0.5,
-			(float)(myrand()%ued)+0.5,
-			(float)(myrand()%ued)+0.5
-		);
-		
-		bool found_existing = false;
-
-		// Check z-
-		try
-		{
-			s16 z = -1;
-			for(s16 y=0; y<ued; y++)
-			for(s16 x=0; x<ued; x++)
-			{
-				v3s16 ap = v3s16(x,y,z) + block->getPosRelative();
-				if(getNode(ap).d == CONTENT_AIR)
-				{
-					orp = v3f(x+1,y+1,0);
-					found_existing = true;
-					goto continue_generating;
-				}
-			}
-		}
-		catch(InvalidPositionException &e){}
-		
-		// Check z+
-		try
-		{
-			s16 z = ued;
-			for(s16 y=0; y<ued; y++)
-			for(s16 x=0; x<ued; x++)
-			{
-				v3s16 ap = v3s16(x,y,z) + block->getPosRelative();
-				if(getNode(ap).d == CONTENT_AIR)
-				{
-					orp = v3f(x+1,y+1,ued-1);
-					found_existing = true;
-					goto continue_generating;
-				}
-			}
-		}
-		catch(InvalidPositionException &e){}
-		
-		// Check x-
-		try
-		{
-			s16 x = -1;
-			for(s16 y=0; y<ued; y++)
-			for(s16 z=0; z<ued; z++)
-			{
-				v3s16 ap = v3s16(x,y,z) + block->getPosRelative();
-				if(getNode(ap).d == CONTENT_AIR)
-				{
-					orp = v3f(0,y+1,z+1);
-					found_existing = true;
-					goto continue_generating;
-				}
-			}
-		}
-		catch(InvalidPositionException &e){}
-		
-		// Check x+
-		try
-		{
-			s16 x = ued;
-			for(s16 y=0; y<ued; y++)
-			for(s16 z=0; z<ued; z++)
-			{
-				v3s16 ap = v3s16(x,y,z) + block->getPosRelative();
-				if(getNode(ap).d == CONTENT_AIR)
-				{
-					orp = v3f(ued-1,y+1,z+1);
-					found_existing = true;
-					goto continue_generating;
-				}
-			}
-		}
-		catch(InvalidPositionException &e){}
-
-		// Check y-
-		try
-		{
-			s16 y = -1;
-			for(s16 x=0; x<ued; x++)
-			for(s16 z=0; z<ued; z++)
-			{
-				v3s16 ap = v3s16(x,y,z) + block->getPosRelative();
-				if(getNode(ap).d == CONTENT_AIR)
-				{
-					orp = v3f(x+1,0,z+1);
-					found_existing = true;
-					goto continue_generating;
-				}
-			}
-		}
-		catch(InvalidPositionException &e){}
-		
-		// Check y+
-		try
-		{
-			s16 y = ued;
-			for(s16 x=0; x<ued; x++)
-			for(s16 z=0; z<ued; z++)
-			{
-				v3s16 ap = v3s16(x,y,z) + block->getPosRelative();
-				if(getNode(ap).d == CONTENT_AIR)
-				{
-					orp = v3f(x+1,ued-1,z+1);
-					found_existing = true;
-					goto continue_generating;
-				}
-			}
-		}
-		catch(InvalidPositionException &e){}
-
-continue_generating:
-		
-		/*
-			Choose whether to actually generate cave
-		*/
-		bool do_generate_caves = true;
-		// Don't generate if no part is underground
-		if(!some_part_underground)
-		{
-			do_generate_caves = false;
-		}
-		// Don't generate if mostly underwater surface
-		/*else if(mostly_underwater_surface)
-		{
-			do_generate_caves = false;
-		}*/
-		// Partly underground = cave
-		else if(!completely_underground)
-		{
-			do_generate_caves = (rand() % 100 <= (s32)(caves_amount*100));
-		}
-		// Found existing cave underground
-		else if(found_existing && completely_underground)
-		{
-			do_generate_caves = (rand() % 100 <= (s32)(caves_amount*100));
-		}
-		// Underground and no caves found
-		else
-		{
-			do_generate_caves = (rand() % 300 <= (s32)(caves_amount*100));
-		}
-
-		if(do_generate_caves)
+		v3s16 p(x0,y0,z0);
+		MapNode n = block->getNode(p);
+		if(n.d == CONTENT_IGNORE)
 		{
-			/*
-				Generate some tunnel starting from orp and ors
-			*/
-			for(u16 i=0; i<3; i++)
-			{
-				v3f rp(
-					(float)(myrand()%ued)+0.5,
-					(float)(myrand()%ued)+0.5,
-					(float)(myrand()%ued)+0.5
-				);
-				s16 min_d = 0;
-				s16 max_d = 4;
-				s16 rs = (myrand()%(max_d-min_d+1))+min_d;
-				
-				v3f vec = rp - orp;
-
-				for(float f=0; f<1.0; f+=0.04)
-				{
-					v3f fp = orp + vec * f;
-					v3s16 cp(fp.X, fp.Y, fp.Z);
-					s16 d0 = -rs/2;
-					s16 d1 = d0 + rs - 1;
-					for(s16 z0=d0; z0<=d1; z0++)
-					{
-						s16 si = rs - abs(z0);
-						for(s16 x0=-si; x0<=si-1; x0++)
-						{
-							s16 si2 = rs - abs(x0);
-							for(s16 y0=-si2+1; y0<=si2-1; y0++)
-							{
-								s16 z = cp.Z + z0;
-								s16 y = cp.Y + y0;
-								s16 x = cp.X + x0;
-								v3s16 p(x,y,z);
-								if(isInArea(p, ued) == false)
-									continue;
-								underground_emptiness[ued*ued*z + ued*y + x] = 1;
-							}
-						}
-					}
-				}
-
-				orp = rp;
-			}
+			dstream<<"CONTENT_IGNORE at "
+					<<"("<<p.X<<","<<p.Y<<","<<p.Z<<")"
+					<<std::endl;
+			erroneus_content = true;
+			assert(0);
 		}
 	}
+	if(erroneus_content)
+	{
+		assert(0);
+	}
 #endif
 
-	// Set to true if has caves.
-	// Set when some non-air is changed to air when making caves.
-	bool has_caves = false;
-
+#if 0
 	/*
-		Apply temporary cave data to block
+		Generate a completely empty block
 	*/
-
 	for(s16 z0=0; z0<MAP_BLOCKSIZE; z0++)
 	for(s16 x0=0; x0<MAP_BLOCKSIZE; x0++)
 	{
 		for(s16 y0=0; y0<MAP_BLOCKSIZE; y0++)
 		{
-			MapNode n = block->getNode(v3s16(x0,y0,z0));
-
-			// Create caves
-			if(underground_emptiness[
-					ued*ued*(z0*ued/MAP_BLOCKSIZE)
-					+ued*(y0*ued/MAP_BLOCKSIZE)
-					+(x0*ued/MAP_BLOCKSIZE)])
-			{
-				if(content_features(n.d).walkable/*is_ground_content(n.d)*/)
-				{
-					// Has now caves
-					has_caves = true;
-					// Set air to node
-					n.d = CONTENT_AIR;
-				}
-			}
-
-			block->setNode(v3s16(x0,y0,z0), n);
-		}
-	}
-	
-	/*
-		This is used for guessing whether or not the block should
-		receive sunlight from the top if the block above doesn't exist
-	*/
-	block->setIsUnderground(completely_underground);
-
-	/*
-		Force lighting update if some part of block is partly
-		underground and has caves.
-	*/
-	/*if(some_part_underground && !completely_underground && has_caves)
-	{
-		//dstream<<"Half-ground caves"<<std::endl;
-		lighting_invalidated_blocks[block->getPos()] = block;
-	}*/
-	
-	// DEBUG: Always update lighting
-	//lighting_invalidated_blocks[block->getPos()] = block;
-
-	/*
-		Add some minerals
-	*/
-
-	if(some_part_underground)
-	{
-		s16 underground_level = (lowest_ground_y/MAP_BLOCKSIZE - block_y)+1;
-
-		/*
-			Add meseblocks
-		*/
-		for(s16 i=0; i<underground_level/4 + 1; i++)
-		{
-			if(myrand()%50 == 0)
-			{
-				v3s16 cp(
-					(myrand()%(MAP_BLOCKSIZE-2))+1,
-					(myrand()%(MAP_BLOCKSIZE-2))+1,
-					(myrand()%(MAP_BLOCKSIZE-2))+1
-				);
-
-				MapNode n;
-				n.d = CONTENT_MESE;
-				
-				for(u16 i=0; i<27; i++)
-				{
-					if(block->getNode(cp+g_27dirs[i]).d == CONTENT_STONE)
-						if(myrand()%8 == 0)
-							block->setNode(cp+g_27dirs[i], n);
-				}
-			}
-		}
-
-		/*
-			Add coal
-		*/
-		u16 coal_amount = 30;
-		u16 coal_rareness = 60 / coal_amount;
-		if(coal_rareness == 0)
-			coal_rareness = 1;
-		if(myrand()%coal_rareness == 0)
-		{
-			u16 a = myrand() % 16;
-			u16 amount = coal_amount * a*a*a / 1000;
-			for(s16 i=0; i<amount; i++)
-			{
-				v3s16 cp(
-					(myrand()%(MAP_BLOCKSIZE-2))+1,
-					(myrand()%(MAP_BLOCKSIZE-2))+1,
-					(myrand()%(MAP_BLOCKSIZE-2))+1
-				);
-
-				MapNode n;
-				n.d = CONTENT_STONE;
-				n.param = MINERAL_COAL;
-
-				for(u16 i=0; i<27; i++)
-				{
-					if(block->getNode(cp+g_27dirs[i]).d == CONTENT_STONE)
-						if(myrand()%8 == 0)
-							block->setNode(cp+g_27dirs[i], n);
-				}
-			}
-		}
-
-		/*
-			Add iron
-		*/
-		//TODO: change to iron_amount or whatever
-		u16 iron_amount = 15;
-		u16 iron_rareness = 60 / iron_amount;
-		if(iron_rareness == 0)
-			iron_rareness = 1;
-		if(myrand()%iron_rareness == 0)
-		{
-			u16 a = myrand() % 16;
-			u16 amount = iron_amount * a*a*a / 1000;
-			for(s16 i=0; i<amount; i++)
-			{
-				v3s16 cp(
-					(myrand()%(MAP_BLOCKSIZE-2))+1,
-					(myrand()%(MAP_BLOCKSIZE-2))+1,
-					(myrand()%(MAP_BLOCKSIZE-2))+1
-				);
-
-				MapNode n;
+			MapNode n;
+			if(y0%2==0)
+				n.d = CONTENT_AIR;
+			else
 				n.d = CONTENT_STONE;
-				n.param = MINERAL_IRON;
-
-				for(u16 i=0; i<27; i++)
-				{
-					if(block->getNode(cp+g_27dirs[i]).d == CONTENT_STONE)
-						if(myrand()%8 == 0)
-							block->setNode(cp+g_27dirs[i], n);
-				}
-			}
-		}
-	}
-	
-	/*
-		Create a few rats in empty blocks underground
-	*/
-	if(completely_underground)
-	{
-		//for(u16 i=0; i<2; i++)
-		{
-			v3s16 cp(
-				(myrand()%(MAP_BLOCKSIZE-2))+1,
-				(myrand()%(MAP_BLOCKSIZE-2))+1,
-				(myrand()%(MAP_BLOCKSIZE-2))+1
-			);
-
-			// Check that the place is empty
-			//if(!is_ground_content(block->getNode(cp).d))
-			if(1)
-			{
-				RatObject *obj = new RatObject(NULL, -1, intToFloat(cp, BS));
-				block->addObject(obj);
-			}
+			block->setNode(v3s16(x0,y0,z0), n);
 		}
 	}
-
-#endif // end of proper block generation
-	
-	/*
-		Add block to sector.
-	*/
-	sector->insertBlock(block);
-	
-	// Lighting is invalid after generation.
-	block->setLightingExpired(true);
-	
-#if 0
-	/*
-		Debug information
-	*/
-	dstream
-	<<"lighting_invalidated_blocks.size()"
-	<<", has_caves"
-	<<", completely_ug"
-	<<", some_part_ug"
-	<<"  "<<lighting_invalidated_blocks.size()
-	<<", "<<has_caves
-	<<", "<<completely_underground
-	<<", "<<some_part_underground
-	<<std::endl;
 #endif
 
 	return block;
@@ -4733,12 +2372,17 @@ MapBlock * ServerMap::createBlock(v3s16 p)
 
 	MapBlock *block = sector->getBlockNoCreateNoEx(block_y);
 	if(block)
+	{
+		if(block->isDummy())
+			block->unDummify();
 		return block;
+	}
 	// Create blank
 	block = sector->createBlankBlock(block_y);
 	return block;
 }
 
+#if 0
 MapBlock * ServerMap::emergeBlock(
 		v3s16 p,
 		bool only_from_disk,
@@ -4750,6 +2394,13 @@ MapBlock * ServerMap::emergeBlock(
 			__FUNCTION_NAME,
 			p.X, p.Y, p.Z, only_from_disk);
 	
+	// This has to be redone or removed
+	assert(0);
+	return NULL;
+}
+#endif
+
+#if 0
 	/*
 		Do not generate over-limit
 	*/
@@ -4769,12 +2420,12 @@ MapBlock * ServerMap::emergeBlock(
 	*/
 	ServerMapSector *sector;
 	try{
-		sector = (ServerMapSector*)emergeSector(p2d, changed_blocks);
-		assert(sector->getId() == MAPSECTOR_SERVER);
+		sector = createSector(p2d);
+		//sector = emergeSector(p2d, changed_blocks);
 	}
 	catch(InvalidPositionException &e)
 	{
-		dstream<<"emergeBlock: emergeSector() failed: "
+		dstream<<"emergeBlock: createSector() failed: "
 				<<e.what()<<std::endl;
 		dstream<<"Path to failed sector: "<<getSectorDir(p2d)
 				<<std::endl
@@ -4783,27 +2434,13 @@ MapBlock * ServerMap::emergeBlock(
 	}
 	catch(VersionMismatchException &e)
 	{
-		dstream<<"emergeBlock: emergeSector() failed: "
+		dstream<<"emergeBlock: createSector() failed: "
 				<<e.what()<<std::endl;
 		dstream<<"Path to failed sector: "<<getSectorDir(p2d)
 				<<std::endl
 				<<"You could try to delete it."<<std::endl;
 		throw e;
 	}
-	/*
-		NOTE: This should not be done, or at least the exception
-		should not be passed on as std::exception, because it
-		won't be catched at all.
-	*/
-	/*catch(std::exception &e)
-	{
-		dstream<<"emergeBlock: emergeSector() failed: "
-				<<e.what()<<std::endl;
-		dstream<<"Path to failed sector: "<<getSectorDir(p2d)
-				<<std::endl
-				<<"You could try to delete it."<<std::endl;
-		throw e;
-	}*/
 
 	/*
 		Try to get a block from the sector
@@ -4812,7 +2449,14 @@ MapBlock * ServerMap::emergeBlock(
 	bool does_not_exist = false;
 	bool lighting_expired = false;
 	MapBlock *block = sector->getBlockNoCreateNoEx(block_y);
-
+	
+	// If not found, try loading from disk
+	if(block == NULL)
+	{
+		block = loadBlock(p);
+	}
+	
+	// Handle result
 	if(block == NULL)
 	{
 		does_not_exist = true;
@@ -4872,16 +2516,16 @@ MapBlock * ServerMap::emergeBlock(
 		lighting_invalidated_blocks.insert(p, block);
 	}
 
+#if 0
 	/*
 		Initially update sunlight
 	*/
-	
 	{
 		core::map<v3s16, bool> light_sources;
 		bool black_air_left = false;
 		bool bottom_invalid =
 				block->propagateSunlight(light_sources, true,
-				&black_air_left, true);
+				&black_air_left);
 
 		// If sunlight didn't reach everywhere and part of block is
 		// above ground, lighting has to be properly updated
@@ -4896,12 +2540,15 @@ MapBlock * ServerMap::emergeBlock(
 			lighting_invalidated_blocks[block->getPos()] = block;
 		}
 	}
+#endif
 	
 	return block;
 }
+#endif
 
 s16 ServerMap::findGroundLevel(v2s16 p2d)
 {
+#if 0
 	/*
 		Uh, just do something random...
 	*/
@@ -4927,16 +2574,20 @@ s16 ServerMap::findGroundLevel(v2s16 p2d)
 		if(content_walkable(n.d) && n.d != CONTENT_IGNORE)
 			return p.Y;
 	}
+
 	// Move to plan b
 plan_b:
+#endif
+
 	/*
-		Plan B: Get from map generator perlin noise function
+		Determine from map generator noise functions
 	*/
-	// This won't work if proper generation is disabled
-	if(m_chunksize == 0)
-		return WATER_LEVEL+2;
-	double level = base_rock_level_2d(m_seed, p2d) + AVERAGE_MUD_AMOUNT;
-	return (s16)level;
+	
+	s16 level = mapgen::find_ground_level_from_noise(m_seed, p2d, 1);
+	return level;
+
+	//double level = base_rock_level_2d(m_seed, p2d) + AVERAGE_MUD_AMOUNT;
+	//return (s16)level;
 }
 
 void ServerMap::createDirs(std::string path)
@@ -5013,6 +2664,13 @@ v3s16 ServerMap::getBlockPos(std::string sectordir, std::string blockfile)
 	return v3s16(p2d.X, y, p2d.Y);
 }
 
+std::string ServerMap::getBlockFilename(v3s16 p)
+{
+	char cc[5];
+	snprintf(cc, 5, "%.4x", (unsigned int)p.Y&0xffff);
+	return cc;
+}
+
 void ServerMap::save(bool only_changed)
 {
 	DSTACK(__FUNCTION_NAME);
@@ -5031,18 +2689,9 @@ void ServerMap::save(bool only_changed)
 		saveMapMeta();
 	}
 
-	// Disable saving chunk metadata if chunks are disabled
-	if(m_chunksize != 0)
-	{
-		if(only_changed == false || anyChunkModified())
-			saveChunkMeta();
-	}
-	
 	u32 sector_meta_count = 0;
 	u32 block_count = 0;
-	
-	{ //sectorlock
-	//JMutexAutoLock lock(m_sector_mutex); // Bulk comment-out
+	u32 block_count_all = 0; // Number of blocks in memory
 	
 	core::map<v2s16, MapSector*>::Iterator i = m_sectors.getIterator();
 	for(; i.atEnd() == false; i++)
@@ -5061,7 +2710,11 @@ void ServerMap::save(bool only_changed)
 		for(j=blocks.begin(); j!=blocks.end(); j++)
 		{
 			MapBlock *block = *j;
-			if(block->getChangedFlag() || only_changed == false)
+			
+			block_count_all++;
+
+			if(block->getModified() >= MOD_STATE_WRITE_NEEDED 
+					|| only_changed == false)
 			{
 				saveBlock(block);
 				block_count++;
@@ -5075,8 +2728,6 @@ void ServerMap::save(bool only_changed)
 		}
 	}
 
-	}//sectorlock
-	
 	/*
 		Only print if something happened or saved whole map
 	*/
@@ -5086,111 +2737,17 @@ void ServerMap::save(bool only_changed)
 		dstream<<DTIME<<"ServerMap: Written: "
 				<<sector_meta_count<<" sector metadata files, "
 				<<block_count<<" block files"
+				<<", "<<block_count_all<<" blocks in memory."
 				<<std::endl;
 	}
 }
 
-#if 0
-// NOTE: Doing this is insane. Deprecated and probably broken.
-void ServerMap::loadAll()
-{
-	DSTACK(__FUNCTION_NAME);
-	dstream<<DTIME<<"ServerMap: Loading map..."<<std::endl;
-	
-	loadMapMeta();
-	loadChunkMeta();
-
-	std::vector<fs::DirListNode> list = fs::GetDirListing(m_savedir+"/sectors/");
-
-	dstream<<DTIME<<"There are "<<list.size()<<" sectors."<<std::endl;
-	
-	//JMutexAutoLock lock(m_sector_mutex); // Bulk comment-out
-	
-	s32 counter = 0;
-	s32 printed_counter = -100000;
-	s32 count = list.size();
-
-	std::vector<fs::DirListNode>::iterator i;
-	for(i=list.begin(); i!=list.end(); i++)
-	{
-		if(counter > printed_counter + 10)
-		{
-			dstream<<DTIME<<counter<<"/"<<count<<std::endl;
-			printed_counter = counter;
-		}
-		counter++;
-
-		MapSector *sector = NULL;
-
-		// We want directories
-		if(i->dir == false)
-			continue;
-		try{
-			sector = loadSectorMeta(i->name);
-		}
-		catch(InvalidFilenameException &e)
-		{
-			// This catches unknown crap in directory
-		}
-		
-		std::vector<fs::DirListNode> list2 = fs::GetDirListing
-				(m_savedir+"/sectors/"+i->name);
-		std::vector<fs::DirListNode>::iterator i2;
-		for(i2=list2.begin(); i2!=list2.end(); i2++)
-		{
-			// We want files
-			if(i2->dir)
-				continue;
-			try{
-				loadBlock(i->name, i2->name, sector);
-			}
-			catch(InvalidFilenameException &e)
-			{
-				// This catches unknown crap in directory
-			}
-		}
-	}
-	dstream<<DTIME<<"ServerMap: Map loaded."<<std::endl;
-}
-#endif
-
-#if 0
-void ServerMap::saveMasterHeightmap()
-{
-	DSTACK(__FUNCTION_NAME);
-	
-	dstream<<"DEPRECATED: "<<__FUNCTION_NAME<<std::endl;
-
-	createDir(m_savedir);
-	
-	/*std::string fullpath = m_savedir + "/master_heightmap";
-	std::ofstream o(fullpath.c_str(), std::ios_base::binary);
-	if(o.good() == false)
-		throw FileNotGoodException("Cannot open master heightmap");*/
-	
-	// Format used for writing
-	//u8 version = SER_FMT_VER_HIGHEST;
-}
-
-void ServerMap::loadMasterHeightmap()
-{
-	DSTACK(__FUNCTION_NAME);
-	
-	dstream<<"DEPRECATED: "<<__FUNCTION_NAME<<std::endl;
-
-	/*std::string fullpath = m_savedir + "/master_heightmap";
-	std::ifstream is(fullpath.c_str(), std::ios_base::binary);
-	if(is.good() == false)
-		throw FileNotGoodException("Cannot open master heightmap");*/
-}
-#endif
-
 void ServerMap::saveMapMeta()
 {
 	DSTACK(__FUNCTION_NAME);
 	
 	dstream<<"INFO: ServerMap::saveMapMeta(): "
-			<<"seed="<<m_seed<<", chunksize="<<m_chunksize
+			<<"seed="<<m_seed
 			<<std::endl;
 
 	createDirs(m_savedir);
@@ -5206,7 +2763,6 @@ void ServerMap::saveMapMeta()
 	
 	Settings params;
 	params.setU64("seed", m_seed);
-	params.setS32("chunksize", m_chunksize);
 
 	params.writeLines(os);
 
@@ -5247,106 +2803,12 @@ void ServerMap::loadMapMeta()
 	}
 
 	m_seed = params.getU64("seed");
-	m_chunksize = params.getS32("chunksize");
 
 	dstream<<"INFO: ServerMap::loadMapMeta(): "
-			<<"seed="<<m_seed<<", chunksize="<<m_chunksize
+			<<"seed="<<m_seed
 			<<std::endl;
 }
 
-void ServerMap::saveChunkMeta()
-{
-	DSTACK(__FUNCTION_NAME);
-
-	// This should not be called if chunks are disabled.
-	assert(m_chunksize != 0);
-	
-	u32 count = m_chunks.size();
-
-	dstream<<"INFO: ServerMap::saveChunkMeta(): Saving metadata of "
-			<<count<<" chunks"<<std::endl;
-
-	createDirs(m_savedir);
-	
-	std::string fullpath = m_savedir + "/chunk_meta";
-	std::ofstream os(fullpath.c_str(), std::ios_base::binary);
-	if(os.good() == false)
-	{
-		dstream<<"ERROR: ServerMap::saveChunkMeta(): "
-				<<"could not open"<<fullpath<<std::endl;
-		throw FileNotGoodException("Cannot open chunk metadata");
-	}
-	
-	u8 version = 0;
-	
-	// Write version
-	os.write((char*)&version, 1);
-
-	u8 buf[4];
-	
-	// Write count
-	writeU32(buf, count);
-	os.write((char*)buf, 4);
-	
-	for(core::map<v2s16, MapChunk*>::Iterator
-			i = m_chunks.getIterator();
-			i.atEnd()==false; i++)
-	{
-		v2s16 p = i.getNode()->getKey();
-		MapChunk *chunk = i.getNode()->getValue();
-		// Write position
-		writeV2S16(buf, p);
-		os.write((char*)buf, 4);
-		// Write chunk data
-		chunk->serialize(os, version);
-	}
-
-	setChunksNonModified();
-}
-
-void ServerMap::loadChunkMeta()
-{
-	DSTACK(__FUNCTION_NAME);
-	
-	dstream<<"INFO: ServerMap::loadChunkMeta(): Loading chunk metadata"
-			<<std::endl;
-
-	std::string fullpath = m_savedir + "/chunk_meta";
-	std::ifstream is(fullpath.c_str(), std::ios_base::binary);
-	if(is.good() == false)
-	{
-		dstream<<"ERROR: ServerMap::loadChunkMeta(): "
-				<<"could not open"<<fullpath<<std::endl;
-		throw FileNotGoodException("Cannot open chunk metadata");
-	}
-
-	u8 version = 0;
-	
-	// Read version
-	is.read((char*)&version, 1);
-
-	u8 buf[4];
-	
-	// Read count
-	is.read((char*)buf, 4);
-	u32 count = readU32(buf);
-
-	dstream<<"INFO: ServerMap::loadChunkMeta(): Loading metadata of "
-			<<count<<" chunks"<<std::endl;
-	
-	for(u32 i=0; i<count; i++)
-	{
-		v2s16 p;
-		MapChunk *chunk = new MapChunk();
-		// Read position
-		is.read((char*)buf, 4);
-		p = readV2S16(buf);
-		// Read chunk data
-		chunk->deSerialize(is, version);
-		m_chunks.insert(p, chunk);
-	}
-}
-
 void ServerMap::saveSectorMeta(ServerMapSector *sector)
 {
 	DSTACK(__FUNCTION_NAME);
@@ -5408,7 +2870,7 @@ MapSector* ServerMap::loadSectorMeta(std::string sectordir, bool save_after_load
 	return sector;
 }
 
-bool ServerMap::loadSectorFull(v2s16 p2d)
+bool ServerMap::loadSectorMeta(v2s16 p2d)
 {
 	DSTACK(__FUNCTION_NAME);
 
@@ -5432,7 +2894,49 @@ bool ServerMap::loadSectorFull(v2s16 p2d)
 		sectordir = getSectorDir(p2d, 2);
 	}
 
-	//JMutexAutoLock lock(m_sector_mutex); // Bulk comment-out
+	try{
+		sector = loadSectorMeta(sectordir, loadlayout != 2);
+	}
+	catch(InvalidFilenameException &e)
+	{
+		return false;
+	}
+	catch(FileNotGoodException &e)
+	{
+		return false;
+	}
+	catch(std::exception &e)
+	{
+		return false;
+	}
+	
+	return true;
+}
+
+#if 0
+bool ServerMap::loadSectorFull(v2s16 p2d)
+{
+	DSTACK(__FUNCTION_NAME);
+
+	MapSector *sector = NULL;
+
+	// The directory layout we're going to load from.
+	//  1 - original sectors/xxxxzzzz/
+	//  2 - new sectors2/xxx/zzz/
+	//  If we load from anything but the latest structure, we will
+	//  immediately save to the new one, and remove the old.
+	int loadlayout = 1;
+	std::string sectordir1 = getSectorDir(p2d, 1);
+	std::string sectordir;
+	if(fs::PathExists(sectordir1))
+	{
+		sectordir = sectordir1;
+	}
+	else
+	{
+		loadlayout = 2;
+		sectordir = getSectorDir(p2d, 2);
+	}
 
 	try{
 		sector = loadSectorMeta(sectordir, loadlayout != 2);
@@ -5479,7 +2983,7 @@ bool ServerMap::loadSectorFull(v2s16 p2d)
 
 	return true;
 }
-
+#endif
 
 void ServerMap::saveBlock(MapBlock *block)
 {
@@ -5499,13 +3003,13 @@ void ServerMap::saveBlock(MapBlock *block)
 	u8 version = SER_FMT_VER_HIGHEST;
 	// Get destination
 	v3s16 p3d = block->getPos();
-	v2s16 p2d(p3d.X, p3d.Z);
-	std::string dir = getSectorDir(p2d);
-	createDirs(dir);
 	
-	char cc[5];
-	snprintf(cc, 5, "%.4x", (unsigned int)p3d.Y&0xffff);
-	std::string fullpath = dir + "/" + cc;
+	v2s16 p2d(p3d.X, p3d.Z);
+	std::string sectordir = getSectorDir(p2d);
+
+	createDirs(sectordir);
+
+	std::string fullpath = sectordir+"/"+getBlockFilename(p3d);
 	std::ofstream o(fullpath.c_str(), std::ios_base::binary);
 	if(o.good() == false)
 		throw FileNotGoodException("Cannot open block data");
@@ -5523,7 +3027,7 @@ void ServerMap::saveBlock(MapBlock *block)
 	block->serializeDiskExtra(o, version);
 
 	// We just wrote it to the disk so clear modified flag
-	block->resetChangedFlag();
+	block->resetModified();
 }
 
 void ServerMap::loadBlock(std::string sectordir, std::string blockfile, MapSector *sector, bool save_after_load)
@@ -5587,20 +3091,85 @@ void ServerMap::loadBlock(std::string sectordir, std::string blockfile, MapSecto
 		}
 		
 		// We just loaded it from the disk, so it's up-to-date.
-		block->resetChangedFlag();
+		block->resetModified();
 
 	}
 	catch(SerializationError &e)
 	{
 		dstream<<"WARNING: Invalid block data on disk "
-				"(SerializationError). Ignoring. "
-				"A new one will be generated."
+				<<"fullpath="<<fullpath
+				<<" (SerializationError). "
+				<<"what()="<<e.what()
 				<<std::endl;
+				//" Ignoring. A new one will be generated.
+		assert(0);
 
 		// TODO: Backup file; name is in fullpath.
 	}
 }
 
+MapBlock* ServerMap::loadBlock(v3s16 blockpos)
+{
+	DSTACK(__FUNCTION_NAME);
+
+	v2s16 p2d(blockpos.X, blockpos.Z);
+
+	// The directory layout we're going to load from.
+	//  1 - original sectors/xxxxzzzz/
+	//  2 - new sectors2/xxx/zzz/
+	//  If we load from anything but the latest structure, we will
+	//  immediately save to the new one, and remove the old.
+	int loadlayout = 1;
+	std::string sectordir1 = getSectorDir(p2d, 1);
+	std::string sectordir;
+	if(fs::PathExists(sectordir1))
+	{
+		sectordir = sectordir1;
+	}
+	else
+	{
+		loadlayout = 2;
+		sectordir = getSectorDir(p2d, 2);
+	}
+	
+	/*
+		Make sure sector is loaded
+	*/
+	MapSector *sector = getSectorNoGenerateNoEx(p2d);
+	if(sector == NULL)
+	{
+		try{
+			sector = loadSectorMeta(sectordir, loadlayout != 2);
+		}
+		catch(InvalidFilenameException &e)
+		{
+			return false;
+		}
+		catch(FileNotGoodException &e)
+		{
+			return false;
+		}
+		catch(std::exception &e)
+		{
+			return false;
+		}
+	}
+	
+	/*
+		Make sure file exists
+	*/
+
+	std::string blockfilename = getBlockFilename(blockpos);
+	if(fs::PathExists(sectordir+"/"+blockfilename) == false)
+		return NULL;
+
+	/*
+		Load block
+	*/
+	loadBlock(sectordir, blockfilename, sector, loadlayout != 2);
+	return getBlockNoCreateNoEx(blockpos);
+}
+
 void ServerMap::PrintInfo(std::ostream &out)
 {
 	out<<"ServerMap: ";
@@ -5709,6 +3278,14 @@ void ClientMap::renderMap(video::IVideoDriver* driver, s32 pass)
 	DSTACK(__FUNCTION_NAME);
 
 	bool is_transparent_pass = pass == scene::ESNRP_TRANSPARENT;
+	
+	/*
+		This is called two times per frame, reset on the non-transparent one
+	*/
+	if(pass == scene::ESNRP_SOLID)
+	{
+		m_last_drawn_sectors.clear();
+	}
 
 	/*
 		Get time for measuring timeout.
@@ -5745,9 +3322,9 @@ void ClientMap::renderMap(video::IVideoDriver* driver, s32 pass)
 			p_nodes_min.Y / MAP_BLOCKSIZE - 1,
 			p_nodes_min.Z / MAP_BLOCKSIZE - 1);
 	v3s16 p_blocks_max(
-			p_nodes_max.X / MAP_BLOCKSIZE + 1,
-			p_nodes_max.Y / MAP_BLOCKSIZE + 1,
-			p_nodes_max.Z / MAP_BLOCKSIZE + 1);
+			p_nodes_max.X / MAP_BLOCKSIZE,
+			p_nodes_max.Y / MAP_BLOCKSIZE,
+			p_nodes_max.Z / MAP_BLOCKSIZE);
 	
 	u32 vertex_count = 0;
 	
@@ -5757,9 +3334,6 @@ void ClientMap::renderMap(video::IVideoDriver* driver, s32 pass)
 	u32 blocks_would_have_drawn = 0;
 	u32 blocks_drawn = 0;
 
-	//NOTE: The sectors map should be locked but we're not doing it
-	// because it'd cause too much delays
-
 	int timecheck_counter = 0;
 	core::map<v2s16, MapSector*>::Iterator si;
 	si = m_sectors.getIterator();
@@ -5799,6 +3373,8 @@ void ClientMap::renderMap(video::IVideoDriver* driver, s32 pass)
 		/*
 			Draw blocks
 		*/
+		
+		u32 sector_blocks_drawn = 0;
 
 		core::list< MapBlock * >::Iterator i;
 		for(i=sectorblocks.begin(); i!=sectorblocks.end(); i++)
@@ -5891,7 +3467,9 @@ void ClientMap::renderMap(video::IVideoDriver* driver, s32 pass)
 						&& m_control.range_all == false
 						&& d > m_control.wanted_min_range * BS)
 					continue;
+
 				blocks_drawn++;
+				sector_blocks_drawn++;
 
 				u32 c = mesh->getMeshBufferCount();
 
@@ -5917,6 +3495,11 @@ void ClientMap::renderMap(video::IVideoDriver* driver, s32 pass)
 				}
 			}
 		} // foreach sectorblocks
+
+		if(sector_blocks_drawn != 0)
+		{
+			m_last_drawn_sectors[sp] = true;
+		}
 	}
 	
 	m_control.blocks_drawn = blocks_drawn;
diff --git a/src/map.h b/src/map.h
index 09154547c..86b6b6e18 100644
--- a/src/map.h
+++ b/src/map.h
@@ -41,13 +41,27 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "mapchunk.h"
 #include "nodemetadata.h"
 
+namespace mapgen{
+	struct BlockMakeData;
+};
+
+/*
+	MapEditEvent
+*/
+
 #define MAPTYPE_BASE 0
 #define MAPTYPE_SERVER 1
 #define MAPTYPE_CLIENT 2
 
 enum MapEditEventType{
+	// Node added (changed from air or something else to something)
 	MEET_ADDNODE,
+	// Node removed (changed to air)
 	MEET_REMOVENODE,
+	// Node metadata of block changed (not knowing which node exactly)
+	// p stores block coordinate
+	MEET_BLOCK_NODE_METADATA_CHANGED,
+	// Anything else
 	MEET_OTHER
 };
 
@@ -122,7 +136,7 @@ public:
 
 	// On failure returns NULL
 	MapSector * getSectorNoGenerateNoExNoLock(v2s16 p2d);
-	// On failure returns NULL
+	// Same as the above (there exists no lock anymore)
 	MapSector * getSectorNoGenerateNoEx(v2s16 p2d);
 	// On failure throws InvalidPositionException
 	MapSector * getSectorNoGenerate(v2s16 p2d);
@@ -258,6 +272,9 @@ public:
 	//bool updateChangedVisibleArea();
 	
 	virtual void save(bool only_changed){assert(0);};
+	
+	// Server implements this
+	virtual void saveBlock(MapBlock *block){};
 
 	/*
 		Updates usage timers
@@ -269,7 +286,7 @@ public:
 	void deleteSectors(core::list<v2s16> &list, bool only_blocks);
 	
 	// Returns count of deleted sectors
-	u32 deleteUnusedSectors(float timeout, bool only_blocks=false,
+	u32 unloadUnusedData(float timeout, bool only_blocks=false,
 			core::list<v3s16> *deleted_blocks=NULL);
 
 	// For debug printing
@@ -320,8 +337,6 @@ protected:
 	This is the only map class that is able to generate map.
 */
 
-struct ChunkMakeData;
-
 class ServerMap : public Map
 {
 public:
@@ -337,159 +352,24 @@ public:
 	}
 
 	/*
-		Map generation
-	*/
-	
-	// Returns the position of the chunk where the sector is in
-	v2s16 sector_to_chunk(v2s16 sectorpos)
-	{
-		if(m_chunksize == 0)
-			return v2s16(0,0);
-		sectorpos.X += m_chunksize / 2;
-		sectorpos.Y += m_chunksize / 2;
-		v2s16 chunkpos = getContainerPos(sectorpos, m_chunksize);
-		return chunkpos;
-	}
-	
-	// Returns the position of the (0,0) sector of the chunk
-	v2s16 chunk_to_sector(v2s16 chunkpos)
-	{
-		if(m_chunksize == 0)
-			return v2s16(0,0);
-		v2s16 sectorpos(
-			chunkpos.X * m_chunksize,
-			chunkpos.Y * m_chunksize
-		);
-		sectorpos.X -= m_chunksize / 2;
-		sectorpos.Y -= m_chunksize / 2;
-		return sectorpos;
-	}
-
-	/*
-		Get a chunk.
-	*/
-	MapChunk *getChunk(v2s16 chunkpos)
-	{
-		core::map<v2s16, MapChunk*>::Node *n;
-		n = m_chunks.find(chunkpos);
-		if(n == NULL)
-			return NULL;
-		return n->getValue();
-	}
-
-	/*
-		True if the chunk and its neighbors are fully generated.
-		It means the chunk will not be touched in the future by the
-		generator. If false, generateChunk will make it true.
-	*/
-	bool chunkNonVolatile(v2s16 chunkpos)
-	{
-		if(m_chunksize == 0)
-			return true;
-		
-		/*for(s16 x=-1; x<=1; x++)
-		for(s16 y=-1; y<=1; y++)*/
-		s16 x=0;
-		s16 y=0;
-		{
-			v2s16 chunkpos0 = chunkpos + v2s16(x,y);
-			MapChunk *chunk = getChunk(chunkpos);
-			if(chunk == NULL)
-				return false;
-			if(chunk->getGenLevel() != GENERATED_FULLY)
-				return false;
-		}
-		return true;
-	}
-	
-	/*
-		Returns true if any chunk is marked as modified
-	*/
-	bool anyChunkModified()
-	{
-		for(core::map<v2s16, MapChunk*>::Iterator
-				i = m_chunks.getIterator();
-				i.atEnd()==false; i++)
-		{
-			v2s16 p = i.getNode()->getKey();
-			MapChunk *chunk = i.getNode()->getValue();
-			if(chunk->isModified())
-				return true;
-		}
-		return false;
-	}
-
-	void setChunksNonModified()
-	{
-		for(core::map<v2s16, MapChunk*>::Iterator
-				i = m_chunks.getIterator();
-				i.atEnd()==false; i++)
-		{
-			v2s16 p = i.getNode()->getKey();
-			MapChunk *chunk = i.getNode()->getValue();
-			chunk->setModified(false);
-		}
-	}
-
-	/*
-		Chunks are generated by using these and makeChunk().
-	*/
-	void initChunkMake(ChunkMakeData &data, v2s16 chunkpos);
-	MapChunk* finishChunkMake(ChunkMakeData &data,
-			core::map<v3s16, MapBlock*> &changed_blocks);
-
-	/*
-		Generate a chunk.
-
-		All chunks touching this one can be altered also.
-	*/
-	/*MapChunk* generateChunkRaw(v2s16 chunkpos,
-			core::map<v3s16, MapBlock*> &changed_blocks,
-			bool force=false);*/
-	
-	/*
-		Generate a chunk and its neighbors so that it won't be touched
-		anymore.
-	*/
-	/*MapChunk* generateChunk(v2s16 chunkpos,
-			core::map<v3s16, MapBlock*> &changed_blocks);*/
-	
-	/*
-		Generate a sector.
-		
-		This is mainly called by generateChunkRaw.
-	*/
-	//ServerMapSector * generateSector(v2s16 p);
-	
-	/*
 		Get a sector from somewhere.
 		- Check memory
-		- Check disk (loads blocks also)
+		- Check disk (doesn't load blocks)
 		- Create blank one
 	*/
 	ServerMapSector * createSector(v2s16 p);
 
 	/*
-		Get a sector from somewhere.
-		- Check memory
-		- Check disk (loads blocks also)
-		- Generate chunk
+		Blocks are generated by using these and makeBlock().
 	*/
-	/*MapSector * emergeSector(v2s16 p,
-			core::map<v3s16, MapBlock*> &changed_blocks);*/
+	void initBlockMake(mapgen::BlockMakeData *data, v3s16 blockpos);
+	MapBlock* finishBlockMake(mapgen::BlockMakeData *data,
+			core::map<v3s16, MapBlock*> &changed_blocks);
 	
-	/*MapSector * emergeSector(v2s16 p)
-	{
-		core::map<v3s16, MapBlock*> changed_blocks;
-		return emergeSector(p, changed_blocks);
-	}*/
-
+	// A non-threaded wrapper to the above
 	MapBlock * generateBlock(
 			v3s16 p,
-			MapBlock *original_dummy,
-			ServerMapSector *sector,
-			core::map<v3s16, MapBlock*> &changed_blocks,
-			core::map<v3s16, MapBlock*> &lighting_invalidated_blocks
+			core::map<v3s16, MapBlock*> &modified_blocks
 	);
 	
 	/*
@@ -498,37 +378,17 @@ public:
 		- Create blank
 	*/
 	MapBlock * createBlock(v3s16 p);
-	
-	/*
-		only_from_disk, changed_blocks and lighting_invalidated_blocks
-		are not properly used by the new map generator.
-	*/
-	MapBlock * emergeBlock(
-			v3s16 p,
-			bool only_from_disk,
-			core::map<v3s16, MapBlock*> &changed_blocks,
-			core::map<v3s16, MapBlock*> &lighting_invalidated_blocks
-	);
 
 #if 0
 	/*
+		NOTE: This comment might be outdated
+		
 		Forcefully get a block from somewhere.
 
-		Exceptions:
-		- InvalidPositionException: possible if only_from_disk==true
+		InvalidPositionException possible if only_from_disk==true
 		
-		changed_blocks:
-		- All already existing blocks that were modified are added.
-			- If found on disk, nothing will be added.
-			- If generated, the new block will not be included.
-
-		lighting_invalidated_blocks:
-		- All blocks that have heavy-to-calculate lighting changes
-		  are added.
-			- updateLighting() should be called for these.
-		
-		- A block that is in changed_blocks may not be in
-		  lighting_invalidated_blocks.
+		Parameters:
+		changed_blocks: Blocks that have been modified
 	*/
 	MapBlock * emergeBlock(
 			v3s16 p,
@@ -551,6 +411,7 @@ public:
 	// dirname: final directory name
 	v2s16 getSectorPos(std::string dirname);
 	v3s16 getBlockPos(std::string sectordir, std::string blockfile);
+	static std::string getBlockFilename(v3s16 p);
 
 	void save(bool only_changed);
 	//void loadAll();
@@ -559,8 +420,8 @@ public:
 	void saveMapMeta();
 	void loadMapMeta();
 	
-	void saveChunkMeta();
-	void loadChunkMeta();
+	/*void saveChunkMeta();
+	void loadChunkMeta();*/
 	
 	// The sector mutex should be locked when calling most of these
 	
@@ -569,6 +430,7 @@ public:
 	// DEPRECATED? Sectors have no metadata anymore.
 	void saveSectorMeta(ServerMapSector *sector);
 	MapSector* loadSectorMeta(std::string dirname, bool save_after_load);
+	bool loadSectorMeta(v2s16 p2d);
 	
 	// Full load of a sector including all blocks.
 	// returns true on success, false on failure.
@@ -580,12 +442,15 @@ public:
 	void saveBlock(MapBlock *block);
 	// This will generate a sector with getSector if not found.
 	void loadBlock(std::string sectordir, std::string blockfile, MapSector *sector, bool save_after_load=false);
+	MapBlock* loadBlock(v3s16 p);
 
 	// For debug printing
 	virtual void PrintInfo(std::ostream &out);
 
 	bool isSavingEnabled(){ return m_map_saving_enabled; }
 
+	u64 getSeed(){ return m_seed; }
+
 private:
 	// Seed used for all kinds of randomness
 	u64 m_seed;
@@ -593,11 +458,13 @@ private:
 	std::string m_savedir;
 	bool m_map_saving_enabled;
 
+#if 0
 	// Chunk size in MapSectors
 	// If 0, chunks are disabled.
 	s16 m_chunksize;
 	// Chunks
 	core::map<v2s16, MapChunk*> m_chunks;
+#endif
 
 	/*
 		Metadata is re-written on disk only if this is true.
@@ -732,6 +599,12 @@ public:
 	// For debug printing
 	virtual void PrintInfo(std::ostream &out);
 	
+	// Check if sector was drawn on last render()
+	bool sectorWasDrawn(v2s16 p)
+	{
+		return (m_last_drawn_sectors.find(p) != NULL);
+	}
+	
 private:
 	Client *m_client;
 	
@@ -746,7 +619,8 @@ private:
 	v3f m_camera_position;
 	v3f m_camera_direction;
 	JMutex m_camera_mutex;
-
+	
+	core::map<v2s16, bool> m_last_drawn_sectors;
 };
 
 #endif
@@ -796,29 +670,5 @@ protected:
 	bool m_create_area;
 };
 
-struct ChunkMakeData
-{
-	bool no_op;
-	ManualMapVoxelManipulator vmanip;
-	u64 seed;
-	v2s16 chunkpos;
-	s16 y_blocks_min;
-	s16 y_blocks_max;
-	v2s16 sectorpos_base;
-	s16 sectorpos_base_size;
-	v2s16 sectorpos_bigbase;
-	s16 sectorpos_bigbase_size;
-	s16 max_spread_amount;
-	UniqueQueue<v3s16> transforming_liquid;
-
-	ChunkMakeData():
-		no_op(false),
-		vmanip(NULL),
-		seed(0)
-	{}
-};
-
-void makeChunk(ChunkMakeData *data);
-
 #endif
 
diff --git a/src/mapblock.cpp b/src/mapblock.cpp
index 71044652d..2f6a4b850 100644
--- a/src/mapblock.cpp
+++ b/src/mapblock.cpp
@@ -24,1813 +24,6 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "light.h"
 #include <sstream>
 
-#ifndef SERVER
-void MeshMakeData::fill(u32 daynight_ratio, MapBlock *block)
-{
-	m_daynight_ratio = daynight_ratio;
-	m_blockpos = block->getPos();
-
-	v3s16 blockpos_nodes = m_blockpos*MAP_BLOCKSIZE;
-	
-	/*
-		There is no harm not copying the TempMods of the neighbors
-		because they are already copied to this block
-	*/
-	m_temp_mods.clear();
-	block->copyTempMods(m_temp_mods);
-	
-	/*
-		Copy data
-	*/
-
-	// Allocate this block + neighbors
-	m_vmanip.clear();
-	m_vmanip.addArea(VoxelArea(blockpos_nodes-v3s16(1,1,1)*MAP_BLOCKSIZE,
-			blockpos_nodes+v3s16(1,1,1)*MAP_BLOCKSIZE*2-v3s16(1,1,1)));
-
-	{
-		//TimeTaker timer("copy central block data");
-		// 0ms
-
-		// Copy our data
-		block->copyTo(m_vmanip);
-	}
-	{
-		//TimeTaker timer("copy neighbor block data");
-		// 0ms
-
-		/*
-			Copy neighbors. This is lightning fast.
-			Copying only the borders would be *very* slow.
-		*/
-		
-		// Get map
-		NodeContainer *parentcontainer = block->getParent();
-		// This will only work if the parent is the map
-		assert(parentcontainer->nodeContainerId() == NODECONTAINER_ID_MAP);
-		// OK, we have the map!
-		Map *map = (Map*)parentcontainer;
-
-		for(u16 i=0; i<6; i++)
-		{
-			const v3s16 &dir = g_6dirs[i];
-			v3s16 bp = m_blockpos + dir;
-			MapBlock *b = map->getBlockNoCreateNoEx(bp);
-			if(b)
-				b->copyTo(m_vmanip);
-		}
-	}
-}
-#endif
-
-/*
-	Parameters must consist of air and !air.
-	Order doesn't matter.
-
-	If either of the nodes doesn't exist, light is 0.
-	
-	parameters:
-		daynight_ratio: 0...1000
-		n: getNodeParent(p)
-		n2: getNodeParent(p + face_dir)
-		face_dir: axis oriented unit vector from p to p2
-	
-	returns encoded light value.
-*/
-u8 getFaceLight(u32 daynight_ratio, MapNode n, MapNode n2,
-		v3s16 face_dir)
-{
-	try{
-		u8 light;
-		u8 l1 = n.getLightBlend(daynight_ratio);
-		u8 l2 = n2.getLightBlend(daynight_ratio);
-		if(l1 > l2)
-			light = l1;
-		else
-			light = l2;
-
-		// Make some nice difference to different sides
-
-		// This makes light come from a corner
-		/*if(face_dir.X == 1 || face_dir.Z == 1 || face_dir.Y == -1)
-			light = diminish_light(diminish_light(light));
-		else if(face_dir.X == -1 || face_dir.Z == -1)
-			light = diminish_light(light);*/
-		
-		// All neighboring faces have different shade (like in minecraft)
-		if(face_dir.X == 1 || face_dir.X == -1 || face_dir.Y == -1)
-			light = diminish_light(diminish_light(light));
-		else if(face_dir.Z == 1 || face_dir.Z == -1)
-			light = diminish_light(light);
-
-		return light;
-	}
-	catch(InvalidPositionException &e)
-	{
-		return 0;
-	}
-}
-
-#ifndef SERVER
-
-/*
-	vertex_dirs: v3s16[4]
-*/
-void getNodeVertexDirs(v3s16 dir, v3s16 *vertex_dirs)
-{
-	/*
-		If looked from outside the node towards the face, the corners are:
-		0: bottom-right
-		1: bottom-left
-		2: top-left
-		3: top-right
-	*/
-	if(dir == v3s16(0,0,1))
-	{
-		// If looking towards z+, this is the face that is behind
-		// the center point, facing towards z+.
-		vertex_dirs[0] = v3s16(-1,-1, 1);
-		vertex_dirs[1] = v3s16( 1,-1, 1);
-		vertex_dirs[2] = v3s16( 1, 1, 1);
-		vertex_dirs[3] = v3s16(-1, 1, 1);
-	}
-	else if(dir == v3s16(0,0,-1))
-	{
-		// faces towards Z-
-		vertex_dirs[0] = v3s16( 1,-1,-1);
-		vertex_dirs[1] = v3s16(-1,-1,-1);
-		vertex_dirs[2] = v3s16(-1, 1,-1);
-		vertex_dirs[3] = v3s16( 1, 1,-1);
-	}
-	else if(dir == v3s16(1,0,0))
-	{
-		// faces towards X+
-		vertex_dirs[0] = v3s16( 1,-1, 1);
-		vertex_dirs[1] = v3s16( 1,-1,-1);
-		vertex_dirs[2] = v3s16( 1, 1,-1);
-		vertex_dirs[3] = v3s16( 1, 1, 1);
-	}
-	else if(dir == v3s16(-1,0,0))
-	{
-		// faces towards X-
-		vertex_dirs[0] = v3s16(-1,-1,-1);
-		vertex_dirs[1] = v3s16(-1,-1, 1);
-		vertex_dirs[2] = v3s16(-1, 1, 1);
-		vertex_dirs[3] = v3s16(-1, 1,-1);
-	}
-	else if(dir == v3s16(0,1,0))
-	{
-		// faces towards Y+ (assume Z- as "down" in texture)
-		vertex_dirs[0] = v3s16( 1, 1,-1);
-		vertex_dirs[1] = v3s16(-1, 1,-1);
-		vertex_dirs[2] = v3s16(-1, 1, 1);
-		vertex_dirs[3] = v3s16( 1, 1, 1);
-	}
-	else if(dir == v3s16(0,-1,0))
-	{
-		// faces towards Y- (assume Z+ as "down" in texture)
-		vertex_dirs[0] = v3s16( 1,-1, 1);
-		vertex_dirs[1] = v3s16(-1,-1, 1);
-		vertex_dirs[2] = v3s16(-1,-1,-1);
-		vertex_dirs[3] = v3s16( 1,-1,-1);
-	}
-}
-
-inline video::SColor lightColor(u8 alpha, u8 light)
-{
-	return video::SColor(alpha,light,light,light);
-}
-
-void makeFastFace(TileSpec tile, u8 li0, u8 li1, u8 li2, u8 li3, v3f p,
-		v3s16 dir, v3f scale, v3f posRelative_f,
-		core::array<FastFace> &dest)
-{
-	FastFace face;
-	
-	// Position is at the center of the cube.
-	v3f pos = p * BS;
-	posRelative_f *= BS;
-
-	v3f vertex_pos[4];
-	v3s16 vertex_dirs[4];
-	getNodeVertexDirs(dir, vertex_dirs);
-	for(u16 i=0; i<4; i++)
-	{
-		vertex_pos[i] = v3f(
-				BS/2*vertex_dirs[i].X,
-				BS/2*vertex_dirs[i].Y,
-				BS/2*vertex_dirs[i].Z
-		);
-	}
-
-	for(u16 i=0; i<4; i++)
-	{
-		vertex_pos[i].X *= scale.X;
-		vertex_pos[i].Y *= scale.Y;
-		vertex_pos[i].Z *= scale.Z;
-		vertex_pos[i] += pos + posRelative_f;
-	}
-
-	f32 abs_scale = 1.;
-	if     (scale.X < 0.999 || scale.X > 1.001) abs_scale = scale.X;
-	else if(scale.Y < 0.999 || scale.Y > 1.001) abs_scale = scale.Y;
-	else if(scale.Z < 0.999 || scale.Z > 1.001) abs_scale = scale.Z;
-
-	v3f zerovector = v3f(0,0,0);
-	
-	u8 alpha = tile.alpha;
-	/*u8 alpha = 255;
-	if(tile.id == TILE_WATER)
-		alpha = WATER_ALPHA;*/
-
-	float x0 = tile.texture.pos.X;
-	float y0 = tile.texture.pos.Y;
-	float w = tile.texture.size.X;
-	float h = tile.texture.size.Y;
-
-	/*video::SColor c = lightColor(alpha, li);
-
-	face.vertices[0] = video::S3DVertex(vertex_pos[0], v3f(0,1,0), c,
-			core::vector2d<f32>(x0+w*abs_scale, y0+h));
-	face.vertices[1] = video::S3DVertex(vertex_pos[1], v3f(0,1,0), c,
-			core::vector2d<f32>(x0, y0+h));
-	face.vertices[2] = video::S3DVertex(vertex_pos[2], v3f(0,1,0), c,
-			core::vector2d<f32>(x0, y0));
-	face.vertices[3] = video::S3DVertex(vertex_pos[3], v3f(0,1,0), c,
-			core::vector2d<f32>(x0+w*abs_scale, y0));*/
-
-	face.vertices[0] = video::S3DVertex(vertex_pos[0], v3f(0,1,0),
-			lightColor(alpha, li0),
-			core::vector2d<f32>(x0+w*abs_scale, y0+h));
-	face.vertices[1] = video::S3DVertex(vertex_pos[1], v3f(0,1,0),
-			lightColor(alpha, li1),
-			core::vector2d<f32>(x0, y0+h));
-	face.vertices[2] = video::S3DVertex(vertex_pos[2], v3f(0,1,0),
-			lightColor(alpha, li2),
-			core::vector2d<f32>(x0, y0));
-	face.vertices[3] = video::S3DVertex(vertex_pos[3], v3f(0,1,0),
-			lightColor(alpha, li3),
-			core::vector2d<f32>(x0+w*abs_scale, y0));
-
-	face.tile = tile;
-	//DEBUG
-	//f->tile = TILE_STONE;
-	
-	dest.push_back(face);
-}
-	
-/*
-	Gets node tile from any place relative to block.
-	Returns TILE_NODE if doesn't exist or should not be drawn.
-*/
-TileSpec getNodeTile(MapNode mn, v3s16 p, v3s16 face_dir,
-		NodeModMap &temp_mods)
-{
-	TileSpec spec;
-	spec = mn.getTile(face_dir);
-	
-	/*
-		Check temporary modifications on this node
-	*/
-	/*core::map<v3s16, NodeMod>::Node *n;
-	n = m_temp_mods.find(p);
-	// If modified
-	if(n != NULL)
-	{
-		struct NodeMod mod = n->getValue();*/
-	NodeMod mod;
-	if(temp_mods.get(p, &mod))
-	{
-		if(mod.type == NODEMOD_CHANGECONTENT)
-		{
-			MapNode mn2(mod.param);
-			spec = mn2.getTile(face_dir);
-		}
-		if(mod.type == NODEMOD_CRACK)
-		{
-			/*
-				Get texture id, translate it to name, append stuff to
-				name, get texture id
-			*/
-
-			// Get original texture name
-			u32 orig_id = spec.texture.id;
-			std::string orig_name = g_texturesource->getTextureName(orig_id);
-
-			// Create new texture name
-			std::ostringstream os;
-			os<<orig_name<<"^[crack"<<mod.param;
-
-			// Get new texture
-			u32 new_id = g_texturesource->getTextureId(os.str());
-			
-			/*dstream<<"MapBlock::getNodeTile(): Switching from "
-					<<orig_name<<" to "<<os.str()<<" ("
-					<<orig_id<<" to "<<new_id<<")"<<std::endl;*/
-			
-			spec.texture = g_texturesource->getTexture(new_id);
-		}
-	}
-	
-	return spec;
-}
-
-u8 getNodeContent(v3s16 p, MapNode mn, NodeModMap &temp_mods)
-{
-	/*
-		Check temporary modifications on this node
-	*/
-	/*core::map<v3s16, NodeMod>::Node *n;
-	n = m_temp_mods.find(p);
-	// If modified
-	if(n != NULL)
-	{
-		struct NodeMod mod = n->getValue();*/
-	NodeMod mod;
-	if(temp_mods.get(p, &mod))
-	{
-		if(mod.type == NODEMOD_CHANGECONTENT)
-		{
-			// Overrides content
-			return mod.param;
-		}
-		if(mod.type == NODEMOD_CRACK)
-		{
-			/*
-				Content doesn't change.
-				
-				face_contents works just like it should, because
-				there should not be faces between differently cracked
-				nodes.
-
-				If a semi-transparent node is cracked in front an
-				another one, it really doesn't matter whether there
-				is a cracked face drawn in between or not.
-			*/
-		}
-	}
-
-	return mn.d;
-}
-
-v3s16 dirs8[8] = {
-	v3s16(0,0,0),
-	v3s16(0,0,1),
-	v3s16(0,1,0),
-	v3s16(0,1,1),
-	v3s16(1,0,0),
-	v3s16(1,1,0),
-	v3s16(1,0,1),
-	v3s16(1,1,1),
-};
-
-// Calculate lighting at the XYZ- corner of p
-u8 getSmoothLight(v3s16 p, VoxelManipulator &vmanip, u32 daynight_ratio)
-{
-	u16 ambient_occlusion = 0;
-	u16 light = 0;
-	u16 light_count = 0;
-	for(u32 i=0; i<8; i++)
-	{
-		MapNode n = vmanip.getNodeNoEx(p - dirs8[i]);
-		if(content_features(n.d).param_type == CPT_LIGHT)
-		{
-			light += decode_light(n.getLightBlend(daynight_ratio));
-			light_count++;
-		}
-		else
-		{
-			if(n.d != CONTENT_IGNORE)
-				ambient_occlusion++;
-		}
-	}
-
-	if(light_count == 0)
-		return 255;
-	
-	light /= light_count;
-
-	if(ambient_occlusion > 4)
-	{
-		ambient_occlusion -= 4;
-		light = (float)light / ((float)ambient_occlusion * 0.5 + 1.0);
-	}
-
-	return light;
-}
-
-// Calculate lighting at the given corner of p
-u8 getSmoothLight(v3s16 p, v3s16 corner,
-		VoxelManipulator &vmanip, u32 daynight_ratio)
-{
-	if(corner.X == 1) p.X += 1;
-	else              assert(corner.X == -1);
-	if(corner.Y == 1) p.Y += 1;
-	else              assert(corner.Y == -1);
-	if(corner.Z == 1) p.Z += 1;
-	else              assert(corner.Z == -1);
-	
-	return getSmoothLight(p, vmanip, daynight_ratio);
-}
-
-void getTileInfo(
-		// Input:
-		v3s16 blockpos_nodes,
-		v3s16 p,
-		v3s16 face_dir,
-		u32 daynight_ratio,
-		VoxelManipulator &vmanip,
-		NodeModMap &temp_mods,
-		bool smooth_lighting,
-		// Output:
-		bool &makes_face,
-		v3s16 &p_corrected,
-		v3s16 &face_dir_corrected,
-		u8 *lights,
-		TileSpec &tile
-	)
-{
-	MapNode n0 = vmanip.getNodeNoEx(blockpos_nodes + p);
-	MapNode n1 = vmanip.getNodeNoEx(blockpos_nodes + p + face_dir);
-	TileSpec tile0 = getNodeTile(n0, p, face_dir, temp_mods);
-	TileSpec tile1 = getNodeTile(n1, p + face_dir, -face_dir, temp_mods);
-	
-	// This is hackish
-	u8 content0 = getNodeContent(p, n0, temp_mods);
-	u8 content1 = getNodeContent(p + face_dir, n1, temp_mods);
-	u8 mf = face_contents(content0, content1);
-
-	if(mf == 0)
-	{
-		makes_face = false;
-		return;
-	}
-
-	makes_face = true;
-	
-	if(mf == 1)
-	{
-		tile = tile0;
-		p_corrected = p;
-		face_dir_corrected = face_dir;
-	}
-	else
-	{
-		tile = tile1;
-		p_corrected = p + face_dir;
-		face_dir_corrected = -face_dir;
-	}
-	
-	if(smooth_lighting == false)
-	{
-		lights[0] = lights[1] = lights[2] = lights[3] =
-				decode_light(getFaceLight(daynight_ratio, n0, n1, face_dir));
-	}
-	else
-	{
-		v3s16 vertex_dirs[4];
-		getNodeVertexDirs(face_dir_corrected, vertex_dirs);
-		for(u16 i=0; i<4; i++)
-		{
-			lights[i] = getSmoothLight(blockpos_nodes + p_corrected,
-					vertex_dirs[i], vmanip, daynight_ratio);
-		}
-	}
-	
-	return;
-}
-
-/*
-	startpos:
-	translate_dir: unit vector with only one of x, y or z
-	face_dir: unit vector with only one of x, y or z
-*/
-void updateFastFaceRow(
-		u32 daynight_ratio,
-		v3f posRelative_f,
-		v3s16 startpos,
-		u16 length,
-		v3s16 translate_dir,
-		v3f translate_dir_f,
-		v3s16 face_dir,
-		v3f face_dir_f,
-		core::array<FastFace> &dest,
-		NodeModMap &temp_mods,
-		VoxelManipulator &vmanip,
-		v3s16 blockpos_nodes,
-		bool smooth_lighting)
-{
-	v3s16 p = startpos;
-	
-	u16 continuous_tiles_count = 0;
-	
-	bool makes_face;
-	v3s16 p_corrected;
-	v3s16 face_dir_corrected;
-	u8 lights[4];
-	TileSpec tile;
-	getTileInfo(blockpos_nodes, p, face_dir, daynight_ratio,
-			vmanip, temp_mods, smooth_lighting,
-			makes_face, p_corrected, face_dir_corrected, lights, tile);
-
-	for(u16 j=0; j<length; j++)
-	{
-		// If tiling can be done, this is set to false in the next step
-		bool next_is_different = true;
-		
-		v3s16 p_next;
-		
-		bool next_makes_face;
-		v3s16 next_p_corrected;
-		v3s16 next_face_dir_corrected;
-		u8 next_lights[4];
-		TileSpec next_tile;
-		
-		// If at last position, there is nothing to compare to and
-		// the face must be drawn anyway
-		if(j != length - 1)
-		{
-			p_next = p + translate_dir;
-			
-			getTileInfo(blockpos_nodes, p_next, face_dir, daynight_ratio,
-					vmanip, temp_mods, smooth_lighting,
-					next_makes_face, next_p_corrected,
-					next_face_dir_corrected, next_lights,
-					next_tile);
-			
-			if(next_makes_face == makes_face
-					&& next_p_corrected == p_corrected
-					&& next_face_dir_corrected == face_dir_corrected
-					&& next_lights[0] == lights[0]
-					&& next_lights[1] == lights[1]
-					&& next_lights[2] == lights[2]
-					&& next_lights[3] == lights[3]
-					&& next_tile == tile)
-			{
-				next_is_different = false;
-			}
-		}
-
-		continuous_tiles_count++;
-		
-		// This is set to true if the texture doesn't allow more tiling
-		bool end_of_texture = false;
-		/*
-			If there is no texture, it can be tiled infinitely.
-			If tiled==0, it means the texture can be tiled infinitely.
-			Otherwise check tiled agains continuous_tiles_count.
-		*/
-		if(tile.texture.atlas != NULL && tile.texture.tiled != 0)
-		{
-			if(tile.texture.tiled <= continuous_tiles_count)
-				end_of_texture = true;
-		}
-		
-		// Do this to disable tiling textures
-		//end_of_texture = true; //DEBUG
-		
-		if(next_is_different || end_of_texture)
-		{
-			/*
-				Create a face if there should be one
-			*/
-			if(makes_face)
-			{
-				// Floating point conversion of the position vector
-				v3f pf(p_corrected.X, p_corrected.Y, p_corrected.Z);
-				// Center point of face (kind of)
-				v3f sp = pf - ((f32)continuous_tiles_count / 2. - 0.5) * translate_dir_f;
-				v3f scale(1,1,1);
-
-				if(translate_dir.X != 0)
-				{
-					scale.X = continuous_tiles_count;
-				}
-				if(translate_dir.Y != 0)
-				{
-					scale.Y = continuous_tiles_count;
-				}
-				if(translate_dir.Z != 0)
-				{
-					scale.Z = continuous_tiles_count;
-				}
-				
-				makeFastFace(tile, lights[0], lights[1], lights[2], lights[3],
-						sp, face_dir_corrected, scale,
-						posRelative_f, dest);
-			}
-
-			continuous_tiles_count = 0;
-			
-			makes_face = next_makes_face;
-			p_corrected = next_p_corrected;
-			face_dir_corrected = next_face_dir_corrected;
-			lights[0] = next_lights[0];
-			lights[1] = next_lights[1];
-			lights[2] = next_lights[2];
-			lights[3] = next_lights[3];
-			tile = next_tile;
-		}
-		
-		p = p_next;
-	}
-}
-
-/*
-	This is used because CMeshBuffer::append() is very slow
-*/
-struct PreMeshBuffer
-{
-	video::SMaterial material;
-	core::array<u16> indices;
-	core::array<video::S3DVertex> vertices;
-};
-
-class MeshCollector
-{
-public:
-	void append(
-			video::SMaterial material,
-			const video::S3DVertex* const vertices,
-			u32 numVertices,
-			const u16* const indices,
-			u32 numIndices
-		)
-	{
-		PreMeshBuffer *p = NULL;
-		for(u32 i=0; i<m_prebuffers.size(); i++)
-		{
-			PreMeshBuffer &pp = m_prebuffers[i];
-			if(pp.material != material)
-				continue;
-
-			p = &pp;
-			break;
-		}
-
-		if(p == NULL)
-		{
-			PreMeshBuffer pp;
-			pp.material = material;
-			m_prebuffers.push_back(pp);
-			p = &m_prebuffers[m_prebuffers.size()-1];
-		}
-
-		u32 vertex_count = p->vertices.size();
-		for(u32 i=0; i<numIndices; i++)
-		{
-			u32 j = indices[i] + vertex_count;
-			if(j > 65535)
-			{
-				dstream<<"FIXME: Meshbuffer ran out of indices"<<std::endl;
-				// NOTE: Fix is to just add an another MeshBuffer
-			}
-			p->indices.push_back(j);
-		}
-		for(u32 i=0; i<numVertices; i++)
-		{
-			p->vertices.push_back(vertices[i]);
-		}
-	}
-
-	void fillMesh(scene::SMesh *mesh)
-	{
-		/*dstream<<"Filling mesh with "<<m_prebuffers.size()
-				<<" meshbuffers"<<std::endl;*/
-		for(u32 i=0; i<m_prebuffers.size(); i++)
-		{
-			PreMeshBuffer &p = m_prebuffers[i];
-
-			/*dstream<<"p.vertices.size()="<<p.vertices.size()
-					<<", p.indices.size()="<<p.indices.size()
-					<<std::endl;*/
-			
-			// Create meshbuffer
-			
-			// This is a "Standard MeshBuffer",
-			// it's a typedeffed CMeshBuffer<video::S3DVertex>
-			scene::SMeshBuffer *buf = new scene::SMeshBuffer();
-			// Set material
-			buf->Material = p.material;
-			//((scene::SMeshBuffer*)buf)->Material = p.material;
-			// Use VBO
-			//buf->setHardwareMappingHint(scene::EHM_STATIC);
-			// Add to mesh
-			mesh->addMeshBuffer(buf);
-			// Mesh grabbed it
-			buf->drop();
-
-			buf->append(p.vertices.pointer(), p.vertices.size(),
-					p.indices.pointer(), p.indices.size());
-		}
-	}
-
-private:
-	core::array<PreMeshBuffer> m_prebuffers;
-};
-
-void makeCuboid(video::SMaterial &material, MeshCollector *collector,
-	AtlasPointer* pa, video::SColor &c,
-	v3f &pos, f32 rx, f32 ry, f32 rz)
-{
-	video::S3DVertex v[4] =
-	{
-		video::S3DVertex(0,0,0, 0,0,0, c,
-			pa->x0(), pa->y1()),
-		video::S3DVertex(0,0,0, 0,0,0, c,
-			pa->x1(), pa->y1()),
-		video::S3DVertex(0,0,0, 0,0,0, c,
-			pa->x1(), pa->y0()),
-		video::S3DVertex(0,0,0, 0,0,0, c,
-			pa->x0(), pa->y0())
-	};
-
-	for(int i=0;i<6;i++)
-	{
-		switch(i)
-		{
-			case 0:
-				v[0].Pos.X=-rx; v[0].Pos.Y= ry; v[0].Pos.Z=-rz;
-				v[1].Pos.X=-rx; v[1].Pos.Y= ry; v[1].Pos.Z= rz;
-				v[2].Pos.X= rx; v[2].Pos.Y= ry; v[2].Pos.Z= rz;
-				v[3].Pos.X= rx; v[3].Pos.Y= ry, v[3].Pos.Z=-rz;
-				break;
-			case 1:
-				v[0].Pos.X=-rx; v[0].Pos.Y= ry; v[0].Pos.Z=-rz;
-				v[1].Pos.X= rx; v[1].Pos.Y= ry; v[1].Pos.Z=-rz;
-				v[2].Pos.X= rx; v[2].Pos.Y=-ry; v[2].Pos.Z=-rz;
-				v[3].Pos.X=-rx; v[3].Pos.Y=-ry, v[3].Pos.Z=-rz;
-				break;
-			case 2:
-				v[0].Pos.X= rx; v[0].Pos.Y= ry; v[0].Pos.Z=-rz;
-				v[1].Pos.X= rx; v[1].Pos.Y= ry; v[1].Pos.Z= rz;
-				v[2].Pos.X= rx; v[2].Pos.Y=-ry; v[2].Pos.Z= rz;
-				v[3].Pos.X= rx; v[3].Pos.Y=-ry, v[3].Pos.Z=-rz;
-				break;
-			case 3:
-				v[0].Pos.X= rx; v[0].Pos.Y= ry; v[0].Pos.Z= rz;
-				v[1].Pos.X=-rx; v[1].Pos.Y= ry; v[1].Pos.Z= rz;
-				v[2].Pos.X=-rx; v[2].Pos.Y=-ry; v[2].Pos.Z= rz;
-				v[3].Pos.X= rx; v[3].Pos.Y=-ry, v[3].Pos.Z= rz;
-				break;
-			case 4:
-				v[0].Pos.X=-rx; v[0].Pos.Y= ry; v[0].Pos.Z= rz;
-				v[1].Pos.X=-rx; v[1].Pos.Y= ry; v[1].Pos.Z=-rz;
-				v[2].Pos.X=-rx; v[2].Pos.Y=-ry; v[2].Pos.Z=-rz;
-				v[3].Pos.X=-rx; v[3].Pos.Y=-ry, v[3].Pos.Z= rz;
-				break;
-			case 5:
-				v[0].Pos.X= rx; v[0].Pos.Y=-ry; v[0].Pos.Z= rz;
-				v[1].Pos.X=-rx; v[1].Pos.Y=-ry; v[1].Pos.Z= rz;
-				v[2].Pos.X=-rx; v[2].Pos.Y=-ry; v[2].Pos.Z=-rz;
-				v[3].Pos.X= rx; v[3].Pos.Y=-ry, v[3].Pos.Z=-rz;
-				break;
-		}
-		for(u16 i=0; i<4; i++)
-			v[i].Pos += pos;
-		u16 indices[] = {0,1,2,2,3,0};
-		collector->append(material, v, 4, indices, 6);
-
-	}
-
-}
-
-scene::SMesh* makeMapBlockMesh(MeshMakeData *data)
-{
-	// 4-21ms for MAP_BLOCKSIZE=16
-	// 24-155ms for MAP_BLOCKSIZE=32
-	//TimeTaker timer1("makeMapBlockMesh()");
-
-	core::array<FastFace> fastfaces_new;
-
-	v3s16 blockpos_nodes = data->m_blockpos*MAP_BLOCKSIZE;
-	
-	// floating point conversion
-	v3f posRelative_f(blockpos_nodes.X, blockpos_nodes.Y, blockpos_nodes.Z);
-	
-	/*
-		Some settings
-	*/
-	bool new_style_water = g_settings.getBool("new_style_water");
-	bool new_style_leaves = g_settings.getBool("new_style_leaves");
-	bool smooth_lighting = g_settings.getBool("smooth_lighting");
-	
-	float node_water_level = 1.0;
-	if(new_style_water)
-		node_water_level = 0.85;
-	
-	/*
-		We are including the faces of the trailing edges of the block.
-		This means that when something changes, the caller must
-		also update the meshes of the blocks at the leading edges.
-
-		NOTE: This is the slowest part of this method.
-	*/
-	
-	{
-		// 4-23ms for MAP_BLOCKSIZE=16
-		//TimeTaker timer2("updateMesh() collect");
-
-		/*
-			Go through every y,z and get top(y+) faces in rows of x+
-		*/
-		for(s16 y=0; y<MAP_BLOCKSIZE; y++){
-			for(s16 z=0; z<MAP_BLOCKSIZE; z++){
-				updateFastFaceRow(data->m_daynight_ratio, posRelative_f,
-						v3s16(0,y,z), MAP_BLOCKSIZE,
-						v3s16(1,0,0), //dir
-						v3f  (1,0,0),
-						v3s16(0,1,0), //face dir
-						v3f  (0,1,0),
-						fastfaces_new,
-						data->m_temp_mods,
-						data->m_vmanip,
-						blockpos_nodes,
-						smooth_lighting);
-			}
-		}
-		/*
-			Go through every x,y and get right(x+) faces in rows of z+
-		*/
-		for(s16 x=0; x<MAP_BLOCKSIZE; x++){
-			for(s16 y=0; y<MAP_BLOCKSIZE; y++){
-				updateFastFaceRow(data->m_daynight_ratio, posRelative_f,
-						v3s16(x,y,0), MAP_BLOCKSIZE,
-						v3s16(0,0,1),
-						v3f  (0,0,1),
-						v3s16(1,0,0),
-						v3f  (1,0,0),
-						fastfaces_new,
-						data->m_temp_mods,
-						data->m_vmanip,
-						blockpos_nodes,
-						smooth_lighting);
-			}
-		}
-		/*
-			Go through every y,z and get back(z+) faces in rows of x+
-		*/
-		for(s16 z=0; z<MAP_BLOCKSIZE; z++){
-			for(s16 y=0; y<MAP_BLOCKSIZE; y++){
-				updateFastFaceRow(data->m_daynight_ratio, posRelative_f,
-						v3s16(0,y,z), MAP_BLOCKSIZE,
-						v3s16(1,0,0),
-						v3f  (1,0,0),
-						v3s16(0,0,1),
-						v3f  (0,0,1),
-						fastfaces_new,
-						data->m_temp_mods,
-						data->m_vmanip,
-						blockpos_nodes,
-						smooth_lighting);
-			}
-		}
-	}
-
-	// End of slow part
-
-	/*
-		Convert FastFaces to SMesh
-	*/
-
-	MeshCollector collector;
-
-	if(fastfaces_new.size() > 0)
-	{
-		// avg 0ms (100ms spikes when loading textures the first time)
-		//TimeTaker timer2("updateMesh() mesh building");
-
-		video::SMaterial material;
-		material.setFlag(video::EMF_LIGHTING, false);
-		material.setFlag(video::EMF_BILINEAR_FILTER, false);
-		material.setFlag(video::EMF_FOG_ENABLE, true);
-		//material.setFlag(video::EMF_ANTI_ALIASING, video::EAAM_OFF);
-		//material.setFlag(video::EMF_ANTI_ALIASING, video::EAAM_SIMPLE);
-
-		for(u32 i=0; i<fastfaces_new.size(); i++)
-		{
-			FastFace &f = fastfaces_new[i];
-
-			const u16 indices[] = {0,1,2,2,3,0};
-			const u16 indices_alternate[] = {0,1,3,2,3,1};
-			
-			video::ITexture *texture = f.tile.texture.atlas;
-			if(texture == NULL)
-				continue;
-
-			material.setTexture(0, texture);
-			
-			f.tile.applyMaterialOptions(material);
-
-			const u16 *indices_p = indices;
-			
-			/*
-				Revert triangles for nicer looking gradient if vertices
-				1 and 3 have same color or 0 and 2 have different color.
-			*/
-			if(f.vertices[0].Color != f.vertices[2].Color
-					|| f.vertices[1].Color == f.vertices[3].Color)
-				indices_p = indices_alternate;
-			
-			collector.append(material, f.vertices, 4, indices_p, 6);
-		}
-	}
-
-	/*
-		Add special graphics:
-		- torches
-		- flowing water
-	*/
-
-	// 0ms
-	//TimeTaker timer2("updateMesh() adding special stuff");
-
-	// Flowing water material
-	video::SMaterial material_water1;
-	material_water1.setFlag(video::EMF_LIGHTING, false);
-	material_water1.setFlag(video::EMF_BACK_FACE_CULLING, false);
-	material_water1.setFlag(video::EMF_BILINEAR_FILTER, false);
-	material_water1.setFlag(video::EMF_FOG_ENABLE, true);
-	material_water1.MaterialType = video::EMT_TRANSPARENT_VERTEX_ALPHA;
-	AtlasPointer pa_water1 = g_texturesource->getTexture(
-			g_texturesource->getTextureId("water.png"));
-	material_water1.setTexture(0, pa_water1.atlas);
-
-	// New-style leaves material
-	video::SMaterial material_leaves1;
-	material_leaves1.setFlag(video::EMF_LIGHTING, false);
-	//material_leaves1.setFlag(video::EMF_BACK_FACE_CULLING, false);
-	material_leaves1.setFlag(video::EMF_BILINEAR_FILTER, false);
-	material_leaves1.setFlag(video::EMF_FOG_ENABLE, true);
-	material_leaves1.MaterialType = video::EMT_TRANSPARENT_ALPHA_CHANNEL_REF;
-	AtlasPointer pa_leaves1 = g_texturesource->getTexture(
-			g_texturesource->getTextureId("leaves.png"));
-	material_leaves1.setTexture(0, pa_leaves1.atlas);
-
-	// Glass material
-	video::SMaterial material_glass;
-	material_glass.setFlag(video::EMF_LIGHTING, false);
-	material_glass.setFlag(video::EMF_BILINEAR_FILTER, false);
-	material_glass.setFlag(video::EMF_FOG_ENABLE, true);
-	material_glass.MaterialType = video::EMT_TRANSPARENT_ALPHA_CHANNEL_REF;
-	AtlasPointer pa_glass = g_texturesource->getTexture(
-			g_texturesource->getTextureId("glass.png"));
-	material_glass.setTexture(0, pa_glass.atlas);
-
-	// Wood material
-	video::SMaterial material_wood;
-	material_wood.setFlag(video::EMF_LIGHTING, false);
-	material_wood.setFlag(video::EMF_BILINEAR_FILTER, false);
-	material_wood.setFlag(video::EMF_FOG_ENABLE, true);
-	material_wood.MaterialType = video::EMT_TRANSPARENT_ALPHA_CHANNEL_REF;
-	AtlasPointer pa_wood = g_texturesource->getTexture(
-			g_texturesource->getTextureId("wood.png"));
-	material_wood.setTexture(0, pa_wood.atlas);
-
-	// Papyrus material
-	video::SMaterial material_papyrus;
-	material_papyrus.setFlag(video::EMF_LIGHTING, false);
-	material_papyrus.setFlag(video::EMF_BILINEAR_FILTER, false);
-	material_papyrus.setFlag(video::EMF_FOG_ENABLE, true);
-	material_papyrus.MaterialType = video::EMT_TRANSPARENT_ALPHA_CHANNEL_REF;
-	AtlasPointer pa_papyrus = g_texturesource->getTexture(
-			g_texturesource->getTextureId("papyrus.png"));
-	material_papyrus.setTexture(0, pa_papyrus.atlas);
-
-	for(s16 z=0; z<MAP_BLOCKSIZE; z++)
-	for(s16 y=0; y<MAP_BLOCKSIZE; y++)
-	for(s16 x=0; x<MAP_BLOCKSIZE; x++)
-	{
-		v3s16 p(x,y,z);
-
-		MapNode n = data->m_vmanip.getNodeNoEx(blockpos_nodes+p);
-		
-		/*
-			Add torches to mesh
-		*/
-		if(n.d == CONTENT_TORCH)
-		{
-			video::SColor c(255,255,255,255);
-
-			// Wall at X+ of node
-			video::S3DVertex vertices[4] =
-			{
-				video::S3DVertex(-BS/2,-BS/2,0, 0,0,0, c, 0,1),
-				video::S3DVertex(BS/2,-BS/2,0, 0,0,0, c, 1,1),
-				video::S3DVertex(BS/2,BS/2,0, 0,0,0, c, 1,0),
-				video::S3DVertex(-BS/2,BS/2,0, 0,0,0, c, 0,0),
-			};
-
-			v3s16 dir = unpackDir(n.dir);
-
-			for(s32 i=0; i<4; i++)
-			{
-				if(dir == v3s16(1,0,0))
-					vertices[i].Pos.rotateXZBy(0);
-				if(dir == v3s16(-1,0,0))
-					vertices[i].Pos.rotateXZBy(180);
-				if(dir == v3s16(0,0,1))
-					vertices[i].Pos.rotateXZBy(90);
-				if(dir == v3s16(0,0,-1))
-					vertices[i].Pos.rotateXZBy(-90);
-				if(dir == v3s16(0,-1,0))
-					vertices[i].Pos.rotateXZBy(45);
-				if(dir == v3s16(0,1,0))
-					vertices[i].Pos.rotateXZBy(-45);
-
-				vertices[i].Pos += intToFloat(p + blockpos_nodes, BS);
-			}
-
-			// Set material
-			video::SMaterial material;
-			material.setFlag(video::EMF_LIGHTING, false);
-			material.setFlag(video::EMF_BACK_FACE_CULLING, false);
-			material.setFlag(video::EMF_BILINEAR_FILTER, false);
-			//material.MaterialType = video::EMT_TRANSPARENT_ALPHA_CHANNEL;
-			material.MaterialType
-					= video::EMT_TRANSPARENT_ALPHA_CHANNEL_REF;
-
-			if(dir == v3s16(0,-1,0))
-				material.setTexture(0,
-						g_texturesource->getTextureRaw("torch_on_floor.png"));
-			else if(dir == v3s16(0,1,0))
-				material.setTexture(0,
-						g_texturesource->getTextureRaw("torch_on_ceiling.png"));
-			// For backwards compatibility
-			else if(dir == v3s16(0,0,0))
-				material.setTexture(0,
-						g_texturesource->getTextureRaw("torch_on_floor.png"));
-			else
-				material.setTexture(0, 
-						g_texturesource->getTextureRaw("torch.png"));
-
-			u16 indices[] = {0,1,2,2,3,0};
-			// Add to mesh collector
-			collector.append(material, vertices, 4, indices, 6);
-		}
-		/*
-			Signs on walls
-		*/
-		if(n.d == CONTENT_SIGN_WALL)
-		{
-			u8 l = decode_light(n.getLightBlend(data->m_daynight_ratio));
-			video::SColor c(255,l,l,l);
-				
-			float d = (float)BS/16;
-			// Wall at X+ of node
-			video::S3DVertex vertices[4] =
-			{
-				video::S3DVertex(BS/2-d,-BS/2,-BS/2, 0,0,0, c, 0,1),
-				video::S3DVertex(BS/2-d,-BS/2,BS/2, 0,0,0, c, 1,1),
-				video::S3DVertex(BS/2-d,BS/2,BS/2, 0,0,0, c, 1,0),
-				video::S3DVertex(BS/2-d,BS/2,-BS/2, 0,0,0, c, 0,0),
-			};
-
-			v3s16 dir = unpackDir(n.dir);
-
-			for(s32 i=0; i<4; i++)
-			{
-				if(dir == v3s16(1,0,0))
-					vertices[i].Pos.rotateXZBy(0);
-				if(dir == v3s16(-1,0,0))
-					vertices[i].Pos.rotateXZBy(180);
-				if(dir == v3s16(0,0,1))
-					vertices[i].Pos.rotateXZBy(90);
-				if(dir == v3s16(0,0,-1))
-					vertices[i].Pos.rotateXZBy(-90);
-				if(dir == v3s16(0,-1,0))
-					vertices[i].Pos.rotateXYBy(-90);
-				if(dir == v3s16(0,1,0))
-					vertices[i].Pos.rotateXYBy(90);
-
-				vertices[i].Pos += intToFloat(p + blockpos_nodes, BS);
-			}
-
-			// Set material
-			video::SMaterial material;
-			material.setFlag(video::EMF_LIGHTING, false);
-			material.setFlag(video::EMF_BACK_FACE_CULLING, false);
-			material.setFlag(video::EMF_BILINEAR_FILTER, false);
-			material.setFlag(video::EMF_FOG_ENABLE, true);
-			//material.MaterialType = video::EMT_TRANSPARENT_ALPHA_CHANNEL;
-			material.MaterialType
-					= video::EMT_TRANSPARENT_ALPHA_CHANNEL_REF;
-
-			material.setTexture(0, 
-					g_texturesource->getTextureRaw("sign_wall.png"));
-
-			u16 indices[] = {0,1,2,2,3,0};
-			// Add to mesh collector
-			collector.append(material, vertices, 4, indices, 6);
-		}
-		/*
-			Add flowing water to mesh
-		*/
-		else if(n.d == CONTENT_WATER)
-		{
-			bool top_is_water = false;
-			MapNode ntop = data->m_vmanip.getNodeNoEx(blockpos_nodes + v3s16(x,y+1,z));
-			if(ntop.d == CONTENT_WATER || ntop.d == CONTENT_WATERSOURCE)
-				top_is_water = true;
-			
-			u8 l = 0;
-			// Use the light of the node on top if possible
-			if(content_features(ntop.d).param_type == CPT_LIGHT)
-				l = decode_light(ntop.getLightBlend(data->m_daynight_ratio));
-			// Otherwise use the light of this node (the water)
-			else
-				l = decode_light(n.getLightBlend(data->m_daynight_ratio));
-			video::SColor c(WATER_ALPHA,l,l,l);
-			
-			// Neighbor water levels (key = relative position)
-			// Includes current node
-			core::map<v3s16, f32> neighbor_levels;
-			core::map<v3s16, u8> neighbor_contents;
-			core::map<v3s16, u8> neighbor_flags;
-			const u8 neighborflag_top_is_water = 0x01;
-			v3s16 neighbor_dirs[9] = {
-				v3s16(0,0,0),
-				v3s16(0,0,1),
-				v3s16(0,0,-1),
-				v3s16(1,0,0),
-				v3s16(-1,0,0),
-				v3s16(1,0,1),
-				v3s16(-1,0,-1),
-				v3s16(1,0,-1),
-				v3s16(-1,0,1),
-			};
-			for(u32 i=0; i<9; i++)
-			{
-				u8 content = CONTENT_AIR;
-				float level = -0.5 * BS;
-				u8 flags = 0;
-				// Check neighbor
-				v3s16 p2 = p + neighbor_dirs[i];
-				MapNode n2 = data->m_vmanip.getNodeNoEx(blockpos_nodes + p2);
-				if(n2.d != CONTENT_IGNORE)
-				{
-					content = n2.d;
-
-					if(n2.d == CONTENT_WATERSOURCE)
-						level = (-0.5+node_water_level) * BS;
-					else if(n2.d == CONTENT_WATER)
-						level = (-0.5 + ((float)n2.param2 + 0.5) / 8.0
-								* node_water_level) * BS;
-
-					// Check node above neighbor.
-					// NOTE: This doesn't get executed if neighbor
-					//       doesn't exist
-					p2.Y += 1;
-					n2 = data->m_vmanip.getNodeNoEx(blockpos_nodes + p2);
-					if(n2.d == CONTENT_WATERSOURCE || n2.d == CONTENT_WATER)
-						flags |= neighborflag_top_is_water;
-				}
-				
-				neighbor_levels.insert(neighbor_dirs[i], level);
-				neighbor_contents.insert(neighbor_dirs[i], content);
-				neighbor_flags.insert(neighbor_dirs[i], flags);
-			}
-
-			//float water_level = (-0.5 + ((float)n.param2 + 0.5) / 8.0) * BS;
-			//float water_level = neighbor_levels[v3s16(0,0,0)];
-
-			// Corner heights (average between four waters)
-			f32 corner_levels[4];
-			
-			v3s16 halfdirs[4] = {
-				v3s16(0,0,0),
-				v3s16(1,0,0),
-				v3s16(1,0,1),
-				v3s16(0,0,1),
-			};
-			for(u32 i=0; i<4; i++)
-			{
-				v3s16 cornerdir = halfdirs[i];
-				float cornerlevel = 0;
-				u32 valid_count = 0;
-				for(u32 j=0; j<4; j++)
-				{
-					v3s16 neighbordir = cornerdir - halfdirs[j];
-					u8 content = neighbor_contents[neighbordir];
-					// Special case for source nodes
-					if(content == CONTENT_WATERSOURCE)
-					{
-						cornerlevel = (-0.5+node_water_level)*BS;
-						valid_count = 1;
-						break;
-					}
-					else if(content == CONTENT_WATER)
-					{
-						cornerlevel += neighbor_levels[neighbordir];
-						valid_count++;
-					}
-					else if(content == CONTENT_AIR)
-					{
-						cornerlevel += -0.5*BS;
-						valid_count++;
-					}
-				}
-				if(valid_count > 0)
-					cornerlevel /= valid_count;
-				corner_levels[i] = cornerlevel;
-			}
-
-			/*
-				Generate sides
-			*/
-
-			v3s16 side_dirs[4] = {
-				v3s16(1,0,0),
-				v3s16(-1,0,0),
-				v3s16(0,0,1),
-				v3s16(0,0,-1),
-			};
-			s16 side_corners[4][2] = {
-				{1, 2},
-				{3, 0},
-				{2, 3},
-				{0, 1},
-			};
-			for(u32 i=0; i<4; i++)
-			{
-				v3s16 dir = side_dirs[i];
-
-				/*
-					If our topside is water and neighbor's topside
-					is water, don't draw side face
-				*/
-				if(top_is_water &&
-						neighbor_flags[dir] & neighborflag_top_is_water)
-					continue;
-
-				u8 neighbor_content = neighbor_contents[dir];
-				
-				// Don't draw face if neighbor is not air or water
-				if(neighbor_content != CONTENT_AIR
-						&& neighbor_content != CONTENT_WATER)
-					continue;
-				
-				bool neighbor_is_water = (neighbor_content == CONTENT_WATER);
-				
-				// Don't draw any faces if neighbor is water and top is water
-				if(neighbor_is_water == true && top_is_water == false)
-					continue;
-				
-				video::S3DVertex vertices[4] =
-				{
-					/*video::S3DVertex(-BS/2,0,BS/2, 0,0,0, c, 0,1),
-					video::S3DVertex(BS/2,0,BS/2, 0,0,0, c, 1,1),
-					video::S3DVertex(BS/2,0,BS/2, 0,0,0, c, 1,0),
-					video::S3DVertex(-BS/2,0,BS/2, 0,0,0, c, 0,0),*/
-					video::S3DVertex(-BS/2,0,BS/2, 0,0,0, c,
-							pa_water1.x0(), pa_water1.y1()),
-					video::S3DVertex(BS/2,0,BS/2, 0,0,0, c,
-							pa_water1.x1(), pa_water1.y1()),
-					video::S3DVertex(BS/2,0,BS/2, 0,0,0, c,
-							pa_water1.x1(), pa_water1.y0()),
-					video::S3DVertex(-BS/2,0,BS/2, 0,0,0, c,
-							pa_water1.x0(), pa_water1.y0()),
-				};
-				
-				/*
-					If our topside is water, set upper border of face
-					at upper border of node
-				*/
-				if(top_is_water)
-				{
-					vertices[2].Pos.Y = 0.5*BS;
-					vertices[3].Pos.Y = 0.5*BS;
-				}
-				/*
-					Otherwise upper position of face is corner levels
-				*/
-				else
-				{
-					vertices[2].Pos.Y = corner_levels[side_corners[i][0]];
-					vertices[3].Pos.Y = corner_levels[side_corners[i][1]];
-				}
-				
-				/*
-					If neighbor is water, lower border of face is corner
-					water levels
-				*/
-				if(neighbor_is_water)
-				{
-					vertices[0].Pos.Y = corner_levels[side_corners[i][1]];
-					vertices[1].Pos.Y = corner_levels[side_corners[i][0]];
-				}
-				/*
-					If neighbor is not water, lower border of face is
-					lower border of node
-				*/
-				else
-				{
-					vertices[0].Pos.Y = -0.5*BS;
-					vertices[1].Pos.Y = -0.5*BS;
-				}
-				
-				for(s32 j=0; j<4; j++)
-				{
-					if(dir == v3s16(0,0,1))
-						vertices[j].Pos.rotateXZBy(0);
-					if(dir == v3s16(0,0,-1))
-						vertices[j].Pos.rotateXZBy(180);
-					if(dir == v3s16(-1,0,0))
-						vertices[j].Pos.rotateXZBy(90);
-					if(dir == v3s16(1,0,-0))
-						vertices[j].Pos.rotateXZBy(-90);
-
-					vertices[j].Pos += intToFloat(p + blockpos_nodes, BS);
-				}
-
-				u16 indices[] = {0,1,2,2,3,0};
-				// Add to mesh collector
-				collector.append(material_water1, vertices, 4, indices, 6);
-			}
-			
-			/*
-				Generate top side, if appropriate
-			*/
-			
-			if(top_is_water == false)
-			{
-				video::S3DVertex vertices[4] =
-				{
-					/*video::S3DVertex(-BS/2,0,-BS/2, 0,0,0, c, 0,1),
-					video::S3DVertex(BS/2,0,-BS/2, 0,0,0, c, 1,1),
-					video::S3DVertex(BS/2,0,BS/2, 0,0,0, c, 1,0),
-					video::S3DVertex(-BS/2,0,BS/2, 0,0,0, c, 0,0),*/
-					video::S3DVertex(-BS/2,0,BS/2, 0,0,0, c,
-							pa_water1.x0(), pa_water1.y1()),
-					video::S3DVertex(BS/2,0,BS/2, 0,0,0, c,
-							pa_water1.x1(), pa_water1.y1()),
-					video::S3DVertex(BS/2,0,-BS/2, 0,0,0, c,
-							pa_water1.x1(), pa_water1.y0()),
-					video::S3DVertex(-BS/2,0,-BS/2, 0,0,0, c,
-							pa_water1.x0(), pa_water1.y0()),
-				};
-				
-				// This fixes a strange bug
-				s32 corner_resolve[4] = {3,2,1,0};
-
-				for(s32 i=0; i<4; i++)
-				{
-					//vertices[i].Pos.Y += water_level;
-					//vertices[i].Pos.Y += neighbor_levels[v3s16(0,0,0)];
-					s32 j = corner_resolve[i];
-					vertices[i].Pos.Y += corner_levels[j];
-					vertices[i].Pos += intToFloat(p + blockpos_nodes, BS);
-				}
-
-				u16 indices[] = {0,1,2,2,3,0};
-				// Add to mesh collector
-				collector.append(material_water1, vertices, 4, indices, 6);
-			}
-		}
-		/*
-			Add water sources to mesh if using new style
-		*/
-		else if(n.d == CONTENT_WATERSOURCE && new_style_water)
-		{
-			//bool top_is_water = false;
-			bool top_is_air = false;
-			MapNode n = data->m_vmanip.getNodeNoEx(blockpos_nodes + v3s16(x,y+1,z));
-			/*if(n.d == CONTENT_WATER || n.d == CONTENT_WATERSOURCE)
-				top_is_water = true;*/
-			if(n.d == CONTENT_AIR)
-				top_is_air = true;
-			
-			/*if(top_is_water == true)
-				continue;*/
-			if(top_is_air == false)
-				continue;
-
-			u8 l = decode_light(n.getLightBlend(data->m_daynight_ratio));
-			video::SColor c(WATER_ALPHA,l,l,l);
-			
-			video::S3DVertex vertices[4] =
-			{
-				/*video::S3DVertex(-BS/2,0,-BS/2, 0,0,0, c, 0,1),
-				video::S3DVertex(BS/2,0,-BS/2, 0,0,0, c, 1,1),
-				video::S3DVertex(BS/2,0,BS/2, 0,0,0, c, 1,0),
-				video::S3DVertex(-BS/2,0,BS/2, 0,0,0, c, 0,0),*/
-				video::S3DVertex(-BS/2,0,BS/2, 0,0,0, c,
-						pa_water1.x0(), pa_water1.y1()),
-				video::S3DVertex(BS/2,0,BS/2, 0,0,0, c,
-						pa_water1.x1(), pa_water1.y1()),
-				video::S3DVertex(BS/2,0,-BS/2, 0,0,0, c,
-						pa_water1.x1(), pa_water1.y0()),
-				video::S3DVertex(-BS/2,0,-BS/2, 0,0,0, c,
-						pa_water1.x0(), pa_water1.y0()),
-			};
-
-			for(s32 i=0; i<4; i++)
-			{
-				vertices[i].Pos.Y += (-0.5+node_water_level)*BS;
-				vertices[i].Pos += intToFloat(p + blockpos_nodes, BS);
-			}
-
-			u16 indices[] = {0,1,2,2,3,0};
-			// Add to mesh collector
-			collector.append(material_water1, vertices, 4, indices, 6);
-		}
-		/*
-			Add leaves if using new style
-		*/
-		else if(n.d == CONTENT_LEAVES && new_style_leaves)
-		{
-			/*u8 l = decode_light(n.getLightBlend(data->m_daynight_ratio));*/
-			u8 l = decode_light(undiminish_light(n.getLightBlend(data->m_daynight_ratio)));
-			video::SColor c(255,l,l,l);
-
-			for(u32 j=0; j<6; j++)
-			{
-				video::S3DVertex vertices[4] =
-				{
-					/*video::S3DVertex(-BS/2,-BS/2,BS/2, 0,0,0, c, 0,1),
-					video::S3DVertex(BS/2,-BS/2,BS/2, 0,0,0, c, 1,1),
-					video::S3DVertex(BS/2,BS/2,BS/2, 0,0,0, c, 1,0),
-					video::S3DVertex(-BS/2,BS/2,BS/2, 0,0,0, c, 0,0),*/
-					video::S3DVertex(-BS/2,-BS/2,BS/2, 0,0,0, c,
-						pa_leaves1.x0(), pa_leaves1.y1()),
-					video::S3DVertex(BS/2,-BS/2,BS/2, 0,0,0, c,
-						pa_leaves1.x1(), pa_leaves1.y1()),
-					video::S3DVertex(BS/2,BS/2,BS/2, 0,0,0, c,
-						pa_leaves1.x1(), pa_leaves1.y0()),
-					video::S3DVertex(-BS/2,BS/2,BS/2, 0,0,0, c,
-						pa_leaves1.x0(), pa_leaves1.y0()),
-				};
-
-				if(j == 0)
-				{
-					for(u16 i=0; i<4; i++)
-						vertices[i].Pos.rotateXZBy(0);
-				}
-				else if(j == 1)
-				{
-					for(u16 i=0; i<4; i++)
-						vertices[i].Pos.rotateXZBy(180);
-				}
-				else if(j == 2)
-				{
-					for(u16 i=0; i<4; i++)
-						vertices[i].Pos.rotateXZBy(-90);
-				}
-				else if(j == 3)
-				{
-					for(u16 i=0; i<4; i++)
-						vertices[i].Pos.rotateXZBy(90);
-				}
-				else if(j == 4)
-				{
-					for(u16 i=0; i<4; i++)
-						vertices[i].Pos.rotateYZBy(-90);
-				}
-				else if(j == 5)
-				{
-					for(u16 i=0; i<4; i++)
-						vertices[i].Pos.rotateYZBy(90);
-				}
-
-				for(u16 i=0; i<4; i++)
-				{
-					vertices[i].Pos += intToFloat(p + blockpos_nodes, BS);
-				}
-
-				u16 indices[] = {0,1,2,2,3,0};
-				// Add to mesh collector
-				collector.append(material_leaves1, vertices, 4, indices, 6);
-			}
-		}
-		/*
-			Add glass
-		*/
-		else if(n.d == CONTENT_GLASS)
-		{
-			u8 l = decode_light(undiminish_light(n.getLightBlend(data->m_daynight_ratio)));
-			video::SColor c(255,l,l,l);
-
-			for(u32 j=0; j<6; j++)
-			{
-				video::S3DVertex vertices[4] =
-				{
-					video::S3DVertex(-BS/2,-BS/2,BS/2, 0,0,0, c,
-						pa_glass.x0(), pa_glass.y1()),
-					video::S3DVertex(BS/2,-BS/2,BS/2, 0,0,0, c,
-						pa_glass.x1(), pa_glass.y1()),
-					video::S3DVertex(BS/2,BS/2,BS/2, 0,0,0, c,
-						pa_glass.x1(), pa_glass.y0()),
-					video::S3DVertex(-BS/2,BS/2,BS/2, 0,0,0, c,
-						pa_glass.x0(), pa_glass.y0()),
-				};
-
-				if(j == 0)
-				{
-					for(u16 i=0; i<4; i++)
-						vertices[i].Pos.rotateXZBy(0);
-				}
-				else if(j == 1)
-				{
-					for(u16 i=0; i<4; i++)
-						vertices[i].Pos.rotateXZBy(180);
-				}
-				else if(j == 2)
-				{
-					for(u16 i=0; i<4; i++)
-						vertices[i].Pos.rotateXZBy(-90);
-				}
-				else if(j == 3)
-				{
-					for(u16 i=0; i<4; i++)
-						vertices[i].Pos.rotateXZBy(90);
-				}
-				else if(j == 4)
-				{
-					for(u16 i=0; i<4; i++)
-						vertices[i].Pos.rotateYZBy(-90);
-				}
-				else if(j == 5)
-				{
-					for(u16 i=0; i<4; i++)
-						vertices[i].Pos.rotateYZBy(90);
-				}
-
-				for(u16 i=0; i<4; i++)
-				{
-					vertices[i].Pos += intToFloat(p + blockpos_nodes, BS);
-				}
-
-				u16 indices[] = {0,1,2,2,3,0};
-				// Add to mesh collector
-				collector.append(material_glass, vertices, 4, indices, 6);
-			}
-		}
-		/*
-			Add fence
-		*/
-		else if(n.d == CONTENT_FENCE)
-		{
-			u8 l = decode_light(undiminish_light(n.getLightBlend(data->m_daynight_ratio)));
-			video::SColor c(255,l,l,l);
-
-			const f32 post_rad=(f32)BS/(32.0/4.0);
-			const f32 bar_rad=(f32)BS/(32.0/2.0);
-			const f32 bar_len=(f32)(BS/2)-post_rad;
-
-			// The post - always present
-			v3f pos = intToFloat(p+blockpos_nodes, BS);
-			makeCuboid(material_wood, &collector,
-				&pa_wood, c, pos,
-				post_rad,BS/2,post_rad);
-
-			// Now a section of fence, +X, if there's a post there
-			v3s16 p2 = p;
-			p2.X++;
-			MapNode n2 = data->m_vmanip.getNodeNoEx(blockpos_nodes + p2);
-			if(n2.d == CONTENT_FENCE)
-			{
-				pos = intToFloat(p+blockpos_nodes, BS);
-				pos.X += BS/2;
-				pos.Y += 3*bar_rad;
-				makeCuboid(material_wood, &collector,
-					&pa_wood, c, pos,
-					bar_len,bar_rad,bar_rad);
-
-				pos.Y -= 6*bar_rad;
-				makeCuboid(material_wood, &collector,
-					&pa_wood, c, pos,
-					bar_len,bar_rad,bar_rad);
-			}
-
-			// Now a section of fence, +Z, if there's a post there
-			p2 = p;
-			p2.Z++;
-			n2 = data->m_vmanip.getNodeNoEx(blockpos_nodes + p2);
-			if(n2.d == CONTENT_FENCE)
-			{
-				pos = intToFloat(p+blockpos_nodes, BS);
-				pos.Z += BS/2;
-				pos.Y += 3*bar_rad;
-				makeCuboid(material_wood, &collector,
-					&pa_wood, c, pos,
-					bar_rad,bar_rad,bar_len);
-				pos.Y -= 6*bar_rad;
-				makeCuboid(material_wood, &collector,
-					&pa_wood, c, pos,
-					bar_rad,bar_rad,bar_len);
-
-			}
-
-		}
-		else if(n.d == CONTENT_PAPYRUS)
-		{
-			u8 l = decode_light(undiminish_light(n.getLightBlend(data->m_daynight_ratio)));
-			video::SColor c(255,l,l,l);
-
-			for(u32 j=0; j<4; j++)
-			{
-				video::S3DVertex vertices[4] =
-				{
-					video::S3DVertex(-BS/2,-BS/2,0, 0,0,0, c,
-						pa_papyrus.x0(), pa_papyrus.y1()),
-					video::S3DVertex(BS/2,-BS/2,0, 0,0,0, c,
-						pa_papyrus.x1(), pa_papyrus.y1()),
-					video::S3DVertex(BS/2,BS/2,0, 0,0,0, c,
-						pa_papyrus.x1(), pa_papyrus.y0()),
-					video::S3DVertex(-BS/2,BS/2,0, 0,0,0, c,
-						pa_papyrus.x0(), pa_papyrus.y0()),
-				};
-
-				if(j == 0)
-				{
-					for(u16 i=0; i<4; i++)
-						vertices[i].Pos.rotateXZBy(45);
-				}
-				else if(j == 1)
-				{
-					for(u16 i=0; i<4; i++)
-						vertices[i].Pos.rotateXZBy(-45);
-				}
-				else if(j == 2)
-				{
-					for(u16 i=0; i<4; i++)
-						vertices[i].Pos.rotateXZBy(135);
-				}
-				else if(j == 3)
-				{
-					for(u16 i=0; i<4; i++)
-						vertices[i].Pos.rotateXZBy(-135);
-				}
-
-				for(u16 i=0; i<4; i++)
-				{
-					vertices[i].Pos += intToFloat(p + blockpos_nodes, BS);
-				}
-
-				u16 indices[] = {0,1,2,2,3,0};
-				// Add to mesh collector
-				collector.append(material_papyrus, vertices, 4, indices, 6);
-			}
-		}
-		else if(n.d == CONTENT_RAIL)
-		{
-			u8 l = decode_light(n.getLightBlend(data->m_daynight_ratio));
-			video::SColor c(255,l,l,l);
-
-			bool is_rail_x [] = { false, false };  /* x-1, x+1 */
-			bool is_rail_z [] = { false, false };  /* z-1, z+1 */
-
-			MapNode n_minus_x = data->m_vmanip.getNodeNoEx(blockpos_nodes + v3s16(x-1,y,z));
-			MapNode n_plus_x = data->m_vmanip.getNodeNoEx(blockpos_nodes + v3s16(x+1,y,z));
-			MapNode n_minus_z = data->m_vmanip.getNodeNoEx(blockpos_nodes + v3s16(x,y,z-1));
-			MapNode n_plus_z = data->m_vmanip.getNodeNoEx(blockpos_nodes + v3s16(x,y,z+1));
-
-			if(n_minus_x.d == CONTENT_RAIL)
-				is_rail_x[0] = true;
-			if(n_plus_x.d == CONTENT_RAIL)
-				is_rail_x[1] = true;
-			if(n_minus_z.d == CONTENT_RAIL)
-				is_rail_z[0] = true;
-			if(n_plus_z.d == CONTENT_RAIL)
-				is_rail_z[1] = true;
-
-			float d = (float)BS/16;
-			video::S3DVertex vertices[4] =
-			{
-				video::S3DVertex(-BS/2,-BS/2+d,-BS/2, 0,0,0, c,
-					0, 1),
-				video::S3DVertex(BS/2,-BS/2+d,-BS/2, 0,0,0, c,
-					1, 1),
-				video::S3DVertex(BS/2,-BS/2+d,BS/2, 0,0,0, c,
-					1, 0),
-				video::S3DVertex(-BS/2,-BS/2+d,BS/2, 0,0,0, c,
-					0, 0),
-			};
-
-			video::SMaterial material_rail;
-			material_rail.setFlag(video::EMF_LIGHTING, false);
-			material_rail.setFlag(video::EMF_BACK_FACE_CULLING, false);
-			material_rail.setFlag(video::EMF_BILINEAR_FILTER, false);
-			material_rail.setFlag(video::EMF_FOG_ENABLE, true);
-			material_rail.MaterialType
-					= video::EMT_TRANSPARENT_ALPHA_CHANNEL_REF;
-
-			int adjacencies = is_rail_x[0] + is_rail_x[1] + is_rail_z[0] + is_rail_z[1];
-
-			// Assign textures
-			if(adjacencies < 2)
-				material_rail.setTexture(0, g_texturesource->getTextureRaw("rail.png"));
-			else if(adjacencies == 2)
-			{
-				if((is_rail_x[0] && is_rail_x[1]) || (is_rail_z[0] && is_rail_z[1]))
-					material_rail.setTexture(0, g_texturesource->getTextureRaw("rail.png"));
-				else
-					material_rail.setTexture(0, g_texturesource->getTextureRaw("rail_curved.png"));
-			}
-			else if(adjacencies == 3)
-				material_rail.setTexture(0, g_texturesource->getTextureRaw("rail_t_junction.png"));
-			else if(adjacencies == 4)
-				material_rail.setTexture(0, g_texturesource->getTextureRaw("rail_crossing.png"));
-
-			// Rotate textures
-			int angle = 0;
-
-			if(adjacencies == 1)
-			{
-				if(is_rail_x[0] || is_rail_x[1])
-					angle = 90;
-			}
-			else if(adjacencies == 2)
-			{
-				if(is_rail_x[0] && is_rail_x[1])
-					angle = 90;
-				else if(is_rail_x[0] && is_rail_z[0])
-					angle = 270;
-				else if(is_rail_x[0] && is_rail_z[1])
-					angle = 180;
-				else if(is_rail_x[1] && is_rail_z[1])
-					angle = 90;
-			}
-			else if(adjacencies == 3)
-			{
-				if(!is_rail_x[0])
-					angle=0;
-				if(!is_rail_x[1])
-					angle=180;
-				if(!is_rail_z[0])
-					angle=90;
-				if(!is_rail_z[1])
-					angle=270;
-			}
-
-			if(angle != 0) {
-				for(u16 i=0; i<4; i++)
-					vertices[i].Pos.rotateXZBy(angle);
-			}
-
-			for(s32 i=0; i<4; i++)
-			{
-				vertices[i].Pos += intToFloat(p + blockpos_nodes, BS);
-			}
-
-			u16 indices[] = {0,1,2,2,3,0};
-			collector.append(material_rail, vertices, 4, indices, 6);
-		}
-
-	}
-
-	/*
-		Add stuff from collector to mesh
-	*/
-	
-	scene::SMesh *mesh_new = NULL;
-	mesh_new = new scene::SMesh();
-	
-	collector.fillMesh(mesh_new);
-
-	/*
-		Do some stuff to the mesh
-	*/
-
-	mesh_new->recalculateBoundingBox();
-
-	/*
-		Delete new mesh if it is empty
-	*/
-
-	if(mesh_new->getMeshBufferCount() == 0)
-	{
-		mesh_new->drop();
-		mesh_new = NULL;
-	}
-
-	if(mesh_new)
-	{
-#if 0
-		// Usually 1-700 faces and 1-7 materials
-		std::cout<<"Updated MapBlock has "<<fastfaces_new.size()<<" faces "
-				<<"and uses "<<mesh_new->getMeshBufferCount()
-				<<" materials (meshbuffers)"<<std::endl;
-#endif
-
-		// Use VBO for mesh (this just would set this for ever buffer)
-		// This will lead to infinite memory usage because or irrlicht.
-		//mesh_new->setHardwareMappingHint(scene::EHM_STATIC);
-
-		/*
-			NOTE: If that is enabled, some kind of a queue to the main
-			thread should be made which would call irrlicht to delete
-			the hardware buffer and then delete the mesh
-		*/
-	}
-
-	return mesh_new;
-	
-	//std::cout<<"added "<<fastfaces.getSize()<<" faces."<<std::endl;
-}
-
-#endif // !SERVER
-
 /*
 	MapBlock
 */
@@ -1838,13 +31,14 @@ scene::SMesh* makeMapBlockMesh(MeshMakeData *data)
 MapBlock::MapBlock(NodeContainer *parent, v3s16 pos, bool dummy):
 		m_parent(parent),
 		m_pos(pos),
-		changed(true),
+		m_modified(MOD_STATE_WRITE_NEEDED),
 		is_underground(false),
 		m_lighting_expired(true),
 		m_day_night_differs(false),
-		//m_not_fully_generated(false),
+		m_generated(false),
 		m_objects(this),
-		m_timestamp(BLOCK_TIMESTAMP_UNDEFINED)
+		m_timestamp(BLOCK_TIMESTAMP_UNDEFINED),
+		m_usage_timer(BLOCK_TIMESTAMP_UNDEFINED)
 {
 	data = NULL;
 	if(dummy == false)
@@ -2025,16 +219,13 @@ void MapBlock::replaceMesh(scene::SMesh *mesh_new)
 
 	All sunlighted nodes are added to light_sources.
 
-	If grow_grass==true, turns sunglighted mud into grass.
-
 	if remove_light==true, sets non-sunlighted nodes black.
 
 	if black_air_left!=NULL, it is set to true if non-sunlighted
 	air is left in block.
 */
 bool MapBlock::propagateSunlight(core::map<v3s16, bool> & light_sources,
-		bool remove_light, bool *black_air_left,
-		bool grow_grass)
+		bool remove_light, bool *black_air_left)
 {
 	// Whether the sunlight at the top of the bottom block is valid
 	bool block_below_is_valid = true;
@@ -2051,7 +242,7 @@ bool MapBlock::propagateSunlight(core::map<v3s16, bool> & light_sources,
 			// Check if node above block has sunlight
 			try{
 				MapNode n = getNodeParent(v3s16(x, MAP_BLOCKSIZE, z));
-				if(n.getLight(LIGHTBANK_DAY) != LIGHT_SUN)
+				if(n.d == CONTENT_IGNORE || n.getLight(LIGHTBANK_DAY) != LIGHT_SUN)
 				{
 					no_sunlight = true;
 				}
@@ -2069,7 +260,8 @@ bool MapBlock::propagateSunlight(core::map<v3s16, bool> & light_sources,
 				else
 				{
 					MapNode n = getNode(v3s16(x, MAP_BLOCKSIZE-1, z));
-					if(n.d == CONTENT_WATER || n.d == CONTENT_WATERSOURCE)
+					//if(n.d == CONTENT_WATER || n.d == CONTENT_WATERSOURCE)
+					if(content_features(n.d).sunlight_propagates == false)
 					{
 						no_sunlight = true;
 					}
@@ -2124,6 +316,7 @@ bool MapBlock::propagateSunlight(core::map<v3s16, bool> & light_sources,
 				}
 				else if(n.light_propagates() == false)
 				{
+					/*// DEPRECATED TODO: REMOVE
 					if(grow_grass)
 					{
 						bool upper_is_air = false;
@@ -2141,7 +334,7 @@ bool MapBlock::propagateSunlight(core::map<v3s16, bool> & light_sources,
 						{
 							n.d = CONTENT_GRASS;
 						}
-					}
+					}*/
 
 					// A solid object is on the way.
 					stopped_to_solid_object = true;
@@ -2401,6 +594,11 @@ void MapBlock::serialize(std::ostream &os, u8 version)
 			flags |= 0x02;
 		if(m_lighting_expired)
 			flags |= 0x04;
+		if(version >= 18)
+		{
+			if(m_generated == false)
+				flags |= 0x08;
+		}
 		os.write((char*)&flags, 1);
 
 		u32 nodecount = MAP_BLOCKSIZE*MAP_BLOCKSIZE*MAP_BLOCKSIZE;
@@ -2476,6 +674,12 @@ void MapBlock::deSerialize(std::istream &is, u8 version)
 		setLightingExpired(true);
 	}
 
+	// These have no "generated" field
+	if(version < 18)
+	{
+		m_generated = true;
+	}
+
 	// These have no compression
 	if(version <= 3 || version == 5 || version == 6)
 	{
@@ -2557,6 +761,8 @@ void MapBlock::deSerialize(std::istream &is, u8 version)
 		is_underground = (flags & 0x01) ? true : false;
 		m_day_night_differs = (flags & 0x02) ? true : false;
 		m_lighting_expired = (flags & 0x04) ? true : false;
+		if(version >= 18)
+			m_generated = (flags & 0x08) ? false : true;
 
 		// Uncompress data
 		std::ostringstream os(std::ios_base::binary);
@@ -2564,7 +770,8 @@ void MapBlock::deSerialize(std::istream &is, u8 version)
 		std::string s = os.str();
 		if(s.size() != nodecount*3)
 			throw SerializationError
-					("MapBlock::deSerialize: invalid format");
+					("MapBlock::deSerialize: decompress resulted in size"
+					" other than nodecount*3");
 
 		// Set contents
 		for(u32 i=0; i<nodecount; i++)
@@ -2637,7 +844,9 @@ void MapBlock::serializeDiskExtra(std::ostream &os, u8 version)
 	// Versions up from 9 have block objects.
 	if(version >= 9)
 	{
-		serializeObjects(os, version);
+		//serializeObjects(os, version); // DEPRECATED
+		// count=0
+		writeU16(os, 0);
 	}
 	
 	// Versions up from 15 have static objects.
diff --git a/src/mapblock.h b/src/mapblock.h
index 1eb97353c..693bc5190 100644
--- a/src/mapblock.h
+++ b/src/mapblock.h
@@ -33,10 +33,15 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "voxel.h"
 #include "nodemetadata.h"
 #include "staticobject.h"
+#include "mapblock_nodemod.h"
+#ifndef SERVER
+	#include "mapblock_mesh.h"
+#endif
+
 
 #define BLOCK_TIMESTAMP_UNDEFINED 0xffffffff
 
-// Named by looking towards z+
+/*// Named by looking towards z+
 enum{
 	FACE_BACK=0,
 	FACE_TOP,
@@ -44,103 +49,37 @@ enum{
 	FACE_FRONT,
 	FACE_BOTTOM,
 	FACE_LEFT
-};
-
-struct FastFace
-{
-	TileSpec tile;
-	video::S3DVertex vertices[4]; // Precalculated vertices
-};
-
-enum NodeModType
-{
-	NODEMOD_NONE,
-	NODEMOD_CHANGECONTENT, //param is content id
-	NODEMOD_CRACK // param is crack progression
-};
+};*/
 
-struct NodeMod
+enum ModifiedState
 {
-	NodeMod(enum NodeModType a_type=NODEMOD_NONE, u16 a_param=0)
-	{
-		type = a_type;
-		param = a_param;
-	}
-	bool operator==(const NodeMod &other)
-	{
-		return (type == other.type && param == other.param);
-	}
-	enum NodeModType type;
-	u16 param;
+	// Has not been modified.
+	MOD_STATE_CLEAN = 0,
+	MOD_RESERVED1 = 1,
+	// Has been modified, and will be saved when being unloaded.
+	MOD_STATE_WRITE_AT_UNLOAD = 2,
+	MOD_RESERVED3 = 3,
+	// Has been modified, and will be saved as soon as possible.
+	MOD_STATE_WRITE_NEEDED = 4,
+	MOD_RESERVED5 = 5,
 };
 
-class NodeModMap
+// NOTE: If this is enabled, set MapBlock to be initialized with
+//       CONTENT_IGNORE.
+/*enum BlockGenerationStatus
 {
-public:
-	/*
-		returns true if the mod was different last time
-	*/
-	bool set(v3s16 p, const NodeMod &mod)
-	{
-		// See if old is different, cancel if it is not different.
-		core::map<v3s16, NodeMod>::Node *n = m_mods.find(p);
-		if(n)
-		{
-			NodeMod old = n->getValue();
-			if(old == mod)
-				return false;
-
-			n->setValue(mod);
-		}
-		else
-		{
-			m_mods.insert(p, mod);
-		}
-		
-		return true;
-	}
-	// Returns true if there was one
-	bool get(v3s16 p, NodeMod *mod)
-	{
-		core::map<v3s16, NodeMod>::Node *n;
-		n = m_mods.find(p);
-		if(n == NULL)
-			return false;
-		if(mod)
-			*mod = n->getValue();
-		return true;
-	}
-	bool clear(v3s16 p)
-	{
-		if(m_mods.find(p))
-		{
-			m_mods.remove(p);
-			return true;
-		}
-		return false;
-	}
-	bool clear()
-	{
-		if(m_mods.size() == 0)
-			return false;
-		m_mods.clear();
-		return true;
-	}
-	void copy(NodeModMap &dest)
-	{
-		dest.m_mods.clear();
-
-		for(core::map<v3s16, NodeMod>::Iterator
-				i = m_mods.getIterator();
-				i.atEnd() == false; i++)
-		{
-			dest.m_mods.insert(i.getNode()->getKey(), i.getNode()->getValue());
-		}
-	}
-
-private:
-	core::map<v3s16, NodeMod> m_mods;
-};
+	// Completely non-generated (filled with CONTENT_IGNORE).
+	BLOCKGEN_UNTOUCHED=0,
+	// Trees or similar might have been blitted from other blocks to here.
+	// Otherwise, the block contains CONTENT_IGNORE
+	BLOCKGEN_FROM_NEIGHBORS=2,
+	// Has been generated, but some neighbors might put some stuff in here
+	// when they are generated.
+	// Does not contain any CONTENT_IGNORE
+	BLOCKGEN_SELF_GENERATED=4,
+	// The block and all its neighbors have been generated
+	BLOCKGEN_FULLY_GENERATED=6
+};*/
 
 enum
 {
@@ -171,35 +110,6 @@ public:
 };
 
 /*
-	Mesh making stuff
-*/
-
-class MapBlock;
-
-#ifndef SERVER
-
-struct MeshMakeData
-{
-	u32 m_daynight_ratio;
-	NodeModMap m_temp_mods;
-	VoxelManipulator m_vmanip;
-	v3s16 m_blockpos;
-	
-	/*
-		Copy central data directly from block, and other data from
-		parent of block.
-	*/
-	void fill(u32 daynight_ratio, MapBlock *block);
-};
-
-scene::SMesh* makeMapBlockMesh(MeshMakeData *data);
-
-#endif
-
-u8 getFaceLight(u32 daynight_ratio, MapNode n, MapNode n2,
-		v3s16 face_dir);
-
-/*
 	MapBlock itself
 */
 
@@ -226,9 +136,10 @@ public:
 		u32 l = MAP_BLOCKSIZE * MAP_BLOCKSIZE * MAP_BLOCKSIZE;
 		data = new MapNode[l];
 		for(u32 i=0; i<l; i++){
-			data[i] = MapNode();
+			//data[i] = MapNode();
+			data[i] = MapNode(CONTENT_IGNORE);
 		}
-		setChangedFlag();
+		raiseModified(MOD_STATE_WRITE_NEEDED);
 	}
 
 	/*
@@ -250,19 +161,43 @@ public:
 		modified, so that the block is saved and possibly not deleted from
 		memory.
 	*/
+	// DEPRECATED, use *Modified()
 	void setChangedFlag()
 	{
-		changed = true;
+		//dstream<<"Deprecated setChangedFlag() called"<<std::endl;
+		raiseModified(MOD_STATE_WRITE_NEEDED);
 	}
+	// DEPRECATED, use *Modified()
 	void resetChangedFlag()
 	{
-		changed = false;
+		//dstream<<"Deprecated resetChangedFlag() called"<<std::endl;
+		resetModified();
 	}
+	// DEPRECATED, use *Modified()
 	bool getChangedFlag()
 	{
-		return changed;
+		//dstream<<"Deprecated getChangedFlag() called"<<std::endl;
+		if(getModified() == MOD_STATE_CLEAN)
+			return false;
+		else
+			return true;
+	}
+	
+	// m_modified methods
+	void raiseModified(u32 mod)
+	{
+		m_modified = MYMAX(m_modified, mod);
 	}
-
+	u32 getModified()
+	{
+		return m_modified;
+	}
+	void resetModified()
+	{
+		m_modified = MOD_STATE_CLEAN;
+	}
+	
+	// is_underground getter/setter
 	bool getIsUnderground()
 	{
 		return is_underground;
@@ -270,7 +205,7 @@ public:
 	void setIsUnderground(bool a_is_underground)
 	{
 		is_underground = a_is_underground;
-		setChangedFlag();
+		raiseModified(MOD_STATE_WRITE_NEEDED);
 	}
 
 #ifndef SERVER
@@ -288,22 +223,22 @@ public:
 	void setLightingExpired(bool expired)
 	{
 		m_lighting_expired = expired;
-		setChangedFlag();
+		raiseModified(MOD_STATE_WRITE_NEEDED);
 	}
 	bool getLightingExpired()
 	{
 		return m_lighting_expired;
 	}
 
-	/*bool isFullyGenerated()
+	bool isGenerated()
 	{
-		return !m_not_fully_generated;
+		return m_generated;
 	}
-	void setFullyGenerated(bool b)
+	void setGenerated(bool b)
 	{
-		setChangedFlag();
-		m_not_fully_generated = !b;
-	}*/
+		raiseModified(MOD_STATE_WRITE_NEEDED);
+		m_generated = b;
+	}
 
 	bool isValid()
 	{
@@ -381,7 +316,7 @@ public:
 		if(y < 0 || y >= MAP_BLOCKSIZE) throw InvalidPositionException();
 		if(z < 0 || z >= MAP_BLOCKSIZE) throw InvalidPositionException();
 		data[z*MAP_BLOCKSIZE*MAP_BLOCKSIZE + y*MAP_BLOCKSIZE + x] = n;
-		setChangedFlag();
+		raiseModified(MOD_STATE_WRITE_NEEDED);
 	}
 	
 	void setNode(v3s16 p, MapNode & n)
@@ -410,7 +345,7 @@ public:
 		if(data == NULL)
 			throw InvalidPositionException();
 		data[z*MAP_BLOCKSIZE*MAP_BLOCKSIZE + y*MAP_BLOCKSIZE + x] = n;
-		setChangedFlag();
+		raiseModified(MOD_STATE_WRITE_NEEDED);
 	}
 	
 	void setNodeNoCheck(v3s16 p, MapNode & n)
@@ -474,8 +409,7 @@ public:
 	
 	// See comments in mapblock.cpp
 	bool propagateSunlight(core::map<v3s16, bool> & light_sources,
-			bool remove_light=false, bool *black_air_left=NULL,
-			bool grow_grass=false);
+			bool remove_light=false, bool *black_air_left=NULL);
 	
 	// Copies data to VoxelManipulator to getPosRelative()
 	void copyTo(VoxelManipulator &dst);
@@ -487,36 +421,36 @@ public:
 		DEPRECATED
 	*/
 	
-	void serializeObjects(std::ostream &os, u8 version)
+	/*void serializeObjects(std::ostream &os, u8 version)
 	{
 		m_objects.serialize(os, version);
-	}
+	}*/
 	// If smgr!=NULL, new objects are added to the scene
 	void updateObjects(std::istream &is, u8 version,
 			scene::ISceneManager *smgr, u32 daynight_ratio)
 	{
 		m_objects.update(is, version, smgr, daynight_ratio);
 
-		setChangedFlag();
+		raiseModified(MOD_STATE_WRITE_NEEDED);
 	}
 	void clearObjects()
 	{
 		m_objects.clear();
 
-		setChangedFlag();
+		raiseModified(MOD_STATE_WRITE_NEEDED);
 	}
 	void addObject(MapBlockObject *object)
 			throw(ContainerFullException, AlreadyExistsException)
 	{
 		m_objects.add(object);
 
-		setChangedFlag();
+		raiseModified(MOD_STATE_WRITE_NEEDED);
 	}
 	void removeObject(s16 id)
 	{
 		m_objects.remove(id);
 
-		setChangedFlag();
+		raiseModified(MOD_STATE_WRITE_NEEDED);
 	}
 	MapBlockObject * getObject(s16 id)
 	{
@@ -626,12 +560,32 @@ public:
 	void setTimestamp(u32 time)
 	{
 		m_timestamp = time;
-		setChangedFlag();
+		raiseModified(MOD_STATE_WRITE_AT_UNLOAD);
+	}
+	void setTimestampNoChangedFlag(u32 time)
+	{
+		m_timestamp = time;
 	}
 	u32 getTimestamp()
 	{
 		return m_timestamp;
 	}
+	
+	/*
+		See m_usage_timer
+	*/
+	void resetUsageTimer()
+	{
+		m_usage_timer = 0;
+	}
+	void incrementUsageTimer(float dtime)
+	{
+		m_usage_timer += dtime;
+	}
+	u32 getUsageTimer()
+	{
+		return m_usage_timer;
+	}
 
 	/*
 		Serialization
@@ -698,10 +652,10 @@ private:
 
 	/*
 		- On the server, this is used for telling whether the
-		  block has been changed from the one on disk.
+		  block has been modified from the one on disk.
 		- On the client, this is used for nothing.
 	*/
-	bool changed;
+	u32 m_modified;
 
 	/*
 		When propagating sunlight and the above block doesn't exist,
@@ -724,6 +678,8 @@ private:
 	
 	// Whether day and night lighting differs
 	bool m_day_night_differs;
+
+	bool m_generated;
 	
 	// DEPRECATED
 	MapBlockObjectList m_objects;
@@ -747,6 +703,12 @@ private:
 		Value BLOCK_TIMESTAMP_UNDEFINED=0xffffffff means there is no timestamp.
 	*/
 	u32 m_timestamp;
+
+	/*
+		When the block is accessed, this is set to 0.
+		Map will unload the block when this reaches a timeout.
+	*/
+	float m_usage_timer;
 };
 
 inline bool blockpos_over_limit(v3s16 p)
diff --git a/src/mapblock_mesh.cpp b/src/mapblock_mesh.cpp
new file mode 100644
index 000000000..d4921c2c5
--- /dev/null
+++ b/src/mapblock_mesh.cpp
@@ -0,0 +1,791 @@
+/*
+Minetest-c55
+Copyright (C) 2010-2011 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "mapblock_mesh.h"
+#include "light.h"
+#include "mapblock.h"
+#include "map.h"
+#include "main.h" // For g_settings and g_texturesource
+#include "content_mapblock.h"
+
+void MeshMakeData::fill(u32 daynight_ratio, MapBlock *block)
+{
+	m_daynight_ratio = daynight_ratio;
+	m_blockpos = block->getPos();
+
+	v3s16 blockpos_nodes = m_blockpos*MAP_BLOCKSIZE;
+	
+	/*
+		There is no harm not copying the TempMods of the neighbors
+		because they are already copied to this block
+	*/
+	m_temp_mods.clear();
+	block->copyTempMods(m_temp_mods);
+	
+	/*
+		Copy data
+	*/
+
+	// Allocate this block + neighbors
+	m_vmanip.clear();
+	m_vmanip.addArea(VoxelArea(blockpos_nodes-v3s16(1,1,1)*MAP_BLOCKSIZE,
+			blockpos_nodes+v3s16(1,1,1)*MAP_BLOCKSIZE*2-v3s16(1,1,1)));
+
+	{
+		//TimeTaker timer("copy central block data");
+		// 0ms
+
+		// Copy our data
+		block->copyTo(m_vmanip);
+	}
+	{
+		//TimeTaker timer("copy neighbor block data");
+		// 0ms
+
+		/*
+			Copy neighbors. This is lightning fast.
+			Copying only the borders would be *very* slow.
+		*/
+		
+		// Get map
+		NodeContainer *parentcontainer = block->getParent();
+		// This will only work if the parent is the map
+		assert(parentcontainer->nodeContainerId() == NODECONTAINER_ID_MAP);
+		// OK, we have the map!
+		Map *map = (Map*)parentcontainer;
+
+		for(u16 i=0; i<6; i++)
+		{
+			const v3s16 &dir = g_6dirs[i];
+			v3s16 bp = m_blockpos + dir;
+			MapBlock *b = map->getBlockNoCreateNoEx(bp);
+			if(b)
+				b->copyTo(m_vmanip);
+		}
+	}
+}
+
+/*
+	vertex_dirs: v3s16[4]
+*/
+void getNodeVertexDirs(v3s16 dir, v3s16 *vertex_dirs)
+{
+	/*
+		If looked from outside the node towards the face, the corners are:
+		0: bottom-right
+		1: bottom-left
+		2: top-left
+		3: top-right
+	*/
+	if(dir == v3s16(0,0,1))
+	{
+		// If looking towards z+, this is the face that is behind
+		// the center point, facing towards z+.
+		vertex_dirs[0] = v3s16(-1,-1, 1);
+		vertex_dirs[1] = v3s16( 1,-1, 1);
+		vertex_dirs[2] = v3s16( 1, 1, 1);
+		vertex_dirs[3] = v3s16(-1, 1, 1);
+	}
+	else if(dir == v3s16(0,0,-1))
+	{
+		// faces towards Z-
+		vertex_dirs[0] = v3s16( 1,-1,-1);
+		vertex_dirs[1] = v3s16(-1,-1,-1);
+		vertex_dirs[2] = v3s16(-1, 1,-1);
+		vertex_dirs[3] = v3s16( 1, 1,-1);
+	}
+	else if(dir == v3s16(1,0,0))
+	{
+		// faces towards X+
+		vertex_dirs[0] = v3s16( 1,-1, 1);
+		vertex_dirs[1] = v3s16( 1,-1,-1);
+		vertex_dirs[2] = v3s16( 1, 1,-1);
+		vertex_dirs[3] = v3s16( 1, 1, 1);
+	}
+	else if(dir == v3s16(-1,0,0))
+	{
+		// faces towards X-
+		vertex_dirs[0] = v3s16(-1,-1,-1);
+		vertex_dirs[1] = v3s16(-1,-1, 1);
+		vertex_dirs[2] = v3s16(-1, 1, 1);
+		vertex_dirs[3] = v3s16(-1, 1,-1);
+	}
+	else if(dir == v3s16(0,1,0))
+	{
+		// faces towards Y+ (assume Z- as "down" in texture)
+		vertex_dirs[0] = v3s16( 1, 1,-1);
+		vertex_dirs[1] = v3s16(-1, 1,-1);
+		vertex_dirs[2] = v3s16(-1, 1, 1);
+		vertex_dirs[3] = v3s16( 1, 1, 1);
+	}
+	else if(dir == v3s16(0,-1,0))
+	{
+		// faces towards Y- (assume Z+ as "down" in texture)
+		vertex_dirs[0] = v3s16( 1,-1, 1);
+		vertex_dirs[1] = v3s16(-1,-1, 1);
+		vertex_dirs[2] = v3s16(-1,-1,-1);
+		vertex_dirs[3] = v3s16( 1,-1,-1);
+	}
+}
+
+inline video::SColor lightColor(u8 alpha, u8 light)
+{
+	return video::SColor(alpha,light,light,light);
+}
+
+struct FastFace
+{
+	TileSpec tile;
+	video::S3DVertex vertices[4]; // Precalculated vertices
+};
+
+void makeFastFace(TileSpec tile, u8 li0, u8 li1, u8 li2, u8 li3, v3f p,
+		v3s16 dir, v3f scale, v3f posRelative_f,
+		core::array<FastFace> &dest)
+{
+	FastFace face;
+	
+	// Position is at the center of the cube.
+	v3f pos = p * BS;
+	posRelative_f *= BS;
+
+	v3f vertex_pos[4];
+	v3s16 vertex_dirs[4];
+	getNodeVertexDirs(dir, vertex_dirs);
+	for(u16 i=0; i<4; i++)
+	{
+		vertex_pos[i] = v3f(
+				BS/2*vertex_dirs[i].X,
+				BS/2*vertex_dirs[i].Y,
+				BS/2*vertex_dirs[i].Z
+		);
+	}
+
+	for(u16 i=0; i<4; i++)
+	{
+		vertex_pos[i].X *= scale.X;
+		vertex_pos[i].Y *= scale.Y;
+		vertex_pos[i].Z *= scale.Z;
+		vertex_pos[i] += pos + posRelative_f;
+	}
+
+	f32 abs_scale = 1.;
+	if     (scale.X < 0.999 || scale.X > 1.001) abs_scale = scale.X;
+	else if(scale.Y < 0.999 || scale.Y > 1.001) abs_scale = scale.Y;
+	else if(scale.Z < 0.999 || scale.Z > 1.001) abs_scale = scale.Z;
+
+	v3f zerovector = v3f(0,0,0);
+	
+	u8 alpha = tile.alpha;
+	/*u8 alpha = 255;
+	if(tile.id == TILE_WATER)
+		alpha = WATER_ALPHA;*/
+
+	float x0 = tile.texture.pos.X;
+	float y0 = tile.texture.pos.Y;
+	float w = tile.texture.size.X;
+	float h = tile.texture.size.Y;
+
+	/*video::SColor c = lightColor(alpha, li);
+
+	face.vertices[0] = video::S3DVertex(vertex_pos[0], v3f(0,1,0), c,
+			core::vector2d<f32>(x0+w*abs_scale, y0+h));
+	face.vertices[1] = video::S3DVertex(vertex_pos[1], v3f(0,1,0), c,
+			core::vector2d<f32>(x0, y0+h));
+	face.vertices[2] = video::S3DVertex(vertex_pos[2], v3f(0,1,0), c,
+			core::vector2d<f32>(x0, y0));
+	face.vertices[3] = video::S3DVertex(vertex_pos[3], v3f(0,1,0), c,
+			core::vector2d<f32>(x0+w*abs_scale, y0));*/
+
+	face.vertices[0] = video::S3DVertex(vertex_pos[0], v3f(0,1,0),
+			lightColor(alpha, li0),
+			core::vector2d<f32>(x0+w*abs_scale, y0+h));
+	face.vertices[1] = video::S3DVertex(vertex_pos[1], v3f(0,1,0),
+			lightColor(alpha, li1),
+			core::vector2d<f32>(x0, y0+h));
+	face.vertices[2] = video::S3DVertex(vertex_pos[2], v3f(0,1,0),
+			lightColor(alpha, li2),
+			core::vector2d<f32>(x0, y0));
+	face.vertices[3] = video::S3DVertex(vertex_pos[3], v3f(0,1,0),
+			lightColor(alpha, li3),
+			core::vector2d<f32>(x0+w*abs_scale, y0));
+
+	face.tile = tile;
+	//DEBUG
+	//f->tile = TILE_STONE;
+	
+	dest.push_back(face);
+}
+	
+/*
+	Gets node tile from any place relative to block.
+	Returns TILE_NODE if doesn't exist or should not be drawn.
+*/
+TileSpec getNodeTile(MapNode mn, v3s16 p, v3s16 face_dir,
+		NodeModMap &temp_mods)
+{
+	TileSpec spec;
+	spec = mn.getTile(face_dir);
+	
+	/*
+		Check temporary modifications on this node
+	*/
+	/*core::map<v3s16, NodeMod>::Node *n;
+	n = m_temp_mods.find(p);
+	// If modified
+	if(n != NULL)
+	{
+		struct NodeMod mod = n->getValue();*/
+	NodeMod mod;
+	if(temp_mods.get(p, &mod))
+	{
+		if(mod.type == NODEMOD_CHANGECONTENT)
+		{
+			MapNode mn2(mod.param);
+			spec = mn2.getTile(face_dir);
+		}
+		if(mod.type == NODEMOD_CRACK)
+		{
+			/*
+				Get texture id, translate it to name, append stuff to
+				name, get texture id
+			*/
+
+			// Get original texture name
+			u32 orig_id = spec.texture.id;
+			std::string orig_name = g_texturesource->getTextureName(orig_id);
+
+			// Create new texture name
+			std::ostringstream os;
+			os<<orig_name<<"^[crack"<<mod.param;
+
+			// Get new texture
+			u32 new_id = g_texturesource->getTextureId(os.str());
+			
+			/*dstream<<"MapBlock::getNodeTile(): Switching from "
+					<<orig_name<<" to "<<os.str()<<" ("
+					<<orig_id<<" to "<<new_id<<")"<<std::endl;*/
+			
+			spec.texture = g_texturesource->getTexture(new_id);
+		}
+	}
+	
+	return spec;
+}
+
+u8 getNodeContent(v3s16 p, MapNode mn, NodeModMap &temp_mods)
+{
+	/*
+		Check temporary modifications on this node
+	*/
+	/*core::map<v3s16, NodeMod>::Node *n;
+	n = m_temp_mods.find(p);
+	// If modified
+	if(n != NULL)
+	{
+		struct NodeMod mod = n->getValue();*/
+	NodeMod mod;
+	if(temp_mods.get(p, &mod))
+	{
+		if(mod.type == NODEMOD_CHANGECONTENT)
+		{
+			// Overrides content
+			return mod.param;
+		}
+		if(mod.type == NODEMOD_CRACK)
+		{
+			/*
+				Content doesn't change.
+				
+				face_contents works just like it should, because
+				there should not be faces between differently cracked
+				nodes.
+
+				If a semi-transparent node is cracked in front an
+				another one, it really doesn't matter whether there
+				is a cracked face drawn in between or not.
+			*/
+		}
+	}
+
+	return mn.d;
+}
+
+v3s16 dirs8[8] = {
+	v3s16(0,0,0),
+	v3s16(0,0,1),
+	v3s16(0,1,0),
+	v3s16(0,1,1),
+	v3s16(1,0,0),
+	v3s16(1,1,0),
+	v3s16(1,0,1),
+	v3s16(1,1,1),
+};
+
+// Calculate lighting at the XYZ- corner of p
+u8 getSmoothLight(v3s16 p, VoxelManipulator &vmanip, u32 daynight_ratio)
+{
+	u16 ambient_occlusion = 0;
+	u16 light = 0;
+	u16 light_count = 0;
+	for(u32 i=0; i<8; i++)
+	{
+		MapNode n = vmanip.getNodeNoEx(p - dirs8[i]);
+		if(content_features(n.d).param_type == CPT_LIGHT
+				// Fast-style leaves look better this way
+				&& content_features(n.d).solidness != 2)
+		{
+			light += decode_light(n.getLightBlend(daynight_ratio));
+			light_count++;
+		}
+		else
+		{
+			if(n.d != CONTENT_IGNORE)
+				ambient_occlusion++;
+		}
+	}
+
+	if(light_count == 0)
+		return 255;
+	
+	light /= light_count;
+
+	if(ambient_occlusion > 4)
+	{
+		ambient_occlusion -= 4;
+		light = (float)light / ((float)ambient_occlusion * 0.5 + 1.0);
+	}
+
+	return light;
+}
+
+// Calculate lighting at the given corner of p
+u8 getSmoothLight(v3s16 p, v3s16 corner,
+		VoxelManipulator &vmanip, u32 daynight_ratio)
+{
+	if(corner.X == 1) p.X += 1;
+	else              assert(corner.X == -1);
+	if(corner.Y == 1) p.Y += 1;
+	else              assert(corner.Y == -1);
+	if(corner.Z == 1) p.Z += 1;
+	else              assert(corner.Z == -1);
+	
+	return getSmoothLight(p, vmanip, daynight_ratio);
+}
+
+void getTileInfo(
+		// Input:
+		v3s16 blockpos_nodes,
+		v3s16 p,
+		v3s16 face_dir,
+		u32 daynight_ratio,
+		VoxelManipulator &vmanip,
+		NodeModMap &temp_mods,
+		bool smooth_lighting,
+		// Output:
+		bool &makes_face,
+		v3s16 &p_corrected,
+		v3s16 &face_dir_corrected,
+		u8 *lights,
+		TileSpec &tile
+	)
+{
+	MapNode n0 = vmanip.getNodeNoEx(blockpos_nodes + p);
+	MapNode n1 = vmanip.getNodeNoEx(blockpos_nodes + p + face_dir);
+	TileSpec tile0 = getNodeTile(n0, p, face_dir, temp_mods);
+	TileSpec tile1 = getNodeTile(n1, p + face_dir, -face_dir, temp_mods);
+	
+	// This is hackish
+	u8 content0 = getNodeContent(p, n0, temp_mods);
+	u8 content1 = getNodeContent(p + face_dir, n1, temp_mods);
+	u8 mf = face_contents(content0, content1);
+
+	if(mf == 0)
+	{
+		makes_face = false;
+		return;
+	}
+
+	makes_face = true;
+	
+	if(mf == 1)
+	{
+		tile = tile0;
+		p_corrected = p;
+		face_dir_corrected = face_dir;
+	}
+	else
+	{
+		tile = tile1;
+		p_corrected = p + face_dir;
+		face_dir_corrected = -face_dir;
+	}
+	
+	if(smooth_lighting == false)
+	{
+		lights[0] = lights[1] = lights[2] = lights[3] =
+				decode_light(getFaceLight(daynight_ratio, n0, n1, face_dir));
+	}
+	else
+	{
+		v3s16 vertex_dirs[4];
+		getNodeVertexDirs(face_dir_corrected, vertex_dirs);
+		for(u16 i=0; i<4; i++)
+		{
+			lights[i] = getSmoothLight(blockpos_nodes + p_corrected,
+					vertex_dirs[i], vmanip, daynight_ratio);
+		}
+	}
+	
+	return;
+}
+
+/*
+	startpos:
+	translate_dir: unit vector with only one of x, y or z
+	face_dir: unit vector with only one of x, y or z
+*/
+void updateFastFaceRow(
+		u32 daynight_ratio,
+		v3f posRelative_f,
+		v3s16 startpos,
+		u16 length,
+		v3s16 translate_dir,
+		v3f translate_dir_f,
+		v3s16 face_dir,
+		v3f face_dir_f,
+		core::array<FastFace> &dest,
+		NodeModMap &temp_mods,
+		VoxelManipulator &vmanip,
+		v3s16 blockpos_nodes,
+		bool smooth_lighting)
+{
+	v3s16 p = startpos;
+	
+	u16 continuous_tiles_count = 0;
+	
+	bool makes_face;
+	v3s16 p_corrected;
+	v3s16 face_dir_corrected;
+	u8 lights[4];
+	TileSpec tile;
+	getTileInfo(blockpos_nodes, p, face_dir, daynight_ratio,
+			vmanip, temp_mods, smooth_lighting,
+			makes_face, p_corrected, face_dir_corrected, lights, tile);
+
+	for(u16 j=0; j<length; j++)
+	{
+		// If tiling can be done, this is set to false in the next step
+		bool next_is_different = true;
+		
+		v3s16 p_next;
+		
+		bool next_makes_face = false;
+		v3s16 next_p_corrected;
+		v3s16 next_face_dir_corrected;
+		u8 next_lights[4] = {0,0,0,0};
+		TileSpec next_tile;
+		
+		// If at last position, there is nothing to compare to and
+		// the face must be drawn anyway
+		if(j != length - 1)
+		{
+			p_next = p + translate_dir;
+			
+			getTileInfo(blockpos_nodes, p_next, face_dir, daynight_ratio,
+					vmanip, temp_mods, smooth_lighting,
+					next_makes_face, next_p_corrected,
+					next_face_dir_corrected, next_lights,
+					next_tile);
+			
+			if(next_makes_face == makes_face
+					&& next_p_corrected == p_corrected
+					&& next_face_dir_corrected == face_dir_corrected
+					&& next_lights[0] == lights[0]
+					&& next_lights[1] == lights[1]
+					&& next_lights[2] == lights[2]
+					&& next_lights[3] == lights[3]
+					&& next_tile == tile)
+			{
+				next_is_different = false;
+			}
+		}
+
+		continuous_tiles_count++;
+		
+		// This is set to true if the texture doesn't allow more tiling
+		bool end_of_texture = false;
+		/*
+			If there is no texture, it can be tiled infinitely.
+			If tiled==0, it means the texture can be tiled infinitely.
+			Otherwise check tiled agains continuous_tiles_count.
+		*/
+		if(tile.texture.atlas != NULL && tile.texture.tiled != 0)
+		{
+			if(tile.texture.tiled <= continuous_tiles_count)
+				end_of_texture = true;
+		}
+		
+		// Do this to disable tiling textures
+		//end_of_texture = true; //DEBUG
+		
+		if(next_is_different || end_of_texture)
+		{
+			/*
+				Create a face if there should be one
+			*/
+			if(makes_face)
+			{
+				// Floating point conversion of the position vector
+				v3f pf(p_corrected.X, p_corrected.Y, p_corrected.Z);
+				// Center point of face (kind of)
+				v3f sp = pf - ((f32)continuous_tiles_count / 2. - 0.5) * translate_dir_f;
+				v3f scale(1,1,1);
+
+				if(translate_dir.X != 0)
+				{
+					scale.X = continuous_tiles_count;
+				}
+				if(translate_dir.Y != 0)
+				{
+					scale.Y = continuous_tiles_count;
+				}
+				if(translate_dir.Z != 0)
+				{
+					scale.Z = continuous_tiles_count;
+				}
+				
+				makeFastFace(tile, lights[0], lights[1], lights[2], lights[3],
+						sp, face_dir_corrected, scale,
+						posRelative_f, dest);
+			}
+
+			continuous_tiles_count = 0;
+			
+			makes_face = next_makes_face;
+			p_corrected = next_p_corrected;
+			face_dir_corrected = next_face_dir_corrected;
+			lights[0] = next_lights[0];
+			lights[1] = next_lights[1];
+			lights[2] = next_lights[2];
+			lights[3] = next_lights[3];
+			tile = next_tile;
+		}
+		
+		p = p_next;
+	}
+}
+
+scene::SMesh* makeMapBlockMesh(MeshMakeData *data)
+{
+	// 4-21ms for MAP_BLOCKSIZE=16
+	// 24-155ms for MAP_BLOCKSIZE=32
+	//TimeTaker timer1("makeMapBlockMesh()");
+
+	core::array<FastFace> fastfaces_new;
+
+	v3s16 blockpos_nodes = data->m_blockpos*MAP_BLOCKSIZE;
+	
+	// floating point conversion
+	v3f posRelative_f(blockpos_nodes.X, blockpos_nodes.Y, blockpos_nodes.Z);
+	
+	/*
+		Some settings
+	*/
+	//bool new_style_water = g_settings.getBool("new_style_water");
+	//bool new_style_leaves = g_settings.getBool("new_style_leaves");
+	bool smooth_lighting = g_settings.getBool("smooth_lighting");
+	
+	/*
+		We are including the faces of the trailing edges of the block.
+		This means that when something changes, the caller must
+		also update the meshes of the blocks at the leading edges.
+
+		NOTE: This is the slowest part of this method.
+	*/
+	
+	{
+		// 4-23ms for MAP_BLOCKSIZE=16
+		//TimeTaker timer2("updateMesh() collect");
+
+		/*
+			Go through every y,z and get top(y+) faces in rows of x+
+		*/
+		for(s16 y=0; y<MAP_BLOCKSIZE; y++){
+			for(s16 z=0; z<MAP_BLOCKSIZE; z++){
+				updateFastFaceRow(data->m_daynight_ratio, posRelative_f,
+						v3s16(0,y,z), MAP_BLOCKSIZE,
+						v3s16(1,0,0), //dir
+						v3f  (1,0,0),
+						v3s16(0,1,0), //face dir
+						v3f  (0,1,0),
+						fastfaces_new,
+						data->m_temp_mods,
+						data->m_vmanip,
+						blockpos_nodes,
+						smooth_lighting);
+			}
+		}
+		/*
+			Go through every x,y and get right(x+) faces in rows of z+
+		*/
+		for(s16 x=0; x<MAP_BLOCKSIZE; x++){
+			for(s16 y=0; y<MAP_BLOCKSIZE; y++){
+				updateFastFaceRow(data->m_daynight_ratio, posRelative_f,
+						v3s16(x,y,0), MAP_BLOCKSIZE,
+						v3s16(0,0,1),
+						v3f  (0,0,1),
+						v3s16(1,0,0),
+						v3f  (1,0,0),
+						fastfaces_new,
+						data->m_temp_mods,
+						data->m_vmanip,
+						blockpos_nodes,
+						smooth_lighting);
+			}
+		}
+		/*
+			Go through every y,z and get back(z+) faces in rows of x+
+		*/
+		for(s16 z=0; z<MAP_BLOCKSIZE; z++){
+			for(s16 y=0; y<MAP_BLOCKSIZE; y++){
+				updateFastFaceRow(data->m_daynight_ratio, posRelative_f,
+						v3s16(0,y,z), MAP_BLOCKSIZE,
+						v3s16(1,0,0),
+						v3f  (1,0,0),
+						v3s16(0,0,1),
+						v3f  (0,0,1),
+						fastfaces_new,
+						data->m_temp_mods,
+						data->m_vmanip,
+						blockpos_nodes,
+						smooth_lighting);
+			}
+		}
+	}
+
+	// End of slow part
+
+	/*
+		Convert FastFaces to SMesh
+	*/
+
+	MeshCollector collector;
+
+	if(fastfaces_new.size() > 0)
+	{
+		// avg 0ms (100ms spikes when loading textures the first time)
+		//TimeTaker timer2("updateMesh() mesh building");
+
+		video::SMaterial material;
+		material.setFlag(video::EMF_LIGHTING, false);
+		material.setFlag(video::EMF_BILINEAR_FILTER, false);
+		material.setFlag(video::EMF_FOG_ENABLE, true);
+		//material.setFlag(video::EMF_ANTI_ALIASING, video::EAAM_OFF);
+		//material.setFlag(video::EMF_ANTI_ALIASING, video::EAAM_SIMPLE);
+
+		for(u32 i=0; i<fastfaces_new.size(); i++)
+		{
+			FastFace &f = fastfaces_new[i];
+
+			const u16 indices[] = {0,1,2,2,3,0};
+			const u16 indices_alternate[] = {0,1,3,2,3,1};
+			
+			video::ITexture *texture = f.tile.texture.atlas;
+			if(texture == NULL)
+				continue;
+
+			material.setTexture(0, texture);
+			
+			f.tile.applyMaterialOptions(material);
+
+			const u16 *indices_p = indices;
+			
+			/*
+				Revert triangles for nicer looking gradient if vertices
+				1 and 3 have same color or 0 and 2 have different color.
+			*/
+			if(f.vertices[0].Color != f.vertices[2].Color
+					|| f.vertices[1].Color == f.vertices[3].Color)
+				indices_p = indices_alternate;
+			
+			collector.append(material, f.vertices, 4, indices_p, 6);
+		}
+	}
+
+	/*
+		Add special graphics:
+		- torches
+		- flowing water
+		- fences
+		- whatever
+	*/
+
+	mapblock_mesh_generate_special(data, collector);
+	
+	/*
+		Add stuff from collector to mesh
+	*/
+	
+	scene::SMesh *mesh_new = NULL;
+	mesh_new = new scene::SMesh();
+	
+	collector.fillMesh(mesh_new);
+
+	/*
+		Do some stuff to the mesh
+	*/
+
+	mesh_new->recalculateBoundingBox();
+
+	/*
+		Delete new mesh if it is empty
+	*/
+
+	if(mesh_new->getMeshBufferCount() == 0)
+	{
+		mesh_new->drop();
+		mesh_new = NULL;
+	}
+
+	if(mesh_new)
+	{
+#if 0
+		// Usually 1-700 faces and 1-7 materials
+		std::cout<<"Updated MapBlock has "<<fastfaces_new.size()<<" faces "
+				<<"and uses "<<mesh_new->getMeshBufferCount()
+				<<" materials (meshbuffers)"<<std::endl;
+#endif
+
+		// Use VBO for mesh (this just would set this for ever buffer)
+		// This will lead to infinite memory usage because or irrlicht.
+		//mesh_new->setHardwareMappingHint(scene::EHM_STATIC);
+
+		/*
+			NOTE: If that is enabled, some kind of a queue to the main
+			thread should be made which would call irrlicht to delete
+			the hardware buffer and then delete the mesh
+		*/
+	}
+
+	return mesh_new;
+	
+	//std::cout<<"added "<<fastfaces.getSize()<<" faces."<<std::endl;
+}
+
diff --git a/src/mapblock_mesh.h b/src/mapblock_mesh.h
new file mode 100644
index 000000000..591172bc9
--- /dev/null
+++ b/src/mapblock_mesh.h
@@ -0,0 +1,143 @@
+/*
+Minetest-c55
+Copyright (C) 2010-2011 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#ifndef MAPBLOCK_MESH_HEADER
+#define MAPBLOCK_MESH_HEADER
+
+#include "common_irrlicht.h"
+#include "mapblock_nodemod.h"
+#include "voxel.h"
+
+/*
+	Mesh making stuff
+*/
+
+/*
+	This is used because CMeshBuffer::append() is very slow
+*/
+struct PreMeshBuffer
+{
+	video::SMaterial material;
+	core::array<u16> indices;
+	core::array<video::S3DVertex> vertices;
+};
+
+class MeshCollector
+{
+public:
+	void append(
+			video::SMaterial material,
+			const video::S3DVertex* const vertices,
+			u32 numVertices,
+			const u16* const indices,
+			u32 numIndices
+		)
+	{
+		PreMeshBuffer *p = NULL;
+		for(u32 i=0; i<m_prebuffers.size(); i++)
+		{
+			PreMeshBuffer &pp = m_prebuffers[i];
+			if(pp.material != material)
+				continue;
+
+			p = &pp;
+			break;
+		}
+
+		if(p == NULL)
+		{
+			PreMeshBuffer pp;
+			pp.material = material;
+			m_prebuffers.push_back(pp);
+			p = &m_prebuffers[m_prebuffers.size()-1];
+		}
+
+		u32 vertex_count = p->vertices.size();
+		for(u32 i=0; i<numIndices; i++)
+		{
+			u32 j = indices[i] + vertex_count;
+			if(j > 65535)
+			{
+				dstream<<"FIXME: Meshbuffer ran out of indices"<<std::endl;
+				// NOTE: Fix is to just add an another MeshBuffer
+			}
+			p->indices.push_back(j);
+		}
+		for(u32 i=0; i<numVertices; i++)
+		{
+			p->vertices.push_back(vertices[i]);
+		}
+	}
+
+	void fillMesh(scene::SMesh *mesh)
+	{
+		/*dstream<<"Filling mesh with "<<m_prebuffers.size()
+				<<" meshbuffers"<<std::endl;*/
+		for(u32 i=0; i<m_prebuffers.size(); i++)
+		{
+			PreMeshBuffer &p = m_prebuffers[i];
+
+			/*dstream<<"p.vertices.size()="<<p.vertices.size()
+					<<", p.indices.size()="<<p.indices.size()
+					<<std::endl;*/
+			
+			// Create meshbuffer
+			
+			// This is a "Standard MeshBuffer",
+			// it's a typedeffed CMeshBuffer<video::S3DVertex>
+			scene::SMeshBuffer *buf = new scene::SMeshBuffer();
+			// Set material
+			buf->Material = p.material;
+			//((scene::SMeshBuffer*)buf)->Material = p.material;
+			// Use VBO
+			//buf->setHardwareMappingHint(scene::EHM_STATIC);
+			// Add to mesh
+			mesh->addMeshBuffer(buf);
+			// Mesh grabbed it
+			buf->drop();
+
+			buf->append(p.vertices.pointer(), p.vertices.size(),
+					p.indices.pointer(), p.indices.size());
+		}
+	}
+
+private:
+	core::array<PreMeshBuffer> m_prebuffers;
+};
+
+class MapBlock;
+
+struct MeshMakeData
+{
+	u32 m_daynight_ratio;
+	NodeModMap m_temp_mods;
+	VoxelManipulator m_vmanip;
+	v3s16 m_blockpos;
+	
+	/*
+		Copy central data directly from block, and other data from
+		parent of block.
+	*/
+	void fill(u32 daynight_ratio, MapBlock *block);
+};
+
+scene::SMesh* makeMapBlockMesh(MeshMakeData *data);
+
+#endif
+
diff --git a/src/mapblock_nodemod.h b/src/mapblock_nodemod.h
new file mode 100644
index 000000000..4952df107
--- /dev/null
+++ b/src/mapblock_nodemod.h
@@ -0,0 +1,114 @@
+/*
+Minetest-c55
+Copyright (C) 2010 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#ifndef MAPBLOCK_NODEMOD_HEADER
+#define MAPBLOCK_NODEMOD_HEADER
+
+enum NodeModType
+{
+	NODEMOD_NONE,
+	NODEMOD_CHANGECONTENT, //param is content id
+	NODEMOD_CRACK // param is crack progression
+};
+
+struct NodeMod
+{
+	NodeMod(enum NodeModType a_type=NODEMOD_NONE, u16 a_param=0)
+	{
+		type = a_type;
+		param = a_param;
+	}
+	bool operator==(const NodeMod &other)
+	{
+		return (type == other.type && param == other.param);
+	}
+	enum NodeModType type;
+	u16 param;
+};
+
+class NodeModMap
+{
+public:
+	/*
+		returns true if the mod was different last time
+	*/
+	bool set(v3s16 p, const NodeMod &mod)
+	{
+		// See if old is different, cancel if it is not different.
+		core::map<v3s16, NodeMod>::Node *n = m_mods.find(p);
+		if(n)
+		{
+			NodeMod old = n->getValue();
+			if(old == mod)
+				return false;
+
+			n->setValue(mod);
+		}
+		else
+		{
+			m_mods.insert(p, mod);
+		}
+		
+		return true;
+	}
+	// Returns true if there was one
+	bool get(v3s16 p, NodeMod *mod)
+	{
+		core::map<v3s16, NodeMod>::Node *n;
+		n = m_mods.find(p);
+		if(n == NULL)
+			return false;
+		if(mod)
+			*mod = n->getValue();
+		return true;
+	}
+	bool clear(v3s16 p)
+	{
+		if(m_mods.find(p))
+		{
+			m_mods.remove(p);
+			return true;
+		}
+		return false;
+	}
+	bool clear()
+	{
+		if(m_mods.size() == 0)
+			return false;
+		m_mods.clear();
+		return true;
+	}
+	void copy(NodeModMap &dest)
+	{
+		dest.m_mods.clear();
+
+		for(core::map<v3s16, NodeMod>::Iterator
+				i = m_mods.getIterator();
+				i.atEnd() == false; i++)
+		{
+			dest.m_mods.insert(i.getNode()->getKey(), i.getNode()->getValue());
+		}
+	}
+
+private:
+	core::map<v3s16, NodeMod> m_mods;
+};
+
+#endif
+
diff --git a/src/mapgen.cpp b/src/mapgen.cpp
new file mode 100644
index 000000000..801dd72b1
--- /dev/null
+++ b/src/mapgen.cpp
@@ -0,0 +1,1950 @@
+/*
+Minetest-c55
+Copyright (C) 2010-2011 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "mapgen.h"
+#include "voxel.h"
+#include "content_mapnode.h"
+#include "noise.h"
+#include "mapblock.h"
+#include "map.h"
+#include "serverobject.h"
+#include "mineral.h"
+
+namespace mapgen
+{
+
+/*
+	Some helper functions for the map generator
+*/
+
+#if 0
+static s16 find_ground_level(VoxelManipulator &vmanip, v2s16 p2d)
+{
+	v3s16 em = vmanip.m_area.getExtent();
+	s16 y_nodes_max = vmanip.m_area.MaxEdge.Y;
+	s16 y_nodes_min = vmanip.m_area.MinEdge.Y;
+	u32 i = vmanip.m_area.index(v3s16(p2d.X, y_nodes_max, p2d.Y));
+	s16 y;
+	for(y=y_nodes_max; y>=y_nodes_min; y--)
+	{
+		MapNode &n = vmanip.m_data[i];
+		if(content_walkable(n.d))
+			break;
+
+		vmanip.m_area.add_y(em, i, -1);
+	}
+	if(y >= y_nodes_min)
+		return y;
+	else
+		return y_nodes_min;
+}
+
+static s16 find_ground_level_clever(VoxelManipulator &vmanip, v2s16 p2d)
+{
+	v3s16 em = vmanip.m_area.getExtent();
+	s16 y_nodes_max = vmanip.m_area.MaxEdge.Y;
+	s16 y_nodes_min = vmanip.m_area.MinEdge.Y;
+	u32 i = vmanip.m_area.index(v3s16(p2d.X, y_nodes_max, p2d.Y));
+	s16 y;
+	for(y=y_nodes_max; y>=y_nodes_min; y--)
+	{
+		MapNode &n = vmanip.m_data[i];
+		if(content_walkable(n.d)
+				&& n.d != CONTENT_TREE
+				&& n.d != CONTENT_LEAVES)
+			break;
+
+		vmanip.m_area.add_y(em, i, -1);
+	}
+	if(y >= y_nodes_min)
+		return y;
+	else
+		return y_nodes_min;
+}
+#endif
+
+static void make_tree(VoxelManipulator &vmanip, v3s16 p0)
+{
+	MapNode treenode(CONTENT_TREE);
+	MapNode leavesnode(CONTENT_LEAVES);
+
+	s16 trunk_h = myrand_range(3, 6);
+	v3s16 p1 = p0;
+	for(s16 ii=0; ii<trunk_h; ii++)
+	{
+		if(vmanip.m_area.contains(p1))
+			vmanip.m_data[vmanip.m_area.index(p1)] = treenode;
+		p1.Y++;
+	}
+
+	// p1 is now the last piece of the trunk
+	p1.Y -= 1;
+
+	VoxelArea leaves_a(v3s16(-2,-2,-2), v3s16(2,2,2));
+	//SharedPtr<u8> leaves_d(new u8[leaves_a.getVolume()]);
+	Buffer<u8> leaves_d(leaves_a.getVolume());
+	for(s32 i=0; i<leaves_a.getVolume(); i++)
+		leaves_d[i] = 0;
+
+	// Force leaves at near the end of the trunk
+	{
+		s16 d = 1;
+		for(s16 z=-d; z<=d; z++)
+		for(s16 y=-d; y<=d; y++)
+		for(s16 x=-d; x<=d; x++)
+		{
+			leaves_d[leaves_a.index(v3s16(x,y,z))] = 1;
+		}
+	}
+
+	// Add leaves randomly
+	for(u32 iii=0; iii<7; iii++)
+	{
+		s16 d = 1;
+
+		v3s16 p(
+			myrand_range(leaves_a.MinEdge.X, leaves_a.MaxEdge.X-d),
+			myrand_range(leaves_a.MinEdge.Y, leaves_a.MaxEdge.Y-d),
+			myrand_range(leaves_a.MinEdge.Z, leaves_a.MaxEdge.Z-d)
+		);
+
+		for(s16 z=0; z<=d; z++)
+		for(s16 y=0; y<=d; y++)
+		for(s16 x=0; x<=d; x++)
+		{
+			leaves_d[leaves_a.index(p+v3s16(x,y,z))] = 1;
+		}
+	}
+
+	// Blit leaves to vmanip
+	for(s16 z=leaves_a.MinEdge.Z; z<=leaves_a.MaxEdge.Z; z++)
+	for(s16 y=leaves_a.MinEdge.Y; y<=leaves_a.MaxEdge.Y; y++)
+	for(s16 x=leaves_a.MinEdge.X; x<=leaves_a.MaxEdge.X; x++)
+	{
+		v3s16 p(x,y,z);
+		p += p1;
+		if(vmanip.m_area.contains(p) == false)
+			continue;
+		u32 vi = vmanip.m_area.index(p);
+		if(vmanip.m_data[vi].d != CONTENT_AIR
+				&& vmanip.m_data[vi].d != CONTENT_IGNORE)
+			continue;
+		u32 i = leaves_a.index(x,y,z);
+		if(leaves_d[i] == 1)
+			vmanip.m_data[vi] = leavesnode;
+	}
+}
+
+#if 0
+static void make_randomstone(VoxelManipulator &vmanip, v3s16 p0)
+{
+	MapNode stonenode(CONTENT_STONE);
+
+	s16 size = myrand_range(3, 6);
+	
+	VoxelArea stone_a(v3s16(-2,0,-2), v3s16(2,size,2));
+	Buffer<u8> stone_d(stone_a.getVolume());
+	for(s32 i=0; i<stone_a.getVolume(); i++)
+		stone_d[i] = 0;
+
+	// Force stone at bottom to make it usually touch the ground
+	{
+		for(s16 z=0; z<=0; z++)
+		for(s16 y=0; y<=0; y++)
+		for(s16 x=0; x<=0; x++)
+		{
+			stone_d[stone_a.index(v3s16(x,y,z))] = 1;
+		}
+	}
+
+	// Generate from perlin noise
+	for(s16 z=stone_a.MinEdge.Z; z<=stone_a.MaxEdge.Z; z++)
+	for(s16 y=stone_a.MinEdge.Y; y<=stone_a.MaxEdge.Y; y++)
+	for(s16 x=stone_a.MinEdge.X; x<=stone_a.MaxEdge.X; x++)
+	{
+		double d = noise3d_perlin((float)x/3.,(float)z/3.,(float)y/3.,
+				p0.Z*4243+p0.Y*34+p0.X, 2, 0.5);
+		if(z == stone_a.MinEdge.Z || z == stone_a.MaxEdge.Z)
+			d -= 0.3;
+		if(/*y == stone_a.MinEdge.Y ||*/ y == stone_a.MaxEdge.Y)
+			d -= 0.3;
+		if(x == stone_a.MinEdge.X || x == stone_a.MaxEdge.X)
+			d -= 0.3;
+		if(d > 0.0)
+		{
+			u32 vi = stone_a.index(v3s16(x,y,z));
+			stone_d[vi] = 1;
+		}
+	}
+
+	/*// Add stone randomly
+	for(u32 iii=0; iii<7; iii++)
+	{
+		s16 d = 1;
+
+		v3s16 p(
+			myrand_range(stone_a.MinEdge.X, stone_a.MaxEdge.X-d),
+			myrand_range(stone_a.MinEdge.Y, stone_a.MaxEdge.Y-d),
+			myrand_range(stone_a.MinEdge.Z, stone_a.MaxEdge.Z-d)
+		);
+
+		for(s16 z=0; z<=d; z++)
+		for(s16 y=0; y<=d; y++)
+		for(s16 x=0; x<=d; x++)
+		{
+			stone_d[stone_a.index(p+v3s16(x,y,z))] = 1;
+		}
+	}*/
+
+	// Blit stone to vmanip
+	for(s16 z=stone_a.MinEdge.Z; z<=stone_a.MaxEdge.Z; z++)
+	for(s16 y=stone_a.MinEdge.Y; y<=stone_a.MaxEdge.Y; y++)
+	for(s16 x=stone_a.MinEdge.X; x<=stone_a.MaxEdge.X; x++)
+	{
+		v3s16 p(x,y,z);
+		p += p0;
+		if(vmanip.m_area.contains(p) == false)
+			continue;
+		u32 vi = vmanip.m_area.index(p);
+		if(vmanip.m_data[vi].d != CONTENT_AIR
+				&& vmanip.m_data[vi].d != CONTENT_IGNORE)
+			continue;
+		u32 i = stone_a.index(x,y,z);
+		if(stone_d[i] == 1)
+			vmanip.m_data[vi] = stonenode;
+	}
+}
+#endif
+
+#if 0
+static void make_largestone(VoxelManipulator &vmanip, v3s16 p0)
+{
+	MapNode stonenode(CONTENT_STONE);
+
+	s16 size = myrand_range(8, 16);
+	
+	VoxelArea stone_a(v3s16(-size/2,0,-size/2), v3s16(size/2,size,size/2));
+	Buffer<u8> stone_d(stone_a.getVolume());
+	for(s32 i=0; i<stone_a.getVolume(); i++)
+		stone_d[i] = 0;
+
+	// Force stone at bottom to make it usually touch the ground
+	{
+		for(s16 z=0; z<=0; z++)
+		for(s16 y=0; y<=0; y++)
+		for(s16 x=0; x<=0; x++)
+		{
+			stone_d[stone_a.index(v3s16(x,y,z))] = 1;
+		}
+	}
+
+	// Generate from perlin noise
+	for(s16 z=stone_a.MinEdge.Z; z<=stone_a.MaxEdge.Z; z++)
+	for(s16 y=stone_a.MinEdge.Y; y<=stone_a.MaxEdge.Y; y++)
+	for(s16 x=stone_a.MinEdge.X; x<=stone_a.MaxEdge.X; x++)
+	{
+		double d = 1.0;
+		d += noise3d_perlin((float)x/10.,(float)z/10.,(float)y/10.,
+				p0.Z*5123+p0.Y*2439+p0.X, 2, 0.5);
+		double mid_z = (stone_a.MaxEdge.Z+stone_a.MinEdge.Z)/2;
+		double mid_x = (stone_a.MaxEdge.X+stone_a.MinEdge.X)/2;
+		double mid_y = (stone_a.MaxEdge.Y+stone_a.MinEdge.Y)/2;
+		double dz = (double)z-mid_z;
+		double dx = (double)x-mid_x;
+		double dy = MYMAX(0, (double)y-mid_y);
+		double r = sqrt(dz*dz+dx*dx+dy*dy);
+		d /= (2*r/size)*2 + 0.01;
+		if(d > 1.0)
+		{
+			u32 vi = stone_a.index(v3s16(x,y,z));
+			stone_d[vi] = 1;
+		}
+	}
+
+	/*// Add stone randomly
+	for(u32 iii=0; iii<7; iii++)
+	{
+		s16 d = 1;
+
+		v3s16 p(
+			myrand_range(stone_a.MinEdge.X, stone_a.MaxEdge.X-d),
+			myrand_range(stone_a.MinEdge.Y, stone_a.MaxEdge.Y-d),
+			myrand_range(stone_a.MinEdge.Z, stone_a.MaxEdge.Z-d)
+		);
+
+		for(s16 z=0; z<=d; z++)
+		for(s16 y=0; y<=d; y++)
+		for(s16 x=0; x<=d; x++)
+		{
+			stone_d[stone_a.index(p+v3s16(x,y,z))] = 1;
+		}
+	}*/
+
+	// Blit stone to vmanip
+	for(s16 z=stone_a.MinEdge.Z; z<=stone_a.MaxEdge.Z; z++)
+	for(s16 y=stone_a.MinEdge.Y; y<=stone_a.MaxEdge.Y; y++)
+	for(s16 x=stone_a.MinEdge.X; x<=stone_a.MaxEdge.X; x++)
+	{
+		v3s16 p(x,y,z);
+		p += p0;
+		if(vmanip.m_area.contains(p) == false)
+			continue;
+		u32 vi = vmanip.m_area.index(p);
+		/*if(vmanip.m_data[vi].d != CONTENT_AIR
+				&& vmanip.m_data[vi].d != CONTENT_IGNORE)
+			continue;*/
+		u32 i = stone_a.index(x,y,z);
+		if(stone_d[i] == 1)
+			vmanip.m_data[vi] = stonenode;
+	}
+}
+#endif
+
+/*
+	Dungeon making routines
+*/
+
+#define VMANIP_FLAG_DUNGEON_INSIDE VOXELFLAG_CHECKED1
+#define VMANIP_FLAG_DUNGEON_PRESERVE VOXELFLAG_CHECKED2
+#define VMANIP_FLAG_DUNGEON_UNTOUCHABLE (\
+		VMANIP_FLAG_DUNGEON_INSIDE|VMANIP_FLAG_DUNGEON_PRESERVE)
+
+static void make_room1(VoxelManipulator &vmanip, v3s16 roomsize, v3s16 roomplace)
+{
+	// Make +-X walls
+	for(s16 z=0; z<roomsize.Z; z++)
+	for(s16 y=0; y<roomsize.Y; y++)
+	{
+		{
+			v3s16 p = roomplace + v3s16(0,y,z);
+			if(vmanip.m_area.contains(p) == false)
+				continue;
+			u32 vi = vmanip.m_area.index(p);
+			if(vmanip.m_flags[vi] & VMANIP_FLAG_DUNGEON_UNTOUCHABLE)
+				continue;
+			vmanip.m_data[vi] = MapNode(CONTENT_COBBLE);
+		}
+		{
+			v3s16 p = roomplace + v3s16(roomsize.X-1,y,z);
+			if(vmanip.m_area.contains(p) == false)
+				continue;
+			u32 vi = vmanip.m_area.index(p);
+			if(vmanip.m_flags[vi] & VMANIP_FLAG_DUNGEON_UNTOUCHABLE)
+				continue;
+			vmanip.m_data[vi] = MapNode(CONTENT_COBBLE);
+		}
+	}
+	
+	// Make +-Z walls
+	for(s16 x=0; x<roomsize.X; x++)
+	for(s16 y=0; y<roomsize.Y; y++)
+	{
+		{
+			v3s16 p = roomplace + v3s16(x,y,0);
+			if(vmanip.m_area.contains(p) == false)
+				continue;
+			u32 vi = vmanip.m_area.index(p);
+			if(vmanip.m_flags[vi] & VMANIP_FLAG_DUNGEON_UNTOUCHABLE)
+				continue;
+			vmanip.m_data[vi] = MapNode(CONTENT_COBBLE);
+		}
+		{
+			v3s16 p = roomplace + v3s16(x,y,roomsize.Z-1);
+			if(vmanip.m_area.contains(p) == false)
+				continue;
+			u32 vi = vmanip.m_area.index(p);
+			if(vmanip.m_flags[vi] & VMANIP_FLAG_DUNGEON_UNTOUCHABLE)
+				continue;
+			vmanip.m_data[vi] = MapNode(CONTENT_COBBLE);
+		}
+	}
+	
+	// Make +-Y walls (floor and ceiling)
+	for(s16 z=0; z<roomsize.Z; z++)
+	for(s16 x=0; x<roomsize.X; x++)
+	{
+		{
+			v3s16 p = roomplace + v3s16(x,0,z);
+			if(vmanip.m_area.contains(p) == false)
+				continue;
+			u32 vi = vmanip.m_area.index(p);
+			if(vmanip.m_flags[vi] & VMANIP_FLAG_DUNGEON_UNTOUCHABLE)
+				continue;
+			vmanip.m_data[vi] = MapNode(CONTENT_COBBLE);
+		}
+		{
+			v3s16 p = roomplace + v3s16(x,roomsize.Y-1,z);
+			if(vmanip.m_area.contains(p) == false)
+				continue;
+			u32 vi = vmanip.m_area.index(p);
+			if(vmanip.m_flags[vi] & VMANIP_FLAG_DUNGEON_UNTOUCHABLE)
+				continue;
+			vmanip.m_data[vi] = MapNode(CONTENT_COBBLE);
+		}
+	}
+	
+	// Fill with air
+	for(s16 z=1; z<roomsize.Z-1; z++)
+	for(s16 y=1; y<roomsize.Y-1; y++)
+	for(s16 x=1; x<roomsize.X-1; x++)
+	{
+		v3s16 p = roomplace + v3s16(x,y,z);
+		if(vmanip.m_area.contains(p) == false)
+			continue;
+		u32 vi = vmanip.m_area.index(p);
+		vmanip.m_flags[vi] |= VMANIP_FLAG_DUNGEON_UNTOUCHABLE;
+		vmanip.m_data[vi] = MapNode(CONTENT_AIR);
+	}
+}
+
+static void make_fill(VoxelManipulator &vmanip, v3s16 place, v3s16 size,
+		u8 avoid_flags, MapNode n, u8 or_flags)
+{
+	for(s16 z=0; z<size.Z; z++)
+	for(s16 y=0; y<size.Y; y++)
+	for(s16 x=0; x<size.X; x++)
+	{
+		v3s16 p = place + v3s16(x,y,z);
+		if(vmanip.m_area.contains(p) == false)
+			continue;
+		u32 vi = vmanip.m_area.index(p);
+		if(vmanip.m_flags[vi] & avoid_flags)
+			continue;
+		vmanip.m_flags[vi] |= or_flags;
+		vmanip.m_data[vi] = n;
+	}
+}
+
+static void make_hole1(VoxelManipulator &vmanip, v3s16 place)
+{
+	make_fill(vmanip, place, v3s16(1,2,1), 0, MapNode(CONTENT_AIR),
+			VMANIP_FLAG_DUNGEON_INSIDE);
+}
+
+static void make_door1(VoxelManipulator &vmanip, v3s16 doorplace, v3s16 doordir)
+{
+	make_hole1(vmanip, doorplace);
+	// Place torch (for testing)
+	//vmanip.m_data[vmanip.m_area.index(doorplace)] = MapNode(CONTENT_TORCH);
+}
+
+static v3s16 rand_ortho_dir(PseudoRandom &random)
+{
+	if(random.next()%2==0)
+		return random.next()%2 ? v3s16(-1,0,0) : v3s16(1,0,0);
+	else
+		return random.next()%2 ? v3s16(0,0,-1) : v3s16(0,0,1);
+}
+
+static v3s16 turn_xz(v3s16 olddir, int t)
+{
+	v3s16 dir;
+	if(t == 0)
+	{
+		// Turn right
+		dir.X = olddir.Z;
+		dir.Z = -olddir.X;
+		dir.Y = olddir.Y;
+	}
+	else
+	{
+		// Turn left
+		dir.X = -olddir.Z;
+		dir.Z = olddir.X;
+		dir.Y = olddir.Y;
+	}
+	return dir;
+}
+
+static v3s16 random_turn(PseudoRandom &random, v3s16 olddir)
+{
+	int turn = random.range(0,2);
+	v3s16 dir;
+	if(turn == 0)
+	{
+		// Go straight
+		dir = olddir;
+	}
+	else if(turn == 1)
+		// Turn right
+		dir = turn_xz(olddir, 0);
+	else
+		// Turn left
+		dir = turn_xz(olddir, 1);
+	return dir;
+}
+
+static void make_corridor(VoxelManipulator &vmanip, v3s16 doorplace,
+		v3s16 doordir, v3s16 &result_place, v3s16 &result_dir,
+		PseudoRandom &random)
+{
+	make_hole1(vmanip, doorplace);
+	v3s16 p0 = doorplace;
+	v3s16 dir = doordir;
+	u32 length;
+	if(random.next()%2)
+		length = random.range(1,13);
+	else
+		length = random.range(1,6);
+	length = random.range(1,13);
+	u32 partlength = random.range(1,length);
+	u32 partcount = 0;
+	s16 make_stairs = 0;
+	if(random.next()%2 == 0 && partlength >= 3)
+		make_stairs = random.next()%2 ? 1 : -1;
+	for(u32 i=0; i<length; i++)
+	{
+		v3s16 p = p0 + dir;
+		if(partcount != 0)
+			p.Y += make_stairs;
+
+		/*// If already empty
+		if(vmanip.getNodeNoExNoEmerge(p).d
+				== CONTENT_AIR
+		&& vmanip.getNodeNoExNoEmerge(p+v3s16(0,1,0)).d
+				== CONTENT_AIR)
+		{
+		}*/
+
+		if(vmanip.m_area.contains(p) == true
+				&& vmanip.m_area.contains(p+v3s16(0,1,0)) == true)
+		{
+			if(make_stairs)
+			{
+				make_fill(vmanip, p+v3s16(-1,-1,-1), v3s16(3,5,3),
+						VMANIP_FLAG_DUNGEON_UNTOUCHABLE, MapNode(CONTENT_COBBLE), 0);
+				make_fill(vmanip, p, v3s16(1,2,1), 0, MapNode(CONTENT_AIR),
+						VMANIP_FLAG_DUNGEON_INSIDE);
+				make_fill(vmanip, p-dir, v3s16(1,2,1), 0, MapNode(CONTENT_AIR),
+						VMANIP_FLAG_DUNGEON_INSIDE);
+			}
+			else
+			{
+				make_fill(vmanip, p+v3s16(-1,-1,-1), v3s16(3,4,3),
+						VMANIP_FLAG_DUNGEON_UNTOUCHABLE, MapNode(CONTENT_COBBLE), 0);
+				make_hole1(vmanip, p);
+				/*make_fill(vmanip, p, v3s16(1,2,1), 0, MapNode(CONTENT_AIR),
+						VMANIP_FLAG_DUNGEON_INSIDE);*/
+			}
+
+			p0 = p;
+		}
+		else
+		{
+			// Can't go here, turn away
+			dir = turn_xz(dir, random.range(0,1));
+			make_stairs = -make_stairs;
+			partcount = 0;
+			partlength = random.range(1,length);
+			continue;
+		}
+
+		partcount++;
+		if(partcount >= partlength)
+		{
+			partcount = 0;
+			
+			dir = random_turn(random, dir);
+			
+			partlength = random.range(1,length);
+
+			make_stairs = 0;
+			if(random.next()%2 == 0 && partlength >= 3)
+				make_stairs = random.next()%2 ? 1 : -1;
+		}
+	}
+	result_place = p0;
+	result_dir = dir;
+}
+
+class RoomWalker
+{
+public:
+
+	RoomWalker(VoxelManipulator &vmanip_, v3s16 pos, PseudoRandom &random):
+			vmanip(vmanip_),
+			m_pos(pos),
+			m_random(random)
+	{
+		randomizeDir();
+	}
+
+	void randomizeDir()
+	{
+		m_dir = rand_ortho_dir(m_random);
+	}
+
+	void setPos(v3s16 pos)
+	{
+		m_pos = pos;
+	}
+
+	void setDir(v3s16 dir)
+	{
+		m_dir = dir;
+	}
+	
+	bool findPlaceForDoor(v3s16 &result_place, v3s16 &result_dir)
+	{
+		for(u32 i=0; i<100; i++)
+		{
+			v3s16 p = m_pos + m_dir;
+			v3s16 p1 = p + v3s16(0,1,0);
+			if(vmanip.m_area.contains(p) == false
+					|| vmanip.m_area.contains(p1) == false
+					|| i % 4 == 0)
+			{
+				randomizeDir();
+				continue;
+			}
+			if(vmanip.getNodeNoExNoEmerge(p).d
+					== CONTENT_COBBLE
+			&& vmanip.getNodeNoExNoEmerge(p1).d
+					== CONTENT_COBBLE)
+			{
+				// Found wall, this is a good place!
+				result_place = p;
+				result_dir = m_dir;
+				// Randomize next direction
+				randomizeDir();
+				return true;
+			}
+			/*
+				Determine where to move next
+			*/
+			// Jump one up if the actual space is there
+			if(vmanip.getNodeNoExNoEmerge(p+v3s16(0,0,0)).d
+					== CONTENT_COBBLE
+			&& vmanip.getNodeNoExNoEmerge(p+v3s16(0,1,0)).d
+					== CONTENT_AIR
+			&& vmanip.getNodeNoExNoEmerge(p+v3s16(0,2,0)).d
+					== CONTENT_AIR)
+				p += v3s16(0,1,0);
+			// Jump one down if the actual space is there
+			if(vmanip.getNodeNoExNoEmerge(p+v3s16(0,1,0)).d
+					== CONTENT_COBBLE
+			&& vmanip.getNodeNoExNoEmerge(p+v3s16(0,0,0)).d
+					== CONTENT_AIR
+			&& vmanip.getNodeNoExNoEmerge(p+v3s16(0,-1,0)).d
+					== CONTENT_AIR)
+				p += v3s16(0,-1,0);
+			// Check if walking is now possible
+			if(vmanip.getNodeNoExNoEmerge(p).d
+					!= CONTENT_AIR
+			|| vmanip.getNodeNoExNoEmerge(p+v3s16(0,1,0)).d
+					!= CONTENT_AIR)
+			{
+				// Cannot continue walking here
+				randomizeDir();
+				continue;
+			}
+			// Move there
+			m_pos = p;
+		}
+		return false;
+	}
+
+	bool findPlaceForRoomDoor(v3s16 roomsize, v3s16 &result_doorplace,
+			v3s16 &result_doordir, v3s16 &result_roomplace)
+	{
+		for(s16 trycount=0; trycount<30; trycount++)
+		{
+			v3s16 doorplace;
+			v3s16 doordir;
+			bool r = findPlaceForDoor(doorplace, doordir);
+			if(r == false)
+				continue;
+			v3s16 roomplace;
+			// X east, Z north, Y up
+			if(doordir == v3s16(1,0,0)) // X+
+				roomplace = doorplace + v3s16(0,-1,-roomsize.Z/2+m_random.range(-roomsize.Z/2+1,roomsize.Z/2-1));
+			if(doordir == v3s16(-1,0,0)) // X-
+				roomplace = doorplace + v3s16(-roomsize.X+1,-1,-roomsize.Z/2+m_random.range(-roomsize.Z/2+1,roomsize.Z/2-1));
+			if(doordir == v3s16(0,0,1)) // Z+
+				roomplace = doorplace + v3s16(-roomsize.X/2+m_random.range(-roomsize.X/2+1,roomsize.X/2-1),-1,0);
+			if(doordir == v3s16(0,0,-1)) // Z-
+				roomplace = doorplace + v3s16(-roomsize.X/2+m_random.range(-roomsize.X/2+1,roomsize.X/2-1),-1,-roomsize.Z+1);
+			
+			// Check fit
+			bool fits = true;
+			for(s16 z=1; z<roomsize.Z-1; z++)
+			for(s16 y=1; y<roomsize.Y-1; y++)
+			for(s16 x=1; x<roomsize.X-1; x++)
+			{
+				v3s16 p = roomplace + v3s16(x,y,z);
+				if(vmanip.m_area.contains(p) == false)
+				{
+					fits = false;
+					break;
+				}
+				if(vmanip.m_flags[vmanip.m_area.index(p)]
+						& VMANIP_FLAG_DUNGEON_INSIDE)
+				{
+					fits = false;
+					break;
+				}
+			}
+			if(fits == false)
+			{
+				// Find new place
+				continue;
+			}
+			result_doorplace = doorplace;
+			result_doordir = doordir;
+			result_roomplace = roomplace;
+			return true;
+		}
+		return false;
+	}
+
+private:
+	VoxelManipulator &vmanip;
+	v3s16 m_pos;
+	v3s16 m_dir;
+	PseudoRandom &m_random;
+};
+
+static void make_dungeon1(VoxelManipulator &vmanip, PseudoRandom &random)
+{
+	v3s16 areasize = vmanip.m_area.getExtent();
+	v3s16 roomsize;
+	v3s16 roomplace;
+	
+	/*
+		Find place for first room
+	*/
+	bool fits = false;
+	for(u32 i=0; i<100; i++)
+	{
+		roomsize = v3s16(random.range(4,8),random.range(4,6),random.range(4,8));
+		roomplace = vmanip.m_area.MinEdge + v3s16(
+				random.range(0,areasize.X-roomsize.X-1),
+				random.range(0,areasize.Y-roomsize.Y-1),
+				random.range(0,areasize.Z-roomsize.Z-1));
+		/*
+			Check that we're not putting the room to an unknown place,
+			otherwise it might end up floating in the air
+		*/
+		fits = true;
+		for(s16 z=1; z<roomsize.Z-1; z++)
+		for(s16 y=1; y<roomsize.Y-1; y++)
+		for(s16 x=1; x<roomsize.X-1; x++)
+		{
+			v3s16 p = roomplace + v3s16(x,y,z);
+			u32 vi = vmanip.m_area.index(p);
+			if(vmanip.m_flags[vi] & VMANIP_FLAG_DUNGEON_INSIDE)
+			{
+				fits = false;
+				break;
+			}
+			if(vmanip.m_data[vi].d == CONTENT_IGNORE)
+			{
+				fits = false;
+				break;
+			}
+		}
+		if(fits)
+			break;
+	}
+	// No place found
+	if(fits == false)
+		return;
+	
+	/*
+		Stores the center position of the last room made, so that
+		a new corridor can be started from the last room instead of
+		the new room, if chosen so.
+	*/
+	v3s16 last_room_center = roomplace+v3s16(roomsize.X/2,1,roomsize.Z/2);
+	
+	u32 room_count = random.range(2,7);
+	for(u32 i=0; i<room_count; i++)
+	{
+		// Make a room to the determined place
+		make_room1(vmanip, roomsize, roomplace);
+		
+		v3s16 room_center = roomplace + v3s16(roomsize.X/2,1,roomsize.Z/2);
+
+		// Place torch at room center (for testing)
+		//vmanip.m_data[vmanip.m_area.index(room_center)] = MapNode(CONTENT_TORCH);
+
+		// Quit if last room
+		if(i == room_count-1)
+			break;
+		
+		// Determine walker start position
+
+		bool start_in_last_room = (random.range(0,1)==0);
+		//bool start_in_last_room = true;
+
+		v3s16 walker_start_place;
+
+		if(start_in_last_room)
+		{
+			walker_start_place = last_room_center;
+		}
+		else
+		{
+			walker_start_place = room_center;
+			// Store center of current room as the last one
+			last_room_center = room_center;
+		}
+		
+		// Create walker and find a place for a door
+		RoomWalker walker(vmanip, walker_start_place, random);
+		v3s16 doorplace;
+		v3s16 doordir;
+		bool r = walker.findPlaceForDoor(doorplace, doordir);
+		if(r == false)
+			return;
+		
+		if(random.range(0,1)==0)
+			// Make the door
+			make_door1(vmanip, doorplace, doordir);
+		else
+			// Don't actually make a door
+			doorplace -= doordir;
+		
+		// Make a random corridor starting from the door
+		v3s16 corridor_end;
+		v3s16 corridor_end_dir;
+		make_corridor(vmanip, doorplace, doordir, corridor_end,
+				corridor_end_dir, random);
+		
+		// Find a place for a random sized room
+		roomsize = v3s16(random.range(4,8),random.range(4,6),random.range(4,8));
+		walker.setPos(corridor_end);
+		walker.setDir(corridor_end_dir);
+		r = walker.findPlaceForRoomDoor(roomsize, doorplace, doordir, roomplace);
+		if(r == false)
+			return;
+
+		if(random.range(0,1)==0)
+			// Make the door
+			make_door1(vmanip, doorplace, doordir);
+		else
+			// Don't actually make a door
+			roomplace -= doordir;
+		
+	}
+}
+
+/*
+	Noise functions. Make sure seed is mangled differently in each one.
+*/
+
+// This affects the shape of the contour
+//#define CAVE_NOISE_SCALE 10.0
+//#define CAVE_NOISE_SCALE 7.5
+#define CAVE_NOISE_SCALE 5.0
+
+NoiseParams get_cave_noise1_params(u64 seed)
+{
+	/*return NoiseParams(NOISE_PERLIN_CONTOUR, seed+52534, 5, 0.7,
+			200, CAVE_NOISE_SCALE);*/
+	return NoiseParams(NOISE_PERLIN_CONTOUR, seed+52534, 4, 0.7,
+			100, CAVE_NOISE_SCALE);
+}
+
+NoiseParams get_cave_noise2_params(u64 seed)
+{
+	/*return NoiseParams(NOISE_PERLIN_CONTOUR_FLIP_YZ, seed+10325, 5, 0.7,
+			200, CAVE_NOISE_SCALE);*/
+	return NoiseParams(NOISE_PERLIN_CONTOUR_FLIP_YZ, seed+10325, 4, 0.7,
+			100, CAVE_NOISE_SCALE);
+}
+
+//#define CAVE_NOISE_THRESHOLD (2.5/CAVE_NOISE_SCALE)
+#define CAVE_NOISE_THRESHOLD (2.0/CAVE_NOISE_SCALE)
+
+NoiseParams get_ground_noise1_params(u64 seed)
+{
+	return NoiseParams(NOISE_PERLIN, seed+983240, 5,
+			0.60, 100.0, 30.0);
+}
+
+NoiseParams get_ground_crumbleness_params(u64 seed)
+{
+	return NoiseParams(NOISE_PERLIN, seed+34413, 3,
+			1.3, 20.0, 1.0);
+}
+
+NoiseParams get_ground_wetness_params(u64 seed)
+{
+	return NoiseParams(NOISE_PERLIN, seed+32474, 4,
+			1.1, 40.0, 1.0);
+}
+
+bool is_cave(u64 seed, v3s16 p)
+{
+	double d1 = noise3d_param(get_cave_noise1_params(seed), p.X,p.Y,p.Z);
+	double d2 = noise3d_param(get_cave_noise2_params(seed), p.X,p.Y,p.Z);
+	return d1*d2 > CAVE_NOISE_THRESHOLD;
+}
+
+/*
+	Ground density noise shall be interpreted by using this.
+
+	TODO: No perlin noises here, they should be outsourced
+	      and buffered
+		  NOTE: The speed of these actually isn't terrible
+*/
+bool val_is_ground(double ground_noise1_val, v3s16 p, u64 seed)
+{
+	//return ((double)p.Y < ground_noise1_val);
+
+	double f = 0.8 + noise2d_perlin(
+			0.5+(float)p.X/250, 0.5+(float)p.Z/250,
+			seed+920381, 3, 0.5);
+	if(f < 0.01)
+		f = 0.01;
+	else if(f >= 1.0)
+		f *= 2.0;
+	double h = WATER_LEVEL + 10 * noise2d_perlin(
+			0.5+(float)p.X/250, 0.5+(float)p.Z/250,
+			seed+84174, 4, 0.5);
+	/*double f = 1;
+	double h = 0;*/
+	return ((double)p.Y - h < ground_noise1_val * f);
+}
+
+/*
+	Queries whether a position is ground or not.
+*/
+bool is_ground(u64 seed, v3s16 p)
+{
+	double val1 = noise3d_param(get_ground_noise1_params(seed), p.X,p.Y,p.Z);
+	return val_is_ground(val1, p, seed);
+}
+
+// Amount of trees per area in nodes
+double tree_amount_2d(u64 seed, v2s16 p)
+{
+	/*double noise = noise2d_perlin(
+			0.5+(float)p.X/250, 0.5+(float)p.Y/250,
+			seed+2, 5, 0.66);*/
+	double noise = noise2d_perlin(
+			0.5+(float)p.X/125, 0.5+(float)p.Y/125,
+			seed+2, 4, 0.66);
+	double zeroval = -0.35;
+	if(noise < zeroval)
+		return 0;
+	else
+		return 0.04 * (noise-zeroval) / (1.0-zeroval);
+}
+
+#if 0
+double randomstone_amount_2d(u64 seed, v2s16 p)
+{
+	double noise = noise2d_perlin(
+			0.5+(float)p.X/250, 0.5+(float)p.Y/250,
+			seed+3829434, 5, 0.66);
+	double zeroval = 0.1;
+	if(noise < zeroval)
+		return 0;
+	else
+		return 0.01 * (noise-zeroval) / (1.0-zeroval);
+}
+#endif
+
+double largestone_amount_2d(u64 seed, v2s16 p)
+{
+	double noise = noise2d_perlin(
+			0.5+(float)p.X/250, 0.5+(float)p.Y/250,
+			seed+14143242, 5, 0.66);
+	double zeroval = 0.3;
+	if(noise < zeroval)
+		return 0;
+	else
+		return 0.005 * (noise-zeroval) / (1.0-zeroval);
+}
+
+/*
+	Incrementally find ground level from 3d noise
+*/
+s16 find_ground_level_from_noise(u64 seed, v2s16 p2d, s16 precision)
+{
+	// Start a bit fuzzy to make averaging lower precision values
+	// more useful
+	s16 level = myrand_range(-precision/2, precision/2);
+	s16 dec[] = {31000, 100, 20, 4, 1, 0};
+	s16 i;
+	for(i = 1; dec[i] != 0 && precision <= dec[i]; i++)
+	{
+		// First find non-ground by going upwards
+		// Don't stop in caves.
+		{
+			s16 max = level+dec[i-1]*2;
+			v3s16 p(p2d.X, level, p2d.Y);
+			for(; p.Y < max; p.Y += dec[i])
+			{
+				if(!is_ground(seed, p))
+				{
+					level = p.Y;
+					break;
+				}
+			}
+		}
+		// Then find ground by going downwards from there.
+		// Go in caves, too, when precision is 1.
+		{
+			s16 min = level-dec[i-1]*2;
+			v3s16 p(p2d.X, level, p2d.Y);
+			for(; p.Y>min; p.Y-=dec[i])
+			{
+				bool ground = is_ground(seed, p);
+				/*if(dec[i] == 1 && is_cave(seed, p))
+					ground = false;*/
+				if(ground)
+				{
+					level = p.Y;
+					break;
+				}
+			}
+		}
+	}
+	
+	// This is more like the actual ground level
+	level += dec[i-1]/2;
+
+	return level;
+}
+
+double get_sector_average_ground_level(u64 seed, v2s16 sectorpos, double p=4);
+
+double get_sector_average_ground_level(u64 seed, v2s16 sectorpos, double p)
+{
+	v2s16 node_min = sectorpos*MAP_BLOCKSIZE;
+	v2s16 node_max = (sectorpos+v2s16(1,1))*MAP_BLOCKSIZE-v2s16(1,1);
+	double a = 0;
+	a += find_ground_level_from_noise(seed,
+			v2s16(node_min.X, node_min.Y), p);
+	a += find_ground_level_from_noise(seed,
+			v2s16(node_min.X, node_max.Y), p);
+	a += find_ground_level_from_noise(seed,
+			v2s16(node_max.X, node_max.Y), p);
+	a += find_ground_level_from_noise(seed,
+			v2s16(node_max.X, node_min.Y), p);
+	a += find_ground_level_from_noise(seed,
+			v2s16(node_min.X+MAP_BLOCKSIZE/2, node_min.Y+MAP_BLOCKSIZE/2), p);
+	a /= 5;
+	return a;
+}
+
+double get_sector_maximum_ground_level(u64 seed, v2s16 sectorpos, double p=4);
+
+double get_sector_maximum_ground_level(u64 seed, v2s16 sectorpos, double p)
+{
+	v2s16 node_min = sectorpos*MAP_BLOCKSIZE;
+	v2s16 node_max = (sectorpos+v2s16(1,1))*MAP_BLOCKSIZE-v2s16(1,1);
+	double a = -31000;
+	a = MYMAX(a, find_ground_level_from_noise(seed,
+			v2s16(node_min.X, node_min.Y), p));
+	a = MYMAX(a, find_ground_level_from_noise(seed,
+			v2s16(node_min.X, node_max.Y), p));
+	a = MYMAX(a, find_ground_level_from_noise(seed,
+			v2s16(node_max.X, node_max.Y), p));
+	a = MYMAX(a, find_ground_level_from_noise(seed,
+			v2s16(node_min.X, node_min.Y), p));
+	a = MYMAX(a, find_ground_level_from_noise(seed,
+			v2s16(node_min.X+MAP_BLOCKSIZE/2, node_min.Y+MAP_BLOCKSIZE/2), p));
+	return a;
+}
+
+double get_sector_minimum_ground_level(u64 seed, v2s16 sectorpos, double p=4);
+
+double get_sector_minimum_ground_level(u64 seed, v2s16 sectorpos, double p)
+{
+	v2s16 node_min = sectorpos*MAP_BLOCKSIZE;
+	v2s16 node_max = (sectorpos+v2s16(1,1))*MAP_BLOCKSIZE-v2s16(1,1);
+	double a = 31000;
+	a = MYMIN(a, find_ground_level_from_noise(seed,
+			v2s16(node_min.X, node_min.Y), p));
+	a = MYMIN(a, find_ground_level_from_noise(seed,
+			v2s16(node_min.X, node_max.Y), p));
+	a = MYMIN(a, find_ground_level_from_noise(seed,
+			v2s16(node_max.X, node_max.Y), p));
+	a = MYMIN(a, find_ground_level_from_noise(seed,
+			v2s16(node_min.X, node_min.Y), p));
+	a = MYMIN(a, find_ground_level_from_noise(seed,
+			v2s16(node_min.X+MAP_BLOCKSIZE/2, node_min.Y+MAP_BLOCKSIZE/2), p));
+	return a;
+}
+
+bool block_is_underground(u64 seed, v3s16 blockpos)
+{
+	s16 minimum_groundlevel = (s16)get_sector_minimum_ground_level(
+			seed, v2s16(blockpos.X, blockpos.Z));
+	
+	if(blockpos.Y*MAP_BLOCKSIZE + MAP_BLOCKSIZE <= minimum_groundlevel)
+		return true;
+	else
+		return false;
+}
+
+#if 0
+#define AVERAGE_MUD_AMOUNT 4
+
+double base_rock_level_2d(u64 seed, v2s16 p)
+{
+	// The base ground level
+	double base = (double)WATER_LEVEL - (double)AVERAGE_MUD_AMOUNT
+			+ 20. * noise2d_perlin(
+			0.5+(float)p.X/500., 0.5+(float)p.Y/500.,
+			(seed>>32)+654879876, 6, 0.6);
+
+	/*// A bit hillier one
+	double base2 = WATER_LEVEL - 4.0 + 40. * noise2d_perlin(
+			0.5+(float)p.X/250., 0.5+(float)p.Y/250.,
+			(seed>>27)+90340, 6, 0.69);
+	if(base2 > base)
+		base = base2;*/
+#if 1
+	// Higher ground level
+	double higher = (double)WATER_LEVEL + 25. + 35. * noise2d_perlin(
+			0.5+(float)p.X/250., 0.5+(float)p.Y/250.,
+			seed+85039, 5, 0.69);
+	//higher = 30; // For debugging
+
+	// Limit higher to at least base
+	if(higher < base)
+		higher = base;
+
+	// Steepness factor of cliffs
+	double b = 1.0 + 1.0 * noise2d_perlin(
+			0.5+(float)p.X/250., 0.5+(float)p.Y/250.,
+			seed-932, 7, 0.7);
+	b = rangelim(b, 0.0, 1000.0);
+	b = pow(b, 5);
+	b *= 7;
+	b = rangelim(b, 3.0, 1000.0);
+	//dstream<<"b="<<b<<std::endl;
+	//double b = 20;
+
+	// Offset to more low
+	double a_off = -0.2;
+	// High/low selector
+	/*double a = 0.5 + b * (a_off + noise2d_perlin(
+			0.5+(float)p.X/500., 0.5+(float)p.Y/500.,
+			seed-359, 6, 0.7));*/
+	double a = (double)0.5 + b * (a_off + noise2d_perlin(
+			0.5+(float)p.X/250., 0.5+(float)p.Y/250.,
+			seed-359, 5, 0.60));
+	// Limit
+	a = rangelim(a, 0.0, 1.0);
+
+	//dstream<<"a="<<a<<std::endl;
+
+	double h = base*(1.0-a) + higher*a;
+#else
+	double h = base;
+#endif
+	return h;
+}
+
+double get_mud_add_amount(u64 seed, v2s16 p)
+{
+	return ((float)AVERAGE_MUD_AMOUNT + 3.0 * noise2d_perlin(
+			0.5+(float)p.X/200, 0.5+(float)p.Y/200,
+			seed+91013, 3, 0.55));
+}
+#endif
+
+bool get_have_sand(u64 seed, v2s16 p2d)
+{
+	// Determine whether to have sand here
+	double sandnoise = noise2d_perlin(
+			0.5+(float)p2d.X/500, 0.5+(float)p2d.Y/500,
+			seed+59420, 3, 0.50);
+
+	return (sandnoise > -0.15);
+}
+
+/*
+	Adds random objects to block, depending on the content of the block
+*/
+void add_random_objects(MapBlock *block)
+{
+	for(s16 z0=0; z0<MAP_BLOCKSIZE; z0++)
+	for(s16 x0=0; x0<MAP_BLOCKSIZE; x0++)
+	{
+		bool last_node_walkable = false;
+		for(s16 y0=0; y0<MAP_BLOCKSIZE; y0++)
+		{
+			v3s16 p(x0,y0,z0);
+			MapNode n = block->getNodeNoEx(p);
+			if(n.d == CONTENT_IGNORE)
+				continue;
+			if(content_features(n.d).liquid_type != LIQUID_NONE)
+				continue;
+			if(content_features(n.d).walkable)
+			{
+				last_node_walkable = true;
+				continue;
+			}
+			if(last_node_walkable)
+			{
+				// If block contains light information
+				if(content_features(n.d).param_type == CPT_LIGHT)
+				{
+					if(n.getLight(LIGHTBANK_DAY) <= 3)
+					{
+						if(myrand() % 300 == 0)
+						{
+							v3f pos_f = intToFloat(p+block->getPosRelative(), BS);
+							pos_f.Y -= BS*0.4;
+							ServerActiveObject *obj = new RatSAO(NULL, 0, pos_f);
+							std::string data = obj->getStaticData();
+							StaticObject s_obj(obj->getType(),
+									obj->getBasePosition(), data);
+							// Add some
+							block->m_static_objects.insert(0, s_obj);
+							block->m_static_objects.insert(0, s_obj);
+							block->m_static_objects.insert(0, s_obj);
+							block->m_static_objects.insert(0, s_obj);
+							block->m_static_objects.insert(0, s_obj);
+							block->m_static_objects.insert(0, s_obj);
+							delete obj;
+						}
+						if(myrand() % 1000 == 0)
+						{
+							v3f pos_f = intToFloat(p+block->getPosRelative(), BS);
+							pos_f.Y -= BS*0.4;
+							ServerActiveObject *obj = new Oerkki1SAO(NULL,0,pos_f);
+							std::string data = obj->getStaticData();
+							StaticObject s_obj(obj->getType(),
+									obj->getBasePosition(), data);
+							// Add one
+							block->m_static_objects.insert(0, s_obj);
+							delete obj;
+						}
+					}
+				}
+			}
+			last_node_walkable = false;
+		}
+	}
+	block->setChangedFlag();
+}
+
+void make_block(BlockMakeData *data)
+{
+	if(data->no_op)
+	{
+		dstream<<"makeBlock: no-op"<<std::endl;
+		return;
+	}
+
+	v3s16 blockpos = data->blockpos;
+	
+	/*dstream<<"makeBlock(): ("<<blockpos.X<<","<<blockpos.Y<<","
+			<<blockpos.Z<<")"<<std::endl;*/
+
+	ManualMapVoxelManipulator &vmanip = *(data->vmanip);
+	v3s16 blockpos_min = blockpos - v3s16(1,1,1);
+	v3s16 blockpos_max = blockpos + v3s16(1,1,1);
+	// Area of center block
+	v3s16 node_min = blockpos*MAP_BLOCKSIZE;
+	v3s16 node_max = (blockpos+v3s16(1,1,1))*MAP_BLOCKSIZE-v3s16(1,1,1);
+	// Full allocated area
+	v3s16 full_node_min = (blockpos-1)*MAP_BLOCKSIZE;
+	v3s16 full_node_max = (blockpos+2)*MAP_BLOCKSIZE-v3s16(1,1,1);
+	// Area of a block
+	double block_area_nodes = MAP_BLOCKSIZE*MAP_BLOCKSIZE;
+
+	v2s16 p2d_center(node_min.X+MAP_BLOCKSIZE/2, node_min.Z+MAP_BLOCKSIZE/2);
+
+	/*
+		Get average ground level from noise
+	*/
+	
+	s16 approx_groundlevel = (s16)get_sector_average_ground_level(
+			data->seed, v2s16(blockpos.X, blockpos.Z));
+	//dstream<<"approx_groundlevel="<<approx_groundlevel<<std::endl;
+	
+	s16 approx_ground_depth = approx_groundlevel - (node_min.Y+MAP_BLOCKSIZE/2);
+	
+	s16 minimum_groundlevel = (s16)get_sector_minimum_ground_level(
+			data->seed, v2s16(blockpos.X, blockpos.Z));
+	// Minimum amount of ground above the top of the central block
+	s16 minimum_ground_depth = minimum_groundlevel - node_max.Y;
+
+	s16 maximum_groundlevel = (s16)get_sector_maximum_ground_level(
+			data->seed, v2s16(blockpos.X, blockpos.Z), 1);
+	// Maximum amount of ground above the bottom of the central block
+	s16 maximum_ground_depth = maximum_groundlevel - node_min.Y;
+	
+	/*
+		Special case for high air or water: Just fill with air and water.
+	*/
+	if(maximum_ground_depth < -20)
+	{
+		for(s16 x=node_min.X; x<=node_max.X; x++)
+		for(s16 z=node_min.Z; z<=node_max.Z; z++)
+		{
+			// Node position
+			v2s16 p2d(x,z);
+			{
+				// Use fast index incrementing
+				v3s16 em = vmanip.m_area.getExtent();
+				u32 i = vmanip.m_area.index(v3s16(p2d.X, node_min.Y, p2d.Y));
+				for(s16 y=node_min.Y; y<=node_max.Y; y++)
+				{
+					// Only modify places that have no content
+					if(vmanip.m_data[i].d == CONTENT_IGNORE)
+					{
+						if(y <= WATER_LEVEL)
+							vmanip.m_data[i] = MapNode(CONTENT_WATERSOURCE);
+						else
+							vmanip.m_data[i] = MapNode(CONTENT_AIR);
+					}
+				
+					data->vmanip->m_area.add_y(em, i, 1);
+				}
+			}
+		}
+		
+		// We're done
+		return;
+	}
+
+	/*
+		If block is deep underground, this is set to true and ground
+		density noise is not generated, for speed optimization.
+	*/
+	bool all_is_ground_except_caves = (minimum_ground_depth > 16);
+	
+	/*
+		Create a block-specific seed
+	*/
+	u32 blockseed = (data->seed%0x100000000) + full_node_min.Z*38134234
+			+ full_node_min.Y*42123 + full_node_min.X*23;
+	
+	/*
+		Make some 3D noise
+	*/
+	
+	//NoiseBuffer noisebuf1;
+	//NoiseBuffer noisebuf2;
+	NoiseBuffer noisebuf_cave;
+	NoiseBuffer noisebuf_ground;
+	NoiseBuffer noisebuf_ground_crumbleness;
+	NoiseBuffer noisebuf_ground_wetness;
+	{
+		v3f minpos_f(node_min.X, node_min.Y, node_min.Z);
+		v3f maxpos_f(node_max.X, node_max.Y, node_max.Z);
+
+		//TimeTaker timer("noisebuf.create");
+
+		/*
+			Cave noise
+		*/
+
+		noisebuf_cave.create(get_cave_noise1_params(data->seed),
+				minpos_f.X, minpos_f.Y, minpos_f.Z,
+				maxpos_f.X, maxpos_f.Y, maxpos_f.Z,
+				4, 3, 4);
+		
+		noisebuf_cave.multiply(get_cave_noise2_params(data->seed));
+
+		/*
+			Ground noise
+		*/
+		
+		// Sample length
+		v3f sl = v3f(4.0, 4.0, 4.0);
+		
+		/*
+			Density noise
+		*/
+		if(all_is_ground_except_caves == false)
+			//noisebuf_ground.create(data->seed+983240, 6, 0.60, false,
+			noisebuf_ground.create(get_ground_noise1_params(data->seed),
+					minpos_f.X, minpos_f.Y, minpos_f.Z,
+					maxpos_f.X, maxpos_f.Y, maxpos_f.Z,
+					sl.X, sl.Y, sl.Z);
+		
+		/*
+			Ground property noise
+		*/
+		sl = v3f(2.5, 2.5, 2.5);
+		noisebuf_ground_crumbleness.create(
+				get_ground_crumbleness_params(data->seed),
+				minpos_f.X, minpos_f.Y, minpos_f.Z,
+				maxpos_f.X, maxpos_f.Y+5, maxpos_f.Z,
+				sl.X, sl.Y, sl.Z);
+		noisebuf_ground_wetness.create(
+				get_ground_wetness_params(data->seed),
+				minpos_f.X, minpos_f.Y, minpos_f.Z,
+				maxpos_f.X, maxpos_f.Y+5, maxpos_f.Z,
+				sl.X, sl.Y, sl.Z);
+	}
+	
+	/*
+		Make base ground level
+	*/
+
+	for(s16 x=node_min.X; x<=node_max.X; x++)
+	for(s16 z=node_min.Z; z<=node_max.Z; z++)
+	{
+		// Node position
+		v2s16 p2d(x,z);
+		{
+			// Use fast index incrementing
+			v3s16 em = vmanip.m_area.getExtent();
+			u32 i = vmanip.m_area.index(v3s16(p2d.X, node_min.Y, p2d.Y));
+			for(s16 y=node_min.Y; y<=node_max.Y; y++)
+			{
+				// Only modify places that have no content
+				if(vmanip.m_data[i].d == CONTENT_IGNORE)
+				{
+					// First priority: make air and water.
+					// This avoids caves inside water.
+					if(all_is_ground_except_caves == false
+							&& val_is_ground(noisebuf_ground.get(x,y,z),
+							v3s16(x,y,z), data->seed) == false)
+					{
+						if(y <= WATER_LEVEL)
+							vmanip.m_data[i] = MapNode(CONTENT_WATERSOURCE);
+						else
+							vmanip.m_data[i] = MapNode(CONTENT_AIR);
+					}
+					else if(noisebuf_cave.get(x,y,z) > CAVE_NOISE_THRESHOLD)
+						vmanip.m_data[i] = MapNode(CONTENT_AIR);
+					else
+						vmanip.m_data[i] = MapNode(CONTENT_STONE);
+				}
+			
+				data->vmanip->m_area.add_y(em, i, 1);
+			}
+		}
+	}
+
+	/*
+		Add minerals
+	*/
+
+	{
+		PseudoRandom mineralrandom(blockseed);
+
+		/*
+			Add meseblocks
+		*/
+		for(s16 i=0; i<approx_ground_depth/4; i++)
+		{
+			if(mineralrandom.next()%50 == 0)
+			{
+				s16 x = mineralrandom.range(node_min.X+1, node_max.X-1);
+				s16 y = mineralrandom.range(node_min.Y+1, node_max.Y-1);
+				s16 z = mineralrandom.range(node_min.Z+1, node_max.Z-1);
+				for(u16 i=0; i<27; i++)
+				{
+					v3s16 p = v3s16(x,y,z) + g_27dirs[i];
+					u32 vi = vmanip.m_area.index(p);
+					if(vmanip.m_data[vi].d == CONTENT_STONE)
+						if(mineralrandom.next()%8 == 0)
+							vmanip.m_data[vi] = MapNode(CONTENT_MESE);
+				}
+					
+			}
+		}
+		/*
+			Add others
+		*/
+		{
+			u16 a = mineralrandom.range(0,15);
+			a = a*a*a;
+			u16 amount = 20 * a/1000;
+			for(s16 i=0; i<amount; i++)
+			{
+				s16 x = mineralrandom.range(node_min.X+1, node_max.X-1);
+				s16 y = mineralrandom.range(node_min.Y+1, node_max.Y-1);
+				s16 z = mineralrandom.range(node_min.Z+1, node_max.Z-1);
+
+				u8 base_content = CONTENT_STONE;
+				MapNode new_content(CONTENT_IGNORE);
+				u32 sparseness = 6;
+
+				if(noisebuf_ground_crumbleness.get(x,y+5,z) < -0.1)
+				{
+					new_content = MapNode(CONTENT_STONE, MINERAL_COAL);
+				}
+				else
+				{
+					if(noisebuf_ground_wetness.get(x,y+5,z) > 0.0)
+						new_content = MapNode(CONTENT_STONE, MINERAL_IRON);
+					/*if(noisebuf_ground_wetness.get(x,y,z) > 0.0)
+						vmanip.m_data[i] = MapNode(CONTENT_MUD);
+					else
+						vmanip.m_data[i] = MapNode(CONTENT_SAND);*/
+				}
+				/*else if(noisebuf_ground_crumbleness.get(x,y,z) > 0.1)
+				{
+				}*/
+
+				if(new_content.d != CONTENT_IGNORE)
+				{
+					for(u16 i=0; i<27; i++)
+					{
+						v3s16 p = v3s16(x,y,z) + g_27dirs[i];
+						u32 vi = vmanip.m_area.index(p);
+						if(vmanip.m_data[vi].d == base_content)
+						{
+							if(mineralrandom.next()%sparseness == 0)
+								vmanip.m_data[vi] = new_content;
+						}
+					}
+				}
+			}
+		}
+		/*
+			Add coal
+		*/
+		//for(s16 i=0; i < MYMAX(0, 50 - abs(node_min.Y+8 - (-30))); i++)
+		//for(s16 i=0; i<50; i++)
+		u16 coal_amount = 30;
+		u16 coal_rareness = 60 / coal_amount;
+		if(coal_rareness == 0)
+			coal_rareness = 1;
+		if(mineralrandom.next()%coal_rareness == 0)
+		{
+			u16 a = mineralrandom.next() % 16;
+			u16 amount = coal_amount * a*a*a / 1000;
+			for(s16 i=0; i<amount; i++)
+			{
+				s16 x = mineralrandom.range(node_min.X+1, node_max.X-1);
+				s16 y = mineralrandom.range(node_min.Y+1, node_max.Y-1);
+				s16 z = mineralrandom.range(node_min.Z+1, node_max.Z-1);
+				for(u16 i=0; i<27; i++)
+				{
+					v3s16 p = v3s16(x,y,z) + g_27dirs[i];
+					u32 vi = vmanip.m_area.index(p);
+					if(vmanip.m_data[vi].d == CONTENT_STONE)
+						if(mineralrandom.next()%8 == 0)
+							vmanip.m_data[vi] = MapNode(CONTENT_STONE, MINERAL_COAL);
+				}
+			}
+		}
+		/*
+			Add iron
+		*/
+		u16 iron_amount = 8;
+		u16 iron_rareness = 60 / iron_amount;
+		if(iron_rareness == 0)
+			iron_rareness = 1;
+		if(mineralrandom.next()%iron_rareness == 0)
+		{
+			u16 a = mineralrandom.next() % 16;
+			u16 amount = iron_amount * a*a*a / 1000;
+			for(s16 i=0; i<amount; i++)
+			{
+				s16 x = mineralrandom.range(node_min.X+1, node_max.X-1);
+				s16 y = mineralrandom.range(node_min.Y+1, node_max.Y-1);
+				s16 z = mineralrandom.range(node_min.Z+1, node_max.Z-1);
+				for(u16 i=0; i<27; i++)
+				{
+					v3s16 p = v3s16(x,y,z) + g_27dirs[i];
+					u32 vi = vmanip.m_area.index(p);
+					if(vmanip.m_data[vi].d == CONTENT_STONE)
+						if(mineralrandom.next()%8 == 0)
+							vmanip.m_data[vi] = MapNode(CONTENT_STONE, MINERAL_IRON);
+				}
+			}
+		}
+	}
+
+	/*
+		Add mud and sand and others underground (in place of stone)
+	*/
+
+	for(s16 x=node_min.X; x<=node_max.X; x++)
+	for(s16 z=node_min.Z; z<=node_max.Z; z++)
+	{
+		// Node position
+		v2s16 p2d(x,z);
+		{
+			// Use fast index incrementing
+			v3s16 em = vmanip.m_area.getExtent();
+			u32 i = vmanip.m_area.index(v3s16(p2d.X, node_max.Y, p2d.Y));
+			for(s16 y=node_max.Y; y>=node_min.Y; y--)
+			{
+				if(vmanip.m_data[i].d == CONTENT_STONE)
+				{
+					if(noisebuf_ground_crumbleness.get(x,y,z) > 1.3)
+					{
+						if(noisebuf_ground_wetness.get(x,y,z) > 0.0)
+							vmanip.m_data[i] = MapNode(CONTENT_MUD);
+						else
+							vmanip.m_data[i] = MapNode(CONTENT_SAND);
+					}
+					else if(noisebuf_ground_crumbleness.get(x,y,z) > 0.7)
+					{
+						if(noisebuf_ground_wetness.get(x,y,z) < -0.6)
+							vmanip.m_data[i] = MapNode(CONTENT_GRAVEL);
+					}
+				}
+
+				data->vmanip->m_area.add_y(em, i, -1);
+			}
+		}
+	}
+
+	/*
+		Add dungeons
+	*/
+	
+	//if(node_min.Y < approx_groundlevel)
+	//if(myrand() % 3 == 0)
+	//if(myrand() % 3 == 0 && node_min.Y < approx_groundlevel)
+	//if(myrand() % 100 == 0 && node_min.Y < approx_groundlevel)
+	//float dungeon_rarity = g_settings.getFloat("dungeon_rarity");
+	float dungeon_rarity = 0.02;
+	if(((noise3d(blockpos.X,blockpos.Y,blockpos.Z,data->seed)+1.0)/2.0)
+			< dungeon_rarity
+			&& node_min.Y < approx_groundlevel)
+	{
+		// Dungeon generator doesn't modify places which have this set
+		data->vmanip->clearFlag(VMANIP_FLAG_DUNGEON_INSIDE
+				| VMANIP_FLAG_DUNGEON_PRESERVE);
+		
+		// Set all air and water to be untouchable to make dungeons open
+		// to caves and open air
+		for(s16 x=full_node_min.X; x<=full_node_max.X; x++)
+		for(s16 z=full_node_min.Z; z<=full_node_max.Z; z++)
+		{
+			// Node position
+			v2s16 p2d(x,z);
+			{
+				// Use fast index incrementing
+				v3s16 em = vmanip.m_area.getExtent();
+				u32 i = vmanip.m_area.index(v3s16(p2d.X, full_node_max.Y, p2d.Y));
+				for(s16 y=full_node_max.Y; y>=full_node_min.Y; y--)
+				{
+					if(vmanip.m_data[i].d == CONTENT_AIR)
+						vmanip.m_flags[i] |= VMANIP_FLAG_DUNGEON_PRESERVE;
+					else if(vmanip.m_data[i].d == CONTENT_WATERSOURCE)
+						vmanip.m_flags[i] |= VMANIP_FLAG_DUNGEON_PRESERVE;
+					data->vmanip->m_area.add_y(em, i, -1);
+				}
+			}
+		}
+		
+		PseudoRandom random(blockseed+2);
+
+		// Add it
+		make_dungeon1(vmanip, random);
+		
+		// Convert some cobble to mossy cobble
+		for(s16 x=full_node_min.X; x<=full_node_max.X; x++)
+		for(s16 z=full_node_min.Z; z<=full_node_max.Z; z++)
+		{
+			// Node position
+			v2s16 p2d(x,z);
+			{
+				// Use fast index incrementing
+				v3s16 em = vmanip.m_area.getExtent();
+				u32 i = vmanip.m_area.index(v3s16(p2d.X, full_node_max.Y, p2d.Y));
+				for(s16 y=full_node_max.Y; y>=full_node_min.Y; y--)
+				{
+					// (noisebuf not used because it doesn't contain the
+					//  full area)
+					double wetness = noise3d_param(
+							get_ground_wetness_params(data->seed), x,y,z);
+					double d = noise3d_perlin((float)x/2.5,
+							(float)y/2.5,(float)z/2.5,
+							blockseed, 2, 1.4);
+					if(vmanip.m_data[i].d == CONTENT_COBBLE)
+					{
+						if(d < wetness/3.0)
+						{
+							vmanip.m_data[i].d = CONTENT_MOSSYCOBBLE;
+						}
+					}
+					/*else if(vmanip.m_flags[i] & VMANIP_FLAG_DUNGEON_INSIDE)
+					{
+						if(wetness > 1.2)
+							vmanip.m_data[i].d = CONTENT_MUD;
+					}*/
+					data->vmanip->m_area.add_y(em, i, -1);
+				}
+			}
+		}
+	}
+	
+	/*
+		Add top and bottom side of water to transforming_liquid queue
+	*/
+
+	for(s16 x=node_min.X; x<=node_max.X; x++)
+	for(s16 z=node_min.Z; z<=node_max.Z; z++)
+	{
+		// Node position
+		v2s16 p2d(x,z);
+		{
+			bool water_found = false;
+			// Use fast index incrementing
+			v3s16 em = vmanip.m_area.getExtent();
+			u32 i = vmanip.m_area.index(v3s16(p2d.X, node_max.Y, p2d.Y));
+			for(s16 y=node_max.Y; y>=node_min.Y; y--)
+			{
+				if(water_found == false)
+				{
+					if(vmanip.m_data[i].d == CONTENT_WATERSOURCE)
+					{
+						v3s16 p = v3s16(p2d.X, y, p2d.Y);
+						data->transforming_liquid.push_back(p);
+						water_found = true;
+					}
+				}
+				else
+				{
+					// This can be done because water_found can only
+					// turn to true and end up here after going through
+					// a single block.
+					if(vmanip.m_data[i+1].d != CONTENT_WATERSOURCE)
+					{
+						v3s16 p = v3s16(p2d.X, y+1, p2d.Y);
+						data->transforming_liquid.push_back(p);
+						water_found = false;
+					}
+				}
+
+				data->vmanip->m_area.add_y(em, i, -1);
+			}
+		}
+	}
+
+	/*
+		If close to ground level
+	*/
+
+	//if(abs(approx_ground_depth) < 30)
+	if(minimum_ground_depth < 5 && maximum_ground_depth > -5)
+	{
+		/*
+			Add grass and mud
+		*/
+
+		for(s16 x=node_min.X; x<=node_max.X; x++)
+		for(s16 z=node_min.Z; z<=node_max.Z; z++)
+		{
+			// Node position
+			v2s16 p2d(x,z);
+			{
+				bool possibly_have_sand = get_have_sand(data->seed, p2d);
+				bool have_sand = false;
+				u32 current_depth = 0;
+				bool air_detected = false;
+				bool water_detected = false;
+				// Use fast index incrementing
+				s16 start_y = node_max.Y+2;
+				v3s16 em = vmanip.m_area.getExtent();
+				u32 i = vmanip.m_area.index(v3s16(p2d.X, start_y, p2d.Y));
+				for(s16 y=start_y; y>=node_min.Y-3; y--)
+				{
+					if(vmanip.m_data[i].d == CONTENT_WATERSOURCE)
+						water_detected = true;
+					if(vmanip.m_data[i].d == CONTENT_AIR)
+						air_detected = true;
+
+					if((vmanip.m_data[i].d == CONTENT_STONE
+							|| vmanip.m_data[i].d == CONTENT_GRASS
+							|| vmanip.m_data[i].d == CONTENT_MUD
+							|| vmanip.m_data[i].d == CONTENT_SAND
+							|| vmanip.m_data[i].d == CONTENT_GRAVEL
+							) && (air_detected || water_detected))
+					{
+						if(current_depth == 0 && y <= WATER_LEVEL+2
+								&& possibly_have_sand)
+							have_sand = true;
+						
+						if(current_depth < 4)
+						{
+							if(have_sand)
+							{
+								vmanip.m_data[i] = MapNode(CONTENT_SAND);
+							}
+							#if 1
+							else if(current_depth==0 && !water_detected
+									&& y >= WATER_LEVEL && air_detected)
+								vmanip.m_data[i] = MapNode(CONTENT_GRASS);
+							#endif
+							else
+								vmanip.m_data[i] = MapNode(CONTENT_MUD);
+						}
+						else
+						{
+							if(vmanip.m_data[i].d == CONTENT_MUD
+								|| vmanip.m_data[i].d == CONTENT_GRASS)
+								vmanip.m_data[i] = MapNode(CONTENT_STONE);
+						}
+
+						current_depth++;
+
+						if(current_depth >= 8)
+							break;
+					}
+					else if(current_depth != 0)
+						break;
+
+					data->vmanip->m_area.add_y(em, i, -1);
+				}
+			}
+		}
+
+		/*
+			Add trees
+		*/
+		
+		// Amount of trees
+		u32 tree_count = block_area_nodes * tree_amount_2d(data->seed, p2d_center);
+		PseudoRandom treerandom(blockseed);
+		// Put trees in random places on part of division
+		for(u32 i=0; i<tree_count; i++)
+		{
+			s16 x = treerandom.range(node_min.X, node_max.X);
+			s16 z = treerandom.range(node_min.Z, node_max.Z);
+			//s16 y = find_ground_level(data->vmanip, v2s16(x,z));
+			s16 y = find_ground_level_from_noise(data->seed, v2s16(x,z), 4);
+			// Don't make a tree under water level
+			if(y < WATER_LEVEL)
+				continue;
+			// Make sure tree fits (only trees whose starting point is
+			// at this block are added)
+			if(y < node_min.Y || y > node_max.Y)
+				continue;
+			/*
+				Find exact ground level
+			*/
+			v3s16 p(x,y+6,z);
+			bool found = false;
+			for(; p.Y >= y-6; p.Y--)
+			{
+				u32 i = data->vmanip->m_area.index(p);
+				MapNode *n = &data->vmanip->m_data[i];
+				if(n->d != CONTENT_AIR && n->d != CONTENT_IGNORE)
+				{
+					found = true;
+					break;
+				}
+			}
+			// If not found, handle next one
+			if(found == false)
+				continue;
+			/*
+				Trees grow only on mud and grass
+			*/
+			{
+				u32 i = data->vmanip->m_area.index(p);
+				MapNode *n = &data->vmanip->m_data[i];
+				if(n->d != CONTENT_MUD && n->d != CONTENT_GRASS)
+					continue;
+			}
+			// Tree will be placed one higher
+			p.Y++;
+			// Make a tree
+			make_tree(vmanip, p);
+		}
+
+#if 0
+		/*
+			Add some kind of random stones
+		*/
+		
+		u32 random_stone_count = block_area_nodes *
+				randomstone_amount_2d(data->seed, p2d_center);
+		// Put in random places on part of division
+		for(u32 i=0; i<random_stone_count; i++)
+		{
+			s16 x = myrand_range(node_min.X, node_max.X);
+			s16 z = myrand_range(node_min.Z, node_max.Z);
+			s16 y = find_ground_level_from_noise(data->seed, v2s16(x,z), 1);
+			// Don't add under water level
+			/*if(y < WATER_LEVEL)
+				continue;*/
+			// Don't add if doesn't belong to this block
+			if(y < node_min.Y || y > node_max.Y)
+				continue;
+			v3s16 p(x,y,z);
+			// Filter placement
+			/*{
+				u32 i = data->vmanip->m_area.index(v3s16(p));
+				MapNode *n = &data->vmanip->m_data[i];
+				if(n->d != CONTENT_MUD && n->d != CONTENT_GRASS)
+					continue;
+			}*/
+			// Will be placed one higher
+			p.Y++;
+			// Add it
+			make_randomstone(data->vmanip, p);
+		}
+#endif
+
+#if 0
+		/*
+			Add larger stones
+		*/
+		
+		u32 large_stone_count = block_area_nodes *
+				largestone_amount_2d(data->seed, p2d_center);
+		//u32 large_stone_count = 1;
+		// Put in random places on part of division
+		for(u32 i=0; i<large_stone_count; i++)
+		{
+			s16 x = myrand_range(node_min.X, node_max.X);
+			s16 z = myrand_range(node_min.Z, node_max.Z);
+			s16 y = find_ground_level_from_noise(data->seed, v2s16(x,z), 1);
+			// Don't add under water level
+			/*if(y < WATER_LEVEL)
+				continue;*/
+			// Don't add if doesn't belong to this block
+			if(y < node_min.Y || y > node_max.Y)
+				continue;
+			v3s16 p(x,y,z);
+			// Filter placement
+			/*{
+				u32 i = data->vmanip->m_area.index(v3s16(p));
+				MapNode *n = &data->vmanip->m_data[i];
+				if(n->d != CONTENT_MUD && n->d != CONTENT_GRASS)
+					continue;
+			}*/
+			// Will be placed one lower
+			p.Y--;
+			// Add it
+			make_largestone(data->vmanip, p);
+		}
+#endif
+	}
+
+}
+
+BlockMakeData::BlockMakeData():
+	no_op(false),
+	vmanip(NULL),
+	seed(0)
+{}
+
+BlockMakeData::~BlockMakeData()
+{
+	delete vmanip;
+}
+
+}; // namespace mapgen
+
+
diff --git a/src/mapgen.h b/src/mapgen.h
new file mode 100644
index 000000000..57d0ee8a0
--- /dev/null
+++ b/src/mapgen.h
@@ -0,0 +1,66 @@
+/*
+Minetest-c55
+Copyright (C) 2010-2011 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#ifndef MAPGEN_HEADER
+#define MAPGEN_HEADER
+
+#include "common_irrlicht.h"
+#include "utility.h" // UniqueQueue
+
+struct BlockMakeData;
+class MapBlock;
+class ManualMapVoxelManipulator;
+
+namespace mapgen
+{
+	// Finds precise ground level at any position
+	s16 find_ground_level_from_noise(u64 seed, v2s16 p2d, s16 precision);
+
+	// Find out if block is completely underground
+	bool block_is_underground(u64 seed, v3s16 blockpos);
+
+	// Main map generation routine
+	void make_block(BlockMakeData *data);
+	
+	// Add objects according to block content
+	void add_random_objects(MapBlock *block);
+	
+	/*
+		These are used by FarMesh
+	*/
+	bool get_have_sand(u64 seed, v2s16 p2d);
+	double tree_amount_2d(u64 seed, v2s16 p);
+	
+
+	struct BlockMakeData
+	{
+		bool no_op;
+		ManualMapVoxelManipulator *vmanip;
+		u64 seed;
+		v3s16 blockpos;
+		UniqueQueue<v3s16> transforming_liquid;
+
+		BlockMakeData();
+		~BlockMakeData();
+	};
+
+}; // namespace mapgen
+
+#endif
+
diff --git a/src/mapnode.cpp b/src/mapnode.cpp
index 1c0a2740b..dae21e7cc 100644
--- a/src/mapnode.cpp
+++ b/src/mapnode.cpp
@@ -25,6 +25,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "mineral.h"
 // For g_settings
 #include "main.h"
+#include "content_mapnode.h"
 #include "nodemetadata.h"
 
 ContentFeatures::~ContentFeatures()
@@ -107,9 +108,9 @@ void init_mapnode()
 				"g_texturesource!=NULL"<<std::endl;
 	}
 
-	// Read some settings
+	/*// Read some settings
 	bool new_style_water = g_settings.getBool("new_style_water");
-	bool new_style_leaves = g_settings.getBool("new_style_leaves");
+	bool new_style_leaves = g_settings.getBool("new_style_leaves");*/
 
 	/*
 		Initialize content feature table
@@ -131,313 +132,17 @@ void init_mapnode()
 	{
 		ContentFeatures *f = &g_content_features[i];
 		// Re-initialize
-		*f = ContentFeatures();
+		f->reset();
 
 		for(u16 j=0; j<6; j++)
 			f->tiles[j].material_type = initial_material_type;
 	}
-	
-	u8 i;
-	ContentFeatures *f = NULL;
-
-	i = CONTENT_STONE;
-	f = &g_content_features[i];
-	f->setAllTextures("stone.png");
-	f->setInventoryTextureCube("stone.png", "stone.png", "stone.png");
-	f->param_type = CPT_MINERAL;
-	f->is_ground_content = true;
-	f->dug_item = std::string("MaterialItem ")+itos(CONTENT_COBBLE)+" 1";
-	
-	i = CONTENT_GRASS;
-	f = &g_content_features[i];
-	f->setAllTextures("mud.png^grass_side.png");
-	f->setTexture(0, "grass.png");
-	f->setTexture(1, "mud.png");
-	f->param_type = CPT_MINERAL;
-	f->is_ground_content = true;
-	f->dug_item = std::string("MaterialItem ")+itos(CONTENT_MUD)+" 1";
-	
-	i = CONTENT_GRASS_FOOTSTEPS;
-	f = &g_content_features[i];
-	f->setAllTextures("mud.png^grass_side.png");
-	f->setTexture(0, "grass_footsteps.png");
-	f->setTexture(1, "mud.png");
-	f->param_type = CPT_MINERAL;
-	f->is_ground_content = true;
-	f->dug_item = std::string("MaterialItem ")+itos(CONTENT_MUD)+" 1";
-	
-	i = CONTENT_MUD;
-	f = &g_content_features[i];
-	f->setAllTextures("mud.png");
-	f->setInventoryTextureCube("mud.png", "mud.png", "mud.png");
-	f->param_type = CPT_MINERAL;
-	f->is_ground_content = true;
-	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
-	
-	i = CONTENT_SAND;
-	f = &g_content_features[i];
-	f->setAllTextures("sand.png");
-	f->param_type = CPT_MINERAL;
-	f->is_ground_content = true;
-	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
-	
-	i = CONTENT_SANDSTONE;
-	f = &g_content_features[i];
-	f->setAllTextures("sandstone.png");
-	f->setInventoryTextureCube("sandstone.png", "sandstone.png", "sandstone.png");
-	f->param_type = CPT_MINERAL;
-	f->is_ground_content = true;
-	f->dug_item = std::string("MaterialItem ")+itos(CONTENT_SAND)+" 1";
-	
-	i = CONTENT_CLAY;
-	f = &g_content_features[i];
-	f->setAllTextures("clay.png");
-	f->setInventoryTextureCube("clay.png", "clay.png", "clay.png");
-	f->param_type = CPT_MINERAL;
-	f->is_ground_content = true;
-	f->dug_item = std::string("CraftItem lump_of_clay 4");
-	
-	i = CONTENT_BRICK;
-	f = &g_content_features[i];
-	f->setAllTextures("brick.png");
-	f->setInventoryTextureCube("brick.png", "brick.png", "brick.png");
-	f->param_type = CPT_MINERAL;
-	f->is_ground_content = true;
-	f->dug_item = std::string("CraftItem clay_brick 4");
-	
-	i = CONTENT_TREE;
-	f = &g_content_features[i];
-	f->setAllTextures("tree.png");
-	f->setTexture(0, "tree_top.png");
-	f->setTexture(1, "tree_top.png");
-	f->param_type = CPT_MINERAL;
-	f->is_ground_content = true;
-	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
-	
-	i = CONTENT_LEAVES;
-	f = &g_content_features[i];
-	f->light_propagates = true;
-	//f->param_type = CPT_MINERAL;
-	f->param_type = CPT_LIGHT;
-	f->is_ground_content = true;
-	if(new_style_leaves)
-	{
-		f->solidness = 0; // drawn separately, makes no faces
-		f->setInventoryTextureCube("leaves.png", "leaves.png", "leaves.png");
-	}
-	else
-	{
-		f->setAllTextures("[noalpha:leaves.png");
-	}
-	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
-
-	i = CONTENT_CACTUS;
-	f = &g_content_features[i];
-	f->setAllTextures("cactus_side.png");
-	f->setTexture(0, "cactus_top.png");
-	f->setTexture(1, "cactus_top.png");
-	f->setInventoryTextureCube("cactus_top.png", "cactus_side.png", "cactus_side.png");
-	f->param_type = CPT_MINERAL;
-	f->is_ground_content = true;
-	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
-
-	i = CONTENT_PAPYRUS;
-	f = &g_content_features[i];
-	f->setInventoryTexture("papyrus.png");
-	f->light_propagates = true;
-	f->param_type = CPT_LIGHT;
-	f->is_ground_content = true;
-	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
-	f->solidness = 0; // drawn separately, makes no faces
-	f->walkable = false;
-
- 	i = CONTENT_BOOKSHELF;
- 	f = &g_content_features[i];
- 	f->setAllTextures("bookshelf.png");
-	f->setTexture(0, "wood.png");
-	f->setTexture(1, "wood.png");
-	// FIXME: setInventoryTextureCube() only cares for the first texture
-	f->setInventoryTextureCube("bookshelf.png", "bookshelf.png", "bookshelf.png");
-	//f->setInventoryTextureCube("wood.png", "bookshelf.png", "bookshelf.png");
-	f->param_type = CPT_MINERAL;
-	f->is_ground_content = true;
-
-	i = CONTENT_GLASS;
-	f = &g_content_features[i];
-	f->light_propagates = true;
-	f->param_type = CPT_LIGHT;
-	f->is_ground_content = true;
-	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
-	f->solidness = 0; // drawn separately, makes no faces
-	f->setInventoryTextureCube("glass.png", "glass.png", "glass.png");
-
-	i = CONTENT_FENCE;
-	f = &g_content_features[i];
-	f->setInventoryTexture("fence.png");
-	f->light_propagates = true;
-	f->param_type = CPT_LIGHT;
-	f->is_ground_content = true;
-	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
-	f->solidness = 0; // drawn separately, makes no faces
-	f->air_equivalent = true; // grass grows underneath
-
-	i = CONTENT_RAIL;
-	f = &g_content_features[i];
-	f->setInventoryTexture("rail.png");
-	f->light_propagates = true;
-	f->param_type = CPT_LIGHT;
-	f->is_ground_content = true;
-	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
-	f->solidness = 0; // drawn separately, makes no faces
-	f->air_equivalent = true; // grass grows underneath
-	f->walkable = false;
-
-	// Deprecated
-	i = CONTENT_COALSTONE;
-	f = &g_content_features[i];
-	//f->translate_to = new MapNode(CONTENT_STONE, MINERAL_COAL);
-	f->setAllTextures("stone.png^mineral_coal.png");
-	f->is_ground_content = true;
-	
-	i = CONTENT_WOOD;
-	f = &g_content_features[i];
-	f->setAllTextures("wood.png");
-	f->is_ground_content = true;
-	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
-	
-	i = CONTENT_MESE;
-	f = &g_content_features[i];
-	f->setAllTextures("mese.png");
-	f->is_ground_content = true;
-	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
-	
-	i = CONTENT_CLOUD;
-	f = &g_content_features[i];
-	f->setAllTextures("cloud.png");
-	f->is_ground_content = true;
-	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
-	
-	i = CONTENT_AIR;
-	f = &g_content_features[i];
-	f->param_type = CPT_LIGHT;
-	f->light_propagates = true;
-	f->sunlight_propagates = true;
-	f->solidness = 0;
-	f->walkable = false;
-	f->pointable = false;
-	f->diggable = false;
-	f->buildable_to = true;
-	f->air_equivalent = true;
-	
-	i = CONTENT_WATER;
-	f = &g_content_features[i];
-	f->setInventoryTextureCube("water.png", "water.png", "water.png");
-	f->param_type = CPT_LIGHT;
-	f->light_propagates = true;
-	f->solidness = 0; // Drawn separately, makes no faces
-	f->walkable = false;
-	f->pointable = false;
-	f->diggable = false;
-	f->buildable_to = true;
-	f->liquid_type = LIQUID_FLOWING;
-	
-	i = CONTENT_WATERSOURCE;
-	f = &g_content_features[i];
-	f->setInventoryTexture("water.png");
-	if(new_style_water)
-	{
-		f->solidness = 0; // drawn separately, makes no faces
-	}
-	else // old style
-	{
-		f->solidness = 1;
 
-		TileSpec t;
-		if(g_texturesource)
-			t.texture = g_texturesource->getTexture("water.png");
-		
-		t.alpha = WATER_ALPHA;
-		t.material_type = MATERIAL_ALPHA_VERTEX;
-		t.material_flags &= ~MATERIAL_FLAG_BACKFACE_CULLING;
-		f->setAllTiles(t);
-	}
-	f->param_type = CPT_LIGHT;
-	f->light_propagates = true;
-	f->walkable = false;
-	f->pointable = false;
-	f->diggable = false;
-	f->buildable_to = true;
-	f->liquid_type = LIQUID_SOURCE;
-	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
-	
-	i = CONTENT_TORCH;
-	f = &g_content_features[i];
-	f->setInventoryTexture("torch_on_floor.png");
-	f->param_type = CPT_LIGHT;
-	f->light_propagates = true;
-	f->sunlight_propagates = true;
-	f->solidness = 0; // drawn separately, makes no faces
-	f->walkable = false;
-	f->wall_mounted = true;
-	f->air_equivalent = true;
-	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
-	
-	i = CONTENT_SIGN_WALL;
-	f = &g_content_features[i];
-	f->setInventoryTexture("sign_wall.png");
-	f->param_type = CPT_LIGHT;
-	f->light_propagates = true;
-	f->sunlight_propagates = true;
-	f->solidness = 0; // drawn separately, makes no faces
-	f->walkable = false;
-	f->wall_mounted = true;
-	f->air_equivalent = true;
-	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
-	if(f->initial_metadata == NULL)
-		f->initial_metadata = new SignNodeMetadata("Some sign");
-	
-	i = CONTENT_CHEST;
-	f = &g_content_features[i];
-	f->param_type = CPT_FACEDIR_SIMPLE;
-	f->setAllTextures("chest_side.png");
-	f->setTexture(0, "chest_top.png");
-	f->setTexture(1, "chest_top.png");
-	f->setTexture(5, "chest_front.png"); // Z-
-	f->setInventoryTexture("chest_top.png");
-	//f->setInventoryTextureCube("chest_top.png", "chest_side.png", "chest_side.png");
-	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
-	if(f->initial_metadata == NULL)
-		f->initial_metadata = new ChestNodeMetadata();
-	
-	i = CONTENT_FURNACE;
-	f = &g_content_features[i];
-	f->param_type = CPT_FACEDIR_SIMPLE;
-	f->setAllTextures("furnace_side.png");
-	f->setTexture(5, "furnace_front.png"); // Z-
-	f->setInventoryTexture("furnace_front.png");
-	//f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
-	f->dug_item = std::string("MaterialItem ")+itos(CONTENT_COBBLE)+" 6";
-	if(f->initial_metadata == NULL)
-		f->initial_metadata = new FurnaceNodeMetadata();
-	
-	i = CONTENT_COBBLE;
-	f = &g_content_features[i];
-	f->setAllTextures("cobble.png");
-	f->setInventoryTextureCube("cobble.png", "cobble.png", "cobble.png");
-	f->param_type = CPT_NONE;
-	f->is_ground_content = true;
-	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
-	
-	i = CONTENT_STEEL;
-	f = &g_content_features[i];
-	f->setAllTextures("steel_block.png");
-	f->setInventoryTextureCube("steel_block.png", "steel_block.png",
-			"steel_block.png");
-	f->param_type = CPT_NONE;
-	f->is_ground_content = true;
-	f->dug_item = std::string("MaterialItem ")+itos(i)+" 1";
+	/*
+		Initialize mapnode content
+	*/
+	content_mapnode_init();
 	
-	// NOTE: Remember to add frequently used stuff to the texture atlas in tile.cpp
 }
 
 v3s16 facedir_rotate(u8 facedir, v3s16 dir)
@@ -525,16 +230,54 @@ u8 MapNode::getMineral()
 	return MINERAL_NONE;
 }
 
-// Pointers to c_str()s g_content_features[i].inventory_image_path
-//const char * g_content_inventory_texture_paths[USEFUL_CONTENT_COUNT] = {0};
+/*
+	Gets lighting value at face of node
+	
+	Parameters must consist of air and !air.
+	Order doesn't matter.
 
-void init_content_inventory_texture_paths()
+	If either of the nodes doesn't exist, light is 0.
+	
+	parameters:
+		daynight_ratio: 0...1000
+		n: getNodeParent(p)
+		n2: getNodeParent(p + face_dir)
+		face_dir: axis oriented unit vector from p to p2
+	
+	returns encoded light value.
+*/
+u8 getFaceLight(u32 daynight_ratio, MapNode n, MapNode n2,
+		v3s16 face_dir)
 {
-	dstream<<"DEPRECATED "<<__FUNCTION_NAME<<std::endl;
-	/*for(u16 i=0; i<USEFUL_CONTENT_COUNT; i++)
+	try{
+		u8 light;
+		u8 l1 = n.getLightBlend(daynight_ratio);
+		u8 l2 = n2.getLightBlend(daynight_ratio);
+		if(l1 > l2)
+			light = l1;
+		else
+			light = l2;
+
+		// Make some nice difference to different sides
+
+		// This makes light come from a corner
+		/*if(face_dir.X == 1 || face_dir.Z == 1 || face_dir.Y == -1)
+			light = diminish_light(diminish_light(light));
+		else if(face_dir.X == -1 || face_dir.Z == -1)
+			light = diminish_light(light);*/
+		
+		// All neighboring faces have different shade (like in minecraft)
+		if(face_dir.X == 1 || face_dir.X == -1 || face_dir.Y == -1)
+			light = diminish_light(diminish_light(light));
+		else if(face_dir.Z == 1 || face_dir.Z == -1)
+			light = diminish_light(light);
+
+		return light;
+	}
+	catch(InvalidPositionException &e)
 	{
-		g_content_inventory_texture_paths[i] =
-				g_content_features[i].inventory_image_path.c_str();
-	}*/
+		return 0;
+	}
 }
 
+
diff --git a/src/mapnode.h b/src/mapnode.h
index 409fe2bcf..d975a50c4 100644
--- a/src/mapnode.h
+++ b/src/mapnode.h
@@ -27,6 +27,14 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "exceptions.h"
 #include "serialization.h"
 #include "tile.h"
+#include "materials.h"
+
+/*
+	Naming scheme:
+	- Material = irrlicht's Material class
+	- Content = (u8) content of a node
+	- Tile = TileSpec at some side of a node of some content type
+*/
 
 /*
 	Initializes all kind of stuff in here.
@@ -42,13 +50,6 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 */
 void init_mapnode();
 
-// Initializes g_content_inventory_texture_paths
-void init_content_inventory_texture_paths();
-
-
-// NOTE: This is not used appropriately everywhere.
-#define MATERIALS_COUNT 256
-
 /*
 	Ignored node.
 
@@ -68,48 +69,6 @@ void init_content_inventory_texture_paths();
 #define CONTENT_AIR 254
 
 /*
-	Suggested materials:
-	- Gravel
-	- Sand
-	
-	New naming scheme:
-	- Material = irrlicht's Material class
-	- Content = (u8) content of a node
-	- Tile = (u16) Material ID at some side of a node
-*/
-
-#define CONTENT_STONE 0
-#define CONTENT_GRASS 1
-#define CONTENT_WATER 2
-#define CONTENT_TORCH 3
-#define CONTENT_TREE 4
-#define CONTENT_LEAVES 5
-#define CONTENT_GRASS_FOOTSTEPS 6
-#define CONTENT_MESE 7
-#define CONTENT_MUD 8
-#define CONTENT_WATERSOURCE 9
-// Pretty much useless, clouds won't be drawn this way
-#define CONTENT_CLOUD 10
-#define CONTENT_COALSTONE 11
-#define CONTENT_WOOD 12
-#define CONTENT_SAND 13
-#define CONTENT_SIGN_WALL 14
-#define CONTENT_CHEST 15
-#define CONTENT_FURNACE 16
-//#define CONTENT_WORKBENCH 17
-#define CONTENT_COBBLE 18
-#define CONTENT_STEEL 19
-#define CONTENT_GLASS 20
-#define CONTENT_FENCE 21
-#define CONTENT_SANDSTONE 22
-#define CONTENT_CACTUS 23
-#define CONTENT_BRICK 24
-#define CONTENT_CLAY 25
-#define CONTENT_PAPYRUS 26
-#define CONTENT_BOOKSHELF 27
-#define CONTENT_RAIL 28
-
-/*
 	Content feature list
 */
 
@@ -180,10 +139,20 @@ struct ContentFeatures
 	
 	// Initial metadata is cloned from this
 	NodeMetadata *initial_metadata;
+	
+	// If the content is liquid, this is the flowing version of the liquid.
+	// If content is liquid, this is the same content.
+	u8 liquid_alternative_flowing;
+	
+	// Amount of light the node emits
+	u8 light_source;
+	
+	// Digging properties for different tools
+	DiggingPropertiesList digging_properties;
+	
+	// NOTE: Move relevant properties to here from elsewhere
 
-	//TODO: Move more properties here
-
-	ContentFeatures()
+	void reset()
 	{
 		translate_to = NULL;
 		param_type = CPT_NONE;
@@ -201,6 +170,14 @@ struct ContentFeatures
 		air_equivalent = false;
 		dug_item = "";
 		initial_metadata = NULL;
+		liquid_alternative_flowing = CONTENT_IGNORE;
+		light_source = 0;
+		digging_properties.clear();
+	}
+
+	ContentFeatures()
+	{
+		reset();
 	}
 
 	~ContentFeatures();
@@ -242,6 +219,11 @@ struct ContentFeatures
 */
 ContentFeatures & content_features(u8 i);
 
+
+/*
+	Here is a bunch of DEPRECATED functions.
+*/
+
 /*
 	If true, the material allows light propagation and brightness is stored
 	in param.
@@ -250,9 +232,7 @@ ContentFeatures & content_features(u8 i);
 inline bool light_propagates_content(u8 m)
 {
 	return content_features(m).light_propagates;
-	//return (m == CONTENT_AIR || m == CONTENT_TORCH || m == CONTENT_WATER || m == CONTENT_WATERSOURCE);
 }
-
 /*
 	If true, the material allows lossless sunlight propagation.
 	NOTE: It doesn't seem to go through torches regardlessly of this
@@ -261,9 +241,7 @@ inline bool light_propagates_content(u8 m)
 inline bool sunlight_propagates_content(u8 m)
 {
 	return content_features(m).sunlight_propagates;
-	//return (m == CONTENT_AIR || m == CONTENT_TORCH);
 }
-
 /*
 	On a node-node surface, the material of the node with higher solidness
 	is used for drawing.
@@ -275,84 +253,55 @@ inline bool sunlight_propagates_content(u8 m)
 inline u8 content_solidness(u8 m)
 {
 	return content_features(m).solidness;
-	/*// As of now, every pseudo node like torches are added to this
-	if(m == CONTENT_AIR || m == CONTENT_TORCH || m == CONTENT_WATER)
-		return 0;
-	if(m == CONTENT_WATER || m == CONTENT_WATERSOURCE)
-		return 1;
-	return 2;*/
 }
-
 // Objects collide with walkable contents
 // NOTE: Don't use, use "content_features(m).whatever" instead
 inline bool content_walkable(u8 m)
 {
 	return content_features(m).walkable;
-	//return (m != CONTENT_AIR && m != CONTENT_WATER && m != CONTENT_WATERSOURCE && m != CONTENT_TORCH);
 }
-
 // NOTE: Don't use, use "content_features(m).whatever" instead
 inline bool content_liquid(u8 m)
 {
 	return content_features(m).liquid_type != LIQUID_NONE;
-	//return (m == CONTENT_WATER || m == CONTENT_WATERSOURCE);
 }
-
 // NOTE: Don't use, use "content_features(m).whatever" instead
 inline bool content_flowing_liquid(u8 m)
 {
 	return content_features(m).liquid_type == LIQUID_FLOWING;
-	//return (m == CONTENT_WATER);
 }
-
 // NOTE: Don't use, use "content_features(m).whatever" instead
 inline bool content_liquid_source(u8 m)
 {
 	return content_features(m).liquid_type == LIQUID_SOURCE;
-	//return (m == CONTENT_WATERSOURCE);
 }
-
 // CONTENT_WATER || CONTENT_WATERSOURCE -> CONTENT_WATER
 // CONTENT_LAVA || CONTENT_LAVASOURCE -> CONTENT_LAVA
+// NOTE: Don't use, use "content_features(m).whatever" instead
 inline u8 make_liquid_flowing(u8 m)
 {
-	if(m == CONTENT_WATER || m == CONTENT_WATERSOURCE)
-		return CONTENT_WATER;
-	assert(0);
+	u8 c = content_features(m).liquid_alternative_flowing;
+	assert(c != CONTENT_IGNORE);
+	return c;
 }
-
 // Pointable contents can be pointed to in the map
 // NOTE: Don't use, use "content_features(m).whatever" instead
 inline bool content_pointable(u8 m)
 {
 	return content_features(m).pointable;
-	//return (m != CONTENT_AIR && m != CONTENT_WATER && m != CONTENT_WATERSOURCE);
 }
-
 // NOTE: Don't use, use "content_features(m).whatever" instead
 inline bool content_diggable(u8 m)
 {
 	return content_features(m).diggable;
-	//return (m != CONTENT_AIR && m != CONTENT_WATER && m != CONTENT_WATERSOURCE);
 }
-
 // NOTE: Don't use, use "content_features(m).whatever" instead
 inline bool content_buildable_to(u8 m)
 {
 	return content_features(m).buildable_to;
-	//return (m == CONTENT_AIR || m == CONTENT_WATER || m == CONTENT_WATERSOURCE);
 }
 
 /*
-	Returns true for contents that form the base ground that
-	follows the main heightmap
-*/
-/*inline bool is_ground_content(u8 m)
-{
-	return content_features(m).is_ground_content;
-}*/
-
-/*
 	Nodes make a face if contents differ and solidness differs.
 	Return value:
 		0: No face
@@ -500,31 +449,25 @@ struct MapNode
 				&& param == other.param
 				&& param2 == other.param2);
 	}
-
+	
+	/*
+		These four are DEPRECATED I guess. -c55
+	*/
 	bool light_propagates()
 	{
 		return light_propagates_content(d);
 	}
-	
 	bool sunlight_propagates()
 	{
 		return sunlight_propagates_content(d);
 	}
-	
 	u8 solidness()
 	{
 		return content_solidness(d);
 	}
-
 	u8 light_source()
 	{
-		/*
-			Note that a block that isn't light_propagates() can be a light source.
-		*/
-		if(d == CONTENT_TORCH)
-			return LIGHT_MAX;
-		
-		return 0;
+		return content_features(d).light_source;
 	}
 
 	u8 getLightBanksWithSource()
@@ -544,11 +487,6 @@ struct MapNode
 		return (lightday&0x0f) | ((lightnight<<4)&0xf0);
 	}
 
-	void setLightBanks(u8 a_light)
-	{
-		param = a_light;
-	}
-
 	u8 getLight(enum LightBank bank)
 	{
 		// Select the brightest of [light source, propagated light]
@@ -613,13 +551,25 @@ struct MapNode
 	}
 	
 	// In mapnode.cpp
+	/*
+		Get tile of a face of the node.
+		dir: direction of face
+		Returns: TileSpec. Can contain miscellaneous texture coordinates,
+		         which must be obeyed so that the texture atlas can be used.
+	*/
 	TileSpec getTile(v3s16 dir);
-
+	
+	/*
+		Gets mineral content of node, if there is any.
+		MINERAL_NONE if doesn't contain or isn't able to contain mineral.
+	*/
 	u8 getMineral();
 
 	/*
 		These serialization functions are used when informing client
-		of a single node add
+		of a single node add.
+
+		NOTE: When loading a MapBlock, these are not used. Should they?
 	*/
 
 	static u32 serializedLength(u8 version)
@@ -698,7 +648,24 @@ struct MapNode
 	}
 };
 
+/*
+	Gets lighting value at face of node
+	
+	Parameters must consist of air and !air.
+	Order doesn't matter.
 
+	If either of the nodes doesn't exist, light is 0.
+	
+	parameters:
+		daynight_ratio: 0...1000
+		n: getNodeParent(p)
+		n2: getNodeParent(p + face_dir)
+		face_dir: axis oriented unit vector from p to p2
+	
+	returns encoded light value.
+*/
+u8 getFaceLight(u32 daynight_ratio, MapNode n, MapNode n2,
+		v3s16 face_dir);
 
 #endif
 
diff --git a/src/mapsector.cpp b/src/mapsector.cpp
index a24b6c5de..97101dd36 100644
--- a/src/mapsector.cpp
+++ b/src/mapsector.cpp
@@ -24,7 +24,6 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 MapSector::MapSector(NodeContainer *parent, v2s16 pos):
 		differs_from_disk(true),
-		usage_timer(0.0),
 		m_parent(parent),
 		m_pos(pos),
 		m_block_cache(NULL)
diff --git a/src/mapsector.h b/src/mapsector.h
index 2888eb7b2..fda290cd7 100644
--- a/src/mapsector.h
+++ b/src/mapsector.h
@@ -203,13 +203,6 @@ public:
 	// Basically, this should be changed to true in every setter method
 	bool differs_from_disk;
 
-	// Counts seconds from last usage.
-	// Sector can be deleted from memory after some time of inactivity.
-	// NOTE: It has to be made very sure no other thread is accessing
-	//       the sector and it doesn't remain in any cache when
-	//       deleting it.
-	float usage_timer;
-
 protected:
 	
 	// The pile of MapBlocks
diff --git a/src/materials.cpp b/src/materials.cpp
index a8a9a94a8..e3a24b9e3 100644
--- a/src/materials.cpp
+++ b/src/materials.cpp
@@ -1,119 +1,20 @@
 #include "materials.h"
+#include "mapnode.h"
 
-#define MATERIAL_PROPERTIES_COUNT 256
+// NOTE: DEPRECATED
 
-// These correspond to the CONTENT_* constants
-MaterialProperties g_material_properties[MATERIAL_PROPERTIES_COUNT];
-
-bool g_material_properties_initialized = false;
-
-void setStoneLikeDiggingProperties(u8 material, float toughness)
-{
-	g_material_properties[material].setDiggingProperties("",
-			DiggingProperties(true, 15.0*toughness, 0));
-	
-	g_material_properties[material].setDiggingProperties("WPick",
-			DiggingProperties(true, 1.3*toughness, 65535./30.*toughness));
-	g_material_properties[material].setDiggingProperties("STPick",
-			DiggingProperties(true, 0.75*toughness, 65535./100.*toughness));
-	g_material_properties[material].setDiggingProperties("SteelPick",
-			DiggingProperties(true, 0.50*toughness, 65535./333.*toughness));
-
-	/*g_material_properties[material].setDiggingProperties("MesePick",
-			DiggingProperties(true, 0.0*toughness, 65535./20.*toughness));*/
-}
-
-void setDirtLikeDiggingProperties(u8 material, float toughness)
-{
-	g_material_properties[material].setDiggingProperties("",
-			DiggingProperties(true, 0.75*toughness, 0));
-	
-	g_material_properties[material].setDiggingProperties("WShovel",
-			DiggingProperties(true, 0.4*toughness, 65535./50.*toughness));
-	g_material_properties[material].setDiggingProperties("STShovel",
-			DiggingProperties(true, 0.2*toughness, 65535./150.*toughness));
-	g_material_properties[material].setDiggingProperties("SteelShovel",
-			DiggingProperties(true, 0.15*toughness, 65535./400.*toughness));
-}
-
-void setWoodLikeDiggingProperties(u8 material, float toughness)
-{
-	g_material_properties[material].setDiggingProperties("",
-			DiggingProperties(true, 3.0*toughness, 0));
-	
-	g_material_properties[material].setDiggingProperties("WAxe",
-			DiggingProperties(true, 1.5*toughness, 65535./30.*toughness));
-	g_material_properties[material].setDiggingProperties("STAxe",
-			DiggingProperties(true, 0.75*toughness, 65535./100.*toughness));
-	g_material_properties[material].setDiggingProperties("SteelAxe",
-			DiggingProperties(true, 0.5*toughness, 65535./333.*toughness));
-}
-
-void initializeMaterialProperties()
-{
-	/*
-		Now, the g_material_properties array is already initialized
-		by the constructors to such that no digging is possible.
-
-		Add some digging properties to them.
-	*/
-
-	setStoneLikeDiggingProperties(CONTENT_STONE, 1.0);
-	setStoneLikeDiggingProperties(CONTENT_SANDSTONE, 1.0);
-	setStoneLikeDiggingProperties(CONTENT_BRICK, 3.0);
-	setStoneLikeDiggingProperties(CONTENT_MESE, 0.5);
-	setStoneLikeDiggingProperties(CONTENT_COALSTONE, 1.5);
-	setStoneLikeDiggingProperties(CONTENT_FURNACE, 3.0);
-	setStoneLikeDiggingProperties(CONTENT_COBBLE, 1.0);
-	setStoneLikeDiggingProperties(CONTENT_STEEL, 5.0);
-
-	setDirtLikeDiggingProperties(CONTENT_MUD, 1.0);
-	setDirtLikeDiggingProperties(CONTENT_GRASS, 1.0);
-	setDirtLikeDiggingProperties(CONTENT_GRASS_FOOTSTEPS, 1.0);
-	setDirtLikeDiggingProperties(CONTENT_SAND, 1.0);
-	setDirtLikeDiggingProperties(CONTENT_CLAY, 1.0);
-	
-	setWoodLikeDiggingProperties(CONTENT_TREE, 1.0);
-	setWoodLikeDiggingProperties(CONTENT_LEAVES, 0.15);
-	setWoodLikeDiggingProperties(CONTENT_CACTUS, 0.75);
-	setWoodLikeDiggingProperties(CONTENT_PAPYRUS, 0.25);
-	setWoodLikeDiggingProperties(CONTENT_GLASS, 0.15);
-	setWoodLikeDiggingProperties(CONTENT_FENCE, 0.75);
-	setDirtLikeDiggingProperties(CONTENT_RAIL, 0.75);
-	setWoodLikeDiggingProperties(CONTENT_WOOD, 0.75);
-	setWoodLikeDiggingProperties(CONTENT_BOOKSHELF, 0.75);
-	setWoodLikeDiggingProperties(CONTENT_CHEST, 1.0);
-
-	g_material_properties[CONTENT_SIGN_WALL].setDiggingProperties("",
-			DiggingProperties(true, 0.5, 0));
-	g_material_properties[CONTENT_TORCH].setDiggingProperties("",
-			DiggingProperties(true, 0.0, 0));
-	
-	/*
-		Add MesePick to everything
-	*/
-	for(u16 i=0; i<MATERIAL_PROPERTIES_COUNT; i++)
-	{
-		g_material_properties[i].setDiggingProperties("MesePick",
-				DiggingProperties(true, 0.0, 65535./1337));
-	}
-
-	g_material_properties_initialized = true;
-}
-
-MaterialProperties * getMaterialProperties(u8 material)
+DiggingPropertiesList * getDiggingPropertiesList(u8 content)
 {
-	assert(g_material_properties_initialized);
-	return &g_material_properties[material];
+	return &content_features(content).digging_properties;
 }
 
-DiggingProperties getDiggingProperties(u8 material, const std::string &tool)
+DiggingProperties getDiggingProperties(u8 content, const std::string &tool)
 {
-	MaterialProperties *mprop = getMaterialProperties(material);
+	DiggingPropertiesList *mprop = getDiggingPropertiesList(content);
 	if(mprop == NULL)
 		// Not diggable
 		return DiggingProperties();
 	
-	return mprop->getDiggingProperties(tool);
+	return mprop->get(tool);
 }
 
diff --git a/src/materials.h b/src/materials.h
index 422149753..f061ecbfa 100644
--- a/src/materials.h
+++ b/src/materials.h
@@ -25,7 +25,6 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 */
 
 #include "common_irrlicht.h"
-#include "inventory.h"
 #include <string>
 
 struct DiggingProperties
@@ -49,20 +48,26 @@ struct DiggingProperties
 	u16 wear;
 };
 
-class MaterialProperties
+/*
+	This is a bad way of determining mining characteristics.
+	TODO: Get rid of this and set up some attributes like toughness,
+	      fluffyness, and a funciton to calculate time and durability loss
+	      (and sound? and whatever else) from them
+*/
+class DiggingPropertiesList
 {
 public:
-	MaterialProperties()
+	DiggingPropertiesList()
 	{
 	}
 
-	void setDiggingProperties(const std::string toolname,
+	void set(const std::string toolname,
 			const DiggingProperties &prop)
 	{
 		m_digging_properties[toolname] = prop;
 	}
 
-	DiggingProperties getDiggingProperties(const std::string toolname)
+	DiggingProperties get(const std::string toolname)
 	{
 		core::map<std::string, DiggingProperties>::Node *n;
 		n = m_digging_properties.find(toolname);
@@ -80,16 +85,17 @@ public:
 		return n->getValue();
 	}
 
+	void clear()
+	{
+		m_digging_properties.clear();
+	}
+
 private:
 	// toolname="": default properties (digging by hand)
 	// Key is toolname
 	core::map<std::string, DiggingProperties> m_digging_properties;
 };
 
-void initializeMaterialProperties();
-
-// Material correspond to the CONTENT_* constants
-MaterialProperties * getMaterialProperties(u8 material);
 // For getting the default properties, set tool=""
 DiggingProperties getDiggingProperties(u8 material, const std::string &tool);
 
diff --git a/src/nodemetadata.cpp b/src/nodemetadata.cpp
index 308a33854..3edf6d3c2 100644
--- a/src/nodemetadata.cpp
+++ b/src/nodemetadata.cpp
@@ -23,6 +23,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "exceptions.h"
 #include "inventory.h"
 #include <sstream>
+#include "content_mapnode.h"
 
 /*
 	NodeMetadata
@@ -96,268 +97,7 @@ void NodeMetadata::registerType(u16 id, Factory f)
 }
 
 /*
-	SignNodeMetadata
-*/
-
-// Prototype
-SignNodeMetadata proto_SignNodeMetadata("");
-
-SignNodeMetadata::SignNodeMetadata(std::string text):
-	m_text(text)
-{
-	NodeMetadata::registerType(typeId(), create);
-}
-u16 SignNodeMetadata::typeId() const
-{
-	return CONTENT_SIGN_WALL;
-}
-NodeMetadata* SignNodeMetadata::create(std::istream &is)
-{
-	std::string text = deSerializeString(is);
-	return new SignNodeMetadata(text);
-}
-NodeMetadata* SignNodeMetadata::clone()
-{
-	return new SignNodeMetadata(m_text);
-}
-void SignNodeMetadata::serializeBody(std::ostream &os)
-{
-	os<<serializeString(m_text);
-}
-std::string SignNodeMetadata::infoText()
-{
-	return std::string("\"")+m_text+"\"";
-}
-
-/*
-	ChestNodeMetadata
-*/
-
-// Prototype
-ChestNodeMetadata proto_ChestNodeMetadata;
-
-ChestNodeMetadata::ChestNodeMetadata()
-{
-	NodeMetadata::registerType(typeId(), create);
-	
-	m_inventory = new Inventory();
-	m_inventory->addList("0", 8*4);
-}
-ChestNodeMetadata::~ChestNodeMetadata()
-{
-	delete m_inventory;
-}
-u16 ChestNodeMetadata::typeId() const
-{
-	return CONTENT_CHEST;
-}
-NodeMetadata* ChestNodeMetadata::create(std::istream &is)
-{
-	ChestNodeMetadata *d = new ChestNodeMetadata();
-	d->m_inventory->deSerialize(is);
-	return d;
-}
-NodeMetadata* ChestNodeMetadata::clone()
-{
-	ChestNodeMetadata *d = new ChestNodeMetadata();
-	*d->m_inventory = *m_inventory;
-	return d;
-}
-void ChestNodeMetadata::serializeBody(std::ostream &os)
-{
-	m_inventory->serialize(os);
-}
-std::string ChestNodeMetadata::infoText()
-{
-	return "Chest";
-}
-bool ChestNodeMetadata::nodeRemovalDisabled()
-{
-	/*
-		Disable removal if chest contains something
-	*/
-	InventoryList *list = m_inventory->getList("0");
-	if(list == NULL)
-		return false;
-	if(list->getUsedSlots() == 0)
-		return false;
-	return true;
-}
-
-/*
-	FurnaceNodeMetadata
-*/
-
-// Prototype
-FurnaceNodeMetadata proto_FurnaceNodeMetadata;
-
-FurnaceNodeMetadata::FurnaceNodeMetadata()
-{
-	NodeMetadata::registerType(typeId(), create);
-	
-	m_inventory = new Inventory();
-	m_inventory->addList("fuel", 1);
-	m_inventory->addList("src", 1);
-	m_inventory->addList("dst", 4);
-
-	m_step_accumulator = 0;
-	m_fuel_totaltime = 0;
-	m_fuel_time = 0;
-	m_src_totaltime = 0;
-	m_src_time = 0;
-}
-FurnaceNodeMetadata::~FurnaceNodeMetadata()
-{
-	delete m_inventory;
-}
-u16 FurnaceNodeMetadata::typeId() const
-{
-	return CONTENT_FURNACE;
-}
-NodeMetadata* FurnaceNodeMetadata::clone()
-{
-	FurnaceNodeMetadata *d = new FurnaceNodeMetadata();
-	*d->m_inventory = *m_inventory;
-	return d;
-}
-NodeMetadata* FurnaceNodeMetadata::create(std::istream &is)
-{
-	FurnaceNodeMetadata *d = new FurnaceNodeMetadata();
-
-	d->m_inventory->deSerialize(is);
-
-	int temp;
-	is>>temp;
-	d->m_fuel_totaltime = (float)temp/10;
-	is>>temp;
-	d->m_fuel_time = (float)temp/10;
-
-	return d;
-}
-void FurnaceNodeMetadata::serializeBody(std::ostream &os)
-{
-	m_inventory->serialize(os);
-	os<<itos(m_fuel_totaltime*10)<<" ";
-	os<<itos(m_fuel_time*10)<<" ";
-}
-std::string FurnaceNodeMetadata::infoText()
-{
-	//return "Furnace";
-	if(m_fuel_time >= m_fuel_totaltime)
-	{
-		InventoryList *src_list = m_inventory->getList("src");
-		assert(src_list);
-		InventoryItem *src_item = src_list->getItem(0);
-
-		if(src_item)
-			return "Furnace is out of fuel";
-		else
-			return "Furnace is inactive";
-	}
-	else
-	{
-		std::string s = "Furnace is active (";
-		s += itos(m_fuel_time/m_fuel_totaltime*100);
-		s += "%)";
-		return s;
-	}
-}
-void FurnaceNodeMetadata::inventoryModified()
-{
-	dstream<<"Furnace inventory modification callback"<<std::endl;
-}
-bool FurnaceNodeMetadata::step(float dtime)
-{
-	// Update at a fixed frequency
-	const float interval = 0.5;
-	m_step_accumulator += dtime;
-	if(m_step_accumulator < interval)
-		return false;
-	m_step_accumulator -= interval;
-	dtime = interval;
-
-	//dstream<<"Furnace step dtime="<<dtime<<std::endl;
-	
-	InventoryList *dst_list = m_inventory->getList("dst");
-	assert(dst_list);
-
-	InventoryList *src_list = m_inventory->getList("src");
-	assert(src_list);
-	InventoryItem *src_item = src_list->getItem(0);
-	
-	// Start only if there are free slots in dst, so that it can
-	// accomodate any result item
-	if(dst_list->getFreeSlots() > 0 && src_item && src_item->isCookable())
-	{
-		m_src_totaltime = 3;
-	}
-	else
-	{
-		m_src_time = 0;
-		m_src_totaltime = 0;
-	}
-
-	if(m_fuel_time < m_fuel_totaltime)
-	{
-		//dstream<<"Furnace is active"<<std::endl;
-		m_fuel_time += dtime;
-		m_src_time += dtime;
-		if(m_src_time >= m_src_totaltime && m_src_totaltime > 0.001
-				&& src_item)
-		{
-			InventoryItem *cookresult = src_item->createCookResult();
-			dst_list->addItem(cookresult);
-			src_list->decrementMaterials(1);
-			m_src_time = 0;
-			m_src_totaltime = 0;
-		}
-		return true;
-	}
-	
-	if(src_item == NULL || m_src_totaltime < 0.001)
-	{
-		return false;
-	}
-	
-	bool changed = false;
-
-	//dstream<<"Furnace is out of fuel"<<std::endl;
-
-	InventoryList *fuel_list = m_inventory->getList("fuel");
-	assert(fuel_list);
-	InventoryItem *fuel_item = fuel_list->getItem(0);
-
-	if(ItemSpec(ITEM_MATERIAL, CONTENT_TREE).checkItem(fuel_item))
-	{
-		m_fuel_totaltime = 10;
-		m_fuel_time = 0;
-		fuel_list->decrementMaterials(1);
-		changed = true;
-	}
-	else if(ItemSpec(ITEM_MATERIAL, CONTENT_WOOD).checkItem(fuel_item))
-	{
-		m_fuel_totaltime = 5;
-		m_fuel_time = 0;
-		fuel_list->decrementMaterials(1);
-		changed = true;
-	}
-	else if(ItemSpec(ITEM_CRAFT, "lump_of_coal").checkItem(fuel_item))
-	{
-		m_fuel_totaltime = 10;
-		m_fuel_time = 0;
-		fuel_list->decrementMaterials(1);
-		changed = true;
-	}
-	else
-	{
-		//dstream<<"No fuel found"<<std::endl;
-	}
-
-	return changed;
-}
-
-/*
-	NodeMetadatalist
+	NodeMetadataList
 */
 
 void NodeMetadataList::serialize(std::ostream &os)
@@ -484,19 +224,6 @@ bool NodeMetadataList::step(float dtime)
 		bool changed = meta->step(dtime);
 		if(changed)
 			something_changed = true;
-		/*if(res.inventory_changed)
-		{
-			std::string inv_id;
-			inv_id += "nodemeta:";
-			inv_id += itos(p.X);
-			inv_id += ",";
-			inv_id += itos(p.Y);
-			inv_id += ",";
-			inv_id += itos(p.Z);
-			InventoryContext c;
-			c.current_player = NULL;
-			inv_mgr->inventoryModified(&c, inv_id);
-		}*/
 	}
 	return something_changed;
 }
diff --git a/src/nodemetadata.h b/src/nodemetadata.h
index ae02cfc3c..de682f9b6 100644
--- a/src/nodemetadata.h
+++ b/src/nodemetadata.h
@@ -62,6 +62,9 @@ public:
 	// A step in time. Returns true if metadata changed.
 	virtual bool step(float dtime) {return false;}
 	virtual bool nodeRemovalDisabled(){return false;}
+	// Used to make custom inventory menus.
+	// See format in guiInventoryMenu.cpp.
+	virtual std::string getInventoryDrawSpecString(){return "";}
 
 protected:
 	static void registerType(u16 id, Factory f);
@@ -69,74 +72,10 @@ private:
 	static core::map<u16, Factory> m_types;
 };
 
-class SignNodeMetadata : public NodeMetadata
-{
-public:
-	SignNodeMetadata(std::string text);
-	//~SignNodeMetadata();
-	
-	virtual u16 typeId() const;
-	static NodeMetadata* create(std::istream &is);
-	virtual NodeMetadata* clone();
-	virtual void serializeBody(std::ostream &os);
-	virtual std::string infoText();
-
-	std::string getText(){ return m_text; }
-	void setText(std::string t){ m_text = t; }
-
-private:
-	std::string m_text;
-};
-
-class ChestNodeMetadata : public NodeMetadata
-{
-public:
-	ChestNodeMetadata();
-	~ChestNodeMetadata();
-	
-	virtual u16 typeId() const;
-	static NodeMetadata* create(std::istream &is);
-	virtual NodeMetadata* clone();
-	virtual void serializeBody(std::ostream &os);
-	virtual std::string infoText();
-	virtual Inventory* getInventory() {return m_inventory;}
-
-	virtual bool nodeRemovalDisabled();
-	
-private:
-	Inventory *m_inventory;
-};
-
-class FurnaceNodeMetadata : public NodeMetadata
-{
-public:
-	FurnaceNodeMetadata();
-	~FurnaceNodeMetadata();
-	
-	virtual u16 typeId() const;
-	virtual NodeMetadata* clone();
-	static NodeMetadata* create(std::istream &is);
-	virtual void serializeBody(std::ostream &os);
-	virtual std::string infoText();
-	virtual Inventory* getInventory() {return m_inventory;}
-	virtual void inventoryModified();
-	virtual bool step(float dtime);
-
-private:
-	Inventory *m_inventory;
-	float m_step_accumulator;
-	float m_fuel_totaltime;
-	float m_fuel_time;
-	float m_src_totaltime;
-	float m_src_time;
-};
-
 /*
 	List of metadata of all the nodes of a block
 */
 
-class InventoryManager;
-
 class NodeMetadataList
 {
 public:
diff --git a/src/noise.cpp b/src/noise.cpp
index 6362f5b2c..b755a824a 100644
--- a/src/noise.cpp
+++ b/src/noise.cpp
@@ -222,6 +222,49 @@ double noise3d_perlin_abs(double x, double y, double z, int seed,
 	return a;
 }
 
+// -1->0, 0->1, 1->0
+double contour(double v)
+{
+	v = fabs(v);
+	if(v >= 1.0)
+		return 0.0;
+	return (1.0-v);
+}
+
+double noise3d_param(const NoiseParams &param, double x, double y, double z)
+{
+	double s = param.pos_scale;
+	x /= s;
+	y /= s;
+	z /= s;
+
+	if(param.type == NOISE_PERLIN)
+	{
+		return param.noise_scale*noise3d_perlin(x,y,z, param.seed,
+				param.octaves,
+				param.persistence);
+	}
+	else if(param.type == NOISE_PERLIN_ABS)
+	{
+		return param.noise_scale*noise3d_perlin_abs(x,y,z, param.seed,
+				param.octaves,
+				param.persistence);
+	}
+	else if(param.type == NOISE_PERLIN_CONTOUR)
+	{
+		return contour(param.noise_scale*noise3d_perlin(x,y,z,
+				param.seed, param.octaves,
+				param.persistence));
+	}
+	else if(param.type == NOISE_PERLIN_CONTOUR_FLIP_YZ)
+	{
+		return contour(param.noise_scale*noise3d_perlin(x,z,y,
+				param.seed, param.octaves,
+				param.persistence));
+	}
+	else assert(0);
+}
+
 /*
 	NoiseBuffer
 */
@@ -246,8 +289,7 @@ void NoiseBuffer::clear()
 	m_size_z = 0;
 }
 
-void NoiseBuffer::create(int seed, int octaves, double persistence,
-		double pos_scale,
+void NoiseBuffer::create(const NoiseParams &param,
 		double first_x, double first_y, double first_z,
 		double last_x, double last_y, double last_z,
 		double samplelength_x, double samplelength_y, double samplelength_z)
@@ -265,22 +307,54 @@ void NoiseBuffer::create(int seed, int octaves, double persistence,
 	m_size_y = (last_y - m_start_y)/samplelength_y + 2;
 	m_size_z = (last_z - m_start_z)/samplelength_z + 2;
 
-	/*dstream<<"m_size_x="<<m_size_x<<", m_size_y="<<m_size_y
-			<<", m_size_z="<<m_size_z<<std::endl;*/
-	
 	m_data = new double[m_size_x*m_size_y*m_size_z];
 
 	for(int x=0; x<m_size_x; x++)
 	for(int y=0; y<m_size_y; y++)
 	for(int z=0; z<m_size_z; z++)
 	{
-		double xd = (m_start_x + (double)x*m_samplelength_x)/pos_scale;
-		double yd = (m_start_y + (double)y*m_samplelength_y)/pos_scale;
-		double zd = (m_start_z + (double)z*m_samplelength_z)/pos_scale;
-		intSet(x,y,z, noise3d_perlin(xd,yd,zd,seed,octaves,persistence));
+		double xd = (m_start_x + (double)x*m_samplelength_x);
+		double yd = (m_start_y + (double)y*m_samplelength_y);
+		double zd = (m_start_z + (double)z*m_samplelength_z);
+		double a = noise3d_param(param, xd,yd,zd);
+		intSet(x,y,z, a);
+	}
+}
+
+void NoiseBuffer::multiply(const NoiseParams &param)
+{
+	assert(m_data != NULL);
+
+	for(int x=0; x<m_size_x; x++)
+	for(int y=0; y<m_size_y; y++)
+	for(int z=0; z<m_size_z; z++)
+	{
+		double xd = (m_start_x + (double)x*m_samplelength_x);
+		double yd = (m_start_y + (double)y*m_samplelength_y);
+		double zd = (m_start_z + (double)z*m_samplelength_z);
+		double a = noise3d_param(param, xd,yd,zd);
+		intMultiply(x,y,z, a);
 	}
 }
 
+// Deprecated
+void NoiseBuffer::create(int seed, int octaves, double persistence,
+		bool abs,
+		double first_x, double first_y, double first_z,
+		double last_x, double last_y, double last_z,
+		double samplelength_x, double samplelength_y, double samplelength_z)
+{
+	NoiseParams param;
+	param.type = abs ? NOISE_PERLIN_ABS : NOISE_PERLIN;
+	param.seed = seed;
+	param.octaves = octaves;
+	param.persistence = persistence;
+
+	create(param, first_x, first_y, first_z,
+			last_x, last_y, last_z,
+			samplelength_x, samplelength_y, samplelength_z);
+}
+
 void NoiseBuffer::intSet(int x, int y, int z, double d)
 {
 	int i = m_size_x*m_size_y*z + m_size_x*y + x;
@@ -289,6 +363,14 @@ void NoiseBuffer::intSet(int x, int y, int z, double d)
 	m_data[i] = d;
 }
 
+void NoiseBuffer::intMultiply(int x, int y, int z, double d)
+{
+	int i = m_size_x*m_size_y*z + m_size_x*y + x;
+	assert(i >= 0);
+	assert(i < m_size_x*m_size_y*m_size_z);
+	m_data[i] = m_data[i] * d;
+}
+
 double NoiseBuffer::intGet(int x, int y, int z)
 {
 	int i = m_size_x*m_size_y*z + m_size_x*y + x;
@@ -326,3 +408,14 @@ double NoiseBuffer::get(double x, double y, double z)
 	return triLinearInterpolation(v000,v100,v010,v110,v001,v101,v011,v111,xl,yl,zl);
 }
 
+/*bool NoiseBuffer::contains(double x, double y, double z)
+{
+	x -= m_start_x;
+	y -= m_start_y;
+	z -= m_start_z;
+	x /= m_samplelength_x;
+	y /= m_samplelength_y;
+	z /= m_samplelength_z;
+	if(x <= 0.0 || x >= m_size_x)
+}*/
+
diff --git a/src/noise.h b/src/noise.h
index ba26519f2..c8d8985c6 100644
--- a/src/noise.h
+++ b/src/noise.h
@@ -20,6 +20,45 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #ifndef NOISE_HEADER
 #define NOISE_HEADER
 
+#include "debug.h"
+
+class PseudoRandom
+{
+public:
+	PseudoRandom(): m_next(0)
+	{
+	}
+	PseudoRandom(int seed): m_next(seed)
+	{
+	}
+	void seed(int seed)
+	{
+		m_next = seed;
+	}
+	// Returns 0...32767
+	int next()
+	{
+		m_next = m_next * 1103515245 + 12345;
+		return((unsigned)(m_next/65536) % 32768);
+	}
+	int range(int min, int max)
+	{
+		if(max-min > 32768/10)
+		{
+			//dstream<<"WARNING: PseudoRandom::range: max > 32767"<<std::endl;
+			assert(0);
+		}
+		if(min > max)
+		{
+			assert(0);
+			return max;
+		}
+		return (next()%(max-min+1))+min;
+	}
+private:
+	int m_next;
+};
+
 double easeCurve(double t);
  
 // Return value: -1 ... 1
@@ -41,6 +80,38 @@ double noise3d_perlin(double x, double y, double z, int seed,
 double noise3d_perlin_abs(double x, double y, double z, int seed,
 		int octaves, double persistence);
 
+enum NoiseType
+{
+	NOISE_PERLIN,
+	NOISE_PERLIN_ABS,
+	NOISE_PERLIN_CONTOUR,
+	NOISE_PERLIN_CONTOUR_FLIP_YZ
+};
+
+struct NoiseParams
+{
+	NoiseType type;
+	int seed;
+	int octaves;
+	double persistence;
+	double pos_scale;
+	double noise_scale; // Useful for contour noises
+	
+	NoiseParams(NoiseType type_=NOISE_PERLIN, int seed_=0,
+			int octaves_=3, double persistence_=0.5,
+			double pos_scale_=100.0, double noise_scale_=1.0):
+		type(type_),
+		seed(seed_),
+		octaves(octaves_),
+		persistence(persistence_),
+		pos_scale(pos_scale_),
+		noise_scale(noise_scale_)
+	{
+	}
+};
+
+double noise3d_param(const NoiseParams &param, double x, double y, double z);
+
 class NoiseBuffer
 {
 public:
@@ -48,15 +119,23 @@ public:
 	~NoiseBuffer();
 	
 	void clear();
+	void create(const NoiseParams &param,
+			double first_x, double first_y, double first_z,
+			double last_x, double last_y, double last_z,
+			double samplelength_x, double samplelength_y, double samplelength_z);
+	void multiply(const NoiseParams &param);
+	// Deprecated
 	void create(int seed, int octaves, double persistence,
-			double pos_scale,
+			bool abs,
 			double first_x, double first_y, double first_z,
 			double last_x, double last_y, double last_z,
 			double samplelength_x, double samplelength_y, double samplelength_z);
 
 	void intSet(int x, int y, int z, double d);
+	void intMultiply(int x, int y, int z, double d);
 	double intGet(int x, int y, int z);
 	double get(double x, double y, double z);
+	//bool contains(double x, double y, double z);
 
 private:
 	double *m_data;
diff --git a/src/player.cpp b/src/player.cpp
index 147b6c97a..198eca957 100644
--- a/src/player.cpp
+++ b/src/player.cpp
@@ -23,58 +23,6 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "constants.h"
 #include "utility.h"
 
-// Convert a privileges value into a human-readable string,
-// with each component separated by a comma.
-std::wstring privsToString(u64 privs)
-{
-	std::wostringstream os(std::ios_base::binary);
-	if(privs & PRIV_BUILD)
-		os<<L"build,";
-	if(privs & PRIV_TELEPORT)
-		os<<L"teleport,";
-	if(privs & PRIV_SETTIME)
-		os<<L"settime,";
-	if(privs & PRIV_PRIVS)
-		os<<L"privs,";
-	if(privs & PRIV_SHOUT)
-		os<<L"shout,";
-	if(os.tellp())
-	{
-		// Drop the trailing comma. (Why on earth can't
-		// you truncate a C++ stream anyway???)
-		std::wstring tmp = os.str();
-		return tmp.substr(0, tmp.length() -1);
-	}
-	return os.str();
-}
-
-// Converts a comma-seperated list of privilege values into a
-// privileges value. The reverse of privsToString(). Returns
-// PRIV_INVALID if there is anything wrong with the input.
-u64 stringToPrivs(std::wstring str)
-{
-	u64 privs=0;
-	std::vector<std::wstring> pr;
-	pr=str_split(str, ',');
-	for(std::vector<std::wstring>::iterator i = pr.begin();
-		i != pr.end(); ++i)
-	{
-		if(*i == L"build")
-			privs |= PRIV_BUILD;
-		else if(*i == L"teleport")
-			privs |= PRIV_TELEPORT;
-		else if(*i == L"settime")
-			privs |= PRIV_SETTIME;
-		else if(*i == L"privs")
-			privs |= PRIV_PRIVS;
-		else if(*i == L"shout")
-			privs |= PRIV_SHOUT;
-		else
-			return PRIV_INVALID;
-	}
-	return privs;
-}
-
 
 Player::Player():
 	touching_ground(false),
@@ -83,7 +31,6 @@ Player::Player():
 	swimming_up(false),
 	craftresult_is_preview(true),
 	hp(20),
-	privs(PRIV_DEFAULT),
 	peer_id(PEER_ID_INEXISTENT),
 	m_pitch(0),
 	m_yaw(0),
@@ -91,7 +38,6 @@ Player::Player():
 	m_position(0,0,0)
 {
 	updateName("<not set>");
-	updatePassword("");
 	resetInventory();
 }
 
@@ -150,13 +96,12 @@ void Player::serialize(std::ostream &os)
 	Settings args;
 	args.setS32("version", 1);
 	args.set("name", m_name);
-	args.set("password", m_password);
+	//args.set("password", m_password);
 	args.setFloat("pitch", m_pitch);
 	args.setFloat("yaw", m_yaw);
 	args.setV3F("position", m_position);
 	args.setBool("craftresult_is_preview", craftresult_is_preview);
 	args.setS32("hp", hp);
-	args.setU64("privs", privs);
 
 	args.writeLines(os);
 
@@ -185,10 +130,10 @@ void Player::deSerialize(std::istream &is)
 	//args.getS32("version");
 	std::string name = args.get("name");
 	updateName(name.c_str());
-	std::string password = "";
+	/*std::string password = "";
 	if(args.exists("password"))
 		password = args.get("password");
-	updatePassword(password.c_str());
+	updatePassword(password.c_str());*/
 	m_pitch = args.getFloat("pitch");
 	m_yaw = args.getFloat("yaw");
 	m_position = args.getV3F("position");
@@ -202,7 +147,7 @@ void Player::deSerialize(std::istream &is)
 	}catch(SettingNotFoundException &e){
 		hp = 20;
 	}
-	try{
+	/*try{
 		std::string sprivs = args.get("privs");
 		if(sprivs == "all")
 		{
@@ -215,7 +160,7 @@ void Player::deSerialize(std::istream &is)
 		}
 	}catch(SettingNotFoundException &e){
 		privs = PRIV_DEFAULT;
-	}
+	}*/
 
 	inventory.deSerialize(is);
 }
diff --git a/src/player.h b/src/player.h
index 4b776a03f..a7a2433ce 100644
--- a/src/player.h
+++ b/src/player.h
@@ -25,39 +25,8 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "collision.h"
 
 #define PLAYERNAME_SIZE 20
-#define PASSWORD_SIZE 28       // Maximum password length. Allows for
-                               // base64-encoded SHA-1.
-
-#define PLAYERNAME_ALLOWED_CHARS "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-_.,"
-
-// Player privileges. These form a bitmask stored in the privs field
-// of the player, and define things they're allowed to do. See also
-// the static methods Player::privsToString and stringToPrivs that
-// convert these to human-readable form.
-const u64 PRIV_BUILD = 1;            // Can build - i.e. modify the world
-const u64 PRIV_TELEPORT = 2;         // Can teleport
-const u64 PRIV_SETTIME = 4;          // Can set the time
-const u64 PRIV_PRIVS = 8;            // Can grant and revoke privileges
-const u64 PRIV_SERVER = 16;          // Can manage the server (e.g. shutodwn
-                                     // ,settings)
-const u64 PRIV_SHOUT = 32;           // Can broadcast chat messages to all
-                                     // players
-
-// Default privileges - these can be overriden for new players using the
-// config option "default_privs" - however, this value still applies for
-// players that existed before the privileges system was added.
-const u64 PRIV_DEFAULT = PRIV_BUILD|PRIV_SHOUT;
-const u64 PRIV_ALL = 0x7FFFFFFFFFFFFFFFULL;
-const u64 PRIV_INVALID = 0x8000000000000000ULL;
-
-// Convert a privileges value into a human-readable string,
-// with each component separated by a comma.
-std::wstring privsToString(u64 privs);
-
-// Converts a comma-seperated list of privilege values into a
-// privileges value. The reverse of privsToString(). Returns
-// PRIV_INVALID if there is anything wrong with the input.
-u64 stringToPrivs(std::wstring str);
+
+#define PLAYERNAME_ALLOWED_CHARS "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-_"
 
 
 class Map;
@@ -128,16 +97,6 @@ public:
 		return m_name;
 	}
 
-	virtual void updatePassword(const char *password)
-	{
-		snprintf(m_password, PASSWORD_SIZE, "%s", password);
-	}
-
-	const char * getPassword()
-	{
-		return m_password;
-	}
-
 	virtual bool isLocal() const = 0;
 
 	virtual void updateLight(u8 light_at_pos) {};
@@ -167,14 +126,10 @@ public:
 
 	u16 hp;
 
-	// Player's privileges - a bitmaps of PRIV_xxxx.
-	u64 privs;
-
 	u16 peer_id;
 
 protected:
 	char m_name[PLAYERNAME_SIZE];
-	char m_password[PASSWORD_SIZE];
 	f32 m_pitch;
 	f32 m_yaw;
 	v3f m_speed;
diff --git a/src/porting.cpp b/src/porting.cpp
index 7c7ce48ea..7de042ab5 100644
--- a/src/porting.cpp
+++ b/src/porting.cpp
@@ -27,6 +27,10 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "config.h"
 #include "debug.h"
 
+#ifdef __APPLE__
+	#include "CoreFoundation/CoreFoundation.h"
+#endif
+
 namespace porting
 {
 
@@ -215,9 +219,26 @@ void initializePaths()
 	#elif defined(__APPLE__)
 		#include <unistd.h>
 
+    // Code based on
+    // http://stackoverflow.com/questions/516200/relative-paths-not-working-in-xcode-c
+    CFBundleRef main_bundle = CFBundleGetMainBundle();
+    CFURLRef resources_url = CFBundleCopyResourcesDirectoryURL(main_bundle);
+    char path[PATH_MAX];
+    if(CFURLGetFileSystemRepresentation(resources_url, TRUE, (UInt8 *)path, PATH_MAX))
+	{
+		dstream<<"Bundle resource path: "<<path<<std::endl;
+		//chdir(path);
+		path_data = std::string(path) + "/data";
+	}
+	else
+    {
+        // error!
+		dstream<<"WARNING: Could not determine bundle resource path"<<std::endl;
+    }
+    CFRelease(resources_url);
+	
 	path_userdata = std::string(getenv("HOME")) + "/Library/Application Support/" + APPNAME;
-	path_data = std::string("minetest-mac.app/Contents/Resources/data/");
-
+    
 	#endif
 
 #endif // RUN_IN_PLACE
diff --git a/src/profiler.h b/src/profiler.h
new file mode 100644
index 000000000..a30e34a7c
--- /dev/null
+++ b/src/profiler.h
@@ -0,0 +1,131 @@
+/*
+Minetest-c55
+Copyright (C) 2011 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#ifndef PROFILER_HEADER
+#define PROFILER_HEADER
+
+#include "common_irrlicht.h"
+#include <string>
+#include "utility.h"
+#include <jmutex.h>
+#include <jmutexautolock.h>
+
+/*
+	Time profiler
+*/
+
+class Profiler
+{
+public:
+	Profiler()
+	{
+		m_mutex.Init();
+	}
+
+	void add(const std::string &name, u32 duration)
+	{
+		JMutexAutoLock lock(m_mutex);
+		core::map<std::string, u32>::Node *n = m_data.find(name);
+		if(n == NULL)
+		{
+			m_data[name] = duration;
+		}
+		else
+		{
+			n->setValue(n->getValue()+duration);
+		}
+	}
+
+	void clear()
+	{
+		JMutexAutoLock lock(m_mutex);
+		for(core::map<std::string, u32>::Iterator
+				i = m_data.getIterator();
+				i.atEnd() == false; i++)
+		{
+			i.getNode()->setValue(0);
+		}
+	}
+
+	void print(std::ostream &o)
+	{
+		JMutexAutoLock lock(m_mutex);
+		for(core::map<std::string, u32>::Iterator
+				i = m_data.getIterator();
+				i.atEnd() == false; i++)
+		{
+			std::string name = i.getNode()->getKey();
+			o<<name<<": ";
+			s32 clampsize = 40;
+			s32 space = clampsize-name.size();
+			for(s32 j=0; j<space; j++)
+			{
+				if(j%2 == 0 && j < space - 1)
+					o<<"-";
+				else
+					o<<" ";
+			}
+			o<<i.getNode()->getValue();
+			o<<std::endl;
+		}
+	}
+
+private:
+	JMutex m_mutex;
+	core::map<std::string, u32> m_data;
+};
+
+class ScopeProfiler
+{
+public:
+	ScopeProfiler(Profiler *profiler, const std::string &name):
+		m_profiler(profiler),
+		m_name(name),
+		m_timer(NULL)
+	{
+		if(m_profiler)
+			m_timer = new TimeTaker(m_name.c_str());
+	}
+	// name is copied
+	ScopeProfiler(Profiler *profiler, const char *name):
+		m_profiler(profiler),
+		m_name(name),
+		m_timer(NULL)
+	{
+		if(m_profiler)
+			m_timer = new TimeTaker(m_name.c_str());
+	}
+	~ScopeProfiler()
+	{
+		if(m_timer)
+		{
+			u32 duration = m_timer->stop(true);
+			if(m_profiler)
+				m_profiler->add(m_name, duration);
+			delete m_timer;
+		}
+	}
+private:
+	Profiler *m_profiler;
+	std::string m_name;
+	TimeTaker *m_timer;
+};
+
+#endif
+
diff --git a/src/serialization.cpp b/src/serialization.cpp
index 6a43d9190..ff7ca15f2 100644
--- a/src/serialization.cpp
+++ b/src/serialization.cpp
@@ -128,7 +128,7 @@ void decompressZlib(std::istream &is, std::ostream &os)
 
 	ret = inflateInit(&z);
 	if(ret != Z_OK)
-		throw SerializationError("compressZlib: inflateInit failed");
+		throw SerializationError("dcompressZlib: inflateInit failed");
 	
 	z.avail_in = 0;
 	
@@ -162,7 +162,7 @@ void decompressZlib(std::istream &is, std::ostream &os)
 				|| status == Z_MEM_ERROR)
 		{
 			zerr(status);
-			throw SerializationError("compressZlib: inflate failed");
+			throw SerializationError("decompressZlib: inflate failed");
 		}
 		int count = bufsize - z.avail_out;
 		//dstream<<"count="<<count<<std::endl;
@@ -182,7 +182,7 @@ void decompressZlib(std::istream &is, std::ostream &os)
 				{
 					dstream<<"unget #"<<i<<" failed"<<std::endl;
 					dstream<<"fail="<<is.fail()<<" bad="<<is.bad()<<std::endl;
-					throw SerializationError("compressZlib: unget failed");
+					throw SerializationError("decompressZlib: unget failed");
 				}
 			}
 			
diff --git a/src/serialization.h b/src/serialization.h
index fad1388e0..80a336101 100644
--- a/src/serialization.h
+++ b/src/serialization.h
@@ -53,11 +53,12 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 	15: StaticObjects
 	16: larger maximum size of node metadata, and compression
 	17: MapBlocks contain timestamp
+	18: sqlite/new generator/whatever
 */
 // This represents an uninitialized or invalid format
 #define SER_FMT_VER_INVALID 255
 // Highest supported serialization version
-#define SER_FMT_VER_HIGHEST 17
+#define SER_FMT_VER_HIGHEST 18
 // Lowest supported serialization version
 #define SER_FMT_VER_LOWEST 0
 
diff --git a/src/server.cpp b/src/server.cpp
index 4e9ff076f..cf8b57773 100644
--- a/src/server.cpp
+++ b/src/server.cpp
@@ -31,9 +31,37 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "config.h"
 #include "servercommand.h"
 #include "filesys.h"
+#include "content_mapnode.h"
+#include "content_craft.h"
+#include "content_nodemeta.h"
 
 #define BLOCK_EMERGE_FLAG_FROMDISK (1<<0)
 
+class MapEditEventIgnorer
+{
+public:
+	MapEditEventIgnorer(bool *flag):
+		m_flag(flag)
+	{
+		if(*m_flag == false)
+			*m_flag = true;
+		else
+			m_flag = NULL;
+	}
+
+	~MapEditEventIgnorer()
+	{
+		if(m_flag)
+		{
+			assert(*m_flag);
+			*m_flag = false;
+		}
+	}
+	
+private:
+	bool *m_flag;
+};
+
 void * ServerThread::Thread()
 {
 	ThreadStarted();
@@ -147,8 +175,8 @@ void * EmergeThread::Thread()
 		
 		ServerMap &map = ((ServerMap&)m_server->m_env.getMap());
 			
-		core::map<v3s16, MapBlock*> changed_blocks;
-		core::map<v3s16, MapBlock*> lighting_invalidated_blocks;
+		//core::map<v3s16, MapBlock*> changed_blocks;
+		//core::map<v3s16, MapBlock*> lighting_invalidated_blocks;
 
 		MapBlock *block = NULL;
 		bool got_block = true;
@@ -159,32 +187,6 @@ void * EmergeThread::Thread()
 		if(optional)
 			only_from_disk = true;
 
-		v2s16 chunkpos = map.sector_to_chunk(p2d);
-
-		bool generate_chunk = false;
-		if(only_from_disk == false)
-		{
-			JMutexAutoLock envlock(m_server->m_env_mutex);
-			if(map.chunkNonVolatile(chunkpos) == false)
-				generate_chunk = true;
-		}
-		if(generate_chunk)
-		{
-			ChunkMakeData data;
-			
-			{
-				JMutexAutoLock envlock(m_server->m_env_mutex);
-				map.initChunkMake(data, chunkpos);
-			}
-
-			makeChunk(&data);
-
-			{
-				JMutexAutoLock envlock(m_server->m_env_mutex);
-				map.finishChunkMake(data, changed_blocks);
-			}
-		}
-	
 		/*
 			Fetch block from map or generate a single block
 		*/
@@ -193,36 +195,55 @@ void * EmergeThread::Thread()
 			
 			// Load sector if it isn't loaded
 			if(map.getSectorNoGenerateNoEx(p2d) == NULL)
-				map.loadSectorFull(p2d);
+				//map.loadSectorFull(p2d);
+				map.loadSectorMeta(p2d);
 
 			block = map.getBlockNoCreateNoEx(p);
-			if(!block || block->isDummy())
+			if(!block || block->isDummy() || !block->isGenerated())
 			{
-				if(only_from_disk)
+				// Get, load or create sector
+				/*ServerMapSector *sector =
+						(ServerMapSector*)map.createSector(p2d);*/
+
+				// Load/generate block
+
+				/*block = map.emergeBlock(p, sector, changed_blocks,
+						lighting_invalidated_blocks);*/
+
+				block = map.loadBlock(p);
+
+				if(block == NULL && only_from_disk == false)
+					block = map.generateBlock(p, modified_blocks);
+					//block = map.generateBlock(p, changed_blocks);
+					/*block = map.generateBlock(p, block, sector, changed_blocks,
+							lighting_invalidated_blocks);*/
+
+				if(block == NULL)
 				{
 					got_block = false;
 				}
 				else
 				{
-					// Get, load or create sector
-					ServerMapSector *sector =
-							(ServerMapSector*)map.createSector(p2d);
-					// Generate block
-					block = map.generateBlock(p, block, sector, changed_blocks,
-							lighting_invalidated_blocks);
-					if(block == NULL)
-						got_block = false;
+					/*
+						Ignore map edit events, they will not need to be
+						sent to anybody because the block hasn't been sent
+						to anybody
+					*/
+					MapEditEventIgnorer ign(&m_server->m_ignore_map_edit_events);
+					
+					// Activate objects and stuff
+					m_server->m_env.activateBlock(block, 3600);
 				}
 			}
 			else
 			{
-				if(block->getLightingExpired()){
+				/*if(block->getLightingExpired()){
 					lighting_invalidated_blocks[block->getPos()] = block;
-				}
+				}*/
 			}
 
 			// TODO: Some additional checking and lighting updating,
-			// see emergeBlock
+			//       see emergeBlock
 		}
 
 		{//envlock
@@ -234,7 +255,8 @@ void * EmergeThread::Thread()
 				Collect a list of blocks that have been modified in
 				addition to the fetched one.
 			*/
-			
+
+#if 0
 			if(lighting_invalidated_blocks.size() > 0)
 			{
 				/*dstream<<"lighting "<<lighting_invalidated_blocks.size()
@@ -255,11 +277,12 @@ void * EmergeThread::Thread()
 				MapBlock *block = i.getNode()->getValue();
 				modified_blocks.insert(block->getPos(), block);
 			}
+#endif
 		}
 		// If we got no block, there should be no invalidated blocks
 		else
 		{
-			assert(lighting_invalidated_blocks.size() == 0);
+			//assert(lighting_invalidated_blocks.size() == 0);
 		}
 
 		}//envlock
@@ -312,11 +335,14 @@ void RemoteClient::GetNextBlocks(Server *server, float dtime,
 	TimeTaker timer("RemoteClient::GetNextBlocks", &timer_result);*/
 	
 	// Increment timers
-	m_nearest_unsent_reset_timer += dtime;
 	m_nothing_to_send_pause_timer -= dtime;
 	
 	if(m_nothing_to_send_pause_timer >= 0)
+	{
+		// Keep this reset
+		m_nearest_unsent_reset_timer = 0;
 		return;
+	}
 
 	// Won't send anything if already sending
 	if(m_blocks_sending.size() >= g_settings.getU16
@@ -326,14 +352,21 @@ void RemoteClient::GetNextBlocks(Server *server, float dtime,
 		return;
 	}
 
+	//TimeTaker timer("RemoteClient::GetNextBlocks");
+	
 	Player *player = server->m_env.getPlayer(peer_id);
 
 	assert(player != NULL);
 
 	v3f playerpos = player->getPosition();
 	v3f playerspeed = player->getSpeed();
+	v3f playerspeeddir(0,0,0);
+	if(playerspeed.getLength() > 1.0*BS)
+		playerspeeddir = playerspeed / playerspeed.getLength();
+	// Predict to next block
+	v3f playerpos_predicted = playerpos + playerspeeddir*MAP_BLOCKSIZE*BS;
 
-	v3s16 center_nodepos = floatToInt(playerpos, BS);
+	v3s16 center_nodepos = floatToInt(playerpos_predicted, BS);
 
 	v3s16 center = getNodeBlockPos(center_nodepos);
 	
@@ -344,6 +377,9 @@ void RemoteClient::GetNextBlocks(Server *server, float dtime,
 	camera_dir.rotateYZBy(player->getPitch());
 	camera_dir.rotateXZBy(player->getYaw());
 
+	/*dstream<<"camera_dir=("<<camera_dir.X<<","<<camera_dir.Y<<","
+			<<camera_dir.Z<<")"<<std::endl;*/
+
 	/*
 		Get the starting value of the block finder radius.
 	*/
@@ -356,11 +392,18 @@ void RemoteClient::GetNextBlocks(Server *server, float dtime,
 
 	/*dstream<<"m_nearest_unsent_reset_timer="
 			<<m_nearest_unsent_reset_timer<<std::endl;*/
-	if(m_nearest_unsent_reset_timer > 5.0)
+			
+	// This has to be incremented only when the nothing to send pause
+	// is not active
+	m_nearest_unsent_reset_timer += dtime;
+	
+	// Reset periodically to avoid possible bugs or other mishaps
+	if(m_nearest_unsent_reset_timer > 10.0)
 	{
 		m_nearest_unsent_reset_timer = 0;
 		m_nearest_unsent_d = 0;
-		//dstream<<"Resetting m_nearest_unsent_d"<<std::endl;
+		/*dstream<<"Resetting m_nearest_unsent_d for "
+				<<server->getPlayerName(peer_id)<<std::endl;*/
 	}
 
 	//s16 last_nearest_unsent_d = m_nearest_unsent_d;
@@ -402,11 +445,22 @@ void RemoteClient::GetNextBlocks(Server *server, float dtime,
 	s16 d_max = g_settings.getS16("max_block_send_distance");
 	s16 d_max_gen = g_settings.getS16("max_block_generate_distance");
 	
+	// Don't loop very much at a time
+	if(d_max > d_start+1)
+		d_max = d_start+1;
+	/*if(d_max_gen > d_start+2)
+		d_max_gen = d_start+2;*/
+	
 	//dstream<<"Starting from "<<d_start<<std::endl;
 
 	bool sending_something = false;
 
-	for(s16 d = d_start; d <= d_max; d++)
+	bool no_blocks_found_for_sending = true;
+
+	bool queue_is_full = false;
+	
+	s16 d;
+	for(d = d_start; d <= d_max; d++)
 	{
 		//dstream<<"RemoteClient::SendBlocks(): d="<<d<<std::endl;
 		
@@ -451,7 +505,10 @@ void RemoteClient::GetNextBlocks(Server *server, float dtime,
 
 			// Don't select too many blocks for sending
 			if(num_blocks_selected >= max_simul_dynamic)
-				goto queue_full;
+			{
+				queue_is_full = true;
+				goto queue_full_break;
+			}
 			
 			// Don't send blocks that are currently being transferred
 			if(m_blocks_sending.find(p) != NULL)
@@ -513,6 +570,8 @@ void RemoteClient::GetNextBlocks(Server *server, float dtime,
 			}
 #endif
 
+			//dstream<<"d="<<d<<std::endl;
+			
 			/*
 				Don't generate or send if not in sight
 			*/
@@ -527,7 +586,9 @@ void RemoteClient::GetNextBlocks(Server *server, float dtime,
 			*/
 			{
 				if(m_blocks_sent.find(p) != NULL)
+				{
 					continue;
+				}
 			}
 
 			/*
@@ -539,11 +600,14 @@ void RemoteClient::GetNextBlocks(Server *server, float dtime,
 			bool block_is_invalid = false;
 			if(block != NULL)
 			{
+				// Block is dummy if data doesn't exist.
+				// It means it has been not found from disk and not generated
 				if(block->isDummy())
 				{
 					surely_not_found_on_disk = true;
 				}
-
+				
+				// Block is valid if lighting is up-to-date and data exists
 				if(block->isValid() == false)
 				{
 					block_is_invalid = true;
@@ -553,19 +617,23 @@ void RemoteClient::GetNextBlocks(Server *server, float dtime,
 				{
 					block_is_invalid = true;
 				}*/
-				
+
+#if 0
 				v2s16 p2d(p.X, p.Z);
 				ServerMap *map = (ServerMap*)(&server->m_env.getMap());
 				v2s16 chunkpos = map->sector_to_chunk(p2d);
 				if(map->chunkNonVolatile(chunkpos) == false)
 					block_is_invalid = true;
+#endif
+				if(block->isGenerated() == false)
+					block_is_invalid = true;
 #if 1
 				/*
 					If block is not close, don't send it unless it is near
 					ground level.
 
-					Block is not near ground level if night-time mesh
-					doesn't differ from day-time mesh.
+					Block is near ground level if night-time mesh
+					differs from day-time mesh.
 				*/
 				if(d > 3)
 				{
@@ -586,14 +654,16 @@ void RemoteClient::GetNextBlocks(Server *server, float dtime,
 			}
 
 			/*
-				Record the lowest d from which a a block has been
+				Record the lowest d from which a block has been
 				found being not sent and possibly to exist
 			*/
-			if(new_nearest_unsent_d == -1 || d < new_nearest_unsent_d)
+			if(no_blocks_found_for_sending)
 			{
 				if(generate == true)
 					new_nearest_unsent_d = d;
 			}
+
+			no_blocks_found_for_sending = false;
 					
 			/*
 				Add inexistent block to emerge queue.
@@ -603,6 +673,7 @@ void RemoteClient::GetNextBlocks(Server *server, float dtime,
 				//TODO: Get value from somewhere
 				// Allow only one block in emerge queue
 				//if(server->m_emerge_queue.peerItemCount(peer_id) < 1)
+				// Allow two blocks in queue per client
 				if(server->m_emerge_queue.peerItemCount(peer_id) < 2)
 				{
 					//dstream<<"Adding block to emerge queue"<<std::endl;
@@ -633,20 +704,30 @@ void RemoteClient::GetNextBlocks(Server *server, float dtime,
 			sending_something = true;
 		}
 	}
-queue_full:
+queue_full_break:
 
-	if(new_nearest_unsent_d != -1)
+	//dstream<<"Stopped at "<<d<<std::endl;
+	
+	if(no_blocks_found_for_sending)
 	{
-		m_nearest_unsent_d = new_nearest_unsent_d;
+		if(queue_is_full == false)
+			new_nearest_unsent_d = d;
 	}
 
+	if(new_nearest_unsent_d != -1)
+		m_nearest_unsent_d = new_nearest_unsent_d;
+
 	if(sending_something == false)
 	{
 		m_nothing_to_send_counter++;
-		if(m_nothing_to_send_counter >= 3)
+		if((s16)m_nothing_to_send_counter >=
+				g_settings.getS16("max_block_send_distance"))
 		{
 			// Pause time in seconds
-			m_nothing_to_send_pause_timer = 2.0;
+			m_nothing_to_send_pause_timer = 1.0;
+			/*dstream<<"nothing to send to "
+					<<server->getPlayerName(peer_id)
+					<<" (d="<<d<<")"<<std::endl;*/
 		}
 	}
 	else
@@ -817,7 +898,9 @@ void RemoteClient::SendObjectData(
 			bos.write((char*)buf, 6);
 
 			// Write objects
-			block->serializeObjects(bos, serialization_version);
+			//block->serializeObjects(bos, serialization_version); // DEPRECATED
+			// count=0
+			writeU16(bos, 0);
 
 			blockcount++;
 
@@ -967,6 +1050,7 @@ Server::Server(
 	):
 	m_env(new ServerMap(mapsavedir), this),
 	m_con(PROTOCOL_ID, 512, CONNECTION_TIMEOUT, this),
+	m_authmanager(mapsavedir+"/auth.txt"),
 	m_thread(this),
 	m_emergethread(this),
 	m_time_counter(0),
@@ -1129,12 +1213,16 @@ void Server::AsyncRunStep()
 		dtime = m_step_dtime;
 	}
 	
-	// Send blocks to clients
-	SendBlocks(dtime);
+	{
+		ScopeProfiler sp(&g_profiler, "Server: selecting and sending "
+				"blocks to clients");
+		// Send blocks to clients
+		SendBlocks(dtime);
+	}
 	
 	if(dtime < 0.001)
 		return;
-	
+
 	//dstream<<"Server steps "<<dtime<<std::endl;
 	//dstream<<"Server::AsyncRunStep(): dtime="<<dtime<<std::endl;
 	
@@ -1195,12 +1283,14 @@ void Server::AsyncRunStep()
 	{
 		// Process connection's timeouts
 		JMutexAutoLock lock2(m_con_mutex);
+		ScopeProfiler sp(&g_profiler, "Server: connection timeout processing");
 		m_con.RunTimeouts(dtime);
 	}
 	
 	{
 		// This has to be called so that the client list gets synced
 		// with the peer list of the connection
+		ScopeProfiler sp(&g_profiler, "Server: peer change handling");
 		handlePeerChanges();
 	}
 
@@ -1208,6 +1298,7 @@ void Server::AsyncRunStep()
 		// Step environment
 		// This also runs Map's timers
 		JMutexAutoLock lock(m_env_mutex);
+		ScopeProfiler sp(&g_profiler, "Server: environment step");
 		m_env.step(dtime);
 	}
 	
@@ -1224,7 +1315,9 @@ void Server::AsyncRunStep()
 		m_liquid_transform_timer -= 1.00;
 		
 		JMutexAutoLock lock(m_env_mutex);
-		
+
+		ScopeProfiler sp(&g_profiler, "Server: liquid transform");
+
 		core::map<v3s16, MapBlock*> modified_blocks;
 		m_env.getMap().transformLiquids(modified_blocks);
 #if 0		
@@ -1297,10 +1390,11 @@ void Server::AsyncRunStep()
 	*/
 	{
 		//dstream<<"Server: Checking added and deleted active objects"<<std::endl;
-
 		JMutexAutoLock envlock(m_env_mutex);
 		JMutexAutoLock conlock(m_con_mutex);
-		
+
+		ScopeProfiler sp(&g_profiler, "Server: checking added and deleted objects");
+
 		// Radius inside which objects are active
 		s16 radius = 32;
 
@@ -1312,8 +1406,10 @@ void Server::AsyncRunStep()
 			Player *player = m_env.getPlayer(client->peer_id);
 			if(player==NULL)
 			{
-				dstream<<"WARNING: "<<__FUNCTION_NAME<<": Client "<<client->peer_id
-						<<" has no associated player"<<std::endl;
+				// This can happen if the client timeouts somehow
+				/*dstream<<"WARNING: "<<__FUNCTION_NAME<<": Client "
+						<<client->peer_id
+						<<" has no associated player"<<std::endl;*/
 				continue;
 			}
 			v3s16 pos = floatToInt(player->getPosition(), BS);
@@ -1445,6 +1541,8 @@ void Server::AsyncRunStep()
 		JMutexAutoLock envlock(m_env_mutex);
 		JMutexAutoLock conlock(m_con_mutex);
 
+		ScopeProfiler sp(&g_profiler, "Server: sending object messages");
+
 		// Key = object id
 		// Value = data sent by object
 		core::map<u16, core::list<ActiveObjectMessage>* > buffered_messages;
@@ -1557,19 +1655,33 @@ void Server::AsyncRunStep()
 		Send queued-for-sending map edit events.
 	*/
 	{
+		// Don't send too many at a time
+		u32 count = 0;
 		while(m_unsent_map_edit_queue.size() != 0)
 		{
 			MapEditEvent* event = m_unsent_map_edit_queue.pop_front();
+			
+			// Players far away from the change are stored here.
+			// Instead of sending the changes, MapBlocks are set not sent
+			// for them.
+			core::list<u16> far_players;
 
 			if(event->type == MEET_ADDNODE)
 			{
 				dstream<<"Server: MEET_ADDNODE"<<std::endl;
-				sendAddNode(event->p, event->n, event->already_known_by_peer);
+				sendAddNode(event->p, event->n, event->already_known_by_peer,
+						&far_players, 30);
 			}
 			else if(event->type == MEET_REMOVENODE)
 			{
 				dstream<<"Server: MEET_REMOVENODE"<<std::endl;
-				sendRemoveNode(event->p, event->already_known_by_peer);
+				sendRemoveNode(event->p, event->already_known_by_peer,
+						&far_players, 30);
+			}
+			else if(event->type == MEET_BLOCK_NODE_METADATA_CHANGED)
+			{
+				dstream<<"Server: MEET_BLOCK_NODE_METADATA_CHANGED"<<std::endl;
+				setBlockNotSent(event->p);
 			}
 			else if(event->type == MEET_OTHER)
 			{
@@ -1581,8 +1693,35 @@ void Server::AsyncRunStep()
 				dstream<<"WARNING: Server: Unknown MapEditEvent "
 						<<((u32)event->type)<<std::endl;
 			}
+			
+			/*
+				Set blocks not sent to far players
+			*/
+			core::map<v3s16, MapBlock*> modified_blocks2;
+			for(core::map<v3s16, bool>::Iterator
+					i = event->modified_blocks.getIterator();
+					i.atEnd()==false; i++)
+			{
+				v3s16 p = i.getNode()->getKey();
+				modified_blocks2.insert(p, m_env.getMap().getBlockNoCreateNoEx(p));
+			}
+			for(core::list<u16>::Iterator
+					i = far_players.begin();
+					i != far_players.end(); i++)
+			{
+				u16 peer_id = *i;
+				RemoteClient *client = getClient(peer_id);
+				if(client==NULL)
+					continue;
+				client->SetBlocksNotSent(modified_blocks2);
+			}
 
 			delete event;
+
+			// Don't send too many at a time
+			count++;
+			if(count >= 1 && m_unsent_map_edit_queue.size() < 100)
+				break;
 		}
 	}
 
@@ -1597,6 +1736,9 @@ void Server::AsyncRunStep()
 		{
 			JMutexAutoLock lock1(m_env_mutex);
 			JMutexAutoLock lock2(m_con_mutex);
+
+			ScopeProfiler sp(&g_profiler, "Server: sending mbo positions");
+
 			SendObjectData(counter);
 
 			counter = 0.0;
@@ -1605,15 +1747,20 @@ void Server::AsyncRunStep()
 	
 	/*
 		Step node metadata
+		TODO: Move to ServerEnvironment and utilize active block stuff
 	*/
-	{
+	/*{
 		//TimeTaker timer("Step node metadata");
 
 		JMutexAutoLock envlock(m_env_mutex);
 		JMutexAutoLock conlock(m_con_mutex);
-		
+
+		ScopeProfiler sp(&g_profiler, "Server: stepping node metadata");
+
 		core::map<v3s16, MapBlock*> changed_blocks;
 		m_env.getMap().nodeMetadataStep(dtime, changed_blocks);
+		
+		// Use setBlockNotSent
 
 		for(core::map<v3s16, MapBlock*>::Iterator
 				i = changed_blocks.getIterator();
@@ -1629,7 +1776,7 @@ void Server::AsyncRunStep()
 				client->SetBlockNotSent(block->getPos());
 			}
 		}
-	}
+	}*/
 		
 	/*
 		Trigger emergethread (it somehow gets to a non-triggered but
@@ -1646,7 +1793,7 @@ void Server::AsyncRunStep()
 		}
 	}
 
-	// Save map
+	// Save map, players and auth stuff
 	{
 		float &counter = m_savemap_timer;
 		counter += dtime;
@@ -1654,15 +1801,21 @@ void Server::AsyncRunStep()
 		{
 			counter = 0.0;
 
-			JMutexAutoLock lock(m_env_mutex);
+			ScopeProfiler sp(&g_profiler, "Server: saving stuff");
 
+			// Auth stuff
+			if(m_authmanager.isModified())
+				m_authmanager.save();
+			
+			// Map
+			JMutexAutoLock lock(m_env_mutex);
 			if(((ServerMap*)(&m_env.getMap()))->isSavingEnabled() == true)
 			{
 				// Save only changed parts
 				m_env.getMap().save(true);
 
 				// Delete unused sectors
-				u32 deleted_count = m_env.getMap().deleteUnusedSectors(
+				u32 deleted_count = m_env.getMap().unloadUnusedData(
 						g_settings.getFloat("server_unload_unused_sectors_timeout"));
 				if(deleted_count > 0)
 				{
@@ -1795,7 +1948,23 @@ void Server::ProcessData(u8 *data, u32 datasize, u16 peer_id)
 			playername[i] = data[3+i];
 		}
 		playername[PLAYERNAME_SIZE-1] = 0;
-	
+		
+		if(playername[0]=='\0')
+		{
+			derr_server<<DTIME<<"Server: Player has empty name"<<std::endl;
+			SendAccessDenied(m_con, peer_id,
+					L"Empty name");
+			return;
+		}
+
+		if(string_allowed(playername, PLAYERNAME_ALLOWED_CHARS)==false)
+		{
+			derr_server<<DTIME<<"Server: Player has invalid name"<<std::endl;
+			SendAccessDenied(m_con, peer_id,
+					L"Name contains unallowed characters");
+			return;
+		}
+
 		// Get password
 		char password[PASSWORD_SIZE];
 		if(datasize == 2+1+PLAYERNAME_SIZE)
@@ -1811,15 +1980,37 @@ void Server::ProcessData(u8 *data, u32 datasize, u16 peer_id)
 				}
 				password[PASSWORD_SIZE-1] = 0;
 		}
-		Player *checkplayer = m_env.getPlayer(playername);
-		if(checkplayer != NULL && strcmp(checkplayer->getPassword(),password))
+		
+		std::string checkpwd;
+		if(m_authmanager.exists(playername))
+		{
+			checkpwd = m_authmanager.getPassword(playername);
+		}
+		else
+		{
+			checkpwd = g_settings.get("default_password");
+		}
+		
+		if(password != checkpwd && checkpwd != "")
 		{
 			derr_server<<DTIME<<"Server: peer_id="<<peer_id
 					<<": supplied invalid password for "
 					<<playername<<std::endl;
-			SendAccessDenied(m_con, peer_id);
+			SendAccessDenied(m_con, peer_id, L"Invalid password");
 			return;
 		}
+		
+		// Add player to auth manager
+		if(m_authmanager.exists(playername) == false)
+		{
+			derr_server<<DTIME<<"Server: adding player "<<playername
+					<<" to auth manager"<<std::endl;
+			m_authmanager.add(playername);
+			m_authmanager.setPassword(playername, checkpwd);
+			m_authmanager.setPrivs(playername,
+					stringToPrivs(g_settings.get("default_privs")));
+			m_authmanager.save();
+		}
 
 		// Get player
 		Player *player = emergePlayer(playername, password, peer_id);
@@ -1877,8 +2068,7 @@ void Server::ProcessData(u8 *data, u32 datasize, u16 peer_id)
 			writeU16(&reply[0], TOCLIENT_INIT);
 			writeU8(&reply[2], deployed);
 			writeV3S16(&reply[2+1], floatToInt(player->getPosition()+v3f(0,BS/2,0), BS));
-			//writeU64(&reply[2+1+6], m_env.getServerMap().getSeed());
-			writeU64(&reply[2+1+6], 0); // no seed
+			writeU64(&reply[2+1+6], m_env.getServerMap().getSeed());
 			
 			// Send as reliable
 			m_con.Send(peer_id, 0, reply, true);
@@ -2041,7 +2231,7 @@ void Server::ProcessData(u8 *data, u32 datasize, u16 peer_id)
 		if(datasize < 13)
 			return;
 
-		if((player->privs & PRIV_BUILD) == 0)
+		if((getPlayerPrivs(player) & PRIV_BUILD) == 0)
 			return;
 
 		/*
@@ -2125,7 +2315,7 @@ void Server::ProcessData(u8 *data, u32 datasize, u16 peer_id)
 		if(datasize < 7)
 			return;
 
-		if((player->privs & PRIV_BUILD) == 0)
+		if((getPlayerPrivs(player) & PRIV_BUILD) == 0)
 			return;
 
 		/*
@@ -2326,8 +2516,13 @@ void Server::ProcessData(u8 *data, u32 datasize, u16 peer_id)
 			}
 
 			// Make sure the player is allowed to do it
-			if((player->privs & PRIV_BUILD) == 0)
+			if((getPlayerPrivs(player) & PRIV_BUILD) == 0)
+			{
+				dstream<<"Player "<<player->getName()<<" cannot remove node"
+						<<" because privileges are "<<getPlayerPrivs(player)
+						<<std::endl;
 				cannot_remove_node = true;
+			}
 
 			/*
 				If node can't be removed, set block to be re-sent to
@@ -2351,12 +2546,12 @@ void Server::ProcessData(u8 *data, u32 datasize, u16 peer_id)
 			}
 			
 			/*
-				Send the removal to all other clients.
+				Send the removal to all close-by players.
 				- If other player is close, send REMOVENODE
 				- Otherwise set blocks not sent
 			*/
 			core::list<u16> far_players;
-			sendRemoveNode(p_under, peer_id, &far_players, 100);
+			sendRemoveNode(p_under, peer_id, &far_players, 30);
 			
 			/*
 				Update and send inventory
@@ -2431,10 +2626,11 @@ void Server::ProcessData(u8 *data, u32 datasize, u16 peer_id)
 				Remove the node
 				(this takes some time so it is done after the quick stuff)
 			*/
-			m_ignore_map_edit_events = true;
-			m_env.getMap().removeNodeAndUpdate(p_under, modified_blocks);
-			m_ignore_map_edit_events = false;
-			
+			{
+				MapEditEventIgnorer ign(&m_ignore_map_edit_events);
+
+				m_env.getMap().removeNodeAndUpdate(p_under, modified_blocks);
+			}
 			/*
 				Set blocks not sent to far players
 			*/
@@ -2475,8 +2671,15 @@ void Server::ProcessData(u8 *data, u32 datasize, u16 peer_id)
 				try{
 					// Don't add a node if this is not a free space
 					MapNode n2 = m_env.getMap().getNode(p_over);
+					bool no_enough_privs =
+							((getPlayerPrivs(player) & PRIV_BUILD)==0);
+					if(no_enough_privs)
+						dstream<<"Player "<<player->getName()<<" cannot add node"
+							<<" because privileges are "<<getPlayerPrivs(player)
+							<<std::endl;
+
 					if(content_buildable_to(n2.d) == false
-						|| (player->privs & PRIV_BUILD) ==0)
+						|| no_enough_privs)
 					{
 						// Client probably has wrong data.
 						// Set block not sent, so that client will get
@@ -2511,10 +2714,10 @@ void Server::ProcessData(u8 *data, u32 datasize, u16 peer_id)
 					n.dir = packDir(p_under - p_over);
 				
 				/*
-					Send to all players
+					Send to all close-by players
 				*/
 				core::list<u16> far_players;
-				sendAddNode(p_over, n, 0, &far_players, 100);
+				sendAddNode(p_over, n, 0, &far_players, 30);
 				
 				/*
 					Handle inventory
@@ -2538,10 +2741,11 @@ void Server::ProcessData(u8 *data, u32 datasize, u16 peer_id)
 					This takes some time so it is done after the quick stuff
 				*/
 				core::map<v3s16, MapBlock*> modified_blocks;
-				m_ignore_map_edit_events = true;
-				m_env.getMap().addNodeAndUpdate(p_over, n, modified_blocks);
-				m_ignore_map_edit_events = false;
-				
+				{
+					MapEditEventIgnorer ign(&m_ignore_map_edit_events);
+
+					m_env.getMap().addNodeAndUpdate(p_over, n, modified_blocks);
+				}
 				/*
 					Set blocks not sent to far players
 				*/
@@ -2673,7 +2877,7 @@ void Server::ProcessData(u8 *data, u32 datasize, u16 peer_id)
 #endif
 	else if(command == TOSERVER_SIGNTEXT)
 	{
-		if((player->privs & PRIV_BUILD) == 0)
+		if((getPlayerPrivs(player) & PRIV_BUILD) == 0)
 			return;
 		/*
 			u16 command
@@ -2732,7 +2936,7 @@ void Server::ProcessData(u8 *data, u32 datasize, u16 peer_id)
 	}
 	else if(command == TOSERVER_SIGNNODETEXT)
 	{
-		if((player->privs & PRIV_BUILD) == 0)
+		if((getPlayerPrivs(player) & PRIV_BUILD) == 0)
 			return;
 		/*
 			u16 command
@@ -2910,9 +3114,7 @@ void Server::ProcessData(u8 *data, u32 datasize, u16 peer_id)
 		
 		// Local player gets all privileges regardless of
 		// what's set on their account.
-		u64 privs = player->privs;
-		if(g_settings.get("name") == player->getName())
-			privs = PRIV_ALL;
+		u64 privs = getPlayerPrivs(player);
 
 		// Parse commands
 		std::wstring commandprefix = L"/#";
@@ -3020,19 +3222,51 @@ void Server::ProcessData(u8 *data, u32 datasize, u16 peer_id)
 
 		if(datasize != 2+PASSWORD_SIZE*2)
 			return;
-		char password[PASSWORD_SIZE];
+		/*char password[PASSWORD_SIZE];
 		for(u32 i=0; i<PASSWORD_SIZE-1; i++)
 			password[i] = data[2+i];
-		password[PASSWORD_SIZE-1] = 0;
-		if(strcmp(player->getPassword(),password))
+		password[PASSWORD_SIZE-1] = 0;*/
+		std::string oldpwd;
+		for(u32 i=0; i<PASSWORD_SIZE-1; i++)
+		{
+			char c = data[2+i];
+			if(c == 0)
+				break;
+			oldpwd += c;
+		}
+		std::string newpwd;
+		for(u32 i=0; i<PASSWORD_SIZE-1; i++)
+		{
+			char c = data[2+PASSWORD_SIZE+i];
+			if(c == 0)
+				break;
+			newpwd += c;
+		}
+
+		std::string playername = player->getName();
+
+		if(m_authmanager.exists(playername) == false)
 		{
+			dstream<<"Server: playername not found in authmanager"<<std::endl;
+			// Wrong old password supplied!!
+			SendChatMessage(peer_id, L"playername not found in authmanager");
+			return;
+		}
+
+		std::string checkpwd = m_authmanager.getPassword(playername);
+		
+		if(oldpwd != checkpwd)
+		{
+			dstream<<"Server: invalid old password"<<std::endl;
 			// Wrong old password supplied!!
 			SendChatMessage(peer_id, L"Invalid old password supplied. Password NOT changed.");
 			return;
 		}
-		for(u32 i=0; i<PASSWORD_SIZE-1; i++)
-			password[i] = data[30+i];
-		player->updatePassword(password);
+
+		m_authmanager.setPassword(playername, newpwd);
+		
+		dstream<<"Server: password change successful for "<<playername
+				<<std::endl;
 		SendChatMessage(peer_id, L"Password change successful");
 	}
 	else
@@ -3215,12 +3449,14 @@ void Server::SendHP(con::Connection &con, u16 peer_id, u8 hp)
 	con.Send(peer_id, 0, data, true);
 }
 
-void Server::SendAccessDenied(con::Connection &con, u16 peer_id)
+void Server::SendAccessDenied(con::Connection &con, u16 peer_id,
+		const std::wstring &reason)
 {
 	DSTACK(__FUNCTION_NAME);
 	std::ostringstream os(std::ios_base::binary);
 
 	writeU16(os, TOCLIENT_ACCESS_DENIED);
+	os<<serializeWideString(reason);
 
 	// Make data buffer
 	std::string s = os.str();
@@ -3495,6 +3731,17 @@ void Server::sendAddNode(v3s16 p, MapNode n, u16 ignore_id,
 	}
 }
 
+void Server::setBlockNotSent(v3s16 p)
+{
+	for(core::map<u16, RemoteClient*>::Iterator
+		i = m_clients.getIterator();
+		i.atEnd()==false; i++)
+	{
+		RemoteClient *client = i.getNode()->getValue();
+		client->SetBlockNotSent(p);
+	}
+}
+
 void Server::SendBlockNoLock(u16 peer_id, MapBlock *block, u8 ver)
 {
 	DSTACK(__FUNCTION_NAME);
@@ -3560,20 +3807,24 @@ void Server::SendBlocks(float dtime)
 	core::array<PrioritySortedBlockTransfer> queue;
 
 	s32 total_sending = 0;
-
-	for(core::map<u16, RemoteClient*>::Iterator
-		i = m_clients.getIterator();
-		i.atEnd() == false; i++)
+	
 	{
-		RemoteClient *client = i.getNode()->getValue();
-		assert(client->peer_id == i.getNode()->getKey());
+		ScopeProfiler sp(&g_profiler, "Server: selecting blocks for sending");
 
-		total_sending += client->SendingCount();
-		
-		if(client->serialization_version == SER_FMT_VER_INVALID)
-			continue;
-		
-		client->GetNextBlocks(this, dtime, queue);
+		for(core::map<u16, RemoteClient*>::Iterator
+			i = m_clients.getIterator();
+			i.atEnd() == false; i++)
+		{
+			RemoteClient *client = i.getNode()->getValue();
+			assert(client->peer_id == i.getNode()->getKey());
+
+			total_sending += client->SendingCount();
+			
+			if(client->serialization_version == SER_FMT_VER_INVALID)
+				continue;
+			
+			client->GetNextBlocks(this, dtime, queue);
+		}
 	}
 
 	// Sort.
@@ -3644,447 +3895,10 @@ void Server::UpdateCrafting(u16 peer_id)
 				items[i] = clist->getItem(i);
 			}
 			
-			bool found = false;
-
-			// Wood
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[0] = ItemSpec(ITEM_MATERIAL, CONTENT_TREE);
-				if(checkItemCombination(items, specs))
-				{
-					rlist->addItem(new MaterialItem(CONTENT_WOOD, 4));
-					found = true;
-				}
-			}
-
-			// Stick
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[0] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				if(checkItemCombination(items, specs))
-				{
-					rlist->addItem(new CraftItem("Stick", 4));
-					found = true;
-				}
-			}
-
-			// Fence
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[3] = ItemSpec(ITEM_CRAFT, "Stick");
-				specs[4] = ItemSpec(ITEM_CRAFT, "Stick");
-				specs[5] = ItemSpec(ITEM_CRAFT, "Stick");
-				specs[6] = ItemSpec(ITEM_CRAFT, "Stick");
-				specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
-				specs[8] = ItemSpec(ITEM_CRAFT, "Stick");
-				if(checkItemCombination(items, specs))
-				{
-					rlist->addItem(new MaterialItem(CONTENT_FENCE, 2));
-					found = true;
-				}
-			}
-
-			// Sign
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[0] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				specs[1] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				specs[2] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				specs[3] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				specs[4] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				specs[5] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
-				if(checkItemCombination(items, specs))
-				{
-					//rlist->addItem(new MapBlockObjectItem("Sign"));
-					rlist->addItem(new MaterialItem(CONTENT_SIGN_WALL, 1));
-					found = true;
-				}
-			}
-
-			// Torch
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[0] = ItemSpec(ITEM_CRAFT, "lump_of_coal");
-				specs[3] = ItemSpec(ITEM_CRAFT, "Stick");
-				if(checkItemCombination(items, specs))
-				{
-					rlist->addItem(new MaterialItem(CONTENT_TORCH, 4));
-					found = true;
-				}
-			}
-
-			// Wooden pick
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[0] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				specs[1] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				specs[2] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				specs[4] = ItemSpec(ITEM_CRAFT, "Stick");
-				specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
-				if(checkItemCombination(items, specs))
-				{
-					rlist->addItem(new ToolItem("WPick", 0));
-					found = true;
-				}
-			}
-
-			// Stone pick
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[0] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
-				specs[1] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
-				specs[2] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
-				specs[4] = ItemSpec(ITEM_CRAFT, "Stick");
-				specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
-				if(checkItemCombination(items, specs))
-				{
-					rlist->addItem(new ToolItem("STPick", 0));
-					found = true;
-				}
-			}
-
-			// Steel pick
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[0] = ItemSpec(ITEM_CRAFT, "steel_ingot");
-				specs[1] = ItemSpec(ITEM_CRAFT, "steel_ingot");
-				specs[2] = ItemSpec(ITEM_CRAFT, "steel_ingot");
-				specs[4] = ItemSpec(ITEM_CRAFT, "Stick");
-				specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
-				if(checkItemCombination(items, specs))
-				{
-					rlist->addItem(new ToolItem("SteelPick", 0));
-					found = true;
-				}
-			}
-
-			// Mese pick
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[0] = ItemSpec(ITEM_MATERIAL, CONTENT_MESE);
-				specs[1] = ItemSpec(ITEM_MATERIAL, CONTENT_MESE);
-				specs[2] = ItemSpec(ITEM_MATERIAL, CONTENT_MESE);
-				specs[4] = ItemSpec(ITEM_CRAFT, "Stick");
-				specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
-				if(checkItemCombination(items, specs))
-				{
-					rlist->addItem(new ToolItem("MesePick", 0));
-					found = true;
-				}
-			}
-
-			// Wooden shovel
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[1] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				specs[4] = ItemSpec(ITEM_CRAFT, "Stick");
-				specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
-				if(checkItemCombination(items, specs))
-				{
-					rlist->addItem(new ToolItem("WShovel", 0));
-					found = true;
-				}
-			}
-
-			// Stone shovel
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[1] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
-				specs[4] = ItemSpec(ITEM_CRAFT, "Stick");
-				specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
-				if(checkItemCombination(items, specs))
-				{
-					rlist->addItem(new ToolItem("STShovel", 0));
-					found = true;
-				}
-			}
-
-			// Steel shovel
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[1] = ItemSpec(ITEM_CRAFT, "steel_ingot");
-				specs[4] = ItemSpec(ITEM_CRAFT, "Stick");
-				specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
-				if(checkItemCombination(items, specs))
-				{
-					rlist->addItem(new ToolItem("SteelShovel", 0));
-					found = true;
-				}
-			}
-
-			// Wooden axe
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[0] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				specs[1] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				specs[3] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				specs[4] = ItemSpec(ITEM_CRAFT, "Stick");
-				specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
-				if(checkItemCombination(items, specs))
-				{
-					rlist->addItem(new ToolItem("WAxe", 0));
-					found = true;
-				}
-			}
-
-			// Stone axe
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[0] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
-				specs[1] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
-				specs[3] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
-				specs[4] = ItemSpec(ITEM_CRAFT, "Stick");
-				specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
-				if(checkItemCombination(items, specs))
-				{
-					rlist->addItem(new ToolItem("STAxe", 0));
-					found = true;
-				}
-			}
-
-			// Steel axe
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[0] = ItemSpec(ITEM_CRAFT, "steel_ingot");
-				specs[1] = ItemSpec(ITEM_CRAFT, "steel_ingot");
-				specs[3] = ItemSpec(ITEM_CRAFT, "steel_ingot");
-				specs[4] = ItemSpec(ITEM_CRAFT, "Stick");
-				specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
-				if(checkItemCombination(items, specs))
-				{
-					rlist->addItem(new ToolItem("SteelAxe", 0));
-					found = true;
-				}
-			}
-
-			// Wooden sword
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[1] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				specs[4] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
-				if(checkItemCombination(items, specs))
-				{
-					rlist->addItem(new ToolItem("WSword", 0));
-					found = true;
-				}
-			}
-
-			// Stone sword
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[1] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
-				specs[4] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
-				specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
-				if(checkItemCombination(items, specs))
-				{
-					rlist->addItem(new ToolItem("STSword", 0));
-					found = true;
-				}
-			}
-
-			// Steel sword
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[1] = ItemSpec(ITEM_CRAFT, "steel_ingot");
-				specs[4] = ItemSpec(ITEM_CRAFT, "steel_ingot");
-				specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
-				if(checkItemCombination(items, specs))
-				{
-					rlist->addItem(new ToolItem("SteelSword", 0));
-					found = true;
-				}
-			}
-
-			// Rail
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[0] = ItemSpec(ITEM_CRAFT, "steel_ingot");
-				specs[1] = ItemSpec(ITEM_CRAFT, "Stick");
-				specs[2] = ItemSpec(ITEM_CRAFT, "steel_ingot");
-				specs[3] = ItemSpec(ITEM_CRAFT, "steel_ingot");
-				specs[4] = ItemSpec(ITEM_CRAFT, "Stick");
-				specs[5] = ItemSpec(ITEM_CRAFT, "steel_ingot");
-				specs[6] = ItemSpec(ITEM_CRAFT, "steel_ingot");
-				specs[7] = ItemSpec(ITEM_CRAFT, "Stick");
-				specs[8] = ItemSpec(ITEM_CRAFT, "steel_ingot");
-				if(checkItemCombination(items, specs))
-				{
-					rlist->addItem(new MaterialItem(CONTENT_RAIL, 15));
-					found = true;
-				}
-			}
-
-			// Chest
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[0] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				specs[1] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				specs[2] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				specs[3] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				specs[5] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				specs[6] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				specs[7] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				specs[8] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				if(checkItemCombination(items, specs))
-				{
-					rlist->addItem(new MaterialItem(CONTENT_CHEST, 1));
-					found = true;
-				}
-			}
-
-			// Furnace
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[0] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
-				specs[1] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
-				specs[2] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
-				specs[3] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
-				specs[5] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
-				specs[6] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
-				specs[7] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
-				specs[8] = ItemSpec(ITEM_MATERIAL, CONTENT_COBBLE);
-				if(checkItemCombination(items, specs))
-				{
-					rlist->addItem(new MaterialItem(CONTENT_FURNACE, 1));
-					found = true;
-				}
-			}
-
-			// Steel block
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[0] = ItemSpec(ITEM_CRAFT, "steel_ingot");
-				specs[1] = ItemSpec(ITEM_CRAFT, "steel_ingot");
-				specs[2] = ItemSpec(ITEM_CRAFT, "steel_ingot");
-				specs[3] = ItemSpec(ITEM_CRAFT, "steel_ingot");
-				specs[4] = ItemSpec(ITEM_CRAFT, "steel_ingot");
-				specs[5] = ItemSpec(ITEM_CRAFT, "steel_ingot");
-				specs[6] = ItemSpec(ITEM_CRAFT, "steel_ingot");
-				specs[7] = ItemSpec(ITEM_CRAFT, "steel_ingot");
-				specs[8] = ItemSpec(ITEM_CRAFT, "steel_ingot");
-				if(checkItemCombination(items, specs))
-				{
-					rlist->addItem(new MaterialItem(CONTENT_STEEL, 1));
-					found = true;
-				}
-			}
-
-			// Sandstone
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[3] = ItemSpec(ITEM_MATERIAL, CONTENT_SAND);
-				specs[4] = ItemSpec(ITEM_MATERIAL, CONTENT_SAND);
-				specs[6] = ItemSpec(ITEM_MATERIAL, CONTENT_SAND);
-				specs[7] = ItemSpec(ITEM_MATERIAL, CONTENT_SAND);
-				if(checkItemCombination(items, specs))
-				{
-					rlist->addItem(new MaterialItem(CONTENT_SANDSTONE, 1));
-					found = true;
-				}
-			}
-
-			// Clay
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[3] = ItemSpec(ITEM_CRAFT, "lump_of_clay");
-				specs[4] = ItemSpec(ITEM_CRAFT, "lump_of_clay");
-				specs[6] = ItemSpec(ITEM_CRAFT, "lump_of_clay");
-				specs[7] = ItemSpec(ITEM_CRAFT, "lump_of_clay");
-				if(checkItemCombination(items, specs))
-				{
-					rlist->addItem(new MaterialItem(CONTENT_CLAY, 1));
-					found = true;
-				}
-			}
-
-			// Brick
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[3] = ItemSpec(ITEM_CRAFT, "clay_brick");
-				specs[4] = ItemSpec(ITEM_CRAFT, "clay_brick");
-				specs[6] = ItemSpec(ITEM_CRAFT, "clay_brick");
-				specs[7] = ItemSpec(ITEM_CRAFT, "clay_brick");
-				if(checkItemCombination(items, specs))
-				{
-					rlist->addItem(new MaterialItem(CONTENT_BRICK, 1));
-					found = true;
-				}
-			}
-
-			// Paper
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[3] = ItemSpec(ITEM_MATERIAL, CONTENT_PAPYRUS);
-				specs[4] = ItemSpec(ITEM_MATERIAL, CONTENT_PAPYRUS);
-				specs[5] = ItemSpec(ITEM_MATERIAL, CONTENT_PAPYRUS);
-				if(checkItemCombination(items, specs))
-				{
-					rlist->addItem(new CraftItem("paper", 1));
-					found = true;
-				}
-			}
-
-			// Book
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[1] = ItemSpec(ITEM_CRAFT, "paper");
-				specs[4] = ItemSpec(ITEM_CRAFT, "paper");
-				specs[7] = ItemSpec(ITEM_CRAFT, "paper");
-				if(checkItemCombination(items, specs))
-				{
-					rlist->addItem(new CraftItem("book", 1));
-					found = true;
-				}
-			}
-
-			// Book shelf
-			if(!found)
-			{
-				ItemSpec specs[9];
-				specs[0] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				specs[1] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				specs[2] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				specs[3] = ItemSpec(ITEM_CRAFT, "book");
-				specs[4] = ItemSpec(ITEM_CRAFT, "book");
-				specs[5] = ItemSpec(ITEM_CRAFT, "book");
-				specs[6] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				specs[7] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				specs[8] = ItemSpec(ITEM_MATERIAL, CONTENT_WOOD);
-				if(checkItemCombination(items, specs))
-				{
-					rlist->addItem(new MaterialItem(CONTENT_BOOKSHELF, 1));
-					found = true;
-				}
-			}
+			// Get result of crafting grid
+			InventoryItem *result = craft_get_result(items);
+			if(result)
+				rlist->addItem(result);
 		}
 	
 	} // if creative_mode == false
@@ -4135,111 +3949,19 @@ std::wstring Server::getStatusString()
 	return os.str();
 }
 
-
-void setCreativeInventory(Player *player)
-{
-	player->resetInventory();
-	
-	// Give some good tools
-	{
-		InventoryItem *item = new ToolItem("MesePick", 0);
-		void* r = player->inventory.addItem("main", item);
-		assert(r == NULL);
-	}
-	{
-		InventoryItem *item = new ToolItem("SteelPick", 0);
-		void* r = player->inventory.addItem("main", item);
-		assert(r == NULL);
-	}
-	{
-		InventoryItem *item = new ToolItem("SteelAxe", 0);
-		void* r = player->inventory.addItem("main", item);
-		assert(r == NULL);
-	}
-	{
-		InventoryItem *item = new ToolItem("SteelShovel", 0);
-		void* r = player->inventory.addItem("main", item);
-		assert(r == NULL);
-	}
-
-	/*
-		Give materials
-	*/
-	
-	// CONTENT_IGNORE-terminated list
-	u8 material_items[] = {
-		CONTENT_TORCH,
-		CONTENT_COBBLE,
-		CONTENT_MUD,
-		CONTENT_STONE,
-		CONTENT_SAND,
-		CONTENT_SANDSTONE,
-		CONTENT_CLAY,
-		CONTENT_BRICK,
-		CONTENT_TREE,
-		CONTENT_LEAVES,
-		CONTENT_CACTUS,
-		CONTENT_PAPYRUS,
-		CONTENT_BOOKSHELF,
-		CONTENT_GLASS,
-		CONTENT_FENCE,
-		CONTENT_RAIL,
-		CONTENT_MESE,
-		CONTENT_WATERSOURCE,
-		CONTENT_CLOUD,
-		CONTENT_CHEST,
-		CONTENT_FURNACE,
-		CONTENT_SIGN_WALL,
-		CONTENT_IGNORE
-	};
-	
-	u8 *mip = material_items;
-	for(u16 i=0; i<PLAYER_INVENTORY_SIZE; i++)
-	{
-		if(*mip == CONTENT_IGNORE)
-			break;
-
-		InventoryItem *item = new MaterialItem(*mip, 1);
-		player->inventory.addItem("main", item);
-
-		mip++;
-	}
-
-#if 0
-	assert(USEFUL_CONTENT_COUNT <= PLAYER_INVENTORY_SIZE);
-	
-	// add torch first
-	InventoryItem *item = new MaterialItem(CONTENT_TORCH, 1);
-	player->inventory.addItem("main", item);
-	
-	// Then others
-	for(u16 i=0; i<USEFUL_CONTENT_COUNT; i++)
-	{
-		// Skip some materials
-		if(i == CONTENT_WATER || i == CONTENT_TORCH
-			|| i == CONTENT_COALSTONE)
-			continue;
-
-		InventoryItem *item = new MaterialItem(i, 1);
-		player->inventory.addItem("main", item);
-	}
-#endif
-
-	/*// Sign
-	{
-		InventoryItem *item = new MapBlockObjectItem("Sign Example text");
-		void* r = player->inventory.addItem("main", item);
-		assert(r == NULL);
-	}*/
-}
-
 v3f findSpawnPos(ServerMap &map)
 {
 	//return v3f(50,50,50)*BS;
-	
+
 	v2s16 nodepos;
 	s16 groundheight = 0;
 	
+#if 0
+	nodepos = v2s16(0,0);
+	groundheight = 20;
+#endif
+
+#if 1
 	// Try to find a good place a few times
 	for(s32 i=0; i<1000; i++)
 	{
@@ -4269,6 +3991,7 @@ v3f findSpawnPos(ServerMap &map)
 		//dstream<<"Searched through "<<i<<" places."<<std::endl;
 		break;
 	}
+#endif
 	
 	// If no suitable place was not found, go above water at least.
 	if(groundheight < WATER_LEVEL)
@@ -4276,7 +3999,7 @@ v3f findSpawnPos(ServerMap &map)
 
 	return intToFloat(v3s16(
 			nodepos.X,
-			groundheight + 2,
+			groundheight + 3,
 			nodepos.Y
 			), BS);
 }
@@ -4302,7 +4025,7 @@ Player *Server::emergePlayer(const char *name, const char *password, u16 peer_id
 		// Reset inventory to creative if in creative mode
 		if(g_settings.getBool("creative_mode"))
 		{
-			setCreativeInventory(player);
+			craft_set_creative_inventory(player);
 		}
 
 		return player;
@@ -4327,10 +4050,10 @@ Player *Server::emergePlayer(const char *name, const char *password, u16 peer_id
 		//player->peer_id = PEER_ID_INEXISTENT;
 		player->peer_id = peer_id;
 		player->updateName(name);
-		player->updatePassword(password);
-
-		if(g_settings.exists("default_privs"))
-				player->privs = g_settings.getU64("default_privs");
+		m_authmanager.add(name);
+		m_authmanager.setPassword(name, password);
+		m_authmanager.setPrivs(name,
+				stringToPrivs(g_settings.get("default_privs")));
 
 		/*
 			Set player position
@@ -4355,78 +4078,11 @@ Player *Server::emergePlayer(const char *name, const char *password, u16 peer_id
 		
 		if(g_settings.getBool("creative_mode"))
 		{
-			setCreativeInventory(player);
+			craft_set_creative_inventory(player);
 		}
 		else if(g_settings.getBool("give_initial_stuff"))
 		{
-			{
-				InventoryItem *item = new ToolItem("SteelPick", 0);
-				void* r = player->inventory.addItem("main", item);
-				assert(r == NULL);
-			}
-			{
-				InventoryItem *item = new MaterialItem(CONTENT_TORCH, 99);
-				void* r = player->inventory.addItem("main", item);
-				assert(r == NULL);
-			}
-			{
-				InventoryItem *item = new ToolItem("SteelAxe", 0);
-				void* r = player->inventory.addItem("main", item);
-				assert(r == NULL);
-			}
-			{
-				InventoryItem *item = new ToolItem("SteelShovel", 0);
-				void* r = player->inventory.addItem("main", item);
-				assert(r == NULL);
-			}
-			{
-				InventoryItem *item = new MaterialItem(CONTENT_COBBLE, 99);
-				void* r = player->inventory.addItem("main", item);
-				assert(r == NULL);
-			}
-			/*{
-				InventoryItem *item = new MaterialItem(CONTENT_MESE, 6);
-				void* r = player->inventory.addItem("main", item);
-				assert(r == NULL);
-			}
-			{
-				InventoryItem *item = new MaterialItem(CONTENT_COALSTONE, 6);
-				void* r = player->inventory.addItem("main", item);
-				assert(r == NULL);
-			}
-			{
-				InventoryItem *item = new MaterialItem(CONTENT_WOOD, 6);
-				void* r = player->inventory.addItem("main", item);
-				assert(r == NULL);
-			}
-			{
-				InventoryItem *item = new CraftItem("Stick", 4);
-				void* r = player->inventory.addItem("main", item);
-				assert(r == NULL);
-			}
-			{
-				InventoryItem *item = new ToolItem("WPick", 32000);
-				void* r = player->inventory.addItem("main", item);
-				assert(r == NULL);
-			}
-			{
-				InventoryItem *item = new ToolItem("STPick", 32000);
-				void* r = player->inventory.addItem("main", item);
-				assert(r == NULL);
-			}*/
-			/*// and some signs
-			for(u16 i=0; i<4; i++)
-			{
-				InventoryItem *item = new MapBlockObjectItem("Sign Example text");
-				bool r = player->inventory.addItem("main", item);
-				assert(r == true);
-			}*/
-			/*// Give some other stuff
-			{
-				InventoryItem *item = new MaterialItem(CONTENT_TREE, 999);
-				bool r = player->inventory.addItem("main", item);
-				assert(r == true);
-			}*/
+			craft_give_initial_stuff(player);
 		}
 
 		return player;
@@ -4544,29 +4200,69 @@ void Server::handlePeerChanges()
 	}
 }
 
+u64 Server::getPlayerPrivs(Player *player)
+{
+	if(player==NULL)
+		return 0;
+	std::string playername = player->getName();
+	// Local player gets all privileges regardless of
+	// what's set on their account.
+	if(g_settings.get("name") == playername)
+	{
+		return PRIV_ALL;
+	}
+	else
+	{
+		return getPlayerAuthPrivs(playername);
+	}
+}
+
 void dedicated_server_loop(Server &server, bool &kill)
 {
 	DSTACK(__FUNCTION_NAME);
 	
-	std::cout<<DTIME<<std::endl;
-	std::cout<<"========================"<<std::endl;
-	std::cout<<"Running dedicated server"<<std::endl;
-	std::cout<<"========================"<<std::endl;
-	std::cout<<std::endl;
+	dstream<<DTIME<<std::endl;
+	dstream<<"========================"<<std::endl;
+	dstream<<"Running dedicated server"<<std::endl;
+	dstream<<"========================"<<std::endl;
+	dstream<<std::endl;
+
+	IntervalLimiter m_profiler_interval;
 
 	for(;;)
 	{
 		// This is kind of a hack but can be done like this
 		// because server.step() is very light
-		sleep_ms(30);
+		{
+			ScopeProfiler sp(&g_profiler, "dedicated server sleep");
+			sleep_ms(30);
+		}
 		server.step(0.030);
 
 		if(server.getShutdownRequested() || kill)
 		{
-			std::cout<<DTIME<<" dedicated_server_loop(): Quitting."<<std::endl;
+			dstream<<DTIME<<" dedicated_server_loop(): Quitting."<<std::endl;
 			break;
 		}
 
+		/*
+			Profiler
+		*/
+		float profiler_print_interval =
+				g_settings.getFloat("profiler_print_interval");
+		if(profiler_print_interval != 0)
+		{
+			if(m_profiler_interval.step(0.030, profiler_print_interval))
+			{
+				dstream<<"Profiler:"<<std::endl;
+				g_profiler.print(dstream);
+				g_profiler.clear();
+			}
+		}
+		
+		/*
+			Player info
+		*/
 		static int counter = 0;
 		counter--;
 		if(counter <= 0)
@@ -4579,10 +4275,10 @@ void dedicated_server_loop(Server &server, bool &kill)
 			u32 sum = PIChecksum(list);
 			if(sum != sum_old)
 			{
-				std::cout<<DTIME<<"Player info:"<<std::endl;
+				dstream<<DTIME<<"Player info:"<<std::endl;
 				for(i=list.begin(); i!=list.end(); i++)
 				{
-					i->PrintLine(&std::cout);
+					i->PrintLine(&dstream);
 				}
 			}
 			sum_old = sum;
diff --git a/src/server.h b/src/server.h
index 54330856c..b88369ddf 100644
--- a/src/server.h
+++ b/src/server.h
@@ -17,10 +17,6 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
-/*
-(c) 2010 Perttu Ahola <celeron55@gmail.com>
-*/
-
 #ifndef SERVER_HEADER
 #define SERVER_HEADER
 
@@ -32,6 +28,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "porting.h"
 #include "map.h"
 #include "inventory.h"
+#include "auth.h"
 
 /*
 	Some random functions
@@ -423,7 +420,29 @@ public:
 
 	// Envlock and conlock should be locked when calling this
 	void SendMovePlayer(Player *player);
+	
+	u64 getPlayerAuthPrivs(const std::string &name)
+	{
+		try{
+			return m_authmanager.getPrivs(name);
+		}
+		catch(AuthNotFoundException &e)
+		{
+			dstream<<"WARNING: Auth not found for "<<name<<std::endl;
+			return 0;
+		}
+	}
 
+	void setPlayerAuthPrivs(const std::string &name, u64 privs)
+	{
+		try{
+			return m_authmanager.setPrivs(name, privs);
+		}
+		catch(AuthNotFoundException &e)
+		{
+			dstream<<"WARNING: Auth not found for "<<name<<std::endl;
+		}
+	}
 
 private:
 
@@ -438,7 +457,8 @@ private:
 	*/
 	
 	static void SendHP(con::Connection &con, u16 peer_id, u8 hp);
-	static void SendAccessDenied(con::Connection &con, u16 peer_id);
+	static void SendAccessDenied(con::Connection &con, u16 peer_id,
+			const std::wstring &reason);
 	
 	/*
 		Non-static send methods
@@ -456,15 +476,17 @@ private:
 		Additionally, if far_players!=NULL, players further away than
 		far_d_nodes are ignored and their peer_ids are added to far_players
 	*/
+	// Envlock and conlock should be locked when calling these
 	void sendRemoveNode(v3s16 p, u16 ignore_id=0,
 			core::list<u16> *far_players=NULL, float far_d_nodes=100);
 	void sendAddNode(v3s16 p, MapNode n, u16 ignore_id=0,
 			core::list<u16> *far_players=NULL, float far_d_nodes=100);
+	void setBlockNotSent(v3s16 p);
 	
 	// Environment and Connection must be locked when called
 	void SendBlockNoLock(u16 peer_id, MapBlock *block, u8 ver);
 	
-	// Sends blocks to clients
+	// Sends blocks to clients (locks env and con on its own)
 	void SendBlocks(float dtime);
 
 	/*
@@ -476,6 +498,15 @@ private:
 	// When called, connection mutex should be locked
 	RemoteClient* getClient(u16 peer_id);
 	
+	// When called, environment mutex should be locked
+	std::string getPlayerName(u16 peer_id)
+	{
+		Player *player = m_env.getPlayer(peer_id);
+		if(player == NULL)
+			return "[id="+itos(peer_id);
+		return player->getName();
+	}
+
 	/*
 		Get a player from memory or creates one.
 		If player is already connected, return NULL
@@ -491,6 +522,8 @@ private:
 	void handlePeerChange(PeerChange &c);
 	void handlePeerChanges();
 
+	u64 getPlayerPrivs(Player *player);
+
 	/*
 		Variables
 	*/
@@ -514,6 +547,9 @@ private:
 	JMutex m_con_mutex;
 	// Connected clients (behind the con mutex)
 	core::map<u16, RemoteClient*> m_clients;
+
+	// User authentication
+	AuthManager m_authmanager;
 	
 	/*
 		Threads
@@ -598,6 +634,8 @@ private:
 	*/
 	u16 m_ignore_map_edit_events_peer_id;
 
+	Profiler *m_profiler;
+
 	friend class EmergeThread;
 	friend class RemoteClient;
 };
diff --git a/src/servercommand.cpp b/src/servercommand.cpp
index 5bb4f67f8..333e29084 100644
--- a/src/servercommand.cpp
+++ b/src/servercommand.cpp
@@ -1,24 +1,21 @@
 /*
-Minetest-c55
-Copyright (C) 2010-2011 celeron55, Perttu Ahola <celeron55@gmail.com>
+Part of Minetest-c55
+Copyright (C) 2010-11 celeron55, Perttu Ahola <celeron55@gmail.com>
 Copyright (C) 2011 Ciaran Gultnieks <ciaran@ciarang.com>
 
-This program is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-This program is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with this program; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+Permission to use, copy, modify, and distribute this software for any
+purpose with or without fee is hereby granted, provided that the above
+copyright notice and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
 
-
 #include "servercommand.h"
 #include "utility.h"
 
@@ -35,7 +32,8 @@ void cmd_privs(std::wostringstream &os,
 	{
 		// Show our own real privs, without any adjustments
 		// made for admin status
-		os<<L"-!- " + privsToString(ctx->player->privs);
+		os<<L"-!- " + narrow_to_wide(privsToString(
+				ctx->server->getPlayerAuthPrivs(ctx->player->getName())));
 		return;
 	}
 
@@ -52,7 +50,7 @@ void cmd_privs(std::wostringstream &os,
 		return;
 	}
 	
-	os<<L"-!- " + privsToString(tp->privs);
+	os<<L"-!- " + narrow_to_wide(privsToString(ctx->server->getPlayerAuthPrivs(tp->getName())));
 }
 
 void cmd_grantrevoke(std::wostringstream &os,
@@ -70,7 +68,7 @@ void cmd_grantrevoke(std::wostringstream &os,
 		return;
 	}
 
-	u64 newprivs = stringToPrivs(ctx->parms[2]);
+	u64 newprivs = stringToPrivs(wide_to_narrow(ctx->parms[2]));
 	if(newprivs == PRIV_INVALID)
 	{
 		os<<L"-!- Invalid privileges specified";
@@ -83,14 +81,19 @@ void cmd_grantrevoke(std::wostringstream &os,
 		os<<L"-!- No such player";
 		return;
 	}
+	
+	std::string playername = wide_to_narrow(ctx->parms[1]);
+	u64 privs = ctx->server->getPlayerAuthPrivs(playername);
 
 	if(ctx->parms[0] == L"grant")
-		tp->privs |= newprivs;
+		privs |= newprivs;
 	else
-		tp->privs &= ~newprivs;
+		privs &= ~newprivs;
+	
+	ctx->server->setPlayerAuthPrivs(playername, privs);
 	
 	os<<L"-!- Privileges change to ";
-	os<<privsToString(tp->privs);
+	os<<narrow_to_wide(privsToString(privs));
 }
 
 void cmd_time(std::wostringstream &os,
diff --git a/src/servercommand.h b/src/servercommand.h
index 058fbe65b..9013bc2a6 100644
--- a/src/servercommand.h
+++ b/src/servercommand.h
@@ -1,21 +1,19 @@
 /*
-Minetest-c55
-Copyright (C) 2010-2011 celeron55, Perttu Ahola <celeron55@gmail.com>
+Part of Minetest-c55
+Copyright (C) 2010-11 celeron55, Perttu Ahola <celeron55@gmail.com>
 Copyright (C) 2011 Ciaran Gultnieks <ciaran@ciarang.com>
 
-This program is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-This program is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with this program; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+Permission to use, copy, modify, and distribute this software for any
+purpose with or without fee is hereby granted, provided that the above
+copyright notice and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
 
 #ifndef SERVERCOMMAND_HEADER
diff --git a/src/servermain.cpp b/src/servermain.cpp
index 254b1f28a..146c548c5 100644
--- a/src/servermain.cpp
+++ b/src/servermain.cpp
@@ -69,6 +69,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "materials.h"
 #include "config.h"
 #include "mineral.h"
+#include "filesys.h"
 
 /*
 	Settings.
@@ -79,6 +80,9 @@ Settings g_settings;
 
 extern void set_default_settings();
 
+// Global profiler
+Profiler g_profiler;
+
 // A dummy thing
 ITextureSource *g_texturesource = NULL;
 
@@ -113,6 +117,15 @@ u32 getTimeMs()
 int main(int argc, char *argv[])
 {
 	/*
+		Initialization
+	*/
+
+	// Set locale. This is for forcing '.' as the decimal point.
+	std::locale::global(std::locale("C"));
+	// This enables printing all characters in bitmap font
+	setlocale(LC_CTYPE, "en_US");
+
+	/*
 		Low-level initialization
 	*/
 
@@ -121,20 +134,31 @@ int main(int argc, char *argv[])
 	disable_stderr = true;
 #endif
 
+	porting::signal_handler_init();
+	bool &kill = *porting::signal_handler_killstatus();
+	
+	// Initialize porting::path_data and porting::path_userdata
+	porting::initializePaths();
+
+	// Create user data directory
+	fs::CreateDir(porting::path_userdata);
+	
 	// Initialize debug streams
-	debugstreams_init(disable_stderr, DEBUGFILE);
+#ifdef RUN_IN_PLACE
+	std::string debugfile = DEBUGFILE;
+#else
+	std::string debugfile = porting::path_userdata+"/"+DEBUGFILE;
+#endif
+	debugstreams_init(disable_stderr, debugfile.c_str());
 	// Initialize debug stacks
 	debug_stacks_init();
 
 	DSTACK(__FUNCTION_NAME);
 
-	porting::signal_handler_init();
-	bool &kill = *porting::signal_handler_killstatus();
-	
-	porting::initializePaths();
-
-	initializeMaterialProperties();
+	// Init material properties table
+	//initializeMaterialProperties();
 
+	// Debug handler
 	BEGIN_DEBUG_EXCEPTION_HANDLER
 
 	// Print startup message
@@ -199,20 +223,11 @@ int main(int argc, char *argv[])
 	// Initialize default settings
 	set_default_settings();
 	
-	// Set locale. This is for forcing '.' as the decimal point.
-	std::locale::global(std::locale("C"));
-	// This enables printing all characters in bitmap font
-	setlocale(LC_CTYPE, "en_US");
-
 	// Initialize sockets
 	sockets_init();
 	atexit(sockets_cleanup);
 	
 	/*
-		Initialization
-	*/
-
-	/*
 		Read config file
 	*/
 	
@@ -301,7 +316,7 @@ int main(int argc, char *argv[])
 	}
 	
 	// Figure out path to map
-	std::string map_dir = porting::path_userdata+"/map";
+	std::string map_dir = porting::path_userdata+"/world";
 	if(cmd_args.exists("map-dir"))
 		map_dir = cmd_args.get("map-dir");
 	else if(g_settings.exists("map-dir"))
diff --git a/src/sqlite/CMakeLists.txt b/src/sqlite/CMakeLists.txt
new file mode 100644
index 000000000..253625501
--- /dev/null
+++ b/src/sqlite/CMakeLists.txt
@@ -0,0 +1,16 @@
+if( UNIX )
+	set(sqlite3_SRCS sqlite3.c)
+	set(sqlite3_platform_LIBS "")
+else( UNIX )
+	set(sqlite3_SRCS sqlite3.c)
+	set(sqlite3_platform_LIBS "")
+endif( UNIX )
+
+add_library(sqlite3 ${sqlite3_SRCS})
+
+target_link_libraries(
+	sqlite3
+	${sqlite3_platform_LIBS}
+)
+
+
diff --git a/src/sqlite/sqlite3.c b/src/sqlite/sqlite3.c
new file mode 100644
index 000000000..c6595fe36
--- /dev/null
+++ b/src/sqlite/sqlite3.c
@@ -0,0 +1,125968 @@
+/******************************************************************************
+** This file is an amalgamation of many separate C source files from SQLite
+** version 3.7.6.3.  By combining all the individual C code files into this 
+** single large file, the entire code can be compiled as a single translation
+** unit.  This allows many compilers to do optimizations that would not be
+** possible if the files were compiled separately.  Performance improvements
+** of 5% or more are commonly seen when SQLite is compiled as a single
+** translation unit.
+**
+** This file is all you need to compile SQLite.  To use SQLite in other
+** programs, you need this file and the "sqlite3.h" header file that defines
+** the programming interface to the SQLite library.  (If you do not have 
+** the "sqlite3.h" header file at hand, you will find a copy embedded within
+** the text of this file.  Search for "Begin file sqlite3.h" to find the start
+** of the embedded sqlite3.h header file.) Additional code files may be needed
+** if you want a wrapper to interface SQLite with your choice of programming
+** language. The code for the "sqlite3" command-line shell is also in a
+** separate file. This file contains only code for the core SQLite library.
+*/
+#define SQLITE_CORE 1
+#define SQLITE_AMALGAMATION 1
+#ifndef SQLITE_PRIVATE
+# define SQLITE_PRIVATE static
+#endif
+#ifndef SQLITE_API
+# define SQLITE_API
+#endif
+/************** Begin file sqliteInt.h ***************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** Internal interface definitions for SQLite.
+**
+*/
+#ifndef _SQLITEINT_H_
+#define _SQLITEINT_H_
+
+/*
+** These #defines should enable >2GB file support on POSIX if the
+** underlying operating system supports it.  If the OS lacks
+** large file support, or if the OS is windows, these should be no-ops.
+**
+** Ticket #2739:  The _LARGEFILE_SOURCE macro must appear before any
+** system #includes.  Hence, this block of code must be the very first
+** code in all source files.
+**
+** Large file support can be disabled using the -DSQLITE_DISABLE_LFS switch
+** on the compiler command line.  This is necessary if you are compiling
+** on a recent machine (ex: Red Hat 7.2) but you want your code to work
+** on an older machine (ex: Red Hat 6.0).  If you compile on Red Hat 7.2
+** without this option, LFS is enable.  But LFS does not exist in the kernel
+** in Red Hat 6.0, so the code won't work.  Hence, for maximum binary
+** portability you should omit LFS.
+**
+** Similar is true for Mac OS X.  LFS is only supported on Mac OS X 9 and later.
+*/
+#ifndef SQLITE_DISABLE_LFS
+# define _LARGE_FILE       1
+# ifndef _FILE_OFFSET_BITS
+#   define _FILE_OFFSET_BITS 64
+# endif
+# define _LARGEFILE_SOURCE 1
+#endif
+
+/*
+** Include the configuration header output by 'configure' if we're using the
+** autoconf-based build
+*/
+#ifdef _HAVE_SQLITE_CONFIG_H
+#include "config.h"
+#endif
+
+/************** Include sqliteLimit.h in the middle of sqliteInt.h ***********/
+/************** Begin file sqliteLimit.h *************************************/
+/*
+** 2007 May 7
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** 
+** This file defines various limits of what SQLite can process.
+*/
+
+/*
+** The maximum length of a TEXT or BLOB in bytes.   This also
+** limits the size of a row in a table or index.
+**
+** The hard limit is the ability of a 32-bit signed integer
+** to count the size: 2^31-1 or 2147483647.
+*/
+#ifndef SQLITE_MAX_LENGTH
+# define SQLITE_MAX_LENGTH 1000000000
+#endif
+
+/*
+** This is the maximum number of
+**
+**    * Columns in a table
+**    * Columns in an index
+**    * Columns in a view
+**    * Terms in the SET clause of an UPDATE statement
+**    * Terms in the result set of a SELECT statement
+**    * Terms in the GROUP BY or ORDER BY clauses of a SELECT statement.
+**    * Terms in the VALUES clause of an INSERT statement
+**
+** The hard upper limit here is 32676.  Most database people will
+** tell you that in a well-normalized database, you usually should
+** not have more than a dozen or so columns in any table.  And if
+** that is the case, there is no point in having more than a few
+** dozen values in any of the other situations described above.
+*/
+#ifndef SQLITE_MAX_COLUMN
+# define SQLITE_MAX_COLUMN 2000
+#endif
+
+/*
+** The maximum length of a single SQL statement in bytes.
+**
+** It used to be the case that setting this value to zero would
+** turn the limit off.  That is no longer true.  It is not possible
+** to turn this limit off.
+*/
+#ifndef SQLITE_MAX_SQL_LENGTH
+# define SQLITE_MAX_SQL_LENGTH 1000000000
+#endif
+
+/*
+** The maximum depth of an expression tree. This is limited to 
+** some extent by SQLITE_MAX_SQL_LENGTH. But sometime you might 
+** want to place more severe limits on the complexity of an 
+** expression.
+**
+** A value of 0 used to mean that the limit was not enforced.
+** But that is no longer true.  The limit is now strictly enforced
+** at all times.
+*/
+#ifndef SQLITE_MAX_EXPR_DEPTH
+# define SQLITE_MAX_EXPR_DEPTH 1000
+#endif
+
+/*
+** The maximum number of terms in a compound SELECT statement.
+** The code generator for compound SELECT statements does one
+** level of recursion for each term.  A stack overflow can result
+** if the number of terms is too large.  In practice, most SQL
+** never has more than 3 or 4 terms.  Use a value of 0 to disable
+** any limit on the number of terms in a compount SELECT.
+*/
+#ifndef SQLITE_MAX_COMPOUND_SELECT
+# define SQLITE_MAX_COMPOUND_SELECT 500
+#endif
+
+/*
+** The maximum number of opcodes in a VDBE program.
+** Not currently enforced.
+*/
+#ifndef SQLITE_MAX_VDBE_OP
+# define SQLITE_MAX_VDBE_OP 25000
+#endif
+
+/*
+** The maximum number of arguments to an SQL function.
+*/
+#ifndef SQLITE_MAX_FUNCTION_ARG
+# define SQLITE_MAX_FUNCTION_ARG 127
+#endif
+
+/*
+** The maximum number of in-memory pages to use for the main database
+** table and for temporary tables.  The SQLITE_DEFAULT_CACHE_SIZE
+*/
+#ifndef SQLITE_DEFAULT_CACHE_SIZE
+# define SQLITE_DEFAULT_CACHE_SIZE  2000
+#endif
+#ifndef SQLITE_DEFAULT_TEMP_CACHE_SIZE
+# define SQLITE_DEFAULT_TEMP_CACHE_SIZE  500
+#endif
+
+/*
+** The default number of frames to accumulate in the log file before
+** checkpointing the database in WAL mode.
+*/
+#ifndef SQLITE_DEFAULT_WAL_AUTOCHECKPOINT
+# define SQLITE_DEFAULT_WAL_AUTOCHECKPOINT  1000
+#endif
+
+/*
+** The maximum number of attached databases.  This must be between 0
+** and 62.  The upper bound on 62 is because a 64-bit integer bitmap
+** is used internally to track attached databases.
+*/
+#ifndef SQLITE_MAX_ATTACHED
+# define SQLITE_MAX_ATTACHED 10
+#endif
+
+
+/*
+** The maximum value of a ?nnn wildcard that the parser will accept.
+*/
+#ifndef SQLITE_MAX_VARIABLE_NUMBER
+# define SQLITE_MAX_VARIABLE_NUMBER 999
+#endif
+
+/* Maximum page size.  The upper bound on this value is 65536.  This a limit
+** imposed by the use of 16-bit offsets within each page.
+**
+** Earlier versions of SQLite allowed the user to change this value at
+** compile time. This is no longer permitted, on the grounds that it creates
+** a library that is technically incompatible with an SQLite library 
+** compiled with a different limit. If a process operating on a database 
+** with a page-size of 65536 bytes crashes, then an instance of SQLite 
+** compiled with the default page-size limit will not be able to rollback 
+** the aborted transaction. This could lead to database corruption.
+*/
+#ifdef SQLITE_MAX_PAGE_SIZE
+# undef SQLITE_MAX_PAGE_SIZE
+#endif
+#define SQLITE_MAX_PAGE_SIZE 65536
+
+
+/*
+** The default size of a database page.
+*/
+#ifndef SQLITE_DEFAULT_PAGE_SIZE
+# define SQLITE_DEFAULT_PAGE_SIZE 1024
+#endif
+#if SQLITE_DEFAULT_PAGE_SIZE>SQLITE_MAX_PAGE_SIZE
+# undef SQLITE_DEFAULT_PAGE_SIZE
+# define SQLITE_DEFAULT_PAGE_SIZE SQLITE_MAX_PAGE_SIZE
+#endif
+
+/*
+** Ordinarily, if no value is explicitly provided, SQLite creates databases
+** with page size SQLITE_DEFAULT_PAGE_SIZE. However, based on certain
+** device characteristics (sector-size and atomic write() support),
+** SQLite may choose a larger value. This constant is the maximum value
+** SQLite will choose on its own.
+*/
+#ifndef SQLITE_MAX_DEFAULT_PAGE_SIZE
+# define SQLITE_MAX_DEFAULT_PAGE_SIZE 8192
+#endif
+#if SQLITE_MAX_DEFAULT_PAGE_SIZE>SQLITE_MAX_PAGE_SIZE
+# undef SQLITE_MAX_DEFAULT_PAGE_SIZE
+# define SQLITE_MAX_DEFAULT_PAGE_SIZE SQLITE_MAX_PAGE_SIZE
+#endif
+
+
+/*
+** Maximum number of pages in one database file.
+**
+** This is really just the default value for the max_page_count pragma.
+** This value can be lowered (or raised) at run-time using that the
+** max_page_count macro.
+*/
+#ifndef SQLITE_MAX_PAGE_COUNT
+# define SQLITE_MAX_PAGE_COUNT 1073741823
+#endif
+
+/*
+** Maximum length (in bytes) of the pattern in a LIKE or GLOB
+** operator.
+*/
+#ifndef SQLITE_MAX_LIKE_PATTERN_LENGTH
+# define SQLITE_MAX_LIKE_PATTERN_LENGTH 50000
+#endif
+
+/*
+** Maximum depth of recursion for triggers.
+**
+** A value of 1 means that a trigger program will not be able to itself
+** fire any triggers. A value of 0 means that no trigger programs at all 
+** may be executed.
+*/
+#ifndef SQLITE_MAX_TRIGGER_DEPTH
+# define SQLITE_MAX_TRIGGER_DEPTH 1000
+#endif
+
+/************** End of sqliteLimit.h *****************************************/
+/************** Continuing where we left off in sqliteInt.h ******************/
+
+/* Disable nuisance warnings on Borland compilers */
+#if defined(__BORLANDC__)
+#pragma warn -rch /* unreachable code */
+#pragma warn -ccc /* Condition is always true or false */
+#pragma warn -aus /* Assigned value is never used */
+#pragma warn -csu /* Comparing signed and unsigned */
+#pragma warn -spa /* Suspicious pointer arithmetic */
+#endif
+
+/* Needed for various definitions... */
+#ifndef _GNU_SOURCE
+# define _GNU_SOURCE
+#endif
+
+/*
+** Include standard header files as necessary
+*/
+#ifdef HAVE_STDINT_H
+#include <stdint.h>
+#endif
+#ifdef HAVE_INTTYPES_H
+#include <inttypes.h>
+#endif
+
+/*
+** The number of samples of an index that SQLite takes in order to 
+** construct a histogram of the table content when running ANALYZE
+** and with SQLITE_ENABLE_STAT2
+*/
+#define SQLITE_INDEX_SAMPLES 10
+
+/*
+** The following macros are used to cast pointers to integers and
+** integers to pointers.  The way you do this varies from one compiler
+** to the next, so we have developed the following set of #if statements
+** to generate appropriate macros for a wide range of compilers.
+**
+** The correct "ANSI" way to do this is to use the intptr_t type. 
+** Unfortunately, that typedef is not available on all compilers, or
+** if it is available, it requires an #include of specific headers
+** that vary from one machine to the next.
+**
+** Ticket #3860:  The llvm-gcc-4.2 compiler from Apple chokes on
+** the ((void*)&((char*)0)[X]) construct.  But MSVC chokes on ((void*)(X)).
+** So we have to define the macros in different ways depending on the
+** compiler.
+*/
+#if defined(__PTRDIFF_TYPE__)  /* This case should work for GCC */
+# define SQLITE_INT_TO_PTR(X)  ((void*)(__PTRDIFF_TYPE__)(X))
+# define SQLITE_PTR_TO_INT(X)  ((int)(__PTRDIFF_TYPE__)(X))
+#elif !defined(__GNUC__)       /* Works for compilers other than LLVM */
+# define SQLITE_INT_TO_PTR(X)  ((void*)&((char*)0)[X])
+# define SQLITE_PTR_TO_INT(X)  ((int)(((char*)X)-(char*)0))
+#elif defined(HAVE_STDINT_H)   /* Use this case if we have ANSI headers */
+# define SQLITE_INT_TO_PTR(X)  ((void*)(intptr_t)(X))
+# define SQLITE_PTR_TO_INT(X)  ((int)(intptr_t)(X))
+#else                          /* Generates a warning - but it always works */
+# define SQLITE_INT_TO_PTR(X)  ((void*)(X))
+# define SQLITE_PTR_TO_INT(X)  ((int)(X))
+#endif
+
+/*
+** The SQLITE_THREADSAFE macro must be defined as 0, 1, or 2.
+** 0 means mutexes are permanently disable and the library is never
+** threadsafe.  1 means the library is serialized which is the highest
+** level of threadsafety.  2 means the libary is multithreaded - multiple
+** threads can use SQLite as long as no two threads try to use the same
+** database connection at the same time.
+**
+** Older versions of SQLite used an optional THREADSAFE macro.
+** We support that for legacy.
+*/
+#if !defined(SQLITE_THREADSAFE)
+#if defined(THREADSAFE)
+# define SQLITE_THREADSAFE THREADSAFE
+#else
+# define SQLITE_THREADSAFE 1 /* IMP: R-07272-22309 */
+#endif
+#endif
+
+/*
+** The SQLITE_DEFAULT_MEMSTATUS macro must be defined as either 0 or 1.
+** It determines whether or not the features related to 
+** SQLITE_CONFIG_MEMSTATUS are available by default or not. This value can
+** be overridden at runtime using the sqlite3_config() API.
+*/
+#if !defined(SQLITE_DEFAULT_MEMSTATUS)
+# define SQLITE_DEFAULT_MEMSTATUS 1
+#endif
+
+/*
+** Exactly one of the following macros must be defined in order to
+** specify which memory allocation subsystem to use.
+**
+**     SQLITE_SYSTEM_MALLOC          // Use normal system malloc()
+**     SQLITE_MEMDEBUG               // Debugging version of system malloc()
+**
+** (Historical note:  There used to be several other options, but we've
+** pared it down to just these two.)
+**
+** If none of the above are defined, then set SQLITE_SYSTEM_MALLOC as
+** the default.
+*/
+#if defined(SQLITE_SYSTEM_MALLOC)+defined(SQLITE_MEMDEBUG)>1
+# error "At most one of the following compile-time configuration options\
+ is allows: SQLITE_SYSTEM_MALLOC, SQLITE_MEMDEBUG"
+#endif
+#if defined(SQLITE_SYSTEM_MALLOC)+defined(SQLITE_MEMDEBUG)==0
+# define SQLITE_SYSTEM_MALLOC 1
+#endif
+
+/*
+** If SQLITE_MALLOC_SOFT_LIMIT is not zero, then try to keep the
+** sizes of memory allocations below this value where possible.
+*/
+#if !defined(SQLITE_MALLOC_SOFT_LIMIT)
+# define SQLITE_MALLOC_SOFT_LIMIT 1024
+#endif
+
+/*
+** We need to define _XOPEN_SOURCE as follows in order to enable
+** recursive mutexes on most Unix systems.  But Mac OS X is different.
+** The _XOPEN_SOURCE define causes problems for Mac OS X we are told,
+** so it is omitted there.  See ticket #2673.
+**
+** Later we learn that _XOPEN_SOURCE is poorly or incorrectly
+** implemented on some systems.  So we avoid defining it at all
+** if it is already defined or if it is unneeded because we are
+** not doing a threadsafe build.  Ticket #2681.
+**
+** See also ticket #2741.
+*/
+#if !defined(_XOPEN_SOURCE) && !defined(__DARWIN__) && !defined(__APPLE__) && SQLITE_THREADSAFE
+#  define _XOPEN_SOURCE 500  /* Needed to enable pthread recursive mutexes */
+#endif
+
+/*
+** The TCL headers are only needed when compiling the TCL bindings.
+*/
+#if defined(SQLITE_TCL) || defined(TCLSH)
+# include <tcl.h>
+#endif
+
+/*
+** Many people are failing to set -DNDEBUG=1 when compiling SQLite.
+** Setting NDEBUG makes the code smaller and run faster.  So the following
+** lines are added to automatically set NDEBUG unless the -DSQLITE_DEBUG=1
+** option is set.  Thus NDEBUG becomes an opt-in rather than an opt-out
+** feature.
+*/
+#if !defined(NDEBUG) && !defined(SQLITE_DEBUG) 
+# define NDEBUG 1
+#endif
+
+/*
+** The testcase() macro is used to aid in coverage testing.  When 
+** doing coverage testing, the condition inside the argument to
+** testcase() must be evaluated both true and false in order to
+** get full branch coverage.  The testcase() macro is inserted
+** to help ensure adequate test coverage in places where simple
+** condition/decision coverage is inadequate.  For example, testcase()
+** can be used to make sure boundary values are tested.  For
+** bitmask tests, testcase() can be used to make sure each bit
+** is significant and used at least once.  On switch statements
+** where multiple cases go to the same block of code, testcase()
+** can insure that all cases are evaluated.
+**
+*/
+#ifdef SQLITE_COVERAGE_TEST
+SQLITE_PRIVATE   void sqlite3Coverage(int);
+# define testcase(X)  if( X ){ sqlite3Coverage(__LINE__); }
+#else
+# define testcase(X)
+#endif
+
+/*
+** The TESTONLY macro is used to enclose variable declarations or
+** other bits of code that are needed to support the arguments
+** within testcase() and assert() macros.
+*/
+#if !defined(NDEBUG) || defined(SQLITE_COVERAGE_TEST)
+# define TESTONLY(X)  X
+#else
+# define TESTONLY(X)
+#endif
+
+/*
+** Sometimes we need a small amount of code such as a variable initialization
+** to setup for a later assert() statement.  We do not want this code to
+** appear when assert() is disabled.  The following macro is therefore
+** used to contain that setup code.  The "VVA" acronym stands for
+** "Verification, Validation, and Accreditation".  In other words, the
+** code within VVA_ONLY() will only run during verification processes.
+*/
+#ifndef NDEBUG
+# define VVA_ONLY(X)  X
+#else
+# define VVA_ONLY(X)
+#endif
+
+/*
+** The ALWAYS and NEVER macros surround boolean expressions which 
+** are intended to always be true or false, respectively.  Such
+** expressions could be omitted from the code completely.  But they
+** are included in a few cases in order to enhance the resilience
+** of SQLite to unexpected behavior - to make the code "self-healing"
+** or "ductile" rather than being "brittle" and crashing at the first
+** hint of unplanned behavior.
+**
+** In other words, ALWAYS and NEVER are added for defensive code.
+**
+** When doing coverage testing ALWAYS and NEVER are hard-coded to
+** be true and false so that the unreachable code then specify will
+** not be counted as untested code.
+*/
+#if defined(SQLITE_COVERAGE_TEST)
+# define ALWAYS(X)      (1)
+# define NEVER(X)       (0)
+#elif !defined(NDEBUG)
+# define ALWAYS(X)      ((X)?1:(assert(0),0))
+# define NEVER(X)       ((X)?(assert(0),1):0)
+#else
+# define ALWAYS(X)      (X)
+# define NEVER(X)       (X)
+#endif
+
+/*
+** Return true (non-zero) if the input is a integer that is too large
+** to fit in 32-bits.  This macro is used inside of various testcase()
+** macros to verify that we have tested SQLite for large-file support.
+*/
+#define IS_BIG_INT(X)  (((X)&~(i64)0xffffffff)!=0)
+
+/*
+** The macro unlikely() is a hint that surrounds a boolean
+** expression that is usually false.  Macro likely() surrounds
+** a boolean expression that is usually true.  GCC is able to
+** use these hints to generate better code, sometimes.
+*/
+#if defined(__GNUC__) && 0
+# define likely(X)    __builtin_expect((X),1)
+# define unlikely(X)  __builtin_expect((X),0)
+#else
+# define likely(X)    !!(X)
+# define unlikely(X)  !!(X)
+#endif
+
+/************** Include sqlite3.h in the middle of sqliteInt.h ***************/
+/************** Begin file sqlite3.h *****************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This header file defines the interface that the SQLite library
+** presents to client programs.  If a C-function, structure, datatype,
+** or constant definition does not appear in this file, then it is
+** not a published API of SQLite, is subject to change without
+** notice, and should not be referenced by programs that use SQLite.
+**
+** Some of the definitions that are in this file are marked as
+** "experimental".  Experimental interfaces are normally new
+** features recently added to SQLite.  We do not anticipate changes
+** to experimental interfaces but reserve the right to make minor changes
+** if experience from use "in the wild" suggest such changes are prudent.
+**
+** The official C-language API documentation for SQLite is derived
+** from comments in this file.  This file is the authoritative source
+** on how SQLite interfaces are suppose to operate.
+**
+** The name of this file under configuration management is "sqlite.h.in".
+** The makefile makes some minor changes to this file (such as inserting
+** the version number) and changes its name to "sqlite3.h" as
+** part of the build process.
+*/
+#ifndef _SQLITE3_H_
+#define _SQLITE3_H_
+#include <stdarg.h>     /* Needed for the definition of va_list */
+
+/*
+** Make sure we can call this stuff from C++.
+*/
+#if 0
+extern "C" {
+#endif
+
+
+/*
+** Add the ability to override 'extern'
+*/
+#ifndef SQLITE_EXTERN
+# define SQLITE_EXTERN extern
+#endif
+
+#ifndef SQLITE_API
+# define SQLITE_API
+#endif
+
+
+/*
+** These no-op macros are used in front of interfaces to mark those
+** interfaces as either deprecated or experimental.  New applications
+** should not use deprecated interfaces - they are support for backwards
+** compatibility only.  Application writers should be aware that
+** experimental interfaces are subject to change in point releases.
+**
+** These macros used to resolve to various kinds of compiler magic that
+** would generate warning messages when they were used.  But that
+** compiler magic ended up generating such a flurry of bug reports
+** that we have taken it all out and gone back to using simple
+** noop macros.
+*/
+#define SQLITE_DEPRECATED
+#define SQLITE_EXPERIMENTAL
+
+/*
+** Ensure these symbols were not defined by some previous header file.
+*/
+#ifdef SQLITE_VERSION
+# undef SQLITE_VERSION
+#endif
+#ifdef SQLITE_VERSION_NUMBER
+# undef SQLITE_VERSION_NUMBER
+#endif
+
+/*
+** CAPI3REF: Compile-Time Library Version Numbers
+**
+** ^(The [SQLITE_VERSION] C preprocessor macro in the sqlite3.h header
+** evaluates to a string literal that is the SQLite version in the
+** format "X.Y.Z" where X is the major version number (always 3 for
+** SQLite3) and Y is the minor version number and Z is the release number.)^
+** ^(The [SQLITE_VERSION_NUMBER] C preprocessor macro resolves to an integer
+** with the value (X*1000000 + Y*1000 + Z) where X, Y, and Z are the same
+** numbers used in [SQLITE_VERSION].)^
+** The SQLITE_VERSION_NUMBER for any given release of SQLite will also
+** be larger than the release from which it is derived.  Either Y will
+** be held constant and Z will be incremented or else Y will be incremented
+** and Z will be reset to zero.
+**
+** Since version 3.6.18, SQLite source code has been stored in the
+** <a href="http://www.fossil-scm.org/">Fossil configuration management
+** system</a>.  ^The SQLITE_SOURCE_ID macro evaluates to
+** a string which identifies a particular check-in of SQLite
+** within its configuration management system.  ^The SQLITE_SOURCE_ID
+** string contains the date and time of the check-in (UTC) and an SHA1
+** hash of the entire source tree.
+**
+** See also: [sqlite3_libversion()],
+** [sqlite3_libversion_number()], [sqlite3_sourceid()],
+** [sqlite_version()] and [sqlite_source_id()].
+*/
+#define SQLITE_VERSION        "3.7.6.3"
+#define SQLITE_VERSION_NUMBER 3007006
+#define SQLITE_SOURCE_ID      "2011-05-19 13:26:54 ed1da510a239ea767a01dc332b667119fa3c908e"
+
+/*
+** CAPI3REF: Run-Time Library Version Numbers
+** KEYWORDS: sqlite3_version, sqlite3_sourceid
+**
+** These interfaces provide the same information as the [SQLITE_VERSION],
+** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
+** but are associated with the library instead of the header file.  ^(Cautious
+** programmers might include assert() statements in their application to
+** verify that values returned by these interfaces match the macros in
+** the header, and thus insure that the application is
+** compiled with matching library and header files.
+**
+** <blockquote><pre>
+** assert( sqlite3_libversion_number()==SQLITE_VERSION_NUMBER );
+** assert( strcmp(sqlite3_sourceid(),SQLITE_SOURCE_ID)==0 );
+** assert( strcmp(sqlite3_libversion(),SQLITE_VERSION)==0 );
+** </pre></blockquote>)^
+**
+** ^The sqlite3_version[] string constant contains the text of [SQLITE_VERSION]
+** macro.  ^The sqlite3_libversion() function returns a pointer to the
+** to the sqlite3_version[] string constant.  The sqlite3_libversion()
+** function is provided for use in DLLs since DLL users usually do not have
+** direct access to string constants within the DLL.  ^The
+** sqlite3_libversion_number() function returns an integer equal to
+** [SQLITE_VERSION_NUMBER].  ^The sqlite3_sourceid() function returns 
+** a pointer to a string constant whose value is the same as the 
+** [SQLITE_SOURCE_ID] C preprocessor macro.
+**
+** See also: [sqlite_version()] and [sqlite_source_id()].
+*/
+SQLITE_API const char sqlite3_version[] = SQLITE_VERSION;
+SQLITE_API const char *sqlite3_libversion(void);
+SQLITE_API const char *sqlite3_sourceid(void);
+SQLITE_API int sqlite3_libversion_number(void);
+
+/*
+** CAPI3REF: Run-Time Library Compilation Options Diagnostics
+**
+** ^The sqlite3_compileoption_used() function returns 0 or 1 
+** indicating whether the specified option was defined at 
+** compile time.  ^The SQLITE_ prefix may be omitted from the 
+** option name passed to sqlite3_compileoption_used().  
+**
+** ^The sqlite3_compileoption_get() function allows iterating
+** over the list of options that were defined at compile time by
+** returning the N-th compile time option string.  ^If N is out of range,
+** sqlite3_compileoption_get() returns a NULL pointer.  ^The SQLITE_ 
+** prefix is omitted from any strings returned by 
+** sqlite3_compileoption_get().
+**
+** ^Support for the diagnostic functions sqlite3_compileoption_used()
+** and sqlite3_compileoption_get() may be omitted by specifying the 
+** [SQLITE_OMIT_COMPILEOPTION_DIAGS] option at compile time.
+**
+** See also: SQL functions [sqlite_compileoption_used()] and
+** [sqlite_compileoption_get()] and the [compile_options pragma].
+*/
+#ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
+SQLITE_API int sqlite3_compileoption_used(const char *zOptName);
+SQLITE_API const char *sqlite3_compileoption_get(int N);
+#endif
+
+/*
+** CAPI3REF: Test To See If The Library Is Threadsafe
+**
+** ^The sqlite3_threadsafe() function returns zero if and only if
+** SQLite was compiled mutexing code omitted due to the
+** [SQLITE_THREADSAFE] compile-time option being set to 0.
+**
+** SQLite can be compiled with or without mutexes.  When
+** the [SQLITE_THREADSAFE] C preprocessor macro is 1 or 2, mutexes
+** are enabled and SQLite is threadsafe.  When the
+** [SQLITE_THREADSAFE] macro is 0, 
+** the mutexes are omitted.  Without the mutexes, it is not safe
+** to use SQLite concurrently from more than one thread.
+**
+** Enabling mutexes incurs a measurable performance penalty.
+** So if speed is of utmost importance, it makes sense to disable
+** the mutexes.  But for maximum safety, mutexes should be enabled.
+** ^The default behavior is for mutexes to be enabled.
+**
+** This interface can be used by an application to make sure that the
+** version of SQLite that it is linking against was compiled with
+** the desired setting of the [SQLITE_THREADSAFE] macro.
+**
+** This interface only reports on the compile-time mutex setting
+** of the [SQLITE_THREADSAFE] flag.  If SQLite is compiled with
+** SQLITE_THREADSAFE=1 or =2 then mutexes are enabled by default but
+** can be fully or partially disabled using a call to [sqlite3_config()]
+** with the verbs [SQLITE_CONFIG_SINGLETHREAD], [SQLITE_CONFIG_MULTITHREAD],
+** or [SQLITE_CONFIG_MUTEX].  ^(The return value of the
+** sqlite3_threadsafe() function shows only the compile-time setting of
+** thread safety, not any run-time changes to that setting made by
+** sqlite3_config(). In other words, the return value from sqlite3_threadsafe()
+** is unchanged by calls to sqlite3_config().)^
+**
+** See the [threading mode] documentation for additional information.
+*/
+SQLITE_API int sqlite3_threadsafe(void);
+
+/*
+** CAPI3REF: Database Connection Handle
+** KEYWORDS: {database connection} {database connections}
+**
+** Each open SQLite database is represented by a pointer to an instance of
+** the opaque structure named "sqlite3".  It is useful to think of an sqlite3
+** pointer as an object.  The [sqlite3_open()], [sqlite3_open16()], and
+** [sqlite3_open_v2()] interfaces are its constructors, and [sqlite3_close()]
+** is its destructor.  There are many other interfaces (such as
+** [sqlite3_prepare_v2()], [sqlite3_create_function()], and
+** [sqlite3_busy_timeout()] to name but three) that are methods on an
+** sqlite3 object.
+*/
+typedef struct sqlite3 sqlite3;
+
+/*
+** CAPI3REF: 64-Bit Integer Types
+** KEYWORDS: sqlite_int64 sqlite_uint64
+**
+** Because there is no cross-platform way to specify 64-bit integer types
+** SQLite includes typedefs for 64-bit signed and unsigned integers.
+**
+** The sqlite3_int64 and sqlite3_uint64 are the preferred type definitions.
+** The sqlite_int64 and sqlite_uint64 types are supported for backwards
+** compatibility only.
+**
+** ^The sqlite3_int64 and sqlite_int64 types can store integer values
+** between -9223372036854775808 and +9223372036854775807 inclusive.  ^The
+** sqlite3_uint64 and sqlite_uint64 types can store integer values 
+** between 0 and +18446744073709551615 inclusive.
+*/
+#ifdef SQLITE_INT64_TYPE
+  typedef SQLITE_INT64_TYPE sqlite_int64;
+  typedef unsigned SQLITE_INT64_TYPE sqlite_uint64;
+#elif defined(_MSC_VER) || defined(__BORLANDC__)
+  typedef __int64 sqlite_int64;
+  typedef unsigned __int64 sqlite_uint64;
+#else
+  typedef long long int sqlite_int64;
+  typedef unsigned long long int sqlite_uint64;
+#endif
+typedef sqlite_int64 sqlite3_int64;
+typedef sqlite_uint64 sqlite3_uint64;
+
+/*
+** If compiling for a processor that lacks floating point support,
+** substitute integer for floating-point.
+*/
+#ifdef SQLITE_OMIT_FLOATING_POINT
+# define double sqlite3_int64
+#endif
+
+/*
+** CAPI3REF: Closing A Database Connection
+**
+** ^The sqlite3_close() routine is the destructor for the [sqlite3] object.
+** ^Calls to sqlite3_close() return SQLITE_OK if the [sqlite3] object is
+** successfully destroyed and all associated resources are deallocated.
+**
+** Applications must [sqlite3_finalize | finalize] all [prepared statements]
+** and [sqlite3_blob_close | close] all [BLOB handles] associated with
+** the [sqlite3] object prior to attempting to close the object.  ^If
+** sqlite3_close() is called on a [database connection] that still has
+** outstanding [prepared statements] or [BLOB handles], then it returns
+** SQLITE_BUSY.
+**
+** ^If [sqlite3_close()] is invoked while a transaction is open,
+** the transaction is automatically rolled back.
+**
+** The C parameter to [sqlite3_close(C)] must be either a NULL
+** pointer or an [sqlite3] object pointer obtained
+** from [sqlite3_open()], [sqlite3_open16()], or
+** [sqlite3_open_v2()], and not previously closed.
+** ^Calling sqlite3_close() with a NULL pointer argument is a 
+** harmless no-op.
+*/
+SQLITE_API int sqlite3_close(sqlite3 *);
+
+/*
+** The type for a callback function.
+** This is legacy and deprecated.  It is included for historical
+** compatibility and is not documented.
+*/
+typedef int (*sqlite3_callback)(void*,int,char**, char**);
+
+/*
+** CAPI3REF: One-Step Query Execution Interface
+**
+** The sqlite3_exec() interface is a convenience wrapper around
+** [sqlite3_prepare_v2()], [sqlite3_step()], and [sqlite3_finalize()],
+** that allows an application to run multiple statements of SQL
+** without having to use a lot of C code. 
+**
+** ^The sqlite3_exec() interface runs zero or more UTF-8 encoded,
+** semicolon-separate SQL statements passed into its 2nd argument,
+** in the context of the [database connection] passed in as its 1st
+** argument.  ^If the callback function of the 3rd argument to
+** sqlite3_exec() is not NULL, then it is invoked for each result row
+** coming out of the evaluated SQL statements.  ^The 4th argument to
+** to sqlite3_exec() is relayed through to the 1st argument of each
+** callback invocation.  ^If the callback pointer to sqlite3_exec()
+** is NULL, then no callback is ever invoked and result rows are
+** ignored.
+**
+** ^If an error occurs while evaluating the SQL statements passed into
+** sqlite3_exec(), then execution of the current statement stops and
+** subsequent statements are skipped.  ^If the 5th parameter to sqlite3_exec()
+** is not NULL then any error message is written into memory obtained
+** from [sqlite3_malloc()] and passed back through the 5th parameter.
+** To avoid memory leaks, the application should invoke [sqlite3_free()]
+** on error message strings returned through the 5th parameter of
+** of sqlite3_exec() after the error message string is no longer needed.
+** ^If the 5th parameter to sqlite3_exec() is not NULL and no errors
+** occur, then sqlite3_exec() sets the pointer in its 5th parameter to
+** NULL before returning.
+**
+** ^If an sqlite3_exec() callback returns non-zero, the sqlite3_exec()
+** routine returns SQLITE_ABORT without invoking the callback again and
+** without running any subsequent SQL statements.
+**
+** ^The 2nd argument to the sqlite3_exec() callback function is the
+** number of columns in the result.  ^The 3rd argument to the sqlite3_exec()
+** callback is an array of pointers to strings obtained as if from
+** [sqlite3_column_text()], one for each column.  ^If an element of a
+** result row is NULL then the corresponding string pointer for the
+** sqlite3_exec() callback is a NULL pointer.  ^The 4th argument to the
+** sqlite3_exec() callback is an array of pointers to strings where each
+** entry represents the name of corresponding result column as obtained
+** from [sqlite3_column_name()].
+**
+** ^If the 2nd parameter to sqlite3_exec() is a NULL pointer, a pointer
+** to an empty string, or a pointer that contains only whitespace and/or 
+** SQL comments, then no SQL statements are evaluated and the database
+** is not changed.
+**
+** Restrictions:
+**
+** <ul>
+** <li> The application must insure that the 1st parameter to sqlite3_exec()
+**      is a valid and open [database connection].
+** <li> The application must not close [database connection] specified by
+**      the 1st parameter to sqlite3_exec() while sqlite3_exec() is running.
+** <li> The application must not modify the SQL statement text passed into
+**      the 2nd parameter of sqlite3_exec() while sqlite3_exec() is running.
+** </ul>
+*/
+SQLITE_API int sqlite3_exec(
+  sqlite3*,                                  /* An open database */
+  const char *sql,                           /* SQL to be evaluated */
+  int (*callback)(void*,int,char**,char**),  /* Callback function */
+  void *,                                    /* 1st argument to callback */
+  char **errmsg                              /* Error msg written here */
+);
+
+/*
+** CAPI3REF: Result Codes
+** KEYWORDS: SQLITE_OK {error code} {error codes}
+** KEYWORDS: {result code} {result codes}
+**
+** Many SQLite functions return an integer result code from the set shown
+** here in order to indicates success or failure.
+**
+** New error codes may be added in future versions of SQLite.
+**
+** See also: [SQLITE_IOERR_READ | extended result codes]
+*/
+#define SQLITE_OK           0   /* Successful result */
+/* beginning-of-error-codes */
+#define SQLITE_ERROR        1   /* SQL error or missing database */
+#define SQLITE_INTERNAL     2   /* Internal logic error in SQLite */
+#define SQLITE_PERM         3   /* Access permission denied */
+#define SQLITE_ABORT        4   /* Callback routine requested an abort */
+#define SQLITE_BUSY         5   /* The database file is locked */
+#define SQLITE_LOCKED       6   /* A table in the database is locked */
+#define SQLITE_NOMEM        7   /* A malloc() failed */
+#define SQLITE_READONLY     8   /* Attempt to write a readonly database */
+#define SQLITE_INTERRUPT    9   /* Operation terminated by sqlite3_interrupt()*/
+#define SQLITE_IOERR       10   /* Some kind of disk I/O error occurred */
+#define SQLITE_CORRUPT     11   /* The database disk image is malformed */
+#define SQLITE_NOTFOUND    12   /* Unknown opcode in sqlite3_file_control() */
+#define SQLITE_FULL        13   /* Insertion failed because database is full */
+#define SQLITE_CANTOPEN    14   /* Unable to open the database file */
+#define SQLITE_PROTOCOL    15   /* Database lock protocol error */
+#define SQLITE_EMPTY       16   /* Database is empty */
+#define SQLITE_SCHEMA      17   /* The database schema changed */
+#define SQLITE_TOOBIG      18   /* String or BLOB exceeds size limit */
+#define SQLITE_CONSTRAINT  19   /* Abort due to constraint violation */
+#define SQLITE_MISMATCH    20   /* Data type mismatch */
+#define SQLITE_MISUSE      21   /* Library used incorrectly */
+#define SQLITE_NOLFS       22   /* Uses OS features not supported on host */
+#define SQLITE_AUTH        23   /* Authorization denied */
+#define SQLITE_FORMAT      24   /* Auxiliary database format error */
+#define SQLITE_RANGE       25   /* 2nd parameter to sqlite3_bind out of range */
+#define SQLITE_NOTADB      26   /* File opened that is not a database file */
+#define SQLITE_ROW         100  /* sqlite3_step() has another row ready */
+#define SQLITE_DONE        101  /* sqlite3_step() has finished executing */
+/* end-of-error-codes */
+
+/*
+** CAPI3REF: Extended Result Codes
+** KEYWORDS: {extended error code} {extended error codes}
+** KEYWORDS: {extended result code} {extended result codes}
+**
+** In its default configuration, SQLite API routines return one of 26 integer
+** [SQLITE_OK | result codes].  However, experience has shown that many of
+** these result codes are too coarse-grained.  They do not provide as
+** much information about problems as programmers might like.  In an effort to
+** address this, newer versions of SQLite (version 3.3.8 and later) include
+** support for additional result codes that provide more detailed information
+** about errors. The extended result codes are enabled or disabled
+** on a per database connection basis using the
+** [sqlite3_extended_result_codes()] API.
+**
+** Some of the available extended result codes are listed here.
+** One may expect the number of extended result codes will be expand
+** over time.  Software that uses extended result codes should expect
+** to see new result codes in future releases of SQLite.
+**
+** The SQLITE_OK result code will never be extended.  It will always
+** be exactly zero.
+*/
+#define SQLITE_IOERR_READ              (SQLITE_IOERR | (1<<8))
+#define SQLITE_IOERR_SHORT_READ        (SQLITE_IOERR | (2<<8))
+#define SQLITE_IOERR_WRITE             (SQLITE_IOERR | (3<<8))
+#define SQLITE_IOERR_FSYNC             (SQLITE_IOERR | (4<<8))
+#define SQLITE_IOERR_DIR_FSYNC         (SQLITE_IOERR | (5<<8))
+#define SQLITE_IOERR_TRUNCATE          (SQLITE_IOERR | (6<<8))
+#define SQLITE_IOERR_FSTAT             (SQLITE_IOERR | (7<<8))
+#define SQLITE_IOERR_UNLOCK            (SQLITE_IOERR | (8<<8))
+#define SQLITE_IOERR_RDLOCK            (SQLITE_IOERR | (9<<8))
+#define SQLITE_IOERR_DELETE            (SQLITE_IOERR | (10<<8))
+#define SQLITE_IOERR_BLOCKED           (SQLITE_IOERR | (11<<8))
+#define SQLITE_IOERR_NOMEM             (SQLITE_IOERR | (12<<8))
+#define SQLITE_IOERR_ACCESS            (SQLITE_IOERR | (13<<8))
+#define SQLITE_IOERR_CHECKRESERVEDLOCK (SQLITE_IOERR | (14<<8))
+#define SQLITE_IOERR_LOCK              (SQLITE_IOERR | (15<<8))
+#define SQLITE_IOERR_CLOSE             (SQLITE_IOERR | (16<<8))
+#define SQLITE_IOERR_DIR_CLOSE         (SQLITE_IOERR | (17<<8))
+#define SQLITE_IOERR_SHMOPEN           (SQLITE_IOERR | (18<<8))
+#define SQLITE_IOERR_SHMSIZE           (SQLITE_IOERR | (19<<8))
+#define SQLITE_IOERR_SHMLOCK           (SQLITE_IOERR | (20<<8))
+#define SQLITE_LOCKED_SHAREDCACHE      (SQLITE_LOCKED |  (1<<8))
+#define SQLITE_BUSY_RECOVERY           (SQLITE_BUSY   |  (1<<8))
+#define SQLITE_CANTOPEN_NOTEMPDIR      (SQLITE_CANTOPEN | (1<<8))
+
+/*
+** CAPI3REF: Flags For File Open Operations
+**
+** These bit values are intended for use in the
+** 3rd parameter to the [sqlite3_open_v2()] interface and
+** in the 4th parameter to the xOpen method of the
+** [sqlite3_vfs] object.
+*/
+#define SQLITE_OPEN_READONLY         0x00000001  /* Ok for sqlite3_open_v2() */
+#define SQLITE_OPEN_READWRITE        0x00000002  /* Ok for sqlite3_open_v2() */
+#define SQLITE_OPEN_CREATE           0x00000004  /* Ok for sqlite3_open_v2() */
+#define SQLITE_OPEN_DELETEONCLOSE    0x00000008  /* VFS only */
+#define SQLITE_OPEN_EXCLUSIVE        0x00000010  /* VFS only */
+#define SQLITE_OPEN_AUTOPROXY        0x00000020  /* VFS only */
+#define SQLITE_OPEN_MAIN_DB          0x00000100  /* VFS only */
+#define SQLITE_OPEN_TEMP_DB          0x00000200  /* VFS only */
+#define SQLITE_OPEN_TRANSIENT_DB     0x00000400  /* VFS only */
+#define SQLITE_OPEN_MAIN_JOURNAL     0x00000800  /* VFS only */
+#define SQLITE_OPEN_TEMP_JOURNAL     0x00001000  /* VFS only */
+#define SQLITE_OPEN_SUBJOURNAL       0x00002000  /* VFS only */
+#define SQLITE_OPEN_MASTER_JOURNAL   0x00004000  /* VFS only */
+#define SQLITE_OPEN_NOMUTEX          0x00008000  /* Ok for sqlite3_open_v2() */
+#define SQLITE_OPEN_FULLMUTEX        0x00010000  /* Ok for sqlite3_open_v2() */
+#define SQLITE_OPEN_SHAREDCACHE      0x00020000  /* Ok for sqlite3_open_v2() */
+#define SQLITE_OPEN_PRIVATECACHE     0x00040000  /* Ok for sqlite3_open_v2() */
+#define SQLITE_OPEN_WAL              0x00080000  /* VFS only */
+
+/* Reserved:                         0x00F00000 */
+
+/*
+** CAPI3REF: Device Characteristics
+**
+** The xDeviceCharacteristics method of the [sqlite3_io_methods]
+** object returns an integer which is a vector of the these
+** bit values expressing I/O characteristics of the mass storage
+** device that holds the file that the [sqlite3_io_methods]
+** refers to.
+**
+** The SQLITE_IOCAP_ATOMIC property means that all writes of
+** any size are atomic.  The SQLITE_IOCAP_ATOMICnnn values
+** mean that writes of blocks that are nnn bytes in size and
+** are aligned to an address which is an integer multiple of
+** nnn are atomic.  The SQLITE_IOCAP_SAFE_APPEND value means
+** that when data is appended to a file, the data is appended
+** first then the size of the file is extended, never the other
+** way around.  The SQLITE_IOCAP_SEQUENTIAL property means that
+** information is written to disk in the same order as calls
+** to xWrite().
+*/
+#define SQLITE_IOCAP_ATOMIC                 0x00000001
+#define SQLITE_IOCAP_ATOMIC512              0x00000002
+#define SQLITE_IOCAP_ATOMIC1K               0x00000004
+#define SQLITE_IOCAP_ATOMIC2K               0x00000008
+#define SQLITE_IOCAP_ATOMIC4K               0x00000010
+#define SQLITE_IOCAP_ATOMIC8K               0x00000020
+#define SQLITE_IOCAP_ATOMIC16K              0x00000040
+#define SQLITE_IOCAP_ATOMIC32K              0x00000080
+#define SQLITE_IOCAP_ATOMIC64K              0x00000100
+#define SQLITE_IOCAP_SAFE_APPEND            0x00000200
+#define SQLITE_IOCAP_SEQUENTIAL             0x00000400
+#define SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN  0x00000800
+
+/*
+** CAPI3REF: File Locking Levels
+**
+** SQLite uses one of these integer values as the second
+** argument to calls it makes to the xLock() and xUnlock() methods
+** of an [sqlite3_io_methods] object.
+*/
+#define SQLITE_LOCK_NONE          0
+#define SQLITE_LOCK_SHARED        1
+#define SQLITE_LOCK_RESERVED      2
+#define SQLITE_LOCK_PENDING       3
+#define SQLITE_LOCK_EXCLUSIVE     4
+
+/*
+** CAPI3REF: Synchronization Type Flags
+**
+** When SQLite invokes the xSync() method of an
+** [sqlite3_io_methods] object it uses a combination of
+** these integer values as the second argument.
+**
+** When the SQLITE_SYNC_DATAONLY flag is used, it means that the
+** sync operation only needs to flush data to mass storage.  Inode
+** information need not be flushed. If the lower four bits of the flag
+** equal SQLITE_SYNC_NORMAL, that means to use normal fsync() semantics.
+** If the lower four bits equal SQLITE_SYNC_FULL, that means
+** to use Mac OS X style fullsync instead of fsync().
+**
+** Do not confuse the SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags
+** with the [PRAGMA synchronous]=NORMAL and [PRAGMA synchronous]=FULL
+** settings.  The [synchronous pragma] determines when calls to the
+** xSync VFS method occur and applies uniformly across all platforms.
+** The SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags determine how
+** energetic or rigorous or forceful the sync operations are and
+** only make a difference on Mac OSX for the default SQLite code.
+** (Third-party VFS implementations might also make the distinction
+** between SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL, but among the
+** operating systems natively supported by SQLite, only Mac OSX
+** cares about the difference.)
+*/
+#define SQLITE_SYNC_NORMAL        0x00002
+#define SQLITE_SYNC_FULL          0x00003
+#define SQLITE_SYNC_DATAONLY      0x00010
+
+/*
+** CAPI3REF: OS Interface Open File Handle
+**
+** An [sqlite3_file] object represents an open file in the 
+** [sqlite3_vfs | OS interface layer].  Individual OS interface
+** implementations will
+** want to subclass this object by appending additional fields
+** for their own use.  The pMethods entry is a pointer to an
+** [sqlite3_io_methods] object that defines methods for performing
+** I/O operations on the open file.
+*/
+typedef struct sqlite3_file sqlite3_file;
+struct sqlite3_file {
+  const struct sqlite3_io_methods *pMethods;  /* Methods for an open file */
+};
+
+/*
+** CAPI3REF: OS Interface File Virtual Methods Object
+**
+** Every file opened by the [sqlite3_vfs] xOpen method populates an
+** [sqlite3_file] object (or, more commonly, a subclass of the
+** [sqlite3_file] object) with a pointer to an instance of this object.
+** This object defines the methods used to perform various operations
+** against the open file represented by the [sqlite3_file] object.
+**
+** If the xOpen method sets the sqlite3_file.pMethods element 
+** to a non-NULL pointer, then the sqlite3_io_methods.xClose method
+** may be invoked even if the xOpen reported that it failed.  The
+** only way to prevent a call to xClose following a failed xOpen
+** is for the xOpen to set the sqlite3_file.pMethods element to NULL.
+**
+** The flags argument to xSync may be one of [SQLITE_SYNC_NORMAL] or
+** [SQLITE_SYNC_FULL].  The first choice is the normal fsync().
+** The second choice is a Mac OS X style fullsync.  The [SQLITE_SYNC_DATAONLY]
+** flag may be ORed in to indicate that only the data of the file
+** and not its inode needs to be synced.
+**
+** The integer values to xLock() and xUnlock() are one of
+** <ul>
+** <li> [SQLITE_LOCK_NONE],
+** <li> [SQLITE_LOCK_SHARED],
+** <li> [SQLITE_LOCK_RESERVED],
+** <li> [SQLITE_LOCK_PENDING], or
+** <li> [SQLITE_LOCK_EXCLUSIVE].
+** </ul>
+** xLock() increases the lock. xUnlock() decreases the lock.
+** The xCheckReservedLock() method checks whether any database connection,
+** either in this process or in some other process, is holding a RESERVED,
+** PENDING, or EXCLUSIVE lock on the file.  It returns true
+** if such a lock exists and false otherwise.
+**
+** The xFileControl() method is a generic interface that allows custom
+** VFS implementations to directly control an open file using the
+** [sqlite3_file_control()] interface.  The second "op" argument is an
+** integer opcode.  The third argument is a generic pointer intended to
+** point to a structure that may contain arguments or space in which to
+** write return values.  Potential uses for xFileControl() might be
+** functions to enable blocking locks with timeouts, to change the
+** locking strategy (for example to use dot-file locks), to inquire
+** about the status of a lock, or to break stale locks.  The SQLite
+** core reserves all opcodes less than 100 for its own use.
+** A [SQLITE_FCNTL_LOCKSTATE | list of opcodes] less than 100 is available.
+** Applications that define a custom xFileControl method should use opcodes
+** greater than 100 to avoid conflicts.  VFS implementations should
+** return [SQLITE_NOTFOUND] for file control opcodes that they do not
+** recognize.
+**
+** The xSectorSize() method returns the sector size of the
+** device that underlies the file.  The sector size is the
+** minimum write that can be performed without disturbing
+** other bytes in the file.  The xDeviceCharacteristics()
+** method returns a bit vector describing behaviors of the
+** underlying device:
+**
+** <ul>
+** <li> [SQLITE_IOCAP_ATOMIC]
+** <li> [SQLITE_IOCAP_ATOMIC512]
+** <li> [SQLITE_IOCAP_ATOMIC1K]
+** <li> [SQLITE_IOCAP_ATOMIC2K]
+** <li> [SQLITE_IOCAP_ATOMIC4K]
+** <li> [SQLITE_IOCAP_ATOMIC8K]
+** <li> [SQLITE_IOCAP_ATOMIC16K]
+** <li> [SQLITE_IOCAP_ATOMIC32K]
+** <li> [SQLITE_IOCAP_ATOMIC64K]
+** <li> [SQLITE_IOCAP_SAFE_APPEND]
+** <li> [SQLITE_IOCAP_SEQUENTIAL]
+** </ul>
+**
+** The SQLITE_IOCAP_ATOMIC property means that all writes of
+** any size are atomic.  The SQLITE_IOCAP_ATOMICnnn values
+** mean that writes of blocks that are nnn bytes in size and
+** are aligned to an address which is an integer multiple of
+** nnn are atomic.  The SQLITE_IOCAP_SAFE_APPEND value means
+** that when data is appended to a file, the data is appended
+** first then the size of the file is extended, never the other
+** way around.  The SQLITE_IOCAP_SEQUENTIAL property means that
+** information is written to disk in the same order as calls
+** to xWrite().
+**
+** If xRead() returns SQLITE_IOERR_SHORT_READ it must also fill
+** in the unread portions of the buffer with zeros.  A VFS that
+** fails to zero-fill short reads might seem to work.  However,
+** failure to zero-fill short reads will eventually lead to
+** database corruption.
+*/
+typedef struct sqlite3_io_methods sqlite3_io_methods;
+struct sqlite3_io_methods {
+  int iVersion;
+  int (*xClose)(sqlite3_file*);
+  int (*xRead)(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst);
+  int (*xWrite)(sqlite3_file*, const void*, int iAmt, sqlite3_int64 iOfst);
+  int (*xTruncate)(sqlite3_file*, sqlite3_int64 size);
+  int (*xSync)(sqlite3_file*, int flags);
+  int (*xFileSize)(sqlite3_file*, sqlite3_int64 *pSize);
+  int (*xLock)(sqlite3_file*, int);
+  int (*xUnlock)(sqlite3_file*, int);
+  int (*xCheckReservedLock)(sqlite3_file*, int *pResOut);
+  int (*xFileControl)(sqlite3_file*, int op, void *pArg);
+  int (*xSectorSize)(sqlite3_file*);
+  int (*xDeviceCharacteristics)(sqlite3_file*);
+  /* Methods above are valid for version 1 */
+  int (*xShmMap)(sqlite3_file*, int iPg, int pgsz, int, void volatile**);
+  int (*xShmLock)(sqlite3_file*, int offset, int n, int flags);
+  void (*xShmBarrier)(sqlite3_file*);
+  int (*xShmUnmap)(sqlite3_file*, int deleteFlag);
+  /* Methods above are valid for version 2 */
+  /* Additional methods may be added in future releases */
+};
+
+/*
+** CAPI3REF: Standard File Control Opcodes
+**
+** These integer constants are opcodes for the xFileControl method
+** of the [sqlite3_io_methods] object and for the [sqlite3_file_control()]
+** interface.
+**
+** The [SQLITE_FCNTL_LOCKSTATE] opcode is used for debugging.  This
+** opcode causes the xFileControl method to write the current state of
+** the lock (one of [SQLITE_LOCK_NONE], [SQLITE_LOCK_SHARED],
+** [SQLITE_LOCK_RESERVED], [SQLITE_LOCK_PENDING], or [SQLITE_LOCK_EXCLUSIVE])
+** into an integer that the pArg argument points to. This capability
+** is used during testing and only needs to be supported when SQLITE_TEST
+** is defined.
+**
+** The [SQLITE_FCNTL_SIZE_HINT] opcode is used by SQLite to give the VFS
+** layer a hint of how large the database file will grow to be during the
+** current transaction.  This hint is not guaranteed to be accurate but it
+** is often close.  The underlying VFS might choose to preallocate database
+** file space based on this hint in order to help writes to the database
+** file run faster.
+**
+** The [SQLITE_FCNTL_CHUNK_SIZE] opcode is used to request that the VFS
+** extends and truncates the database file in chunks of a size specified
+** by the user. The fourth argument to [sqlite3_file_control()] should 
+** point to an integer (type int) containing the new chunk-size to use
+** for the nominated database. Allocating database file space in large
+** chunks (say 1MB at a time), may reduce file-system fragmentation and
+** improve performance on some systems.
+**
+** The [SQLITE_FCNTL_FILE_POINTER] opcode is used to obtain a pointer
+** to the [sqlite3_file] object associated with a particular database
+** connection.  See the [sqlite3_file_control()] documentation for
+** additional information.
+**
+** ^(The [SQLITE_FCNTL_SYNC_OMITTED] opcode is generated internally by
+** SQLite and sent to all VFSes in place of a call to the xSync method
+** when the database connection has [PRAGMA synchronous] set to OFF.)^
+** Some specialized VFSes need this signal in order to operate correctly
+** when [PRAGMA synchronous | PRAGMA synchronous=OFF] is set, but most 
+** VFSes do not need this signal and should silently ignore this opcode.
+** Applications should not call [sqlite3_file_control()] with this
+** opcode as doing so may disrupt the operation of the specialized VFSes
+** that do require it.  
+*/
+#define SQLITE_FCNTL_LOCKSTATE        1
+#define SQLITE_GET_LOCKPROXYFILE      2
+#define SQLITE_SET_LOCKPROXYFILE      3
+#define SQLITE_LAST_ERRNO             4
+#define SQLITE_FCNTL_SIZE_HINT        5
+#define SQLITE_FCNTL_CHUNK_SIZE       6
+#define SQLITE_FCNTL_FILE_POINTER     7
+#define SQLITE_FCNTL_SYNC_OMITTED     8
+
+
+/*
+** CAPI3REF: Mutex Handle
+**
+** The mutex module within SQLite defines [sqlite3_mutex] to be an
+** abstract type for a mutex object.  The SQLite core never looks
+** at the internal representation of an [sqlite3_mutex].  It only
+** deals with pointers to the [sqlite3_mutex] object.
+**
+** Mutexes are created using [sqlite3_mutex_alloc()].
+*/
+typedef struct sqlite3_mutex sqlite3_mutex;
+
+/*
+** CAPI3REF: OS Interface Object
+**
+** An instance of the sqlite3_vfs object defines the interface between
+** the SQLite core and the underlying operating system.  The "vfs"
+** in the name of the object stands for "virtual file system".
+**
+** The value of the iVersion field is initially 1 but may be larger in
+** future versions of SQLite.  Additional fields may be appended to this
+** object when the iVersion value is increased.  Note that the structure
+** of the sqlite3_vfs object changes in the transaction between
+** SQLite version 3.5.9 and 3.6.0 and yet the iVersion field was not
+** modified.
+**
+** The szOsFile field is the size of the subclassed [sqlite3_file]
+** structure used by this VFS.  mxPathname is the maximum length of
+** a pathname in this VFS.
+**
+** Registered sqlite3_vfs objects are kept on a linked list formed by
+** the pNext pointer.  The [sqlite3_vfs_register()]
+** and [sqlite3_vfs_unregister()] interfaces manage this list
+** in a thread-safe way.  The [sqlite3_vfs_find()] interface
+** searches the list.  Neither the application code nor the VFS
+** implementation should use the pNext pointer.
+**
+** The pNext field is the only field in the sqlite3_vfs
+** structure that SQLite will ever modify.  SQLite will only access
+** or modify this field while holding a particular static mutex.
+** The application should never modify anything within the sqlite3_vfs
+** object once the object has been registered.
+**
+** The zName field holds the name of the VFS module.  The name must
+** be unique across all VFS modules.
+**
+** ^SQLite guarantees that the zFilename parameter to xOpen
+** is either a NULL pointer or string obtained
+** from xFullPathname() with an optional suffix added.
+** ^If a suffix is added to the zFilename parameter, it will
+** consist of a single "-" character followed by no more than
+** 10 alphanumeric and/or "-" characters.
+** ^SQLite further guarantees that
+** the string will be valid and unchanged until xClose() is
+** called. Because of the previous sentence,
+** the [sqlite3_file] can safely store a pointer to the
+** filename if it needs to remember the filename for some reason.
+** If the zFilename parameter to xOpen is a NULL pointer then xOpen
+** must invent its own temporary name for the file.  ^Whenever the 
+** xFilename parameter is NULL it will also be the case that the
+** flags parameter will include [SQLITE_OPEN_DELETEONCLOSE].
+**
+** The flags argument to xOpen() includes all bits set in
+** the flags argument to [sqlite3_open_v2()].  Or if [sqlite3_open()]
+** or [sqlite3_open16()] is used, then flags includes at least
+** [SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]. 
+** If xOpen() opens a file read-only then it sets *pOutFlags to
+** include [SQLITE_OPEN_READONLY].  Other bits in *pOutFlags may be set.
+**
+** ^(SQLite will also add one of the following flags to the xOpen()
+** call, depending on the object being opened:
+**
+** <ul>
+** <li>  [SQLITE_OPEN_MAIN_DB]
+** <li>  [SQLITE_OPEN_MAIN_JOURNAL]
+** <li>  [SQLITE_OPEN_TEMP_DB]
+** <li>  [SQLITE_OPEN_TEMP_JOURNAL]
+** <li>  [SQLITE_OPEN_TRANSIENT_DB]
+** <li>  [SQLITE_OPEN_SUBJOURNAL]
+** <li>  [SQLITE_OPEN_MASTER_JOURNAL]
+** <li>  [SQLITE_OPEN_WAL]
+** </ul>)^
+**
+** The file I/O implementation can use the object type flags to
+** change the way it deals with files.  For example, an application
+** that does not care about crash recovery or rollback might make
+** the open of a journal file a no-op.  Writes to this journal would
+** also be no-ops, and any attempt to read the journal would return
+** SQLITE_IOERR.  Or the implementation might recognize that a database
+** file will be doing page-aligned sector reads and writes in a random
+** order and set up its I/O subsystem accordingly.
+**
+** SQLite might also add one of the following flags to the xOpen method:
+**
+** <ul>
+** <li> [SQLITE_OPEN_DELETEONCLOSE]
+** <li> [SQLITE_OPEN_EXCLUSIVE]
+** </ul>
+**
+** The [SQLITE_OPEN_DELETEONCLOSE] flag means the file should be
+** deleted when it is closed.  ^The [SQLITE_OPEN_DELETEONCLOSE]
+** will be set for TEMP databases and their journals, transient
+** databases, and subjournals.
+**
+** ^The [SQLITE_OPEN_EXCLUSIVE] flag is always used in conjunction
+** with the [SQLITE_OPEN_CREATE] flag, which are both directly
+** analogous to the O_EXCL and O_CREAT flags of the POSIX open()
+** API.  The SQLITE_OPEN_EXCLUSIVE flag, when paired with the 
+** SQLITE_OPEN_CREATE, is used to indicate that file should always
+** be created, and that it is an error if it already exists.
+** It is <i>not</i> used to indicate the file should be opened 
+** for exclusive access.
+**
+** ^At least szOsFile bytes of memory are allocated by SQLite
+** to hold the  [sqlite3_file] structure passed as the third
+** argument to xOpen.  The xOpen method does not have to
+** allocate the structure; it should just fill it in.  Note that
+** the xOpen method must set the sqlite3_file.pMethods to either
+** a valid [sqlite3_io_methods] object or to NULL.  xOpen must do
+** this even if the open fails.  SQLite expects that the sqlite3_file.pMethods
+** element will be valid after xOpen returns regardless of the success
+** or failure of the xOpen call.
+**
+** ^The flags argument to xAccess() may be [SQLITE_ACCESS_EXISTS]
+** to test for the existence of a file, or [SQLITE_ACCESS_READWRITE] to
+** test whether a file is readable and writable, or [SQLITE_ACCESS_READ]
+** to test whether a file is at least readable.   The file can be a
+** directory.
+**
+** ^SQLite will always allocate at least mxPathname+1 bytes for the
+** output buffer xFullPathname.  The exact size of the output buffer
+** is also passed as a parameter to both  methods. If the output buffer
+** is not large enough, [SQLITE_CANTOPEN] should be returned. Since this is
+** handled as a fatal error by SQLite, vfs implementations should endeavor
+** to prevent this by setting mxPathname to a sufficiently large value.
+**
+** The xRandomness(), xSleep(), xCurrentTime(), and xCurrentTimeInt64()
+** interfaces are not strictly a part of the filesystem, but they are
+** included in the VFS structure for completeness.
+** The xRandomness() function attempts to return nBytes bytes
+** of good-quality randomness into zOut.  The return value is
+** the actual number of bytes of randomness obtained.
+** The xSleep() method causes the calling thread to sleep for at
+** least the number of microseconds given.  ^The xCurrentTime()
+** method returns a Julian Day Number for the current date and time as
+** a floating point value.
+** ^The xCurrentTimeInt64() method returns, as an integer, the Julian
+** Day Number multipled by 86400000 (the number of milliseconds in 
+** a 24-hour day).  
+** ^SQLite will use the xCurrentTimeInt64() method to get the current
+** date and time if that method is available (if iVersion is 2 or 
+** greater and the function pointer is not NULL) and will fall back
+** to xCurrentTime() if xCurrentTimeInt64() is unavailable.
+**
+** ^The xSetSystemCall(), xGetSystemCall(), and xNestSystemCall() interfaces
+** are not used by the SQLite core.  These optional interfaces are provided
+** by some VFSes to facilitate testing of the VFS code. By overriding 
+** system calls with functions under its control, a test program can
+** simulate faults and error conditions that would otherwise be difficult
+** or impossible to induce.  The set of system calls that can be overridden
+** varies from one VFS to another, and from one version of the same VFS to the
+** next.  Applications that use these interfaces must be prepared for any
+** or all of these interfaces to be NULL or for their behavior to change
+** from one release to the next.  Applications must not attempt to access
+** any of these methods if the iVersion of the VFS is less than 3.
+*/
+typedef struct sqlite3_vfs sqlite3_vfs;
+typedef void (*sqlite3_syscall_ptr)(void);
+struct sqlite3_vfs {
+  int iVersion;            /* Structure version number (currently 3) */
+  int szOsFile;            /* Size of subclassed sqlite3_file */
+  int mxPathname;          /* Maximum file pathname length */
+  sqlite3_vfs *pNext;      /* Next registered VFS */
+  const char *zName;       /* Name of this virtual file system */
+  void *pAppData;          /* Pointer to application-specific data */
+  int (*xOpen)(sqlite3_vfs*, const char *zName, sqlite3_file*,
+               int flags, int *pOutFlags);
+  int (*xDelete)(sqlite3_vfs*, const char *zName, int syncDir);
+  int (*xAccess)(sqlite3_vfs*, const char *zName, int flags, int *pResOut);
+  int (*xFullPathname)(sqlite3_vfs*, const char *zName, int nOut, char *zOut);
+  void *(*xDlOpen)(sqlite3_vfs*, const char *zFilename);
+  void (*xDlError)(sqlite3_vfs*, int nByte, char *zErrMsg);
+  void (*(*xDlSym)(sqlite3_vfs*,void*, const char *zSymbol))(void);
+  void (*xDlClose)(sqlite3_vfs*, void*);
+  int (*xRandomness)(sqlite3_vfs*, int nByte, char *zOut);
+  int (*xSleep)(sqlite3_vfs*, int microseconds);
+  int (*xCurrentTime)(sqlite3_vfs*, double*);
+  int (*xGetLastError)(sqlite3_vfs*, int, char *);
+  /*
+  ** The methods above are in version 1 of the sqlite_vfs object
+  ** definition.  Those that follow are added in version 2 or later
+  */
+  int (*xCurrentTimeInt64)(sqlite3_vfs*, sqlite3_int64*);
+  /*
+  ** The methods above are in versions 1 and 2 of the sqlite_vfs object.
+  ** Those below are for version 3 and greater.
+  */
+  int (*xSetSystemCall)(sqlite3_vfs*, const char *zName, sqlite3_syscall_ptr);
+  sqlite3_syscall_ptr (*xGetSystemCall)(sqlite3_vfs*, const char *zName);
+  const char *(*xNextSystemCall)(sqlite3_vfs*, const char *zName);
+  /*
+  ** The methods above are in versions 1 through 3 of the sqlite_vfs object.
+  ** New fields may be appended in figure versions.  The iVersion
+  ** value will increment whenever this happens. 
+  */
+};
+
+/*
+** CAPI3REF: Flags for the xAccess VFS method
+**
+** These integer constants can be used as the third parameter to
+** the xAccess method of an [sqlite3_vfs] object.  They determine
+** what kind of permissions the xAccess method is looking for.
+** With SQLITE_ACCESS_EXISTS, the xAccess method
+** simply checks whether the file exists.
+** With SQLITE_ACCESS_READWRITE, the xAccess method
+** checks whether the named directory is both readable and writable
+** (in other words, if files can be added, removed, and renamed within
+** the directory).
+** The SQLITE_ACCESS_READWRITE constant is currently used only by the
+** [temp_store_directory pragma], though this could change in a future
+** release of SQLite.
+** With SQLITE_ACCESS_READ, the xAccess method
+** checks whether the file is readable.  The SQLITE_ACCESS_READ constant is
+** currently unused, though it might be used in a future release of
+** SQLite.
+*/
+#define SQLITE_ACCESS_EXISTS    0
+#define SQLITE_ACCESS_READWRITE 1   /* Used by PRAGMA temp_store_directory */
+#define SQLITE_ACCESS_READ      2   /* Unused */
+
+/*
+** CAPI3REF: Flags for the xShmLock VFS method
+**
+** These integer constants define the various locking operations
+** allowed by the xShmLock method of [sqlite3_io_methods].  The
+** following are the only legal combinations of flags to the
+** xShmLock method:
+**
+** <ul>
+** <li>  SQLITE_SHM_LOCK | SQLITE_SHM_SHARED
+** <li>  SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE
+** <li>  SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED
+** <li>  SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE
+** </ul>
+**
+** When unlocking, the same SHARED or EXCLUSIVE flag must be supplied as
+** was given no the corresponding lock.  
+**
+** The xShmLock method can transition between unlocked and SHARED or
+** between unlocked and EXCLUSIVE.  It cannot transition between SHARED
+** and EXCLUSIVE.
+*/
+#define SQLITE_SHM_UNLOCK       1
+#define SQLITE_SHM_LOCK         2
+#define SQLITE_SHM_SHARED       4
+#define SQLITE_SHM_EXCLUSIVE    8
+
+/*
+** CAPI3REF: Maximum xShmLock index
+**
+** The xShmLock method on [sqlite3_io_methods] may use values
+** between 0 and this upper bound as its "offset" argument.
+** The SQLite core will never attempt to acquire or release a
+** lock outside of this range
+*/
+#define SQLITE_SHM_NLOCK        8
+
+
+/*
+** CAPI3REF: Initialize The SQLite Library
+**
+** ^The sqlite3_initialize() routine initializes the
+** SQLite library.  ^The sqlite3_shutdown() routine
+** deallocates any resources that were allocated by sqlite3_initialize().
+** These routines are designed to aid in process initialization and
+** shutdown on embedded systems.  Workstation applications using
+** SQLite normally do not need to invoke either of these routines.
+**
+** A call to sqlite3_initialize() is an "effective" call if it is
+** the first time sqlite3_initialize() is invoked during the lifetime of
+** the process, or if it is the first time sqlite3_initialize() is invoked
+** following a call to sqlite3_shutdown().  ^(Only an effective call
+** of sqlite3_initialize() does any initialization.  All other calls
+** are harmless no-ops.)^
+**
+** A call to sqlite3_shutdown() is an "effective" call if it is the first
+** call to sqlite3_shutdown() since the last sqlite3_initialize().  ^(Only
+** an effective call to sqlite3_shutdown() does any deinitialization.
+** All other valid calls to sqlite3_shutdown() are harmless no-ops.)^
+**
+** The sqlite3_initialize() interface is threadsafe, but sqlite3_shutdown()
+** is not.  The sqlite3_shutdown() interface must only be called from a
+** single thread.  All open [database connections] must be closed and all
+** other SQLite resources must be deallocated prior to invoking
+** sqlite3_shutdown().
+**
+** Among other things, ^sqlite3_initialize() will invoke
+** sqlite3_os_init().  Similarly, ^sqlite3_shutdown()
+** will invoke sqlite3_os_end().
+**
+** ^The sqlite3_initialize() routine returns [SQLITE_OK] on success.
+** ^If for some reason, sqlite3_initialize() is unable to initialize
+** the library (perhaps it is unable to allocate a needed resource such
+** as a mutex) it returns an [error code] other than [SQLITE_OK].
+**
+** ^The sqlite3_initialize() routine is called internally by many other
+** SQLite interfaces so that an application usually does not need to
+** invoke sqlite3_initialize() directly.  For example, [sqlite3_open()]
+** calls sqlite3_initialize() so the SQLite library will be automatically
+** initialized when [sqlite3_open()] is called if it has not be initialized
+** already.  ^However, if SQLite is compiled with the [SQLITE_OMIT_AUTOINIT]
+** compile-time option, then the automatic calls to sqlite3_initialize()
+** are omitted and the application must call sqlite3_initialize() directly
+** prior to using any other SQLite interface.  For maximum portability,
+** it is recommended that applications always invoke sqlite3_initialize()
+** directly prior to using any other SQLite interface.  Future releases
+** of SQLite may require this.  In other words, the behavior exhibited
+** when SQLite is compiled with [SQLITE_OMIT_AUTOINIT] might become the
+** default behavior in some future release of SQLite.
+**
+** The sqlite3_os_init() routine does operating-system specific
+** initialization of the SQLite library.  The sqlite3_os_end()
+** routine undoes the effect of sqlite3_os_init().  Typical tasks
+** performed by these routines include allocation or deallocation
+** of static resources, initialization of global variables,
+** setting up a default [sqlite3_vfs] module, or setting up
+** a default configuration using [sqlite3_config()].
+**
+** The application should never invoke either sqlite3_os_init()
+** or sqlite3_os_end() directly.  The application should only invoke
+** sqlite3_initialize() and sqlite3_shutdown().  The sqlite3_os_init()
+** interface is called automatically by sqlite3_initialize() and
+** sqlite3_os_end() is called by sqlite3_shutdown().  Appropriate
+** implementations for sqlite3_os_init() and sqlite3_os_end()
+** are built into SQLite when it is compiled for Unix, Windows, or OS/2.
+** When [custom builds | built for other platforms]
+** (using the [SQLITE_OS_OTHER=1] compile-time
+** option) the application must supply a suitable implementation for
+** sqlite3_os_init() and sqlite3_os_end().  An application-supplied
+** implementation of sqlite3_os_init() or sqlite3_os_end()
+** must return [SQLITE_OK] on success and some other [error code] upon
+** failure.
+*/
+SQLITE_API int sqlite3_initialize(void);
+SQLITE_API int sqlite3_shutdown(void);
+SQLITE_API int sqlite3_os_init(void);
+SQLITE_API int sqlite3_os_end(void);
+
+/*
+** CAPI3REF: Configuring The SQLite Library
+**
+** The sqlite3_config() interface is used to make global configuration
+** changes to SQLite in order to tune SQLite to the specific needs of
+** the application.  The default configuration is recommended for most
+** applications and so this routine is usually not necessary.  It is
+** provided to support rare applications with unusual needs.
+**
+** The sqlite3_config() interface is not threadsafe.  The application
+** must insure that no other SQLite interfaces are invoked by other
+** threads while sqlite3_config() is running.  Furthermore, sqlite3_config()
+** may only be invoked prior to library initialization using
+** [sqlite3_initialize()] or after shutdown by [sqlite3_shutdown()].
+** ^If sqlite3_config() is called after [sqlite3_initialize()] and before
+** [sqlite3_shutdown()] then it will return SQLITE_MISUSE.
+** Note, however, that ^sqlite3_config() can be called as part of the
+** implementation of an application-defined [sqlite3_os_init()].
+**
+** The first argument to sqlite3_config() is an integer
+** [SQLITE_CONFIG_SINGLETHREAD | configuration option] that determines
+** what property of SQLite is to be configured.  Subsequent arguments
+** vary depending on the [SQLITE_CONFIG_SINGLETHREAD | configuration option]
+** in the first argument.
+**
+** ^When a configuration option is set, sqlite3_config() returns [SQLITE_OK].
+** ^If the option is unknown or SQLite is unable to set the option
+** then this routine returns a non-zero [error code].
+*/
+SQLITE_API int sqlite3_config(int, ...);
+
+/*
+** CAPI3REF: Configure database connections
+**
+** The sqlite3_db_config() interface is used to make configuration
+** changes to a [database connection].  The interface is similar to
+** [sqlite3_config()] except that the changes apply to a single
+** [database connection] (specified in the first argument).
+**
+** The second argument to sqlite3_db_config(D,V,...)  is the
+** [SQLITE_DBCONFIG_LOOKASIDE | configuration verb] - an integer code 
+** that indicates what aspect of the [database connection] is being configured.
+** Subsequent arguments vary depending on the configuration verb.
+**
+** ^Calls to sqlite3_db_config() return SQLITE_OK if and only if
+** the call is considered successful.
+*/
+SQLITE_API int sqlite3_db_config(sqlite3*, int op, ...);
+
+/*
+** CAPI3REF: Memory Allocation Routines
+**
+** An instance of this object defines the interface between SQLite
+** and low-level memory allocation routines.
+**
+** This object is used in only one place in the SQLite interface.
+** A pointer to an instance of this object is the argument to
+** [sqlite3_config()] when the configuration option is
+** [SQLITE_CONFIG_MALLOC] or [SQLITE_CONFIG_GETMALLOC].  
+** By creating an instance of this object
+** and passing it to [sqlite3_config]([SQLITE_CONFIG_MALLOC])
+** during configuration, an application can specify an alternative
+** memory allocation subsystem for SQLite to use for all of its
+** dynamic memory needs.
+**
+** Note that SQLite comes with several [built-in memory allocators]
+** that are perfectly adequate for the overwhelming majority of applications
+** and that this object is only useful to a tiny minority of applications
+** with specialized memory allocation requirements.  This object is
+** also used during testing of SQLite in order to specify an alternative
+** memory allocator that simulates memory out-of-memory conditions in
+** order to verify that SQLite recovers gracefully from such
+** conditions.
+**
+** The xMalloc and xFree methods must work like the
+** malloc() and free() functions from the standard C library.
+** The xRealloc method must work like realloc() from the standard C library
+** with the exception that if the second argument to xRealloc is zero,
+** xRealloc must be a no-op - it must not perform any allocation or
+** deallocation.  ^SQLite guarantees that the second argument to
+** xRealloc is always a value returned by a prior call to xRoundup.
+** And so in cases where xRoundup always returns a positive number,
+** xRealloc can perform exactly as the standard library realloc() and
+** still be in compliance with this specification.
+**
+** xSize should return the allocated size of a memory allocation
+** previously obtained from xMalloc or xRealloc.  The allocated size
+** is always at least as big as the requested size but may be larger.
+**
+** The xRoundup method returns what would be the allocated size of
+** a memory allocation given a particular requested size.  Most memory
+** allocators round up memory allocations at least to the next multiple
+** of 8.  Some allocators round up to a larger multiple or to a power of 2.
+** Every memory allocation request coming in through [sqlite3_malloc()]
+** or [sqlite3_realloc()] first calls xRoundup.  If xRoundup returns 0, 
+** that causes the corresponding memory allocation to fail.
+**
+** The xInit method initializes the memory allocator.  (For example,
+** it might allocate any require mutexes or initialize internal data
+** structures.  The xShutdown method is invoked (indirectly) by
+** [sqlite3_shutdown()] and should deallocate any resources acquired
+** by xInit.  The pAppData pointer is used as the only parameter to
+** xInit and xShutdown.
+**
+** SQLite holds the [SQLITE_MUTEX_STATIC_MASTER] mutex when it invokes
+** the xInit method, so the xInit method need not be threadsafe.  The
+** xShutdown method is only called from [sqlite3_shutdown()] so it does
+** not need to be threadsafe either.  For all other methods, SQLite
+** holds the [SQLITE_MUTEX_STATIC_MEM] mutex as long as the
+** [SQLITE_CONFIG_MEMSTATUS] configuration option is turned on (which
+** it is by default) and so the methods are automatically serialized.
+** However, if [SQLITE_CONFIG_MEMSTATUS] is disabled, then the other
+** methods must be threadsafe or else make their own arrangements for
+** serialization.
+**
+** SQLite will never invoke xInit() more than once without an intervening
+** call to xShutdown().
+*/
+typedef struct sqlite3_mem_methods sqlite3_mem_methods;
+struct sqlite3_mem_methods {
+  void *(*xMalloc)(int);         /* Memory allocation function */
+  void (*xFree)(void*);          /* Free a prior allocation */
+  void *(*xRealloc)(void*,int);  /* Resize an allocation */
+  int (*xSize)(void*);           /* Return the size of an allocation */
+  int (*xRoundup)(int);          /* Round up request size to allocation size */
+  int (*xInit)(void*);           /* Initialize the memory allocator */
+  void (*xShutdown)(void*);      /* Deinitialize the memory allocator */
+  void *pAppData;                /* Argument to xInit() and xShutdown() */
+};
+
+/*
+** CAPI3REF: Configuration Options
+**
+** These constants are the available integer configuration options that
+** can be passed as the first argument to the [sqlite3_config()] interface.
+**
+** New configuration options may be added in future releases of SQLite.
+** Existing configuration options might be discontinued.  Applications
+** should check the return code from [sqlite3_config()] to make sure that
+** the call worked.  The [sqlite3_config()] interface will return a
+** non-zero [error code] if a discontinued or unsupported configuration option
+** is invoked.
+**
+** <dl>
+** <dt>SQLITE_CONFIG_SINGLETHREAD</dt>
+** <dd>There are no arguments to this option.  ^This option sets the
+** [threading mode] to Single-thread.  In other words, it disables
+** all mutexing and puts SQLite into a mode where it can only be used
+** by a single thread.   ^If SQLite is compiled with
+** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
+** it is not possible to change the [threading mode] from its default
+** value of Single-thread and so [sqlite3_config()] will return 
+** [SQLITE_ERROR] if called with the SQLITE_CONFIG_SINGLETHREAD
+** configuration option.</dd>
+**
+** <dt>SQLITE_CONFIG_MULTITHREAD</dt>
+** <dd>There are no arguments to this option.  ^This option sets the
+** [threading mode] to Multi-thread.  In other words, it disables
+** mutexing on [database connection] and [prepared statement] objects.
+** The application is responsible for serializing access to
+** [database connections] and [prepared statements].  But other mutexes
+** are enabled so that SQLite will be safe to use in a multi-threaded
+** environment as long as no two threads attempt to use the same
+** [database connection] at the same time.  ^If SQLite is compiled with
+** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
+** it is not possible to set the Multi-thread [threading mode] and
+** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
+** SQLITE_CONFIG_MULTITHREAD configuration option.</dd>
+**
+** <dt>SQLITE_CONFIG_SERIALIZED</dt>
+** <dd>There are no arguments to this option.  ^This option sets the
+** [threading mode] to Serialized. In other words, this option enables
+** all mutexes including the recursive
+** mutexes on [database connection] and [prepared statement] objects.
+** In this mode (which is the default when SQLite is compiled with
+** [SQLITE_THREADSAFE=1]) the SQLite library will itself serialize access
+** to [database connections] and [prepared statements] so that the
+** application is free to use the same [database connection] or the
+** same [prepared statement] in different threads at the same time.
+** ^If SQLite is compiled with
+** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
+** it is not possible to set the Serialized [threading mode] and
+** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
+** SQLITE_CONFIG_SERIALIZED configuration option.</dd>
+**
+** <dt>SQLITE_CONFIG_MALLOC</dt>
+** <dd> ^(This option takes a single argument which is a pointer to an
+** instance of the [sqlite3_mem_methods] structure.  The argument specifies
+** alternative low-level memory allocation routines to be used in place of
+** the memory allocation routines built into SQLite.)^ ^SQLite makes
+** its own private copy of the content of the [sqlite3_mem_methods] structure
+** before the [sqlite3_config()] call returns.</dd>
+**
+** <dt>SQLITE_CONFIG_GETMALLOC</dt>
+** <dd> ^(This option takes a single argument which is a pointer to an
+** instance of the [sqlite3_mem_methods] structure.  The [sqlite3_mem_methods]
+** structure is filled with the currently defined memory allocation routines.)^
+** This option can be used to overload the default memory allocation
+** routines with a wrapper that simulations memory allocation failure or
+** tracks memory usage, for example. </dd>
+**
+** <dt>SQLITE_CONFIG_MEMSTATUS</dt>
+** <dd> ^This option takes single argument of type int, interpreted as a 
+** boolean, which enables or disables the collection of memory allocation 
+** statistics. ^(When memory allocation statistics are disabled, the 
+** following SQLite interfaces become non-operational:
+**   <ul>
+**   <li> [sqlite3_memory_used()]
+**   <li> [sqlite3_memory_highwater()]
+**   <li> [sqlite3_soft_heap_limit64()]
+**   <li> [sqlite3_status()]
+**   </ul>)^
+** ^Memory allocation statistics are enabled by default unless SQLite is
+** compiled with [SQLITE_DEFAULT_MEMSTATUS]=0 in which case memory
+** allocation statistics are disabled by default.
+** </dd>
+**
+** <dt>SQLITE_CONFIG_SCRATCH</dt>
+** <dd> ^This option specifies a static memory buffer that SQLite can use for
+** scratch memory.  There are three arguments:  A pointer an 8-byte
+** aligned memory buffer from which the scratch allocations will be
+** drawn, the size of each scratch allocation (sz),
+** and the maximum number of scratch allocations (N).  The sz
+** argument must be a multiple of 16.
+** The first argument must be a pointer to an 8-byte aligned buffer
+** of at least sz*N bytes of memory.
+** ^SQLite will use no more than two scratch buffers per thread.  So
+** N should be set to twice the expected maximum number of threads.
+** ^SQLite will never require a scratch buffer that is more than 6
+** times the database page size. ^If SQLite needs needs additional
+** scratch memory beyond what is provided by this configuration option, then 
+** [sqlite3_malloc()] will be used to obtain the memory needed.</dd>
+**
+** <dt>SQLITE_CONFIG_PAGECACHE</dt>
+** <dd> ^This option specifies a static memory buffer that SQLite can use for
+** the database page cache with the default page cache implemenation.  
+** This configuration should not be used if an application-define page
+** cache implementation is loaded using the SQLITE_CONFIG_PCACHE option.
+** There are three arguments to this option: A pointer to 8-byte aligned
+** memory, the size of each page buffer (sz), and the number of pages (N).
+** The sz argument should be the size of the largest database page
+** (a power of two between 512 and 32768) plus a little extra for each
+** page header.  ^The page header size is 20 to 40 bytes depending on
+** the host architecture.  ^It is harmless, apart from the wasted memory,
+** to make sz a little too large.  The first
+** argument should point to an allocation of at least sz*N bytes of memory.
+** ^SQLite will use the memory provided by the first argument to satisfy its
+** memory needs for the first N pages that it adds to cache.  ^If additional
+** page cache memory is needed beyond what is provided by this option, then
+** SQLite goes to [sqlite3_malloc()] for the additional storage space.
+** The pointer in the first argument must
+** be aligned to an 8-byte boundary or subsequent behavior of SQLite
+** will be undefined.</dd>
+**
+** <dt>SQLITE_CONFIG_HEAP</dt>
+** <dd> ^This option specifies a static memory buffer that SQLite will use
+** for all of its dynamic memory allocation needs beyond those provided
+** for by [SQLITE_CONFIG_SCRATCH] and [SQLITE_CONFIG_PAGECACHE].
+** There are three arguments: An 8-byte aligned pointer to the memory,
+** the number of bytes in the memory buffer, and the minimum allocation size.
+** ^If the first pointer (the memory pointer) is NULL, then SQLite reverts
+** to using its default memory allocator (the system malloc() implementation),
+** undoing any prior invocation of [SQLITE_CONFIG_MALLOC].  ^If the
+** memory pointer is not NULL and either [SQLITE_ENABLE_MEMSYS3] or
+** [SQLITE_ENABLE_MEMSYS5] are defined, then the alternative memory
+** allocator is engaged to handle all of SQLites memory allocation needs.
+** The first pointer (the memory pointer) must be aligned to an 8-byte
+** boundary or subsequent behavior of SQLite will be undefined.
+** The minimum allocation size is capped at 2^12. Reasonable values
+** for the minimum allocation size are 2^5 through 2^8.</dd>
+**
+** <dt>SQLITE_CONFIG_MUTEX</dt>
+** <dd> ^(This option takes a single argument which is a pointer to an
+** instance of the [sqlite3_mutex_methods] structure.  The argument specifies
+** alternative low-level mutex routines to be used in place
+** the mutex routines built into SQLite.)^  ^SQLite makes a copy of the
+** content of the [sqlite3_mutex_methods] structure before the call to
+** [sqlite3_config()] returns. ^If SQLite is compiled with
+** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
+** the entire mutexing subsystem is omitted from the build and hence calls to
+** [sqlite3_config()] with the SQLITE_CONFIG_MUTEX configuration option will
+** return [SQLITE_ERROR].</dd>
+**
+** <dt>SQLITE_CONFIG_GETMUTEX</dt>
+** <dd> ^(This option takes a single argument which is a pointer to an
+** instance of the [sqlite3_mutex_methods] structure.  The
+** [sqlite3_mutex_methods]
+** structure is filled with the currently defined mutex routines.)^
+** This option can be used to overload the default mutex allocation
+** routines with a wrapper used to track mutex usage for performance
+** profiling or testing, for example.   ^If SQLite is compiled with
+** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
+** the entire mutexing subsystem is omitted from the build and hence calls to
+** [sqlite3_config()] with the SQLITE_CONFIG_GETMUTEX configuration option will
+** return [SQLITE_ERROR].</dd>
+**
+** <dt>SQLITE_CONFIG_LOOKASIDE</dt>
+** <dd> ^(This option takes two arguments that determine the default
+** memory allocation for the lookaside memory allocator on each
+** [database connection].  The first argument is the
+** size of each lookaside buffer slot and the second is the number of
+** slots allocated to each database connection.)^  ^(This option sets the
+** <i>default</i> lookaside size. The [SQLITE_DBCONFIG_LOOKASIDE]
+** verb to [sqlite3_db_config()] can be used to change the lookaside
+** configuration on individual connections.)^ </dd>
+**
+** <dt>SQLITE_CONFIG_PCACHE</dt>
+** <dd> ^(This option takes a single argument which is a pointer to
+** an [sqlite3_pcache_methods] object.  This object specifies the interface
+** to a custom page cache implementation.)^  ^SQLite makes a copy of the
+** object and uses it for page cache memory allocations.</dd>
+**
+** <dt>SQLITE_CONFIG_GETPCACHE</dt>
+** <dd> ^(This option takes a single argument which is a pointer to an
+** [sqlite3_pcache_methods] object.  SQLite copies of the current
+** page cache implementation into that object.)^ </dd>
+**
+** <dt>SQLITE_CONFIG_LOG</dt>
+** <dd> ^The SQLITE_CONFIG_LOG option takes two arguments: a pointer to a
+** function with a call signature of void(*)(void*,int,const char*), 
+** and a pointer to void. ^If the function pointer is not NULL, it is
+** invoked by [sqlite3_log()] to process each logging event.  ^If the
+** function pointer is NULL, the [sqlite3_log()] interface becomes a no-op.
+** ^The void pointer that is the second argument to SQLITE_CONFIG_LOG is
+** passed through as the first parameter to the application-defined logger
+** function whenever that function is invoked.  ^The second parameter to
+** the logger function is a copy of the first parameter to the corresponding
+** [sqlite3_log()] call and is intended to be a [result code] or an
+** [extended result code].  ^The third parameter passed to the logger is
+** log message after formatting via [sqlite3_snprintf()].
+** The SQLite logging interface is not reentrant; the logger function
+** supplied by the application must not invoke any SQLite interface.
+** In a multi-threaded application, the application-defined logger
+** function must be threadsafe. </dd>
+**
+** </dl>
+*/
+#define SQLITE_CONFIG_SINGLETHREAD  1  /* nil */
+#define SQLITE_CONFIG_MULTITHREAD   2  /* nil */
+#define SQLITE_CONFIG_SERIALIZED    3  /* nil */
+#define SQLITE_CONFIG_MALLOC        4  /* sqlite3_mem_methods* */
+#define SQLITE_CONFIG_GETMALLOC     5  /* sqlite3_mem_methods* */
+#define SQLITE_CONFIG_SCRATCH       6  /* void*, int sz, int N */
+#define SQLITE_CONFIG_PAGECACHE     7  /* void*, int sz, int N */
+#define SQLITE_CONFIG_HEAP          8  /* void*, int nByte, int min */
+#define SQLITE_CONFIG_MEMSTATUS     9  /* boolean */
+#define SQLITE_CONFIG_MUTEX        10  /* sqlite3_mutex_methods* */
+#define SQLITE_CONFIG_GETMUTEX     11  /* sqlite3_mutex_methods* */
+/* previously SQLITE_CONFIG_CHUNKALLOC 12 which is now unused. */ 
+#define SQLITE_CONFIG_LOOKASIDE    13  /* int int */
+#define SQLITE_CONFIG_PCACHE       14  /* sqlite3_pcache_methods* */
+#define SQLITE_CONFIG_GETPCACHE    15  /* sqlite3_pcache_methods* */
+#define SQLITE_CONFIG_LOG          16  /* xFunc, void* */
+
+/*
+** CAPI3REF: Database Connection Configuration Options
+**
+** These constants are the available integer configuration options that
+** can be passed as the second argument to the [sqlite3_db_config()] interface.
+**
+** New configuration options may be added in future releases of SQLite.
+** Existing configuration options might be discontinued.  Applications
+** should check the return code from [sqlite3_db_config()] to make sure that
+** the call worked.  ^The [sqlite3_db_config()] interface will return a
+** non-zero [error code] if a discontinued or unsupported configuration option
+** is invoked.
+**
+** <dl>
+** <dt>SQLITE_DBCONFIG_LOOKASIDE</dt>
+** <dd> ^This option takes three additional arguments that determine the 
+** [lookaside memory allocator] configuration for the [database connection].
+** ^The first argument (the third parameter to [sqlite3_db_config()] is a
+** pointer to a memory buffer to use for lookaside memory.
+** ^The first argument after the SQLITE_DBCONFIG_LOOKASIDE verb
+** may be NULL in which case SQLite will allocate the
+** lookaside buffer itself using [sqlite3_malloc()]. ^The second argument is the
+** size of each lookaside buffer slot.  ^The third argument is the number of
+** slots.  The size of the buffer in the first argument must be greater than
+** or equal to the product of the second and third arguments.  The buffer
+** must be aligned to an 8-byte boundary.  ^If the second argument to
+** SQLITE_DBCONFIG_LOOKASIDE is not a multiple of 8, it is internally
+** rounded down to the next smaller multiple of 8.  ^(The lookaside memory
+** configuration for a database connection can only be changed when that
+** connection is not currently using lookaside memory, or in other words
+** when the "current value" returned by
+** [sqlite3_db_status](D,[SQLITE_CONFIG_LOOKASIDE],...) is zero.
+** Any attempt to change the lookaside memory configuration when lookaside
+** memory is in use leaves the configuration unchanged and returns 
+** [SQLITE_BUSY].)^</dd>
+**
+** <dt>SQLITE_DBCONFIG_ENABLE_FKEY</dt>
+** <dd> ^This option is used to enable or disable the enforcement of
+** [foreign key constraints].  There should be two additional arguments.
+** The first argument is an integer which is 0 to disable FK enforcement,
+** positive to enable FK enforcement or negative to leave FK enforcement
+** unchanged.  The second parameter is a pointer to an integer into which
+** is written 0 or 1 to indicate whether FK enforcement is off or on
+** following this call.  The second parameter may be a NULL pointer, in
+** which case the FK enforcement setting is not reported back. </dd>
+**
+** <dt>SQLITE_DBCONFIG_ENABLE_TRIGGER</dt>
+** <dd> ^This option is used to enable or disable [CREATE TRIGGER | triggers].
+** There should be two additional arguments.
+** The first argument is an integer which is 0 to disable triggers,
+** positive to enable triggers or negative to leave the setting unchanged.
+** The second parameter is a pointer to an integer into which
+** is written 0 or 1 to indicate whether triggers are disabled or enabled
+** following this call.  The second parameter may be a NULL pointer, in
+** which case the trigger setting is not reported back. </dd>
+**
+** </dl>
+*/
+#define SQLITE_DBCONFIG_LOOKASIDE       1001  /* void* int int */
+#define SQLITE_DBCONFIG_ENABLE_FKEY     1002  /* int int* */
+#define SQLITE_DBCONFIG_ENABLE_TRIGGER  1003  /* int int* */
+
+
+/*
+** CAPI3REF: Enable Or Disable Extended Result Codes
+**
+** ^The sqlite3_extended_result_codes() routine enables or disables the
+** [extended result codes] feature of SQLite. ^The extended result
+** codes are disabled by default for historical compatibility.
+*/
+SQLITE_API int sqlite3_extended_result_codes(sqlite3*, int onoff);
+
+/*
+** CAPI3REF: Last Insert Rowid
+**
+** ^Each entry in an SQLite table has a unique 64-bit signed
+** integer key called the [ROWID | "rowid"]. ^The rowid is always available
+** as an undeclared column named ROWID, OID, or _ROWID_ as long as those
+** names are not also used by explicitly declared columns. ^If
+** the table has a column of type [INTEGER PRIMARY KEY] then that column
+** is another alias for the rowid.
+**
+** ^This routine returns the [rowid] of the most recent
+** successful [INSERT] into the database from the [database connection]
+** in the first argument.  ^If no successful [INSERT]s
+** have ever occurred on that database connection, zero is returned.
+**
+** ^(If an [INSERT] occurs within a trigger, then the [rowid] of the inserted
+** row is returned by this routine as long as the trigger is running.
+** But once the trigger terminates, the value returned by this routine
+** reverts to the last value inserted before the trigger fired.)^
+**
+** ^An [INSERT] that fails due to a constraint violation is not a
+** successful [INSERT] and does not change the value returned by this
+** routine.  ^Thus INSERT OR FAIL, INSERT OR IGNORE, INSERT OR ROLLBACK,
+** and INSERT OR ABORT make no changes to the return value of this
+** routine when their insertion fails.  ^(When INSERT OR REPLACE
+** encounters a constraint violation, it does not fail.  The
+** INSERT continues to completion after deleting rows that caused
+** the constraint problem so INSERT OR REPLACE will always change
+** the return value of this interface.)^
+**
+** ^For the purposes of this routine, an [INSERT] is considered to
+** be successful even if it is subsequently rolled back.
+**
+** This function is accessible to SQL statements via the
+** [last_insert_rowid() SQL function].
+**
+** If a separate thread performs a new [INSERT] on the same
+** database connection while the [sqlite3_last_insert_rowid()]
+** function is running and thus changes the last insert [rowid],
+** then the value returned by [sqlite3_last_insert_rowid()] is
+** unpredictable and might not equal either the old or the new
+** last insert [rowid].
+*/
+SQLITE_API sqlite3_int64 sqlite3_last_insert_rowid(sqlite3*);
+
+/*
+** CAPI3REF: Count The Number Of Rows Modified
+**
+** ^This function returns the number of database rows that were changed
+** or inserted or deleted by the most recently completed SQL statement
+** on the [database connection] specified by the first parameter.
+** ^(Only changes that are directly specified by the [INSERT], [UPDATE],
+** or [DELETE] statement are counted.  Auxiliary changes caused by
+** triggers or [foreign key actions] are not counted.)^ Use the
+** [sqlite3_total_changes()] function to find the total number of changes
+** including changes caused by triggers and foreign key actions.
+**
+** ^Changes to a view that are simulated by an [INSTEAD OF trigger]
+** are not counted.  Only real table changes are counted.
+**
+** ^(A "row change" is a change to a single row of a single table
+** caused by an INSERT, DELETE, or UPDATE statement.  Rows that
+** are changed as side effects of [REPLACE] constraint resolution,
+** rollback, ABORT processing, [DROP TABLE], or by any other
+** mechanisms do not count as direct row changes.)^
+**
+** A "trigger context" is a scope of execution that begins and
+** ends with the script of a [CREATE TRIGGER | trigger]. 
+** Most SQL statements are
+** evaluated outside of any trigger.  This is the "top level"
+** trigger context.  If a trigger fires from the top level, a
+** new trigger context is entered for the duration of that one
+** trigger.  Subtriggers create subcontexts for their duration.
+**
+** ^Calling [sqlite3_exec()] or [sqlite3_step()] recursively does
+** not create a new trigger context.
+**
+** ^This function returns the number of direct row changes in the
+** most recent INSERT, UPDATE, or DELETE statement within the same
+** trigger context.
+**
+** ^Thus, when called from the top level, this function returns the
+** number of changes in the most recent INSERT, UPDATE, or DELETE
+** that also occurred at the top level.  ^(Within the body of a trigger,
+** the sqlite3_changes() interface can be called to find the number of
+** changes in the most recently completed INSERT, UPDATE, or DELETE
+** statement within the body of the same trigger.
+** However, the number returned does not include changes
+** caused by subtriggers since those have their own context.)^
+**
+** See also the [sqlite3_total_changes()] interface, the
+** [count_changes pragma], and the [changes() SQL function].
+**
+** If a separate thread makes changes on the same database connection
+** while [sqlite3_changes()] is running then the value returned
+** is unpredictable and not meaningful.
+*/
+SQLITE_API int sqlite3_changes(sqlite3*);
+
+/*
+** CAPI3REF: Total Number Of Rows Modified
+**
+** ^This function returns the number of row changes caused by [INSERT],
+** [UPDATE] or [DELETE] statements since the [database connection] was opened.
+** ^(The count returned by sqlite3_total_changes() includes all changes
+** from all [CREATE TRIGGER | trigger] contexts and changes made by
+** [foreign key actions]. However,
+** the count does not include changes used to implement [REPLACE] constraints,
+** do rollbacks or ABORT processing, or [DROP TABLE] processing.  The
+** count does not include rows of views that fire an [INSTEAD OF trigger],
+** though if the INSTEAD OF trigger makes changes of its own, those changes 
+** are counted.)^
+** ^The sqlite3_total_changes() function counts the changes as soon as
+** the statement that makes them is completed (when the statement handle
+** is passed to [sqlite3_reset()] or [sqlite3_finalize()]).
+**
+** See also the [sqlite3_changes()] interface, the
+** [count_changes pragma], and the [total_changes() SQL function].
+**
+** If a separate thread makes changes on the same database connection
+** while [sqlite3_total_changes()] is running then the value
+** returned is unpredictable and not meaningful.
+*/
+SQLITE_API int sqlite3_total_changes(sqlite3*);
+
+/*
+** CAPI3REF: Interrupt A Long-Running Query
+**
+** ^This function causes any pending database operation to abort and
+** return at its earliest opportunity. This routine is typically
+** called in response to a user action such as pressing "Cancel"
+** or Ctrl-C where the user wants a long query operation to halt
+** immediately.
+**
+** ^It is safe to call this routine from a thread different from the
+** thread that is currently running the database operation.  But it
+** is not safe to call this routine with a [database connection] that
+** is closed or might close before sqlite3_interrupt() returns.
+**
+** ^If an SQL operation is very nearly finished at the time when
+** sqlite3_interrupt() is called, then it might not have an opportunity
+** to be interrupted and might continue to completion.
+**
+** ^An SQL operation that is interrupted will return [SQLITE_INTERRUPT].
+** ^If the interrupted SQL operation is an INSERT, UPDATE, or DELETE
+** that is inside an explicit transaction, then the entire transaction
+** will be rolled back automatically.
+**
+** ^The sqlite3_interrupt(D) call is in effect until all currently running
+** SQL statements on [database connection] D complete.  ^Any new SQL statements
+** that are started after the sqlite3_interrupt() call and before the 
+** running statements reaches zero are interrupted as if they had been
+** running prior to the sqlite3_interrupt() call.  ^New SQL statements
+** that are started after the running statement count reaches zero are
+** not effected by the sqlite3_interrupt().
+** ^A call to sqlite3_interrupt(D) that occurs when there are no running
+** SQL statements is a no-op and has no effect on SQL statements
+** that are started after the sqlite3_interrupt() call returns.
+**
+** If the database connection closes while [sqlite3_interrupt()]
+** is running then bad things will likely happen.
+*/
+SQLITE_API void sqlite3_interrupt(sqlite3*);
+
+/*
+** CAPI3REF: Determine If An SQL Statement Is Complete
+**
+** These routines are useful during command-line input to determine if the
+** currently entered text seems to form a complete SQL statement or
+** if additional input is needed before sending the text into
+** SQLite for parsing.  ^These routines return 1 if the input string
+** appears to be a complete SQL statement.  ^A statement is judged to be
+** complete if it ends with a semicolon token and is not a prefix of a
+** well-formed CREATE TRIGGER statement.  ^Semicolons that are embedded within
+** string literals or quoted identifier names or comments are not
+** independent tokens (they are part of the token in which they are
+** embedded) and thus do not count as a statement terminator.  ^Whitespace
+** and comments that follow the final semicolon are ignored.
+**
+** ^These routines return 0 if the statement is incomplete.  ^If a
+** memory allocation fails, then SQLITE_NOMEM is returned.
+**
+** ^These routines do not parse the SQL statements thus
+** will not detect syntactically incorrect SQL.
+**
+** ^(If SQLite has not been initialized using [sqlite3_initialize()] prior 
+** to invoking sqlite3_complete16() then sqlite3_initialize() is invoked
+** automatically by sqlite3_complete16().  If that initialization fails,
+** then the return value from sqlite3_complete16() will be non-zero
+** regardless of whether or not the input SQL is complete.)^
+**
+** The input to [sqlite3_complete()] must be a zero-terminated
+** UTF-8 string.
+**
+** The input to [sqlite3_complete16()] must be a zero-terminated
+** UTF-16 string in native byte order.
+*/
+SQLITE_API int sqlite3_complete(const char *sql);
+SQLITE_API int sqlite3_complete16(const void *sql);
+
+/*
+** CAPI3REF: Register A Callback To Handle SQLITE_BUSY Errors
+**
+** ^This routine sets a callback function that might be invoked whenever
+** an attempt is made to open a database table that another thread
+** or process has locked.
+**
+** ^If the busy callback is NULL, then [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED]
+** is returned immediately upon encountering the lock.  ^If the busy callback
+** is not NULL, then the callback might be invoked with two arguments.
+**
+** ^The first argument to the busy handler is a copy of the void* pointer which
+** is the third argument to sqlite3_busy_handler().  ^The second argument to
+** the busy handler callback is the number of times that the busy handler has
+** been invoked for this locking event.  ^If the
+** busy callback returns 0, then no additional attempts are made to
+** access the database and [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED] is returned.
+** ^If the callback returns non-zero, then another attempt
+** is made to open the database for reading and the cycle repeats.
+**
+** The presence of a busy handler does not guarantee that it will be invoked
+** when there is lock contention. ^If SQLite determines that invoking the busy
+** handler could result in a deadlock, it will go ahead and return [SQLITE_BUSY]
+** or [SQLITE_IOERR_BLOCKED] instead of invoking the busy handler.
+** Consider a scenario where one process is holding a read lock that
+** it is trying to promote to a reserved lock and
+** a second process is holding a reserved lock that it is trying
+** to promote to an exclusive lock.  The first process cannot proceed
+** because it is blocked by the second and the second process cannot
+** proceed because it is blocked by the first.  If both processes
+** invoke the busy handlers, neither will make any progress.  Therefore,
+** SQLite returns [SQLITE_BUSY] for the first process, hoping that this
+** will induce the first process to release its read lock and allow
+** the second process to proceed.
+**
+** ^The default busy callback is NULL.
+**
+** ^The [SQLITE_BUSY] error is converted to [SQLITE_IOERR_BLOCKED]
+** when SQLite is in the middle of a large transaction where all the
+** changes will not fit into the in-memory cache.  SQLite will
+** already hold a RESERVED lock on the database file, but it needs
+** to promote this lock to EXCLUSIVE so that it can spill cache
+** pages into the database file without harm to concurrent
+** readers.  ^If it is unable to promote the lock, then the in-memory
+** cache will be left in an inconsistent state and so the error
+** code is promoted from the relatively benign [SQLITE_BUSY] to
+** the more severe [SQLITE_IOERR_BLOCKED].  ^This error code promotion
+** forces an automatic rollback of the changes.  See the
+** <a href="/cvstrac/wiki?p=CorruptionFollowingBusyError">
+** CorruptionFollowingBusyError</a> wiki page for a discussion of why
+** this is important.
+**
+** ^(There can only be a single busy handler defined for each
+** [database connection].  Setting a new busy handler clears any
+** previously set handler.)^  ^Note that calling [sqlite3_busy_timeout()]
+** will also set or clear the busy handler.
+**
+** The busy callback should not take any actions which modify the
+** database connection that invoked the busy handler.  Any such actions
+** result in undefined behavior.
+** 
+** A busy handler must not close the database connection
+** or [prepared statement] that invoked the busy handler.
+*/
+SQLITE_API int sqlite3_busy_handler(sqlite3*, int(*)(void*,int), void*);
+
+/*
+** CAPI3REF: Set A Busy Timeout
+**
+** ^This routine sets a [sqlite3_busy_handler | busy handler] that sleeps
+** for a specified amount of time when a table is locked.  ^The handler
+** will sleep multiple times until at least "ms" milliseconds of sleeping
+** have accumulated.  ^After at least "ms" milliseconds of sleeping,
+** the handler returns 0 which causes [sqlite3_step()] to return
+** [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED].
+**
+** ^Calling this routine with an argument less than or equal to zero
+** turns off all busy handlers.
+**
+** ^(There can only be a single busy handler for a particular
+** [database connection] any any given moment.  If another busy handler
+** was defined  (using [sqlite3_busy_handler()]) prior to calling
+** this routine, that other busy handler is cleared.)^
+*/
+SQLITE_API int sqlite3_busy_timeout(sqlite3*, int ms);
+
+/*
+** CAPI3REF: Convenience Routines For Running Queries
+**
+** This is a legacy interface that is preserved for backwards compatibility.
+** Use of this interface is not recommended.
+**
+** Definition: A <b>result table</b> is memory data structure created by the
+** [sqlite3_get_table()] interface.  A result table records the
+** complete query results from one or more queries.
+**
+** The table conceptually has a number of rows and columns.  But
+** these numbers are not part of the result table itself.  These
+** numbers are obtained separately.  Let N be the number of rows
+** and M be the number of columns.
+**
+** A result table is an array of pointers to zero-terminated UTF-8 strings.
+** There are (N+1)*M elements in the array.  The first M pointers point
+** to zero-terminated strings that  contain the names of the columns.
+** The remaining entries all point to query results.  NULL values result
+** in NULL pointers.  All other values are in their UTF-8 zero-terminated
+** string representation as returned by [sqlite3_column_text()].
+**
+** A result table might consist of one or more memory allocations.
+** It is not safe to pass a result table directly to [sqlite3_free()].
+** A result table should be deallocated using [sqlite3_free_table()].
+**
+** ^(As an example of the result table format, suppose a query result
+** is as follows:
+**
+** <blockquote><pre>
+**        Name        | Age
+**        -----------------------
+**        Alice       | 43
+**        Bob         | 28
+**        Cindy       | 21
+** </pre></blockquote>
+**
+** There are two column (M==2) and three rows (N==3).  Thus the
+** result table has 8 entries.  Suppose the result table is stored
+** in an array names azResult.  Then azResult holds this content:
+**
+** <blockquote><pre>
+**        azResult&#91;0] = "Name";
+**        azResult&#91;1] = "Age";
+**        azResult&#91;2] = "Alice";
+**        azResult&#91;3] = "43";
+**        azResult&#91;4] = "Bob";
+**        azResult&#91;5] = "28";
+**        azResult&#91;6] = "Cindy";
+**        azResult&#91;7] = "21";
+** </pre></blockquote>)^
+**
+** ^The sqlite3_get_table() function evaluates one or more
+** semicolon-separated SQL statements in the zero-terminated UTF-8
+** string of its 2nd parameter and returns a result table to the
+** pointer given in its 3rd parameter.
+**
+** After the application has finished with the result from sqlite3_get_table(),
+** it must pass the result table pointer to sqlite3_free_table() in order to
+** release the memory that was malloced.  Because of the way the
+** [sqlite3_malloc()] happens within sqlite3_get_table(), the calling
+** function must not try to call [sqlite3_free()] directly.  Only
+** [sqlite3_free_table()] is able to release the memory properly and safely.
+**
+** The sqlite3_get_table() interface is implemented as a wrapper around
+** [sqlite3_exec()].  The sqlite3_get_table() routine does not have access
+** to any internal data structures of SQLite.  It uses only the public
+** interface defined here.  As a consequence, errors that occur in the
+** wrapper layer outside of the internal [sqlite3_exec()] call are not
+** reflected in subsequent calls to [sqlite3_errcode()] or
+** [sqlite3_errmsg()].
+*/
+SQLITE_API int sqlite3_get_table(
+  sqlite3 *db,          /* An open database */
+  const char *zSql,     /* SQL to be evaluated */
+  char ***pazResult,    /* Results of the query */
+  int *pnRow,           /* Number of result rows written here */
+  int *pnColumn,        /* Number of result columns written here */
+  char **pzErrmsg       /* Error msg written here */
+);
+SQLITE_API void sqlite3_free_table(char **result);
+
+/*
+** CAPI3REF: Formatted String Printing Functions
+**
+** These routines are work-alikes of the "printf()" family of functions
+** from the standard C library.
+**
+** ^The sqlite3_mprintf() and sqlite3_vmprintf() routines write their
+** results into memory obtained from [sqlite3_malloc()].
+** The strings returned by these two routines should be
+** released by [sqlite3_free()].  ^Both routines return a
+** NULL pointer if [sqlite3_malloc()] is unable to allocate enough
+** memory to hold the resulting string.
+**
+** ^(The sqlite3_snprintf() routine is similar to "snprintf()" from
+** the standard C library.  The result is written into the
+** buffer supplied as the second parameter whose size is given by
+** the first parameter. Note that the order of the
+** first two parameters is reversed from snprintf().)^  This is an
+** historical accident that cannot be fixed without breaking
+** backwards compatibility.  ^(Note also that sqlite3_snprintf()
+** returns a pointer to its buffer instead of the number of
+** characters actually written into the buffer.)^  We admit that
+** the number of characters written would be a more useful return
+** value but we cannot change the implementation of sqlite3_snprintf()
+** now without breaking compatibility.
+**
+** ^As long as the buffer size is greater than zero, sqlite3_snprintf()
+** guarantees that the buffer is always zero-terminated.  ^The first
+** parameter "n" is the total size of the buffer, including space for
+** the zero terminator.  So the longest string that can be completely
+** written will be n-1 characters.
+**
+** ^The sqlite3_vsnprintf() routine is a varargs version of sqlite3_snprintf().
+**
+** These routines all implement some additional formatting
+** options that are useful for constructing SQL statements.
+** All of the usual printf() formatting options apply.  In addition, there
+** is are "%q", "%Q", and "%z" options.
+**
+** ^(The %q option works like %s in that it substitutes a null-terminated
+** string from the argument list.  But %q also doubles every '\'' character.
+** %q is designed for use inside a string literal.)^  By doubling each '\''
+** character it escapes that character and allows it to be inserted into
+** the string.
+**
+** For example, assume the string variable zText contains text as follows:
+**
+** <blockquote><pre>
+**  char *zText = "It's a happy day!";
+** </pre></blockquote>
+**
+** One can use this text in an SQL statement as follows:
+**
+** <blockquote><pre>
+**  char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES('%q')", zText);
+**  sqlite3_exec(db, zSQL, 0, 0, 0);
+**  sqlite3_free(zSQL);
+** </pre></blockquote>
+**
+** Because the %q format string is used, the '\'' character in zText
+** is escaped and the SQL generated is as follows:
+**
+** <blockquote><pre>
+**  INSERT INTO table1 VALUES('It''s a happy day!')
+** </pre></blockquote>
+**
+** This is correct.  Had we used %s instead of %q, the generated SQL
+** would have looked like this:
+**
+** <blockquote><pre>
+**  INSERT INTO table1 VALUES('It's a happy day!');
+** </pre></blockquote>
+**
+** This second example is an SQL syntax error.  As a general rule you should
+** always use %q instead of %s when inserting text into a string literal.
+**
+** ^(The %Q option works like %q except it also adds single quotes around
+** the outside of the total string.  Additionally, if the parameter in the
+** argument list is a NULL pointer, %Q substitutes the text "NULL" (without
+** single quotes).)^  So, for example, one could say:
+**
+** <blockquote><pre>
+**  char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES(%Q)", zText);
+**  sqlite3_exec(db, zSQL, 0, 0, 0);
+**  sqlite3_free(zSQL);
+** </pre></blockquote>
+**
+** The code above will render a correct SQL statement in the zSQL
+** variable even if the zText variable is a NULL pointer.
+**
+** ^(The "%z" formatting option works like "%s" but with the
+** addition that after the string has been read and copied into
+** the result, [sqlite3_free()] is called on the input string.)^
+*/
+SQLITE_API char *sqlite3_mprintf(const char*,...);
+SQLITE_API char *sqlite3_vmprintf(const char*, va_list);
+SQLITE_API char *sqlite3_snprintf(int,char*,const char*, ...);
+SQLITE_API char *sqlite3_vsnprintf(int,char*,const char*, va_list);
+
+/*
+** CAPI3REF: Memory Allocation Subsystem
+**
+** The SQLite core uses these three routines for all of its own
+** internal memory allocation needs. "Core" in the previous sentence
+** does not include operating-system specific VFS implementation.  The
+** Windows VFS uses native malloc() and free() for some operations.
+**
+** ^The sqlite3_malloc() routine returns a pointer to a block
+** of memory at least N bytes in length, where N is the parameter.
+** ^If sqlite3_malloc() is unable to obtain sufficient free
+** memory, it returns a NULL pointer.  ^If the parameter N to
+** sqlite3_malloc() is zero or negative then sqlite3_malloc() returns
+** a NULL pointer.
+**
+** ^Calling sqlite3_free() with a pointer previously returned
+** by sqlite3_malloc() or sqlite3_realloc() releases that memory so
+** that it might be reused.  ^The sqlite3_free() routine is
+** a no-op if is called with a NULL pointer.  Passing a NULL pointer
+** to sqlite3_free() is harmless.  After being freed, memory
+** should neither be read nor written.  Even reading previously freed
+** memory might result in a segmentation fault or other severe error.
+** Memory corruption, a segmentation fault, or other severe error
+** might result if sqlite3_free() is called with a non-NULL pointer that
+** was not obtained from sqlite3_malloc() or sqlite3_realloc().
+**
+** ^(The sqlite3_realloc() interface attempts to resize a
+** prior memory allocation to be at least N bytes, where N is the
+** second parameter.  The memory allocation to be resized is the first
+** parameter.)^ ^ If the first parameter to sqlite3_realloc()
+** is a NULL pointer then its behavior is identical to calling
+** sqlite3_malloc(N) where N is the second parameter to sqlite3_realloc().
+** ^If the second parameter to sqlite3_realloc() is zero or
+** negative then the behavior is exactly the same as calling
+** sqlite3_free(P) where P is the first parameter to sqlite3_realloc().
+** ^sqlite3_realloc() returns a pointer to a memory allocation
+** of at least N bytes in size or NULL if sufficient memory is unavailable.
+** ^If M is the size of the prior allocation, then min(N,M) bytes
+** of the prior allocation are copied into the beginning of buffer returned
+** by sqlite3_realloc() and the prior allocation is freed.
+** ^If sqlite3_realloc() returns NULL, then the prior allocation
+** is not freed.
+**
+** ^The memory returned by sqlite3_malloc() and sqlite3_realloc()
+** is always aligned to at least an 8 byte boundary, or to a
+** 4 byte boundary if the [SQLITE_4_BYTE_ALIGNED_MALLOC] compile-time
+** option is used.
+**
+** In SQLite version 3.5.0 and 3.5.1, it was possible to define
+** the SQLITE_OMIT_MEMORY_ALLOCATION which would cause the built-in
+** implementation of these routines to be omitted.  That capability
+** is no longer provided.  Only built-in memory allocators can be used.
+**
+** The Windows OS interface layer calls
+** the system malloc() and free() directly when converting
+** filenames between the UTF-8 encoding used by SQLite
+** and whatever filename encoding is used by the particular Windows
+** installation.  Memory allocation errors are detected, but
+** they are reported back as [SQLITE_CANTOPEN] or
+** [SQLITE_IOERR] rather than [SQLITE_NOMEM].
+**
+** The pointer arguments to [sqlite3_free()] and [sqlite3_realloc()]
+** must be either NULL or else pointers obtained from a prior
+** invocation of [sqlite3_malloc()] or [sqlite3_realloc()] that have
+** not yet been released.
+**
+** The application must not read or write any part of
+** a block of memory after it has been released using
+** [sqlite3_free()] or [sqlite3_realloc()].
+*/
+SQLITE_API void *sqlite3_malloc(int);
+SQLITE_API void *sqlite3_realloc(void*, int);
+SQLITE_API void sqlite3_free(void*);
+
+/*
+** CAPI3REF: Memory Allocator Statistics
+**
+** SQLite provides these two interfaces for reporting on the status
+** of the [sqlite3_malloc()], [sqlite3_free()], and [sqlite3_realloc()]
+** routines, which form the built-in memory allocation subsystem.
+**
+** ^The [sqlite3_memory_used()] routine returns the number of bytes
+** of memory currently outstanding (malloced but not freed).
+** ^The [sqlite3_memory_highwater()] routine returns the maximum
+** value of [sqlite3_memory_used()] since the high-water mark
+** was last reset.  ^The values returned by [sqlite3_memory_used()] and
+** [sqlite3_memory_highwater()] include any overhead
+** added by SQLite in its implementation of [sqlite3_malloc()],
+** but not overhead added by the any underlying system library
+** routines that [sqlite3_malloc()] may call.
+**
+** ^The memory high-water mark is reset to the current value of
+** [sqlite3_memory_used()] if and only if the parameter to
+** [sqlite3_memory_highwater()] is true.  ^The value returned
+** by [sqlite3_memory_highwater(1)] is the high-water mark
+** prior to the reset.
+*/
+SQLITE_API sqlite3_int64 sqlite3_memory_used(void);
+SQLITE_API sqlite3_int64 sqlite3_memory_highwater(int resetFlag);
+
+/*
+** CAPI3REF: Pseudo-Random Number Generator
+**
+** SQLite contains a high-quality pseudo-random number generator (PRNG) used to
+** select random [ROWID | ROWIDs] when inserting new records into a table that
+** already uses the largest possible [ROWID].  The PRNG is also used for
+** the build-in random() and randomblob() SQL functions.  This interface allows
+** applications to access the same PRNG for other purposes.
+**
+** ^A call to this routine stores N bytes of randomness into buffer P.
+**
+** ^The first time this routine is invoked (either internally or by
+** the application) the PRNG is seeded using randomness obtained
+** from the xRandomness method of the default [sqlite3_vfs] object.
+** ^On all subsequent invocations, the pseudo-randomness is generated
+** internally and without recourse to the [sqlite3_vfs] xRandomness
+** method.
+*/
+SQLITE_API void sqlite3_randomness(int N, void *P);
+
+/*
+** CAPI3REF: Compile-Time Authorization Callbacks
+**
+** ^This routine registers an authorizer callback with a particular
+** [database connection], supplied in the first argument.
+** ^The authorizer callback is invoked as SQL statements are being compiled
+** by [sqlite3_prepare()] or its variants [sqlite3_prepare_v2()],
+** [sqlite3_prepare16()] and [sqlite3_prepare16_v2()].  ^At various
+** points during the compilation process, as logic is being created
+** to perform various actions, the authorizer callback is invoked to
+** see if those actions are allowed.  ^The authorizer callback should
+** return [SQLITE_OK] to allow the action, [SQLITE_IGNORE] to disallow the
+** specific action but allow the SQL statement to continue to be
+** compiled, or [SQLITE_DENY] to cause the entire SQL statement to be
+** rejected with an error.  ^If the authorizer callback returns
+** any value other than [SQLITE_IGNORE], [SQLITE_OK], or [SQLITE_DENY]
+** then the [sqlite3_prepare_v2()] or equivalent call that triggered
+** the authorizer will fail with an error message.
+**
+** When the callback returns [SQLITE_OK], that means the operation
+** requested is ok.  ^When the callback returns [SQLITE_DENY], the
+** [sqlite3_prepare_v2()] or equivalent call that triggered the
+** authorizer will fail with an error message explaining that
+** access is denied. 
+**
+** ^The first parameter to the authorizer callback is a copy of the third
+** parameter to the sqlite3_set_authorizer() interface. ^The second parameter
+** to the callback is an integer [SQLITE_COPY | action code] that specifies
+** the particular action to be authorized. ^The third through sixth parameters
+** to the callback are zero-terminated strings that contain additional
+** details about the action to be authorized.
+**
+** ^If the action code is [SQLITE_READ]
+** and the callback returns [SQLITE_IGNORE] then the
+** [prepared statement] statement is constructed to substitute
+** a NULL value in place of the table column that would have
+** been read if [SQLITE_OK] had been returned.  The [SQLITE_IGNORE]
+** return can be used to deny an untrusted user access to individual
+** columns of a table.
+** ^If the action code is [SQLITE_DELETE] and the callback returns
+** [SQLITE_IGNORE] then the [DELETE] operation proceeds but the
+** [truncate optimization] is disabled and all rows are deleted individually.
+**
+** An authorizer is used when [sqlite3_prepare | preparing]
+** SQL statements from an untrusted source, to ensure that the SQL statements
+** do not try to access data they are not allowed to see, or that they do not
+** try to execute malicious statements that damage the database.  For
+** example, an application may allow a user to enter arbitrary
+** SQL queries for evaluation by a database.  But the application does
+** not want the user to be able to make arbitrary changes to the
+** database.  An authorizer could then be put in place while the
+** user-entered SQL is being [sqlite3_prepare | prepared] that
+** disallows everything except [SELECT] statements.
+**
+** Applications that need to process SQL from untrusted sources
+** might also consider lowering resource limits using [sqlite3_limit()]
+** and limiting database size using the [max_page_count] [PRAGMA]
+** in addition to using an authorizer.
+**
+** ^(Only a single authorizer can be in place on a database connection
+** at a time.  Each call to sqlite3_set_authorizer overrides the
+** previous call.)^  ^Disable the authorizer by installing a NULL callback.
+** The authorizer is disabled by default.
+**
+** The authorizer callback must not do anything that will modify
+** the database connection that invoked the authorizer callback.
+** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
+** database connections for the meaning of "modify" in this paragraph.
+**
+** ^When [sqlite3_prepare_v2()] is used to prepare a statement, the
+** statement might be re-prepared during [sqlite3_step()] due to a 
+** schema change.  Hence, the application should ensure that the
+** correct authorizer callback remains in place during the [sqlite3_step()].
+**
+** ^Note that the authorizer callback is invoked only during
+** [sqlite3_prepare()] or its variants.  Authorization is not
+** performed during statement evaluation in [sqlite3_step()], unless
+** as stated in the previous paragraph, sqlite3_step() invokes
+** sqlite3_prepare_v2() to reprepare a statement after a schema change.
+*/
+SQLITE_API int sqlite3_set_authorizer(
+  sqlite3*,
+  int (*xAuth)(void*,int,const char*,const char*,const char*,const char*),
+  void *pUserData
+);
+
+/*
+** CAPI3REF: Authorizer Return Codes
+**
+** The [sqlite3_set_authorizer | authorizer callback function] must
+** return either [SQLITE_OK] or one of these two constants in order
+** to signal SQLite whether or not the action is permitted.  See the
+** [sqlite3_set_authorizer | authorizer documentation] for additional
+** information.
+*/
+#define SQLITE_DENY   1   /* Abort the SQL statement with an error */
+#define SQLITE_IGNORE 2   /* Don't allow access, but don't generate an error */
+
+/*
+** CAPI3REF: Authorizer Action Codes
+**
+** The [sqlite3_set_authorizer()] interface registers a callback function
+** that is invoked to authorize certain SQL statement actions.  The
+** second parameter to the callback is an integer code that specifies
+** what action is being authorized.  These are the integer action codes that
+** the authorizer callback may be passed.
+**
+** These action code values signify what kind of operation is to be
+** authorized.  The 3rd and 4th parameters to the authorization
+** callback function will be parameters or NULL depending on which of these
+** codes is used as the second parameter.  ^(The 5th parameter to the
+** authorizer callback is the name of the database ("main", "temp",
+** etc.) if applicable.)^  ^The 6th parameter to the authorizer callback
+** is the name of the inner-most trigger or view that is responsible for
+** the access attempt or NULL if this access attempt is directly from
+** top-level SQL code.
+*/
+/******************************************* 3rd ************ 4th ***********/
+#define SQLITE_CREATE_INDEX          1   /* Index Name      Table Name      */
+#define SQLITE_CREATE_TABLE          2   /* Table Name      NULL            */
+#define SQLITE_CREATE_TEMP_INDEX     3   /* Index Name      Table Name      */
+#define SQLITE_CREATE_TEMP_TABLE     4   /* Table Name      NULL            */
+#define SQLITE_CREATE_TEMP_TRIGGER   5   /* Trigger Name    Table Name      */
+#define SQLITE_CREATE_TEMP_VIEW      6   /* View Name       NULL            */
+#define SQLITE_CREATE_TRIGGER        7   /* Trigger Name    Table Name      */
+#define SQLITE_CREATE_VIEW           8   /* View Name       NULL            */
+#define SQLITE_DELETE                9   /* Table Name      NULL            */
+#define SQLITE_DROP_INDEX           10   /* Index Name      Table Name      */
+#define SQLITE_DROP_TABLE           11   /* Table Name      NULL            */
+#define SQLITE_DROP_TEMP_INDEX      12   /* Index Name      Table Name      */
+#define SQLITE_DROP_TEMP_TABLE      13   /* Table Name      NULL            */
+#define SQLITE_DROP_TEMP_TRIGGER    14   /* Trigger Name    Table Name      */
+#define SQLITE_DROP_TEMP_VIEW       15   /* View Name       NULL            */
+#define SQLITE_DROP_TRIGGER         16   /* Trigger Name    Table Name      */
+#define SQLITE_DROP_VIEW            17   /* View Name       NULL            */
+#define SQLITE_INSERT               18   /* Table Name      NULL            */
+#define SQLITE_PRAGMA               19   /* Pragma Name     1st arg or NULL */
+#define SQLITE_READ                 20   /* Table Name      Column Name     */
+#define SQLITE_SELECT               21   /* NULL            NULL            */
+#define SQLITE_TRANSACTION          22   /* Operation       NULL            */
+#define SQLITE_UPDATE               23   /* Table Name      Column Name     */
+#define SQLITE_ATTACH               24   /* Filename        NULL            */
+#define SQLITE_DETACH               25   /* Database Name   NULL            */
+#define SQLITE_ALTER_TABLE          26   /* Database Name   Table Name      */
+#define SQLITE_REINDEX              27   /* Index Name      NULL            */
+#define SQLITE_ANALYZE              28   /* Table Name      NULL            */
+#define SQLITE_CREATE_VTABLE        29   /* Table Name      Module Name     */
+#define SQLITE_DROP_VTABLE          30   /* Table Name      Module Name     */
+#define SQLITE_FUNCTION             31   /* NULL            Function Name   */
+#define SQLITE_SAVEPOINT            32   /* Operation       Savepoint Name  */
+#define SQLITE_COPY                  0   /* No longer used */
+
+/*
+** CAPI3REF: Tracing And Profiling Functions
+**
+** These routines register callback functions that can be used for
+** tracing and profiling the execution of SQL statements.
+**
+** ^The callback function registered by sqlite3_trace() is invoked at
+** various times when an SQL statement is being run by [sqlite3_step()].
+** ^The sqlite3_trace() callback is invoked with a UTF-8 rendering of the
+** SQL statement text as the statement first begins executing.
+** ^(Additional sqlite3_trace() callbacks might occur
+** as each triggered subprogram is entered.  The callbacks for triggers
+** contain a UTF-8 SQL comment that identifies the trigger.)^
+**
+** ^The callback function registered by sqlite3_profile() is invoked
+** as each SQL statement finishes.  ^The profile callback contains
+** the original statement text and an estimate of wall-clock time
+** of how long that statement took to run.  ^The profile callback
+** time is in units of nanoseconds, however the current implementation
+** is only capable of millisecond resolution so the six least significant
+** digits in the time are meaningless.  Future versions of SQLite
+** might provide greater resolution on the profiler callback.  The
+** sqlite3_profile() function is considered experimental and is
+** subject to change in future versions of SQLite.
+*/
+SQLITE_API void *sqlite3_trace(sqlite3*, void(*xTrace)(void*,const char*), void*);
+SQLITE_API SQLITE_EXPERIMENTAL void *sqlite3_profile(sqlite3*,
+   void(*xProfile)(void*,const char*,sqlite3_uint64), void*);
+
+/*
+** CAPI3REF: Query Progress Callbacks
+**
+** ^The sqlite3_progress_handler(D,N,X,P) interface causes the callback
+** function X to be invoked periodically during long running calls to
+** [sqlite3_exec()], [sqlite3_step()] and [sqlite3_get_table()] for
+** database connection D.  An example use for this
+** interface is to keep a GUI updated during a large query.
+**
+** ^The parameter P is passed through as the only parameter to the 
+** callback function X.  ^The parameter N is the number of 
+** [virtual machine instructions] that are evaluated between successive
+** invocations of the callback X.
+**
+** ^Only a single progress handler may be defined at one time per
+** [database connection]; setting a new progress handler cancels the
+** old one.  ^Setting parameter X to NULL disables the progress handler.
+** ^The progress handler is also disabled by setting N to a value less
+** than 1.
+**
+** ^If the progress callback returns non-zero, the operation is
+** interrupted.  This feature can be used to implement a
+** "Cancel" button on a GUI progress dialog box.
+**
+** The progress handler callback must not do anything that will modify
+** the database connection that invoked the progress handler.
+** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
+** database connections for the meaning of "modify" in this paragraph.
+**
+*/
+SQLITE_API void sqlite3_progress_handler(sqlite3*, int, int(*)(void*), void*);
+
+/*
+** CAPI3REF: Opening A New Database Connection
+**
+** ^These routines open an SQLite database file whose name is given by the
+** filename argument. ^The filename argument is interpreted as UTF-8 for
+** sqlite3_open() and sqlite3_open_v2() and as UTF-16 in the native byte
+** order for sqlite3_open16(). ^(A [database connection] handle is usually
+** returned in *ppDb, even if an error occurs.  The only exception is that
+** if SQLite is unable to allocate memory to hold the [sqlite3] object,
+** a NULL will be written into *ppDb instead of a pointer to the [sqlite3]
+** object.)^ ^(If the database is opened (and/or created) successfully, then
+** [SQLITE_OK] is returned.  Otherwise an [error code] is returned.)^ ^The
+** [sqlite3_errmsg()] or [sqlite3_errmsg16()] routines can be used to obtain
+** an English language description of the error following a failure of any
+** of the sqlite3_open() routines.
+**
+** ^The default encoding for the database will be UTF-8 if
+** sqlite3_open() or sqlite3_open_v2() is called and
+** UTF-16 in the native byte order if sqlite3_open16() is used.
+**
+** Whether or not an error occurs when it is opened, resources
+** associated with the [database connection] handle should be released by
+** passing it to [sqlite3_close()] when it is no longer required.
+**
+** The sqlite3_open_v2() interface works like sqlite3_open()
+** except that it accepts two additional parameters for additional control
+** over the new database connection.  ^(The flags parameter to
+** sqlite3_open_v2() can take one of
+** the following three values, optionally combined with the 
+** [SQLITE_OPEN_NOMUTEX], [SQLITE_OPEN_FULLMUTEX], [SQLITE_OPEN_SHAREDCACHE],
+** and/or [SQLITE_OPEN_PRIVATECACHE] flags:)^
+**
+** <dl>
+** ^(<dt>[SQLITE_OPEN_READONLY]</dt>
+** <dd>The database is opened in read-only mode.  If the database does not
+** already exist, an error is returned.</dd>)^
+**
+** ^(<dt>[SQLITE_OPEN_READWRITE]</dt>
+** <dd>The database is opened for reading and writing if possible, or reading
+** only if the file is write protected by the operating system.  In either
+** case the database must already exist, otherwise an error is returned.</dd>)^
+**
+** ^(<dt>[SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]</dt>
+** <dd>The database is opened for reading and writing, and is created if
+** it does not already exist. This is the behavior that is always used for
+** sqlite3_open() and sqlite3_open16().</dd>)^
+** </dl>
+**
+** If the 3rd parameter to sqlite3_open_v2() is not one of the
+** combinations shown above or one of the combinations shown above combined
+** with the [SQLITE_OPEN_NOMUTEX], [SQLITE_OPEN_FULLMUTEX],
+** [SQLITE_OPEN_SHAREDCACHE] and/or [SQLITE_OPEN_PRIVATECACHE] flags,
+** then the behavior is undefined.
+**
+** ^If the [SQLITE_OPEN_NOMUTEX] flag is set, then the database connection
+** opens in the multi-thread [threading mode] as long as the single-thread
+** mode has not been set at compile-time or start-time.  ^If the
+** [SQLITE_OPEN_FULLMUTEX] flag is set then the database connection opens
+** in the serialized [threading mode] unless single-thread was
+** previously selected at compile-time or start-time.
+** ^The [SQLITE_OPEN_SHAREDCACHE] flag causes the database connection to be
+** eligible to use [shared cache mode], regardless of whether or not shared
+** cache is enabled using [sqlite3_enable_shared_cache()].  ^The
+** [SQLITE_OPEN_PRIVATECACHE] flag causes the database connection to not
+** participate in [shared cache mode] even if it is enabled.
+**
+** ^If the filename is ":memory:", then a private, temporary in-memory database
+** is created for the connection.  ^This in-memory database will vanish when
+** the database connection is closed.  Future versions of SQLite might
+** make use of additional special filenames that begin with the ":" character.
+** It is recommended that when a database filename actually does begin with
+** a ":" character you should prefix the filename with a pathname such as
+** "./" to avoid ambiguity.
+**
+** ^If the filename is an empty string, then a private, temporary
+** on-disk database will be created.  ^This private database will be
+** automatically deleted as soon as the database connection is closed.
+**
+** ^The fourth parameter to sqlite3_open_v2() is the name of the
+** [sqlite3_vfs] object that defines the operating system interface that
+** the new database connection should use.  ^If the fourth parameter is
+** a NULL pointer then the default [sqlite3_vfs] object is used.
+**
+** <b>Note to Windows users:</b>  The encoding used for the filename argument
+** of sqlite3_open() and sqlite3_open_v2() must be UTF-8, not whatever
+** codepage is currently defined.  Filenames containing international
+** characters must be converted to UTF-8 prior to passing them into
+** sqlite3_open() or sqlite3_open_v2().
+*/
+SQLITE_API int sqlite3_open(
+  const char *filename,   /* Database filename (UTF-8) */
+  sqlite3 **ppDb          /* OUT: SQLite db handle */
+);
+SQLITE_API int sqlite3_open16(
+  const void *filename,   /* Database filename (UTF-16) */
+  sqlite3 **ppDb          /* OUT: SQLite db handle */
+);
+SQLITE_API int sqlite3_open_v2(
+  const char *filename,   /* Database filename (UTF-8) */
+  sqlite3 **ppDb,         /* OUT: SQLite db handle */
+  int flags,              /* Flags */
+  const char *zVfs        /* Name of VFS module to use */
+);
+
+/*
+** CAPI3REF: Error Codes And Messages
+**
+** ^The sqlite3_errcode() interface returns the numeric [result code] or
+** [extended result code] for the most recent failed sqlite3_* API call
+** associated with a [database connection]. If a prior API call failed
+** but the most recent API call succeeded, the return value from
+** sqlite3_errcode() is undefined.  ^The sqlite3_extended_errcode()
+** interface is the same except that it always returns the 
+** [extended result code] even when extended result codes are
+** disabled.
+**
+** ^The sqlite3_errmsg() and sqlite3_errmsg16() return English-language
+** text that describes the error, as either UTF-8 or UTF-16 respectively.
+** ^(Memory to hold the error message string is managed internally.
+** The application does not need to worry about freeing the result.
+** However, the error string might be overwritten or deallocated by
+** subsequent calls to other SQLite interface functions.)^
+**
+** When the serialized [threading mode] is in use, it might be the
+** case that a second error occurs on a separate thread in between
+** the time of the first error and the call to these interfaces.
+** When that happens, the second error will be reported since these
+** interfaces always report the most recent result.  To avoid
+** this, each thread can obtain exclusive use of the [database connection] D
+** by invoking [sqlite3_mutex_enter]([sqlite3_db_mutex](D)) before beginning
+** to use D and invoking [sqlite3_mutex_leave]([sqlite3_db_mutex](D)) after
+** all calls to the interfaces listed here are completed.
+**
+** If an interface fails with SQLITE_MISUSE, that means the interface
+** was invoked incorrectly by the application.  In that case, the
+** error code and message may or may not be set.
+*/
+SQLITE_API int sqlite3_errcode(sqlite3 *db);
+SQLITE_API int sqlite3_extended_errcode(sqlite3 *db);
+SQLITE_API const char *sqlite3_errmsg(sqlite3*);
+SQLITE_API const void *sqlite3_errmsg16(sqlite3*);
+
+/*
+** CAPI3REF: SQL Statement Object
+** KEYWORDS: {prepared statement} {prepared statements}
+**
+** An instance of this object represents a single SQL statement.
+** This object is variously known as a "prepared statement" or a
+** "compiled SQL statement" or simply as a "statement".
+**
+** The life of a statement object goes something like this:
+**
+** <ol>
+** <li> Create the object using [sqlite3_prepare_v2()] or a related
+**      function.
+** <li> Bind values to [host parameters] using the sqlite3_bind_*()
+**      interfaces.
+** <li> Run the SQL by calling [sqlite3_step()] one or more times.
+** <li> Reset the statement using [sqlite3_reset()] then go back
+**      to step 2.  Do this zero or more times.
+** <li> Destroy the object using [sqlite3_finalize()].
+** </ol>
+**
+** Refer to documentation on individual methods above for additional
+** information.
+*/
+typedef struct sqlite3_stmt sqlite3_stmt;
+
+/*
+** CAPI3REF: Run-time Limits
+**
+** ^(This interface allows the size of various constructs to be limited
+** on a connection by connection basis.  The first parameter is the
+** [database connection] whose limit is to be set or queried.  The
+** second parameter is one of the [limit categories] that define a
+** class of constructs to be size limited.  The third parameter is the
+** new limit for that construct.)^
+**
+** ^If the new limit is a negative number, the limit is unchanged.
+** ^(For each limit category SQLITE_LIMIT_<i>NAME</i> there is a 
+** [limits | hard upper bound]
+** set at compile-time by a C preprocessor macro called
+** [limits | SQLITE_MAX_<i>NAME</i>].
+** (The "_LIMIT_" in the name is changed to "_MAX_".))^
+** ^Attempts to increase a limit above its hard upper bound are
+** silently truncated to the hard upper bound.
+**
+** ^Regardless of whether or not the limit was changed, the 
+** [sqlite3_limit()] interface returns the prior value of the limit.
+** ^Hence, to find the current value of a limit without changing it,
+** simply invoke this interface with the third parameter set to -1.
+**
+** Run-time limits are intended for use in applications that manage
+** both their own internal database and also databases that are controlled
+** by untrusted external sources.  An example application might be a
+** web browser that has its own databases for storing history and
+** separate databases controlled by JavaScript applications downloaded
+** off the Internet.  The internal databases can be given the
+** large, default limits.  Databases managed by external sources can
+** be given much smaller limits designed to prevent a denial of service
+** attack.  Developers might also want to use the [sqlite3_set_authorizer()]
+** interface to further control untrusted SQL.  The size of the database
+** created by an untrusted script can be contained using the
+** [max_page_count] [PRAGMA].
+**
+** New run-time limit categories may be added in future releases.
+*/
+SQLITE_API int sqlite3_limit(sqlite3*, int id, int newVal);
+
+/*
+** CAPI3REF: Run-Time Limit Categories
+** KEYWORDS: {limit category} {*limit categories}
+**
+** These constants define various performance limits
+** that can be lowered at run-time using [sqlite3_limit()].
+** The synopsis of the meanings of the various limits is shown below.
+** Additional information is available at [limits | Limits in SQLite].
+**
+** <dl>
+** ^(<dt>SQLITE_LIMIT_LENGTH</dt>
+** <dd>The maximum size of any string or BLOB or table row, in bytes.<dd>)^
+**
+** ^(<dt>SQLITE_LIMIT_SQL_LENGTH</dt>
+** <dd>The maximum length of an SQL statement, in bytes.</dd>)^
+**
+** ^(<dt>SQLITE_LIMIT_COLUMN</dt>
+** <dd>The maximum number of columns in a table definition or in the
+** result set of a [SELECT] or the maximum number of columns in an index
+** or in an ORDER BY or GROUP BY clause.</dd>)^
+**
+** ^(<dt>SQLITE_LIMIT_EXPR_DEPTH</dt>
+** <dd>The maximum depth of the parse tree on any expression.</dd>)^
+**
+** ^(<dt>SQLITE_LIMIT_COMPOUND_SELECT</dt>
+** <dd>The maximum number of terms in a compound SELECT statement.</dd>)^
+**
+** ^(<dt>SQLITE_LIMIT_VDBE_OP</dt>
+** <dd>The maximum number of instructions in a virtual machine program
+** used to implement an SQL statement.  This limit is not currently
+** enforced, though that might be added in some future release of
+** SQLite.</dd>)^
+**
+** ^(<dt>SQLITE_LIMIT_FUNCTION_ARG</dt>
+** <dd>The maximum number of arguments on a function.</dd>)^
+**
+** ^(<dt>SQLITE_LIMIT_ATTACHED</dt>
+** <dd>The maximum number of [ATTACH | attached databases].)^</dd>
+**
+** ^(<dt>SQLITE_LIMIT_LIKE_PATTERN_LENGTH</dt>
+** <dd>The maximum length of the pattern argument to the [LIKE] or
+** [GLOB] operators.</dd>)^
+**
+** ^(<dt>SQLITE_LIMIT_VARIABLE_NUMBER</dt>
+** <dd>The maximum index number of any [parameter] in an SQL statement.)^
+**
+** ^(<dt>SQLITE_LIMIT_TRIGGER_DEPTH</dt>
+** <dd>The maximum depth of recursion for triggers.</dd>)^
+** </dl>
+*/
+#define SQLITE_LIMIT_LENGTH                    0
+#define SQLITE_LIMIT_SQL_LENGTH                1
+#define SQLITE_LIMIT_COLUMN                    2
+#define SQLITE_LIMIT_EXPR_DEPTH                3
+#define SQLITE_LIMIT_COMPOUND_SELECT           4
+#define SQLITE_LIMIT_VDBE_OP                   5
+#define SQLITE_LIMIT_FUNCTION_ARG              6
+#define SQLITE_LIMIT_ATTACHED                  7
+#define SQLITE_LIMIT_LIKE_PATTERN_LENGTH       8
+#define SQLITE_LIMIT_VARIABLE_NUMBER           9
+#define SQLITE_LIMIT_TRIGGER_DEPTH            10
+
+/*
+** CAPI3REF: Compiling An SQL Statement
+** KEYWORDS: {SQL statement compiler}
+**
+** To execute an SQL query, it must first be compiled into a byte-code
+** program using one of these routines.
+**
+** The first argument, "db", is a [database connection] obtained from a
+** prior successful call to [sqlite3_open()], [sqlite3_open_v2()] or
+** [sqlite3_open16()].  The database connection must not have been closed.
+**
+** The second argument, "zSql", is the statement to be compiled, encoded
+** as either UTF-8 or UTF-16.  The sqlite3_prepare() and sqlite3_prepare_v2()
+** interfaces use UTF-8, and sqlite3_prepare16() and sqlite3_prepare16_v2()
+** use UTF-16.
+**
+** ^If the nByte argument is less than zero, then zSql is read up to the
+** first zero terminator. ^If nByte is non-negative, then it is the maximum
+** number of  bytes read from zSql.  ^When nByte is non-negative, the
+** zSql string ends at either the first '\000' or '\u0000' character or
+** the nByte-th byte, whichever comes first. If the caller knows
+** that the supplied string is nul-terminated, then there is a small
+** performance advantage to be gained by passing an nByte parameter that
+** is equal to the number of bytes in the input string <i>including</i>
+** the nul-terminator bytes.
+**
+** ^If pzTail is not NULL then *pzTail is made to point to the first byte
+** past the end of the first SQL statement in zSql.  These routines only
+** compile the first statement in zSql, so *pzTail is left pointing to
+** what remains uncompiled.
+**
+** ^*ppStmt is left pointing to a compiled [prepared statement] that can be
+** executed using [sqlite3_step()].  ^If there is an error, *ppStmt is set
+** to NULL.  ^If the input text contains no SQL (if the input is an empty
+** string or a comment) then *ppStmt is set to NULL.
+** The calling procedure is responsible for deleting the compiled
+** SQL statement using [sqlite3_finalize()] after it has finished with it.
+** ppStmt may not be NULL.
+**
+** ^On success, the sqlite3_prepare() family of routines return [SQLITE_OK];
+** otherwise an [error code] is returned.
+**
+** The sqlite3_prepare_v2() and sqlite3_prepare16_v2() interfaces are
+** recommended for all new programs. The two older interfaces are retained
+** for backwards compatibility, but their use is discouraged.
+** ^In the "v2" interfaces, the prepared statement
+** that is returned (the [sqlite3_stmt] object) contains a copy of the
+** original SQL text. This causes the [sqlite3_step()] interface to
+** behave differently in three ways:
+**
+** <ol>
+** <li>
+** ^If the database schema changes, instead of returning [SQLITE_SCHEMA] as it
+** always used to do, [sqlite3_step()] will automatically recompile the SQL
+** statement and try to run it again.
+** </li>
+**
+** <li>
+** ^When an error occurs, [sqlite3_step()] will return one of the detailed
+** [error codes] or [extended error codes].  ^The legacy behavior was that
+** [sqlite3_step()] would only return a generic [SQLITE_ERROR] result code
+** and the application would have to make a second call to [sqlite3_reset()]
+** in order to find the underlying cause of the problem. With the "v2" prepare
+** interfaces, the underlying reason for the error is returned immediately.
+** </li>
+**
+** <li>
+** ^If the specific value bound to [parameter | host parameter] in the 
+** WHERE clause might influence the choice of query plan for a statement,
+** then the statement will be automatically recompiled, as if there had been 
+** a schema change, on the first  [sqlite3_step()] call following any change
+** to the [sqlite3_bind_text | bindings] of that [parameter]. 
+** ^The specific value of WHERE-clause [parameter] might influence the 
+** choice of query plan if the parameter is the left-hand side of a [LIKE]
+** or [GLOB] operator or if the parameter is compared to an indexed column
+** and the [SQLITE_ENABLE_STAT2] compile-time option is enabled.
+** the 
+** </li>
+** </ol>
+*/
+SQLITE_API int sqlite3_prepare(
+  sqlite3 *db,            /* Database handle */
+  const char *zSql,       /* SQL statement, UTF-8 encoded */
+  int nByte,              /* Maximum length of zSql in bytes. */
+  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
+  const char **pzTail     /* OUT: Pointer to unused portion of zSql */
+);
+SQLITE_API int sqlite3_prepare_v2(
+  sqlite3 *db,            /* Database handle */
+  const char *zSql,       /* SQL statement, UTF-8 encoded */
+  int nByte,              /* Maximum length of zSql in bytes. */
+  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
+  const char **pzTail     /* OUT: Pointer to unused portion of zSql */
+);
+SQLITE_API int sqlite3_prepare16(
+  sqlite3 *db,            /* Database handle */
+  const void *zSql,       /* SQL statement, UTF-16 encoded */
+  int nByte,              /* Maximum length of zSql in bytes. */
+  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
+  const void **pzTail     /* OUT: Pointer to unused portion of zSql */
+);
+SQLITE_API int sqlite3_prepare16_v2(
+  sqlite3 *db,            /* Database handle */
+  const void *zSql,       /* SQL statement, UTF-16 encoded */
+  int nByte,              /* Maximum length of zSql in bytes. */
+  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
+  const void **pzTail     /* OUT: Pointer to unused portion of zSql */
+);
+
+/*
+** CAPI3REF: Retrieving Statement SQL
+**
+** ^This interface can be used to retrieve a saved copy of the original
+** SQL text used to create a [prepared statement] if that statement was
+** compiled using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()].
+*/
+SQLITE_API const char *sqlite3_sql(sqlite3_stmt *pStmt);
+
+/*
+** CAPI3REF: Determine If An SQL Statement Writes The Database
+**
+** ^The sqlite3_stmt_readonly(X) interface returns true (non-zero) if
+** and only if the [prepared statement] X makes no direct changes to
+** the content of the database file.
+**
+** Note that [application-defined SQL functions] or
+** [virtual tables] might change the database indirectly as a side effect.  
+** ^(For example, if an application defines a function "eval()" that 
+** calls [sqlite3_exec()], then the following SQL statement would
+** change the database file through side-effects:
+**
+** <blockquote><pre>
+**    SELECT eval('DELETE FROM t1') FROM t2;
+** </pre></blockquote>
+**
+** But because the [SELECT] statement does not change the database file
+** directly, sqlite3_stmt_readonly() would still return true.)^
+**
+** ^Transaction control statements such as [BEGIN], [COMMIT], [ROLLBACK],
+** [SAVEPOINT], and [RELEASE] cause sqlite3_stmt_readonly() to return true,
+** since the statements themselves do not actually modify the database but
+** rather they control the timing of when other statements modify the 
+** database.  ^The [ATTACH] and [DETACH] statements also cause
+** sqlite3_stmt_readonly() to return true since, while those statements
+** change the configuration of a database connection, they do not make 
+** changes to the content of the database files on disk.
+*/
+SQLITE_API int sqlite3_stmt_readonly(sqlite3_stmt *pStmt);
+
+/*
+** CAPI3REF: Dynamically Typed Value Object
+** KEYWORDS: {protected sqlite3_value} {unprotected sqlite3_value}
+**
+** SQLite uses the sqlite3_value object to represent all values
+** that can be stored in a database table. SQLite uses dynamic typing
+** for the values it stores.  ^Values stored in sqlite3_value objects
+** can be integers, floating point values, strings, BLOBs, or NULL.
+**
+** An sqlite3_value object may be either "protected" or "unprotected".
+** Some interfaces require a protected sqlite3_value.  Other interfaces
+** will accept either a protected or an unprotected sqlite3_value.
+** Every interface that accepts sqlite3_value arguments specifies
+** whether or not it requires a protected sqlite3_value.
+**
+** The terms "protected" and "unprotected" refer to whether or not
+** a mutex is held.  An internal mutex is held for a protected
+** sqlite3_value object but no mutex is held for an unprotected
+** sqlite3_value object.  If SQLite is compiled to be single-threaded
+** (with [SQLITE_THREADSAFE=0] and with [sqlite3_threadsafe()] returning 0)
+** or if SQLite is run in one of reduced mutex modes 
+** [SQLITE_CONFIG_SINGLETHREAD] or [SQLITE_CONFIG_MULTITHREAD]
+** then there is no distinction between protected and unprotected
+** sqlite3_value objects and they can be used interchangeably.  However,
+** for maximum code portability it is recommended that applications
+** still make the distinction between protected and unprotected
+** sqlite3_value objects even when not strictly required.
+**
+** ^The sqlite3_value objects that are passed as parameters into the
+** implementation of [application-defined SQL functions] are protected.
+** ^The sqlite3_value object returned by
+** [sqlite3_column_value()] is unprotected.
+** Unprotected sqlite3_value objects may only be used with
+** [sqlite3_result_value()] and [sqlite3_bind_value()].
+** The [sqlite3_value_blob | sqlite3_value_type()] family of
+** interfaces require protected sqlite3_value objects.
+*/
+typedef struct Mem sqlite3_value;
+
+/*
+** CAPI3REF: SQL Function Context Object
+**
+** The context in which an SQL function executes is stored in an
+** sqlite3_context object.  ^A pointer to an sqlite3_context object
+** is always first parameter to [application-defined SQL functions].
+** The application-defined SQL function implementation will pass this
+** pointer through into calls to [sqlite3_result_int | sqlite3_result()],
+** [sqlite3_aggregate_context()], [sqlite3_user_data()],
+** [sqlite3_context_db_handle()], [sqlite3_get_auxdata()],
+** and/or [sqlite3_set_auxdata()].
+*/
+typedef struct sqlite3_context sqlite3_context;
+
+/*
+** CAPI3REF: Binding Values To Prepared Statements
+** KEYWORDS: {host parameter} {host parameters} {host parameter name}
+** KEYWORDS: {SQL parameter} {SQL parameters} {parameter binding}
+**
+** ^(In the SQL statement text input to [sqlite3_prepare_v2()] and its variants,
+** literals may be replaced by a [parameter] that matches one of following
+** templates:
+**
+** <ul>
+** <li>  ?
+** <li>  ?NNN
+** <li>  :VVV
+** <li>  @VVV
+** <li>  $VVV
+** </ul>
+**
+** In the templates above, NNN represents an integer literal,
+** and VVV represents an alphanumeric identifier.)^  ^The values of these
+** parameters (also called "host parameter names" or "SQL parameters")
+** can be set using the sqlite3_bind_*() routines defined here.
+**
+** ^The first argument to the sqlite3_bind_*() routines is always
+** a pointer to the [sqlite3_stmt] object returned from
+** [sqlite3_prepare_v2()] or its variants.
+**
+** ^The second argument is the index of the SQL parameter to be set.
+** ^The leftmost SQL parameter has an index of 1.  ^When the same named
+** SQL parameter is used more than once, second and subsequent
+** occurrences have the same index as the first occurrence.
+** ^The index for named parameters can be looked up using the
+** [sqlite3_bind_parameter_index()] API if desired.  ^The index
+** for "?NNN" parameters is the value of NNN.
+** ^The NNN value must be between 1 and the [sqlite3_limit()]
+** parameter [SQLITE_LIMIT_VARIABLE_NUMBER] (default value: 999).
+**
+** ^The third argument is the value to bind to the parameter.
+**
+** ^(In those routines that have a fourth argument, its value is the
+** number of bytes in the parameter.  To be clear: the value is the
+** number of <u>bytes</u> in the value, not the number of characters.)^
+** ^If the fourth parameter is negative, the length of the string is
+** the number of bytes up to the first zero terminator.
+**
+** ^The fifth argument to sqlite3_bind_blob(), sqlite3_bind_text(), and
+** sqlite3_bind_text16() is a destructor used to dispose of the BLOB or
+** string after SQLite has finished with it.  ^The destructor is called
+** to dispose of the BLOB or string even if the call to sqlite3_bind_blob(),
+** sqlite3_bind_text(), or sqlite3_bind_text16() fails.  
+** ^If the fifth argument is
+** the special value [SQLITE_STATIC], then SQLite assumes that the
+** information is in static, unmanaged space and does not need to be freed.
+** ^If the fifth argument has the value [SQLITE_TRANSIENT], then
+** SQLite makes its own private copy of the data immediately, before
+** the sqlite3_bind_*() routine returns.
+**
+** ^The sqlite3_bind_zeroblob() routine binds a BLOB of length N that
+** is filled with zeroes.  ^A zeroblob uses a fixed amount of memory
+** (just an integer to hold its size) while it is being processed.
+** Zeroblobs are intended to serve as placeholders for BLOBs whose
+** content is later written using
+** [sqlite3_blob_open | incremental BLOB I/O] routines.
+** ^A negative value for the zeroblob results in a zero-length BLOB.
+**
+** ^If any of the sqlite3_bind_*() routines are called with a NULL pointer
+** for the [prepared statement] or with a prepared statement for which
+** [sqlite3_step()] has been called more recently than [sqlite3_reset()],
+** then the call will return [SQLITE_MISUSE].  If any sqlite3_bind_()
+** routine is passed a [prepared statement] that has been finalized, the
+** result is undefined and probably harmful.
+**
+** ^Bindings are not cleared by the [sqlite3_reset()] routine.
+** ^Unbound parameters are interpreted as NULL.
+**
+** ^The sqlite3_bind_* routines return [SQLITE_OK] on success or an
+** [error code] if anything goes wrong.
+** ^[SQLITE_RANGE] is returned if the parameter
+** index is out of range.  ^[SQLITE_NOMEM] is returned if malloc() fails.
+**
+** See also: [sqlite3_bind_parameter_count()],
+** [sqlite3_bind_parameter_name()], and [sqlite3_bind_parameter_index()].
+*/
+SQLITE_API int sqlite3_bind_blob(sqlite3_stmt*, int, const void*, int n, void(*)(void*));
+SQLITE_API int sqlite3_bind_double(sqlite3_stmt*, int, double);
+SQLITE_API int sqlite3_bind_int(sqlite3_stmt*, int, int);
+SQLITE_API int sqlite3_bind_int64(sqlite3_stmt*, int, sqlite3_int64);
+SQLITE_API int sqlite3_bind_null(sqlite3_stmt*, int);
+SQLITE_API int sqlite3_bind_text(sqlite3_stmt*, int, const char*, int n, void(*)(void*));
+SQLITE_API int sqlite3_bind_text16(sqlite3_stmt*, int, const void*, int, void(*)(void*));
+SQLITE_API int sqlite3_bind_value(sqlite3_stmt*, int, const sqlite3_value*);
+SQLITE_API int sqlite3_bind_zeroblob(sqlite3_stmt*, int, int n);
+
+/*
+** CAPI3REF: Number Of SQL Parameters
+**
+** ^This routine can be used to find the number of [SQL parameters]
+** in a [prepared statement].  SQL parameters are tokens of the
+** form "?", "?NNN", ":AAA", "$AAA", or "@AAA" that serve as
+** placeholders for values that are [sqlite3_bind_blob | bound]
+** to the parameters at a later time.
+**
+** ^(This routine actually returns the index of the largest (rightmost)
+** parameter. For all forms except ?NNN, this will correspond to the
+** number of unique parameters.  If parameters of the ?NNN form are used,
+** there may be gaps in the list.)^
+**
+** See also: [sqlite3_bind_blob|sqlite3_bind()],
+** [sqlite3_bind_parameter_name()], and
+** [sqlite3_bind_parameter_index()].
+*/
+SQLITE_API int sqlite3_bind_parameter_count(sqlite3_stmt*);
+
+/*
+** CAPI3REF: Name Of A Host Parameter
+**
+** ^The sqlite3_bind_parameter_name(P,N) interface returns
+** the name of the N-th [SQL parameter] in the [prepared statement] P.
+** ^(SQL parameters of the form "?NNN" or ":AAA" or "@AAA" or "$AAA"
+** have a name which is the string "?NNN" or ":AAA" or "@AAA" or "$AAA"
+** respectively.
+** In other words, the initial ":" or "$" or "@" or "?"
+** is included as part of the name.)^
+** ^Parameters of the form "?" without a following integer have no name
+** and are referred to as "nameless" or "anonymous parameters".
+**
+** ^The first host parameter has an index of 1, not 0.
+**
+** ^If the value N is out of range or if the N-th parameter is
+** nameless, then NULL is returned.  ^The returned string is
+** always in UTF-8 encoding even if the named parameter was
+** originally specified as UTF-16 in [sqlite3_prepare16()] or
+** [sqlite3_prepare16_v2()].
+**
+** See also: [sqlite3_bind_blob|sqlite3_bind()],
+** [sqlite3_bind_parameter_count()], and
+** [sqlite3_bind_parameter_index()].
+*/
+SQLITE_API const char *sqlite3_bind_parameter_name(sqlite3_stmt*, int);
+
+/*
+** CAPI3REF: Index Of A Parameter With A Given Name
+**
+** ^Return the index of an SQL parameter given its name.  ^The
+** index value returned is suitable for use as the second
+** parameter to [sqlite3_bind_blob|sqlite3_bind()].  ^A zero
+** is returned if no matching parameter is found.  ^The parameter
+** name must be given in UTF-8 even if the original statement
+** was prepared from UTF-16 text using [sqlite3_prepare16_v2()].
+**
+** See also: [sqlite3_bind_blob|sqlite3_bind()],
+** [sqlite3_bind_parameter_count()], and
+** [sqlite3_bind_parameter_index()].
+*/
+SQLITE_API int sqlite3_bind_parameter_index(sqlite3_stmt*, const char *zName);
+
+/*
+** CAPI3REF: Reset All Bindings On A Prepared Statement
+**
+** ^Contrary to the intuition of many, [sqlite3_reset()] does not reset
+** the [sqlite3_bind_blob | bindings] on a [prepared statement].
+** ^Use this routine to reset all host parameters to NULL.
+*/
+SQLITE_API int sqlite3_clear_bindings(sqlite3_stmt*);
+
+/*
+** CAPI3REF: Number Of Columns In A Result Set
+**
+** ^Return the number of columns in the result set returned by the
+** [prepared statement]. ^This routine returns 0 if pStmt is an SQL
+** statement that does not return data (for example an [UPDATE]).
+**
+** See also: [sqlite3_data_count()]
+*/
+SQLITE_API int sqlite3_column_count(sqlite3_stmt *pStmt);
+
+/*
+** CAPI3REF: Column Names In A Result Set
+**
+** ^These routines return the name assigned to a particular column
+** in the result set of a [SELECT] statement.  ^The sqlite3_column_name()
+** interface returns a pointer to a zero-terminated UTF-8 string
+** and sqlite3_column_name16() returns a pointer to a zero-terminated
+** UTF-16 string.  ^The first parameter is the [prepared statement]
+** that implements the [SELECT] statement. ^The second parameter is the
+** column number.  ^The leftmost column is number 0.
+**
+** ^The returned string pointer is valid until either the [prepared statement]
+** is destroyed by [sqlite3_finalize()] or until the statement is automatically
+** reprepared by the first call to [sqlite3_step()] for a particular run
+** or until the next call to
+** sqlite3_column_name() or sqlite3_column_name16() on the same column.
+**
+** ^If sqlite3_malloc() fails during the processing of either routine
+** (for example during a conversion from UTF-8 to UTF-16) then a
+** NULL pointer is returned.
+**
+** ^The name of a result column is the value of the "AS" clause for
+** that column, if there is an AS clause.  If there is no AS clause
+** then the name of the column is unspecified and may change from
+** one release of SQLite to the next.
+*/
+SQLITE_API const char *sqlite3_column_name(sqlite3_stmt*, int N);
+SQLITE_API const void *sqlite3_column_name16(sqlite3_stmt*, int N);
+
+/*
+** CAPI3REF: Source Of Data In A Query Result
+**
+** ^These routines provide a means to determine the database, table, and
+** table column that is the origin of a particular result column in
+** [SELECT] statement.
+** ^The name of the database or table or column can be returned as
+** either a UTF-8 or UTF-16 string.  ^The _database_ routines return
+** the database name, the _table_ routines return the table name, and
+** the origin_ routines return the column name.
+** ^The returned string is valid until the [prepared statement] is destroyed
+** using [sqlite3_finalize()] or until the statement is automatically
+** reprepared by the first call to [sqlite3_step()] for a particular run
+** or until the same information is requested
+** again in a different encoding.
+**
+** ^The names returned are the original un-aliased names of the
+** database, table, and column.
+**
+** ^The first argument to these interfaces is a [prepared statement].
+** ^These functions return information about the Nth result column returned by
+** the statement, where N is the second function argument.
+** ^The left-most column is column 0 for these routines.
+**
+** ^If the Nth column returned by the statement is an expression or
+** subquery and is not a column value, then all of these functions return
+** NULL.  ^These routine might also return NULL if a memory allocation error
+** occurs.  ^Otherwise, they return the name of the attached database, table,
+** or column that query result column was extracted from.
+**
+** ^As with all other SQLite APIs, those whose names end with "16" return
+** UTF-16 encoded strings and the other functions return UTF-8.
+**
+** ^These APIs are only available if the library was compiled with the
+** [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol.
+**
+** If two or more threads call one or more of these routines against the same
+** prepared statement and column at the same time then the results are
+** undefined.
+**
+** If two or more threads call one or more
+** [sqlite3_column_database_name | column metadata interfaces]
+** for the same [prepared statement] and result column
+** at the same time then the results are undefined.
+*/
+SQLITE_API const char *sqlite3_column_database_name(sqlite3_stmt*,int);
+SQLITE_API const void *sqlite3_column_database_name16(sqlite3_stmt*,int);
+SQLITE_API const char *sqlite3_column_table_name(sqlite3_stmt*,int);
+SQLITE_API const void *sqlite3_column_table_name16(sqlite3_stmt*,int);
+SQLITE_API const char *sqlite3_column_origin_name(sqlite3_stmt*,int);
+SQLITE_API const void *sqlite3_column_origin_name16(sqlite3_stmt*,int);
+
+/*
+** CAPI3REF: Declared Datatype Of A Query Result
+**
+** ^(The first parameter is a [prepared statement].
+** If this statement is a [SELECT] statement and the Nth column of the
+** returned result set of that [SELECT] is a table column (not an
+** expression or subquery) then the declared type of the table
+** column is returned.)^  ^If the Nth column of the result set is an
+** expression or subquery, then a NULL pointer is returned.
+** ^The returned string is always UTF-8 encoded.
+**
+** ^(For example, given the database schema:
+**
+** CREATE TABLE t1(c1 VARIANT);
+**
+** and the following statement to be compiled:
+**
+** SELECT c1 + 1, c1 FROM t1;
+**
+** this routine would return the string "VARIANT" for the second result
+** column (i==1), and a NULL pointer for the first result column (i==0).)^
+**
+** ^SQLite uses dynamic run-time typing.  ^So just because a column
+** is declared to contain a particular type does not mean that the
+** data stored in that column is of the declared type.  SQLite is
+** strongly typed, but the typing is dynamic not static.  ^Type
+** is associated with individual values, not with the containers
+** used to hold those values.
+*/
+SQLITE_API const char *sqlite3_column_decltype(sqlite3_stmt*,int);
+SQLITE_API const void *sqlite3_column_decltype16(sqlite3_stmt*,int);
+
+/*
+** CAPI3REF: Evaluate An SQL Statement
+**
+** After a [prepared statement] has been prepared using either
+** [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] or one of the legacy
+** interfaces [sqlite3_prepare()] or [sqlite3_prepare16()], this function
+** must be called one or more times to evaluate the statement.
+**
+** The details of the behavior of the sqlite3_step() interface depend
+** on whether the statement was prepared using the newer "v2" interface
+** [sqlite3_prepare_v2()] and [sqlite3_prepare16_v2()] or the older legacy
+** interface [sqlite3_prepare()] and [sqlite3_prepare16()].  The use of the
+** new "v2" interface is recommended for new applications but the legacy
+** interface will continue to be supported.
+**
+** ^In the legacy interface, the return value will be either [SQLITE_BUSY],
+** [SQLITE_DONE], [SQLITE_ROW], [SQLITE_ERROR], or [SQLITE_MISUSE].
+** ^With the "v2" interface, any of the other [result codes] or
+** [extended result codes] might be returned as well.
+**
+** ^[SQLITE_BUSY] means that the database engine was unable to acquire the
+** database locks it needs to do its job.  ^If the statement is a [COMMIT]
+** or occurs outside of an explicit transaction, then you can retry the
+** statement.  If the statement is not a [COMMIT] and occurs within a
+** explicit transaction then you should rollback the transaction before
+** continuing.
+**
+** ^[SQLITE_DONE] means that the statement has finished executing
+** successfully.  sqlite3_step() should not be called again on this virtual
+** machine without first calling [sqlite3_reset()] to reset the virtual
+** machine back to its initial state.
+**
+** ^If the SQL statement being executed returns any data, then [SQLITE_ROW]
+** is returned each time a new row of data is ready for processing by the
+** caller. The values may be accessed using the [column access functions].
+** sqlite3_step() is called again to retrieve the next row of data.
+**
+** ^[SQLITE_ERROR] means that a run-time error (such as a constraint
+** violation) has occurred.  sqlite3_step() should not be called again on
+** the VM. More information may be found by calling [sqlite3_errmsg()].
+** ^With the legacy interface, a more specific error code (for example,
+** [SQLITE_INTERRUPT], [SQLITE_SCHEMA], [SQLITE_CORRUPT], and so forth)
+** can be obtained by calling [sqlite3_reset()] on the
+** [prepared statement].  ^In the "v2" interface,
+** the more specific error code is returned directly by sqlite3_step().
+**
+** [SQLITE_MISUSE] means that the this routine was called inappropriately.
+** Perhaps it was called on a [prepared statement] that has
+** already been [sqlite3_finalize | finalized] or on one that had
+** previously returned [SQLITE_ERROR] or [SQLITE_DONE].  Or it could
+** be the case that the same database connection is being used by two or
+** more threads at the same moment in time.
+**
+** For all versions of SQLite up to and including 3.6.23.1, a call to
+** [sqlite3_reset()] was required after sqlite3_step() returned anything
+** other than [SQLITE_ROW] before any subsequent invocation of
+** sqlite3_step().  Failure to reset the prepared statement using 
+** [sqlite3_reset()] would result in an [SQLITE_MISUSE] return from
+** sqlite3_step().  But after version 3.6.23.1, sqlite3_step() began
+** calling [sqlite3_reset()] automatically in this circumstance rather
+** than returning [SQLITE_MISUSE].  This is not considered a compatibility
+** break because any application that ever receives an SQLITE_MISUSE error
+** is broken by definition.  The [SQLITE_OMIT_AUTORESET] compile-time option
+** can be used to restore the legacy behavior.
+**
+** <b>Goofy Interface Alert:</b> In the legacy interface, the sqlite3_step()
+** API always returns a generic error code, [SQLITE_ERROR], following any
+** error other than [SQLITE_BUSY] and [SQLITE_MISUSE].  You must call
+** [sqlite3_reset()] or [sqlite3_finalize()] in order to find one of the
+** specific [error codes] that better describes the error.
+** We admit that this is a goofy design.  The problem has been fixed
+** with the "v2" interface.  If you prepare all of your SQL statements
+** using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] instead
+** of the legacy [sqlite3_prepare()] and [sqlite3_prepare16()] interfaces,
+** then the more specific [error codes] are returned directly
+** by sqlite3_step().  The use of the "v2" interface is recommended.
+*/
+SQLITE_API int sqlite3_step(sqlite3_stmt*);
+
+/*
+** CAPI3REF: Number of columns in a result set
+**
+** ^The sqlite3_data_count(P) interface returns the number of columns in the
+** current row of the result set of [prepared statement] P.
+** ^If prepared statement P does not have results ready to return
+** (via calls to the [sqlite3_column_int | sqlite3_column_*()] of
+** interfaces) then sqlite3_data_count(P) returns 0.
+** ^The sqlite3_data_count(P) routine also returns 0 if P is a NULL pointer.
+**
+** See also: [sqlite3_column_count()]
+*/
+SQLITE_API int sqlite3_data_count(sqlite3_stmt *pStmt);
+
+/*
+** CAPI3REF: Fundamental Datatypes
+** KEYWORDS: SQLITE_TEXT
+**
+** ^(Every value in SQLite has one of five fundamental datatypes:
+**
+** <ul>
+** <li> 64-bit signed integer
+** <li> 64-bit IEEE floating point number
+** <li> string
+** <li> BLOB
+** <li> NULL
+** </ul>)^
+**
+** These constants are codes for each of those types.
+**
+** Note that the SQLITE_TEXT constant was also used in SQLite version 2
+** for a completely different meaning.  Software that links against both
+** SQLite version 2 and SQLite version 3 should use SQLITE3_TEXT, not
+** SQLITE_TEXT.
+*/
+#define SQLITE_INTEGER  1
+#define SQLITE_FLOAT    2
+#define SQLITE_BLOB     4
+#define SQLITE_NULL     5
+#ifdef SQLITE_TEXT
+# undef SQLITE_TEXT
+#else
+# define SQLITE_TEXT     3
+#endif
+#define SQLITE3_TEXT     3
+
+/*
+** CAPI3REF: Result Values From A Query
+** KEYWORDS: {column access functions}
+**
+** These routines form the "result set" interface.
+**
+** ^These routines return information about a single column of the current
+** result row of a query.  ^In every case the first argument is a pointer
+** to the [prepared statement] that is being evaluated (the [sqlite3_stmt*]
+** that was returned from [sqlite3_prepare_v2()] or one of its variants)
+** and the second argument is the index of the column for which information
+** should be returned. ^The leftmost column of the result set has the index 0.
+** ^The number of columns in the result can be determined using
+** [sqlite3_column_count()].
+**
+** If the SQL statement does not currently point to a valid row, or if the
+** column index is out of range, the result is undefined.
+** These routines may only be called when the most recent call to
+** [sqlite3_step()] has returned [SQLITE_ROW] and neither
+** [sqlite3_reset()] nor [sqlite3_finalize()] have been called subsequently.
+** If any of these routines are called after [sqlite3_reset()] or
+** [sqlite3_finalize()] or after [sqlite3_step()] has returned
+** something other than [SQLITE_ROW], the results are undefined.
+** If [sqlite3_step()] or [sqlite3_reset()] or [sqlite3_finalize()]
+** are called from a different thread while any of these routines
+** are pending, then the results are undefined.
+**
+** ^The sqlite3_column_type() routine returns the
+** [SQLITE_INTEGER | datatype code] for the initial data type
+** of the result column.  ^The returned value is one of [SQLITE_INTEGER],
+** [SQLITE_FLOAT], [SQLITE_TEXT], [SQLITE_BLOB], or [SQLITE_NULL].  The value
+** returned by sqlite3_column_type() is only meaningful if no type
+** conversions have occurred as described below.  After a type conversion,
+** the value returned by sqlite3_column_type() is undefined.  Future
+** versions of SQLite may change the behavior of sqlite3_column_type()
+** following a type conversion.
+**
+** ^If the result is a BLOB or UTF-8 string then the sqlite3_column_bytes()
+** routine returns the number of bytes in that BLOB or string.
+** ^If the result is a UTF-16 string, then sqlite3_column_bytes() converts
+** the string to UTF-8 and then returns the number of bytes.
+** ^If the result is a numeric value then sqlite3_column_bytes() uses
+** [sqlite3_snprintf()] to convert that value to a UTF-8 string and returns
+** the number of bytes in that string.
+** ^If the result is NULL, then sqlite3_column_bytes() returns zero.
+**
+** ^If the result is a BLOB or UTF-16 string then the sqlite3_column_bytes16()
+** routine returns the number of bytes in that BLOB or string.
+** ^If the result is a UTF-8 string, then sqlite3_column_bytes16() converts
+** the string to UTF-16 and then returns the number of bytes.
+** ^If the result is a numeric value then sqlite3_column_bytes16() uses
+** [sqlite3_snprintf()] to convert that value to a UTF-16 string and returns
+** the number of bytes in that string.
+** ^If the result is NULL, then sqlite3_column_bytes16() returns zero.
+**
+** ^The values returned by [sqlite3_column_bytes()] and 
+** [sqlite3_column_bytes16()] do not include the zero terminators at the end
+** of the string.  ^For clarity: the values returned by
+** [sqlite3_column_bytes()] and [sqlite3_column_bytes16()] are the number of
+** bytes in the string, not the number of characters.
+**
+** ^Strings returned by sqlite3_column_text() and sqlite3_column_text16(),
+** even empty strings, are always zero terminated.  ^The return
+** value from sqlite3_column_blob() for a zero-length BLOB is a NULL pointer.
+**
+** ^The object returned by [sqlite3_column_value()] is an
+** [unprotected sqlite3_value] object.  An unprotected sqlite3_value object
+** may only be used with [sqlite3_bind_value()] and [sqlite3_result_value()].
+** If the [unprotected sqlite3_value] object returned by
+** [sqlite3_column_value()] is used in any other way, including calls
+** to routines like [sqlite3_value_int()], [sqlite3_value_text()],
+** or [sqlite3_value_bytes()], then the behavior is undefined.
+**
+** These routines attempt to convert the value where appropriate.  ^For
+** example, if the internal representation is FLOAT and a text result
+** is requested, [sqlite3_snprintf()] is used internally to perform the
+** conversion automatically.  ^(The following table details the conversions
+** that are applied:
+**
+** <blockquote>
+** <table border="1">
+** <tr><th> Internal<br>Type <th> Requested<br>Type <th>  Conversion
+**
+** <tr><td>  NULL    <td> INTEGER   <td> Result is 0
+** <tr><td>  NULL    <td>  FLOAT    <td> Result is 0.0
+** <tr><td>  NULL    <td>   TEXT    <td> Result is NULL pointer
+** <tr><td>  NULL    <td>   BLOB    <td> Result is NULL pointer
+** <tr><td> INTEGER  <td>  FLOAT    <td> Convert from integer to float
+** <tr><td> INTEGER  <td>   TEXT    <td> ASCII rendering of the integer
+** <tr><td> INTEGER  <td>   BLOB    <td> Same as INTEGER->TEXT
+** <tr><td>  FLOAT   <td> INTEGER   <td> Convert from float to integer
+** <tr><td>  FLOAT   <td>   TEXT    <td> ASCII rendering of the float
+** <tr><td>  FLOAT   <td>   BLOB    <td> Same as FLOAT->TEXT
+** <tr><td>  TEXT    <td> INTEGER   <td> Use atoi()
+** <tr><td>  TEXT    <td>  FLOAT    <td> Use atof()
+** <tr><td>  TEXT    <td>   BLOB    <td> No change
+** <tr><td>  BLOB    <td> INTEGER   <td> Convert to TEXT then use atoi()
+** <tr><td>  BLOB    <td>  FLOAT    <td> Convert to TEXT then use atof()
+** <tr><td>  BLOB    <td>   TEXT    <td> Add a zero terminator if needed
+** </table>
+** </blockquote>)^
+**
+** The table above makes reference to standard C library functions atoi()
+** and atof().  SQLite does not really use these functions.  It has its
+** own equivalent internal routines.  The atoi() and atof() names are
+** used in the table for brevity and because they are familiar to most
+** C programmers.
+**
+** Note that when type conversions occur, pointers returned by prior
+** calls to sqlite3_column_blob(), sqlite3_column_text(), and/or
+** sqlite3_column_text16() may be invalidated.
+** Type conversions and pointer invalidations might occur
+** in the following cases:
+**
+** <ul>
+** <li> The initial content is a BLOB and sqlite3_column_text() or
+**      sqlite3_column_text16() is called.  A zero-terminator might
+**      need to be added to the string.</li>
+** <li> The initial content is UTF-8 text and sqlite3_column_bytes16() or
+**      sqlite3_column_text16() is called.  The content must be converted
+**      to UTF-16.</li>
+** <li> The initial content is UTF-16 text and sqlite3_column_bytes() or
+**      sqlite3_column_text() is called.  The content must be converted
+**      to UTF-8.</li>
+** </ul>
+**
+** ^Conversions between UTF-16be and UTF-16le are always done in place and do
+** not invalidate a prior pointer, though of course the content of the buffer
+** that the prior pointer references will have been modified.  Other kinds
+** of conversion are done in place when it is possible, but sometimes they
+** are not possible and in those cases prior pointers are invalidated.
+**
+** The safest and easiest to remember policy is to invoke these routines
+** in one of the following ways:
+**
+** <ul>
+**  <li>sqlite3_column_text() followed by sqlite3_column_bytes()</li>
+**  <li>sqlite3_column_blob() followed by sqlite3_column_bytes()</li>
+**  <li>sqlite3_column_text16() followed by sqlite3_column_bytes16()</li>
+** </ul>
+**
+** In other words, you should call sqlite3_column_text(),
+** sqlite3_column_blob(), or sqlite3_column_text16() first to force the result
+** into the desired format, then invoke sqlite3_column_bytes() or
+** sqlite3_column_bytes16() to find the size of the result.  Do not mix calls
+** to sqlite3_column_text() or sqlite3_column_blob() with calls to
+** sqlite3_column_bytes16(), and do not mix calls to sqlite3_column_text16()
+** with calls to sqlite3_column_bytes().
+**
+** ^The pointers returned are valid until a type conversion occurs as
+** described above, or until [sqlite3_step()] or [sqlite3_reset()] or
+** [sqlite3_finalize()] is called.  ^The memory space used to hold strings
+** and BLOBs is freed automatically.  Do <b>not</b> pass the pointers returned
+** [sqlite3_column_blob()], [sqlite3_column_text()], etc. into
+** [sqlite3_free()].
+**
+** ^(If a memory allocation error occurs during the evaluation of any
+** of these routines, a default value is returned.  The default value
+** is either the integer 0, the floating point number 0.0, or a NULL
+** pointer.  Subsequent calls to [sqlite3_errcode()] will return
+** [SQLITE_NOMEM].)^
+*/
+SQLITE_API const void *sqlite3_column_blob(sqlite3_stmt*, int iCol);
+SQLITE_API int sqlite3_column_bytes(sqlite3_stmt*, int iCol);
+SQLITE_API int sqlite3_column_bytes16(sqlite3_stmt*, int iCol);
+SQLITE_API double sqlite3_column_double(sqlite3_stmt*, int iCol);
+SQLITE_API int sqlite3_column_int(sqlite3_stmt*, int iCol);
+SQLITE_API sqlite3_int64 sqlite3_column_int64(sqlite3_stmt*, int iCol);
+SQLITE_API const unsigned char *sqlite3_column_text(sqlite3_stmt*, int iCol);
+SQLITE_API const void *sqlite3_column_text16(sqlite3_stmt*, int iCol);
+SQLITE_API int sqlite3_column_type(sqlite3_stmt*, int iCol);
+SQLITE_API sqlite3_value *sqlite3_column_value(sqlite3_stmt*, int iCol);
+
+/*
+** CAPI3REF: Destroy A Prepared Statement Object
+**
+** ^The sqlite3_finalize() function is called to delete a [prepared statement].
+** ^If the most recent evaluation of the statement encountered no errors or
+** or if the statement is never been evaluated, then sqlite3_finalize() returns
+** SQLITE_OK.  ^If the most recent evaluation of statement S failed, then
+** sqlite3_finalize(S) returns the appropriate [error code] or
+** [extended error code].
+**
+** ^The sqlite3_finalize(S) routine can be called at any point during
+** the life cycle of [prepared statement] S:
+** before statement S is ever evaluated, after
+** one or more calls to [sqlite3_reset()], or after any call
+** to [sqlite3_step()] regardless of whether or not the statement has
+** completed execution.
+**
+** ^Invoking sqlite3_finalize() on a NULL pointer is a harmless no-op.
+**
+** The application must finalize every [prepared statement] in order to avoid
+** resource leaks.  It is a grievous error for the application to try to use
+** a prepared statement after it has been finalized.  Any use of a prepared
+** statement after it has been finalized can result in undefined and
+** undesirable behavior such as segfaults and heap corruption.
+*/
+SQLITE_API int sqlite3_finalize(sqlite3_stmt *pStmt);
+
+/*
+** CAPI3REF: Reset A Prepared Statement Object
+**
+** The sqlite3_reset() function is called to reset a [prepared statement]
+** object back to its initial state, ready to be re-executed.
+** ^Any SQL statement variables that had values bound to them using
+** the [sqlite3_bind_blob | sqlite3_bind_*() API] retain their values.
+** Use [sqlite3_clear_bindings()] to reset the bindings.
+**
+** ^The [sqlite3_reset(S)] interface resets the [prepared statement] S
+** back to the beginning of its program.
+**
+** ^If the most recent call to [sqlite3_step(S)] for the
+** [prepared statement] S returned [SQLITE_ROW] or [SQLITE_DONE],
+** or if [sqlite3_step(S)] has never before been called on S,
+** then [sqlite3_reset(S)] returns [SQLITE_OK].
+**
+** ^If the most recent call to [sqlite3_step(S)] for the
+** [prepared statement] S indicated an error, then
+** [sqlite3_reset(S)] returns an appropriate [error code].
+**
+** ^The [sqlite3_reset(S)] interface does not change the values
+** of any [sqlite3_bind_blob|bindings] on the [prepared statement] S.
+*/
+SQLITE_API int sqlite3_reset(sqlite3_stmt *pStmt);
+
+/*
+** CAPI3REF: Create Or Redefine SQL Functions
+** KEYWORDS: {function creation routines}
+** KEYWORDS: {application-defined SQL function}
+** KEYWORDS: {application-defined SQL functions}
+**
+** ^These functions (collectively known as "function creation routines")
+** are used to add SQL functions or aggregates or to redefine the behavior
+** of existing SQL functions or aggregates.  The only differences between
+** these routines are the text encoding expected for
+** the second parameter (the name of the function being created)
+** and the presence or absence of a destructor callback for
+** the application data pointer.
+**
+** ^The first parameter is the [database connection] to which the SQL
+** function is to be added.  ^If an application uses more than one database
+** connection then application-defined SQL functions must be added
+** to each database connection separately.
+**
+** ^The second parameter is the name of the SQL function to be created or
+** redefined.  ^The length of the name is limited to 255 bytes in a UTF-8
+** representation, exclusive of the zero-terminator.  ^Note that the name
+** length limit is in UTF-8 bytes, not characters nor UTF-16 bytes.  
+** ^Any attempt to create a function with a longer name
+** will result in [SQLITE_MISUSE] being returned.
+**
+** ^The third parameter (nArg)
+** is the number of arguments that the SQL function or
+** aggregate takes. ^If this parameter is -1, then the SQL function or
+** aggregate may take any number of arguments between 0 and the limit
+** set by [sqlite3_limit]([SQLITE_LIMIT_FUNCTION_ARG]).  If the third
+** parameter is less than -1 or greater than 127 then the behavior is
+** undefined.
+**
+** ^The fourth parameter, eTextRep, specifies what
+** [SQLITE_UTF8 | text encoding] this SQL function prefers for
+** its parameters.  Every SQL function implementation must be able to work
+** with UTF-8, UTF-16le, or UTF-16be.  But some implementations may be
+** more efficient with one encoding than another.  ^An application may
+** invoke sqlite3_create_function() or sqlite3_create_function16() multiple
+** times with the same function but with different values of eTextRep.
+** ^When multiple implementations of the same function are available, SQLite
+** will pick the one that involves the least amount of data conversion.
+** If there is only a single implementation which does not care what text
+** encoding is used, then the fourth argument should be [SQLITE_ANY].
+**
+** ^(The fifth parameter is an arbitrary pointer.  The implementation of the
+** function can gain access to this pointer using [sqlite3_user_data()].)^
+**
+** ^The sixth, seventh and eighth parameters, xFunc, xStep and xFinal, are
+** pointers to C-language functions that implement the SQL function or
+** aggregate. ^A scalar SQL function requires an implementation of the xFunc
+** callback only; NULL pointers must be passed as the xStep and xFinal
+** parameters. ^An aggregate SQL function requires an implementation of xStep
+** and xFinal and NULL pointer must be passed for xFunc. ^To delete an existing
+** SQL function or aggregate, pass NULL pointers for all three function
+** callbacks.
+**
+** ^(If the ninth parameter to sqlite3_create_function_v2() is not NULL,
+** then it is destructor for the application data pointer. 
+** The destructor is invoked when the function is deleted, either by being
+** overloaded or when the database connection closes.)^
+** ^The destructor is also invoked if the call to
+** sqlite3_create_function_v2() fails.
+** ^When the destructor callback of the tenth parameter is invoked, it
+** is passed a single argument which is a copy of the application data 
+** pointer which was the fifth parameter to sqlite3_create_function_v2().
+**
+** ^It is permitted to register multiple implementations of the same
+** functions with the same name but with either differing numbers of
+** arguments or differing preferred text encodings.  ^SQLite will use
+** the implementation that most closely matches the way in which the
+** SQL function is used.  ^A function implementation with a non-negative
+** nArg parameter is a better match than a function implementation with
+** a negative nArg.  ^A function where the preferred text encoding
+** matches the database encoding is a better
+** match than a function where the encoding is different.  
+** ^A function where the encoding difference is between UTF16le and UTF16be
+** is a closer match than a function where the encoding difference is
+** between UTF8 and UTF16.
+**
+** ^Built-in functions may be overloaded by new application-defined functions.
+**
+** ^An application-defined function is permitted to call other
+** SQLite interfaces.  However, such calls must not
+** close the database connection nor finalize or reset the prepared
+** statement in which the function is running.
+*/
+SQLITE_API int sqlite3_create_function(
+  sqlite3 *db,
+  const char *zFunctionName,
+  int nArg,
+  int eTextRep,
+  void *pApp,
+  void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
+  void (*xStep)(sqlite3_context*,int,sqlite3_value**),
+  void (*xFinal)(sqlite3_context*)
+);
+SQLITE_API int sqlite3_create_function16(
+  sqlite3 *db,
+  const void *zFunctionName,
+  int nArg,
+  int eTextRep,
+  void *pApp,
+  void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
+  void (*xStep)(sqlite3_context*,int,sqlite3_value**),
+  void (*xFinal)(sqlite3_context*)
+);
+SQLITE_API int sqlite3_create_function_v2(
+  sqlite3 *db,
+  const char *zFunctionName,
+  int nArg,
+  int eTextRep,
+  void *pApp,
+  void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
+  void (*xStep)(sqlite3_context*,int,sqlite3_value**),
+  void (*xFinal)(sqlite3_context*),
+  void(*xDestroy)(void*)
+);
+
+/*
+** CAPI3REF: Text Encodings
+**
+** These constant define integer codes that represent the various
+** text encodings supported by SQLite.
+*/
+#define SQLITE_UTF8           1
+#define SQLITE_UTF16LE        2
+#define SQLITE_UTF16BE        3
+#define SQLITE_UTF16          4    /* Use native byte order */
+#define SQLITE_ANY            5    /* sqlite3_create_function only */
+#define SQLITE_UTF16_ALIGNED  8    /* sqlite3_create_collation only */
+
+/*
+** CAPI3REF: Deprecated Functions
+** DEPRECATED
+**
+** These functions are [deprecated].  In order to maintain
+** backwards compatibility with older code, these functions continue 
+** to be supported.  However, new applications should avoid
+** the use of these functions.  To help encourage people to avoid
+** using these functions, we are not going to tell you what they do.
+*/
+#ifndef SQLITE_OMIT_DEPRECATED
+SQLITE_API SQLITE_DEPRECATED int sqlite3_aggregate_count(sqlite3_context*);
+SQLITE_API SQLITE_DEPRECATED int sqlite3_expired(sqlite3_stmt*);
+SQLITE_API SQLITE_DEPRECATED int sqlite3_transfer_bindings(sqlite3_stmt*, sqlite3_stmt*);
+SQLITE_API SQLITE_DEPRECATED int sqlite3_global_recover(void);
+SQLITE_API SQLITE_DEPRECATED void sqlite3_thread_cleanup(void);
+SQLITE_API SQLITE_DEPRECATED int sqlite3_memory_alarm(void(*)(void*,sqlite3_int64,int),void*,sqlite3_int64);
+#endif
+
+/*
+** CAPI3REF: Obtaining SQL Function Parameter Values
+**
+** The C-language implementation of SQL functions and aggregates uses
+** this set of interface routines to access the parameter values on
+** the function or aggregate.
+**
+** The xFunc (for scalar functions) or xStep (for aggregates) parameters
+** to [sqlite3_create_function()] and [sqlite3_create_function16()]
+** define callbacks that implement the SQL functions and aggregates.
+** The 3rd parameter to these callbacks is an array of pointers to
+** [protected sqlite3_value] objects.  There is one [sqlite3_value] object for
+** each parameter to the SQL function.  These routines are used to
+** extract values from the [sqlite3_value] objects.
+**
+** These routines work only with [protected sqlite3_value] objects.
+** Any attempt to use these routines on an [unprotected sqlite3_value]
+** object results in undefined behavior.
+**
+** ^These routines work just like the corresponding [column access functions]
+** except that  these routines take a single [protected sqlite3_value] object
+** pointer instead of a [sqlite3_stmt*] pointer and an integer column number.
+**
+** ^The sqlite3_value_text16() interface extracts a UTF-16 string
+** in the native byte-order of the host machine.  ^The
+** sqlite3_value_text16be() and sqlite3_value_text16le() interfaces
+** extract UTF-16 strings as big-endian and little-endian respectively.
+**
+** ^(The sqlite3_value_numeric_type() interface attempts to apply
+** numeric affinity to the value.  This means that an attempt is
+** made to convert the value to an integer or floating point.  If
+** such a conversion is possible without loss of information (in other
+** words, if the value is a string that looks like a number)
+** then the conversion is performed.  Otherwise no conversion occurs.
+** The [SQLITE_INTEGER | datatype] after conversion is returned.)^
+**
+** Please pay particular attention to the fact that the pointer returned
+** from [sqlite3_value_blob()], [sqlite3_value_text()], or
+** [sqlite3_value_text16()] can be invalidated by a subsequent call to
+** [sqlite3_value_bytes()], [sqlite3_value_bytes16()], [sqlite3_value_text()],
+** or [sqlite3_value_text16()].
+**
+** These routines must be called from the same thread as
+** the SQL function that supplied the [sqlite3_value*] parameters.
+*/
+SQLITE_API const void *sqlite3_value_blob(sqlite3_value*);
+SQLITE_API int sqlite3_value_bytes(sqlite3_value*);
+SQLITE_API int sqlite3_value_bytes16(sqlite3_value*);
+SQLITE_API double sqlite3_value_double(sqlite3_value*);
+SQLITE_API int sqlite3_value_int(sqlite3_value*);
+SQLITE_API sqlite3_int64 sqlite3_value_int64(sqlite3_value*);
+SQLITE_API const unsigned char *sqlite3_value_text(sqlite3_value*);
+SQLITE_API const void *sqlite3_value_text16(sqlite3_value*);
+SQLITE_API const void *sqlite3_value_text16le(sqlite3_value*);
+SQLITE_API const void *sqlite3_value_text16be(sqlite3_value*);
+SQLITE_API int sqlite3_value_type(sqlite3_value*);
+SQLITE_API int sqlite3_value_numeric_type(sqlite3_value*);
+
+/*
+** CAPI3REF: Obtain Aggregate Function Context
+**
+** Implementations of aggregate SQL functions use this
+** routine to allocate memory for storing their state.
+**
+** ^The first time the sqlite3_aggregate_context(C,N) routine is called 
+** for a particular aggregate function, SQLite
+** allocates N of memory, zeroes out that memory, and returns a pointer
+** to the new memory. ^On second and subsequent calls to
+** sqlite3_aggregate_context() for the same aggregate function instance,
+** the same buffer is returned.  Sqlite3_aggregate_context() is normally
+** called once for each invocation of the xStep callback and then one
+** last time when the xFinal callback is invoked.  ^(When no rows match
+** an aggregate query, the xStep() callback of the aggregate function
+** implementation is never called and xFinal() is called exactly once.
+** In those cases, sqlite3_aggregate_context() might be called for the
+** first time from within xFinal().)^
+**
+** ^The sqlite3_aggregate_context(C,N) routine returns a NULL pointer if N is
+** less than or equal to zero or if a memory allocate error occurs.
+**
+** ^(The amount of space allocated by sqlite3_aggregate_context(C,N) is
+** determined by the N parameter on first successful call.  Changing the
+** value of N in subsequent call to sqlite3_aggregate_context() within
+** the same aggregate function instance will not resize the memory
+** allocation.)^
+**
+** ^SQLite automatically frees the memory allocated by 
+** sqlite3_aggregate_context() when the aggregate query concludes.
+**
+** The first parameter must be a copy of the
+** [sqlite3_context | SQL function context] that is the first parameter
+** to the xStep or xFinal callback routine that implements the aggregate
+** function.
+**
+** This routine must be called from the same thread in which
+** the aggregate SQL function is running.
+*/
+SQLITE_API void *sqlite3_aggregate_context(sqlite3_context*, int nBytes);
+
+/*
+** CAPI3REF: User Data For Functions
+**
+** ^The sqlite3_user_data() interface returns a copy of
+** the pointer that was the pUserData parameter (the 5th parameter)
+** of the [sqlite3_create_function()]
+** and [sqlite3_create_function16()] routines that originally
+** registered the application defined function.
+**
+** This routine must be called from the same thread in which
+** the application-defined function is running.
+*/
+SQLITE_API void *sqlite3_user_data(sqlite3_context*);
+
+/*
+** CAPI3REF: Database Connection For Functions
+**
+** ^The sqlite3_context_db_handle() interface returns a copy of
+** the pointer to the [database connection] (the 1st parameter)
+** of the [sqlite3_create_function()]
+** and [sqlite3_create_function16()] routines that originally
+** registered the application defined function.
+*/
+SQLITE_API sqlite3 *sqlite3_context_db_handle(sqlite3_context*);
+
+/*
+** CAPI3REF: Function Auxiliary Data
+**
+** The following two functions may be used by scalar SQL functions to
+** associate metadata with argument values. If the same value is passed to
+** multiple invocations of the same SQL function during query execution, under
+** some circumstances the associated metadata may be preserved. This may
+** be used, for example, to add a regular-expression matching scalar
+** function. The compiled version of the regular expression is stored as
+** metadata associated with the SQL value passed as the regular expression
+** pattern.  The compiled regular expression can be reused on multiple
+** invocations of the same function so that the original pattern string
+** does not need to be recompiled on each invocation.
+**
+** ^The sqlite3_get_auxdata() interface returns a pointer to the metadata
+** associated by the sqlite3_set_auxdata() function with the Nth argument
+** value to the application-defined function. ^If no metadata has been ever
+** been set for the Nth argument of the function, or if the corresponding
+** function parameter has changed since the meta-data was set,
+** then sqlite3_get_auxdata() returns a NULL pointer.
+**
+** ^The sqlite3_set_auxdata() interface saves the metadata
+** pointed to by its 3rd parameter as the metadata for the N-th
+** argument of the application-defined function.  Subsequent
+** calls to sqlite3_get_auxdata() might return this data, if it has
+** not been destroyed.
+** ^If it is not NULL, SQLite will invoke the destructor
+** function given by the 4th parameter to sqlite3_set_auxdata() on
+** the metadata when the corresponding function parameter changes
+** or when the SQL statement completes, whichever comes first.
+**
+** SQLite is free to call the destructor and drop metadata on any
+** parameter of any function at any time.  ^The only guarantee is that
+** the destructor will be called before the metadata is dropped.
+**
+** ^(In practice, metadata is preserved between function calls for
+** expressions that are constant at compile time. This includes literal
+** values and [parameters].)^
+**
+** These routines must be called from the same thread in which
+** the SQL function is running.
+*/
+SQLITE_API void *sqlite3_get_auxdata(sqlite3_context*, int N);
+SQLITE_API void sqlite3_set_auxdata(sqlite3_context*, int N, void*, void (*)(void*));
+
+
+/*
+** CAPI3REF: Constants Defining Special Destructor Behavior
+**
+** These are special values for the destructor that is passed in as the
+** final argument to routines like [sqlite3_result_blob()].  ^If the destructor
+** argument is SQLITE_STATIC, it means that the content pointer is constant
+** and will never change.  It does not need to be destroyed.  ^The
+** SQLITE_TRANSIENT value means that the content will likely change in
+** the near future and that SQLite should make its own private copy of
+** the content before returning.
+**
+** The typedef is necessary to work around problems in certain
+** C++ compilers.  See ticket #2191.
+*/
+typedef void (*sqlite3_destructor_type)(void*);
+#define SQLITE_STATIC      ((sqlite3_destructor_type)0)
+#define SQLITE_TRANSIENT   ((sqlite3_destructor_type)-1)
+
+/*
+** CAPI3REF: Setting The Result Of An SQL Function
+**
+** These routines are used by the xFunc or xFinal callbacks that
+** implement SQL functions and aggregates.  See
+** [sqlite3_create_function()] and [sqlite3_create_function16()]
+** for additional information.
+**
+** These functions work very much like the [parameter binding] family of
+** functions used to bind values to host parameters in prepared statements.
+** Refer to the [SQL parameter] documentation for additional information.
+**
+** ^The sqlite3_result_blob() interface sets the result from
+** an application-defined function to be the BLOB whose content is pointed
+** to by the second parameter and which is N bytes long where N is the
+** third parameter.
+**
+** ^The sqlite3_result_zeroblob() interfaces set the result of
+** the application-defined function to be a BLOB containing all zero
+** bytes and N bytes in size, where N is the value of the 2nd parameter.
+**
+** ^The sqlite3_result_double() interface sets the result from
+** an application-defined function to be a floating point value specified
+** by its 2nd argument.
+**
+** ^The sqlite3_result_error() and sqlite3_result_error16() functions
+** cause the implemented SQL function to throw an exception.
+** ^SQLite uses the string pointed to by the
+** 2nd parameter of sqlite3_result_error() or sqlite3_result_error16()
+** as the text of an error message.  ^SQLite interprets the error
+** message string from sqlite3_result_error() as UTF-8. ^SQLite
+** interprets the string from sqlite3_result_error16() as UTF-16 in native
+** byte order.  ^If the third parameter to sqlite3_result_error()
+** or sqlite3_result_error16() is negative then SQLite takes as the error
+** message all text up through the first zero character.
+** ^If the third parameter to sqlite3_result_error() or
+** sqlite3_result_error16() is non-negative then SQLite takes that many
+** bytes (not characters) from the 2nd parameter as the error message.
+** ^The sqlite3_result_error() and sqlite3_result_error16()
+** routines make a private copy of the error message text before
+** they return.  Hence, the calling function can deallocate or
+** modify the text after they return without harm.
+** ^The sqlite3_result_error_code() function changes the error code
+** returned by SQLite as a result of an error in a function.  ^By default,
+** the error code is SQLITE_ERROR.  ^A subsequent call to sqlite3_result_error()
+** or sqlite3_result_error16() resets the error code to SQLITE_ERROR.
+**
+** ^The sqlite3_result_toobig() interface causes SQLite to throw an error
+** indicating that a string or BLOB is too long to represent.
+**
+** ^The sqlite3_result_nomem() interface causes SQLite to throw an error
+** indicating that a memory allocation failed.
+**
+** ^The sqlite3_result_int() interface sets the return value
+** of the application-defined function to be the 32-bit signed integer
+** value given in the 2nd argument.
+** ^The sqlite3_result_int64() interface sets the return value
+** of the application-defined function to be the 64-bit signed integer
+** value given in the 2nd argument.
+**
+** ^The sqlite3_result_null() interface sets the return value
+** of the application-defined function to be NULL.
+**
+** ^The sqlite3_result_text(), sqlite3_result_text16(),
+** sqlite3_result_text16le(), and sqlite3_result_text16be() interfaces
+** set the return value of the application-defined function to be
+** a text string which is represented as UTF-8, UTF-16 native byte order,
+** UTF-16 little endian, or UTF-16 big endian, respectively.
+** ^SQLite takes the text result from the application from
+** the 2nd parameter of the sqlite3_result_text* interfaces.
+** ^If the 3rd parameter to the sqlite3_result_text* interfaces
+** is negative, then SQLite takes result text from the 2nd parameter
+** through the first zero character.
+** ^If the 3rd parameter to the sqlite3_result_text* interfaces
+** is non-negative, then as many bytes (not characters) of the text
+** pointed to by the 2nd parameter are taken as the application-defined
+** function result.
+** ^If the 4th parameter to the sqlite3_result_text* interfaces
+** or sqlite3_result_blob is a non-NULL pointer, then SQLite calls that
+** function as the destructor on the text or BLOB result when it has
+** finished using that result.
+** ^If the 4th parameter to the sqlite3_result_text* interfaces or to
+** sqlite3_result_blob is the special constant SQLITE_STATIC, then SQLite
+** assumes that the text or BLOB result is in constant space and does not
+** copy the content of the parameter nor call a destructor on the content
+** when it has finished using that result.
+** ^If the 4th parameter to the sqlite3_result_text* interfaces
+** or sqlite3_result_blob is the special constant SQLITE_TRANSIENT
+** then SQLite makes a copy of the result into space obtained from
+** from [sqlite3_malloc()] before it returns.
+**
+** ^The sqlite3_result_value() interface sets the result of
+** the application-defined function to be a copy the
+** [unprotected sqlite3_value] object specified by the 2nd parameter.  ^The
+** sqlite3_result_value() interface makes a copy of the [sqlite3_value]
+** so that the [sqlite3_value] specified in the parameter may change or
+** be deallocated after sqlite3_result_value() returns without harm.
+** ^A [protected sqlite3_value] object may always be used where an
+** [unprotected sqlite3_value] object is required, so either
+** kind of [sqlite3_value] object can be used with this interface.
+**
+** If these routines are called from within the different thread
+** than the one containing the application-defined function that received
+** the [sqlite3_context] pointer, the results are undefined.
+*/
+SQLITE_API void sqlite3_result_blob(sqlite3_context*, const void*, int, void(*)(void*));
+SQLITE_API void sqlite3_result_double(sqlite3_context*, double);
+SQLITE_API void sqlite3_result_error(sqlite3_context*, const char*, int);
+SQLITE_API void sqlite3_result_error16(sqlite3_context*, const void*, int);
+SQLITE_API void sqlite3_result_error_toobig(sqlite3_context*);
+SQLITE_API void sqlite3_result_error_nomem(sqlite3_context*);
+SQLITE_API void sqlite3_result_error_code(sqlite3_context*, int);
+SQLITE_API void sqlite3_result_int(sqlite3_context*, int);
+SQLITE_API void sqlite3_result_int64(sqlite3_context*, sqlite3_int64);
+SQLITE_API void sqlite3_result_null(sqlite3_context*);
+SQLITE_API void sqlite3_result_text(sqlite3_context*, const char*, int, void(*)(void*));
+SQLITE_API void sqlite3_result_text16(sqlite3_context*, const void*, int, void(*)(void*));
+SQLITE_API void sqlite3_result_text16le(sqlite3_context*, const void*, int,void(*)(void*));
+SQLITE_API void sqlite3_result_text16be(sqlite3_context*, const void*, int,void(*)(void*));
+SQLITE_API void sqlite3_result_value(sqlite3_context*, sqlite3_value*);
+SQLITE_API void sqlite3_result_zeroblob(sqlite3_context*, int n);
+
+/*
+** CAPI3REF: Define New Collating Sequences
+**
+** ^These functions add, remove, or modify a [collation] associated
+** with the [database connection] specified as the first argument.
+**
+** ^The name of the collation is a UTF-8 string
+** for sqlite3_create_collation() and sqlite3_create_collation_v2()
+** and a UTF-16 string in native byte order for sqlite3_create_collation16().
+** ^Collation names that compare equal according to [sqlite3_strnicmp()] are
+** considered to be the same name.
+**
+** ^(The third argument (eTextRep) must be one of the constants:
+** <ul>
+** <li> [SQLITE_UTF8],
+** <li> [SQLITE_UTF16LE],
+** <li> [SQLITE_UTF16BE],
+** <li> [SQLITE_UTF16], or
+** <li> [SQLITE_UTF16_ALIGNED].
+** </ul>)^
+** ^The eTextRep argument determines the encoding of strings passed
+** to the collating function callback, xCallback.
+** ^The [SQLITE_UTF16] and [SQLITE_UTF16_ALIGNED] values for eTextRep
+** force strings to be UTF16 with native byte order.
+** ^The [SQLITE_UTF16_ALIGNED] value for eTextRep forces strings to begin
+** on an even byte address.
+**
+** ^The fourth argument, pArg, is an application data pointer that is passed
+** through as the first argument to the collating function callback.
+**
+** ^The fifth argument, xCallback, is a pointer to the collating function.
+** ^Multiple collating functions can be registered using the same name but
+** with different eTextRep parameters and SQLite will use whichever
+** function requires the least amount of data transformation.
+** ^If the xCallback argument is NULL then the collating function is
+** deleted.  ^When all collating functions having the same name are deleted,
+** that collation is no longer usable.
+**
+** ^The collating function callback is invoked with a copy of the pArg 
+** application data pointer and with two strings in the encoding specified
+** by the eTextRep argument.  The collating function must return an
+** integer that is negative, zero, or positive
+** if the first string is less than, equal to, or greater than the second,
+** respectively.  A collating function must always return the same answer
+** given the same inputs.  If two or more collating functions are registered
+** to the same collation name (using different eTextRep values) then all
+** must give an equivalent answer when invoked with equivalent strings.
+** The collating function must obey the following properties for all
+** strings A, B, and C:
+**
+** <ol>
+** <li> If A==B then B==A.
+** <li> If A==B and B==C then A==C.
+** <li> If A&lt;B THEN B&gt;A.
+** <li> If A&lt;B and B&lt;C then A&lt;C.
+** </ol>
+**
+** If a collating function fails any of the above constraints and that
+** collating function is  registered and used, then the behavior of SQLite
+** is undefined.
+**
+** ^The sqlite3_create_collation_v2() works like sqlite3_create_collation()
+** with the addition that the xDestroy callback is invoked on pArg when
+** the collating function is deleted.
+** ^Collating functions are deleted when they are overridden by later
+** calls to the collation creation functions or when the
+** [database connection] is closed using [sqlite3_close()].
+**
+** ^The xDestroy callback is <u>not</u> called if the 
+** sqlite3_create_collation_v2() function fails.  Applications that invoke
+** sqlite3_create_collation_v2() with a non-NULL xDestroy argument should 
+** check the return code and dispose of the application data pointer
+** themselves rather than expecting SQLite to deal with it for them.
+** This is different from every other SQLite interface.  The inconsistency 
+** is unfortunate but cannot be changed without breaking backwards 
+** compatibility.
+**
+** See also:  [sqlite3_collation_needed()] and [sqlite3_collation_needed16()].
+*/
+SQLITE_API int sqlite3_create_collation(
+  sqlite3*, 
+  const char *zName, 
+  int eTextRep, 
+  void *pArg,
+  int(*xCompare)(void*,int,const void*,int,const void*)
+);
+SQLITE_API int sqlite3_create_collation_v2(
+  sqlite3*, 
+  const char *zName, 
+  int eTextRep, 
+  void *pArg,
+  int(*xCompare)(void*,int,const void*,int,const void*),
+  void(*xDestroy)(void*)
+);
+SQLITE_API int sqlite3_create_collation16(
+  sqlite3*, 
+  const void *zName,
+  int eTextRep, 
+  void *pArg,
+  int(*xCompare)(void*,int,const void*,int,const void*)
+);
+
+/*
+** CAPI3REF: Collation Needed Callbacks
+**
+** ^To avoid having to register all collation sequences before a database
+** can be used, a single callback function may be registered with the
+** [database connection] to be invoked whenever an undefined collation
+** sequence is required.
+**
+** ^If the function is registered using the sqlite3_collation_needed() API,
+** then it is passed the names of undefined collation sequences as strings
+** encoded in UTF-8. ^If sqlite3_collation_needed16() is used,
+** the names are passed as UTF-16 in machine native byte order.
+** ^A call to either function replaces the existing collation-needed callback.
+**
+** ^(When the callback is invoked, the first argument passed is a copy
+** of the second argument to sqlite3_collation_needed() or
+** sqlite3_collation_needed16().  The second argument is the database
+** connection.  The third argument is one of [SQLITE_UTF8], [SQLITE_UTF16BE],
+** or [SQLITE_UTF16LE], indicating the most desirable form of the collation
+** sequence function required.  The fourth parameter is the name of the
+** required collation sequence.)^
+**
+** The callback function should register the desired collation using
+** [sqlite3_create_collation()], [sqlite3_create_collation16()], or
+** [sqlite3_create_collation_v2()].
+*/
+SQLITE_API int sqlite3_collation_needed(
+  sqlite3*, 
+  void*, 
+  void(*)(void*,sqlite3*,int eTextRep,const char*)
+);
+SQLITE_API int sqlite3_collation_needed16(
+  sqlite3*, 
+  void*,
+  void(*)(void*,sqlite3*,int eTextRep,const void*)
+);
+
+#ifdef SQLITE_HAS_CODEC
+/*
+** Specify the key for an encrypted database.  This routine should be
+** called right after sqlite3_open().
+**
+** The code to implement this API is not available in the public release
+** of SQLite.
+*/
+SQLITE_API int sqlite3_key(
+  sqlite3 *db,                   /* Database to be rekeyed */
+  const void *pKey, int nKey     /* The key */
+);
+
+/*
+** Change the key on an open database.  If the current database is not
+** encrypted, this routine will encrypt it.  If pNew==0 or nNew==0, the
+** database is decrypted.
+**
+** The code to implement this API is not available in the public release
+** of SQLite.
+*/
+SQLITE_API int sqlite3_rekey(
+  sqlite3 *db,                   /* Database to be rekeyed */
+  const void *pKey, int nKey     /* The new key */
+);
+
+/*
+** Specify the activation key for a SEE database.  Unless 
+** activated, none of the SEE routines will work.
+*/
+SQLITE_API void sqlite3_activate_see(
+  const char *zPassPhrase        /* Activation phrase */
+);
+#endif
+
+#ifdef SQLITE_ENABLE_CEROD
+/*
+** Specify the activation key for a CEROD database.  Unless 
+** activated, none of the CEROD routines will work.
+*/
+SQLITE_API void sqlite3_activate_cerod(
+  const char *zPassPhrase        /* Activation phrase */
+);
+#endif
+
+/*
+** CAPI3REF: Suspend Execution For A Short Time
+**
+** The sqlite3_sleep() function causes the current thread to suspend execution
+** for at least a number of milliseconds specified in its parameter.
+**
+** If the operating system does not support sleep requests with
+** millisecond time resolution, then the time will be rounded up to
+** the nearest second. The number of milliseconds of sleep actually
+** requested from the operating system is returned.
+**
+** ^SQLite implements this interface by calling the xSleep()
+** method of the default [sqlite3_vfs] object.  If the xSleep() method
+** of the default VFS is not implemented correctly, or not implemented at
+** all, then the behavior of sqlite3_sleep() may deviate from the description
+** in the previous paragraphs.
+*/
+SQLITE_API int sqlite3_sleep(int);
+
+/*
+** CAPI3REF: Name Of The Folder Holding Temporary Files
+**
+** ^(If this global variable is made to point to a string which is
+** the name of a folder (a.k.a. directory), then all temporary files
+** created by SQLite when using a built-in [sqlite3_vfs | VFS]
+** will be placed in that directory.)^  ^If this variable
+** is a NULL pointer, then SQLite performs a search for an appropriate
+** temporary file directory.
+**
+** It is not safe to read or modify this variable in more than one
+** thread at a time.  It is not safe to read or modify this variable
+** if a [database connection] is being used at the same time in a separate
+** thread.
+** It is intended that this variable be set once
+** as part of process initialization and before any SQLite interface
+** routines have been called and that this variable remain unchanged
+** thereafter.
+**
+** ^The [temp_store_directory pragma] may modify this variable and cause
+** it to point to memory obtained from [sqlite3_malloc].  ^Furthermore,
+** the [temp_store_directory pragma] always assumes that any string
+** that this variable points to is held in memory obtained from 
+** [sqlite3_malloc] and the pragma may attempt to free that memory
+** using [sqlite3_free].
+** Hence, if this variable is modified directly, either it should be
+** made NULL or made to point to memory obtained from [sqlite3_malloc]
+** or else the use of the [temp_store_directory pragma] should be avoided.
+*/
+SQLITE_API char *sqlite3_temp_directory;
+
+/*
+** CAPI3REF: Test For Auto-Commit Mode
+** KEYWORDS: {autocommit mode}
+**
+** ^The sqlite3_get_autocommit() interface returns non-zero or
+** zero if the given database connection is or is not in autocommit mode,
+** respectively.  ^Autocommit mode is on by default.
+** ^Autocommit mode is disabled by a [BEGIN] statement.
+** ^Autocommit mode is re-enabled by a [COMMIT] or [ROLLBACK].
+**
+** If certain kinds of errors occur on a statement within a multi-statement
+** transaction (errors including [SQLITE_FULL], [SQLITE_IOERR],
+** [SQLITE_NOMEM], [SQLITE_BUSY], and [SQLITE_INTERRUPT]) then the
+** transaction might be rolled back automatically.  The only way to
+** find out whether SQLite automatically rolled back the transaction after
+** an error is to use this function.
+**
+** If another thread changes the autocommit status of the database
+** connection while this routine is running, then the return value
+** is undefined.
+*/
+SQLITE_API int sqlite3_get_autocommit(sqlite3*);
+
+/*
+** CAPI3REF: Find The Database Handle Of A Prepared Statement
+**
+** ^The sqlite3_db_handle interface returns the [database connection] handle
+** to which a [prepared statement] belongs.  ^The [database connection]
+** returned by sqlite3_db_handle is the same [database connection]
+** that was the first argument
+** to the [sqlite3_prepare_v2()] call (or its variants) that was used to
+** create the statement in the first place.
+*/
+SQLITE_API sqlite3 *sqlite3_db_handle(sqlite3_stmt*);
+
+/*
+** CAPI3REF: Find the next prepared statement
+**
+** ^This interface returns a pointer to the next [prepared statement] after
+** pStmt associated with the [database connection] pDb.  ^If pStmt is NULL
+** then this interface returns a pointer to the first prepared statement
+** associated with the database connection pDb.  ^If no prepared statement
+** satisfies the conditions of this routine, it returns NULL.
+**
+** The [database connection] pointer D in a call to
+** [sqlite3_next_stmt(D,S)] must refer to an open database
+** connection and in particular must not be a NULL pointer.
+*/
+SQLITE_API sqlite3_stmt *sqlite3_next_stmt(sqlite3 *pDb, sqlite3_stmt *pStmt);
+
+/*
+** CAPI3REF: Commit And Rollback Notification Callbacks
+**
+** ^The sqlite3_commit_hook() interface registers a callback
+** function to be invoked whenever a transaction is [COMMIT | committed].
+** ^Any callback set by a previous call to sqlite3_commit_hook()
+** for the same database connection is overridden.
+** ^The sqlite3_rollback_hook() interface registers a callback
+** function to be invoked whenever a transaction is [ROLLBACK | rolled back].
+** ^Any callback set by a previous call to sqlite3_rollback_hook()
+** for the same database connection is overridden.
+** ^The pArg argument is passed through to the callback.
+** ^If the callback on a commit hook function returns non-zero,
+** then the commit is converted into a rollback.
+**
+** ^The sqlite3_commit_hook(D,C,P) and sqlite3_rollback_hook(D,C,P) functions
+** return the P argument from the previous call of the same function
+** on the same [database connection] D, or NULL for
+** the first call for each function on D.
+**
+** The callback implementation must not do anything that will modify
+** the database connection that invoked the callback.  Any actions
+** to modify the database connection must be deferred until after the
+** completion of the [sqlite3_step()] call that triggered the commit
+** or rollback hook in the first place.
+** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
+** database connections for the meaning of "modify" in this paragraph.
+**
+** ^Registering a NULL function disables the callback.
+**
+** ^When the commit hook callback routine returns zero, the [COMMIT]
+** operation is allowed to continue normally.  ^If the commit hook
+** returns non-zero, then the [COMMIT] is converted into a [ROLLBACK].
+** ^The rollback hook is invoked on a rollback that results from a commit
+** hook returning non-zero, just as it would be with any other rollback.
+**
+** ^For the purposes of this API, a transaction is said to have been
+** rolled back if an explicit "ROLLBACK" statement is executed, or
+** an error or constraint causes an implicit rollback to occur.
+** ^The rollback callback is not invoked if a transaction is
+** automatically rolled back because the database connection is closed.
+**
+** See also the [sqlite3_update_hook()] interface.
+*/
+SQLITE_API void *sqlite3_commit_hook(sqlite3*, int(*)(void*), void*);
+SQLITE_API void *sqlite3_rollback_hook(sqlite3*, void(*)(void *), void*);
+
+/*
+** CAPI3REF: Data Change Notification Callbacks
+**
+** ^The sqlite3_update_hook() interface registers a callback function
+** with the [database connection] identified by the first argument
+** to be invoked whenever a row is updated, inserted or deleted.
+** ^Any callback set by a previous call to this function
+** for the same database connection is overridden.
+**
+** ^The second argument is a pointer to the function to invoke when a
+** row is updated, inserted or deleted.
+** ^The first argument to the callback is a copy of the third argument
+** to sqlite3_update_hook().
+** ^The second callback argument is one of [SQLITE_INSERT], [SQLITE_DELETE],
+** or [SQLITE_UPDATE], depending on the operation that caused the callback
+** to be invoked.
+** ^The third and fourth arguments to the callback contain pointers to the
+** database and table name containing the affected row.
+** ^The final callback parameter is the [rowid] of the row.
+** ^In the case of an update, this is the [rowid] after the update takes place.
+**
+** ^(The update hook is not invoked when internal system tables are
+** modified (i.e. sqlite_master and sqlite_sequence).)^
+**
+** ^In the current implementation, the update hook
+** is not invoked when duplication rows are deleted because of an
+** [ON CONFLICT | ON CONFLICT REPLACE] clause.  ^Nor is the update hook
+** invoked when rows are deleted using the [truncate optimization].
+** The exceptions defined in this paragraph might change in a future
+** release of SQLite.
+**
+** The update hook implementation must not do anything that will modify
+** the database connection that invoked the update hook.  Any actions
+** to modify the database connection must be deferred until after the
+** completion of the [sqlite3_step()] call that triggered the update hook.
+** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
+** database connections for the meaning of "modify" in this paragraph.
+**
+** ^The sqlite3_update_hook(D,C,P) function
+** returns the P argument from the previous call
+** on the same [database connection] D, or NULL for
+** the first call on D.
+**
+** See also the [sqlite3_commit_hook()] and [sqlite3_rollback_hook()]
+** interfaces.
+*/
+SQLITE_API void *sqlite3_update_hook(
+  sqlite3*, 
+  void(*)(void *,int ,char const *,char const *,sqlite3_int64),
+  void*
+);
+
+/*
+** CAPI3REF: Enable Or Disable Shared Pager Cache
+** KEYWORDS: {shared cache}
+**
+** ^(This routine enables or disables the sharing of the database cache
+** and schema data structures between [database connection | connections]
+** to the same database. Sharing is enabled if the argument is true
+** and disabled if the argument is false.)^
+**
+** ^Cache sharing is enabled and disabled for an entire process.
+** This is a change as of SQLite version 3.5.0. In prior versions of SQLite,
+** sharing was enabled or disabled for each thread separately.
+**
+** ^(The cache sharing mode set by this interface effects all subsequent
+** calls to [sqlite3_open()], [sqlite3_open_v2()], and [sqlite3_open16()].
+** Existing database connections continue use the sharing mode
+** that was in effect at the time they were opened.)^
+**
+** ^(This routine returns [SQLITE_OK] if shared cache was enabled or disabled
+** successfully.  An [error code] is returned otherwise.)^
+**
+** ^Shared cache is disabled by default. But this might change in
+** future releases of SQLite.  Applications that care about shared
+** cache setting should set it explicitly.
+**
+** See Also:  [SQLite Shared-Cache Mode]
+*/
+SQLITE_API int sqlite3_enable_shared_cache(int);
+
+/*
+** CAPI3REF: Attempt To Free Heap Memory
+**
+** ^The sqlite3_release_memory() interface attempts to free N bytes
+** of heap memory by deallocating non-essential memory allocations
+** held by the database library.   Memory used to cache database
+** pages to improve performance is an example of non-essential memory.
+** ^sqlite3_release_memory() returns the number of bytes actually freed,
+** which might be more or less than the amount requested.
+** ^The sqlite3_release_memory() routine is a no-op returning zero
+** if SQLite is not compiled with [SQLITE_ENABLE_MEMORY_MANAGEMENT].
+*/
+SQLITE_API int sqlite3_release_memory(int);
+
+/*
+** CAPI3REF: Impose A Limit On Heap Size
+**
+** ^The sqlite3_soft_heap_limit64() interface sets and/or queries the
+** soft limit on the amount of heap memory that may be allocated by SQLite.
+** ^SQLite strives to keep heap memory utilization below the soft heap
+** limit by reducing the number of pages held in the page cache
+** as heap memory usages approaches the limit.
+** ^The soft heap limit is "soft" because even though SQLite strives to stay
+** below the limit, it will exceed the limit rather than generate
+** an [SQLITE_NOMEM] error.  In other words, the soft heap limit 
+** is advisory only.
+**
+** ^The return value from sqlite3_soft_heap_limit64() is the size of
+** the soft heap limit prior to the call.  ^If the argument N is negative
+** then no change is made to the soft heap limit.  Hence, the current
+** size of the soft heap limit can be determined by invoking
+** sqlite3_soft_heap_limit64() with a negative argument.
+**
+** ^If the argument N is zero then the soft heap limit is disabled.
+**
+** ^(The soft heap limit is not enforced in the current implementation
+** if one or more of following conditions are true:
+**
+** <ul>
+** <li> The soft heap limit is set to zero.
+** <li> Memory accounting is disabled using a combination of the
+**      [sqlite3_config]([SQLITE_CONFIG_MEMSTATUS],...) start-time option and
+**      the [SQLITE_DEFAULT_MEMSTATUS] compile-time option.
+** <li> An alternative page cache implementation is specified using
+**      [sqlite3_config]([SQLITE_CONFIG_PCACHE],...).
+** <li> The page cache allocates from its own memory pool supplied
+**      by [sqlite3_config]([SQLITE_CONFIG_PAGECACHE],...) rather than
+**      from the heap.
+** </ul>)^
+**
+** Beginning with SQLite version 3.7.3, the soft heap limit is enforced
+** regardless of whether or not the [SQLITE_ENABLE_MEMORY_MANAGEMENT]
+** compile-time option is invoked.  With [SQLITE_ENABLE_MEMORY_MANAGEMENT],
+** the soft heap limit is enforced on every memory allocation.  Without
+** [SQLITE_ENABLE_MEMORY_MANAGEMENT], the soft heap limit is only enforced
+** when memory is allocated by the page cache.  Testing suggests that because
+** the page cache is the predominate memory user in SQLite, most
+** applications will achieve adequate soft heap limit enforcement without
+** the use of [SQLITE_ENABLE_MEMORY_MANAGEMENT].
+**
+** The circumstances under which SQLite will enforce the soft heap limit may
+** changes in future releases of SQLite.
+*/
+SQLITE_API sqlite3_int64 sqlite3_soft_heap_limit64(sqlite3_int64 N);
+
+/*
+** CAPI3REF: Deprecated Soft Heap Limit Interface
+** DEPRECATED
+**
+** This is a deprecated version of the [sqlite3_soft_heap_limit64()]
+** interface.  This routine is provided for historical compatibility
+** only.  All new applications should use the
+** [sqlite3_soft_heap_limit64()] interface rather than this one.
+*/
+SQLITE_API SQLITE_DEPRECATED void sqlite3_soft_heap_limit(int N);
+
+
+/*
+** CAPI3REF: Extract Metadata About A Column Of A Table
+**
+** ^This routine returns metadata about a specific column of a specific
+** database table accessible using the [database connection] handle
+** passed as the first function argument.
+**
+** ^The column is identified by the second, third and fourth parameters to
+** this function. ^The second parameter is either the name of the database
+** (i.e. "main", "temp", or an attached database) containing the specified
+** table or NULL. ^If it is NULL, then all attached databases are searched
+** for the table using the same algorithm used by the database engine to
+** resolve unqualified table references.
+**
+** ^The third and fourth parameters to this function are the table and column
+** name of the desired column, respectively. Neither of these parameters
+** may be NULL.
+**
+** ^Metadata is returned by writing to the memory locations passed as the 5th
+** and subsequent parameters to this function. ^Any of these arguments may be
+** NULL, in which case the corresponding element of metadata is omitted.
+**
+** ^(<blockquote>
+** <table border="1">
+** <tr><th> Parameter <th> Output<br>Type <th>  Description
+**
+** <tr><td> 5th <td> const char* <td> Data type
+** <tr><td> 6th <td> const char* <td> Name of default collation sequence
+** <tr><td> 7th <td> int         <td> True if column has a NOT NULL constraint
+** <tr><td> 8th <td> int         <td> True if column is part of the PRIMARY KEY
+** <tr><td> 9th <td> int         <td> True if column is [AUTOINCREMENT]
+** </table>
+** </blockquote>)^
+**
+** ^The memory pointed to by the character pointers returned for the
+** declaration type and collation sequence is valid only until the next
+** call to any SQLite API function.
+**
+** ^If the specified table is actually a view, an [error code] is returned.
+**
+** ^If the specified column is "rowid", "oid" or "_rowid_" and an
+** [INTEGER PRIMARY KEY] column has been explicitly declared, then the output
+** parameters are set for the explicitly declared column. ^(If there is no
+** explicitly declared [INTEGER PRIMARY KEY] column, then the output
+** parameters are set as follows:
+**
+** <pre>
+**     data type: "INTEGER"
+**     collation sequence: "BINARY"
+**     not null: 0
+**     primary key: 1
+**     auto increment: 0
+** </pre>)^
+**
+** ^(This function may load one or more schemas from database files. If an
+** error occurs during this process, or if the requested table or column
+** cannot be found, an [error code] is returned and an error message left
+** in the [database connection] (to be retrieved using sqlite3_errmsg()).)^
+**
+** ^This API is only available if the library was compiled with the
+** [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol defined.
+*/
+SQLITE_API int sqlite3_table_column_metadata(
+  sqlite3 *db,                /* Connection handle */
+  const char *zDbName,        /* Database name or NULL */
+  const char *zTableName,     /* Table name */
+  const char *zColumnName,    /* Column name */
+  char const **pzDataType,    /* OUTPUT: Declared data type */
+  char const **pzCollSeq,     /* OUTPUT: Collation sequence name */
+  int *pNotNull,              /* OUTPUT: True if NOT NULL constraint exists */
+  int *pPrimaryKey,           /* OUTPUT: True if column part of PK */
+  int *pAutoinc               /* OUTPUT: True if column is auto-increment */
+);
+
+/*
+** CAPI3REF: Load An Extension
+**
+** ^This interface loads an SQLite extension library from the named file.
+**
+** ^The sqlite3_load_extension() interface attempts to load an
+** SQLite extension library contained in the file zFile.
+**
+** ^The entry point is zProc.
+** ^zProc may be 0, in which case the name of the entry point
+** defaults to "sqlite3_extension_init".
+** ^The sqlite3_load_extension() interface returns
+** [SQLITE_OK] on success and [SQLITE_ERROR] if something goes wrong.
+** ^If an error occurs and pzErrMsg is not 0, then the
+** [sqlite3_load_extension()] interface shall attempt to
+** fill *pzErrMsg with error message text stored in memory
+** obtained from [sqlite3_malloc()]. The calling function
+** should free this memory by calling [sqlite3_free()].
+**
+** ^Extension loading must be enabled using
+** [sqlite3_enable_load_extension()] prior to calling this API,
+** otherwise an error will be returned.
+**
+** See also the [load_extension() SQL function].
+*/
+SQLITE_API int sqlite3_load_extension(
+  sqlite3 *db,          /* Load the extension into this database connection */
+  const char *zFile,    /* Name of the shared library containing extension */
+  const char *zProc,    /* Entry point.  Derived from zFile if 0 */
+  char **pzErrMsg       /* Put error message here if not 0 */
+);
+
+/*
+** CAPI3REF: Enable Or Disable Extension Loading
+**
+** ^So as not to open security holes in older applications that are
+** unprepared to deal with extension loading, and as a means of disabling
+** extension loading while evaluating user-entered SQL, the following API
+** is provided to turn the [sqlite3_load_extension()] mechanism on and off.
+**
+** ^Extension loading is off by default. See ticket #1863.
+** ^Call the sqlite3_enable_load_extension() routine with onoff==1
+** to turn extension loading on and call it with onoff==0 to turn
+** it back off again.
+*/
+SQLITE_API int sqlite3_enable_load_extension(sqlite3 *db, int onoff);
+
+/*
+** CAPI3REF: Automatically Load Statically Linked Extensions
+**
+** ^This interface causes the xEntryPoint() function to be invoked for
+** each new [database connection] that is created.  The idea here is that
+** xEntryPoint() is the entry point for a statically linked SQLite extension
+** that is to be automatically loaded into all new database connections.
+**
+** ^(Even though the function prototype shows that xEntryPoint() takes
+** no arguments and returns void, SQLite invokes xEntryPoint() with three
+** arguments and expects and integer result as if the signature of the
+** entry point where as follows:
+**
+** <blockquote><pre>
+** &nbsp;  int xEntryPoint(
+** &nbsp;    sqlite3 *db,
+** &nbsp;    const char **pzErrMsg,
+** &nbsp;    const struct sqlite3_api_routines *pThunk
+** &nbsp;  );
+** </pre></blockquote>)^
+**
+** If the xEntryPoint routine encounters an error, it should make *pzErrMsg
+** point to an appropriate error message (obtained from [sqlite3_mprintf()])
+** and return an appropriate [error code].  ^SQLite ensures that *pzErrMsg
+** is NULL before calling the xEntryPoint().  ^SQLite will invoke
+** [sqlite3_free()] on *pzErrMsg after xEntryPoint() returns.  ^If any
+** xEntryPoint() returns an error, the [sqlite3_open()], [sqlite3_open16()],
+** or [sqlite3_open_v2()] call that provoked the xEntryPoint() will fail.
+**
+** ^Calling sqlite3_auto_extension(X) with an entry point X that is already
+** on the list of automatic extensions is a harmless no-op. ^No entry point
+** will be called more than once for each database connection that is opened.
+**
+** See also: [sqlite3_reset_auto_extension()].
+*/
+SQLITE_API int sqlite3_auto_extension(void (*xEntryPoint)(void));
+
+/*
+** CAPI3REF: Reset Automatic Extension Loading
+**
+** ^This interface disables all automatic extensions previously
+** registered using [sqlite3_auto_extension()].
+*/
+SQLITE_API void sqlite3_reset_auto_extension(void);
+
+/*
+** The interface to the virtual-table mechanism is currently considered
+** to be experimental.  The interface might change in incompatible ways.
+** If this is a problem for you, do not use the interface at this time.
+**
+** When the virtual-table mechanism stabilizes, we will declare the
+** interface fixed, support it indefinitely, and remove this comment.
+*/
+
+/*
+** Structures used by the virtual table interface
+*/
+typedef struct sqlite3_vtab sqlite3_vtab;
+typedef struct sqlite3_index_info sqlite3_index_info;
+typedef struct sqlite3_vtab_cursor sqlite3_vtab_cursor;
+typedef struct sqlite3_module sqlite3_module;
+
+/*
+** CAPI3REF: Virtual Table Object
+** KEYWORDS: sqlite3_module {virtual table module}
+**
+** This structure, sometimes called a "virtual table module", 
+** defines the implementation of a [virtual tables].  
+** This structure consists mostly of methods for the module.
+**
+** ^A virtual table module is created by filling in a persistent
+** instance of this structure and passing a pointer to that instance
+** to [sqlite3_create_module()] or [sqlite3_create_module_v2()].
+** ^The registration remains valid until it is replaced by a different
+** module or until the [database connection] closes.  The content
+** of this structure must not change while it is registered with
+** any database connection.
+*/
+struct sqlite3_module {
+  int iVersion;
+  int (*xCreate)(sqlite3*, void *pAux,
+               int argc, const char *const*argv,
+               sqlite3_vtab **ppVTab, char**);
+  int (*xConnect)(sqlite3*, void *pAux,
+               int argc, const char *const*argv,
+               sqlite3_vtab **ppVTab, char**);
+  int (*xBestIndex)(sqlite3_vtab *pVTab, sqlite3_index_info*);
+  int (*xDisconnect)(sqlite3_vtab *pVTab);
+  int (*xDestroy)(sqlite3_vtab *pVTab);
+  int (*xOpen)(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor);
+  int (*xClose)(sqlite3_vtab_cursor*);
+  int (*xFilter)(sqlite3_vtab_cursor*, int idxNum, const char *idxStr,
+                int argc, sqlite3_value **argv);
+  int (*xNext)(sqlite3_vtab_cursor*);
+  int (*xEof)(sqlite3_vtab_cursor*);
+  int (*xColumn)(sqlite3_vtab_cursor*, sqlite3_context*, int);
+  int (*xRowid)(sqlite3_vtab_cursor*, sqlite3_int64 *pRowid);
+  int (*xUpdate)(sqlite3_vtab *, int, sqlite3_value **, sqlite3_int64 *);
+  int (*xBegin)(sqlite3_vtab *pVTab);
+  int (*xSync)(sqlite3_vtab *pVTab);
+  int (*xCommit)(sqlite3_vtab *pVTab);
+  int (*xRollback)(sqlite3_vtab *pVTab);
+  int (*xFindFunction)(sqlite3_vtab *pVtab, int nArg, const char *zName,
+                       void (**pxFunc)(sqlite3_context*,int,sqlite3_value**),
+                       void **ppArg);
+  int (*xRename)(sqlite3_vtab *pVtab, const char *zNew);
+};
+
+/*
+** CAPI3REF: Virtual Table Indexing Information
+** KEYWORDS: sqlite3_index_info
+**
+** The sqlite3_index_info structure and its substructures is used as part
+** of the [virtual table] interface to
+** pass information into and receive the reply from the [xBestIndex]
+** method of a [virtual table module].  The fields under **Inputs** are the
+** inputs to xBestIndex and are read-only.  xBestIndex inserts its
+** results into the **Outputs** fields.
+**
+** ^(The aConstraint[] array records WHERE clause constraints of the form:
+**
+** <blockquote>column OP expr</blockquote>
+**
+** where OP is =, &lt;, &lt;=, &gt;, or &gt;=.)^  ^(The particular operator is
+** stored in aConstraint[].op using one of the
+** [SQLITE_INDEX_CONSTRAINT_EQ | SQLITE_INDEX_CONSTRAINT_ values].)^
+** ^(The index of the column is stored in
+** aConstraint[].iColumn.)^  ^(aConstraint[].usable is TRUE if the
+** expr on the right-hand side can be evaluated (and thus the constraint
+** is usable) and false if it cannot.)^
+**
+** ^The optimizer automatically inverts terms of the form "expr OP column"
+** and makes other simplifications to the WHERE clause in an attempt to
+** get as many WHERE clause terms into the form shown above as possible.
+** ^The aConstraint[] array only reports WHERE clause terms that are
+** relevant to the particular virtual table being queried.
+**
+** ^Information about the ORDER BY clause is stored in aOrderBy[].
+** ^Each term of aOrderBy records a column of the ORDER BY clause.
+**
+** The [xBestIndex] method must fill aConstraintUsage[] with information
+** about what parameters to pass to xFilter.  ^If argvIndex>0 then
+** the right-hand side of the corresponding aConstraint[] is evaluated
+** and becomes the argvIndex-th entry in argv.  ^(If aConstraintUsage[].omit
+** is true, then the constraint is assumed to be fully handled by the
+** virtual table and is not checked again by SQLite.)^
+**
+** ^The idxNum and idxPtr values are recorded and passed into the
+** [xFilter] method.
+** ^[sqlite3_free()] is used to free idxPtr if and only if
+** needToFreeIdxPtr is true.
+**
+** ^The orderByConsumed means that output from [xFilter]/[xNext] will occur in
+** the correct order to satisfy the ORDER BY clause so that no separate
+** sorting step is required.
+**
+** ^The estimatedCost value is an estimate of the cost of doing the
+** particular lookup.  A full scan of a table with N entries should have
+** a cost of N.  A binary search of a table of N entries should have a
+** cost of approximately log(N).
+*/
+struct sqlite3_index_info {
+  /* Inputs */
+  int nConstraint;           /* Number of entries in aConstraint */
+  struct sqlite3_index_constraint {
+     int iColumn;              /* Column on left-hand side of constraint */
+     unsigned char op;         /* Constraint operator */
+     unsigned char usable;     /* True if this constraint is usable */
+     int iTermOffset;          /* Used internally - xBestIndex should ignore */
+  } *aConstraint;            /* Table of WHERE clause constraints */
+  int nOrderBy;              /* Number of terms in the ORDER BY clause */
+  struct sqlite3_index_orderby {
+     int iColumn;              /* Column number */
+     unsigned char desc;       /* True for DESC.  False for ASC. */
+  } *aOrderBy;               /* The ORDER BY clause */
+  /* Outputs */
+  struct sqlite3_index_constraint_usage {
+    int argvIndex;           /* if >0, constraint is part of argv to xFilter */
+    unsigned char omit;      /* Do not code a test for this constraint */
+  } *aConstraintUsage;
+  int idxNum;                /* Number used to identify the index */
+  char *idxStr;              /* String, possibly obtained from sqlite3_malloc */
+  int needToFreeIdxStr;      /* Free idxStr using sqlite3_free() if true */
+  int orderByConsumed;       /* True if output is already ordered */
+  double estimatedCost;      /* Estimated cost of using this index */
+};
+
+/*
+** CAPI3REF: Virtual Table Constraint Operator Codes
+**
+** These macros defined the allowed values for the
+** [sqlite3_index_info].aConstraint[].op field.  Each value represents
+** an operator that is part of a constraint term in the wHERE clause of
+** a query that uses a [virtual table].
+*/
+#define SQLITE_INDEX_CONSTRAINT_EQ    2
+#define SQLITE_INDEX_CONSTRAINT_GT    4
+#define SQLITE_INDEX_CONSTRAINT_LE    8
+#define SQLITE_INDEX_CONSTRAINT_LT    16
+#define SQLITE_INDEX_CONSTRAINT_GE    32
+#define SQLITE_INDEX_CONSTRAINT_MATCH 64
+
+/*
+** CAPI3REF: Register A Virtual Table Implementation
+**
+** ^These routines are used to register a new [virtual table module] name.
+** ^Module names must be registered before
+** creating a new [virtual table] using the module and before using a
+** preexisting [virtual table] for the module.
+**
+** ^The module name is registered on the [database connection] specified
+** by the first parameter.  ^The name of the module is given by the 
+** second parameter.  ^The third parameter is a pointer to
+** the implementation of the [virtual table module].   ^The fourth
+** parameter is an arbitrary client data pointer that is passed through
+** into the [xCreate] and [xConnect] methods of the virtual table module
+** when a new virtual table is be being created or reinitialized.
+**
+** ^The sqlite3_create_module_v2() interface has a fifth parameter which
+** is a pointer to a destructor for the pClientData.  ^SQLite will
+** invoke the destructor function (if it is not NULL) when SQLite
+** no longer needs the pClientData pointer.  ^The destructor will also
+** be invoked if the call to sqlite3_create_module_v2() fails.
+** ^The sqlite3_create_module()
+** interface is equivalent to sqlite3_create_module_v2() with a NULL
+** destructor.
+*/
+SQLITE_API int sqlite3_create_module(
+  sqlite3 *db,               /* SQLite connection to register module with */
+  const char *zName,         /* Name of the module */
+  const sqlite3_module *p,   /* Methods for the module */
+  void *pClientData          /* Client data for xCreate/xConnect */
+);
+SQLITE_API int sqlite3_create_module_v2(
+  sqlite3 *db,               /* SQLite connection to register module with */
+  const char *zName,         /* Name of the module */
+  const sqlite3_module *p,   /* Methods for the module */
+  void *pClientData,         /* Client data for xCreate/xConnect */
+  void(*xDestroy)(void*)     /* Module destructor function */
+);
+
+/*
+** CAPI3REF: Virtual Table Instance Object
+** KEYWORDS: sqlite3_vtab
+**
+** Every [virtual table module] implementation uses a subclass
+** of this object to describe a particular instance
+** of the [virtual table].  Each subclass will
+** be tailored to the specific needs of the module implementation.
+** The purpose of this superclass is to define certain fields that are
+** common to all module implementations.
+**
+** ^Virtual tables methods can set an error message by assigning a
+** string obtained from [sqlite3_mprintf()] to zErrMsg.  The method should
+** take care that any prior string is freed by a call to [sqlite3_free()]
+** prior to assigning a new string to zErrMsg.  ^After the error message
+** is delivered up to the client application, the string will be automatically
+** freed by sqlite3_free() and the zErrMsg field will be zeroed.
+*/
+struct sqlite3_vtab {
+  const sqlite3_module *pModule;  /* The module for this virtual table */
+  int nRef;                       /* NO LONGER USED */
+  char *zErrMsg;                  /* Error message from sqlite3_mprintf() */
+  /* Virtual table implementations will typically add additional fields */
+};
+
+/*
+** CAPI3REF: Virtual Table Cursor Object
+** KEYWORDS: sqlite3_vtab_cursor {virtual table cursor}
+**
+** Every [virtual table module] implementation uses a subclass of the
+** following structure to describe cursors that point into the
+** [virtual table] and are used
+** to loop through the virtual table.  Cursors are created using the
+** [sqlite3_module.xOpen | xOpen] method of the module and are destroyed
+** by the [sqlite3_module.xClose | xClose] method.  Cursors are used
+** by the [xFilter], [xNext], [xEof], [xColumn], and [xRowid] methods
+** of the module.  Each module implementation will define
+** the content of a cursor structure to suit its own needs.
+**
+** This superclass exists in order to define fields of the cursor that
+** are common to all implementations.
+*/
+struct sqlite3_vtab_cursor {
+  sqlite3_vtab *pVtab;      /* Virtual table of this cursor */
+  /* Virtual table implementations will typically add additional fields */
+};
+
+/*
+** CAPI3REF: Declare The Schema Of A Virtual Table
+**
+** ^The [xCreate] and [xConnect] methods of a
+** [virtual table module] call this interface
+** to declare the format (the names and datatypes of the columns) of
+** the virtual tables they implement.
+*/
+SQLITE_API int sqlite3_declare_vtab(sqlite3*, const char *zSQL);
+
+/*
+** CAPI3REF: Overload A Function For A Virtual Table
+**
+** ^(Virtual tables can provide alternative implementations of functions
+** using the [xFindFunction] method of the [virtual table module].  
+** But global versions of those functions
+** must exist in order to be overloaded.)^
+**
+** ^(This API makes sure a global version of a function with a particular
+** name and number of parameters exists.  If no such function exists
+** before this API is called, a new function is created.)^  ^The implementation
+** of the new function always causes an exception to be thrown.  So
+** the new function is not good for anything by itself.  Its only
+** purpose is to be a placeholder function that can be overloaded
+** by a [virtual table].
+*/
+SQLITE_API int sqlite3_overload_function(sqlite3*, const char *zFuncName, int nArg);
+
+/*
+** The interface to the virtual-table mechanism defined above (back up
+** to a comment remarkably similar to this one) is currently considered
+** to be experimental.  The interface might change in incompatible ways.
+** If this is a problem for you, do not use the interface at this time.
+**
+** When the virtual-table mechanism stabilizes, we will declare the
+** interface fixed, support it indefinitely, and remove this comment.
+*/
+
+/*
+** CAPI3REF: A Handle To An Open BLOB
+** KEYWORDS: {BLOB handle} {BLOB handles}
+**
+** An instance of this object represents an open BLOB on which
+** [sqlite3_blob_open | incremental BLOB I/O] can be performed.
+** ^Objects of this type are created by [sqlite3_blob_open()]
+** and destroyed by [sqlite3_blob_close()].
+** ^The [sqlite3_blob_read()] and [sqlite3_blob_write()] interfaces
+** can be used to read or write small subsections of the BLOB.
+** ^The [sqlite3_blob_bytes()] interface returns the size of the BLOB in bytes.
+*/
+typedef struct sqlite3_blob sqlite3_blob;
+
+/*
+** CAPI3REF: Open A BLOB For Incremental I/O
+**
+** ^(This interfaces opens a [BLOB handle | handle] to the BLOB located
+** in row iRow, column zColumn, table zTable in database zDb;
+** in other words, the same BLOB that would be selected by:
+**
+** <pre>
+**     SELECT zColumn FROM zDb.zTable WHERE [rowid] = iRow;
+** </pre>)^
+**
+** ^If the flags parameter is non-zero, then the BLOB is opened for read
+** and write access. ^If it is zero, the BLOB is opened for read access.
+** ^It is not possible to open a column that is part of an index or primary 
+** key for writing. ^If [foreign key constraints] are enabled, it is 
+** not possible to open a column that is part of a [child key] for writing.
+**
+** ^Note that the database name is not the filename that contains
+** the database but rather the symbolic name of the database that
+** appears after the AS keyword when the database is connected using [ATTACH].
+** ^For the main database file, the database name is "main".
+** ^For TEMP tables, the database name is "temp".
+**
+** ^(On success, [SQLITE_OK] is returned and the new [BLOB handle] is written
+** to *ppBlob. Otherwise an [error code] is returned and *ppBlob is set
+** to be a null pointer.)^
+** ^This function sets the [database connection] error code and message
+** accessible via [sqlite3_errcode()] and [sqlite3_errmsg()] and related
+** functions. ^Note that the *ppBlob variable is always initialized in a
+** way that makes it safe to invoke [sqlite3_blob_close()] on *ppBlob
+** regardless of the success or failure of this routine.
+**
+** ^(If the row that a BLOB handle points to is modified by an
+** [UPDATE], [DELETE], or by [ON CONFLICT] side-effects
+** then the BLOB handle is marked as "expired".
+** This is true if any column of the row is changed, even a column
+** other than the one the BLOB handle is open on.)^
+** ^Calls to [sqlite3_blob_read()] and [sqlite3_blob_write()] for
+** an expired BLOB handle fail with a return code of [SQLITE_ABORT].
+** ^(Changes written into a BLOB prior to the BLOB expiring are not
+** rolled back by the expiration of the BLOB.  Such changes will eventually
+** commit if the transaction continues to completion.)^
+**
+** ^Use the [sqlite3_blob_bytes()] interface to determine the size of
+** the opened blob.  ^The size of a blob may not be changed by this
+** interface.  Use the [UPDATE] SQL command to change the size of a
+** blob.
+**
+** ^The [sqlite3_bind_zeroblob()] and [sqlite3_result_zeroblob()] interfaces
+** and the built-in [zeroblob] SQL function can be used, if desired,
+** to create an empty, zero-filled blob in which to read or write using
+** this interface.
+**
+** To avoid a resource leak, every open [BLOB handle] should eventually
+** be released by a call to [sqlite3_blob_close()].
+*/
+SQLITE_API int sqlite3_blob_open(
+  sqlite3*,
+  const char *zDb,
+  const char *zTable,
+  const char *zColumn,
+  sqlite3_int64 iRow,
+  int flags,
+  sqlite3_blob **ppBlob
+);
+
+/*
+** CAPI3REF: Move a BLOB Handle to a New Row
+**
+** ^This function is used to move an existing blob handle so that it points
+** to a different row of the same database table. ^The new row is identified
+** by the rowid value passed as the second argument. Only the row can be
+** changed. ^The database, table and column on which the blob handle is open
+** remain the same. Moving an existing blob handle to a new row can be
+** faster than closing the existing handle and opening a new one.
+**
+** ^(The new row must meet the same criteria as for [sqlite3_blob_open()] -
+** it must exist and there must be either a blob or text value stored in
+** the nominated column.)^ ^If the new row is not present in the table, or if
+** it does not contain a blob or text value, or if another error occurs, an
+** SQLite error code is returned and the blob handle is considered aborted.
+** ^All subsequent calls to [sqlite3_blob_read()], [sqlite3_blob_write()] or
+** [sqlite3_blob_reopen()] on an aborted blob handle immediately return
+** SQLITE_ABORT. ^Calling [sqlite3_blob_bytes()] on an aborted blob handle
+** always returns zero.
+**
+** ^This function sets the database handle error code and message.
+*/
+SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_blob_reopen(sqlite3_blob *, sqlite3_int64);
+
+/*
+** CAPI3REF: Close A BLOB Handle
+**
+** ^Closes an open [BLOB handle].
+**
+** ^Closing a BLOB shall cause the current transaction to commit
+** if there are no other BLOBs, no pending prepared statements, and the
+** database connection is in [autocommit mode].
+** ^If any writes were made to the BLOB, they might be held in cache
+** until the close operation if they will fit.
+**
+** ^(Closing the BLOB often forces the changes
+** out to disk and so if any I/O errors occur, they will likely occur
+** at the time when the BLOB is closed.  Any errors that occur during
+** closing are reported as a non-zero return value.)^
+**
+** ^(The BLOB is closed unconditionally.  Even if this routine returns
+** an error code, the BLOB is still closed.)^
+**
+** ^Calling this routine with a null pointer (such as would be returned
+** by a failed call to [sqlite3_blob_open()]) is a harmless no-op.
+*/
+SQLITE_API int sqlite3_blob_close(sqlite3_blob *);
+
+/*
+** CAPI3REF: Return The Size Of An Open BLOB
+**
+** ^Returns the size in bytes of the BLOB accessible via the 
+** successfully opened [BLOB handle] in its only argument.  ^The
+** incremental blob I/O routines can only read or overwriting existing
+** blob content; they cannot change the size of a blob.
+**
+** This routine only works on a [BLOB handle] which has been created
+** by a prior successful call to [sqlite3_blob_open()] and which has not
+** been closed by [sqlite3_blob_close()].  Passing any other pointer in
+** to this routine results in undefined and probably undesirable behavior.
+*/
+SQLITE_API int sqlite3_blob_bytes(sqlite3_blob *);
+
+/*
+** CAPI3REF: Read Data From A BLOB Incrementally
+**
+** ^(This function is used to read data from an open [BLOB handle] into a
+** caller-supplied buffer. N bytes of data are copied into buffer Z
+** from the open BLOB, starting at offset iOffset.)^
+**
+** ^If offset iOffset is less than N bytes from the end of the BLOB,
+** [SQLITE_ERROR] is returned and no data is read.  ^If N or iOffset is
+** less than zero, [SQLITE_ERROR] is returned and no data is read.
+** ^The size of the blob (and hence the maximum value of N+iOffset)
+** can be determined using the [sqlite3_blob_bytes()] interface.
+**
+** ^An attempt to read from an expired [BLOB handle] fails with an
+** error code of [SQLITE_ABORT].
+**
+** ^(On success, sqlite3_blob_read() returns SQLITE_OK.
+** Otherwise, an [error code] or an [extended error code] is returned.)^
+**
+** This routine only works on a [BLOB handle] which has been created
+** by a prior successful call to [sqlite3_blob_open()] and which has not
+** been closed by [sqlite3_blob_close()].  Passing any other pointer in
+** to this routine results in undefined and probably undesirable behavior.
+**
+** See also: [sqlite3_blob_write()].
+*/
+SQLITE_API int sqlite3_blob_read(sqlite3_blob *, void *Z, int N, int iOffset);
+
+/*
+** CAPI3REF: Write Data Into A BLOB Incrementally
+**
+** ^This function is used to write data into an open [BLOB handle] from a
+** caller-supplied buffer. ^N bytes of data are copied from the buffer Z
+** into the open BLOB, starting at offset iOffset.
+**
+** ^If the [BLOB handle] passed as the first argument was not opened for
+** writing (the flags parameter to [sqlite3_blob_open()] was zero),
+** this function returns [SQLITE_READONLY].
+**
+** ^This function may only modify the contents of the BLOB; it is
+** not possible to increase the size of a BLOB using this API.
+** ^If offset iOffset is less than N bytes from the end of the BLOB,
+** [SQLITE_ERROR] is returned and no data is written.  ^If N is
+** less than zero [SQLITE_ERROR] is returned and no data is written.
+** The size of the BLOB (and hence the maximum value of N+iOffset)
+** can be determined using the [sqlite3_blob_bytes()] interface.
+**
+** ^An attempt to write to an expired [BLOB handle] fails with an
+** error code of [SQLITE_ABORT].  ^Writes to the BLOB that occurred
+** before the [BLOB handle] expired are not rolled back by the
+** expiration of the handle, though of course those changes might
+** have been overwritten by the statement that expired the BLOB handle
+** or by other independent statements.
+**
+** ^(On success, sqlite3_blob_write() returns SQLITE_OK.
+** Otherwise, an  [error code] or an [extended error code] is returned.)^
+**
+** This routine only works on a [BLOB handle] which has been created
+** by a prior successful call to [sqlite3_blob_open()] and which has not
+** been closed by [sqlite3_blob_close()].  Passing any other pointer in
+** to this routine results in undefined and probably undesirable behavior.
+**
+** See also: [sqlite3_blob_read()].
+*/
+SQLITE_API int sqlite3_blob_write(sqlite3_blob *, const void *z, int n, int iOffset);
+
+/*
+** CAPI3REF: Virtual File System Objects
+**
+** A virtual filesystem (VFS) is an [sqlite3_vfs] object
+** that SQLite uses to interact
+** with the underlying operating system.  Most SQLite builds come with a
+** single default VFS that is appropriate for the host computer.
+** New VFSes can be registered and existing VFSes can be unregistered.
+** The following interfaces are provided.
+**
+** ^The sqlite3_vfs_find() interface returns a pointer to a VFS given its name.
+** ^Names are case sensitive.
+** ^Names are zero-terminated UTF-8 strings.
+** ^If there is no match, a NULL pointer is returned.
+** ^If zVfsName is NULL then the default VFS is returned.
+**
+** ^New VFSes are registered with sqlite3_vfs_register().
+** ^Each new VFS becomes the default VFS if the makeDflt flag is set.
+** ^The same VFS can be registered multiple times without injury.
+** ^To make an existing VFS into the default VFS, register it again
+** with the makeDflt flag set.  If two different VFSes with the
+** same name are registered, the behavior is undefined.  If a
+** VFS is registered with a name that is NULL or an empty string,
+** then the behavior is undefined.
+**
+** ^Unregister a VFS with the sqlite3_vfs_unregister() interface.
+** ^(If the default VFS is unregistered, another VFS is chosen as
+** the default.  The choice for the new VFS is arbitrary.)^
+*/
+SQLITE_API sqlite3_vfs *sqlite3_vfs_find(const char *zVfsName);
+SQLITE_API int sqlite3_vfs_register(sqlite3_vfs*, int makeDflt);
+SQLITE_API int sqlite3_vfs_unregister(sqlite3_vfs*);
+
+/*
+** CAPI3REF: Mutexes
+**
+** The SQLite core uses these routines for thread
+** synchronization. Though they are intended for internal
+** use by SQLite, code that links against SQLite is
+** permitted to use any of these routines.
+**
+** The SQLite source code contains multiple implementations
+** of these mutex routines.  An appropriate implementation
+** is selected automatically at compile-time.  ^(The following
+** implementations are available in the SQLite core:
+**
+** <ul>
+** <li>   SQLITE_MUTEX_OS2
+** <li>   SQLITE_MUTEX_PTHREAD
+** <li>   SQLITE_MUTEX_W32
+** <li>   SQLITE_MUTEX_NOOP
+** </ul>)^
+**
+** ^The SQLITE_MUTEX_NOOP implementation is a set of routines
+** that does no real locking and is appropriate for use in
+** a single-threaded application.  ^The SQLITE_MUTEX_OS2,
+** SQLITE_MUTEX_PTHREAD, and SQLITE_MUTEX_W32 implementations
+** are appropriate for use on OS/2, Unix, and Windows.
+**
+** ^(If SQLite is compiled with the SQLITE_MUTEX_APPDEF preprocessor
+** macro defined (with "-DSQLITE_MUTEX_APPDEF=1"), then no mutex
+** implementation is included with the library. In this case the
+** application must supply a custom mutex implementation using the
+** [SQLITE_CONFIG_MUTEX] option of the sqlite3_config() function
+** before calling sqlite3_initialize() or any other public sqlite3_
+** function that calls sqlite3_initialize().)^
+**
+** ^The sqlite3_mutex_alloc() routine allocates a new
+** mutex and returns a pointer to it. ^If it returns NULL
+** that means that a mutex could not be allocated.  ^SQLite
+** will unwind its stack and return an error.  ^(The argument
+** to sqlite3_mutex_alloc() is one of these integer constants:
+**
+** <ul>
+** <li>  SQLITE_MUTEX_FAST
+** <li>  SQLITE_MUTEX_RECURSIVE
+** <li>  SQLITE_MUTEX_STATIC_MASTER
+** <li>  SQLITE_MUTEX_STATIC_MEM
+** <li>  SQLITE_MUTEX_STATIC_MEM2
+** <li>  SQLITE_MUTEX_STATIC_PRNG
+** <li>  SQLITE_MUTEX_STATIC_LRU
+** <li>  SQLITE_MUTEX_STATIC_LRU2
+** </ul>)^
+**
+** ^The first two constants (SQLITE_MUTEX_FAST and SQLITE_MUTEX_RECURSIVE)
+** cause sqlite3_mutex_alloc() to create
+** a new mutex.  ^The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
+** is used but not necessarily so when SQLITE_MUTEX_FAST is used.
+** The mutex implementation does not need to make a distinction
+** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does
+** not want to.  ^SQLite will only request a recursive mutex in
+** cases where it really needs one.  ^If a faster non-recursive mutex
+** implementation is available on the host platform, the mutex subsystem
+** might return such a mutex in response to SQLITE_MUTEX_FAST.
+**
+** ^The other allowed parameters to sqlite3_mutex_alloc() (anything other
+** than SQLITE_MUTEX_FAST and SQLITE_MUTEX_RECURSIVE) each return
+** a pointer to a static preexisting mutex.  ^Six static mutexes are
+** used by the current version of SQLite.  Future versions of SQLite
+** may add additional static mutexes.  Static mutexes are for internal
+** use by SQLite only.  Applications that use SQLite mutexes should
+** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or
+** SQLITE_MUTEX_RECURSIVE.
+**
+** ^Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST
+** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc()
+** returns a different mutex on every call.  ^But for the static
+** mutex types, the same mutex is returned on every call that has
+** the same type number.
+**
+** ^The sqlite3_mutex_free() routine deallocates a previously
+** allocated dynamic mutex.  ^SQLite is careful to deallocate every
+** dynamic mutex that it allocates.  The dynamic mutexes must not be in
+** use when they are deallocated.  Attempting to deallocate a static
+** mutex results in undefined behavior.  ^SQLite never deallocates
+** a static mutex.
+**
+** ^The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
+** to enter a mutex.  ^If another thread is already within the mutex,
+** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
+** SQLITE_BUSY.  ^The sqlite3_mutex_try() interface returns [SQLITE_OK]
+** upon successful entry.  ^(Mutexes created using
+** SQLITE_MUTEX_RECURSIVE can be entered multiple times by the same thread.
+** In such cases the,
+** mutex must be exited an equal number of times before another thread
+** can enter.)^  ^(If the same thread tries to enter any other
+** kind of mutex more than once, the behavior is undefined.
+** SQLite will never exhibit
+** such behavior in its own use of mutexes.)^
+**
+** ^(Some systems (for example, Windows 95) do not support the operation
+** implemented by sqlite3_mutex_try().  On those systems, sqlite3_mutex_try()
+** will always return SQLITE_BUSY.  The SQLite core only ever uses
+** sqlite3_mutex_try() as an optimization so this is acceptable behavior.)^
+**
+** ^The sqlite3_mutex_leave() routine exits a mutex that was
+** previously entered by the same thread.   ^(The behavior
+** is undefined if the mutex is not currently entered by the
+** calling thread or is not currently allocated.  SQLite will
+** never do either.)^
+**
+** ^If the argument to sqlite3_mutex_enter(), sqlite3_mutex_try(), or
+** sqlite3_mutex_leave() is a NULL pointer, then all three routines
+** behave as no-ops.
+**
+** See also: [sqlite3_mutex_held()] and [sqlite3_mutex_notheld()].
+*/
+SQLITE_API sqlite3_mutex *sqlite3_mutex_alloc(int);
+SQLITE_API void sqlite3_mutex_free(sqlite3_mutex*);
+SQLITE_API void sqlite3_mutex_enter(sqlite3_mutex*);
+SQLITE_API int sqlite3_mutex_try(sqlite3_mutex*);
+SQLITE_API void sqlite3_mutex_leave(sqlite3_mutex*);
+
+/*
+** CAPI3REF: Mutex Methods Object
+**
+** An instance of this structure defines the low-level routines
+** used to allocate and use mutexes.
+**
+** Usually, the default mutex implementations provided by SQLite are
+** sufficient, however the user has the option of substituting a custom
+** implementation for specialized deployments or systems for which SQLite
+** does not provide a suitable implementation. In this case, the user
+** creates and populates an instance of this structure to pass
+** to sqlite3_config() along with the [SQLITE_CONFIG_MUTEX] option.
+** Additionally, an instance of this structure can be used as an
+** output variable when querying the system for the current mutex
+** implementation, using the [SQLITE_CONFIG_GETMUTEX] option.
+**
+** ^The xMutexInit method defined by this structure is invoked as
+** part of system initialization by the sqlite3_initialize() function.
+** ^The xMutexInit routine is called by SQLite exactly once for each
+** effective call to [sqlite3_initialize()].
+**
+** ^The xMutexEnd method defined by this structure is invoked as
+** part of system shutdown by the sqlite3_shutdown() function. The
+** implementation of this method is expected to release all outstanding
+** resources obtained by the mutex methods implementation, especially
+** those obtained by the xMutexInit method.  ^The xMutexEnd()
+** interface is invoked exactly once for each call to [sqlite3_shutdown()].
+**
+** ^(The remaining seven methods defined by this structure (xMutexAlloc,
+** xMutexFree, xMutexEnter, xMutexTry, xMutexLeave, xMutexHeld and
+** xMutexNotheld) implement the following interfaces (respectively):
+**
+** <ul>
+**   <li>  [sqlite3_mutex_alloc()] </li>
+**   <li>  [sqlite3_mutex_free()] </li>
+**   <li>  [sqlite3_mutex_enter()] </li>
+**   <li>  [sqlite3_mutex_try()] </li>
+**   <li>  [sqlite3_mutex_leave()] </li>
+**   <li>  [sqlite3_mutex_held()] </li>
+**   <li>  [sqlite3_mutex_notheld()] </li>
+** </ul>)^
+**
+** The only difference is that the public sqlite3_XXX functions enumerated
+** above silently ignore any invocations that pass a NULL pointer instead
+** of a valid mutex handle. The implementations of the methods defined
+** by this structure are not required to handle this case, the results
+** of passing a NULL pointer instead of a valid mutex handle are undefined
+** (i.e. it is acceptable to provide an implementation that segfaults if
+** it is passed a NULL pointer).
+**
+** The xMutexInit() method must be threadsafe.  ^It must be harmless to
+** invoke xMutexInit() multiple times within the same process and without
+** intervening calls to xMutexEnd().  Second and subsequent calls to
+** xMutexInit() must be no-ops.
+**
+** ^xMutexInit() must not use SQLite memory allocation ([sqlite3_malloc()]
+** and its associates).  ^Similarly, xMutexAlloc() must not use SQLite memory
+** allocation for a static mutex.  ^However xMutexAlloc() may use SQLite
+** memory allocation for a fast or recursive mutex.
+**
+** ^SQLite will invoke the xMutexEnd() method when [sqlite3_shutdown()] is
+** called, but only if the prior call to xMutexInit returned SQLITE_OK.
+** If xMutexInit fails in any way, it is expected to clean up after itself
+** prior to returning.
+*/
+typedef struct sqlite3_mutex_methods sqlite3_mutex_methods;
+struct sqlite3_mutex_methods {
+  int (*xMutexInit)(void);
+  int (*xMutexEnd)(void);
+  sqlite3_mutex *(*xMutexAlloc)(int);
+  void (*xMutexFree)(sqlite3_mutex *);
+  void (*xMutexEnter)(sqlite3_mutex *);
+  int (*xMutexTry)(sqlite3_mutex *);
+  void (*xMutexLeave)(sqlite3_mutex *);
+  int (*xMutexHeld)(sqlite3_mutex *);
+  int (*xMutexNotheld)(sqlite3_mutex *);
+};
+
+/*
+** CAPI3REF: Mutex Verification Routines
+**
+** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routines
+** are intended for use inside assert() statements.  ^The SQLite core
+** never uses these routines except inside an assert() and applications
+** are advised to follow the lead of the core.  ^The SQLite core only
+** provides implementations for these routines when it is compiled
+** with the SQLITE_DEBUG flag.  ^External mutex implementations
+** are only required to provide these routines if SQLITE_DEBUG is
+** defined and if NDEBUG is not defined.
+**
+** ^These routines should return true if the mutex in their argument
+** is held or not held, respectively, by the calling thread.
+**
+** ^The implementation is not required to provided versions of these
+** routines that actually work. If the implementation does not provide working
+** versions of these routines, it should at least provide stubs that always
+** return true so that one does not get spurious assertion failures.
+**
+** ^If the argument to sqlite3_mutex_held() is a NULL pointer then
+** the routine should return 1.   This seems counter-intuitive since
+** clearly the mutex cannot be held if it does not exist.  But the
+** the reason the mutex does not exist is because the build is not
+** using mutexes.  And we do not want the assert() containing the
+** call to sqlite3_mutex_held() to fail, so a non-zero return is
+** the appropriate thing to do.  ^The sqlite3_mutex_notheld()
+** interface should also return 1 when given a NULL pointer.
+*/
+#ifndef NDEBUG
+SQLITE_API int sqlite3_mutex_held(sqlite3_mutex*);
+SQLITE_API int sqlite3_mutex_notheld(sqlite3_mutex*);
+#endif
+
+/*
+** CAPI3REF: Mutex Types
+**
+** The [sqlite3_mutex_alloc()] interface takes a single argument
+** which is one of these integer constants.
+**
+** The set of static mutexes may change from one SQLite release to the
+** next.  Applications that override the built-in mutex logic must be
+** prepared to accommodate additional static mutexes.
+*/
+#define SQLITE_MUTEX_FAST             0
+#define SQLITE_MUTEX_RECURSIVE        1
+#define SQLITE_MUTEX_STATIC_MASTER    2
+#define SQLITE_MUTEX_STATIC_MEM       3  /* sqlite3_malloc() */
+#define SQLITE_MUTEX_STATIC_MEM2      4  /* NOT USED */
+#define SQLITE_MUTEX_STATIC_OPEN      4  /* sqlite3BtreeOpen() */
+#define SQLITE_MUTEX_STATIC_PRNG      5  /* sqlite3_random() */
+#define SQLITE_MUTEX_STATIC_LRU       6  /* lru page list */
+#define SQLITE_MUTEX_STATIC_LRU2      7  /* NOT USED */
+#define SQLITE_MUTEX_STATIC_PMEM      7  /* sqlite3PageMalloc() */
+
+/*
+** CAPI3REF: Retrieve the mutex for a database connection
+**
+** ^This interface returns a pointer the [sqlite3_mutex] object that 
+** serializes access to the [database connection] given in the argument
+** when the [threading mode] is Serialized.
+** ^If the [threading mode] is Single-thread or Multi-thread then this
+** routine returns a NULL pointer.
+*/
+SQLITE_API sqlite3_mutex *sqlite3_db_mutex(sqlite3*);
+
+/*
+** CAPI3REF: Low-Level Control Of Database Files
+**
+** ^The [sqlite3_file_control()] interface makes a direct call to the
+** xFileControl method for the [sqlite3_io_methods] object associated
+** with a particular database identified by the second argument. ^The
+** name of the database is "main" for the main database or "temp" for the
+** TEMP database, or the name that appears after the AS keyword for
+** databases that are added using the [ATTACH] SQL command.
+** ^A NULL pointer can be used in place of "main" to refer to the
+** main database file.
+** ^The third and fourth parameters to this routine
+** are passed directly through to the second and third parameters of
+** the xFileControl method.  ^The return value of the xFileControl
+** method becomes the return value of this routine.
+**
+** ^The SQLITE_FCNTL_FILE_POINTER value for the op parameter causes
+** a pointer to the underlying [sqlite3_file] object to be written into
+** the space pointed to by the 4th parameter.  ^The SQLITE_FCNTL_FILE_POINTER
+** case is a short-circuit path which does not actually invoke the
+** underlying sqlite3_io_methods.xFileControl method.
+**
+** ^If the second parameter (zDbName) does not match the name of any
+** open database file, then SQLITE_ERROR is returned.  ^This error
+** code is not remembered and will not be recalled by [sqlite3_errcode()]
+** or [sqlite3_errmsg()].  The underlying xFileControl method might
+** also return SQLITE_ERROR.  There is no way to distinguish between
+** an incorrect zDbName and an SQLITE_ERROR return from the underlying
+** xFileControl method.
+**
+** See also: [SQLITE_FCNTL_LOCKSTATE]
+*/
+SQLITE_API int sqlite3_file_control(sqlite3*, const char *zDbName, int op, void*);
+
+/*
+** CAPI3REF: Testing Interface
+**
+** ^The sqlite3_test_control() interface is used to read out internal
+** state of SQLite and to inject faults into SQLite for testing
+** purposes.  ^The first parameter is an operation code that determines
+** the number, meaning, and operation of all subsequent parameters.
+**
+** This interface is not for use by applications.  It exists solely
+** for verifying the correct operation of the SQLite library.  Depending
+** on how the SQLite library is compiled, this interface might not exist.
+**
+** The details of the operation codes, their meanings, the parameters
+** they take, and what they do are all subject to change without notice.
+** Unlike most of the SQLite API, this function is not guaranteed to
+** operate consistently from one release to the next.
+*/
+SQLITE_API int sqlite3_test_control(int op, ...);
+
+/*
+** CAPI3REF: Testing Interface Operation Codes
+**
+** These constants are the valid operation code parameters used
+** as the first argument to [sqlite3_test_control()].
+**
+** These parameters and their meanings are subject to change
+** without notice.  These values are for testing purposes only.
+** Applications should not use any of these parameters or the
+** [sqlite3_test_control()] interface.
+*/
+#define SQLITE_TESTCTRL_FIRST                    5
+#define SQLITE_TESTCTRL_PRNG_SAVE                5
+#define SQLITE_TESTCTRL_PRNG_RESTORE             6
+#define SQLITE_TESTCTRL_PRNG_RESET               7
+#define SQLITE_TESTCTRL_BITVEC_TEST              8
+#define SQLITE_TESTCTRL_FAULT_INSTALL            9
+#define SQLITE_TESTCTRL_BENIGN_MALLOC_HOOKS     10
+#define SQLITE_TESTCTRL_PENDING_BYTE            11
+#define SQLITE_TESTCTRL_ASSERT                  12
+#define SQLITE_TESTCTRL_ALWAYS                  13
+#define SQLITE_TESTCTRL_RESERVE                 14
+#define SQLITE_TESTCTRL_OPTIMIZATIONS           15
+#define SQLITE_TESTCTRL_ISKEYWORD               16
+#define SQLITE_TESTCTRL_PGHDRSZ                 17
+#define SQLITE_TESTCTRL_SCRATCHMALLOC           18
+#define SQLITE_TESTCTRL_LAST                    18
+
+/*
+** CAPI3REF: SQLite Runtime Status
+**
+** ^This interface is used to retrieve runtime status information
+** about the performance of SQLite, and optionally to reset various
+** highwater marks.  ^The first argument is an integer code for
+** the specific parameter to measure.  ^(Recognized integer codes
+** are of the form [SQLITE_STATUS_MEMORY_USED | SQLITE_STATUS_...].)^
+** ^The current value of the parameter is returned into *pCurrent.
+** ^The highest recorded value is returned in *pHighwater.  ^If the
+** resetFlag is true, then the highest record value is reset after
+** *pHighwater is written.  ^(Some parameters do not record the highest
+** value.  For those parameters
+** nothing is written into *pHighwater and the resetFlag is ignored.)^
+** ^(Other parameters record only the highwater mark and not the current
+** value.  For these latter parameters nothing is written into *pCurrent.)^
+**
+** ^The sqlite3_status() routine returns SQLITE_OK on success and a
+** non-zero [error code] on failure.
+**
+** This routine is threadsafe but is not atomic.  This routine can be
+** called while other threads are running the same or different SQLite
+** interfaces.  However the values returned in *pCurrent and
+** *pHighwater reflect the status of SQLite at different points in time
+** and it is possible that another thread might change the parameter
+** in between the times when *pCurrent and *pHighwater are written.
+**
+** See also: [sqlite3_db_status()]
+*/
+SQLITE_API int sqlite3_status(int op, int *pCurrent, int *pHighwater, int resetFlag);
+
+
+/*
+** CAPI3REF: Status Parameters
+**
+** These integer constants designate various run-time status parameters
+** that can be returned by [sqlite3_status()].
+**
+** <dl>
+** ^(<dt>SQLITE_STATUS_MEMORY_USED</dt>
+** <dd>This parameter is the current amount of memory checked out
+** using [sqlite3_malloc()], either directly or indirectly.  The
+** figure includes calls made to [sqlite3_malloc()] by the application
+** and internal memory usage by the SQLite library.  Scratch memory
+** controlled by [SQLITE_CONFIG_SCRATCH] and auxiliary page-cache
+** memory controlled by [SQLITE_CONFIG_PAGECACHE] is not included in
+** this parameter.  The amount returned is the sum of the allocation
+** sizes as reported by the xSize method in [sqlite3_mem_methods].</dd>)^
+**
+** ^(<dt>SQLITE_STATUS_MALLOC_SIZE</dt>
+** <dd>This parameter records the largest memory allocation request
+** handed to [sqlite3_malloc()] or [sqlite3_realloc()] (or their
+** internal equivalents).  Only the value returned in the
+** *pHighwater parameter to [sqlite3_status()] is of interest.  
+** The value written into the *pCurrent parameter is undefined.</dd>)^
+**
+** ^(<dt>SQLITE_STATUS_MALLOC_COUNT</dt>
+** <dd>This parameter records the number of separate memory allocations
+** currently checked out.</dd>)^
+**
+** ^(<dt>SQLITE_STATUS_PAGECACHE_USED</dt>
+** <dd>This parameter returns the number of pages used out of the
+** [pagecache memory allocator] that was configured using 
+** [SQLITE_CONFIG_PAGECACHE].  The
+** value returned is in pages, not in bytes.</dd>)^
+**
+** ^(<dt>SQLITE_STATUS_PAGECACHE_OVERFLOW</dt>
+** <dd>This parameter returns the number of bytes of page cache
+** allocation which could not be satisfied by the [SQLITE_CONFIG_PAGECACHE]
+** buffer and where forced to overflow to [sqlite3_malloc()].  The
+** returned value includes allocations that overflowed because they
+** where too large (they were larger than the "sz" parameter to
+** [SQLITE_CONFIG_PAGECACHE]) and allocations that overflowed because
+** no space was left in the page cache.</dd>)^
+**
+** ^(<dt>SQLITE_STATUS_PAGECACHE_SIZE</dt>
+** <dd>This parameter records the largest memory allocation request
+** handed to [pagecache memory allocator].  Only the value returned in the
+** *pHighwater parameter to [sqlite3_status()] is of interest.  
+** The value written into the *pCurrent parameter is undefined.</dd>)^
+**
+** ^(<dt>SQLITE_STATUS_SCRATCH_USED</dt>
+** <dd>This parameter returns the number of allocations used out of the
+** [scratch memory allocator] configured using
+** [SQLITE_CONFIG_SCRATCH].  The value returned is in allocations, not
+** in bytes.  Since a single thread may only have one scratch allocation
+** outstanding at time, this parameter also reports the number of threads
+** using scratch memory at the same time.</dd>)^
+**
+** ^(<dt>SQLITE_STATUS_SCRATCH_OVERFLOW</dt>
+** <dd>This parameter returns the number of bytes of scratch memory
+** allocation which could not be satisfied by the [SQLITE_CONFIG_SCRATCH]
+** buffer and where forced to overflow to [sqlite3_malloc()].  The values
+** returned include overflows because the requested allocation was too
+** larger (that is, because the requested allocation was larger than the
+** "sz" parameter to [SQLITE_CONFIG_SCRATCH]) and because no scratch buffer
+** slots were available.
+** </dd>)^
+**
+** ^(<dt>SQLITE_STATUS_SCRATCH_SIZE</dt>
+** <dd>This parameter records the largest memory allocation request
+** handed to [scratch memory allocator].  Only the value returned in the
+** *pHighwater parameter to [sqlite3_status()] is of interest.  
+** The value written into the *pCurrent parameter is undefined.</dd>)^
+**
+** ^(<dt>SQLITE_STATUS_PARSER_STACK</dt>
+** <dd>This parameter records the deepest parser stack.  It is only
+** meaningful if SQLite is compiled with [YYTRACKMAXSTACKDEPTH].</dd>)^
+** </dl>
+**
+** New status parameters may be added from time to time.
+*/
+#define SQLITE_STATUS_MEMORY_USED          0
+#define SQLITE_STATUS_PAGECACHE_USED       1
+#define SQLITE_STATUS_PAGECACHE_OVERFLOW   2
+#define SQLITE_STATUS_SCRATCH_USED         3
+#define SQLITE_STATUS_SCRATCH_OVERFLOW     4
+#define SQLITE_STATUS_MALLOC_SIZE          5
+#define SQLITE_STATUS_PARSER_STACK         6
+#define SQLITE_STATUS_PAGECACHE_SIZE       7
+#define SQLITE_STATUS_SCRATCH_SIZE         8
+#define SQLITE_STATUS_MALLOC_COUNT         9
+
+/*
+** CAPI3REF: Database Connection Status
+**
+** ^This interface is used to retrieve runtime status information 
+** about a single [database connection].  ^The first argument is the
+** database connection object to be interrogated.  ^The second argument
+** is an integer constant, taken from the set of
+** [SQLITE_DBSTATUS_LOOKASIDE_USED | SQLITE_DBSTATUS_*] macros, that
+** determines the parameter to interrogate.  The set of 
+** [SQLITE_DBSTATUS_LOOKASIDE_USED | SQLITE_DBSTATUS_*] macros is likely
+** to grow in future releases of SQLite.
+**
+** ^The current value of the requested parameter is written into *pCur
+** and the highest instantaneous value is written into *pHiwtr.  ^If
+** the resetFlg is true, then the highest instantaneous value is
+** reset back down to the current value.
+**
+** ^The sqlite3_db_status() routine returns SQLITE_OK on success and a
+** non-zero [error code] on failure.
+**
+** See also: [sqlite3_status()] and [sqlite3_stmt_status()].
+*/
+SQLITE_API int sqlite3_db_status(sqlite3*, int op, int *pCur, int *pHiwtr, int resetFlg);
+
+/*
+** CAPI3REF: Status Parameters for database connections
+**
+** These constants are the available integer "verbs" that can be passed as
+** the second argument to the [sqlite3_db_status()] interface.
+**
+** New verbs may be added in future releases of SQLite. Existing verbs
+** might be discontinued. Applications should check the return code from
+** [sqlite3_db_status()] to make sure that the call worked.
+** The [sqlite3_db_status()] interface will return a non-zero error code
+** if a discontinued or unsupported verb is invoked.
+**
+** <dl>
+** ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_USED</dt>
+** <dd>This parameter returns the number of lookaside memory slots currently
+** checked out.</dd>)^
+**
+** ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_HIT</dt>
+** <dd>This parameter returns the number malloc attempts that were 
+** satisfied using lookaside memory. Only the high-water value is meaningful;
+** the current value is always zero.)^
+**
+** ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE</dt>
+** <dd>This parameter returns the number malloc attempts that might have
+** been satisfied using lookaside memory but failed due to the amount of
+** memory requested being larger than the lookaside slot size.
+** Only the high-water value is meaningful;
+** the current value is always zero.)^
+**
+** ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL</dt>
+** <dd>This parameter returns the number malloc attempts that might have
+** been satisfied using lookaside memory but failed due to all lookaside
+** memory already being in use.
+** Only the high-water value is meaningful;
+** the current value is always zero.)^
+**
+** ^(<dt>SQLITE_DBSTATUS_CACHE_USED</dt>
+** <dd>This parameter returns the approximate number of of bytes of heap
+** memory used by all pager caches associated with the database connection.)^
+** ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_USED is always 0.
+**
+** ^(<dt>SQLITE_DBSTATUS_SCHEMA_USED</dt>
+** <dd>This parameter returns the approximate number of of bytes of heap
+** memory used to store the schema for all databases associated
+** with the connection - main, temp, and any [ATTACH]-ed databases.)^ 
+** ^The full amount of memory used by the schemas is reported, even if the
+** schema memory is shared with other database connections due to
+** [shared cache mode] being enabled.
+** ^The highwater mark associated with SQLITE_DBSTATUS_SCHEMA_USED is always 0.
+**
+** ^(<dt>SQLITE_DBSTATUS_STMT_USED</dt>
+** <dd>This parameter returns the approximate number of of bytes of heap
+** and lookaside memory used by all prepared statements associated with
+** the database connection.)^
+** ^The highwater mark associated with SQLITE_DBSTATUS_STMT_USED is always 0.
+** </dd>
+** </dl>
+*/
+#define SQLITE_DBSTATUS_LOOKASIDE_USED       0
+#define SQLITE_DBSTATUS_CACHE_USED           1
+#define SQLITE_DBSTATUS_SCHEMA_USED          2
+#define SQLITE_DBSTATUS_STMT_USED            3
+#define SQLITE_DBSTATUS_LOOKASIDE_HIT        4
+#define SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE  5
+#define SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL  6
+#define SQLITE_DBSTATUS_MAX                  6   /* Largest defined DBSTATUS */
+
+
+/*
+** CAPI3REF: Prepared Statement Status
+**
+** ^(Each prepared statement maintains various
+** [SQLITE_STMTSTATUS_SORT | counters] that measure the number
+** of times it has performed specific operations.)^  These counters can
+** be used to monitor the performance characteristics of the prepared
+** statements.  For example, if the number of table steps greatly exceeds
+** the number of table searches or result rows, that would tend to indicate
+** that the prepared statement is using a full table scan rather than
+** an index.  
+**
+** ^(This interface is used to retrieve and reset counter values from
+** a [prepared statement].  The first argument is the prepared statement
+** object to be interrogated.  The second argument
+** is an integer code for a specific [SQLITE_STMTSTATUS_SORT | counter]
+** to be interrogated.)^
+** ^The current value of the requested counter is returned.
+** ^If the resetFlg is true, then the counter is reset to zero after this
+** interface call returns.
+**
+** See also: [sqlite3_status()] and [sqlite3_db_status()].
+*/
+SQLITE_API int sqlite3_stmt_status(sqlite3_stmt*, int op,int resetFlg);
+
+/*
+** CAPI3REF: Status Parameters for prepared statements
+**
+** These preprocessor macros define integer codes that name counter
+** values associated with the [sqlite3_stmt_status()] interface.
+** The meanings of the various counters are as follows:
+**
+** <dl>
+** <dt>SQLITE_STMTSTATUS_FULLSCAN_STEP</dt>
+** <dd>^This is the number of times that SQLite has stepped forward in
+** a table as part of a full table scan.  Large numbers for this counter
+** may indicate opportunities for performance improvement through 
+** careful use of indices.</dd>
+**
+** <dt>SQLITE_STMTSTATUS_SORT</dt>
+** <dd>^This is the number of sort operations that have occurred.
+** A non-zero value in this counter may indicate an opportunity to
+** improvement performance through careful use of indices.</dd>
+**
+** <dt>SQLITE_STMTSTATUS_AUTOINDEX</dt>
+** <dd>^This is the number of rows inserted into transient indices that
+** were created automatically in order to help joins run faster.
+** A non-zero value in this counter may indicate an opportunity to
+** improvement performance by adding permanent indices that do not
+** need to be reinitialized each time the statement is run.</dd>
+**
+** </dl>
+*/
+#define SQLITE_STMTSTATUS_FULLSCAN_STEP     1
+#define SQLITE_STMTSTATUS_SORT              2
+#define SQLITE_STMTSTATUS_AUTOINDEX         3
+
+/*
+** CAPI3REF: Custom Page Cache Object
+**
+** The sqlite3_pcache type is opaque.  It is implemented by
+** the pluggable module.  The SQLite core has no knowledge of
+** its size or internal structure and never deals with the
+** sqlite3_pcache object except by holding and passing pointers
+** to the object.
+**
+** See [sqlite3_pcache_methods] for additional information.
+*/
+typedef struct sqlite3_pcache sqlite3_pcache;
+
+/*
+** CAPI3REF: Application Defined Page Cache.
+** KEYWORDS: {page cache}
+**
+** ^(The [sqlite3_config]([SQLITE_CONFIG_PCACHE], ...) interface can
+** register an alternative page cache implementation by passing in an 
+** instance of the sqlite3_pcache_methods structure.)^
+** In many applications, most of the heap memory allocated by 
+** SQLite is used for the page cache.
+** By implementing a 
+** custom page cache using this API, an application can better control
+** the amount of memory consumed by SQLite, the way in which 
+** that memory is allocated and released, and the policies used to 
+** determine exactly which parts of a database file are cached and for 
+** how long.
+**
+** The alternative page cache mechanism is an
+** extreme measure that is only needed by the most demanding applications.
+** The built-in page cache is recommended for most uses.
+**
+** ^(The contents of the sqlite3_pcache_methods structure are copied to an
+** internal buffer by SQLite within the call to [sqlite3_config].  Hence
+** the application may discard the parameter after the call to
+** [sqlite3_config()] returns.)^
+**
+** ^(The xInit() method is called once for each effective 
+** call to [sqlite3_initialize()])^
+** (usually only once during the lifetime of the process). ^(The xInit()
+** method is passed a copy of the sqlite3_pcache_methods.pArg value.)^
+** The intent of the xInit() method is to set up global data structures 
+** required by the custom page cache implementation. 
+** ^(If the xInit() method is NULL, then the 
+** built-in default page cache is used instead of the application defined
+** page cache.)^
+**
+** ^The xShutdown() method is called by [sqlite3_shutdown()].
+** It can be used to clean up 
+** any outstanding resources before process shutdown, if required.
+** ^The xShutdown() method may be NULL.
+**
+** ^SQLite automatically serializes calls to the xInit method,
+** so the xInit method need not be threadsafe.  ^The
+** xShutdown method is only called from [sqlite3_shutdown()] so it does
+** not need to be threadsafe either.  All other methods must be threadsafe
+** in multithreaded applications.
+**
+** ^SQLite will never invoke xInit() more than once without an intervening
+** call to xShutdown().
+**
+** ^SQLite invokes the xCreate() method to construct a new cache instance.
+** SQLite will typically create one cache instance for each open database file,
+** though this is not guaranteed. ^The
+** first parameter, szPage, is the size in bytes of the pages that must
+** be allocated by the cache.  ^szPage will not be a power of two.  ^szPage
+** will the page size of the database file that is to be cached plus an
+** increment (here called "R") of less than 250.  SQLite will use the
+** extra R bytes on each page to store metadata about the underlying
+** database page on disk.  The value of R depends
+** on the SQLite version, the target platform, and how SQLite was compiled.
+** ^(R is constant for a particular build of SQLite. Except, there are two
+** distinct values of R when SQLite is compiled with the proprietary
+** ZIPVFS extension.)^  ^The second argument to
+** xCreate(), bPurgeable, is true if the cache being created will
+** be used to cache database pages of a file stored on disk, or
+** false if it is used for an in-memory database. The cache implementation
+** does not have to do anything special based with the value of bPurgeable;
+** it is purely advisory.  ^On a cache where bPurgeable is false, SQLite will
+** never invoke xUnpin() except to deliberately delete a page.
+** ^In other words, calls to xUnpin() on a cache with bPurgeable set to
+** false will always have the "discard" flag set to true.  
+** ^Hence, a cache created with bPurgeable false will
+** never contain any unpinned pages.
+**
+** ^(The xCachesize() method may be called at any time by SQLite to set the
+** suggested maximum cache-size (number of pages stored by) the cache
+** instance passed as the first argument. This is the value configured using
+** the SQLite "[PRAGMA cache_size]" command.)^  As with the bPurgeable
+** parameter, the implementation is not required to do anything with this
+** value; it is advisory only.
+**
+** The xPagecount() method must return the number of pages currently
+** stored in the cache, both pinned and unpinned.
+** 
+** The xFetch() method locates a page in the cache and returns a pointer to 
+** the page, or a NULL pointer.
+** A "page", in this context, means a buffer of szPage bytes aligned at an
+** 8-byte boundary. The page to be fetched is determined by the key. ^The
+** mimimum key value is 1.  After it has been retrieved using xFetch, the page 
+** is considered to be "pinned".
+**
+** If the requested page is already in the page cache, then the page cache
+** implementation must return a pointer to the page buffer with its content
+** intact.  If the requested page is not already in the cache, then the
+** cache implementation should use the value of the createFlag
+** parameter to help it determined what action to take:
+**
+** <table border=1 width=85% align=center>
+** <tr><th> createFlag <th> Behaviour when page is not already in cache
+** <tr><td> 0 <td> Do not allocate a new page.  Return NULL.
+** <tr><td> 1 <td> Allocate a new page if it easy and convenient to do so.
+**                 Otherwise return NULL.
+** <tr><td> 2 <td> Make every effort to allocate a new page.  Only return
+**                 NULL if allocating a new page is effectively impossible.
+** </table>
+**
+** ^(SQLite will normally invoke xFetch() with a createFlag of 0 or 1.  SQLite
+** will only use a createFlag of 2 after a prior call with a createFlag of 1
+** failed.)^  In between the to xFetch() calls, SQLite may
+** attempt to unpin one or more cache pages by spilling the content of
+** pinned pages to disk and synching the operating system disk cache.
+**
+** ^xUnpin() is called by SQLite with a pointer to a currently pinned page
+** as its second argument.  If the third parameter, discard, is non-zero,
+** then the page must be evicted from the cache.
+** ^If the discard parameter is
+** zero, then the page may be discarded or retained at the discretion of
+** page cache implementation. ^The page cache implementation
+** may choose to evict unpinned pages at any time.
+**
+** The cache must not perform any reference counting. A single 
+** call to xUnpin() unpins the page regardless of the number of prior calls 
+** to xFetch().
+**
+** The xRekey() method is used to change the key value associated with the
+** page passed as the second argument. If the cache
+** previously contains an entry associated with newKey, it must be
+** discarded. ^Any prior cache entry associated with newKey is guaranteed not
+** to be pinned.
+**
+** When SQLite calls the xTruncate() method, the cache must discard all
+** existing cache entries with page numbers (keys) greater than or equal
+** to the value of the iLimit parameter passed to xTruncate(). If any
+** of these pages are pinned, they are implicitly unpinned, meaning that
+** they can be safely discarded.
+**
+** ^The xDestroy() method is used to delete a cache allocated by xCreate().
+** All resources associated with the specified cache should be freed. ^After
+** calling the xDestroy() method, SQLite considers the [sqlite3_pcache*]
+** handle invalid, and will not use it with any other sqlite3_pcache_methods
+** functions.
+*/
+typedef struct sqlite3_pcache_methods sqlite3_pcache_methods;
+struct sqlite3_pcache_methods {
+  void *pArg;
+  int (*xInit)(void*);
+  void (*xShutdown)(void*);
+  sqlite3_pcache *(*xCreate)(int szPage, int bPurgeable);
+  void (*xCachesize)(sqlite3_pcache*, int nCachesize);
+  int (*xPagecount)(sqlite3_pcache*);
+  void *(*xFetch)(sqlite3_pcache*, unsigned key, int createFlag);
+  void (*xUnpin)(sqlite3_pcache*, void*, int discard);
+  void (*xRekey)(sqlite3_pcache*, void*, unsigned oldKey, unsigned newKey);
+  void (*xTruncate)(sqlite3_pcache*, unsigned iLimit);
+  void (*xDestroy)(sqlite3_pcache*);
+};
+
+/*
+** CAPI3REF: Online Backup Object
+**
+** The sqlite3_backup object records state information about an ongoing
+** online backup operation.  ^The sqlite3_backup object is created by
+** a call to [sqlite3_backup_init()] and is destroyed by a call to
+** [sqlite3_backup_finish()].
+**
+** See Also: [Using the SQLite Online Backup API]
+*/
+typedef struct sqlite3_backup sqlite3_backup;
+
+/*
+** CAPI3REF: Online Backup API.
+**
+** The backup API copies the content of one database into another.
+** It is useful either for creating backups of databases or
+** for copying in-memory databases to or from persistent files. 
+**
+** See Also: [Using the SQLite Online Backup API]
+**
+** ^SQLite holds a write transaction open on the destination database file
+** for the duration of the backup operation.
+** ^The source database is read-locked only while it is being read;
+** it is not locked continuously for the entire backup operation.
+** ^Thus, the backup may be performed on a live source database without
+** preventing other database connections from
+** reading or writing to the source database while the backup is underway.
+** 
+** ^(To perform a backup operation: 
+**   <ol>
+**     <li><b>sqlite3_backup_init()</b> is called once to initialize the
+**         backup, 
+**     <li><b>sqlite3_backup_step()</b> is called one or more times to transfer 
+**         the data between the two databases, and finally
+**     <li><b>sqlite3_backup_finish()</b> is called to release all resources 
+**         associated with the backup operation. 
+**   </ol>)^
+** There should be exactly one call to sqlite3_backup_finish() for each
+** successful call to sqlite3_backup_init().
+**
+** <b>sqlite3_backup_init()</b>
+**
+** ^The D and N arguments to sqlite3_backup_init(D,N,S,M) are the 
+** [database connection] associated with the destination database 
+** and the database name, respectively.
+** ^The database name is "main" for the main database, "temp" for the
+** temporary database, or the name specified after the AS keyword in
+** an [ATTACH] statement for an attached database.
+** ^The S and M arguments passed to 
+** sqlite3_backup_init(D,N,S,M) identify the [database connection]
+** and database name of the source database, respectively.
+** ^The source and destination [database connections] (parameters S and D)
+** must be different or else sqlite3_backup_init(D,N,S,M) will fail with
+** an error.
+**
+** ^If an error occurs within sqlite3_backup_init(D,N,S,M), then NULL is
+** returned and an error code and error message are stored in the
+** destination [database connection] D.
+** ^The error code and message for the failed call to sqlite3_backup_init()
+** can be retrieved using the [sqlite3_errcode()], [sqlite3_errmsg()], and/or
+** [sqlite3_errmsg16()] functions.
+** ^A successful call to sqlite3_backup_init() returns a pointer to an
+** [sqlite3_backup] object.
+** ^The [sqlite3_backup] object may be used with the sqlite3_backup_step() and
+** sqlite3_backup_finish() functions to perform the specified backup 
+** operation.
+**
+** <b>sqlite3_backup_step()</b>
+**
+** ^Function sqlite3_backup_step(B,N) will copy up to N pages between 
+** the source and destination databases specified by [sqlite3_backup] object B.
+** ^If N is negative, all remaining source pages are copied. 
+** ^If sqlite3_backup_step(B,N) successfully copies N pages and there
+** are still more pages to be copied, then the function returns [SQLITE_OK].
+** ^If sqlite3_backup_step(B,N) successfully finishes copying all pages
+** from source to destination, then it returns [SQLITE_DONE].
+** ^If an error occurs while running sqlite3_backup_step(B,N),
+** then an [error code] is returned. ^As well as [SQLITE_OK] and
+** [SQLITE_DONE], a call to sqlite3_backup_step() may return [SQLITE_READONLY],
+** [SQLITE_NOMEM], [SQLITE_BUSY], [SQLITE_LOCKED], or an
+** [SQLITE_IOERR_ACCESS | SQLITE_IOERR_XXX] extended error code.
+**
+** ^(The sqlite3_backup_step() might return [SQLITE_READONLY] if
+** <ol>
+** <li> the destination database was opened read-only, or
+** <li> the destination database is using write-ahead-log journaling
+** and the destination and source page sizes differ, or
+** <li> the destination database is an in-memory database and the
+** destination and source page sizes differ.
+** </ol>)^
+**
+** ^If sqlite3_backup_step() cannot obtain a required file-system lock, then
+** the [sqlite3_busy_handler | busy-handler function]
+** is invoked (if one is specified). ^If the 
+** busy-handler returns non-zero before the lock is available, then 
+** [SQLITE_BUSY] is returned to the caller. ^In this case the call to
+** sqlite3_backup_step() can be retried later. ^If the source
+** [database connection]
+** is being used to write to the source database when sqlite3_backup_step()
+** is called, then [SQLITE_LOCKED] is returned immediately. ^Again, in this
+** case the call to sqlite3_backup_step() can be retried later on. ^(If
+** [SQLITE_IOERR_ACCESS | SQLITE_IOERR_XXX], [SQLITE_NOMEM], or
+** [SQLITE_READONLY] is returned, then 
+** there is no point in retrying the call to sqlite3_backup_step(). These 
+** errors are considered fatal.)^  The application must accept 
+** that the backup operation has failed and pass the backup operation handle 
+** to the sqlite3_backup_finish() to release associated resources.
+**
+** ^The first call to sqlite3_backup_step() obtains an exclusive lock
+** on the destination file. ^The exclusive lock is not released until either 
+** sqlite3_backup_finish() is called or the backup operation is complete 
+** and sqlite3_backup_step() returns [SQLITE_DONE].  ^Every call to
+** sqlite3_backup_step() obtains a [shared lock] on the source database that
+** lasts for the duration of the sqlite3_backup_step() call.
+** ^Because the source database is not locked between calls to
+** sqlite3_backup_step(), the source database may be modified mid-way
+** through the backup process.  ^If the source database is modified by an
+** external process or via a database connection other than the one being
+** used by the backup operation, then the backup will be automatically
+** restarted by the next call to sqlite3_backup_step(). ^If the source 
+** database is modified by the using the same database connection as is used
+** by the backup operation, then the backup database is automatically
+** updated at the same time.
+**
+** <b>sqlite3_backup_finish()</b>
+**
+** When sqlite3_backup_step() has returned [SQLITE_DONE], or when the 
+** application wishes to abandon the backup operation, the application
+** should destroy the [sqlite3_backup] by passing it to sqlite3_backup_finish().
+** ^The sqlite3_backup_finish() interfaces releases all
+** resources associated with the [sqlite3_backup] object. 
+** ^If sqlite3_backup_step() has not yet returned [SQLITE_DONE], then any
+** active write-transaction on the destination database is rolled back.
+** The [sqlite3_backup] object is invalid
+** and may not be used following a call to sqlite3_backup_finish().
+**
+** ^The value returned by sqlite3_backup_finish is [SQLITE_OK] if no
+** sqlite3_backup_step() errors occurred, regardless or whether or not
+** sqlite3_backup_step() completed.
+** ^If an out-of-memory condition or IO error occurred during any prior
+** sqlite3_backup_step() call on the same [sqlite3_backup] object, then
+** sqlite3_backup_finish() returns the corresponding [error code].
+**
+** ^A return of [SQLITE_BUSY] or [SQLITE_LOCKED] from sqlite3_backup_step()
+** is not a permanent error and does not affect the return value of
+** sqlite3_backup_finish().
+**
+** <b>sqlite3_backup_remaining(), sqlite3_backup_pagecount()</b>
+**
+** ^Each call to sqlite3_backup_step() sets two values inside
+** the [sqlite3_backup] object: the number of pages still to be backed
+** up and the total number of pages in the source database file.
+** The sqlite3_backup_remaining() and sqlite3_backup_pagecount() interfaces
+** retrieve these two values, respectively.
+**
+** ^The values returned by these functions are only updated by
+** sqlite3_backup_step(). ^If the source database is modified during a backup
+** operation, then the values are not updated to account for any extra
+** pages that need to be updated or the size of the source database file
+** changing.
+**
+** <b>Concurrent Usage of Database Handles</b>
+**
+** ^The source [database connection] may be used by the application for other
+** purposes while a backup operation is underway or being initialized.
+** ^If SQLite is compiled and configured to support threadsafe database
+** connections, then the source database connection may be used concurrently
+** from within other threads.
+**
+** However, the application must guarantee that the destination 
+** [database connection] is not passed to any other API (by any thread) after 
+** sqlite3_backup_init() is called and before the corresponding call to
+** sqlite3_backup_finish().  SQLite does not currently check to see
+** if the application incorrectly accesses the destination [database connection]
+** and so no error code is reported, but the operations may malfunction
+** nevertheless.  Use of the destination database connection while a
+** backup is in progress might also also cause a mutex deadlock.
+**
+** If running in [shared cache mode], the application must
+** guarantee that the shared cache used by the destination database
+** is not accessed while the backup is running. In practice this means
+** that the application must guarantee that the disk file being 
+** backed up to is not accessed by any connection within the process,
+** not just the specific connection that was passed to sqlite3_backup_init().
+**
+** The [sqlite3_backup] object itself is partially threadsafe. Multiple 
+** threads may safely make multiple concurrent calls to sqlite3_backup_step().
+** However, the sqlite3_backup_remaining() and sqlite3_backup_pagecount()
+** APIs are not strictly speaking threadsafe. If they are invoked at the
+** same time as another thread is invoking sqlite3_backup_step() it is
+** possible that they return invalid values.
+*/
+SQLITE_API sqlite3_backup *sqlite3_backup_init(
+  sqlite3 *pDest,                        /* Destination database handle */
+  const char *zDestName,                 /* Destination database name */
+  sqlite3 *pSource,                      /* Source database handle */
+  const char *zSourceName                /* Source database name */
+);
+SQLITE_API int sqlite3_backup_step(sqlite3_backup *p, int nPage);
+SQLITE_API int sqlite3_backup_finish(sqlite3_backup *p);
+SQLITE_API int sqlite3_backup_remaining(sqlite3_backup *p);
+SQLITE_API int sqlite3_backup_pagecount(sqlite3_backup *p);
+
+/*
+** CAPI3REF: Unlock Notification
+**
+** ^When running in shared-cache mode, a database operation may fail with
+** an [SQLITE_LOCKED] error if the required locks on the shared-cache or
+** individual tables within the shared-cache cannot be obtained. See
+** [SQLite Shared-Cache Mode] for a description of shared-cache locking. 
+** ^This API may be used to register a callback that SQLite will invoke 
+** when the connection currently holding the required lock relinquishes it.
+** ^This API is only available if the library was compiled with the
+** [SQLITE_ENABLE_UNLOCK_NOTIFY] C-preprocessor symbol defined.
+**
+** See Also: [Using the SQLite Unlock Notification Feature].
+**
+** ^Shared-cache locks are released when a database connection concludes
+** its current transaction, either by committing it or rolling it back. 
+**
+** ^When a connection (known as the blocked connection) fails to obtain a
+** shared-cache lock and SQLITE_LOCKED is returned to the caller, the
+** identity of the database connection (the blocking connection) that
+** has locked the required resource is stored internally. ^After an 
+** application receives an SQLITE_LOCKED error, it may call the
+** sqlite3_unlock_notify() method with the blocked connection handle as 
+** the first argument to register for a callback that will be invoked
+** when the blocking connections current transaction is concluded. ^The
+** callback is invoked from within the [sqlite3_step] or [sqlite3_close]
+** call that concludes the blocking connections transaction.
+**
+** ^(If sqlite3_unlock_notify() is called in a multi-threaded application,
+** there is a chance that the blocking connection will have already
+** concluded its transaction by the time sqlite3_unlock_notify() is invoked.
+** If this happens, then the specified callback is invoked immediately,
+** from within the call to sqlite3_unlock_notify().)^
+**
+** ^If the blocked connection is attempting to obtain a write-lock on a
+** shared-cache table, and more than one other connection currently holds
+** a read-lock on the same table, then SQLite arbitrarily selects one of 
+** the other connections to use as the blocking connection.
+**
+** ^(There may be at most one unlock-notify callback registered by a 
+** blocked connection. If sqlite3_unlock_notify() is called when the
+** blocked connection already has a registered unlock-notify callback,
+** then the new callback replaces the old.)^ ^If sqlite3_unlock_notify() is
+** called with a NULL pointer as its second argument, then any existing
+** unlock-notify callback is canceled. ^The blocked connections 
+** unlock-notify callback may also be canceled by closing the blocked
+** connection using [sqlite3_close()].
+**
+** The unlock-notify callback is not reentrant. If an application invokes
+** any sqlite3_xxx API functions from within an unlock-notify callback, a
+** crash or deadlock may be the result.
+**
+** ^Unless deadlock is detected (see below), sqlite3_unlock_notify() always
+** returns SQLITE_OK.
+**
+** <b>Callback Invocation Details</b>
+**
+** When an unlock-notify callback is registered, the application provides a 
+** single void* pointer that is passed to the callback when it is invoked.
+** However, the signature of the callback function allows SQLite to pass
+** it an array of void* context pointers. The first argument passed to
+** an unlock-notify callback is a pointer to an array of void* pointers,
+** and the second is the number of entries in the array.
+**
+** When a blocking connections transaction is concluded, there may be
+** more than one blocked connection that has registered for an unlock-notify
+** callback. ^If two or more such blocked connections have specified the
+** same callback function, then instead of invoking the callback function
+** multiple times, it is invoked once with the set of void* context pointers
+** specified by the blocked connections bundled together into an array.
+** This gives the application an opportunity to prioritize any actions 
+** related to the set of unblocked database connections.
+**
+** <b>Deadlock Detection</b>
+**
+** Assuming that after registering for an unlock-notify callback a 
+** database waits for the callback to be issued before taking any further
+** action (a reasonable assumption), then using this API may cause the
+** application to deadlock. For example, if connection X is waiting for
+** connection Y's transaction to be concluded, and similarly connection
+** Y is waiting on connection X's transaction, then neither connection
+** will proceed and the system may remain deadlocked indefinitely.
+**
+** To avoid this scenario, the sqlite3_unlock_notify() performs deadlock
+** detection. ^If a given call to sqlite3_unlock_notify() would put the
+** system in a deadlocked state, then SQLITE_LOCKED is returned and no
+** unlock-notify callback is registered. The system is said to be in
+** a deadlocked state if connection A has registered for an unlock-notify
+** callback on the conclusion of connection B's transaction, and connection
+** B has itself registered for an unlock-notify callback when connection
+** A's transaction is concluded. ^Indirect deadlock is also detected, so
+** the system is also considered to be deadlocked if connection B has
+** registered for an unlock-notify callback on the conclusion of connection
+** C's transaction, where connection C is waiting on connection A. ^Any
+** number of levels of indirection are allowed.
+**
+** <b>The "DROP TABLE" Exception</b>
+**
+** When a call to [sqlite3_step()] returns SQLITE_LOCKED, it is almost 
+** always appropriate to call sqlite3_unlock_notify(). There is however,
+** one exception. When executing a "DROP TABLE" or "DROP INDEX" statement,
+** SQLite checks if there are any currently executing SELECT statements
+** that belong to the same connection. If there are, SQLITE_LOCKED is
+** returned. In this case there is no "blocking connection", so invoking
+** sqlite3_unlock_notify() results in the unlock-notify callback being
+** invoked immediately. If the application then re-attempts the "DROP TABLE"
+** or "DROP INDEX" query, an infinite loop might be the result.
+**
+** One way around this problem is to check the extended error code returned
+** by an sqlite3_step() call. ^(If there is a blocking connection, then the
+** extended error code is set to SQLITE_LOCKED_SHAREDCACHE. Otherwise, in
+** the special "DROP TABLE/INDEX" case, the extended error code is just 
+** SQLITE_LOCKED.)^
+*/
+SQLITE_API int sqlite3_unlock_notify(
+  sqlite3 *pBlocked,                          /* Waiting connection */
+  void (*xNotify)(void **apArg, int nArg),    /* Callback function to invoke */
+  void *pNotifyArg                            /* Argument to pass to xNotify */
+);
+
+
+/*
+** CAPI3REF: String Comparison
+**
+** ^The [sqlite3_strnicmp()] API allows applications and extensions to
+** compare the contents of two buffers containing UTF-8 strings in a
+** case-independent fashion, using the same definition of case independence 
+** that SQLite uses internally when comparing identifiers.
+*/
+SQLITE_API int sqlite3_strnicmp(const char *, const char *, int);
+
+/*
+** CAPI3REF: Error Logging Interface
+**
+** ^The [sqlite3_log()] interface writes a message into the error log
+** established by the [SQLITE_CONFIG_LOG] option to [sqlite3_config()].
+** ^If logging is enabled, the zFormat string and subsequent arguments are
+** used with [sqlite3_snprintf()] to generate the final output string.
+**
+** The sqlite3_log() interface is intended for use by extensions such as
+** virtual tables, collating functions, and SQL functions.  While there is
+** nothing to prevent an application from calling sqlite3_log(), doing so
+** is considered bad form.
+**
+** The zFormat string must not be NULL.
+**
+** To avoid deadlocks and other threading problems, the sqlite3_log() routine
+** will not use dynamically allocated memory.  The log message is stored in
+** a fixed-length buffer on the stack.  If the log message is longer than
+** a few hundred characters, it will be truncated to the length of the
+** buffer.
+*/
+SQLITE_API void sqlite3_log(int iErrCode, const char *zFormat, ...);
+
+/*
+** CAPI3REF: Write-Ahead Log Commit Hook
+**
+** ^The [sqlite3_wal_hook()] function is used to register a callback that
+** will be invoked each time a database connection commits data to a
+** [write-ahead log] (i.e. whenever a transaction is committed in
+** [journal_mode | journal_mode=WAL mode]). 
+**
+** ^The callback is invoked by SQLite after the commit has taken place and 
+** the associated write-lock on the database released, so the implementation 
+** may read, write or [checkpoint] the database as required.
+**
+** ^The first parameter passed to the callback function when it is invoked
+** is a copy of the third parameter passed to sqlite3_wal_hook() when
+** registering the callback. ^The second is a copy of the database handle.
+** ^The third parameter is the name of the database that was written to -
+** either "main" or the name of an [ATTACH]-ed database. ^The fourth parameter
+** is the number of pages currently in the write-ahead log file,
+** including those that were just committed.
+**
+** The callback function should normally return [SQLITE_OK].  ^If an error
+** code is returned, that error will propagate back up through the
+** SQLite code base to cause the statement that provoked the callback
+** to report an error, though the commit will have still occurred. If the
+** callback returns [SQLITE_ROW] or [SQLITE_DONE], or if it returns a value
+** that does not correspond to any valid SQLite error code, the results
+** are undefined.
+**
+** A single database handle may have at most a single write-ahead log callback 
+** registered at one time. ^Calling [sqlite3_wal_hook()] replaces any
+** previously registered write-ahead log callback. ^Note that the
+** [sqlite3_wal_autocheckpoint()] interface and the
+** [wal_autocheckpoint pragma] both invoke [sqlite3_wal_hook()] and will
+** those overwrite any prior [sqlite3_wal_hook()] settings.
+*/
+SQLITE_API void *sqlite3_wal_hook(
+  sqlite3*, 
+  int(*)(void *,sqlite3*,const char*,int),
+  void*
+);
+
+/*
+** CAPI3REF: Configure an auto-checkpoint
+**
+** ^The [sqlite3_wal_autocheckpoint(D,N)] is a wrapper around
+** [sqlite3_wal_hook()] that causes any database on [database connection] D
+** to automatically [checkpoint]
+** after committing a transaction if there are N or
+** more frames in the [write-ahead log] file.  ^Passing zero or 
+** a negative value as the nFrame parameter disables automatic
+** checkpoints entirely.
+**
+** ^The callback registered by this function replaces any existing callback
+** registered using [sqlite3_wal_hook()].  ^Likewise, registering a callback
+** using [sqlite3_wal_hook()] disables the automatic checkpoint mechanism
+** configured by this function.
+**
+** ^The [wal_autocheckpoint pragma] can be used to invoke this interface
+** from SQL.
+**
+** ^Every new [database connection] defaults to having the auto-checkpoint
+** enabled with a threshold of 1000 or [SQLITE_DEFAULT_WAL_AUTOCHECKPOINT]
+** pages.  The use of this interface
+** is only necessary if the default setting is found to be suboptimal
+** for a particular application.
+*/
+SQLITE_API int sqlite3_wal_autocheckpoint(sqlite3 *db, int N);
+
+/*
+** CAPI3REF: Checkpoint a database
+**
+** ^The [sqlite3_wal_checkpoint(D,X)] interface causes database named X
+** on [database connection] D to be [checkpointed].  ^If X is NULL or an
+** empty string, then a checkpoint is run on all databases of
+** connection D.  ^If the database connection D is not in
+** [WAL | write-ahead log mode] then this interface is a harmless no-op.
+**
+** ^The [wal_checkpoint pragma] can be used to invoke this interface
+** from SQL.  ^The [sqlite3_wal_autocheckpoint()] interface and the
+** [wal_autocheckpoint pragma] can be used to cause this interface to be
+** run whenever the WAL reaches a certain size threshold.
+**
+** See also: [sqlite3_wal_checkpoint_v2()]
+*/
+SQLITE_API int sqlite3_wal_checkpoint(sqlite3 *db, const char *zDb);
+
+/*
+** CAPI3REF: Checkpoint a database
+**
+** Run a checkpoint operation on WAL database zDb attached to database 
+** handle db. The specific operation is determined by the value of the 
+** eMode parameter:
+**
+** <dl>
+** <dt>SQLITE_CHECKPOINT_PASSIVE<dd>
+**   Checkpoint as many frames as possible without waiting for any database 
+**   readers or writers to finish. Sync the db file if all frames in the log
+**   are checkpointed. This mode is the same as calling 
+**   sqlite3_wal_checkpoint(). The busy-handler callback is never invoked.
+**
+** <dt>SQLITE_CHECKPOINT_FULL<dd>
+**   This mode blocks (calls the busy-handler callback) until there is no
+**   database writer and all readers are reading from the most recent database
+**   snapshot. It then checkpoints all frames in the log file and syncs the
+**   database file. This call blocks database writers while it is running,
+**   but not database readers.
+**
+** <dt>SQLITE_CHECKPOINT_RESTART<dd>
+**   This mode works the same way as SQLITE_CHECKPOINT_FULL, except after 
+**   checkpointing the log file it blocks (calls the busy-handler callback)
+**   until all readers are reading from the database file only. This ensures 
+**   that the next client to write to the database file restarts the log file 
+**   from the beginning. This call blocks database writers while it is running,
+**   but not database readers.
+** </dl>
+**
+** If pnLog is not NULL, then *pnLog is set to the total number of frames in
+** the log file before returning. If pnCkpt is not NULL, then *pnCkpt is set to
+** the total number of checkpointed frames (including any that were already
+** checkpointed when this function is called). *pnLog and *pnCkpt may be
+** populated even if sqlite3_wal_checkpoint_v2() returns other than SQLITE_OK.
+** If no values are available because of an error, they are both set to -1
+** before returning to communicate this to the caller.
+**
+** All calls obtain an exclusive "checkpoint" lock on the database file. If
+** any other process is running a checkpoint operation at the same time, the 
+** lock cannot be obtained and SQLITE_BUSY is returned. Even if there is a 
+** busy-handler configured, it will not be invoked in this case.
+**
+** The SQLITE_CHECKPOINT_FULL and RESTART modes also obtain the exclusive 
+** "writer" lock on the database file. If the writer lock cannot be obtained
+** immediately, and a busy-handler is configured, it is invoked and the writer
+** lock retried until either the busy-handler returns 0 or the lock is
+** successfully obtained. The busy-handler is also invoked while waiting for
+** database readers as described above. If the busy-handler returns 0 before
+** the writer lock is obtained or while waiting for database readers, the
+** checkpoint operation proceeds from that point in the same way as 
+** SQLITE_CHECKPOINT_PASSIVE - checkpointing as many frames as possible 
+** without blocking any further. SQLITE_BUSY is returned in this case.
+**
+** If parameter zDb is NULL or points to a zero length string, then the
+** specified operation is attempted on all WAL databases. In this case the
+** values written to output parameters *pnLog and *pnCkpt are undefined. If 
+** an SQLITE_BUSY error is encountered when processing one or more of the 
+** attached WAL databases, the operation is still attempted on any remaining 
+** attached databases and SQLITE_BUSY is returned to the caller. If any other 
+** error occurs while processing an attached database, processing is abandoned 
+** and the error code returned to the caller immediately. If no error 
+** (SQLITE_BUSY or otherwise) is encountered while processing the attached 
+** databases, SQLITE_OK is returned.
+**
+** If database zDb is the name of an attached database that is not in WAL
+** mode, SQLITE_OK is returned and both *pnLog and *pnCkpt set to -1. If
+** zDb is not NULL (or a zero length string) and is not the name of any
+** attached database, SQLITE_ERROR is returned to the caller.
+*/
+SQLITE_API int sqlite3_wal_checkpoint_v2(
+  sqlite3 *db,                    /* Database handle */
+  const char *zDb,                /* Name of attached database (or NULL) */
+  int eMode,                      /* SQLITE_CHECKPOINT_* value */
+  int *pnLog,                     /* OUT: Size of WAL log in frames */
+  int *pnCkpt                     /* OUT: Total number of frames checkpointed */
+);
+
+/*
+** CAPI3REF: Checkpoint operation parameters
+**
+** These constants can be used as the 3rd parameter to
+** [sqlite3_wal_checkpoint_v2()].  See the [sqlite3_wal_checkpoint_v2()]
+** documentation for additional information about the meaning and use of
+** each of these values.
+*/
+#define SQLITE_CHECKPOINT_PASSIVE 0
+#define SQLITE_CHECKPOINT_FULL    1
+#define SQLITE_CHECKPOINT_RESTART 2
+
+
+/*
+** Undo the hack that converts floating point types to integer for
+** builds on processors without floating point support.
+*/
+#ifdef SQLITE_OMIT_FLOATING_POINT
+# undef double
+#endif
+
+#if 0
+}  /* End of the 'extern "C"' block */
+#endif
+#endif
+
+/*
+** 2010 August 30
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+*/
+
+#ifndef _SQLITE3RTREE_H_
+#define _SQLITE3RTREE_H_
+
+
+#if 0
+extern "C" {
+#endif
+
+typedef struct sqlite3_rtree_geometry sqlite3_rtree_geometry;
+
+/*
+** Register a geometry callback named zGeom that can be used as part of an
+** R-Tree geometry query as follows:
+**
+**   SELECT ... FROM <rtree> WHERE <rtree col> MATCH $zGeom(... params ...)
+*/
+SQLITE_API int sqlite3_rtree_geometry_callback(
+  sqlite3 *db,
+  const char *zGeom,
+  int (*xGeom)(sqlite3_rtree_geometry *, int nCoord, double *aCoord, int *pRes),
+  void *pContext
+);
+
+
+/*
+** A pointer to a structure of the following type is passed as the first
+** argument to callbacks registered using rtree_geometry_callback().
+*/
+struct sqlite3_rtree_geometry {
+  void *pContext;                 /* Copy of pContext passed to s_r_g_c() */
+  int nParam;                     /* Size of array aParam[] */
+  double *aParam;                 /* Parameters passed to SQL geom function */
+  void *pUser;                    /* Callback implementation user data */
+  void (*xDelUser)(void *);       /* Called by SQLite to clean up pUser */
+};
+
+
+#if 0
+}  /* end of the 'extern "C"' block */
+#endif
+
+#endif  /* ifndef _SQLITE3RTREE_H_ */
+
+
+/************** End of sqlite3.h *********************************************/
+/************** Continuing where we left off in sqliteInt.h ******************/
+/************** Include hash.h in the middle of sqliteInt.h ******************/
+/************** Begin file hash.h ********************************************/
+/*
+** 2001 September 22
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This is the header file for the generic hash-table implemenation
+** used in SQLite.
+*/
+#ifndef _SQLITE_HASH_H_
+#define _SQLITE_HASH_H_
+
+/* Forward declarations of structures. */
+typedef struct Hash Hash;
+typedef struct HashElem HashElem;
+
+/* A complete hash table is an instance of the following structure.
+** The internals of this structure are intended to be opaque -- client
+** code should not attempt to access or modify the fields of this structure
+** directly.  Change this structure only by using the routines below.
+** However, some of the "procedures" and "functions" for modifying and
+** accessing this structure are really macros, so we can't really make
+** this structure opaque.
+**
+** All elements of the hash table are on a single doubly-linked list.
+** Hash.first points to the head of this list.
+**
+** There are Hash.htsize buckets.  Each bucket points to a spot in
+** the global doubly-linked list.  The contents of the bucket are the
+** element pointed to plus the next _ht.count-1 elements in the list.
+**
+** Hash.htsize and Hash.ht may be zero.  In that case lookup is done
+** by a linear search of the global list.  For small tables, the 
+** Hash.ht table is never allocated because if there are few elements
+** in the table, it is faster to do a linear search than to manage
+** the hash table.
+*/
+struct Hash {
+  unsigned int htsize;      /* Number of buckets in the hash table */
+  unsigned int count;       /* Number of entries in this table */
+  HashElem *first;          /* The first element of the array */
+  struct _ht {              /* the hash table */
+    int count;                 /* Number of entries with this hash */
+    HashElem *chain;           /* Pointer to first entry with this hash */
+  } *ht;
+};
+
+/* Each element in the hash table is an instance of the following 
+** structure.  All elements are stored on a single doubly-linked list.
+**
+** Again, this structure is intended to be opaque, but it can't really
+** be opaque because it is used by macros.
+*/
+struct HashElem {
+  HashElem *next, *prev;       /* Next and previous elements in the table */
+  void *data;                  /* Data associated with this element */
+  const char *pKey; int nKey;  /* Key associated with this element */
+};
+
+/*
+** Access routines.  To delete, insert a NULL pointer.
+*/
+SQLITE_PRIVATE void sqlite3HashInit(Hash*);
+SQLITE_PRIVATE void *sqlite3HashInsert(Hash*, const char *pKey, int nKey, void *pData);
+SQLITE_PRIVATE void *sqlite3HashFind(const Hash*, const char *pKey, int nKey);
+SQLITE_PRIVATE void sqlite3HashClear(Hash*);
+
+/*
+** Macros for looping over all elements of a hash table.  The idiom is
+** like this:
+**
+**   Hash h;
+**   HashElem *p;
+**   ...
+**   for(p=sqliteHashFirst(&h); p; p=sqliteHashNext(p)){
+**     SomeStructure *pData = sqliteHashData(p);
+**     // do something with pData
+**   }
+*/
+#define sqliteHashFirst(H)  ((H)->first)
+#define sqliteHashNext(E)   ((E)->next)
+#define sqliteHashData(E)   ((E)->data)
+/* #define sqliteHashKey(E)    ((E)->pKey) // NOT USED */
+/* #define sqliteHashKeysize(E) ((E)->nKey)  // NOT USED */
+
+/*
+** Number of entries in a hash table
+*/
+/* #define sqliteHashCount(H)  ((H)->count) // NOT USED */
+
+#endif /* _SQLITE_HASH_H_ */
+
+/************** End of hash.h ************************************************/
+/************** Continuing where we left off in sqliteInt.h ******************/
+/************** Include parse.h in the middle of sqliteInt.h *****************/
+/************** Begin file parse.h *******************************************/
+#define TK_SEMI                            1
+#define TK_EXPLAIN                         2
+#define TK_QUERY                           3
+#define TK_PLAN                            4
+#define TK_BEGIN                           5
+#define TK_TRANSACTION                     6
+#define TK_DEFERRED                        7
+#define TK_IMMEDIATE                       8
+#define TK_EXCLUSIVE                       9
+#define TK_COMMIT                         10
+#define TK_END                            11
+#define TK_ROLLBACK                       12
+#define TK_SAVEPOINT                      13
+#define TK_RELEASE                        14
+#define TK_TO                             15
+#define TK_TABLE                          16
+#define TK_CREATE                         17
+#define TK_IF                             18
+#define TK_NOT                            19
+#define TK_EXISTS                         20
+#define TK_TEMP                           21
+#define TK_LP                             22
+#define TK_RP                             23
+#define TK_AS                             24
+#define TK_COMMA                          25
+#define TK_ID                             26
+#define TK_INDEXED                        27
+#define TK_ABORT                          28
+#define TK_ACTION                         29
+#define TK_AFTER                          30
+#define TK_ANALYZE                        31
+#define TK_ASC                            32
+#define TK_ATTACH                         33
+#define TK_BEFORE                         34
+#define TK_BY                             35
+#define TK_CASCADE                        36
+#define TK_CAST                           37
+#define TK_COLUMNKW                       38
+#define TK_CONFLICT                       39
+#define TK_DATABASE                       40
+#define TK_DESC                           41
+#define TK_DETACH                         42
+#define TK_EACH                           43
+#define TK_FAIL                           44
+#define TK_FOR                            45
+#define TK_IGNORE                         46
+#define TK_INITIALLY                      47
+#define TK_INSTEAD                        48
+#define TK_LIKE_KW                        49
+#define TK_MATCH                          50
+#define TK_NO                             51
+#define TK_KEY                            52
+#define TK_OF                             53
+#define TK_OFFSET                         54
+#define TK_PRAGMA                         55
+#define TK_RAISE                          56
+#define TK_REPLACE                        57
+#define TK_RESTRICT                       58
+#define TK_ROW                            59
+#define TK_TRIGGER                        60
+#define TK_VACUUM                         61
+#define TK_VIEW                           62
+#define TK_VIRTUAL                        63
+#define TK_REINDEX                        64
+#define TK_RENAME                         65
+#define TK_CTIME_KW                       66
+#define TK_ANY                            67
+#define TK_OR                             68
+#define TK_AND                            69
+#define TK_IS                             70
+#define TK_BETWEEN                        71
+#define TK_IN                             72
+#define TK_ISNULL                         73
+#define TK_NOTNULL                        74
+#define TK_NE                             75
+#define TK_EQ                             76
+#define TK_GT                             77
+#define TK_LE                             78
+#define TK_LT                             79
+#define TK_GE                             80
+#define TK_ESCAPE                         81
+#define TK_BITAND                         82
+#define TK_BITOR                          83
+#define TK_LSHIFT                         84
+#define TK_RSHIFT                         85
+#define TK_PLUS                           86
+#define TK_MINUS                          87
+#define TK_STAR                           88
+#define TK_SLASH                          89
+#define TK_REM                            90
+#define TK_CONCAT                         91
+#define TK_COLLATE                        92
+#define TK_BITNOT                         93
+#define TK_STRING                         94
+#define TK_JOIN_KW                        95
+#define TK_CONSTRAINT                     96
+#define TK_DEFAULT                        97
+#define TK_NULL                           98
+#define TK_PRIMARY                        99
+#define TK_UNIQUE                         100
+#define TK_CHECK                          101
+#define TK_REFERENCES                     102
+#define TK_AUTOINCR                       103
+#define TK_ON                             104
+#define TK_INSERT                         105
+#define TK_DELETE                         106
+#define TK_UPDATE                         107
+#define TK_SET                            108
+#define TK_DEFERRABLE                     109
+#define TK_FOREIGN                        110
+#define TK_DROP                           111
+#define TK_UNION                          112
+#define TK_ALL                            113
+#define TK_EXCEPT                         114
+#define TK_INTERSECT                      115
+#define TK_SELECT                         116
+#define TK_DISTINCT                       117
+#define TK_DOT                            118
+#define TK_FROM                           119
+#define TK_JOIN                           120
+#define TK_USING                          121
+#define TK_ORDER                          122
+#define TK_GROUP                          123
+#define TK_HAVING                         124
+#define TK_LIMIT                          125
+#define TK_WHERE                          126
+#define TK_INTO                           127
+#define TK_VALUES                         128
+#define TK_INTEGER                        129
+#define TK_FLOAT                          130
+#define TK_BLOB                           131
+#define TK_REGISTER                       132
+#define TK_VARIABLE                       133
+#define TK_CASE                           134
+#define TK_WHEN                           135
+#define TK_THEN                           136
+#define TK_ELSE                           137
+#define TK_INDEX                          138
+#define TK_ALTER                          139
+#define TK_ADD                            140
+#define TK_TO_TEXT                        141
+#define TK_TO_BLOB                        142
+#define TK_TO_NUMERIC                     143
+#define TK_TO_INT                         144
+#define TK_TO_REAL                        145
+#define TK_ISNOT                          146
+#define TK_END_OF_FILE                    147
+#define TK_ILLEGAL                        148
+#define TK_SPACE                          149
+#define TK_UNCLOSED_STRING                150
+#define TK_FUNCTION                       151
+#define TK_COLUMN                         152
+#define TK_AGG_FUNCTION                   153
+#define TK_AGG_COLUMN                     154
+#define TK_CONST_FUNC                     155
+#define TK_UMINUS                         156
+#define TK_UPLUS                          157
+
+/************** End of parse.h ***********************************************/
+/************** Continuing where we left off in sqliteInt.h ******************/
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <stddef.h>
+
+/*
+** If compiling for a processor that lacks floating point support,
+** substitute integer for floating-point
+*/
+#ifdef SQLITE_OMIT_FLOATING_POINT
+# define double sqlite_int64
+# define float sqlite_int64
+# define LONGDOUBLE_TYPE sqlite_int64
+# ifndef SQLITE_BIG_DBL
+#   define SQLITE_BIG_DBL (((sqlite3_int64)1)<<50)
+# endif
+# define SQLITE_OMIT_DATETIME_FUNCS 1
+# define SQLITE_OMIT_TRACE 1
+# undef SQLITE_MIXED_ENDIAN_64BIT_FLOAT
+# undef SQLITE_HAVE_ISNAN
+#endif
+#ifndef SQLITE_BIG_DBL
+# define SQLITE_BIG_DBL (1e99)
+#endif
+
+/*
+** OMIT_TEMPDB is set to 1 if SQLITE_OMIT_TEMPDB is defined, or 0
+** afterward. Having this macro allows us to cause the C compiler 
+** to omit code used by TEMP tables without messy #ifndef statements.
+*/
+#ifdef SQLITE_OMIT_TEMPDB
+#define OMIT_TEMPDB 1
+#else
+#define OMIT_TEMPDB 0
+#endif
+
+/*
+** The "file format" number is an integer that is incremented whenever
+** the VDBE-level file format changes.  The following macros define the
+** the default file format for new databases and the maximum file format
+** that the library can read.
+*/
+#define SQLITE_MAX_FILE_FORMAT 4
+#ifndef SQLITE_DEFAULT_FILE_FORMAT
+# define SQLITE_DEFAULT_FILE_FORMAT 1
+#endif
+
+/*
+** Determine whether triggers are recursive by default.  This can be
+** changed at run-time using a pragma.
+*/
+#ifndef SQLITE_DEFAULT_RECURSIVE_TRIGGERS
+# define SQLITE_DEFAULT_RECURSIVE_TRIGGERS 0
+#endif
+
+/*
+** Provide a default value for SQLITE_TEMP_STORE in case it is not specified
+** on the command-line
+*/
+#ifndef SQLITE_TEMP_STORE
+# define SQLITE_TEMP_STORE 1
+#endif
+
+/*
+** GCC does not define the offsetof() macro so we'll have to do it
+** ourselves.
+*/
+#ifndef offsetof
+#define offsetof(STRUCTURE,FIELD) ((int)((char*)&((STRUCTURE*)0)->FIELD))
+#endif
+
+/*
+** Check to see if this machine uses EBCDIC.  (Yes, believe it or
+** not, there are still machines out there that use EBCDIC.)
+*/
+#if 'A' == '\301'
+# define SQLITE_EBCDIC 1
+#else
+# define SQLITE_ASCII 1
+#endif
+
+/*
+** Integers of known sizes.  These typedefs might change for architectures
+** where the sizes very.  Preprocessor macros are available so that the
+** types can be conveniently redefined at compile-type.  Like this:
+**
+**         cc '-DUINTPTR_TYPE=long long int' ...
+*/
+#ifndef UINT32_TYPE
+# ifdef HAVE_UINT32_T
+#  define UINT32_TYPE uint32_t
+# else
+#  define UINT32_TYPE unsigned int
+# endif
+#endif
+#ifndef UINT16_TYPE
+# ifdef HAVE_UINT16_T
+#  define UINT16_TYPE uint16_t
+# else
+#  define UINT16_TYPE unsigned short int
+# endif
+#endif
+#ifndef INT16_TYPE
+# ifdef HAVE_INT16_T
+#  define INT16_TYPE int16_t
+# else
+#  define INT16_TYPE short int
+# endif
+#endif
+#ifndef UINT8_TYPE
+# ifdef HAVE_UINT8_T
+#  define UINT8_TYPE uint8_t
+# else
+#  define UINT8_TYPE unsigned char
+# endif
+#endif
+#ifndef INT8_TYPE
+# ifdef HAVE_INT8_T
+#  define INT8_TYPE int8_t
+# else
+#  define INT8_TYPE signed char
+# endif
+#endif
+#ifndef LONGDOUBLE_TYPE
+# define LONGDOUBLE_TYPE long double
+#endif
+typedef sqlite_int64 i64;          /* 8-byte signed integer */
+typedef sqlite_uint64 u64;         /* 8-byte unsigned integer */
+typedef UINT32_TYPE u32;           /* 4-byte unsigned integer */
+typedef UINT16_TYPE u16;           /* 2-byte unsigned integer */
+typedef INT16_TYPE i16;            /* 2-byte signed integer */
+typedef UINT8_TYPE u8;             /* 1-byte unsigned integer */
+typedef INT8_TYPE i8;              /* 1-byte signed integer */
+
+/*
+** SQLITE_MAX_U32 is a u64 constant that is the maximum u64 value
+** that can be stored in a u32 without loss of data.  The value
+** is 0x00000000ffffffff.  But because of quirks of some compilers, we
+** have to specify the value in the less intuitive manner shown:
+*/
+#define SQLITE_MAX_U32  ((((u64)1)<<32)-1)
+
+/*
+** Macros to determine whether the machine is big or little endian,
+** evaluated at runtime.
+*/
+#ifdef SQLITE_AMALGAMATION
+SQLITE_PRIVATE const int sqlite3one = 1;
+#else
+SQLITE_PRIVATE const int sqlite3one;
+#endif
+#if defined(i386) || defined(__i386__) || defined(_M_IX86)\
+                             || defined(__x86_64) || defined(__x86_64__)
+# define SQLITE_BIGENDIAN    0
+# define SQLITE_LITTLEENDIAN 1
+# define SQLITE_UTF16NATIVE  SQLITE_UTF16LE
+#else
+# define SQLITE_BIGENDIAN    (*(char *)(&sqlite3one)==0)
+# define SQLITE_LITTLEENDIAN (*(char *)(&sqlite3one)==1)
+# define SQLITE_UTF16NATIVE (SQLITE_BIGENDIAN?SQLITE_UTF16BE:SQLITE_UTF16LE)
+#endif
+
+/*
+** Constants for the largest and smallest possible 64-bit signed integers.
+** These macros are designed to work correctly on both 32-bit and 64-bit
+** compilers.
+*/
+#define LARGEST_INT64  (0xffffffff|(((i64)0x7fffffff)<<32))
+#define SMALLEST_INT64 (((i64)-1) - LARGEST_INT64)
+
+/* 
+** Round up a number to the next larger multiple of 8.  This is used
+** to force 8-byte alignment on 64-bit architectures.
+*/
+#define ROUND8(x)     (((x)+7)&~7)
+
+/*
+** Round down to the nearest multiple of 8
+*/
+#define ROUNDDOWN8(x) ((x)&~7)
+
+/*
+** Assert that the pointer X is aligned to an 8-byte boundary.  This
+** macro is used only within assert() to verify that the code gets
+** all alignment restrictions correct.
+**
+** Except, if SQLITE_4_BYTE_ALIGNED_MALLOC is defined, then the
+** underlying malloc() implemention might return us 4-byte aligned
+** pointers.  In that case, only verify 4-byte alignment.
+*/
+#ifdef SQLITE_4_BYTE_ALIGNED_MALLOC
+# define EIGHT_BYTE_ALIGNMENT(X)   ((((char*)(X) - (char*)0)&3)==0)
+#else
+# define EIGHT_BYTE_ALIGNMENT(X)   ((((char*)(X) - (char*)0)&7)==0)
+#endif
+
+
+/*
+** An instance of the following structure is used to store the busy-handler
+** callback for a given sqlite handle. 
+**
+** The sqlite.busyHandler member of the sqlite struct contains the busy
+** callback for the database handle. Each pager opened via the sqlite
+** handle is passed a pointer to sqlite.busyHandler. The busy-handler
+** callback is currently invoked only from within pager.c.
+*/
+typedef struct BusyHandler BusyHandler;
+struct BusyHandler {
+  int (*xFunc)(void *,int);  /* The busy callback */
+  void *pArg;                /* First arg to busy callback */
+  int nBusy;                 /* Incremented with each busy call */
+};
+
+/*
+** Name of the master database table.  The master database table
+** is a special table that holds the names and attributes of all
+** user tables and indices.
+*/
+#define MASTER_NAME       "sqlite_master"
+#define TEMP_MASTER_NAME  "sqlite_temp_master"
+
+/*
+** The root-page of the master database table.
+*/
+#define MASTER_ROOT       1
+
+/*
+** The name of the schema table.
+*/
+#define SCHEMA_TABLE(x)  ((!OMIT_TEMPDB)&&(x==1)?TEMP_MASTER_NAME:MASTER_NAME)
+
+/*
+** A convenience macro that returns the number of elements in
+** an array.
+*/
+#define ArraySize(X)    ((int)(sizeof(X)/sizeof(X[0])))
+
+/*
+** The following value as a destructor means to use sqlite3DbFree().
+** This is an internal extension to SQLITE_STATIC and SQLITE_TRANSIENT.
+*/
+#define SQLITE_DYNAMIC   ((sqlite3_destructor_type)sqlite3DbFree)
+
+/*
+** When SQLITE_OMIT_WSD is defined, it means that the target platform does
+** not support Writable Static Data (WSD) such as global and static variables.
+** All variables must either be on the stack or dynamically allocated from
+** the heap.  When WSD is unsupported, the variable declarations scattered
+** throughout the SQLite code must become constants instead.  The SQLITE_WSD
+** macro is used for this purpose.  And instead of referencing the variable
+** directly, we use its constant as a key to lookup the run-time allocated
+** buffer that holds real variable.  The constant is also the initializer
+** for the run-time allocated buffer.
+**
+** In the usual case where WSD is supported, the SQLITE_WSD and GLOBAL
+** macros become no-ops and have zero performance impact.
+*/
+#ifdef SQLITE_OMIT_WSD
+  #define SQLITE_WSD const
+  #define GLOBAL(t,v) (*(t*)sqlite3_wsd_find((void*)&(v), sizeof(v)))
+  #define sqlite3GlobalConfig GLOBAL(struct Sqlite3Config, sqlite3Config)
+SQLITE_API   int sqlite3_wsd_init(int N, int J);
+SQLITE_API   void *sqlite3_wsd_find(void *K, int L);
+#else
+  #define SQLITE_WSD 
+  #define GLOBAL(t,v) v
+  #define sqlite3GlobalConfig sqlite3Config
+#endif
+
+/*
+** The following macros are used to suppress compiler warnings and to
+** make it clear to human readers when a function parameter is deliberately 
+** left unused within the body of a function. This usually happens when
+** a function is called via a function pointer. For example the 
+** implementation of an SQL aggregate step callback may not use the
+** parameter indicating the number of arguments passed to the aggregate,
+** if it knows that this is enforced elsewhere.
+**
+** When a function parameter is not used at all within the body of a function,
+** it is generally named "NotUsed" or "NotUsed2" to make things even clearer.
+** However, these macros may also be used to suppress warnings related to
+** parameters that may or may not be used depending on compilation options.
+** For example those parameters only used in assert() statements. In these
+** cases the parameters are named as per the usual conventions.
+*/
+#define UNUSED_PARAMETER(x) (void)(x)
+#define UNUSED_PARAMETER2(x,y) UNUSED_PARAMETER(x),UNUSED_PARAMETER(y)
+
+/*
+** Forward references to structures
+*/
+typedef struct AggInfo AggInfo;
+typedef struct AuthContext AuthContext;
+typedef struct AutoincInfo AutoincInfo;
+typedef struct Bitvec Bitvec;
+typedef struct CollSeq CollSeq;
+typedef struct Column Column;
+typedef struct Db Db;
+typedef struct Schema Schema;
+typedef struct Expr Expr;
+typedef struct ExprList ExprList;
+typedef struct ExprSpan ExprSpan;
+typedef struct FKey FKey;
+typedef struct FuncDestructor FuncDestructor;
+typedef struct FuncDef FuncDef;
+typedef struct FuncDefHash FuncDefHash;
+typedef struct IdList IdList;
+typedef struct Index Index;
+typedef struct IndexSample IndexSample;
+typedef struct KeyClass KeyClass;
+typedef struct KeyInfo KeyInfo;
+typedef struct Lookaside Lookaside;
+typedef struct LookasideSlot LookasideSlot;
+typedef struct Module Module;
+typedef struct NameContext NameContext;
+typedef struct Parse Parse;
+typedef struct RowSet RowSet;
+typedef struct Savepoint Savepoint;
+typedef struct Select Select;
+typedef struct SrcList SrcList;
+typedef struct StrAccum StrAccum;
+typedef struct Table Table;
+typedef struct TableLock TableLock;
+typedef struct Token Token;
+typedef struct Trigger Trigger;
+typedef struct TriggerPrg TriggerPrg;
+typedef struct TriggerStep TriggerStep;
+typedef struct UnpackedRecord UnpackedRecord;
+typedef struct VTable VTable;
+typedef struct Walker Walker;
+typedef struct WherePlan WherePlan;
+typedef struct WhereInfo WhereInfo;
+typedef struct WhereLevel WhereLevel;
+
+/*
+** Defer sourcing vdbe.h and btree.h until after the "u8" and 
+** "BusyHandler" typedefs. vdbe.h also requires a few of the opaque
+** pointer types (i.e. FuncDef) defined above.
+*/
+/************** Include btree.h in the middle of sqliteInt.h *****************/
+/************** Begin file btree.h *******************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This header file defines the interface that the sqlite B-Tree file
+** subsystem.  See comments in the source code for a detailed description
+** of what each interface routine does.
+*/
+#ifndef _BTREE_H_
+#define _BTREE_H_
+
+/* TODO: This definition is just included so other modules compile. It
+** needs to be revisited.
+*/
+#define SQLITE_N_BTREE_META 10
+
+/*
+** If defined as non-zero, auto-vacuum is enabled by default. Otherwise
+** it must be turned on for each database using "PRAGMA auto_vacuum = 1".
+*/
+#ifndef SQLITE_DEFAULT_AUTOVACUUM
+  #define SQLITE_DEFAULT_AUTOVACUUM 0
+#endif
+
+#define BTREE_AUTOVACUUM_NONE 0        /* Do not do auto-vacuum */
+#define BTREE_AUTOVACUUM_FULL 1        /* Do full auto-vacuum */
+#define BTREE_AUTOVACUUM_INCR 2        /* Incremental vacuum */
+
+/*
+** Forward declarations of structure
+*/
+typedef struct Btree Btree;
+typedef struct BtCursor BtCursor;
+typedef struct BtShared BtShared;
+
+
+SQLITE_PRIVATE int sqlite3BtreeOpen(
+  const char *zFilename,   /* Name of database file to open */
+  sqlite3 *db,             /* Associated database connection */
+  Btree **ppBtree,         /* Return open Btree* here */
+  int flags,               /* Flags */
+  int vfsFlags             /* Flags passed through to VFS open */
+);
+
+/* The flags parameter to sqlite3BtreeOpen can be the bitwise or of the
+** following values.
+**
+** NOTE:  These values must match the corresponding PAGER_ values in
+** pager.h.
+*/
+#define BTREE_OMIT_JOURNAL  1  /* Do not create or use a rollback journal */
+#define BTREE_NO_READLOCK   2  /* Omit readlocks on readonly files */
+#define BTREE_MEMORY        4  /* This is an in-memory DB */
+#define BTREE_SINGLE        8  /* The file contains at most 1 b-tree */
+#define BTREE_UNORDERED    16  /* Use of a hash implementation is OK */
+
+SQLITE_PRIVATE int sqlite3BtreeClose(Btree*);
+SQLITE_PRIVATE int sqlite3BtreeSetCacheSize(Btree*,int);
+SQLITE_PRIVATE int sqlite3BtreeSetSafetyLevel(Btree*,int,int,int);
+SQLITE_PRIVATE int sqlite3BtreeSyncDisabled(Btree*);
+SQLITE_PRIVATE int sqlite3BtreeSetPageSize(Btree *p, int nPagesize, int nReserve, int eFix);
+SQLITE_PRIVATE int sqlite3BtreeGetPageSize(Btree*);
+SQLITE_PRIVATE int sqlite3BtreeMaxPageCount(Btree*,int);
+SQLITE_PRIVATE u32 sqlite3BtreeLastPage(Btree*);
+SQLITE_PRIVATE int sqlite3BtreeSecureDelete(Btree*,int);
+SQLITE_PRIVATE int sqlite3BtreeGetReserve(Btree*);
+SQLITE_PRIVATE int sqlite3BtreeSetAutoVacuum(Btree *, int);
+SQLITE_PRIVATE int sqlite3BtreeGetAutoVacuum(Btree *);
+SQLITE_PRIVATE int sqlite3BtreeBeginTrans(Btree*,int);
+SQLITE_PRIVATE int sqlite3BtreeCommitPhaseOne(Btree*, const char *zMaster);
+SQLITE_PRIVATE int sqlite3BtreeCommitPhaseTwo(Btree*, int);
+SQLITE_PRIVATE int sqlite3BtreeCommit(Btree*);
+SQLITE_PRIVATE int sqlite3BtreeRollback(Btree*);
+SQLITE_PRIVATE int sqlite3BtreeBeginStmt(Btree*,int);
+SQLITE_PRIVATE int sqlite3BtreeCreateTable(Btree*, int*, int flags);
+SQLITE_PRIVATE int sqlite3BtreeIsInTrans(Btree*);
+SQLITE_PRIVATE int sqlite3BtreeIsInReadTrans(Btree*);
+SQLITE_PRIVATE int sqlite3BtreeIsInBackup(Btree*);
+SQLITE_PRIVATE void *sqlite3BtreeSchema(Btree *, int, void(*)(void *));
+SQLITE_PRIVATE int sqlite3BtreeSchemaLocked(Btree *pBtree);
+SQLITE_PRIVATE int sqlite3BtreeLockTable(Btree *pBtree, int iTab, u8 isWriteLock);
+SQLITE_PRIVATE int sqlite3BtreeSavepoint(Btree *, int, int);
+
+SQLITE_PRIVATE const char *sqlite3BtreeGetFilename(Btree *);
+SQLITE_PRIVATE const char *sqlite3BtreeGetJournalname(Btree *);
+SQLITE_PRIVATE int sqlite3BtreeCopyFile(Btree *, Btree *);
+
+SQLITE_PRIVATE int sqlite3BtreeIncrVacuum(Btree *);
+
+/* The flags parameter to sqlite3BtreeCreateTable can be the bitwise OR
+** of the flags shown below.
+**
+** Every SQLite table must have either BTREE_INTKEY or BTREE_BLOBKEY set.
+** With BTREE_INTKEY, the table key is a 64-bit integer and arbitrary data
+** is stored in the leaves.  (BTREE_INTKEY is used for SQL tables.)  With
+** BTREE_BLOBKEY, the key is an arbitrary BLOB and no content is stored
+** anywhere - the key is the content.  (BTREE_BLOBKEY is used for SQL
+** indices.)
+*/
+#define BTREE_INTKEY     1    /* Table has only 64-bit signed integer keys */
+#define BTREE_BLOBKEY    2    /* Table has keys only - no data */
+
+SQLITE_PRIVATE int sqlite3BtreeDropTable(Btree*, int, int*);
+SQLITE_PRIVATE int sqlite3BtreeClearTable(Btree*, int, int*);
+SQLITE_PRIVATE void sqlite3BtreeTripAllCursors(Btree*, int);
+
+SQLITE_PRIVATE void sqlite3BtreeGetMeta(Btree *pBtree, int idx, u32 *pValue);
+SQLITE_PRIVATE int sqlite3BtreeUpdateMeta(Btree*, int idx, u32 value);
+
+/*
+** The second parameter to sqlite3BtreeGetMeta or sqlite3BtreeUpdateMeta
+** should be one of the following values. The integer values are assigned 
+** to constants so that the offset of the corresponding field in an
+** SQLite database header may be found using the following formula:
+**
+**   offset = 36 + (idx * 4)
+**
+** For example, the free-page-count field is located at byte offset 36 of
+** the database file header. The incr-vacuum-flag field is located at
+** byte offset 64 (== 36+4*7).
+*/
+#define BTREE_FREE_PAGE_COUNT     0
+#define BTREE_SCHEMA_VERSION      1
+#define BTREE_FILE_FORMAT         2
+#define BTREE_DEFAULT_CACHE_SIZE  3
+#define BTREE_LARGEST_ROOT_PAGE   4
+#define BTREE_TEXT_ENCODING       5
+#define BTREE_USER_VERSION        6
+#define BTREE_INCR_VACUUM         7
+
+SQLITE_PRIVATE int sqlite3BtreeCursor(
+  Btree*,                              /* BTree containing table to open */
+  int iTable,                          /* Index of root page */
+  int wrFlag,                          /* 1 for writing.  0 for read-only */
+  struct KeyInfo*,                     /* First argument to compare function */
+  BtCursor *pCursor                    /* Space to write cursor structure */
+);
+SQLITE_PRIVATE int sqlite3BtreeCursorSize(void);
+SQLITE_PRIVATE void sqlite3BtreeCursorZero(BtCursor*);
+
+SQLITE_PRIVATE int sqlite3BtreeCloseCursor(BtCursor*);
+SQLITE_PRIVATE int sqlite3BtreeMovetoUnpacked(
+  BtCursor*,
+  UnpackedRecord *pUnKey,
+  i64 intKey,
+  int bias,
+  int *pRes
+);
+SQLITE_PRIVATE int sqlite3BtreeCursorHasMoved(BtCursor*, int*);
+SQLITE_PRIVATE int sqlite3BtreeDelete(BtCursor*);
+SQLITE_PRIVATE int sqlite3BtreeInsert(BtCursor*, const void *pKey, i64 nKey,
+                                  const void *pData, int nData,
+                                  int nZero, int bias, int seekResult);
+SQLITE_PRIVATE int sqlite3BtreeFirst(BtCursor*, int *pRes);
+SQLITE_PRIVATE int sqlite3BtreeLast(BtCursor*, int *pRes);
+SQLITE_PRIVATE int sqlite3BtreeNext(BtCursor*, int *pRes);
+SQLITE_PRIVATE int sqlite3BtreeEof(BtCursor*);
+SQLITE_PRIVATE int sqlite3BtreePrevious(BtCursor*, int *pRes);
+SQLITE_PRIVATE int sqlite3BtreeKeySize(BtCursor*, i64 *pSize);
+SQLITE_PRIVATE int sqlite3BtreeKey(BtCursor*, u32 offset, u32 amt, void*);
+SQLITE_PRIVATE const void *sqlite3BtreeKeyFetch(BtCursor*, int *pAmt);
+SQLITE_PRIVATE const void *sqlite3BtreeDataFetch(BtCursor*, int *pAmt);
+SQLITE_PRIVATE int sqlite3BtreeDataSize(BtCursor*, u32 *pSize);
+SQLITE_PRIVATE int sqlite3BtreeData(BtCursor*, u32 offset, u32 amt, void*);
+SQLITE_PRIVATE void sqlite3BtreeSetCachedRowid(BtCursor*, sqlite3_int64);
+SQLITE_PRIVATE sqlite3_int64 sqlite3BtreeGetCachedRowid(BtCursor*);
+
+SQLITE_PRIVATE char *sqlite3BtreeIntegrityCheck(Btree*, int *aRoot, int nRoot, int, int*);
+SQLITE_PRIVATE struct Pager *sqlite3BtreePager(Btree*);
+
+SQLITE_PRIVATE int sqlite3BtreePutData(BtCursor*, u32 offset, u32 amt, void*);
+SQLITE_PRIVATE void sqlite3BtreeCacheOverflow(BtCursor *);
+SQLITE_PRIVATE void sqlite3BtreeClearCursor(BtCursor *);
+
+SQLITE_PRIVATE int sqlite3BtreeSetVersion(Btree *pBt, int iVersion);
+
+#ifndef NDEBUG
+SQLITE_PRIVATE int sqlite3BtreeCursorIsValid(BtCursor*);
+#endif
+
+#ifndef SQLITE_OMIT_BTREECOUNT
+SQLITE_PRIVATE int sqlite3BtreeCount(BtCursor *, i64 *);
+#endif
+
+#ifdef SQLITE_TEST
+SQLITE_PRIVATE int sqlite3BtreeCursorInfo(BtCursor*, int*, int);
+SQLITE_PRIVATE void sqlite3BtreeCursorList(Btree*);
+#endif
+
+#ifndef SQLITE_OMIT_WAL
+SQLITE_PRIVATE   int sqlite3BtreeCheckpoint(Btree*, int, int *, int *);
+#endif
+
+/*
+** If we are not using shared cache, then there is no need to
+** use mutexes to access the BtShared structures.  So make the
+** Enter and Leave procedures no-ops.
+*/
+#ifndef SQLITE_OMIT_SHARED_CACHE
+SQLITE_PRIVATE   void sqlite3BtreeEnter(Btree*);
+SQLITE_PRIVATE   void sqlite3BtreeEnterAll(sqlite3*);
+#else
+# define sqlite3BtreeEnter(X) 
+# define sqlite3BtreeEnterAll(X)
+#endif
+
+#if !defined(SQLITE_OMIT_SHARED_CACHE) && SQLITE_THREADSAFE
+SQLITE_PRIVATE   int sqlite3BtreeSharable(Btree*);
+SQLITE_PRIVATE   void sqlite3BtreeLeave(Btree*);
+SQLITE_PRIVATE   void sqlite3BtreeEnterCursor(BtCursor*);
+SQLITE_PRIVATE   void sqlite3BtreeLeaveCursor(BtCursor*);
+SQLITE_PRIVATE   void sqlite3BtreeLeaveAll(sqlite3*);
+#ifndef NDEBUG
+  /* These routines are used inside assert() statements only. */
+SQLITE_PRIVATE   int sqlite3BtreeHoldsMutex(Btree*);
+SQLITE_PRIVATE   int sqlite3BtreeHoldsAllMutexes(sqlite3*);
+SQLITE_PRIVATE   int sqlite3SchemaMutexHeld(sqlite3*,int,Schema*);
+#endif
+#else
+
+# define sqlite3BtreeSharable(X) 0
+# define sqlite3BtreeLeave(X)
+# define sqlite3BtreeEnterCursor(X)
+# define sqlite3BtreeLeaveCursor(X)
+# define sqlite3BtreeLeaveAll(X)
+
+# define sqlite3BtreeHoldsMutex(X) 1
+# define sqlite3BtreeHoldsAllMutexes(X) 1
+# define sqlite3SchemaMutexHeld(X,Y,Z) 1
+#endif
+
+
+#endif /* _BTREE_H_ */
+
+/************** End of btree.h ***********************************************/
+/************** Continuing where we left off in sqliteInt.h ******************/
+/************** Include vdbe.h in the middle of sqliteInt.h ******************/
+/************** Begin file vdbe.h ********************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** Header file for the Virtual DataBase Engine (VDBE)
+**
+** This header defines the interface to the virtual database engine
+** or VDBE.  The VDBE implements an abstract machine that runs a
+** simple program to access and modify the underlying database.
+*/
+#ifndef _SQLITE_VDBE_H_
+#define _SQLITE_VDBE_H_
+
+/*
+** A single VDBE is an opaque structure named "Vdbe".  Only routines
+** in the source file sqliteVdbe.c are allowed to see the insides
+** of this structure.
+*/
+typedef struct Vdbe Vdbe;
+
+/*
+** The names of the following types declared in vdbeInt.h are required
+** for the VdbeOp definition.
+*/
+typedef struct VdbeFunc VdbeFunc;
+typedef struct Mem Mem;
+typedef struct SubProgram SubProgram;
+
+/*
+** A single instruction of the virtual machine has an opcode
+** and as many as three operands.  The instruction is recorded
+** as an instance of the following structure:
+*/
+struct VdbeOp {
+  u8 opcode;          /* What operation to perform */
+  signed char p4type; /* One of the P4_xxx constants for p4 */
+  u8 opflags;         /* Mask of the OPFLG_* flags in opcodes.h */
+  u8 p5;              /* Fifth parameter is an unsigned character */
+  int p1;             /* First operand */
+  int p2;             /* Second parameter (often the jump destination) */
+  int p3;             /* The third parameter */
+  union {             /* fourth parameter */
+    int i;                 /* Integer value if p4type==P4_INT32 */
+    void *p;               /* Generic pointer */
+    char *z;               /* Pointer to data for string (char array) types */
+    i64 *pI64;             /* Used when p4type is P4_INT64 */
+    double *pReal;         /* Used when p4type is P4_REAL */
+    FuncDef *pFunc;        /* Used when p4type is P4_FUNCDEF */
+    VdbeFunc *pVdbeFunc;   /* Used when p4type is P4_VDBEFUNC */
+    CollSeq *pColl;        /* Used when p4type is P4_COLLSEQ */
+    Mem *pMem;             /* Used when p4type is P4_MEM */
+    VTable *pVtab;         /* Used when p4type is P4_VTAB */
+    KeyInfo *pKeyInfo;     /* Used when p4type is P4_KEYINFO */
+    int *ai;               /* Used when p4type is P4_INTARRAY */
+    SubProgram *pProgram;  /* Used when p4type is P4_SUBPROGRAM */
+  } p4;
+#ifdef SQLITE_DEBUG
+  char *zComment;          /* Comment to improve readability */
+#endif
+#ifdef VDBE_PROFILE
+  int cnt;                 /* Number of times this instruction was executed */
+  u64 cycles;              /* Total time spent executing this instruction */
+#endif
+};
+typedef struct VdbeOp VdbeOp;
+
+
+/*
+** A sub-routine used to implement a trigger program.
+*/
+struct SubProgram {
+  VdbeOp *aOp;                  /* Array of opcodes for sub-program */
+  int nOp;                      /* Elements in aOp[] */
+  int nMem;                     /* Number of memory cells required */
+  int nCsr;                     /* Number of cursors required */
+  void *token;                  /* id that may be used to recursive triggers */
+  SubProgram *pNext;            /* Next sub-program already visited */
+};
+
+/*
+** A smaller version of VdbeOp used for the VdbeAddOpList() function because
+** it takes up less space.
+*/
+struct VdbeOpList {
+  u8 opcode;          /* What operation to perform */
+  signed char p1;     /* First operand */
+  signed char p2;     /* Second parameter (often the jump destination) */
+  signed char p3;     /* Third parameter */
+};
+typedef struct VdbeOpList VdbeOpList;
+
+/*
+** Allowed values of VdbeOp.p4type
+*/
+#define P4_NOTUSED    0   /* The P4 parameter is not used */
+#define P4_DYNAMIC  (-1)  /* Pointer to a string obtained from sqliteMalloc() */
+#define P4_STATIC   (-2)  /* Pointer to a static string */
+#define P4_COLLSEQ  (-4)  /* P4 is a pointer to a CollSeq structure */
+#define P4_FUNCDEF  (-5)  /* P4 is a pointer to a FuncDef structure */
+#define P4_KEYINFO  (-6)  /* P4 is a pointer to a KeyInfo structure */
+#define P4_VDBEFUNC (-7)  /* P4 is a pointer to a VdbeFunc structure */
+#define P4_MEM      (-8)  /* P4 is a pointer to a Mem*    structure */
+#define P4_TRANSIENT  0   /* P4 is a pointer to a transient string */
+#define P4_VTAB     (-10) /* P4 is a pointer to an sqlite3_vtab structure */
+#define P4_MPRINTF  (-11) /* P4 is a string obtained from sqlite3_mprintf() */
+#define P4_REAL     (-12) /* P4 is a 64-bit floating point value */
+#define P4_INT64    (-13) /* P4 is a 64-bit signed integer */
+#define P4_INT32    (-14) /* P4 is a 32-bit signed integer */
+#define P4_INTARRAY (-15) /* P4 is a vector of 32-bit integers */
+#define P4_SUBPROGRAM  (-18) /* P4 is a pointer to a SubProgram structure */
+
+/* When adding a P4 argument using P4_KEYINFO, a copy of the KeyInfo structure
+** is made.  That copy is freed when the Vdbe is finalized.  But if the
+** argument is P4_KEYINFO_HANDOFF, the passed in pointer is used.  It still
+** gets freed when the Vdbe is finalized so it still should be obtained
+** from a single sqliteMalloc().  But no copy is made and the calling
+** function should *not* try to free the KeyInfo.
+*/
+#define P4_KEYINFO_HANDOFF (-16)
+#define P4_KEYINFO_STATIC  (-17)
+
+/*
+** The Vdbe.aColName array contains 5n Mem structures, where n is the 
+** number of columns of data returned by the statement.
+*/
+#define COLNAME_NAME     0
+#define COLNAME_DECLTYPE 1
+#define COLNAME_DATABASE 2
+#define COLNAME_TABLE    3
+#define COLNAME_COLUMN   4
+#ifdef SQLITE_ENABLE_COLUMN_METADATA
+# define COLNAME_N        5      /* Number of COLNAME_xxx symbols */
+#else
+# ifdef SQLITE_OMIT_DECLTYPE
+#   define COLNAME_N      1      /* Store only the name */
+# else
+#   define COLNAME_N      2      /* Store the name and decltype */
+# endif
+#endif
+
+/*
+** The following macro converts a relative address in the p2 field
+** of a VdbeOp structure into a negative number so that 
+** sqlite3VdbeAddOpList() knows that the address is relative.  Calling
+** the macro again restores the address.
+*/
+#define ADDR(X)  (-1-(X))
+
+/*
+** The makefile scans the vdbe.c source file and creates the "opcodes.h"
+** header file that defines a number for each opcode used by the VDBE.
+*/
+/************** Include opcodes.h in the middle of vdbe.h ********************/
+/************** Begin file opcodes.h *****************************************/
+/* Automatically generated.  Do not edit */
+/* See the mkopcodeh.awk script for details */
+#define OP_Goto                                 1
+#define OP_Gosub                                2
+#define OP_Return                               3
+#define OP_Yield                                4
+#define OP_HaltIfNull                           5
+#define OP_Halt                                 6
+#define OP_Integer                              7
+#define OP_Int64                                8
+#define OP_Real                               130   /* same as TK_FLOAT    */
+#define OP_String8                             94   /* same as TK_STRING   */
+#define OP_String                               9
+#define OP_Null                                10
+#define OP_Blob                                11
+#define OP_Variable                            12
+#define OP_Move                                13
+#define OP_Copy                                14
+#define OP_SCopy                               15
+#define OP_ResultRow                           16
+#define OP_Concat                              91   /* same as TK_CONCAT   */
+#define OP_Add                                 86   /* same as TK_PLUS     */
+#define OP_Subtract                            87   /* same as TK_MINUS    */
+#define OP_Multiply                            88   /* same as TK_STAR     */
+#define OP_Divide                              89   /* same as TK_SLASH    */
+#define OP_Remainder                           90   /* same as TK_REM      */
+#define OP_CollSeq                             17
+#define OP_Function                            18
+#define OP_BitAnd                              82   /* same as TK_BITAND   */
+#define OP_BitOr                               83   /* same as TK_BITOR    */
+#define OP_ShiftLeft                           84   /* same as TK_LSHIFT   */
+#define OP_ShiftRight                          85   /* same as TK_RSHIFT   */
+#define OP_AddImm                              20
+#define OP_MustBeInt                           21
+#define OP_RealAffinity                        22
+#define OP_ToText                             141   /* same as TK_TO_TEXT  */
+#define OP_ToBlob                             142   /* same as TK_TO_BLOB  */
+#define OP_ToNumeric                          143   /* same as TK_TO_NUMERIC*/
+#define OP_ToInt                              144   /* same as TK_TO_INT   */
+#define OP_ToReal                             145   /* same as TK_TO_REAL  */
+#define OP_Eq                                  76   /* same as TK_EQ       */
+#define OP_Ne                                  75   /* same as TK_NE       */
+#define OP_Lt                                  79   /* same as TK_LT       */
+#define OP_Le                                  78   /* same as TK_LE       */
+#define OP_Gt                                  77   /* same as TK_GT       */
+#define OP_Ge                                  80   /* same as TK_GE       */
+#define OP_Permutation                         23
+#define OP_Compare                             24
+#define OP_Jump                                25
+#define OP_And                                 69   /* same as TK_AND      */
+#define OP_Or                                  68   /* same as TK_OR       */
+#define OP_Not                                 19   /* same as TK_NOT      */
+#define OP_BitNot                              93   /* same as TK_BITNOT   */
+#define OP_If                                  26
+#define OP_IfNot                               27
+#define OP_IsNull                              73   /* same as TK_ISNULL   */
+#define OP_NotNull                             74   /* same as TK_NOTNULL  */
+#define OP_Column                              28
+#define OP_Affinity                            29
+#define OP_MakeRecord                          30
+#define OP_Count                               31
+#define OP_Savepoint                           32
+#define OP_AutoCommit                          33
+#define OP_Transaction                         34
+#define OP_ReadCookie                          35
+#define OP_SetCookie                           36
+#define OP_VerifyCookie                        37
+#define OP_OpenRead                            38
+#define OP_OpenWrite                           39
+#define OP_OpenAutoindex                       40
+#define OP_OpenEphemeral                       41
+#define OP_OpenPseudo                          42
+#define OP_Close                               43
+#define OP_SeekLt                              44
+#define OP_SeekLe                              45
+#define OP_SeekGe                              46
+#define OP_SeekGt                              47
+#define OP_Seek                                48
+#define OP_NotFound                            49
+#define OP_Found                               50
+#define OP_IsUnique                            51
+#define OP_NotExists                           52
+#define OP_Sequence                            53
+#define OP_NewRowid                            54
+#define OP_Insert                              55
+#define OP_InsertInt                           56
+#define OP_Delete                              57
+#define OP_ResetCount                          58
+#define OP_RowKey                              59
+#define OP_RowData                             60
+#define OP_Rowid                               61
+#define OP_NullRow                             62
+#define OP_Last                                63
+#define OP_Sort                                64
+#define OP_Rewind                              65
+#define OP_Prev                                66
+#define OP_Next                                67
+#define OP_IdxInsert                           70
+#define OP_IdxDelete                           71
+#define OP_IdxRowid                            72
+#define OP_IdxLT                               81
+#define OP_IdxGE                               92
+#define OP_Destroy                             95
+#define OP_Clear                               96
+#define OP_CreateIndex                         97
+#define OP_CreateTable                         98
+#define OP_ParseSchema                         99
+#define OP_LoadAnalysis                       100
+#define OP_DropTable                          101
+#define OP_DropIndex                          102
+#define OP_DropTrigger                        103
+#define OP_IntegrityCk                        104
+#define OP_RowSetAdd                          105
+#define OP_RowSetRead                         106
+#define OP_RowSetTest                         107
+#define OP_Program                            108
+#define OP_Param                              109
+#define OP_FkCounter                          110
+#define OP_FkIfZero                           111
+#define OP_MemMax                             112
+#define OP_IfPos                              113
+#define OP_IfNeg                              114
+#define OP_IfZero                             115
+#define OP_AggStep                            116
+#define OP_AggFinal                           117
+#define OP_Checkpoint                         118
+#define OP_JournalMode                        119
+#define OP_Vacuum                             120
+#define OP_IncrVacuum                         121
+#define OP_Expire                             122
+#define OP_TableLock                          123
+#define OP_VBegin                             124
+#define OP_VCreate                            125
+#define OP_VDestroy                           126
+#define OP_VOpen                              127
+#define OP_VFilter                            128
+#define OP_VColumn                            129
+#define OP_VNext                              131
+#define OP_VRename                            132
+#define OP_VUpdate                            133
+#define OP_Pagecount                          134
+#define OP_MaxPgcnt                           135
+#define OP_Trace                              136
+#define OP_Noop                               137
+#define OP_Explain                            138
+
+/* The following opcode values are never used */
+#define OP_NotUsed_139                        139
+#define OP_NotUsed_140                        140
+
+
+/* Properties such as "out2" or "jump" that are specified in
+** comments following the "case" for each opcode in the vdbe.c
+** are encoded into bitvectors as follows:
+*/
+#define OPFLG_JUMP            0x0001  /* jump:  P2 holds jmp target */
+#define OPFLG_OUT2_PRERELEASE 0x0002  /* out2-prerelease: */
+#define OPFLG_IN1             0x0004  /* in1:   P1 is an input */
+#define OPFLG_IN2             0x0008  /* in2:   P2 is an input */
+#define OPFLG_IN3             0x0010  /* in3:   P3 is an input */
+#define OPFLG_OUT2            0x0020  /* out2:  P2 is an output */
+#define OPFLG_OUT3            0x0040  /* out3:  P3 is an output */
+#define OPFLG_INITIALIZER {\
+/*   0 */ 0x00, 0x01, 0x05, 0x04, 0x04, 0x10, 0x00, 0x02,\
+/*   8 */ 0x02, 0x02, 0x02, 0x02, 0x02, 0x00, 0x24, 0x24,\
+/*  16 */ 0x00, 0x00, 0x00, 0x24, 0x04, 0x05, 0x04, 0x00,\
+/*  24 */ 0x00, 0x01, 0x05, 0x05, 0x00, 0x00, 0x00, 0x02,\
+/*  32 */ 0x00, 0x00, 0x00, 0x02, 0x10, 0x00, 0x00, 0x00,\
+/*  40 */ 0x00, 0x00, 0x00, 0x00, 0x11, 0x11, 0x11, 0x11,\
+/*  48 */ 0x08, 0x11, 0x11, 0x11, 0x11, 0x02, 0x02, 0x00,\
+/*  56 */ 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x01,\
+/*  64 */ 0x01, 0x01, 0x01, 0x01, 0x4c, 0x4c, 0x08, 0x00,\
+/*  72 */ 0x02, 0x05, 0x05, 0x15, 0x15, 0x15, 0x15, 0x15,\
+/*  80 */ 0x15, 0x01, 0x4c, 0x4c, 0x4c, 0x4c, 0x4c, 0x4c,\
+/*  88 */ 0x4c, 0x4c, 0x4c, 0x4c, 0x01, 0x24, 0x02, 0x02,\
+/*  96 */ 0x00, 0x02, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00,\
+/* 104 */ 0x00, 0x0c, 0x45, 0x15, 0x01, 0x02, 0x00, 0x01,\
+/* 112 */ 0x08, 0x05, 0x05, 0x05, 0x00, 0x00, 0x00, 0x02,\
+/* 120 */ 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,\
+/* 128 */ 0x01, 0x00, 0x02, 0x01, 0x00, 0x00, 0x02, 0x02,\
+/* 136 */ 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x04, 0x04,\
+/* 144 */ 0x04, 0x04,}
+
+/************** End of opcodes.h *********************************************/
+/************** Continuing where we left off in vdbe.h ***********************/
+
+/*
+** Prototypes for the VDBE interface.  See comments on the implementation
+** for a description of what each of these routines does.
+*/
+SQLITE_PRIVATE Vdbe *sqlite3VdbeCreate(sqlite3*);
+SQLITE_PRIVATE int sqlite3VdbeAddOp0(Vdbe*,int);
+SQLITE_PRIVATE int sqlite3VdbeAddOp1(Vdbe*,int,int);
+SQLITE_PRIVATE int sqlite3VdbeAddOp2(Vdbe*,int,int,int);
+SQLITE_PRIVATE int sqlite3VdbeAddOp3(Vdbe*,int,int,int,int);
+SQLITE_PRIVATE int sqlite3VdbeAddOp4(Vdbe*,int,int,int,int,const char *zP4,int);
+SQLITE_PRIVATE int sqlite3VdbeAddOp4Int(Vdbe*,int,int,int,int,int);
+SQLITE_PRIVATE int sqlite3VdbeAddOpList(Vdbe*, int nOp, VdbeOpList const *aOp);
+SQLITE_PRIVATE void sqlite3VdbeChangeP1(Vdbe*, int addr, int P1);
+SQLITE_PRIVATE void sqlite3VdbeChangeP2(Vdbe*, int addr, int P2);
+SQLITE_PRIVATE void sqlite3VdbeChangeP3(Vdbe*, int addr, int P3);
+SQLITE_PRIVATE void sqlite3VdbeChangeP5(Vdbe*, u8 P5);
+SQLITE_PRIVATE void sqlite3VdbeJumpHere(Vdbe*, int addr);
+SQLITE_PRIVATE void sqlite3VdbeChangeToNoop(Vdbe*, int addr, int N);
+SQLITE_PRIVATE void sqlite3VdbeChangeP4(Vdbe*, int addr, const char *zP4, int N);
+SQLITE_PRIVATE void sqlite3VdbeUsesBtree(Vdbe*, int);
+SQLITE_PRIVATE VdbeOp *sqlite3VdbeGetOp(Vdbe*, int);
+SQLITE_PRIVATE int sqlite3VdbeMakeLabel(Vdbe*);
+SQLITE_PRIVATE void sqlite3VdbeRunOnlyOnce(Vdbe*);
+SQLITE_PRIVATE void sqlite3VdbeDelete(Vdbe*);
+SQLITE_PRIVATE void sqlite3VdbeDeleteObject(sqlite3*,Vdbe*);
+SQLITE_PRIVATE void sqlite3VdbeMakeReady(Vdbe*,int,int,int,int,int,int);
+SQLITE_PRIVATE int sqlite3VdbeFinalize(Vdbe*);
+SQLITE_PRIVATE void sqlite3VdbeResolveLabel(Vdbe*, int);
+SQLITE_PRIVATE int sqlite3VdbeCurrentAddr(Vdbe*);
+#ifdef SQLITE_DEBUG
+SQLITE_PRIVATE   int sqlite3VdbeAssertMayAbort(Vdbe *, int);
+SQLITE_PRIVATE   void sqlite3VdbeTrace(Vdbe*,FILE*);
+#endif
+SQLITE_PRIVATE void sqlite3VdbeResetStepResult(Vdbe*);
+SQLITE_PRIVATE int sqlite3VdbeReset(Vdbe*);
+SQLITE_PRIVATE void sqlite3VdbeSetNumCols(Vdbe*,int);
+SQLITE_PRIVATE int sqlite3VdbeSetColName(Vdbe*, int, int, const char *, void(*)(void*));
+SQLITE_PRIVATE void sqlite3VdbeCountChanges(Vdbe*);
+SQLITE_PRIVATE sqlite3 *sqlite3VdbeDb(Vdbe*);
+SQLITE_PRIVATE void sqlite3VdbeSetSql(Vdbe*, const char *z, int n, int);
+SQLITE_PRIVATE void sqlite3VdbeSwap(Vdbe*,Vdbe*);
+SQLITE_PRIVATE VdbeOp *sqlite3VdbeTakeOpArray(Vdbe*, int*, int*);
+SQLITE_PRIVATE sqlite3_value *sqlite3VdbeGetValue(Vdbe*, int, u8);
+SQLITE_PRIVATE void sqlite3VdbeSetVarmask(Vdbe*, int);
+#ifndef SQLITE_OMIT_TRACE
+SQLITE_PRIVATE   char *sqlite3VdbeExpandSql(Vdbe*, const char*);
+#endif
+
+SQLITE_PRIVATE UnpackedRecord *sqlite3VdbeRecordUnpack(KeyInfo*,int,const void*,char*,int);
+SQLITE_PRIVATE void sqlite3VdbeDeleteUnpackedRecord(UnpackedRecord*);
+SQLITE_PRIVATE int sqlite3VdbeRecordCompare(int,const void*,UnpackedRecord*);
+
+#ifndef SQLITE_OMIT_TRIGGER
+SQLITE_PRIVATE void sqlite3VdbeLinkSubProgram(Vdbe *, SubProgram *);
+#endif
+
+
+#ifndef NDEBUG
+SQLITE_PRIVATE   void sqlite3VdbeComment(Vdbe*, const char*, ...);
+# define VdbeComment(X)  sqlite3VdbeComment X
+SQLITE_PRIVATE   void sqlite3VdbeNoopComment(Vdbe*, const char*, ...);
+# define VdbeNoopComment(X)  sqlite3VdbeNoopComment X
+#else
+# define VdbeComment(X)
+# define VdbeNoopComment(X)
+#endif
+
+#endif
+
+/************** End of vdbe.h ************************************************/
+/************** Continuing where we left off in sqliteInt.h ******************/
+/************** Include pager.h in the middle of sqliteInt.h *****************/
+/************** Begin file pager.h *******************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This header file defines the interface that the sqlite page cache
+** subsystem.  The page cache subsystem reads and writes a file a page
+** at a time and provides a journal for rollback.
+*/
+
+#ifndef _PAGER_H_
+#define _PAGER_H_
+
+/*
+** Default maximum size for persistent journal files. A negative 
+** value means no limit. This value may be overridden using the 
+** sqlite3PagerJournalSizeLimit() API. See also "PRAGMA journal_size_limit".
+*/
+#ifndef SQLITE_DEFAULT_JOURNAL_SIZE_LIMIT
+  #define SQLITE_DEFAULT_JOURNAL_SIZE_LIMIT -1
+#endif
+
+/*
+** The type used to represent a page number.  The first page in a file
+** is called page 1.  0 is used to represent "not a page".
+*/
+typedef u32 Pgno;
+
+/*
+** Each open file is managed by a separate instance of the "Pager" structure.
+*/
+typedef struct Pager Pager;
+
+/*
+** Handle type for pages.
+*/
+typedef struct PgHdr DbPage;
+
+/*
+** Page number PAGER_MJ_PGNO is never used in an SQLite database (it is
+** reserved for working around a windows/posix incompatibility). It is
+** used in the journal to signify that the remainder of the journal file 
+** is devoted to storing a master journal name - there are no more pages to
+** roll back. See comments for function writeMasterJournal() in pager.c 
+** for details.
+*/
+#define PAGER_MJ_PGNO(x) ((Pgno)((PENDING_BYTE/((x)->pageSize))+1))
+
+/*
+** Allowed values for the flags parameter to sqlite3PagerOpen().
+**
+** NOTE: These values must match the corresponding BTREE_ values in btree.h.
+*/
+#define PAGER_OMIT_JOURNAL  0x0001    /* Do not use a rollback journal */
+#define PAGER_NO_READLOCK   0x0002    /* Omit readlocks on readonly files */
+#define PAGER_MEMORY        0x0004    /* In-memory database */
+
+/*
+** Valid values for the second argument to sqlite3PagerLockingMode().
+*/
+#define PAGER_LOCKINGMODE_QUERY      -1
+#define PAGER_LOCKINGMODE_NORMAL      0
+#define PAGER_LOCKINGMODE_EXCLUSIVE   1
+
+/*
+** Numeric constants that encode the journalmode.  
+*/
+#define PAGER_JOURNALMODE_QUERY     (-1)  /* Query the value of journalmode */
+#define PAGER_JOURNALMODE_DELETE      0   /* Commit by deleting journal file */
+#define PAGER_JOURNALMODE_PERSIST     1   /* Commit by zeroing journal header */
+#define PAGER_JOURNALMODE_OFF         2   /* Journal omitted.  */
+#define PAGER_JOURNALMODE_TRUNCATE    3   /* Commit by truncating journal */
+#define PAGER_JOURNALMODE_MEMORY      4   /* In-memory journal file */
+#define PAGER_JOURNALMODE_WAL         5   /* Use write-ahead logging */
+
+/*
+** The remainder of this file contains the declarations of the functions
+** that make up the Pager sub-system API. See source code comments for 
+** a detailed description of each routine.
+*/
+
+/* Open and close a Pager connection. */ 
+SQLITE_PRIVATE int sqlite3PagerOpen(
+  sqlite3_vfs*,
+  Pager **ppPager,
+  const char*,
+  int,
+  int,
+  int,
+  void(*)(DbPage*)
+);
+SQLITE_PRIVATE int sqlite3PagerClose(Pager *pPager);
+SQLITE_PRIVATE int sqlite3PagerReadFileheader(Pager*, int, unsigned char*);
+
+/* Functions used to configure a Pager object. */
+SQLITE_PRIVATE void sqlite3PagerSetBusyhandler(Pager*, int(*)(void *), void *);
+SQLITE_PRIVATE int sqlite3PagerSetPagesize(Pager*, u32*, int);
+SQLITE_PRIVATE int sqlite3PagerMaxPageCount(Pager*, int);
+SQLITE_PRIVATE void sqlite3PagerSetCachesize(Pager*, int);
+SQLITE_PRIVATE void sqlite3PagerSetSafetyLevel(Pager*,int,int,int);
+SQLITE_PRIVATE int sqlite3PagerLockingMode(Pager *, int);
+SQLITE_PRIVATE int sqlite3PagerSetJournalMode(Pager *, int);
+SQLITE_PRIVATE int sqlite3PagerGetJournalMode(Pager*);
+SQLITE_PRIVATE int sqlite3PagerOkToChangeJournalMode(Pager*);
+SQLITE_PRIVATE i64 sqlite3PagerJournalSizeLimit(Pager *, i64);
+SQLITE_PRIVATE sqlite3_backup **sqlite3PagerBackupPtr(Pager*);
+
+/* Functions used to obtain and release page references. */ 
+SQLITE_PRIVATE int sqlite3PagerAcquire(Pager *pPager, Pgno pgno, DbPage **ppPage, int clrFlag);
+#define sqlite3PagerGet(A,B,C) sqlite3PagerAcquire(A,B,C,0)
+SQLITE_PRIVATE DbPage *sqlite3PagerLookup(Pager *pPager, Pgno pgno);
+SQLITE_PRIVATE void sqlite3PagerRef(DbPage*);
+SQLITE_PRIVATE void sqlite3PagerUnref(DbPage*);
+
+/* Operations on page references. */
+SQLITE_PRIVATE int sqlite3PagerWrite(DbPage*);
+SQLITE_PRIVATE void sqlite3PagerDontWrite(DbPage*);
+SQLITE_PRIVATE int sqlite3PagerMovepage(Pager*,DbPage*,Pgno,int);
+SQLITE_PRIVATE int sqlite3PagerPageRefcount(DbPage*);
+SQLITE_PRIVATE void *sqlite3PagerGetData(DbPage *); 
+SQLITE_PRIVATE void *sqlite3PagerGetExtra(DbPage *); 
+
+/* Functions used to manage pager transactions and savepoints. */
+SQLITE_PRIVATE void sqlite3PagerPagecount(Pager*, int*);
+SQLITE_PRIVATE int sqlite3PagerBegin(Pager*, int exFlag, int);
+SQLITE_PRIVATE int sqlite3PagerCommitPhaseOne(Pager*,const char *zMaster, int);
+SQLITE_PRIVATE int sqlite3PagerExclusiveLock(Pager*);
+SQLITE_PRIVATE int sqlite3PagerSync(Pager *pPager);
+SQLITE_PRIVATE int sqlite3PagerCommitPhaseTwo(Pager*);
+SQLITE_PRIVATE int sqlite3PagerRollback(Pager*);
+SQLITE_PRIVATE int sqlite3PagerOpenSavepoint(Pager *pPager, int n);
+SQLITE_PRIVATE int sqlite3PagerSavepoint(Pager *pPager, int op, int iSavepoint);
+SQLITE_PRIVATE int sqlite3PagerSharedLock(Pager *pPager);
+
+SQLITE_PRIVATE int sqlite3PagerCheckpoint(Pager *pPager, int, int*, int*);
+SQLITE_PRIVATE int sqlite3PagerWalSupported(Pager *pPager);
+SQLITE_PRIVATE int sqlite3PagerWalCallback(Pager *pPager);
+SQLITE_PRIVATE int sqlite3PagerOpenWal(Pager *pPager, int *pisOpen);
+SQLITE_PRIVATE int sqlite3PagerCloseWal(Pager *pPager);
+
+/* Functions used to query pager state and configuration. */
+SQLITE_PRIVATE u8 sqlite3PagerIsreadonly(Pager*);
+SQLITE_PRIVATE int sqlite3PagerRefcount(Pager*);
+SQLITE_PRIVATE int sqlite3PagerMemUsed(Pager*);
+SQLITE_PRIVATE const char *sqlite3PagerFilename(Pager*);
+SQLITE_PRIVATE const sqlite3_vfs *sqlite3PagerVfs(Pager*);
+SQLITE_PRIVATE sqlite3_file *sqlite3PagerFile(Pager*);
+SQLITE_PRIVATE const char *sqlite3PagerJournalname(Pager*);
+SQLITE_PRIVATE int sqlite3PagerNosync(Pager*);
+SQLITE_PRIVATE void *sqlite3PagerTempSpace(Pager*);
+SQLITE_PRIVATE int sqlite3PagerIsMemdb(Pager*);
+
+/* Functions used to truncate the database file. */
+SQLITE_PRIVATE void sqlite3PagerTruncateImage(Pager*,Pgno);
+
+#if defined(SQLITE_HAS_CODEC) && !defined(SQLITE_OMIT_WAL)
+SQLITE_PRIVATE void *sqlite3PagerCodec(DbPage *);
+#endif
+
+/* Functions to support testing and debugging. */
+#if !defined(NDEBUG) || defined(SQLITE_TEST)
+SQLITE_PRIVATE   Pgno sqlite3PagerPagenumber(DbPage*);
+SQLITE_PRIVATE   int sqlite3PagerIswriteable(DbPage*);
+#endif
+#ifdef SQLITE_TEST
+SQLITE_PRIVATE   int *sqlite3PagerStats(Pager*);
+SQLITE_PRIVATE   void sqlite3PagerRefdump(Pager*);
+  void disable_simulated_io_errors(void);
+  void enable_simulated_io_errors(void);
+#else
+# define disable_simulated_io_errors()
+# define enable_simulated_io_errors()
+#endif
+
+#endif /* _PAGER_H_ */
+
+/************** End of pager.h ***********************************************/
+/************** Continuing where we left off in sqliteInt.h ******************/
+/************** Include pcache.h in the middle of sqliteInt.h ****************/
+/************** Begin file pcache.h ******************************************/
+/*
+** 2008 August 05
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This header file defines the interface that the sqlite page cache
+** subsystem. 
+*/
+
+#ifndef _PCACHE_H_
+
+typedef struct PgHdr PgHdr;
+typedef struct PCache PCache;
+
+/*
+** Every page in the cache is controlled by an instance of the following
+** structure.
+*/
+struct PgHdr {
+  void *pData;                   /* Content of this page */
+  void *pExtra;                  /* Extra content */
+  PgHdr *pDirty;                 /* Transient list of dirty pages */
+  Pgno pgno;                     /* Page number for this page */
+  Pager *pPager;                 /* The pager this page is part of */
+#ifdef SQLITE_CHECK_PAGES
+  u32 pageHash;                  /* Hash of page content */
+#endif
+  u16 flags;                     /* PGHDR flags defined below */
+
+  /**********************************************************************
+  ** Elements above are public.  All that follows is private to pcache.c
+  ** and should not be accessed by other modules.
+  */
+  i16 nRef;                      /* Number of users of this page */
+  PCache *pCache;                /* Cache that owns this page */
+
+  PgHdr *pDirtyNext;             /* Next element in list of dirty pages */
+  PgHdr *pDirtyPrev;             /* Previous element in list of dirty pages */
+};
+
+/* Bit values for PgHdr.flags */
+#define PGHDR_DIRTY             0x002  /* Page has changed */
+#define PGHDR_NEED_SYNC         0x004  /* Fsync the rollback journal before
+                                       ** writing this page to the database */
+#define PGHDR_NEED_READ         0x008  /* Content is unread */
+#define PGHDR_REUSE_UNLIKELY    0x010  /* A hint that reuse is unlikely */
+#define PGHDR_DONT_WRITE        0x020  /* Do not write content to disk */
+
+/* Initialize and shutdown the page cache subsystem */
+SQLITE_PRIVATE int sqlite3PcacheInitialize(void);
+SQLITE_PRIVATE void sqlite3PcacheShutdown(void);
+
+/* Page cache buffer management:
+** These routines implement SQLITE_CONFIG_PAGECACHE.
+*/
+SQLITE_PRIVATE void sqlite3PCacheBufferSetup(void *, int sz, int n);
+
+/* Create a new pager cache.
+** Under memory stress, invoke xStress to try to make pages clean.
+** Only clean and unpinned pages can be reclaimed.
+*/
+SQLITE_PRIVATE void sqlite3PcacheOpen(
+  int szPage,                    /* Size of every page */
+  int szExtra,                   /* Extra space associated with each page */
+  int bPurgeable,                /* True if pages are on backing store */
+  int (*xStress)(void*, PgHdr*), /* Call to try to make pages clean */
+  void *pStress,                 /* Argument to xStress */
+  PCache *pToInit                /* Preallocated space for the PCache */
+);
+
+/* Modify the page-size after the cache has been created. */
+SQLITE_PRIVATE void sqlite3PcacheSetPageSize(PCache *, int);
+
+/* Return the size in bytes of a PCache object.  Used to preallocate
+** storage space.
+*/
+SQLITE_PRIVATE int sqlite3PcacheSize(void);
+
+/* One release per successful fetch.  Page is pinned until released.
+** Reference counted. 
+*/
+SQLITE_PRIVATE int sqlite3PcacheFetch(PCache*, Pgno, int createFlag, PgHdr**);
+SQLITE_PRIVATE void sqlite3PcacheRelease(PgHdr*);
+
+SQLITE_PRIVATE void sqlite3PcacheDrop(PgHdr*);         /* Remove page from cache */
+SQLITE_PRIVATE void sqlite3PcacheMakeDirty(PgHdr*);    /* Make sure page is marked dirty */
+SQLITE_PRIVATE void sqlite3PcacheMakeClean(PgHdr*);    /* Mark a single page as clean */
+SQLITE_PRIVATE void sqlite3PcacheCleanAll(PCache*);    /* Mark all dirty list pages as clean */
+
+/* Change a page number.  Used by incr-vacuum. */
+SQLITE_PRIVATE void sqlite3PcacheMove(PgHdr*, Pgno);
+
+/* Remove all pages with pgno>x.  Reset the cache if x==0 */
+SQLITE_PRIVATE void sqlite3PcacheTruncate(PCache*, Pgno x);
+
+/* Get a list of all dirty pages in the cache, sorted by page number */
+SQLITE_PRIVATE PgHdr *sqlite3PcacheDirtyList(PCache*);
+
+/* Reset and close the cache object */
+SQLITE_PRIVATE void sqlite3PcacheClose(PCache*);
+
+/* Clear flags from pages of the page cache */
+SQLITE_PRIVATE void sqlite3PcacheClearSyncFlags(PCache *);
+
+/* Discard the contents of the cache */
+SQLITE_PRIVATE void sqlite3PcacheClear(PCache*);
+
+/* Return the total number of outstanding page references */
+SQLITE_PRIVATE int sqlite3PcacheRefCount(PCache*);
+
+/* Increment the reference count of an existing page */
+SQLITE_PRIVATE void sqlite3PcacheRef(PgHdr*);
+
+SQLITE_PRIVATE int sqlite3PcachePageRefcount(PgHdr*);
+
+/* Return the total number of pages stored in the cache */
+SQLITE_PRIVATE int sqlite3PcachePagecount(PCache*);
+
+#if defined(SQLITE_CHECK_PAGES) || defined(SQLITE_DEBUG)
+/* Iterate through all dirty pages currently stored in the cache. This
+** interface is only available if SQLITE_CHECK_PAGES is defined when the 
+** library is built.
+*/
+SQLITE_PRIVATE void sqlite3PcacheIterateDirty(PCache *pCache, void (*xIter)(PgHdr *));
+#endif
+
+/* Set and get the suggested cache-size for the specified pager-cache.
+**
+** If no global maximum is configured, then the system attempts to limit
+** the total number of pages cached by purgeable pager-caches to the sum
+** of the suggested cache-sizes.
+*/
+SQLITE_PRIVATE void sqlite3PcacheSetCachesize(PCache *, int);
+#ifdef SQLITE_TEST
+SQLITE_PRIVATE int sqlite3PcacheGetCachesize(PCache *);
+#endif
+
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+/* Try to return memory used by the pcache module to the main memory heap */
+SQLITE_PRIVATE int sqlite3PcacheReleaseMemory(int);
+#endif
+
+#ifdef SQLITE_TEST
+SQLITE_PRIVATE void sqlite3PcacheStats(int*,int*,int*,int*);
+#endif
+
+SQLITE_PRIVATE void sqlite3PCacheSetDefault(void);
+
+#endif /* _PCACHE_H_ */
+
+/************** End of pcache.h **********************************************/
+/************** Continuing where we left off in sqliteInt.h ******************/
+
+/************** Include os.h in the middle of sqliteInt.h ********************/
+/************** Begin file os.h **********************************************/
+/*
+** 2001 September 16
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This header file (together with is companion C source-code file
+** "os.c") attempt to abstract the underlying operating system so that
+** the SQLite library will work on both POSIX and windows systems.
+**
+** This header file is #include-ed by sqliteInt.h and thus ends up
+** being included by every source file.
+*/
+#ifndef _SQLITE_OS_H_
+#define _SQLITE_OS_H_
+
+/*
+** Figure out if we are dealing with Unix, Windows, or some other
+** operating system.  After the following block of preprocess macros,
+** all of SQLITE_OS_UNIX, SQLITE_OS_WIN, SQLITE_OS_OS2, and SQLITE_OS_OTHER 
+** will defined to either 1 or 0.  One of the four will be 1.  The other 
+** three will be 0.
+*/
+#if defined(SQLITE_OS_OTHER)
+# if SQLITE_OS_OTHER==1
+#   undef SQLITE_OS_UNIX
+#   define SQLITE_OS_UNIX 0
+#   undef SQLITE_OS_WIN
+#   define SQLITE_OS_WIN 0
+#   undef SQLITE_OS_OS2
+#   define SQLITE_OS_OS2 0
+# else
+#   undef SQLITE_OS_OTHER
+# endif
+#endif
+#if !defined(SQLITE_OS_UNIX) && !defined(SQLITE_OS_OTHER)
+# define SQLITE_OS_OTHER 0
+# ifndef SQLITE_OS_WIN
+#   if defined(_WIN32) || defined(WIN32) || defined(__CYGWIN__) || defined(__MINGW32__) || defined(__BORLANDC__)
+#     define SQLITE_OS_WIN 1
+#     define SQLITE_OS_UNIX 0
+#     define SQLITE_OS_OS2 0
+#   elif defined(__EMX__) || defined(_OS2) || defined(OS2) || defined(_OS2_) || defined(__OS2__)
+#     define SQLITE_OS_WIN 0
+#     define SQLITE_OS_UNIX 0
+#     define SQLITE_OS_OS2 1
+#   else
+#     define SQLITE_OS_WIN 0
+#     define SQLITE_OS_UNIX 1
+#     define SQLITE_OS_OS2 0
+#  endif
+# else
+#  define SQLITE_OS_UNIX 0
+#  define SQLITE_OS_OS2 0
+# endif
+#else
+# ifndef SQLITE_OS_WIN
+#  define SQLITE_OS_WIN 0
+# endif
+#endif
+
+/*
+** Determine if we are dealing with WindowsCE - which has a much
+** reduced API.
+*/
+#if defined(_WIN32_WCE)
+# define SQLITE_OS_WINCE 1
+#else
+# define SQLITE_OS_WINCE 0
+#endif
+
+
+/*
+** Define the maximum size of a temporary filename
+*/
+#if SQLITE_OS_WIN
+# include <windows.h>
+# define SQLITE_TEMPNAME_SIZE (MAX_PATH+50)
+#elif SQLITE_OS_OS2
+# if (__GNUC__ > 3 || __GNUC__ == 3 && __GNUC_MINOR__ >= 3) && defined(OS2_HIGH_MEMORY)
+#  include <os2safe.h> /* has to be included before os2.h for linking to work */
+# endif
+# define INCL_DOSDATETIME
+# define INCL_DOSFILEMGR
+# define INCL_DOSERRORS
+# define INCL_DOSMISC
+# define INCL_DOSPROCESS
+# define INCL_DOSMODULEMGR
+# define INCL_DOSSEMAPHORES
+# include <os2.h>
+# include <uconv.h>
+# define SQLITE_TEMPNAME_SIZE (CCHMAXPATHCOMP)
+#else
+# define SQLITE_TEMPNAME_SIZE 200
+#endif
+
+/* If the SET_FULLSYNC macro is not defined above, then make it
+** a no-op
+*/
+#ifndef SET_FULLSYNC
+# define SET_FULLSYNC(x,y)
+#endif
+
+/*
+** The default size of a disk sector
+*/
+#ifndef SQLITE_DEFAULT_SECTOR_SIZE
+# define SQLITE_DEFAULT_SECTOR_SIZE 512
+#endif
+
+/*
+** Temporary files are named starting with this prefix followed by 16 random
+** alphanumeric characters, and no file extension. They are stored in the
+** OS's standard temporary file directory, and are deleted prior to exit.
+** If sqlite is being embedded in another program, you may wish to change the
+** prefix to reflect your program's name, so that if your program exits
+** prematurely, old temporary files can be easily identified. This can be done
+** using -DSQLITE_TEMP_FILE_PREFIX=myprefix_ on the compiler command line.
+**
+** 2006-10-31:  The default prefix used to be "sqlite_".  But then
+** Mcafee started using SQLite in their anti-virus product and it
+** started putting files with the "sqlite" name in the c:/temp folder.
+** This annoyed many windows users.  Those users would then do a 
+** Google search for "sqlite", find the telephone numbers of the
+** developers and call to wake them up at night and complain.
+** For this reason, the default name prefix is changed to be "sqlite" 
+** spelled backwards.  So the temp files are still identified, but
+** anybody smart enough to figure out the code is also likely smart
+** enough to know that calling the developer will not help get rid
+** of the file.
+*/
+#ifndef SQLITE_TEMP_FILE_PREFIX
+# define SQLITE_TEMP_FILE_PREFIX "etilqs_"
+#endif
+
+/*
+** The following values may be passed as the second argument to
+** sqlite3OsLock(). The various locks exhibit the following semantics:
+**
+** SHARED:    Any number of processes may hold a SHARED lock simultaneously.
+** RESERVED:  A single process may hold a RESERVED lock on a file at
+**            any time. Other processes may hold and obtain new SHARED locks.
+** PENDING:   A single process may hold a PENDING lock on a file at
+**            any one time. Existing SHARED locks may persist, but no new
+**            SHARED locks may be obtained by other processes.
+** EXCLUSIVE: An EXCLUSIVE lock precludes all other locks.
+**
+** PENDING_LOCK may not be passed directly to sqlite3OsLock(). Instead, a
+** process that requests an EXCLUSIVE lock may actually obtain a PENDING
+** lock. This can be upgraded to an EXCLUSIVE lock by a subsequent call to
+** sqlite3OsLock().
+*/
+#define NO_LOCK         0
+#define SHARED_LOCK     1
+#define RESERVED_LOCK   2
+#define PENDING_LOCK    3
+#define EXCLUSIVE_LOCK  4
+
+/*
+** File Locking Notes:  (Mostly about windows but also some info for Unix)
+**
+** We cannot use LockFileEx() or UnlockFileEx() on Win95/98/ME because
+** those functions are not available.  So we use only LockFile() and
+** UnlockFile().
+**
+** LockFile() prevents not just writing but also reading by other processes.
+** A SHARED_LOCK is obtained by locking a single randomly-chosen 
+** byte out of a specific range of bytes. The lock byte is obtained at 
+** random so two separate readers can probably access the file at the 
+** same time, unless they are unlucky and choose the same lock byte.
+** An EXCLUSIVE_LOCK is obtained by locking all bytes in the range.
+** There can only be one writer.  A RESERVED_LOCK is obtained by locking
+** a single byte of the file that is designated as the reserved lock byte.
+** A PENDING_LOCK is obtained by locking a designated byte different from
+** the RESERVED_LOCK byte.
+**
+** On WinNT/2K/XP systems, LockFileEx() and UnlockFileEx() are available,
+** which means we can use reader/writer locks.  When reader/writer locks
+** are used, the lock is placed on the same range of bytes that is used
+** for probabilistic locking in Win95/98/ME.  Hence, the locking scheme
+** will support two or more Win95 readers or two or more WinNT readers.
+** But a single Win95 reader will lock out all WinNT readers and a single
+** WinNT reader will lock out all other Win95 readers.
+**
+** The following #defines specify the range of bytes used for locking.
+** SHARED_SIZE is the number of bytes available in the pool from which
+** a random byte is selected for a shared lock.  The pool of bytes for
+** shared locks begins at SHARED_FIRST. 
+**
+** The same locking strategy and
+** byte ranges are used for Unix.  This leaves open the possiblity of having
+** clients on win95, winNT, and unix all talking to the same shared file
+** and all locking correctly.  To do so would require that samba (or whatever
+** tool is being used for file sharing) implements locks correctly between
+** windows and unix.  I'm guessing that isn't likely to happen, but by
+** using the same locking range we are at least open to the possibility.
+**
+** Locking in windows is manditory.  For this reason, we cannot store
+** actual data in the bytes used for locking.  The pager never allocates
+** the pages involved in locking therefore.  SHARED_SIZE is selected so
+** that all locks will fit on a single page even at the minimum page size.
+** PENDING_BYTE defines the beginning of the locks.  By default PENDING_BYTE
+** is set high so that we don't have to allocate an unused page except
+** for very large databases.  But one should test the page skipping logic 
+** by setting PENDING_BYTE low and running the entire regression suite.
+**
+** Changing the value of PENDING_BYTE results in a subtly incompatible
+** file format.  Depending on how it is changed, you might not notice
+** the incompatibility right away, even running a full regression test.
+** The default location of PENDING_BYTE is the first byte past the
+** 1GB boundary.
+**
+*/
+#ifdef SQLITE_OMIT_WSD
+# define PENDING_BYTE     (0x40000000)
+#else
+# define PENDING_BYTE      sqlite3PendingByte
+#endif
+#define RESERVED_BYTE     (PENDING_BYTE+1)
+#define SHARED_FIRST      (PENDING_BYTE+2)
+#define SHARED_SIZE       510
+
+/*
+** Wrapper around OS specific sqlite3_os_init() function.
+*/
+SQLITE_PRIVATE int sqlite3OsInit(void);
+
+/* 
+** Functions for accessing sqlite3_file methods 
+*/
+SQLITE_PRIVATE int sqlite3OsClose(sqlite3_file*);
+SQLITE_PRIVATE int sqlite3OsRead(sqlite3_file*, void*, int amt, i64 offset);
+SQLITE_PRIVATE int sqlite3OsWrite(sqlite3_file*, const void*, int amt, i64 offset);
+SQLITE_PRIVATE int sqlite3OsTruncate(sqlite3_file*, i64 size);
+SQLITE_PRIVATE int sqlite3OsSync(sqlite3_file*, int);
+SQLITE_PRIVATE int sqlite3OsFileSize(sqlite3_file*, i64 *pSize);
+SQLITE_PRIVATE int sqlite3OsLock(sqlite3_file*, int);
+SQLITE_PRIVATE int sqlite3OsUnlock(sqlite3_file*, int);
+SQLITE_PRIVATE int sqlite3OsCheckReservedLock(sqlite3_file *id, int *pResOut);
+SQLITE_PRIVATE int sqlite3OsFileControl(sqlite3_file*,int,void*);
+#define SQLITE_FCNTL_DB_UNCHANGED 0xca093fa0
+SQLITE_PRIVATE int sqlite3OsSectorSize(sqlite3_file *id);
+SQLITE_PRIVATE int sqlite3OsDeviceCharacteristics(sqlite3_file *id);
+SQLITE_PRIVATE int sqlite3OsShmMap(sqlite3_file *,int,int,int,void volatile **);
+SQLITE_PRIVATE int sqlite3OsShmLock(sqlite3_file *id, int, int, int);
+SQLITE_PRIVATE void sqlite3OsShmBarrier(sqlite3_file *id);
+SQLITE_PRIVATE int sqlite3OsShmUnmap(sqlite3_file *id, int);
+
+/* 
+** Functions for accessing sqlite3_vfs methods 
+*/
+SQLITE_PRIVATE int sqlite3OsOpen(sqlite3_vfs *, const char *, sqlite3_file*, int, int *);
+SQLITE_PRIVATE int sqlite3OsDelete(sqlite3_vfs *, const char *, int);
+SQLITE_PRIVATE int sqlite3OsAccess(sqlite3_vfs *, const char *, int, int *pResOut);
+SQLITE_PRIVATE int sqlite3OsFullPathname(sqlite3_vfs *, const char *, int, char *);
+#ifndef SQLITE_OMIT_LOAD_EXTENSION
+SQLITE_PRIVATE void *sqlite3OsDlOpen(sqlite3_vfs *, const char *);
+SQLITE_PRIVATE void sqlite3OsDlError(sqlite3_vfs *, int, char *);
+SQLITE_PRIVATE void (*sqlite3OsDlSym(sqlite3_vfs *, void *, const char *))(void);
+SQLITE_PRIVATE void sqlite3OsDlClose(sqlite3_vfs *, void *);
+#endif /* SQLITE_OMIT_LOAD_EXTENSION */
+SQLITE_PRIVATE int sqlite3OsRandomness(sqlite3_vfs *, int, char *);
+SQLITE_PRIVATE int sqlite3OsSleep(sqlite3_vfs *, int);
+SQLITE_PRIVATE int sqlite3OsCurrentTimeInt64(sqlite3_vfs *, sqlite3_int64*);
+
+/*
+** Convenience functions for opening and closing files using 
+** sqlite3_malloc() to obtain space for the file-handle structure.
+*/
+SQLITE_PRIVATE int sqlite3OsOpenMalloc(sqlite3_vfs *, const char *, sqlite3_file **, int,int*);
+SQLITE_PRIVATE int sqlite3OsCloseFree(sqlite3_file *);
+
+#endif /* _SQLITE_OS_H_ */
+
+/************** End of os.h **************************************************/
+/************** Continuing where we left off in sqliteInt.h ******************/
+/************** Include mutex.h in the middle of sqliteInt.h *****************/
+/************** Begin file mutex.h *******************************************/
+/*
+** 2007 August 28
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains the common header for all mutex implementations.
+** The sqliteInt.h header #includes this file so that it is available
+** to all source files.  We break it out in an effort to keep the code
+** better organized.
+**
+** NOTE:  source files should *not* #include this header file directly.
+** Source files should #include the sqliteInt.h file and let that file
+** include this one indirectly.
+*/
+
+
+/*
+** Figure out what version of the code to use.  The choices are
+**
+**   SQLITE_MUTEX_OMIT         No mutex logic.  Not even stubs.  The
+**                             mutexes implemention cannot be overridden
+**                             at start-time.
+**
+**   SQLITE_MUTEX_NOOP         For single-threaded applications.  No
+**                             mutual exclusion is provided.  But this
+**                             implementation can be overridden at
+**                             start-time.
+**
+**   SQLITE_MUTEX_PTHREADS     For multi-threaded applications on Unix.
+**
+**   SQLITE_MUTEX_W32          For multi-threaded applications on Win32.
+**
+**   SQLITE_MUTEX_OS2          For multi-threaded applications on OS/2.
+*/
+#if !SQLITE_THREADSAFE
+# define SQLITE_MUTEX_OMIT
+#endif
+#if SQLITE_THREADSAFE && !defined(SQLITE_MUTEX_NOOP)
+#  if SQLITE_OS_UNIX
+#    define SQLITE_MUTEX_PTHREADS
+#  elif SQLITE_OS_WIN
+#    define SQLITE_MUTEX_W32
+#  elif SQLITE_OS_OS2
+#    define SQLITE_MUTEX_OS2
+#  else
+#    define SQLITE_MUTEX_NOOP
+#  endif
+#endif
+
+#ifdef SQLITE_MUTEX_OMIT
+/*
+** If this is a no-op implementation, implement everything as macros.
+*/
+#define sqlite3_mutex_alloc(X)    ((sqlite3_mutex*)8)
+#define sqlite3_mutex_free(X)
+#define sqlite3_mutex_enter(X)
+#define sqlite3_mutex_try(X)      SQLITE_OK
+#define sqlite3_mutex_leave(X)
+#define sqlite3_mutex_held(X)     ((void)(X),1)
+#define sqlite3_mutex_notheld(X)  ((void)(X),1)
+#define sqlite3MutexAlloc(X)      ((sqlite3_mutex*)8)
+#define sqlite3MutexInit()        SQLITE_OK
+#define sqlite3MutexEnd()
+#endif /* defined(SQLITE_MUTEX_OMIT) */
+
+/************** End of mutex.h ***********************************************/
+/************** Continuing where we left off in sqliteInt.h ******************/
+
+
+/*
+** Each database file to be accessed by the system is an instance
+** of the following structure.  There are normally two of these structures
+** in the sqlite.aDb[] array.  aDb[0] is the main database file and
+** aDb[1] is the database file used to hold temporary tables.  Additional
+** databases may be attached.
+*/
+struct Db {
+  char *zName;         /* Name of this database */
+  Btree *pBt;          /* The B*Tree structure for this database file */
+  u8 inTrans;          /* 0: not writable.  1: Transaction.  2: Checkpoint */
+  u8 safety_level;     /* How aggressive at syncing data to disk */
+  Schema *pSchema;     /* Pointer to database schema (possibly shared) */
+};
+
+/*
+** An instance of the following structure stores a database schema.
+**
+** Most Schema objects are associated with a Btree.  The exception is
+** the Schema for the TEMP databaes (sqlite3.aDb[1]) which is free-standing.
+** In shared cache mode, a single Schema object can be shared by multiple
+** Btrees that refer to the same underlying BtShared object.
+** 
+** Schema objects are automatically deallocated when the last Btree that
+** references them is destroyed.   The TEMP Schema is manually freed by
+** sqlite3_close().
+*
+** A thread must be holding a mutex on the corresponding Btree in order
+** to access Schema content.  This implies that the thread must also be
+** holding a mutex on the sqlite3 connection pointer that owns the Btree.
+** For a TEMP Schema, on the connection mutex is required.
+*/
+struct Schema {
+  int schema_cookie;   /* Database schema version number for this file */
+  int iGeneration;     /* Generation counter.  Incremented with each change */
+  Hash tblHash;        /* All tables indexed by name */
+  Hash idxHash;        /* All (named) indices indexed by name */
+  Hash trigHash;       /* All triggers indexed by name */
+  Hash fkeyHash;       /* All foreign keys by referenced table name */
+  Table *pSeqTab;      /* The sqlite_sequence table used by AUTOINCREMENT */
+  u8 file_format;      /* Schema format version for this file */
+  u8 enc;              /* Text encoding used by this database */
+  u16 flags;           /* Flags associated with this schema */
+  int cache_size;      /* Number of pages to use in the cache */
+};
+
+/*
+** These macros can be used to test, set, or clear bits in the 
+** Db.pSchema->flags field.
+*/
+#define DbHasProperty(D,I,P)     (((D)->aDb[I].pSchema->flags&(P))==(P))
+#define DbHasAnyProperty(D,I,P)  (((D)->aDb[I].pSchema->flags&(P))!=0)
+#define DbSetProperty(D,I,P)     (D)->aDb[I].pSchema->flags|=(P)
+#define DbClearProperty(D,I,P)   (D)->aDb[I].pSchema->flags&=~(P)
+
+/*
+** Allowed values for the DB.pSchema->flags field.
+**
+** The DB_SchemaLoaded flag is set after the database schema has been
+** read into internal hash tables.
+**
+** DB_UnresetViews means that one or more views have column names that
+** have been filled out.  If the schema changes, these column names might
+** changes and so the view will need to be reset.
+*/
+#define DB_SchemaLoaded    0x0001  /* The schema has been loaded */
+#define DB_UnresetViews    0x0002  /* Some views have defined column names */
+#define DB_Empty           0x0004  /* The file is empty (length 0 bytes) */
+
+/*
+** The number of different kinds of things that can be limited
+** using the sqlite3_limit() interface.
+*/
+#define SQLITE_N_LIMIT (SQLITE_LIMIT_TRIGGER_DEPTH+1)
+
+/*
+** Lookaside malloc is a set of fixed-size buffers that can be used
+** to satisfy small transient memory allocation requests for objects
+** associated with a particular database connection.  The use of
+** lookaside malloc provides a significant performance enhancement
+** (approx 10%) by avoiding numerous malloc/free requests while parsing
+** SQL statements.
+**
+** The Lookaside structure holds configuration information about the
+** lookaside malloc subsystem.  Each available memory allocation in
+** the lookaside subsystem is stored on a linked list of LookasideSlot
+** objects.
+**
+** Lookaside allocations are only allowed for objects that are associated
+** with a particular database connection.  Hence, schema information cannot
+** be stored in lookaside because in shared cache mode the schema information
+** is shared by multiple database connections.  Therefore, while parsing
+** schema information, the Lookaside.bEnabled flag is cleared so that
+** lookaside allocations are not used to construct the schema objects.
+*/
+struct Lookaside {
+  u16 sz;                 /* Size of each buffer in bytes */
+  u8 bEnabled;            /* False to disable new lookaside allocations */
+  u8 bMalloced;           /* True if pStart obtained from sqlite3_malloc() */
+  int nOut;               /* Number of buffers currently checked out */
+  int mxOut;              /* Highwater mark for nOut */
+  int anStat[3];          /* 0: hits.  1: size misses.  2: full misses */
+  LookasideSlot *pFree;   /* List of available buffers */
+  void *pStart;           /* First byte of available memory space */
+  void *pEnd;             /* First byte past end of available space */
+};
+struct LookasideSlot {
+  LookasideSlot *pNext;    /* Next buffer in the list of free buffers */
+};
+
+/*
+** A hash table for function definitions.
+**
+** Hash each FuncDef structure into one of the FuncDefHash.a[] slots.
+** Collisions are on the FuncDef.pHash chain.
+*/
+struct FuncDefHash {
+  FuncDef *a[23];       /* Hash table for functions */
+};
+
+/*
+** Each database connection is an instance of the following structure.
+**
+** The sqlite.lastRowid records the last insert rowid generated by an
+** insert statement.  Inserts on views do not affect its value.  Each
+** trigger has its own context, so that lastRowid can be updated inside
+** triggers as usual.  The previous value will be restored once the trigger
+** exits.  Upon entering a before or instead of trigger, lastRowid is no
+** longer (since after version 2.8.12) reset to -1.
+**
+** The sqlite.nChange does not count changes within triggers and keeps no
+** context.  It is reset at start of sqlite3_exec.
+** The sqlite.lsChange represents the number of changes made by the last
+** insert, update, or delete statement.  It remains constant throughout the
+** length of a statement and is then updated by OP_SetCounts.  It keeps a
+** context stack just like lastRowid so that the count of changes
+** within a trigger is not seen outside the trigger.  Changes to views do not
+** affect the value of lsChange.
+** The sqlite.csChange keeps track of the number of current changes (since
+** the last statement) and is used to update sqlite_lsChange.
+**
+** The member variables sqlite.errCode, sqlite.zErrMsg and sqlite.zErrMsg16
+** store the most recent error code and, if applicable, string. The
+** internal function sqlite3Error() is used to set these variables
+** consistently.
+*/
+struct sqlite3 {
+  sqlite3_vfs *pVfs;            /* OS Interface */
+  int nDb;                      /* Number of backends currently in use */
+  Db *aDb;                      /* All backends */
+  int flags;                    /* Miscellaneous flags. See below */
+  int openFlags;                /* Flags passed to sqlite3_vfs.xOpen() */
+  int errCode;                  /* Most recent error code (SQLITE_*) */
+  int errMask;                  /* & result codes with this before returning */
+  u8 autoCommit;                /* The auto-commit flag. */
+  u8 temp_store;                /* 1: file 2: memory 0: default */
+  u8 mallocFailed;              /* True if we have seen a malloc failure */
+  u8 dfltLockMode;              /* Default locking-mode for attached dbs */
+  signed char nextAutovac;      /* Autovac setting after VACUUM if >=0 */
+  u8 suppressErr;               /* Do not issue error messages if true */
+  int nextPagesize;             /* Pagesize after VACUUM if >0 */
+  int nTable;                   /* Number of tables in the database */
+  CollSeq *pDfltColl;           /* The default collating sequence (BINARY) */
+  i64 lastRowid;                /* ROWID of most recent insert (see above) */
+  u32 magic;                    /* Magic number for detect library misuse */
+  int nChange;                  /* Value returned by sqlite3_changes() */
+  int nTotalChange;             /* Value returned by sqlite3_total_changes() */
+  sqlite3_mutex *mutex;         /* Connection mutex */
+  int aLimit[SQLITE_N_LIMIT];   /* Limits */
+  struct sqlite3InitInfo {      /* Information used during initialization */
+    int iDb;                    /* When back is being initialized */
+    int newTnum;                /* Rootpage of table being initialized */
+    u8 busy;                    /* TRUE if currently initializing */
+    u8 orphanTrigger;           /* Last statement is orphaned TEMP trigger */
+  } init;
+  int nExtension;               /* Number of loaded extensions */
+  void **aExtension;            /* Array of shared library handles */
+  struct Vdbe *pVdbe;           /* List of active virtual machines */
+  int activeVdbeCnt;            /* Number of VDBEs currently executing */
+  int writeVdbeCnt;             /* Number of active VDBEs that are writing */
+  int vdbeExecCnt;              /* Number of nested calls to VdbeExec() */
+  void (*xTrace)(void*,const char*);        /* Trace function */
+  void *pTraceArg;                          /* Argument to the trace function */
+  void (*xProfile)(void*,const char*,u64);  /* Profiling function */
+  void *pProfileArg;                        /* Argument to profile function */
+  void *pCommitArg;                 /* Argument to xCommitCallback() */   
+  int (*xCommitCallback)(void*);    /* Invoked at every commit. */
+  void *pRollbackArg;               /* Argument to xRollbackCallback() */   
+  void (*xRollbackCallback)(void*); /* Invoked at every commit. */
+  void *pUpdateArg;
+  void (*xUpdateCallback)(void*,int, const char*,const char*,sqlite_int64);
+#ifndef SQLITE_OMIT_WAL
+  int (*xWalCallback)(void *, sqlite3 *, const char *, int);
+  void *pWalArg;
+#endif
+  void(*xCollNeeded)(void*,sqlite3*,int eTextRep,const char*);
+  void(*xCollNeeded16)(void*,sqlite3*,int eTextRep,const void*);
+  void *pCollNeededArg;
+  sqlite3_value *pErr;          /* Most recent error message */
+  char *zErrMsg;                /* Most recent error message (UTF-8 encoded) */
+  char *zErrMsg16;              /* Most recent error message (UTF-16 encoded) */
+  union {
+    volatile int isInterrupted; /* True if sqlite3_interrupt has been called */
+    double notUsed1;            /* Spacer */
+  } u1;
+  Lookaside lookaside;          /* Lookaside malloc configuration */
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  int (*xAuth)(void*,int,const char*,const char*,const char*,const char*);
+                                /* Access authorization function */
+  void *pAuthArg;               /* 1st argument to the access auth function */
+#endif
+#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
+  int (*xProgress)(void *);     /* The progress callback */
+  void *pProgressArg;           /* Argument to the progress callback */
+  int nProgressOps;             /* Number of opcodes for progress callback */
+#endif
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  Hash aModule;                 /* populated by sqlite3_create_module() */
+  Table *pVTab;                 /* vtab with active Connect/Create method */
+  VTable **aVTrans;             /* Virtual tables with open transactions */
+  int nVTrans;                  /* Allocated size of aVTrans */
+  VTable *pDisconnect;    /* Disconnect these in next sqlite3_prepare() */
+#endif
+  FuncDefHash aFunc;            /* Hash table of connection functions */
+  Hash aCollSeq;                /* All collating sequences */
+  BusyHandler busyHandler;      /* Busy callback */
+  int busyTimeout;              /* Busy handler timeout, in msec */
+  Db aDbStatic[2];              /* Static space for the 2 default backends */
+  Savepoint *pSavepoint;        /* List of active savepoints */
+  int nSavepoint;               /* Number of non-transaction savepoints */
+  int nStatement;               /* Number of nested statement-transactions  */
+  u8 isTransactionSavepoint;    /* True if the outermost savepoint is a TS */
+  i64 nDeferredCons;            /* Net deferred constraints this transaction. */
+  int *pnBytesFreed;            /* If not NULL, increment this in DbFree() */
+
+#ifdef SQLITE_ENABLE_UNLOCK_NOTIFY
+  /* The following variables are all protected by the STATIC_MASTER 
+  ** mutex, not by sqlite3.mutex. They are used by code in notify.c. 
+  **
+  ** When X.pUnlockConnection==Y, that means that X is waiting for Y to
+  ** unlock so that it can proceed.
+  **
+  ** When X.pBlockingConnection==Y, that means that something that X tried
+  ** tried to do recently failed with an SQLITE_LOCKED error due to locks
+  ** held by Y.
+  */
+  sqlite3 *pBlockingConnection; /* Connection that caused SQLITE_LOCKED */
+  sqlite3 *pUnlockConnection;           /* Connection to watch for unlock */
+  void *pUnlockArg;                     /* Argument to xUnlockNotify */
+  void (*xUnlockNotify)(void **, int);  /* Unlock notify callback */
+  sqlite3 *pNextBlocked;        /* Next in list of all blocked connections */
+#endif
+};
+
+/*
+** A macro to discover the encoding of a database.
+*/
+#define ENC(db) ((db)->aDb[0].pSchema->enc)
+
+/*
+** Possible values for the sqlite3.flags.
+*/
+#define SQLITE_VdbeTrace      0x00000100  /* True to trace VDBE execution */
+#define SQLITE_InternChanges  0x00000200  /* Uncommitted Hash table changes */
+#define SQLITE_FullColNames   0x00000400  /* Show full column names on SELECT */
+#define SQLITE_ShortColNames  0x00000800  /* Show short columns names */
+#define SQLITE_CountRows      0x00001000  /* Count rows changed by INSERT, */
+                                          /*   DELETE, or UPDATE and return */
+                                          /*   the count using a callback. */
+#define SQLITE_NullCallback   0x00002000  /* Invoke the callback once if the */
+                                          /*   result set is empty */
+#define SQLITE_SqlTrace       0x00004000  /* Debug print SQL as it executes */
+#define SQLITE_VdbeListing    0x00008000  /* Debug listings of VDBE programs */
+#define SQLITE_WriteSchema    0x00010000  /* OK to update SQLITE_MASTER */
+#define SQLITE_NoReadlock     0x00020000  /* Readlocks are omitted when 
+                                          ** accessing read-only databases */
+#define SQLITE_IgnoreChecks   0x00040000  /* Do not enforce check constraints */
+#define SQLITE_ReadUncommitted 0x0080000  /* For shared-cache mode */
+#define SQLITE_LegacyFileFmt  0x00100000  /* Create new databases in format 1 */
+#define SQLITE_FullFSync      0x00200000  /* Use full fsync on the backend */
+#define SQLITE_CkptFullFSync  0x00400000  /* Use full fsync for checkpoint */
+#define SQLITE_RecoveryMode   0x00800000  /* Ignore schema errors */
+#define SQLITE_ReverseOrder   0x01000000  /* Reverse unordered SELECTs */
+#define SQLITE_RecTriggers    0x02000000  /* Enable recursive triggers */
+#define SQLITE_ForeignKeys    0x04000000  /* Enforce foreign key constraints  */
+#define SQLITE_AutoIndex      0x08000000  /* Enable automatic indexes */
+#define SQLITE_PreferBuiltin  0x10000000  /* Preference to built-in funcs */
+#define SQLITE_LoadExtension  0x20000000  /* Enable load_extension */
+#define SQLITE_EnableTrigger  0x40000000  /* True to enable triggers */
+
+/*
+** Bits of the sqlite3.flags field that are used by the
+** sqlite3_test_control(SQLITE_TESTCTRL_OPTIMIZATIONS,...) interface.
+** These must be the low-order bits of the flags field.
+*/
+#define SQLITE_QueryFlattener 0x01        /* Disable query flattening */
+#define SQLITE_ColumnCache    0x02        /* Disable the column cache */
+#define SQLITE_IndexSort      0x04        /* Disable indexes for sorting */
+#define SQLITE_IndexSearch    0x08        /* Disable indexes for searching */
+#define SQLITE_IndexCover     0x10        /* Disable index covering table */
+#define SQLITE_GroupByOrder   0x20        /* Disable GROUPBY cover of ORDERBY */
+#define SQLITE_FactorOutConst 0x40        /* Disable factoring out constants */
+#define SQLITE_OptMask        0xff        /* Mask of all disablable opts */
+
+/*
+** Possible values for the sqlite.magic field.
+** The numbers are obtained at random and have no special meaning, other
+** than being distinct from one another.
+*/
+#define SQLITE_MAGIC_OPEN     0xa029a697  /* Database is open */
+#define SQLITE_MAGIC_CLOSED   0x9f3c2d33  /* Database is closed */
+#define SQLITE_MAGIC_SICK     0x4b771290  /* Error and awaiting close */
+#define SQLITE_MAGIC_BUSY     0xf03b7906  /* Database currently in use */
+#define SQLITE_MAGIC_ERROR    0xb5357930  /* An SQLITE_MISUSE error occurred */
+
+/*
+** Each SQL function is defined by an instance of the following
+** structure.  A pointer to this structure is stored in the sqlite.aFunc
+** hash table.  When multiple functions have the same name, the hash table
+** points to a linked list of these structures.
+*/
+struct FuncDef {
+  i16 nArg;            /* Number of arguments.  -1 means unlimited */
+  u8 iPrefEnc;         /* Preferred text encoding (SQLITE_UTF8, 16LE, 16BE) */
+  u8 flags;            /* Some combination of SQLITE_FUNC_* */
+  void *pUserData;     /* User data parameter */
+  FuncDef *pNext;      /* Next function with same name */
+  void (*xFunc)(sqlite3_context*,int,sqlite3_value**); /* Regular function */
+  void (*xStep)(sqlite3_context*,int,sqlite3_value**); /* Aggregate step */
+  void (*xFinalize)(sqlite3_context*);                /* Aggregate finalizer */
+  char *zName;         /* SQL name of the function. */
+  FuncDef *pHash;      /* Next with a different name but the same hash */
+  FuncDestructor *pDestructor;   /* Reference counted destructor function */
+};
+
+/*
+** This structure encapsulates a user-function destructor callback (as
+** configured using create_function_v2()) and a reference counter. When
+** create_function_v2() is called to create a function with a destructor,
+** a single object of this type is allocated. FuncDestructor.nRef is set to 
+** the number of FuncDef objects created (either 1 or 3, depending on whether
+** or not the specified encoding is SQLITE_ANY). The FuncDef.pDestructor
+** member of each of the new FuncDef objects is set to point to the allocated
+** FuncDestructor.
+**
+** Thereafter, when one of the FuncDef objects is deleted, the reference
+** count on this object is decremented. When it reaches 0, the destructor
+** is invoked and the FuncDestructor structure freed.
+*/
+struct FuncDestructor {
+  int nRef;
+  void (*xDestroy)(void *);
+  void *pUserData;
+};
+
+/*
+** Possible values for FuncDef.flags
+*/
+#define SQLITE_FUNC_LIKE     0x01 /* Candidate for the LIKE optimization */
+#define SQLITE_FUNC_CASE     0x02 /* Case-sensitive LIKE-type function */
+#define SQLITE_FUNC_EPHEM    0x04 /* Ephemeral.  Delete with VDBE */
+#define SQLITE_FUNC_NEEDCOLL 0x08 /* sqlite3GetFuncCollSeq() might be called */
+#define SQLITE_FUNC_PRIVATE  0x10 /* Allowed for internal use only */
+#define SQLITE_FUNC_COUNT    0x20 /* Built-in count(*) aggregate */
+#define SQLITE_FUNC_COALESCE 0x40 /* Built-in coalesce() or ifnull() function */
+
+/*
+** The following three macros, FUNCTION(), LIKEFUNC() and AGGREGATE() are
+** used to create the initializers for the FuncDef structures.
+**
+**   FUNCTION(zName, nArg, iArg, bNC, xFunc)
+**     Used to create a scalar function definition of a function zName 
+**     implemented by C function xFunc that accepts nArg arguments. The
+**     value passed as iArg is cast to a (void*) and made available
+**     as the user-data (sqlite3_user_data()) for the function. If 
+**     argument bNC is true, then the SQLITE_FUNC_NEEDCOLL flag is set.
+**
+**   AGGREGATE(zName, nArg, iArg, bNC, xStep, xFinal)
+**     Used to create an aggregate function definition implemented by
+**     the C functions xStep and xFinal. The first four parameters
+**     are interpreted in the same way as the first 4 parameters to
+**     FUNCTION().
+**
+**   LIKEFUNC(zName, nArg, pArg, flags)
+**     Used to create a scalar function definition of a function zName 
+**     that accepts nArg arguments and is implemented by a call to C 
+**     function likeFunc. Argument pArg is cast to a (void *) and made
+**     available as the function user-data (sqlite3_user_data()). The
+**     FuncDef.flags variable is set to the value passed as the flags
+**     parameter.
+*/
+#define FUNCTION(zName, nArg, iArg, bNC, xFunc) \
+  {nArg, SQLITE_UTF8, bNC*SQLITE_FUNC_NEEDCOLL, \
+   SQLITE_INT_TO_PTR(iArg), 0, xFunc, 0, 0, #zName, 0, 0}
+#define STR_FUNCTION(zName, nArg, pArg, bNC, xFunc) \
+  {nArg, SQLITE_UTF8, bNC*SQLITE_FUNC_NEEDCOLL, \
+   pArg, 0, xFunc, 0, 0, #zName, 0, 0}
+#define LIKEFUNC(zName, nArg, arg, flags) \
+  {nArg, SQLITE_UTF8, flags, (void *)arg, 0, likeFunc, 0, 0, #zName, 0, 0}
+#define AGGREGATE(zName, nArg, arg, nc, xStep, xFinal) \
+  {nArg, SQLITE_UTF8, nc*SQLITE_FUNC_NEEDCOLL, \
+   SQLITE_INT_TO_PTR(arg), 0, 0, xStep,xFinal,#zName,0,0}
+
+/*
+** All current savepoints are stored in a linked list starting at
+** sqlite3.pSavepoint. The first element in the list is the most recently
+** opened savepoint. Savepoints are added to the list by the vdbe
+** OP_Savepoint instruction.
+*/
+struct Savepoint {
+  char *zName;                        /* Savepoint name (nul-terminated) */
+  i64 nDeferredCons;                  /* Number of deferred fk violations */
+  Savepoint *pNext;                   /* Parent savepoint (if any) */
+};
+
+/*
+** The following are used as the second parameter to sqlite3Savepoint(),
+** and as the P1 argument to the OP_Savepoint instruction.
+*/
+#define SAVEPOINT_BEGIN      0
+#define SAVEPOINT_RELEASE    1
+#define SAVEPOINT_ROLLBACK   2
+
+
+/*
+** Each SQLite module (virtual table definition) is defined by an
+** instance of the following structure, stored in the sqlite3.aModule
+** hash table.
+*/
+struct Module {
+  const sqlite3_module *pModule;       /* Callback pointers */
+  const char *zName;                   /* Name passed to create_module() */
+  void *pAux;                          /* pAux passed to create_module() */
+  void (*xDestroy)(void *);            /* Module destructor function */
+};
+
+/*
+** information about each column of an SQL table is held in an instance
+** of this structure.
+*/
+struct Column {
+  char *zName;     /* Name of this column */
+  Expr *pDflt;     /* Default value of this column */
+  char *zDflt;     /* Original text of the default value */
+  char *zType;     /* Data type for this column */
+  char *zColl;     /* Collating sequence.  If NULL, use the default */
+  u8 notNull;      /* True if there is a NOT NULL constraint */
+  u8 isPrimKey;    /* True if this column is part of the PRIMARY KEY */
+  char affinity;   /* One of the SQLITE_AFF_... values */
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  u8 isHidden;     /* True if this column is 'hidden' */
+#endif
+};
+
+/*
+** A "Collating Sequence" is defined by an instance of the following
+** structure. Conceptually, a collating sequence consists of a name and
+** a comparison routine that defines the order of that sequence.
+**
+** There may two separate implementations of the collation function, one
+** that processes text in UTF-8 encoding (CollSeq.xCmp) and another that
+** processes text encoded in UTF-16 (CollSeq.xCmp16), using the machine
+** native byte order. When a collation sequence is invoked, SQLite selects
+** the version that will require the least expensive encoding
+** translations, if any.
+**
+** The CollSeq.pUser member variable is an extra parameter that passed in
+** as the first argument to the UTF-8 comparison function, xCmp.
+** CollSeq.pUser16 is the equivalent for the UTF-16 comparison function,
+** xCmp16.
+**
+** If both CollSeq.xCmp and CollSeq.xCmp16 are NULL, it means that the
+** collating sequence is undefined.  Indices built on an undefined
+** collating sequence may not be read or written.
+*/
+struct CollSeq {
+  char *zName;          /* Name of the collating sequence, UTF-8 encoded */
+  u8 enc;               /* Text encoding handled by xCmp() */
+  u8 type;              /* One of the SQLITE_COLL_... values below */
+  void *pUser;          /* First argument to xCmp() */
+  int (*xCmp)(void*,int, const void*, int, const void*);
+  void (*xDel)(void*);  /* Destructor for pUser */
+};
+
+/*
+** Allowed values of CollSeq.type:
+*/
+#define SQLITE_COLL_BINARY  1  /* The default memcmp() collating sequence */
+#define SQLITE_COLL_NOCASE  2  /* The built-in NOCASE collating sequence */
+#define SQLITE_COLL_REVERSE 3  /* The built-in REVERSE collating sequence */
+#define SQLITE_COLL_USER    0  /* Any other user-defined collating sequence */
+
+/*
+** A sort order can be either ASC or DESC.
+*/
+#define SQLITE_SO_ASC       0  /* Sort in ascending order */
+#define SQLITE_SO_DESC      1  /* Sort in ascending order */
+
+/*
+** Column affinity types.
+**
+** These used to have mnemonic name like 'i' for SQLITE_AFF_INTEGER and
+** 't' for SQLITE_AFF_TEXT.  But we can save a little space and improve
+** the speed a little by numbering the values consecutively.  
+**
+** But rather than start with 0 or 1, we begin with 'a'.  That way,
+** when multiple affinity types are concatenated into a string and
+** used as the P4 operand, they will be more readable.
+**
+** Note also that the numeric types are grouped together so that testing
+** for a numeric type is a single comparison.
+*/
+#define SQLITE_AFF_TEXT     'a'
+#define SQLITE_AFF_NONE     'b'
+#define SQLITE_AFF_NUMERIC  'c'
+#define SQLITE_AFF_INTEGER  'd'
+#define SQLITE_AFF_REAL     'e'
+
+#define sqlite3IsNumericAffinity(X)  ((X)>=SQLITE_AFF_NUMERIC)
+
+/*
+** The SQLITE_AFF_MASK values masks off the significant bits of an
+** affinity value. 
+*/
+#define SQLITE_AFF_MASK     0x67
+
+/*
+** Additional bit values that can be ORed with an affinity without
+** changing the affinity.
+*/
+#define SQLITE_JUMPIFNULL   0x08  /* jumps if either operand is NULL */
+#define SQLITE_STOREP2      0x10  /* Store result in reg[P2] rather than jump */
+#define SQLITE_NULLEQ       0x80  /* NULL=NULL */
+
+/*
+** An object of this type is created for each virtual table present in
+** the database schema. 
+**
+** If the database schema is shared, then there is one instance of this
+** structure for each database connection (sqlite3*) that uses the shared
+** schema. This is because each database connection requires its own unique
+** instance of the sqlite3_vtab* handle used to access the virtual table 
+** implementation. sqlite3_vtab* handles can not be shared between 
+** database connections, even when the rest of the in-memory database 
+** schema is shared, as the implementation often stores the database
+** connection handle passed to it via the xConnect() or xCreate() method
+** during initialization internally. This database connection handle may
+** then be used by the virtual table implementation to access real tables 
+** within the database. So that they appear as part of the callers 
+** transaction, these accesses need to be made via the same database 
+** connection as that used to execute SQL operations on the virtual table.
+**
+** All VTable objects that correspond to a single table in a shared
+** database schema are initially stored in a linked-list pointed to by
+** the Table.pVTable member variable of the corresponding Table object.
+** When an sqlite3_prepare() operation is required to access the virtual
+** table, it searches the list for the VTable that corresponds to the
+** database connection doing the preparing so as to use the correct
+** sqlite3_vtab* handle in the compiled query.
+**
+** When an in-memory Table object is deleted (for example when the
+** schema is being reloaded for some reason), the VTable objects are not 
+** deleted and the sqlite3_vtab* handles are not xDisconnect()ed 
+** immediately. Instead, they are moved from the Table.pVTable list to
+** another linked list headed by the sqlite3.pDisconnect member of the
+** corresponding sqlite3 structure. They are then deleted/xDisconnected 
+** next time a statement is prepared using said sqlite3*. This is done
+** to avoid deadlock issues involving multiple sqlite3.mutex mutexes.
+** Refer to comments above function sqlite3VtabUnlockList() for an
+** explanation as to why it is safe to add an entry to an sqlite3.pDisconnect
+** list without holding the corresponding sqlite3.mutex mutex.
+**
+** The memory for objects of this type is always allocated by 
+** sqlite3DbMalloc(), using the connection handle stored in VTable.db as 
+** the first argument.
+*/
+struct VTable {
+  sqlite3 *db;              /* Database connection associated with this table */
+  Module *pMod;             /* Pointer to module implementation */
+  sqlite3_vtab *pVtab;      /* Pointer to vtab instance */
+  int nRef;                 /* Number of pointers to this structure */
+  VTable *pNext;            /* Next in linked list (see above) */
+};
+
+/*
+** Each SQL table is represented in memory by an instance of the
+** following structure.
+**
+** Table.zName is the name of the table.  The case of the original
+** CREATE TABLE statement is stored, but case is not significant for
+** comparisons.
+**
+** Table.nCol is the number of columns in this table.  Table.aCol is a
+** pointer to an array of Column structures, one for each column.
+**
+** If the table has an INTEGER PRIMARY KEY, then Table.iPKey is the index of
+** the column that is that key.   Otherwise Table.iPKey is negative.  Note
+** that the datatype of the PRIMARY KEY must be INTEGER for this field to
+** be set.  An INTEGER PRIMARY KEY is used as the rowid for each row of
+** the table.  If a table has no INTEGER PRIMARY KEY, then a random rowid
+** is generated for each row of the table.  TF_HasPrimaryKey is set if
+** the table has any PRIMARY KEY, INTEGER or otherwise.
+**
+** Table.tnum is the page number for the root BTree page of the table in the
+** database file.  If Table.iDb is the index of the database table backend
+** in sqlite.aDb[].  0 is for the main database and 1 is for the file that
+** holds temporary tables and indices.  If TF_Ephemeral is set
+** then the table is stored in a file that is automatically deleted
+** when the VDBE cursor to the table is closed.  In this case Table.tnum 
+** refers VDBE cursor number that holds the table open, not to the root
+** page number.  Transient tables are used to hold the results of a
+** sub-query that appears instead of a real table name in the FROM clause 
+** of a SELECT statement.
+*/
+struct Table {
+  char *zName;         /* Name of the table or view */
+  int iPKey;           /* If not negative, use aCol[iPKey] as the primary key */
+  int nCol;            /* Number of columns in this table */
+  Column *aCol;        /* Information about each column */
+  Index *pIndex;       /* List of SQL indexes on this table. */
+  int tnum;            /* Root BTree node for this table (see note above) */
+  unsigned nRowEst;    /* Estimated rows in table - from sqlite_stat1 table */
+  Select *pSelect;     /* NULL for tables.  Points to definition if a view. */
+  u16 nRef;            /* Number of pointers to this Table */
+  u8 tabFlags;         /* Mask of TF_* values */
+  u8 keyConf;          /* What to do in case of uniqueness conflict on iPKey */
+  FKey *pFKey;         /* Linked list of all foreign keys in this table */
+  char *zColAff;       /* String defining the affinity of each column */
+#ifndef SQLITE_OMIT_CHECK
+  Expr *pCheck;        /* The AND of all CHECK constraints */
+#endif
+#ifndef SQLITE_OMIT_ALTERTABLE
+  int addColOffset;    /* Offset in CREATE TABLE stmt to add a new column */
+#endif
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  VTable *pVTable;     /* List of VTable objects. */
+  int nModuleArg;      /* Number of arguments to the module */
+  char **azModuleArg;  /* Text of all module args. [0] is module name */
+#endif
+  Trigger *pTrigger;   /* List of triggers stored in pSchema */
+  Schema *pSchema;     /* Schema that contains this table */
+  Table *pNextZombie;  /* Next on the Parse.pZombieTab list */
+};
+
+/*
+** Allowed values for Tabe.tabFlags.
+*/
+#define TF_Readonly        0x01    /* Read-only system table */
+#define TF_Ephemeral       0x02    /* An ephemeral table */
+#define TF_HasPrimaryKey   0x04    /* Table has a primary key */
+#define TF_Autoincrement   0x08    /* Integer primary key is autoincrement */
+#define TF_Virtual         0x10    /* Is a virtual table */
+#define TF_NeedMetadata    0x20    /* aCol[].zType and aCol[].pColl missing */
+
+
+
+/*
+** Test to see whether or not a table is a virtual table.  This is
+** done as a macro so that it will be optimized out when virtual
+** table support is omitted from the build.
+*/
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+#  define IsVirtual(X)      (((X)->tabFlags & TF_Virtual)!=0)
+#  define IsHiddenColumn(X) ((X)->isHidden)
+#else
+#  define IsVirtual(X)      0
+#  define IsHiddenColumn(X) 0
+#endif
+
+/*
+** Each foreign key constraint is an instance of the following structure.
+**
+** A foreign key is associated with two tables.  The "from" table is
+** the table that contains the REFERENCES clause that creates the foreign
+** key.  The "to" table is the table that is named in the REFERENCES clause.
+** Consider this example:
+**
+**     CREATE TABLE ex1(
+**       a INTEGER PRIMARY KEY,
+**       b INTEGER CONSTRAINT fk1 REFERENCES ex2(x)
+**     );
+**
+** For foreign key "fk1", the from-table is "ex1" and the to-table is "ex2".
+**
+** Each REFERENCES clause generates an instance of the following structure
+** which is attached to the from-table.  The to-table need not exist when
+** the from-table is created.  The existence of the to-table is not checked.
+*/
+struct FKey {
+  Table *pFrom;     /* Table containing the REFERENCES clause (aka: Child) */
+  FKey *pNextFrom;  /* Next foreign key in pFrom */
+  char *zTo;        /* Name of table that the key points to (aka: Parent) */
+  FKey *pNextTo;    /* Next foreign key on table named zTo */
+  FKey *pPrevTo;    /* Previous foreign key on table named zTo */
+  int nCol;         /* Number of columns in this key */
+  /* EV: R-30323-21917 */
+  u8 isDeferred;    /* True if constraint checking is deferred till COMMIT */
+  u8 aAction[2];          /* ON DELETE and ON UPDATE actions, respectively */
+  Trigger *apTrigger[2];  /* Triggers for aAction[] actions */
+  struct sColMap {  /* Mapping of columns in pFrom to columns in zTo */
+    int iFrom;         /* Index of column in pFrom */
+    char *zCol;        /* Name of column in zTo.  If 0 use PRIMARY KEY */
+  } aCol[1];        /* One entry for each of nCol column s */
+};
+
+/*
+** SQLite supports many different ways to resolve a constraint
+** error.  ROLLBACK processing means that a constraint violation
+** causes the operation in process to fail and for the current transaction
+** to be rolled back.  ABORT processing means the operation in process
+** fails and any prior changes from that one operation are backed out,
+** but the transaction is not rolled back.  FAIL processing means that
+** the operation in progress stops and returns an error code.  But prior
+** changes due to the same operation are not backed out and no rollback
+** occurs.  IGNORE means that the particular row that caused the constraint
+** error is not inserted or updated.  Processing continues and no error
+** is returned.  REPLACE means that preexisting database rows that caused
+** a UNIQUE constraint violation are removed so that the new insert or
+** update can proceed.  Processing continues and no error is reported.
+**
+** RESTRICT, SETNULL, and CASCADE actions apply only to foreign keys.
+** RESTRICT is the same as ABORT for IMMEDIATE foreign keys and the
+** same as ROLLBACK for DEFERRED keys.  SETNULL means that the foreign
+** key is set to NULL.  CASCADE means that a DELETE or UPDATE of the
+** referenced table row is propagated into the row that holds the
+** foreign key.
+** 
+** The following symbolic values are used to record which type
+** of action to take.
+*/
+#define OE_None     0   /* There is no constraint to check */
+#define OE_Rollback 1   /* Fail the operation and rollback the transaction */
+#define OE_Abort    2   /* Back out changes but do no rollback transaction */
+#define OE_Fail     3   /* Stop the operation but leave all prior changes */
+#define OE_Ignore   4   /* Ignore the error. Do not do the INSERT or UPDATE */
+#define OE_Replace  5   /* Delete existing record, then do INSERT or UPDATE */
+
+#define OE_Restrict 6   /* OE_Abort for IMMEDIATE, OE_Rollback for DEFERRED */
+#define OE_SetNull  7   /* Set the foreign key value to NULL */
+#define OE_SetDflt  8   /* Set the foreign key value to its default */
+#define OE_Cascade  9   /* Cascade the changes */
+
+#define OE_Default  99  /* Do whatever the default action is */
+
+
+/*
+** An instance of the following structure is passed as the first
+** argument to sqlite3VdbeKeyCompare and is used to control the 
+** comparison of the two index keys.
+*/
+struct KeyInfo {
+  sqlite3 *db;        /* The database connection */
+  u8 enc;             /* Text encoding - one of the SQLITE_UTF* values */
+  u16 nField;         /* Number of entries in aColl[] */
+  u8 *aSortOrder;     /* Sort order for each column.  May be NULL */
+  CollSeq *aColl[1];  /* Collating sequence for each term of the key */
+};
+
+/*
+** An instance of the following structure holds information about a
+** single index record that has already been parsed out into individual
+** values.
+**
+** A record is an object that contains one or more fields of data.
+** Records are used to store the content of a table row and to store
+** the key of an index.  A blob encoding of a record is created by
+** the OP_MakeRecord opcode of the VDBE and is disassembled by the
+** OP_Column opcode.
+**
+** This structure holds a record that has already been disassembled
+** into its constituent fields.
+*/
+struct UnpackedRecord {
+  KeyInfo *pKeyInfo;  /* Collation and sort-order information */
+  u16 nField;         /* Number of entries in apMem[] */
+  u16 flags;          /* Boolean settings.  UNPACKED_... below */
+  i64 rowid;          /* Used by UNPACKED_PREFIX_SEARCH */
+  Mem *aMem;          /* Values */
+};
+
+/*
+** Allowed values of UnpackedRecord.flags
+*/
+#define UNPACKED_NEED_FREE     0x0001  /* Memory is from sqlite3Malloc() */
+#define UNPACKED_NEED_DESTROY  0x0002  /* apMem[]s should all be destroyed */
+#define UNPACKED_IGNORE_ROWID  0x0004  /* Ignore trailing rowid on key1 */
+#define UNPACKED_INCRKEY       0x0008  /* Make this key an epsilon larger */
+#define UNPACKED_PREFIX_MATCH  0x0010  /* A prefix match is considered OK */
+#define UNPACKED_PREFIX_SEARCH 0x0020  /* A prefix match is considered OK */
+
+/*
+** Each SQL index is represented in memory by an
+** instance of the following structure.
+**
+** The columns of the table that are to be indexed are described
+** by the aiColumn[] field of this structure.  For example, suppose
+** we have the following table and index:
+**
+**     CREATE TABLE Ex1(c1 int, c2 int, c3 text);
+**     CREATE INDEX Ex2 ON Ex1(c3,c1);
+**
+** In the Table structure describing Ex1, nCol==3 because there are
+** three columns in the table.  In the Index structure describing
+** Ex2, nColumn==2 since 2 of the 3 columns of Ex1 are indexed.
+** The value of aiColumn is {2, 0}.  aiColumn[0]==2 because the 
+** first column to be indexed (c3) has an index of 2 in Ex1.aCol[].
+** The second column to be indexed (c1) has an index of 0 in
+** Ex1.aCol[], hence Ex2.aiColumn[1]==0.
+**
+** The Index.onError field determines whether or not the indexed columns
+** must be unique and what to do if they are not.  When Index.onError=OE_None,
+** it means this is not a unique index.  Otherwise it is a unique index
+** and the value of Index.onError indicate the which conflict resolution 
+** algorithm to employ whenever an attempt is made to insert a non-unique
+** element.
+*/
+struct Index {
+  char *zName;     /* Name of this index */
+  int nColumn;     /* Number of columns in the table used by this index */
+  int *aiColumn;   /* Which columns are used by this index.  1st is 0 */
+  unsigned *aiRowEst; /* Result of ANALYZE: Est. rows selected by each column */
+  Table *pTable;   /* The SQL table being indexed */
+  int tnum;        /* Page containing root of this index in database file */
+  u8 onError;      /* OE_Abort, OE_Ignore, OE_Replace, or OE_None */
+  u8 autoIndex;    /* True if is automatically created (ex: by UNIQUE) */
+  u8 bUnordered;   /* Use this index for == or IN queries only */
+  char *zColAff;   /* String defining the affinity of each column */
+  Index *pNext;    /* The next index associated with the same table */
+  Schema *pSchema; /* Schema containing this index */
+  u8 *aSortOrder;  /* Array of size Index.nColumn. True==DESC, False==ASC */
+  char **azColl;   /* Array of collation sequence names for index */
+  IndexSample *aSample;    /* Array of SQLITE_INDEX_SAMPLES samples */
+};
+
+/*
+** Each sample stored in the sqlite_stat2 table is represented in memory 
+** using a structure of this type.
+*/
+struct IndexSample {
+  union {
+    char *z;        /* Value if eType is SQLITE_TEXT or SQLITE_BLOB */
+    double r;       /* Value if eType is SQLITE_FLOAT or SQLITE_INTEGER */
+  } u;
+  u8 eType;         /* SQLITE_NULL, SQLITE_INTEGER ... etc. */
+  u8 nByte;         /* Size in byte of text or blob. */
+};
+
+/*
+** Each token coming out of the lexer is an instance of
+** this structure.  Tokens are also used as part of an expression.
+**
+** Note if Token.z==0 then Token.dyn and Token.n are undefined and
+** may contain random values.  Do not make any assumptions about Token.dyn
+** and Token.n when Token.z==0.
+*/
+struct Token {
+  const char *z;     /* Text of the token.  Not NULL-terminated! */
+  unsigned int n;    /* Number of characters in this token */
+};
+
+/*
+** An instance of this structure contains information needed to generate
+** code for a SELECT that contains aggregate functions.
+**
+** If Expr.op==TK_AGG_COLUMN or TK_AGG_FUNCTION then Expr.pAggInfo is a
+** pointer to this structure.  The Expr.iColumn field is the index in
+** AggInfo.aCol[] or AggInfo.aFunc[] of information needed to generate
+** code for that node.
+**
+** AggInfo.pGroupBy and AggInfo.aFunc.pExpr point to fields within the
+** original Select structure that describes the SELECT statement.  These
+** fields do not need to be freed when deallocating the AggInfo structure.
+*/
+struct AggInfo {
+  u8 directMode;          /* Direct rendering mode means take data directly
+                          ** from source tables rather than from accumulators */
+  u8 useSortingIdx;       /* In direct mode, reference the sorting index rather
+                          ** than the source table */
+  int sortingIdx;         /* Cursor number of the sorting index */
+  ExprList *pGroupBy;     /* The group by clause */
+  int nSortingColumn;     /* Number of columns in the sorting index */
+  struct AggInfo_col {    /* For each column used in source tables */
+    Table *pTab;             /* Source table */
+    int iTable;              /* Cursor number of the source table */
+    int iColumn;             /* Column number within the source table */
+    int iSorterColumn;       /* Column number in the sorting index */
+    int iMem;                /* Memory location that acts as accumulator */
+    Expr *pExpr;             /* The original expression */
+  } *aCol;
+  int nColumn;            /* Number of used entries in aCol[] */
+  int nColumnAlloc;       /* Number of slots allocated for aCol[] */
+  int nAccumulator;       /* Number of columns that show through to the output.
+                          ** Additional columns are used only as parameters to
+                          ** aggregate functions */
+  struct AggInfo_func {   /* For each aggregate function */
+    Expr *pExpr;             /* Expression encoding the function */
+    FuncDef *pFunc;          /* The aggregate function implementation */
+    int iMem;                /* Memory location that acts as accumulator */
+    int iDistinct;           /* Ephemeral table used to enforce DISTINCT */
+  } *aFunc;
+  int nFunc;              /* Number of entries in aFunc[] */
+  int nFuncAlloc;         /* Number of slots allocated for aFunc[] */
+};
+
+/*
+** The datatype ynVar is a signed integer, either 16-bit or 32-bit.
+** Usually it is 16-bits.  But if SQLITE_MAX_VARIABLE_NUMBER is greater
+** than 32767 we have to make it 32-bit.  16-bit is preferred because
+** it uses less memory in the Expr object, which is a big memory user
+** in systems with lots of prepared statements.  And few applications
+** need more than about 10 or 20 variables.  But some extreme users want
+** to have prepared statements with over 32767 variables, and for them
+** the option is available (at compile-time).
+*/
+#if SQLITE_MAX_VARIABLE_NUMBER<=32767
+typedef i16 ynVar;
+#else
+typedef int ynVar;
+#endif
+
+/*
+** Each node of an expression in the parse tree is an instance
+** of this structure.
+**
+** Expr.op is the opcode. The integer parser token codes are reused
+** as opcodes here. For example, the parser defines TK_GE to be an integer
+** code representing the ">=" operator. This same integer code is reused
+** to represent the greater-than-or-equal-to operator in the expression
+** tree.
+**
+** If the expression is an SQL literal (TK_INTEGER, TK_FLOAT, TK_BLOB, 
+** or TK_STRING), then Expr.token contains the text of the SQL literal. If
+** the expression is a variable (TK_VARIABLE), then Expr.token contains the 
+** variable name. Finally, if the expression is an SQL function (TK_FUNCTION),
+** then Expr.token contains the name of the function.
+**
+** Expr.pRight and Expr.pLeft are the left and right subexpressions of a
+** binary operator. Either or both may be NULL.
+**
+** Expr.x.pList is a list of arguments if the expression is an SQL function,
+** a CASE expression or an IN expression of the form "<lhs> IN (<y>, <z>...)".
+** Expr.x.pSelect is used if the expression is a sub-select or an expression of
+** the form "<lhs> IN (SELECT ...)". If the EP_xIsSelect bit is set in the
+** Expr.flags mask, then Expr.x.pSelect is valid. Otherwise, Expr.x.pList is 
+** valid.
+**
+** An expression of the form ID or ID.ID refers to a column in a table.
+** For such expressions, Expr.op is set to TK_COLUMN and Expr.iTable is
+** the integer cursor number of a VDBE cursor pointing to that table and
+** Expr.iColumn is the column number for the specific column.  If the
+** expression is used as a result in an aggregate SELECT, then the
+** value is also stored in the Expr.iAgg column in the aggregate so that
+** it can be accessed after all aggregates are computed.
+**
+** If the expression is an unbound variable marker (a question mark 
+** character '?' in the original SQL) then the Expr.iTable holds the index 
+** number for that variable.
+**
+** If the expression is a subquery then Expr.iColumn holds an integer
+** register number containing the result of the subquery.  If the
+** subquery gives a constant result, then iTable is -1.  If the subquery
+** gives a different answer at different times during statement processing
+** then iTable is the address of a subroutine that computes the subquery.
+**
+** If the Expr is of type OP_Column, and the table it is selecting from
+** is a disk table or the "old.*" pseudo-table, then pTab points to the
+** corresponding table definition.
+**
+** ALLOCATION NOTES:
+**
+** Expr objects can use a lot of memory space in database schema.  To
+** help reduce memory requirements, sometimes an Expr object will be
+** truncated.  And to reduce the number of memory allocations, sometimes
+** two or more Expr objects will be stored in a single memory allocation,
+** together with Expr.zToken strings.
+**
+** If the EP_Reduced and EP_TokenOnly flags are set when
+** an Expr object is truncated.  When EP_Reduced is set, then all
+** the child Expr objects in the Expr.pLeft and Expr.pRight subtrees
+** are contained within the same memory allocation.  Note, however, that
+** the subtrees in Expr.x.pList or Expr.x.pSelect are always separately
+** allocated, regardless of whether or not EP_Reduced is set.
+*/
+struct Expr {
+  u8 op;                 /* Operation performed by this node */
+  char affinity;         /* The affinity of the column or 0 if not a column */
+  u16 flags;             /* Various flags.  EP_* See below */
+  union {
+    char *zToken;          /* Token value. Zero terminated and dequoted */
+    int iValue;            /* Non-negative integer value if EP_IntValue */
+  } u;
+
+  /* If the EP_TokenOnly flag is set in the Expr.flags mask, then no
+  ** space is allocated for the fields below this point. An attempt to
+  ** access them will result in a segfault or malfunction. 
+  *********************************************************************/
+
+  Expr *pLeft;           /* Left subnode */
+  Expr *pRight;          /* Right subnode */
+  union {
+    ExprList *pList;     /* Function arguments or in "<expr> IN (<expr-list)" */
+    Select *pSelect;     /* Used for sub-selects and "<expr> IN (<select>)" */
+  } x;
+  CollSeq *pColl;        /* The collation type of the column or 0 */
+
+  /* If the EP_Reduced flag is set in the Expr.flags mask, then no
+  ** space is allocated for the fields below this point. An attempt to
+  ** access them will result in a segfault or malfunction.
+  *********************************************************************/
+
+  int iTable;            /* TK_COLUMN: cursor number of table holding column
+                         ** TK_REGISTER: register number
+                         ** TK_TRIGGER: 1 -> new, 0 -> old */
+  ynVar iColumn;         /* TK_COLUMN: column index.  -1 for rowid.
+                         ** TK_VARIABLE: variable number (always >= 1). */
+  i16 iAgg;              /* Which entry in pAggInfo->aCol[] or ->aFunc[] */
+  i16 iRightJoinTable;   /* If EP_FromJoin, the right table of the join */
+  u8 flags2;             /* Second set of flags.  EP2_... */
+  u8 op2;                /* If a TK_REGISTER, the original value of Expr.op */
+  AggInfo *pAggInfo;     /* Used by TK_AGG_COLUMN and TK_AGG_FUNCTION */
+  Table *pTab;           /* Table for TK_COLUMN expressions. */
+#if SQLITE_MAX_EXPR_DEPTH>0
+  int nHeight;           /* Height of the tree headed by this node */
+#endif
+};
+
+/*
+** The following are the meanings of bits in the Expr.flags field.
+*/
+#define EP_FromJoin   0x0001  /* Originated in ON or USING clause of a join */
+#define EP_Agg        0x0002  /* Contains one or more aggregate functions */
+#define EP_Resolved   0x0004  /* IDs have been resolved to COLUMNs */
+#define EP_Error      0x0008  /* Expression contains one or more errors */
+#define EP_Distinct   0x0010  /* Aggregate function with DISTINCT keyword */
+#define EP_VarSelect  0x0020  /* pSelect is correlated, not constant */
+#define EP_DblQuoted  0x0040  /* token.z was originally in "..." */
+#define EP_InfixFunc  0x0080  /* True for an infix function: LIKE, GLOB, etc */
+#define EP_ExpCollate 0x0100  /* Collating sequence specified explicitly */
+#define EP_FixedDest  0x0200  /* Result needed in a specific register */
+#define EP_IntValue   0x0400  /* Integer value contained in u.iValue */
+#define EP_xIsSelect  0x0800  /* x.pSelect is valid (otherwise x.pList is) */
+
+#define EP_Reduced    0x1000  /* Expr struct is EXPR_REDUCEDSIZE bytes only */
+#define EP_TokenOnly  0x2000  /* Expr struct is EXPR_TOKENONLYSIZE bytes only */
+#define EP_Static     0x4000  /* Held in memory not obtained from malloc() */
+
+/*
+** The following are the meanings of bits in the Expr.flags2 field.
+*/
+#define EP2_MallocedToken  0x0001  /* Need to sqlite3DbFree() Expr.zToken */
+#define EP2_Irreducible    0x0002  /* Cannot EXPRDUP_REDUCE this Expr */
+
+/*
+** The pseudo-routine sqlite3ExprSetIrreducible sets the EP2_Irreducible
+** flag on an expression structure.  This flag is used for VV&A only.  The
+** routine is implemented as a macro that only works when in debugging mode,
+** so as not to burden production code.
+*/
+#ifdef SQLITE_DEBUG
+# define ExprSetIrreducible(X)  (X)->flags2 |= EP2_Irreducible
+#else
+# define ExprSetIrreducible(X)
+#endif
+
+/*
+** These macros can be used to test, set, or clear bits in the 
+** Expr.flags field.
+*/
+#define ExprHasProperty(E,P)     (((E)->flags&(P))==(P))
+#define ExprHasAnyProperty(E,P)  (((E)->flags&(P))!=0)
+#define ExprSetProperty(E,P)     (E)->flags|=(P)
+#define ExprClearProperty(E,P)   (E)->flags&=~(P)
+
+/*
+** Macros to determine the number of bytes required by a normal Expr 
+** struct, an Expr struct with the EP_Reduced flag set in Expr.flags 
+** and an Expr struct with the EP_TokenOnly flag set.
+*/
+#define EXPR_FULLSIZE           sizeof(Expr)           /* Full size */
+#define EXPR_REDUCEDSIZE        offsetof(Expr,iTable)  /* Common features */
+#define EXPR_TOKENONLYSIZE      offsetof(Expr,pLeft)   /* Fewer features */
+
+/*
+** Flags passed to the sqlite3ExprDup() function. See the header comment 
+** above sqlite3ExprDup() for details.
+*/
+#define EXPRDUP_REDUCE         0x0001  /* Used reduced-size Expr nodes */
+
+/*
+** A list of expressions.  Each expression may optionally have a
+** name.  An expr/name combination can be used in several ways, such
+** as the list of "expr AS ID" fields following a "SELECT" or in the
+** list of "ID = expr" items in an UPDATE.  A list of expressions can
+** also be used as the argument to a function, in which case the a.zName
+** field is not used.
+*/
+struct ExprList {
+  int nExpr;             /* Number of expressions on the list */
+  int nAlloc;            /* Number of entries allocated below */
+  int iECursor;          /* VDBE Cursor associated with this ExprList */
+  struct ExprList_item {
+    Expr *pExpr;           /* The list of expressions */
+    char *zName;           /* Token associated with this expression */
+    char *zSpan;           /* Original text of the expression */
+    u8 sortOrder;          /* 1 for DESC or 0 for ASC */
+    u8 done;               /* A flag to indicate when processing is finished */
+    u16 iCol;              /* For ORDER BY, column number in result set */
+    u16 iAlias;            /* Index into Parse.aAlias[] for zName */
+  } *a;                  /* One entry for each expression */
+};
+
+/*
+** An instance of this structure is used by the parser to record both
+** the parse tree for an expression and the span of input text for an
+** expression.
+*/
+struct ExprSpan {
+  Expr *pExpr;          /* The expression parse tree */
+  const char *zStart;   /* First character of input text */
+  const char *zEnd;     /* One character past the end of input text */
+};
+
+/*
+** An instance of this structure can hold a simple list of identifiers,
+** such as the list "a,b,c" in the following statements:
+**
+**      INSERT INTO t(a,b,c) VALUES ...;
+**      CREATE INDEX idx ON t(a,b,c);
+**      CREATE TRIGGER trig BEFORE UPDATE ON t(a,b,c) ...;
+**
+** The IdList.a.idx field is used when the IdList represents the list of
+** column names after a table name in an INSERT statement.  In the statement
+**
+**     INSERT INTO t(a,b,c) ...
+**
+** If "a" is the k-th column of table "t", then IdList.a[0].idx==k.
+*/
+struct IdList {
+  struct IdList_item {
+    char *zName;      /* Name of the identifier */
+    int idx;          /* Index in some Table.aCol[] of a column named zName */
+  } *a;
+  int nId;         /* Number of identifiers on the list */
+  int nAlloc;      /* Number of entries allocated for a[] below */
+};
+
+/*
+** The bitmask datatype defined below is used for various optimizations.
+**
+** Changing this from a 64-bit to a 32-bit type limits the number of
+** tables in a join to 32 instead of 64.  But it also reduces the size
+** of the library by 738 bytes on ix86.
+*/
+typedef u64 Bitmask;
+
+/*
+** The number of bits in a Bitmask.  "BMS" means "BitMask Size".
+*/
+#define BMS  ((int)(sizeof(Bitmask)*8))
+
+/*
+** The following structure describes the FROM clause of a SELECT statement.
+** Each table or subquery in the FROM clause is a separate element of
+** the SrcList.a[] array.
+**
+** With the addition of multiple database support, the following structure
+** can also be used to describe a particular table such as the table that
+** is modified by an INSERT, DELETE, or UPDATE statement.  In standard SQL,
+** such a table must be a simple name: ID.  But in SQLite, the table can
+** now be identified by a database name, a dot, then the table name: ID.ID.
+**
+** The jointype starts out showing the join type between the current table
+** and the next table on the list.  The parser builds the list this way.
+** But sqlite3SrcListShiftJoinType() later shifts the jointypes so that each
+** jointype expresses the join between the table and the previous table.
+**
+** In the colUsed field, the high-order bit (bit 63) is set if the table
+** contains more than 63 columns and the 64-th or later column is used.
+*/
+struct SrcList {
+  i16 nSrc;        /* Number of tables or subqueries in the FROM clause */
+  i16 nAlloc;      /* Number of entries allocated in a[] below */
+  struct SrcList_item {
+    char *zDatabase;  /* Name of database holding this table */
+    char *zName;      /* Name of the table */
+    char *zAlias;     /* The "B" part of a "A AS B" phrase.  zName is the "A" */
+    Table *pTab;      /* An SQL table corresponding to zName */
+    Select *pSelect;  /* A SELECT statement used in place of a table name */
+    u8 isPopulated;   /* Temporary table associated with SELECT is populated */
+    u8 jointype;      /* Type of join between this able and the previous */
+    u8 notIndexed;    /* True if there is a NOT INDEXED clause */
+#ifndef SQLITE_OMIT_EXPLAIN
+    u8 iSelectId;     /* If pSelect!=0, the id of the sub-select in EQP */
+#endif
+    int iCursor;      /* The VDBE cursor number used to access this table */
+    Expr *pOn;        /* The ON clause of a join */
+    IdList *pUsing;   /* The USING clause of a join */
+    Bitmask colUsed;  /* Bit N (1<<N) set if column N of pTab is used */
+    char *zIndex;     /* Identifier from "INDEXED BY <zIndex>" clause */
+    Index *pIndex;    /* Index structure corresponding to zIndex, if any */
+  } a[1];             /* One entry for each identifier on the list */
+};
+
+/*
+** Permitted values of the SrcList.a.jointype field
+*/
+#define JT_INNER     0x0001    /* Any kind of inner or cross join */
+#define JT_CROSS     0x0002    /* Explicit use of the CROSS keyword */
+#define JT_NATURAL   0x0004    /* True for a "natural" join */
+#define JT_LEFT      0x0008    /* Left outer join */
+#define JT_RIGHT     0x0010    /* Right outer join */
+#define JT_OUTER     0x0020    /* The "OUTER" keyword is present */
+#define JT_ERROR     0x0040    /* unknown or unsupported join type */
+
+
+/*
+** A WherePlan object holds information that describes a lookup
+** strategy.
+**
+** This object is intended to be opaque outside of the where.c module.
+** It is included here only so that that compiler will know how big it
+** is.  None of the fields in this object should be used outside of
+** the where.c module.
+**
+** Within the union, pIdx is only used when wsFlags&WHERE_INDEXED is true.
+** pTerm is only used when wsFlags&WHERE_MULTI_OR is true.  And pVtabIdx
+** is only used when wsFlags&WHERE_VIRTUALTABLE is true.  It is never the
+** case that more than one of these conditions is true.
+*/
+struct WherePlan {
+  u32 wsFlags;                   /* WHERE_* flags that describe the strategy */
+  u32 nEq;                       /* Number of == constraints */
+  double nRow;                   /* Estimated number of rows (for EQP) */
+  union {
+    Index *pIdx;                   /* Index when WHERE_INDEXED is true */
+    struct WhereTerm *pTerm;       /* WHERE clause term for OR-search */
+    sqlite3_index_info *pVtabIdx;  /* Virtual table index to use */
+  } u;
+};
+
+/*
+** For each nested loop in a WHERE clause implementation, the WhereInfo
+** structure contains a single instance of this structure.  This structure
+** is intended to be private the the where.c module and should not be
+** access or modified by other modules.
+**
+** The pIdxInfo field is used to help pick the best index on a
+** virtual table.  The pIdxInfo pointer contains indexing
+** information for the i-th table in the FROM clause before reordering.
+** All the pIdxInfo pointers are freed by whereInfoFree() in where.c.
+** All other information in the i-th WhereLevel object for the i-th table
+** after FROM clause ordering.
+*/
+struct WhereLevel {
+  WherePlan plan;       /* query plan for this element of the FROM clause */
+  int iLeftJoin;        /* Memory cell used to implement LEFT OUTER JOIN */
+  int iTabCur;          /* The VDBE cursor used to access the table */
+  int iIdxCur;          /* The VDBE cursor used to access pIdx */
+  int addrBrk;          /* Jump here to break out of the loop */
+  int addrNxt;          /* Jump here to start the next IN combination */
+  int addrCont;         /* Jump here to continue with the next loop cycle */
+  int addrFirst;        /* First instruction of interior of the loop */
+  u8 iFrom;             /* Which entry in the FROM clause */
+  u8 op, p5;            /* Opcode and P5 of the opcode that ends the loop */
+  int p1, p2;           /* Operands of the opcode used to ends the loop */
+  union {               /* Information that depends on plan.wsFlags */
+    struct {
+      int nIn;              /* Number of entries in aInLoop[] */
+      struct InLoop {
+        int iCur;              /* The VDBE cursor used by this IN operator */
+        int addrInTop;         /* Top of the IN loop */
+      } *aInLoop;           /* Information about each nested IN operator */
+    } in;                 /* Used when plan.wsFlags&WHERE_IN_ABLE */
+  } u;
+
+  /* The following field is really not part of the current level.  But
+  ** we need a place to cache virtual table index information for each
+  ** virtual table in the FROM clause and the WhereLevel structure is
+  ** a convenient place since there is one WhereLevel for each FROM clause
+  ** element.
+  */
+  sqlite3_index_info *pIdxInfo;  /* Index info for n-th source table */
+};
+
+/*
+** Flags appropriate for the wctrlFlags parameter of sqlite3WhereBegin()
+** and the WhereInfo.wctrlFlags member.
+*/
+#define WHERE_ORDERBY_NORMAL   0x0000 /* No-op */
+#define WHERE_ORDERBY_MIN      0x0001 /* ORDER BY processing for min() func */
+#define WHERE_ORDERBY_MAX      0x0002 /* ORDER BY processing for max() func */
+#define WHERE_ONEPASS_DESIRED  0x0004 /* Want to do one-pass UPDATE/DELETE */
+#define WHERE_DUPLICATES_OK    0x0008 /* Ok to return a row more than once */
+#define WHERE_OMIT_OPEN        0x0010 /* Table cursors are already open */
+#define WHERE_OMIT_CLOSE       0x0020 /* Omit close of table & index cursors */
+#define WHERE_FORCE_TABLE      0x0040 /* Do not use an index-only search */
+#define WHERE_ONETABLE_ONLY    0x0080 /* Only code the 1st table in pTabList */
+
+/*
+** The WHERE clause processing routine has two halves.  The
+** first part does the start of the WHERE loop and the second
+** half does the tail of the WHERE loop.  An instance of
+** this structure is returned by the first half and passed
+** into the second half to give some continuity.
+*/
+struct WhereInfo {
+  Parse *pParse;       /* Parsing and code generating context */
+  u16 wctrlFlags;      /* Flags originally passed to sqlite3WhereBegin() */
+  u8 okOnePass;        /* Ok to use one-pass algorithm for UPDATE or DELETE */
+  u8 untestedTerms;    /* Not all WHERE terms resolved by outer loop */
+  SrcList *pTabList;             /* List of tables in the join */
+  int iTop;                      /* The very beginning of the WHERE loop */
+  int iContinue;                 /* Jump here to continue with next record */
+  int iBreak;                    /* Jump here to break out of the loop */
+  int nLevel;                    /* Number of nested loop */
+  struct WhereClause *pWC;       /* Decomposition of the WHERE clause */
+  double savedNQueryLoop;        /* pParse->nQueryLoop outside the WHERE loop */
+  double nRowOut;                /* Estimated number of output rows */
+  WhereLevel a[1];               /* Information about each nest loop in WHERE */
+};
+
+/*
+** A NameContext defines a context in which to resolve table and column
+** names.  The context consists of a list of tables (the pSrcList) field and
+** a list of named expression (pEList).  The named expression list may
+** be NULL.  The pSrc corresponds to the FROM clause of a SELECT or
+** to the table being operated on by INSERT, UPDATE, or DELETE.  The
+** pEList corresponds to the result set of a SELECT and is NULL for
+** other statements.
+**
+** NameContexts can be nested.  When resolving names, the inner-most 
+** context is searched first.  If no match is found, the next outer
+** context is checked.  If there is still no match, the next context
+** is checked.  This process continues until either a match is found
+** or all contexts are check.  When a match is found, the nRef member of
+** the context containing the match is incremented. 
+**
+** Each subquery gets a new NameContext.  The pNext field points to the
+** NameContext in the parent query.  Thus the process of scanning the
+** NameContext list corresponds to searching through successively outer
+** subqueries looking for a match.
+*/
+struct NameContext {
+  Parse *pParse;       /* The parser */
+  SrcList *pSrcList;   /* One or more tables used to resolve names */
+  ExprList *pEList;    /* Optional list of named expressions */
+  int nRef;            /* Number of names resolved by this context */
+  int nErr;            /* Number of errors encountered while resolving names */
+  u8 allowAgg;         /* Aggregate functions allowed here */
+  u8 hasAgg;           /* True if aggregates are seen */
+  u8 isCheck;          /* True if resolving names in a CHECK constraint */
+  int nDepth;          /* Depth of subquery recursion. 1 for no recursion */
+  AggInfo *pAggInfo;   /* Information about aggregates at this level */
+  NameContext *pNext;  /* Next outer name context.  NULL for outermost */
+};
+
+/*
+** An instance of the following structure contains all information
+** needed to generate code for a single SELECT statement.
+**
+** nLimit is set to -1 if there is no LIMIT clause.  nOffset is set to 0.
+** If there is a LIMIT clause, the parser sets nLimit to the value of the
+** limit and nOffset to the value of the offset (or 0 if there is not
+** offset).  But later on, nLimit and nOffset become the memory locations
+** in the VDBE that record the limit and offset counters.
+**
+** addrOpenEphm[] entries contain the address of OP_OpenEphemeral opcodes.
+** These addresses must be stored so that we can go back and fill in
+** the P4_KEYINFO and P2 parameters later.  Neither the KeyInfo nor
+** the number of columns in P2 can be computed at the same time
+** as the OP_OpenEphm instruction is coded because not
+** enough information about the compound query is known at that point.
+** The KeyInfo for addrOpenTran[0] and [1] contains collating sequences
+** for the result set.  The KeyInfo for addrOpenTran[2] contains collating
+** sequences for the ORDER BY clause.
+*/
+struct Select {
+  ExprList *pEList;      /* The fields of the result */
+  u8 op;                 /* One of: TK_UNION TK_ALL TK_INTERSECT TK_EXCEPT */
+  char affinity;         /* MakeRecord with this affinity for SRT_Set */
+  u16 selFlags;          /* Various SF_* values */
+  SrcList *pSrc;         /* The FROM clause */
+  Expr *pWhere;          /* The WHERE clause */
+  ExprList *pGroupBy;    /* The GROUP BY clause */
+  Expr *pHaving;         /* The HAVING clause */
+  ExprList *pOrderBy;    /* The ORDER BY clause */
+  Select *pPrior;        /* Prior select in a compound select statement */
+  Select *pNext;         /* Next select to the left in a compound */
+  Select *pRightmost;    /* Right-most select in a compound select statement */
+  Expr *pLimit;          /* LIMIT expression. NULL means not used. */
+  Expr *pOffset;         /* OFFSET expression. NULL means not used. */
+  int iLimit, iOffset;   /* Memory registers holding LIMIT & OFFSET counters */
+  int addrOpenEphm[3];   /* OP_OpenEphem opcodes related to this select */
+  double nSelectRow;     /* Estimated number of result rows */
+};
+
+/*
+** Allowed values for Select.selFlags.  The "SF" prefix stands for
+** "Select Flag".
+*/
+#define SF_Distinct        0x0001  /* Output should be DISTINCT */
+#define SF_Resolved        0x0002  /* Identifiers have been resolved */
+#define SF_Aggregate       0x0004  /* Contains aggregate functions */
+#define SF_UsesEphemeral   0x0008  /* Uses the OpenEphemeral opcode */
+#define SF_Expanded        0x0010  /* sqlite3SelectExpand() called on this */
+#define SF_HasTypeInfo     0x0020  /* FROM subqueries have Table metadata */
+
+
+/*
+** The results of a select can be distributed in several ways.  The
+** "SRT" prefix means "SELECT Result Type".
+*/
+#define SRT_Union        1  /* Store result as keys in an index */
+#define SRT_Except       2  /* Remove result from a UNION index */
+#define SRT_Exists       3  /* Store 1 if the result is not empty */
+#define SRT_Discard      4  /* Do not save the results anywhere */
+
+/* The ORDER BY clause is ignored for all of the above */
+#define IgnorableOrderby(X) ((X->eDest)<=SRT_Discard)
+
+#define SRT_Output       5  /* Output each row of result */
+#define SRT_Mem          6  /* Store result in a memory cell */
+#define SRT_Set          7  /* Store results as keys in an index */
+#define SRT_Table        8  /* Store result as data with an automatic rowid */
+#define SRT_EphemTab     9  /* Create transient tab and store like SRT_Table */
+#define SRT_Coroutine   10  /* Generate a single row of result */
+
+/*
+** A structure used to customize the behavior of sqlite3Select(). See
+** comments above sqlite3Select() for details.
+*/
+typedef struct SelectDest SelectDest;
+struct SelectDest {
+  u8 eDest;         /* How to dispose of the results */
+  u8 affinity;      /* Affinity used when eDest==SRT_Set */
+  int iParm;        /* A parameter used by the eDest disposal method */
+  int iMem;         /* Base register where results are written */
+  int nMem;         /* Number of registers allocated */
+};
+
+/*
+** During code generation of statements that do inserts into AUTOINCREMENT 
+** tables, the following information is attached to the Table.u.autoInc.p
+** pointer of each autoincrement table to record some side information that
+** the code generator needs.  We have to keep per-table autoincrement
+** information in case inserts are down within triggers.  Triggers do not
+** normally coordinate their activities, but we do need to coordinate the
+** loading and saving of autoincrement information.
+*/
+struct AutoincInfo {
+  AutoincInfo *pNext;   /* Next info block in a list of them all */
+  Table *pTab;          /* Table this info block refers to */
+  int iDb;              /* Index in sqlite3.aDb[] of database holding pTab */
+  int regCtr;           /* Memory register holding the rowid counter */
+};
+
+/*
+** Size of the column cache
+*/
+#ifndef SQLITE_N_COLCACHE
+# define SQLITE_N_COLCACHE 10
+#endif
+
+/*
+** At least one instance of the following structure is created for each 
+** trigger that may be fired while parsing an INSERT, UPDATE or DELETE
+** statement. All such objects are stored in the linked list headed at
+** Parse.pTriggerPrg and deleted once statement compilation has been
+** completed.
+**
+** A Vdbe sub-program that implements the body and WHEN clause of trigger
+** TriggerPrg.pTrigger, assuming a default ON CONFLICT clause of
+** TriggerPrg.orconf, is stored in the TriggerPrg.pProgram variable.
+** The Parse.pTriggerPrg list never contains two entries with the same
+** values for both pTrigger and orconf.
+**
+** The TriggerPrg.aColmask[0] variable is set to a mask of old.* columns
+** accessed (or set to 0 for triggers fired as a result of INSERT 
+** statements). Similarly, the TriggerPrg.aColmask[1] variable is set to
+** a mask of new.* columns used by the program.
+*/
+struct TriggerPrg {
+  Trigger *pTrigger;      /* Trigger this program was coded from */
+  int orconf;             /* Default ON CONFLICT policy */
+  SubProgram *pProgram;   /* Program implementing pTrigger/orconf */
+  u32 aColmask[2];        /* Masks of old.*, new.* columns accessed */
+  TriggerPrg *pNext;      /* Next entry in Parse.pTriggerPrg list */
+};
+
+/*
+** The yDbMask datatype for the bitmask of all attached databases.
+*/
+#if SQLITE_MAX_ATTACHED>30
+  typedef sqlite3_uint64 yDbMask;
+#else
+  typedef unsigned int yDbMask;
+#endif
+
+/*
+** An SQL parser context.  A copy of this structure is passed through
+** the parser and down into all the parser action routine in order to
+** carry around information that is global to the entire parse.
+**
+** The structure is divided into two parts.  When the parser and code
+** generate call themselves recursively, the first part of the structure
+** is constant but the second part is reset at the beginning and end of
+** each recursion.
+**
+** The nTableLock and aTableLock variables are only used if the shared-cache 
+** feature is enabled (if sqlite3Tsd()->useSharedData is true). They are
+** used to store the set of table-locks required by the statement being
+** compiled. Function sqlite3TableLock() is used to add entries to the
+** list.
+*/
+struct Parse {
+  sqlite3 *db;         /* The main database structure */
+  int rc;              /* Return code from execution */
+  char *zErrMsg;       /* An error message */
+  Vdbe *pVdbe;         /* An engine for executing database bytecode */
+  u8 colNamesSet;      /* TRUE after OP_ColumnName has been issued to pVdbe */
+  u8 nameClash;        /* A permanent table name clashes with temp table name */
+  u8 checkSchema;      /* Causes schema cookie check after an error */
+  u8 nested;           /* Number of nested calls to the parser/code generator */
+  u8 parseError;       /* True after a parsing error.  Ticket #1794 */
+  u8 nTempReg;         /* Number of temporary registers in aTempReg[] */
+  u8 nTempInUse;       /* Number of aTempReg[] currently checked out */
+  int aTempReg[8];     /* Holding area for temporary registers */
+  int nRangeReg;       /* Size of the temporary register block */
+  int iRangeReg;       /* First register in temporary register block */
+  int nErr;            /* Number of errors seen */
+  int nTab;            /* Number of previously allocated VDBE cursors */
+  int nMem;            /* Number of memory cells used so far */
+  int nSet;            /* Number of sets used so far */
+  int ckBase;          /* Base register of data during check constraints */
+  int iCacheLevel;     /* ColCache valid when aColCache[].iLevel<=iCacheLevel */
+  int iCacheCnt;       /* Counter used to generate aColCache[].lru values */
+  u8 nColCache;        /* Number of entries in the column cache */
+  u8 iColCache;        /* Next entry of the cache to replace */
+  struct yColCache {
+    int iTable;           /* Table cursor number */
+    int iColumn;          /* Table column number */
+    u8 tempReg;           /* iReg is a temp register that needs to be freed */
+    int iLevel;           /* Nesting level */
+    int iReg;             /* Reg with value of this column. 0 means none. */
+    int lru;              /* Least recently used entry has the smallest value */
+  } aColCache[SQLITE_N_COLCACHE];  /* One for each column cache entry */
+  yDbMask writeMask;   /* Start a write transaction on these databases */
+  yDbMask cookieMask;  /* Bitmask of schema verified databases */
+  u8 isMultiWrite;     /* True if statement may affect/insert multiple rows */
+  u8 mayAbort;         /* True if statement may throw an ABORT exception */
+  int cookieGoto;      /* Address of OP_Goto to cookie verifier subroutine */
+  int cookieValue[SQLITE_MAX_ATTACHED+2];  /* Values of cookies to verify */
+#ifndef SQLITE_OMIT_SHARED_CACHE
+  int nTableLock;        /* Number of locks in aTableLock */
+  TableLock *aTableLock; /* Required table locks for shared-cache mode */
+#endif
+  int regRowid;        /* Register holding rowid of CREATE TABLE entry */
+  int regRoot;         /* Register holding root page number for new objects */
+  AutoincInfo *pAinc;  /* Information about AUTOINCREMENT counters */
+  int nMaxArg;         /* Max args passed to user function by sub-program */
+
+  /* Information used while coding trigger programs. */
+  Parse *pToplevel;    /* Parse structure for main program (or NULL) */
+  Table *pTriggerTab;  /* Table triggers are being coded for */
+  u32 oldmask;         /* Mask of old.* columns referenced */
+  u32 newmask;         /* Mask of new.* columns referenced */
+  u8 eTriggerOp;       /* TK_UPDATE, TK_INSERT or TK_DELETE */
+  u8 eOrconf;          /* Default ON CONFLICT policy for trigger steps */
+  u8 disableTriggers;  /* True to disable triggers */
+  double nQueryLoop;   /* Estimated number of iterations of a query */
+
+  /* Above is constant between recursions.  Below is reset before and after
+  ** each recursion */
+
+  int nVar;            /* Number of '?' variables seen in the SQL so far */
+  int nVarExpr;        /* Number of used slots in apVarExpr[] */
+  int nVarExprAlloc;   /* Number of allocated slots in apVarExpr[] */
+  Expr **apVarExpr;    /* Pointers to :aaa and $aaaa wildcard expressions */
+  Vdbe *pReprepare;    /* VM being reprepared (sqlite3Reprepare()) */
+  int nAlias;          /* Number of aliased result set columns */
+  int nAliasAlloc;     /* Number of allocated slots for aAlias[] */
+  int *aAlias;         /* Register used to hold aliased result */
+  u8 explain;          /* True if the EXPLAIN flag is found on the query */
+  Token sNameToken;    /* Token with unqualified schema object name */
+  Token sLastToken;    /* The last token parsed */
+  const char *zTail;   /* All SQL text past the last semicolon parsed */
+  Table *pNewTable;    /* A table being constructed by CREATE TABLE */
+  Trigger *pNewTrigger;     /* Trigger under construct by a CREATE TRIGGER */
+  const char *zAuthContext; /* The 6th parameter to db->xAuth callbacks */
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  Token sArg;                /* Complete text of a module argument */
+  u8 declareVtab;            /* True if inside sqlite3_declare_vtab() */
+  int nVtabLock;             /* Number of virtual tables to lock */
+  Table **apVtabLock;        /* Pointer to virtual tables needing locking */
+#endif
+  int nHeight;            /* Expression tree height of current sub-select */
+  Table *pZombieTab;      /* List of Table objects to delete after code gen */
+  TriggerPrg *pTriggerPrg;    /* Linked list of coded triggers */
+
+#ifndef SQLITE_OMIT_EXPLAIN
+  int iSelectId;
+  int iNextSelectId;
+#endif
+};
+
+#ifdef SQLITE_OMIT_VIRTUALTABLE
+  #define IN_DECLARE_VTAB 0
+#else
+  #define IN_DECLARE_VTAB (pParse->declareVtab)
+#endif
+
+/*
+** An instance of the following structure can be declared on a stack and used
+** to save the Parse.zAuthContext value so that it can be restored later.
+*/
+struct AuthContext {
+  const char *zAuthContext;   /* Put saved Parse.zAuthContext here */
+  Parse *pParse;              /* The Parse structure */
+};
+
+/*
+** Bitfield flags for P5 value in OP_Insert and OP_Delete
+*/
+#define OPFLAG_NCHANGE       0x01    /* Set to update db->nChange */
+#define OPFLAG_LASTROWID     0x02    /* Set to update db->lastRowid */
+#define OPFLAG_ISUPDATE      0x04    /* This OP_Insert is an sql UPDATE */
+#define OPFLAG_APPEND        0x08    /* This is likely to be an append */
+#define OPFLAG_USESEEKRESULT 0x10    /* Try to avoid a seek in BtreeInsert() */
+#define OPFLAG_CLEARCACHE    0x20    /* Clear pseudo-table cache in OP_Column */
+
+/*
+ * Each trigger present in the database schema is stored as an instance of
+ * struct Trigger. 
+ *
+ * Pointers to instances of struct Trigger are stored in two ways.
+ * 1. In the "trigHash" hash table (part of the sqlite3* that represents the 
+ *    database). This allows Trigger structures to be retrieved by name.
+ * 2. All triggers associated with a single table form a linked list, using the
+ *    pNext member of struct Trigger. A pointer to the first element of the
+ *    linked list is stored as the "pTrigger" member of the associated
+ *    struct Table.
+ *
+ * The "step_list" member points to the first element of a linked list
+ * containing the SQL statements specified as the trigger program.
+ */
+struct Trigger {
+  char *zName;            /* The name of the trigger                        */
+  char *table;            /* The table or view to which the trigger applies */
+  u8 op;                  /* One of TK_DELETE, TK_UPDATE, TK_INSERT         */
+  u8 tr_tm;               /* One of TRIGGER_BEFORE, TRIGGER_AFTER */
+  Expr *pWhen;            /* The WHEN clause of the expression (may be NULL) */
+  IdList *pColumns;       /* If this is an UPDATE OF <column-list> trigger,
+                             the <column-list> is stored here */
+  Schema *pSchema;        /* Schema containing the trigger */
+  Schema *pTabSchema;     /* Schema containing the table */
+  TriggerStep *step_list; /* Link list of trigger program steps             */
+  Trigger *pNext;         /* Next trigger associated with the table */
+};
+
+/*
+** A trigger is either a BEFORE or an AFTER trigger.  The following constants
+** determine which. 
+**
+** If there are multiple triggers, you might of some BEFORE and some AFTER.
+** In that cases, the constants below can be ORed together.
+*/
+#define TRIGGER_BEFORE  1
+#define TRIGGER_AFTER   2
+
+/*
+ * An instance of struct TriggerStep is used to store a single SQL statement
+ * that is a part of a trigger-program. 
+ *
+ * Instances of struct TriggerStep are stored in a singly linked list (linked
+ * using the "pNext" member) referenced by the "step_list" member of the 
+ * associated struct Trigger instance. The first element of the linked list is
+ * the first step of the trigger-program.
+ * 
+ * The "op" member indicates whether this is a "DELETE", "INSERT", "UPDATE" or
+ * "SELECT" statement. The meanings of the other members is determined by the 
+ * value of "op" as follows:
+ *
+ * (op == TK_INSERT)
+ * orconf    -> stores the ON CONFLICT algorithm
+ * pSelect   -> If this is an INSERT INTO ... SELECT ... statement, then
+ *              this stores a pointer to the SELECT statement. Otherwise NULL.
+ * target    -> A token holding the quoted name of the table to insert into.
+ * pExprList -> If this is an INSERT INTO ... VALUES ... statement, then
+ *              this stores values to be inserted. Otherwise NULL.
+ * pIdList   -> If this is an INSERT INTO ... (<column-names>) VALUES ... 
+ *              statement, then this stores the column-names to be
+ *              inserted into.
+ *
+ * (op == TK_DELETE)
+ * target    -> A token holding the quoted name of the table to delete from.
+ * pWhere    -> The WHERE clause of the DELETE statement if one is specified.
+ *              Otherwise NULL.
+ * 
+ * (op == TK_UPDATE)
+ * target    -> A token holding the quoted name of the table to update rows of.
+ * pWhere    -> The WHERE clause of the UPDATE statement if one is specified.
+ *              Otherwise NULL.
+ * pExprList -> A list of the columns to update and the expressions to update
+ *              them to. See sqlite3Update() documentation of "pChanges"
+ *              argument.
+ * 
+ */
+struct TriggerStep {
+  u8 op;               /* One of TK_DELETE, TK_UPDATE, TK_INSERT, TK_SELECT */
+  u8 orconf;           /* OE_Rollback etc. */
+  Trigger *pTrig;      /* The trigger that this step is a part of */
+  Select *pSelect;     /* SELECT statment or RHS of INSERT INTO .. SELECT ... */
+  Token target;        /* Target table for DELETE, UPDATE, INSERT */
+  Expr *pWhere;        /* The WHERE clause for DELETE or UPDATE steps */
+  ExprList *pExprList; /* SET clause for UPDATE.  VALUES clause for INSERT */
+  IdList *pIdList;     /* Column names for INSERT */
+  TriggerStep *pNext;  /* Next in the link-list */
+  TriggerStep *pLast;  /* Last element in link-list. Valid for 1st elem only */
+};
+
+/*
+** The following structure contains information used by the sqliteFix...
+** routines as they walk the parse tree to make database references
+** explicit.  
+*/
+typedef struct DbFixer DbFixer;
+struct DbFixer {
+  Parse *pParse;      /* The parsing context.  Error messages written here */
+  const char *zDb;    /* Make sure all objects are contained in this database */
+  const char *zType;  /* Type of the container - used for error messages */
+  const Token *pName; /* Name of the container - used for error messages */
+};
+
+/*
+** An objected used to accumulate the text of a string where we
+** do not necessarily know how big the string will be in the end.
+*/
+struct StrAccum {
+  sqlite3 *db;         /* Optional database for lookaside.  Can be NULL */
+  char *zBase;         /* A base allocation.  Not from malloc. */
+  char *zText;         /* The string collected so far */
+  int  nChar;          /* Length of the string so far */
+  int  nAlloc;         /* Amount of space allocated in zText */
+  int  mxAlloc;        /* Maximum allowed string length */
+  u8   mallocFailed;   /* Becomes true if any memory allocation fails */
+  u8   useMalloc;      /* 0: none,  1: sqlite3DbMalloc,  2: sqlite3_malloc */
+  u8   tooBig;         /* Becomes true if string size exceeds limits */
+};
+
+/*
+** A pointer to this structure is used to communicate information
+** from sqlite3Init and OP_ParseSchema into the sqlite3InitCallback.
+*/
+typedef struct {
+  sqlite3 *db;        /* The database being initialized */
+  int iDb;            /* 0 for main database.  1 for TEMP, 2.. for ATTACHed */
+  char **pzErrMsg;    /* Error message stored here */
+  int rc;             /* Result code stored here */
+} InitData;
+
+/*
+** Structure containing global configuration data for the SQLite library.
+**
+** This structure also contains some state information.
+*/
+struct Sqlite3Config {
+  int bMemstat;                     /* True to enable memory status */
+  int bCoreMutex;                   /* True to enable core mutexing */
+  int bFullMutex;                   /* True to enable full mutexing */
+  int mxStrlen;                     /* Maximum string length */
+  int szLookaside;                  /* Default lookaside buffer size */
+  int nLookaside;                   /* Default lookaside buffer count */
+  sqlite3_mem_methods m;            /* Low-level memory allocation interface */
+  sqlite3_mutex_methods mutex;      /* Low-level mutex interface */
+  sqlite3_pcache_methods pcache;    /* Low-level page-cache interface */
+  void *pHeap;                      /* Heap storage space */
+  int nHeap;                        /* Size of pHeap[] */
+  int mnReq, mxReq;                 /* Min and max heap requests sizes */
+  void *pScratch;                   /* Scratch memory */
+  int szScratch;                    /* Size of each scratch buffer */
+  int nScratch;                     /* Number of scratch buffers */
+  void *pPage;                      /* Page cache memory */
+  int szPage;                       /* Size of each page in pPage[] */
+  int nPage;                        /* Number of pages in pPage[] */
+  int mxParserStack;                /* maximum depth of the parser stack */
+  int sharedCacheEnabled;           /* true if shared-cache mode enabled */
+  /* The above might be initialized to non-zero.  The following need to always
+  ** initially be zero, however. */
+  int isInit;                       /* True after initialization has finished */
+  int inProgress;                   /* True while initialization in progress */
+  int isMutexInit;                  /* True after mutexes are initialized */
+  int isMallocInit;                 /* True after malloc is initialized */
+  int isPCacheInit;                 /* True after malloc is initialized */
+  sqlite3_mutex *pInitMutex;        /* Mutex used by sqlite3_initialize() */
+  int nRefInitMutex;                /* Number of users of pInitMutex */
+  void (*xLog)(void*,int,const char*); /* Function for logging */
+  void *pLogArg;                       /* First argument to xLog() */
+};
+
+/*
+** Context pointer passed down through the tree-walk.
+*/
+struct Walker {
+  int (*xExprCallback)(Walker*, Expr*);     /* Callback for expressions */
+  int (*xSelectCallback)(Walker*,Select*);  /* Callback for SELECTs */
+  Parse *pParse;                            /* Parser context.  */
+  union {                                   /* Extra data for callback */
+    NameContext *pNC;                          /* Naming context */
+    int i;                                     /* Integer value */
+  } u;
+};
+
+/* Forward declarations */
+SQLITE_PRIVATE int sqlite3WalkExpr(Walker*, Expr*);
+SQLITE_PRIVATE int sqlite3WalkExprList(Walker*, ExprList*);
+SQLITE_PRIVATE int sqlite3WalkSelect(Walker*, Select*);
+SQLITE_PRIVATE int sqlite3WalkSelectExpr(Walker*, Select*);
+SQLITE_PRIVATE int sqlite3WalkSelectFrom(Walker*, Select*);
+
+/*
+** Return code from the parse-tree walking primitives and their
+** callbacks.
+*/
+#define WRC_Continue    0   /* Continue down into children */
+#define WRC_Prune       1   /* Omit children but continue walking siblings */
+#define WRC_Abort       2   /* Abandon the tree walk */
+
+/*
+** Assuming zIn points to the first byte of a UTF-8 character,
+** advance zIn to point to the first byte of the next UTF-8 character.
+*/
+#define SQLITE_SKIP_UTF8(zIn) {                        \
+  if( (*(zIn++))>=0xc0 ){                              \
+    while( (*zIn & 0xc0)==0x80 ){ zIn++; }             \
+  }                                                    \
+}
+
+/*
+** The SQLITE_*_BKPT macros are substitutes for the error codes with
+** the same name but without the _BKPT suffix.  These macros invoke
+** routines that report the line-number on which the error originated
+** using sqlite3_log().  The routines also provide a convenient place
+** to set a debugger breakpoint.
+*/
+SQLITE_PRIVATE int sqlite3CorruptError(int);
+SQLITE_PRIVATE int sqlite3MisuseError(int);
+SQLITE_PRIVATE int sqlite3CantopenError(int);
+#define SQLITE_CORRUPT_BKPT sqlite3CorruptError(__LINE__)
+#define SQLITE_MISUSE_BKPT sqlite3MisuseError(__LINE__)
+#define SQLITE_CANTOPEN_BKPT sqlite3CantopenError(__LINE__)
+
+
+/*
+** FTS4 is really an extension for FTS3.  It is enabled using the
+** SQLITE_ENABLE_FTS3 macro.  But to avoid confusion we also all
+** the SQLITE_ENABLE_FTS4 macro to serve as an alisse for SQLITE_ENABLE_FTS3.
+*/
+#if defined(SQLITE_ENABLE_FTS4) && !defined(SQLITE_ENABLE_FTS3)
+# define SQLITE_ENABLE_FTS3
+#endif
+
+/*
+** The ctype.h header is needed for non-ASCII systems.  It is also
+** needed by FTS3 when FTS3 is included in the amalgamation.
+*/
+#if !defined(SQLITE_ASCII) || \
+    (defined(SQLITE_ENABLE_FTS3) && defined(SQLITE_AMALGAMATION))
+# include <ctype.h>
+#endif
+
+/*
+** The following macros mimic the standard library functions toupper(),
+** isspace(), isalnum(), isdigit() and isxdigit(), respectively. The
+** sqlite versions only work for ASCII characters, regardless of locale.
+*/
+#ifdef SQLITE_ASCII
+# define sqlite3Toupper(x)  ((x)&~(sqlite3CtypeMap[(unsigned char)(x)]&0x20))
+# define sqlite3Isspace(x)   (sqlite3CtypeMap[(unsigned char)(x)]&0x01)
+# define sqlite3Isalnum(x)   (sqlite3CtypeMap[(unsigned char)(x)]&0x06)
+# define sqlite3Isalpha(x)   (sqlite3CtypeMap[(unsigned char)(x)]&0x02)
+# define sqlite3Isdigit(x)   (sqlite3CtypeMap[(unsigned char)(x)]&0x04)
+# define sqlite3Isxdigit(x)  (sqlite3CtypeMap[(unsigned char)(x)]&0x08)
+# define sqlite3Tolower(x)   (sqlite3UpperToLower[(unsigned char)(x)])
+#else
+# define sqlite3Toupper(x)   toupper((unsigned char)(x))
+# define sqlite3Isspace(x)   isspace((unsigned char)(x))
+# define sqlite3Isalnum(x)   isalnum((unsigned char)(x))
+# define sqlite3Isalpha(x)   isalpha((unsigned char)(x))
+# define sqlite3Isdigit(x)   isdigit((unsigned char)(x))
+# define sqlite3Isxdigit(x)  isxdigit((unsigned char)(x))
+# define sqlite3Tolower(x)   tolower((unsigned char)(x))
+#endif
+
+/*
+** Internal function prototypes
+*/
+SQLITE_PRIVATE int sqlite3StrICmp(const char *, const char *);
+SQLITE_PRIVATE int sqlite3Strlen30(const char*);
+#define sqlite3StrNICmp sqlite3_strnicmp
+
+SQLITE_PRIVATE int sqlite3MallocInit(void);
+SQLITE_PRIVATE void sqlite3MallocEnd(void);
+SQLITE_PRIVATE void *sqlite3Malloc(int);
+SQLITE_PRIVATE void *sqlite3MallocZero(int);
+SQLITE_PRIVATE void *sqlite3DbMallocZero(sqlite3*, int);
+SQLITE_PRIVATE void *sqlite3DbMallocRaw(sqlite3*, int);
+SQLITE_PRIVATE char *sqlite3DbStrDup(sqlite3*,const char*);
+SQLITE_PRIVATE char *sqlite3DbStrNDup(sqlite3*,const char*, int);
+SQLITE_PRIVATE void *sqlite3Realloc(void*, int);
+SQLITE_PRIVATE void *sqlite3DbReallocOrFree(sqlite3 *, void *, int);
+SQLITE_PRIVATE void *sqlite3DbRealloc(sqlite3 *, void *, int);
+SQLITE_PRIVATE void sqlite3DbFree(sqlite3*, void*);
+SQLITE_PRIVATE int sqlite3MallocSize(void*);
+SQLITE_PRIVATE int sqlite3DbMallocSize(sqlite3*, void*);
+SQLITE_PRIVATE void *sqlite3ScratchMalloc(int);
+SQLITE_PRIVATE void sqlite3ScratchFree(void*);
+SQLITE_PRIVATE void *sqlite3PageMalloc(int);
+SQLITE_PRIVATE void sqlite3PageFree(void*);
+SQLITE_PRIVATE void sqlite3MemSetDefault(void);
+SQLITE_PRIVATE void sqlite3BenignMallocHooks(void (*)(void), void (*)(void));
+SQLITE_PRIVATE int sqlite3HeapNearlyFull(void);
+
+/*
+** On systems with ample stack space and that support alloca(), make
+** use of alloca() to obtain space for large automatic objects.  By default,
+** obtain space from malloc().
+**
+** The alloca() routine never returns NULL.  This will cause code paths
+** that deal with sqlite3StackAlloc() failures to be unreachable.
+*/
+#ifdef SQLITE_USE_ALLOCA
+# define sqlite3StackAllocRaw(D,N)   alloca(N)
+# define sqlite3StackAllocZero(D,N)  memset(alloca(N), 0, N)
+# define sqlite3StackFree(D,P)       
+#else
+# define sqlite3StackAllocRaw(D,N)   sqlite3DbMallocRaw(D,N)
+# define sqlite3StackAllocZero(D,N)  sqlite3DbMallocZero(D,N)
+# define sqlite3StackFree(D,P)       sqlite3DbFree(D,P)
+#endif
+
+#ifdef SQLITE_ENABLE_MEMSYS3
+SQLITE_PRIVATE const sqlite3_mem_methods *sqlite3MemGetMemsys3(void);
+#endif
+#ifdef SQLITE_ENABLE_MEMSYS5
+SQLITE_PRIVATE const sqlite3_mem_methods *sqlite3MemGetMemsys5(void);
+#endif
+
+
+#ifndef SQLITE_MUTEX_OMIT
+SQLITE_PRIVATE   sqlite3_mutex_methods const *sqlite3DefaultMutex(void);
+SQLITE_PRIVATE   sqlite3_mutex_methods const *sqlite3NoopMutex(void);
+SQLITE_PRIVATE   sqlite3_mutex *sqlite3MutexAlloc(int);
+SQLITE_PRIVATE   int sqlite3MutexInit(void);
+SQLITE_PRIVATE   int sqlite3MutexEnd(void);
+#endif
+
+SQLITE_PRIVATE int sqlite3StatusValue(int);
+SQLITE_PRIVATE void sqlite3StatusAdd(int, int);
+SQLITE_PRIVATE void sqlite3StatusSet(int, int);
+
+#ifndef SQLITE_OMIT_FLOATING_POINT
+SQLITE_PRIVATE   int sqlite3IsNaN(double);
+#else
+# define sqlite3IsNaN(X)  0
+#endif
+
+SQLITE_PRIVATE void sqlite3VXPrintf(StrAccum*, int, const char*, va_list);
+#ifndef SQLITE_OMIT_TRACE
+SQLITE_PRIVATE void sqlite3XPrintf(StrAccum*, const char*, ...);
+#endif
+SQLITE_PRIVATE char *sqlite3MPrintf(sqlite3*,const char*, ...);
+SQLITE_PRIVATE char *sqlite3VMPrintf(sqlite3*,const char*, va_list);
+SQLITE_PRIVATE char *sqlite3MAppendf(sqlite3*,char*,const char*,...);
+#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
+SQLITE_PRIVATE   void sqlite3DebugPrintf(const char*, ...);
+#endif
+#if defined(SQLITE_TEST)
+SQLITE_PRIVATE   void *sqlite3TestTextToPtr(const char*);
+#endif
+SQLITE_PRIVATE void sqlite3SetString(char **, sqlite3*, const char*, ...);
+SQLITE_PRIVATE void sqlite3ErrorMsg(Parse*, const char*, ...);
+SQLITE_PRIVATE int sqlite3Dequote(char*);
+SQLITE_PRIVATE int sqlite3KeywordCode(const unsigned char*, int);
+SQLITE_PRIVATE int sqlite3RunParser(Parse*, const char*, char **);
+SQLITE_PRIVATE void sqlite3FinishCoding(Parse*);
+SQLITE_PRIVATE int sqlite3GetTempReg(Parse*);
+SQLITE_PRIVATE void sqlite3ReleaseTempReg(Parse*,int);
+SQLITE_PRIVATE int sqlite3GetTempRange(Parse*,int);
+SQLITE_PRIVATE void sqlite3ReleaseTempRange(Parse*,int,int);
+SQLITE_PRIVATE Expr *sqlite3ExprAlloc(sqlite3*,int,const Token*,int);
+SQLITE_PRIVATE Expr *sqlite3Expr(sqlite3*,int,const char*);
+SQLITE_PRIVATE void sqlite3ExprAttachSubtrees(sqlite3*,Expr*,Expr*,Expr*);
+SQLITE_PRIVATE Expr *sqlite3PExpr(Parse*, int, Expr*, Expr*, const Token*);
+SQLITE_PRIVATE Expr *sqlite3ExprAnd(sqlite3*,Expr*, Expr*);
+SQLITE_PRIVATE Expr *sqlite3ExprFunction(Parse*,ExprList*, Token*);
+SQLITE_PRIVATE void sqlite3ExprAssignVarNumber(Parse*, Expr*);
+SQLITE_PRIVATE void sqlite3ExprDelete(sqlite3*, Expr*);
+SQLITE_PRIVATE ExprList *sqlite3ExprListAppend(Parse*,ExprList*,Expr*);
+SQLITE_PRIVATE void sqlite3ExprListSetName(Parse*,ExprList*,Token*,int);
+SQLITE_PRIVATE void sqlite3ExprListSetSpan(Parse*,ExprList*,ExprSpan*);
+SQLITE_PRIVATE void sqlite3ExprListDelete(sqlite3*, ExprList*);
+SQLITE_PRIVATE int sqlite3Init(sqlite3*, char**);
+SQLITE_PRIVATE int sqlite3InitCallback(void*, int, char**, char**);
+SQLITE_PRIVATE void sqlite3Pragma(Parse*,Token*,Token*,Token*,int);
+SQLITE_PRIVATE void sqlite3ResetInternalSchema(sqlite3*, int);
+SQLITE_PRIVATE void sqlite3BeginParse(Parse*,int);
+SQLITE_PRIVATE void sqlite3CommitInternalChanges(sqlite3*);
+SQLITE_PRIVATE Table *sqlite3ResultSetOfSelect(Parse*,Select*);
+SQLITE_PRIVATE void sqlite3OpenMasterTable(Parse *, int);
+SQLITE_PRIVATE void sqlite3StartTable(Parse*,Token*,Token*,int,int,int,int);
+SQLITE_PRIVATE void sqlite3AddColumn(Parse*,Token*);
+SQLITE_PRIVATE void sqlite3AddNotNull(Parse*, int);
+SQLITE_PRIVATE void sqlite3AddPrimaryKey(Parse*, ExprList*, int, int, int);
+SQLITE_PRIVATE void sqlite3AddCheckConstraint(Parse*, Expr*);
+SQLITE_PRIVATE void sqlite3AddColumnType(Parse*,Token*);
+SQLITE_PRIVATE void sqlite3AddDefaultValue(Parse*,ExprSpan*);
+SQLITE_PRIVATE void sqlite3AddCollateType(Parse*, Token*);
+SQLITE_PRIVATE void sqlite3EndTable(Parse*,Token*,Token*,Select*);
+
+SQLITE_PRIVATE Bitvec *sqlite3BitvecCreate(u32);
+SQLITE_PRIVATE int sqlite3BitvecTest(Bitvec*, u32);
+SQLITE_PRIVATE int sqlite3BitvecSet(Bitvec*, u32);
+SQLITE_PRIVATE void sqlite3BitvecClear(Bitvec*, u32, void*);
+SQLITE_PRIVATE void sqlite3BitvecDestroy(Bitvec*);
+SQLITE_PRIVATE u32 sqlite3BitvecSize(Bitvec*);
+SQLITE_PRIVATE int sqlite3BitvecBuiltinTest(int,int*);
+
+SQLITE_PRIVATE RowSet *sqlite3RowSetInit(sqlite3*, void*, unsigned int);
+SQLITE_PRIVATE void sqlite3RowSetClear(RowSet*);
+SQLITE_PRIVATE void sqlite3RowSetInsert(RowSet*, i64);
+SQLITE_PRIVATE int sqlite3RowSetTest(RowSet*, u8 iBatch, i64);
+SQLITE_PRIVATE int sqlite3RowSetNext(RowSet*, i64*);
+
+SQLITE_PRIVATE void sqlite3CreateView(Parse*,Token*,Token*,Token*,Select*,int,int);
+
+#if !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_VIRTUALTABLE)
+SQLITE_PRIVATE   int sqlite3ViewGetColumnNames(Parse*,Table*);
+#else
+# define sqlite3ViewGetColumnNames(A,B) 0
+#endif
+
+SQLITE_PRIVATE void sqlite3DropTable(Parse*, SrcList*, int, int);
+SQLITE_PRIVATE void sqlite3DeleteTable(sqlite3*, Table*);
+#ifndef SQLITE_OMIT_AUTOINCREMENT
+SQLITE_PRIVATE   void sqlite3AutoincrementBegin(Parse *pParse);
+SQLITE_PRIVATE   void sqlite3AutoincrementEnd(Parse *pParse);
+#else
+# define sqlite3AutoincrementBegin(X)
+# define sqlite3AutoincrementEnd(X)
+#endif
+SQLITE_PRIVATE void sqlite3Insert(Parse*, SrcList*, ExprList*, Select*, IdList*, int);
+SQLITE_PRIVATE void *sqlite3ArrayAllocate(sqlite3*,void*,int,int,int*,int*,int*);
+SQLITE_PRIVATE IdList *sqlite3IdListAppend(sqlite3*, IdList*, Token*);
+SQLITE_PRIVATE int sqlite3IdListIndex(IdList*,const char*);
+SQLITE_PRIVATE SrcList *sqlite3SrcListEnlarge(sqlite3*, SrcList*, int, int);
+SQLITE_PRIVATE SrcList *sqlite3SrcListAppend(sqlite3*, SrcList*, Token*, Token*);
+SQLITE_PRIVATE SrcList *sqlite3SrcListAppendFromTerm(Parse*, SrcList*, Token*, Token*,
+                                      Token*, Select*, Expr*, IdList*);
+SQLITE_PRIVATE void sqlite3SrcListIndexedBy(Parse *, SrcList *, Token *);
+SQLITE_PRIVATE int sqlite3IndexedByLookup(Parse *, struct SrcList_item *);
+SQLITE_PRIVATE void sqlite3SrcListShiftJoinType(SrcList*);
+SQLITE_PRIVATE void sqlite3SrcListAssignCursors(Parse*, SrcList*);
+SQLITE_PRIVATE void sqlite3IdListDelete(sqlite3*, IdList*);
+SQLITE_PRIVATE void sqlite3SrcListDelete(sqlite3*, SrcList*);
+SQLITE_PRIVATE Index *sqlite3CreateIndex(Parse*,Token*,Token*,SrcList*,ExprList*,int,Token*,
+                        Token*, int, int);
+SQLITE_PRIVATE void sqlite3DropIndex(Parse*, SrcList*, int);
+SQLITE_PRIVATE int sqlite3Select(Parse*, Select*, SelectDest*);
+SQLITE_PRIVATE Select *sqlite3SelectNew(Parse*,ExprList*,SrcList*,Expr*,ExprList*,
+                         Expr*,ExprList*,int,Expr*,Expr*);
+SQLITE_PRIVATE void sqlite3SelectDelete(sqlite3*, Select*);
+SQLITE_PRIVATE Table *sqlite3SrcListLookup(Parse*, SrcList*);
+SQLITE_PRIVATE int sqlite3IsReadOnly(Parse*, Table*, int);
+SQLITE_PRIVATE void sqlite3OpenTable(Parse*, int iCur, int iDb, Table*, int);
+#if defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) && !defined(SQLITE_OMIT_SUBQUERY)
+SQLITE_PRIVATE Expr *sqlite3LimitWhere(Parse *, SrcList *, Expr *, ExprList *, Expr *, Expr *, char *);
+#endif
+SQLITE_PRIVATE void sqlite3DeleteFrom(Parse*, SrcList*, Expr*);
+SQLITE_PRIVATE void sqlite3Update(Parse*, SrcList*, ExprList*, Expr*, int);
+SQLITE_PRIVATE WhereInfo *sqlite3WhereBegin(Parse*, SrcList*, Expr*, ExprList**, u16);
+SQLITE_PRIVATE void sqlite3WhereEnd(WhereInfo*);
+SQLITE_PRIVATE int sqlite3ExprCodeGetColumn(Parse*, Table*, int, int, int);
+SQLITE_PRIVATE void sqlite3ExprCodeGetColumnOfTable(Vdbe*, Table*, int, int, int);
+SQLITE_PRIVATE void sqlite3ExprCodeMove(Parse*, int, int, int);
+SQLITE_PRIVATE void sqlite3ExprCodeCopy(Parse*, int, int, int);
+SQLITE_PRIVATE void sqlite3ExprCacheStore(Parse*, int, int, int);
+SQLITE_PRIVATE void sqlite3ExprCachePush(Parse*);
+SQLITE_PRIVATE void sqlite3ExprCachePop(Parse*, int);
+SQLITE_PRIVATE void sqlite3ExprCacheRemove(Parse*, int, int);
+SQLITE_PRIVATE void sqlite3ExprCacheClear(Parse*);
+SQLITE_PRIVATE void sqlite3ExprCacheAffinityChange(Parse*, int, int);
+SQLITE_PRIVATE int sqlite3ExprCode(Parse*, Expr*, int);
+SQLITE_PRIVATE int sqlite3ExprCodeTemp(Parse*, Expr*, int*);
+SQLITE_PRIVATE int sqlite3ExprCodeTarget(Parse*, Expr*, int);
+SQLITE_PRIVATE int sqlite3ExprCodeAndCache(Parse*, Expr*, int);
+SQLITE_PRIVATE void sqlite3ExprCodeConstants(Parse*, Expr*);
+SQLITE_PRIVATE int sqlite3ExprCodeExprList(Parse*, ExprList*, int, int);
+SQLITE_PRIVATE void sqlite3ExprIfTrue(Parse*, Expr*, int, int);
+SQLITE_PRIVATE void sqlite3ExprIfFalse(Parse*, Expr*, int, int);
+SQLITE_PRIVATE Table *sqlite3FindTable(sqlite3*,const char*, const char*);
+SQLITE_PRIVATE Table *sqlite3LocateTable(Parse*,int isView,const char*, const char*);
+SQLITE_PRIVATE Index *sqlite3FindIndex(sqlite3*,const char*, const char*);
+SQLITE_PRIVATE void sqlite3UnlinkAndDeleteTable(sqlite3*,int,const char*);
+SQLITE_PRIVATE void sqlite3UnlinkAndDeleteIndex(sqlite3*,int,const char*);
+SQLITE_PRIVATE void sqlite3Vacuum(Parse*);
+SQLITE_PRIVATE int sqlite3RunVacuum(char**, sqlite3*);
+SQLITE_PRIVATE char *sqlite3NameFromToken(sqlite3*, Token*);
+SQLITE_PRIVATE int sqlite3ExprCompare(Expr*, Expr*);
+SQLITE_PRIVATE int sqlite3ExprListCompare(ExprList*, ExprList*);
+SQLITE_PRIVATE void sqlite3ExprAnalyzeAggregates(NameContext*, Expr*);
+SQLITE_PRIVATE void sqlite3ExprAnalyzeAggList(NameContext*,ExprList*);
+SQLITE_PRIVATE Vdbe *sqlite3GetVdbe(Parse*);
+SQLITE_PRIVATE void sqlite3PrngSaveState(void);
+SQLITE_PRIVATE void sqlite3PrngRestoreState(void);
+SQLITE_PRIVATE void sqlite3PrngResetState(void);
+SQLITE_PRIVATE void sqlite3RollbackAll(sqlite3*);
+SQLITE_PRIVATE void sqlite3CodeVerifySchema(Parse*, int);
+SQLITE_PRIVATE void sqlite3CodeVerifyNamedSchema(Parse*, const char *zDb);
+SQLITE_PRIVATE void sqlite3BeginTransaction(Parse*, int);
+SQLITE_PRIVATE void sqlite3CommitTransaction(Parse*);
+SQLITE_PRIVATE void sqlite3RollbackTransaction(Parse*);
+SQLITE_PRIVATE void sqlite3Savepoint(Parse*, int, Token*);
+SQLITE_PRIVATE void sqlite3CloseSavepoints(sqlite3 *);
+SQLITE_PRIVATE int sqlite3ExprIsConstant(Expr*);
+SQLITE_PRIVATE int sqlite3ExprIsConstantNotJoin(Expr*);
+SQLITE_PRIVATE int sqlite3ExprIsConstantOrFunction(Expr*);
+SQLITE_PRIVATE int sqlite3ExprIsInteger(Expr*, int*);
+SQLITE_PRIVATE int sqlite3ExprCanBeNull(const Expr*);
+SQLITE_PRIVATE void sqlite3ExprCodeIsNullJump(Vdbe*, const Expr*, int, int);
+SQLITE_PRIVATE int sqlite3ExprNeedsNoAffinityChange(const Expr*, char);
+SQLITE_PRIVATE int sqlite3IsRowid(const char*);
+SQLITE_PRIVATE void sqlite3GenerateRowDelete(Parse*, Table*, int, int, int, Trigger *, int);
+SQLITE_PRIVATE void sqlite3GenerateRowIndexDelete(Parse*, Table*, int, int*);
+SQLITE_PRIVATE int sqlite3GenerateIndexKey(Parse*, Index*, int, int, int);
+SQLITE_PRIVATE void sqlite3GenerateConstraintChecks(Parse*,Table*,int,int,
+                                     int*,int,int,int,int,int*);
+SQLITE_PRIVATE void sqlite3CompleteInsertion(Parse*, Table*, int, int, int*, int, int, int);
+SQLITE_PRIVATE int sqlite3OpenTableAndIndices(Parse*, Table*, int, int);
+SQLITE_PRIVATE void sqlite3BeginWriteOperation(Parse*, int, int);
+SQLITE_PRIVATE void sqlite3MultiWrite(Parse*);
+SQLITE_PRIVATE void sqlite3MayAbort(Parse*);
+SQLITE_PRIVATE void sqlite3HaltConstraint(Parse*, int, char*, int);
+SQLITE_PRIVATE Expr *sqlite3ExprDup(sqlite3*,Expr*,int);
+SQLITE_PRIVATE ExprList *sqlite3ExprListDup(sqlite3*,ExprList*,int);
+SQLITE_PRIVATE SrcList *sqlite3SrcListDup(sqlite3*,SrcList*,int);
+SQLITE_PRIVATE IdList *sqlite3IdListDup(sqlite3*,IdList*);
+SQLITE_PRIVATE Select *sqlite3SelectDup(sqlite3*,Select*,int);
+SQLITE_PRIVATE void sqlite3FuncDefInsert(FuncDefHash*, FuncDef*);
+SQLITE_PRIVATE FuncDef *sqlite3FindFunction(sqlite3*,const char*,int,int,u8,int);
+SQLITE_PRIVATE void sqlite3RegisterBuiltinFunctions(sqlite3*);
+SQLITE_PRIVATE void sqlite3RegisterDateTimeFunctions(void);
+SQLITE_PRIVATE void sqlite3RegisterGlobalFunctions(void);
+SQLITE_PRIVATE int sqlite3SafetyCheckOk(sqlite3*);
+SQLITE_PRIVATE int sqlite3SafetyCheckSickOrOk(sqlite3*);
+SQLITE_PRIVATE void sqlite3ChangeCookie(Parse*, int);
+
+#if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER)
+SQLITE_PRIVATE void sqlite3MaterializeView(Parse*, Table*, Expr*, int);
+#endif
+
+#ifndef SQLITE_OMIT_TRIGGER
+SQLITE_PRIVATE   void sqlite3BeginTrigger(Parse*, Token*,Token*,int,int,IdList*,SrcList*,
+                           Expr*,int, int);
+SQLITE_PRIVATE   void sqlite3FinishTrigger(Parse*, TriggerStep*, Token*);
+SQLITE_PRIVATE   void sqlite3DropTrigger(Parse*, SrcList*, int);
+SQLITE_PRIVATE   void sqlite3DropTriggerPtr(Parse*, Trigger*);
+SQLITE_PRIVATE   Trigger *sqlite3TriggersExist(Parse *, Table*, int, ExprList*, int *pMask);
+SQLITE_PRIVATE   Trigger *sqlite3TriggerList(Parse *, Table *);
+SQLITE_PRIVATE   void sqlite3CodeRowTrigger(Parse*, Trigger *, int, ExprList*, int, Table *,
+                            int, int, int);
+SQLITE_PRIVATE   void sqlite3CodeRowTriggerDirect(Parse *, Trigger *, Table *, int, int, int);
+  void sqliteViewTriggers(Parse*, Table*, Expr*, int, ExprList*);
+SQLITE_PRIVATE   void sqlite3DeleteTriggerStep(sqlite3*, TriggerStep*);
+SQLITE_PRIVATE   TriggerStep *sqlite3TriggerSelectStep(sqlite3*,Select*);
+SQLITE_PRIVATE   TriggerStep *sqlite3TriggerInsertStep(sqlite3*,Token*, IdList*,
+                                        ExprList*,Select*,u8);
+SQLITE_PRIVATE   TriggerStep *sqlite3TriggerUpdateStep(sqlite3*,Token*,ExprList*, Expr*, u8);
+SQLITE_PRIVATE   TriggerStep *sqlite3TriggerDeleteStep(sqlite3*,Token*, Expr*);
+SQLITE_PRIVATE   void sqlite3DeleteTrigger(sqlite3*, Trigger*);
+SQLITE_PRIVATE   void sqlite3UnlinkAndDeleteTrigger(sqlite3*,int,const char*);
+SQLITE_PRIVATE   u32 sqlite3TriggerColmask(Parse*,Trigger*,ExprList*,int,int,Table*,int);
+# define sqlite3ParseToplevel(p) ((p)->pToplevel ? (p)->pToplevel : (p))
+#else
+# define sqlite3TriggersExist(B,C,D,E,F) 0
+# define sqlite3DeleteTrigger(A,B)
+# define sqlite3DropTriggerPtr(A,B)
+# define sqlite3UnlinkAndDeleteTrigger(A,B,C)
+# define sqlite3CodeRowTrigger(A,B,C,D,E,F,G,H,I)
+# define sqlite3CodeRowTriggerDirect(A,B,C,D,E,F)
+# define sqlite3TriggerList(X, Y) 0
+# define sqlite3ParseToplevel(p) p
+# define sqlite3TriggerColmask(A,B,C,D,E,F,G) 0
+#endif
+
+SQLITE_PRIVATE int sqlite3JoinType(Parse*, Token*, Token*, Token*);
+SQLITE_PRIVATE void sqlite3CreateForeignKey(Parse*, ExprList*, Token*, ExprList*, int);
+SQLITE_PRIVATE void sqlite3DeferForeignKey(Parse*, int);
+#ifndef SQLITE_OMIT_AUTHORIZATION
+SQLITE_PRIVATE   void sqlite3AuthRead(Parse*,Expr*,Schema*,SrcList*);
+SQLITE_PRIVATE   int sqlite3AuthCheck(Parse*,int, const char*, const char*, const char*);
+SQLITE_PRIVATE   void sqlite3AuthContextPush(Parse*, AuthContext*, const char*);
+SQLITE_PRIVATE   void sqlite3AuthContextPop(AuthContext*);
+SQLITE_PRIVATE   int sqlite3AuthReadCol(Parse*, const char *, const char *, int);
+#else
+# define sqlite3AuthRead(a,b,c,d)
+# define sqlite3AuthCheck(a,b,c,d,e)    SQLITE_OK
+# define sqlite3AuthContextPush(a,b,c)
+# define sqlite3AuthContextPop(a)  ((void)(a))
+#endif
+SQLITE_PRIVATE void sqlite3Attach(Parse*, Expr*, Expr*, Expr*);
+SQLITE_PRIVATE void sqlite3Detach(Parse*, Expr*);
+SQLITE_PRIVATE int sqlite3FixInit(DbFixer*, Parse*, int, const char*, const Token*);
+SQLITE_PRIVATE int sqlite3FixSrcList(DbFixer*, SrcList*);
+SQLITE_PRIVATE int sqlite3FixSelect(DbFixer*, Select*);
+SQLITE_PRIVATE int sqlite3FixExpr(DbFixer*, Expr*);
+SQLITE_PRIVATE int sqlite3FixExprList(DbFixer*, ExprList*);
+SQLITE_PRIVATE int sqlite3FixTriggerStep(DbFixer*, TriggerStep*);
+SQLITE_PRIVATE int sqlite3AtoF(const char *z, double*, int, u8);
+SQLITE_PRIVATE int sqlite3GetInt32(const char *, int*);
+SQLITE_PRIVATE int sqlite3Atoi(const char*);
+SQLITE_PRIVATE int sqlite3Utf16ByteLen(const void *pData, int nChar);
+SQLITE_PRIVATE int sqlite3Utf8CharLen(const char *pData, int nByte);
+SQLITE_PRIVATE int sqlite3Utf8Read(const u8*, const u8**);
+
+/*
+** Routines to read and write variable-length integers.  These used to
+** be defined locally, but now we use the varint routines in the util.c
+** file.  Code should use the MACRO forms below, as the Varint32 versions
+** are coded to assume the single byte case is already handled (which 
+** the MACRO form does).
+*/
+SQLITE_PRIVATE int sqlite3PutVarint(unsigned char*, u64);
+SQLITE_PRIVATE int sqlite3PutVarint32(unsigned char*, u32);
+SQLITE_PRIVATE u8 sqlite3GetVarint(const unsigned char *, u64 *);
+SQLITE_PRIVATE u8 sqlite3GetVarint32(const unsigned char *, u32 *);
+SQLITE_PRIVATE int sqlite3VarintLen(u64 v);
+
+/*
+** The header of a record consists of a sequence variable-length integers.
+** These integers are almost always small and are encoded as a single byte.
+** The following macros take advantage this fact to provide a fast encode
+** and decode of the integers in a record header.  It is faster for the common
+** case where the integer is a single byte.  It is a little slower when the
+** integer is two or more bytes.  But overall it is faster.
+**
+** The following expressions are equivalent:
+**
+**     x = sqlite3GetVarint32( A, &B );
+**     x = sqlite3PutVarint32( A, B );
+**
+**     x = getVarint32( A, B );
+**     x = putVarint32( A, B );
+**
+*/
+#define getVarint32(A,B)  (u8)((*(A)<(u8)0x80) ? ((B) = (u32)*(A)),1 : sqlite3GetVarint32((A), (u32 *)&(B)))
+#define putVarint32(A,B)  (u8)(((u32)(B)<(u32)0x80) ? (*(A) = (unsigned char)(B)),1 : sqlite3PutVarint32((A), (B)))
+#define getVarint    sqlite3GetVarint
+#define putVarint    sqlite3PutVarint
+
+
+SQLITE_PRIVATE const char *sqlite3IndexAffinityStr(Vdbe *, Index *);
+SQLITE_PRIVATE void sqlite3TableAffinityStr(Vdbe *, Table *);
+SQLITE_PRIVATE char sqlite3CompareAffinity(Expr *pExpr, char aff2);
+SQLITE_PRIVATE int sqlite3IndexAffinityOk(Expr *pExpr, char idx_affinity);
+SQLITE_PRIVATE char sqlite3ExprAffinity(Expr *pExpr);
+SQLITE_PRIVATE int sqlite3Atoi64(const char*, i64*, int, u8);
+SQLITE_PRIVATE void sqlite3Error(sqlite3*, int, const char*,...);
+SQLITE_PRIVATE void *sqlite3HexToBlob(sqlite3*, const char *z, int n);
+SQLITE_PRIVATE int sqlite3TwoPartName(Parse *, Token *, Token *, Token **);
+SQLITE_PRIVATE const char *sqlite3ErrStr(int);
+SQLITE_PRIVATE int sqlite3ReadSchema(Parse *pParse);
+SQLITE_PRIVATE CollSeq *sqlite3FindCollSeq(sqlite3*,u8 enc, const char*,int);
+SQLITE_PRIVATE CollSeq *sqlite3LocateCollSeq(Parse *pParse, const char*zName);
+SQLITE_PRIVATE CollSeq *sqlite3ExprCollSeq(Parse *pParse, Expr *pExpr);
+SQLITE_PRIVATE Expr *sqlite3ExprSetColl(Expr*, CollSeq*);
+SQLITE_PRIVATE Expr *sqlite3ExprSetCollByToken(Parse *pParse, Expr*, Token*);
+SQLITE_PRIVATE int sqlite3CheckCollSeq(Parse *, CollSeq *);
+SQLITE_PRIVATE int sqlite3CheckObjectName(Parse *, const char *);
+SQLITE_PRIVATE void sqlite3VdbeSetChanges(sqlite3 *, int);
+SQLITE_PRIVATE int sqlite3AddInt64(i64*,i64);
+SQLITE_PRIVATE int sqlite3SubInt64(i64*,i64);
+SQLITE_PRIVATE int sqlite3MulInt64(i64*,i64);
+SQLITE_PRIVATE int sqlite3AbsInt32(int);
+
+SQLITE_PRIVATE const void *sqlite3ValueText(sqlite3_value*, u8);
+SQLITE_PRIVATE int sqlite3ValueBytes(sqlite3_value*, u8);
+SQLITE_PRIVATE void sqlite3ValueSetStr(sqlite3_value*, int, const void *,u8, 
+                        void(*)(void*));
+SQLITE_PRIVATE void sqlite3ValueFree(sqlite3_value*);
+SQLITE_PRIVATE sqlite3_value *sqlite3ValueNew(sqlite3 *);
+SQLITE_PRIVATE char *sqlite3Utf16to8(sqlite3 *, const void*, int, u8);
+#ifdef SQLITE_ENABLE_STAT2
+SQLITE_PRIVATE char *sqlite3Utf8to16(sqlite3 *, u8, char *, int, int *);
+#endif
+SQLITE_PRIVATE int sqlite3ValueFromExpr(sqlite3 *, Expr *, u8, u8, sqlite3_value **);
+SQLITE_PRIVATE void sqlite3ValueApplyAffinity(sqlite3_value *, u8, u8);
+#ifndef SQLITE_AMALGAMATION
+SQLITE_PRIVATE const unsigned char sqlite3OpcodeProperty[];
+SQLITE_PRIVATE const unsigned char sqlite3UpperToLower[];
+SQLITE_PRIVATE const unsigned char sqlite3CtypeMap[];
+SQLITE_PRIVATE const Token sqlite3IntTokens[];
+SQLITE_PRIVATE SQLITE_WSD struct Sqlite3Config sqlite3Config;
+SQLITE_PRIVATE SQLITE_WSD FuncDefHash sqlite3GlobalFunctions;
+#ifndef SQLITE_OMIT_WSD
+SQLITE_PRIVATE int sqlite3PendingByte;
+#endif
+#endif
+SQLITE_PRIVATE void sqlite3RootPageMoved(sqlite3*, int, int, int);
+SQLITE_PRIVATE void sqlite3Reindex(Parse*, Token*, Token*);
+SQLITE_PRIVATE void sqlite3AlterFunctions(void);
+SQLITE_PRIVATE void sqlite3AlterRenameTable(Parse*, SrcList*, Token*);
+SQLITE_PRIVATE int sqlite3GetToken(const unsigned char *, int *);
+SQLITE_PRIVATE void sqlite3NestedParse(Parse*, const char*, ...);
+SQLITE_PRIVATE void sqlite3ExpirePreparedStatements(sqlite3*);
+SQLITE_PRIVATE int sqlite3CodeSubselect(Parse *, Expr *, int, int);
+SQLITE_PRIVATE void sqlite3SelectPrep(Parse*, Select*, NameContext*);
+SQLITE_PRIVATE int sqlite3ResolveExprNames(NameContext*, Expr*);
+SQLITE_PRIVATE void sqlite3ResolveSelectNames(Parse*, Select*, NameContext*);
+SQLITE_PRIVATE int sqlite3ResolveOrderGroupBy(Parse*, Select*, ExprList*, const char*);
+SQLITE_PRIVATE void sqlite3ColumnDefault(Vdbe *, Table *, int, int);
+SQLITE_PRIVATE void sqlite3AlterFinishAddColumn(Parse *, Token *);
+SQLITE_PRIVATE void sqlite3AlterBeginAddColumn(Parse *, SrcList *);
+SQLITE_PRIVATE CollSeq *sqlite3GetCollSeq(sqlite3*, u8, CollSeq *, const char*);
+SQLITE_PRIVATE char sqlite3AffinityType(const char*);
+SQLITE_PRIVATE void sqlite3Analyze(Parse*, Token*, Token*);
+SQLITE_PRIVATE int sqlite3InvokeBusyHandler(BusyHandler*);
+SQLITE_PRIVATE int sqlite3FindDb(sqlite3*, Token*);
+SQLITE_PRIVATE int sqlite3FindDbName(sqlite3 *, const char *);
+SQLITE_PRIVATE int sqlite3AnalysisLoad(sqlite3*,int iDB);
+SQLITE_PRIVATE void sqlite3DeleteIndexSamples(sqlite3*,Index*);
+SQLITE_PRIVATE void sqlite3DefaultRowEst(Index*);
+SQLITE_PRIVATE void sqlite3RegisterLikeFunctions(sqlite3*, int);
+SQLITE_PRIVATE int sqlite3IsLikeFunction(sqlite3*,Expr*,int*,char*);
+SQLITE_PRIVATE void sqlite3MinimumFileFormat(Parse*, int, int);
+SQLITE_PRIVATE void sqlite3SchemaClear(void *);
+SQLITE_PRIVATE Schema *sqlite3SchemaGet(sqlite3 *, Btree *);
+SQLITE_PRIVATE int sqlite3SchemaToIndex(sqlite3 *db, Schema *);
+SQLITE_PRIVATE KeyInfo *sqlite3IndexKeyinfo(Parse *, Index *);
+SQLITE_PRIVATE int sqlite3CreateFunc(sqlite3 *, const char *, int, int, void *, 
+  void (*)(sqlite3_context*,int,sqlite3_value **),
+  void (*)(sqlite3_context*,int,sqlite3_value **), void (*)(sqlite3_context*),
+  FuncDestructor *pDestructor
+);
+SQLITE_PRIVATE int sqlite3ApiExit(sqlite3 *db, int);
+SQLITE_PRIVATE int sqlite3OpenTempDatabase(Parse *);
+
+SQLITE_PRIVATE void sqlite3StrAccumInit(StrAccum*, char*, int, int);
+SQLITE_PRIVATE void sqlite3StrAccumAppend(StrAccum*,const char*,int);
+SQLITE_PRIVATE char *sqlite3StrAccumFinish(StrAccum*);
+SQLITE_PRIVATE void sqlite3StrAccumReset(StrAccum*);
+SQLITE_PRIVATE void sqlite3SelectDestInit(SelectDest*,int,int);
+SQLITE_PRIVATE Expr *sqlite3CreateColumnExpr(sqlite3 *, SrcList *, int, int);
+
+SQLITE_PRIVATE void sqlite3BackupRestart(sqlite3_backup *);
+SQLITE_PRIVATE void sqlite3BackupUpdate(sqlite3_backup *, Pgno, const u8 *);
+
+/*
+** The interface to the LEMON-generated parser
+*/
+SQLITE_PRIVATE void *sqlite3ParserAlloc(void*(*)(size_t));
+SQLITE_PRIVATE void sqlite3ParserFree(void*, void(*)(void*));
+SQLITE_PRIVATE void sqlite3Parser(void*, int, Token, Parse*);
+#ifdef YYTRACKMAXSTACKDEPTH
+SQLITE_PRIVATE   int sqlite3ParserStackPeak(void*);
+#endif
+
+SQLITE_PRIVATE void sqlite3AutoLoadExtensions(sqlite3*);
+#ifndef SQLITE_OMIT_LOAD_EXTENSION
+SQLITE_PRIVATE   void sqlite3CloseExtensions(sqlite3*);
+#else
+# define sqlite3CloseExtensions(X)
+#endif
+
+#ifndef SQLITE_OMIT_SHARED_CACHE
+SQLITE_PRIVATE   void sqlite3TableLock(Parse *, int, int, u8, const char *);
+#else
+  #define sqlite3TableLock(v,w,x,y,z)
+#endif
+
+#ifdef SQLITE_TEST
+SQLITE_PRIVATE   int sqlite3Utf8To8(unsigned char*);
+#endif
+
+#ifdef SQLITE_OMIT_VIRTUALTABLE
+#  define sqlite3VtabClear(Y)
+#  define sqlite3VtabSync(X,Y) SQLITE_OK
+#  define sqlite3VtabRollback(X)
+#  define sqlite3VtabCommit(X)
+#  define sqlite3VtabInSync(db) 0
+#  define sqlite3VtabLock(X) 
+#  define sqlite3VtabUnlock(X)
+#  define sqlite3VtabUnlockList(X)
+#else
+SQLITE_PRIVATE    void sqlite3VtabClear(sqlite3 *db, Table*);
+SQLITE_PRIVATE    int sqlite3VtabSync(sqlite3 *db, char **);
+SQLITE_PRIVATE    int sqlite3VtabRollback(sqlite3 *db);
+SQLITE_PRIVATE    int sqlite3VtabCommit(sqlite3 *db);
+SQLITE_PRIVATE    void sqlite3VtabLock(VTable *);
+SQLITE_PRIVATE    void sqlite3VtabUnlock(VTable *);
+SQLITE_PRIVATE    void sqlite3VtabUnlockList(sqlite3*);
+#  define sqlite3VtabInSync(db) ((db)->nVTrans>0 && (db)->aVTrans==0)
+#endif
+SQLITE_PRIVATE void sqlite3VtabMakeWritable(Parse*,Table*);
+SQLITE_PRIVATE void sqlite3VtabBeginParse(Parse*, Token*, Token*, Token*);
+SQLITE_PRIVATE void sqlite3VtabFinishParse(Parse*, Token*);
+SQLITE_PRIVATE void sqlite3VtabArgInit(Parse*);
+SQLITE_PRIVATE void sqlite3VtabArgExtend(Parse*, Token*);
+SQLITE_PRIVATE int sqlite3VtabCallCreate(sqlite3*, int, const char *, char **);
+SQLITE_PRIVATE int sqlite3VtabCallConnect(Parse*, Table*);
+SQLITE_PRIVATE int sqlite3VtabCallDestroy(sqlite3*, int, const char *);
+SQLITE_PRIVATE int sqlite3VtabBegin(sqlite3 *, VTable *);
+SQLITE_PRIVATE FuncDef *sqlite3VtabOverloadFunction(sqlite3 *,FuncDef*, int nArg, Expr*);
+SQLITE_PRIVATE void sqlite3InvalidFunction(sqlite3_context*,int,sqlite3_value**);
+SQLITE_PRIVATE int sqlite3VdbeParameterIndex(Vdbe*, const char*, int);
+SQLITE_PRIVATE int sqlite3TransferBindings(sqlite3_stmt *, sqlite3_stmt *);
+SQLITE_PRIVATE int sqlite3Reprepare(Vdbe*);
+SQLITE_PRIVATE void sqlite3ExprListCheckLength(Parse*, ExprList*, const char*);
+SQLITE_PRIVATE CollSeq *sqlite3BinaryCompareCollSeq(Parse *, Expr *, Expr *);
+SQLITE_PRIVATE int sqlite3TempInMemory(const sqlite3*);
+SQLITE_PRIVATE VTable *sqlite3GetVTable(sqlite3*, Table*);
+SQLITE_PRIVATE const char *sqlite3JournalModename(int);
+SQLITE_PRIVATE int sqlite3Checkpoint(sqlite3*, int, int, int*, int*);
+SQLITE_PRIVATE int sqlite3WalDefaultHook(void*,sqlite3*,const char*,int);
+
+/* Declarations for functions in fkey.c. All of these are replaced by
+** no-op macros if OMIT_FOREIGN_KEY is defined. In this case no foreign
+** key functionality is available. If OMIT_TRIGGER is defined but
+** OMIT_FOREIGN_KEY is not, only some of the functions are no-oped. In
+** this case foreign keys are parsed, but no other functionality is 
+** provided (enforcement of FK constraints requires the triggers sub-system).
+*/
+#if !defined(SQLITE_OMIT_FOREIGN_KEY) && !defined(SQLITE_OMIT_TRIGGER)
+SQLITE_PRIVATE   void sqlite3FkCheck(Parse*, Table*, int, int);
+SQLITE_PRIVATE   void sqlite3FkDropTable(Parse*, SrcList *, Table*);
+SQLITE_PRIVATE   void sqlite3FkActions(Parse*, Table*, ExprList*, int);
+SQLITE_PRIVATE   int sqlite3FkRequired(Parse*, Table*, int*, int);
+SQLITE_PRIVATE   u32 sqlite3FkOldmask(Parse*, Table*);
+SQLITE_PRIVATE   FKey *sqlite3FkReferences(Table *);
+#else
+  #define sqlite3FkActions(a,b,c,d)
+  #define sqlite3FkCheck(a,b,c,d)
+  #define sqlite3FkDropTable(a,b,c)
+  #define sqlite3FkOldmask(a,b)      0
+  #define sqlite3FkRequired(a,b,c,d) 0
+#endif
+#ifndef SQLITE_OMIT_FOREIGN_KEY
+SQLITE_PRIVATE   void sqlite3FkDelete(sqlite3 *, Table*);
+#else
+  #define sqlite3FkDelete(a,b)
+#endif
+
+
+/*
+** Available fault injectors.  Should be numbered beginning with 0.
+*/
+#define SQLITE_FAULTINJECTOR_MALLOC     0
+#define SQLITE_FAULTINJECTOR_COUNT      1
+
+/*
+** The interface to the code in fault.c used for identifying "benign"
+** malloc failures. This is only present if SQLITE_OMIT_BUILTIN_TEST
+** is not defined.
+*/
+#ifndef SQLITE_OMIT_BUILTIN_TEST
+SQLITE_PRIVATE   void sqlite3BeginBenignMalloc(void);
+SQLITE_PRIVATE   void sqlite3EndBenignMalloc(void);
+#else
+  #define sqlite3BeginBenignMalloc()
+  #define sqlite3EndBenignMalloc()
+#endif
+
+#define IN_INDEX_ROWID           1
+#define IN_INDEX_EPH             2
+#define IN_INDEX_INDEX           3
+SQLITE_PRIVATE int sqlite3FindInIndex(Parse *, Expr *, int*);
+
+#ifdef SQLITE_ENABLE_ATOMIC_WRITE
+SQLITE_PRIVATE   int sqlite3JournalOpen(sqlite3_vfs *, const char *, sqlite3_file *, int, int);
+SQLITE_PRIVATE   int sqlite3JournalSize(sqlite3_vfs *);
+SQLITE_PRIVATE   int sqlite3JournalCreate(sqlite3_file *);
+#else
+  #define sqlite3JournalSize(pVfs) ((pVfs)->szOsFile)
+#endif
+
+SQLITE_PRIVATE void sqlite3MemJournalOpen(sqlite3_file *);
+SQLITE_PRIVATE int sqlite3MemJournalSize(void);
+SQLITE_PRIVATE int sqlite3IsMemJournal(sqlite3_file *);
+
+#if SQLITE_MAX_EXPR_DEPTH>0
+SQLITE_PRIVATE   void sqlite3ExprSetHeight(Parse *pParse, Expr *p);
+SQLITE_PRIVATE   int sqlite3SelectExprHeight(Select *);
+SQLITE_PRIVATE   int sqlite3ExprCheckHeight(Parse*, int);
+#else
+  #define sqlite3ExprSetHeight(x,y)
+  #define sqlite3SelectExprHeight(x) 0
+  #define sqlite3ExprCheckHeight(x,y)
+#endif
+
+SQLITE_PRIVATE u32 sqlite3Get4byte(const u8*);
+SQLITE_PRIVATE void sqlite3Put4byte(u8*, u32);
+
+#ifdef SQLITE_ENABLE_UNLOCK_NOTIFY
+SQLITE_PRIVATE   void sqlite3ConnectionBlocked(sqlite3 *, sqlite3 *);
+SQLITE_PRIVATE   void sqlite3ConnectionUnlocked(sqlite3 *db);
+SQLITE_PRIVATE   void sqlite3ConnectionClosed(sqlite3 *db);
+#else
+  #define sqlite3ConnectionBlocked(x,y)
+  #define sqlite3ConnectionUnlocked(x)
+  #define sqlite3ConnectionClosed(x)
+#endif
+
+#ifdef SQLITE_DEBUG
+SQLITE_PRIVATE   void sqlite3ParserTrace(FILE*, char *);
+#endif
+
+/*
+** If the SQLITE_ENABLE IOTRACE exists then the global variable
+** sqlite3IoTrace is a pointer to a printf-like routine used to
+** print I/O tracing messages. 
+*/
+#ifdef SQLITE_ENABLE_IOTRACE
+# define IOTRACE(A)  if( sqlite3IoTrace ){ sqlite3IoTrace A; }
+SQLITE_PRIVATE   void sqlite3VdbeIOTraceSql(Vdbe*);
+SQLITE_PRIVATE void (*sqlite3IoTrace)(const char*,...);
+#else
+# define IOTRACE(A)
+# define sqlite3VdbeIOTraceSql(X)
+#endif
+
+/*
+** These routines are available for the mem2.c debugging memory allocator
+** only.  They are used to verify that different "types" of memory
+** allocations are properly tracked by the system.
+**
+** sqlite3MemdebugSetType() sets the "type" of an allocation to one of
+** the MEMTYPE_* macros defined below.  The type must be a bitmask with
+** a single bit set.
+**
+** sqlite3MemdebugHasType() returns true if any of the bits in its second
+** argument match the type set by the previous sqlite3MemdebugSetType().
+** sqlite3MemdebugHasType() is intended for use inside assert() statements.
+**
+** sqlite3MemdebugNoType() returns true if none of the bits in its second
+** argument match the type set by the previous sqlite3MemdebugSetType().
+**
+** Perhaps the most important point is the difference between MEMTYPE_HEAP
+** and MEMTYPE_LOOKASIDE.  If an allocation is MEMTYPE_LOOKASIDE, that means
+** it might have been allocated by lookaside, except the allocation was
+** too large or lookaside was already full.  It is important to verify
+** that allocations that might have been satisfied by lookaside are not
+** passed back to non-lookaside free() routines.  Asserts such as the
+** example above are placed on the non-lookaside free() routines to verify
+** this constraint. 
+**
+** All of this is no-op for a production build.  It only comes into
+** play when the SQLITE_MEMDEBUG compile-time option is used.
+*/
+#ifdef SQLITE_MEMDEBUG
+SQLITE_PRIVATE   void sqlite3MemdebugSetType(void*,u8);
+SQLITE_PRIVATE   int sqlite3MemdebugHasType(void*,u8);
+SQLITE_PRIVATE   int sqlite3MemdebugNoType(void*,u8);
+#else
+# define sqlite3MemdebugSetType(X,Y)  /* no-op */
+# define sqlite3MemdebugHasType(X,Y)  1
+# define sqlite3MemdebugNoType(X,Y)   1
+#endif
+#define MEMTYPE_HEAP       0x01  /* General heap allocations */
+#define MEMTYPE_LOOKASIDE  0x02  /* Might have been lookaside memory */
+#define MEMTYPE_SCRATCH    0x04  /* Scratch allocations */
+#define MEMTYPE_PCACHE     0x08  /* Page cache allocations */
+#define MEMTYPE_DB         0x10  /* Uses sqlite3DbMalloc, not sqlite_malloc */
+
+#endif /* _SQLITEINT_H_ */
+
+/************** End of sqliteInt.h *******************************************/
+/************** Begin file global.c ******************************************/
+/*
+** 2008 June 13
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains definitions of global variables and contants.
+*/
+
+/* An array to map all upper-case characters into their corresponding
+** lower-case character. 
+**
+** SQLite only considers US-ASCII (or EBCDIC) characters.  We do not
+** handle case conversions for the UTF character set since the tables
+** involved are nearly as big or bigger than SQLite itself.
+*/
+SQLITE_PRIVATE const unsigned char sqlite3UpperToLower[] = {
+#ifdef SQLITE_ASCII
+      0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17,
+     18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35,
+     36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53,
+     54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 97, 98, 99,100,101,102,103,
+    104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,
+    122, 91, 92, 93, 94, 95, 96, 97, 98, 99,100,101,102,103,104,105,106,107,
+    108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,
+    126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,
+    144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,
+    162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,
+    180,181,182,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197,
+    198,199,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,215,
+    216,217,218,219,220,221,222,223,224,225,226,227,228,229,230,231,232,233,
+    234,235,236,237,238,239,240,241,242,243,244,245,246,247,248,249,250,251,
+    252,253,254,255
+#endif
+#ifdef SQLITE_EBCDIC
+      0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, /* 0x */
+     16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, /* 1x */
+     32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, /* 2x */
+     48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, /* 3x */
+     64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, /* 4x */
+     80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, /* 5x */
+     96, 97, 66, 67, 68, 69, 70, 71, 72, 73,106,107,108,109,110,111, /* 6x */
+    112, 81, 82, 83, 84, 85, 86, 87, 88, 89,122,123,124,125,126,127, /* 7x */
+    128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143, /* 8x */
+    144,145,146,147,148,149,150,151,152,153,154,155,156,157,156,159, /* 9x */
+    160,161,162,163,164,165,166,167,168,169,170,171,140,141,142,175, /* Ax */
+    176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191, /* Bx */
+    192,129,130,131,132,133,134,135,136,137,202,203,204,205,206,207, /* Cx */
+    208,145,146,147,148,149,150,151,152,153,218,219,220,221,222,223, /* Dx */
+    224,225,162,163,164,165,166,167,168,169,232,203,204,205,206,207, /* Ex */
+    239,240,241,242,243,244,245,246,247,248,249,219,220,221,222,255, /* Fx */
+#endif
+};
+
+/*
+** The following 256 byte lookup table is used to support SQLites built-in
+** equivalents to the following standard library functions:
+**
+**   isspace()                        0x01
+**   isalpha()                        0x02
+**   isdigit()                        0x04
+**   isalnum()                        0x06
+**   isxdigit()                       0x08
+**   toupper()                        0x20
+**   SQLite identifier character      0x40
+**
+** Bit 0x20 is set if the mapped character requires translation to upper
+** case. i.e. if the character is a lower-case ASCII character.
+** If x is a lower-case ASCII character, then its upper-case equivalent
+** is (x - 0x20). Therefore toupper() can be implemented as:
+**
+**   (x & ~(map[x]&0x20))
+**
+** Standard function tolower() is implemented using the sqlite3UpperToLower[]
+** array. tolower() is used more often than toupper() by SQLite.
+**
+** Bit 0x40 is set if the character non-alphanumeric and can be used in an 
+** SQLite identifier.  Identifiers are alphanumerics, "_", "$", and any
+** non-ASCII UTF character. Hence the test for whether or not a character is
+** part of an identifier is 0x46.
+**
+** SQLite's versions are identical to the standard versions assuming a
+** locale of "C". They are implemented as macros in sqliteInt.h.
+*/
+#ifdef SQLITE_ASCII
+SQLITE_PRIVATE const unsigned char sqlite3CtypeMap[256] = {
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 00..07    ........ */
+  0x00, 0x01, 0x01, 0x01, 0x01, 0x01, 0x00, 0x00,  /* 08..0f    ........ */
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 10..17    ........ */
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 18..1f    ........ */
+  0x01, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x00,  /* 20..27     !"#$%&' */
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 28..2f    ()*+,-./ */
+  0x0c, 0x0c, 0x0c, 0x0c, 0x0c, 0x0c, 0x0c, 0x0c,  /* 30..37    01234567 */
+  0x0c, 0x0c, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 38..3f    89:;<=>? */
+
+  0x00, 0x0a, 0x0a, 0x0a, 0x0a, 0x0a, 0x0a, 0x02,  /* 40..47    @ABCDEFG */
+  0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,  /* 48..4f    HIJKLMNO */
+  0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,  /* 50..57    PQRSTUVW */
+  0x02, 0x02, 0x02, 0x00, 0x00, 0x00, 0x00, 0x40,  /* 58..5f    XYZ[\]^_ */
+  0x00, 0x2a, 0x2a, 0x2a, 0x2a, 0x2a, 0x2a, 0x22,  /* 60..67    `abcdefg */
+  0x22, 0x22, 0x22, 0x22, 0x22, 0x22, 0x22, 0x22,  /* 68..6f    hijklmno */
+  0x22, 0x22, 0x22, 0x22, 0x22, 0x22, 0x22, 0x22,  /* 70..77    pqrstuvw */
+  0x22, 0x22, 0x22, 0x00, 0x00, 0x00, 0x00, 0x00,  /* 78..7f    xyz{|}~. */
+
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* 80..87    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* 88..8f    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* 90..97    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* 98..9f    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* a0..a7    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* a8..af    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* b0..b7    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* b8..bf    ........ */
+
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* c0..c7    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* c8..cf    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* d0..d7    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* d8..df    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* e0..e7    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* e8..ef    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  /* f0..f7    ........ */
+  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40   /* f8..ff    ........ */
+};
+#endif
+
+
+
+/*
+** The following singleton contains the global configuration for
+** the SQLite library.
+*/
+SQLITE_PRIVATE SQLITE_WSD struct Sqlite3Config sqlite3Config = {
+   SQLITE_DEFAULT_MEMSTATUS,  /* bMemstat */
+   1,                         /* bCoreMutex */
+   SQLITE_THREADSAFE==1,      /* bFullMutex */
+   0x7ffffffe,                /* mxStrlen */
+   100,                       /* szLookaside */
+   500,                       /* nLookaside */
+   {0,0,0,0,0,0,0,0},         /* m */
+   {0,0,0,0,0,0,0,0,0},       /* mutex */
+   {0,0,0,0,0,0,0,0,0,0,0},   /* pcache */
+   (void*)0,                  /* pHeap */
+   0,                         /* nHeap */
+   0, 0,                      /* mnHeap, mxHeap */
+   (void*)0,                  /* pScratch */
+   0,                         /* szScratch */
+   0,                         /* nScratch */
+   (void*)0,                  /* pPage */
+   0,                         /* szPage */
+   0,                         /* nPage */
+   0,                         /* mxParserStack */
+   0,                         /* sharedCacheEnabled */
+   /* All the rest should always be initialized to zero */
+   0,                         /* isInit */
+   0,                         /* inProgress */
+   0,                         /* isMutexInit */
+   0,                         /* isMallocInit */
+   0,                         /* isPCacheInit */
+   0,                         /* pInitMutex */
+   0,                         /* nRefInitMutex */
+   0,                         /* xLog */
+   0,                         /* pLogArg */
+};
+
+
+/*
+** Hash table for global functions - functions common to all
+** database connections.  After initialization, this table is
+** read-only.
+*/
+SQLITE_PRIVATE SQLITE_WSD FuncDefHash sqlite3GlobalFunctions;
+
+/*
+** Constant tokens for values 0 and 1.
+*/
+SQLITE_PRIVATE const Token sqlite3IntTokens[] = {
+   { "0", 1 },
+   { "1", 1 }
+};
+
+
+/*
+** The value of the "pending" byte must be 0x40000000 (1 byte past the
+** 1-gibabyte boundary) in a compatible database.  SQLite never uses
+** the database page that contains the pending byte.  It never attempts
+** to read or write that page.  The pending byte page is set assign
+** for use by the VFS layers as space for managing file locks.
+**
+** During testing, it is often desirable to move the pending byte to
+** a different position in the file.  This allows code that has to
+** deal with the pending byte to run on files that are much smaller
+** than 1 GiB.  The sqlite3_test_control() interface can be used to
+** move the pending byte.
+**
+** IMPORTANT:  Changing the pending byte to any value other than
+** 0x40000000 results in an incompatible database file format!
+** Changing the pending byte during operating results in undefined
+** and dileterious behavior.
+*/
+#ifndef SQLITE_OMIT_WSD
+SQLITE_PRIVATE int sqlite3PendingByte = 0x40000000;
+#endif
+
+/*
+** Properties of opcodes.  The OPFLG_INITIALIZER macro is
+** created by mkopcodeh.awk during compilation.  Data is obtained
+** from the comments following the "case OP_xxxx:" statements in
+** the vdbe.c file.  
+*/
+SQLITE_PRIVATE const unsigned char sqlite3OpcodeProperty[] = OPFLG_INITIALIZER;
+
+/************** End of global.c **********************************************/
+/************** Begin file ctime.c *******************************************/
+/*
+** 2010 February 23
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file implements routines used to report what compile-time options
+** SQLite was built with.
+*/
+
+#ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
+
+
+/*
+** An array of names of all compile-time options.  This array should 
+** be sorted A-Z.
+**
+** This array looks large, but in a typical installation actually uses
+** only a handful of compile-time options, so most times this array is usually
+** rather short and uses little memory space.
+*/
+static const char * const azCompileOpt[] = {
+
+/* These macros are provided to "stringify" the value of the define
+** for those options in which the value is meaningful. */
+#define CTIMEOPT_VAL_(opt) #opt
+#define CTIMEOPT_VAL(opt) CTIMEOPT_VAL_(opt)
+
+#ifdef SQLITE_32BIT_ROWID
+  "32BIT_ROWID",
+#endif
+#ifdef SQLITE_4_BYTE_ALIGNED_MALLOC
+  "4_BYTE_ALIGNED_MALLOC",
+#endif
+#ifdef SQLITE_CASE_SENSITIVE_LIKE
+  "CASE_SENSITIVE_LIKE",
+#endif
+#ifdef SQLITE_CHECK_PAGES
+  "CHECK_PAGES",
+#endif
+#ifdef SQLITE_COVERAGE_TEST
+  "COVERAGE_TEST",
+#endif
+#ifdef SQLITE_DEBUG
+  "DEBUG",
+#endif
+#ifdef SQLITE_DEFAULT_LOCKING_MODE
+  "DEFAULT_LOCKING_MODE=" CTIMEOPT_VAL(SQLITE_DEFAULT_LOCKING_MODE),
+#endif
+#ifdef SQLITE_DISABLE_DIRSYNC
+  "DISABLE_DIRSYNC",
+#endif
+#ifdef SQLITE_DISABLE_LFS
+  "DISABLE_LFS",
+#endif
+#ifdef SQLITE_ENABLE_ATOMIC_WRITE
+  "ENABLE_ATOMIC_WRITE",
+#endif
+#ifdef SQLITE_ENABLE_CEROD
+  "ENABLE_CEROD",
+#endif
+#ifdef SQLITE_ENABLE_COLUMN_METADATA
+  "ENABLE_COLUMN_METADATA",
+#endif
+#ifdef SQLITE_ENABLE_EXPENSIVE_ASSERT
+  "ENABLE_EXPENSIVE_ASSERT",
+#endif
+#ifdef SQLITE_ENABLE_FTS1
+  "ENABLE_FTS1",
+#endif
+#ifdef SQLITE_ENABLE_FTS2
+  "ENABLE_FTS2",
+#endif
+#ifdef SQLITE_ENABLE_FTS3
+  "ENABLE_FTS3",
+#endif
+#ifdef SQLITE_ENABLE_FTS3_PARENTHESIS
+  "ENABLE_FTS3_PARENTHESIS",
+#endif
+#ifdef SQLITE_ENABLE_FTS4
+  "ENABLE_FTS4",
+#endif
+#ifdef SQLITE_ENABLE_ICU
+  "ENABLE_ICU",
+#endif
+#ifdef SQLITE_ENABLE_IOTRACE
+  "ENABLE_IOTRACE",
+#endif
+#ifdef SQLITE_ENABLE_LOAD_EXTENSION
+  "ENABLE_LOAD_EXTENSION",
+#endif
+#ifdef SQLITE_ENABLE_LOCKING_STYLE
+  "ENABLE_LOCKING_STYLE=" CTIMEOPT_VAL(SQLITE_ENABLE_LOCKING_STYLE),
+#endif
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+  "ENABLE_MEMORY_MANAGEMENT",
+#endif
+#ifdef SQLITE_ENABLE_MEMSYS3
+  "ENABLE_MEMSYS3",
+#endif
+#ifdef SQLITE_ENABLE_MEMSYS5
+  "ENABLE_MEMSYS5",
+#endif
+#ifdef SQLITE_ENABLE_OVERSIZE_CELL_CHECK
+  "ENABLE_OVERSIZE_CELL_CHECK",
+#endif
+#ifdef SQLITE_ENABLE_RTREE
+  "ENABLE_RTREE",
+#endif
+#ifdef SQLITE_ENABLE_STAT2
+  "ENABLE_STAT2",
+#endif
+#ifdef SQLITE_ENABLE_UNLOCK_NOTIFY
+  "ENABLE_UNLOCK_NOTIFY",
+#endif
+#ifdef SQLITE_ENABLE_UPDATE_DELETE_LIMIT
+  "ENABLE_UPDATE_DELETE_LIMIT",
+#endif
+#ifdef SQLITE_HAS_CODEC
+  "HAS_CODEC",
+#endif
+#ifdef SQLITE_HAVE_ISNAN
+  "HAVE_ISNAN",
+#endif
+#ifdef SQLITE_HOMEGROWN_RECURSIVE_MUTEX
+  "HOMEGROWN_RECURSIVE_MUTEX",
+#endif
+#ifdef SQLITE_IGNORE_AFP_LOCK_ERRORS
+  "IGNORE_AFP_LOCK_ERRORS",
+#endif
+#ifdef SQLITE_IGNORE_FLOCK_LOCK_ERRORS
+  "IGNORE_FLOCK_LOCK_ERRORS",
+#endif
+#ifdef SQLITE_INT64_TYPE
+  "INT64_TYPE",
+#endif
+#ifdef SQLITE_LOCK_TRACE
+  "LOCK_TRACE",
+#endif
+#ifdef SQLITE_MEMDEBUG
+  "MEMDEBUG",
+#endif
+#ifdef SQLITE_MIXED_ENDIAN_64BIT_FLOAT
+  "MIXED_ENDIAN_64BIT_FLOAT",
+#endif
+#ifdef SQLITE_NO_SYNC
+  "NO_SYNC",
+#endif
+#ifdef SQLITE_OMIT_ALTERTABLE
+  "OMIT_ALTERTABLE",
+#endif
+#ifdef SQLITE_OMIT_ANALYZE
+  "OMIT_ANALYZE",
+#endif
+#ifdef SQLITE_OMIT_ATTACH
+  "OMIT_ATTACH",
+#endif
+#ifdef SQLITE_OMIT_AUTHORIZATION
+  "OMIT_AUTHORIZATION",
+#endif
+#ifdef SQLITE_OMIT_AUTOINCREMENT
+  "OMIT_AUTOINCREMENT",
+#endif
+#ifdef SQLITE_OMIT_AUTOINIT
+  "OMIT_AUTOINIT",
+#endif
+#ifdef SQLITE_OMIT_AUTOMATIC_INDEX
+  "OMIT_AUTOMATIC_INDEX",
+#endif
+#ifdef SQLITE_OMIT_AUTORESET
+  "OMIT_AUTORESET",
+#endif
+#ifdef SQLITE_OMIT_AUTOVACUUM
+  "OMIT_AUTOVACUUM",
+#endif
+#ifdef SQLITE_OMIT_BETWEEN_OPTIMIZATION
+  "OMIT_BETWEEN_OPTIMIZATION",
+#endif
+#ifdef SQLITE_OMIT_BLOB_LITERAL
+  "OMIT_BLOB_LITERAL",
+#endif
+#ifdef SQLITE_OMIT_BTREECOUNT
+  "OMIT_BTREECOUNT",
+#endif
+#ifdef SQLITE_OMIT_BUILTIN_TEST
+  "OMIT_BUILTIN_TEST",
+#endif
+#ifdef SQLITE_OMIT_CAST
+  "OMIT_CAST",
+#endif
+#ifdef SQLITE_OMIT_CHECK
+  "OMIT_CHECK",
+#endif
+/* // redundant
+** #ifdef SQLITE_OMIT_COMPILEOPTION_DIAGS
+**   "OMIT_COMPILEOPTION_DIAGS",
+** #endif
+*/
+#ifdef SQLITE_OMIT_COMPLETE
+  "OMIT_COMPLETE",
+#endif
+#ifdef SQLITE_OMIT_COMPOUND_SELECT
+  "OMIT_COMPOUND_SELECT",
+#endif
+#ifdef SQLITE_OMIT_DATETIME_FUNCS
+  "OMIT_DATETIME_FUNCS",
+#endif
+#ifdef SQLITE_OMIT_DECLTYPE
+  "OMIT_DECLTYPE",
+#endif
+#ifdef SQLITE_OMIT_DEPRECATED
+  "OMIT_DEPRECATED",
+#endif
+#ifdef SQLITE_OMIT_DISKIO
+  "OMIT_DISKIO",
+#endif
+#ifdef SQLITE_OMIT_EXPLAIN
+  "OMIT_EXPLAIN",
+#endif
+#ifdef SQLITE_OMIT_FLAG_PRAGMAS
+  "OMIT_FLAG_PRAGMAS",
+#endif
+#ifdef SQLITE_OMIT_FLOATING_POINT
+  "OMIT_FLOATING_POINT",
+#endif
+#ifdef SQLITE_OMIT_FOREIGN_KEY
+  "OMIT_FOREIGN_KEY",
+#endif
+#ifdef SQLITE_OMIT_GET_TABLE
+  "OMIT_GET_TABLE",
+#endif
+#ifdef SQLITE_OMIT_INCRBLOB
+  "OMIT_INCRBLOB",
+#endif
+#ifdef SQLITE_OMIT_INTEGRITY_CHECK
+  "OMIT_INTEGRITY_CHECK",
+#endif
+#ifdef SQLITE_OMIT_LIKE_OPTIMIZATION
+  "OMIT_LIKE_OPTIMIZATION",
+#endif
+#ifdef SQLITE_OMIT_LOAD_EXTENSION
+  "OMIT_LOAD_EXTENSION",
+#endif
+#ifdef SQLITE_OMIT_LOCALTIME
+  "OMIT_LOCALTIME",
+#endif
+#ifdef SQLITE_OMIT_LOOKASIDE
+  "OMIT_LOOKASIDE",
+#endif
+#ifdef SQLITE_OMIT_MEMORYDB
+  "OMIT_MEMORYDB",
+#endif
+#ifdef SQLITE_OMIT_OR_OPTIMIZATION
+  "OMIT_OR_OPTIMIZATION",
+#endif
+#ifdef SQLITE_OMIT_PAGER_PRAGMAS
+  "OMIT_PAGER_PRAGMAS",
+#endif
+#ifdef SQLITE_OMIT_PRAGMA
+  "OMIT_PRAGMA",
+#endif
+#ifdef SQLITE_OMIT_PROGRESS_CALLBACK
+  "OMIT_PROGRESS_CALLBACK",
+#endif
+#ifdef SQLITE_OMIT_QUICKBALANCE
+  "OMIT_QUICKBALANCE",
+#endif
+#ifdef SQLITE_OMIT_REINDEX
+  "OMIT_REINDEX",
+#endif
+#ifdef SQLITE_OMIT_SCHEMA_PRAGMAS
+  "OMIT_SCHEMA_PRAGMAS",
+#endif
+#ifdef SQLITE_OMIT_SCHEMA_VERSION_PRAGMAS
+  "OMIT_SCHEMA_VERSION_PRAGMAS",
+#endif
+#ifdef SQLITE_OMIT_SHARED_CACHE
+  "OMIT_SHARED_CACHE",
+#endif
+#ifdef SQLITE_OMIT_SUBQUERY
+  "OMIT_SUBQUERY",
+#endif
+#ifdef SQLITE_OMIT_TCL_VARIABLE
+  "OMIT_TCL_VARIABLE",
+#endif
+#ifdef SQLITE_OMIT_TEMPDB
+  "OMIT_TEMPDB",
+#endif
+#ifdef SQLITE_OMIT_TRACE
+  "OMIT_TRACE",
+#endif
+#ifdef SQLITE_OMIT_TRIGGER
+  "OMIT_TRIGGER",
+#endif
+#ifdef SQLITE_OMIT_TRUNCATE_OPTIMIZATION
+  "OMIT_TRUNCATE_OPTIMIZATION",
+#endif
+#ifdef SQLITE_OMIT_UTF16
+  "OMIT_UTF16",
+#endif
+#ifdef SQLITE_OMIT_VACUUM
+  "OMIT_VACUUM",
+#endif
+#ifdef SQLITE_OMIT_VIEW
+  "OMIT_VIEW",
+#endif
+#ifdef SQLITE_OMIT_VIRTUALTABLE
+  "OMIT_VIRTUALTABLE",
+#endif
+#ifdef SQLITE_OMIT_WAL
+  "OMIT_WAL",
+#endif
+#ifdef SQLITE_OMIT_WSD
+  "OMIT_WSD",
+#endif
+#ifdef SQLITE_OMIT_XFER_OPT
+  "OMIT_XFER_OPT",
+#endif
+#ifdef SQLITE_PERFORMANCE_TRACE
+  "PERFORMANCE_TRACE",
+#endif
+#ifdef SQLITE_PROXY_DEBUG
+  "PROXY_DEBUG",
+#endif
+#ifdef SQLITE_SECURE_DELETE
+  "SECURE_DELETE",
+#endif
+#ifdef SQLITE_SMALL_STACK
+  "SMALL_STACK",
+#endif
+#ifdef SQLITE_SOUNDEX
+  "SOUNDEX",
+#endif
+#ifdef SQLITE_TCL
+  "TCL",
+#endif
+#ifdef SQLITE_TEMP_STORE
+  "TEMP_STORE=" CTIMEOPT_VAL(SQLITE_TEMP_STORE),
+#endif
+#ifdef SQLITE_TEST
+  "TEST",
+#endif
+#ifdef SQLITE_THREADSAFE
+  "THREADSAFE=" CTIMEOPT_VAL(SQLITE_THREADSAFE),
+#endif
+#ifdef SQLITE_USE_ALLOCA
+  "USE_ALLOCA",
+#endif
+#ifdef SQLITE_ZERO_MALLOC
+  "ZERO_MALLOC"
+#endif
+};
+
+/*
+** Given the name of a compile-time option, return true if that option
+** was used and false if not.
+**
+** The name can optionally begin with "SQLITE_" but the "SQLITE_" prefix
+** is not required for a match.
+*/
+SQLITE_API int sqlite3_compileoption_used(const char *zOptName){
+  int i, n;
+  if( sqlite3StrNICmp(zOptName, "SQLITE_", 7)==0 ) zOptName += 7;
+  n = sqlite3Strlen30(zOptName);
+
+  /* Since ArraySize(azCompileOpt) is normally in single digits, a
+  ** linear search is adequate.  No need for a binary search. */
+  for(i=0; i<ArraySize(azCompileOpt); i++){
+    if(   (sqlite3StrNICmp(zOptName, azCompileOpt[i], n)==0)
+       && ( (azCompileOpt[i][n]==0) || (azCompileOpt[i][n]=='=') ) ) return 1;
+  }
+  return 0;
+}
+
+/*
+** Return the N-th compile-time option string.  If N is out of range,
+** return a NULL pointer.
+*/
+SQLITE_API const char *sqlite3_compileoption_get(int N){
+  if( N>=0 && N<ArraySize(azCompileOpt) ){
+    return azCompileOpt[N];
+  }
+  return 0;
+}
+
+#endif /* SQLITE_OMIT_COMPILEOPTION_DIAGS */
+
+/************** End of ctime.c ***********************************************/
+/************** Begin file status.c ******************************************/
+/*
+** 2008 June 18
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This module implements the sqlite3_status() interface and related
+** functionality.
+*/
+/************** Include vdbeInt.h in the middle of status.c ******************/
+/************** Begin file vdbeInt.h *****************************************/
+/*
+** 2003 September 6
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This is the header file for information that is private to the
+** VDBE.  This information used to all be at the top of the single
+** source code file "vdbe.c".  When that file became too big (over
+** 6000 lines long) it was split up into several smaller files and
+** this header information was factored out.
+*/
+#ifndef _VDBEINT_H_
+#define _VDBEINT_H_
+
+/*
+** SQL is translated into a sequence of instructions to be
+** executed by a virtual machine.  Each instruction is an instance
+** of the following structure.
+*/
+typedef struct VdbeOp Op;
+
+/*
+** Boolean values
+*/
+typedef unsigned char Bool;
+
+/*
+** A cursor is a pointer into a single BTree within a database file.
+** The cursor can seek to a BTree entry with a particular key, or
+** loop over all entries of the Btree.  You can also insert new BTree
+** entries or retrieve the key or data from the entry that the cursor
+** is currently pointing to.
+** 
+** Every cursor that the virtual machine has open is represented by an
+** instance of the following structure.
+*/
+struct VdbeCursor {
+  BtCursor *pCursor;    /* The cursor structure of the backend */
+  Btree *pBt;           /* Separate file holding temporary table */
+  KeyInfo *pKeyInfo;    /* Info about index keys needed by index cursors */
+  int iDb;              /* Index of cursor database in db->aDb[] (or -1) */
+  int pseudoTableReg;   /* Register holding pseudotable content. */
+  int nField;           /* Number of fields in the header */
+  Bool zeroed;          /* True if zeroed out and ready for reuse */
+  Bool rowidIsValid;    /* True if lastRowid is valid */
+  Bool atFirst;         /* True if pointing to first entry */
+  Bool useRandomRowid;  /* Generate new record numbers semi-randomly */
+  Bool nullRow;         /* True if pointing to a row with no data */
+  Bool deferredMoveto;  /* A call to sqlite3BtreeMoveto() is needed */
+  Bool isTable;         /* True if a table requiring integer keys */
+  Bool isIndex;         /* True if an index containing keys only - no data */
+  Bool isOrdered;       /* True if the underlying table is BTREE_UNORDERED */
+  sqlite3_vtab_cursor *pVtabCursor;  /* The cursor for a virtual table */
+  const sqlite3_module *pModule;     /* Module for cursor pVtabCursor */
+  i64 seqCount;         /* Sequence counter */
+  i64 movetoTarget;     /* Argument to the deferred sqlite3BtreeMoveto() */
+  i64 lastRowid;        /* Last rowid from a Next or NextIdx operation */
+
+  /* Result of last sqlite3BtreeMoveto() done by an OP_NotExists or 
+  ** OP_IsUnique opcode on this cursor. */
+  int seekResult;
+
+  /* Cached information about the header for the data record that the
+  ** cursor is currently pointing to.  Only valid if cacheStatus matches
+  ** Vdbe.cacheCtr.  Vdbe.cacheCtr will never take on the value of
+  ** CACHE_STALE and so setting cacheStatus=CACHE_STALE guarantees that
+  ** the cache is out of date.
+  **
+  ** aRow might point to (ephemeral) data for the current row, or it might
+  ** be NULL.
+  */
+  u32 cacheStatus;      /* Cache is valid if this matches Vdbe.cacheCtr */
+  int payloadSize;      /* Total number of bytes in the record */
+  u32 *aType;           /* Type values for all entries in the record */
+  u32 *aOffset;         /* Cached offsets to the start of each columns data */
+  u8 *aRow;             /* Data for the current row, if all on one page */
+};
+typedef struct VdbeCursor VdbeCursor;
+
+/*
+** When a sub-program is executed (OP_Program), a structure of this type
+** is allocated to store the current value of the program counter, as
+** well as the current memory cell array and various other frame specific
+** values stored in the Vdbe struct. When the sub-program is finished, 
+** these values are copied back to the Vdbe from the VdbeFrame structure,
+** restoring the state of the VM to as it was before the sub-program
+** began executing.
+**
+** The memory for a VdbeFrame object is allocated and managed by a memory
+** cell in the parent (calling) frame. When the memory cell is deleted or
+** overwritten, the VdbeFrame object is not freed immediately. Instead, it
+** is linked into the Vdbe.pDelFrame list. The contents of the Vdbe.pDelFrame
+** list is deleted when the VM is reset in VdbeHalt(). The reason for doing
+** this instead of deleting the VdbeFrame immediately is to avoid recursive
+** calls to sqlite3VdbeMemRelease() when the memory cells belonging to the
+** child frame are released.
+**
+** The currently executing frame is stored in Vdbe.pFrame. Vdbe.pFrame is
+** set to NULL if the currently executing frame is the main program.
+*/
+typedef struct VdbeFrame VdbeFrame;
+struct VdbeFrame {
+  Vdbe *v;                /* VM this frame belongs to */
+  int pc;                 /* Program Counter in parent (calling) frame */
+  Op *aOp;                /* Program instructions for parent frame */
+  int nOp;                /* Size of aOp array */
+  Mem *aMem;              /* Array of memory cells for parent frame */
+  int nMem;               /* Number of entries in aMem */
+  VdbeCursor **apCsr;     /* Array of Vdbe cursors for parent frame */
+  u16 nCursor;            /* Number of entries in apCsr */
+  void *token;            /* Copy of SubProgram.token */
+  int nChildMem;          /* Number of memory cells for child frame */
+  int nChildCsr;          /* Number of cursors for child frame */
+  i64 lastRowid;          /* Last insert rowid (sqlite3.lastRowid) */
+  int nChange;            /* Statement changes (Vdbe.nChanges)     */
+  VdbeFrame *pParent;     /* Parent of this frame, or NULL if parent is main */
+};
+
+#define VdbeFrameMem(p) ((Mem *)&((u8 *)p)[ROUND8(sizeof(VdbeFrame))])
+
+/*
+** A value for VdbeCursor.cacheValid that means the cache is always invalid.
+*/
+#define CACHE_STALE 0
+
+/*
+** Internally, the vdbe manipulates nearly all SQL values as Mem
+** structures. Each Mem struct may cache multiple representations (string,
+** integer etc.) of the same value.
+*/
+struct Mem {
+  sqlite3 *db;        /* The associated database connection */
+  char *z;            /* String or BLOB value */
+  double r;           /* Real value */
+  union {
+    i64 i;              /* Integer value used when MEM_Int is set in flags */
+    int nZero;          /* Used when bit MEM_Zero is set in flags */
+    FuncDef *pDef;      /* Used only when flags==MEM_Agg */
+    RowSet *pRowSet;    /* Used only when flags==MEM_RowSet */
+    VdbeFrame *pFrame;  /* Used when flags==MEM_Frame */
+  } u;
+  int n;              /* Number of characters in string value, excluding '\0' */
+  u16 flags;          /* Some combination of MEM_Null, MEM_Str, MEM_Dyn, etc. */
+  u8  type;           /* One of SQLITE_NULL, SQLITE_TEXT, SQLITE_INTEGER, etc */
+  u8  enc;            /* SQLITE_UTF8, SQLITE_UTF16BE, SQLITE_UTF16LE */
+#ifdef SQLITE_DEBUG
+  Mem *pScopyFrom;    /* This Mem is a shallow copy of pScopyFrom */
+  void *pFiller;      /* So that sizeof(Mem) is a multiple of 8 */
+#endif
+  void (*xDel)(void *);  /* If not null, call this function to delete Mem.z */
+  char *zMalloc;      /* Dynamic buffer allocated by sqlite3_malloc() */
+};
+
+/* One or more of the following flags are set to indicate the validOK
+** representations of the value stored in the Mem struct.
+**
+** If the MEM_Null flag is set, then the value is an SQL NULL value.
+** No other flags may be set in this case.
+**
+** If the MEM_Str flag is set then Mem.z points at a string representation.
+** Usually this is encoded in the same unicode encoding as the main
+** database (see below for exceptions). If the MEM_Term flag is also
+** set, then the string is nul terminated. The MEM_Int and MEM_Real 
+** flags may coexist with the MEM_Str flag.
+*/
+#define MEM_Null      0x0001   /* Value is NULL */
+#define MEM_Str       0x0002   /* Value is a string */
+#define MEM_Int       0x0004   /* Value is an integer */
+#define MEM_Real      0x0008   /* Value is a real number */
+#define MEM_Blob      0x0010   /* Value is a BLOB */
+#define MEM_RowSet    0x0020   /* Value is a RowSet object */
+#define MEM_Frame     0x0040   /* Value is a VdbeFrame object */
+#define MEM_Invalid   0x0080   /* Value is undefined */
+#define MEM_TypeMask  0x00ff   /* Mask of type bits */
+
+/* Whenever Mem contains a valid string or blob representation, one of
+** the following flags must be set to determine the memory management
+** policy for Mem.z.  The MEM_Term flag tells us whether or not the
+** string is \000 or \u0000 terminated
+*/
+#define MEM_Term      0x0200   /* String rep is nul terminated */
+#define MEM_Dyn       0x0400   /* Need to call sqliteFree() on Mem.z */
+#define MEM_Static    0x0800   /* Mem.z points to a static string */
+#define MEM_Ephem     0x1000   /* Mem.z points to an ephemeral string */
+#define MEM_Agg       0x2000   /* Mem.z points to an agg function context */
+#define MEM_Zero      0x4000   /* Mem.i contains count of 0s appended to blob */
+#ifdef SQLITE_OMIT_INCRBLOB
+  #undef MEM_Zero
+  #define MEM_Zero 0x0000
+#endif
+
+/*
+** Clear any existing type flags from a Mem and replace them with f
+*/
+#define MemSetTypeFlag(p, f) \
+   ((p)->flags = ((p)->flags&~(MEM_TypeMask|MEM_Zero))|f)
+
+/*
+** Return true if a memory cell is not marked as invalid.  This macro
+** is for use inside assert() statements only.
+*/
+#ifdef SQLITE_DEBUG
+#define memIsValid(M)  ((M)->flags & MEM_Invalid)==0
+#endif
+
+
+/* A VdbeFunc is just a FuncDef (defined in sqliteInt.h) that contains
+** additional information about auxiliary information bound to arguments
+** of the function.  This is used to implement the sqlite3_get_auxdata()
+** and sqlite3_set_auxdata() APIs.  The "auxdata" is some auxiliary data
+** that can be associated with a constant argument to a function.  This
+** allows functions such as "regexp" to compile their constant regular
+** expression argument once and reused the compiled code for multiple
+** invocations.
+*/
+struct VdbeFunc {
+  FuncDef *pFunc;               /* The definition of the function */
+  int nAux;                     /* Number of entries allocated for apAux[] */
+  struct AuxData {
+    void *pAux;                   /* Aux data for the i-th argument */
+    void (*xDelete)(void *);      /* Destructor for the aux data */
+  } apAux[1];                   /* One slot for each function argument */
+};
+
+/*
+** The "context" argument for a installable function.  A pointer to an
+** instance of this structure is the first argument to the routines used
+** implement the SQL functions.
+**
+** There is a typedef for this structure in sqlite.h.  So all routines,
+** even the public interface to SQLite, can use a pointer to this structure.
+** But this file is the only place where the internal details of this
+** structure are known.
+**
+** This structure is defined inside of vdbeInt.h because it uses substructures
+** (Mem) which are only defined there.
+*/
+struct sqlite3_context {
+  FuncDef *pFunc;       /* Pointer to function information.  MUST BE FIRST */
+  VdbeFunc *pVdbeFunc;  /* Auxilary data, if created. */
+  Mem s;                /* The return value is stored here */
+  Mem *pMem;            /* Memory cell used to store aggregate context */
+  int isError;          /* Error code returned by the function. */
+  CollSeq *pColl;       /* Collating sequence */
+};
+
+/*
+** An instance of the virtual machine.  This structure contains the complete
+** state of the virtual machine.
+**
+** The "sqlite3_stmt" structure pointer that is returned by sqlite3_prepare()
+** is really a pointer to an instance of this structure.
+**
+** The Vdbe.inVtabMethod variable is set to non-zero for the duration of
+** any virtual table method invocations made by the vdbe program. It is
+** set to 2 for xDestroy method calls and 1 for all other methods. This
+** variable is used for two purposes: to allow xDestroy methods to execute
+** "DROP TABLE" statements and to prevent some nasty side effects of
+** malloc failure when SQLite is invoked recursively by a virtual table 
+** method function.
+*/
+struct Vdbe {
+  sqlite3 *db;            /* The database connection that owns this statement */
+  Op *aOp;                /* Space to hold the virtual machine's program */
+  Mem *aMem;              /* The memory locations */
+  Mem **apArg;            /* Arguments to currently executing user function */
+  Mem *aColName;          /* Column names to return */
+  Mem *pResultSet;        /* Pointer to an array of results */
+  int nMem;               /* Number of memory locations currently allocated */
+  int nOp;                /* Number of instructions in the program */
+  int nOpAlloc;           /* Number of slots allocated for aOp[] */
+  int nLabel;             /* Number of labels used */
+  int nLabelAlloc;        /* Number of slots allocated in aLabel[] */
+  int *aLabel;            /* Space to hold the labels */
+  u16 nResColumn;         /* Number of columns in one row of the result set */
+  u16 nCursor;            /* Number of slots in apCsr[] */
+  u32 magic;              /* Magic number for sanity checking */
+  char *zErrMsg;          /* Error message written here */
+  Vdbe *pPrev,*pNext;     /* Linked list of VDBEs with the same Vdbe.db */
+  VdbeCursor **apCsr;     /* One element of this array for each open cursor */
+  Mem *aVar;              /* Values for the OP_Variable opcode. */
+  char **azVar;           /* Name of variables */
+  ynVar nVar;             /* Number of entries in aVar[] */
+  u32 cacheCtr;           /* VdbeCursor row cache generation counter */
+  int pc;                 /* The program counter */
+  int rc;                 /* Value to return */
+  u8 errorAction;         /* Recovery action to do in case of an error */
+  u8 okVar;               /* True if azVar[] has been initialized */
+  u8 explain;             /* True if EXPLAIN present on SQL command */
+  u8 changeCntOn;         /* True to update the change-counter */
+  u8 expired;             /* True if the VM needs to be recompiled */
+  u8 runOnlyOnce;         /* Automatically expire on reset */
+  u8 minWriteFileFormat;  /* Minimum file format for writable database files */
+  u8 inVtabMethod;        /* See comments above */
+  u8 usesStmtJournal;     /* True if uses a statement journal */
+  u8 readOnly;            /* True for read-only statements */
+  u8 isPrepareV2;         /* True if prepared with prepare_v2() */
+  int nChange;            /* Number of db changes made since last reset */
+  yDbMask btreeMask;      /* Bitmask of db->aDb[] entries referenced */
+  yDbMask lockMask;       /* Subset of btreeMask that requires a lock */
+  int iStatement;         /* Statement number (or 0 if has not opened stmt) */
+  int aCounter[3];        /* Counters used by sqlite3_stmt_status() */
+#ifndef SQLITE_OMIT_TRACE
+  i64 startTime;          /* Time when query started - used for profiling */
+#endif
+  i64 nFkConstraint;      /* Number of imm. FK constraints this VM */
+  i64 nStmtDefCons;       /* Number of def. constraints when stmt started */
+  char *zSql;             /* Text of the SQL statement that generated this */
+  void *pFree;            /* Free this when deleting the vdbe */
+#ifdef SQLITE_DEBUG
+  FILE *trace;            /* Write an execution trace here, if not NULL */
+#endif
+  VdbeFrame *pFrame;      /* Parent frame */
+  VdbeFrame *pDelFrame;   /* List of frame objects to free on VM reset */
+  int nFrame;             /* Number of frames in pFrame list */
+  u32 expmask;            /* Binding to these vars invalidates VM */
+  SubProgram *pProgram;   /* Linked list of all sub-programs used by VM */
+};
+
+/*
+** The following are allowed values for Vdbe.magic
+*/
+#define VDBE_MAGIC_INIT     0x26bceaa5    /* Building a VDBE program */
+#define VDBE_MAGIC_RUN      0xbdf20da3    /* VDBE is ready to execute */
+#define VDBE_MAGIC_HALT     0x519c2973    /* VDBE has completed execution */
+#define VDBE_MAGIC_DEAD     0xb606c3c8    /* The VDBE has been deallocated */
+
+/*
+** Function prototypes
+*/
+SQLITE_PRIVATE void sqlite3VdbeFreeCursor(Vdbe *, VdbeCursor*);
+void sqliteVdbePopStack(Vdbe*,int);
+SQLITE_PRIVATE int sqlite3VdbeCursorMoveto(VdbeCursor*);
+#if defined(SQLITE_DEBUG) || defined(VDBE_PROFILE)
+SQLITE_PRIVATE void sqlite3VdbePrintOp(FILE*, int, Op*);
+#endif
+SQLITE_PRIVATE u32 sqlite3VdbeSerialTypeLen(u32);
+SQLITE_PRIVATE u32 sqlite3VdbeSerialType(Mem*, int);
+SQLITE_PRIVATE u32 sqlite3VdbeSerialPut(unsigned char*, int, Mem*, int);
+SQLITE_PRIVATE u32 sqlite3VdbeSerialGet(const unsigned char*, u32, Mem*);
+SQLITE_PRIVATE void sqlite3VdbeDeleteAuxData(VdbeFunc*, int);
+
+int sqlite2BtreeKeyCompare(BtCursor *, const void *, int, int, int *);
+SQLITE_PRIVATE int sqlite3VdbeIdxKeyCompare(VdbeCursor*,UnpackedRecord*,int*);
+SQLITE_PRIVATE int sqlite3VdbeIdxRowid(sqlite3*, BtCursor *, i64 *);
+SQLITE_PRIVATE int sqlite3MemCompare(const Mem*, const Mem*, const CollSeq*);
+SQLITE_PRIVATE int sqlite3VdbeExec(Vdbe*);
+SQLITE_PRIVATE int sqlite3VdbeList(Vdbe*);
+SQLITE_PRIVATE int sqlite3VdbeHalt(Vdbe*);
+SQLITE_PRIVATE int sqlite3VdbeChangeEncoding(Mem *, int);
+SQLITE_PRIVATE int sqlite3VdbeMemTooBig(Mem*);
+SQLITE_PRIVATE int sqlite3VdbeMemCopy(Mem*, const Mem*);
+SQLITE_PRIVATE void sqlite3VdbeMemShallowCopy(Mem*, const Mem*, int);
+SQLITE_PRIVATE void sqlite3VdbeMemMove(Mem*, Mem*);
+SQLITE_PRIVATE int sqlite3VdbeMemNulTerminate(Mem*);
+SQLITE_PRIVATE int sqlite3VdbeMemSetStr(Mem*, const char*, int, u8, void(*)(void*));
+SQLITE_PRIVATE void sqlite3VdbeMemSetInt64(Mem*, i64);
+#ifdef SQLITE_OMIT_FLOATING_POINT
+# define sqlite3VdbeMemSetDouble sqlite3VdbeMemSetInt64
+#else
+SQLITE_PRIVATE   void sqlite3VdbeMemSetDouble(Mem*, double);
+#endif
+SQLITE_PRIVATE void sqlite3VdbeMemSetNull(Mem*);
+SQLITE_PRIVATE void sqlite3VdbeMemSetZeroBlob(Mem*,int);
+SQLITE_PRIVATE void sqlite3VdbeMemSetRowSet(Mem*);
+SQLITE_PRIVATE int sqlite3VdbeMemMakeWriteable(Mem*);
+SQLITE_PRIVATE int sqlite3VdbeMemStringify(Mem*, int);
+SQLITE_PRIVATE i64 sqlite3VdbeIntValue(Mem*);
+SQLITE_PRIVATE int sqlite3VdbeMemIntegerify(Mem*);
+SQLITE_PRIVATE double sqlite3VdbeRealValue(Mem*);
+SQLITE_PRIVATE void sqlite3VdbeIntegerAffinity(Mem*);
+SQLITE_PRIVATE int sqlite3VdbeMemRealify(Mem*);
+SQLITE_PRIVATE int sqlite3VdbeMemNumerify(Mem*);
+SQLITE_PRIVATE int sqlite3VdbeMemFromBtree(BtCursor*,int,int,int,Mem*);
+SQLITE_PRIVATE void sqlite3VdbeMemRelease(Mem *p);
+SQLITE_PRIVATE void sqlite3VdbeMemReleaseExternal(Mem *p);
+SQLITE_PRIVATE int sqlite3VdbeMemFinalize(Mem*, FuncDef*);
+SQLITE_PRIVATE const char *sqlite3OpcodeName(int);
+SQLITE_PRIVATE int sqlite3VdbeMemGrow(Mem *pMem, int n, int preserve);
+SQLITE_PRIVATE int sqlite3VdbeCloseStatement(Vdbe *, int);
+SQLITE_PRIVATE void sqlite3VdbeFrameDelete(VdbeFrame*);
+SQLITE_PRIVATE int sqlite3VdbeFrameRestore(VdbeFrame *);
+SQLITE_PRIVATE void sqlite3VdbeMemStoreType(Mem *pMem);
+
+#if !defined(SQLITE_OMIT_SHARED_CACHE) && SQLITE_THREADSAFE>0
+SQLITE_PRIVATE   void sqlite3VdbeEnter(Vdbe*);
+SQLITE_PRIVATE   void sqlite3VdbeLeave(Vdbe*);
+#else
+# define sqlite3VdbeEnter(X)
+# define sqlite3VdbeLeave(X)
+#endif
+
+#ifdef SQLITE_DEBUG
+SQLITE_PRIVATE void sqlite3VdbeMemPrepareToChange(Vdbe*,Mem*);
+#endif
+
+#ifndef SQLITE_OMIT_FOREIGN_KEY
+SQLITE_PRIVATE int sqlite3VdbeCheckFk(Vdbe *, int);
+#else
+# define sqlite3VdbeCheckFk(p,i) 0
+#endif
+
+SQLITE_PRIVATE int sqlite3VdbeMemTranslate(Mem*, u8);
+#ifdef SQLITE_DEBUG
+SQLITE_PRIVATE   void sqlite3VdbePrintSql(Vdbe*);
+SQLITE_PRIVATE   void sqlite3VdbeMemPrettyPrint(Mem *pMem, char *zBuf);
+#endif
+SQLITE_PRIVATE int sqlite3VdbeMemHandleBom(Mem *pMem);
+
+#ifndef SQLITE_OMIT_INCRBLOB
+SQLITE_PRIVATE   int sqlite3VdbeMemExpandBlob(Mem *);
+#else
+  #define sqlite3VdbeMemExpandBlob(x) SQLITE_OK
+#endif
+
+#endif /* !defined(_VDBEINT_H_) */
+
+/************** End of vdbeInt.h *********************************************/
+/************** Continuing where we left off in status.c *********************/
+
+/*
+** Variables in which to record status information.
+*/
+typedef struct sqlite3StatType sqlite3StatType;
+static SQLITE_WSD struct sqlite3StatType {
+  int nowValue[10];         /* Current value */
+  int mxValue[10];          /* Maximum value */
+} sqlite3Stat = { {0,}, {0,} };
+
+
+/* The "wsdStat" macro will resolve to the status information
+** state vector.  If writable static data is unsupported on the target,
+** we have to locate the state vector at run-time.  In the more common
+** case where writable static data is supported, wsdStat can refer directly
+** to the "sqlite3Stat" state vector declared above.
+*/
+#ifdef SQLITE_OMIT_WSD
+# define wsdStatInit  sqlite3StatType *x = &GLOBAL(sqlite3StatType,sqlite3Stat)
+# define wsdStat x[0]
+#else
+# define wsdStatInit
+# define wsdStat sqlite3Stat
+#endif
+
+/*
+** Return the current value of a status parameter.
+*/
+SQLITE_PRIVATE int sqlite3StatusValue(int op){
+  wsdStatInit;
+  assert( op>=0 && op<ArraySize(wsdStat.nowValue) );
+  return wsdStat.nowValue[op];
+}
+
+/*
+** Add N to the value of a status record.  It is assumed that the
+** caller holds appropriate locks.
+*/
+SQLITE_PRIVATE void sqlite3StatusAdd(int op, int N){
+  wsdStatInit;
+  assert( op>=0 && op<ArraySize(wsdStat.nowValue) );
+  wsdStat.nowValue[op] += N;
+  if( wsdStat.nowValue[op]>wsdStat.mxValue[op] ){
+    wsdStat.mxValue[op] = wsdStat.nowValue[op];
+  }
+}
+
+/*
+** Set the value of a status to X.
+*/
+SQLITE_PRIVATE void sqlite3StatusSet(int op, int X){
+  wsdStatInit;
+  assert( op>=0 && op<ArraySize(wsdStat.nowValue) );
+  wsdStat.nowValue[op] = X;
+  if( wsdStat.nowValue[op]>wsdStat.mxValue[op] ){
+    wsdStat.mxValue[op] = wsdStat.nowValue[op];
+  }
+}
+
+/*
+** Query status information.
+**
+** This implementation assumes that reading or writing an aligned
+** 32-bit integer is an atomic operation.  If that assumption is not true,
+** then this routine is not threadsafe.
+*/
+SQLITE_API int sqlite3_status(int op, int *pCurrent, int *pHighwater, int resetFlag){
+  wsdStatInit;
+  if( op<0 || op>=ArraySize(wsdStat.nowValue) ){
+    return SQLITE_MISUSE_BKPT;
+  }
+  *pCurrent = wsdStat.nowValue[op];
+  *pHighwater = wsdStat.mxValue[op];
+  if( resetFlag ){
+    wsdStat.mxValue[op] = wsdStat.nowValue[op];
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Query status information for a single database connection
+*/
+SQLITE_API int sqlite3_db_status(
+  sqlite3 *db,          /* The database connection whose status is desired */
+  int op,               /* Status verb */
+  int *pCurrent,        /* Write current value here */
+  int *pHighwater,      /* Write high-water mark here */
+  int resetFlag         /* Reset high-water mark if true */
+){
+  int rc = SQLITE_OK;   /* Return code */
+  sqlite3_mutex_enter(db->mutex);
+  switch( op ){
+    case SQLITE_DBSTATUS_LOOKASIDE_USED: {
+      *pCurrent = db->lookaside.nOut;
+      *pHighwater = db->lookaside.mxOut;
+      if( resetFlag ){
+        db->lookaside.mxOut = db->lookaside.nOut;
+      }
+      break;
+    }
+
+    case SQLITE_DBSTATUS_LOOKASIDE_HIT:
+    case SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE:
+    case SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL: {
+      testcase( op==SQLITE_DBSTATUS_LOOKASIDE_HIT );
+      testcase( op==SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE );
+      testcase( op==SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL );
+      assert( (op-SQLITE_DBSTATUS_LOOKASIDE_HIT)>=0 );
+      assert( (op-SQLITE_DBSTATUS_LOOKASIDE_HIT)<3 );
+      *pCurrent = 0;
+      *pHighwater = db->lookaside.anStat[op - SQLITE_DBSTATUS_LOOKASIDE_HIT];
+      if( resetFlag ){
+        db->lookaside.anStat[op - SQLITE_DBSTATUS_LOOKASIDE_HIT] = 0;
+      }
+      break;
+    }
+
+    /* 
+    ** Return an approximation for the amount of memory currently used
+    ** by all pagers associated with the given database connection.  The
+    ** highwater mark is meaningless and is returned as zero.
+    */
+    case SQLITE_DBSTATUS_CACHE_USED: {
+      int totalUsed = 0;
+      int i;
+      sqlite3BtreeEnterAll(db);
+      for(i=0; i<db->nDb; i++){
+        Btree *pBt = db->aDb[i].pBt;
+        if( pBt ){
+          Pager *pPager = sqlite3BtreePager(pBt);
+          totalUsed += sqlite3PagerMemUsed(pPager);
+        }
+      }
+      sqlite3BtreeLeaveAll(db);
+      *pCurrent = totalUsed;
+      *pHighwater = 0;
+      break;
+    }
+
+    /*
+    ** *pCurrent gets an accurate estimate of the amount of memory used
+    ** to store the schema for all databases (main, temp, and any ATTACHed
+    ** databases.  *pHighwater is set to zero.
+    */
+    case SQLITE_DBSTATUS_SCHEMA_USED: {
+      int i;                      /* Used to iterate through schemas */
+      int nByte = 0;              /* Used to accumulate return value */
+
+      sqlite3BtreeEnterAll(db);
+      db->pnBytesFreed = &nByte;
+      for(i=0; i<db->nDb; i++){
+        Schema *pSchema = db->aDb[i].pSchema;
+        if( ALWAYS(pSchema!=0) ){
+          HashElem *p;
+
+          nByte += sqlite3GlobalConfig.m.xRoundup(sizeof(HashElem)) * (
+              pSchema->tblHash.count 
+            + pSchema->trigHash.count
+            + pSchema->idxHash.count
+            + pSchema->fkeyHash.count
+          );
+          nByte += sqlite3MallocSize(pSchema->tblHash.ht);
+          nByte += sqlite3MallocSize(pSchema->trigHash.ht);
+          nByte += sqlite3MallocSize(pSchema->idxHash.ht);
+          nByte += sqlite3MallocSize(pSchema->fkeyHash.ht);
+
+          for(p=sqliteHashFirst(&pSchema->trigHash); p; p=sqliteHashNext(p)){
+            sqlite3DeleteTrigger(db, (Trigger*)sqliteHashData(p));
+          }
+          for(p=sqliteHashFirst(&pSchema->tblHash); p; p=sqliteHashNext(p)){
+            sqlite3DeleteTable(db, (Table *)sqliteHashData(p));
+          }
+        }
+      }
+      db->pnBytesFreed = 0;
+      sqlite3BtreeLeaveAll(db);
+
+      *pHighwater = 0;
+      *pCurrent = nByte;
+      break;
+    }
+
+    /*
+    ** *pCurrent gets an accurate estimate of the amount of memory used
+    ** to store all prepared statements.
+    ** *pHighwater is set to zero.
+    */
+    case SQLITE_DBSTATUS_STMT_USED: {
+      struct Vdbe *pVdbe;         /* Used to iterate through VMs */
+      int nByte = 0;              /* Used to accumulate return value */
+
+      db->pnBytesFreed = &nByte;
+      for(pVdbe=db->pVdbe; pVdbe; pVdbe=pVdbe->pNext){
+        sqlite3VdbeDeleteObject(db, pVdbe);
+      }
+      db->pnBytesFreed = 0;
+
+      *pHighwater = 0;
+      *pCurrent = nByte;
+
+      break;
+    }
+
+    default: {
+      rc = SQLITE_ERROR;
+    }
+  }
+  sqlite3_mutex_leave(db->mutex);
+  return rc;
+}
+
+/************** End of status.c **********************************************/
+/************** Begin file date.c ********************************************/
+/*
+** 2003 October 31
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains the C functions that implement date and time
+** functions for SQLite.  
+**
+** There is only one exported symbol in this file - the function
+** sqlite3RegisterDateTimeFunctions() found at the bottom of the file.
+** All other code has file scope.
+**
+** SQLite processes all times and dates as Julian Day numbers.  The
+** dates and times are stored as the number of days since noon
+** in Greenwich on November 24, 4714 B.C. according to the Gregorian
+** calendar system. 
+**
+** 1970-01-01 00:00:00 is JD 2440587.5
+** 2000-01-01 00:00:00 is JD 2451544.5
+**
+** This implemention requires years to be expressed as a 4-digit number
+** which means that only dates between 0000-01-01 and 9999-12-31 can
+** be represented, even though julian day numbers allow a much wider
+** range of dates.
+**
+** The Gregorian calendar system is used for all dates and times,
+** even those that predate the Gregorian calendar.  Historians usually
+** use the Julian calendar for dates prior to 1582-10-15 and for some
+** dates afterwards, depending on locale.  Beware of this difference.
+**
+** The conversion algorithms are implemented based on descriptions
+** in the following text:
+**
+**      Jean Meeus
+**      Astronomical Algorithms, 2nd Edition, 1998
+**      ISBM 0-943396-61-1
+**      Willmann-Bell, Inc
+**      Richmond, Virginia (USA)
+*/
+#include <time.h>
+
+#ifndef SQLITE_OMIT_DATETIME_FUNCS
+
+/*
+** On recent Windows platforms, the localtime_s() function is available
+** as part of the "Secure CRT". It is essentially equivalent to 
+** localtime_r() available under most POSIX platforms, except that the 
+** order of the parameters is reversed.
+**
+** See http://msdn.microsoft.com/en-us/library/a442x3ye(VS.80).aspx.
+**
+** If the user has not indicated to use localtime_r() or localtime_s()
+** already, check for an MSVC build environment that provides 
+** localtime_s().
+*/
+#if !defined(HAVE_LOCALTIME_R) && !defined(HAVE_LOCALTIME_S) && \
+     defined(_MSC_VER) && defined(_CRT_INSECURE_DEPRECATE)
+#define HAVE_LOCALTIME_S 1
+#endif
+
+/*
+** A structure for holding a single date and time.
+*/
+typedef struct DateTime DateTime;
+struct DateTime {
+  sqlite3_int64 iJD; /* The julian day number times 86400000 */
+  int Y, M, D;       /* Year, month, and day */
+  int h, m;          /* Hour and minutes */
+  int tz;            /* Timezone offset in minutes */
+  double s;          /* Seconds */
+  char validYMD;     /* True (1) if Y,M,D are valid */
+  char validHMS;     /* True (1) if h,m,s are valid */
+  char validJD;      /* True (1) if iJD is valid */
+  char validTZ;      /* True (1) if tz is valid */
+};
+
+
+/*
+** Convert zDate into one or more integers.  Additional arguments
+** come in groups of 5 as follows:
+**
+**       N       number of digits in the integer
+**       min     minimum allowed value of the integer
+**       max     maximum allowed value of the integer
+**       nextC   first character after the integer
+**       pVal    where to write the integers value.
+**
+** Conversions continue until one with nextC==0 is encountered.
+** The function returns the number of successful conversions.
+*/
+static int getDigits(const char *zDate, ...){
+  va_list ap;
+  int val;
+  int N;
+  int min;
+  int max;
+  int nextC;
+  int *pVal;
+  int cnt = 0;
+  va_start(ap, zDate);
+  do{
+    N = va_arg(ap, int);
+    min = va_arg(ap, int);
+    max = va_arg(ap, int);
+    nextC = va_arg(ap, int);
+    pVal = va_arg(ap, int*);
+    val = 0;
+    while( N-- ){
+      if( !sqlite3Isdigit(*zDate) ){
+        goto end_getDigits;
+      }
+      val = val*10 + *zDate - '0';
+      zDate++;
+    }
+    if( val<min || val>max || (nextC!=0 && nextC!=*zDate) ){
+      goto end_getDigits;
+    }
+    *pVal = val;
+    zDate++;
+    cnt++;
+  }while( nextC );
+end_getDigits:
+  va_end(ap);
+  return cnt;
+}
+
+/*
+** Parse a timezone extension on the end of a date-time.
+** The extension is of the form:
+**
+**        (+/-)HH:MM
+**
+** Or the "zulu" notation:
+**
+**        Z
+**
+** If the parse is successful, write the number of minutes
+** of change in p->tz and return 0.  If a parser error occurs,
+** return non-zero.
+**
+** A missing specifier is not considered an error.
+*/
+static int parseTimezone(const char *zDate, DateTime *p){
+  int sgn = 0;
+  int nHr, nMn;
+  int c;
+  while( sqlite3Isspace(*zDate) ){ zDate++; }
+  p->tz = 0;
+  c = *zDate;
+  if( c=='-' ){
+    sgn = -1;
+  }else if( c=='+' ){
+    sgn = +1;
+  }else if( c=='Z' || c=='z' ){
+    zDate++;
+    goto zulu_time;
+  }else{
+    return c!=0;
+  }
+  zDate++;
+  if( getDigits(zDate, 2, 0, 14, ':', &nHr, 2, 0, 59, 0, &nMn)!=2 ){
+    return 1;
+  }
+  zDate += 5;
+  p->tz = sgn*(nMn + nHr*60);
+zulu_time:
+  while( sqlite3Isspace(*zDate) ){ zDate++; }
+  return *zDate!=0;
+}
+
+/*
+** Parse times of the form HH:MM or HH:MM:SS or HH:MM:SS.FFFF.
+** The HH, MM, and SS must each be exactly 2 digits.  The
+** fractional seconds FFFF can be one or more digits.
+**
+** Return 1 if there is a parsing error and 0 on success.
+*/
+static int parseHhMmSs(const char *zDate, DateTime *p){
+  int h, m, s;
+  double ms = 0.0;
+  if( getDigits(zDate, 2, 0, 24, ':', &h, 2, 0, 59, 0, &m)!=2 ){
+    return 1;
+  }
+  zDate += 5;
+  if( *zDate==':' ){
+    zDate++;
+    if( getDigits(zDate, 2, 0, 59, 0, &s)!=1 ){
+      return 1;
+    }
+    zDate += 2;
+    if( *zDate=='.' && sqlite3Isdigit(zDate[1]) ){
+      double rScale = 1.0;
+      zDate++;
+      while( sqlite3Isdigit(*zDate) ){
+        ms = ms*10.0 + *zDate - '0';
+        rScale *= 10.0;
+        zDate++;
+      }
+      ms /= rScale;
+    }
+  }else{
+    s = 0;
+  }
+  p->validJD = 0;
+  p->validHMS = 1;
+  p->h = h;
+  p->m = m;
+  p->s = s + ms;
+  if( parseTimezone(zDate, p) ) return 1;
+  p->validTZ = (p->tz!=0)?1:0;
+  return 0;
+}
+
+/*
+** Convert from YYYY-MM-DD HH:MM:SS to julian day.  We always assume
+** that the YYYY-MM-DD is according to the Gregorian calendar.
+**
+** Reference:  Meeus page 61
+*/
+static void computeJD(DateTime *p){
+  int Y, M, D, A, B, X1, X2;
+
+  if( p->validJD ) return;
+  if( p->validYMD ){
+    Y = p->Y;
+    M = p->M;
+    D = p->D;
+  }else{
+    Y = 2000;  /* If no YMD specified, assume 2000-Jan-01 */
+    M = 1;
+    D = 1;
+  }
+  if( M<=2 ){
+    Y--;
+    M += 12;
+  }
+  A = Y/100;
+  B = 2 - A + (A/4);
+  X1 = 36525*(Y+4716)/100;
+  X2 = 306001*(M+1)/10000;
+  p->iJD = (sqlite3_int64)((X1 + X2 + D + B - 1524.5 ) * 86400000);
+  p->validJD = 1;
+  if( p->validHMS ){
+    p->iJD += p->h*3600000 + p->m*60000 + (sqlite3_int64)(p->s*1000);
+    if( p->validTZ ){
+      p->iJD -= p->tz*60000;
+      p->validYMD = 0;
+      p->validHMS = 0;
+      p->validTZ = 0;
+    }
+  }
+}
+
+/*
+** Parse dates of the form
+**
+**     YYYY-MM-DD HH:MM:SS.FFF
+**     YYYY-MM-DD HH:MM:SS
+**     YYYY-MM-DD HH:MM
+**     YYYY-MM-DD
+**
+** Write the result into the DateTime structure and return 0
+** on success and 1 if the input string is not a well-formed
+** date.
+*/
+static int parseYyyyMmDd(const char *zDate, DateTime *p){
+  int Y, M, D, neg;
+
+  if( zDate[0]=='-' ){
+    zDate++;
+    neg = 1;
+  }else{
+    neg = 0;
+  }
+  if( getDigits(zDate,4,0,9999,'-',&Y,2,1,12,'-',&M,2,1,31,0,&D)!=3 ){
+    return 1;
+  }
+  zDate += 10;
+  while( sqlite3Isspace(*zDate) || 'T'==*(u8*)zDate ){ zDate++; }
+  if( parseHhMmSs(zDate, p)==0 ){
+    /* We got the time */
+  }else if( *zDate==0 ){
+    p->validHMS = 0;
+  }else{
+    return 1;
+  }
+  p->validJD = 0;
+  p->validYMD = 1;
+  p->Y = neg ? -Y : Y;
+  p->M = M;
+  p->D = D;
+  if( p->validTZ ){
+    computeJD(p);
+  }
+  return 0;
+}
+
+/*
+** Set the time to the current time reported by the VFS
+*/
+static void setDateTimeToCurrent(sqlite3_context *context, DateTime *p){
+  sqlite3 *db = sqlite3_context_db_handle(context);
+  sqlite3OsCurrentTimeInt64(db->pVfs, &p->iJD);
+  p->validJD = 1;
+}
+
+/*
+** Attempt to parse the given string into a Julian Day Number.  Return
+** the number of errors.
+**
+** The following are acceptable forms for the input string:
+**
+**      YYYY-MM-DD HH:MM:SS.FFF  +/-HH:MM
+**      DDDD.DD 
+**      now
+**
+** In the first form, the +/-HH:MM is always optional.  The fractional
+** seconds extension (the ".FFF") is optional.  The seconds portion
+** (":SS.FFF") is option.  The year and date can be omitted as long
+** as there is a time string.  The time string can be omitted as long
+** as there is a year and date.
+*/
+static int parseDateOrTime(
+  sqlite3_context *context, 
+  const char *zDate, 
+  DateTime *p
+){
+  double r;
+  if( parseYyyyMmDd(zDate,p)==0 ){
+    return 0;
+  }else if( parseHhMmSs(zDate, p)==0 ){
+    return 0;
+  }else if( sqlite3StrICmp(zDate,"now")==0){
+    setDateTimeToCurrent(context, p);
+    return 0;
+  }else if( sqlite3AtoF(zDate, &r, sqlite3Strlen30(zDate), SQLITE_UTF8) ){
+    p->iJD = (sqlite3_int64)(r*86400000.0 + 0.5);
+    p->validJD = 1;
+    return 0;
+  }
+  return 1;
+}
+
+/*
+** Compute the Year, Month, and Day from the julian day number.
+*/
+static void computeYMD(DateTime *p){
+  int Z, A, B, C, D, E, X1;
+  if( p->validYMD ) return;
+  if( !p->validJD ){
+    p->Y = 2000;
+    p->M = 1;
+    p->D = 1;
+  }else{
+    Z = (int)((p->iJD + 43200000)/86400000);
+    A = (int)((Z - 1867216.25)/36524.25);
+    A = Z + 1 + A - (A/4);
+    B = A + 1524;
+    C = (int)((B - 122.1)/365.25);
+    D = (36525*C)/100;
+    E = (int)((B-D)/30.6001);
+    X1 = (int)(30.6001*E);
+    p->D = B - D - X1;
+    p->M = E<14 ? E-1 : E-13;
+    p->Y = p->M>2 ? C - 4716 : C - 4715;
+  }
+  p->validYMD = 1;
+}
+
+/*
+** Compute the Hour, Minute, and Seconds from the julian day number.
+*/
+static void computeHMS(DateTime *p){
+  int s;
+  if( p->validHMS ) return;
+  computeJD(p);
+  s = (int)((p->iJD + 43200000) % 86400000);
+  p->s = s/1000.0;
+  s = (int)p->s;
+  p->s -= s;
+  p->h = s/3600;
+  s -= p->h*3600;
+  p->m = s/60;
+  p->s += s - p->m*60;
+  p->validHMS = 1;
+}
+
+/*
+** Compute both YMD and HMS
+*/
+static void computeYMD_HMS(DateTime *p){
+  computeYMD(p);
+  computeHMS(p);
+}
+
+/*
+** Clear the YMD and HMS and the TZ
+*/
+static void clearYMD_HMS_TZ(DateTime *p){
+  p->validYMD = 0;
+  p->validHMS = 0;
+  p->validTZ = 0;
+}
+
+#ifndef SQLITE_OMIT_LOCALTIME
+/*
+** Compute the difference (in milliseconds)
+** between localtime and UTC (a.k.a. GMT)
+** for the time value p where p is in UTC.
+*/
+static sqlite3_int64 localtimeOffset(DateTime *p){
+  DateTime x, y;
+  time_t t;
+  x = *p;
+  computeYMD_HMS(&x);
+  if( x.Y<1971 || x.Y>=2038 ){
+    x.Y = 2000;
+    x.M = 1;
+    x.D = 1;
+    x.h = 0;
+    x.m = 0;
+    x.s = 0.0;
+  } else {
+    int s = (int)(x.s + 0.5);
+    x.s = s;
+  }
+  x.tz = 0;
+  x.validJD = 0;
+  computeJD(&x);
+  t = (time_t)(x.iJD/1000 - 21086676*(i64)10000);
+#ifdef HAVE_LOCALTIME_R
+  {
+    struct tm sLocal;
+    localtime_r(&t, &sLocal);
+    y.Y = sLocal.tm_year + 1900;
+    y.M = sLocal.tm_mon + 1;
+    y.D = sLocal.tm_mday;
+    y.h = sLocal.tm_hour;
+    y.m = sLocal.tm_min;
+    y.s = sLocal.tm_sec;
+  }
+#elif defined(HAVE_LOCALTIME_S) && HAVE_LOCALTIME_S
+  {
+    struct tm sLocal;
+    localtime_s(&sLocal, &t);
+    y.Y = sLocal.tm_year + 1900;
+    y.M = sLocal.tm_mon + 1;
+    y.D = sLocal.tm_mday;
+    y.h = sLocal.tm_hour;
+    y.m = sLocal.tm_min;
+    y.s = sLocal.tm_sec;
+  }
+#else
+  {
+    struct tm *pTm;
+    sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
+    pTm = localtime(&t);
+    y.Y = pTm->tm_year + 1900;
+    y.M = pTm->tm_mon + 1;
+    y.D = pTm->tm_mday;
+    y.h = pTm->tm_hour;
+    y.m = pTm->tm_min;
+    y.s = pTm->tm_sec;
+    sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
+  }
+#endif
+  y.validYMD = 1;
+  y.validHMS = 1;
+  y.validJD = 0;
+  y.validTZ = 0;
+  computeJD(&y);
+  return y.iJD - x.iJD;
+}
+#endif /* SQLITE_OMIT_LOCALTIME */
+
+/*
+** Process a modifier to a date-time stamp.  The modifiers are
+** as follows:
+**
+**     NNN days
+**     NNN hours
+**     NNN minutes
+**     NNN.NNNN seconds
+**     NNN months
+**     NNN years
+**     start of month
+**     start of year
+**     start of week
+**     start of day
+**     weekday N
+**     unixepoch
+**     localtime
+**     utc
+**
+** Return 0 on success and 1 if there is any kind of error.
+*/
+static int parseModifier(const char *zMod, DateTime *p){
+  int rc = 1;
+  int n;
+  double r;
+  char *z, zBuf[30];
+  z = zBuf;
+  for(n=0; n<ArraySize(zBuf)-1 && zMod[n]; n++){
+    z[n] = (char)sqlite3UpperToLower[(u8)zMod[n]];
+  }
+  z[n] = 0;
+  switch( z[0] ){
+#ifndef SQLITE_OMIT_LOCALTIME
+    case 'l': {
+      /*    localtime
+      **
+      ** Assuming the current time value is UTC (a.k.a. GMT), shift it to
+      ** show local time.
+      */
+      if( strcmp(z, "localtime")==0 ){
+        computeJD(p);
+        p->iJD += localtimeOffset(p);
+        clearYMD_HMS_TZ(p);
+        rc = 0;
+      }
+      break;
+    }
+#endif
+    case 'u': {
+      /*
+      **    unixepoch
+      **
+      ** Treat the current value of p->iJD as the number of
+      ** seconds since 1970.  Convert to a real julian day number.
+      */
+      if( strcmp(z, "unixepoch")==0 && p->validJD ){
+        p->iJD = (p->iJD + 43200)/86400 + 21086676*(i64)10000000;
+        clearYMD_HMS_TZ(p);
+        rc = 0;
+      }
+#ifndef SQLITE_OMIT_LOCALTIME
+      else if( strcmp(z, "utc")==0 ){
+        sqlite3_int64 c1;
+        computeJD(p);
+        c1 = localtimeOffset(p);
+        p->iJD -= c1;
+        clearYMD_HMS_TZ(p);
+        p->iJD += c1 - localtimeOffset(p);
+        rc = 0;
+      }
+#endif
+      break;
+    }
+    case 'w': {
+      /*
+      **    weekday N
+      **
+      ** Move the date to the same time on the next occurrence of
+      ** weekday N where 0==Sunday, 1==Monday, and so forth.  If the
+      ** date is already on the appropriate weekday, this is a no-op.
+      */
+      if( strncmp(z, "weekday ", 8)==0
+               && sqlite3AtoF(&z[8], &r, sqlite3Strlen30(&z[8]), SQLITE_UTF8)
+               && (n=(int)r)==r && n>=0 && r<7 ){
+        sqlite3_int64 Z;
+        computeYMD_HMS(p);
+        p->validTZ = 0;
+        p->validJD = 0;
+        computeJD(p);
+        Z = ((p->iJD + 129600000)/86400000) % 7;
+        if( Z>n ) Z -= 7;
+        p->iJD += (n - Z)*86400000;
+        clearYMD_HMS_TZ(p);
+        rc = 0;
+      }
+      break;
+    }
+    case 's': {
+      /*
+      **    start of TTTTT
+      **
+      ** Move the date backwards to the beginning of the current day,
+      ** or month or year.
+      */
+      if( strncmp(z, "start of ", 9)!=0 ) break;
+      z += 9;
+      computeYMD(p);
+      p->validHMS = 1;
+      p->h = p->m = 0;
+      p->s = 0.0;
+      p->validTZ = 0;
+      p->validJD = 0;
+      if( strcmp(z,"month")==0 ){
+        p->D = 1;
+        rc = 0;
+      }else if( strcmp(z,"year")==0 ){
+        computeYMD(p);
+        p->M = 1;
+        p->D = 1;
+        rc = 0;
+      }else if( strcmp(z,"day")==0 ){
+        rc = 0;
+      }
+      break;
+    }
+    case '+':
+    case '-':
+    case '0':
+    case '1':
+    case '2':
+    case '3':
+    case '4':
+    case '5':
+    case '6':
+    case '7':
+    case '8':
+    case '9': {
+      double rRounder;
+      for(n=1; z[n] && z[n]!=':' && !sqlite3Isspace(z[n]); n++){}
+      if( !sqlite3AtoF(z, &r, n, SQLITE_UTF8) ){
+        rc = 1;
+        break;
+      }
+      if( z[n]==':' ){
+        /* A modifier of the form (+|-)HH:MM:SS.FFF adds (or subtracts) the
+        ** specified number of hours, minutes, seconds, and fractional seconds
+        ** to the time.  The ".FFF" may be omitted.  The ":SS.FFF" may be
+        ** omitted.
+        */
+        const char *z2 = z;
+        DateTime tx;
+        sqlite3_int64 day;
+        if( !sqlite3Isdigit(*z2) ) z2++;
+        memset(&tx, 0, sizeof(tx));
+        if( parseHhMmSs(z2, &tx) ) break;
+        computeJD(&tx);
+        tx.iJD -= 43200000;
+        day = tx.iJD/86400000;
+        tx.iJD -= day*86400000;
+        if( z[0]=='-' ) tx.iJD = -tx.iJD;
+        computeJD(p);
+        clearYMD_HMS_TZ(p);
+        p->iJD += tx.iJD;
+        rc = 0;
+        break;
+      }
+      z += n;
+      while( sqlite3Isspace(*z) ) z++;
+      n = sqlite3Strlen30(z);
+      if( n>10 || n<3 ) break;
+      if( z[n-1]=='s' ){ z[n-1] = 0; n--; }
+      computeJD(p);
+      rc = 0;
+      rRounder = r<0 ? -0.5 : +0.5;
+      if( n==3 && strcmp(z,"day")==0 ){
+        p->iJD += (sqlite3_int64)(r*86400000.0 + rRounder);
+      }else if( n==4 && strcmp(z,"hour")==0 ){
+        p->iJD += (sqlite3_int64)(r*(86400000.0/24.0) + rRounder);
+      }else if( n==6 && strcmp(z,"minute")==0 ){
+        p->iJD += (sqlite3_int64)(r*(86400000.0/(24.0*60.0)) + rRounder);
+      }else if( n==6 && strcmp(z,"second")==0 ){
+        p->iJD += (sqlite3_int64)(r*(86400000.0/(24.0*60.0*60.0)) + rRounder);
+      }else if( n==5 && strcmp(z,"month")==0 ){
+        int x, y;
+        computeYMD_HMS(p);
+        p->M += (int)r;
+        x = p->M>0 ? (p->M-1)/12 : (p->M-12)/12;
+        p->Y += x;
+        p->M -= x*12;
+        p->validJD = 0;
+        computeJD(p);
+        y = (int)r;
+        if( y!=r ){
+          p->iJD += (sqlite3_int64)((r - y)*30.0*86400000.0 + rRounder);
+        }
+      }else if( n==4 && strcmp(z,"year")==0 ){
+        int y = (int)r;
+        computeYMD_HMS(p);
+        p->Y += y;
+        p->validJD = 0;
+        computeJD(p);
+        if( y!=r ){
+          p->iJD += (sqlite3_int64)((r - y)*365.0*86400000.0 + rRounder);
+        }
+      }else{
+        rc = 1;
+      }
+      clearYMD_HMS_TZ(p);
+      break;
+    }
+    default: {
+      break;
+    }
+  }
+  return rc;
+}
+
+/*
+** Process time function arguments.  argv[0] is a date-time stamp.
+** argv[1] and following are modifiers.  Parse them all and write
+** the resulting time into the DateTime structure p.  Return 0
+** on success and 1 if there are any errors.
+**
+** If there are zero parameters (if even argv[0] is undefined)
+** then assume a default value of "now" for argv[0].
+*/
+static int isDate(
+  sqlite3_context *context, 
+  int argc, 
+  sqlite3_value **argv, 
+  DateTime *p
+){
+  int i;
+  const unsigned char *z;
+  int eType;
+  memset(p, 0, sizeof(*p));
+  if( argc==0 ){
+    setDateTimeToCurrent(context, p);
+  }else if( (eType = sqlite3_value_type(argv[0]))==SQLITE_FLOAT
+                   || eType==SQLITE_INTEGER ){
+    p->iJD = (sqlite3_int64)(sqlite3_value_double(argv[0])*86400000.0 + 0.5);
+    p->validJD = 1;
+  }else{
+    z = sqlite3_value_text(argv[0]);
+    if( !z || parseDateOrTime(context, (char*)z, p) ){
+      return 1;
+    }
+  }
+  for(i=1; i<argc; i++){
+    if( (z = sqlite3_value_text(argv[i]))==0 || parseModifier((char*)z, p) ){
+      return 1;
+    }
+  }
+  return 0;
+}
+
+
+/*
+** The following routines implement the various date and time functions
+** of SQLite.
+*/
+
+/*
+**    julianday( TIMESTRING, MOD, MOD, ...)
+**
+** Return the julian day number of the date specified in the arguments
+*/
+static void juliandayFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  DateTime x;
+  if( isDate(context, argc, argv, &x)==0 ){
+    computeJD(&x);
+    sqlite3_result_double(context, x.iJD/86400000.0);
+  }
+}
+
+/*
+**    datetime( TIMESTRING, MOD, MOD, ...)
+**
+** Return YYYY-MM-DD HH:MM:SS
+*/
+static void datetimeFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  DateTime x;
+  if( isDate(context, argc, argv, &x)==0 ){
+    char zBuf[100];
+    computeYMD_HMS(&x);
+    sqlite3_snprintf(sizeof(zBuf), zBuf, "%04d-%02d-%02d %02d:%02d:%02d",
+                     x.Y, x.M, x.D, x.h, x.m, (int)(x.s));
+    sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
+  }
+}
+
+/*
+**    time( TIMESTRING, MOD, MOD, ...)
+**
+** Return HH:MM:SS
+*/
+static void timeFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  DateTime x;
+  if( isDate(context, argc, argv, &x)==0 ){
+    char zBuf[100];
+    computeHMS(&x);
+    sqlite3_snprintf(sizeof(zBuf), zBuf, "%02d:%02d:%02d", x.h, x.m, (int)x.s);
+    sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
+  }
+}
+
+/*
+**    date( TIMESTRING, MOD, MOD, ...)
+**
+** Return YYYY-MM-DD
+*/
+static void dateFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  DateTime x;
+  if( isDate(context, argc, argv, &x)==0 ){
+    char zBuf[100];
+    computeYMD(&x);
+    sqlite3_snprintf(sizeof(zBuf), zBuf, "%04d-%02d-%02d", x.Y, x.M, x.D);
+    sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
+  }
+}
+
+/*
+**    strftime( FORMAT, TIMESTRING, MOD, MOD, ...)
+**
+** Return a string described by FORMAT.  Conversions as follows:
+**
+**   %d  day of month
+**   %f  ** fractional seconds  SS.SSS
+**   %H  hour 00-24
+**   %j  day of year 000-366
+**   %J  ** Julian day number
+**   %m  month 01-12
+**   %M  minute 00-59
+**   %s  seconds since 1970-01-01
+**   %S  seconds 00-59
+**   %w  day of week 0-6  sunday==0
+**   %W  week of year 00-53
+**   %Y  year 0000-9999
+**   %%  %
+*/
+static void strftimeFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  DateTime x;
+  u64 n;
+  size_t i,j;
+  char *z;
+  sqlite3 *db;
+  const char *zFmt = (const char*)sqlite3_value_text(argv[0]);
+  char zBuf[100];
+  if( zFmt==0 || isDate(context, argc-1, argv+1, &x) ) return;
+  db = sqlite3_context_db_handle(context);
+  for(i=0, n=1; zFmt[i]; i++, n++){
+    if( zFmt[i]=='%' ){
+      switch( zFmt[i+1] ){
+        case 'd':
+        case 'H':
+        case 'm':
+        case 'M':
+        case 'S':
+        case 'W':
+          n++;
+          /* fall thru */
+        case 'w':
+        case '%':
+          break;
+        case 'f':
+          n += 8;
+          break;
+        case 'j':
+          n += 3;
+          break;
+        case 'Y':
+          n += 8;
+          break;
+        case 's':
+        case 'J':
+          n += 50;
+          break;
+        default:
+          return;  /* ERROR.  return a NULL */
+      }
+      i++;
+    }
+  }
+  testcase( n==sizeof(zBuf)-1 );
+  testcase( n==sizeof(zBuf) );
+  testcase( n==(u64)db->aLimit[SQLITE_LIMIT_LENGTH]+1 );
+  testcase( n==(u64)db->aLimit[SQLITE_LIMIT_LENGTH] );
+  if( n<sizeof(zBuf) ){
+    z = zBuf;
+  }else if( n>(u64)db->aLimit[SQLITE_LIMIT_LENGTH] ){
+    sqlite3_result_error_toobig(context);
+    return;
+  }else{
+    z = sqlite3DbMallocRaw(db, (int)n);
+    if( z==0 ){
+      sqlite3_result_error_nomem(context);
+      return;
+    }
+  }
+  computeJD(&x);
+  computeYMD_HMS(&x);
+  for(i=j=0; zFmt[i]; i++){
+    if( zFmt[i]!='%' ){
+      z[j++] = zFmt[i];
+    }else{
+      i++;
+      switch( zFmt[i] ){
+        case 'd':  sqlite3_snprintf(3, &z[j],"%02d",x.D); j+=2; break;
+        case 'f': {
+          double s = x.s;
+          if( s>59.999 ) s = 59.999;
+          sqlite3_snprintf(7, &z[j],"%06.3f", s);
+          j += sqlite3Strlen30(&z[j]);
+          break;
+        }
+        case 'H':  sqlite3_snprintf(3, &z[j],"%02d",x.h); j+=2; break;
+        case 'W': /* Fall thru */
+        case 'j': {
+          int nDay;             /* Number of days since 1st day of year */
+          DateTime y = x;
+          y.validJD = 0;
+          y.M = 1;
+          y.D = 1;
+          computeJD(&y);
+          nDay = (int)((x.iJD-y.iJD+43200000)/86400000);
+          if( zFmt[i]=='W' ){
+            int wd;   /* 0=Monday, 1=Tuesday, ... 6=Sunday */
+            wd = (int)(((x.iJD+43200000)/86400000)%7);
+            sqlite3_snprintf(3, &z[j],"%02d",(nDay+7-wd)/7);
+            j += 2;
+          }else{
+            sqlite3_snprintf(4, &z[j],"%03d",nDay+1);
+            j += 3;
+          }
+          break;
+        }
+        case 'J': {
+          sqlite3_snprintf(20, &z[j],"%.16g",x.iJD/86400000.0);
+          j+=sqlite3Strlen30(&z[j]);
+          break;
+        }
+        case 'm':  sqlite3_snprintf(3, &z[j],"%02d",x.M); j+=2; break;
+        case 'M':  sqlite3_snprintf(3, &z[j],"%02d",x.m); j+=2; break;
+        case 's': {
+          sqlite3_snprintf(30,&z[j],"%lld",
+                           (i64)(x.iJD/1000 - 21086676*(i64)10000));
+          j += sqlite3Strlen30(&z[j]);
+          break;
+        }
+        case 'S':  sqlite3_snprintf(3,&z[j],"%02d",(int)x.s); j+=2; break;
+        case 'w': {
+          z[j++] = (char)(((x.iJD+129600000)/86400000) % 7) + '0';
+          break;
+        }
+        case 'Y': {
+          sqlite3_snprintf(5,&z[j],"%04d",x.Y); j+=sqlite3Strlen30(&z[j]);
+          break;
+        }
+        default:   z[j++] = '%'; break;
+      }
+    }
+  }
+  z[j] = 0;
+  sqlite3_result_text(context, z, -1,
+                      z==zBuf ? SQLITE_TRANSIENT : SQLITE_DYNAMIC);
+}
+
+/*
+** current_time()
+**
+** This function returns the same value as time('now').
+*/
+static void ctimeFunc(
+  sqlite3_context *context,
+  int NotUsed,
+  sqlite3_value **NotUsed2
+){
+  UNUSED_PARAMETER2(NotUsed, NotUsed2);
+  timeFunc(context, 0, 0);
+}
+
+/*
+** current_date()
+**
+** This function returns the same value as date('now').
+*/
+static void cdateFunc(
+  sqlite3_context *context,
+  int NotUsed,
+  sqlite3_value **NotUsed2
+){
+  UNUSED_PARAMETER2(NotUsed, NotUsed2);
+  dateFunc(context, 0, 0);
+}
+
+/*
+** current_timestamp()
+**
+** This function returns the same value as datetime('now').
+*/
+static void ctimestampFunc(
+  sqlite3_context *context,
+  int NotUsed,
+  sqlite3_value **NotUsed2
+){
+  UNUSED_PARAMETER2(NotUsed, NotUsed2);
+  datetimeFunc(context, 0, 0);
+}
+#endif /* !defined(SQLITE_OMIT_DATETIME_FUNCS) */
+
+#ifdef SQLITE_OMIT_DATETIME_FUNCS
+/*
+** If the library is compiled to omit the full-scale date and time
+** handling (to get a smaller binary), the following minimal version
+** of the functions current_time(), current_date() and current_timestamp()
+** are included instead. This is to support column declarations that
+** include "DEFAULT CURRENT_TIME" etc.
+**
+** This function uses the C-library functions time(), gmtime()
+** and strftime(). The format string to pass to strftime() is supplied
+** as the user-data for the function.
+*/
+static void currentTimeFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  time_t t;
+  char *zFormat = (char *)sqlite3_user_data(context);
+  sqlite3 *db;
+  sqlite3_int64 iT;
+  char zBuf[20];
+
+  UNUSED_PARAMETER(argc);
+  UNUSED_PARAMETER(argv);
+
+  db = sqlite3_context_db_handle(context);
+  sqlite3OsCurrentTimeInt64(db->pVfs, &iT);
+  t = iT/1000 - 10000*(sqlite3_int64)21086676;
+#ifdef HAVE_GMTIME_R
+  {
+    struct tm sNow;
+    gmtime_r(&t, &sNow);
+    strftime(zBuf, 20, zFormat, &sNow);
+  }
+#else
+  {
+    struct tm *pTm;
+    sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
+    pTm = gmtime(&t);
+    strftime(zBuf, 20, zFormat, pTm);
+    sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
+  }
+#endif
+
+  sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
+}
+#endif
+
+/*
+** This function registered all of the above C functions as SQL
+** functions.  This should be the only routine in this file with
+** external linkage.
+*/
+SQLITE_PRIVATE void sqlite3RegisterDateTimeFunctions(void){
+  static SQLITE_WSD FuncDef aDateTimeFuncs[] = {
+#ifndef SQLITE_OMIT_DATETIME_FUNCS
+    FUNCTION(julianday,        -1, 0, 0, juliandayFunc ),
+    FUNCTION(date,             -1, 0, 0, dateFunc      ),
+    FUNCTION(time,             -1, 0, 0, timeFunc      ),
+    FUNCTION(datetime,         -1, 0, 0, datetimeFunc  ),
+    FUNCTION(strftime,         -1, 0, 0, strftimeFunc  ),
+    FUNCTION(current_time,      0, 0, 0, ctimeFunc     ),
+    FUNCTION(current_timestamp, 0, 0, 0, ctimestampFunc),
+    FUNCTION(current_date,      0, 0, 0, cdateFunc     ),
+#else
+    STR_FUNCTION(current_time,      0, "%H:%M:%S",          0, currentTimeFunc),
+    STR_FUNCTION(current_date,      0, "%Y-%m-%d",          0, currentTimeFunc),
+    STR_FUNCTION(current_timestamp, 0, "%Y-%m-%d %H:%M:%S", 0, currentTimeFunc),
+#endif
+  };
+  int i;
+  FuncDefHash *pHash = &GLOBAL(FuncDefHash, sqlite3GlobalFunctions);
+  FuncDef *aFunc = (FuncDef*)&GLOBAL(FuncDef, aDateTimeFuncs);
+
+  for(i=0; i<ArraySize(aDateTimeFuncs); i++){
+    sqlite3FuncDefInsert(pHash, &aFunc[i]);
+  }
+}
+
+/************** End of date.c ************************************************/
+/************** Begin file os.c **********************************************/
+/*
+** 2005 November 29
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains OS interface code that is common to all
+** architectures.
+*/
+#define _SQLITE_OS_C_ 1
+#undef _SQLITE_OS_C_
+
+/*
+** The default SQLite sqlite3_vfs implementations do not allocate
+** memory (actually, os_unix.c allocates a small amount of memory
+** from within OsOpen()), but some third-party implementations may.
+** So we test the effects of a malloc() failing and the sqlite3OsXXX()
+** function returning SQLITE_IOERR_NOMEM using the DO_OS_MALLOC_TEST macro.
+**
+** The following functions are instrumented for malloc() failure 
+** testing:
+**
+**     sqlite3OsOpen()
+**     sqlite3OsRead()
+**     sqlite3OsWrite()
+**     sqlite3OsSync()
+**     sqlite3OsLock()
+**
+*/
+#if defined(SQLITE_TEST)
+SQLITE_API int sqlite3_memdebug_vfs_oom_test = 1;
+  #define DO_OS_MALLOC_TEST(x)                                       \
+  if (sqlite3_memdebug_vfs_oom_test && (!x || !sqlite3IsMemJournal(x))) {  \
+    void *pTstAlloc = sqlite3Malloc(10);                             \
+    if (!pTstAlloc) return SQLITE_IOERR_NOMEM;                       \
+    sqlite3_free(pTstAlloc);                                         \
+  }
+#else
+  #define DO_OS_MALLOC_TEST(x)
+#endif
+
+/*
+** The following routines are convenience wrappers around methods
+** of the sqlite3_file object.  This is mostly just syntactic sugar. All
+** of this would be completely automatic if SQLite were coded using
+** C++ instead of plain old C.
+*/
+SQLITE_PRIVATE int sqlite3OsClose(sqlite3_file *pId){
+  int rc = SQLITE_OK;
+  if( pId->pMethods ){
+    rc = pId->pMethods->xClose(pId);
+    pId->pMethods = 0;
+  }
+  return rc;
+}
+SQLITE_PRIVATE int sqlite3OsRead(sqlite3_file *id, void *pBuf, int amt, i64 offset){
+  DO_OS_MALLOC_TEST(id);
+  return id->pMethods->xRead(id, pBuf, amt, offset);
+}
+SQLITE_PRIVATE int sqlite3OsWrite(sqlite3_file *id, const void *pBuf, int amt, i64 offset){
+  DO_OS_MALLOC_TEST(id);
+  return id->pMethods->xWrite(id, pBuf, amt, offset);
+}
+SQLITE_PRIVATE int sqlite3OsTruncate(sqlite3_file *id, i64 size){
+  return id->pMethods->xTruncate(id, size);
+}
+SQLITE_PRIVATE int sqlite3OsSync(sqlite3_file *id, int flags){
+  DO_OS_MALLOC_TEST(id);
+  return id->pMethods->xSync(id, flags);
+}
+SQLITE_PRIVATE int sqlite3OsFileSize(sqlite3_file *id, i64 *pSize){
+  DO_OS_MALLOC_TEST(id);
+  return id->pMethods->xFileSize(id, pSize);
+}
+SQLITE_PRIVATE int sqlite3OsLock(sqlite3_file *id, int lockType){
+  DO_OS_MALLOC_TEST(id);
+  return id->pMethods->xLock(id, lockType);
+}
+SQLITE_PRIVATE int sqlite3OsUnlock(sqlite3_file *id, int lockType){
+  return id->pMethods->xUnlock(id, lockType);
+}
+SQLITE_PRIVATE int sqlite3OsCheckReservedLock(sqlite3_file *id, int *pResOut){
+  DO_OS_MALLOC_TEST(id);
+  return id->pMethods->xCheckReservedLock(id, pResOut);
+}
+SQLITE_PRIVATE int sqlite3OsFileControl(sqlite3_file *id, int op, void *pArg){
+  return id->pMethods->xFileControl(id, op, pArg);
+}
+SQLITE_PRIVATE int sqlite3OsSectorSize(sqlite3_file *id){
+  int (*xSectorSize)(sqlite3_file*) = id->pMethods->xSectorSize;
+  return (xSectorSize ? xSectorSize(id) : SQLITE_DEFAULT_SECTOR_SIZE);
+}
+SQLITE_PRIVATE int sqlite3OsDeviceCharacteristics(sqlite3_file *id){
+  return id->pMethods->xDeviceCharacteristics(id);
+}
+SQLITE_PRIVATE int sqlite3OsShmLock(sqlite3_file *id, int offset, int n, int flags){
+  return id->pMethods->xShmLock(id, offset, n, flags);
+}
+SQLITE_PRIVATE void sqlite3OsShmBarrier(sqlite3_file *id){
+  id->pMethods->xShmBarrier(id);
+}
+SQLITE_PRIVATE int sqlite3OsShmUnmap(sqlite3_file *id, int deleteFlag){
+  return id->pMethods->xShmUnmap(id, deleteFlag);
+}
+SQLITE_PRIVATE int sqlite3OsShmMap(
+  sqlite3_file *id,               /* Database file handle */
+  int iPage,
+  int pgsz,
+  int bExtend,                    /* True to extend file if necessary */
+  void volatile **pp              /* OUT: Pointer to mapping */
+){
+  return id->pMethods->xShmMap(id, iPage, pgsz, bExtend, pp);
+}
+
+/*
+** The next group of routines are convenience wrappers around the
+** VFS methods.
+*/
+SQLITE_PRIVATE int sqlite3OsOpen(
+  sqlite3_vfs *pVfs, 
+  const char *zPath, 
+  sqlite3_file *pFile, 
+  int flags, 
+  int *pFlagsOut
+){
+  int rc;
+  DO_OS_MALLOC_TEST(0);
+  /* 0x87f3f is a mask of SQLITE_OPEN_ flags that are valid to be passed
+  ** down into the VFS layer.  Some SQLITE_OPEN_ flags (for example,
+  ** SQLITE_OPEN_FULLMUTEX or SQLITE_OPEN_SHAREDCACHE) are blocked before
+  ** reaching the VFS. */
+  rc = pVfs->xOpen(pVfs, zPath, pFile, flags & 0x87f3f, pFlagsOut);
+  assert( rc==SQLITE_OK || pFile->pMethods==0 );
+  return rc;
+}
+SQLITE_PRIVATE int sqlite3OsDelete(sqlite3_vfs *pVfs, const char *zPath, int dirSync){
+  return pVfs->xDelete(pVfs, zPath, dirSync);
+}
+SQLITE_PRIVATE int sqlite3OsAccess(
+  sqlite3_vfs *pVfs, 
+  const char *zPath, 
+  int flags, 
+  int *pResOut
+){
+  DO_OS_MALLOC_TEST(0);
+  return pVfs->xAccess(pVfs, zPath, flags, pResOut);
+}
+SQLITE_PRIVATE int sqlite3OsFullPathname(
+  sqlite3_vfs *pVfs, 
+  const char *zPath, 
+  int nPathOut, 
+  char *zPathOut
+){
+  zPathOut[0] = 0;
+  return pVfs->xFullPathname(pVfs, zPath, nPathOut, zPathOut);
+}
+#ifndef SQLITE_OMIT_LOAD_EXTENSION
+SQLITE_PRIVATE void *sqlite3OsDlOpen(sqlite3_vfs *pVfs, const char *zPath){
+  return pVfs->xDlOpen(pVfs, zPath);
+}
+SQLITE_PRIVATE void sqlite3OsDlError(sqlite3_vfs *pVfs, int nByte, char *zBufOut){
+  pVfs->xDlError(pVfs, nByte, zBufOut);
+}
+SQLITE_PRIVATE void (*sqlite3OsDlSym(sqlite3_vfs *pVfs, void *pHdle, const char *zSym))(void){
+  return pVfs->xDlSym(pVfs, pHdle, zSym);
+}
+SQLITE_PRIVATE void sqlite3OsDlClose(sqlite3_vfs *pVfs, void *pHandle){
+  pVfs->xDlClose(pVfs, pHandle);
+}
+#endif /* SQLITE_OMIT_LOAD_EXTENSION */
+SQLITE_PRIVATE int sqlite3OsRandomness(sqlite3_vfs *pVfs, int nByte, char *zBufOut){
+  return pVfs->xRandomness(pVfs, nByte, zBufOut);
+}
+SQLITE_PRIVATE int sqlite3OsSleep(sqlite3_vfs *pVfs, int nMicro){
+  return pVfs->xSleep(pVfs, nMicro);
+}
+SQLITE_PRIVATE int sqlite3OsCurrentTimeInt64(sqlite3_vfs *pVfs, sqlite3_int64 *pTimeOut){
+  int rc;
+  /* IMPLEMENTATION-OF: R-49045-42493 SQLite will use the xCurrentTimeInt64()
+  ** method to get the current date and time if that method is available
+  ** (if iVersion is 2 or greater and the function pointer is not NULL) and
+  ** will fall back to xCurrentTime() if xCurrentTimeInt64() is
+  ** unavailable.
+  */
+  if( pVfs->iVersion>=2 && pVfs->xCurrentTimeInt64 ){
+    rc = pVfs->xCurrentTimeInt64(pVfs, pTimeOut);
+  }else{
+    double r;
+    rc = pVfs->xCurrentTime(pVfs, &r);
+    *pTimeOut = (sqlite3_int64)(r*86400000.0);
+  }
+  return rc;
+}
+
+SQLITE_PRIVATE int sqlite3OsOpenMalloc(
+  sqlite3_vfs *pVfs, 
+  const char *zFile, 
+  sqlite3_file **ppFile, 
+  int flags,
+  int *pOutFlags
+){
+  int rc = SQLITE_NOMEM;
+  sqlite3_file *pFile;
+  pFile = (sqlite3_file *)sqlite3Malloc(pVfs->szOsFile);
+  if( pFile ){
+    rc = sqlite3OsOpen(pVfs, zFile, pFile, flags, pOutFlags);
+    if( rc!=SQLITE_OK ){
+      sqlite3_free(pFile);
+    }else{
+      *ppFile = pFile;
+    }
+  }
+  return rc;
+}
+SQLITE_PRIVATE int sqlite3OsCloseFree(sqlite3_file *pFile){
+  int rc = SQLITE_OK;
+  assert( pFile );
+  rc = sqlite3OsClose(pFile);
+  sqlite3_free(pFile);
+  return rc;
+}
+
+/*
+** This function is a wrapper around the OS specific implementation of
+** sqlite3_os_init(). The purpose of the wrapper is to provide the
+** ability to simulate a malloc failure, so that the handling of an
+** error in sqlite3_os_init() by the upper layers can be tested.
+*/
+SQLITE_PRIVATE int sqlite3OsInit(void){
+  void *p = sqlite3_malloc(10);
+  if( p==0 ) return SQLITE_NOMEM;
+  sqlite3_free(p);
+  return sqlite3_os_init();
+}
+
+/*
+** The list of all registered VFS implementations.
+*/
+static sqlite3_vfs * SQLITE_WSD vfsList = 0;
+#define vfsList GLOBAL(sqlite3_vfs *, vfsList)
+
+/*
+** Locate a VFS by name.  If no name is given, simply return the
+** first VFS on the list.
+*/
+SQLITE_API sqlite3_vfs *sqlite3_vfs_find(const char *zVfs){
+  sqlite3_vfs *pVfs = 0;
+#if SQLITE_THREADSAFE
+  sqlite3_mutex *mutex;
+#endif
+#ifndef SQLITE_OMIT_AUTOINIT
+  int rc = sqlite3_initialize();
+  if( rc ) return 0;
+#endif
+#if SQLITE_THREADSAFE
+  mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
+#endif
+  sqlite3_mutex_enter(mutex);
+  for(pVfs = vfsList; pVfs; pVfs=pVfs->pNext){
+    if( zVfs==0 ) break;
+    if( strcmp(zVfs, pVfs->zName)==0 ) break;
+  }
+  sqlite3_mutex_leave(mutex);
+  return pVfs;
+}
+
+/*
+** Unlink a VFS from the linked list
+*/
+static void vfsUnlink(sqlite3_vfs *pVfs){
+  assert( sqlite3_mutex_held(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER)) );
+  if( pVfs==0 ){
+    /* No-op */
+  }else if( vfsList==pVfs ){
+    vfsList = pVfs->pNext;
+  }else if( vfsList ){
+    sqlite3_vfs *p = vfsList;
+    while( p->pNext && p->pNext!=pVfs ){
+      p = p->pNext;
+    }
+    if( p->pNext==pVfs ){
+      p->pNext = pVfs->pNext;
+    }
+  }
+}
+
+/*
+** Register a VFS with the system.  It is harmless to register the same
+** VFS multiple times.  The new VFS becomes the default if makeDflt is
+** true.
+*/
+SQLITE_API int sqlite3_vfs_register(sqlite3_vfs *pVfs, int makeDflt){
+  sqlite3_mutex *mutex = 0;
+#ifndef SQLITE_OMIT_AUTOINIT
+  int rc = sqlite3_initialize();
+  if( rc ) return rc;
+#endif
+  mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
+  sqlite3_mutex_enter(mutex);
+  vfsUnlink(pVfs);
+  if( makeDflt || vfsList==0 ){
+    pVfs->pNext = vfsList;
+    vfsList = pVfs;
+  }else{
+    pVfs->pNext = vfsList->pNext;
+    vfsList->pNext = pVfs;
+  }
+  assert(vfsList);
+  sqlite3_mutex_leave(mutex);
+  return SQLITE_OK;
+}
+
+/*
+** Unregister a VFS so that it is no longer accessible.
+*/
+SQLITE_API int sqlite3_vfs_unregister(sqlite3_vfs *pVfs){
+#if SQLITE_THREADSAFE
+  sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
+#endif
+  sqlite3_mutex_enter(mutex);
+  vfsUnlink(pVfs);
+  sqlite3_mutex_leave(mutex);
+  return SQLITE_OK;
+}
+
+/************** End of os.c **************************************************/
+/************** Begin file fault.c *******************************************/
+/*
+** 2008 Jan 22
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains code to support the concept of "benign" 
+** malloc failures (when the xMalloc() or xRealloc() method of the
+** sqlite3_mem_methods structure fails to allocate a block of memory
+** and returns 0). 
+**
+** Most malloc failures are non-benign. After they occur, SQLite
+** abandons the current operation and returns an error code (usually
+** SQLITE_NOMEM) to the user. However, sometimes a fault is not necessarily
+** fatal. For example, if a malloc fails while resizing a hash table, this 
+** is completely recoverable simply by not carrying out the resize. The 
+** hash table will continue to function normally.  So a malloc failure 
+** during a hash table resize is a benign fault.
+*/
+
+
+#ifndef SQLITE_OMIT_BUILTIN_TEST
+
+/*
+** Global variables.
+*/
+typedef struct BenignMallocHooks BenignMallocHooks;
+static SQLITE_WSD struct BenignMallocHooks {
+  void (*xBenignBegin)(void);
+  void (*xBenignEnd)(void);
+} sqlite3Hooks = { 0, 0 };
+
+/* The "wsdHooks" macro will resolve to the appropriate BenignMallocHooks
+** structure.  If writable static data is unsupported on the target,
+** we have to locate the state vector at run-time.  In the more common
+** case where writable static data is supported, wsdHooks can refer directly
+** to the "sqlite3Hooks" state vector declared above.
+*/
+#ifdef SQLITE_OMIT_WSD
+# define wsdHooksInit \
+  BenignMallocHooks *x = &GLOBAL(BenignMallocHooks,sqlite3Hooks)
+# define wsdHooks x[0]
+#else
+# define wsdHooksInit
+# define wsdHooks sqlite3Hooks
+#endif
+
+
+/*
+** Register hooks to call when sqlite3BeginBenignMalloc() and
+** sqlite3EndBenignMalloc() are called, respectively.
+*/
+SQLITE_PRIVATE void sqlite3BenignMallocHooks(
+  void (*xBenignBegin)(void),
+  void (*xBenignEnd)(void)
+){
+  wsdHooksInit;
+  wsdHooks.xBenignBegin = xBenignBegin;
+  wsdHooks.xBenignEnd = xBenignEnd;
+}
+
+/*
+** This (sqlite3EndBenignMalloc()) is called by SQLite code to indicate that
+** subsequent malloc failures are benign. A call to sqlite3EndBenignMalloc()
+** indicates that subsequent malloc failures are non-benign.
+*/
+SQLITE_PRIVATE void sqlite3BeginBenignMalloc(void){
+  wsdHooksInit;
+  if( wsdHooks.xBenignBegin ){
+    wsdHooks.xBenignBegin();
+  }
+}
+SQLITE_PRIVATE void sqlite3EndBenignMalloc(void){
+  wsdHooksInit;
+  if( wsdHooks.xBenignEnd ){
+    wsdHooks.xBenignEnd();
+  }
+}
+
+#endif   /* #ifndef SQLITE_OMIT_BUILTIN_TEST */
+
+/************** End of fault.c ***********************************************/
+/************** Begin file mem0.c ********************************************/
+/*
+** 2008 October 28
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains a no-op memory allocation drivers for use when
+** SQLITE_ZERO_MALLOC is defined.  The allocation drivers implemented
+** here always fail.  SQLite will not operate with these drivers.  These
+** are merely placeholders.  Real drivers must be substituted using
+** sqlite3_config() before SQLite will operate.
+*/
+
+/*
+** This version of the memory allocator is the default.  It is
+** used when no other memory allocator is specified using compile-time
+** macros.
+*/
+#ifdef SQLITE_ZERO_MALLOC
+
+/*
+** No-op versions of all memory allocation routines
+*/
+static void *sqlite3MemMalloc(int nByte){ return 0; }
+static void sqlite3MemFree(void *pPrior){ return; }
+static void *sqlite3MemRealloc(void *pPrior, int nByte){ return 0; }
+static int sqlite3MemSize(void *pPrior){ return 0; }
+static int sqlite3MemRoundup(int n){ return n; }
+static int sqlite3MemInit(void *NotUsed){ return SQLITE_OK; }
+static void sqlite3MemShutdown(void *NotUsed){ return; }
+
+/*
+** This routine is the only routine in this file with external linkage.
+**
+** Populate the low-level memory allocation function pointers in
+** sqlite3GlobalConfig.m with pointers to the routines in this file.
+*/
+SQLITE_PRIVATE void sqlite3MemSetDefault(void){
+  static const sqlite3_mem_methods defaultMethods = {
+     sqlite3MemMalloc,
+     sqlite3MemFree,
+     sqlite3MemRealloc,
+     sqlite3MemSize,
+     sqlite3MemRoundup,
+     sqlite3MemInit,
+     sqlite3MemShutdown,
+     0
+  };
+  sqlite3_config(SQLITE_CONFIG_MALLOC, &defaultMethods);
+}
+
+#endif /* SQLITE_ZERO_MALLOC */
+
+/************** End of mem0.c ************************************************/
+/************** Begin file mem1.c ********************************************/
+/*
+** 2007 August 14
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains low-level memory allocation drivers for when
+** SQLite will use the standard C-library malloc/realloc/free interface
+** to obtain the memory it needs.
+**
+** This file contains implementations of the low-level memory allocation
+** routines specified in the sqlite3_mem_methods object.
+*/
+
+/*
+** This version of the memory allocator is the default.  It is
+** used when no other memory allocator is specified using compile-time
+** macros.
+*/
+#ifdef SQLITE_SYSTEM_MALLOC
+
+/*
+** Like malloc(), but remember the size of the allocation
+** so that we can find it later using sqlite3MemSize().
+**
+** For this low-level routine, we are guaranteed that nByte>0 because
+** cases of nByte<=0 will be intercepted and dealt with by higher level
+** routines.
+*/
+static void *sqlite3MemMalloc(int nByte){
+  sqlite3_int64 *p;
+  assert( nByte>0 );
+  nByte = ROUND8(nByte);
+  p = malloc( nByte+8 );
+  if( p ){
+    p[0] = nByte;
+    p++;
+  }else{
+    testcase( sqlite3GlobalConfig.xLog!=0 );
+    sqlite3_log(SQLITE_NOMEM, "failed to allocate %u bytes of memory", nByte);
+  }
+  return (void *)p;
+}
+
+/*
+** Like free() but works for allocations obtained from sqlite3MemMalloc()
+** or sqlite3MemRealloc().
+**
+** For this low-level routine, we already know that pPrior!=0 since
+** cases where pPrior==0 will have been intecepted and dealt with
+** by higher-level routines.
+*/
+static void sqlite3MemFree(void *pPrior){
+  sqlite3_int64 *p = (sqlite3_int64*)pPrior;
+  assert( pPrior!=0 );
+  p--;
+  free(p);
+}
+
+/*
+** Report the allocated size of a prior return from xMalloc()
+** or xRealloc().
+*/
+static int sqlite3MemSize(void *pPrior){
+  sqlite3_int64 *p;
+  if( pPrior==0 ) return 0;
+  p = (sqlite3_int64*)pPrior;
+  p--;
+  return (int)p[0];
+}
+
+/*
+** Like realloc().  Resize an allocation previously obtained from
+** sqlite3MemMalloc().
+**
+** For this low-level interface, we know that pPrior!=0.  Cases where
+** pPrior==0 while have been intercepted by higher-level routine and
+** redirected to xMalloc.  Similarly, we know that nByte>0 becauses
+** cases where nByte<=0 will have been intercepted by higher-level
+** routines and redirected to xFree.
+*/
+static void *sqlite3MemRealloc(void *pPrior, int nByte){
+  sqlite3_int64 *p = (sqlite3_int64*)pPrior;
+  assert( pPrior!=0 && nByte>0 );
+  assert( nByte==ROUND8(nByte) ); /* EV: R-46199-30249 */
+  p--;
+  p = realloc(p, nByte+8 );
+  if( p ){
+    p[0] = nByte;
+    p++;
+  }else{
+    testcase( sqlite3GlobalConfig.xLog!=0 );
+    sqlite3_log(SQLITE_NOMEM,
+      "failed memory resize %u to %u bytes",
+      sqlite3MemSize(pPrior), nByte);
+  }
+  return (void*)p;
+}
+
+/*
+** Round up a request size to the next valid allocation size.
+*/
+static int sqlite3MemRoundup(int n){
+  return ROUND8(n);
+}
+
+/*
+** Initialize this module.
+*/
+static int sqlite3MemInit(void *NotUsed){
+  UNUSED_PARAMETER(NotUsed);
+  return SQLITE_OK;
+}
+
+/*
+** Deinitialize this module.
+*/
+static void sqlite3MemShutdown(void *NotUsed){
+  UNUSED_PARAMETER(NotUsed);
+  return;
+}
+
+/*
+** This routine is the only routine in this file with external linkage.
+**
+** Populate the low-level memory allocation function pointers in
+** sqlite3GlobalConfig.m with pointers to the routines in this file.
+*/
+SQLITE_PRIVATE void sqlite3MemSetDefault(void){
+  static const sqlite3_mem_methods defaultMethods = {
+     sqlite3MemMalloc,
+     sqlite3MemFree,
+     sqlite3MemRealloc,
+     sqlite3MemSize,
+     sqlite3MemRoundup,
+     sqlite3MemInit,
+     sqlite3MemShutdown,
+     0
+  };
+  sqlite3_config(SQLITE_CONFIG_MALLOC, &defaultMethods);
+}
+
+#endif /* SQLITE_SYSTEM_MALLOC */
+
+/************** End of mem1.c ************************************************/
+/************** Begin file mem2.c ********************************************/
+/*
+** 2007 August 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains low-level memory allocation drivers for when
+** SQLite will use the standard C-library malloc/realloc/free interface
+** to obtain the memory it needs while adding lots of additional debugging
+** information to each allocation in order to help detect and fix memory
+** leaks and memory usage errors.
+**
+** This file contains implementations of the low-level memory allocation
+** routines specified in the sqlite3_mem_methods object.
+*/
+
+/*
+** This version of the memory allocator is used only if the
+** SQLITE_MEMDEBUG macro is defined
+*/
+#ifdef SQLITE_MEMDEBUG
+
+/*
+** The backtrace functionality is only available with GLIBC
+*/
+#ifdef __GLIBC__
+  extern int backtrace(void**,int);
+  extern void backtrace_symbols_fd(void*const*,int,int);
+#else
+# define backtrace(A,B) 1
+# define backtrace_symbols_fd(A,B,C)
+#endif
+
+/*
+** Each memory allocation looks like this:
+**
+**  ------------------------------------------------------------------------
+**  | Title |  backtrace pointers |  MemBlockHdr |  allocation |  EndGuard |
+**  ------------------------------------------------------------------------
+**
+** The application code sees only a pointer to the allocation.  We have
+** to back up from the allocation pointer to find the MemBlockHdr.  The
+** MemBlockHdr tells us the size of the allocation and the number of
+** backtrace pointers.  There is also a guard word at the end of the
+** MemBlockHdr.
+*/
+struct MemBlockHdr {
+  i64 iSize;                          /* Size of this allocation */
+  struct MemBlockHdr *pNext, *pPrev;  /* Linked list of all unfreed memory */
+  char nBacktrace;                    /* Number of backtraces on this alloc */
+  char nBacktraceSlots;               /* Available backtrace slots */
+  u8 nTitle;                          /* Bytes of title; includes '\0' */
+  u8 eType;                           /* Allocation type code */
+  int iForeGuard;                     /* Guard word for sanity */
+};
+
+/*
+** Guard words
+*/
+#define FOREGUARD 0x80F5E153
+#define REARGUARD 0xE4676B53
+
+/*
+** Number of malloc size increments to track.
+*/
+#define NCSIZE  1000
+
+/*
+** All of the static variables used by this module are collected
+** into a single structure named "mem".  This is to keep the
+** static variables organized and to reduce namespace pollution
+** when this module is combined with other in the amalgamation.
+*/
+static struct {
+  
+  /*
+  ** Mutex to control access to the memory allocation subsystem.
+  */
+  sqlite3_mutex *mutex;
+
+  /*
+  ** Head and tail of a linked list of all outstanding allocations
+  */
+  struct MemBlockHdr *pFirst;
+  struct MemBlockHdr *pLast;
+  
+  /*
+  ** The number of levels of backtrace to save in new allocations.
+  */
+  int nBacktrace;
+  void (*xBacktrace)(int, int, void **);
+
+  /*
+  ** Title text to insert in front of each block
+  */
+  int nTitle;        /* Bytes of zTitle to save.  Includes '\0' and padding */
+  char zTitle[100];  /* The title text */
+
+  /* 
+  ** sqlite3MallocDisallow() increments the following counter.
+  ** sqlite3MallocAllow() decrements it.
+  */
+  int disallow; /* Do not allow memory allocation */
+
+  /*
+  ** Gather statistics on the sizes of memory allocations.
+  ** nAlloc[i] is the number of allocation attempts of i*8
+  ** bytes.  i==NCSIZE is the number of allocation attempts for
+  ** sizes more than NCSIZE*8 bytes.
+  */
+  int nAlloc[NCSIZE];      /* Total number of allocations */
+  int nCurrent[NCSIZE];    /* Current number of allocations */
+  int mxCurrent[NCSIZE];   /* Highwater mark for nCurrent */
+
+} mem;
+
+
+/*
+** Adjust memory usage statistics
+*/
+static void adjustStats(int iSize, int increment){
+  int i = ROUND8(iSize)/8;
+  if( i>NCSIZE-1 ){
+    i = NCSIZE - 1;
+  }
+  if( increment>0 ){
+    mem.nAlloc[i]++;
+    mem.nCurrent[i]++;
+    if( mem.nCurrent[i]>mem.mxCurrent[i] ){
+      mem.mxCurrent[i] = mem.nCurrent[i];
+    }
+  }else{
+    mem.nCurrent[i]--;
+    assert( mem.nCurrent[i]>=0 );
+  }
+}
+
+/*
+** Given an allocation, find the MemBlockHdr for that allocation.
+**
+** This routine checks the guards at either end of the allocation and
+** if they are incorrect it asserts.
+*/
+static struct MemBlockHdr *sqlite3MemsysGetHeader(void *pAllocation){
+  struct MemBlockHdr *p;
+  int *pInt;
+  u8 *pU8;
+  int nReserve;
+
+  p = (struct MemBlockHdr*)pAllocation;
+  p--;
+  assert( p->iForeGuard==(int)FOREGUARD );
+  nReserve = ROUND8(p->iSize);
+  pInt = (int*)pAllocation;
+  pU8 = (u8*)pAllocation;
+  assert( pInt[nReserve/sizeof(int)]==(int)REARGUARD );
+  /* This checks any of the "extra" bytes allocated due
+  ** to rounding up to an 8 byte boundary to ensure 
+  ** they haven't been overwritten.
+  */
+  while( nReserve-- > p->iSize ) assert( pU8[nReserve]==0x65 );
+  return p;
+}
+
+/*
+** Return the number of bytes currently allocated at address p.
+*/
+static int sqlite3MemSize(void *p){
+  struct MemBlockHdr *pHdr;
+  if( !p ){
+    return 0;
+  }
+  pHdr = sqlite3MemsysGetHeader(p);
+  return pHdr->iSize;
+}
+
+/*
+** Initialize the memory allocation subsystem.
+*/
+static int sqlite3MemInit(void *NotUsed){
+  UNUSED_PARAMETER(NotUsed);
+  assert( (sizeof(struct MemBlockHdr)&7) == 0 );
+  if( !sqlite3GlobalConfig.bMemstat ){
+    /* If memory status is enabled, then the malloc.c wrapper will already
+    ** hold the STATIC_MEM mutex when the routines here are invoked. */
+    mem.mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM);
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Deinitialize the memory allocation subsystem.
+*/
+static void sqlite3MemShutdown(void *NotUsed){
+  UNUSED_PARAMETER(NotUsed);
+  mem.mutex = 0;
+}
+
+/*
+** Round up a request size to the next valid allocation size.
+*/
+static int sqlite3MemRoundup(int n){
+  return ROUND8(n);
+}
+
+/*
+** Fill a buffer with pseudo-random bytes.  This is used to preset
+** the content of a new memory allocation to unpredictable values and
+** to clear the content of a freed allocation to unpredictable values.
+*/
+static void randomFill(char *pBuf, int nByte){
+  unsigned int x, y, r;
+  x = SQLITE_PTR_TO_INT(pBuf);
+  y = nByte | 1;
+  while( nByte >= 4 ){
+    x = (x>>1) ^ (-(x&1) & 0xd0000001);
+    y = y*1103515245 + 12345;
+    r = x ^ y;
+    *(int*)pBuf = r;
+    pBuf += 4;
+    nByte -= 4;
+  }
+  while( nByte-- > 0 ){
+    x = (x>>1) ^ (-(x&1) & 0xd0000001);
+    y = y*1103515245 + 12345;
+    r = x ^ y;
+    *(pBuf++) = r & 0xff;
+  }
+}
+
+/*
+** Allocate nByte bytes of memory.
+*/
+static void *sqlite3MemMalloc(int nByte){
+  struct MemBlockHdr *pHdr;
+  void **pBt;
+  char *z;
+  int *pInt;
+  void *p = 0;
+  int totalSize;
+  int nReserve;
+  sqlite3_mutex_enter(mem.mutex);
+  assert( mem.disallow==0 );
+  nReserve = ROUND8(nByte);
+  totalSize = nReserve + sizeof(*pHdr) + sizeof(int) +
+               mem.nBacktrace*sizeof(void*) + mem.nTitle;
+  p = malloc(totalSize);
+  if( p ){
+    z = p;
+    pBt = (void**)&z[mem.nTitle];
+    pHdr = (struct MemBlockHdr*)&pBt[mem.nBacktrace];
+    pHdr->pNext = 0;
+    pHdr->pPrev = mem.pLast;
+    if( mem.pLast ){
+      mem.pLast->pNext = pHdr;
+    }else{
+      mem.pFirst = pHdr;
+    }
+    mem.pLast = pHdr;
+    pHdr->iForeGuard = FOREGUARD;
+    pHdr->eType = MEMTYPE_HEAP;
+    pHdr->nBacktraceSlots = mem.nBacktrace;
+    pHdr->nTitle = mem.nTitle;
+    if( mem.nBacktrace ){
+      void *aAddr[40];
+      pHdr->nBacktrace = backtrace(aAddr, mem.nBacktrace+1)-1;
+      memcpy(pBt, &aAddr[1], pHdr->nBacktrace*sizeof(void*));
+      assert(pBt[0]);
+      if( mem.xBacktrace ){
+        mem.xBacktrace(nByte, pHdr->nBacktrace-1, &aAddr[1]);
+      }
+    }else{
+      pHdr->nBacktrace = 0;
+    }
+    if( mem.nTitle ){
+      memcpy(z, mem.zTitle, mem.nTitle);
+    }
+    pHdr->iSize = nByte;
+    adjustStats(nByte, +1);
+    pInt = (int*)&pHdr[1];
+    pInt[nReserve/sizeof(int)] = REARGUARD;
+    randomFill((char*)pInt, nByte);
+    memset(((char*)pInt)+nByte, 0x65, nReserve-nByte);
+    p = (void*)pInt;
+  }
+  sqlite3_mutex_leave(mem.mutex);
+  return p; 
+}
+
+/*
+** Free memory.
+*/
+static void sqlite3MemFree(void *pPrior){
+  struct MemBlockHdr *pHdr;
+  void **pBt;
+  char *z;
+  assert( sqlite3GlobalConfig.bMemstat || sqlite3GlobalConfig.bCoreMutex==0 
+       || mem.mutex!=0 );
+  pHdr = sqlite3MemsysGetHeader(pPrior);
+  pBt = (void**)pHdr;
+  pBt -= pHdr->nBacktraceSlots;
+  sqlite3_mutex_enter(mem.mutex);
+  if( pHdr->pPrev ){
+    assert( pHdr->pPrev->pNext==pHdr );
+    pHdr->pPrev->pNext = pHdr->pNext;
+  }else{
+    assert( mem.pFirst==pHdr );
+    mem.pFirst = pHdr->pNext;
+  }
+  if( pHdr->pNext ){
+    assert( pHdr->pNext->pPrev==pHdr );
+    pHdr->pNext->pPrev = pHdr->pPrev;
+  }else{
+    assert( mem.pLast==pHdr );
+    mem.pLast = pHdr->pPrev;
+  }
+  z = (char*)pBt;
+  z -= pHdr->nTitle;
+  adjustStats(pHdr->iSize, -1);
+  randomFill(z, sizeof(void*)*pHdr->nBacktraceSlots + sizeof(*pHdr) +
+                pHdr->iSize + sizeof(int) + pHdr->nTitle);
+  free(z);
+  sqlite3_mutex_leave(mem.mutex);  
+}
+
+/*
+** Change the size of an existing memory allocation.
+**
+** For this debugging implementation, we *always* make a copy of the
+** allocation into a new place in memory.  In this way, if the 
+** higher level code is using pointer to the old allocation, it is 
+** much more likely to break and we are much more liking to find
+** the error.
+*/
+static void *sqlite3MemRealloc(void *pPrior, int nByte){
+  struct MemBlockHdr *pOldHdr;
+  void *pNew;
+  assert( mem.disallow==0 );
+  assert( (nByte & 7)==0 );     /* EV: R-46199-30249 */
+  pOldHdr = sqlite3MemsysGetHeader(pPrior);
+  pNew = sqlite3MemMalloc(nByte);
+  if( pNew ){
+    memcpy(pNew, pPrior, nByte<pOldHdr->iSize ? nByte : pOldHdr->iSize);
+    if( nByte>pOldHdr->iSize ){
+      randomFill(&((char*)pNew)[pOldHdr->iSize], nByte - pOldHdr->iSize);
+    }
+    sqlite3MemFree(pPrior);
+  }
+  return pNew;
+}
+
+/*
+** Populate the low-level memory allocation function pointers in
+** sqlite3GlobalConfig.m with pointers to the routines in this file.
+*/
+SQLITE_PRIVATE void sqlite3MemSetDefault(void){
+  static const sqlite3_mem_methods defaultMethods = {
+     sqlite3MemMalloc,
+     sqlite3MemFree,
+     sqlite3MemRealloc,
+     sqlite3MemSize,
+     sqlite3MemRoundup,
+     sqlite3MemInit,
+     sqlite3MemShutdown,
+     0
+  };
+  sqlite3_config(SQLITE_CONFIG_MALLOC, &defaultMethods);
+}
+
+/*
+** Set the "type" of an allocation.
+*/
+SQLITE_PRIVATE void sqlite3MemdebugSetType(void *p, u8 eType){
+  if( p && sqlite3GlobalConfig.m.xMalloc==sqlite3MemMalloc ){
+    struct MemBlockHdr *pHdr;
+    pHdr = sqlite3MemsysGetHeader(p);
+    assert( pHdr->iForeGuard==FOREGUARD );
+    pHdr->eType = eType;
+  }
+}
+
+/*
+** Return TRUE if the mask of type in eType matches the type of the
+** allocation p.  Also return true if p==NULL.
+**
+** This routine is designed for use within an assert() statement, to
+** verify the type of an allocation.  For example:
+**
+**     assert( sqlite3MemdebugHasType(p, MEMTYPE_DB) );
+*/
+SQLITE_PRIVATE int sqlite3MemdebugHasType(void *p, u8 eType){
+  int rc = 1;
+  if( p && sqlite3GlobalConfig.m.xMalloc==sqlite3MemMalloc ){
+    struct MemBlockHdr *pHdr;
+    pHdr = sqlite3MemsysGetHeader(p);
+    assert( pHdr->iForeGuard==FOREGUARD );         /* Allocation is valid */
+    if( (pHdr->eType&eType)==0 ){
+      rc = 0;
+    }
+  }
+  return rc;
+}
+
+/*
+** Return TRUE if the mask of type in eType matches no bits of the type of the
+** allocation p.  Also return true if p==NULL.
+**
+** This routine is designed for use within an assert() statement, to
+** verify the type of an allocation.  For example:
+**
+**     assert( sqlite3MemdebugNoType(p, MEMTYPE_DB) );
+*/
+SQLITE_PRIVATE int sqlite3MemdebugNoType(void *p, u8 eType){
+  int rc = 1;
+  if( p && sqlite3GlobalConfig.m.xMalloc==sqlite3MemMalloc ){
+    struct MemBlockHdr *pHdr;
+    pHdr = sqlite3MemsysGetHeader(p);
+    assert( pHdr->iForeGuard==FOREGUARD );         /* Allocation is valid */
+    if( (pHdr->eType&eType)!=0 ){
+      rc = 0;
+    }
+  }
+  return rc;
+}
+
+/*
+** Set the number of backtrace levels kept for each allocation.
+** A value of zero turns off backtracing.  The number is always rounded
+** up to a multiple of 2.
+*/
+SQLITE_PRIVATE void sqlite3MemdebugBacktrace(int depth){
+  if( depth<0 ){ depth = 0; }
+  if( depth>20 ){ depth = 20; }
+  depth = (depth+1)&0xfe;
+  mem.nBacktrace = depth;
+}
+
+SQLITE_PRIVATE void sqlite3MemdebugBacktraceCallback(void (*xBacktrace)(int, int, void **)){
+  mem.xBacktrace = xBacktrace;
+}
+
+/*
+** Set the title string for subsequent allocations.
+*/
+SQLITE_PRIVATE void sqlite3MemdebugSettitle(const char *zTitle){
+  unsigned int n = sqlite3Strlen30(zTitle) + 1;
+  sqlite3_mutex_enter(mem.mutex);
+  if( n>=sizeof(mem.zTitle) ) n = sizeof(mem.zTitle)-1;
+  memcpy(mem.zTitle, zTitle, n);
+  mem.zTitle[n] = 0;
+  mem.nTitle = ROUND8(n);
+  sqlite3_mutex_leave(mem.mutex);
+}
+
+SQLITE_PRIVATE void sqlite3MemdebugSync(){
+  struct MemBlockHdr *pHdr;
+  for(pHdr=mem.pFirst; pHdr; pHdr=pHdr->pNext){
+    void **pBt = (void**)pHdr;
+    pBt -= pHdr->nBacktraceSlots;
+    mem.xBacktrace(pHdr->iSize, pHdr->nBacktrace-1, &pBt[1]);
+  }
+}
+
+/*
+** Open the file indicated and write a log of all unfreed memory 
+** allocations into that log.
+*/
+SQLITE_PRIVATE void sqlite3MemdebugDump(const char *zFilename){
+  FILE *out;
+  struct MemBlockHdr *pHdr;
+  void **pBt;
+  int i;
+  out = fopen(zFilename, "w");
+  if( out==0 ){
+    fprintf(stderr, "** Unable to output memory debug output log: %s **\n",
+                    zFilename);
+    return;
+  }
+  for(pHdr=mem.pFirst; pHdr; pHdr=pHdr->pNext){
+    char *z = (char*)pHdr;
+    z -= pHdr->nBacktraceSlots*sizeof(void*) + pHdr->nTitle;
+    fprintf(out, "**** %lld bytes at %p from %s ****\n", 
+            pHdr->iSize, &pHdr[1], pHdr->nTitle ? z : "???");
+    if( pHdr->nBacktrace ){
+      fflush(out);
+      pBt = (void**)pHdr;
+      pBt -= pHdr->nBacktraceSlots;
+      backtrace_symbols_fd(pBt, pHdr->nBacktrace, fileno(out));
+      fprintf(out, "\n");
+    }
+  }
+  fprintf(out, "COUNTS:\n");
+  for(i=0; i<NCSIZE-1; i++){
+    if( mem.nAlloc[i] ){
+      fprintf(out, "   %5d: %10d %10d %10d\n", 
+            i*8, mem.nAlloc[i], mem.nCurrent[i], mem.mxCurrent[i]);
+    }
+  }
+  if( mem.nAlloc[NCSIZE-1] ){
+    fprintf(out, "   %5d: %10d %10d %10d\n",
+             NCSIZE*8-8, mem.nAlloc[NCSIZE-1],
+             mem.nCurrent[NCSIZE-1], mem.mxCurrent[NCSIZE-1]);
+  }
+  fclose(out);
+}
+
+/*
+** Return the number of times sqlite3MemMalloc() has been called.
+*/
+SQLITE_PRIVATE int sqlite3MemdebugMallocCount(){
+  int i;
+  int nTotal = 0;
+  for(i=0; i<NCSIZE; i++){
+    nTotal += mem.nAlloc[i];
+  }
+  return nTotal;
+}
+
+
+#endif /* SQLITE_MEMDEBUG */
+
+/************** End of mem2.c ************************************************/
+/************** Begin file mem3.c ********************************************/
+/*
+** 2007 October 14
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains the C functions that implement a memory
+** allocation subsystem for use by SQLite. 
+**
+** This version of the memory allocation subsystem omits all
+** use of malloc(). The SQLite user supplies a block of memory
+** before calling sqlite3_initialize() from which allocations
+** are made and returned by the xMalloc() and xRealloc() 
+** implementations. Once sqlite3_initialize() has been called,
+** the amount of memory available to SQLite is fixed and cannot
+** be changed.
+**
+** This version of the memory allocation subsystem is included
+** in the build only if SQLITE_ENABLE_MEMSYS3 is defined.
+*/
+
+/*
+** This version of the memory allocator is only built into the library
+** SQLITE_ENABLE_MEMSYS3 is defined. Defining this symbol does not
+** mean that the library will use a memory-pool by default, just that
+** it is available. The mempool allocator is activated by calling
+** sqlite3_config().
+*/
+#ifdef SQLITE_ENABLE_MEMSYS3
+
+/*
+** Maximum size (in Mem3Blocks) of a "small" chunk.
+*/
+#define MX_SMALL 10
+
+
+/*
+** Number of freelist hash slots
+*/
+#define N_HASH  61
+
+/*
+** A memory allocation (also called a "chunk") consists of two or 
+** more blocks where each block is 8 bytes.  The first 8 bytes are 
+** a header that is not returned to the user.
+**
+** A chunk is two or more blocks that is either checked out or
+** free.  The first block has format u.hdr.  u.hdr.size4x is 4 times the
+** size of the allocation in blocks if the allocation is free.
+** The u.hdr.size4x&1 bit is true if the chunk is checked out and
+** false if the chunk is on the freelist.  The u.hdr.size4x&2 bit
+** is true if the previous chunk is checked out and false if the
+** previous chunk is free.  The u.hdr.prevSize field is the size of
+** the previous chunk in blocks if the previous chunk is on the
+** freelist. If the previous chunk is checked out, then
+** u.hdr.prevSize can be part of the data for that chunk and should
+** not be read or written.
+**
+** We often identify a chunk by its index in mem3.aPool[].  When
+** this is done, the chunk index refers to the second block of
+** the chunk.  In this way, the first chunk has an index of 1.
+** A chunk index of 0 means "no such chunk" and is the equivalent
+** of a NULL pointer.
+**
+** The second block of free chunks is of the form u.list.  The
+** two fields form a double-linked list of chunks of related sizes.
+** Pointers to the head of the list are stored in mem3.aiSmall[] 
+** for smaller chunks and mem3.aiHash[] for larger chunks.
+**
+** The second block of a chunk is user data if the chunk is checked 
+** out.  If a chunk is checked out, the user data may extend into
+** the u.hdr.prevSize value of the following chunk.
+*/
+typedef struct Mem3Block Mem3Block;
+struct Mem3Block {
+  union {
+    struct {
+      u32 prevSize;   /* Size of previous chunk in Mem3Block elements */
+      u32 size4x;     /* 4x the size of current chunk in Mem3Block elements */
+    } hdr;
+    struct {
+      u32 next;       /* Index in mem3.aPool[] of next free chunk */
+      u32 prev;       /* Index in mem3.aPool[] of previous free chunk */
+    } list;
+  } u;
+};
+
+/*
+** All of the static variables used by this module are collected
+** into a single structure named "mem3".  This is to keep the
+** static variables organized and to reduce namespace pollution
+** when this module is combined with other in the amalgamation.
+*/
+static SQLITE_WSD struct Mem3Global {
+  /*
+  ** Memory available for allocation. nPool is the size of the array
+  ** (in Mem3Blocks) pointed to by aPool less 2.
+  */
+  u32 nPool;
+  Mem3Block *aPool;
+
+  /*
+  ** True if we are evaluating an out-of-memory callback.
+  */
+  int alarmBusy;
+  
+  /*
+  ** Mutex to control access to the memory allocation subsystem.
+  */
+  sqlite3_mutex *mutex;
+  
+  /*
+  ** The minimum amount of free space that we have seen.
+  */
+  u32 mnMaster;
+
+  /*
+  ** iMaster is the index of the master chunk.  Most new allocations
+  ** occur off of this chunk.  szMaster is the size (in Mem3Blocks)
+  ** of the current master.  iMaster is 0 if there is not master chunk.
+  ** The master chunk is not in either the aiHash[] or aiSmall[].
+  */
+  u32 iMaster;
+  u32 szMaster;
+
+  /*
+  ** Array of lists of free blocks according to the block size 
+  ** for smaller chunks, or a hash on the block size for larger
+  ** chunks.
+  */
+  u32 aiSmall[MX_SMALL-1];   /* For sizes 2 through MX_SMALL, inclusive */
+  u32 aiHash[N_HASH];        /* For sizes MX_SMALL+1 and larger */
+} mem3 = { 97535575 };
+
+#define mem3 GLOBAL(struct Mem3Global, mem3)
+
+/*
+** Unlink the chunk at mem3.aPool[i] from list it is currently
+** on.  *pRoot is the list that i is a member of.
+*/
+static void memsys3UnlinkFromList(u32 i, u32 *pRoot){
+  u32 next = mem3.aPool[i].u.list.next;
+  u32 prev = mem3.aPool[i].u.list.prev;
+  assert( sqlite3_mutex_held(mem3.mutex) );
+  if( prev==0 ){
+    *pRoot = next;
+  }else{
+    mem3.aPool[prev].u.list.next = next;
+  }
+  if( next ){
+    mem3.aPool[next].u.list.prev = prev;
+  }
+  mem3.aPool[i].u.list.next = 0;
+  mem3.aPool[i].u.list.prev = 0;
+}
+
+/*
+** Unlink the chunk at index i from 
+** whatever list is currently a member of.
+*/
+static void memsys3Unlink(u32 i){
+  u32 size, hash;
+  assert( sqlite3_mutex_held(mem3.mutex) );
+  assert( (mem3.aPool[i-1].u.hdr.size4x & 1)==0 );
+  assert( i>=1 );
+  size = mem3.aPool[i-1].u.hdr.size4x/4;
+  assert( size==mem3.aPool[i+size-1].u.hdr.prevSize );
+  assert( size>=2 );
+  if( size <= MX_SMALL ){
+    memsys3UnlinkFromList(i, &mem3.aiSmall[size-2]);
+  }else{
+    hash = size % N_HASH;
+    memsys3UnlinkFromList(i, &mem3.aiHash[hash]);
+  }
+}
+
+/*
+** Link the chunk at mem3.aPool[i] so that is on the list rooted
+** at *pRoot.
+*/
+static void memsys3LinkIntoList(u32 i, u32 *pRoot){
+  assert( sqlite3_mutex_held(mem3.mutex) );
+  mem3.aPool[i].u.list.next = *pRoot;
+  mem3.aPool[i].u.list.prev = 0;
+  if( *pRoot ){
+    mem3.aPool[*pRoot].u.list.prev = i;
+  }
+  *pRoot = i;
+}
+
+/*
+** Link the chunk at index i into either the appropriate
+** small chunk list, or into the large chunk hash table.
+*/
+static void memsys3Link(u32 i){
+  u32 size, hash;
+  assert( sqlite3_mutex_held(mem3.mutex) );
+  assert( i>=1 );
+  assert( (mem3.aPool[i-1].u.hdr.size4x & 1)==0 );
+  size = mem3.aPool[i-1].u.hdr.size4x/4;
+  assert( size==mem3.aPool[i+size-1].u.hdr.prevSize );
+  assert( size>=2 );
+  if( size <= MX_SMALL ){
+    memsys3LinkIntoList(i, &mem3.aiSmall[size-2]);
+  }else{
+    hash = size % N_HASH;
+    memsys3LinkIntoList(i, &mem3.aiHash[hash]);
+  }
+}
+
+/*
+** If the STATIC_MEM mutex is not already held, obtain it now. The mutex
+** will already be held (obtained by code in malloc.c) if
+** sqlite3GlobalConfig.bMemStat is true.
+*/
+static void memsys3Enter(void){
+  if( sqlite3GlobalConfig.bMemstat==0 && mem3.mutex==0 ){
+    mem3.mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM);
+  }
+  sqlite3_mutex_enter(mem3.mutex);
+}
+static void memsys3Leave(void){
+  sqlite3_mutex_leave(mem3.mutex);
+}
+
+/*
+** Called when we are unable to satisfy an allocation of nBytes.
+*/
+static void memsys3OutOfMemory(int nByte){
+  if( !mem3.alarmBusy ){
+    mem3.alarmBusy = 1;
+    assert( sqlite3_mutex_held(mem3.mutex) );
+    sqlite3_mutex_leave(mem3.mutex);
+    sqlite3_release_memory(nByte);
+    sqlite3_mutex_enter(mem3.mutex);
+    mem3.alarmBusy = 0;
+  }
+}
+
+
+/*
+** Chunk i is a free chunk that has been unlinked.  Adjust its 
+** size parameters for check-out and return a pointer to the 
+** user portion of the chunk.
+*/
+static void *memsys3Checkout(u32 i, u32 nBlock){
+  u32 x;
+  assert( sqlite3_mutex_held(mem3.mutex) );
+  assert( i>=1 );
+  assert( mem3.aPool[i-1].u.hdr.size4x/4==nBlock );
+  assert( mem3.aPool[i+nBlock-1].u.hdr.prevSize==nBlock );
+  x = mem3.aPool[i-1].u.hdr.size4x;
+  mem3.aPool[i-1].u.hdr.size4x = nBlock*4 | 1 | (x&2);
+  mem3.aPool[i+nBlock-1].u.hdr.prevSize = nBlock;
+  mem3.aPool[i+nBlock-1].u.hdr.size4x |= 2;
+  return &mem3.aPool[i];
+}
+
+/*
+** Carve a piece off of the end of the mem3.iMaster free chunk.
+** Return a pointer to the new allocation.  Or, if the master chunk
+** is not large enough, return 0.
+*/
+static void *memsys3FromMaster(u32 nBlock){
+  assert( sqlite3_mutex_held(mem3.mutex) );
+  assert( mem3.szMaster>=nBlock );
+  if( nBlock>=mem3.szMaster-1 ){
+    /* Use the entire master */
+    void *p = memsys3Checkout(mem3.iMaster, mem3.szMaster);
+    mem3.iMaster = 0;
+    mem3.szMaster = 0;
+    mem3.mnMaster = 0;
+    return p;
+  }else{
+    /* Split the master block.  Return the tail. */
+    u32 newi, x;
+    newi = mem3.iMaster + mem3.szMaster - nBlock;
+    assert( newi > mem3.iMaster+1 );
+    mem3.aPool[mem3.iMaster+mem3.szMaster-1].u.hdr.prevSize = nBlock;
+    mem3.aPool[mem3.iMaster+mem3.szMaster-1].u.hdr.size4x |= 2;
+    mem3.aPool[newi-1].u.hdr.size4x = nBlock*4 + 1;
+    mem3.szMaster -= nBlock;
+    mem3.aPool[newi-1].u.hdr.prevSize = mem3.szMaster;
+    x = mem3.aPool[mem3.iMaster-1].u.hdr.size4x & 2;
+    mem3.aPool[mem3.iMaster-1].u.hdr.size4x = mem3.szMaster*4 | x;
+    if( mem3.szMaster < mem3.mnMaster ){
+      mem3.mnMaster = mem3.szMaster;
+    }
+    return (void*)&mem3.aPool[newi];
+  }
+}
+
+/*
+** *pRoot is the head of a list of free chunks of the same size
+** or same size hash.  In other words, *pRoot is an entry in either
+** mem3.aiSmall[] or mem3.aiHash[].  
+**
+** This routine examines all entries on the given list and tries
+** to coalesce each entries with adjacent free chunks.  
+**
+** If it sees a chunk that is larger than mem3.iMaster, it replaces 
+** the current mem3.iMaster with the new larger chunk.  In order for
+** this mem3.iMaster replacement to work, the master chunk must be
+** linked into the hash tables.  That is not the normal state of
+** affairs, of course.  The calling routine must link the master
+** chunk before invoking this routine, then must unlink the (possibly
+** changed) master chunk once this routine has finished.
+*/
+static void memsys3Merge(u32 *pRoot){
+  u32 iNext, prev, size, i, x;
+
+  assert( sqlite3_mutex_held(mem3.mutex) );
+  for(i=*pRoot; i>0; i=iNext){
+    iNext = mem3.aPool[i].u.list.next;
+    size = mem3.aPool[i-1].u.hdr.size4x;
+    assert( (size&1)==0 );
+    if( (size&2)==0 ){
+      memsys3UnlinkFromList(i, pRoot);
+      assert( i > mem3.aPool[i-1].u.hdr.prevSize );
+      prev = i - mem3.aPool[i-1].u.hdr.prevSize;
+      if( prev==iNext ){
+        iNext = mem3.aPool[prev].u.list.next;
+      }
+      memsys3Unlink(prev);
+      size = i + size/4 - prev;
+      x = mem3.aPool[prev-1].u.hdr.size4x & 2;
+      mem3.aPool[prev-1].u.hdr.size4x = size*4 | x;
+      mem3.aPool[prev+size-1].u.hdr.prevSize = size;
+      memsys3Link(prev);
+      i = prev;
+    }else{
+      size /= 4;
+    }
+    if( size>mem3.szMaster ){
+      mem3.iMaster = i;
+      mem3.szMaster = size;
+    }
+  }
+}
+
+/*
+** Return a block of memory of at least nBytes in size.
+** Return NULL if unable.
+**
+** This function assumes that the necessary mutexes, if any, are
+** already held by the caller. Hence "Unsafe".
+*/
+static void *memsys3MallocUnsafe(int nByte){
+  u32 i;
+  u32 nBlock;
+  u32 toFree;
+
+  assert( sqlite3_mutex_held(mem3.mutex) );
+  assert( sizeof(Mem3Block)==8 );
+  if( nByte<=12 ){
+    nBlock = 2;
+  }else{
+    nBlock = (nByte + 11)/8;
+  }
+  assert( nBlock>=2 );
+
+  /* STEP 1:
+  ** Look for an entry of the correct size in either the small
+  ** chunk table or in the large chunk hash table.  This is
+  ** successful most of the time (about 9 times out of 10).
+  */
+  if( nBlock <= MX_SMALL ){
+    i = mem3.aiSmall[nBlock-2];
+    if( i>0 ){
+      memsys3UnlinkFromList(i, &mem3.aiSmall[nBlock-2]);
+      return memsys3Checkout(i, nBlock);
+    }
+  }else{
+    int hash = nBlock % N_HASH;
+    for(i=mem3.aiHash[hash]; i>0; i=mem3.aPool[i].u.list.next){
+      if( mem3.aPool[i-1].u.hdr.size4x/4==nBlock ){
+        memsys3UnlinkFromList(i, &mem3.aiHash[hash]);
+        return memsys3Checkout(i, nBlock);
+      }
+    }
+  }
+
+  /* STEP 2:
+  ** Try to satisfy the allocation by carving a piece off of the end
+  ** of the master chunk.  This step usually works if step 1 fails.
+  */
+  if( mem3.szMaster>=nBlock ){
+    return memsys3FromMaster(nBlock);
+  }
+
+
+  /* STEP 3:  
+  ** Loop through the entire memory pool.  Coalesce adjacent free
+  ** chunks.  Recompute the master chunk as the largest free chunk.
+  ** Then try again to satisfy the allocation by carving a piece off
+  ** of the end of the master chunk.  This step happens very
+  ** rarely (we hope!)
+  */
+  for(toFree=nBlock*16; toFree<(mem3.nPool*16); toFree *= 2){
+    memsys3OutOfMemory(toFree);
+    if( mem3.iMaster ){
+      memsys3Link(mem3.iMaster);
+      mem3.iMaster = 0;
+      mem3.szMaster = 0;
+    }
+    for(i=0; i<N_HASH; i++){
+      memsys3Merge(&mem3.aiHash[i]);
+    }
+    for(i=0; i<MX_SMALL-1; i++){
+      memsys3Merge(&mem3.aiSmall[i]);
+    }
+    if( mem3.szMaster ){
+      memsys3Unlink(mem3.iMaster);
+      if( mem3.szMaster>=nBlock ){
+        return memsys3FromMaster(nBlock);
+      }
+    }
+  }
+
+  /* If none of the above worked, then we fail. */
+  return 0;
+}
+
+/*
+** Free an outstanding memory allocation.
+**
+** This function assumes that the necessary mutexes, if any, are
+** already held by the caller. Hence "Unsafe".
+*/
+void memsys3FreeUnsafe(void *pOld){
+  Mem3Block *p = (Mem3Block*)pOld;
+  int i;
+  u32 size, x;
+  assert( sqlite3_mutex_held(mem3.mutex) );
+  assert( p>mem3.aPool && p<&mem3.aPool[mem3.nPool] );
+  i = p - mem3.aPool;
+  assert( (mem3.aPool[i-1].u.hdr.size4x&1)==1 );
+  size = mem3.aPool[i-1].u.hdr.size4x/4;
+  assert( i+size<=mem3.nPool+1 );
+  mem3.aPool[i-1].u.hdr.size4x &= ~1;
+  mem3.aPool[i+size-1].u.hdr.prevSize = size;
+  mem3.aPool[i+size-1].u.hdr.size4x &= ~2;
+  memsys3Link(i);
+
+  /* Try to expand the master using the newly freed chunk */
+  if( mem3.iMaster ){
+    while( (mem3.aPool[mem3.iMaster-1].u.hdr.size4x&2)==0 ){
+      size = mem3.aPool[mem3.iMaster-1].u.hdr.prevSize;
+      mem3.iMaster -= size;
+      mem3.szMaster += size;
+      memsys3Unlink(mem3.iMaster);
+      x = mem3.aPool[mem3.iMaster-1].u.hdr.size4x & 2;
+      mem3.aPool[mem3.iMaster-1].u.hdr.size4x = mem3.szMaster*4 | x;
+      mem3.aPool[mem3.iMaster+mem3.szMaster-1].u.hdr.prevSize = mem3.szMaster;
+    }
+    x = mem3.aPool[mem3.iMaster-1].u.hdr.size4x & 2;
+    while( (mem3.aPool[mem3.iMaster+mem3.szMaster-1].u.hdr.size4x&1)==0 ){
+      memsys3Unlink(mem3.iMaster+mem3.szMaster);
+      mem3.szMaster += mem3.aPool[mem3.iMaster+mem3.szMaster-1].u.hdr.size4x/4;
+      mem3.aPool[mem3.iMaster-1].u.hdr.size4x = mem3.szMaster*4 | x;
+      mem3.aPool[mem3.iMaster+mem3.szMaster-1].u.hdr.prevSize = mem3.szMaster;
+    }
+  }
+}
+
+/*
+** Return the size of an outstanding allocation, in bytes.  The
+** size returned omits the 8-byte header overhead.  This only
+** works for chunks that are currently checked out.
+*/
+static int memsys3Size(void *p){
+  Mem3Block *pBlock;
+  if( p==0 ) return 0;
+  pBlock = (Mem3Block*)p;
+  assert( (pBlock[-1].u.hdr.size4x&1)!=0 );
+  return (pBlock[-1].u.hdr.size4x&~3)*2 - 4;
+}
+
+/*
+** Round up a request size to the next valid allocation size.
+*/
+static int memsys3Roundup(int n){
+  if( n<=12 ){
+    return 12;
+  }else{
+    return ((n+11)&~7) - 4;
+  }
+}
+
+/*
+** Allocate nBytes of memory.
+*/
+static void *memsys3Malloc(int nBytes){
+  sqlite3_int64 *p;
+  assert( nBytes>0 );          /* malloc.c filters out 0 byte requests */
+  memsys3Enter();
+  p = memsys3MallocUnsafe(nBytes);
+  memsys3Leave();
+  return (void*)p; 
+}
+
+/*
+** Free memory.
+*/
+void memsys3Free(void *pPrior){
+  assert( pPrior );
+  memsys3Enter();
+  memsys3FreeUnsafe(pPrior);
+  memsys3Leave();
+}
+
+/*
+** Change the size of an existing memory allocation
+*/
+void *memsys3Realloc(void *pPrior, int nBytes){
+  int nOld;
+  void *p;
+  if( pPrior==0 ){
+    return sqlite3_malloc(nBytes);
+  }
+  if( nBytes<=0 ){
+    sqlite3_free(pPrior);
+    return 0;
+  }
+  nOld = memsys3Size(pPrior);
+  if( nBytes<=nOld && nBytes>=nOld-128 ){
+    return pPrior;
+  }
+  memsys3Enter();
+  p = memsys3MallocUnsafe(nBytes);
+  if( p ){
+    if( nOld<nBytes ){
+      memcpy(p, pPrior, nOld);
+    }else{
+      memcpy(p, pPrior, nBytes);
+    }
+    memsys3FreeUnsafe(pPrior);
+  }
+  memsys3Leave();
+  return p;
+}
+
+/*
+** Initialize this module.
+*/
+static int memsys3Init(void *NotUsed){
+  UNUSED_PARAMETER(NotUsed);
+  if( !sqlite3GlobalConfig.pHeap ){
+    return SQLITE_ERROR;
+  }
+
+  /* Store a pointer to the memory block in global structure mem3. */
+  assert( sizeof(Mem3Block)==8 );
+  mem3.aPool = (Mem3Block *)sqlite3GlobalConfig.pHeap;
+  mem3.nPool = (sqlite3GlobalConfig.nHeap / sizeof(Mem3Block)) - 2;
+
+  /* Initialize the master block. */
+  mem3.szMaster = mem3.nPool;
+  mem3.mnMaster = mem3.szMaster;
+  mem3.iMaster = 1;
+  mem3.aPool[0].u.hdr.size4x = (mem3.szMaster<<2) + 2;
+  mem3.aPool[mem3.nPool].u.hdr.prevSize = mem3.nPool;
+  mem3.aPool[mem3.nPool].u.hdr.size4x = 1;
+
+  return SQLITE_OK;
+}
+
+/*
+** Deinitialize this module.
+*/
+static void memsys3Shutdown(void *NotUsed){
+  UNUSED_PARAMETER(NotUsed);
+  mem3.mutex = 0;
+  return;
+}
+
+
+
+/*
+** Open the file indicated and write a log of all unfreed memory 
+** allocations into that log.
+*/
+SQLITE_PRIVATE void sqlite3Memsys3Dump(const char *zFilename){
+#ifdef SQLITE_DEBUG
+  FILE *out;
+  u32 i, j;
+  u32 size;
+  if( zFilename==0 || zFilename[0]==0 ){
+    out = stdout;
+  }else{
+    out = fopen(zFilename, "w");
+    if( out==0 ){
+      fprintf(stderr, "** Unable to output memory debug output log: %s **\n",
+                      zFilename);
+      return;
+    }
+  }
+  memsys3Enter();
+  fprintf(out, "CHUNKS:\n");
+  for(i=1; i<=mem3.nPool; i+=size/4){
+    size = mem3.aPool[i-1].u.hdr.size4x;
+    if( size/4<=1 ){
+      fprintf(out, "%p size error\n", &mem3.aPool[i]);
+      assert( 0 );
+      break;
+    }
+    if( (size&1)==0 && mem3.aPool[i+size/4-1].u.hdr.prevSize!=size/4 ){
+      fprintf(out, "%p tail size does not match\n", &mem3.aPool[i]);
+      assert( 0 );
+      break;
+    }
+    if( ((mem3.aPool[i+size/4-1].u.hdr.size4x&2)>>1)!=(size&1) ){
+      fprintf(out, "%p tail checkout bit is incorrect\n", &mem3.aPool[i]);
+      assert( 0 );
+      break;
+    }
+    if( size&1 ){
+      fprintf(out, "%p %6d bytes checked out\n", &mem3.aPool[i], (size/4)*8-8);
+    }else{
+      fprintf(out, "%p %6d bytes free%s\n", &mem3.aPool[i], (size/4)*8-8,
+                  i==mem3.iMaster ? " **master**" : "");
+    }
+  }
+  for(i=0; i<MX_SMALL-1; i++){
+    if( mem3.aiSmall[i]==0 ) continue;
+    fprintf(out, "small(%2d):", i);
+    for(j = mem3.aiSmall[i]; j>0; j=mem3.aPool[j].u.list.next){
+      fprintf(out, " %p(%d)", &mem3.aPool[j],
+              (mem3.aPool[j-1].u.hdr.size4x/4)*8-8);
+    }
+    fprintf(out, "\n"); 
+  }
+  for(i=0; i<N_HASH; i++){
+    if( mem3.aiHash[i]==0 ) continue;
+    fprintf(out, "hash(%2d):", i);
+    for(j = mem3.aiHash[i]; j>0; j=mem3.aPool[j].u.list.next){
+      fprintf(out, " %p(%d)", &mem3.aPool[j],
+              (mem3.aPool[j-1].u.hdr.size4x/4)*8-8);
+    }
+    fprintf(out, "\n"); 
+  }
+  fprintf(out, "master=%d\n", mem3.iMaster);
+  fprintf(out, "nowUsed=%d\n", mem3.nPool*8 - mem3.szMaster*8);
+  fprintf(out, "mxUsed=%d\n", mem3.nPool*8 - mem3.mnMaster*8);
+  sqlite3_mutex_leave(mem3.mutex);
+  if( out==stdout ){
+    fflush(stdout);
+  }else{
+    fclose(out);
+  }
+#else
+  UNUSED_PARAMETER(zFilename);
+#endif
+}
+
+/*
+** This routine is the only routine in this file with external 
+** linkage.
+**
+** Populate the low-level memory allocation function pointers in
+** sqlite3GlobalConfig.m with pointers to the routines in this file. The
+** arguments specify the block of memory to manage.
+**
+** This routine is only called by sqlite3_config(), and therefore
+** is not required to be threadsafe (it is not).
+*/
+SQLITE_PRIVATE const sqlite3_mem_methods *sqlite3MemGetMemsys3(void){
+  static const sqlite3_mem_methods mempoolMethods = {
+     memsys3Malloc,
+     memsys3Free,
+     memsys3Realloc,
+     memsys3Size,
+     memsys3Roundup,
+     memsys3Init,
+     memsys3Shutdown,
+     0
+  };
+  return &mempoolMethods;
+}
+
+#endif /* SQLITE_ENABLE_MEMSYS3 */
+
+/************** End of mem3.c ************************************************/
+/************** Begin file mem5.c ********************************************/
+/*
+** 2007 October 14
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains the C functions that implement a memory
+** allocation subsystem for use by SQLite. 
+**
+** This version of the memory allocation subsystem omits all
+** use of malloc(). The application gives SQLite a block of memory
+** before calling sqlite3_initialize() from which allocations
+** are made and returned by the xMalloc() and xRealloc() 
+** implementations. Once sqlite3_initialize() has been called,
+** the amount of memory available to SQLite is fixed and cannot
+** be changed.
+**
+** This version of the memory allocation subsystem is included
+** in the build only if SQLITE_ENABLE_MEMSYS5 is defined.
+**
+** This memory allocator uses the following algorithm:
+**
+**   1.  All memory allocations sizes are rounded up to a power of 2.
+**
+**   2.  If two adjacent free blocks are the halves of a larger block,
+**       then the two blocks are coalesed into the single larger block.
+**
+**   3.  New memory is allocated from the first available free block.
+**
+** This algorithm is described in: J. M. Robson. "Bounds for Some Functions
+** Concerning Dynamic Storage Allocation". Journal of the Association for
+** Computing Machinery, Volume 21, Number 8, July 1974, pages 491-499.
+** 
+** Let n be the size of the largest allocation divided by the minimum
+** allocation size (after rounding all sizes up to a power of 2.)  Let M
+** be the maximum amount of memory ever outstanding at one time.  Let
+** N be the total amount of memory available for allocation.  Robson
+** proved that this memory allocator will never breakdown due to 
+** fragmentation as long as the following constraint holds:
+**
+**      N >=  M*(1 + log2(n)/2) - n + 1
+**
+** The sqlite3_status() logic tracks the maximum values of n and M so
+** that an application can, at any time, verify this constraint.
+*/
+
+/*
+** This version of the memory allocator is used only when 
+** SQLITE_ENABLE_MEMSYS5 is defined.
+*/
+#ifdef SQLITE_ENABLE_MEMSYS5
+
+/*
+** A minimum allocation is an instance of the following structure.
+** Larger allocations are an array of these structures where the
+** size of the array is a power of 2.
+**
+** The size of this object must be a power of two.  That fact is
+** verified in memsys5Init().
+*/
+typedef struct Mem5Link Mem5Link;
+struct Mem5Link {
+  int next;       /* Index of next free chunk */
+  int prev;       /* Index of previous free chunk */
+};
+
+/*
+** Maximum size of any allocation is ((1<<LOGMAX)*mem5.szAtom). Since
+** mem5.szAtom is always at least 8 and 32-bit integers are used,
+** it is not actually possible to reach this limit.
+*/
+#define LOGMAX 30
+
+/*
+** Masks used for mem5.aCtrl[] elements.
+*/
+#define CTRL_LOGSIZE  0x1f    /* Log2 Size of this block */
+#define CTRL_FREE     0x20    /* True if not checked out */
+
+/*
+** All of the static variables used by this module are collected
+** into a single structure named "mem5".  This is to keep the
+** static variables organized and to reduce namespace pollution
+** when this module is combined with other in the amalgamation.
+*/
+static SQLITE_WSD struct Mem5Global {
+  /*
+  ** Memory available for allocation
+  */
+  int szAtom;      /* Smallest possible allocation in bytes */
+  int nBlock;      /* Number of szAtom sized blocks in zPool */
+  u8 *zPool;       /* Memory available to be allocated */
+  
+  /*
+  ** Mutex to control access to the memory allocation subsystem.
+  */
+  sqlite3_mutex *mutex;
+
+  /*
+  ** Performance statistics
+  */
+  u64 nAlloc;         /* Total number of calls to malloc */
+  u64 totalAlloc;     /* Total of all malloc calls - includes internal frag */
+  u64 totalExcess;    /* Total internal fragmentation */
+  u32 currentOut;     /* Current checkout, including internal fragmentation */
+  u32 currentCount;   /* Current number of distinct checkouts */
+  u32 maxOut;         /* Maximum instantaneous currentOut */
+  u32 maxCount;       /* Maximum instantaneous currentCount */
+  u32 maxRequest;     /* Largest allocation (exclusive of internal frag) */
+  
+  /*
+  ** Lists of free blocks.  aiFreelist[0] is a list of free blocks of
+  ** size mem5.szAtom.  aiFreelist[1] holds blocks of size szAtom*2.
+  ** and so forth.
+  */
+  int aiFreelist[LOGMAX+1];
+
+  /*
+  ** Space for tracking which blocks are checked out and the size
+  ** of each block.  One byte per block.
+  */
+  u8 *aCtrl;
+
+} mem5;
+
+/*
+** Access the static variable through a macro for SQLITE_OMIT_WSD
+*/
+#define mem5 GLOBAL(struct Mem5Global, mem5)
+
+/*
+** Assuming mem5.zPool is divided up into an array of Mem5Link
+** structures, return a pointer to the idx-th such lik.
+*/
+#define MEM5LINK(idx) ((Mem5Link *)(&mem5.zPool[(idx)*mem5.szAtom]))
+
+/*
+** Unlink the chunk at mem5.aPool[i] from list it is currently
+** on.  It should be found on mem5.aiFreelist[iLogsize].
+*/
+static void memsys5Unlink(int i, int iLogsize){
+  int next, prev;
+  assert( i>=0 && i<mem5.nBlock );
+  assert( iLogsize>=0 && iLogsize<=LOGMAX );
+  assert( (mem5.aCtrl[i] & CTRL_LOGSIZE)==iLogsize );
+
+  next = MEM5LINK(i)->next;
+  prev = MEM5LINK(i)->prev;
+  if( prev<0 ){
+    mem5.aiFreelist[iLogsize] = next;
+  }else{
+    MEM5LINK(prev)->next = next;
+  }
+  if( next>=0 ){
+    MEM5LINK(next)->prev = prev;
+  }
+}
+
+/*
+** Link the chunk at mem5.aPool[i] so that is on the iLogsize
+** free list.
+*/
+static void memsys5Link(int i, int iLogsize){
+  int x;
+  assert( sqlite3_mutex_held(mem5.mutex) );
+  assert( i>=0 && i<mem5.nBlock );
+  assert( iLogsize>=0 && iLogsize<=LOGMAX );
+  assert( (mem5.aCtrl[i] & CTRL_LOGSIZE)==iLogsize );
+
+  x = MEM5LINK(i)->next = mem5.aiFreelist[iLogsize];
+  MEM5LINK(i)->prev = -1;
+  if( x>=0 ){
+    assert( x<mem5.nBlock );
+    MEM5LINK(x)->prev = i;
+  }
+  mem5.aiFreelist[iLogsize] = i;
+}
+
+/*
+** If the STATIC_MEM mutex is not already held, obtain it now. The mutex
+** will already be held (obtained by code in malloc.c) if
+** sqlite3GlobalConfig.bMemStat is true.
+*/
+static void memsys5Enter(void){
+  sqlite3_mutex_enter(mem5.mutex);
+}
+static void memsys5Leave(void){
+  sqlite3_mutex_leave(mem5.mutex);
+}
+
+/*
+** Return the size of an outstanding allocation, in bytes.  The
+** size returned omits the 8-byte header overhead.  This only
+** works for chunks that are currently checked out.
+*/
+static int memsys5Size(void *p){
+  int iSize = 0;
+  if( p ){
+    int i = ((u8 *)p-mem5.zPool)/mem5.szAtom;
+    assert( i>=0 && i<mem5.nBlock );
+    iSize = mem5.szAtom * (1 << (mem5.aCtrl[i]&CTRL_LOGSIZE));
+  }
+  return iSize;
+}
+
+/*
+** Find the first entry on the freelist iLogsize.  Unlink that
+** entry and return its index. 
+*/
+static int memsys5UnlinkFirst(int iLogsize){
+  int i;
+  int iFirst;
+
+  assert( iLogsize>=0 && iLogsize<=LOGMAX );
+  i = iFirst = mem5.aiFreelist[iLogsize];
+  assert( iFirst>=0 );
+  while( i>0 ){
+    if( i<iFirst ) iFirst = i;
+    i = MEM5LINK(i)->next;
+  }
+  memsys5Unlink(iFirst, iLogsize);
+  return iFirst;
+}
+
+/*
+** Return a block of memory of at least nBytes in size.
+** Return NULL if unable.  Return NULL if nBytes==0.
+**
+** The caller guarantees that nByte positive.
+**
+** The caller has obtained a mutex prior to invoking this
+** routine so there is never any chance that two or more
+** threads can be in this routine at the same time.
+*/
+static void *memsys5MallocUnsafe(int nByte){
+  int i;           /* Index of a mem5.aPool[] slot */
+  int iBin;        /* Index into mem5.aiFreelist[] */
+  int iFullSz;     /* Size of allocation rounded up to power of 2 */
+  int iLogsize;    /* Log2 of iFullSz/POW2_MIN */
+
+  /* nByte must be a positive */
+  assert( nByte>0 );
+
+  /* Keep track of the maximum allocation request.  Even unfulfilled
+  ** requests are counted */
+  if( (u32)nByte>mem5.maxRequest ){
+    mem5.maxRequest = nByte;
+  }
+
+  /* Abort if the requested allocation size is larger than the largest
+  ** power of two that we can represent using 32-bit signed integers.
+  */
+  if( nByte > 0x40000000 ){
+    return 0;
+  }
+
+  /* Round nByte up to the next valid power of two */
+  for(iFullSz=mem5.szAtom, iLogsize=0; iFullSz<nByte; iFullSz *= 2, iLogsize++){}
+
+  /* Make sure mem5.aiFreelist[iLogsize] contains at least one free
+  ** block.  If not, then split a block of the next larger power of
+  ** two in order to create a new free block of size iLogsize.
+  */
+  for(iBin=iLogsize; mem5.aiFreelist[iBin]<0 && iBin<=LOGMAX; iBin++){}
+  if( iBin>LOGMAX ){
+    testcase( sqlite3GlobalConfig.xLog!=0 );
+    sqlite3_log(SQLITE_NOMEM, "failed to allocate %u bytes", nByte);
+    return 0;
+  }
+  i = memsys5UnlinkFirst(iBin);
+  while( iBin>iLogsize ){
+    int newSize;
+
+    iBin--;
+    newSize = 1 << iBin;
+    mem5.aCtrl[i+newSize] = CTRL_FREE | iBin;
+    memsys5Link(i+newSize, iBin);
+  }
+  mem5.aCtrl[i] = iLogsize;
+
+  /* Update allocator performance statistics. */
+  mem5.nAlloc++;
+  mem5.totalAlloc += iFullSz;
+  mem5.totalExcess += iFullSz - nByte;
+  mem5.currentCount++;
+  mem5.currentOut += iFullSz;
+  if( mem5.maxCount<mem5.currentCount ) mem5.maxCount = mem5.currentCount;
+  if( mem5.maxOut<mem5.currentOut ) mem5.maxOut = mem5.currentOut;
+
+  /* Return a pointer to the allocated memory. */
+  return (void*)&mem5.zPool[i*mem5.szAtom];
+}
+
+/*
+** Free an outstanding memory allocation.
+*/
+static void memsys5FreeUnsafe(void *pOld){
+  u32 size, iLogsize;
+  int iBlock;
+
+  /* Set iBlock to the index of the block pointed to by pOld in 
+  ** the array of mem5.szAtom byte blocks pointed to by mem5.zPool.
+  */
+  iBlock = ((u8 *)pOld-mem5.zPool)/mem5.szAtom;
+
+  /* Check that the pointer pOld points to a valid, non-free block. */
+  assert( iBlock>=0 && iBlock<mem5.nBlock );
+  assert( ((u8 *)pOld-mem5.zPool)%mem5.szAtom==0 );
+  assert( (mem5.aCtrl[iBlock] & CTRL_FREE)==0 );
+
+  iLogsize = mem5.aCtrl[iBlock] & CTRL_LOGSIZE;
+  size = 1<<iLogsize;
+  assert( iBlock+size-1<(u32)mem5.nBlock );
+
+  mem5.aCtrl[iBlock] |= CTRL_FREE;
+  mem5.aCtrl[iBlock+size-1] |= CTRL_FREE;
+  assert( mem5.currentCount>0 );
+  assert( mem5.currentOut>=(size*mem5.szAtom) );
+  mem5.currentCount--;
+  mem5.currentOut -= size*mem5.szAtom;
+  assert( mem5.currentOut>0 || mem5.currentCount==0 );
+  assert( mem5.currentCount>0 || mem5.currentOut==0 );
+
+  mem5.aCtrl[iBlock] = CTRL_FREE | iLogsize;
+  while( ALWAYS(iLogsize<LOGMAX) ){
+    int iBuddy;
+    if( (iBlock>>iLogsize) & 1 ){
+      iBuddy = iBlock - size;
+    }else{
+      iBuddy = iBlock + size;
+    }
+    assert( iBuddy>=0 );
+    if( (iBuddy+(1<<iLogsize))>mem5.nBlock ) break;
+    if( mem5.aCtrl[iBuddy]!=(CTRL_FREE | iLogsize) ) break;
+    memsys5Unlink(iBuddy, iLogsize);
+    iLogsize++;
+    if( iBuddy<iBlock ){
+      mem5.aCtrl[iBuddy] = CTRL_FREE | iLogsize;
+      mem5.aCtrl[iBlock] = 0;
+      iBlock = iBuddy;
+    }else{
+      mem5.aCtrl[iBlock] = CTRL_FREE | iLogsize;
+      mem5.aCtrl[iBuddy] = 0;
+    }
+    size *= 2;
+  }
+  memsys5Link(iBlock, iLogsize);
+}
+
+/*
+** Allocate nBytes of memory
+*/
+static void *memsys5Malloc(int nBytes){
+  sqlite3_int64 *p = 0;
+  if( nBytes>0 ){
+    memsys5Enter();
+    p = memsys5MallocUnsafe(nBytes);
+    memsys5Leave();
+  }
+  return (void*)p; 
+}
+
+/*
+** Free memory.
+**
+** The outer layer memory allocator prevents this routine from
+** being called with pPrior==0.
+*/
+static void memsys5Free(void *pPrior){
+  assert( pPrior!=0 );
+  memsys5Enter();
+  memsys5FreeUnsafe(pPrior);
+  memsys5Leave();  
+}
+
+/*
+** Change the size of an existing memory allocation.
+**
+** The outer layer memory allocator prevents this routine from
+** being called with pPrior==0.  
+**
+** nBytes is always a value obtained from a prior call to
+** memsys5Round().  Hence nBytes is always a non-negative power
+** of two.  If nBytes==0 that means that an oversize allocation
+** (an allocation larger than 0x40000000) was requested and this
+** routine should return 0 without freeing pPrior.
+*/
+static void *memsys5Realloc(void *pPrior, int nBytes){
+  int nOld;
+  void *p;
+  assert( pPrior!=0 );
+  assert( (nBytes&(nBytes-1))==0 );  /* EV: R-46199-30249 */
+  assert( nBytes>=0 );
+  if( nBytes==0 ){
+    return 0;
+  }
+  nOld = memsys5Size(pPrior);
+  if( nBytes<=nOld ){
+    return pPrior;
+  }
+  memsys5Enter();
+  p = memsys5MallocUnsafe(nBytes);
+  if( p ){
+    memcpy(p, pPrior, nOld);
+    memsys5FreeUnsafe(pPrior);
+  }
+  memsys5Leave();
+  return p;
+}
+
+/*
+** Round up a request size to the next valid allocation size.  If
+** the allocation is too large to be handled by this allocation system,
+** return 0.
+**
+** All allocations must be a power of two and must be expressed by a
+** 32-bit signed integer.  Hence the largest allocation is 0x40000000
+** or 1073741824 bytes.
+*/
+static int memsys5Roundup(int n){
+  int iFullSz;
+  if( n > 0x40000000 ) return 0;
+  for(iFullSz=mem5.szAtom; iFullSz<n; iFullSz *= 2);
+  return iFullSz;
+}
+
+/*
+** Return the ceiling of the logarithm base 2 of iValue.
+**
+** Examples:   memsys5Log(1) -> 0
+**             memsys5Log(2) -> 1
+**             memsys5Log(4) -> 2
+**             memsys5Log(5) -> 3
+**             memsys5Log(8) -> 3
+**             memsys5Log(9) -> 4
+*/
+static int memsys5Log(int iValue){
+  int iLog;
+  for(iLog=0; (iLog<(int)((sizeof(int)*8)-1)) && (1<<iLog)<iValue; iLog++);
+  return iLog;
+}
+
+/*
+** Initialize the memory allocator.
+**
+** This routine is not threadsafe.  The caller must be holding a mutex
+** to prevent multiple threads from entering at the same time.
+*/
+static int memsys5Init(void *NotUsed){
+  int ii;            /* Loop counter */
+  int nByte;         /* Number of bytes of memory available to this allocator */
+  u8 *zByte;         /* Memory usable by this allocator */
+  int nMinLog;       /* Log base 2 of minimum allocation size in bytes */
+  int iOffset;       /* An offset into mem5.aCtrl[] */
+
+  UNUSED_PARAMETER(NotUsed);
+
+  /* For the purposes of this routine, disable the mutex */
+  mem5.mutex = 0;
+
+  /* The size of a Mem5Link object must be a power of two.  Verify that
+  ** this is case.
+  */
+  assert( (sizeof(Mem5Link)&(sizeof(Mem5Link)-1))==0 );
+
+  nByte = sqlite3GlobalConfig.nHeap;
+  zByte = (u8*)sqlite3GlobalConfig.pHeap;
+  assert( zByte!=0 );  /* sqlite3_config() does not allow otherwise */
+
+  /* boundaries on sqlite3GlobalConfig.mnReq are enforced in sqlite3_config() */
+  nMinLog = memsys5Log(sqlite3GlobalConfig.mnReq);
+  mem5.szAtom = (1<<nMinLog);
+  while( (int)sizeof(Mem5Link)>mem5.szAtom ){
+    mem5.szAtom = mem5.szAtom << 1;
+  }
+
+  mem5.nBlock = (nByte / (mem5.szAtom+sizeof(u8)));
+  mem5.zPool = zByte;
+  mem5.aCtrl = (u8 *)&mem5.zPool[mem5.nBlock*mem5.szAtom];
+
+  for(ii=0; ii<=LOGMAX; ii++){
+    mem5.aiFreelist[ii] = -1;
+  }
+
+  iOffset = 0;
+  for(ii=LOGMAX; ii>=0; ii--){
+    int nAlloc = (1<<ii);
+    if( (iOffset+nAlloc)<=mem5.nBlock ){
+      mem5.aCtrl[iOffset] = ii | CTRL_FREE;
+      memsys5Link(iOffset, ii);
+      iOffset += nAlloc;
+    }
+    assert((iOffset+nAlloc)>mem5.nBlock);
+  }
+
+  /* If a mutex is required for normal operation, allocate one */
+  if( sqlite3GlobalConfig.bMemstat==0 ){
+    mem5.mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM);
+  }
+
+  return SQLITE_OK;
+}
+
+/*
+** Deinitialize this module.
+*/
+static void memsys5Shutdown(void *NotUsed){
+  UNUSED_PARAMETER(NotUsed);
+  mem5.mutex = 0;
+  return;
+}
+
+#ifdef SQLITE_TEST
+/*
+** Open the file indicated and write a log of all unfreed memory 
+** allocations into that log.
+*/
+SQLITE_PRIVATE void sqlite3Memsys5Dump(const char *zFilename){
+  FILE *out;
+  int i, j, n;
+  int nMinLog;
+
+  if( zFilename==0 || zFilename[0]==0 ){
+    out = stdout;
+  }else{
+    out = fopen(zFilename, "w");
+    if( out==0 ){
+      fprintf(stderr, "** Unable to output memory debug output log: %s **\n",
+                      zFilename);
+      return;
+    }
+  }
+  memsys5Enter();
+  nMinLog = memsys5Log(mem5.szAtom);
+  for(i=0; i<=LOGMAX && i+nMinLog<32; i++){
+    for(n=0, j=mem5.aiFreelist[i]; j>=0; j = MEM5LINK(j)->next, n++){}
+    fprintf(out, "freelist items of size %d: %d\n", mem5.szAtom << i, n);
+  }
+  fprintf(out, "mem5.nAlloc       = %llu\n", mem5.nAlloc);
+  fprintf(out, "mem5.totalAlloc   = %llu\n", mem5.totalAlloc);
+  fprintf(out, "mem5.totalExcess  = %llu\n", mem5.totalExcess);
+  fprintf(out, "mem5.currentOut   = %u\n", mem5.currentOut);
+  fprintf(out, "mem5.currentCount = %u\n", mem5.currentCount);
+  fprintf(out, "mem5.maxOut       = %u\n", mem5.maxOut);
+  fprintf(out, "mem5.maxCount     = %u\n", mem5.maxCount);
+  fprintf(out, "mem5.maxRequest   = %u\n", mem5.maxRequest);
+  memsys5Leave();
+  if( out==stdout ){
+    fflush(stdout);
+  }else{
+    fclose(out);
+  }
+}
+#endif
+
+/*
+** This routine is the only routine in this file with external 
+** linkage. It returns a pointer to a static sqlite3_mem_methods
+** struct populated with the memsys5 methods.
+*/
+SQLITE_PRIVATE const sqlite3_mem_methods *sqlite3MemGetMemsys5(void){
+  static const sqlite3_mem_methods memsys5Methods = {
+     memsys5Malloc,
+     memsys5Free,
+     memsys5Realloc,
+     memsys5Size,
+     memsys5Roundup,
+     memsys5Init,
+     memsys5Shutdown,
+     0
+  };
+  return &memsys5Methods;
+}
+
+#endif /* SQLITE_ENABLE_MEMSYS5 */
+
+/************** End of mem5.c ************************************************/
+/************** Begin file mutex.c *******************************************/
+/*
+** 2007 August 14
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains the C functions that implement mutexes.
+**
+** This file contains code that is common across all mutex implementations.
+*/
+
+#if defined(SQLITE_DEBUG) && !defined(SQLITE_MUTEX_OMIT)
+/*
+** For debugging purposes, record when the mutex subsystem is initialized
+** and uninitialized so that we can assert() if there is an attempt to
+** allocate a mutex while the system is uninitialized.
+*/
+static SQLITE_WSD int mutexIsInit = 0;
+#endif /* SQLITE_DEBUG */
+
+
+#ifndef SQLITE_MUTEX_OMIT
+/*
+** Initialize the mutex system.
+*/
+SQLITE_PRIVATE int sqlite3MutexInit(void){ 
+  int rc = SQLITE_OK;
+  if( !sqlite3GlobalConfig.mutex.xMutexAlloc ){
+    /* If the xMutexAlloc method has not been set, then the user did not
+    ** install a mutex implementation via sqlite3_config() prior to 
+    ** sqlite3_initialize() being called. This block copies pointers to
+    ** the default implementation into the sqlite3GlobalConfig structure.
+    */
+    sqlite3_mutex_methods const *pFrom;
+    sqlite3_mutex_methods *pTo = &sqlite3GlobalConfig.mutex;
+
+    if( sqlite3GlobalConfig.bCoreMutex ){
+      pFrom = sqlite3DefaultMutex();
+    }else{
+      pFrom = sqlite3NoopMutex();
+    }
+    memcpy(pTo, pFrom, offsetof(sqlite3_mutex_methods, xMutexAlloc));
+    memcpy(&pTo->xMutexFree, &pFrom->xMutexFree,
+           sizeof(*pTo) - offsetof(sqlite3_mutex_methods, xMutexFree));
+    pTo->xMutexAlloc = pFrom->xMutexAlloc;
+  }
+  rc = sqlite3GlobalConfig.mutex.xMutexInit();
+
+#ifdef SQLITE_DEBUG
+  GLOBAL(int, mutexIsInit) = 1;
+#endif
+
+  return rc;
+}
+
+/*
+** Shutdown the mutex system. This call frees resources allocated by
+** sqlite3MutexInit().
+*/
+SQLITE_PRIVATE int sqlite3MutexEnd(void){
+  int rc = SQLITE_OK;
+  if( sqlite3GlobalConfig.mutex.xMutexEnd ){
+    rc = sqlite3GlobalConfig.mutex.xMutexEnd();
+  }
+
+#ifdef SQLITE_DEBUG
+  GLOBAL(int, mutexIsInit) = 0;
+#endif
+
+  return rc;
+}
+
+/*
+** Retrieve a pointer to a static mutex or allocate a new dynamic one.
+*/
+SQLITE_API sqlite3_mutex *sqlite3_mutex_alloc(int id){
+#ifndef SQLITE_OMIT_AUTOINIT
+  if( sqlite3_initialize() ) return 0;
+#endif
+  return sqlite3GlobalConfig.mutex.xMutexAlloc(id);
+}
+
+SQLITE_PRIVATE sqlite3_mutex *sqlite3MutexAlloc(int id){
+  if( !sqlite3GlobalConfig.bCoreMutex ){
+    return 0;
+  }
+  assert( GLOBAL(int, mutexIsInit) );
+  return sqlite3GlobalConfig.mutex.xMutexAlloc(id);
+}
+
+/*
+** Free a dynamic mutex.
+*/
+SQLITE_API void sqlite3_mutex_free(sqlite3_mutex *p){
+  if( p ){
+    sqlite3GlobalConfig.mutex.xMutexFree(p);
+  }
+}
+
+/*
+** Obtain the mutex p. If some other thread already has the mutex, block
+** until it can be obtained.
+*/
+SQLITE_API void sqlite3_mutex_enter(sqlite3_mutex *p){
+  if( p ){
+    sqlite3GlobalConfig.mutex.xMutexEnter(p);
+  }
+}
+
+/*
+** Obtain the mutex p. If successful, return SQLITE_OK. Otherwise, if another
+** thread holds the mutex and it cannot be obtained, return SQLITE_BUSY.
+*/
+SQLITE_API int sqlite3_mutex_try(sqlite3_mutex *p){
+  int rc = SQLITE_OK;
+  if( p ){
+    return sqlite3GlobalConfig.mutex.xMutexTry(p);
+  }
+  return rc;
+}
+
+/*
+** The sqlite3_mutex_leave() routine exits a mutex that was previously
+** entered by the same thread.  The behavior is undefined if the mutex 
+** is not currently entered. If a NULL pointer is passed as an argument
+** this function is a no-op.
+*/
+SQLITE_API void sqlite3_mutex_leave(sqlite3_mutex *p){
+  if( p ){
+    sqlite3GlobalConfig.mutex.xMutexLeave(p);
+  }
+}
+
+#ifndef NDEBUG
+/*
+** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
+** intended for use inside assert() statements.
+*/
+SQLITE_API int sqlite3_mutex_held(sqlite3_mutex *p){
+  return p==0 || sqlite3GlobalConfig.mutex.xMutexHeld(p);
+}
+SQLITE_API int sqlite3_mutex_notheld(sqlite3_mutex *p){
+  return p==0 || sqlite3GlobalConfig.mutex.xMutexNotheld(p);
+}
+#endif
+
+#endif /* SQLITE_MUTEX_OMIT */
+
+/************** End of mutex.c ***********************************************/
+/************** Begin file mutex_noop.c **************************************/
+/*
+** 2008 October 07
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains the C functions that implement mutexes.
+**
+** This implementation in this file does not provide any mutual
+** exclusion and is thus suitable for use only in applications
+** that use SQLite in a single thread.  The routines defined
+** here are place-holders.  Applications can substitute working
+** mutex routines at start-time using the
+**
+**     sqlite3_config(SQLITE_CONFIG_MUTEX,...)
+**
+** interface.
+**
+** If compiled with SQLITE_DEBUG, then additional logic is inserted
+** that does error checking on mutexes to make sure they are being
+** called correctly.
+*/
+
+#ifndef SQLITE_MUTEX_OMIT
+
+#ifndef SQLITE_DEBUG
+/*
+** Stub routines for all mutex methods.
+**
+** This routines provide no mutual exclusion or error checking.
+*/
+static int noopMutexInit(void){ return SQLITE_OK; }
+static int noopMutexEnd(void){ return SQLITE_OK; }
+static sqlite3_mutex *noopMutexAlloc(int id){ 
+  UNUSED_PARAMETER(id);
+  return (sqlite3_mutex*)8; 
+}
+static void noopMutexFree(sqlite3_mutex *p){ UNUSED_PARAMETER(p); return; }
+static void noopMutexEnter(sqlite3_mutex *p){ UNUSED_PARAMETER(p); return; }
+static int noopMutexTry(sqlite3_mutex *p){
+  UNUSED_PARAMETER(p);
+  return SQLITE_OK;
+}
+static void noopMutexLeave(sqlite3_mutex *p){ UNUSED_PARAMETER(p); return; }
+
+SQLITE_PRIVATE sqlite3_mutex_methods const *sqlite3NoopMutex(void){
+  static const sqlite3_mutex_methods sMutex = {
+    noopMutexInit,
+    noopMutexEnd,
+    noopMutexAlloc,
+    noopMutexFree,
+    noopMutexEnter,
+    noopMutexTry,
+    noopMutexLeave,
+
+    0,
+    0,
+  };
+
+  return &sMutex;
+}
+#endif /* !SQLITE_DEBUG */
+
+#ifdef SQLITE_DEBUG
+/*
+** In this implementation, error checking is provided for testing
+** and debugging purposes.  The mutexes still do not provide any
+** mutual exclusion.
+*/
+
+/*
+** The mutex object
+*/
+typedef struct sqlite3_debug_mutex {
+  int id;     /* The mutex type */
+  int cnt;    /* Number of entries without a matching leave */
+} sqlite3_debug_mutex;
+
+/*
+** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
+** intended for use inside assert() statements.
+*/
+static int debugMutexHeld(sqlite3_mutex *pX){
+  sqlite3_debug_mutex *p = (sqlite3_debug_mutex*)pX;
+  return p==0 || p->cnt>0;
+}
+static int debugMutexNotheld(sqlite3_mutex *pX){
+  sqlite3_debug_mutex *p = (sqlite3_debug_mutex*)pX;
+  return p==0 || p->cnt==0;
+}
+
+/*
+** Initialize and deinitialize the mutex subsystem.
+*/
+static int debugMutexInit(void){ return SQLITE_OK; }
+static int debugMutexEnd(void){ return SQLITE_OK; }
+
+/*
+** The sqlite3_mutex_alloc() routine allocates a new
+** mutex and returns a pointer to it.  If it returns NULL
+** that means that a mutex could not be allocated. 
+*/
+static sqlite3_mutex *debugMutexAlloc(int id){
+  static sqlite3_debug_mutex aStatic[6];
+  sqlite3_debug_mutex *pNew = 0;
+  switch( id ){
+    case SQLITE_MUTEX_FAST:
+    case SQLITE_MUTEX_RECURSIVE: {
+      pNew = sqlite3Malloc(sizeof(*pNew));
+      if( pNew ){
+        pNew->id = id;
+        pNew->cnt = 0;
+      }
+      break;
+    }
+    default: {
+      assert( id-2 >= 0 );
+      assert( id-2 < (int)(sizeof(aStatic)/sizeof(aStatic[0])) );
+      pNew = &aStatic[id-2];
+      pNew->id = id;
+      break;
+    }
+  }
+  return (sqlite3_mutex*)pNew;
+}
+
+/*
+** This routine deallocates a previously allocated mutex.
+*/
+static void debugMutexFree(sqlite3_mutex *pX){
+  sqlite3_debug_mutex *p = (sqlite3_debug_mutex*)pX;
+  assert( p->cnt==0 );
+  assert( p->id==SQLITE_MUTEX_FAST || p->id==SQLITE_MUTEX_RECURSIVE );
+  sqlite3_free(p);
+}
+
+/*
+** The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
+** to enter a mutex.  If another thread is already within the mutex,
+** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
+** SQLITE_BUSY.  The sqlite3_mutex_try() interface returns SQLITE_OK
+** upon successful entry.  Mutexes created using SQLITE_MUTEX_RECURSIVE can
+** be entered multiple times by the same thread.  In such cases the,
+** mutex must be exited an equal number of times before another thread
+** can enter.  If the same thread tries to enter any other kind of mutex
+** more than once, the behavior is undefined.
+*/
+static void debugMutexEnter(sqlite3_mutex *pX){
+  sqlite3_debug_mutex *p = (sqlite3_debug_mutex*)pX;
+  assert( p->id==SQLITE_MUTEX_RECURSIVE || debugMutexNotheld(pX) );
+  p->cnt++;
+}
+static int debugMutexTry(sqlite3_mutex *pX){
+  sqlite3_debug_mutex *p = (sqlite3_debug_mutex*)pX;
+  assert( p->id==SQLITE_MUTEX_RECURSIVE || debugMutexNotheld(pX) );
+  p->cnt++;
+  return SQLITE_OK;
+}
+
+/*
+** The sqlite3_mutex_leave() routine exits a mutex that was
+** previously entered by the same thread.  The behavior
+** is undefined if the mutex is not currently entered or
+** is not currently allocated.  SQLite will never do either.
+*/
+static void debugMutexLeave(sqlite3_mutex *pX){
+  sqlite3_debug_mutex *p = (sqlite3_debug_mutex*)pX;
+  assert( debugMutexHeld(pX) );
+  p->cnt--;
+  assert( p->id==SQLITE_MUTEX_RECURSIVE || debugMutexNotheld(pX) );
+}
+
+SQLITE_PRIVATE sqlite3_mutex_methods const *sqlite3NoopMutex(void){
+  static const sqlite3_mutex_methods sMutex = {
+    debugMutexInit,
+    debugMutexEnd,
+    debugMutexAlloc,
+    debugMutexFree,
+    debugMutexEnter,
+    debugMutexTry,
+    debugMutexLeave,
+
+    debugMutexHeld,
+    debugMutexNotheld
+  };
+
+  return &sMutex;
+}
+#endif /* SQLITE_DEBUG */
+
+/*
+** If compiled with SQLITE_MUTEX_NOOP, then the no-op mutex implementation
+** is used regardless of the run-time threadsafety setting.
+*/
+#ifdef SQLITE_MUTEX_NOOP
+SQLITE_PRIVATE sqlite3_mutex_methods const *sqlite3DefaultMutex(void){
+  return sqlite3NoopMutex();
+}
+#endif /* SQLITE_MUTEX_NOOP */
+#endif /* SQLITE_MUTEX_OMIT */
+
+/************** End of mutex_noop.c ******************************************/
+/************** Begin file mutex_os2.c ***************************************/
+/*
+** 2007 August 28
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains the C functions that implement mutexes for OS/2
+*/
+
+/*
+** The code in this file is only used if SQLITE_MUTEX_OS2 is defined.
+** See the mutex.h file for details.
+*/
+#ifdef SQLITE_MUTEX_OS2
+
+/********************** OS/2 Mutex Implementation **********************
+**
+** This implementation of mutexes is built using the OS/2 API.
+*/
+
+/*
+** The mutex object
+** Each recursive mutex is an instance of the following structure.
+*/
+struct sqlite3_mutex {
+  HMTX mutex;       /* Mutex controlling the lock */
+  int  id;          /* Mutex type */
+#ifdef SQLITE_DEBUG
+ int   trace;       /* True to trace changes */
+#endif
+};
+
+#ifdef SQLITE_DEBUG
+#define SQLITE3_MUTEX_INITIALIZER { 0, 0, 0 }
+#else
+#define SQLITE3_MUTEX_INITIALIZER { 0, 0 }
+#endif
+
+/*
+** Initialize and deinitialize the mutex subsystem.
+*/
+static int os2MutexInit(void){ return SQLITE_OK; }
+static int os2MutexEnd(void){ return SQLITE_OK; }
+
+/*
+** The sqlite3_mutex_alloc() routine allocates a new
+** mutex and returns a pointer to it.  If it returns NULL
+** that means that a mutex could not be allocated. 
+** SQLite will unwind its stack and return an error.  The argument
+** to sqlite3_mutex_alloc() is one of these integer constants:
+**
+** <ul>
+** <li>  SQLITE_MUTEX_FAST
+** <li>  SQLITE_MUTEX_RECURSIVE
+** <li>  SQLITE_MUTEX_STATIC_MASTER
+** <li>  SQLITE_MUTEX_STATIC_MEM
+** <li>  SQLITE_MUTEX_STATIC_MEM2
+** <li>  SQLITE_MUTEX_STATIC_PRNG
+** <li>  SQLITE_MUTEX_STATIC_LRU
+** <li>  SQLITE_MUTEX_STATIC_LRU2
+** </ul>
+**
+** The first two constants cause sqlite3_mutex_alloc() to create
+** a new mutex.  The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
+** is used but not necessarily so when SQLITE_MUTEX_FAST is used.
+** The mutex implementation does not need to make a distinction
+** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does
+** not want to.  But SQLite will only request a recursive mutex in
+** cases where it really needs one.  If a faster non-recursive mutex
+** implementation is available on the host platform, the mutex subsystem
+** might return such a mutex in response to SQLITE_MUTEX_FAST.
+**
+** The other allowed parameters to sqlite3_mutex_alloc() each return
+** a pointer to a static preexisting mutex.  Six static mutexes are
+** used by the current version of SQLite.  Future versions of SQLite
+** may add additional static mutexes.  Static mutexes are for internal
+** use by SQLite only.  Applications that use SQLite mutexes should
+** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or
+** SQLITE_MUTEX_RECURSIVE.
+**
+** Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST
+** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc()
+** returns a different mutex on every call.  But for the static
+** mutex types, the same mutex is returned on every call that has
+** the same type number.
+*/
+static sqlite3_mutex *os2MutexAlloc(int iType){
+  sqlite3_mutex *p = NULL;
+  switch( iType ){
+    case SQLITE_MUTEX_FAST:
+    case SQLITE_MUTEX_RECURSIVE: {
+      p = sqlite3MallocZero( sizeof(*p) );
+      if( p ){
+        p->id = iType;
+        if( DosCreateMutexSem( 0, &p->mutex, 0, FALSE ) != NO_ERROR ){
+          sqlite3_free( p );
+          p = NULL;
+        }
+      }
+      break;
+    }
+    default: {
+      static volatile int isInit = 0;
+      static sqlite3_mutex staticMutexes[6] = {
+        SQLITE3_MUTEX_INITIALIZER,
+        SQLITE3_MUTEX_INITIALIZER,
+        SQLITE3_MUTEX_INITIALIZER,
+        SQLITE3_MUTEX_INITIALIZER,
+        SQLITE3_MUTEX_INITIALIZER,
+        SQLITE3_MUTEX_INITIALIZER,
+      };
+      if ( !isInit ){
+        APIRET rc;
+        PTIB ptib;
+        PPIB ppib;
+        HMTX mutex;
+        char name[32];
+        DosGetInfoBlocks( &ptib, &ppib );
+        sqlite3_snprintf( sizeof(name), name, "\\SEM32\\SQLITE%04x",
+                          ppib->pib_ulpid );
+        while( !isInit ){
+          mutex = 0;
+          rc = DosCreateMutexSem( name, &mutex, 0, FALSE);
+          if( rc == NO_ERROR ){
+            unsigned int i;
+            if( !isInit ){
+              for( i = 0; i < sizeof(staticMutexes)/sizeof(staticMutexes[0]); i++ ){
+                DosCreateMutexSem( 0, &staticMutexes[i].mutex, 0, FALSE );
+              }
+              isInit = 1;
+            }
+            DosCloseMutexSem( mutex );
+          }else if( rc == ERROR_DUPLICATE_NAME ){
+            DosSleep( 1 );
+          }else{
+            return p;
+          }
+        }
+      }
+      assert( iType-2 >= 0 );
+      assert( iType-2 < sizeof(staticMutexes)/sizeof(staticMutexes[0]) );
+      p = &staticMutexes[iType-2];
+      p->id = iType;
+      break;
+    }
+  }
+  return p;
+}
+
+
+/*
+** This routine deallocates a previously allocated mutex.
+** SQLite is careful to deallocate every mutex that it allocates.
+*/
+static void os2MutexFree(sqlite3_mutex *p){
+#ifdef SQLITE_DEBUG
+  TID tid;
+  PID pid;
+  ULONG ulCount;
+  DosQueryMutexSem(p->mutex, &pid, &tid, &ulCount);
+  assert( ulCount==0 );
+  assert( p->id==SQLITE_MUTEX_FAST || p->id==SQLITE_MUTEX_RECURSIVE );
+#endif
+  DosCloseMutexSem( p->mutex );
+  sqlite3_free( p );
+}
+
+#ifdef SQLITE_DEBUG
+/*
+** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
+** intended for use inside assert() statements.
+*/
+static int os2MutexHeld(sqlite3_mutex *p){
+  TID tid;
+  PID pid;
+  ULONG ulCount;
+  PTIB ptib;
+  DosQueryMutexSem(p->mutex, &pid, &tid, &ulCount);
+  if( ulCount==0 || ( ulCount>1 && p->id!=SQLITE_MUTEX_RECURSIVE ) )
+    return 0;
+  DosGetInfoBlocks(&ptib, NULL);
+  return tid==ptib->tib_ptib2->tib2_ultid;
+}
+static int os2MutexNotheld(sqlite3_mutex *p){
+  TID tid;
+  PID pid;
+  ULONG ulCount;
+  PTIB ptib;
+  DosQueryMutexSem(p->mutex, &pid, &tid, &ulCount);
+  if( ulCount==0 )
+    return 1;
+  DosGetInfoBlocks(&ptib, NULL);
+  return tid!=ptib->tib_ptib2->tib2_ultid;
+}
+static void os2MutexTrace(sqlite3_mutex *p, char *pAction){
+  TID   tid;
+  PID   pid;
+  ULONG ulCount;
+  DosQueryMutexSem(p->mutex, &pid, &tid, &ulCount);
+  printf("%s mutex %p (%d) with nRef=%ld\n", pAction, (void*)p, p->trace, ulCount);
+}
+#endif
+
+/*
+** The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
+** to enter a mutex.  If another thread is already within the mutex,
+** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
+** SQLITE_BUSY.  The sqlite3_mutex_try() interface returns SQLITE_OK
+** upon successful entry.  Mutexes created using SQLITE_MUTEX_RECURSIVE can
+** be entered multiple times by the same thread.  In such cases the,
+** mutex must be exited an equal number of times before another thread
+** can enter.  If the same thread tries to enter any other kind of mutex
+** more than once, the behavior is undefined.
+*/
+static void os2MutexEnter(sqlite3_mutex *p){
+  assert( p->id==SQLITE_MUTEX_RECURSIVE || os2MutexNotheld(p) );
+  DosRequestMutexSem(p->mutex, SEM_INDEFINITE_WAIT);
+#ifdef SQLITE_DEBUG
+  if( p->trace ) os2MutexTrace(p, "enter");
+#endif
+}
+static int os2MutexTry(sqlite3_mutex *p){
+  int rc = SQLITE_BUSY;
+  assert( p->id==SQLITE_MUTEX_RECURSIVE || os2MutexNotheld(p) );
+  if( DosRequestMutexSem(p->mutex, SEM_IMMEDIATE_RETURN) == NO_ERROR ) {
+    rc = SQLITE_OK;
+#ifdef SQLITE_DEBUG
+    if( p->trace ) os2MutexTrace(p, "try");
+#endif
+  }
+  return rc;
+}
+
+/*
+** The sqlite3_mutex_leave() routine exits a mutex that was
+** previously entered by the same thread.  The behavior
+** is undefined if the mutex is not currently entered or
+** is not currently allocated.  SQLite will never do either.
+*/
+static void os2MutexLeave(sqlite3_mutex *p){
+  assert( os2MutexHeld(p) );
+  DosReleaseMutexSem(p->mutex);
+#ifdef SQLITE_DEBUG
+  if( p->trace ) os2MutexTrace(p, "leave");
+#endif
+}
+
+SQLITE_PRIVATE sqlite3_mutex_methods const *sqlite3DefaultMutex(void){
+  static const sqlite3_mutex_methods sMutex = {
+    os2MutexInit,
+    os2MutexEnd,
+    os2MutexAlloc,
+    os2MutexFree,
+    os2MutexEnter,
+    os2MutexTry,
+    os2MutexLeave,
+#ifdef SQLITE_DEBUG
+    os2MutexHeld,
+    os2MutexNotheld
+#else
+    0,
+    0
+#endif
+  };
+
+  return &sMutex;
+}
+#endif /* SQLITE_MUTEX_OS2 */
+
+/************** End of mutex_os2.c *******************************************/
+/************** Begin file mutex_unix.c **************************************/
+/*
+** 2007 August 28
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains the C functions that implement mutexes for pthreads
+*/
+
+/*
+** The code in this file is only used if we are compiling threadsafe
+** under unix with pthreads.
+**
+** Note that this implementation requires a version of pthreads that
+** supports recursive mutexes.
+*/
+#ifdef SQLITE_MUTEX_PTHREADS
+
+#include <pthread.h>
+
+/*
+** The sqlite3_mutex.id, sqlite3_mutex.nRef, and sqlite3_mutex.owner fields
+** are necessary under two condidtions:  (1) Debug builds and (2) using
+** home-grown mutexes.  Encapsulate these conditions into a single #define.
+*/
+#if defined(SQLITE_DEBUG) || defined(SQLITE_HOMEGROWN_RECURSIVE_MUTEX)
+# define SQLITE_MUTEX_NREF 1
+#else
+# define SQLITE_MUTEX_NREF 0
+#endif
+
+/*
+** Each recursive mutex is an instance of the following structure.
+*/
+struct sqlite3_mutex {
+  pthread_mutex_t mutex;     /* Mutex controlling the lock */
+#if SQLITE_MUTEX_NREF
+  int id;                    /* Mutex type */
+  volatile int nRef;         /* Number of entrances */
+  volatile pthread_t owner;  /* Thread that is within this mutex */
+  int trace;                 /* True to trace changes */
+#endif
+};
+#if SQLITE_MUTEX_NREF
+#define SQLITE3_MUTEX_INITIALIZER { PTHREAD_MUTEX_INITIALIZER, 0, 0, (pthread_t)0, 0 }
+#else
+#define SQLITE3_MUTEX_INITIALIZER { PTHREAD_MUTEX_INITIALIZER }
+#endif
+
+/*
+** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
+** intended for use only inside assert() statements.  On some platforms,
+** there might be race conditions that can cause these routines to
+** deliver incorrect results.  In particular, if pthread_equal() is
+** not an atomic operation, then these routines might delivery
+** incorrect results.  On most platforms, pthread_equal() is a 
+** comparison of two integers and is therefore atomic.  But we are
+** told that HPUX is not such a platform.  If so, then these routines
+** will not always work correctly on HPUX.
+**
+** On those platforms where pthread_equal() is not atomic, SQLite
+** should be compiled without -DSQLITE_DEBUG and with -DNDEBUG to
+** make sure no assert() statements are evaluated and hence these
+** routines are never called.
+*/
+#if !defined(NDEBUG) || defined(SQLITE_DEBUG)
+static int pthreadMutexHeld(sqlite3_mutex *p){
+  return (p->nRef!=0 && pthread_equal(p->owner, pthread_self()));
+}
+static int pthreadMutexNotheld(sqlite3_mutex *p){
+  return p->nRef==0 || pthread_equal(p->owner, pthread_self())==0;
+}
+#endif
+
+/*
+** Initialize and deinitialize the mutex subsystem.
+*/
+static int pthreadMutexInit(void){ return SQLITE_OK; }
+static int pthreadMutexEnd(void){ return SQLITE_OK; }
+
+/*
+** The sqlite3_mutex_alloc() routine allocates a new
+** mutex and returns a pointer to it.  If it returns NULL
+** that means that a mutex could not be allocated.  SQLite
+** will unwind its stack and return an error.  The argument
+** to sqlite3_mutex_alloc() is one of these integer constants:
+**
+** <ul>
+** <li>  SQLITE_MUTEX_FAST
+** <li>  SQLITE_MUTEX_RECURSIVE
+** <li>  SQLITE_MUTEX_STATIC_MASTER
+** <li>  SQLITE_MUTEX_STATIC_MEM
+** <li>  SQLITE_MUTEX_STATIC_MEM2
+** <li>  SQLITE_MUTEX_STATIC_PRNG
+** <li>  SQLITE_MUTEX_STATIC_LRU
+** <li>  SQLITE_MUTEX_STATIC_PMEM
+** </ul>
+**
+** The first two constants cause sqlite3_mutex_alloc() to create
+** a new mutex.  The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
+** is used but not necessarily so when SQLITE_MUTEX_FAST is used.
+** The mutex implementation does not need to make a distinction
+** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does
+** not want to.  But SQLite will only request a recursive mutex in
+** cases where it really needs one.  If a faster non-recursive mutex
+** implementation is available on the host platform, the mutex subsystem
+** might return such a mutex in response to SQLITE_MUTEX_FAST.
+**
+** The other allowed parameters to sqlite3_mutex_alloc() each return
+** a pointer to a static preexisting mutex.  Six static mutexes are
+** used by the current version of SQLite.  Future versions of SQLite
+** may add additional static mutexes.  Static mutexes are for internal
+** use by SQLite only.  Applications that use SQLite mutexes should
+** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or
+** SQLITE_MUTEX_RECURSIVE.
+**
+** Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST
+** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc()
+** returns a different mutex on every call.  But for the static 
+** mutex types, the same mutex is returned on every call that has
+** the same type number.
+*/
+static sqlite3_mutex *pthreadMutexAlloc(int iType){
+  static sqlite3_mutex staticMutexes[] = {
+    SQLITE3_MUTEX_INITIALIZER,
+    SQLITE3_MUTEX_INITIALIZER,
+    SQLITE3_MUTEX_INITIALIZER,
+    SQLITE3_MUTEX_INITIALIZER,
+    SQLITE3_MUTEX_INITIALIZER,
+    SQLITE3_MUTEX_INITIALIZER
+  };
+  sqlite3_mutex *p;
+  switch( iType ){
+    case SQLITE_MUTEX_RECURSIVE: {
+      p = sqlite3MallocZero( sizeof(*p) );
+      if( p ){
+#ifdef SQLITE_HOMEGROWN_RECURSIVE_MUTEX
+        /* If recursive mutexes are not available, we will have to
+        ** build our own.  See below. */
+        pthread_mutex_init(&p->mutex, 0);
+#else
+        /* Use a recursive mutex if it is available */
+        pthread_mutexattr_t recursiveAttr;
+        pthread_mutexattr_init(&recursiveAttr);
+        pthread_mutexattr_settype(&recursiveAttr, PTHREAD_MUTEX_RECURSIVE);
+        pthread_mutex_init(&p->mutex, &recursiveAttr);
+        pthread_mutexattr_destroy(&recursiveAttr);
+#endif
+#if SQLITE_MUTEX_NREF
+        p->id = iType;
+#endif
+      }
+      break;
+    }
+    case SQLITE_MUTEX_FAST: {
+      p = sqlite3MallocZero( sizeof(*p) );
+      if( p ){
+#if SQLITE_MUTEX_NREF
+        p->id = iType;
+#endif
+        pthread_mutex_init(&p->mutex, 0);
+      }
+      break;
+    }
+    default: {
+      assert( iType-2 >= 0 );
+      assert( iType-2 < ArraySize(staticMutexes) );
+      p = &staticMutexes[iType-2];
+#if SQLITE_MUTEX_NREF
+      p->id = iType;
+#endif
+      break;
+    }
+  }
+  return p;
+}
+
+
+/*
+** This routine deallocates a previously
+** allocated mutex.  SQLite is careful to deallocate every
+** mutex that it allocates.
+*/
+static void pthreadMutexFree(sqlite3_mutex *p){
+  assert( p->nRef==0 );
+  assert( p->id==SQLITE_MUTEX_FAST || p->id==SQLITE_MUTEX_RECURSIVE );
+  pthread_mutex_destroy(&p->mutex);
+  sqlite3_free(p);
+}
+
+/*
+** The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
+** to enter a mutex.  If another thread is already within the mutex,
+** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
+** SQLITE_BUSY.  The sqlite3_mutex_try() interface returns SQLITE_OK
+** upon successful entry.  Mutexes created using SQLITE_MUTEX_RECURSIVE can
+** be entered multiple times by the same thread.  In such cases the,
+** mutex must be exited an equal number of times before another thread
+** can enter.  If the same thread tries to enter any other kind of mutex
+** more than once, the behavior is undefined.
+*/
+static void pthreadMutexEnter(sqlite3_mutex *p){
+  assert( p->id==SQLITE_MUTEX_RECURSIVE || pthreadMutexNotheld(p) );
+
+#ifdef SQLITE_HOMEGROWN_RECURSIVE_MUTEX
+  /* If recursive mutexes are not available, then we have to grow
+  ** our own.  This implementation assumes that pthread_equal()
+  ** is atomic - that it cannot be deceived into thinking self
+  ** and p->owner are equal if p->owner changes between two values
+  ** that are not equal to self while the comparison is taking place.
+  ** This implementation also assumes a coherent cache - that 
+  ** separate processes cannot read different values from the same
+  ** address at the same time.  If either of these two conditions
+  ** are not met, then the mutexes will fail and problems will result.
+  */
+  {
+    pthread_t self = pthread_self();
+    if( p->nRef>0 && pthread_equal(p->owner, self) ){
+      p->nRef++;
+    }else{
+      pthread_mutex_lock(&p->mutex);
+      assert( p->nRef==0 );
+      p->owner = self;
+      p->nRef = 1;
+    }
+  }
+#else
+  /* Use the built-in recursive mutexes if they are available.
+  */
+  pthread_mutex_lock(&p->mutex);
+#if SQLITE_MUTEX_NREF
+  assert( p->nRef>0 || p->owner==0 );
+  p->owner = pthread_self();
+  p->nRef++;
+#endif
+#endif
+
+#ifdef SQLITE_DEBUG
+  if( p->trace ){
+    printf("enter mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef);
+  }
+#endif
+}
+static int pthreadMutexTry(sqlite3_mutex *p){
+  int rc;
+  assert( p->id==SQLITE_MUTEX_RECURSIVE || pthreadMutexNotheld(p) );
+
+#ifdef SQLITE_HOMEGROWN_RECURSIVE_MUTEX
+  /* If recursive mutexes are not available, then we have to grow
+  ** our own.  This implementation assumes that pthread_equal()
+  ** is atomic - that it cannot be deceived into thinking self
+  ** and p->owner are equal if p->owner changes between two values
+  ** that are not equal to self while the comparison is taking place.
+  ** This implementation also assumes a coherent cache - that 
+  ** separate processes cannot read different values from the same
+  ** address at the same time.  If either of these two conditions
+  ** are not met, then the mutexes will fail and problems will result.
+  */
+  {
+    pthread_t self = pthread_self();
+    if( p->nRef>0 && pthread_equal(p->owner, self) ){
+      p->nRef++;
+      rc = SQLITE_OK;
+    }else if( pthread_mutex_trylock(&p->mutex)==0 ){
+      assert( p->nRef==0 );
+      p->owner = self;
+      p->nRef = 1;
+      rc = SQLITE_OK;
+    }else{
+      rc = SQLITE_BUSY;
+    }
+  }
+#else
+  /* Use the built-in recursive mutexes if they are available.
+  */
+  if( pthread_mutex_trylock(&p->mutex)==0 ){
+#if SQLITE_MUTEX_NREF
+    p->owner = pthread_self();
+    p->nRef++;
+#endif
+    rc = SQLITE_OK;
+  }else{
+    rc = SQLITE_BUSY;
+  }
+#endif
+
+#ifdef SQLITE_DEBUG
+  if( rc==SQLITE_OK && p->trace ){
+    printf("enter mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef);
+  }
+#endif
+  return rc;
+}
+
+/*
+** The sqlite3_mutex_leave() routine exits a mutex that was
+** previously entered by the same thread.  The behavior
+** is undefined if the mutex is not currently entered or
+** is not currently allocated.  SQLite will never do either.
+*/
+static void pthreadMutexLeave(sqlite3_mutex *p){
+  assert( pthreadMutexHeld(p) );
+#if SQLITE_MUTEX_NREF
+  p->nRef--;
+  if( p->nRef==0 ) p->owner = 0;
+#endif
+  assert( p->nRef==0 || p->id==SQLITE_MUTEX_RECURSIVE );
+
+#ifdef SQLITE_HOMEGROWN_RECURSIVE_MUTEX
+  if( p->nRef==0 ){
+    pthread_mutex_unlock(&p->mutex);
+  }
+#else
+  pthread_mutex_unlock(&p->mutex);
+#endif
+
+#ifdef SQLITE_DEBUG
+  if( p->trace ){
+    printf("leave mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef);
+  }
+#endif
+}
+
+SQLITE_PRIVATE sqlite3_mutex_methods const *sqlite3DefaultMutex(void){
+  static const sqlite3_mutex_methods sMutex = {
+    pthreadMutexInit,
+    pthreadMutexEnd,
+    pthreadMutexAlloc,
+    pthreadMutexFree,
+    pthreadMutexEnter,
+    pthreadMutexTry,
+    pthreadMutexLeave,
+#ifdef SQLITE_DEBUG
+    pthreadMutexHeld,
+    pthreadMutexNotheld
+#else
+    0,
+    0
+#endif
+  };
+
+  return &sMutex;
+}
+
+#endif /* SQLITE_MUTEX_PTHREAD */
+
+/************** End of mutex_unix.c ******************************************/
+/************** Begin file mutex_w32.c ***************************************/
+/*
+** 2007 August 14
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains the C functions that implement mutexes for win32
+*/
+
+/*
+** The code in this file is only used if we are compiling multithreaded
+** on a win32 system.
+*/
+#ifdef SQLITE_MUTEX_W32
+
+/*
+** Each recursive mutex is an instance of the following structure.
+*/
+struct sqlite3_mutex {
+  CRITICAL_SECTION mutex;    /* Mutex controlling the lock */
+  int id;                    /* Mutex type */
+#ifdef SQLITE_DEBUG
+  volatile int nRef;         /* Number of enterances */
+  volatile DWORD owner;      /* Thread holding this mutex */
+  int trace;                 /* True to trace changes */
+#endif
+};
+#define SQLITE_W32_MUTEX_INITIALIZER { 0 }
+#ifdef SQLITE_DEBUG
+#define SQLITE3_MUTEX_INITIALIZER { SQLITE_W32_MUTEX_INITIALIZER, 0, 0L, (DWORD)0, 0 }
+#else
+#define SQLITE3_MUTEX_INITIALIZER { SQLITE_W32_MUTEX_INITIALIZER, 0 }
+#endif
+
+/*
+** Return true (non-zero) if we are running under WinNT, Win2K, WinXP,
+** or WinCE.  Return false (zero) for Win95, Win98, or WinME.
+**
+** Here is an interesting observation:  Win95, Win98, and WinME lack
+** the LockFileEx() API.  But we can still statically link against that
+** API as long as we don't call it win running Win95/98/ME.  A call to
+** this routine is used to determine if the host is Win95/98/ME or
+** WinNT/2K/XP so that we will know whether or not we can safely call
+** the LockFileEx() API.
+**
+** mutexIsNT() is only used for the TryEnterCriticalSection() API call,
+** which is only available if your application was compiled with 
+** _WIN32_WINNT defined to a value >= 0x0400.  Currently, the only
+** call to TryEnterCriticalSection() is #ifdef'ed out, so #ifdef 
+** this out as well.
+*/
+#if 0
+#if SQLITE_OS_WINCE
+# define mutexIsNT()  (1)
+#else
+  static int mutexIsNT(void){
+    static int osType = 0;
+    if( osType==0 ){
+      OSVERSIONINFO sInfo;
+      sInfo.dwOSVersionInfoSize = sizeof(sInfo);
+      GetVersionEx(&sInfo);
+      osType = sInfo.dwPlatformId==VER_PLATFORM_WIN32_NT ? 2 : 1;
+    }
+    return osType==2;
+  }
+#endif /* SQLITE_OS_WINCE */
+#endif
+
+#ifdef SQLITE_DEBUG
+/*
+** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
+** intended for use only inside assert() statements.
+*/
+static int winMutexHeld(sqlite3_mutex *p){
+  return p->nRef!=0 && p->owner==GetCurrentThreadId();
+}
+static int winMutexNotheld2(sqlite3_mutex *p, DWORD tid){
+  return p->nRef==0 || p->owner!=tid;
+}
+static int winMutexNotheld(sqlite3_mutex *p){
+  DWORD tid = GetCurrentThreadId(); 
+  return winMutexNotheld2(p, tid);
+}
+#endif
+
+
+/*
+** Initialize and deinitialize the mutex subsystem.
+*/
+static sqlite3_mutex winMutex_staticMutexes[6] = {
+  SQLITE3_MUTEX_INITIALIZER,
+  SQLITE3_MUTEX_INITIALIZER,
+  SQLITE3_MUTEX_INITIALIZER,
+  SQLITE3_MUTEX_INITIALIZER,
+  SQLITE3_MUTEX_INITIALIZER,
+  SQLITE3_MUTEX_INITIALIZER
+};
+static int winMutex_isInit = 0;
+/* As winMutexInit() and winMutexEnd() are called as part
+** of the sqlite3_initialize and sqlite3_shutdown()
+** processing, the "interlocked" magic is probably not
+** strictly necessary.
+*/
+static long winMutex_lock = 0;
+
+static int winMutexInit(void){ 
+  /* The first to increment to 1 does actual initialization */
+  if( InterlockedCompareExchange(&winMutex_lock, 1, 0)==0 ){
+    int i;
+    for(i=0; i<ArraySize(winMutex_staticMutexes); i++){
+      InitializeCriticalSection(&winMutex_staticMutexes[i].mutex);
+    }
+    winMutex_isInit = 1;
+  }else{
+    /* Someone else is in the process of initing the static mutexes */
+    while( !winMutex_isInit ){
+      Sleep(1);
+    }
+  }
+  return SQLITE_OK; 
+}
+
+static int winMutexEnd(void){ 
+  /* The first to decrement to 0 does actual shutdown 
+  ** (which should be the last to shutdown.) */
+  if( InterlockedCompareExchange(&winMutex_lock, 0, 1)==1 ){
+    if( winMutex_isInit==1 ){
+      int i;
+      for(i=0; i<ArraySize(winMutex_staticMutexes); i++){
+        DeleteCriticalSection(&winMutex_staticMutexes[i].mutex);
+      }
+      winMutex_isInit = 0;
+    }
+  }
+  return SQLITE_OK; 
+}
+
+/*
+** The sqlite3_mutex_alloc() routine allocates a new
+** mutex and returns a pointer to it.  If it returns NULL
+** that means that a mutex could not be allocated.  SQLite
+** will unwind its stack and return an error.  The argument
+** to sqlite3_mutex_alloc() is one of these integer constants:
+**
+** <ul>
+** <li>  SQLITE_MUTEX_FAST
+** <li>  SQLITE_MUTEX_RECURSIVE
+** <li>  SQLITE_MUTEX_STATIC_MASTER
+** <li>  SQLITE_MUTEX_STATIC_MEM
+** <li>  SQLITE_MUTEX_STATIC_MEM2
+** <li>  SQLITE_MUTEX_STATIC_PRNG
+** <li>  SQLITE_MUTEX_STATIC_LRU
+** <li>  SQLITE_MUTEX_STATIC_PMEM
+** </ul>
+**
+** The first two constants cause sqlite3_mutex_alloc() to create
+** a new mutex.  The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
+** is used but not necessarily so when SQLITE_MUTEX_FAST is used.
+** The mutex implementation does not need to make a distinction
+** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does
+** not want to.  But SQLite will only request a recursive mutex in
+** cases where it really needs one.  If a faster non-recursive mutex
+** implementation is available on the host platform, the mutex subsystem
+** might return such a mutex in response to SQLITE_MUTEX_FAST.
+**
+** The other allowed parameters to sqlite3_mutex_alloc() each return
+** a pointer to a static preexisting mutex.  Six static mutexes are
+** used by the current version of SQLite.  Future versions of SQLite
+** may add additional static mutexes.  Static mutexes are for internal
+** use by SQLite only.  Applications that use SQLite mutexes should
+** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or
+** SQLITE_MUTEX_RECURSIVE.
+**
+** Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST
+** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc()
+** returns a different mutex on every call.  But for the static 
+** mutex types, the same mutex is returned on every call that has
+** the same type number.
+*/
+static sqlite3_mutex *winMutexAlloc(int iType){
+  sqlite3_mutex *p;
+
+  switch( iType ){
+    case SQLITE_MUTEX_FAST:
+    case SQLITE_MUTEX_RECURSIVE: {
+      p = sqlite3MallocZero( sizeof(*p) );
+      if( p ){  
+#ifdef SQLITE_DEBUG
+        p->id = iType;
+#endif
+        InitializeCriticalSection(&p->mutex);
+      }
+      break;
+    }
+    default: {
+      assert( winMutex_isInit==1 );
+      assert( iType-2 >= 0 );
+      assert( iType-2 < ArraySize(winMutex_staticMutexes) );
+      p = &winMutex_staticMutexes[iType-2];
+#ifdef SQLITE_DEBUG
+      p->id = iType;
+#endif
+      break;
+    }
+  }
+  return p;
+}
+
+
+/*
+** This routine deallocates a previously
+** allocated mutex.  SQLite is careful to deallocate every
+** mutex that it allocates.
+*/
+static void winMutexFree(sqlite3_mutex *p){
+  assert( p );
+  assert( p->nRef==0 && p->owner==0 );
+  assert( p->id==SQLITE_MUTEX_FAST || p->id==SQLITE_MUTEX_RECURSIVE );
+  DeleteCriticalSection(&p->mutex);
+  sqlite3_free(p);
+}
+
+/*
+** The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
+** to enter a mutex.  If another thread is already within the mutex,
+** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
+** SQLITE_BUSY.  The sqlite3_mutex_try() interface returns SQLITE_OK
+** upon successful entry.  Mutexes created using SQLITE_MUTEX_RECURSIVE can
+** be entered multiple times by the same thread.  In such cases the,
+** mutex must be exited an equal number of times before another thread
+** can enter.  If the same thread tries to enter any other kind of mutex
+** more than once, the behavior is undefined.
+*/
+static void winMutexEnter(sqlite3_mutex *p){
+#ifdef SQLITE_DEBUG
+  DWORD tid = GetCurrentThreadId(); 
+  assert( p->id==SQLITE_MUTEX_RECURSIVE || winMutexNotheld2(p, tid) );
+#endif
+  EnterCriticalSection(&p->mutex);
+#ifdef SQLITE_DEBUG
+  assert( p->nRef>0 || p->owner==0 );
+  p->owner = tid; 
+  p->nRef++;
+  if( p->trace ){
+    printf("enter mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef);
+  }
+#endif
+}
+static int winMutexTry(sqlite3_mutex *p){
+#ifndef NDEBUG
+  DWORD tid = GetCurrentThreadId(); 
+#endif
+  int rc = SQLITE_BUSY;
+  assert( p->id==SQLITE_MUTEX_RECURSIVE || winMutexNotheld2(p, tid) );
+  /*
+  ** The sqlite3_mutex_try() routine is very rarely used, and when it
+  ** is used it is merely an optimization.  So it is OK for it to always
+  ** fail.  
+  **
+  ** The TryEnterCriticalSection() interface is only available on WinNT.
+  ** And some windows compilers complain if you try to use it without
+  ** first doing some #defines that prevent SQLite from building on Win98.
+  ** For that reason, we will omit this optimization for now.  See
+  ** ticket #2685.
+  */
+#if 0
+  if( mutexIsNT() && TryEnterCriticalSection(&p->mutex) ){
+    p->owner = tid;
+    p->nRef++;
+    rc = SQLITE_OK;
+  }
+#else
+  UNUSED_PARAMETER(p);
+#endif
+#ifdef SQLITE_DEBUG
+  if( rc==SQLITE_OK && p->trace ){
+    printf("try mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef);
+  }
+#endif
+  return rc;
+}
+
+/*
+** The sqlite3_mutex_leave() routine exits a mutex that was
+** previously entered by the same thread.  The behavior
+** is undefined if the mutex is not currently entered or
+** is not currently allocated.  SQLite will never do either.
+*/
+static void winMutexLeave(sqlite3_mutex *p){
+#ifndef NDEBUG
+  DWORD tid = GetCurrentThreadId();
+  assert( p->nRef>0 );
+  assert( p->owner==tid );
+  p->nRef--;
+  if( p->nRef==0 ) p->owner = 0;
+  assert( p->nRef==0 || p->id==SQLITE_MUTEX_RECURSIVE );
+#endif
+  LeaveCriticalSection(&p->mutex);
+#ifdef SQLITE_DEBUG
+  if( p->trace ){
+    printf("leave mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef);
+  }
+#endif
+}
+
+SQLITE_PRIVATE sqlite3_mutex_methods const *sqlite3DefaultMutex(void){
+  static const sqlite3_mutex_methods sMutex = {
+    winMutexInit,
+    winMutexEnd,
+    winMutexAlloc,
+    winMutexFree,
+    winMutexEnter,
+    winMutexTry,
+    winMutexLeave,
+#ifdef SQLITE_DEBUG
+    winMutexHeld,
+    winMutexNotheld
+#else
+    0,
+    0
+#endif
+  };
+
+  return &sMutex;
+}
+#endif /* SQLITE_MUTEX_W32 */
+
+/************** End of mutex_w32.c *******************************************/
+/************** Begin file malloc.c ******************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** Memory allocation functions used throughout sqlite.
+*/
+
+/*
+** Attempt to release up to n bytes of non-essential memory currently
+** held by SQLite. An example of non-essential memory is memory used to
+** cache database pages that are not currently in use.
+*/
+SQLITE_API int sqlite3_release_memory(int n){
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+  return sqlite3PcacheReleaseMemory(n);
+#else
+  /* IMPLEMENTATION-OF: R-34391-24921 The sqlite3_release_memory() routine
+  ** is a no-op returning zero if SQLite is not compiled with
+  ** SQLITE_ENABLE_MEMORY_MANAGEMENT. */
+  UNUSED_PARAMETER(n);
+  return 0;
+#endif
+}
+
+/*
+** An instance of the following object records the location of
+** each unused scratch buffer.
+*/
+typedef struct ScratchFreeslot {
+  struct ScratchFreeslot *pNext;   /* Next unused scratch buffer */
+} ScratchFreeslot;
+
+/*
+** State information local to the memory allocation subsystem.
+*/
+static SQLITE_WSD struct Mem0Global {
+  sqlite3_mutex *mutex;         /* Mutex to serialize access */
+
+  /*
+  ** The alarm callback and its arguments.  The mem0.mutex lock will
+  ** be held while the callback is running.  Recursive calls into
+  ** the memory subsystem are allowed, but no new callbacks will be
+  ** issued.
+  */
+  sqlite3_int64 alarmThreshold;
+  void (*alarmCallback)(void*, sqlite3_int64,int);
+  void *alarmArg;
+
+  /*
+  ** Pointers to the end of sqlite3GlobalConfig.pScratch memory
+  ** (so that a range test can be used to determine if an allocation
+  ** being freed came from pScratch) and a pointer to the list of
+  ** unused scratch allocations.
+  */
+  void *pScratchEnd;
+  ScratchFreeslot *pScratchFree;
+  u32 nScratchFree;
+
+  /*
+  ** True if heap is nearly "full" where "full" is defined by the
+  ** sqlite3_soft_heap_limit() setting.
+  */
+  int nearlyFull;
+} mem0 = { 0, 0, 0, 0, 0, 0, 0, 0 };
+
+#define mem0 GLOBAL(struct Mem0Global, mem0)
+
+/*
+** This routine runs when the memory allocator sees that the
+** total memory allocation is about to exceed the soft heap
+** limit.
+*/
+static void softHeapLimitEnforcer(
+  void *NotUsed, 
+  sqlite3_int64 NotUsed2,
+  int allocSize
+){
+  UNUSED_PARAMETER2(NotUsed, NotUsed2);
+  sqlite3_release_memory(allocSize);
+}
+
+/*
+** Change the alarm callback
+*/
+static int sqlite3MemoryAlarm(
+  void(*xCallback)(void *pArg, sqlite3_int64 used,int N),
+  void *pArg,
+  sqlite3_int64 iThreshold
+){
+  int nUsed;
+  sqlite3_mutex_enter(mem0.mutex);
+  mem0.alarmCallback = xCallback;
+  mem0.alarmArg = pArg;
+  mem0.alarmThreshold = iThreshold;
+  nUsed = sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED);
+  mem0.nearlyFull = (iThreshold>0 && iThreshold<=nUsed);
+  sqlite3_mutex_leave(mem0.mutex);
+  return SQLITE_OK;
+}
+
+#ifndef SQLITE_OMIT_DEPRECATED
+/*
+** Deprecated external interface.  Internal/core SQLite code
+** should call sqlite3MemoryAlarm.
+*/
+SQLITE_API int sqlite3_memory_alarm(
+  void(*xCallback)(void *pArg, sqlite3_int64 used,int N),
+  void *pArg,
+  sqlite3_int64 iThreshold
+){
+  return sqlite3MemoryAlarm(xCallback, pArg, iThreshold);
+}
+#endif
+
+/*
+** Set the soft heap-size limit for the library. Passing a zero or 
+** negative value indicates no limit.
+*/
+SQLITE_API sqlite3_int64 sqlite3_soft_heap_limit64(sqlite3_int64 n){
+  sqlite3_int64 priorLimit;
+  sqlite3_int64 excess;
+#ifndef SQLITE_OMIT_AUTOINIT
+  sqlite3_initialize();
+#endif
+  sqlite3_mutex_enter(mem0.mutex);
+  priorLimit = mem0.alarmThreshold;
+  sqlite3_mutex_leave(mem0.mutex);
+  if( n<0 ) return priorLimit;
+  if( n>0 ){
+    sqlite3MemoryAlarm(softHeapLimitEnforcer, 0, n);
+  }else{
+    sqlite3MemoryAlarm(0, 0, 0);
+  }
+  excess = sqlite3_memory_used() - n;
+  if( excess>0 ) sqlite3_release_memory((int)(excess & 0x7fffffff));
+  return priorLimit;
+}
+SQLITE_API void sqlite3_soft_heap_limit(int n){
+  if( n<0 ) n = 0;
+  sqlite3_soft_heap_limit64(n);
+}
+
+/*
+** Initialize the memory allocation subsystem.
+*/
+SQLITE_PRIVATE int sqlite3MallocInit(void){
+  if( sqlite3GlobalConfig.m.xMalloc==0 ){
+    sqlite3MemSetDefault();
+  }
+  memset(&mem0, 0, sizeof(mem0));
+  if( sqlite3GlobalConfig.bCoreMutex ){
+    mem0.mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM);
+  }
+  if( sqlite3GlobalConfig.pScratch && sqlite3GlobalConfig.szScratch>=100
+      && sqlite3GlobalConfig.nScratch>0 ){
+    int i, n, sz;
+    ScratchFreeslot *pSlot;
+    sz = ROUNDDOWN8(sqlite3GlobalConfig.szScratch);
+    sqlite3GlobalConfig.szScratch = sz;
+    pSlot = (ScratchFreeslot*)sqlite3GlobalConfig.pScratch;
+    n = sqlite3GlobalConfig.nScratch;
+    mem0.pScratchFree = pSlot;
+    mem0.nScratchFree = n;
+    for(i=0; i<n-1; i++){
+      pSlot->pNext = (ScratchFreeslot*)(sz+(char*)pSlot);
+      pSlot = pSlot->pNext;
+    }
+    pSlot->pNext = 0;
+    mem0.pScratchEnd = (void*)&pSlot[1];
+  }else{
+    mem0.pScratchEnd = 0;
+    sqlite3GlobalConfig.pScratch = 0;
+    sqlite3GlobalConfig.szScratch = 0;
+    sqlite3GlobalConfig.nScratch = 0;
+  }
+  if( sqlite3GlobalConfig.pPage==0 || sqlite3GlobalConfig.szPage<512
+      || sqlite3GlobalConfig.nPage<1 ){
+    sqlite3GlobalConfig.pPage = 0;
+    sqlite3GlobalConfig.szPage = 0;
+    sqlite3GlobalConfig.nPage = 0;
+  }
+  return sqlite3GlobalConfig.m.xInit(sqlite3GlobalConfig.m.pAppData);
+}
+
+/*
+** Return true if the heap is currently under memory pressure - in other
+** words if the amount of heap used is close to the limit set by
+** sqlite3_soft_heap_limit().
+*/
+SQLITE_PRIVATE int sqlite3HeapNearlyFull(void){
+  return mem0.nearlyFull;
+}
+
+/*
+** Deinitialize the memory allocation subsystem.
+*/
+SQLITE_PRIVATE void sqlite3MallocEnd(void){
+  if( sqlite3GlobalConfig.m.xShutdown ){
+    sqlite3GlobalConfig.m.xShutdown(sqlite3GlobalConfig.m.pAppData);
+  }
+  memset(&mem0, 0, sizeof(mem0));
+}
+
+/*
+** Return the amount of memory currently checked out.
+*/
+SQLITE_API sqlite3_int64 sqlite3_memory_used(void){
+  int n, mx;
+  sqlite3_int64 res;
+  sqlite3_status(SQLITE_STATUS_MEMORY_USED, &n, &mx, 0);
+  res = (sqlite3_int64)n;  /* Work around bug in Borland C. Ticket #3216 */
+  return res;
+}
+
+/*
+** Return the maximum amount of memory that has ever been
+** checked out since either the beginning of this process
+** or since the most recent reset.
+*/
+SQLITE_API sqlite3_int64 sqlite3_memory_highwater(int resetFlag){
+  int n, mx;
+  sqlite3_int64 res;
+  sqlite3_status(SQLITE_STATUS_MEMORY_USED, &n, &mx, resetFlag);
+  res = (sqlite3_int64)mx;  /* Work around bug in Borland C. Ticket #3216 */
+  return res;
+}
+
+/*
+** Trigger the alarm 
+*/
+static void sqlite3MallocAlarm(int nByte){
+  void (*xCallback)(void*,sqlite3_int64,int);
+  sqlite3_int64 nowUsed;
+  void *pArg;
+  if( mem0.alarmCallback==0 ) return;
+  xCallback = mem0.alarmCallback;
+  nowUsed = sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED);
+  pArg = mem0.alarmArg;
+  mem0.alarmCallback = 0;
+  sqlite3_mutex_leave(mem0.mutex);
+  xCallback(pArg, nowUsed, nByte);
+  sqlite3_mutex_enter(mem0.mutex);
+  mem0.alarmCallback = xCallback;
+  mem0.alarmArg = pArg;
+}
+
+/*
+** Do a memory allocation with statistics and alarms.  Assume the
+** lock is already held.
+*/
+static int mallocWithAlarm(int n, void **pp){
+  int nFull;
+  void *p;
+  assert( sqlite3_mutex_held(mem0.mutex) );
+  nFull = sqlite3GlobalConfig.m.xRoundup(n);
+  sqlite3StatusSet(SQLITE_STATUS_MALLOC_SIZE, n);
+  if( mem0.alarmCallback!=0 ){
+    int nUsed = sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED);
+    if( nUsed+nFull >= mem0.alarmThreshold ){
+      mem0.nearlyFull = 1;
+      sqlite3MallocAlarm(nFull);
+    }else{
+      mem0.nearlyFull = 0;
+    }
+  }
+  p = sqlite3GlobalConfig.m.xMalloc(nFull);
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+  if( p==0 && mem0.alarmCallback ){
+    sqlite3MallocAlarm(nFull);
+    p = sqlite3GlobalConfig.m.xMalloc(nFull);
+  }
+#endif
+  if( p ){
+    nFull = sqlite3MallocSize(p);
+    sqlite3StatusAdd(SQLITE_STATUS_MEMORY_USED, nFull);
+    sqlite3StatusAdd(SQLITE_STATUS_MALLOC_COUNT, 1);
+  }
+  *pp = p;
+  return nFull;
+}
+
+/*
+** Allocate memory.  This routine is like sqlite3_malloc() except that it
+** assumes the memory subsystem has already been initialized.
+*/
+SQLITE_PRIVATE void *sqlite3Malloc(int n){
+  void *p;
+  if( n<=0               /* IMP: R-65312-04917 */ 
+   || n>=0x7fffff00
+  ){
+    /* A memory allocation of a number of bytes which is near the maximum
+    ** signed integer value might cause an integer overflow inside of the
+    ** xMalloc().  Hence we limit the maximum size to 0x7fffff00, giving
+    ** 255 bytes of overhead.  SQLite itself will never use anything near
+    ** this amount.  The only way to reach the limit is with sqlite3_malloc() */
+    p = 0;
+  }else if( sqlite3GlobalConfig.bMemstat ){
+    sqlite3_mutex_enter(mem0.mutex);
+    mallocWithAlarm(n, &p);
+    sqlite3_mutex_leave(mem0.mutex);
+  }else{
+    p = sqlite3GlobalConfig.m.xMalloc(n);
+  }
+  assert( EIGHT_BYTE_ALIGNMENT(p) );  /* IMP: R-04675-44850 */
+  return p;
+}
+
+/*
+** This version of the memory allocation is for use by the application.
+** First make sure the memory subsystem is initialized, then do the
+** allocation.
+*/
+SQLITE_API void *sqlite3_malloc(int n){
+#ifndef SQLITE_OMIT_AUTOINIT
+  if( sqlite3_initialize() ) return 0;
+#endif
+  return sqlite3Malloc(n);
+}
+
+/*
+** Each thread may only have a single outstanding allocation from
+** xScratchMalloc().  We verify this constraint in the single-threaded
+** case by setting scratchAllocOut to 1 when an allocation
+** is outstanding clearing it when the allocation is freed.
+*/
+#if SQLITE_THREADSAFE==0 && !defined(NDEBUG)
+static int scratchAllocOut = 0;
+#endif
+
+
+/*
+** Allocate memory that is to be used and released right away.
+** This routine is similar to alloca() in that it is not intended
+** for situations where the memory might be held long-term.  This
+** routine is intended to get memory to old large transient data
+** structures that would not normally fit on the stack of an
+** embedded processor.
+*/
+SQLITE_PRIVATE void *sqlite3ScratchMalloc(int n){
+  void *p;
+  assert( n>0 );
+
+  sqlite3_mutex_enter(mem0.mutex);
+  if( mem0.nScratchFree && sqlite3GlobalConfig.szScratch>=n ){
+    p = mem0.pScratchFree;
+    mem0.pScratchFree = mem0.pScratchFree->pNext;
+    mem0.nScratchFree--;
+    sqlite3StatusAdd(SQLITE_STATUS_SCRATCH_USED, 1);
+    sqlite3StatusSet(SQLITE_STATUS_SCRATCH_SIZE, n);
+    sqlite3_mutex_leave(mem0.mutex);
+  }else{
+    if( sqlite3GlobalConfig.bMemstat ){
+      sqlite3StatusSet(SQLITE_STATUS_SCRATCH_SIZE, n);
+      n = mallocWithAlarm(n, &p);
+      if( p ) sqlite3StatusAdd(SQLITE_STATUS_SCRATCH_OVERFLOW, n);
+      sqlite3_mutex_leave(mem0.mutex);
+    }else{
+      sqlite3_mutex_leave(mem0.mutex);
+      p = sqlite3GlobalConfig.m.xMalloc(n);
+    }
+    sqlite3MemdebugSetType(p, MEMTYPE_SCRATCH);
+  }
+  assert( sqlite3_mutex_notheld(mem0.mutex) );
+
+
+#if SQLITE_THREADSAFE==0 && !defined(NDEBUG)
+  /* Verify that no more than two scratch allocations per thread
+  ** are outstanding at one time.  (This is only checked in the
+  ** single-threaded case since checking in the multi-threaded case
+  ** would be much more complicated.) */
+  assert( scratchAllocOut<=1 );
+  if( p ) scratchAllocOut++;
+#endif
+
+  return p;
+}
+SQLITE_PRIVATE void sqlite3ScratchFree(void *p){
+  if( p ){
+
+#if SQLITE_THREADSAFE==0 && !defined(NDEBUG)
+    /* Verify that no more than two scratch allocation per thread
+    ** is outstanding at one time.  (This is only checked in the
+    ** single-threaded case since checking in the multi-threaded case
+    ** would be much more complicated.) */
+    assert( scratchAllocOut>=1 && scratchAllocOut<=2 );
+    scratchAllocOut--;
+#endif
+
+    if( p>=sqlite3GlobalConfig.pScratch && p<mem0.pScratchEnd ){
+      /* Release memory from the SQLITE_CONFIG_SCRATCH allocation */
+      ScratchFreeslot *pSlot;
+      pSlot = (ScratchFreeslot*)p;
+      sqlite3_mutex_enter(mem0.mutex);
+      pSlot->pNext = mem0.pScratchFree;
+      mem0.pScratchFree = pSlot;
+      mem0.nScratchFree++;
+      assert( mem0.nScratchFree <= (u32)sqlite3GlobalConfig.nScratch );
+      sqlite3StatusAdd(SQLITE_STATUS_SCRATCH_USED, -1);
+      sqlite3_mutex_leave(mem0.mutex);
+    }else{
+      /* Release memory back to the heap */
+      assert( sqlite3MemdebugHasType(p, MEMTYPE_SCRATCH) );
+      assert( sqlite3MemdebugNoType(p, ~MEMTYPE_SCRATCH) );
+      sqlite3MemdebugSetType(p, MEMTYPE_HEAP);
+      if( sqlite3GlobalConfig.bMemstat ){
+        int iSize = sqlite3MallocSize(p);
+        sqlite3_mutex_enter(mem0.mutex);
+        sqlite3StatusAdd(SQLITE_STATUS_SCRATCH_OVERFLOW, -iSize);
+        sqlite3StatusAdd(SQLITE_STATUS_MEMORY_USED, -iSize);
+        sqlite3StatusAdd(SQLITE_STATUS_MALLOC_COUNT, -1);
+        sqlite3GlobalConfig.m.xFree(p);
+        sqlite3_mutex_leave(mem0.mutex);
+      }else{
+        sqlite3GlobalConfig.m.xFree(p);
+      }
+    }
+  }
+}
+
+/*
+** TRUE if p is a lookaside memory allocation from db
+*/
+#ifndef SQLITE_OMIT_LOOKASIDE
+static int isLookaside(sqlite3 *db, void *p){
+  return p && p>=db->lookaside.pStart && p<db->lookaside.pEnd;
+}
+#else
+#define isLookaside(A,B) 0
+#endif
+
+/*
+** Return the size of a memory allocation previously obtained from
+** sqlite3Malloc() or sqlite3_malloc().
+*/
+SQLITE_PRIVATE int sqlite3MallocSize(void *p){
+  assert( sqlite3MemdebugHasType(p, MEMTYPE_HEAP) );
+  assert( sqlite3MemdebugNoType(p, MEMTYPE_DB) );
+  return sqlite3GlobalConfig.m.xSize(p);
+}
+SQLITE_PRIVATE int sqlite3DbMallocSize(sqlite3 *db, void *p){
+  assert( db==0 || sqlite3_mutex_held(db->mutex) );
+  if( db && isLookaside(db, p) ){
+    return db->lookaside.sz;
+  }else{
+    assert( sqlite3MemdebugHasType(p, MEMTYPE_DB) );
+    assert( sqlite3MemdebugHasType(p, MEMTYPE_LOOKASIDE|MEMTYPE_HEAP) );
+    assert( db!=0 || sqlite3MemdebugNoType(p, MEMTYPE_LOOKASIDE) );
+    return sqlite3GlobalConfig.m.xSize(p);
+  }
+}
+
+/*
+** Free memory previously obtained from sqlite3Malloc().
+*/
+SQLITE_API void sqlite3_free(void *p){
+  if( p==0 ) return;  /* IMP: R-49053-54554 */
+  assert( sqlite3MemdebugNoType(p, MEMTYPE_DB) );
+  assert( sqlite3MemdebugHasType(p, MEMTYPE_HEAP) );
+  if( sqlite3GlobalConfig.bMemstat ){
+    sqlite3_mutex_enter(mem0.mutex);
+    sqlite3StatusAdd(SQLITE_STATUS_MEMORY_USED, -sqlite3MallocSize(p));
+    sqlite3StatusAdd(SQLITE_STATUS_MALLOC_COUNT, -1);
+    sqlite3GlobalConfig.m.xFree(p);
+    sqlite3_mutex_leave(mem0.mutex);
+  }else{
+    sqlite3GlobalConfig.m.xFree(p);
+  }
+}
+
+/*
+** Free memory that might be associated with a particular database
+** connection.
+*/
+SQLITE_PRIVATE void sqlite3DbFree(sqlite3 *db, void *p){
+  assert( db==0 || sqlite3_mutex_held(db->mutex) );
+  if( db ){
+    if( db->pnBytesFreed ){
+      *db->pnBytesFreed += sqlite3DbMallocSize(db, p);
+      return;
+    }
+    if( isLookaside(db, p) ){
+      LookasideSlot *pBuf = (LookasideSlot*)p;
+      pBuf->pNext = db->lookaside.pFree;
+      db->lookaside.pFree = pBuf;
+      db->lookaside.nOut--;
+      return;
+    }
+  }
+  assert( sqlite3MemdebugHasType(p, MEMTYPE_DB) );
+  assert( sqlite3MemdebugHasType(p, MEMTYPE_LOOKASIDE|MEMTYPE_HEAP) );
+  assert( db!=0 || sqlite3MemdebugNoType(p, MEMTYPE_LOOKASIDE) );
+  sqlite3MemdebugSetType(p, MEMTYPE_HEAP);
+  sqlite3_free(p);
+}
+
+/*
+** Change the size of an existing memory allocation
+*/
+SQLITE_PRIVATE void *sqlite3Realloc(void *pOld, int nBytes){
+  int nOld, nNew;
+  void *pNew;
+  if( pOld==0 ){
+    return sqlite3Malloc(nBytes); /* IMP: R-28354-25769 */
+  }
+  if( nBytes<=0 ){
+    sqlite3_free(pOld); /* IMP: R-31593-10574 */
+    return 0;
+  }
+  if( nBytes>=0x7fffff00 ){
+    /* The 0x7ffff00 limit term is explained in comments on sqlite3Malloc() */
+    return 0;
+  }
+  nOld = sqlite3MallocSize(pOld);
+  /* IMPLEMENTATION-OF: R-46199-30249 SQLite guarantees that the second
+  ** argument to xRealloc is always a value returned by a prior call to
+  ** xRoundup. */
+  nNew = sqlite3GlobalConfig.m.xRoundup(nBytes);
+  if( nOld==nNew ){
+    pNew = pOld;
+  }else if( sqlite3GlobalConfig.bMemstat ){
+    sqlite3_mutex_enter(mem0.mutex);
+    sqlite3StatusSet(SQLITE_STATUS_MALLOC_SIZE, nBytes);
+    if( sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED)+nNew-nOld >= 
+          mem0.alarmThreshold ){
+      sqlite3MallocAlarm(nNew-nOld);
+    }
+    assert( sqlite3MemdebugHasType(pOld, MEMTYPE_HEAP) );
+    assert( sqlite3MemdebugNoType(pOld, ~MEMTYPE_HEAP) );
+    pNew = sqlite3GlobalConfig.m.xRealloc(pOld, nNew);
+    if( pNew==0 && mem0.alarmCallback ){
+      sqlite3MallocAlarm(nBytes);
+      pNew = sqlite3GlobalConfig.m.xRealloc(pOld, nNew);
+    }
+    if( pNew ){
+      nNew = sqlite3MallocSize(pNew);
+      sqlite3StatusAdd(SQLITE_STATUS_MEMORY_USED, nNew-nOld);
+    }
+    sqlite3_mutex_leave(mem0.mutex);
+  }else{
+    pNew = sqlite3GlobalConfig.m.xRealloc(pOld, nNew);
+  }
+  assert( EIGHT_BYTE_ALIGNMENT(pNew) ); /* IMP: R-04675-44850 */
+  return pNew;
+}
+
+/*
+** The public interface to sqlite3Realloc.  Make sure that the memory
+** subsystem is initialized prior to invoking sqliteRealloc.
+*/
+SQLITE_API void *sqlite3_realloc(void *pOld, int n){
+#ifndef SQLITE_OMIT_AUTOINIT
+  if( sqlite3_initialize() ) return 0;
+#endif
+  return sqlite3Realloc(pOld, n);
+}
+
+
+/*
+** Allocate and zero memory.
+*/ 
+SQLITE_PRIVATE void *sqlite3MallocZero(int n){
+  void *p = sqlite3Malloc(n);
+  if( p ){
+    memset(p, 0, n);
+  }
+  return p;
+}
+
+/*
+** Allocate and zero memory.  If the allocation fails, make
+** the mallocFailed flag in the connection pointer.
+*/
+SQLITE_PRIVATE void *sqlite3DbMallocZero(sqlite3 *db, int n){
+  void *p = sqlite3DbMallocRaw(db, n);
+  if( p ){
+    memset(p, 0, n);
+  }
+  return p;
+}
+
+/*
+** Allocate and zero memory.  If the allocation fails, make
+** the mallocFailed flag in the connection pointer.
+**
+** If db!=0 and db->mallocFailed is true (indicating a prior malloc
+** failure on the same database connection) then always return 0.
+** Hence for a particular database connection, once malloc starts
+** failing, it fails consistently until mallocFailed is reset.
+** This is an important assumption.  There are many places in the
+** code that do things like this:
+**
+**         int *a = (int*)sqlite3DbMallocRaw(db, 100);
+**         int *b = (int*)sqlite3DbMallocRaw(db, 200);
+**         if( b ) a[10] = 9;
+**
+** In other words, if a subsequent malloc (ex: "b") worked, it is assumed
+** that all prior mallocs (ex: "a") worked too.
+*/
+SQLITE_PRIVATE void *sqlite3DbMallocRaw(sqlite3 *db, int n){
+  void *p;
+  assert( db==0 || sqlite3_mutex_held(db->mutex) );
+  assert( db==0 || db->pnBytesFreed==0 );
+#ifndef SQLITE_OMIT_LOOKASIDE
+  if( db ){
+    LookasideSlot *pBuf;
+    if( db->mallocFailed ){
+      return 0;
+    }
+    if( db->lookaside.bEnabled ){
+      if( n>db->lookaside.sz ){
+        db->lookaside.anStat[1]++;
+      }else if( (pBuf = db->lookaside.pFree)==0 ){
+        db->lookaside.anStat[2]++;
+      }else{
+        db->lookaside.pFree = pBuf->pNext;
+        db->lookaside.nOut++;
+        db->lookaside.anStat[0]++;
+        if( db->lookaside.nOut>db->lookaside.mxOut ){
+          db->lookaside.mxOut = db->lookaside.nOut;
+        }
+        return (void*)pBuf;
+      }
+    }
+  }
+#else
+  if( db && db->mallocFailed ){
+    return 0;
+  }
+#endif
+  p = sqlite3Malloc(n);
+  if( !p && db ){
+    db->mallocFailed = 1;
+  }
+  sqlite3MemdebugSetType(p, MEMTYPE_DB |
+         ((db && db->lookaside.bEnabled) ? MEMTYPE_LOOKASIDE : MEMTYPE_HEAP));
+  return p;
+}
+
+/*
+** Resize the block of memory pointed to by p to n bytes. If the
+** resize fails, set the mallocFailed flag in the connection object.
+*/
+SQLITE_PRIVATE void *sqlite3DbRealloc(sqlite3 *db, void *p, int n){
+  void *pNew = 0;
+  assert( db!=0 );
+  assert( sqlite3_mutex_held(db->mutex) );
+  if( db->mallocFailed==0 ){
+    if( p==0 ){
+      return sqlite3DbMallocRaw(db, n);
+    }
+    if( isLookaside(db, p) ){
+      if( n<=db->lookaside.sz ){
+        return p;
+      }
+      pNew = sqlite3DbMallocRaw(db, n);
+      if( pNew ){
+        memcpy(pNew, p, db->lookaside.sz);
+        sqlite3DbFree(db, p);
+      }
+    }else{
+      assert( sqlite3MemdebugHasType(p, MEMTYPE_DB) );
+      assert( sqlite3MemdebugHasType(p, MEMTYPE_LOOKASIDE|MEMTYPE_HEAP) );
+      sqlite3MemdebugSetType(p, MEMTYPE_HEAP);
+      pNew = sqlite3_realloc(p, n);
+      if( !pNew ){
+        sqlite3MemdebugSetType(p, MEMTYPE_DB|MEMTYPE_HEAP);
+        db->mallocFailed = 1;
+      }
+      sqlite3MemdebugSetType(pNew, MEMTYPE_DB | 
+            (db->lookaside.bEnabled ? MEMTYPE_LOOKASIDE : MEMTYPE_HEAP));
+    }
+  }
+  return pNew;
+}
+
+/*
+** Attempt to reallocate p.  If the reallocation fails, then free p
+** and set the mallocFailed flag in the database connection.
+*/
+SQLITE_PRIVATE void *sqlite3DbReallocOrFree(sqlite3 *db, void *p, int n){
+  void *pNew;
+  pNew = sqlite3DbRealloc(db, p, n);
+  if( !pNew ){
+    sqlite3DbFree(db, p);
+  }
+  return pNew;
+}
+
+/*
+** Make a copy of a string in memory obtained from sqliteMalloc(). These 
+** functions call sqlite3MallocRaw() directly instead of sqliteMalloc(). This
+** is because when memory debugging is turned on, these two functions are 
+** called via macros that record the current file and line number in the
+** ThreadData structure.
+*/
+SQLITE_PRIVATE char *sqlite3DbStrDup(sqlite3 *db, const char *z){
+  char *zNew;
+  size_t n;
+  if( z==0 ){
+    return 0;
+  }
+  n = sqlite3Strlen30(z) + 1;
+  assert( (n&0x7fffffff)==n );
+  zNew = sqlite3DbMallocRaw(db, (int)n);
+  if( zNew ){
+    memcpy(zNew, z, n);
+  }
+  return zNew;
+}
+SQLITE_PRIVATE char *sqlite3DbStrNDup(sqlite3 *db, const char *z, int n){
+  char *zNew;
+  if( z==0 ){
+    return 0;
+  }
+  assert( (n&0x7fffffff)==n );
+  zNew = sqlite3DbMallocRaw(db, n+1);
+  if( zNew ){
+    memcpy(zNew, z, n);
+    zNew[n] = 0;
+  }
+  return zNew;
+}
+
+/*
+** Create a string from the zFromat argument and the va_list that follows.
+** Store the string in memory obtained from sqliteMalloc() and make *pz
+** point to that string.
+*/
+SQLITE_PRIVATE void sqlite3SetString(char **pz, sqlite3 *db, const char *zFormat, ...){
+  va_list ap;
+  char *z;
+
+  va_start(ap, zFormat);
+  z = sqlite3VMPrintf(db, zFormat, ap);
+  va_end(ap);
+  sqlite3DbFree(db, *pz);
+  *pz = z;
+}
+
+
+/*
+** This function must be called before exiting any API function (i.e. 
+** returning control to the user) that has called sqlite3_malloc or
+** sqlite3_realloc.
+**
+** The returned value is normally a copy of the second argument to this
+** function. However, if a malloc() failure has occurred since the previous
+** invocation SQLITE_NOMEM is returned instead. 
+**
+** If the first argument, db, is not NULL and a malloc() error has occurred,
+** then the connection error-code (the value returned by sqlite3_errcode())
+** is set to SQLITE_NOMEM.
+*/
+SQLITE_PRIVATE int sqlite3ApiExit(sqlite3* db, int rc){
+  /* If the db handle is not NULL, then we must hold the connection handle
+  ** mutex here. Otherwise the read (and possible write) of db->mallocFailed 
+  ** is unsafe, as is the call to sqlite3Error().
+  */
+  assert( !db || sqlite3_mutex_held(db->mutex) );
+  if( db && (db->mallocFailed || rc==SQLITE_IOERR_NOMEM) ){
+    sqlite3Error(db, SQLITE_NOMEM, 0);
+    db->mallocFailed = 0;
+    rc = SQLITE_NOMEM;
+  }
+  return rc & (db ? db->errMask : 0xff);
+}
+
+/************** End of malloc.c **********************************************/
+/************** Begin file printf.c ******************************************/
+/*
+** The "printf" code that follows dates from the 1980's.  It is in
+** the public domain.  The original comments are included here for
+** completeness.  They are very out-of-date but might be useful as
+** an historical reference.  Most of the "enhancements" have been backed
+** out so that the functionality is now the same as standard printf().
+**
+**************************************************************************
+**
+** The following modules is an enhanced replacement for the "printf" subroutines
+** found in the standard C library.  The following enhancements are
+** supported:
+**
+**      +  Additional functions.  The standard set of "printf" functions
+**         includes printf, fprintf, sprintf, vprintf, vfprintf, and
+**         vsprintf.  This module adds the following:
+**
+**           *  snprintf -- Works like sprintf, but has an extra argument
+**                          which is the size of the buffer written to.
+**
+**           *  mprintf --  Similar to sprintf.  Writes output to memory
+**                          obtained from malloc.
+**
+**           *  xprintf --  Calls a function to dispose of output.
+**
+**           *  nprintf --  No output, but returns the number of characters
+**                          that would have been output by printf.
+**
+**           *  A v- version (ex: vsnprintf) of every function is also
+**              supplied.
+**
+**      +  A few extensions to the formatting notation are supported:
+**
+**           *  The "=" flag (similar to "-") causes the output to be
+**              be centered in the appropriately sized field.
+**
+**           *  The %b field outputs an integer in binary notation.
+**
+**           *  The %c field now accepts a precision.  The character output
+**              is repeated by the number of times the precision specifies.
+**
+**           *  The %' field works like %c, but takes as its character the
+**              next character of the format string, instead of the next
+**              argument.  For example,  printf("%.78'-")  prints 78 minus
+**              signs, the same as  printf("%.78c",'-').
+**
+**      +  When compiled using GCC on a SPARC, this version of printf is
+**         faster than the library printf for SUN OS 4.1.
+**
+**      +  All functions are fully reentrant.
+**
+*/
+
+/*
+** Conversion types fall into various categories as defined by the
+** following enumeration.
+*/
+#define etRADIX       1 /* Integer types.  %d, %x, %o, and so forth */
+#define etFLOAT       2 /* Floating point.  %f */
+#define etEXP         3 /* Exponentional notation. %e and %E */
+#define etGENERIC     4 /* Floating or exponential, depending on exponent. %g */
+#define etSIZE        5 /* Return number of characters processed so far. %n */
+#define etSTRING      6 /* Strings. %s */
+#define etDYNSTRING   7 /* Dynamically allocated strings. %z */
+#define etPERCENT     8 /* Percent symbol. %% */
+#define etCHARX       9 /* Characters. %c */
+/* The rest are extensions, not normally found in printf() */
+#define etSQLESCAPE  10 /* Strings with '\'' doubled.  %q */
+#define etSQLESCAPE2 11 /* Strings with '\'' doubled and enclosed in '',
+                          NULL pointers replaced by SQL NULL.  %Q */
+#define etTOKEN      12 /* a pointer to a Token structure */
+#define etSRCLIST    13 /* a pointer to a SrcList */
+#define etPOINTER    14 /* The %p conversion */
+#define etSQLESCAPE3 15 /* %w -> Strings with '\"' doubled */
+#define etORDINAL    16 /* %r -> 1st, 2nd, 3rd, 4th, etc.  English only */
+
+#define etINVALID     0 /* Any unrecognized conversion type */
+
+
+/*
+** An "etByte" is an 8-bit unsigned value.
+*/
+typedef unsigned char etByte;
+
+/*
+** Each builtin conversion character (ex: the 'd' in "%d") is described
+** by an instance of the following structure
+*/
+typedef struct et_info {   /* Information about each format field */
+  char fmttype;            /* The format field code letter */
+  etByte base;             /* The base for radix conversion */
+  etByte flags;            /* One or more of FLAG_ constants below */
+  etByte type;             /* Conversion paradigm */
+  etByte charset;          /* Offset into aDigits[] of the digits string */
+  etByte prefix;           /* Offset into aPrefix[] of the prefix string */
+} et_info;
+
+/*
+** Allowed values for et_info.flags
+*/
+#define FLAG_SIGNED  1     /* True if the value to convert is signed */
+#define FLAG_INTERN  2     /* True if for internal use only */
+#define FLAG_STRING  4     /* Allow infinity precision */
+
+
+/*
+** The following table is searched linearly, so it is good to put the
+** most frequently used conversion types first.
+*/
+static const char aDigits[] = "0123456789ABCDEF0123456789abcdef";
+static const char aPrefix[] = "-x0\000X0";
+static const et_info fmtinfo[] = {
+  {  'd', 10, 1, etRADIX,      0,  0 },
+  {  's',  0, 4, etSTRING,     0,  0 },
+  {  'g',  0, 1, etGENERIC,    30, 0 },
+  {  'z',  0, 4, etDYNSTRING,  0,  0 },
+  {  'q',  0, 4, etSQLESCAPE,  0,  0 },
+  {  'Q',  0, 4, etSQLESCAPE2, 0,  0 },
+  {  'w',  0, 4, etSQLESCAPE3, 0,  0 },
+  {  'c',  0, 0, etCHARX,      0,  0 },
+  {  'o',  8, 0, etRADIX,      0,  2 },
+  {  'u', 10, 0, etRADIX,      0,  0 },
+  {  'x', 16, 0, etRADIX,      16, 1 },
+  {  'X', 16, 0, etRADIX,      0,  4 },
+#ifndef SQLITE_OMIT_FLOATING_POINT
+  {  'f',  0, 1, etFLOAT,      0,  0 },
+  {  'e',  0, 1, etEXP,        30, 0 },
+  {  'E',  0, 1, etEXP,        14, 0 },
+  {  'G',  0, 1, etGENERIC,    14, 0 },
+#endif
+  {  'i', 10, 1, etRADIX,      0,  0 },
+  {  'n',  0, 0, etSIZE,       0,  0 },
+  {  '%',  0, 0, etPERCENT,    0,  0 },
+  {  'p', 16, 0, etPOINTER,    0,  1 },
+
+/* All the rest have the FLAG_INTERN bit set and are thus for internal
+** use only */
+  {  'T',  0, 2, etTOKEN,      0,  0 },
+  {  'S',  0, 2, etSRCLIST,    0,  0 },
+  {  'r', 10, 3, etORDINAL,    0,  0 },
+};
+
+/*
+** If SQLITE_OMIT_FLOATING_POINT is defined, then none of the floating point
+** conversions will work.
+*/
+#ifndef SQLITE_OMIT_FLOATING_POINT
+/*
+** "*val" is a double such that 0.1 <= *val < 10.0
+** Return the ascii code for the leading digit of *val, then
+** multiply "*val" by 10.0 to renormalize.
+**
+** Example:
+**     input:     *val = 3.14159
+**     output:    *val = 1.4159    function return = '3'
+**
+** The counter *cnt is incremented each time.  After counter exceeds
+** 16 (the number of significant digits in a 64-bit float) '0' is
+** always returned.
+*/
+static char et_getdigit(LONGDOUBLE_TYPE *val, int *cnt){
+  int digit;
+  LONGDOUBLE_TYPE d;
+  if( (*cnt)++ >= 16 ) return '0';
+  digit = (int)*val;
+  d = digit;
+  digit += '0';
+  *val = (*val - d)*10.0;
+  return (char)digit;
+}
+#endif /* SQLITE_OMIT_FLOATING_POINT */
+
+/*
+** Append N space characters to the given string buffer.
+*/
+static void appendSpace(StrAccum *pAccum, int N){
+  static const char zSpaces[] = "                             ";
+  while( N>=(int)sizeof(zSpaces)-1 ){
+    sqlite3StrAccumAppend(pAccum, zSpaces, sizeof(zSpaces)-1);
+    N -= sizeof(zSpaces)-1;
+  }
+  if( N>0 ){
+    sqlite3StrAccumAppend(pAccum, zSpaces, N);
+  }
+}
+
+/*
+** On machines with a small stack size, you can redefine the
+** SQLITE_PRINT_BUF_SIZE to be less than 350.
+*/
+#ifndef SQLITE_PRINT_BUF_SIZE
+# if defined(SQLITE_SMALL_STACK)
+#   define SQLITE_PRINT_BUF_SIZE 50
+# else
+#   define SQLITE_PRINT_BUF_SIZE 350
+# endif
+#endif
+#define etBUFSIZE SQLITE_PRINT_BUF_SIZE  /* Size of the output buffer */
+
+/*
+** The root program.  All variations call this core.
+**
+** INPUTS:
+**   func   This is a pointer to a function taking three arguments
+**            1. A pointer to anything.  Same as the "arg" parameter.
+**            2. A pointer to the list of characters to be output
+**               (Note, this list is NOT null terminated.)
+**            3. An integer number of characters to be output.
+**               (Note: This number might be zero.)
+**
+**   arg    This is the pointer to anything which will be passed as the
+**          first argument to "func".  Use it for whatever you like.
+**
+**   fmt    This is the format string, as in the usual print.
+**
+**   ap     This is a pointer to a list of arguments.  Same as in
+**          vfprint.
+**
+** OUTPUTS:
+**          The return value is the total number of characters sent to
+**          the function "func".  Returns -1 on a error.
+**
+** Note that the order in which automatic variables are declared below
+** seems to make a big difference in determining how fast this beast
+** will run.
+*/
+SQLITE_PRIVATE void sqlite3VXPrintf(
+  StrAccum *pAccum,                  /* Accumulate results here */
+  int useExtended,                   /* Allow extended %-conversions */
+  const char *fmt,                   /* Format string */
+  va_list ap                         /* arguments */
+){
+  int c;                     /* Next character in the format string */
+  char *bufpt;               /* Pointer to the conversion buffer */
+  int precision;             /* Precision of the current field */
+  int length;                /* Length of the field */
+  int idx;                   /* A general purpose loop counter */
+  int width;                 /* Width of the current field */
+  etByte flag_leftjustify;   /* True if "-" flag is present */
+  etByte flag_plussign;      /* True if "+" flag is present */
+  etByte flag_blanksign;     /* True if " " flag is present */
+  etByte flag_alternateform; /* True if "#" flag is present */
+  etByte flag_altform2;      /* True if "!" flag is present */
+  etByte flag_zeropad;       /* True if field width constant starts with zero */
+  etByte flag_long;          /* True if "l" flag is present */
+  etByte flag_longlong;      /* True if the "ll" flag is present */
+  etByte done;               /* Loop termination flag */
+  sqlite_uint64 longvalue;   /* Value for integer types */
+  LONGDOUBLE_TYPE realvalue; /* Value for real types */
+  const et_info *infop;      /* Pointer to the appropriate info structure */
+  char buf[etBUFSIZE];       /* Conversion buffer */
+  char prefix;               /* Prefix character.  "+" or "-" or " " or '\0'. */
+  etByte xtype = 0;          /* Conversion paradigm */
+  char *zExtra;              /* Extra memory used for etTCLESCAPE conversions */
+#ifndef SQLITE_OMIT_FLOATING_POINT
+  int  exp, e2;              /* exponent of real numbers */
+  double rounder;            /* Used for rounding floating point values */
+  etByte flag_dp;            /* True if decimal point should be shown */
+  etByte flag_rtz;           /* True if trailing zeros should be removed */
+  etByte flag_exp;           /* True to force display of the exponent */
+  int nsd;                   /* Number of significant digits returned */
+#endif
+
+  length = 0;
+  bufpt = 0;
+  for(; (c=(*fmt))!=0; ++fmt){
+    if( c!='%' ){
+      int amt;
+      bufpt = (char *)fmt;
+      amt = 1;
+      while( (c=(*++fmt))!='%' && c!=0 ) amt++;
+      sqlite3StrAccumAppend(pAccum, bufpt, amt);
+      if( c==0 ) break;
+    }
+    if( (c=(*++fmt))==0 ){
+      sqlite3StrAccumAppend(pAccum, "%", 1);
+      break;
+    }
+    /* Find out what flags are present */
+    flag_leftjustify = flag_plussign = flag_blanksign = 
+     flag_alternateform = flag_altform2 = flag_zeropad = 0;
+    done = 0;
+    do{
+      switch( c ){
+        case '-':   flag_leftjustify = 1;     break;
+        case '+':   flag_plussign = 1;        break;
+        case ' ':   flag_blanksign = 1;       break;
+        case '#':   flag_alternateform = 1;   break;
+        case '!':   flag_altform2 = 1;        break;
+        case '0':   flag_zeropad = 1;         break;
+        default:    done = 1;                 break;
+      }
+    }while( !done && (c=(*++fmt))!=0 );
+    /* Get the field width */
+    width = 0;
+    if( c=='*' ){
+      width = va_arg(ap,int);
+      if( width<0 ){
+        flag_leftjustify = 1;
+        width = -width;
+      }
+      c = *++fmt;
+    }else{
+      while( c>='0' && c<='9' ){
+        width = width*10 + c - '0';
+        c = *++fmt;
+      }
+    }
+    if( width > etBUFSIZE-10 ){
+      width = etBUFSIZE-10;
+    }
+    /* Get the precision */
+    if( c=='.' ){
+      precision = 0;
+      c = *++fmt;
+      if( c=='*' ){
+        precision = va_arg(ap,int);
+        if( precision<0 ) precision = -precision;
+        c = *++fmt;
+      }else{
+        while( c>='0' && c<='9' ){
+          precision = precision*10 + c - '0';
+          c = *++fmt;
+        }
+      }
+    }else{
+      precision = -1;
+    }
+    /* Get the conversion type modifier */
+    if( c=='l' ){
+      flag_long = 1;
+      c = *++fmt;
+      if( c=='l' ){
+        flag_longlong = 1;
+        c = *++fmt;
+      }else{
+        flag_longlong = 0;
+      }
+    }else{
+      flag_long = flag_longlong = 0;
+    }
+    /* Fetch the info entry for the field */
+    infop = &fmtinfo[0];
+    xtype = etINVALID;
+    for(idx=0; idx<ArraySize(fmtinfo); idx++){
+      if( c==fmtinfo[idx].fmttype ){
+        infop = &fmtinfo[idx];
+        if( useExtended || (infop->flags & FLAG_INTERN)==0 ){
+          xtype = infop->type;
+        }else{
+          return;
+        }
+        break;
+      }
+    }
+    zExtra = 0;
+
+
+    /* Limit the precision to prevent overflowing buf[] during conversion */
+    if( precision>etBUFSIZE-40 && (infop->flags & FLAG_STRING)==0 ){
+      precision = etBUFSIZE-40;
+    }
+
+    /*
+    ** At this point, variables are initialized as follows:
+    **
+    **   flag_alternateform          TRUE if a '#' is present.
+    **   flag_altform2               TRUE if a '!' is present.
+    **   flag_plussign               TRUE if a '+' is present.
+    **   flag_leftjustify            TRUE if a '-' is present or if the
+    **                               field width was negative.
+    **   flag_zeropad                TRUE if the width began with 0.
+    **   flag_long                   TRUE if the letter 'l' (ell) prefixed
+    **                               the conversion character.
+    **   flag_longlong               TRUE if the letter 'll' (ell ell) prefixed
+    **                               the conversion character.
+    **   flag_blanksign              TRUE if a ' ' is present.
+    **   width                       The specified field width.  This is
+    **                               always non-negative.  Zero is the default.
+    **   precision                   The specified precision.  The default
+    **                               is -1.
+    **   xtype                       The class of the conversion.
+    **   infop                       Pointer to the appropriate info struct.
+    */
+    switch( xtype ){
+      case etPOINTER:
+        flag_longlong = sizeof(char*)==sizeof(i64);
+        flag_long = sizeof(char*)==sizeof(long int);
+        /* Fall through into the next case */
+      case etORDINAL:
+      case etRADIX:
+        if( infop->flags & FLAG_SIGNED ){
+          i64 v;
+          if( flag_longlong ){
+            v = va_arg(ap,i64);
+          }else if( flag_long ){
+            v = va_arg(ap,long int);
+          }else{
+            v = va_arg(ap,int);
+          }
+          if( v<0 ){
+            if( v==SMALLEST_INT64 ){
+              longvalue = ((u64)1)<<63;
+            }else{
+              longvalue = -v;
+            }
+            prefix = '-';
+          }else{
+            longvalue = v;
+            if( flag_plussign )        prefix = '+';
+            else if( flag_blanksign )  prefix = ' ';
+            else                       prefix = 0;
+          }
+        }else{
+          if( flag_longlong ){
+            longvalue = va_arg(ap,u64);
+          }else if( flag_long ){
+            longvalue = va_arg(ap,unsigned long int);
+          }else{
+            longvalue = va_arg(ap,unsigned int);
+          }
+          prefix = 0;
+        }
+        if( longvalue==0 ) flag_alternateform = 0;
+        if( flag_zeropad && precision<width-(prefix!=0) ){
+          precision = width-(prefix!=0);
+        }
+        bufpt = &buf[etBUFSIZE-1];
+        if( xtype==etORDINAL ){
+          static const char zOrd[] = "thstndrd";
+          int x = (int)(longvalue % 10);
+          if( x>=4 || (longvalue/10)%10==1 ){
+            x = 0;
+          }
+          buf[etBUFSIZE-3] = zOrd[x*2];
+          buf[etBUFSIZE-2] = zOrd[x*2+1];
+          bufpt -= 2;
+        }
+        {
+          register const char *cset;      /* Use registers for speed */
+          register int base;
+          cset = &aDigits[infop->charset];
+          base = infop->base;
+          do{                                           /* Convert to ascii */
+            *(--bufpt) = cset[longvalue%base];
+            longvalue = longvalue/base;
+          }while( longvalue>0 );
+        }
+        length = (int)(&buf[etBUFSIZE-1]-bufpt);
+        for(idx=precision-length; idx>0; idx--){
+          *(--bufpt) = '0';                             /* Zero pad */
+        }
+        if( prefix ) *(--bufpt) = prefix;               /* Add sign */
+        if( flag_alternateform && infop->prefix ){      /* Add "0" or "0x" */
+          const char *pre;
+          char x;
+          pre = &aPrefix[infop->prefix];
+          for(; (x=(*pre))!=0; pre++) *(--bufpt) = x;
+        }
+        length = (int)(&buf[etBUFSIZE-1]-bufpt);
+        break;
+      case etFLOAT:
+      case etEXP:
+      case etGENERIC:
+        realvalue = va_arg(ap,double);
+#ifdef SQLITE_OMIT_FLOATING_POINT
+        length = 0;
+#else
+        if( precision<0 ) precision = 6;         /* Set default precision */
+        if( precision>etBUFSIZE/2-10 ) precision = etBUFSIZE/2-10;
+        if( realvalue<0.0 ){
+          realvalue = -realvalue;
+          prefix = '-';
+        }else{
+          if( flag_plussign )          prefix = '+';
+          else if( flag_blanksign )    prefix = ' ';
+          else                         prefix = 0;
+        }
+        if( xtype==etGENERIC && precision>0 ) precision--;
+#if 0
+        /* Rounding works like BSD when the constant 0.4999 is used.  Wierd! */
+        for(idx=precision, rounder=0.4999; idx>0; idx--, rounder*=0.1);
+#else
+        /* It makes more sense to use 0.5 */
+        for(idx=precision, rounder=0.5; idx>0; idx--, rounder*=0.1){}
+#endif
+        if( xtype==etFLOAT ) realvalue += rounder;
+        /* Normalize realvalue to within 10.0 > realvalue >= 1.0 */
+        exp = 0;
+        if( sqlite3IsNaN((double)realvalue) ){
+          bufpt = "NaN";
+          length = 3;
+          break;
+        }
+        if( realvalue>0.0 ){
+          while( realvalue>=1e32 && exp<=350 ){ realvalue *= 1e-32; exp+=32; }
+          while( realvalue>=1e8 && exp<=350 ){ realvalue *= 1e-8; exp+=8; }
+          while( realvalue>=10.0 && exp<=350 ){ realvalue *= 0.1; exp++; }
+          while( realvalue<1e-8 ){ realvalue *= 1e8; exp-=8; }
+          while( realvalue<1.0 ){ realvalue *= 10.0; exp--; }
+          if( exp>350 ){
+            if( prefix=='-' ){
+              bufpt = "-Inf";
+            }else if( prefix=='+' ){
+              bufpt = "+Inf";
+            }else{
+              bufpt = "Inf";
+            }
+            length = sqlite3Strlen30(bufpt);
+            break;
+          }
+        }
+        bufpt = buf;
+        /*
+        ** If the field type is etGENERIC, then convert to either etEXP
+        ** or etFLOAT, as appropriate.
+        */
+        flag_exp = xtype==etEXP;
+        if( xtype!=etFLOAT ){
+          realvalue += rounder;
+          if( realvalue>=10.0 ){ realvalue *= 0.1; exp++; }
+        }
+        if( xtype==etGENERIC ){
+          flag_rtz = !flag_alternateform;
+          if( exp<-4 || exp>precision ){
+            xtype = etEXP;
+          }else{
+            precision = precision - exp;
+            xtype = etFLOAT;
+          }
+        }else{
+          flag_rtz = 0;
+        }
+        if( xtype==etEXP ){
+          e2 = 0;
+        }else{
+          e2 = exp;
+        }
+        nsd = 0;
+        flag_dp = (precision>0 ?1:0) | flag_alternateform | flag_altform2;
+        /* The sign in front of the number */
+        if( prefix ){
+          *(bufpt++) = prefix;
+        }
+        /* Digits prior to the decimal point */
+        if( e2<0 ){
+          *(bufpt++) = '0';
+        }else{
+          for(; e2>=0; e2--){
+            *(bufpt++) = et_getdigit(&realvalue,&nsd);
+          }
+        }
+        /* The decimal point */
+        if( flag_dp ){
+          *(bufpt++) = '.';
+        }
+        /* "0" digits after the decimal point but before the first
+        ** significant digit of the number */
+        for(e2++; e2<0; precision--, e2++){
+          assert( precision>0 );
+          *(bufpt++) = '0';
+        }
+        /* Significant digits after the decimal point */
+        while( (precision--)>0 ){
+          *(bufpt++) = et_getdigit(&realvalue,&nsd);
+        }
+        /* Remove trailing zeros and the "." if no digits follow the "." */
+        if( flag_rtz && flag_dp ){
+          while( bufpt[-1]=='0' ) *(--bufpt) = 0;
+          assert( bufpt>buf );
+          if( bufpt[-1]=='.' ){
+            if( flag_altform2 ){
+              *(bufpt++) = '0';
+            }else{
+              *(--bufpt) = 0;
+            }
+          }
+        }
+        /* Add the "eNNN" suffix */
+        if( flag_exp || xtype==etEXP ){
+          *(bufpt++) = aDigits[infop->charset];
+          if( exp<0 ){
+            *(bufpt++) = '-'; exp = -exp;
+          }else{
+            *(bufpt++) = '+';
+          }
+          if( exp>=100 ){
+            *(bufpt++) = (char)((exp/100)+'0');        /* 100's digit */
+            exp %= 100;
+          }
+          *(bufpt++) = (char)(exp/10+'0');             /* 10's digit */
+          *(bufpt++) = (char)(exp%10+'0');             /* 1's digit */
+        }
+        *bufpt = 0;
+
+        /* The converted number is in buf[] and zero terminated. Output it.
+        ** Note that the number is in the usual order, not reversed as with
+        ** integer conversions. */
+        length = (int)(bufpt-buf);
+        bufpt = buf;
+
+        /* Special case:  Add leading zeros if the flag_zeropad flag is
+        ** set and we are not left justified */
+        if( flag_zeropad && !flag_leftjustify && length < width){
+          int i;
+          int nPad = width - length;
+          for(i=width; i>=nPad; i--){
+            bufpt[i] = bufpt[i-nPad];
+          }
+          i = prefix!=0;
+          while( nPad-- ) bufpt[i++] = '0';
+          length = width;
+        }
+#endif /* !defined(SQLITE_OMIT_FLOATING_POINT) */
+        break;
+      case etSIZE:
+        *(va_arg(ap,int*)) = pAccum->nChar;
+        length = width = 0;
+        break;
+      case etPERCENT:
+        buf[0] = '%';
+        bufpt = buf;
+        length = 1;
+        break;
+      case etCHARX:
+        c = va_arg(ap,int);
+        buf[0] = (char)c;
+        if( precision>=0 ){
+          for(idx=1; idx<precision; idx++) buf[idx] = (char)c;
+          length = precision;
+        }else{
+          length =1;
+        }
+        bufpt = buf;
+        break;
+      case etSTRING:
+      case etDYNSTRING:
+        bufpt = va_arg(ap,char*);
+        if( bufpt==0 ){
+          bufpt = "";
+        }else if( xtype==etDYNSTRING ){
+          zExtra = bufpt;
+        }
+        if( precision>=0 ){
+          for(length=0; length<precision && bufpt[length]; length++){}
+        }else{
+          length = sqlite3Strlen30(bufpt);
+        }
+        break;
+      case etSQLESCAPE:
+      case etSQLESCAPE2:
+      case etSQLESCAPE3: {
+        int i, j, k, n, isnull;
+        int needQuote;
+        char ch;
+        char q = ((xtype==etSQLESCAPE3)?'"':'\'');   /* Quote character */
+        char *escarg = va_arg(ap,char*);
+        isnull = escarg==0;
+        if( isnull ) escarg = (xtype==etSQLESCAPE2 ? "NULL" : "(NULL)");
+        k = precision;
+        for(i=n=0; k!=0 && (ch=escarg[i])!=0; i++, k--){
+          if( ch==q )  n++;
+        }
+        needQuote = !isnull && xtype==etSQLESCAPE2;
+        n += i + 1 + needQuote*2;
+        if( n>etBUFSIZE ){
+          bufpt = zExtra = sqlite3Malloc( n );
+          if( bufpt==0 ){
+            pAccum->mallocFailed = 1;
+            return;
+          }
+        }else{
+          bufpt = buf;
+        }
+        j = 0;
+        if( needQuote ) bufpt[j++] = q;
+        k = i;
+        for(i=0; i<k; i++){
+          bufpt[j++] = ch = escarg[i];
+          if( ch==q ) bufpt[j++] = ch;
+        }
+        if( needQuote ) bufpt[j++] = q;
+        bufpt[j] = 0;
+        length = j;
+        /* The precision in %q and %Q means how many input characters to
+        ** consume, not the length of the output...
+        ** if( precision>=0 && precision<length ) length = precision; */
+        break;
+      }
+      case etTOKEN: {
+        Token *pToken = va_arg(ap, Token*);
+        if( pToken ){
+          sqlite3StrAccumAppend(pAccum, (const char*)pToken->z, pToken->n);
+        }
+        length = width = 0;
+        break;
+      }
+      case etSRCLIST: {
+        SrcList *pSrc = va_arg(ap, SrcList*);
+        int k = va_arg(ap, int);
+        struct SrcList_item *pItem = &pSrc->a[k];
+        assert( k>=0 && k<pSrc->nSrc );
+        if( pItem->zDatabase ){
+          sqlite3StrAccumAppend(pAccum, pItem->zDatabase, -1);
+          sqlite3StrAccumAppend(pAccum, ".", 1);
+        }
+        sqlite3StrAccumAppend(pAccum, pItem->zName, -1);
+        length = width = 0;
+        break;
+      }
+      default: {
+        assert( xtype==etINVALID );
+        return;
+      }
+    }/* End switch over the format type */
+    /*
+    ** The text of the conversion is pointed to by "bufpt" and is
+    ** "length" characters long.  The field width is "width".  Do
+    ** the output.
+    */
+    if( !flag_leftjustify ){
+      register int nspace;
+      nspace = width-length;
+      if( nspace>0 ){
+        appendSpace(pAccum, nspace);
+      }
+    }
+    if( length>0 ){
+      sqlite3StrAccumAppend(pAccum, bufpt, length);
+    }
+    if( flag_leftjustify ){
+      register int nspace;
+      nspace = width-length;
+      if( nspace>0 ){
+        appendSpace(pAccum, nspace);
+      }
+    }
+    if( zExtra ){
+      sqlite3_free(zExtra);
+    }
+  }/* End for loop over the format string */
+} /* End of function */
+
+/*
+** Append N bytes of text from z to the StrAccum object.
+*/
+SQLITE_PRIVATE void sqlite3StrAccumAppend(StrAccum *p, const char *z, int N){
+  assert( z!=0 || N==0 );
+  if( p->tooBig | p->mallocFailed ){
+    testcase(p->tooBig);
+    testcase(p->mallocFailed);
+    return;
+  }
+  if( N<0 ){
+    N = sqlite3Strlen30(z);
+  }
+  if( N==0 || NEVER(z==0) ){
+    return;
+  }
+  if( p->nChar+N >= p->nAlloc ){
+    char *zNew;
+    if( !p->useMalloc ){
+      p->tooBig = 1;
+      N = p->nAlloc - p->nChar - 1;
+      if( N<=0 ){
+        return;
+      }
+    }else{
+      char *zOld = (p->zText==p->zBase ? 0 : p->zText);
+      i64 szNew = p->nChar;
+      szNew += N + 1;
+      if( szNew > p->mxAlloc ){
+        sqlite3StrAccumReset(p);
+        p->tooBig = 1;
+        return;
+      }else{
+        p->nAlloc = (int)szNew;
+      }
+      if( p->useMalloc==1 ){
+        zNew = sqlite3DbRealloc(p->db, zOld, p->nAlloc);
+      }else{
+        zNew = sqlite3_realloc(zOld, p->nAlloc);
+      }
+      if( zNew ){
+        if( zOld==0 ) memcpy(zNew, p->zText, p->nChar);
+        p->zText = zNew;
+      }else{
+        p->mallocFailed = 1;
+        sqlite3StrAccumReset(p);
+        return;
+      }
+    }
+  }
+  memcpy(&p->zText[p->nChar], z, N);
+  p->nChar += N;
+}
+
+/*
+** Finish off a string by making sure it is zero-terminated.
+** Return a pointer to the resulting string.  Return a NULL
+** pointer if any kind of error was encountered.
+*/
+SQLITE_PRIVATE char *sqlite3StrAccumFinish(StrAccum *p){
+  if( p->zText ){
+    p->zText[p->nChar] = 0;
+    if( p->useMalloc && p->zText==p->zBase ){
+      if( p->useMalloc==1 ){
+        p->zText = sqlite3DbMallocRaw(p->db, p->nChar+1 );
+      }else{
+        p->zText = sqlite3_malloc(p->nChar+1);
+      }
+      if( p->zText ){
+        memcpy(p->zText, p->zBase, p->nChar+1);
+      }else{
+        p->mallocFailed = 1;
+      }
+    }
+  }
+  return p->zText;
+}
+
+/*
+** Reset an StrAccum string.  Reclaim all malloced memory.
+*/
+SQLITE_PRIVATE void sqlite3StrAccumReset(StrAccum *p){
+  if( p->zText!=p->zBase ){
+    if( p->useMalloc==1 ){
+      sqlite3DbFree(p->db, p->zText);
+    }else{
+      sqlite3_free(p->zText);
+    }
+  }
+  p->zText = 0;
+}
+
+/*
+** Initialize a string accumulator
+*/
+SQLITE_PRIVATE void sqlite3StrAccumInit(StrAccum *p, char *zBase, int n, int mx){
+  p->zText = p->zBase = zBase;
+  p->db = 0;
+  p->nChar = 0;
+  p->nAlloc = n;
+  p->mxAlloc = mx;
+  p->useMalloc = 1;
+  p->tooBig = 0;
+  p->mallocFailed = 0;
+}
+
+/*
+** Print into memory obtained from sqliteMalloc().  Use the internal
+** %-conversion extensions.
+*/
+SQLITE_PRIVATE char *sqlite3VMPrintf(sqlite3 *db, const char *zFormat, va_list ap){
+  char *z;
+  char zBase[SQLITE_PRINT_BUF_SIZE];
+  StrAccum acc;
+  assert( db!=0 );
+  sqlite3StrAccumInit(&acc, zBase, sizeof(zBase),
+                      db->aLimit[SQLITE_LIMIT_LENGTH]);
+  acc.db = db;
+  sqlite3VXPrintf(&acc, 1, zFormat, ap);
+  z = sqlite3StrAccumFinish(&acc);
+  if( acc.mallocFailed ){
+    db->mallocFailed = 1;
+  }
+  return z;
+}
+
+/*
+** Print into memory obtained from sqliteMalloc().  Use the internal
+** %-conversion extensions.
+*/
+SQLITE_PRIVATE char *sqlite3MPrintf(sqlite3 *db, const char *zFormat, ...){
+  va_list ap;
+  char *z;
+  va_start(ap, zFormat);
+  z = sqlite3VMPrintf(db, zFormat, ap);
+  va_end(ap);
+  return z;
+}
+
+/*
+** Like sqlite3MPrintf(), but call sqlite3DbFree() on zStr after formatting
+** the string and before returnning.  This routine is intended to be used
+** to modify an existing string.  For example:
+**
+**       x = sqlite3MPrintf(db, x, "prefix %s suffix", x);
+**
+*/
+SQLITE_PRIVATE char *sqlite3MAppendf(sqlite3 *db, char *zStr, const char *zFormat, ...){
+  va_list ap;
+  char *z;
+  va_start(ap, zFormat);
+  z = sqlite3VMPrintf(db, zFormat, ap);
+  va_end(ap);
+  sqlite3DbFree(db, zStr);
+  return z;
+}
+
+/*
+** Print into memory obtained from sqlite3_malloc().  Omit the internal
+** %-conversion extensions.
+*/
+SQLITE_API char *sqlite3_vmprintf(const char *zFormat, va_list ap){
+  char *z;
+  char zBase[SQLITE_PRINT_BUF_SIZE];
+  StrAccum acc;
+#ifndef SQLITE_OMIT_AUTOINIT
+  if( sqlite3_initialize() ) return 0;
+#endif
+  sqlite3StrAccumInit(&acc, zBase, sizeof(zBase), SQLITE_MAX_LENGTH);
+  acc.useMalloc = 2;
+  sqlite3VXPrintf(&acc, 0, zFormat, ap);
+  z = sqlite3StrAccumFinish(&acc);
+  return z;
+}
+
+/*
+** Print into memory obtained from sqlite3_malloc()().  Omit the internal
+** %-conversion extensions.
+*/
+SQLITE_API char *sqlite3_mprintf(const char *zFormat, ...){
+  va_list ap;
+  char *z;
+#ifndef SQLITE_OMIT_AUTOINIT
+  if( sqlite3_initialize() ) return 0;
+#endif
+  va_start(ap, zFormat);
+  z = sqlite3_vmprintf(zFormat, ap);
+  va_end(ap);
+  return z;
+}
+
+/*
+** sqlite3_snprintf() works like snprintf() except that it ignores the
+** current locale settings.  This is important for SQLite because we
+** are not able to use a "," as the decimal point in place of "." as
+** specified by some locales.
+**
+** Oops:  The first two arguments of sqlite3_snprintf() are backwards
+** from the snprintf() standard.  Unfortunately, it is too late to change
+** this without breaking compatibility, so we just have to live with the
+** mistake.
+**
+** sqlite3_vsnprintf() is the varargs version.
+*/
+SQLITE_API char *sqlite3_vsnprintf(int n, char *zBuf, const char *zFormat, va_list ap){
+  StrAccum acc;
+  if( n<=0 ) return zBuf;
+  sqlite3StrAccumInit(&acc, zBuf, n, 0);
+  acc.useMalloc = 0;
+  sqlite3VXPrintf(&acc, 0, zFormat, ap);
+  return sqlite3StrAccumFinish(&acc);
+}
+SQLITE_API char *sqlite3_snprintf(int n, char *zBuf, const char *zFormat, ...){
+  char *z;
+  va_list ap;
+  va_start(ap,zFormat);
+  z = sqlite3_vsnprintf(n, zBuf, zFormat, ap);
+  va_end(ap);
+  return z;
+}
+
+/*
+** This is the routine that actually formats the sqlite3_log() message.
+** We house it in a separate routine from sqlite3_log() to avoid using
+** stack space on small-stack systems when logging is disabled.
+**
+** sqlite3_log() must render into a static buffer.  It cannot dynamically
+** allocate memory because it might be called while the memory allocator
+** mutex is held.
+*/
+static void renderLogMsg(int iErrCode, const char *zFormat, va_list ap){
+  StrAccum acc;                          /* String accumulator */
+  char zMsg[SQLITE_PRINT_BUF_SIZE*3];    /* Complete log message */
+
+  sqlite3StrAccumInit(&acc, zMsg, sizeof(zMsg), 0);
+  acc.useMalloc = 0;
+  sqlite3VXPrintf(&acc, 0, zFormat, ap);
+  sqlite3GlobalConfig.xLog(sqlite3GlobalConfig.pLogArg, iErrCode,
+                           sqlite3StrAccumFinish(&acc));
+}
+
+/*
+** Format and write a message to the log if logging is enabled.
+*/
+SQLITE_API void sqlite3_log(int iErrCode, const char *zFormat, ...){
+  va_list ap;                             /* Vararg list */
+  if( sqlite3GlobalConfig.xLog ){
+    va_start(ap, zFormat);
+    renderLogMsg(iErrCode, zFormat, ap);
+    va_end(ap);
+  }
+}
+
+#if defined(SQLITE_DEBUG)
+/*
+** A version of printf() that understands %lld.  Used for debugging.
+** The printf() built into some versions of windows does not understand %lld
+** and segfaults if you give it a long long int.
+*/
+SQLITE_PRIVATE void sqlite3DebugPrintf(const char *zFormat, ...){
+  va_list ap;
+  StrAccum acc;
+  char zBuf[500];
+  sqlite3StrAccumInit(&acc, zBuf, sizeof(zBuf), 0);
+  acc.useMalloc = 0;
+  va_start(ap,zFormat);
+  sqlite3VXPrintf(&acc, 0, zFormat, ap);
+  va_end(ap);
+  sqlite3StrAccumFinish(&acc);
+  fprintf(stdout,"%s", zBuf);
+  fflush(stdout);
+}
+#endif
+
+#ifndef SQLITE_OMIT_TRACE
+/*
+** variable-argument wrapper around sqlite3VXPrintf().
+*/
+SQLITE_PRIVATE void sqlite3XPrintf(StrAccum *p, const char *zFormat, ...){
+  va_list ap;
+  va_start(ap,zFormat);
+  sqlite3VXPrintf(p, 1, zFormat, ap);
+  va_end(ap);
+}
+#endif
+
+/************** End of printf.c **********************************************/
+/************** Begin file random.c ******************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains code to implement a pseudo-random number
+** generator (PRNG) for SQLite.
+**
+** Random numbers are used by some of the database backends in order
+** to generate random integer keys for tables or random filenames.
+*/
+
+
+/* All threads share a single random number generator.
+** This structure is the current state of the generator.
+*/
+static SQLITE_WSD struct sqlite3PrngType {
+  unsigned char isInit;          /* True if initialized */
+  unsigned char i, j;            /* State variables */
+  unsigned char s[256];          /* State variables */
+} sqlite3Prng;
+
+/*
+** Get a single 8-bit random value from the RC4 PRNG.  The Mutex
+** must be held while executing this routine.
+**
+** Why not just use a library random generator like lrand48() for this?
+** Because the OP_NewRowid opcode in the VDBE depends on having a very
+** good source of random numbers.  The lrand48() library function may
+** well be good enough.  But maybe not.  Or maybe lrand48() has some
+** subtle problems on some systems that could cause problems.  It is hard
+** to know.  To minimize the risk of problems due to bad lrand48()
+** implementations, SQLite uses this random number generator based
+** on RC4, which we know works very well.
+**
+** (Later):  Actually, OP_NewRowid does not depend on a good source of
+** randomness any more.  But we will leave this code in all the same.
+*/
+static u8 randomByte(void){
+  unsigned char t;
+
+
+  /* The "wsdPrng" macro will resolve to the pseudo-random number generator
+  ** state vector.  If writable static data is unsupported on the target,
+  ** we have to locate the state vector at run-time.  In the more common
+  ** case where writable static data is supported, wsdPrng can refer directly
+  ** to the "sqlite3Prng" state vector declared above.
+  */
+#ifdef SQLITE_OMIT_WSD
+  struct sqlite3PrngType *p = &GLOBAL(struct sqlite3PrngType, sqlite3Prng);
+# define wsdPrng p[0]
+#else
+# define wsdPrng sqlite3Prng
+#endif
+
+
+  /* Initialize the state of the random number generator once,
+  ** the first time this routine is called.  The seed value does
+  ** not need to contain a lot of randomness since we are not
+  ** trying to do secure encryption or anything like that...
+  **
+  ** Nothing in this file or anywhere else in SQLite does any kind of
+  ** encryption.  The RC4 algorithm is being used as a PRNG (pseudo-random
+  ** number generator) not as an encryption device.
+  */
+  if( !wsdPrng.isInit ){
+    int i;
+    char k[256];
+    wsdPrng.j = 0;
+    wsdPrng.i = 0;
+    sqlite3OsRandomness(sqlite3_vfs_find(0), 256, k);
+    for(i=0; i<256; i++){
+      wsdPrng.s[i] = (u8)i;
+    }
+    for(i=0; i<256; i++){
+      wsdPrng.j += wsdPrng.s[i] + k[i];
+      t = wsdPrng.s[wsdPrng.j];
+      wsdPrng.s[wsdPrng.j] = wsdPrng.s[i];
+      wsdPrng.s[i] = t;
+    }
+    wsdPrng.isInit = 1;
+  }
+
+  /* Generate and return single random byte
+  */
+  wsdPrng.i++;
+  t = wsdPrng.s[wsdPrng.i];
+  wsdPrng.j += t;
+  wsdPrng.s[wsdPrng.i] = wsdPrng.s[wsdPrng.j];
+  wsdPrng.s[wsdPrng.j] = t;
+  t += wsdPrng.s[wsdPrng.i];
+  return wsdPrng.s[t];
+}
+
+/*
+** Return N random bytes.
+*/
+SQLITE_API void sqlite3_randomness(int N, void *pBuf){
+  unsigned char *zBuf = pBuf;
+#if SQLITE_THREADSAFE
+  sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_PRNG);
+#endif
+  sqlite3_mutex_enter(mutex);
+  while( N-- ){
+    *(zBuf++) = randomByte();
+  }
+  sqlite3_mutex_leave(mutex);
+}
+
+#ifndef SQLITE_OMIT_BUILTIN_TEST
+/*
+** For testing purposes, we sometimes want to preserve the state of
+** PRNG and restore the PRNG to its saved state at a later time, or
+** to reset the PRNG to its initial state.  These routines accomplish
+** those tasks.
+**
+** The sqlite3_test_control() interface calls these routines to
+** control the PRNG.
+*/
+static SQLITE_WSD struct sqlite3PrngType sqlite3SavedPrng;
+SQLITE_PRIVATE void sqlite3PrngSaveState(void){
+  memcpy(
+    &GLOBAL(struct sqlite3PrngType, sqlite3SavedPrng),
+    &GLOBAL(struct sqlite3PrngType, sqlite3Prng),
+    sizeof(sqlite3Prng)
+  );
+}
+SQLITE_PRIVATE void sqlite3PrngRestoreState(void){
+  memcpy(
+    &GLOBAL(struct sqlite3PrngType, sqlite3Prng),
+    &GLOBAL(struct sqlite3PrngType, sqlite3SavedPrng),
+    sizeof(sqlite3Prng)
+  );
+}
+SQLITE_PRIVATE void sqlite3PrngResetState(void){
+  GLOBAL(struct sqlite3PrngType, sqlite3Prng).isInit = 0;
+}
+#endif /* SQLITE_OMIT_BUILTIN_TEST */
+
+/************** End of random.c **********************************************/
+/************** Begin file utf.c *********************************************/
+/*
+** 2004 April 13
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains routines used to translate between UTF-8, 
+** UTF-16, UTF-16BE, and UTF-16LE.
+**
+** Notes on UTF-8:
+**
+**   Byte-0    Byte-1    Byte-2    Byte-3    Value
+**  0xxxxxxx                                 00000000 00000000 0xxxxxxx
+**  110yyyyy  10xxxxxx                       00000000 00000yyy yyxxxxxx
+**  1110zzzz  10yyyyyy  10xxxxxx             00000000 zzzzyyyy yyxxxxxx
+**  11110uuu  10uuzzzz  10yyyyyy  10xxxxxx   000uuuuu zzzzyyyy yyxxxxxx
+**
+**
+** Notes on UTF-16:  (with wwww+1==uuuuu)
+**
+**      Word-0               Word-1          Value
+**  110110ww wwzzzzyy   110111yy yyxxxxxx    000uuuuu zzzzyyyy yyxxxxxx
+**  zzzzyyyy yyxxxxxx                        00000000 zzzzyyyy yyxxxxxx
+**
+**
+** BOM or Byte Order Mark:
+**     0xff 0xfe   little-endian utf-16 follows
+**     0xfe 0xff   big-endian utf-16 follows
+**
+*/
+
+#ifndef SQLITE_AMALGAMATION
+/*
+** The following constant value is used by the SQLITE_BIGENDIAN and
+** SQLITE_LITTLEENDIAN macros.
+*/
+SQLITE_PRIVATE const int sqlite3one = 1;
+#endif /* SQLITE_AMALGAMATION */
+
+/*
+** This lookup table is used to help decode the first byte of
+** a multi-byte UTF8 character.
+*/
+static const unsigned char sqlite3Utf8Trans1[] = {
+  0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+  0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
+  0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
+  0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+  0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+  0x00, 0x01, 0x02, 0x03, 0x00, 0x01, 0x00, 0x00,
+};
+
+
+#define WRITE_UTF8(zOut, c) {                          \
+  if( c<0x00080 ){                                     \
+    *zOut++ = (u8)(c&0xFF);                            \
+  }                                                    \
+  else if( c<0x00800 ){                                \
+    *zOut++ = 0xC0 + (u8)((c>>6)&0x1F);                \
+    *zOut++ = 0x80 + (u8)(c & 0x3F);                   \
+  }                                                    \
+  else if( c<0x10000 ){                                \
+    *zOut++ = 0xE0 + (u8)((c>>12)&0x0F);               \
+    *zOut++ = 0x80 + (u8)((c>>6) & 0x3F);              \
+    *zOut++ = 0x80 + (u8)(c & 0x3F);                   \
+  }else{                                               \
+    *zOut++ = 0xF0 + (u8)((c>>18) & 0x07);             \
+    *zOut++ = 0x80 + (u8)((c>>12) & 0x3F);             \
+    *zOut++ = 0x80 + (u8)((c>>6) & 0x3F);              \
+    *zOut++ = 0x80 + (u8)(c & 0x3F);                   \
+  }                                                    \
+}
+
+#define WRITE_UTF16LE(zOut, c) {                                    \
+  if( c<=0xFFFF ){                                                  \
+    *zOut++ = (u8)(c&0x00FF);                                       \
+    *zOut++ = (u8)((c>>8)&0x00FF);                                  \
+  }else{                                                            \
+    *zOut++ = (u8)(((c>>10)&0x003F) + (((c-0x10000)>>10)&0x00C0));  \
+    *zOut++ = (u8)(0x00D8 + (((c-0x10000)>>18)&0x03));              \
+    *zOut++ = (u8)(c&0x00FF);                                       \
+    *zOut++ = (u8)(0x00DC + ((c>>8)&0x03));                         \
+  }                                                                 \
+}
+
+#define WRITE_UTF16BE(zOut, c) {                                    \
+  if( c<=0xFFFF ){                                                  \
+    *zOut++ = (u8)((c>>8)&0x00FF);                                  \
+    *zOut++ = (u8)(c&0x00FF);                                       \
+  }else{                                                            \
+    *zOut++ = (u8)(0x00D8 + (((c-0x10000)>>18)&0x03));              \
+    *zOut++ = (u8)(((c>>10)&0x003F) + (((c-0x10000)>>10)&0x00C0));  \
+    *zOut++ = (u8)(0x00DC + ((c>>8)&0x03));                         \
+    *zOut++ = (u8)(c&0x00FF);                                       \
+  }                                                                 \
+}
+
+#define READ_UTF16LE(zIn, TERM, c){                                   \
+  c = (*zIn++);                                                       \
+  c += ((*zIn++)<<8);                                                 \
+  if( c>=0xD800 && c<0xE000 && TERM ){                                \
+    int c2 = (*zIn++);                                                \
+    c2 += ((*zIn++)<<8);                                              \
+    c = (c2&0x03FF) + ((c&0x003F)<<10) + (((c&0x03C0)+0x0040)<<10);   \
+  }                                                                   \
+}
+
+#define READ_UTF16BE(zIn, TERM, c){                                   \
+  c = ((*zIn++)<<8);                                                  \
+  c += (*zIn++);                                                      \
+  if( c>=0xD800 && c<0xE000 && TERM ){                                \
+    int c2 = ((*zIn++)<<8);                                           \
+    c2 += (*zIn++);                                                   \
+    c = (c2&0x03FF) + ((c&0x003F)<<10) + (((c&0x03C0)+0x0040)<<10);   \
+  }                                                                   \
+}
+
+/*
+** Translate a single UTF-8 character.  Return the unicode value.
+**
+** During translation, assume that the byte that zTerm points
+** is a 0x00.
+**
+** Write a pointer to the next unread byte back into *pzNext.
+**
+** Notes On Invalid UTF-8:
+**
+**  *  This routine never allows a 7-bit character (0x00 through 0x7f) to
+**     be encoded as a multi-byte character.  Any multi-byte character that
+**     attempts to encode a value between 0x00 and 0x7f is rendered as 0xfffd.
+**
+**  *  This routine never allows a UTF16 surrogate value to be encoded.
+**     If a multi-byte character attempts to encode a value between
+**     0xd800 and 0xe000 then it is rendered as 0xfffd.
+**
+**  *  Bytes in the range of 0x80 through 0xbf which occur as the first
+**     byte of a character are interpreted as single-byte characters
+**     and rendered as themselves even though they are technically
+**     invalid characters.
+**
+**  *  This routine accepts an infinite number of different UTF8 encodings
+**     for unicode values 0x80 and greater.  It do not change over-length
+**     encodings to 0xfffd as some systems recommend.
+*/
+#define READ_UTF8(zIn, zTerm, c)                           \
+  c = *(zIn++);                                            \
+  if( c>=0xc0 ){                                           \
+    c = sqlite3Utf8Trans1[c-0xc0];                         \
+    while( zIn!=zTerm && (*zIn & 0xc0)==0x80 ){            \
+      c = (c<<6) + (0x3f & *(zIn++));                      \
+    }                                                      \
+    if( c<0x80                                             \
+        || (c&0xFFFFF800)==0xD800                          \
+        || (c&0xFFFFFFFE)==0xFFFE ){  c = 0xFFFD; }        \
+  }
+SQLITE_PRIVATE int sqlite3Utf8Read(
+  const unsigned char *zIn,       /* First byte of UTF-8 character */
+  const unsigned char **pzNext    /* Write first byte past UTF-8 char here */
+){
+  unsigned int c;
+
+  /* Same as READ_UTF8() above but without the zTerm parameter.
+  ** For this routine, we assume the UTF8 string is always zero-terminated.
+  */
+  c = *(zIn++);
+  if( c>=0xc0 ){
+    c = sqlite3Utf8Trans1[c-0xc0];
+    while( (*zIn & 0xc0)==0x80 ){
+      c = (c<<6) + (0x3f & *(zIn++));
+    }
+    if( c<0x80
+        || (c&0xFFFFF800)==0xD800
+        || (c&0xFFFFFFFE)==0xFFFE ){  c = 0xFFFD; }
+  }
+  *pzNext = zIn;
+  return c;
+}
+
+
+
+
+/*
+** If the TRANSLATE_TRACE macro is defined, the value of each Mem is
+** printed on stderr on the way into and out of sqlite3VdbeMemTranslate().
+*/ 
+/* #define TRANSLATE_TRACE 1 */
+
+#ifndef SQLITE_OMIT_UTF16
+/*
+** This routine transforms the internal text encoding used by pMem to
+** desiredEnc. It is an error if the string is already of the desired
+** encoding, or if *pMem does not contain a string value.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMemTranslate(Mem *pMem, u8 desiredEnc){
+  int len;                    /* Maximum length of output string in bytes */
+  unsigned char *zOut;                  /* Output buffer */
+  unsigned char *zIn;                   /* Input iterator */
+  unsigned char *zTerm;                 /* End of input */
+  unsigned char *z;                     /* Output iterator */
+  unsigned int c;
+
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  assert( pMem->flags&MEM_Str );
+  assert( pMem->enc!=desiredEnc );
+  assert( pMem->enc!=0 );
+  assert( pMem->n>=0 );
+
+#if defined(TRANSLATE_TRACE) && defined(SQLITE_DEBUG)
+  {
+    char zBuf[100];
+    sqlite3VdbeMemPrettyPrint(pMem, zBuf);
+    fprintf(stderr, "INPUT:  %s\n", zBuf);
+  }
+#endif
+
+  /* If the translation is between UTF-16 little and big endian, then 
+  ** all that is required is to swap the byte order. This case is handled
+  ** differently from the others.
+  */
+  if( pMem->enc!=SQLITE_UTF8 && desiredEnc!=SQLITE_UTF8 ){
+    u8 temp;
+    int rc;
+    rc = sqlite3VdbeMemMakeWriteable(pMem);
+    if( rc!=SQLITE_OK ){
+      assert( rc==SQLITE_NOMEM );
+      return SQLITE_NOMEM;
+    }
+    zIn = (u8*)pMem->z;
+    zTerm = &zIn[pMem->n&~1];
+    while( zIn<zTerm ){
+      temp = *zIn;
+      *zIn = *(zIn+1);
+      zIn++;
+      *zIn++ = temp;
+    }
+    pMem->enc = desiredEnc;
+    goto translate_out;
+  }
+
+  /* Set len to the maximum number of bytes required in the output buffer. */
+  if( desiredEnc==SQLITE_UTF8 ){
+    /* When converting from UTF-16, the maximum growth results from
+    ** translating a 2-byte character to a 4-byte UTF-8 character.
+    ** A single byte is required for the output string
+    ** nul-terminator.
+    */
+    pMem->n &= ~1;
+    len = pMem->n * 2 + 1;
+  }else{
+    /* When converting from UTF-8 to UTF-16 the maximum growth is caused
+    ** when a 1-byte UTF-8 character is translated into a 2-byte UTF-16
+    ** character. Two bytes are required in the output buffer for the
+    ** nul-terminator.
+    */
+    len = pMem->n * 2 + 2;
+  }
+
+  /* Set zIn to point at the start of the input buffer and zTerm to point 1
+  ** byte past the end.
+  **
+  ** Variable zOut is set to point at the output buffer, space obtained
+  ** from sqlite3_malloc().
+  */
+  zIn = (u8*)pMem->z;
+  zTerm = &zIn[pMem->n];
+  zOut = sqlite3DbMallocRaw(pMem->db, len);
+  if( !zOut ){
+    return SQLITE_NOMEM;
+  }
+  z = zOut;
+
+  if( pMem->enc==SQLITE_UTF8 ){
+    if( desiredEnc==SQLITE_UTF16LE ){
+      /* UTF-8 -> UTF-16 Little-endian */
+      while( zIn<zTerm ){
+        /* c = sqlite3Utf8Read(zIn, zTerm, (const u8**)&zIn); */
+        READ_UTF8(zIn, zTerm, c);
+        WRITE_UTF16LE(z, c);
+      }
+    }else{
+      assert( desiredEnc==SQLITE_UTF16BE );
+      /* UTF-8 -> UTF-16 Big-endian */
+      while( zIn<zTerm ){
+        /* c = sqlite3Utf8Read(zIn, zTerm, (const u8**)&zIn); */
+        READ_UTF8(zIn, zTerm, c);
+        WRITE_UTF16BE(z, c);
+      }
+    }
+    pMem->n = (int)(z - zOut);
+    *z++ = 0;
+  }else{
+    assert( desiredEnc==SQLITE_UTF8 );
+    if( pMem->enc==SQLITE_UTF16LE ){
+      /* UTF-16 Little-endian -> UTF-8 */
+      while( zIn<zTerm ){
+        READ_UTF16LE(zIn, zIn<zTerm, c); 
+        WRITE_UTF8(z, c);
+      }
+    }else{
+      /* UTF-16 Big-endian -> UTF-8 */
+      while( zIn<zTerm ){
+        READ_UTF16BE(zIn, zIn<zTerm, c); 
+        WRITE_UTF8(z, c);
+      }
+    }
+    pMem->n = (int)(z - zOut);
+  }
+  *z = 0;
+  assert( (pMem->n+(desiredEnc==SQLITE_UTF8?1:2))<=len );
+
+  sqlite3VdbeMemRelease(pMem);
+  pMem->flags &= ~(MEM_Static|MEM_Dyn|MEM_Ephem);
+  pMem->enc = desiredEnc;
+  pMem->flags |= (MEM_Term|MEM_Dyn);
+  pMem->z = (char*)zOut;
+  pMem->zMalloc = pMem->z;
+
+translate_out:
+#if defined(TRANSLATE_TRACE) && defined(SQLITE_DEBUG)
+  {
+    char zBuf[100];
+    sqlite3VdbeMemPrettyPrint(pMem, zBuf);
+    fprintf(stderr, "OUTPUT: %s\n", zBuf);
+  }
+#endif
+  return SQLITE_OK;
+}
+
+/*
+** This routine checks for a byte-order mark at the beginning of the 
+** UTF-16 string stored in *pMem. If one is present, it is removed and
+** the encoding of the Mem adjusted. This routine does not do any
+** byte-swapping, it just sets Mem.enc appropriately.
+**
+** The allocation (static, dynamic etc.) and encoding of the Mem may be
+** changed by this function.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMemHandleBom(Mem *pMem){
+  int rc = SQLITE_OK;
+  u8 bom = 0;
+
+  assert( pMem->n>=0 );
+  if( pMem->n>1 ){
+    u8 b1 = *(u8 *)pMem->z;
+    u8 b2 = *(((u8 *)pMem->z) + 1);
+    if( b1==0xFE && b2==0xFF ){
+      bom = SQLITE_UTF16BE;
+    }
+    if( b1==0xFF && b2==0xFE ){
+      bom = SQLITE_UTF16LE;
+    }
+  }
+  
+  if( bom ){
+    rc = sqlite3VdbeMemMakeWriteable(pMem);
+    if( rc==SQLITE_OK ){
+      pMem->n -= 2;
+      memmove(pMem->z, &pMem->z[2], pMem->n);
+      pMem->z[pMem->n] = '\0';
+      pMem->z[pMem->n+1] = '\0';
+      pMem->flags |= MEM_Term;
+      pMem->enc = bom;
+    }
+  }
+  return rc;
+}
+#endif /* SQLITE_OMIT_UTF16 */
+
+/*
+** pZ is a UTF-8 encoded unicode string. If nByte is less than zero,
+** return the number of unicode characters in pZ up to (but not including)
+** the first 0x00 byte. If nByte is not less than zero, return the
+** number of unicode characters in the first nByte of pZ (or up to 
+** the first 0x00, whichever comes first).
+*/
+SQLITE_PRIVATE int sqlite3Utf8CharLen(const char *zIn, int nByte){
+  int r = 0;
+  const u8 *z = (const u8*)zIn;
+  const u8 *zTerm;
+  if( nByte>=0 ){
+    zTerm = &z[nByte];
+  }else{
+    zTerm = (const u8*)(-1);
+  }
+  assert( z<=zTerm );
+  while( *z!=0 && z<zTerm ){
+    SQLITE_SKIP_UTF8(z);
+    r++;
+  }
+  return r;
+}
+
+/* This test function is not currently used by the automated test-suite. 
+** Hence it is only available in debug builds.
+*/
+#if defined(SQLITE_TEST) && defined(SQLITE_DEBUG)
+/*
+** Translate UTF-8 to UTF-8.
+**
+** This has the effect of making sure that the string is well-formed
+** UTF-8.  Miscoded characters are removed.
+**
+** The translation is done in-place and aborted if the output
+** overruns the input.
+*/
+SQLITE_PRIVATE int sqlite3Utf8To8(unsigned char *zIn){
+  unsigned char *zOut = zIn;
+  unsigned char *zStart = zIn;
+  u32 c;
+
+  while( zIn[0] && zOut<=zIn ){
+    c = sqlite3Utf8Read(zIn, (const u8**)&zIn);
+    if( c!=0xfffd ){
+      WRITE_UTF8(zOut, c);
+    }
+  }
+  *zOut = 0;
+  return (int)(zOut - zStart);
+}
+#endif
+
+#ifndef SQLITE_OMIT_UTF16
+/*
+** Convert a UTF-16 string in the native encoding into a UTF-8 string.
+** Memory to hold the UTF-8 string is obtained from sqlite3_malloc and must
+** be freed by the calling function.
+**
+** NULL is returned if there is an allocation error.
+*/
+SQLITE_PRIVATE char *sqlite3Utf16to8(sqlite3 *db, const void *z, int nByte, u8 enc){
+  Mem m;
+  memset(&m, 0, sizeof(m));
+  m.db = db;
+  sqlite3VdbeMemSetStr(&m, z, nByte, enc, SQLITE_STATIC);
+  sqlite3VdbeChangeEncoding(&m, SQLITE_UTF8);
+  if( db->mallocFailed ){
+    sqlite3VdbeMemRelease(&m);
+    m.z = 0;
+  }
+  assert( (m.flags & MEM_Term)!=0 || db->mallocFailed );
+  assert( (m.flags & MEM_Str)!=0 || db->mallocFailed );
+  assert( (m.flags & MEM_Dyn)!=0 || db->mallocFailed );
+  assert( m.z || db->mallocFailed );
+  return m.z;
+}
+
+/*
+** Convert a UTF-8 string to the UTF-16 encoding specified by parameter
+** enc. A pointer to the new string is returned, and the value of *pnOut
+** is set to the length of the returned string in bytes. The call should
+** arrange to call sqlite3DbFree() on the returned pointer when it is
+** no longer required.
+** 
+** If a malloc failure occurs, NULL is returned and the db.mallocFailed
+** flag set.
+*/
+#ifdef SQLITE_ENABLE_STAT2
+SQLITE_PRIVATE char *sqlite3Utf8to16(sqlite3 *db, u8 enc, char *z, int n, int *pnOut){
+  Mem m;
+  memset(&m, 0, sizeof(m));
+  m.db = db;
+  sqlite3VdbeMemSetStr(&m, z, n, SQLITE_UTF8, SQLITE_STATIC);
+  if( sqlite3VdbeMemTranslate(&m, enc) ){
+    assert( db->mallocFailed );
+    return 0;
+  }
+  assert( m.z==m.zMalloc );
+  *pnOut = m.n;
+  return m.z;
+}
+#endif
+
+/*
+** zIn is a UTF-16 encoded unicode string at least nChar characters long.
+** Return the number of bytes in the first nChar unicode characters
+** in pZ.  nChar must be non-negative.
+*/
+SQLITE_PRIVATE int sqlite3Utf16ByteLen(const void *zIn, int nChar){
+  int c;
+  unsigned char const *z = zIn;
+  int n = 0;
+  
+  if( SQLITE_UTF16NATIVE==SQLITE_UTF16BE ){
+    while( n<nChar ){
+      READ_UTF16BE(z, 1, c);
+      n++;
+    }
+  }else{
+    while( n<nChar ){
+      READ_UTF16LE(z, 1, c);
+      n++;
+    }
+  }
+  return (int)(z-(unsigned char const *)zIn);
+}
+
+#if defined(SQLITE_TEST)
+/*
+** This routine is called from the TCL test function "translate_selftest".
+** It checks that the primitives for serializing and deserializing
+** characters in each encoding are inverses of each other.
+*/
+SQLITE_PRIVATE void sqlite3UtfSelfTest(void){
+  unsigned int i, t;
+  unsigned char zBuf[20];
+  unsigned char *z;
+  int n;
+  unsigned int c;
+
+  for(i=0; i<0x00110000; i++){
+    z = zBuf;
+    WRITE_UTF8(z, i);
+    n = (int)(z-zBuf);
+    assert( n>0 && n<=4 );
+    z[0] = 0;
+    z = zBuf;
+    c = sqlite3Utf8Read(z, (const u8**)&z);
+    t = i;
+    if( i>=0xD800 && i<=0xDFFF ) t = 0xFFFD;
+    if( (i&0xFFFFFFFE)==0xFFFE ) t = 0xFFFD;
+    assert( c==t );
+    assert( (z-zBuf)==n );
+  }
+  for(i=0; i<0x00110000; i++){
+    if( i>=0xD800 && i<0xE000 ) continue;
+    z = zBuf;
+    WRITE_UTF16LE(z, i);
+    n = (int)(z-zBuf);
+    assert( n>0 && n<=4 );
+    z[0] = 0;
+    z = zBuf;
+    READ_UTF16LE(z, 1, c);
+    assert( c==i );
+    assert( (z-zBuf)==n );
+  }
+  for(i=0; i<0x00110000; i++){
+    if( i>=0xD800 && i<0xE000 ) continue;
+    z = zBuf;
+    WRITE_UTF16BE(z, i);
+    n = (int)(z-zBuf);
+    assert( n>0 && n<=4 );
+    z[0] = 0;
+    z = zBuf;
+    READ_UTF16BE(z, 1, c);
+    assert( c==i );
+    assert( (z-zBuf)==n );
+  }
+}
+#endif /* SQLITE_TEST */
+#endif /* SQLITE_OMIT_UTF16 */
+
+/************** End of utf.c *************************************************/
+/************** Begin file util.c ********************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** Utility functions used throughout sqlite.
+**
+** This file contains functions for allocating memory, comparing
+** strings, and stuff like that.
+**
+*/
+#ifdef SQLITE_HAVE_ISNAN
+# include <math.h>
+#endif
+
+/*
+** Routine needed to support the testcase() macro.
+*/
+#ifdef SQLITE_COVERAGE_TEST
+SQLITE_PRIVATE void sqlite3Coverage(int x){
+  static unsigned dummy = 0;
+  dummy += (unsigned)x;
+}
+#endif
+
+#ifndef SQLITE_OMIT_FLOATING_POINT
+/*
+** Return true if the floating point value is Not a Number (NaN).
+**
+** Use the math library isnan() function if compiled with SQLITE_HAVE_ISNAN.
+** Otherwise, we have our own implementation that works on most systems.
+*/
+SQLITE_PRIVATE int sqlite3IsNaN(double x){
+  int rc;   /* The value return */
+#if !defined(SQLITE_HAVE_ISNAN)
+  /*
+  ** Systems that support the isnan() library function should probably
+  ** make use of it by compiling with -DSQLITE_HAVE_ISNAN.  But we have
+  ** found that many systems do not have a working isnan() function so
+  ** this implementation is provided as an alternative.
+  **
+  ** This NaN test sometimes fails if compiled on GCC with -ffast-math.
+  ** On the other hand, the use of -ffast-math comes with the following
+  ** warning:
+  **
+  **      This option [-ffast-math] should never be turned on by any
+  **      -O option since it can result in incorrect output for programs
+  **      which depend on an exact implementation of IEEE or ISO 
+  **      rules/specifications for math functions.
+  **
+  ** Under MSVC, this NaN test may fail if compiled with a floating-
+  ** point precision mode other than /fp:precise.  From the MSDN 
+  ** documentation:
+  **
+  **      The compiler [with /fp:precise] will properly handle comparisons 
+  **      involving NaN. For example, x != x evaluates to true if x is NaN 
+  **      ...
+  */
+#ifdef __FAST_MATH__
+# error SQLite will not work correctly with the -ffast-math option of GCC.
+#endif
+  volatile double y = x;
+  volatile double z = y;
+  rc = (y!=z);
+#else  /* if defined(SQLITE_HAVE_ISNAN) */
+  rc = isnan(x);
+#endif /* SQLITE_HAVE_ISNAN */
+  testcase( rc );
+  return rc;
+}
+#endif /* SQLITE_OMIT_FLOATING_POINT */
+
+/*
+** Compute a string length that is limited to what can be stored in
+** lower 30 bits of a 32-bit signed integer.
+**
+** The value returned will never be negative.  Nor will it ever be greater
+** than the actual length of the string.  For very long strings (greater
+** than 1GiB) the value returned might be less than the true string length.
+*/
+SQLITE_PRIVATE int sqlite3Strlen30(const char *z){
+  const char *z2 = z;
+  if( z==0 ) return 0;
+  while( *z2 ){ z2++; }
+  return 0x3fffffff & (int)(z2 - z);
+}
+
+/*
+** Set the most recent error code and error string for the sqlite
+** handle "db". The error code is set to "err_code".
+**
+** If it is not NULL, string zFormat specifies the format of the
+** error string in the style of the printf functions: The following
+** format characters are allowed:
+**
+**      %s      Insert a string
+**      %z      A string that should be freed after use
+**      %d      Insert an integer
+**      %T      Insert a token
+**      %S      Insert the first element of a SrcList
+**
+** zFormat and any string tokens that follow it are assumed to be
+** encoded in UTF-8.
+**
+** To clear the most recent error for sqlite handle "db", sqlite3Error
+** should be called with err_code set to SQLITE_OK and zFormat set
+** to NULL.
+*/
+SQLITE_PRIVATE void sqlite3Error(sqlite3 *db, int err_code, const char *zFormat, ...){
+  if( db && (db->pErr || (db->pErr = sqlite3ValueNew(db))!=0) ){
+    db->errCode = err_code;
+    if( zFormat ){
+      char *z;
+      va_list ap;
+      va_start(ap, zFormat);
+      z = sqlite3VMPrintf(db, zFormat, ap);
+      va_end(ap);
+      sqlite3ValueSetStr(db->pErr, -1, z, SQLITE_UTF8, SQLITE_DYNAMIC);
+    }else{
+      sqlite3ValueSetStr(db->pErr, 0, 0, SQLITE_UTF8, SQLITE_STATIC);
+    }
+  }
+}
+
+/*
+** Add an error message to pParse->zErrMsg and increment pParse->nErr.
+** The following formatting characters are allowed:
+**
+**      %s      Insert a string
+**      %z      A string that should be freed after use
+**      %d      Insert an integer
+**      %T      Insert a token
+**      %S      Insert the first element of a SrcList
+**
+** This function should be used to report any error that occurs whilst
+** compiling an SQL statement (i.e. within sqlite3_prepare()). The
+** last thing the sqlite3_prepare() function does is copy the error
+** stored by this function into the database handle using sqlite3Error().
+** Function sqlite3Error() should be used during statement execution
+** (sqlite3_step() etc.).
+*/
+SQLITE_PRIVATE void sqlite3ErrorMsg(Parse *pParse, const char *zFormat, ...){
+  char *zMsg;
+  va_list ap;
+  sqlite3 *db = pParse->db;
+  va_start(ap, zFormat);
+  zMsg = sqlite3VMPrintf(db, zFormat, ap);
+  va_end(ap);
+  if( db->suppressErr ){
+    sqlite3DbFree(db, zMsg);
+  }else{
+    pParse->nErr++;
+    sqlite3DbFree(db, pParse->zErrMsg);
+    pParse->zErrMsg = zMsg;
+    pParse->rc = SQLITE_ERROR;
+  }
+}
+
+/*
+** Convert an SQL-style quoted string into a normal string by removing
+** the quote characters.  The conversion is done in-place.  If the
+** input does not begin with a quote character, then this routine
+** is a no-op.
+**
+** The input string must be zero-terminated.  A new zero-terminator
+** is added to the dequoted string.
+**
+** The return value is -1 if no dequoting occurs or the length of the
+** dequoted string, exclusive of the zero terminator, if dequoting does
+** occur.
+**
+** 2002-Feb-14: This routine is extended to remove MS-Access style
+** brackets from around identifers.  For example:  "[a-b-c]" becomes
+** "a-b-c".
+*/
+SQLITE_PRIVATE int sqlite3Dequote(char *z){
+  char quote;
+  int i, j;
+  if( z==0 ) return -1;
+  quote = z[0];
+  switch( quote ){
+    case '\'':  break;
+    case '"':   break;
+    case '`':   break;                /* For MySQL compatibility */
+    case '[':   quote = ']';  break;  /* For MS SqlServer compatibility */
+    default:    return -1;
+  }
+  for(i=1, j=0; ALWAYS(z[i]); i++){
+    if( z[i]==quote ){
+      if( z[i+1]==quote ){
+        z[j++] = quote;
+        i++;
+      }else{
+        break;
+      }
+    }else{
+      z[j++] = z[i];
+    }
+  }
+  z[j] = 0;
+  return j;
+}
+
+/* Convenient short-hand */
+#define UpperToLower sqlite3UpperToLower
+
+/*
+** Some systems have stricmp().  Others have strcasecmp().  Because
+** there is no consistency, we will define our own.
+**
+** IMPLEMENTATION-OF: R-20522-24639 The sqlite3_strnicmp() API allows
+** applications and extensions to compare the contents of two buffers
+** containing UTF-8 strings in a case-independent fashion, using the same
+** definition of case independence that SQLite uses internally when
+** comparing identifiers.
+*/
+SQLITE_PRIVATE int sqlite3StrICmp(const char *zLeft, const char *zRight){
+  register unsigned char *a, *b;
+  a = (unsigned char *)zLeft;
+  b = (unsigned char *)zRight;
+  while( *a!=0 && UpperToLower[*a]==UpperToLower[*b]){ a++; b++; }
+  return UpperToLower[*a] - UpperToLower[*b];
+}
+SQLITE_API int sqlite3_strnicmp(const char *zLeft, const char *zRight, int N){
+  register unsigned char *a, *b;
+  a = (unsigned char *)zLeft;
+  b = (unsigned char *)zRight;
+  while( N-- > 0 && *a!=0 && UpperToLower[*a]==UpperToLower[*b]){ a++; b++; }
+  return N<0 ? 0 : UpperToLower[*a] - UpperToLower[*b];
+}
+
+/*
+** The string z[] is an text representation of a real number.
+** Convert this string to a double and write it into *pResult.
+**
+** The string z[] is length bytes in length (bytes, not characters) and
+** uses the encoding enc.  The string is not necessarily zero-terminated.
+**
+** Return TRUE if the result is a valid real number (or integer) and FALSE
+** if the string is empty or contains extraneous text.  Valid numbers
+** are in one of these formats:
+**
+**    [+-]digits[E[+-]digits]
+**    [+-]digits.[digits][E[+-]digits]
+**    [+-].digits[E[+-]digits]
+**
+** Leading and trailing whitespace is ignored for the purpose of determining
+** validity.
+**
+** If some prefix of the input string is a valid number, this routine
+** returns FALSE but it still converts the prefix and writes the result
+** into *pResult.
+*/
+SQLITE_PRIVATE int sqlite3AtoF(const char *z, double *pResult, int length, u8 enc){
+#ifndef SQLITE_OMIT_FLOATING_POINT
+  int incr = (enc==SQLITE_UTF8?1:2);
+  const char *zEnd = z + length;
+  /* sign * significand * (10 ^ (esign * exponent)) */
+  int sign = 1;    /* sign of significand */
+  i64 s = 0;       /* significand */
+  int d = 0;       /* adjust exponent for shifting decimal point */
+  int esign = 1;   /* sign of exponent */
+  int e = 0;       /* exponent */
+  int eValid = 1;  /* True exponent is either not used or is well-formed */
+  double result;
+  int nDigits = 0;
+
+  *pResult = 0.0;   /* Default return value, in case of an error */
+
+  if( enc==SQLITE_UTF16BE ) z++;
+
+  /* skip leading spaces */
+  while( z<zEnd && sqlite3Isspace(*z) ) z+=incr;
+  if( z>=zEnd ) return 0;
+
+  /* get sign of significand */
+  if( *z=='-' ){
+    sign = -1;
+    z+=incr;
+  }else if( *z=='+' ){
+    z+=incr;
+  }
+
+  /* skip leading zeroes */
+  while( z<zEnd && z[0]=='0' ) z+=incr, nDigits++;
+
+  /* copy max significant digits to significand */
+  while( z<zEnd && sqlite3Isdigit(*z) && s<((LARGEST_INT64-9)/10) ){
+    s = s*10 + (*z - '0');
+    z+=incr, nDigits++;
+  }
+
+  /* skip non-significant significand digits
+  ** (increase exponent by d to shift decimal left) */
+  while( z<zEnd && sqlite3Isdigit(*z) ) z+=incr, nDigits++, d++;
+  if( z>=zEnd ) goto do_atof_calc;
+
+  /* if decimal point is present */
+  if( *z=='.' ){
+    z+=incr;
+    /* copy digits from after decimal to significand
+    ** (decrease exponent by d to shift decimal right) */
+    while( z<zEnd && sqlite3Isdigit(*z) && s<((LARGEST_INT64-9)/10) ){
+      s = s*10 + (*z - '0');
+      z+=incr, nDigits++, d--;
+    }
+    /* skip non-significant digits */
+    while( z<zEnd && sqlite3Isdigit(*z) ) z+=incr, nDigits++;
+  }
+  if( z>=zEnd ) goto do_atof_calc;
+
+  /* if exponent is present */
+  if( *z=='e' || *z=='E' ){
+    z+=incr;
+    eValid = 0;
+    if( z>=zEnd ) goto do_atof_calc;
+    /* get sign of exponent */
+    if( *z=='-' ){
+      esign = -1;
+      z+=incr;
+    }else if( *z=='+' ){
+      z+=incr;
+    }
+    /* copy digits to exponent */
+    while( z<zEnd && sqlite3Isdigit(*z) ){
+      e = e*10 + (*z - '0');
+      z+=incr;
+      eValid = 1;
+    }
+  }
+
+  /* skip trailing spaces */
+  if( nDigits && eValid ){
+    while( z<zEnd && sqlite3Isspace(*z) ) z+=incr;
+  }
+
+do_atof_calc:
+  /* adjust exponent by d, and update sign */
+  e = (e*esign) + d;
+  if( e<0 ) {
+    esign = -1;
+    e *= -1;
+  } else {
+    esign = 1;
+  }
+
+  /* if 0 significand */
+  if( !s ) {
+    /* In the IEEE 754 standard, zero is signed.
+    ** Add the sign if we've seen at least one digit */
+    result = (sign<0 && nDigits) ? -(double)0 : (double)0;
+  } else {
+    /* attempt to reduce exponent */
+    if( esign>0 ){
+      while( s<(LARGEST_INT64/10) && e>0 ) e--,s*=10;
+    }else{
+      while( !(s%10) && e>0 ) e--,s/=10;
+    }
+
+    /* adjust the sign of significand */
+    s = sign<0 ? -s : s;
+
+    /* if exponent, scale significand as appropriate
+    ** and store in result. */
+    if( e ){
+      double scale = 1.0;
+      /* attempt to handle extremely small/large numbers better */
+      if( e>307 && e<342 ){
+        while( e%308 ) { scale *= 1.0e+1; e -= 1; }
+        if( esign<0 ){
+          result = s / scale;
+          result /= 1.0e+308;
+        }else{
+          result = s * scale;
+          result *= 1.0e+308;
+        }
+      }else{
+        /* 1.0e+22 is the largest power of 10 than can be 
+        ** represented exactly. */
+        while( e%22 ) { scale *= 1.0e+1; e -= 1; }
+        while( e>0 ) { scale *= 1.0e+22; e -= 22; }
+        if( esign<0 ){
+          result = s / scale;
+        }else{
+          result = s * scale;
+        }
+      }
+    } else {
+      result = (double)s;
+    }
+  }
+
+  /* store the result */
+  *pResult = result;
+
+  /* return true if number and no extra non-whitespace chracters after */
+  return z>=zEnd && nDigits>0 && eValid;
+#else
+  return !sqlite3Atoi64(z, pResult, length, enc);
+#endif /* SQLITE_OMIT_FLOATING_POINT */
+}
+
+/*
+** Compare the 19-character string zNum against the text representation
+** value 2^63:  9223372036854775808.  Return negative, zero, or positive
+** if zNum is less than, equal to, or greater than the string.
+** Note that zNum must contain exactly 19 characters.
+**
+** Unlike memcmp() this routine is guaranteed to return the difference
+** in the values of the last digit if the only difference is in the
+** last digit.  So, for example,
+**
+**      compare2pow63("9223372036854775800", 1)
+**
+** will return -8.
+*/
+static int compare2pow63(const char *zNum, int incr){
+  int c = 0;
+  int i;
+                    /* 012345678901234567 */
+  const char *pow63 = "922337203685477580";
+  for(i=0; c==0 && i<18; i++){
+    c = (zNum[i*incr]-pow63[i])*10;
+  }
+  if( c==0 ){
+    c = zNum[18*incr] - '8';
+    testcase( c==(-1) );
+    testcase( c==0 );
+    testcase( c==(+1) );
+  }
+  return c;
+}
+
+
+/*
+** Convert zNum to a 64-bit signed integer.
+**
+** If the zNum value is representable as a 64-bit twos-complement 
+** integer, then write that value into *pNum and return 0.
+**
+** If zNum is exactly 9223372036854665808, return 2.  This special
+** case is broken out because while 9223372036854665808 cannot be a 
+** signed 64-bit integer, its negative -9223372036854665808 can be.
+**
+** If zNum is too big for a 64-bit integer and is not
+** 9223372036854665808 then return 1.
+**
+** length is the number of bytes in the string (bytes, not characters).
+** The string is not necessarily zero-terminated.  The encoding is
+** given by enc.
+*/
+SQLITE_PRIVATE int sqlite3Atoi64(const char *zNum, i64 *pNum, int length, u8 enc){
+  int incr = (enc==SQLITE_UTF8?1:2);
+  u64 u = 0;
+  int neg = 0; /* assume positive */
+  int i;
+  int c = 0;
+  const char *zStart;
+  const char *zEnd = zNum + length;
+  if( enc==SQLITE_UTF16BE ) zNum++;
+  while( zNum<zEnd && sqlite3Isspace(*zNum) ) zNum+=incr;
+  if( zNum<zEnd ){
+    if( *zNum=='-' ){
+      neg = 1;
+      zNum+=incr;
+    }else if( *zNum=='+' ){
+      zNum+=incr;
+    }
+  }
+  zStart = zNum;
+  while( zNum<zEnd && zNum[0]=='0' ){ zNum+=incr; } /* Skip leading zeros. */
+  for(i=0; &zNum[i]<zEnd && (c=zNum[i])>='0' && c<='9'; i+=incr){
+    u = u*10 + c - '0';
+  }
+  if( u>LARGEST_INT64 ){
+    *pNum = SMALLEST_INT64;
+  }else if( neg ){
+    *pNum = -(i64)u;
+  }else{
+    *pNum = (i64)u;
+  }
+  testcase( i==18 );
+  testcase( i==19 );
+  testcase( i==20 );
+  if( (c!=0 && &zNum[i]<zEnd) || (i==0 && zStart==zNum) || i>19*incr ){
+    /* zNum is empty or contains non-numeric text or is longer
+    ** than 19 digits (thus guaranteeing that it is too large) */
+    return 1;
+  }else if( i<19*incr ){
+    /* Less than 19 digits, so we know that it fits in 64 bits */
+    assert( u<=LARGEST_INT64 );
+    return 0;
+  }else{
+    /* zNum is a 19-digit numbers.  Compare it against 9223372036854775808. */
+    c = compare2pow63(zNum, incr);
+    if( c<0 ){
+      /* zNum is less than 9223372036854775808 so it fits */
+      assert( u<=LARGEST_INT64 );
+      return 0;
+    }else if( c>0 ){
+      /* zNum is greater than 9223372036854775808 so it overflows */
+      return 1;
+    }else{
+      /* zNum is exactly 9223372036854775808.  Fits if negative.  The
+      ** special case 2 overflow if positive */
+      assert( u-1==LARGEST_INT64 );
+      assert( (*pNum)==SMALLEST_INT64 );
+      return neg ? 0 : 2;
+    }
+  }
+}
+
+/*
+** If zNum represents an integer that will fit in 32-bits, then set
+** *pValue to that integer and return true.  Otherwise return false.
+**
+** Any non-numeric characters that following zNum are ignored.
+** This is different from sqlite3Atoi64() which requires the
+** input number to be zero-terminated.
+*/
+SQLITE_PRIVATE int sqlite3GetInt32(const char *zNum, int *pValue){
+  sqlite_int64 v = 0;
+  int i, c;
+  int neg = 0;
+  if( zNum[0]=='-' ){
+    neg = 1;
+    zNum++;
+  }else if( zNum[0]=='+' ){
+    zNum++;
+  }
+  while( zNum[0]=='0' ) zNum++;
+  for(i=0; i<11 && (c = zNum[i] - '0')>=0 && c<=9; i++){
+    v = v*10 + c;
+  }
+
+  /* The longest decimal representation of a 32 bit integer is 10 digits:
+  **
+  **             1234567890
+  **     2^31 -> 2147483648
+  */
+  testcase( i==10 );
+  if( i>10 ){
+    return 0;
+  }
+  testcase( v-neg==2147483647 );
+  if( v-neg>2147483647 ){
+    return 0;
+  }
+  if( neg ){
+    v = -v;
+  }
+  *pValue = (int)v;
+  return 1;
+}
+
+/*
+** Return a 32-bit integer value extracted from a string.  If the
+** string is not an integer, just return 0.
+*/
+SQLITE_PRIVATE int sqlite3Atoi(const char *z){
+  int x = 0;
+  if( z ) sqlite3GetInt32(z, &x);
+  return x;
+}
+
+/*
+** The variable-length integer encoding is as follows:
+**
+** KEY:
+**         A = 0xxxxxxx    7 bits of data and one flag bit
+**         B = 1xxxxxxx    7 bits of data and one flag bit
+**         C = xxxxxxxx    8 bits of data
+**
+**  7 bits - A
+** 14 bits - BA
+** 21 bits - BBA
+** 28 bits - BBBA
+** 35 bits - BBBBA
+** 42 bits - BBBBBA
+** 49 bits - BBBBBBA
+** 56 bits - BBBBBBBA
+** 64 bits - BBBBBBBBC
+*/
+
+/*
+** Write a 64-bit variable-length integer to memory starting at p[0].
+** The length of data write will be between 1 and 9 bytes.  The number
+** of bytes written is returned.
+**
+** A variable-length integer consists of the lower 7 bits of each byte
+** for all bytes that have the 8th bit set and one byte with the 8th
+** bit clear.  Except, if we get to the 9th byte, it stores the full
+** 8 bits and is the last byte.
+*/
+SQLITE_PRIVATE int sqlite3PutVarint(unsigned char *p, u64 v){
+  int i, j, n;
+  u8 buf[10];
+  if( v & (((u64)0xff000000)<<32) ){
+    p[8] = (u8)v;
+    v >>= 8;
+    for(i=7; i>=0; i--){
+      p[i] = (u8)((v & 0x7f) | 0x80);
+      v >>= 7;
+    }
+    return 9;
+  }    
+  n = 0;
+  do{
+    buf[n++] = (u8)((v & 0x7f) | 0x80);
+    v >>= 7;
+  }while( v!=0 );
+  buf[0] &= 0x7f;
+  assert( n<=9 );
+  for(i=0, j=n-1; j>=0; j--, i++){
+    p[i] = buf[j];
+  }
+  return n;
+}
+
+/*
+** This routine is a faster version of sqlite3PutVarint() that only
+** works for 32-bit positive integers and which is optimized for
+** the common case of small integers.  A MACRO version, putVarint32,
+** is provided which inlines the single-byte case.  All code should use
+** the MACRO version as this function assumes the single-byte case has
+** already been handled.
+*/
+SQLITE_PRIVATE int sqlite3PutVarint32(unsigned char *p, u32 v){
+#ifndef putVarint32
+  if( (v & ~0x7f)==0 ){
+    p[0] = v;
+    return 1;
+  }
+#endif
+  if( (v & ~0x3fff)==0 ){
+    p[0] = (u8)((v>>7) | 0x80);
+    p[1] = (u8)(v & 0x7f);
+    return 2;
+  }
+  return sqlite3PutVarint(p, v);
+}
+
+/*
+** Bitmasks used by sqlite3GetVarint().  These precomputed constants
+** are defined here rather than simply putting the constant expressions
+** inline in order to work around bugs in the RVT compiler.
+**
+** SLOT_2_0     A mask for  (0x7f<<14) | 0x7f
+**
+** SLOT_4_2_0   A mask for  (0x7f<<28) | SLOT_2_0
+*/
+#define SLOT_2_0     0x001fc07f
+#define SLOT_4_2_0   0xf01fc07f
+
+
+/*
+** Read a 64-bit variable-length integer from memory starting at p[0].
+** Return the number of bytes read.  The value is stored in *v.
+*/
+SQLITE_PRIVATE u8 sqlite3GetVarint(const unsigned char *p, u64 *v){
+  u32 a,b,s;
+
+  a = *p;
+  /* a: p0 (unmasked) */
+  if (!(a&0x80))
+  {
+    *v = a;
+    return 1;
+  }
+
+  p++;
+  b = *p;
+  /* b: p1 (unmasked) */
+  if (!(b&0x80))
+  {
+    a &= 0x7f;
+    a = a<<7;
+    a |= b;
+    *v = a;
+    return 2;
+  }
+
+  /* Verify that constants are precomputed correctly */
+  assert( SLOT_2_0 == ((0x7f<<14) | (0x7f)) );
+  assert( SLOT_4_2_0 == ((0xfU<<28) | (0x7f<<14) | (0x7f)) );
+
+  p++;
+  a = a<<14;
+  a |= *p;
+  /* a: p0<<14 | p2 (unmasked) */
+  if (!(a&0x80))
+  {
+    a &= SLOT_2_0;
+    b &= 0x7f;
+    b = b<<7;
+    a |= b;
+    *v = a;
+    return 3;
+  }
+
+  /* CSE1 from below */
+  a &= SLOT_2_0;
+  p++;
+  b = b<<14;
+  b |= *p;
+  /* b: p1<<14 | p3 (unmasked) */
+  if (!(b&0x80))
+  {
+    b &= SLOT_2_0;
+    /* moved CSE1 up */
+    /* a &= (0x7f<<14)|(0x7f); */
+    a = a<<7;
+    a |= b;
+    *v = a;
+    return 4;
+  }
+
+  /* a: p0<<14 | p2 (masked) */
+  /* b: p1<<14 | p3 (unmasked) */
+  /* 1:save off p0<<21 | p1<<14 | p2<<7 | p3 (masked) */
+  /* moved CSE1 up */
+  /* a &= (0x7f<<14)|(0x7f); */
+  b &= SLOT_2_0;
+  s = a;
+  /* s: p0<<14 | p2 (masked) */
+
+  p++;
+  a = a<<14;
+  a |= *p;
+  /* a: p0<<28 | p2<<14 | p4 (unmasked) */
+  if (!(a&0x80))
+  {
+    /* we can skip these cause they were (effectively) done above in calc'ing s */
+    /* a &= (0x7f<<28)|(0x7f<<14)|(0x7f); */
+    /* b &= (0x7f<<14)|(0x7f); */
+    b = b<<7;
+    a |= b;
+    s = s>>18;
+    *v = ((u64)s)<<32 | a;
+    return 5;
+  }
+
+  /* 2:save off p0<<21 | p1<<14 | p2<<7 | p3 (masked) */
+  s = s<<7;
+  s |= b;
+  /* s: p0<<21 | p1<<14 | p2<<7 | p3 (masked) */
+
+  p++;
+  b = b<<14;
+  b |= *p;
+  /* b: p1<<28 | p3<<14 | p5 (unmasked) */
+  if (!(b&0x80))
+  {
+    /* we can skip this cause it was (effectively) done above in calc'ing s */
+    /* b &= (0x7f<<28)|(0x7f<<14)|(0x7f); */
+    a &= SLOT_2_0;
+    a = a<<7;
+    a |= b;
+    s = s>>18;
+    *v = ((u64)s)<<32 | a;
+    return 6;
+  }
+
+  p++;
+  a = a<<14;
+  a |= *p;
+  /* a: p2<<28 | p4<<14 | p6 (unmasked) */
+  if (!(a&0x80))
+  {
+    a &= SLOT_4_2_0;
+    b &= SLOT_2_0;
+    b = b<<7;
+    a |= b;
+    s = s>>11;
+    *v = ((u64)s)<<32 | a;
+    return 7;
+  }
+
+  /* CSE2 from below */
+  a &= SLOT_2_0;
+  p++;
+  b = b<<14;
+  b |= *p;
+  /* b: p3<<28 | p5<<14 | p7 (unmasked) */
+  if (!(b&0x80))
+  {
+    b &= SLOT_4_2_0;
+    /* moved CSE2 up */
+    /* a &= (0x7f<<14)|(0x7f); */
+    a = a<<7;
+    a |= b;
+    s = s>>4;
+    *v = ((u64)s)<<32 | a;
+    return 8;
+  }
+
+  p++;
+  a = a<<15;
+  a |= *p;
+  /* a: p4<<29 | p6<<15 | p8 (unmasked) */
+
+  /* moved CSE2 up */
+  /* a &= (0x7f<<29)|(0x7f<<15)|(0xff); */
+  b &= SLOT_2_0;
+  b = b<<8;
+  a |= b;
+
+  s = s<<4;
+  b = p[-4];
+  b &= 0x7f;
+  b = b>>3;
+  s |= b;
+
+  *v = ((u64)s)<<32 | a;
+
+  return 9;
+}
+
+/*
+** Read a 32-bit variable-length integer from memory starting at p[0].
+** Return the number of bytes read.  The value is stored in *v.
+**
+** If the varint stored in p[0] is larger than can fit in a 32-bit unsigned
+** integer, then set *v to 0xffffffff.
+**
+** A MACRO version, getVarint32, is provided which inlines the 
+** single-byte case.  All code should use the MACRO version as 
+** this function assumes the single-byte case has already been handled.
+*/
+SQLITE_PRIVATE u8 sqlite3GetVarint32(const unsigned char *p, u32 *v){
+  u32 a,b;
+
+  /* The 1-byte case.  Overwhelmingly the most common.  Handled inline
+  ** by the getVarin32() macro */
+  a = *p;
+  /* a: p0 (unmasked) */
+#ifndef getVarint32
+  if (!(a&0x80))
+  {
+    /* Values between 0 and 127 */
+    *v = a;
+    return 1;
+  }
+#endif
+
+  /* The 2-byte case */
+  p++;
+  b = *p;
+  /* b: p1 (unmasked) */
+  if (!(b&0x80))
+  {
+    /* Values between 128 and 16383 */
+    a &= 0x7f;
+    a = a<<7;
+    *v = a | b;
+    return 2;
+  }
+
+  /* The 3-byte case */
+  p++;
+  a = a<<14;
+  a |= *p;
+  /* a: p0<<14 | p2 (unmasked) */
+  if (!(a&0x80))
+  {
+    /* Values between 16384 and 2097151 */
+    a &= (0x7f<<14)|(0x7f);
+    b &= 0x7f;
+    b = b<<7;
+    *v = a | b;
+    return 3;
+  }
+
+  /* A 32-bit varint is used to store size information in btrees.
+  ** Objects are rarely larger than 2MiB limit of a 3-byte varint.
+  ** A 3-byte varint is sufficient, for example, to record the size
+  ** of a 1048569-byte BLOB or string.
+  **
+  ** We only unroll the first 1-, 2-, and 3- byte cases.  The very
+  ** rare larger cases can be handled by the slower 64-bit varint
+  ** routine.
+  */
+#if 1
+  {
+    u64 v64;
+    u8 n;
+
+    p -= 2;
+    n = sqlite3GetVarint(p, &v64);
+    assert( n>3 && n<=9 );
+    if( (v64 & SQLITE_MAX_U32)!=v64 ){
+      *v = 0xffffffff;
+    }else{
+      *v = (u32)v64;
+    }
+    return n;
+  }
+
+#else
+  /* For following code (kept for historical record only) shows an
+  ** unrolling for the 3- and 4-byte varint cases.  This code is
+  ** slightly faster, but it is also larger and much harder to test.
+  */
+  p++;
+  b = b<<14;
+  b |= *p;
+  /* b: p1<<14 | p3 (unmasked) */
+  if (!(b&0x80))
+  {
+    /* Values between 2097152 and 268435455 */
+    b &= (0x7f<<14)|(0x7f);
+    a &= (0x7f<<14)|(0x7f);
+    a = a<<7;
+    *v = a | b;
+    return 4;
+  }
+
+  p++;
+  a = a<<14;
+  a |= *p;
+  /* a: p0<<28 | p2<<14 | p4 (unmasked) */
+  if (!(a&0x80))
+  {
+    /* Values  between 268435456 and 34359738367 */
+    a &= SLOT_4_2_0;
+    b &= SLOT_4_2_0;
+    b = b<<7;
+    *v = a | b;
+    return 5;
+  }
+
+  /* We can only reach this point when reading a corrupt database
+  ** file.  In that case we are not in any hurry.  Use the (relatively
+  ** slow) general-purpose sqlite3GetVarint() routine to extract the
+  ** value. */
+  {
+    u64 v64;
+    u8 n;
+
+    p -= 4;
+    n = sqlite3GetVarint(p, &v64);
+    assert( n>5 && n<=9 );
+    *v = (u32)v64;
+    return n;
+  }
+#endif
+}
+
+/*
+** Return the number of bytes that will be needed to store the given
+** 64-bit integer.
+*/
+SQLITE_PRIVATE int sqlite3VarintLen(u64 v){
+  int i = 0;
+  do{
+    i++;
+    v >>= 7;
+  }while( v!=0 && ALWAYS(i<9) );
+  return i;
+}
+
+
+/*
+** Read or write a four-byte big-endian integer value.
+*/
+SQLITE_PRIVATE u32 sqlite3Get4byte(const u8 *p){
+  return (p[0]<<24) | (p[1]<<16) | (p[2]<<8) | p[3];
+}
+SQLITE_PRIVATE void sqlite3Put4byte(unsigned char *p, u32 v){
+  p[0] = (u8)(v>>24);
+  p[1] = (u8)(v>>16);
+  p[2] = (u8)(v>>8);
+  p[3] = (u8)v;
+}
+
+
+
+#if !defined(SQLITE_OMIT_BLOB_LITERAL) || defined(SQLITE_HAS_CODEC)
+/*
+** Translate a single byte of Hex into an integer.
+** This routine only works if h really is a valid hexadecimal
+** character:  0..9a..fA..F
+*/
+static u8 hexToInt(int h){
+  assert( (h>='0' && h<='9') ||  (h>='a' && h<='f') ||  (h>='A' && h<='F') );
+#ifdef SQLITE_ASCII
+  h += 9*(1&(h>>6));
+#endif
+#ifdef SQLITE_EBCDIC
+  h += 9*(1&~(h>>4));
+#endif
+  return (u8)(h & 0xf);
+}
+#endif /* !SQLITE_OMIT_BLOB_LITERAL || SQLITE_HAS_CODEC */
+
+#if !defined(SQLITE_OMIT_BLOB_LITERAL) || defined(SQLITE_HAS_CODEC)
+/*
+** Convert a BLOB literal of the form "x'hhhhhh'" into its binary
+** value.  Return a pointer to its binary value.  Space to hold the
+** binary value has been obtained from malloc and must be freed by
+** the calling routine.
+*/
+SQLITE_PRIVATE void *sqlite3HexToBlob(sqlite3 *db, const char *z, int n){
+  char *zBlob;
+  int i;
+
+  zBlob = (char *)sqlite3DbMallocRaw(db, n/2 + 1);
+  n--;
+  if( zBlob ){
+    for(i=0; i<n; i+=2){
+      zBlob[i/2] = (hexToInt(z[i])<<4) | hexToInt(z[i+1]);
+    }
+    zBlob[i/2] = 0;
+  }
+  return zBlob;
+}
+#endif /* !SQLITE_OMIT_BLOB_LITERAL || SQLITE_HAS_CODEC */
+
+/*
+** Log an error that is an API call on a connection pointer that should
+** not have been used.  The "type" of connection pointer is given as the
+** argument.  The zType is a word like "NULL" or "closed" or "invalid".
+*/
+static void logBadConnection(const char *zType){
+  sqlite3_log(SQLITE_MISUSE, 
+     "API call with %s database connection pointer",
+     zType
+  );
+}
+
+/*
+** Check to make sure we have a valid db pointer.  This test is not
+** foolproof but it does provide some measure of protection against
+** misuse of the interface such as passing in db pointers that are
+** NULL or which have been previously closed.  If this routine returns
+** 1 it means that the db pointer is valid and 0 if it should not be
+** dereferenced for any reason.  The calling function should invoke
+** SQLITE_MISUSE immediately.
+**
+** sqlite3SafetyCheckOk() requires that the db pointer be valid for
+** use.  sqlite3SafetyCheckSickOrOk() allows a db pointer that failed to
+** open properly and is not fit for general use but which can be
+** used as an argument to sqlite3_errmsg() or sqlite3_close().
+*/
+SQLITE_PRIVATE int sqlite3SafetyCheckOk(sqlite3 *db){
+  u32 magic;
+  if( db==0 ){
+    logBadConnection("NULL");
+    return 0;
+  }
+  magic = db->magic;
+  if( magic!=SQLITE_MAGIC_OPEN ){
+    if( sqlite3SafetyCheckSickOrOk(db) ){
+      testcase( sqlite3GlobalConfig.xLog!=0 );
+      logBadConnection("unopened");
+    }
+    return 0;
+  }else{
+    return 1;
+  }
+}
+SQLITE_PRIVATE int sqlite3SafetyCheckSickOrOk(sqlite3 *db){
+  u32 magic;
+  magic = db->magic;
+  if( magic!=SQLITE_MAGIC_SICK &&
+      magic!=SQLITE_MAGIC_OPEN &&
+      magic!=SQLITE_MAGIC_BUSY ){
+    testcase( sqlite3GlobalConfig.xLog!=0 );
+    logBadConnection("invalid");
+    return 0;
+  }else{
+    return 1;
+  }
+}
+
+/*
+** Attempt to add, substract, or multiply the 64-bit signed value iB against
+** the other 64-bit signed integer at *pA and store the result in *pA.
+** Return 0 on success.  Or if the operation would have resulted in an
+** overflow, leave *pA unchanged and return 1.
+*/
+SQLITE_PRIVATE int sqlite3AddInt64(i64 *pA, i64 iB){
+  i64 iA = *pA;
+  testcase( iA==0 ); testcase( iA==1 );
+  testcase( iB==-1 ); testcase( iB==0 );
+  if( iB>=0 ){
+    testcase( iA>0 && LARGEST_INT64 - iA == iB );
+    testcase( iA>0 && LARGEST_INT64 - iA == iB - 1 );
+    if( iA>0 && LARGEST_INT64 - iA < iB ) return 1;
+    *pA += iB;
+  }else{
+    testcase( iA<0 && -(iA + LARGEST_INT64) == iB + 1 );
+    testcase( iA<0 && -(iA + LARGEST_INT64) == iB + 2 );
+    if( iA<0 && -(iA + LARGEST_INT64) > iB + 1 ) return 1;
+    *pA += iB;
+  }
+  return 0; 
+}
+SQLITE_PRIVATE int sqlite3SubInt64(i64 *pA, i64 iB){
+  testcase( iB==SMALLEST_INT64+1 );
+  if( iB==SMALLEST_INT64 ){
+    testcase( (*pA)==(-1) ); testcase( (*pA)==0 );
+    if( (*pA)>=0 ) return 1;
+    *pA -= iB;
+    return 0;
+  }else{
+    return sqlite3AddInt64(pA, -iB);
+  }
+}
+#define TWOPOWER32 (((i64)1)<<32)
+#define TWOPOWER31 (((i64)1)<<31)
+SQLITE_PRIVATE int sqlite3MulInt64(i64 *pA, i64 iB){
+  i64 iA = *pA;
+  i64 iA1, iA0, iB1, iB0, r;
+
+  iA1 = iA/TWOPOWER32;
+  iA0 = iA % TWOPOWER32;
+  iB1 = iB/TWOPOWER32;
+  iB0 = iB % TWOPOWER32;
+  if( iA1*iB1 != 0 ) return 1;
+  assert( iA1*iB0==0 || iA0*iB1==0 );
+  r = iA1*iB0 + iA0*iB1;
+  testcase( r==(-TWOPOWER31)-1 );
+  testcase( r==(-TWOPOWER31) );
+  testcase( r==TWOPOWER31 );
+  testcase( r==TWOPOWER31-1 );
+  if( r<(-TWOPOWER31) || r>=TWOPOWER31 ) return 1;
+  r *= TWOPOWER32;
+  if( sqlite3AddInt64(&r, iA0*iB0) ) return 1;
+  *pA = r;
+  return 0;
+}
+
+/*
+** Compute the absolute value of a 32-bit signed integer, of possible.  Or 
+** if the integer has a value of -2147483648, return +2147483647
+*/
+SQLITE_PRIVATE int sqlite3AbsInt32(int x){
+  if( x>=0 ) return x;
+  if( x==(int)0x80000000 ) return 0x7fffffff;
+  return -x;
+}
+
+/************** End of util.c ************************************************/
+/************** Begin file hash.c ********************************************/
+/*
+** 2001 September 22
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This is the implementation of generic hash-tables
+** used in SQLite.
+*/
+
+/* Turn bulk memory into a hash table object by initializing the
+** fields of the Hash structure.
+**
+** "pNew" is a pointer to the hash table that is to be initialized.
+*/
+SQLITE_PRIVATE void sqlite3HashInit(Hash *pNew){
+  assert( pNew!=0 );
+  pNew->first = 0;
+  pNew->count = 0;
+  pNew->htsize = 0;
+  pNew->ht = 0;
+}
+
+/* Remove all entries from a hash table.  Reclaim all memory.
+** Call this routine to delete a hash table or to reset a hash table
+** to the empty state.
+*/
+SQLITE_PRIVATE void sqlite3HashClear(Hash *pH){
+  HashElem *elem;         /* For looping over all elements of the table */
+
+  assert( pH!=0 );
+  elem = pH->first;
+  pH->first = 0;
+  sqlite3_free(pH->ht);
+  pH->ht = 0;
+  pH->htsize = 0;
+  while( elem ){
+    HashElem *next_elem = elem->next;
+    sqlite3_free(elem);
+    elem = next_elem;
+  }
+  pH->count = 0;
+}
+
+/*
+** The hashing function.
+*/
+static unsigned int strHash(const char *z, int nKey){
+  int h = 0;
+  assert( nKey>=0 );
+  while( nKey > 0  ){
+    h = (h<<3) ^ h ^ sqlite3UpperToLower[(unsigned char)*z++];
+    nKey--;
+  }
+  return h;
+}
+
+
+/* Link pNew element into the hash table pH.  If pEntry!=0 then also
+** insert pNew into the pEntry hash bucket.
+*/
+static void insertElement(
+  Hash *pH,              /* The complete hash table */
+  struct _ht *pEntry,    /* The entry into which pNew is inserted */
+  HashElem *pNew         /* The element to be inserted */
+){
+  HashElem *pHead;       /* First element already in pEntry */
+  if( pEntry ){
+    pHead = pEntry->count ? pEntry->chain : 0;
+    pEntry->count++;
+    pEntry->chain = pNew;
+  }else{
+    pHead = 0;
+  }
+  if( pHead ){
+    pNew->next = pHead;
+    pNew->prev = pHead->prev;
+    if( pHead->prev ){ pHead->prev->next = pNew; }
+    else             { pH->first = pNew; }
+    pHead->prev = pNew;
+  }else{
+    pNew->next = pH->first;
+    if( pH->first ){ pH->first->prev = pNew; }
+    pNew->prev = 0;
+    pH->first = pNew;
+  }
+}
+
+
+/* Resize the hash table so that it cantains "new_size" buckets.
+**
+** The hash table might fail to resize if sqlite3_malloc() fails or
+** if the new size is the same as the prior size.
+** Return TRUE if the resize occurs and false if not.
+*/
+static int rehash(Hash *pH, unsigned int new_size){
+  struct _ht *new_ht;            /* The new hash table */
+  HashElem *elem, *next_elem;    /* For looping over existing elements */
+
+#if SQLITE_MALLOC_SOFT_LIMIT>0
+  if( new_size*sizeof(struct _ht)>SQLITE_MALLOC_SOFT_LIMIT ){
+    new_size = SQLITE_MALLOC_SOFT_LIMIT/sizeof(struct _ht);
+  }
+  if( new_size==pH->htsize ) return 0;
+#endif
+
+  /* The inability to allocates space for a larger hash table is
+  ** a performance hit but it is not a fatal error.  So mark the
+  ** allocation as a benign.
+  */
+  sqlite3BeginBenignMalloc();
+  new_ht = (struct _ht *)sqlite3Malloc( new_size*sizeof(struct _ht) );
+  sqlite3EndBenignMalloc();
+
+  if( new_ht==0 ) return 0;
+  sqlite3_free(pH->ht);
+  pH->ht = new_ht;
+  pH->htsize = new_size = sqlite3MallocSize(new_ht)/sizeof(struct _ht);
+  memset(new_ht, 0, new_size*sizeof(struct _ht));
+  for(elem=pH->first, pH->first=0; elem; elem = next_elem){
+    unsigned int h = strHash(elem->pKey, elem->nKey) % new_size;
+    next_elem = elem->next;
+    insertElement(pH, &new_ht[h], elem);
+  }
+  return 1;
+}
+
+/* This function (for internal use only) locates an element in an
+** hash table that matches the given key.  The hash for this key has
+** already been computed and is passed as the 4th parameter.
+*/
+static HashElem *findElementGivenHash(
+  const Hash *pH,     /* The pH to be searched */
+  const char *pKey,   /* The key we are searching for */
+  int nKey,           /* Bytes in key (not counting zero terminator) */
+  unsigned int h      /* The hash for this key. */
+){
+  HashElem *elem;                /* Used to loop thru the element list */
+  int count;                     /* Number of elements left to test */
+
+  if( pH->ht ){
+    struct _ht *pEntry = &pH->ht[h];
+    elem = pEntry->chain;
+    count = pEntry->count;
+  }else{
+    elem = pH->first;
+    count = pH->count;
+  }
+  while( count-- && ALWAYS(elem) ){
+    if( elem->nKey==nKey && sqlite3StrNICmp(elem->pKey,pKey,nKey)==0 ){ 
+      return elem;
+    }
+    elem = elem->next;
+  }
+  return 0;
+}
+
+/* Remove a single entry from the hash table given a pointer to that
+** element and a hash on the element's key.
+*/
+static void removeElementGivenHash(
+  Hash *pH,         /* The pH containing "elem" */
+  HashElem* elem,   /* The element to be removed from the pH */
+  unsigned int h    /* Hash value for the element */
+){
+  struct _ht *pEntry;
+  if( elem->prev ){
+    elem->prev->next = elem->next; 
+  }else{
+    pH->first = elem->next;
+  }
+  if( elem->next ){
+    elem->next->prev = elem->prev;
+  }
+  if( pH->ht ){
+    pEntry = &pH->ht[h];
+    if( pEntry->chain==elem ){
+      pEntry->chain = elem->next;
+    }
+    pEntry->count--;
+    assert( pEntry->count>=0 );
+  }
+  sqlite3_free( elem );
+  pH->count--;
+  if( pH->count<=0 ){
+    assert( pH->first==0 );
+    assert( pH->count==0 );
+    sqlite3HashClear(pH);
+  }
+}
+
+/* Attempt to locate an element of the hash table pH with a key
+** that matches pKey,nKey.  Return the data for this element if it is
+** found, or NULL if there is no match.
+*/
+SQLITE_PRIVATE void *sqlite3HashFind(const Hash *pH, const char *pKey, int nKey){
+  HashElem *elem;    /* The element that matches key */
+  unsigned int h;    /* A hash on key */
+
+  assert( pH!=0 );
+  assert( pKey!=0 );
+  assert( nKey>=0 );
+  if( pH->ht ){
+    h = strHash(pKey, nKey) % pH->htsize;
+  }else{
+    h = 0;
+  }
+  elem = findElementGivenHash(pH, pKey, nKey, h);
+  return elem ? elem->data : 0;
+}
+
+/* Insert an element into the hash table pH.  The key is pKey,nKey
+** and the data is "data".
+**
+** If no element exists with a matching key, then a new
+** element is created and NULL is returned.
+**
+** If another element already exists with the same key, then the
+** new data replaces the old data and the old data is returned.
+** The key is not copied in this instance.  If a malloc fails, then
+** the new data is returned and the hash table is unchanged.
+**
+** If the "data" parameter to this function is NULL, then the
+** element corresponding to "key" is removed from the hash table.
+*/
+SQLITE_PRIVATE void *sqlite3HashInsert(Hash *pH, const char *pKey, int nKey, void *data){
+  unsigned int h;       /* the hash of the key modulo hash table size */
+  HashElem *elem;       /* Used to loop thru the element list */
+  HashElem *new_elem;   /* New element added to the pH */
+
+  assert( pH!=0 );
+  assert( pKey!=0 );
+  assert( nKey>=0 );
+  if( pH->htsize ){
+    h = strHash(pKey, nKey) % pH->htsize;
+  }else{
+    h = 0;
+  }
+  elem = findElementGivenHash(pH,pKey,nKey,h);
+  if( elem ){
+    void *old_data = elem->data;
+    if( data==0 ){
+      removeElementGivenHash(pH,elem,h);
+    }else{
+      elem->data = data;
+      elem->pKey = pKey;
+      assert(nKey==elem->nKey);
+    }
+    return old_data;
+  }
+  if( data==0 ) return 0;
+  new_elem = (HashElem*)sqlite3Malloc( sizeof(HashElem) );
+  if( new_elem==0 ) return data;
+  new_elem->pKey = pKey;
+  new_elem->nKey = nKey;
+  new_elem->data = data;
+  pH->count++;
+  if( pH->count>=10 && pH->count > 2*pH->htsize ){
+    if( rehash(pH, pH->count*2) ){
+      assert( pH->htsize>0 );
+      h = strHash(pKey, nKey) % pH->htsize;
+    }
+  }
+  if( pH->ht ){
+    insertElement(pH, &pH->ht[h], new_elem);
+  }else{
+    insertElement(pH, 0, new_elem);
+  }
+  return 0;
+}
+
+/************** End of hash.c ************************************************/
+/************** Begin file opcodes.c *****************************************/
+/* Automatically generated.  Do not edit */
+/* See the mkopcodec.awk script for details. */
+#if !defined(SQLITE_OMIT_EXPLAIN) || !defined(NDEBUG) || defined(VDBE_PROFILE) || defined(SQLITE_DEBUG)
+SQLITE_PRIVATE const char *sqlite3OpcodeName(int i){
+ static const char *const azName[] = { "?",
+     /*   1 */ "Goto",
+     /*   2 */ "Gosub",
+     /*   3 */ "Return",
+     /*   4 */ "Yield",
+     /*   5 */ "HaltIfNull",
+     /*   6 */ "Halt",
+     /*   7 */ "Integer",
+     /*   8 */ "Int64",
+     /*   9 */ "String",
+     /*  10 */ "Null",
+     /*  11 */ "Blob",
+     /*  12 */ "Variable",
+     /*  13 */ "Move",
+     /*  14 */ "Copy",
+     /*  15 */ "SCopy",
+     /*  16 */ "ResultRow",
+     /*  17 */ "CollSeq",
+     /*  18 */ "Function",
+     /*  19 */ "Not",
+     /*  20 */ "AddImm",
+     /*  21 */ "MustBeInt",
+     /*  22 */ "RealAffinity",
+     /*  23 */ "Permutation",
+     /*  24 */ "Compare",
+     /*  25 */ "Jump",
+     /*  26 */ "If",
+     /*  27 */ "IfNot",
+     /*  28 */ "Column",
+     /*  29 */ "Affinity",
+     /*  30 */ "MakeRecord",
+     /*  31 */ "Count",
+     /*  32 */ "Savepoint",
+     /*  33 */ "AutoCommit",
+     /*  34 */ "Transaction",
+     /*  35 */ "ReadCookie",
+     /*  36 */ "SetCookie",
+     /*  37 */ "VerifyCookie",
+     /*  38 */ "OpenRead",
+     /*  39 */ "OpenWrite",
+     /*  40 */ "OpenAutoindex",
+     /*  41 */ "OpenEphemeral",
+     /*  42 */ "OpenPseudo",
+     /*  43 */ "Close",
+     /*  44 */ "SeekLt",
+     /*  45 */ "SeekLe",
+     /*  46 */ "SeekGe",
+     /*  47 */ "SeekGt",
+     /*  48 */ "Seek",
+     /*  49 */ "NotFound",
+     /*  50 */ "Found",
+     /*  51 */ "IsUnique",
+     /*  52 */ "NotExists",
+     /*  53 */ "Sequence",
+     /*  54 */ "NewRowid",
+     /*  55 */ "Insert",
+     /*  56 */ "InsertInt",
+     /*  57 */ "Delete",
+     /*  58 */ "ResetCount",
+     /*  59 */ "RowKey",
+     /*  60 */ "RowData",
+     /*  61 */ "Rowid",
+     /*  62 */ "NullRow",
+     /*  63 */ "Last",
+     /*  64 */ "Sort",
+     /*  65 */ "Rewind",
+     /*  66 */ "Prev",
+     /*  67 */ "Next",
+     /*  68 */ "Or",
+     /*  69 */ "And",
+     /*  70 */ "IdxInsert",
+     /*  71 */ "IdxDelete",
+     /*  72 */ "IdxRowid",
+     /*  73 */ "IsNull",
+     /*  74 */ "NotNull",
+     /*  75 */ "Ne",
+     /*  76 */ "Eq",
+     /*  77 */ "Gt",
+     /*  78 */ "Le",
+     /*  79 */ "Lt",
+     /*  80 */ "Ge",
+     /*  81 */ "IdxLT",
+     /*  82 */ "BitAnd",
+     /*  83 */ "BitOr",
+     /*  84 */ "ShiftLeft",
+     /*  85 */ "ShiftRight",
+     /*  86 */ "Add",
+     /*  87 */ "Subtract",
+     /*  88 */ "Multiply",
+     /*  89 */ "Divide",
+     /*  90 */ "Remainder",
+     /*  91 */ "Concat",
+     /*  92 */ "IdxGE",
+     /*  93 */ "BitNot",
+     /*  94 */ "String8",
+     /*  95 */ "Destroy",
+     /*  96 */ "Clear",
+     /*  97 */ "CreateIndex",
+     /*  98 */ "CreateTable",
+     /*  99 */ "ParseSchema",
+     /* 100 */ "LoadAnalysis",
+     /* 101 */ "DropTable",
+     /* 102 */ "DropIndex",
+     /* 103 */ "DropTrigger",
+     /* 104 */ "IntegrityCk",
+     /* 105 */ "RowSetAdd",
+     /* 106 */ "RowSetRead",
+     /* 107 */ "RowSetTest",
+     /* 108 */ "Program",
+     /* 109 */ "Param",
+     /* 110 */ "FkCounter",
+     /* 111 */ "FkIfZero",
+     /* 112 */ "MemMax",
+     /* 113 */ "IfPos",
+     /* 114 */ "IfNeg",
+     /* 115 */ "IfZero",
+     /* 116 */ "AggStep",
+     /* 117 */ "AggFinal",
+     /* 118 */ "Checkpoint",
+     /* 119 */ "JournalMode",
+     /* 120 */ "Vacuum",
+     /* 121 */ "IncrVacuum",
+     /* 122 */ "Expire",
+     /* 123 */ "TableLock",
+     /* 124 */ "VBegin",
+     /* 125 */ "VCreate",
+     /* 126 */ "VDestroy",
+     /* 127 */ "VOpen",
+     /* 128 */ "VFilter",
+     /* 129 */ "VColumn",
+     /* 130 */ "Real",
+     /* 131 */ "VNext",
+     /* 132 */ "VRename",
+     /* 133 */ "VUpdate",
+     /* 134 */ "Pagecount",
+     /* 135 */ "MaxPgcnt",
+     /* 136 */ "Trace",
+     /* 137 */ "Noop",
+     /* 138 */ "Explain",
+     /* 139 */ "NotUsed_139",
+     /* 140 */ "NotUsed_140",
+     /* 141 */ "ToText",
+     /* 142 */ "ToBlob",
+     /* 143 */ "ToNumeric",
+     /* 144 */ "ToInt",
+     /* 145 */ "ToReal",
+  };
+  return azName[i];
+}
+#endif
+
+/************** End of opcodes.c *********************************************/
+/************** Begin file os_os2.c ******************************************/
+/*
+** 2006 Feb 14
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains code that is specific to OS/2.
+*/
+
+
+#if SQLITE_OS_OS2
+
+/*
+** A Note About Memory Allocation:
+**
+** This driver uses malloc()/free() directly rather than going through
+** the SQLite-wrappers sqlite3_malloc()/sqlite3_free().  Those wrappers
+** are designed for use on embedded systems where memory is scarce and
+** malloc failures happen frequently.  OS/2 does not typically run on
+** embedded systems, and when it does the developers normally have bigger
+** problems to worry about than running out of memory.  So there is not
+** a compelling need to use the wrappers.
+**
+** But there is a good reason to not use the wrappers.  If we use the
+** wrappers then we will get simulated malloc() failures within this
+** driver.  And that causes all kinds of problems for our tests.  We
+** could enhance SQLite to deal with simulated malloc failures within
+** the OS driver, but the code to deal with those failure would not
+** be exercised on Linux (which does not need to malloc() in the driver)
+** and so we would have difficulty writing coverage tests for that
+** code.  Better to leave the code out, we think.
+**
+** The point of this discussion is as follows:  When creating a new
+** OS layer for an embedded system, if you use this file as an example,
+** avoid the use of malloc()/free().  Those routines work ok on OS/2
+** desktops but not so well in embedded systems.
+*/
+
+/*
+** Macros used to determine whether or not to use threads.
+*/
+#if defined(SQLITE_THREADSAFE) && SQLITE_THREADSAFE
+# define SQLITE_OS2_THREADS 1
+#endif
+
+/*
+** Include code that is common to all os_*.c files
+*/
+/************** Include os_common.h in the middle of os_os2.c ****************/
+/************** Begin file os_common.h ***************************************/
+/*
+** 2004 May 22
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains macros and a little bit of code that is common to
+** all of the platform-specific files (os_*.c) and is #included into those
+** files.
+**
+** This file should be #included by the os_*.c files only.  It is not a
+** general purpose header file.
+*/
+#ifndef _OS_COMMON_H_
+#define _OS_COMMON_H_
+
+/*
+** At least two bugs have slipped in because we changed the MEMORY_DEBUG
+** macro to SQLITE_DEBUG and some older makefiles have not yet made the
+** switch.  The following code should catch this problem at compile-time.
+*/
+#ifdef MEMORY_DEBUG
+# error "The MEMORY_DEBUG macro is obsolete.  Use SQLITE_DEBUG instead."
+#endif
+
+#ifdef SQLITE_DEBUG
+SQLITE_PRIVATE int sqlite3OSTrace = 0;
+#define OSTRACE(X)          if( sqlite3OSTrace ) sqlite3DebugPrintf X
+#else
+#define OSTRACE(X)
+#endif
+
+/*
+** Macros for performance tracing.  Normally turned off.  Only works
+** on i486 hardware.
+*/
+#ifdef SQLITE_PERFORMANCE_TRACE
+
+/* 
+** hwtime.h contains inline assembler code for implementing 
+** high-performance timing routines.
+*/
+/************** Include hwtime.h in the middle of os_common.h ****************/
+/************** Begin file hwtime.h ******************************************/
+/*
+** 2008 May 27
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains inline asm code for retrieving "high-performance"
+** counters for x86 class CPUs.
+*/
+#ifndef _HWTIME_H_
+#define _HWTIME_H_
+
+/*
+** The following routine only works on pentium-class (or newer) processors.
+** It uses the RDTSC opcode to read the cycle count value out of the
+** processor and returns that value.  This can be used for high-res
+** profiling.
+*/
+#if (defined(__GNUC__) || defined(_MSC_VER)) && \
+      (defined(i386) || defined(__i386__) || defined(_M_IX86))
+
+  #if defined(__GNUC__)
+
+  __inline__ sqlite_uint64 sqlite3Hwtime(void){
+     unsigned int lo, hi;
+     __asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi));
+     return (sqlite_uint64)hi << 32 | lo;
+  }
+
+  #elif defined(_MSC_VER)
+
+  __declspec(naked) __inline sqlite_uint64 __cdecl sqlite3Hwtime(void){
+     __asm {
+        rdtsc
+        ret       ; return value at EDX:EAX
+     }
+  }
+
+  #endif
+
+#elif (defined(__GNUC__) && defined(__x86_64__))
+
+  __inline__ sqlite_uint64 sqlite3Hwtime(void){
+      unsigned long val;
+      __asm__ __volatile__ ("rdtsc" : "=A" (val));
+      return val;
+  }
+ 
+#elif (defined(__GNUC__) && defined(__ppc__))
+
+  __inline__ sqlite_uint64 sqlite3Hwtime(void){
+      unsigned long long retval;
+      unsigned long junk;
+      __asm__ __volatile__ ("\n\
+          1:      mftbu   %1\n\
+                  mftb    %L0\n\
+                  mftbu   %0\n\
+                  cmpw    %0,%1\n\
+                  bne     1b"
+                  : "=r" (retval), "=r" (junk));
+      return retval;
+  }
+
+#else
+
+  #error Need implementation of sqlite3Hwtime() for your platform.
+
+  /*
+  ** To compile without implementing sqlite3Hwtime() for your platform,
+  ** you can remove the above #error and use the following
+  ** stub function.  You will lose timing support for many
+  ** of the debugging and testing utilities, but it should at
+  ** least compile and run.
+  */
+SQLITE_PRIVATE   sqlite_uint64 sqlite3Hwtime(void){ return ((sqlite_uint64)0); }
+
+#endif
+
+#endif /* !defined(_HWTIME_H_) */
+
+/************** End of hwtime.h **********************************************/
+/************** Continuing where we left off in os_common.h ******************/
+
+static sqlite_uint64 g_start;
+static sqlite_uint64 g_elapsed;
+#define TIMER_START       g_start=sqlite3Hwtime()
+#define TIMER_END         g_elapsed=sqlite3Hwtime()-g_start
+#define TIMER_ELAPSED     g_elapsed
+#else
+#define TIMER_START
+#define TIMER_END
+#define TIMER_ELAPSED     ((sqlite_uint64)0)
+#endif
+
+/*
+** If we compile with the SQLITE_TEST macro set, then the following block
+** of code will give us the ability to simulate a disk I/O error.  This
+** is used for testing the I/O recovery logic.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_io_error_hit = 0;            /* Total number of I/O Errors */
+SQLITE_API int sqlite3_io_error_hardhit = 0;        /* Number of non-benign errors */
+SQLITE_API int sqlite3_io_error_pending = 0;        /* Count down to first I/O error */
+SQLITE_API int sqlite3_io_error_persist = 0;        /* True if I/O errors persist */
+SQLITE_API int sqlite3_io_error_benign = 0;         /* True if errors are benign */
+SQLITE_API int sqlite3_diskfull_pending = 0;
+SQLITE_API int sqlite3_diskfull = 0;
+#define SimulateIOErrorBenign(X) sqlite3_io_error_benign=(X)
+#define SimulateIOError(CODE)  \
+  if( (sqlite3_io_error_persist && sqlite3_io_error_hit) \
+       || sqlite3_io_error_pending-- == 1 )  \
+              { local_ioerr(); CODE; }
+static void local_ioerr(){
+  IOTRACE(("IOERR\n"));
+  sqlite3_io_error_hit++;
+  if( !sqlite3_io_error_benign ) sqlite3_io_error_hardhit++;
+}
+#define SimulateDiskfullError(CODE) \
+   if( sqlite3_diskfull_pending ){ \
+     if( sqlite3_diskfull_pending == 1 ){ \
+       local_ioerr(); \
+       sqlite3_diskfull = 1; \
+       sqlite3_io_error_hit = 1; \
+       CODE; \
+     }else{ \
+       sqlite3_diskfull_pending--; \
+     } \
+   }
+#else
+#define SimulateIOErrorBenign(X)
+#define SimulateIOError(A)
+#define SimulateDiskfullError(A)
+#endif
+
+/*
+** When testing, keep a count of the number of open files.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_open_file_count = 0;
+#define OpenCounter(X)  sqlite3_open_file_count+=(X)
+#else
+#define OpenCounter(X)
+#endif
+
+#endif /* !defined(_OS_COMMON_H_) */
+
+/************** End of os_common.h *******************************************/
+/************** Continuing where we left off in os_os2.c *********************/
+
+/* Forward references */
+typedef struct os2File os2File;         /* The file structure */
+typedef struct os2ShmNode os2ShmNode;   /* A shared descritive memory node */
+typedef struct os2ShmLink os2ShmLink;   /* A connection to shared-memory */
+
+/*
+** The os2File structure is subclass of sqlite3_file specific for the OS/2
+** protability layer.
+*/
+struct os2File {
+  const sqlite3_io_methods *pMethod;  /* Always the first entry */
+  HFILE h;                  /* Handle for accessing the file */
+  int flags;                /* Flags provided to os2Open() */
+  int locktype;             /* Type of lock currently held on this file */
+  int szChunk;              /* Chunk size configured by FCNTL_CHUNK_SIZE */
+  char *zFullPathCp;        /* Full path name of this file */
+  os2ShmLink *pShmLink;     /* Instance of shared memory on this file */
+};
+
+#define LOCK_TIMEOUT 10L /* the default locking timeout */
+
+/*
+** Missing from some versions of the OS/2 toolkit -
+** used to allocate from high memory if possible
+*/
+#ifndef OBJ_ANY
+# define OBJ_ANY 0x00000400
+#endif
+
+/*****************************************************************************
+** The next group of routines implement the I/O methods specified
+** by the sqlite3_io_methods object.
+******************************************************************************/
+
+/*
+** Close a file.
+*/
+static int os2Close( sqlite3_file *id ){
+  APIRET rc;
+  os2File *pFile = (os2File*)id;
+
+  assert( id!=0 );
+  OSTRACE(( "CLOSE %d (%s)\n", pFile->h, pFile->zFullPathCp ));
+
+  rc = DosClose( pFile->h );
+
+  if( pFile->flags & SQLITE_OPEN_DELETEONCLOSE )
+    DosForceDelete( (PSZ)pFile->zFullPathCp );
+
+  free( pFile->zFullPathCp );
+  pFile->zFullPathCp = NULL;
+  pFile->locktype = NO_LOCK;
+  pFile->h = (HFILE)-1;
+  pFile->flags = 0;
+
+  OpenCounter( -1 );
+  return rc == NO_ERROR ? SQLITE_OK : SQLITE_IOERR;
+}
+
+/*
+** Read data from a file into a buffer.  Return SQLITE_OK if all
+** bytes were read successfully and SQLITE_IOERR if anything goes
+** wrong.
+*/
+static int os2Read(
+  sqlite3_file *id,               /* File to read from */
+  void *pBuf,                     /* Write content into this buffer */
+  int amt,                        /* Number of bytes to read */
+  sqlite3_int64 offset            /* Begin reading at this offset */
+){
+  ULONG fileLocation = 0L;
+  ULONG got;
+  os2File *pFile = (os2File*)id;
+  assert( id!=0 );
+  SimulateIOError( return SQLITE_IOERR_READ );
+  OSTRACE(( "READ %d lock=%d\n", pFile->h, pFile->locktype ));
+  if( DosSetFilePtr(pFile->h, offset, FILE_BEGIN, &fileLocation) != NO_ERROR ){
+    return SQLITE_IOERR;
+  }
+  if( DosRead( pFile->h, pBuf, amt, &got ) != NO_ERROR ){
+    return SQLITE_IOERR_READ;
+  }
+  if( got == (ULONG)amt )
+    return SQLITE_OK;
+  else {
+    /* Unread portions of the input buffer must be zero-filled */
+    memset(&((char*)pBuf)[got], 0, amt-got);
+    return SQLITE_IOERR_SHORT_READ;
+  }
+}
+
+/*
+** Write data from a buffer into a file.  Return SQLITE_OK on success
+** or some other error code on failure.
+*/
+static int os2Write(
+  sqlite3_file *id,               /* File to write into */
+  const void *pBuf,               /* The bytes to be written */
+  int amt,                        /* Number of bytes to write */
+  sqlite3_int64 offset            /* Offset into the file to begin writing at */
+){
+  ULONG fileLocation = 0L;
+  APIRET rc = NO_ERROR;
+  ULONG wrote;
+  os2File *pFile = (os2File*)id;
+  assert( id!=0 );
+  SimulateIOError( return SQLITE_IOERR_WRITE );
+  SimulateDiskfullError( return SQLITE_FULL );
+  OSTRACE(( "WRITE %d lock=%d\n", pFile->h, pFile->locktype ));
+  if( DosSetFilePtr(pFile->h, offset, FILE_BEGIN, &fileLocation) != NO_ERROR ){
+    return SQLITE_IOERR;
+  }
+  assert( amt>0 );
+  while( amt > 0 &&
+         ( rc = DosWrite( pFile->h, (PVOID)pBuf, amt, &wrote ) ) == NO_ERROR &&
+         wrote > 0
+  ){
+    amt -= wrote;
+    pBuf = &((char*)pBuf)[wrote];
+  }
+
+  return ( rc != NO_ERROR || amt > (int)wrote ) ? SQLITE_FULL : SQLITE_OK;
+}
+
+/*
+** Truncate an open file to a specified size
+*/
+static int os2Truncate( sqlite3_file *id, i64 nByte ){
+  APIRET rc;
+  os2File *pFile = (os2File*)id;
+  assert( id!=0 );
+  OSTRACE(( "TRUNCATE %d %lld\n", pFile->h, nByte ));
+  SimulateIOError( return SQLITE_IOERR_TRUNCATE );
+
+  /* If the user has configured a chunk-size for this file, truncate the
+  ** file so that it consists of an integer number of chunks (i.e. the
+  ** actual file size after the operation may be larger than the requested
+  ** size).
+  */
+  if( pFile->szChunk ){
+    nByte = ((nByte + pFile->szChunk - 1)/pFile->szChunk) * pFile->szChunk;
+  }
+  
+  rc = DosSetFileSize( pFile->h, nByte );
+  return rc == NO_ERROR ? SQLITE_OK : SQLITE_IOERR_TRUNCATE;
+}
+
+#ifdef SQLITE_TEST
+/*
+** Count the number of fullsyncs and normal syncs.  This is used to test
+** that syncs and fullsyncs are occuring at the right times.
+*/
+SQLITE_API int sqlite3_sync_count = 0;
+SQLITE_API int sqlite3_fullsync_count = 0;
+#endif
+
+/*
+** Make sure all writes to a particular file are committed to disk.
+*/
+static int os2Sync( sqlite3_file *id, int flags ){
+  os2File *pFile = (os2File*)id;
+  OSTRACE(( "SYNC %d lock=%d\n", pFile->h, pFile->locktype ));
+#ifdef SQLITE_TEST
+  if( flags & SQLITE_SYNC_FULL){
+    sqlite3_fullsync_count++;
+  }
+  sqlite3_sync_count++;
+#endif
+  /* If we compiled with the SQLITE_NO_SYNC flag, then syncing is a
+  ** no-op
+  */
+#ifdef SQLITE_NO_SYNC
+  UNUSED_PARAMETER(pFile);
+  return SQLITE_OK;
+#else
+  return DosResetBuffer( pFile->h ) == NO_ERROR ? SQLITE_OK : SQLITE_IOERR;
+#endif
+}
+
+/*
+** Determine the current size of a file in bytes
+*/
+static int os2FileSize( sqlite3_file *id, sqlite3_int64 *pSize ){
+  APIRET rc = NO_ERROR;
+  FILESTATUS3 fsts3FileInfo;
+  memset(&fsts3FileInfo, 0, sizeof(fsts3FileInfo));
+  assert( id!=0 );
+  SimulateIOError( return SQLITE_IOERR_FSTAT );
+  rc = DosQueryFileInfo( ((os2File*)id)->h, FIL_STANDARD, &fsts3FileInfo, sizeof(FILESTATUS3) );
+  if( rc == NO_ERROR ){
+    *pSize = fsts3FileInfo.cbFile;
+    return SQLITE_OK;
+  }else{
+    return SQLITE_IOERR_FSTAT;
+  }
+}
+
+/*
+** Acquire a reader lock.
+*/
+static int getReadLock( os2File *pFile ){
+  FILELOCK  LockArea,
+            UnlockArea;
+  APIRET res;
+  memset(&LockArea, 0, sizeof(LockArea));
+  memset(&UnlockArea, 0, sizeof(UnlockArea));
+  LockArea.lOffset = SHARED_FIRST;
+  LockArea.lRange = SHARED_SIZE;
+  UnlockArea.lOffset = 0L;
+  UnlockArea.lRange = 0L;
+  res = DosSetFileLocks( pFile->h, &UnlockArea, &LockArea, LOCK_TIMEOUT, 1L );
+  OSTRACE(( "GETREADLOCK %d res=%d\n", pFile->h, res ));
+  return res;
+}
+
+/*
+** Undo a readlock
+*/
+static int unlockReadLock( os2File *id ){
+  FILELOCK  LockArea,
+            UnlockArea;
+  APIRET res;
+  memset(&LockArea, 0, sizeof(LockArea));
+  memset(&UnlockArea, 0, sizeof(UnlockArea));
+  LockArea.lOffset = 0L;
+  LockArea.lRange = 0L;
+  UnlockArea.lOffset = SHARED_FIRST;
+  UnlockArea.lRange = SHARED_SIZE;
+  res = DosSetFileLocks( id->h, &UnlockArea, &LockArea, LOCK_TIMEOUT, 1L );
+  OSTRACE(( "UNLOCK-READLOCK file handle=%d res=%d?\n", id->h, res ));
+  return res;
+}
+
+/*
+** Lock the file with the lock specified by parameter locktype - one
+** of the following:
+**
+**     (1) SHARED_LOCK
+**     (2) RESERVED_LOCK
+**     (3) PENDING_LOCK
+**     (4) EXCLUSIVE_LOCK
+**
+** Sometimes when requesting one lock state, additional lock states
+** are inserted in between.  The locking might fail on one of the later
+** transitions leaving the lock state different from what it started but
+** still short of its goal.  The following chart shows the allowed
+** transitions and the inserted intermediate states:
+**
+**    UNLOCKED -> SHARED
+**    SHARED -> RESERVED
+**    SHARED -> (PENDING) -> EXCLUSIVE
+**    RESERVED -> (PENDING) -> EXCLUSIVE
+**    PENDING -> EXCLUSIVE
+**
+** This routine will only increase a lock.  The os2Unlock() routine
+** erases all locks at once and returns us immediately to locking level 0.
+** It is not possible to lower the locking level one step at a time.  You
+** must go straight to locking level 0.
+*/
+static int os2Lock( sqlite3_file *id, int locktype ){
+  int rc = SQLITE_OK;       /* Return code from subroutines */
+  APIRET res = NO_ERROR;    /* Result of an OS/2 lock call */
+  int newLocktype;       /* Set pFile->locktype to this value before exiting */
+  int gotPendingLock = 0;/* True if we acquired a PENDING lock this time */
+  FILELOCK  LockArea,
+            UnlockArea;
+  os2File *pFile = (os2File*)id;
+  memset(&LockArea, 0, sizeof(LockArea));
+  memset(&UnlockArea, 0, sizeof(UnlockArea));
+  assert( pFile!=0 );
+  OSTRACE(( "LOCK %d %d was %d\n", pFile->h, locktype, pFile->locktype ));
+
+  /* If there is already a lock of this type or more restrictive on the
+  ** os2File, do nothing. Don't use the end_lock: exit path, as
+  ** sqlite3_mutex_enter() hasn't been called yet.
+  */
+  if( pFile->locktype>=locktype ){
+    OSTRACE(( "LOCK %d %d ok (already held)\n", pFile->h, locktype ));
+    return SQLITE_OK;
+  }
+
+  /* Make sure the locking sequence is correct
+  */
+  assert( pFile->locktype!=NO_LOCK || locktype==SHARED_LOCK );
+  assert( locktype!=PENDING_LOCK );
+  assert( locktype!=RESERVED_LOCK || pFile->locktype==SHARED_LOCK );
+
+  /* Lock the PENDING_LOCK byte if we need to acquire a PENDING lock or
+  ** a SHARED lock.  If we are acquiring a SHARED lock, the acquisition of
+  ** the PENDING_LOCK byte is temporary.
+  */
+  newLocktype = pFile->locktype;
+  if( pFile->locktype==NO_LOCK
+      || (locktype==EXCLUSIVE_LOCK && pFile->locktype==RESERVED_LOCK)
+  ){
+    LockArea.lOffset = PENDING_BYTE;
+    LockArea.lRange = 1L;
+    UnlockArea.lOffset = 0L;
+    UnlockArea.lRange = 0L;
+
+    /* wait longer than LOCK_TIMEOUT here not to have to try multiple times */
+    res = DosSetFileLocks( pFile->h, &UnlockArea, &LockArea, 100L, 0L );
+    if( res == NO_ERROR ){
+      gotPendingLock = 1;
+      OSTRACE(( "LOCK %d pending lock boolean set.  res=%d\n", pFile->h, res ));
+    }
+  }
+
+  /* Acquire a shared lock
+  */
+  if( locktype==SHARED_LOCK && res == NO_ERROR ){
+    assert( pFile->locktype==NO_LOCK );
+    res = getReadLock(pFile);
+    if( res == NO_ERROR ){
+      newLocktype = SHARED_LOCK;
+    }
+    OSTRACE(( "LOCK %d acquire shared lock. res=%d\n", pFile->h, res ));
+  }
+
+  /* Acquire a RESERVED lock
+  */
+  if( locktype==RESERVED_LOCK && res == NO_ERROR ){
+    assert( pFile->locktype==SHARED_LOCK );
+    LockArea.lOffset = RESERVED_BYTE;
+    LockArea.lRange = 1L;
+    UnlockArea.lOffset = 0L;
+    UnlockArea.lRange = 0L;
+    res = DosSetFileLocks( pFile->h, &UnlockArea, &LockArea, LOCK_TIMEOUT, 0L );
+    if( res == NO_ERROR ){
+      newLocktype = RESERVED_LOCK;
+    }
+    OSTRACE(( "LOCK %d acquire reserved lock. res=%d\n", pFile->h, res ));
+  }
+
+  /* Acquire a PENDING lock
+  */
+  if( locktype==EXCLUSIVE_LOCK && res == NO_ERROR ){
+    newLocktype = PENDING_LOCK;
+    gotPendingLock = 0;
+    OSTRACE(( "LOCK %d acquire pending lock. pending lock boolean unset.\n",
+               pFile->h ));
+  }
+
+  /* Acquire an EXCLUSIVE lock
+  */
+  if( locktype==EXCLUSIVE_LOCK && res == NO_ERROR ){
+    assert( pFile->locktype>=SHARED_LOCK );
+    res = unlockReadLock(pFile);
+    OSTRACE(( "unreadlock = %d\n", res ));
+    LockArea.lOffset = SHARED_FIRST;
+    LockArea.lRange = SHARED_SIZE;
+    UnlockArea.lOffset = 0L;
+    UnlockArea.lRange = 0L;
+    res = DosSetFileLocks( pFile->h, &UnlockArea, &LockArea, LOCK_TIMEOUT, 0L );
+    if( res == NO_ERROR ){
+      newLocktype = EXCLUSIVE_LOCK;
+    }else{
+      OSTRACE(( "OS/2 error-code = %d\n", res ));
+      getReadLock(pFile);
+    }
+    OSTRACE(( "LOCK %d acquire exclusive lock.  res=%d\n", pFile->h, res ));
+  }
+
+  /* If we are holding a PENDING lock that ought to be released, then
+  ** release it now.
+  */
+  if( gotPendingLock && locktype==SHARED_LOCK ){
+    int r;
+    LockArea.lOffset = 0L;
+    LockArea.lRange = 0L;
+    UnlockArea.lOffset = PENDING_BYTE;
+    UnlockArea.lRange = 1L;
+    r = DosSetFileLocks( pFile->h, &UnlockArea, &LockArea, LOCK_TIMEOUT, 0L );
+    OSTRACE(( "LOCK %d unlocking pending/is shared. r=%d\n", pFile->h, r ));
+  }
+
+  /* Update the state of the lock has held in the file descriptor then
+  ** return the appropriate result code.
+  */
+  if( res == NO_ERROR ){
+    rc = SQLITE_OK;
+  }else{
+    OSTRACE(( "LOCK FAILED %d trying for %d but got %d\n", pFile->h,
+              locktype, newLocktype ));
+    rc = SQLITE_BUSY;
+  }
+  pFile->locktype = newLocktype;
+  OSTRACE(( "LOCK %d now %d\n", pFile->h, pFile->locktype ));
+  return rc;
+}
+
+/*
+** This routine checks if there is a RESERVED lock held on the specified
+** file by this or any other process. If such a lock is held, return
+** non-zero, otherwise zero.
+*/
+static int os2CheckReservedLock( sqlite3_file *id, int *pOut ){
+  int r = 0;
+  os2File *pFile = (os2File*)id;
+  assert( pFile!=0 );
+  if( pFile->locktype>=RESERVED_LOCK ){
+    r = 1;
+    OSTRACE(( "TEST WR-LOCK %d %d (local)\n", pFile->h, r ));
+  }else{
+    FILELOCK  LockArea,
+              UnlockArea;
+    APIRET rc = NO_ERROR;
+    memset(&LockArea, 0, sizeof(LockArea));
+    memset(&UnlockArea, 0, sizeof(UnlockArea));
+    LockArea.lOffset = RESERVED_BYTE;
+    LockArea.lRange = 1L;
+    UnlockArea.lOffset = 0L;
+    UnlockArea.lRange = 0L;
+    rc = DosSetFileLocks( pFile->h, &UnlockArea, &LockArea, LOCK_TIMEOUT, 0L );
+    OSTRACE(( "TEST WR-LOCK %d lock reserved byte rc=%d\n", pFile->h, rc ));
+    if( rc == NO_ERROR ){
+      APIRET rcu = NO_ERROR; /* return code for unlocking */
+      LockArea.lOffset = 0L;
+      LockArea.lRange = 0L;
+      UnlockArea.lOffset = RESERVED_BYTE;
+      UnlockArea.lRange = 1L;
+      rcu = DosSetFileLocks( pFile->h, &UnlockArea, &LockArea, LOCK_TIMEOUT, 0L );
+      OSTRACE(( "TEST WR-LOCK %d unlock reserved byte r=%d\n", pFile->h, rcu ));
+    }
+    r = !(rc == NO_ERROR);
+    OSTRACE(( "TEST WR-LOCK %d %d (remote)\n", pFile->h, r ));
+  }
+  *pOut = r;
+  return SQLITE_OK;
+}
+
+/*
+** Lower the locking level on file descriptor id to locktype.  locktype
+** must be either NO_LOCK or SHARED_LOCK.
+**
+** If the locking level of the file descriptor is already at or below
+** the requested locking level, this routine is a no-op.
+**
+** It is not possible for this routine to fail if the second argument
+** is NO_LOCK.  If the second argument is SHARED_LOCK then this routine
+** might return SQLITE_IOERR;
+*/
+static int os2Unlock( sqlite3_file *id, int locktype ){
+  int type;
+  os2File *pFile = (os2File*)id;
+  APIRET rc = SQLITE_OK;
+  APIRET res = NO_ERROR;
+  FILELOCK  LockArea,
+            UnlockArea;
+  memset(&LockArea, 0, sizeof(LockArea));
+  memset(&UnlockArea, 0, sizeof(UnlockArea));
+  assert( pFile!=0 );
+  assert( locktype<=SHARED_LOCK );
+  OSTRACE(( "UNLOCK %d to %d was %d\n", pFile->h, locktype, pFile->locktype ));
+  type = pFile->locktype;
+  if( type>=EXCLUSIVE_LOCK ){
+    LockArea.lOffset = 0L;
+    LockArea.lRange = 0L;
+    UnlockArea.lOffset = SHARED_FIRST;
+    UnlockArea.lRange = SHARED_SIZE;
+    res = DosSetFileLocks( pFile->h, &UnlockArea, &LockArea, LOCK_TIMEOUT, 0L );
+    OSTRACE(( "UNLOCK %d exclusive lock res=%d\n", pFile->h, res ));
+    if( locktype==SHARED_LOCK && getReadLock(pFile) != NO_ERROR ){
+      /* This should never happen.  We should always be able to
+      ** reacquire the read lock */
+      OSTRACE(( "UNLOCK %d to %d getReadLock() failed\n", pFile->h, locktype ));
+      rc = SQLITE_IOERR_UNLOCK;
+    }
+  }
+  if( type>=RESERVED_LOCK ){
+    LockArea.lOffset = 0L;
+    LockArea.lRange = 0L;
+    UnlockArea.lOffset = RESERVED_BYTE;
+    UnlockArea.lRange = 1L;
+    res = DosSetFileLocks( pFile->h, &UnlockArea, &LockArea, LOCK_TIMEOUT, 0L );
+    OSTRACE(( "UNLOCK %d reserved res=%d\n", pFile->h, res ));
+  }
+  if( locktype==NO_LOCK && type>=SHARED_LOCK ){
+    res = unlockReadLock(pFile);
+    OSTRACE(( "UNLOCK %d is %d want %d res=%d\n",
+              pFile->h, type, locktype, res ));
+  }
+  if( type>=PENDING_LOCK ){
+    LockArea.lOffset = 0L;
+    LockArea.lRange = 0L;
+    UnlockArea.lOffset = PENDING_BYTE;
+    UnlockArea.lRange = 1L;
+    res = DosSetFileLocks( pFile->h, &UnlockArea, &LockArea, LOCK_TIMEOUT, 0L );
+    OSTRACE(( "UNLOCK %d pending res=%d\n", pFile->h, res ));
+  }
+  pFile->locktype = locktype;
+  OSTRACE(( "UNLOCK %d now %d\n", pFile->h, pFile->locktype ));
+  return rc;
+}
+
+/*
+** Control and query of the open file handle.
+*/
+static int os2FileControl(sqlite3_file *id, int op, void *pArg){
+  switch( op ){
+    case SQLITE_FCNTL_LOCKSTATE: {
+      *(int*)pArg = ((os2File*)id)->locktype;
+      OSTRACE(( "FCNTL_LOCKSTATE %d lock=%d\n",
+                ((os2File*)id)->h, ((os2File*)id)->locktype ));
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_CHUNK_SIZE: {
+      ((os2File*)id)->szChunk = *(int*)pArg;
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_SIZE_HINT: {
+      sqlite3_int64 sz = *(sqlite3_int64*)pArg;
+      SimulateIOErrorBenign(1);
+      os2Truncate(id, sz);
+      SimulateIOErrorBenign(0);
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_SYNC_OMITTED: {
+      return SQLITE_OK;
+    }
+  }
+  return SQLITE_NOTFOUND;
+}
+
+/*
+** Return the sector size in bytes of the underlying block device for
+** the specified file. This is almost always 512 bytes, but may be
+** larger for some devices.
+**
+** SQLite code assumes this function cannot fail. It also assumes that
+** if two files are created in the same file-system directory (i.e.
+** a database and its journal file) that the sector size will be the
+** same for both.
+*/
+static int os2SectorSize(sqlite3_file *id){
+  UNUSED_PARAMETER(id);
+  return SQLITE_DEFAULT_SECTOR_SIZE;
+}
+
+/*
+** Return a vector of device characteristics.
+*/
+static int os2DeviceCharacteristics(sqlite3_file *id){
+  UNUSED_PARAMETER(id);
+  return SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN;
+}
+
+
+/*
+** Character set conversion objects used by conversion routines.
+*/
+static UconvObject ucUtf8 = NULL; /* convert between UTF-8 and UCS-2 */
+static UconvObject uclCp = NULL;  /* convert between local codepage and UCS-2 */
+
+/*
+** Helper function to initialize the conversion objects from and to UTF-8.
+*/
+static void initUconvObjects( void ){
+  if( UniCreateUconvObject( UTF_8, &ucUtf8 ) != ULS_SUCCESS )
+    ucUtf8 = NULL;
+  if ( UniCreateUconvObject( (UniChar *)L"@path=yes", &uclCp ) != ULS_SUCCESS )
+    uclCp = NULL;
+}
+
+/*
+** Helper function to free the conversion objects from and to UTF-8.
+*/
+static void freeUconvObjects( void ){
+  if ( ucUtf8 )
+    UniFreeUconvObject( ucUtf8 );
+  if ( uclCp )
+    UniFreeUconvObject( uclCp );
+  ucUtf8 = NULL;
+  uclCp = NULL;
+}
+
+/*
+** Helper function to convert UTF-8 filenames to local OS/2 codepage.
+** The two-step process: first convert the incoming UTF-8 string
+** into UCS-2 and then from UCS-2 to the current codepage.
+** The returned char pointer has to be freed.
+*/
+static char *convertUtf8PathToCp( const char *in ){
+  UniChar tempPath[CCHMAXPATH];
+  char *out = (char *)calloc( CCHMAXPATH, 1 );
+
+  if( !out )
+    return NULL;
+
+  if( !ucUtf8 || !uclCp )
+    initUconvObjects();
+
+  /* determine string for the conversion of UTF-8 which is CP1208 */
+  if( UniStrToUcs( ucUtf8, tempPath, (char *)in, CCHMAXPATH ) != ULS_SUCCESS )
+    return out; /* if conversion fails, return the empty string */
+
+  /* conversion for current codepage which can be used for paths */
+  UniStrFromUcs( uclCp, out, tempPath, CCHMAXPATH );
+
+  return out;
+}
+
+/*
+** Helper function to convert filenames from local codepage to UTF-8.
+** The two-step process: first convert the incoming codepage-specific
+** string into UCS-2 and then from UCS-2 to the codepage of UTF-8.
+** The returned char pointer has to be freed.
+**
+** This function is non-static to be able to use this in shell.c and
+** similar applications that take command line arguments.
+*/
+char *convertCpPathToUtf8( const char *in ){
+  UniChar tempPath[CCHMAXPATH];
+  char *out = (char *)calloc( CCHMAXPATH, 1 );
+
+  if( !out )
+    return NULL;
+
+  if( !ucUtf8 || !uclCp )
+    initUconvObjects();
+
+  /* conversion for current codepage which can be used for paths */
+  if( UniStrToUcs( uclCp, tempPath, (char *)in, CCHMAXPATH ) != ULS_SUCCESS )
+    return out; /* if conversion fails, return the empty string */
+
+  /* determine string for the conversion of UTF-8 which is CP1208 */
+  UniStrFromUcs( ucUtf8, out, tempPath, CCHMAXPATH );
+
+  return out;
+}
+
+
+#ifndef SQLITE_OMIT_WAL
+
+/*
+** Use main database file for interprocess locking. If un-defined
+** a separate file is created for this purpose. The file will be
+** used only to set file locks. There will be no data written to it.
+*/
+#define SQLITE_OS2_NO_WAL_LOCK_FILE     
+
+#if 0
+static void _ERR_TRACE( const char *fmt, ... ) {
+  va_list  ap;
+  va_start(ap, fmt);
+  vfprintf(stderr, fmt, ap);
+  fflush(stderr);
+}
+#define ERR_TRACE(rc, msg)        \
+        if( (rc) != SQLITE_OK ) _ERR_TRACE msg;
+#else
+#define ERR_TRACE(rc, msg)
+#endif
+
+/*
+** Helper functions to obtain and relinquish the global mutex. The
+** global mutex is used to protect os2ShmNodeList.
+**
+** Function os2ShmMutexHeld() is used to assert() that the global mutex 
+** is held when required. This function is only used as part of assert() 
+** statements. e.g.
+**
+**   os2ShmEnterMutex()
+**     assert( os2ShmMutexHeld() );
+**   os2ShmLeaveMutex()
+*/
+static void os2ShmEnterMutex(void){
+  sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
+}
+static void os2ShmLeaveMutex(void){
+  sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
+}
+#ifdef SQLITE_DEBUG
+static int os2ShmMutexHeld(void) {
+  return sqlite3_mutex_held(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
+}
+int GetCurrentProcessId(void) {
+  PPIB pib;
+  DosGetInfoBlocks(NULL, &pib);
+  return (int)pib->pib_ulpid;
+}
+#endif
+
+/*
+** Object used to represent a the shared memory area for a single log file.
+** When multiple threads all reference the same log-summary, each thread has
+** its own os2File object, but they all point to a single instance of this 
+** object.  In other words, each log-summary is opened only once per process.
+**
+** os2ShmMutexHeld() must be true when creating or destroying
+** this object or while reading or writing the following fields:
+**
+**      nRef
+**      pNext 
+**
+** The following fields are read-only after the object is created:
+** 
+**      szRegion
+**      hLockFile
+**      shmBaseName
+**
+** Either os2ShmNode.mutex must be held or os2ShmNode.nRef==0 and
+** os2ShmMutexHeld() is true when reading or writing any other field
+** in this structure.
+**
+*/
+struct os2ShmNode {
+  sqlite3_mutex *mutex;      /* Mutex to access this object */
+  os2ShmNode *pNext;         /* Next in list of all os2ShmNode objects */
+
+  int szRegion;              /* Size of shared-memory regions */
+
+  int nRegion;               /* Size of array apRegion */
+  void **apRegion;           /* Array of pointers to shared-memory regions */
+
+  int nRef;                  /* Number of os2ShmLink objects pointing to this */
+  os2ShmLink *pFirst;        /* First os2ShmLink object pointing to this */
+
+  HFILE hLockFile;           /* File used for inter-process memory locking */
+  char shmBaseName[1];       /* Name of the memory object !!! must last !!! */
+};
+
+
+/*
+** Structure used internally by this VFS to record the state of an
+** open shared memory connection.
+**
+** The following fields are initialized when this object is created and
+** are read-only thereafter:
+**
+**    os2Shm.pShmNode
+**    os2Shm.id
+**
+** All other fields are read/write.  The os2Shm.pShmNode->mutex must be held
+** while accessing any read/write fields.
+*/
+struct os2ShmLink {
+  os2ShmNode *pShmNode;      /* The underlying os2ShmNode object */
+  os2ShmLink *pNext;         /* Next os2Shm with the same os2ShmNode */
+  u32 sharedMask;            /* Mask of shared locks held */
+  u32 exclMask;              /* Mask of exclusive locks held */
+#ifdef SQLITE_DEBUG
+  u8 id;                     /* Id of this connection with its os2ShmNode */
+#endif
+};
+
+
+/*
+** A global list of all os2ShmNode objects.
+**
+** The os2ShmMutexHeld() must be true while reading or writing this list.
+*/
+static os2ShmNode *os2ShmNodeList = NULL;
+
+/*
+** Constants used for locking
+*/
+#ifdef  SQLITE_OS2_NO_WAL_LOCK_FILE
+#define OS2_SHM_BASE   (PENDING_BYTE + 0x10000)         /* first lock byte */
+#else
+#define OS2_SHM_BASE   ((22+SQLITE_SHM_NLOCK)*4)        /* first lock byte */
+#endif
+
+#define OS2_SHM_DMS    (OS2_SHM_BASE+SQLITE_SHM_NLOCK)  /* deadman switch */
+
+/*
+** Apply advisory locks for all n bytes beginning at ofst.
+*/
+#define _SHM_UNLCK  1   /* no lock */
+#define _SHM_RDLCK  2   /* shared lock, no wait */
+#define _SHM_WRLCK  3   /* exlusive lock, no wait */
+#define _SHM_WRLCK_WAIT 4 /* exclusive lock, wait */
+static int os2ShmSystemLock(
+  os2ShmNode *pNode,    /* Apply locks to this open shared-memory segment */
+  int lockType,         /* _SHM_UNLCK, _SHM_RDLCK, _SHM_WRLCK or _SHM_WRLCK_WAIT */
+  int ofst,             /* Offset to first byte to be locked/unlocked */
+  int nByte             /* Number of bytes to lock or unlock */
+){
+  APIRET rc;
+  FILELOCK area;
+  ULONG mode, timeout;
+
+  /* Access to the os2ShmNode object is serialized by the caller */
+  assert( sqlite3_mutex_held(pNode->mutex) || pNode->nRef==0 );
+
+  mode = 1;     /* shared lock */
+  timeout = 0;  /* no wait */
+  area.lOffset = ofst;
+  area.lRange = nByte;
+
+  switch( lockType ) {
+    case _SHM_WRLCK_WAIT:
+      timeout = (ULONG)-1;      /* wait forever */
+    case _SHM_WRLCK:
+      mode = 0;                 /* exclusive lock */
+    case _SHM_RDLCK:
+      rc = DosSetFileLocks(pNode->hLockFile, 
+                           NULL, &area, timeout, mode);
+      break;
+    /* case _SHM_UNLCK: */
+    default:
+      rc = DosSetFileLocks(pNode->hLockFile, 
+                           &area, NULL, 0, 0);
+      break;
+  }
+                          
+  OSTRACE(("SHM-LOCK %d %s %s 0x%08lx\n", 
+           pNode->hLockFile,
+           rc==SQLITE_OK ? "ok" : "failed",
+           lockType==_SHM_UNLCK ? "Unlock" : "Lock",
+           rc));
+
+  ERR_TRACE(rc, ("os2ShmSystemLock: %d %s\n", rc, pNode->shmBaseName))
+
+  return ( rc == 0 ) ?  SQLITE_OK : SQLITE_BUSY;
+}
+
+/*
+** Find an os2ShmNode in global list or allocate a new one, if not found.
+**
+** This is not a VFS shared-memory method; it is a utility function called
+** by VFS shared-memory methods.
+*/
+static int os2OpenSharedMemory( os2File *fd, int szRegion ) {
+  os2ShmLink *pLink;
+  os2ShmNode *pNode;
+  int cbShmName, rc = SQLITE_OK;
+  char shmName[CCHMAXPATH + 30];
+#ifndef SQLITE_OS2_NO_WAL_LOCK_FILE
+  ULONG action;
+#endif
+  
+  /* We need some additional space at the end to append the region number */
+  cbShmName = sprintf(shmName, "\\SHAREMEM\\%s", fd->zFullPathCp );
+  if( cbShmName >= CCHMAXPATH-8 )
+    return SQLITE_IOERR_SHMOPEN; 
+
+  /* Replace colon in file name to form a valid shared memory name */
+  shmName[10+1] = '!';
+
+  /* Allocate link object (we free it later in case of failure) */
+  pLink = sqlite3_malloc( sizeof(*pLink) );
+  if( !pLink )
+    return SQLITE_NOMEM;
+
+  /* Access node list */
+  os2ShmEnterMutex();
+
+  /* Find node by it's shared memory base name */
+  for( pNode = os2ShmNodeList; 
+       pNode && stricmp(shmName, pNode->shmBaseName) != 0; 
+       pNode = pNode->pNext )   ;
+
+  /* Not found: allocate a new node */
+  if( !pNode ) {
+    pNode = sqlite3_malloc( sizeof(*pNode) + cbShmName );
+    if( pNode ) {
+      memset(pNode, 0, sizeof(*pNode) );
+      pNode->szRegion = szRegion;
+      pNode->hLockFile = (HFILE)-1;      
+      strcpy(pNode->shmBaseName, shmName);
+
+#ifdef SQLITE_OS2_NO_WAL_LOCK_FILE
+      if( DosDupHandle(fd->h, &pNode->hLockFile) != 0 ) {
+#else
+      sprintf(shmName, "%s-lck", fd->zFullPathCp);
+      if( DosOpen((PSZ)shmName, &pNode->hLockFile, &action, 0, FILE_NORMAL, 
+                  OPEN_ACTION_OPEN_IF_EXISTS | OPEN_ACTION_CREATE_IF_NEW,
+                  OPEN_ACCESS_READWRITE | OPEN_SHARE_DENYNONE | 
+                  OPEN_FLAGS_NOINHERIT | OPEN_FLAGS_FAIL_ON_ERROR,
+                  NULL) != 0 ) {
+#endif
+        sqlite3_free(pNode);  
+        rc = SQLITE_IOERR;
+      } else {
+        pNode->mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
+        if( !pNode->mutex ) {
+          sqlite3_free(pNode);  
+          rc = SQLITE_NOMEM;
+        }
+      }   
+    } else {
+      rc = SQLITE_NOMEM;
+    }
+    
+    if( rc == SQLITE_OK ) {
+      pNode->pNext = os2ShmNodeList;
+      os2ShmNodeList = pNode;
+    } else {
+      pNode = NULL;
+    }
+  } else if( pNode->szRegion != szRegion ) {
+    rc = SQLITE_IOERR_SHMSIZE;
+    pNode = NULL;
+  }
+
+  if( pNode ) {
+    sqlite3_mutex_enter(pNode->mutex);
+
+    memset(pLink, 0, sizeof(*pLink));
+
+    pLink->pShmNode = pNode;
+    pLink->pNext = pNode->pFirst;
+    pNode->pFirst = pLink;
+    pNode->nRef++;
+
+    fd->pShmLink = pLink;
+
+    sqlite3_mutex_leave(pNode->mutex);
+    
+  } else {
+    /* Error occured. Free our link object. */
+    sqlite3_free(pLink);  
+  }
+
+  os2ShmLeaveMutex();
+
+  ERR_TRACE(rc, ("os2OpenSharedMemory: %d  %s\n", rc, fd->zFullPathCp))  
+  
+  return rc;
+}
+
+/*
+** Purge the os2ShmNodeList list of all entries with nRef==0.
+**
+** This is not a VFS shared-memory method; it is a utility function called
+** by VFS shared-memory methods.
+*/
+static void os2PurgeShmNodes( int deleteFlag ) {
+  os2ShmNode *pNode;
+  os2ShmNode **ppNode;
+
+  os2ShmEnterMutex();
+  
+  ppNode = &os2ShmNodeList;
+
+  while( *ppNode ) {
+    pNode = *ppNode;
+
+    if( pNode->nRef == 0 ) {
+      *ppNode = pNode->pNext;   
+     
+      if( pNode->apRegion ) {
+        /* Prevent other processes from resizing the shared memory */
+        os2ShmSystemLock(pNode, _SHM_WRLCK_WAIT, OS2_SHM_DMS, 1);
+
+        while( pNode->nRegion-- ) {
+#ifdef SQLITE_DEBUG
+          int rc = 
+#endif          
+          DosFreeMem(pNode->apRegion[pNode->nRegion]);
+
+          OSTRACE(("SHM-PURGE pid-%d unmap region=%d %s\n",
+                  (int)GetCurrentProcessId(), pNode->nRegion,
+                  rc == 0 ? "ok" : "failed"));
+        }
+
+        /* Allow other processes to resize the shared memory */
+        os2ShmSystemLock(pNode, _SHM_UNLCK, OS2_SHM_DMS, 1);
+
+        sqlite3_free(pNode->apRegion);
+      }  
+
+      DosClose(pNode->hLockFile);
+      
+#ifndef SQLITE_OS2_NO_WAL_LOCK_FILE
+      if( deleteFlag ) {
+         char fileName[CCHMAXPATH];
+         /* Skip "\\SHAREMEM\\" */
+         sprintf(fileName, "%s-lck", pNode->shmBaseName + 10);
+         /* restore colon */
+         fileName[1] = ':';
+         
+         DosForceDelete(fileName); 
+      }
+#endif
+
+      sqlite3_mutex_free(pNode->mutex);
+
+      sqlite3_free(pNode);
+      
+    } else {
+      ppNode = &pNode->pNext;
+    }
+  } 
+
+  os2ShmLeaveMutex();
+}
+
+/*
+** This function is called to obtain a pointer to region iRegion of the
+** shared-memory associated with the database file id. Shared-memory regions
+** are numbered starting from zero. Each shared-memory region is szRegion
+** bytes in size.
+**
+** If an error occurs, an error code is returned and *pp is set to NULL.
+**
+** Otherwise, if the bExtend parameter is 0 and the requested shared-memory
+** region has not been allocated (by any client, including one running in a
+** separate process), then *pp is set to NULL and SQLITE_OK returned. If
+** bExtend is non-zero and the requested shared-memory region has not yet
+** been allocated, it is allocated by this function.
+**
+** If the shared-memory region has already been allocated or is allocated by
+** this call as described above, then it is mapped into this processes
+** address space (if it is not already), *pp is set to point to the mapped
+** memory and SQLITE_OK returned.
+*/
+static int os2ShmMap(
+  sqlite3_file *id,               /* Handle open on database file */
+  int iRegion,                    /* Region to retrieve */
+  int szRegion,                   /* Size of regions */
+  int bExtend,                    /* True to extend block if necessary */
+  void volatile **pp              /* OUT: Mapped memory */
+){
+  PVOID pvTemp;
+  void **apRegion;
+  os2ShmNode *pNode;
+  int n, rc = SQLITE_OK;
+  char shmName[CCHMAXPATH];
+  os2File *pFile = (os2File*)id;
+  
+  *pp = NULL;
+
+  if( !pFile->pShmLink )
+    rc = os2OpenSharedMemory( pFile, szRegion );
+  
+  if( rc == SQLITE_OK ) {
+    pNode = pFile->pShmLink->pShmNode ;
+    
+    sqlite3_mutex_enter(pNode->mutex);
+    
+    assert( szRegion==pNode->szRegion );
+
+    /* Unmapped region ? */
+    if( iRegion >= pNode->nRegion ) {
+      /* Prevent other processes from resizing the shared memory */
+      os2ShmSystemLock(pNode, _SHM_WRLCK_WAIT, OS2_SHM_DMS, 1);
+
+      apRegion = sqlite3_realloc(
+        pNode->apRegion, (iRegion + 1) * sizeof(apRegion[0]));
+
+      if( apRegion ) {
+        pNode->apRegion = apRegion;
+
+        while( pNode->nRegion <= iRegion ) {
+          sprintf(shmName, "%s-%u", 
+                  pNode->shmBaseName, pNode->nRegion);
+
+          if( DosGetNamedSharedMem(&pvTemp, (PSZ)shmName, 
+                PAG_READ | PAG_WRITE) != NO_ERROR ) {
+            if( !bExtend )
+              break;
+
+            if( DosAllocSharedMem(&pvTemp, (PSZ)shmName, szRegion,
+                  PAG_READ | PAG_WRITE | PAG_COMMIT | OBJ_ANY) != NO_ERROR && 
+                DosAllocSharedMem(&pvTemp, (PSZ)shmName, szRegion,
+                  PAG_READ | PAG_WRITE | PAG_COMMIT) != NO_ERROR ) { 
+              rc = SQLITE_NOMEM;
+              break;
+            }
+          }
+
+          apRegion[pNode->nRegion++] = pvTemp;
+        }
+
+        /* zero out remaining entries */ 
+        for( n = pNode->nRegion; n <= iRegion; n++ )
+          pNode->apRegion[n] = NULL;
+
+        /* Return this region (maybe zero) */
+        *pp = pNode->apRegion[iRegion];
+      } else {
+        rc = SQLITE_NOMEM;
+      }
+
+      /* Allow other processes to resize the shared memory */
+      os2ShmSystemLock(pNode, _SHM_UNLCK, OS2_SHM_DMS, 1);
+      
+    } else {
+      /* Region has been mapped previously */
+      *pp = pNode->apRegion[iRegion];
+    }
+
+    sqlite3_mutex_leave(pNode->mutex);
+  } 
+
+  ERR_TRACE(rc, ("os2ShmMap: %s iRgn = %d, szRgn = %d, bExt = %d : %d\n", 
+                 pFile->zFullPathCp, iRegion, szRegion, bExtend, rc))
+          
+  return rc;
+}
+
+/*
+** Close a connection to shared-memory.  Delete the underlying
+** storage if deleteFlag is true.
+**
+** If there is no shared memory associated with the connection then this
+** routine is a harmless no-op.
+*/
+static int os2ShmUnmap(
+  sqlite3_file *id,               /* The underlying database file */
+  int deleteFlag                  /* Delete shared-memory if true */
+){
+  os2File *pFile = (os2File*)id;
+  os2ShmLink *pLink = pFile->pShmLink;
+  
+  if( pLink ) {
+    int nRef = -1;
+    os2ShmLink **ppLink;
+    os2ShmNode *pNode = pLink->pShmNode;
+
+    sqlite3_mutex_enter(pNode->mutex);
+    
+    for( ppLink = &pNode->pFirst;
+         *ppLink && *ppLink != pLink;
+         ppLink = &(*ppLink)->pNext )   ;
+         
+    assert(*ppLink);
+
+    if( *ppLink ) {
+      *ppLink = pLink->pNext;
+      nRef = --pNode->nRef;
+    } else {
+      ERR_TRACE(1, ("os2ShmUnmap: link not found ! %s\n", 
+                    pNode->shmBaseName))
+    }
+    
+    pFile->pShmLink = NULL;
+    sqlite3_free(pLink);
+
+    sqlite3_mutex_leave(pNode->mutex);
+    
+    if( nRef == 0 )
+      os2PurgeShmNodes( deleteFlag );
+  }
+
+  return SQLITE_OK;
+}
+
+/*
+** Change the lock state for a shared-memory segment.
+**
+** Note that the relationship between SHAREd and EXCLUSIVE locks is a little
+** different here than in posix.  In xShmLock(), one can go from unlocked
+** to shared and back or from unlocked to exclusive and back.  But one may
+** not go from shared to exclusive or from exclusive to shared.
+*/
+static int os2ShmLock(
+  sqlite3_file *id,          /* Database file holding the shared memory */
+  int ofst,                  /* First lock to acquire or release */
+  int n,                     /* Number of locks to acquire or release */
+  int flags                  /* What to do with the lock */
+){
+  u32 mask;                             /* Mask of locks to take or release */
+  int rc = SQLITE_OK;                   /* Result code */
+  os2File *pFile = (os2File*)id;
+  os2ShmLink *p = pFile->pShmLink;      /* The shared memory being locked */
+  os2ShmLink *pX;                       /* For looping over all siblings */
+  os2ShmNode *pShmNode = p->pShmNode;   /* Our node */
+  
+  assert( ofst>=0 && ofst+n<=SQLITE_SHM_NLOCK );
+  assert( n>=1 );
+  assert( flags==(SQLITE_SHM_LOCK | SQLITE_SHM_SHARED)
+       || flags==(SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE)
+       || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED)
+       || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE) );
+  assert( n==1 || (flags & SQLITE_SHM_EXCLUSIVE)!=0 );
+
+  mask = (u32)((1U<<(ofst+n)) - (1U<<ofst));
+  assert( n>1 || mask==(1<<ofst) );
+
+
+  sqlite3_mutex_enter(pShmNode->mutex);
+
+  if( flags & SQLITE_SHM_UNLOCK ){
+    u32 allMask = 0; /* Mask of locks held by siblings */
+
+    /* See if any siblings hold this same lock */
+    for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
+      if( pX==p ) continue;
+      assert( (pX->exclMask & (p->exclMask|p->sharedMask))==0 );
+      allMask |= pX->sharedMask;
+    }
+
+    /* Unlock the system-level locks */
+    if( (mask & allMask)==0 ){
+      rc = os2ShmSystemLock(pShmNode, _SHM_UNLCK, ofst+OS2_SHM_BASE, n);
+    }else{
+      rc = SQLITE_OK;
+    }
+
+    /* Undo the local locks */
+    if( rc==SQLITE_OK ){
+      p->exclMask &= ~mask;
+      p->sharedMask &= ~mask;
+    } 
+  }else if( flags & SQLITE_SHM_SHARED ){
+    u32 allShared = 0;  /* Union of locks held by connections other than "p" */
+
+    /* Find out which shared locks are already held by sibling connections.
+    ** If any sibling already holds an exclusive lock, go ahead and return
+    ** SQLITE_BUSY.
+    */
+    for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
+      if( (pX->exclMask & mask)!=0 ){
+        rc = SQLITE_BUSY;
+        break;
+      }
+      allShared |= pX->sharedMask;
+    }
+
+    /* Get shared locks at the system level, if necessary */
+    if( rc==SQLITE_OK ){
+      if( (allShared & mask)==0 ){
+        rc = os2ShmSystemLock(pShmNode, _SHM_RDLCK, ofst+OS2_SHM_BASE, n);
+      }else{
+        rc = SQLITE_OK;
+      }
+    }
+
+    /* Get the local shared locks */
+    if( rc==SQLITE_OK ){
+      p->sharedMask |= mask;
+    }
+  }else{
+    /* Make sure no sibling connections hold locks that will block this
+    ** lock.  If any do, return SQLITE_BUSY right away.
+    */
+    for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
+      if( (pX->exclMask & mask)!=0 || (pX->sharedMask & mask)!=0 ){
+        rc = SQLITE_BUSY;
+        break;
+      }
+    }
+  
+    /* Get the exclusive locks at the system level.  Then if successful
+    ** also mark the local connection as being locked.
+    */
+    if( rc==SQLITE_OK ){
+      rc = os2ShmSystemLock(pShmNode, _SHM_WRLCK, ofst+OS2_SHM_BASE, n);
+      if( rc==SQLITE_OK ){
+        assert( (p->sharedMask & mask)==0 );
+        p->exclMask |= mask;
+      }
+    }
+  }
+
+  sqlite3_mutex_leave(pShmNode->mutex);
+  
+  OSTRACE(("SHM-LOCK shmid-%d, pid-%d got %03x,%03x %s\n",
+           p->id, (int)GetCurrentProcessId(), p->sharedMask, p->exclMask,
+           rc ? "failed" : "ok"));
+
+  ERR_TRACE(rc, ("os2ShmLock: ofst = %d, n = %d, flags = 0x%x -> %d \n", 
+                 ofst, n, flags, rc))
+                  
+  return rc; 
+}
+
+/*
+** Implement a memory barrier or memory fence on shared memory.
+**
+** All loads and stores begun before the barrier must complete before
+** any load or store begun after the barrier.
+*/
+static void os2ShmBarrier(
+  sqlite3_file *id                /* Database file holding the shared memory */
+){
+  UNUSED_PARAMETER(id);
+  os2ShmEnterMutex();
+  os2ShmLeaveMutex();
+}
+
+#else
+# define os2ShmMap     0
+# define os2ShmLock    0
+# define os2ShmBarrier 0
+# define os2ShmUnmap   0
+#endif /* #ifndef SQLITE_OMIT_WAL */
+
+
+/*
+** This vector defines all the methods that can operate on an
+** sqlite3_file for os2.
+*/
+static const sqlite3_io_methods os2IoMethod = {
+  2,                              /* iVersion */
+  os2Close,                       /* xClose */
+  os2Read,                        /* xRead */
+  os2Write,                       /* xWrite */
+  os2Truncate,                    /* xTruncate */
+  os2Sync,                        /* xSync */
+  os2FileSize,                    /* xFileSize */
+  os2Lock,                        /* xLock */
+  os2Unlock,                      /* xUnlock */
+  os2CheckReservedLock,           /* xCheckReservedLock */
+  os2FileControl,                 /* xFileControl */
+  os2SectorSize,                  /* xSectorSize */
+  os2DeviceCharacteristics,       /* xDeviceCharacteristics */
+  os2ShmMap,                      /* xShmMap */
+  os2ShmLock,                     /* xShmLock */
+  os2ShmBarrier,                  /* xShmBarrier */
+  os2ShmUnmap                     /* xShmUnmap */
+};
+
+
+/***************************************************************************
+** Here ends the I/O methods that form the sqlite3_io_methods object.
+**
+** The next block of code implements the VFS methods.
+****************************************************************************/
+
+/*
+** Create a temporary file name in zBuf.  zBuf must be big enough to
+** hold at pVfs->mxPathname characters.
+*/
+static int getTempname(int nBuf, char *zBuf ){
+  static const char zChars[] =
+    "abcdefghijklmnopqrstuvwxyz"
+    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+    "0123456789";
+  int i, j;
+  PSZ zTempPathCp;      
+  char zTempPath[CCHMAXPATH];
+  ULONG ulDriveNum, ulDriveMap;
+  
+  /* It's odd to simulate an io-error here, but really this is just
+  ** using the io-error infrastructure to test that SQLite handles this
+  ** function failing. 
+  */
+  SimulateIOError( return SQLITE_IOERR );
+
+  if( sqlite3_temp_directory ) {
+    sqlite3_snprintf(CCHMAXPATH-30, zTempPath, "%s", sqlite3_temp_directory);
+  } else if( DosScanEnv( (PSZ)"TEMP",   &zTempPathCp ) == NO_ERROR ||
+             DosScanEnv( (PSZ)"TMP",    &zTempPathCp ) == NO_ERROR ||
+             DosScanEnv( (PSZ)"TMPDIR", &zTempPathCp ) == NO_ERROR ) {
+    char *zTempPathUTF = convertCpPathToUtf8( (char *)zTempPathCp );
+    sqlite3_snprintf(CCHMAXPATH-30, zTempPath, "%s", zTempPathUTF);
+    free( zTempPathUTF );
+  } else if( DosQueryCurrentDisk( &ulDriveNum, &ulDriveMap ) == NO_ERROR ) {
+    zTempPath[0] = (char)('A' + ulDriveNum - 1);
+    zTempPath[1] = ':'; 
+    zTempPath[2] = '\0'; 
+  } else {
+    zTempPath[0] = '\0'; 
+  }
+  
+  /* Strip off a trailing slashes or backslashes, otherwise we would get *
+   * multiple (back)slashes which causes DosOpen() to fail.              *
+   * Trailing spaces are not allowed, either.                            */
+  j = sqlite3Strlen30(zTempPath);
+  while( j > 0 && ( zTempPath[j-1] == '\\' || zTempPath[j-1] == '/' || 
+                    zTempPath[j-1] == ' ' ) ){
+    j--;
+  }
+  zTempPath[j] = '\0';
+  
+  /* We use 20 bytes to randomize the name */
+  sqlite3_snprintf(nBuf-22, zBuf,
+                   "%s\\"SQLITE_TEMP_FILE_PREFIX, zTempPath);
+  j = sqlite3Strlen30(zBuf);
+  sqlite3_randomness( 20, &zBuf[j] );
+  for( i = 0; i < 20; i++, j++ ){
+    zBuf[j] = zChars[ ((unsigned char)zBuf[j])%(sizeof(zChars)-1) ];
+  }
+  zBuf[j] = 0;
+
+  OSTRACE(( "TEMP FILENAME: %s\n", zBuf ));
+  return SQLITE_OK;
+}
+
+
+/*
+** Turn a relative pathname into a full pathname.  Write the full
+** pathname into zFull[].  zFull[] will be at least pVfs->mxPathname
+** bytes in size.
+*/
+static int os2FullPathname(
+  sqlite3_vfs *pVfs,          /* Pointer to vfs object */
+  const char *zRelative,      /* Possibly relative input path */
+  int nFull,                  /* Size of output buffer in bytes */
+  char *zFull                 /* Output buffer */
+){
+  char *zRelativeCp = convertUtf8PathToCp( zRelative );
+  char zFullCp[CCHMAXPATH] = "\0";
+  char *zFullUTF;
+  APIRET rc = DosQueryPathInfo( (PSZ)zRelativeCp, FIL_QUERYFULLNAME, 
+                                zFullCp, CCHMAXPATH );
+  free( zRelativeCp );
+  zFullUTF = convertCpPathToUtf8( zFullCp );
+  sqlite3_snprintf( nFull, zFull, zFullUTF );
+  free( zFullUTF );
+  return rc == NO_ERROR ? SQLITE_OK : SQLITE_IOERR;
+}
+
+
+/*
+** Open a file.
+*/
+static int os2Open(
+  sqlite3_vfs *pVfs,            /* Not used */
+  const char *zName,            /* Name of the file (UTF-8) */
+  sqlite3_file *id,             /* Write the SQLite file handle here */
+  int flags,                    /* Open mode flags */
+  int *pOutFlags                /* Status return flags */
+){
+  HFILE h;
+  ULONG ulOpenFlags = 0;
+  ULONG ulOpenMode = 0;
+  ULONG ulAction = 0;
+  ULONG rc;
+  os2File *pFile = (os2File*)id;
+  const char *zUtf8Name = zName;
+  char *zNameCp;
+  char  zTmpname[CCHMAXPATH];
+
+  int isExclusive  = (flags & SQLITE_OPEN_EXCLUSIVE);
+  int isCreate     = (flags & SQLITE_OPEN_CREATE);
+  int isReadWrite  = (flags & SQLITE_OPEN_READWRITE);
+#ifndef NDEBUG
+  int isDelete     = (flags & SQLITE_OPEN_DELETEONCLOSE);
+  int isReadonly   = (flags & SQLITE_OPEN_READONLY);
+  int eType        = (flags & 0xFFFFFF00);
+  int isOpenJournal = (isCreate && (
+        eType==SQLITE_OPEN_MASTER_JOURNAL 
+     || eType==SQLITE_OPEN_MAIN_JOURNAL 
+     || eType==SQLITE_OPEN_WAL
+  ));
+#endif
+
+  UNUSED_PARAMETER(pVfs);
+  assert( id!=0 );
+
+  /* Check the following statements are true: 
+  **
+  **   (a) Exactly one of the READWRITE and READONLY flags must be set, and 
+  **   (b) if CREATE is set, then READWRITE must also be set, and
+  **   (c) if EXCLUSIVE is set, then CREATE must also be set.
+  **   (d) if DELETEONCLOSE is set, then CREATE must also be set.
+  */
+  assert((isReadonly==0 || isReadWrite==0) && (isReadWrite || isReadonly));
+  assert(isCreate==0 || isReadWrite);
+  assert(isExclusive==0 || isCreate);
+  assert(isDelete==0 || isCreate);
+
+  /* The main DB, main journal, WAL file and master journal are never 
+  ** automatically deleted. Nor are they ever temporary files.  */
+  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MAIN_DB );
+  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MAIN_JOURNAL );
+  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MASTER_JOURNAL );
+  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_WAL );
+
+  /* Assert that the upper layer has set one of the "file-type" flags. */
+  assert( eType==SQLITE_OPEN_MAIN_DB      || eType==SQLITE_OPEN_TEMP_DB 
+       || eType==SQLITE_OPEN_MAIN_JOURNAL || eType==SQLITE_OPEN_TEMP_JOURNAL 
+       || eType==SQLITE_OPEN_SUBJOURNAL   || eType==SQLITE_OPEN_MASTER_JOURNAL 
+       || eType==SQLITE_OPEN_TRANSIENT_DB || eType==SQLITE_OPEN_WAL
+  );
+
+  memset( pFile, 0, sizeof(*pFile) );
+  pFile->h = (HFILE)-1;
+
+  /* If the second argument to this function is NULL, generate a 
+  ** temporary file name to use 
+  */
+  if( !zUtf8Name ){
+    assert(isDelete && !isOpenJournal);
+    rc = getTempname(CCHMAXPATH, zTmpname);
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+    zUtf8Name = zTmpname;
+  }
+
+  if( isReadWrite ){
+    ulOpenMode |= OPEN_ACCESS_READWRITE;
+  }else{
+    ulOpenMode |= OPEN_ACCESS_READONLY;
+  }
+
+  /* Open in random access mode for possibly better speed.  Allow full
+  ** sharing because file locks will provide exclusive access when needed.
+  ** The handle should not be inherited by child processes and we don't 
+  ** want popups from the critical error handler.
+  */
+  ulOpenMode |= OPEN_FLAGS_RANDOM | OPEN_SHARE_DENYNONE | 
+                OPEN_FLAGS_NOINHERIT | OPEN_FLAGS_FAIL_ON_ERROR;
+
+  /* SQLITE_OPEN_EXCLUSIVE is used to make sure that a new file is 
+  ** created. SQLite doesn't use it to indicate "exclusive access" 
+  ** as it is usually understood.
+  */
+  if( isExclusive ){
+    /* Creates a new file, only if it does not already exist. */
+    /* If the file exists, it fails. */
+    ulOpenFlags |= OPEN_ACTION_CREATE_IF_NEW | OPEN_ACTION_FAIL_IF_EXISTS;
+  }else if( isCreate ){
+    /* Open existing file, or create if it doesn't exist */
+    ulOpenFlags |= OPEN_ACTION_CREATE_IF_NEW | OPEN_ACTION_OPEN_IF_EXISTS;
+  }else{
+    /* Opens a file, only if it exists. */
+    ulOpenFlags |= OPEN_ACTION_FAIL_IF_NEW | OPEN_ACTION_OPEN_IF_EXISTS;
+  }
+
+  zNameCp = convertUtf8PathToCp( zUtf8Name );
+  rc = DosOpen( (PSZ)zNameCp,
+                &h,
+                &ulAction,
+                0L,
+                FILE_NORMAL,
+                ulOpenFlags,
+                ulOpenMode,
+                (PEAOP2)NULL );
+  free( zNameCp );
+
+  if( rc != NO_ERROR ){
+    OSTRACE(( "OPEN Invalid handle rc=%d: zName=%s, ulAction=%#lx, ulFlags=%#lx, ulMode=%#lx\n",
+              rc, zUtf8Name, ulAction, ulOpenFlags, ulOpenMode ));
+
+    if( isReadWrite ){
+      return os2Open( pVfs, zName, id,
+                      ((flags|SQLITE_OPEN_READONLY)&~(SQLITE_OPEN_CREATE|SQLITE_OPEN_READWRITE)),
+                      pOutFlags );
+    }else{
+      return SQLITE_CANTOPEN;
+    }
+  }
+
+  if( pOutFlags ){
+    *pOutFlags = isReadWrite ? SQLITE_OPEN_READWRITE : SQLITE_OPEN_READONLY;
+  }
+
+  os2FullPathname( pVfs, zUtf8Name, sizeof( zTmpname ), zTmpname );
+  pFile->zFullPathCp = convertUtf8PathToCp( zTmpname );
+  pFile->pMethod = &os2IoMethod;
+  pFile->flags = flags;
+  pFile->h = h;
+
+  OpenCounter(+1);
+  OSTRACE(( "OPEN %d pOutFlags=%d\n", pFile->h, pOutFlags ));
+  return SQLITE_OK;
+}
+
+/*
+** Delete the named file.
+*/
+static int os2Delete(
+  sqlite3_vfs *pVfs,                     /* Not used on os2 */
+  const char *zFilename,                 /* Name of file to delete */
+  int syncDir                            /* Not used on os2 */
+){
+  APIRET rc;
+  char *zFilenameCp;
+  SimulateIOError( return SQLITE_IOERR_DELETE );
+  zFilenameCp = convertUtf8PathToCp( zFilename );
+  rc = DosDelete( (PSZ)zFilenameCp );
+  free( zFilenameCp );
+  OSTRACE(( "DELETE \"%s\"\n", zFilename ));
+  return (rc == NO_ERROR ||
+          rc == ERROR_FILE_NOT_FOUND ||
+          rc == ERROR_PATH_NOT_FOUND ) ? SQLITE_OK : SQLITE_IOERR_DELETE;
+}
+
+/*
+** Check the existance and status of a file.
+*/
+static int os2Access(
+  sqlite3_vfs *pVfs,        /* Not used on os2 */
+  const char *zFilename,    /* Name of file to check */
+  int flags,                /* Type of test to make on this file */
+  int *pOut                 /* Write results here */
+){
+  APIRET rc;
+  FILESTATUS3 fsts3ConfigInfo;
+  char *zFilenameCp;
+
+  UNUSED_PARAMETER(pVfs);
+  SimulateIOError( return SQLITE_IOERR_ACCESS; );
+  
+  zFilenameCp = convertUtf8PathToCp( zFilename );
+  rc = DosQueryPathInfo( (PSZ)zFilenameCp, FIL_STANDARD,
+                         &fsts3ConfigInfo, sizeof(FILESTATUS3) );
+  free( zFilenameCp );
+  OSTRACE(( "ACCESS fsts3ConfigInfo.attrFile=%d flags=%d rc=%d\n",
+            fsts3ConfigInfo.attrFile, flags, rc ));
+
+  switch( flags ){
+    case SQLITE_ACCESS_EXISTS:
+      /* For an SQLITE_ACCESS_EXISTS query, treat a zero-length file
+      ** as if it does not exist.
+      */
+      if( fsts3ConfigInfo.cbFile == 0 ) 
+        rc = ERROR_FILE_NOT_FOUND;
+      break;
+    case SQLITE_ACCESS_READ:
+      break;
+    case SQLITE_ACCESS_READWRITE:
+      if( fsts3ConfigInfo.attrFile & FILE_READONLY )
+        rc = ERROR_ACCESS_DENIED;
+      break;
+    default:
+      rc = ERROR_FILE_NOT_FOUND;
+      assert( !"Invalid flags argument" );
+  }
+
+  *pOut = (rc == NO_ERROR);
+  OSTRACE(( "ACCESS %s flags %d: rc=%d\n", zFilename, flags, *pOut ));
+
+  return SQLITE_OK;
+}
+
+
+#ifndef SQLITE_OMIT_LOAD_EXTENSION
+/*
+** Interfaces for opening a shared library, finding entry points
+** within the shared library, and closing the shared library.
+*/
+/*
+** Interfaces for opening a shared library, finding entry points
+** within the shared library, and closing the shared library.
+*/
+static void *os2DlOpen(sqlite3_vfs *pVfs, const char *zFilename){
+  HMODULE hmod;
+  APIRET rc;
+  char *zFilenameCp = convertUtf8PathToCp(zFilename);
+  rc = DosLoadModule(NULL, 0, (PSZ)zFilenameCp, &hmod);
+  free(zFilenameCp);
+  return rc != NO_ERROR ? 0 : (void*)hmod;
+}
+/*
+** A no-op since the error code is returned on the DosLoadModule call.
+** os2Dlopen returns zero if DosLoadModule is not successful.
+*/
+static void os2DlError(sqlite3_vfs *pVfs, int nBuf, char *zBufOut){
+/* no-op */
+}
+static void (*os2DlSym(sqlite3_vfs *pVfs, void *pHandle, const char *zSymbol))(void){
+  PFN pfn;
+  APIRET rc;
+  rc = DosQueryProcAddr((HMODULE)pHandle, 0L, (PSZ)zSymbol, &pfn);
+  if( rc != NO_ERROR ){
+    /* if the symbol itself was not found, search again for the same
+     * symbol with an extra underscore, that might be needed depending
+     * on the calling convention */
+    char _zSymbol[256] = "_";
+    strncat(_zSymbol, zSymbol, 254);
+    rc = DosQueryProcAddr((HMODULE)pHandle, 0L, (PSZ)_zSymbol, &pfn);
+  }
+  return rc != NO_ERROR ? 0 : (void(*)(void))pfn;
+}
+static void os2DlClose(sqlite3_vfs *pVfs, void *pHandle){
+  DosFreeModule((HMODULE)pHandle);
+}
+#else /* if SQLITE_OMIT_LOAD_EXTENSION is defined: */
+  #define os2DlOpen 0
+  #define os2DlError 0
+  #define os2DlSym 0
+  #define os2DlClose 0
+#endif
+
+
+/*
+** Write up to nBuf bytes of randomness into zBuf.
+*/
+static int os2Randomness(sqlite3_vfs *pVfs, int nBuf, char *zBuf ){
+  int n = 0;
+#if defined(SQLITE_TEST)
+  n = nBuf;
+  memset(zBuf, 0, nBuf);
+#else
+  int i;                           
+  PPIB ppib;
+  PTIB ptib;
+  DATETIME dt; 
+  static unsigned c = 0;
+  /* Ordered by variation probability */
+  static ULONG svIdx[6] = { QSV_MS_COUNT, QSV_TIME_LOW,
+                            QSV_MAXPRMEM, QSV_MAXSHMEM,
+                            QSV_TOTAVAILMEM, QSV_TOTRESMEM };
+
+  /* 8 bytes; timezone and weekday don't increase the randomness much */
+  if( (int)sizeof(dt)-3 <= nBuf - n ){
+    c += 0x0100;
+    DosGetDateTime(&dt);
+    dt.year = (USHORT)((dt.year - 1900) | c);
+    memcpy(&zBuf[n], &dt, sizeof(dt)-3);
+    n += sizeof(dt)-3;
+  }
+
+  /* 4 bytes; PIDs and TIDs are 16 bit internally, so combine them */
+  if( (int)sizeof(ULONG) <= nBuf - n ){
+    DosGetInfoBlocks(&ptib, &ppib);
+    *(PULONG)&zBuf[n] = MAKELONG(ppib->pib_ulpid,
+                                 ptib->tib_ptib2->tib2_ultid);
+    n += sizeof(ULONG);
+  }
+
+  /* Up to 6 * 4 bytes; variables depend on the system state */
+  for( i = 0; i < 6 && (int)sizeof(ULONG) <= nBuf - n; i++ ){
+    DosQuerySysInfo(svIdx[i], svIdx[i], 
+                    (PULONG)&zBuf[n], sizeof(ULONG));
+    n += sizeof(ULONG);
+  } 
+#endif
+
+  return n;
+}
+
+/*
+** Sleep for a little while.  Return the amount of time slept.
+** The argument is the number of microseconds we want to sleep.
+** The return value is the number of microseconds of sleep actually
+** requested from the underlying operating system, a number which
+** might be greater than or equal to the argument, but not less
+** than the argument.
+*/
+static int os2Sleep( sqlite3_vfs *pVfs, int microsec ){
+  DosSleep( (microsec/1000) );
+  return microsec;
+}
+
+/*
+** The following variable, if set to a non-zero value, becomes the result
+** returned from sqlite3OsCurrentTime().  This is used for testing.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_current_time = 0;
+#endif
+
+/*
+** Find the current time (in Universal Coordinated Time).  Write into *piNow
+** the current time and date as a Julian Day number times 86_400_000.  In
+** other words, write into *piNow the number of milliseconds since the Julian
+** epoch of noon in Greenwich on November 24, 4714 B.C according to the
+** proleptic Gregorian calendar.
+**
+** On success, return 0.  Return 1 if the time and date cannot be found.
+*/
+static int os2CurrentTimeInt64(sqlite3_vfs *pVfs, sqlite3_int64 *piNow){
+#ifdef SQLITE_TEST
+  static const sqlite3_int64 unixEpoch = 24405875*(sqlite3_int64)8640000;
+#endif
+  int year, month, datepart, timepart;
+ 
+  DATETIME dt;
+  DosGetDateTime( &dt );
+
+  year = dt.year;
+  month = dt.month;
+
+  /* Calculations from http://www.astro.keele.ac.uk/~rno/Astronomy/hjd.html
+  ** http://www.astro.keele.ac.uk/~rno/Astronomy/hjd-0.1.c
+  ** Calculate the Julian days
+  */
+  datepart = (int)dt.day - 32076 +
+    1461*(year + 4800 + (month - 14)/12)/4 +
+    367*(month - 2 - (month - 14)/12*12)/12 -
+    3*((year + 4900 + (month - 14)/12)/100)/4;
+
+  /* Time in milliseconds, hours to noon added */
+  timepart = 12*3600*1000 + dt.hundredths*10 + dt.seconds*1000 +
+    ((int)dt.minutes + dt.timezone)*60*1000 + dt.hours*3600*1000;
+
+  *piNow = (sqlite3_int64)datepart*86400*1000 + timepart;
+   
+#ifdef SQLITE_TEST
+  if( sqlite3_current_time ){
+    *piNow = 1000*(sqlite3_int64)sqlite3_current_time + unixEpoch;
+  }
+#endif
+
+  UNUSED_PARAMETER(pVfs);
+  return 0;
+}
+
+/*
+** Find the current time (in Universal Coordinated Time).  Write the
+** current time and date as a Julian Day number into *prNow and
+** return 0.  Return 1 if the time and date cannot be found.
+*/
+static int os2CurrentTime( sqlite3_vfs *pVfs, double *prNow ){
+  int rc;
+  sqlite3_int64 i;
+  rc = os2CurrentTimeInt64(pVfs, &i);
+  if( !rc ){
+    *prNow = i/86400000.0;
+  }
+  return rc;
+}
+
+/*
+** The idea is that this function works like a combination of
+** GetLastError() and FormatMessage() on windows (or errno and
+** strerror_r() on unix). After an error is returned by an OS
+** function, SQLite calls this function with zBuf pointing to
+** a buffer of nBuf bytes. The OS layer should populate the
+** buffer with a nul-terminated UTF-8 encoded error message
+** describing the last IO error to have occurred within the calling
+** thread.
+**
+** If the error message is too large for the supplied buffer,
+** it should be truncated. The return value of xGetLastError
+** is zero if the error message fits in the buffer, or non-zero
+** otherwise (if the message was truncated). If non-zero is returned,
+** then it is not necessary to include the nul-terminator character
+** in the output buffer.
+**
+** Not supplying an error message will have no adverse effect
+** on SQLite. It is fine to have an implementation that never
+** returns an error message:
+**
+**   int xGetLastError(sqlite3_vfs *pVfs, int nBuf, char *zBuf){
+**     assert(zBuf[0]=='\0');
+**     return 0;
+**   }
+**
+** However if an error message is supplied, it will be incorporated
+** by sqlite into the error message available to the user using
+** sqlite3_errmsg(), possibly making IO errors easier to debug.
+*/
+static int os2GetLastError(sqlite3_vfs *pVfs, int nBuf, char *zBuf){
+  assert(zBuf[0]=='\0');
+  return 0;
+}
+
+/*
+** Initialize and deinitialize the operating system interface.
+*/
+SQLITE_API int sqlite3_os_init(void){
+  static sqlite3_vfs os2Vfs = {
+    3,                 /* iVersion */
+    sizeof(os2File),   /* szOsFile */
+    CCHMAXPATH,        /* mxPathname */
+    0,                 /* pNext */
+    "os2",             /* zName */
+    0,                 /* pAppData */
+
+    os2Open,           /* xOpen */
+    os2Delete,         /* xDelete */
+    os2Access,         /* xAccess */
+    os2FullPathname,   /* xFullPathname */
+    os2DlOpen,         /* xDlOpen */
+    os2DlError,        /* xDlError */
+    os2DlSym,          /* xDlSym */
+    os2DlClose,        /* xDlClose */
+    os2Randomness,     /* xRandomness */
+    os2Sleep,          /* xSleep */
+    os2CurrentTime,    /* xCurrentTime */
+    os2GetLastError,   /* xGetLastError */
+    os2CurrentTimeInt64, /* xCurrentTimeInt64 */
+    0,                 /* xSetSystemCall */
+    0,                 /* xGetSystemCall */
+    0                  /* xNextSystemCall */
+  };
+  sqlite3_vfs_register(&os2Vfs, 1);
+  initUconvObjects();
+/*  sqlite3OSTrace = 1; */
+  return SQLITE_OK;
+}
+SQLITE_API int sqlite3_os_end(void){
+  freeUconvObjects();
+  return SQLITE_OK;
+}
+
+#endif /* SQLITE_OS_OS2 */
+
+/************** End of os_os2.c **********************************************/
+/************** Begin file os_unix.c *****************************************/
+/*
+** 2004 May 22
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains the VFS implementation for unix-like operating systems
+** include Linux, MacOSX, *BSD, QNX, VxWorks, AIX, HPUX, and others.
+**
+** There are actually several different VFS implementations in this file.
+** The differences are in the way that file locking is done.  The default
+** implementation uses Posix Advisory Locks.  Alternative implementations
+** use flock(), dot-files, various proprietary locking schemas, or simply
+** skip locking all together.
+**
+** This source file is organized into divisions where the logic for various
+** subfunctions is contained within the appropriate division.  PLEASE
+** KEEP THE STRUCTURE OF THIS FILE INTACT.  New code should be placed
+** in the correct division and should be clearly labeled.
+**
+** The layout of divisions is as follows:
+**
+**   *  General-purpose declarations and utility functions.
+**   *  Unique file ID logic used by VxWorks.
+**   *  Various locking primitive implementations (all except proxy locking):
+**      + for Posix Advisory Locks
+**      + for no-op locks
+**      + for dot-file locks
+**      + for flock() locking
+**      + for named semaphore locks (VxWorks only)
+**      + for AFP filesystem locks (MacOSX only)
+**   *  sqlite3_file methods not associated with locking.
+**   *  Definitions of sqlite3_io_methods objects for all locking
+**      methods plus "finder" functions for each locking method.
+**   *  sqlite3_vfs method implementations.
+**   *  Locking primitives for the proxy uber-locking-method. (MacOSX only)
+**   *  Definitions of sqlite3_vfs objects for all locking methods
+**      plus implementations of sqlite3_os_init() and sqlite3_os_end().
+*/
+#if SQLITE_OS_UNIX              /* This file is used on unix only */
+
+/*
+** There are various methods for file locking used for concurrency
+** control:
+**
+**   1. POSIX locking (the default),
+**   2. No locking,
+**   3. Dot-file locking,
+**   4. flock() locking,
+**   5. AFP locking (OSX only),
+**   6. Named POSIX semaphores (VXWorks only),
+**   7. proxy locking. (OSX only)
+**
+** Styles 4, 5, and 7 are only available of SQLITE_ENABLE_LOCKING_STYLE
+** is defined to 1.  The SQLITE_ENABLE_LOCKING_STYLE also enables automatic
+** selection of the appropriate locking style based on the filesystem
+** where the database is located.  
+*/
+#if !defined(SQLITE_ENABLE_LOCKING_STYLE)
+#  if defined(__APPLE__)
+#    define SQLITE_ENABLE_LOCKING_STYLE 1
+#  else
+#    define SQLITE_ENABLE_LOCKING_STYLE 0
+#  endif
+#endif
+
+/*
+** Define the OS_VXWORKS pre-processor macro to 1 if building on 
+** vxworks, or 0 otherwise.
+*/
+#ifndef OS_VXWORKS
+#  if defined(__RTP__) || defined(_WRS_KERNEL)
+#    define OS_VXWORKS 1
+#  else
+#    define OS_VXWORKS 0
+#  endif
+#endif
+
+/*
+** These #defines should enable >2GB file support on Posix if the
+** underlying operating system supports it.  If the OS lacks
+** large file support, these should be no-ops.
+**
+** Large file support can be disabled using the -DSQLITE_DISABLE_LFS switch
+** on the compiler command line.  This is necessary if you are compiling
+** on a recent machine (ex: RedHat 7.2) but you want your code to work
+** on an older machine (ex: RedHat 6.0).  If you compile on RedHat 7.2
+** without this option, LFS is enable.  But LFS does not exist in the kernel
+** in RedHat 6.0, so the code won't work.  Hence, for maximum binary
+** portability you should omit LFS.
+**
+** The previous paragraph was written in 2005.  (This paragraph is written
+** on 2008-11-28.) These days, all Linux kernels support large files, so
+** you should probably leave LFS enabled.  But some embedded platforms might
+** lack LFS in which case the SQLITE_DISABLE_LFS macro might still be useful.
+*/
+#ifndef SQLITE_DISABLE_LFS
+# define _LARGE_FILE       1
+# ifndef _FILE_OFFSET_BITS
+#   define _FILE_OFFSET_BITS 64
+# endif
+# define _LARGEFILE_SOURCE 1
+#endif
+
+/*
+** standard include files.
+*/
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/time.h>
+#include <errno.h>
+#ifndef SQLITE_OMIT_WAL
+#include <sys/mman.h>
+#endif
+
+#if SQLITE_ENABLE_LOCKING_STYLE
+# include <sys/ioctl.h>
+# if OS_VXWORKS
+#  include <semaphore.h>
+#  include <limits.h>
+# else
+#  include <sys/file.h>
+#  include <sys/param.h>
+# endif
+#endif /* SQLITE_ENABLE_LOCKING_STYLE */
+
+#if defined(__APPLE__) || (SQLITE_ENABLE_LOCKING_STYLE && !OS_VXWORKS)
+# include <sys/mount.h>
+#endif
+
+/*
+** Allowed values of unixFile.fsFlags
+*/
+#define SQLITE_FSFLAGS_IS_MSDOS     0x1
+
+/*
+** If we are to be thread-safe, include the pthreads header and define
+** the SQLITE_UNIX_THREADS macro.
+*/
+#if SQLITE_THREADSAFE
+# define SQLITE_UNIX_THREADS 1
+#endif
+
+/*
+** Default permissions when creating a new file
+*/
+#ifndef SQLITE_DEFAULT_FILE_PERMISSIONS
+# define SQLITE_DEFAULT_FILE_PERMISSIONS 0644
+#endif
+
+/*
+ ** Default permissions when creating auto proxy dir
+ */
+#ifndef SQLITE_DEFAULT_PROXYDIR_PERMISSIONS
+# define SQLITE_DEFAULT_PROXYDIR_PERMISSIONS 0755
+#endif
+
+/*
+** Maximum supported path-length.
+*/
+#define MAX_PATHNAME 512
+
+/*
+** Only set the lastErrno if the error code is a real error and not 
+** a normal expected return code of SQLITE_BUSY or SQLITE_OK
+*/
+#define IS_LOCK_ERROR(x)  ((x != SQLITE_OK) && (x != SQLITE_BUSY))
+
+/* Forward references */
+typedef struct unixShm unixShm;               /* Connection shared memory */
+typedef struct unixShmNode unixShmNode;       /* Shared memory instance */
+typedef struct unixInodeInfo unixInodeInfo;   /* An i-node */
+typedef struct UnixUnusedFd UnixUnusedFd;     /* An unused file descriptor */
+
+/*
+** Sometimes, after a file handle is closed by SQLite, the file descriptor
+** cannot be closed immediately. In these cases, instances of the following
+** structure are used to store the file descriptor while waiting for an
+** opportunity to either close or reuse it.
+*/
+struct UnixUnusedFd {
+  int fd;                   /* File descriptor to close */
+  int flags;                /* Flags this file descriptor was opened with */
+  UnixUnusedFd *pNext;      /* Next unused file descriptor on same file */
+};
+
+/*
+** The unixFile structure is subclass of sqlite3_file specific to the unix
+** VFS implementations.
+*/
+typedef struct unixFile unixFile;
+struct unixFile {
+  sqlite3_io_methods const *pMethod;  /* Always the first entry */
+  unixInodeInfo *pInode;              /* Info about locks on this inode */
+  int h;                              /* The file descriptor */
+  int dirfd;                          /* File descriptor for the directory */
+  unsigned char eFileLock;            /* The type of lock held on this fd */
+  unsigned char ctrlFlags;            /* Behavioral bits.  UNIXFILE_* flags */
+  int lastErrno;                      /* The unix errno from last I/O error */
+  void *lockingContext;               /* Locking style specific state */
+  UnixUnusedFd *pUnused;              /* Pre-allocated UnixUnusedFd */
+  const char *zPath;                  /* Name of the file */
+  unixShm *pShm;                      /* Shared memory segment information */
+  int szChunk;                        /* Configured by FCNTL_CHUNK_SIZE */
+#if SQLITE_ENABLE_LOCKING_STYLE
+  int openFlags;                      /* The flags specified at open() */
+#endif
+#if SQLITE_ENABLE_LOCKING_STYLE || defined(__APPLE__)
+  unsigned fsFlags;                   /* cached details from statfs() */
+#endif
+#if OS_VXWORKS
+  int isDelete;                       /* Delete on close if true */
+  struct vxworksFileId *pId;          /* Unique file ID */
+#endif
+#ifndef NDEBUG
+  /* The next group of variables are used to track whether or not the
+  ** transaction counter in bytes 24-27 of database files are updated
+  ** whenever any part of the database changes.  An assertion fault will
+  ** occur if a file is updated without also updating the transaction
+  ** counter.  This test is made to avoid new problems similar to the
+  ** one described by ticket #3584. 
+  */
+  unsigned char transCntrChng;   /* True if the transaction counter changed */
+  unsigned char dbUpdate;        /* True if any part of database file changed */
+  unsigned char inNormalWrite;   /* True if in a normal write operation */
+#endif
+#ifdef SQLITE_TEST
+  /* In test mode, increase the size of this structure a bit so that 
+  ** it is larger than the struct CrashFile defined in test6.c.
+  */
+  char aPadding[32];
+#endif
+};
+
+/*
+** Allowed values for the unixFile.ctrlFlags bitmask:
+*/
+#define UNIXFILE_EXCL   0x01     /* Connections from one process only */
+#define UNIXFILE_RDONLY 0x02     /* Connection is read only */
+
+/*
+** Include code that is common to all os_*.c files
+*/
+/************** Include os_common.h in the middle of os_unix.c ***************/
+/************** Begin file os_common.h ***************************************/
+/*
+** 2004 May 22
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains macros and a little bit of code that is common to
+** all of the platform-specific files (os_*.c) and is #included into those
+** files.
+**
+** This file should be #included by the os_*.c files only.  It is not a
+** general purpose header file.
+*/
+#ifndef _OS_COMMON_H_
+#define _OS_COMMON_H_
+
+/*
+** At least two bugs have slipped in because we changed the MEMORY_DEBUG
+** macro to SQLITE_DEBUG and some older makefiles have not yet made the
+** switch.  The following code should catch this problem at compile-time.
+*/
+#ifdef MEMORY_DEBUG
+# error "The MEMORY_DEBUG macro is obsolete.  Use SQLITE_DEBUG instead."
+#endif
+
+#ifdef SQLITE_DEBUG
+SQLITE_PRIVATE int sqlite3OSTrace = 0;
+#define OSTRACE(X)          if( sqlite3OSTrace ) sqlite3DebugPrintf X
+#else
+#define OSTRACE(X)
+#endif
+
+/*
+** Macros for performance tracing.  Normally turned off.  Only works
+** on i486 hardware.
+*/
+#ifdef SQLITE_PERFORMANCE_TRACE
+
+/* 
+** hwtime.h contains inline assembler code for implementing 
+** high-performance timing routines.
+*/
+/************** Include hwtime.h in the middle of os_common.h ****************/
+/************** Begin file hwtime.h ******************************************/
+/*
+** 2008 May 27
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains inline asm code for retrieving "high-performance"
+** counters for x86 class CPUs.
+*/
+#ifndef _HWTIME_H_
+#define _HWTIME_H_
+
+/*
+** The following routine only works on pentium-class (or newer) processors.
+** It uses the RDTSC opcode to read the cycle count value out of the
+** processor and returns that value.  This can be used for high-res
+** profiling.
+*/
+#if (defined(__GNUC__) || defined(_MSC_VER)) && \
+      (defined(i386) || defined(__i386__) || defined(_M_IX86))
+
+  #if defined(__GNUC__)
+
+  __inline__ sqlite_uint64 sqlite3Hwtime(void){
+     unsigned int lo, hi;
+     __asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi));
+     return (sqlite_uint64)hi << 32 | lo;
+  }
+
+  #elif defined(_MSC_VER)
+
+  __declspec(naked) __inline sqlite_uint64 __cdecl sqlite3Hwtime(void){
+     __asm {
+        rdtsc
+        ret       ; return value at EDX:EAX
+     }
+  }
+
+  #endif
+
+#elif (defined(__GNUC__) && defined(__x86_64__))
+
+  __inline__ sqlite_uint64 sqlite3Hwtime(void){
+      unsigned long val;
+      __asm__ __volatile__ ("rdtsc" : "=A" (val));
+      return val;
+  }
+ 
+#elif (defined(__GNUC__) && defined(__ppc__))
+
+  __inline__ sqlite_uint64 sqlite3Hwtime(void){
+      unsigned long long retval;
+      unsigned long junk;
+      __asm__ __volatile__ ("\n\
+          1:      mftbu   %1\n\
+                  mftb    %L0\n\
+                  mftbu   %0\n\
+                  cmpw    %0,%1\n\
+                  bne     1b"
+                  : "=r" (retval), "=r" (junk));
+      return retval;
+  }
+
+#else
+
+  #error Need implementation of sqlite3Hwtime() for your platform.
+
+  /*
+  ** To compile without implementing sqlite3Hwtime() for your platform,
+  ** you can remove the above #error and use the following
+  ** stub function.  You will lose timing support for many
+  ** of the debugging and testing utilities, but it should at
+  ** least compile and run.
+  */
+SQLITE_PRIVATE   sqlite_uint64 sqlite3Hwtime(void){ return ((sqlite_uint64)0); }
+
+#endif
+
+#endif /* !defined(_HWTIME_H_) */
+
+/************** End of hwtime.h **********************************************/
+/************** Continuing where we left off in os_common.h ******************/
+
+static sqlite_uint64 g_start;
+static sqlite_uint64 g_elapsed;
+#define TIMER_START       g_start=sqlite3Hwtime()
+#define TIMER_END         g_elapsed=sqlite3Hwtime()-g_start
+#define TIMER_ELAPSED     g_elapsed
+#else
+#define TIMER_START
+#define TIMER_END
+#define TIMER_ELAPSED     ((sqlite_uint64)0)
+#endif
+
+/*
+** If we compile with the SQLITE_TEST macro set, then the following block
+** of code will give us the ability to simulate a disk I/O error.  This
+** is used for testing the I/O recovery logic.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_io_error_hit = 0;            /* Total number of I/O Errors */
+SQLITE_API int sqlite3_io_error_hardhit = 0;        /* Number of non-benign errors */
+SQLITE_API int sqlite3_io_error_pending = 0;        /* Count down to first I/O error */
+SQLITE_API int sqlite3_io_error_persist = 0;        /* True if I/O errors persist */
+SQLITE_API int sqlite3_io_error_benign = 0;         /* True if errors are benign */
+SQLITE_API int sqlite3_diskfull_pending = 0;
+SQLITE_API int sqlite3_diskfull = 0;
+#define SimulateIOErrorBenign(X) sqlite3_io_error_benign=(X)
+#define SimulateIOError(CODE)  \
+  if( (sqlite3_io_error_persist && sqlite3_io_error_hit) \
+       || sqlite3_io_error_pending-- == 1 )  \
+              { local_ioerr(); CODE; }
+static void local_ioerr(){
+  IOTRACE(("IOERR\n"));
+  sqlite3_io_error_hit++;
+  if( !sqlite3_io_error_benign ) sqlite3_io_error_hardhit++;
+}
+#define SimulateDiskfullError(CODE) \
+   if( sqlite3_diskfull_pending ){ \
+     if( sqlite3_diskfull_pending == 1 ){ \
+       local_ioerr(); \
+       sqlite3_diskfull = 1; \
+       sqlite3_io_error_hit = 1; \
+       CODE; \
+     }else{ \
+       sqlite3_diskfull_pending--; \
+     } \
+   }
+#else
+#define SimulateIOErrorBenign(X)
+#define SimulateIOError(A)
+#define SimulateDiskfullError(A)
+#endif
+
+/*
+** When testing, keep a count of the number of open files.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_open_file_count = 0;
+#define OpenCounter(X)  sqlite3_open_file_count+=(X)
+#else
+#define OpenCounter(X)
+#endif
+
+#endif /* !defined(_OS_COMMON_H_) */
+
+/************** End of os_common.h *******************************************/
+/************** Continuing where we left off in os_unix.c ********************/
+
+/*
+** Define various macros that are missing from some systems.
+*/
+#ifndef O_LARGEFILE
+# define O_LARGEFILE 0
+#endif
+#ifdef SQLITE_DISABLE_LFS
+# undef O_LARGEFILE
+# define O_LARGEFILE 0
+#endif
+#ifndef O_NOFOLLOW
+# define O_NOFOLLOW 0
+#endif
+#ifndef O_BINARY
+# define O_BINARY 0
+#endif
+
+/*
+** The threadid macro resolves to the thread-id or to 0.  Used for
+** testing and debugging only.
+*/
+#if SQLITE_THREADSAFE
+#define threadid pthread_self()
+#else
+#define threadid 0
+#endif
+
+/*
+** Many system calls are accessed through pointer-to-functions so that
+** they may be overridden at runtime to facilitate fault injection during
+** testing and sandboxing.  The following array holds the names and pointers
+** to all overrideable system calls.
+*/
+static struct unix_syscall {
+  const char *zName;            /* Name of the sytem call */
+  sqlite3_syscall_ptr pCurrent; /* Current value of the system call */
+  sqlite3_syscall_ptr pDefault; /* Default value */
+} aSyscall[] = {
+  { "open",         (sqlite3_syscall_ptr)open,       0  },
+#define osOpen      ((int(*)(const char*,int,...))aSyscall[0].pCurrent)
+
+  { "close",        (sqlite3_syscall_ptr)close,      0  },
+#define osClose     ((int(*)(int))aSyscall[1].pCurrent)
+
+  { "access",       (sqlite3_syscall_ptr)access,     0  },
+#define osAccess    ((int(*)(const char*,int))aSyscall[2].pCurrent)
+
+  { "getcwd",       (sqlite3_syscall_ptr)getcwd,     0  },
+#define osGetcwd    ((char*(*)(char*,size_t))aSyscall[3].pCurrent)
+
+  { "stat",         (sqlite3_syscall_ptr)stat,       0  },
+#define osStat      ((int(*)(const char*,struct stat*))aSyscall[4].pCurrent)
+
+/*
+** The DJGPP compiler environment looks mostly like Unix, but it
+** lacks the fcntl() system call.  So redefine fcntl() to be something
+** that always succeeds.  This means that locking does not occur under
+** DJGPP.  But it is DOS - what did you expect?
+*/
+#ifdef __DJGPP__
+  { "fstat",        0,                 0  },
+#define osFstat(a,b,c)    0
+#else     
+  { "fstat",        (sqlite3_syscall_ptr)fstat,      0  },
+#define osFstat     ((int(*)(int,struct stat*))aSyscall[5].pCurrent)
+#endif
+
+  { "ftruncate",    (sqlite3_syscall_ptr)ftruncate,  0  },
+#define osFtruncate ((int(*)(int,off_t))aSyscall[6].pCurrent)
+
+  { "fcntl",        (sqlite3_syscall_ptr)fcntl,      0  },
+#define osFcntl     ((int(*)(int,int,...))aSyscall[7].pCurrent)
+
+  { "read",         (sqlite3_syscall_ptr)read,       0  },
+#define osRead      ((ssize_t(*)(int,void*,size_t))aSyscall[8].pCurrent)
+
+#if defined(USE_PREAD) || defined(SQLITE_ENABLE_LOCKING_STYLE)
+  { "pread",        (sqlite3_syscall_ptr)pread,      0  },
+#else
+  { "pread",        (sqlite3_syscall_ptr)0,          0  },
+#endif
+#define osPread     ((ssize_t(*)(int,void*,size_t,off_t))aSyscall[9].pCurrent)
+
+#if defined(USE_PREAD64)
+  { "pread64",      (sqlite3_syscall_ptr)pread64,    0  },
+#else
+  { "pread64",      (sqlite3_syscall_ptr)0,          0  },
+#endif
+#define osPread64   ((ssize_t(*)(int,void*,size_t,off_t))aSyscall[10].pCurrent)
+
+  { "write",        (sqlite3_syscall_ptr)write,      0  },
+#define osWrite     ((ssize_t(*)(int,const void*,size_t))aSyscall[11].pCurrent)
+
+#if defined(USE_PREAD) || defined(SQLITE_ENABLE_LOCKING_STYLE)
+  { "pwrite",       (sqlite3_syscall_ptr)pwrite,     0  },
+#else
+  { "pwrite",       (sqlite3_syscall_ptr)0,          0  },
+#endif
+#define osPwrite    ((ssize_t(*)(int,const void*,size_t,off_t))\
+                    aSyscall[12].pCurrent)
+
+#if defined(USE_PREAD64)
+  { "pwrite64",     (sqlite3_syscall_ptr)pwrite64,   0  },
+#else
+  { "pwrite64",     (sqlite3_syscall_ptr)0,          0  },
+#endif
+#define osPwrite64  ((ssize_t(*)(int,const void*,size_t,off_t))\
+                    aSyscall[13].pCurrent)
+
+#if SQLITE_ENABLE_LOCKING_STYLE
+  { "fchmod",       (sqlite3_syscall_ptr)fchmod,     0  },
+#else
+  { "fchmod",       (sqlite3_syscall_ptr)0,          0  },
+#endif
+#define osFchmod    ((int(*)(int,mode_t))aSyscall[14].pCurrent)
+
+#if defined(HAVE_POSIX_FALLOCATE) && HAVE_POSIX_FALLOCATE
+  { "fallocate",    (sqlite3_syscall_ptr)posix_fallocate,  0 },
+#else
+  { "fallocate",    (sqlite3_syscall_ptr)0,                0 },
+#endif
+#define osFallocate ((int(*)(int,off_t,off_t))aSyscall[15].pCurrent)
+
+}; /* End of the overrideable system calls */
+
+/*
+** This is the xSetSystemCall() method of sqlite3_vfs for all of the
+** "unix" VFSes.  Return SQLITE_OK opon successfully updating the
+** system call pointer, or SQLITE_NOTFOUND if there is no configurable
+** system call named zName.
+*/
+static int unixSetSystemCall(
+  sqlite3_vfs *pNotUsed,        /* The VFS pointer.  Not used */
+  const char *zName,            /* Name of system call to override */
+  sqlite3_syscall_ptr pNewFunc  /* Pointer to new system call value */
+){
+  unsigned int i;
+  int rc = SQLITE_NOTFOUND;
+
+  UNUSED_PARAMETER(pNotUsed);
+  if( zName==0 ){
+    /* If no zName is given, restore all system calls to their default
+    ** settings and return NULL
+    */
+    rc = SQLITE_OK;
+    for(i=0; i<sizeof(aSyscall)/sizeof(aSyscall[0]); i++){
+      if( aSyscall[i].pDefault ){
+        aSyscall[i].pCurrent = aSyscall[i].pDefault;
+      }
+    }
+  }else{
+    /* If zName is specified, operate on only the one system call
+    ** specified.
+    */
+    for(i=0; i<sizeof(aSyscall)/sizeof(aSyscall[0]); i++){
+      if( strcmp(zName, aSyscall[i].zName)==0 ){
+        if( aSyscall[i].pDefault==0 ){
+          aSyscall[i].pDefault = aSyscall[i].pCurrent;
+        }
+        rc = SQLITE_OK;
+        if( pNewFunc==0 ) pNewFunc = aSyscall[i].pDefault;
+        aSyscall[i].pCurrent = pNewFunc;
+        break;
+      }
+    }
+  }
+  return rc;
+}
+
+/*
+** Return the value of a system call.  Return NULL if zName is not a
+** recognized system call name.  NULL is also returned if the system call
+** is currently undefined.
+*/
+static sqlite3_syscall_ptr unixGetSystemCall(
+  sqlite3_vfs *pNotUsed,
+  const char *zName
+){
+  unsigned int i;
+
+  UNUSED_PARAMETER(pNotUsed);
+  for(i=0; i<sizeof(aSyscall)/sizeof(aSyscall[0]); i++){
+    if( strcmp(zName, aSyscall[i].zName)==0 ) return aSyscall[i].pCurrent;
+  }
+  return 0;
+}
+
+/*
+** Return the name of the first system call after zName.  If zName==NULL
+** then return the name of the first system call.  Return NULL if zName
+** is the last system call or if zName is not the name of a valid
+** system call.
+*/
+static const char *unixNextSystemCall(sqlite3_vfs *p, const char *zName){
+  int i = -1;
+
+  UNUSED_PARAMETER(p);
+  if( zName ){
+    for(i=0; i<ArraySize(aSyscall)-1; i++){
+      if( strcmp(zName, aSyscall[i].zName)==0 ) break;
+    }
+  }
+  for(i++; i<ArraySize(aSyscall); i++){
+    if( aSyscall[i].pCurrent!=0 ) return aSyscall[i].zName;
+  }
+  return 0;
+}
+
+/*
+** Retry open() calls that fail due to EINTR
+*/
+static int robust_open(const char *z, int f, int m){
+  int rc;
+  do{ rc = osOpen(z,f,m); }while( rc<0 && errno==EINTR );
+  return rc;
+}
+
+/*
+** Helper functions to obtain and relinquish the global mutex. The
+** global mutex is used to protect the unixInodeInfo and
+** vxworksFileId objects used by this file, all of which may be 
+** shared by multiple threads.
+**
+** Function unixMutexHeld() is used to assert() that the global mutex 
+** is held when required. This function is only used as part of assert() 
+** statements. e.g.
+**
+**   unixEnterMutex()
+**     assert( unixMutexHeld() );
+**   unixEnterLeave()
+*/
+static void unixEnterMutex(void){
+  sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
+}
+static void unixLeaveMutex(void){
+  sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
+}
+#ifdef SQLITE_DEBUG
+static int unixMutexHeld(void) {
+  return sqlite3_mutex_held(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
+}
+#endif
+
+
+#ifdef SQLITE_DEBUG
+/*
+** Helper function for printing out trace information from debugging
+** binaries. This returns the string represetation of the supplied
+** integer lock-type.
+*/
+static const char *azFileLock(int eFileLock){
+  switch( eFileLock ){
+    case NO_LOCK: return "NONE";
+    case SHARED_LOCK: return "SHARED";
+    case RESERVED_LOCK: return "RESERVED";
+    case PENDING_LOCK: return "PENDING";
+    case EXCLUSIVE_LOCK: return "EXCLUSIVE";
+  }
+  return "ERROR";
+}
+#endif
+
+#ifdef SQLITE_LOCK_TRACE
+/*
+** Print out information about all locking operations.
+**
+** This routine is used for troubleshooting locks on multithreaded
+** platforms.  Enable by compiling with the -DSQLITE_LOCK_TRACE
+** command-line option on the compiler.  This code is normally
+** turned off.
+*/
+static int lockTrace(int fd, int op, struct flock *p){
+  char *zOpName, *zType;
+  int s;
+  int savedErrno;
+  if( op==F_GETLK ){
+    zOpName = "GETLK";
+  }else if( op==F_SETLK ){
+    zOpName = "SETLK";
+  }else{
+    s = osFcntl(fd, op, p);
+    sqlite3DebugPrintf("fcntl unknown %d %d %d\n", fd, op, s);
+    return s;
+  }
+  if( p->l_type==F_RDLCK ){
+    zType = "RDLCK";
+  }else if( p->l_type==F_WRLCK ){
+    zType = "WRLCK";
+  }else if( p->l_type==F_UNLCK ){
+    zType = "UNLCK";
+  }else{
+    assert( 0 );
+  }
+  assert( p->l_whence==SEEK_SET );
+  s = osFcntl(fd, op, p);
+  savedErrno = errno;
+  sqlite3DebugPrintf("fcntl %d %d %s %s %d %d %d %d\n",
+     threadid, fd, zOpName, zType, (int)p->l_start, (int)p->l_len,
+     (int)p->l_pid, s);
+  if( s==(-1) && op==F_SETLK && (p->l_type==F_RDLCK || p->l_type==F_WRLCK) ){
+    struct flock l2;
+    l2 = *p;
+    osFcntl(fd, F_GETLK, &l2);
+    if( l2.l_type==F_RDLCK ){
+      zType = "RDLCK";
+    }else if( l2.l_type==F_WRLCK ){
+      zType = "WRLCK";
+    }else if( l2.l_type==F_UNLCK ){
+      zType = "UNLCK";
+    }else{
+      assert( 0 );
+    }
+    sqlite3DebugPrintf("fcntl-failure-reason: %s %d %d %d\n",
+       zType, (int)l2.l_start, (int)l2.l_len, (int)l2.l_pid);
+  }
+  errno = savedErrno;
+  return s;
+}
+#undef osFcntl
+#define osFcntl lockTrace
+#endif /* SQLITE_LOCK_TRACE */
+
+/*
+** Retry ftruncate() calls that fail due to EINTR
+*/
+static int robust_ftruncate(int h, sqlite3_int64 sz){
+  int rc;
+  do{ rc = osFtruncate(h,sz); }while( rc<0 && errno==EINTR );
+  return rc;
+}
+
+/*
+** This routine translates a standard POSIX errno code into something
+** useful to the clients of the sqlite3 functions.  Specifically, it is
+** intended to translate a variety of "try again" errors into SQLITE_BUSY
+** and a variety of "please close the file descriptor NOW" errors into 
+** SQLITE_IOERR
+** 
+** Errors during initialization of locks, or file system support for locks,
+** should handle ENOLCK, ENOTSUP, EOPNOTSUPP separately.
+*/
+static int sqliteErrorFromPosixError(int posixError, int sqliteIOErr) {
+  switch (posixError) {
+#if 0
+  /* At one point this code was not commented out. In theory, this branch
+  ** should never be hit, as this function should only be called after
+  ** a locking-related function (i.e. fcntl()) has returned non-zero with
+  ** the value of errno as the first argument. Since a system call has failed,
+  ** errno should be non-zero.
+  **
+  ** Despite this, if errno really is zero, we still don't want to return
+  ** SQLITE_OK. The system call failed, and *some* SQLite error should be
+  ** propagated back to the caller. Commenting this branch out means errno==0
+  ** will be handled by the "default:" case below.
+  */
+  case 0: 
+    return SQLITE_OK;
+#endif
+
+  case EAGAIN:
+  case ETIMEDOUT:
+  case EBUSY:
+  case EINTR:
+  case ENOLCK:  
+    /* random NFS retry error, unless during file system support 
+     * introspection, in which it actually means what it says */
+    return SQLITE_BUSY;
+    
+  case EACCES: 
+    /* EACCES is like EAGAIN during locking operations, but not any other time*/
+    if( (sqliteIOErr == SQLITE_IOERR_LOCK) || 
+	(sqliteIOErr == SQLITE_IOERR_UNLOCK) || 
+	(sqliteIOErr == SQLITE_IOERR_RDLOCK) ||
+	(sqliteIOErr == SQLITE_IOERR_CHECKRESERVEDLOCK) ){
+      return SQLITE_BUSY;
+    }
+    /* else fall through */
+  case EPERM: 
+    return SQLITE_PERM;
+    
+  /* EDEADLK is only possible if a call to fcntl(F_SETLKW) is made. And
+  ** this module never makes such a call. And the code in SQLite itself 
+  ** asserts that SQLITE_IOERR_BLOCKED is never returned. For these reasons
+  ** this case is also commented out. If the system does set errno to EDEADLK,
+  ** the default SQLITE_IOERR_XXX code will be returned. */
+#if 0
+  case EDEADLK:
+    return SQLITE_IOERR_BLOCKED;
+#endif
+    
+#if EOPNOTSUPP!=ENOTSUP
+  case EOPNOTSUPP: 
+    /* something went terribly awry, unless during file system support 
+     * introspection, in which it actually means what it says */
+#endif
+#ifdef ENOTSUP
+  case ENOTSUP: 
+    /* invalid fd, unless during file system support introspection, in which 
+     * it actually means what it says */
+#endif
+  case EIO:
+  case EBADF:
+  case EINVAL:
+  case ENOTCONN:
+  case ENODEV:
+  case ENXIO:
+  case ENOENT:
+  case ESTALE:
+  case ENOSYS:
+    /* these should force the client to close the file and reconnect */
+    
+  default: 
+    return sqliteIOErr;
+  }
+}
+
+
+
+/******************************************************************************
+****************** Begin Unique File ID Utility Used By VxWorks ***************
+**
+** On most versions of unix, we can get a unique ID for a file by concatenating
+** the device number and the inode number.  But this does not work on VxWorks.
+** On VxWorks, a unique file id must be based on the canonical filename.
+**
+** A pointer to an instance of the following structure can be used as a
+** unique file ID in VxWorks.  Each instance of this structure contains
+** a copy of the canonical filename.  There is also a reference count.  
+** The structure is reclaimed when the number of pointers to it drops to
+** zero.
+**
+** There are never very many files open at one time and lookups are not
+** a performance-critical path, so it is sufficient to put these
+** structures on a linked list.
+*/
+struct vxworksFileId {
+  struct vxworksFileId *pNext;  /* Next in a list of them all */
+  int nRef;                     /* Number of references to this one */
+  int nName;                    /* Length of the zCanonicalName[] string */
+  char *zCanonicalName;         /* Canonical filename */
+};
+
+#if OS_VXWORKS
+/* 
+** All unique filenames are held on a linked list headed by this
+** variable:
+*/
+static struct vxworksFileId *vxworksFileList = 0;
+
+/*
+** Simplify a filename into its canonical form
+** by making the following changes:
+**
+**  * removing any trailing and duplicate /
+**  * convert /./ into just /
+**  * convert /A/../ where A is any simple name into just /
+**
+** Changes are made in-place.  Return the new name length.
+**
+** The original filename is in z[0..n-1].  Return the number of
+** characters in the simplified name.
+*/
+static int vxworksSimplifyName(char *z, int n){
+  int i, j;
+  while( n>1 && z[n-1]=='/' ){ n--; }
+  for(i=j=0; i<n; i++){
+    if( z[i]=='/' ){
+      if( z[i+1]=='/' ) continue;
+      if( z[i+1]=='.' && i+2<n && z[i+2]=='/' ){
+        i += 1;
+        continue;
+      }
+      if( z[i+1]=='.' && i+3<n && z[i+2]=='.' && z[i+3]=='/' ){
+        while( j>0 && z[j-1]!='/' ){ j--; }
+        if( j>0 ){ j--; }
+        i += 2;
+        continue;
+      }
+    }
+    z[j++] = z[i];
+  }
+  z[j] = 0;
+  return j;
+}
+
+/*
+** Find a unique file ID for the given absolute pathname.  Return
+** a pointer to the vxworksFileId object.  This pointer is the unique
+** file ID.
+**
+** The nRef field of the vxworksFileId object is incremented before
+** the object is returned.  A new vxworksFileId object is created
+** and added to the global list if necessary.
+**
+** If a memory allocation error occurs, return NULL.
+*/
+static struct vxworksFileId *vxworksFindFileId(const char *zAbsoluteName){
+  struct vxworksFileId *pNew;         /* search key and new file ID */
+  struct vxworksFileId *pCandidate;   /* For looping over existing file IDs */
+  int n;                              /* Length of zAbsoluteName string */
+
+  assert( zAbsoluteName[0]=='/' );
+  n = (int)strlen(zAbsoluteName);
+  pNew = sqlite3_malloc( sizeof(*pNew) + (n+1) );
+  if( pNew==0 ) return 0;
+  pNew->zCanonicalName = (char*)&pNew[1];
+  memcpy(pNew->zCanonicalName, zAbsoluteName, n+1);
+  n = vxworksSimplifyName(pNew->zCanonicalName, n);
+
+  /* Search for an existing entry that matching the canonical name.
+  ** If found, increment the reference count and return a pointer to
+  ** the existing file ID.
+  */
+  unixEnterMutex();
+  for(pCandidate=vxworksFileList; pCandidate; pCandidate=pCandidate->pNext){
+    if( pCandidate->nName==n 
+     && memcmp(pCandidate->zCanonicalName, pNew->zCanonicalName, n)==0
+    ){
+       sqlite3_free(pNew);
+       pCandidate->nRef++;
+       unixLeaveMutex();
+       return pCandidate;
+    }
+  }
+
+  /* No match was found.  We will make a new file ID */
+  pNew->nRef = 1;
+  pNew->nName = n;
+  pNew->pNext = vxworksFileList;
+  vxworksFileList = pNew;
+  unixLeaveMutex();
+  return pNew;
+}
+
+/*
+** Decrement the reference count on a vxworksFileId object.  Free
+** the object when the reference count reaches zero.
+*/
+static void vxworksReleaseFileId(struct vxworksFileId *pId){
+  unixEnterMutex();
+  assert( pId->nRef>0 );
+  pId->nRef--;
+  if( pId->nRef==0 ){
+    struct vxworksFileId **pp;
+    for(pp=&vxworksFileList; *pp && *pp!=pId; pp = &((*pp)->pNext)){}
+    assert( *pp==pId );
+    *pp = pId->pNext;
+    sqlite3_free(pId);
+  }
+  unixLeaveMutex();
+}
+#endif /* OS_VXWORKS */
+/*************** End of Unique File ID Utility Used By VxWorks ****************
+******************************************************************************/
+
+
+/******************************************************************************
+*************************** Posix Advisory Locking ****************************
+**
+** POSIX advisory locks are broken by design.  ANSI STD 1003.1 (1996)
+** section 6.5.2.2 lines 483 through 490 specify that when a process
+** sets or clears a lock, that operation overrides any prior locks set
+** by the same process.  It does not explicitly say so, but this implies
+** that it overrides locks set by the same process using a different
+** file descriptor.  Consider this test case:
+**
+**       int fd1 = open("./file1", O_RDWR|O_CREAT, 0644);
+**       int fd2 = open("./file2", O_RDWR|O_CREAT, 0644);
+**
+** Suppose ./file1 and ./file2 are really the same file (because
+** one is a hard or symbolic link to the other) then if you set
+** an exclusive lock on fd1, then try to get an exclusive lock
+** on fd2, it works.  I would have expected the second lock to
+** fail since there was already a lock on the file due to fd1.
+** But not so.  Since both locks came from the same process, the
+** second overrides the first, even though they were on different
+** file descriptors opened on different file names.
+**
+** This means that we cannot use POSIX locks to synchronize file access
+** among competing threads of the same process.  POSIX locks will work fine
+** to synchronize access for threads in separate processes, but not
+** threads within the same process.
+**
+** To work around the problem, SQLite has to manage file locks internally
+** on its own.  Whenever a new database is opened, we have to find the
+** specific inode of the database file (the inode is determined by the
+** st_dev and st_ino fields of the stat structure that fstat() fills in)
+** and check for locks already existing on that inode.  When locks are
+** created or removed, we have to look at our own internal record of the
+** locks to see if another thread has previously set a lock on that same
+** inode.
+**
+** (Aside: The use of inode numbers as unique IDs does not work on VxWorks.
+** For VxWorks, we have to use the alternative unique ID system based on
+** canonical filename and implemented in the previous division.)
+**
+** The sqlite3_file structure for POSIX is no longer just an integer file
+** descriptor.  It is now a structure that holds the integer file
+** descriptor and a pointer to a structure that describes the internal
+** locks on the corresponding inode.  There is one locking structure
+** per inode, so if the same inode is opened twice, both unixFile structures
+** point to the same locking structure.  The locking structure keeps
+** a reference count (so we will know when to delete it) and a "cnt"
+** field that tells us its internal lock status.  cnt==0 means the
+** file is unlocked.  cnt==-1 means the file has an exclusive lock.
+** cnt>0 means there are cnt shared locks on the file.
+**
+** Any attempt to lock or unlock a file first checks the locking
+** structure.  The fcntl() system call is only invoked to set a 
+** POSIX lock if the internal lock structure transitions between
+** a locked and an unlocked state.
+**
+** But wait:  there are yet more problems with POSIX advisory locks.
+**
+** If you close a file descriptor that points to a file that has locks,
+** all locks on that file that are owned by the current process are
+** released.  To work around this problem, each unixInodeInfo object
+** maintains a count of the number of pending locks on tha inode.
+** When an attempt is made to close an unixFile, if there are
+** other unixFile open on the same inode that are holding locks, the call
+** to close() the file descriptor is deferred until all of the locks clear.
+** The unixInodeInfo structure keeps a list of file descriptors that need to
+** be closed and that list is walked (and cleared) when the last lock
+** clears.
+**
+** Yet another problem:  LinuxThreads do not play well with posix locks.
+**
+** Many older versions of linux use the LinuxThreads library which is
+** not posix compliant.  Under LinuxThreads, a lock created by thread
+** A cannot be modified or overridden by a different thread B.
+** Only thread A can modify the lock.  Locking behavior is correct
+** if the appliation uses the newer Native Posix Thread Library (NPTL)
+** on linux - with NPTL a lock created by thread A can override locks
+** in thread B.  But there is no way to know at compile-time which
+** threading library is being used.  So there is no way to know at
+** compile-time whether or not thread A can override locks on thread B.
+** One has to do a run-time check to discover the behavior of the
+** current process.
+**
+** SQLite used to support LinuxThreads.  But support for LinuxThreads
+** was dropped beginning with version 3.7.0.  SQLite will still work with
+** LinuxThreads provided that (1) there is no more than one connection 
+** per database file in the same process and (2) database connections
+** do not move across threads.
+*/
+
+/*
+** An instance of the following structure serves as the key used
+** to locate a particular unixInodeInfo object.
+*/
+struct unixFileId {
+  dev_t dev;                  /* Device number */
+#if OS_VXWORKS
+  struct vxworksFileId *pId;  /* Unique file ID for vxworks. */
+#else
+  ino_t ino;                  /* Inode number */
+#endif
+};
+
+/*
+** An instance of the following structure is allocated for each open
+** inode.  Or, on LinuxThreads, there is one of these structures for
+** each inode opened by each thread.
+**
+** A single inode can have multiple file descriptors, so each unixFile
+** structure contains a pointer to an instance of this object and this
+** object keeps a count of the number of unixFile pointing to it.
+*/
+struct unixInodeInfo {
+  struct unixFileId fileId;       /* The lookup key */
+  int nShared;                    /* Number of SHARED locks held */
+  unsigned char eFileLock;        /* One of SHARED_LOCK, RESERVED_LOCK etc. */
+  unsigned char bProcessLock;     /* An exclusive process lock is held */
+  int nRef;                       /* Number of pointers to this structure */
+  unixShmNode *pShmNode;          /* Shared memory associated with this inode */
+  int nLock;                      /* Number of outstanding file locks */
+  UnixUnusedFd *pUnused;          /* Unused file descriptors to close */
+  unixInodeInfo *pNext;           /* List of all unixInodeInfo objects */
+  unixInodeInfo *pPrev;           /*    .... doubly linked */
+#if defined(SQLITE_ENABLE_LOCKING_STYLE)
+  unsigned long long sharedByte;  /* for AFP simulated shared lock */
+#endif
+#if OS_VXWORKS
+  sem_t *pSem;                    /* Named POSIX semaphore */
+  char aSemName[MAX_PATHNAME+2];  /* Name of that semaphore */
+#endif
+};
+
+/*
+** A lists of all unixInodeInfo objects.
+*/
+static unixInodeInfo *inodeList = 0;
+
+/*
+**
+** This function - unixLogError_x(), is only ever called via the macro
+** unixLogError().
+**
+** It is invoked after an error occurs in an OS function and errno has been
+** set. It logs a message using sqlite3_log() containing the current value of
+** errno and, if possible, the human-readable equivalent from strerror() or
+** strerror_r().
+**
+** The first argument passed to the macro should be the error code that
+** will be returned to SQLite (e.g. SQLITE_IOERR_DELETE, SQLITE_CANTOPEN). 
+** The two subsequent arguments should be the name of the OS function that
+** failed (e.g. "unlink", "open") and the the associated file-system path,
+** if any.
+*/
+#define unixLogError(a,b,c)     unixLogErrorAtLine(a,b,c,__LINE__)
+static int unixLogErrorAtLine(
+  int errcode,                    /* SQLite error code */
+  const char *zFunc,              /* Name of OS function that failed */
+  const char *zPath,              /* File path associated with error */
+  int iLine                       /* Source line number where error occurred */
+){
+  char *zErr;                     /* Message from strerror() or equivalent */
+  int iErrno = errno;             /* Saved syscall error number */
+
+  /* If this is not a threadsafe build (SQLITE_THREADSAFE==0), then use
+  ** the strerror() function to obtain the human-readable error message
+  ** equivalent to errno. Otherwise, use strerror_r().
+  */ 
+#if SQLITE_THREADSAFE && defined(HAVE_STRERROR_R)
+  char aErr[80];
+  memset(aErr, 0, sizeof(aErr));
+  zErr = aErr;
+
+  /* If STRERROR_R_CHAR_P (set by autoconf scripts) or __USE_GNU is defined,
+  ** assume that the system provides the the GNU version of strerror_r() that 
+  ** returns a pointer to a buffer containing the error message. That pointer 
+  ** may point to aErr[], or it may point to some static storage somewhere. 
+  ** Otherwise, assume that the system provides the POSIX version of 
+  ** strerror_r(), which always writes an error message into aErr[].
+  **
+  ** If the code incorrectly assumes that it is the POSIX version that is
+  ** available, the error message will often be an empty string. Not a
+  ** huge problem. Incorrectly concluding that the GNU version is available 
+  ** could lead to a segfault though.
+  */
+#if defined(STRERROR_R_CHAR_P) || defined(__USE_GNU)
+  zErr = 
+# endif
+  strerror_r(iErrno, aErr, sizeof(aErr)-1);
+
+#elif SQLITE_THREADSAFE
+  /* This is a threadsafe build, but strerror_r() is not available. */
+  zErr = "";
+#else
+  /* Non-threadsafe build, use strerror(). */
+  zErr = strerror(iErrno);
+#endif
+
+  assert( errcode!=SQLITE_OK );
+  if( zPath==0 ) zPath = "";
+  sqlite3_log(errcode,
+      "os_unix.c:%d: (%d) %s(%s) - %s",
+      iLine, iErrno, zFunc, zPath, zErr
+  );
+
+  return errcode;
+}
+
+/*
+** Close a file descriptor.
+**
+** We assume that close() almost always works, since it is only in a
+** very sick application or on a very sick platform that it might fail.
+** If it does fail, simply leak the file descriptor, but do log the
+** error.
+**
+** Note that it is not safe to retry close() after EINTR since the
+** file descriptor might have already been reused by another thread.
+** So we don't even try to recover from an EINTR.  Just log the error
+** and move on.
+*/
+static void robust_close(unixFile *pFile, int h, int lineno){
+  if( osClose(h) ){
+    unixLogErrorAtLine(SQLITE_IOERR_CLOSE, "close",
+                       pFile ? pFile->zPath : 0, lineno);
+  }
+}
+
+/*
+** Close all file descriptors accumuated in the unixInodeInfo->pUnused list.
+*/ 
+static void closePendingFds(unixFile *pFile){
+  unixInodeInfo *pInode = pFile->pInode;
+  UnixUnusedFd *p;
+  UnixUnusedFd *pNext;
+  for(p=pInode->pUnused; p; p=pNext){
+    pNext = p->pNext;
+    robust_close(pFile, p->fd, __LINE__);
+    sqlite3_free(p);
+  }
+  pInode->pUnused = 0;
+}
+
+/*
+** Release a unixInodeInfo structure previously allocated by findInodeInfo().
+**
+** The mutex entered using the unixEnterMutex() function must be held
+** when this function is called.
+*/
+static void releaseInodeInfo(unixFile *pFile){
+  unixInodeInfo *pInode = pFile->pInode;
+  assert( unixMutexHeld() );
+  if( ALWAYS(pInode) ){
+    pInode->nRef--;
+    if( pInode->nRef==0 ){
+      assert( pInode->pShmNode==0 );
+      closePendingFds(pFile);
+      if( pInode->pPrev ){
+        assert( pInode->pPrev->pNext==pInode );
+        pInode->pPrev->pNext = pInode->pNext;
+      }else{
+        assert( inodeList==pInode );
+        inodeList = pInode->pNext;
+      }
+      if( pInode->pNext ){
+        assert( pInode->pNext->pPrev==pInode );
+        pInode->pNext->pPrev = pInode->pPrev;
+      }
+      sqlite3_free(pInode);
+    }
+  }
+}
+
+/*
+** Given a file descriptor, locate the unixInodeInfo object that
+** describes that file descriptor.  Create a new one if necessary.  The
+** return value might be uninitialized if an error occurs.
+**
+** The mutex entered using the unixEnterMutex() function must be held
+** when this function is called.
+**
+** Return an appropriate error code.
+*/
+static int findInodeInfo(
+  unixFile *pFile,               /* Unix file with file desc used in the key */
+  unixInodeInfo **ppInode        /* Return the unixInodeInfo object here */
+){
+  int rc;                        /* System call return code */
+  int fd;                        /* The file descriptor for pFile */
+  struct unixFileId fileId;      /* Lookup key for the unixInodeInfo */
+  struct stat statbuf;           /* Low-level file information */
+  unixInodeInfo *pInode = 0;     /* Candidate unixInodeInfo object */
+
+  assert( unixMutexHeld() );
+
+  /* Get low-level information about the file that we can used to
+  ** create a unique name for the file.
+  */
+  fd = pFile->h;
+  rc = osFstat(fd, &statbuf);
+  if( rc!=0 ){
+    pFile->lastErrno = errno;
+#ifdef EOVERFLOW
+    if( pFile->lastErrno==EOVERFLOW ) return SQLITE_NOLFS;
+#endif
+    return SQLITE_IOERR;
+  }
+
+#ifdef __APPLE__
+  /* On OS X on an msdos filesystem, the inode number is reported
+  ** incorrectly for zero-size files.  See ticket #3260.  To work
+  ** around this problem (we consider it a bug in OS X, not SQLite)
+  ** we always increase the file size to 1 by writing a single byte
+  ** prior to accessing the inode number.  The one byte written is
+  ** an ASCII 'S' character which also happens to be the first byte
+  ** in the header of every SQLite database.  In this way, if there
+  ** is a race condition such that another thread has already populated
+  ** the first page of the database, no damage is done.
+  */
+  if( statbuf.st_size==0 && (pFile->fsFlags & SQLITE_FSFLAGS_IS_MSDOS)!=0 ){
+    do{ rc = osWrite(fd, "S", 1); }while( rc<0 && errno==EINTR );
+    if( rc!=1 ){
+      pFile->lastErrno = errno;
+      return SQLITE_IOERR;
+    }
+    rc = osFstat(fd, &statbuf);
+    if( rc!=0 ){
+      pFile->lastErrno = errno;
+      return SQLITE_IOERR;
+    }
+  }
+#endif
+
+  memset(&fileId, 0, sizeof(fileId));
+  fileId.dev = statbuf.st_dev;
+#if OS_VXWORKS
+  fileId.pId = pFile->pId;
+#else
+  fileId.ino = statbuf.st_ino;
+#endif
+  pInode = inodeList;
+  while( pInode && memcmp(&fileId, &pInode->fileId, sizeof(fileId)) ){
+    pInode = pInode->pNext;
+  }
+  if( pInode==0 ){
+    pInode = sqlite3_malloc( sizeof(*pInode) );
+    if( pInode==0 ){
+      return SQLITE_NOMEM;
+    }
+    memset(pInode, 0, sizeof(*pInode));
+    memcpy(&pInode->fileId, &fileId, sizeof(fileId));
+    pInode->nRef = 1;
+    pInode->pNext = inodeList;
+    pInode->pPrev = 0;
+    if( inodeList ) inodeList->pPrev = pInode;
+    inodeList = pInode;
+  }else{
+    pInode->nRef++;
+  }
+  *ppInode = pInode;
+  return SQLITE_OK;
+}
+
+
+/*
+** This routine checks if there is a RESERVED lock held on the specified
+** file by this or any other process. If such a lock is held, set *pResOut
+** to a non-zero value otherwise *pResOut is set to zero.  The return value
+** is set to SQLITE_OK unless an I/O error occurs during lock checking.
+*/
+static int unixCheckReservedLock(sqlite3_file *id, int *pResOut){
+  int rc = SQLITE_OK;
+  int reserved = 0;
+  unixFile *pFile = (unixFile*)id;
+
+  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );
+
+  assert( pFile );
+  unixEnterMutex(); /* Because pFile->pInode is shared across threads */
+
+  /* Check if a thread in this process holds such a lock */
+  if( pFile->pInode->eFileLock>SHARED_LOCK ){
+    reserved = 1;
+  }
+
+  /* Otherwise see if some other process holds it.
+  */
+#ifndef __DJGPP__
+  if( !reserved && !pFile->pInode->bProcessLock ){
+    struct flock lock;
+    lock.l_whence = SEEK_SET;
+    lock.l_start = RESERVED_BYTE;
+    lock.l_len = 1;
+    lock.l_type = F_WRLCK;
+    if( osFcntl(pFile->h, F_GETLK, &lock) ){
+      rc = SQLITE_IOERR_CHECKRESERVEDLOCK;
+      pFile->lastErrno = errno;
+    } else if( lock.l_type!=F_UNLCK ){
+      reserved = 1;
+    }
+  }
+#endif
+  
+  unixLeaveMutex();
+  OSTRACE(("TEST WR-LOCK %d %d %d (unix)\n", pFile->h, rc, reserved));
+
+  *pResOut = reserved;
+  return rc;
+}
+
+/*
+** Attempt to set a system-lock on the file pFile.  The lock is 
+** described by pLock.
+**
+** If the pFile was opened read/write from unix-excl, then the only lock
+** ever obtained is an exclusive lock, and it is obtained exactly once
+** the first time any lock is attempted.  All subsequent system locking
+** operations become no-ops.  Locking operations still happen internally,
+** in order to coordinate access between separate database connections
+** within this process, but all of that is handled in memory and the
+** operating system does not participate.
+**
+** This function is a pass-through to fcntl(F_SETLK) if pFile is using
+** any VFS other than "unix-excl" or if pFile is opened on "unix-excl"
+** and is read-only.
+**
+** Zero is returned if the call completes successfully, or -1 if a call
+** to fcntl() fails. In this case, errno is set appropriately (by fcntl()).
+*/
+static int unixFileLock(unixFile *pFile, struct flock *pLock){
+  int rc;
+  unixInodeInfo *pInode = pFile->pInode;
+  assert( unixMutexHeld() );
+  assert( pInode!=0 );
+  if( ((pFile->ctrlFlags & UNIXFILE_EXCL)!=0 || pInode->bProcessLock)
+   && ((pFile->ctrlFlags & UNIXFILE_RDONLY)==0)
+  ){
+    if( pInode->bProcessLock==0 ){
+      struct flock lock;
+      assert( pInode->nLock==0 );
+      lock.l_whence = SEEK_SET;
+      lock.l_start = SHARED_FIRST;
+      lock.l_len = SHARED_SIZE;
+      lock.l_type = F_WRLCK;
+      rc = osFcntl(pFile->h, F_SETLK, &lock);
+      if( rc<0 ) return rc;
+      pInode->bProcessLock = 1;
+      pInode->nLock++;
+    }else{
+      rc = 0;
+    }
+  }else{
+    rc = osFcntl(pFile->h, F_SETLK, pLock);
+  }
+  return rc;
+}
+
+/*
+** Lock the file with the lock specified by parameter eFileLock - one
+** of the following:
+**
+**     (1) SHARED_LOCK
+**     (2) RESERVED_LOCK
+**     (3) PENDING_LOCK
+**     (4) EXCLUSIVE_LOCK
+**
+** Sometimes when requesting one lock state, additional lock states
+** are inserted in between.  The locking might fail on one of the later
+** transitions leaving the lock state different from what it started but
+** still short of its goal.  The following chart shows the allowed
+** transitions and the inserted intermediate states:
+**
+**    UNLOCKED -> SHARED
+**    SHARED -> RESERVED
+**    SHARED -> (PENDING) -> EXCLUSIVE
+**    RESERVED -> (PENDING) -> EXCLUSIVE
+**    PENDING -> EXCLUSIVE
+**
+** This routine will only increase a lock.  Use the sqlite3OsUnlock()
+** routine to lower a locking level.
+*/
+static int unixLock(sqlite3_file *id, int eFileLock){
+  /* The following describes the implementation of the various locks and
+  ** lock transitions in terms of the POSIX advisory shared and exclusive
+  ** lock primitives (called read-locks and write-locks below, to avoid
+  ** confusion with SQLite lock names). The algorithms are complicated
+  ** slightly in order to be compatible with windows systems simultaneously
+  ** accessing the same database file, in case that is ever required.
+  **
+  ** Symbols defined in os.h indentify the 'pending byte' and the 'reserved
+  ** byte', each single bytes at well known offsets, and the 'shared byte
+  ** range', a range of 510 bytes at a well known offset.
+  **
+  ** To obtain a SHARED lock, a read-lock is obtained on the 'pending
+  ** byte'.  If this is successful, a random byte from the 'shared byte
+  ** range' is read-locked and the lock on the 'pending byte' released.
+  **
+  ** A process may only obtain a RESERVED lock after it has a SHARED lock.
+  ** A RESERVED lock is implemented by grabbing a write-lock on the
+  ** 'reserved byte'. 
+  **
+  ** A process may only obtain a PENDING lock after it has obtained a
+  ** SHARED lock. A PENDING lock is implemented by obtaining a write-lock
+  ** on the 'pending byte'. This ensures that no new SHARED locks can be
+  ** obtained, but existing SHARED locks are allowed to persist. A process
+  ** does not have to obtain a RESERVED lock on the way to a PENDING lock.
+  ** This property is used by the algorithm for rolling back a journal file
+  ** after a crash.
+  **
+  ** An EXCLUSIVE lock, obtained after a PENDING lock is held, is
+  ** implemented by obtaining a write-lock on the entire 'shared byte
+  ** range'. Since all other locks require a read-lock on one of the bytes
+  ** within this range, this ensures that no other locks are held on the
+  ** database. 
+  **
+  ** The reason a single byte cannot be used instead of the 'shared byte
+  ** range' is that some versions of windows do not support read-locks. By
+  ** locking a random byte from a range, concurrent SHARED locks may exist
+  ** even if the locking primitive used is always a write-lock.
+  */
+  int rc = SQLITE_OK;
+  unixFile *pFile = (unixFile*)id;
+  unixInodeInfo *pInode = pFile->pInode;
+  struct flock lock;
+  int tErrno = 0;
+
+  assert( pFile );
+  OSTRACE(("LOCK    %d %s was %s(%s,%d) pid=%d (unix)\n", pFile->h,
+      azFileLock(eFileLock), azFileLock(pFile->eFileLock),
+      azFileLock(pInode->eFileLock), pInode->nShared , getpid()));
+
+  /* If there is already a lock of this type or more restrictive on the
+  ** unixFile, do nothing. Don't use the end_lock: exit path, as
+  ** unixEnterMutex() hasn't been called yet.
+  */
+  if( pFile->eFileLock>=eFileLock ){
+    OSTRACE(("LOCK    %d %s ok (already held) (unix)\n", pFile->h,
+            azFileLock(eFileLock)));
+    return SQLITE_OK;
+  }
+
+  /* Make sure the locking sequence is correct.
+  **  (1) We never move from unlocked to anything higher than shared lock.
+  **  (2) SQLite never explicitly requests a pendig lock.
+  **  (3) A shared lock is always held when a reserve lock is requested.
+  */
+  assert( pFile->eFileLock!=NO_LOCK || eFileLock==SHARED_LOCK );
+  assert( eFileLock!=PENDING_LOCK );
+  assert( eFileLock!=RESERVED_LOCK || pFile->eFileLock==SHARED_LOCK );
+
+  /* This mutex is needed because pFile->pInode is shared across threads
+  */
+  unixEnterMutex();
+  pInode = pFile->pInode;
+
+  /* If some thread using this PID has a lock via a different unixFile*
+  ** handle that precludes the requested lock, return BUSY.
+  */
+  if( (pFile->eFileLock!=pInode->eFileLock && 
+          (pInode->eFileLock>=PENDING_LOCK || eFileLock>SHARED_LOCK))
+  ){
+    rc = SQLITE_BUSY;
+    goto end_lock;
+  }
+
+  /* If a SHARED lock is requested, and some thread using this PID already
+  ** has a SHARED or RESERVED lock, then increment reference counts and
+  ** return SQLITE_OK.
+  */
+  if( eFileLock==SHARED_LOCK && 
+      (pInode->eFileLock==SHARED_LOCK || pInode->eFileLock==RESERVED_LOCK) ){
+    assert( eFileLock==SHARED_LOCK );
+    assert( pFile->eFileLock==0 );
+    assert( pInode->nShared>0 );
+    pFile->eFileLock = SHARED_LOCK;
+    pInode->nShared++;
+    pInode->nLock++;
+    goto end_lock;
+  }
+
+
+  /* A PENDING lock is needed before acquiring a SHARED lock and before
+  ** acquiring an EXCLUSIVE lock.  For the SHARED lock, the PENDING will
+  ** be released.
+  */
+  lock.l_len = 1L;
+  lock.l_whence = SEEK_SET;
+  if( eFileLock==SHARED_LOCK 
+      || (eFileLock==EXCLUSIVE_LOCK && pFile->eFileLock<PENDING_LOCK)
+  ){
+    lock.l_type = (eFileLock==SHARED_LOCK?F_RDLCK:F_WRLCK);
+    lock.l_start = PENDING_BYTE;
+    if( unixFileLock(pFile, &lock) ){
+      tErrno = errno;
+      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
+      if( rc!=SQLITE_BUSY ){
+        pFile->lastErrno = tErrno;
+      }
+      goto end_lock;
+    }
+  }
+
+
+  /* If control gets to this point, then actually go ahead and make
+  ** operating system calls for the specified lock.
+  */
+  if( eFileLock==SHARED_LOCK ){
+    assert( pInode->nShared==0 );
+    assert( pInode->eFileLock==0 );
+    assert( rc==SQLITE_OK );
+
+    /* Now get the read-lock */
+    lock.l_start = SHARED_FIRST;
+    lock.l_len = SHARED_SIZE;
+    if( unixFileLock(pFile, &lock) ){
+      tErrno = errno;
+      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
+    }
+
+    /* Drop the temporary PENDING lock */
+    lock.l_start = PENDING_BYTE;
+    lock.l_len = 1L;
+    lock.l_type = F_UNLCK;
+    if( unixFileLock(pFile, &lock) && rc==SQLITE_OK ){
+      /* This could happen with a network mount */
+      tErrno = errno;
+      rc = SQLITE_IOERR_UNLOCK; 
+    }
+
+    if( rc ){
+      if( rc!=SQLITE_BUSY ){
+        pFile->lastErrno = tErrno;
+      }
+      goto end_lock;
+    }else{
+      pFile->eFileLock = SHARED_LOCK;
+      pInode->nLock++;
+      pInode->nShared = 1;
+    }
+  }else if( eFileLock==EXCLUSIVE_LOCK && pInode->nShared>1 ){
+    /* We are trying for an exclusive lock but another thread in this
+    ** same process is still holding a shared lock. */
+    rc = SQLITE_BUSY;
+  }else{
+    /* The request was for a RESERVED or EXCLUSIVE lock.  It is
+    ** assumed that there is a SHARED or greater lock on the file
+    ** already.
+    */
+    assert( 0!=pFile->eFileLock );
+    lock.l_type = F_WRLCK;
+
+    assert( eFileLock==RESERVED_LOCK || eFileLock==EXCLUSIVE_LOCK );
+    if( eFileLock==RESERVED_LOCK ){
+      lock.l_start = RESERVED_BYTE;
+      lock.l_len = 1L;
+    }else{
+      lock.l_start = SHARED_FIRST;
+      lock.l_len = SHARED_SIZE;
+    }
+
+    if( unixFileLock(pFile, &lock) ){
+      tErrno = errno;
+      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
+      if( rc!=SQLITE_BUSY ){
+        pFile->lastErrno = tErrno;
+      }
+    }
+  }
+  
+
+#ifndef NDEBUG
+  /* Set up the transaction-counter change checking flags when
+  ** transitioning from a SHARED to a RESERVED lock.  The change
+  ** from SHARED to RESERVED marks the beginning of a normal
+  ** write operation (not a hot journal rollback).
+  */
+  if( rc==SQLITE_OK
+   && pFile->eFileLock<=SHARED_LOCK
+   && eFileLock==RESERVED_LOCK
+  ){
+    pFile->transCntrChng = 0;
+    pFile->dbUpdate = 0;
+    pFile->inNormalWrite = 1;
+  }
+#endif
+
+
+  if( rc==SQLITE_OK ){
+    pFile->eFileLock = eFileLock;
+    pInode->eFileLock = eFileLock;
+  }else if( eFileLock==EXCLUSIVE_LOCK ){
+    pFile->eFileLock = PENDING_LOCK;
+    pInode->eFileLock = PENDING_LOCK;
+  }
+
+end_lock:
+  unixLeaveMutex();
+  OSTRACE(("LOCK    %d %s %s (unix)\n", pFile->h, azFileLock(eFileLock), 
+      rc==SQLITE_OK ? "ok" : "failed"));
+  return rc;
+}
+
+/*
+** Add the file descriptor used by file handle pFile to the corresponding
+** pUnused list.
+*/
+static void setPendingFd(unixFile *pFile){
+  unixInodeInfo *pInode = pFile->pInode;
+  UnixUnusedFd *p = pFile->pUnused;
+  p->pNext = pInode->pUnused;
+  pInode->pUnused = p;
+  pFile->h = -1;
+  pFile->pUnused = 0;
+}
+
+/*
+** Lower the locking level on file descriptor pFile to eFileLock.  eFileLock
+** must be either NO_LOCK or SHARED_LOCK.
+**
+** If the locking level of the file descriptor is already at or below
+** the requested locking level, this routine is a no-op.
+** 
+** If handleNFSUnlock is true, then on downgrading an EXCLUSIVE_LOCK to SHARED
+** the byte range is divided into 2 parts and the first part is unlocked then
+** set to a read lock, then the other part is simply unlocked.  This works 
+** around a bug in BSD NFS lockd (also seen on MacOSX 10.3+) that fails to 
+** remove the write lock on a region when a read lock is set.
+*/
+static int posixUnlock(sqlite3_file *id, int eFileLock, int handleNFSUnlock){
+  unixFile *pFile = (unixFile*)id;
+  unixInodeInfo *pInode;
+  struct flock lock;
+  int rc = SQLITE_OK;
+  int h;
+
+  assert( pFile );
+  OSTRACE(("UNLOCK  %d %d was %d(%d,%d) pid=%d (unix)\n", pFile->h, eFileLock,
+      pFile->eFileLock, pFile->pInode->eFileLock, pFile->pInode->nShared,
+      getpid()));
+
+  assert( eFileLock<=SHARED_LOCK );
+  if( pFile->eFileLock<=eFileLock ){
+    return SQLITE_OK;
+  }
+  unixEnterMutex();
+  h = pFile->h;
+  pInode = pFile->pInode;
+  assert( pInode->nShared!=0 );
+  if( pFile->eFileLock>SHARED_LOCK ){
+    assert( pInode->eFileLock==pFile->eFileLock );
+    SimulateIOErrorBenign(1);
+    SimulateIOError( h=(-1) )
+    SimulateIOErrorBenign(0);
+
+#ifndef NDEBUG
+    /* When reducing a lock such that other processes can start
+    ** reading the database file again, make sure that the
+    ** transaction counter was updated if any part of the database
+    ** file changed.  If the transaction counter is not updated,
+    ** other connections to the same file might not realize that
+    ** the file has changed and hence might not know to flush their
+    ** cache.  The use of a stale cache can lead to database corruption.
+    */
+#if 0
+    assert( pFile->inNormalWrite==0
+         || pFile->dbUpdate==0
+         || pFile->transCntrChng==1 );
+#endif
+    pFile->inNormalWrite = 0;
+#endif
+
+    /* downgrading to a shared lock on NFS involves clearing the write lock
+    ** before establishing the readlock - to avoid a race condition we downgrade
+    ** the lock in 2 blocks, so that part of the range will be covered by a 
+    ** write lock until the rest is covered by a read lock:
+    **  1:   [WWWWW]
+    **  2:   [....W]
+    **  3:   [RRRRW]
+    **  4:   [RRRR.]
+    */
+    if( eFileLock==SHARED_LOCK ){
+
+#if !defined(__APPLE__) || !SQLITE_ENABLE_LOCKING_STYLE
+      (void)handleNFSUnlock;
+      assert( handleNFSUnlock==0 );
+#endif
+#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
+      if( handleNFSUnlock ){
+        int tErrno;               /* Error code from system call errors */
+        off_t divSize = SHARED_SIZE - 1;
+        
+        lock.l_type = F_UNLCK;
+        lock.l_whence = SEEK_SET;
+        lock.l_start = SHARED_FIRST;
+        lock.l_len = divSize;
+        if( unixFileLock(pFile, &lock)==(-1) ){
+          tErrno = errno;
+          rc = SQLITE_IOERR_UNLOCK;
+          if( IS_LOCK_ERROR(rc) ){
+            pFile->lastErrno = tErrno;
+          }
+          goto end_unlock;
+        }
+        lock.l_type = F_RDLCK;
+        lock.l_whence = SEEK_SET;
+        lock.l_start = SHARED_FIRST;
+        lock.l_len = divSize;
+        if( unixFileLock(pFile, &lock)==(-1) ){
+          tErrno = errno;
+          rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_RDLOCK);
+          if( IS_LOCK_ERROR(rc) ){
+            pFile->lastErrno = tErrno;
+          }
+          goto end_unlock;
+        }
+        lock.l_type = F_UNLCK;
+        lock.l_whence = SEEK_SET;
+        lock.l_start = SHARED_FIRST+divSize;
+        lock.l_len = SHARED_SIZE-divSize;
+        if( unixFileLock(pFile, &lock)==(-1) ){
+          tErrno = errno;
+          rc = SQLITE_IOERR_UNLOCK;
+          if( IS_LOCK_ERROR(rc) ){
+            pFile->lastErrno = tErrno;
+          }
+          goto end_unlock;
+        }
+      }else
+#endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */
+      {
+        lock.l_type = F_RDLCK;
+        lock.l_whence = SEEK_SET;
+        lock.l_start = SHARED_FIRST;
+        lock.l_len = SHARED_SIZE;
+        if( unixFileLock(pFile, &lock) ){
+          /* In theory, the call to unixFileLock() cannot fail because another
+          ** process is holding an incompatible lock. If it does, this 
+          ** indicates that the other process is not following the locking
+          ** protocol. If this happens, return SQLITE_IOERR_RDLOCK. Returning
+          ** SQLITE_BUSY would confuse the upper layer (in practice it causes 
+          ** an assert to fail). */ 
+          rc = SQLITE_IOERR_RDLOCK;
+          pFile->lastErrno = errno;
+          goto end_unlock;
+        }
+      }
+    }
+    lock.l_type = F_UNLCK;
+    lock.l_whence = SEEK_SET;
+    lock.l_start = PENDING_BYTE;
+    lock.l_len = 2L;  assert( PENDING_BYTE+1==RESERVED_BYTE );
+    if( unixFileLock(pFile, &lock)==0 ){
+      pInode->eFileLock = SHARED_LOCK;
+    }else{
+      rc = SQLITE_IOERR_UNLOCK;
+      pFile->lastErrno = errno;
+      goto end_unlock;
+    }
+  }
+  if( eFileLock==NO_LOCK ){
+    /* Decrement the shared lock counter.  Release the lock using an
+    ** OS call only when all threads in this same process have released
+    ** the lock.
+    */
+    pInode->nShared--;
+    if( pInode->nShared==0 ){
+      lock.l_type = F_UNLCK;
+      lock.l_whence = SEEK_SET;
+      lock.l_start = lock.l_len = 0L;
+      SimulateIOErrorBenign(1);
+      SimulateIOError( h=(-1) )
+      SimulateIOErrorBenign(0);
+      if( unixFileLock(pFile, &lock)==0 ){
+        pInode->eFileLock = NO_LOCK;
+      }else{
+        rc = SQLITE_IOERR_UNLOCK;
+	pFile->lastErrno = errno;
+        pInode->eFileLock = NO_LOCK;
+        pFile->eFileLock = NO_LOCK;
+      }
+    }
+
+    /* Decrement the count of locks against this same file.  When the
+    ** count reaches zero, close any other file descriptors whose close
+    ** was deferred because of outstanding locks.
+    */
+    pInode->nLock--;
+    assert( pInode->nLock>=0 );
+    if( pInode->nLock==0 ){
+      closePendingFds(pFile);
+    }
+  }
+	
+end_unlock:
+  unixLeaveMutex();
+  if( rc==SQLITE_OK ) pFile->eFileLock = eFileLock;
+  return rc;
+}
+
+/*
+** Lower the locking level on file descriptor pFile to eFileLock.  eFileLock
+** must be either NO_LOCK or SHARED_LOCK.
+**
+** If the locking level of the file descriptor is already at or below
+** the requested locking level, this routine is a no-op.
+*/
+static int unixUnlock(sqlite3_file *id, int eFileLock){
+  return posixUnlock(id, eFileLock, 0);
+}
+
+/*
+** This function performs the parts of the "close file" operation 
+** common to all locking schemes. It closes the directory and file
+** handles, if they are valid, and sets all fields of the unixFile
+** structure to 0.
+**
+** It is *not* necessary to hold the mutex when this routine is called,
+** even on VxWorks.  A mutex will be acquired on VxWorks by the
+** vxworksReleaseFileId() routine.
+*/
+static int closeUnixFile(sqlite3_file *id){
+  unixFile *pFile = (unixFile*)id;
+  if( pFile->dirfd>=0 ){
+    robust_close(pFile, pFile->dirfd, __LINE__);
+    pFile->dirfd=-1;
+  }
+  if( pFile->h>=0 ){
+    robust_close(pFile, pFile->h, __LINE__);
+    pFile->h = -1;
+  }
+#if OS_VXWORKS
+  if( pFile->pId ){
+    if( pFile->isDelete ){
+      unlink(pFile->pId->zCanonicalName);
+    }
+    vxworksReleaseFileId(pFile->pId);
+    pFile->pId = 0;
+  }
+#endif
+  OSTRACE(("CLOSE   %-3d\n", pFile->h));
+  OpenCounter(-1);
+  sqlite3_free(pFile->pUnused);
+  memset(pFile, 0, sizeof(unixFile));
+  return SQLITE_OK;
+}
+
+/*
+** Close a file.
+*/
+static int unixClose(sqlite3_file *id){
+  int rc = SQLITE_OK;
+  unixFile *pFile = (unixFile *)id;
+  unixUnlock(id, NO_LOCK);
+  unixEnterMutex();
+
+  /* unixFile.pInode is always valid here. Otherwise, a different close
+  ** routine (e.g. nolockClose()) would be called instead.
+  */
+  assert( pFile->pInode->nLock>0 || pFile->pInode->bProcessLock==0 );
+  if( ALWAYS(pFile->pInode) && pFile->pInode->nLock ){
+    /* If there are outstanding locks, do not actually close the file just
+    ** yet because that would clear those locks.  Instead, add the file
+    ** descriptor to pInode->pUnused list.  It will be automatically closed 
+    ** when the last lock is cleared.
+    */
+    setPendingFd(pFile);
+  }
+  releaseInodeInfo(pFile);
+  rc = closeUnixFile(id);
+  unixLeaveMutex();
+  return rc;
+}
+
+/************** End of the posix advisory lock implementation *****************
+******************************************************************************/
+
+/******************************************************************************
+****************************** No-op Locking **********************************
+**
+** Of the various locking implementations available, this is by far the
+** simplest:  locking is ignored.  No attempt is made to lock the database
+** file for reading or writing.
+**
+** This locking mode is appropriate for use on read-only databases
+** (ex: databases that are burned into CD-ROM, for example.)  It can
+** also be used if the application employs some external mechanism to
+** prevent simultaneous access of the same database by two or more
+** database connections.  But there is a serious risk of database
+** corruption if this locking mode is used in situations where multiple
+** database connections are accessing the same database file at the same
+** time and one or more of those connections are writing.
+*/
+
+static int nolockCheckReservedLock(sqlite3_file *NotUsed, int *pResOut){
+  UNUSED_PARAMETER(NotUsed);
+  *pResOut = 0;
+  return SQLITE_OK;
+}
+static int nolockLock(sqlite3_file *NotUsed, int NotUsed2){
+  UNUSED_PARAMETER2(NotUsed, NotUsed2);
+  return SQLITE_OK;
+}
+static int nolockUnlock(sqlite3_file *NotUsed, int NotUsed2){
+  UNUSED_PARAMETER2(NotUsed, NotUsed2);
+  return SQLITE_OK;
+}
+
+/*
+** Close the file.
+*/
+static int nolockClose(sqlite3_file *id) {
+  return closeUnixFile(id);
+}
+
+/******************* End of the no-op lock implementation *********************
+******************************************************************************/
+
+/******************************************************************************
+************************* Begin dot-file Locking ******************************
+**
+** The dotfile locking implementation uses the existance of separate lock
+** files in order to control access to the database.  This works on just
+** about every filesystem imaginable.  But there are serious downsides:
+**
+**    (1)  There is zero concurrency.  A single reader blocks all other
+**         connections from reading or writing the database.
+**
+**    (2)  An application crash or power loss can leave stale lock files
+**         sitting around that need to be cleared manually.
+**
+** Nevertheless, a dotlock is an appropriate locking mode for use if no
+** other locking strategy is available.
+**
+** Dotfile locking works by creating a file in the same directory as the
+** database and with the same name but with a ".lock" extension added.
+** The existance of a lock file implies an EXCLUSIVE lock.  All other lock
+** types (SHARED, RESERVED, PENDING) are mapped into EXCLUSIVE.
+*/
+
+/*
+** The file suffix added to the data base filename in order to create the
+** lock file.
+*/
+#define DOTLOCK_SUFFIX ".lock"
+
+/*
+** This routine checks if there is a RESERVED lock held on the specified
+** file by this or any other process. If such a lock is held, set *pResOut
+** to a non-zero value otherwise *pResOut is set to zero.  The return value
+** is set to SQLITE_OK unless an I/O error occurs during lock checking.
+**
+** In dotfile locking, either a lock exists or it does not.  So in this
+** variation of CheckReservedLock(), *pResOut is set to true if any lock
+** is held on the file and false if the file is unlocked.
+*/
+static int dotlockCheckReservedLock(sqlite3_file *id, int *pResOut) {
+  int rc = SQLITE_OK;
+  int reserved = 0;
+  unixFile *pFile = (unixFile*)id;
+
+  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );
+  
+  assert( pFile );
+
+  /* Check if a thread in this process holds such a lock */
+  if( pFile->eFileLock>SHARED_LOCK ){
+    /* Either this connection or some other connection in the same process
+    ** holds a lock on the file.  No need to check further. */
+    reserved = 1;
+  }else{
+    /* The lock is held if and only if the lockfile exists */
+    const char *zLockFile = (const char*)pFile->lockingContext;
+    reserved = osAccess(zLockFile, 0)==0;
+  }
+  OSTRACE(("TEST WR-LOCK %d %d %d (dotlock)\n", pFile->h, rc, reserved));
+  *pResOut = reserved;
+  return rc;
+}
+
+/*
+** Lock the file with the lock specified by parameter eFileLock - one
+** of the following:
+**
+**     (1) SHARED_LOCK
+**     (2) RESERVED_LOCK
+**     (3) PENDING_LOCK
+**     (4) EXCLUSIVE_LOCK
+**
+** Sometimes when requesting one lock state, additional lock states
+** are inserted in between.  The locking might fail on one of the later
+** transitions leaving the lock state different from what it started but
+** still short of its goal.  The following chart shows the allowed
+** transitions and the inserted intermediate states:
+**
+**    UNLOCKED -> SHARED
+**    SHARED -> RESERVED
+**    SHARED -> (PENDING) -> EXCLUSIVE
+**    RESERVED -> (PENDING) -> EXCLUSIVE
+**    PENDING -> EXCLUSIVE
+**
+** This routine will only increase a lock.  Use the sqlite3OsUnlock()
+** routine to lower a locking level.
+**
+** With dotfile locking, we really only support state (4): EXCLUSIVE.
+** But we track the other locking levels internally.
+*/
+static int dotlockLock(sqlite3_file *id, int eFileLock) {
+  unixFile *pFile = (unixFile*)id;
+  int fd;
+  char *zLockFile = (char *)pFile->lockingContext;
+  int rc = SQLITE_OK;
+
+
+  /* If we have any lock, then the lock file already exists.  All we have
+  ** to do is adjust our internal record of the lock level.
+  */
+  if( pFile->eFileLock > NO_LOCK ){
+    pFile->eFileLock = eFileLock;
+#if !OS_VXWORKS
+    /* Always update the timestamp on the old file */
+    utimes(zLockFile, NULL);
+#endif
+    return SQLITE_OK;
+  }
+  
+  /* grab an exclusive lock */
+  fd = robust_open(zLockFile,O_RDONLY|O_CREAT|O_EXCL,0600);
+  if( fd<0 ){
+    /* failed to open/create the file, someone else may have stolen the lock */
+    int tErrno = errno;
+    if( EEXIST == tErrno ){
+      rc = SQLITE_BUSY;
+    } else {
+      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
+      if( IS_LOCK_ERROR(rc) ){
+        pFile->lastErrno = tErrno;
+      }
+    }
+    return rc;
+  } 
+  robust_close(pFile, fd, __LINE__);
+  
+  /* got it, set the type and return ok */
+  pFile->eFileLock = eFileLock;
+  return rc;
+}
+
+/*
+** Lower the locking level on file descriptor pFile to eFileLock.  eFileLock
+** must be either NO_LOCK or SHARED_LOCK.
+**
+** If the locking level of the file descriptor is already at or below
+** the requested locking level, this routine is a no-op.
+**
+** When the locking level reaches NO_LOCK, delete the lock file.
+*/
+static int dotlockUnlock(sqlite3_file *id, int eFileLock) {
+  unixFile *pFile = (unixFile*)id;
+  char *zLockFile = (char *)pFile->lockingContext;
+
+  assert( pFile );
+  OSTRACE(("UNLOCK  %d %d was %d pid=%d (dotlock)\n", pFile->h, eFileLock,
+	   pFile->eFileLock, getpid()));
+  assert( eFileLock<=SHARED_LOCK );
+  
+  /* no-op if possible */
+  if( pFile->eFileLock==eFileLock ){
+    return SQLITE_OK;
+  }
+
+  /* To downgrade to shared, simply update our internal notion of the
+  ** lock state.  No need to mess with the file on disk.
+  */
+  if( eFileLock==SHARED_LOCK ){
+    pFile->eFileLock = SHARED_LOCK;
+    return SQLITE_OK;
+  }
+  
+  /* To fully unlock the database, delete the lock file */
+  assert( eFileLock==NO_LOCK );
+  if( unlink(zLockFile) ){
+    int rc = 0;
+    int tErrno = errno;
+    if( ENOENT != tErrno ){
+      rc = SQLITE_IOERR_UNLOCK;
+    }
+    if( IS_LOCK_ERROR(rc) ){
+      pFile->lastErrno = tErrno;
+    }
+    return rc; 
+  }
+  pFile->eFileLock = NO_LOCK;
+  return SQLITE_OK;
+}
+
+/*
+** Close a file.  Make sure the lock has been released before closing.
+*/
+static int dotlockClose(sqlite3_file *id) {
+  int rc;
+  if( id ){
+    unixFile *pFile = (unixFile*)id;
+    dotlockUnlock(id, NO_LOCK);
+    sqlite3_free(pFile->lockingContext);
+  }
+  rc = closeUnixFile(id);
+  return rc;
+}
+/****************** End of the dot-file lock implementation *******************
+******************************************************************************/
+
+/******************************************************************************
+************************** Begin flock Locking ********************************
+**
+** Use the flock() system call to do file locking.
+**
+** flock() locking is like dot-file locking in that the various
+** fine-grain locking levels supported by SQLite are collapsed into
+** a single exclusive lock.  In other words, SHARED, RESERVED, and
+** PENDING locks are the same thing as an EXCLUSIVE lock.  SQLite
+** still works when you do this, but concurrency is reduced since
+** only a single process can be reading the database at a time.
+**
+** Omit this section if SQLITE_ENABLE_LOCKING_STYLE is turned off or if
+** compiling for VXWORKS.
+*/
+#if SQLITE_ENABLE_LOCKING_STYLE && !OS_VXWORKS
+
+/*
+** Retry flock() calls that fail with EINTR
+*/
+#ifdef EINTR
+static int robust_flock(int fd, int op){
+  int rc;
+  do{ rc = flock(fd,op); }while( rc<0 && errno==EINTR );
+  return rc;
+}
+#else
+# define robust_flock(a,b) flock(a,b)
+#endif
+     
+
+/*
+** This routine checks if there is a RESERVED lock held on the specified
+** file by this or any other process. If such a lock is held, set *pResOut
+** to a non-zero value otherwise *pResOut is set to zero.  The return value
+** is set to SQLITE_OK unless an I/O error occurs during lock checking.
+*/
+static int flockCheckReservedLock(sqlite3_file *id, int *pResOut){
+  int rc = SQLITE_OK;
+  int reserved = 0;
+  unixFile *pFile = (unixFile*)id;
+  
+  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );
+  
+  assert( pFile );
+  
+  /* Check if a thread in this process holds such a lock */
+  if( pFile->eFileLock>SHARED_LOCK ){
+    reserved = 1;
+  }
+  
+  /* Otherwise see if some other process holds it. */
+  if( !reserved ){
+    /* attempt to get the lock */
+    int lrc = robust_flock(pFile->h, LOCK_EX | LOCK_NB);
+    if( !lrc ){
+      /* got the lock, unlock it */
+      lrc = robust_flock(pFile->h, LOCK_UN);
+      if ( lrc ) {
+        int tErrno = errno;
+        /* unlock failed with an error */
+        lrc = SQLITE_IOERR_UNLOCK; 
+        if( IS_LOCK_ERROR(lrc) ){
+          pFile->lastErrno = tErrno;
+          rc = lrc;
+        }
+      }
+    } else {
+      int tErrno = errno;
+      reserved = 1;
+      /* someone else might have it reserved */
+      lrc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK); 
+      if( IS_LOCK_ERROR(lrc) ){
+        pFile->lastErrno = tErrno;
+        rc = lrc;
+      }
+    }
+  }
+  OSTRACE(("TEST WR-LOCK %d %d %d (flock)\n", pFile->h, rc, reserved));
+
+#ifdef SQLITE_IGNORE_FLOCK_LOCK_ERRORS
+  if( (rc & SQLITE_IOERR) == SQLITE_IOERR ){
+    rc = SQLITE_OK;
+    reserved=1;
+  }
+#endif /* SQLITE_IGNORE_FLOCK_LOCK_ERRORS */
+  *pResOut = reserved;
+  return rc;
+}
+
+/*
+** Lock the file with the lock specified by parameter eFileLock - one
+** of the following:
+**
+**     (1) SHARED_LOCK
+**     (2) RESERVED_LOCK
+**     (3) PENDING_LOCK
+**     (4) EXCLUSIVE_LOCK
+**
+** Sometimes when requesting one lock state, additional lock states
+** are inserted in between.  The locking might fail on one of the later
+** transitions leaving the lock state different from what it started but
+** still short of its goal.  The following chart shows the allowed
+** transitions and the inserted intermediate states:
+**
+**    UNLOCKED -> SHARED
+**    SHARED -> RESERVED
+**    SHARED -> (PENDING) -> EXCLUSIVE
+**    RESERVED -> (PENDING) -> EXCLUSIVE
+**    PENDING -> EXCLUSIVE
+**
+** flock() only really support EXCLUSIVE locks.  We track intermediate
+** lock states in the sqlite3_file structure, but all locks SHARED or
+** above are really EXCLUSIVE locks and exclude all other processes from
+** access the file.
+**
+** This routine will only increase a lock.  Use the sqlite3OsUnlock()
+** routine to lower a locking level.
+*/
+static int flockLock(sqlite3_file *id, int eFileLock) {
+  int rc = SQLITE_OK;
+  unixFile *pFile = (unixFile*)id;
+
+  assert( pFile );
+
+  /* if we already have a lock, it is exclusive.  
+  ** Just adjust level and punt on outta here. */
+  if (pFile->eFileLock > NO_LOCK) {
+    pFile->eFileLock = eFileLock;
+    return SQLITE_OK;
+  }
+  
+  /* grab an exclusive lock */
+  
+  if (robust_flock(pFile->h, LOCK_EX | LOCK_NB)) {
+    int tErrno = errno;
+    /* didn't get, must be busy */
+    rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
+    if( IS_LOCK_ERROR(rc) ){
+      pFile->lastErrno = tErrno;
+    }
+  } else {
+    /* got it, set the type and return ok */
+    pFile->eFileLock = eFileLock;
+  }
+  OSTRACE(("LOCK    %d %s %s (flock)\n", pFile->h, azFileLock(eFileLock), 
+           rc==SQLITE_OK ? "ok" : "failed"));
+#ifdef SQLITE_IGNORE_FLOCK_LOCK_ERRORS
+  if( (rc & SQLITE_IOERR) == SQLITE_IOERR ){
+    rc = SQLITE_BUSY;
+  }
+#endif /* SQLITE_IGNORE_FLOCK_LOCK_ERRORS */
+  return rc;
+}
+
+
+/*
+** Lower the locking level on file descriptor pFile to eFileLock.  eFileLock
+** must be either NO_LOCK or SHARED_LOCK.
+**
+** If the locking level of the file descriptor is already at or below
+** the requested locking level, this routine is a no-op.
+*/
+static int flockUnlock(sqlite3_file *id, int eFileLock) {
+  unixFile *pFile = (unixFile*)id;
+  
+  assert( pFile );
+  OSTRACE(("UNLOCK  %d %d was %d pid=%d (flock)\n", pFile->h, eFileLock,
+           pFile->eFileLock, getpid()));
+  assert( eFileLock<=SHARED_LOCK );
+  
+  /* no-op if possible */
+  if( pFile->eFileLock==eFileLock ){
+    return SQLITE_OK;
+  }
+  
+  /* shared can just be set because we always have an exclusive */
+  if (eFileLock==SHARED_LOCK) {
+    pFile->eFileLock = eFileLock;
+    return SQLITE_OK;
+  }
+  
+  /* no, really, unlock. */
+  if( robust_flock(pFile->h, LOCK_UN) ){
+#ifdef SQLITE_IGNORE_FLOCK_LOCK_ERRORS
+    return SQLITE_OK;
+#endif /* SQLITE_IGNORE_FLOCK_LOCK_ERRORS */
+    return SQLITE_IOERR_UNLOCK;
+  }else{
+    pFile->eFileLock = NO_LOCK;
+    return SQLITE_OK;
+  }
+}
+
+/*
+** Close a file.
+*/
+static int flockClose(sqlite3_file *id) {
+  if( id ){
+    flockUnlock(id, NO_LOCK);
+  }
+  return closeUnixFile(id);
+}
+
+#endif /* SQLITE_ENABLE_LOCKING_STYLE && !OS_VXWORK */
+
+/******************* End of the flock lock implementation *********************
+******************************************************************************/
+
+/******************************************************************************
+************************ Begin Named Semaphore Locking ************************
+**
+** Named semaphore locking is only supported on VxWorks.
+**
+** Semaphore locking is like dot-lock and flock in that it really only
+** supports EXCLUSIVE locking.  Only a single process can read or write
+** the database file at a time.  This reduces potential concurrency, but
+** makes the lock implementation much easier.
+*/
+#if OS_VXWORKS
+
+/*
+** This routine checks if there is a RESERVED lock held on the specified
+** file by this or any other process. If such a lock is held, set *pResOut
+** to a non-zero value otherwise *pResOut is set to zero.  The return value
+** is set to SQLITE_OK unless an I/O error occurs during lock checking.
+*/
+static int semCheckReservedLock(sqlite3_file *id, int *pResOut) {
+  int rc = SQLITE_OK;
+  int reserved = 0;
+  unixFile *pFile = (unixFile*)id;
+
+  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );
+  
+  assert( pFile );
+
+  /* Check if a thread in this process holds such a lock */
+  if( pFile->eFileLock>SHARED_LOCK ){
+    reserved = 1;
+  }
+  
+  /* Otherwise see if some other process holds it. */
+  if( !reserved ){
+    sem_t *pSem = pFile->pInode->pSem;
+    struct stat statBuf;
+
+    if( sem_trywait(pSem)==-1 ){
+      int tErrno = errno;
+      if( EAGAIN != tErrno ){
+        rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_CHECKRESERVEDLOCK);
+        pFile->lastErrno = tErrno;
+      } else {
+        /* someone else has the lock when we are in NO_LOCK */
+        reserved = (pFile->eFileLock < SHARED_LOCK);
+      }
+    }else{
+      /* we could have it if we want it */
+      sem_post(pSem);
+    }
+  }
+  OSTRACE(("TEST WR-LOCK %d %d %d (sem)\n", pFile->h, rc, reserved));
+
+  *pResOut = reserved;
+  return rc;
+}
+
+/*
+** Lock the file with the lock specified by parameter eFileLock - one
+** of the following:
+**
+**     (1) SHARED_LOCK
+**     (2) RESERVED_LOCK
+**     (3) PENDING_LOCK
+**     (4) EXCLUSIVE_LOCK
+**
+** Sometimes when requesting one lock state, additional lock states
+** are inserted in between.  The locking might fail on one of the later
+** transitions leaving the lock state different from what it started but
+** still short of its goal.  The following chart shows the allowed
+** transitions and the inserted intermediate states:
+**
+**    UNLOCKED -> SHARED
+**    SHARED -> RESERVED
+**    SHARED -> (PENDING) -> EXCLUSIVE
+**    RESERVED -> (PENDING) -> EXCLUSIVE
+**    PENDING -> EXCLUSIVE
+**
+** Semaphore locks only really support EXCLUSIVE locks.  We track intermediate
+** lock states in the sqlite3_file structure, but all locks SHARED or
+** above are really EXCLUSIVE locks and exclude all other processes from
+** access the file.
+**
+** This routine will only increase a lock.  Use the sqlite3OsUnlock()
+** routine to lower a locking level.
+*/
+static int semLock(sqlite3_file *id, int eFileLock) {
+  unixFile *pFile = (unixFile*)id;
+  int fd;
+  sem_t *pSem = pFile->pInode->pSem;
+  int rc = SQLITE_OK;
+
+  /* if we already have a lock, it is exclusive.  
+  ** Just adjust level and punt on outta here. */
+  if (pFile->eFileLock > NO_LOCK) {
+    pFile->eFileLock = eFileLock;
+    rc = SQLITE_OK;
+    goto sem_end_lock;
+  }
+  
+  /* lock semaphore now but bail out when already locked. */
+  if( sem_trywait(pSem)==-1 ){
+    rc = SQLITE_BUSY;
+    goto sem_end_lock;
+  }
+
+  /* got it, set the type and return ok */
+  pFile->eFileLock = eFileLock;
+
+ sem_end_lock:
+  return rc;
+}
+
+/*
+** Lower the locking level on file descriptor pFile to eFileLock.  eFileLock
+** must be either NO_LOCK or SHARED_LOCK.
+**
+** If the locking level of the file descriptor is already at or below
+** the requested locking level, this routine is a no-op.
+*/
+static int semUnlock(sqlite3_file *id, int eFileLock) {
+  unixFile *pFile = (unixFile*)id;
+  sem_t *pSem = pFile->pInode->pSem;
+
+  assert( pFile );
+  assert( pSem );
+  OSTRACE(("UNLOCK  %d %d was %d pid=%d (sem)\n", pFile->h, eFileLock,
+	   pFile->eFileLock, getpid()));
+  assert( eFileLock<=SHARED_LOCK );
+  
+  /* no-op if possible */
+  if( pFile->eFileLock==eFileLock ){
+    return SQLITE_OK;
+  }
+  
+  /* shared can just be set because we always have an exclusive */
+  if (eFileLock==SHARED_LOCK) {
+    pFile->eFileLock = eFileLock;
+    return SQLITE_OK;
+  }
+  
+  /* no, really unlock. */
+  if ( sem_post(pSem)==-1 ) {
+    int rc, tErrno = errno;
+    rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
+    if( IS_LOCK_ERROR(rc) ){
+      pFile->lastErrno = tErrno;
+    }
+    return rc; 
+  }
+  pFile->eFileLock = NO_LOCK;
+  return SQLITE_OK;
+}
+
+/*
+ ** Close a file.
+ */
+static int semClose(sqlite3_file *id) {
+  if( id ){
+    unixFile *pFile = (unixFile*)id;
+    semUnlock(id, NO_LOCK);
+    assert( pFile );
+    unixEnterMutex();
+    releaseInodeInfo(pFile);
+    unixLeaveMutex();
+    closeUnixFile(id);
+  }
+  return SQLITE_OK;
+}
+
+#endif /* OS_VXWORKS */
+/*
+** Named semaphore locking is only available on VxWorks.
+**
+*************** End of the named semaphore lock implementation ****************
+******************************************************************************/
+
+
+/******************************************************************************
+*************************** Begin AFP Locking *********************************
+**
+** AFP is the Apple Filing Protocol.  AFP is a network filesystem found
+** on Apple Macintosh computers - both OS9 and OSX.
+**
+** Third-party implementations of AFP are available.  But this code here
+** only works on OSX.
+*/
+
+#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
+/*
+** The afpLockingContext structure contains all afp lock specific state
+*/
+typedef struct afpLockingContext afpLockingContext;
+struct afpLockingContext {
+  int reserved;
+  const char *dbPath;             /* Name of the open file */
+};
+
+struct ByteRangeLockPB2
+{
+  unsigned long long offset;        /* offset to first byte to lock */
+  unsigned long long length;        /* nbr of bytes to lock */
+  unsigned long long retRangeStart; /* nbr of 1st byte locked if successful */
+  unsigned char unLockFlag;         /* 1 = unlock, 0 = lock */
+  unsigned char startEndFlag;       /* 1=rel to end of fork, 0=rel to start */
+  int fd;                           /* file desc to assoc this lock with */
+};
+
+#define afpfsByteRangeLock2FSCTL        _IOWR('z', 23, struct ByteRangeLockPB2)
+
+/*
+** This is a utility for setting or clearing a bit-range lock on an
+** AFP filesystem.
+** 
+** Return SQLITE_OK on success, SQLITE_BUSY on failure.
+*/
+static int afpSetLock(
+  const char *path,              /* Name of the file to be locked or unlocked */
+  unixFile *pFile,               /* Open file descriptor on path */
+  unsigned long long offset,     /* First byte to be locked */
+  unsigned long long length,     /* Number of bytes to lock */
+  int setLockFlag                /* True to set lock.  False to clear lock */
+){
+  struct ByteRangeLockPB2 pb;
+  int err;
+  
+  pb.unLockFlag = setLockFlag ? 0 : 1;
+  pb.startEndFlag = 0;
+  pb.offset = offset;
+  pb.length = length; 
+  pb.fd = pFile->h;
+  
+  OSTRACE(("AFPSETLOCK [%s] for %d%s in range %llx:%llx\n", 
+    (setLockFlag?"ON":"OFF"), pFile->h, (pb.fd==-1?"[testval-1]":""),
+    offset, length));
+  err = fsctl(path, afpfsByteRangeLock2FSCTL, &pb, 0);
+  if ( err==-1 ) {
+    int rc;
+    int tErrno = errno;
+    OSTRACE(("AFPSETLOCK failed to fsctl() '%s' %d %s\n",
+             path, tErrno, strerror(tErrno)));
+#ifdef SQLITE_IGNORE_AFP_LOCK_ERRORS
+    rc = SQLITE_BUSY;
+#else
+    rc = sqliteErrorFromPosixError(tErrno,
+                    setLockFlag ? SQLITE_IOERR_LOCK : SQLITE_IOERR_UNLOCK);
+#endif /* SQLITE_IGNORE_AFP_LOCK_ERRORS */
+    if( IS_LOCK_ERROR(rc) ){
+      pFile->lastErrno = tErrno;
+    }
+    return rc;
+  } else {
+    return SQLITE_OK;
+  }
+}
+
+/*
+** This routine checks if there is a RESERVED lock held on the specified
+** file by this or any other process. If such a lock is held, set *pResOut
+** to a non-zero value otherwise *pResOut is set to zero.  The return value
+** is set to SQLITE_OK unless an I/O error occurs during lock checking.
+*/
+static int afpCheckReservedLock(sqlite3_file *id, int *pResOut){
+  int rc = SQLITE_OK;
+  int reserved = 0;
+  unixFile *pFile = (unixFile*)id;
+  
+  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );
+  
+  assert( pFile );
+  afpLockingContext *context = (afpLockingContext *) pFile->lockingContext;
+  if( context->reserved ){
+    *pResOut = 1;
+    return SQLITE_OK;
+  }
+  unixEnterMutex(); /* Because pFile->pInode is shared across threads */
+  
+  /* Check if a thread in this process holds such a lock */
+  if( pFile->pInode->eFileLock>SHARED_LOCK ){
+    reserved = 1;
+  }
+  
+  /* Otherwise see if some other process holds it.
+   */
+  if( !reserved ){
+    /* lock the RESERVED byte */
+    int lrc = afpSetLock(context->dbPath, pFile, RESERVED_BYTE, 1,1);  
+    if( SQLITE_OK==lrc ){
+      /* if we succeeded in taking the reserved lock, unlock it to restore
+      ** the original state */
+      lrc = afpSetLock(context->dbPath, pFile, RESERVED_BYTE, 1, 0);
+    } else {
+      /* if we failed to get the lock then someone else must have it */
+      reserved = 1;
+    }
+    if( IS_LOCK_ERROR(lrc) ){
+      rc=lrc;
+    }
+  }
+  
+  unixLeaveMutex();
+  OSTRACE(("TEST WR-LOCK %d %d %d (afp)\n", pFile->h, rc, reserved));
+  
+  *pResOut = reserved;
+  return rc;
+}
+
+/*
+** Lock the file with the lock specified by parameter eFileLock - one
+** of the following:
+**
+**     (1) SHARED_LOCK
+**     (2) RESERVED_LOCK
+**     (3) PENDING_LOCK
+**     (4) EXCLUSIVE_LOCK
+**
+** Sometimes when requesting one lock state, additional lock states
+** are inserted in between.  The locking might fail on one of the later
+** transitions leaving the lock state different from what it started but
+** still short of its goal.  The following chart shows the allowed
+** transitions and the inserted intermediate states:
+**
+**    UNLOCKED -> SHARED
+**    SHARED -> RESERVED
+**    SHARED -> (PENDING) -> EXCLUSIVE
+**    RESERVED -> (PENDING) -> EXCLUSIVE
+**    PENDING -> EXCLUSIVE
+**
+** This routine will only increase a lock.  Use the sqlite3OsUnlock()
+** routine to lower a locking level.
+*/
+static int afpLock(sqlite3_file *id, int eFileLock){
+  int rc = SQLITE_OK;
+  unixFile *pFile = (unixFile*)id;
+  unixInodeInfo *pInode = pFile->pInode;
+  afpLockingContext *context = (afpLockingContext *) pFile->lockingContext;
+  
+  assert( pFile );
+  OSTRACE(("LOCK    %d %s was %s(%s,%d) pid=%d (afp)\n", pFile->h,
+           azFileLock(eFileLock), azFileLock(pFile->eFileLock),
+           azFileLock(pInode->eFileLock), pInode->nShared , getpid()));
+
+  /* If there is already a lock of this type or more restrictive on the
+  ** unixFile, do nothing. Don't use the afp_end_lock: exit path, as
+  ** unixEnterMutex() hasn't been called yet.
+  */
+  if( pFile->eFileLock>=eFileLock ){
+    OSTRACE(("LOCK    %d %s ok (already held) (afp)\n", pFile->h,
+           azFileLock(eFileLock)));
+    return SQLITE_OK;
+  }
+
+  /* Make sure the locking sequence is correct
+  **  (1) We never move from unlocked to anything higher than shared lock.
+  **  (2) SQLite never explicitly requests a pendig lock.
+  **  (3) A shared lock is always held when a reserve lock is requested.
+  */
+  assert( pFile->eFileLock!=NO_LOCK || eFileLock==SHARED_LOCK );
+  assert( eFileLock!=PENDING_LOCK );
+  assert( eFileLock!=RESERVED_LOCK || pFile->eFileLock==SHARED_LOCK );
+  
+  /* This mutex is needed because pFile->pInode is shared across threads
+  */
+  unixEnterMutex();
+  pInode = pFile->pInode;
+
+  /* If some thread using this PID has a lock via a different unixFile*
+  ** handle that precludes the requested lock, return BUSY.
+  */
+  if( (pFile->eFileLock!=pInode->eFileLock && 
+       (pInode->eFileLock>=PENDING_LOCK || eFileLock>SHARED_LOCK))
+     ){
+    rc = SQLITE_BUSY;
+    goto afp_end_lock;
+  }
+  
+  /* If a SHARED lock is requested, and some thread using this PID already
+  ** has a SHARED or RESERVED lock, then increment reference counts and
+  ** return SQLITE_OK.
+  */
+  if( eFileLock==SHARED_LOCK && 
+     (pInode->eFileLock==SHARED_LOCK || pInode->eFileLock==RESERVED_LOCK) ){
+    assert( eFileLock==SHARED_LOCK );
+    assert( pFile->eFileLock==0 );
+    assert( pInode->nShared>0 );
+    pFile->eFileLock = SHARED_LOCK;
+    pInode->nShared++;
+    pInode->nLock++;
+    goto afp_end_lock;
+  }
+    
+  /* A PENDING lock is needed before acquiring a SHARED lock and before
+  ** acquiring an EXCLUSIVE lock.  For the SHARED lock, the PENDING will
+  ** be released.
+  */
+  if( eFileLock==SHARED_LOCK 
+      || (eFileLock==EXCLUSIVE_LOCK && pFile->eFileLock<PENDING_LOCK)
+  ){
+    int failed;
+    failed = afpSetLock(context->dbPath, pFile, PENDING_BYTE, 1, 1);
+    if (failed) {
+      rc = failed;
+      goto afp_end_lock;
+    }
+  }
+  
+  /* If control gets to this point, then actually go ahead and make
+  ** operating system calls for the specified lock.
+  */
+  if( eFileLock==SHARED_LOCK ){
+    int lrc1, lrc2, lrc1Errno;
+    long lk, mask;
+    
+    assert( pInode->nShared==0 );
+    assert( pInode->eFileLock==0 );
+        
+    mask = (sizeof(long)==8) ? LARGEST_INT64 : 0x7fffffff;
+    /* Now get the read-lock SHARED_LOCK */
+    /* note that the quality of the randomness doesn't matter that much */
+    lk = random(); 
+    pInode->sharedByte = (lk & mask)%(SHARED_SIZE - 1);
+    lrc1 = afpSetLock(context->dbPath, pFile, 
+          SHARED_FIRST+pInode->sharedByte, 1, 1);
+    if( IS_LOCK_ERROR(lrc1) ){
+      lrc1Errno = pFile->lastErrno;
+    }
+    /* Drop the temporary PENDING lock */
+    lrc2 = afpSetLock(context->dbPath, pFile, PENDING_BYTE, 1, 0);
+    
+    if( IS_LOCK_ERROR(lrc1) ) {
+      pFile->lastErrno = lrc1Errno;
+      rc = lrc1;
+      goto afp_end_lock;
+    } else if( IS_LOCK_ERROR(lrc2) ){
+      rc = lrc2;
+      goto afp_end_lock;
+    } else if( lrc1 != SQLITE_OK ) {
+      rc = lrc1;
+    } else {
+      pFile->eFileLock = SHARED_LOCK;
+      pInode->nLock++;
+      pInode->nShared = 1;
+    }
+  }else if( eFileLock==EXCLUSIVE_LOCK && pInode->nShared>1 ){
+    /* We are trying for an exclusive lock but another thread in this
+     ** same process is still holding a shared lock. */
+    rc = SQLITE_BUSY;
+  }else{
+    /* The request was for a RESERVED or EXCLUSIVE lock.  It is
+    ** assumed that there is a SHARED or greater lock on the file
+    ** already.
+    */
+    int failed = 0;
+    assert( 0!=pFile->eFileLock );
+    if (eFileLock >= RESERVED_LOCK && pFile->eFileLock < RESERVED_LOCK) {
+        /* Acquire a RESERVED lock */
+        failed = afpSetLock(context->dbPath, pFile, RESERVED_BYTE, 1,1);
+      if( !failed ){
+        context->reserved = 1;
+      }
+    }
+    if (!failed && eFileLock == EXCLUSIVE_LOCK) {
+      /* Acquire an EXCLUSIVE lock */
+        
+      /* Remove the shared lock before trying the range.  we'll need to 
+      ** reestablish the shared lock if we can't get the  afpUnlock
+      */
+      if( !(failed = afpSetLock(context->dbPath, pFile, SHARED_FIRST +
+                         pInode->sharedByte, 1, 0)) ){
+        int failed2 = SQLITE_OK;
+        /* now attemmpt to get the exclusive lock range */
+        failed = afpSetLock(context->dbPath, pFile, SHARED_FIRST, 
+                               SHARED_SIZE, 1);
+        if( failed && (failed2 = afpSetLock(context->dbPath, pFile, 
+                       SHARED_FIRST + pInode->sharedByte, 1, 1)) ){
+          /* Can't reestablish the shared lock.  Sqlite can't deal, this is
+          ** a critical I/O error
+          */
+          rc = ((failed & SQLITE_IOERR) == SQLITE_IOERR) ? failed2 : 
+               SQLITE_IOERR_LOCK;
+          goto afp_end_lock;
+        } 
+      }else{
+        rc = failed; 
+      }
+    }
+    if( failed ){
+      rc = failed;
+    }
+  }
+  
+  if( rc==SQLITE_OK ){
+    pFile->eFileLock = eFileLock;
+    pInode->eFileLock = eFileLock;
+  }else if( eFileLock==EXCLUSIVE_LOCK ){
+    pFile->eFileLock = PENDING_LOCK;
+    pInode->eFileLock = PENDING_LOCK;
+  }
+  
+afp_end_lock:
+  unixLeaveMutex();
+  OSTRACE(("LOCK    %d %s %s (afp)\n", pFile->h, azFileLock(eFileLock), 
+         rc==SQLITE_OK ? "ok" : "failed"));
+  return rc;
+}
+
+/*
+** Lower the locking level on file descriptor pFile to eFileLock.  eFileLock
+** must be either NO_LOCK or SHARED_LOCK.
+**
+** If the locking level of the file descriptor is already at or below
+** the requested locking level, this routine is a no-op.
+*/
+static int afpUnlock(sqlite3_file *id, int eFileLock) {
+  int rc = SQLITE_OK;
+  unixFile *pFile = (unixFile*)id;
+  unixInodeInfo *pInode;
+  afpLockingContext *context = (afpLockingContext *) pFile->lockingContext;
+  int skipShared = 0;
+#ifdef SQLITE_TEST
+  int h = pFile->h;
+#endif
+
+  assert( pFile );
+  OSTRACE(("UNLOCK  %d %d was %d(%d,%d) pid=%d (afp)\n", pFile->h, eFileLock,
+           pFile->eFileLock, pFile->pInode->eFileLock, pFile->pInode->nShared,
+           getpid()));
+
+  assert( eFileLock<=SHARED_LOCK );
+  if( pFile->eFileLock<=eFileLock ){
+    return SQLITE_OK;
+  }
+  unixEnterMutex();
+  pInode = pFile->pInode;
+  assert( pInode->nShared!=0 );
+  if( pFile->eFileLock>SHARED_LOCK ){
+    assert( pInode->eFileLock==pFile->eFileLock );
+    SimulateIOErrorBenign(1);
+    SimulateIOError( h=(-1) )
+    SimulateIOErrorBenign(0);
+    
+#ifndef NDEBUG
+    /* When reducing a lock such that other processes can start
+    ** reading the database file again, make sure that the
+    ** transaction counter was updated if any part of the database
+    ** file changed.  If the transaction counter is not updated,
+    ** other connections to the same file might not realize that
+    ** the file has changed and hence might not know to flush their
+    ** cache.  The use of a stale cache can lead to database corruption.
+    */
+    assert( pFile->inNormalWrite==0
+           || pFile->dbUpdate==0
+           || pFile->transCntrChng==1 );
+    pFile->inNormalWrite = 0;
+#endif
+    
+    if( pFile->eFileLock==EXCLUSIVE_LOCK ){
+      rc = afpSetLock(context->dbPath, pFile, SHARED_FIRST, SHARED_SIZE, 0);
+      if( rc==SQLITE_OK && (eFileLock==SHARED_LOCK || pInode->nShared>1) ){
+        /* only re-establish the shared lock if necessary */
+        int sharedLockByte = SHARED_FIRST+pInode->sharedByte;
+        rc = afpSetLock(context->dbPath, pFile, sharedLockByte, 1, 1);
+      } else {
+        skipShared = 1;
+      }
+    }
+    if( rc==SQLITE_OK && pFile->eFileLock>=PENDING_LOCK ){
+      rc = afpSetLock(context->dbPath, pFile, PENDING_BYTE, 1, 0);
+    } 
+    if( rc==SQLITE_OK && pFile->eFileLock>=RESERVED_LOCK && context->reserved ){
+      rc = afpSetLock(context->dbPath, pFile, RESERVED_BYTE, 1, 0);
+      if( !rc ){ 
+        context->reserved = 0; 
+      }
+    }
+    if( rc==SQLITE_OK && (eFileLock==SHARED_LOCK || pInode->nShared>1)){
+      pInode->eFileLock = SHARED_LOCK;
+    }
+  }
+  if( rc==SQLITE_OK && eFileLock==NO_LOCK ){
+
+    /* Decrement the shared lock counter.  Release the lock using an
+    ** OS call only when all threads in this same process have released
+    ** the lock.
+    */
+    unsigned long long sharedLockByte = SHARED_FIRST+pInode->sharedByte;
+    pInode->nShared--;
+    if( pInode->nShared==0 ){
+      SimulateIOErrorBenign(1);
+      SimulateIOError( h=(-1) )
+      SimulateIOErrorBenign(0);
+      if( !skipShared ){
+        rc = afpSetLock(context->dbPath, pFile, sharedLockByte, 1, 0);
+      }
+      if( !rc ){
+        pInode->eFileLock = NO_LOCK;
+        pFile->eFileLock = NO_LOCK;
+      }
+    }
+    if( rc==SQLITE_OK ){
+      pInode->nLock--;
+      assert( pInode->nLock>=0 );
+      if( pInode->nLock==0 ){
+        closePendingFds(pFile);
+      }
+    }
+  }
+  
+  unixLeaveMutex();
+  if( rc==SQLITE_OK ) pFile->eFileLock = eFileLock;
+  return rc;
+}
+
+/*
+** Close a file & cleanup AFP specific locking context 
+*/
+static int afpClose(sqlite3_file *id) {
+  int rc = SQLITE_OK;
+  if( id ){
+    unixFile *pFile = (unixFile*)id;
+    afpUnlock(id, NO_LOCK);
+    unixEnterMutex();
+    if( pFile->pInode && pFile->pInode->nLock ){
+      /* If there are outstanding locks, do not actually close the file just
+      ** yet because that would clear those locks.  Instead, add the file
+      ** descriptor to pInode->aPending.  It will be automatically closed when
+      ** the last lock is cleared.
+      */
+      setPendingFd(pFile);
+    }
+    releaseInodeInfo(pFile);
+    sqlite3_free(pFile->lockingContext);
+    rc = closeUnixFile(id);
+    unixLeaveMutex();
+  }
+  return rc;
+}
+
+#endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */
+/*
+** The code above is the AFP lock implementation.  The code is specific
+** to MacOSX and does not work on other unix platforms.  No alternative
+** is available.  If you don't compile for a mac, then the "unix-afp"
+** VFS is not available.
+**
+********************* End of the AFP lock implementation **********************
+******************************************************************************/
+
+/******************************************************************************
+*************************** Begin NFS Locking ********************************/
+
+#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
+/*
+ ** Lower the locking level on file descriptor pFile to eFileLock.  eFileLock
+ ** must be either NO_LOCK or SHARED_LOCK.
+ **
+ ** If the locking level of the file descriptor is already at or below
+ ** the requested locking level, this routine is a no-op.
+ */
+static int nfsUnlock(sqlite3_file *id, int eFileLock){
+  return posixUnlock(id, eFileLock, 1);
+}
+
+#endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */
+/*
+** The code above is the NFS lock implementation.  The code is specific
+** to MacOSX and does not work on other unix platforms.  No alternative
+** is available.  
+**
+********************* End of the NFS lock implementation **********************
+******************************************************************************/
+
+/******************************************************************************
+**************** Non-locking sqlite3_file methods *****************************
+**
+** The next division contains implementations for all methods of the 
+** sqlite3_file object other than the locking methods.  The locking
+** methods were defined in divisions above (one locking method per
+** division).  Those methods that are common to all locking modes
+** are gather together into this division.
+*/
+
+/*
+** Seek to the offset passed as the second argument, then read cnt 
+** bytes into pBuf. Return the number of bytes actually read.
+**
+** NB:  If you define USE_PREAD or USE_PREAD64, then it might also
+** be necessary to define _XOPEN_SOURCE to be 500.  This varies from
+** one system to another.  Since SQLite does not define USE_PREAD
+** any any form by default, we will not attempt to define _XOPEN_SOURCE.
+** See tickets #2741 and #2681.
+**
+** To avoid stomping the errno value on a failed read the lastErrno value
+** is set before returning.
+*/
+static int seekAndRead(unixFile *id, sqlite3_int64 offset, void *pBuf, int cnt){
+  int got;
+#if (!defined(USE_PREAD) && !defined(USE_PREAD64))
+  i64 newOffset;
+#endif
+  TIMER_START;
+#if defined(USE_PREAD)
+  do{ got = osPread(id->h, pBuf, cnt, offset); }while( got<0 && errno==EINTR );
+  SimulateIOError( got = -1 );
+#elif defined(USE_PREAD64)
+  do{ got = osPread64(id->h, pBuf, cnt, offset); }while( got<0 && errno==EINTR);
+  SimulateIOError( got = -1 );
+#else
+  newOffset = lseek(id->h, offset, SEEK_SET);
+  SimulateIOError( newOffset-- );
+  if( newOffset!=offset ){
+    if( newOffset == -1 ){
+      ((unixFile*)id)->lastErrno = errno;
+    }else{
+      ((unixFile*)id)->lastErrno = 0;			
+    }
+    return -1;
+  }
+  do{ got = osRead(id->h, pBuf, cnt); }while( got<0 && errno==EINTR );
+#endif
+  TIMER_END;
+  if( got<0 ){
+    ((unixFile*)id)->lastErrno = errno;
+  }
+  OSTRACE(("READ    %-3d %5d %7lld %llu\n", id->h, got, offset, TIMER_ELAPSED));
+  return got;
+}
+
+/*
+** Read data from a file into a buffer.  Return SQLITE_OK if all
+** bytes were read successfully and SQLITE_IOERR if anything goes
+** wrong.
+*/
+static int unixRead(
+  sqlite3_file *id, 
+  void *pBuf, 
+  int amt,
+  sqlite3_int64 offset
+){
+  unixFile *pFile = (unixFile *)id;
+  int got;
+  assert( id );
+
+  /* If this is a database file (not a journal, master-journal or temp
+  ** file), the bytes in the locking range should never be read or written. */
+#if 0
+  assert( pFile->pUnused==0
+       || offset>=PENDING_BYTE+512
+       || offset+amt<=PENDING_BYTE 
+  );
+#endif
+
+  got = seekAndRead(pFile, offset, pBuf, amt);
+  if( got==amt ){
+    return SQLITE_OK;
+  }else if( got<0 ){
+    /* lastErrno set by seekAndRead */
+    return SQLITE_IOERR_READ;
+  }else{
+    pFile->lastErrno = 0; /* not a system error */
+    /* Unread parts of the buffer must be zero-filled */
+    memset(&((char*)pBuf)[got], 0, amt-got);
+    return SQLITE_IOERR_SHORT_READ;
+  }
+}
+
+/*
+** Seek to the offset in id->offset then read cnt bytes into pBuf.
+** Return the number of bytes actually read.  Update the offset.
+**
+** To avoid stomping the errno value on a failed write the lastErrno value
+** is set before returning.
+*/
+static int seekAndWrite(unixFile *id, i64 offset, const void *pBuf, int cnt){
+  int got;
+#if (!defined(USE_PREAD) && !defined(USE_PREAD64))
+  i64 newOffset;
+#endif
+  TIMER_START;
+#if defined(USE_PREAD)
+  do{ got = osPwrite(id->h, pBuf, cnt, offset); }while( got<0 && errno==EINTR );
+#elif defined(USE_PREAD64)
+  do{ got = osPwrite64(id->h, pBuf, cnt, offset);}while( got<0 && errno==EINTR);
+#else
+  newOffset = lseek(id->h, offset, SEEK_SET);
+  SimulateIOError( newOffset-- );
+  if( newOffset!=offset ){
+    if( newOffset == -1 ){
+      ((unixFile*)id)->lastErrno = errno;
+    }else{
+      ((unixFile*)id)->lastErrno = 0;			
+    }
+    return -1;
+  }
+  do{ got = osWrite(id->h, pBuf, cnt); }while( got<0 && errno==EINTR );
+#endif
+  TIMER_END;
+  if( got<0 ){
+    ((unixFile*)id)->lastErrno = errno;
+  }
+
+  OSTRACE(("WRITE   %-3d %5d %7lld %llu\n", id->h, got, offset, TIMER_ELAPSED));
+  return got;
+}
+
+
+/*
+** Write data from a buffer into a file.  Return SQLITE_OK on success
+** or some other error code on failure.
+*/
+static int unixWrite(
+  sqlite3_file *id, 
+  const void *pBuf, 
+  int amt,
+  sqlite3_int64 offset 
+){
+  unixFile *pFile = (unixFile*)id;
+  int wrote = 0;
+  assert( id );
+  assert( amt>0 );
+
+  /* If this is a database file (not a journal, master-journal or temp
+  ** file), the bytes in the locking range should never be read or written. */
+#if 0
+  assert( pFile->pUnused==0
+       || offset>=PENDING_BYTE+512
+       || offset+amt<=PENDING_BYTE 
+  );
+#endif
+
+#ifndef NDEBUG
+  /* If we are doing a normal write to a database file (as opposed to
+  ** doing a hot-journal rollback or a write to some file other than a
+  ** normal database file) then record the fact that the database
+  ** has changed.  If the transaction counter is modified, record that
+  ** fact too.
+  */
+  if( pFile->inNormalWrite ){
+    pFile->dbUpdate = 1;  /* The database has been modified */
+    if( offset<=24 && offset+amt>=27 ){
+      int rc;
+      char oldCntr[4];
+      SimulateIOErrorBenign(1);
+      rc = seekAndRead(pFile, 24, oldCntr, 4);
+      SimulateIOErrorBenign(0);
+      if( rc!=4 || memcmp(oldCntr, &((char*)pBuf)[24-offset], 4)!=0 ){
+        pFile->transCntrChng = 1;  /* The transaction counter has changed */
+      }
+    }
+  }
+#endif
+
+  while( amt>0 && (wrote = seekAndWrite(pFile, offset, pBuf, amt))>0 ){
+    amt -= wrote;
+    offset += wrote;
+    pBuf = &((char*)pBuf)[wrote];
+  }
+  SimulateIOError(( wrote=(-1), amt=1 ));
+  SimulateDiskfullError(( wrote=0, amt=1 ));
+
+  if( amt>0 ){
+    if( wrote<0 ){
+      /* lastErrno set by seekAndWrite */
+      return SQLITE_IOERR_WRITE;
+    }else{
+      pFile->lastErrno = 0; /* not a system error */
+      return SQLITE_FULL;
+    }
+  }
+
+  return SQLITE_OK;
+}
+
+#ifdef SQLITE_TEST
+/*
+** Count the number of fullsyncs and normal syncs.  This is used to test
+** that syncs and fullsyncs are occurring at the right times.
+*/
+SQLITE_API int sqlite3_sync_count = 0;
+SQLITE_API int sqlite3_fullsync_count = 0;
+#endif
+
+/*
+** We do not trust systems to provide a working fdatasync().  Some do.
+** Others do no.  To be safe, we will stick with the (slower) fsync().
+** If you know that your system does support fdatasync() correctly,
+** then simply compile with -Dfdatasync=fdatasync
+*/
+#if !defined(fdatasync) && !defined(__linux__)
+# define fdatasync fsync
+#endif
+
+/*
+** Define HAVE_FULLFSYNC to 0 or 1 depending on whether or not
+** the F_FULLFSYNC macro is defined.  F_FULLFSYNC is currently
+** only available on Mac OS X.  But that could change.
+*/
+#ifdef F_FULLFSYNC
+# define HAVE_FULLFSYNC 1
+#else
+# define HAVE_FULLFSYNC 0
+#endif
+
+
+/*
+** The fsync() system call does not work as advertised on many
+** unix systems.  The following procedure is an attempt to make
+** it work better.
+**
+** The SQLITE_NO_SYNC macro disables all fsync()s.  This is useful
+** for testing when we want to run through the test suite quickly.
+** You are strongly advised *not* to deploy with SQLITE_NO_SYNC
+** enabled, however, since with SQLITE_NO_SYNC enabled, an OS crash
+** or power failure will likely corrupt the database file.
+**
+** SQLite sets the dataOnly flag if the size of the file is unchanged.
+** The idea behind dataOnly is that it should only write the file content
+** to disk, not the inode.  We only set dataOnly if the file size is 
+** unchanged since the file size is part of the inode.  However, 
+** Ted Ts'o tells us that fdatasync() will also write the inode if the
+** file size has changed.  The only real difference between fdatasync()
+** and fsync(), Ted tells us, is that fdatasync() will not flush the
+** inode if the mtime or owner or other inode attributes have changed.
+** We only care about the file size, not the other file attributes, so
+** as far as SQLite is concerned, an fdatasync() is always adequate.
+** So, we always use fdatasync() if it is available, regardless of
+** the value of the dataOnly flag.
+*/
+static int full_fsync(int fd, int fullSync, int dataOnly){
+  int rc;
+
+  /* The following "ifdef/elif/else/" block has the same structure as
+  ** the one below. It is replicated here solely to avoid cluttering 
+  ** up the real code with the UNUSED_PARAMETER() macros.
+  */
+#ifdef SQLITE_NO_SYNC
+  UNUSED_PARAMETER(fd);
+  UNUSED_PARAMETER(fullSync);
+  UNUSED_PARAMETER(dataOnly);
+#elif HAVE_FULLFSYNC
+  UNUSED_PARAMETER(dataOnly);
+#else
+  UNUSED_PARAMETER(fullSync);
+  UNUSED_PARAMETER(dataOnly);
+#endif
+
+  /* Record the number of times that we do a normal fsync() and 
+  ** FULLSYNC.  This is used during testing to verify that this procedure
+  ** gets called with the correct arguments.
+  */
+#ifdef SQLITE_TEST
+  if( fullSync ) sqlite3_fullsync_count++;
+  sqlite3_sync_count++;
+#endif
+
+  /* If we compiled with the SQLITE_NO_SYNC flag, then syncing is a
+  ** no-op
+  */
+#ifdef SQLITE_NO_SYNC
+  rc = SQLITE_OK;
+#elif HAVE_FULLFSYNC
+  if( fullSync ){
+    rc = osFcntl(fd, F_FULLFSYNC, 0);
+  }else{
+    rc = 1;
+  }
+  /* If the FULLFSYNC failed, fall back to attempting an fsync().
+  ** It shouldn't be possible for fullfsync to fail on the local 
+  ** file system (on OSX), so failure indicates that FULLFSYNC
+  ** isn't supported for this file system. So, attempt an fsync 
+  ** and (for now) ignore the overhead of a superfluous fcntl call.  
+  ** It'd be better to detect fullfsync support once and avoid 
+  ** the fcntl call every time sync is called.
+  */
+  if( rc ) rc = fsync(fd);
+
+#elif defined(__APPLE__)
+  /* fdatasync() on HFS+ doesn't yet flush the file size if it changed correctly
+  ** so currently we default to the macro that redefines fdatasync to fsync
+  */
+  rc = fsync(fd);
+#else 
+  rc = fdatasync(fd);
+#if OS_VXWORKS
+  if( rc==-1 && errno==ENOTSUP ){
+    rc = fsync(fd);
+  }
+#endif /* OS_VXWORKS */
+#endif /* ifdef SQLITE_NO_SYNC elif HAVE_FULLFSYNC */
+
+  if( OS_VXWORKS && rc!= -1 ){
+    rc = 0;
+  }
+  return rc;
+}
+
+/*
+** Make sure all writes to a particular file are committed to disk.
+**
+** If dataOnly==0 then both the file itself and its metadata (file
+** size, access time, etc) are synced.  If dataOnly!=0 then only the
+** file data is synced.
+**
+** Under Unix, also make sure that the directory entry for the file
+** has been created by fsync-ing the directory that contains the file.
+** If we do not do this and we encounter a power failure, the directory
+** entry for the journal might not exist after we reboot.  The next
+** SQLite to access the file will not know that the journal exists (because
+** the directory entry for the journal was never created) and the transaction
+** will not roll back - possibly leading to database corruption.
+*/
+static int unixSync(sqlite3_file *id, int flags){
+  int rc;
+  unixFile *pFile = (unixFile*)id;
+
+  int isDataOnly = (flags&SQLITE_SYNC_DATAONLY);
+  int isFullsync = (flags&0x0F)==SQLITE_SYNC_FULL;
+
+  /* Check that one of SQLITE_SYNC_NORMAL or FULL was passed */
+  assert((flags&0x0F)==SQLITE_SYNC_NORMAL
+      || (flags&0x0F)==SQLITE_SYNC_FULL
+  );
+
+  /* Unix cannot, but some systems may return SQLITE_FULL from here. This
+  ** line is to test that doing so does not cause any problems.
+  */
+  SimulateDiskfullError( return SQLITE_FULL );
+
+  assert( pFile );
+  OSTRACE(("SYNC    %-3d\n", pFile->h));
+  rc = full_fsync(pFile->h, isFullsync, isDataOnly);
+  SimulateIOError( rc=1 );
+  if( rc ){
+    pFile->lastErrno = errno;
+    return unixLogError(SQLITE_IOERR_FSYNC, "full_fsync", pFile->zPath);
+  }
+  if( pFile->dirfd>=0 ){
+    OSTRACE(("DIRSYNC %-3d (have_fullfsync=%d fullsync=%d)\n", pFile->dirfd,
+            HAVE_FULLFSYNC, isFullsync));
+#ifndef SQLITE_DISABLE_DIRSYNC
+    /* The directory sync is only attempted if full_fsync is
+    ** turned off or unavailable.  If a full_fsync occurred above,
+    ** then the directory sync is superfluous.
+    */
+    if( (!HAVE_FULLFSYNC || !isFullsync) && full_fsync(pFile->dirfd,0,0) ){
+       /*
+       ** We have received multiple reports of fsync() returning
+       ** errors when applied to directories on certain file systems.
+       ** A failed directory sync is not a big deal.  So it seems
+       ** better to ignore the error.  Ticket #1657
+       */
+       /* pFile->lastErrno = errno; */
+       /* return SQLITE_IOERR; */
+    }
+#endif
+    /* Only need to sync once, so close the  directory when we are done */
+    robust_close(pFile, pFile->dirfd, __LINE__);
+    pFile->dirfd = -1;
+  }
+  return rc;
+}
+
+/*
+** Truncate an open file to a specified size
+*/
+static int unixTruncate(sqlite3_file *id, i64 nByte){
+  unixFile *pFile = (unixFile *)id;
+  int rc;
+  assert( pFile );
+  SimulateIOError( return SQLITE_IOERR_TRUNCATE );
+
+  /* If the user has configured a chunk-size for this file, truncate the
+  ** file so that it consists of an integer number of chunks (i.e. the
+  ** actual file size after the operation may be larger than the requested
+  ** size).
+  */
+  if( pFile->szChunk ){
+    nByte = ((nByte + pFile->szChunk - 1)/pFile->szChunk) * pFile->szChunk;
+  }
+
+  rc = robust_ftruncate(pFile->h, (off_t)nByte);
+  if( rc ){
+    pFile->lastErrno = errno;
+    return unixLogError(SQLITE_IOERR_TRUNCATE, "ftruncate", pFile->zPath);
+  }else{
+#ifndef NDEBUG
+    /* If we are doing a normal write to a database file (as opposed to
+    ** doing a hot-journal rollback or a write to some file other than a
+    ** normal database file) and we truncate the file to zero length,
+    ** that effectively updates the change counter.  This might happen
+    ** when restoring a database using the backup API from a zero-length
+    ** source.
+    */
+    if( pFile->inNormalWrite && nByte==0 ){
+      pFile->transCntrChng = 1;
+    }
+#endif
+
+    return SQLITE_OK;
+  }
+}
+
+/*
+** Determine the current size of a file in bytes
+*/
+static int unixFileSize(sqlite3_file *id, i64 *pSize){
+  int rc;
+  struct stat buf;
+  assert( id );
+  rc = osFstat(((unixFile*)id)->h, &buf);
+  SimulateIOError( rc=1 );
+  if( rc!=0 ){
+    ((unixFile*)id)->lastErrno = errno;
+    return SQLITE_IOERR_FSTAT;
+  }
+  *pSize = buf.st_size;
+
+  /* When opening a zero-size database, the findInodeInfo() procedure
+  ** writes a single byte into that file in order to work around a bug
+  ** in the OS-X msdos filesystem.  In order to avoid problems with upper
+  ** layers, we need to report this file size as zero even though it is
+  ** really 1.   Ticket #3260.
+  */
+  if( *pSize==1 ) *pSize = 0;
+
+
+  return SQLITE_OK;
+}
+
+#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
+/*
+** Handler for proxy-locking file-control verbs.  Defined below in the
+** proxying locking division.
+*/
+static int proxyFileControl(sqlite3_file*,int,void*);
+#endif
+
+/* 
+** This function is called to handle the SQLITE_FCNTL_SIZE_HINT 
+** file-control operation.
+**
+** If the user has configured a chunk-size for this file, it could be
+** that the file needs to be extended at this point. Otherwise, the
+** SQLITE_FCNTL_SIZE_HINT operation is a no-op for Unix.
+*/
+static int fcntlSizeHint(unixFile *pFile, i64 nByte){
+  if( pFile->szChunk ){
+    i64 nSize;                    /* Required file size */
+    struct stat buf;              /* Used to hold return values of fstat() */
+   
+    if( osFstat(pFile->h, &buf) ) return SQLITE_IOERR_FSTAT;
+
+    nSize = ((nByte+pFile->szChunk-1) / pFile->szChunk) * pFile->szChunk;
+    if( nSize>(i64)buf.st_size ){
+
+#if defined(HAVE_POSIX_FALLOCATE) && HAVE_POSIX_FALLOCATE
+      /* The code below is handling the return value of osFallocate() 
+      ** correctly. posix_fallocate() is defined to "returns zero on success, 
+      ** or an error number on  failure". See the manpage for details. */
+      int err;
+      do{
+        err = osFallocate(pFile->h, buf.st_size, nSize-buf.st_size);
+      }while( err==EINTR );
+      if( err ) return SQLITE_IOERR_WRITE;
+#else
+      /* If the OS does not have posix_fallocate(), fake it. First use
+      ** ftruncate() to set the file size, then write a single byte to
+      ** the last byte in each block within the extended region. This
+      ** is the same technique used by glibc to implement posix_fallocate()
+      ** on systems that do not have a real fallocate() system call.
+      */
+      int nBlk = buf.st_blksize;  /* File-system block size */
+      i64 iWrite;                 /* Next offset to write to */
+
+      if( robust_ftruncate(pFile->h, nSize) ){
+        pFile->lastErrno = errno;
+        return unixLogError(SQLITE_IOERR_TRUNCATE, "ftruncate", pFile->zPath);
+      }
+      iWrite = ((buf.st_size + 2*nBlk - 1)/nBlk)*nBlk-1;
+      while( iWrite<nSize ){
+        int nWrite = seekAndWrite(pFile, iWrite, "", 1);
+        if( nWrite!=1 ) return SQLITE_IOERR_WRITE;
+        iWrite += nBlk;
+      }
+#endif
+    }
+  }
+
+  return SQLITE_OK;
+}
+
+/*
+** Information and control of an open file handle.
+*/
+static int unixFileControl(sqlite3_file *id, int op, void *pArg){
+  switch( op ){
+    case SQLITE_FCNTL_LOCKSTATE: {
+      *(int*)pArg = ((unixFile*)id)->eFileLock;
+      return SQLITE_OK;
+    }
+    case SQLITE_LAST_ERRNO: {
+      *(int*)pArg = ((unixFile*)id)->lastErrno;
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_CHUNK_SIZE: {
+      ((unixFile*)id)->szChunk = *(int *)pArg;
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_SIZE_HINT: {
+      return fcntlSizeHint((unixFile *)id, *(i64 *)pArg);
+    }
+#ifndef NDEBUG
+    /* The pager calls this method to signal that it has done
+    ** a rollback and that the database is therefore unchanged and
+    ** it hence it is OK for the transaction change counter to be
+    ** unchanged.
+    */
+    case SQLITE_FCNTL_DB_UNCHANGED: {
+      ((unixFile*)id)->dbUpdate = 0;
+      return SQLITE_OK;
+    }
+#endif
+#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
+    case SQLITE_SET_LOCKPROXYFILE:
+    case SQLITE_GET_LOCKPROXYFILE: {
+      return proxyFileControl(id,op,pArg);
+    }
+#endif /* SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__) */
+    case SQLITE_FCNTL_SYNC_OMITTED: {
+      return SQLITE_OK;  /* A no-op */
+    }
+  }
+  return SQLITE_NOTFOUND;
+}
+
+/*
+** Return the sector size in bytes of the underlying block device for
+** the specified file. This is almost always 512 bytes, but may be
+** larger for some devices.
+**
+** SQLite code assumes this function cannot fail. It also assumes that
+** if two files are created in the same file-system directory (i.e.
+** a database and its journal file) that the sector size will be the
+** same for both.
+*/
+static int unixSectorSize(sqlite3_file *NotUsed){
+  UNUSED_PARAMETER(NotUsed);
+  return SQLITE_DEFAULT_SECTOR_SIZE;
+}
+
+/*
+** Return the device characteristics for the file. This is always 0 for unix.
+*/
+static int unixDeviceCharacteristics(sqlite3_file *NotUsed){
+  UNUSED_PARAMETER(NotUsed);
+  return 0;
+}
+
+#ifndef SQLITE_OMIT_WAL
+
+
+/*
+** Object used to represent an shared memory buffer.  
+**
+** When multiple threads all reference the same wal-index, each thread
+** has its own unixShm object, but they all point to a single instance
+** of this unixShmNode object.  In other words, each wal-index is opened
+** only once per process.
+**
+** Each unixShmNode object is connected to a single unixInodeInfo object.
+** We could coalesce this object into unixInodeInfo, but that would mean
+** every open file that does not use shared memory (in other words, most
+** open files) would have to carry around this extra information.  So
+** the unixInodeInfo object contains a pointer to this unixShmNode object
+** and the unixShmNode object is created only when needed.
+**
+** unixMutexHeld() must be true when creating or destroying
+** this object or while reading or writing the following fields:
+**
+**      nRef
+**
+** The following fields are read-only after the object is created:
+** 
+**      fid
+**      zFilename
+**
+** Either unixShmNode.mutex must be held or unixShmNode.nRef==0 and
+** unixMutexHeld() is true when reading or writing any other field
+** in this structure.
+*/
+struct unixShmNode {
+  unixInodeInfo *pInode;     /* unixInodeInfo that owns this SHM node */
+  sqlite3_mutex *mutex;      /* Mutex to access this object */
+  char *zFilename;           /* Name of the mmapped file */
+  int h;                     /* Open file descriptor */
+  int szRegion;              /* Size of shared-memory regions */
+  int nRegion;               /* Size of array apRegion */
+  char **apRegion;           /* Array of mapped shared-memory regions */
+  int nRef;                  /* Number of unixShm objects pointing to this */
+  unixShm *pFirst;           /* All unixShm objects pointing to this */
+#ifdef SQLITE_DEBUG
+  u8 exclMask;               /* Mask of exclusive locks held */
+  u8 sharedMask;             /* Mask of shared locks held */
+  u8 nextShmId;              /* Next available unixShm.id value */
+#endif
+};
+
+/*
+** Structure used internally by this VFS to record the state of an
+** open shared memory connection.
+**
+** The following fields are initialized when this object is created and
+** are read-only thereafter:
+**
+**    unixShm.pFile
+**    unixShm.id
+**
+** All other fields are read/write.  The unixShm.pFile->mutex must be held
+** while accessing any read/write fields.
+*/
+struct unixShm {
+  unixShmNode *pShmNode;     /* The underlying unixShmNode object */
+  unixShm *pNext;            /* Next unixShm with the same unixShmNode */
+  u8 hasMutex;               /* True if holding the unixShmNode mutex */
+  u16 sharedMask;            /* Mask of shared locks held */
+  u16 exclMask;              /* Mask of exclusive locks held */
+#ifdef SQLITE_DEBUG
+  u8 id;                     /* Id of this connection within its unixShmNode */
+#endif
+};
+
+/*
+** Constants used for locking
+*/
+#define UNIX_SHM_BASE   ((22+SQLITE_SHM_NLOCK)*4)         /* first lock byte */
+#define UNIX_SHM_DMS    (UNIX_SHM_BASE+SQLITE_SHM_NLOCK)  /* deadman switch */
+
+/*
+** Apply posix advisory locks for all bytes from ofst through ofst+n-1.
+**
+** Locks block if the mask is exactly UNIX_SHM_C and are non-blocking
+** otherwise.
+*/
+static int unixShmSystemLock(
+  unixShmNode *pShmNode, /* Apply locks to this open shared-memory segment */
+  int lockType,          /* F_UNLCK, F_RDLCK, or F_WRLCK */
+  int ofst,              /* First byte of the locking range */
+  int n                  /* Number of bytes to lock */
+){
+  struct flock f;       /* The posix advisory locking structure */
+  int rc = SQLITE_OK;   /* Result code form fcntl() */
+
+  /* Access to the unixShmNode object is serialized by the caller */
+  assert( sqlite3_mutex_held(pShmNode->mutex) || pShmNode->nRef==0 );
+
+  /* Shared locks never span more than one byte */
+  assert( n==1 || lockType!=F_RDLCK );
+
+  /* Locks are within range */
+  assert( n>=1 && n<SQLITE_SHM_NLOCK );
+
+  if( pShmNode->h>=0 ){
+    /* Initialize the locking parameters */
+    memset(&f, 0, sizeof(f));
+    f.l_type = lockType;
+    f.l_whence = SEEK_SET;
+    f.l_start = ofst;
+    f.l_len = n;
+
+    rc = osFcntl(pShmNode->h, F_SETLK, &f);
+    rc = (rc!=(-1)) ? SQLITE_OK : SQLITE_BUSY;
+  }
+
+  /* Update the global lock state and do debug tracing */
+#ifdef SQLITE_DEBUG
+  { u16 mask;
+  OSTRACE(("SHM-LOCK "));
+  mask = (1<<(ofst+n)) - (1<<ofst);
+  if( rc==SQLITE_OK ){
+    if( lockType==F_UNLCK ){
+      OSTRACE(("unlock %d ok", ofst));
+      pShmNode->exclMask &= ~mask;
+      pShmNode->sharedMask &= ~mask;
+    }else if( lockType==F_RDLCK ){
+      OSTRACE(("read-lock %d ok", ofst));
+      pShmNode->exclMask &= ~mask;
+      pShmNode->sharedMask |= mask;
+    }else{
+      assert( lockType==F_WRLCK );
+      OSTRACE(("write-lock %d ok", ofst));
+      pShmNode->exclMask |= mask;
+      pShmNode->sharedMask &= ~mask;
+    }
+  }else{
+    if( lockType==F_UNLCK ){
+      OSTRACE(("unlock %d failed", ofst));
+    }else if( lockType==F_RDLCK ){
+      OSTRACE(("read-lock failed"));
+    }else{
+      assert( lockType==F_WRLCK );
+      OSTRACE(("write-lock %d failed", ofst));
+    }
+  }
+  OSTRACE((" - afterwards %03x,%03x\n",
+           pShmNode->sharedMask, pShmNode->exclMask));
+  }
+#endif
+
+  return rc;        
+}
+
+
+/*
+** Purge the unixShmNodeList list of all entries with unixShmNode.nRef==0.
+**
+** This is not a VFS shared-memory method; it is a utility function called
+** by VFS shared-memory methods.
+*/
+static void unixShmPurge(unixFile *pFd){
+  unixShmNode *p = pFd->pInode->pShmNode;
+  assert( unixMutexHeld() );
+  if( p && p->nRef==0 ){
+    int i;
+    assert( p->pInode==pFd->pInode );
+    if( p->mutex ) sqlite3_mutex_free(p->mutex);
+    for(i=0; i<p->nRegion; i++){
+      if( p->h>=0 ){
+        munmap(p->apRegion[i], p->szRegion);
+      }else{
+        sqlite3_free(p->apRegion[i]);
+      }
+    }
+    sqlite3_free(p->apRegion);
+    if( p->h>=0 ){
+      robust_close(pFd, p->h, __LINE__);
+      p->h = -1;
+    }
+    p->pInode->pShmNode = 0;
+    sqlite3_free(p);
+  }
+}
+
+/*
+** Open a shared-memory area associated with open database file pDbFd.  
+** This particular implementation uses mmapped files.
+**
+** The file used to implement shared-memory is in the same directory
+** as the open database file and has the same name as the open database
+** file with the "-shm" suffix added.  For example, if the database file
+** is "/home/user1/config.db" then the file that is created and mmapped
+** for shared memory will be called "/home/user1/config.db-shm".  
+**
+** Another approach to is to use files in /dev/shm or /dev/tmp or an
+** some other tmpfs mount. But if a file in a different directory
+** from the database file is used, then differing access permissions
+** or a chroot() might cause two different processes on the same
+** database to end up using different files for shared memory - 
+** meaning that their memory would not really be shared - resulting
+** in database corruption.  Nevertheless, this tmpfs file usage
+** can be enabled at compile-time using -DSQLITE_SHM_DIRECTORY="/dev/shm"
+** or the equivalent.  The use of the SQLITE_SHM_DIRECTORY compile-time
+** option results in an incompatible build of SQLite;  builds of SQLite
+** that with differing SQLITE_SHM_DIRECTORY settings attempt to use the
+** same database file at the same time, database corruption will likely
+** result. The SQLITE_SHM_DIRECTORY compile-time option is considered
+** "unsupported" and may go away in a future SQLite release.
+**
+** When opening a new shared-memory file, if no other instances of that
+** file are currently open, in this process or in other processes, then
+** the file must be truncated to zero length or have its header cleared.
+**
+** If the original database file (pDbFd) is using the "unix-excl" VFS
+** that means that an exclusive lock is held on the database file and
+** that no other processes are able to read or write the database.  In
+** that case, we do not really need shared memory.  No shared memory
+** file is created.  The shared memory will be simulated with heap memory.
+*/
+static int unixOpenSharedMemory(unixFile *pDbFd){
+  struct unixShm *p = 0;          /* The connection to be opened */
+  struct unixShmNode *pShmNode;   /* The underlying mmapped file */
+  int rc;                         /* Result code */
+  unixInodeInfo *pInode;          /* The inode of fd */
+  char *zShmFilename;             /* Name of the file used for SHM */
+  int nShmFilename;               /* Size of the SHM filename in bytes */
+
+  /* Allocate space for the new unixShm object. */
+  p = sqlite3_malloc( sizeof(*p) );
+  if( p==0 ) return SQLITE_NOMEM;
+  memset(p, 0, sizeof(*p));
+  assert( pDbFd->pShm==0 );
+
+  /* Check to see if a unixShmNode object already exists. Reuse an existing
+  ** one if present. Create a new one if necessary.
+  */
+  unixEnterMutex();
+  pInode = pDbFd->pInode;
+  pShmNode = pInode->pShmNode;
+  if( pShmNode==0 ){
+    struct stat sStat;                 /* fstat() info for database file */
+
+    /* Call fstat() to figure out the permissions on the database file. If
+    ** a new *-shm file is created, an attempt will be made to create it
+    ** with the same permissions. The actual permissions the file is created
+    ** with are subject to the current umask setting.
+    */
+    if( osFstat(pDbFd->h, &sStat) && pInode->bProcessLock==0 ){
+      rc = SQLITE_IOERR_FSTAT;
+      goto shm_open_err;
+    }
+
+#ifdef SQLITE_SHM_DIRECTORY
+    nShmFilename = sizeof(SQLITE_SHM_DIRECTORY) + 30;
+#else
+    nShmFilename = 5 + (int)strlen(pDbFd->zPath);
+#endif
+    pShmNode = sqlite3_malloc( sizeof(*pShmNode) + nShmFilename );
+    if( pShmNode==0 ){
+      rc = SQLITE_NOMEM;
+      goto shm_open_err;
+    }
+    memset(pShmNode, 0, sizeof(*pShmNode));
+    zShmFilename = pShmNode->zFilename = (char*)&pShmNode[1];
+#ifdef SQLITE_SHM_DIRECTORY
+    sqlite3_snprintf(nShmFilename, zShmFilename, 
+                     SQLITE_SHM_DIRECTORY "/sqlite-shm-%x-%x",
+                     (u32)sStat.st_ino, (u32)sStat.st_dev);
+#else
+    sqlite3_snprintf(nShmFilename, zShmFilename, "%s-shm", pDbFd->zPath);
+#endif
+    pShmNode->h = -1;
+    pDbFd->pInode->pShmNode = pShmNode;
+    pShmNode->pInode = pDbFd->pInode;
+    pShmNode->mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
+    if( pShmNode->mutex==0 ){
+      rc = SQLITE_NOMEM;
+      goto shm_open_err;
+    }
+
+    if( pInode->bProcessLock==0 ){
+      pShmNode->h = robust_open(zShmFilename, O_RDWR|O_CREAT,
+                               (sStat.st_mode & 0777));
+      if( pShmNode->h<0 ){
+        rc = unixLogError(SQLITE_CANTOPEN_BKPT, "open", zShmFilename);
+        goto shm_open_err;
+      }
+  
+      /* Check to see if another process is holding the dead-man switch.
+      ** If not, truncate the file to zero length. 
+      */
+      rc = SQLITE_OK;
+      if( unixShmSystemLock(pShmNode, F_WRLCK, UNIX_SHM_DMS, 1)==SQLITE_OK ){
+        if( robust_ftruncate(pShmNode->h, 0) ){
+          rc = unixLogError(SQLITE_IOERR_SHMOPEN, "ftruncate", zShmFilename);
+        }
+      }
+      if( rc==SQLITE_OK ){
+        rc = unixShmSystemLock(pShmNode, F_RDLCK, UNIX_SHM_DMS, 1);
+      }
+      if( rc ) goto shm_open_err;
+    }
+  }
+
+  /* Make the new connection a child of the unixShmNode */
+  p->pShmNode = pShmNode;
+#ifdef SQLITE_DEBUG
+  p->id = pShmNode->nextShmId++;
+#endif
+  pShmNode->nRef++;
+  pDbFd->pShm = p;
+  unixLeaveMutex();
+
+  /* The reference count on pShmNode has already been incremented under
+  ** the cover of the unixEnterMutex() mutex and the pointer from the
+  ** new (struct unixShm) object to the pShmNode has been set. All that is
+  ** left to do is to link the new object into the linked list starting
+  ** at pShmNode->pFirst. This must be done while holding the pShmNode->mutex 
+  ** mutex.
+  */
+  sqlite3_mutex_enter(pShmNode->mutex);
+  p->pNext = pShmNode->pFirst;
+  pShmNode->pFirst = p;
+  sqlite3_mutex_leave(pShmNode->mutex);
+  return SQLITE_OK;
+
+  /* Jump here on any error */
+shm_open_err:
+  unixShmPurge(pDbFd);       /* This call frees pShmNode if required */
+  sqlite3_free(p);
+  unixLeaveMutex();
+  return rc;
+}
+
+/*
+** This function is called to obtain a pointer to region iRegion of the 
+** shared-memory associated with the database file fd. Shared-memory regions 
+** are numbered starting from zero. Each shared-memory region is szRegion 
+** bytes in size.
+**
+** If an error occurs, an error code is returned and *pp is set to NULL.
+**
+** Otherwise, if the bExtend parameter is 0 and the requested shared-memory
+** region has not been allocated (by any client, including one running in a
+** separate process), then *pp is set to NULL and SQLITE_OK returned. If 
+** bExtend is non-zero and the requested shared-memory region has not yet 
+** been allocated, it is allocated by this function.
+**
+** If the shared-memory region has already been allocated or is allocated by
+** this call as described above, then it is mapped into this processes 
+** address space (if it is not already), *pp is set to point to the mapped 
+** memory and SQLITE_OK returned.
+*/
+static int unixShmMap(
+  sqlite3_file *fd,               /* Handle open on database file */
+  int iRegion,                    /* Region to retrieve */
+  int szRegion,                   /* Size of regions */
+  int bExtend,                    /* True to extend file if necessary */
+  void volatile **pp              /* OUT: Mapped memory */
+){
+  unixFile *pDbFd = (unixFile*)fd;
+  unixShm *p;
+  unixShmNode *pShmNode;
+  int rc = SQLITE_OK;
+
+  /* If the shared-memory file has not yet been opened, open it now. */
+  if( pDbFd->pShm==0 ){
+    rc = unixOpenSharedMemory(pDbFd);
+    if( rc!=SQLITE_OK ) return rc;
+  }
+
+  p = pDbFd->pShm;
+  pShmNode = p->pShmNode;
+  sqlite3_mutex_enter(pShmNode->mutex);
+  assert( szRegion==pShmNode->szRegion || pShmNode->nRegion==0 );
+  assert( pShmNode->pInode==pDbFd->pInode );
+  assert( pShmNode->h>=0 || pDbFd->pInode->bProcessLock==1 );
+  assert( pShmNode->h<0 || pDbFd->pInode->bProcessLock==0 );
+
+  if( pShmNode->nRegion<=iRegion ){
+    char **apNew;                      /* New apRegion[] array */
+    int nByte = (iRegion+1)*szRegion;  /* Minimum required file size */
+    struct stat sStat;                 /* Used by fstat() */
+
+    pShmNode->szRegion = szRegion;
+
+    if( pShmNode->h>=0 ){
+      /* The requested region is not mapped into this processes address space.
+      ** Check to see if it has been allocated (i.e. if the wal-index file is
+      ** large enough to contain the requested region).
+      */
+      if( osFstat(pShmNode->h, &sStat) ){
+        rc = SQLITE_IOERR_SHMSIZE;
+        goto shmpage_out;
+      }
+  
+      if( sStat.st_size<nByte ){
+        /* The requested memory region does not exist. If bExtend is set to
+        ** false, exit early. *pp will be set to NULL and SQLITE_OK returned.
+        **
+        ** Alternatively, if bExtend is true, use ftruncate() to allocate
+        ** the requested memory region.
+        */
+        if( !bExtend ) goto shmpage_out;
+        if( robust_ftruncate(pShmNode->h, nByte) ){
+          rc = unixLogError(SQLITE_IOERR_SHMSIZE, "ftruncate",
+                            pShmNode->zFilename);
+          goto shmpage_out;
+        }
+      }
+    }
+
+    /* Map the requested memory region into this processes address space. */
+    apNew = (char **)sqlite3_realloc(
+        pShmNode->apRegion, (iRegion+1)*sizeof(char *)
+    );
+    if( !apNew ){
+      rc = SQLITE_IOERR_NOMEM;
+      goto shmpage_out;
+    }
+    pShmNode->apRegion = apNew;
+    while(pShmNode->nRegion<=iRegion){
+      void *pMem;
+      if( pShmNode->h>=0 ){
+        pMem = mmap(0, szRegion, PROT_READ|PROT_WRITE, 
+            MAP_SHARED, pShmNode->h, pShmNode->nRegion*szRegion
+        );
+        if( pMem==MAP_FAILED ){
+          rc = SQLITE_IOERR;
+          goto shmpage_out;
+        }
+      }else{
+        pMem = sqlite3_malloc(szRegion);
+        if( pMem==0 ){
+          rc = SQLITE_NOMEM;
+          goto shmpage_out;
+        }
+        memset(pMem, 0, szRegion);
+      }
+      pShmNode->apRegion[pShmNode->nRegion] = pMem;
+      pShmNode->nRegion++;
+    }
+  }
+
+shmpage_out:
+  if( pShmNode->nRegion>iRegion ){
+    *pp = pShmNode->apRegion[iRegion];
+  }else{
+    *pp = 0;
+  }
+  sqlite3_mutex_leave(pShmNode->mutex);
+  return rc;
+}
+
+/*
+** Change the lock state for a shared-memory segment.
+**
+** Note that the relationship between SHAREd and EXCLUSIVE locks is a little
+** different here than in posix.  In xShmLock(), one can go from unlocked
+** to shared and back or from unlocked to exclusive and back.  But one may
+** not go from shared to exclusive or from exclusive to shared.
+*/
+static int unixShmLock(
+  sqlite3_file *fd,          /* Database file holding the shared memory */
+  int ofst,                  /* First lock to acquire or release */
+  int n,                     /* Number of locks to acquire or release */
+  int flags                  /* What to do with the lock */
+){
+  unixFile *pDbFd = (unixFile*)fd;      /* Connection holding shared memory */
+  unixShm *p = pDbFd->pShm;             /* The shared memory being locked */
+  unixShm *pX;                          /* For looping over all siblings */
+  unixShmNode *pShmNode = p->pShmNode;  /* The underlying file iNode */
+  int rc = SQLITE_OK;                   /* Result code */
+  u16 mask;                             /* Mask of locks to take or release */
+
+  assert( pShmNode==pDbFd->pInode->pShmNode );
+  assert( pShmNode->pInode==pDbFd->pInode );
+  assert( ofst>=0 && ofst+n<=SQLITE_SHM_NLOCK );
+  assert( n>=1 );
+  assert( flags==(SQLITE_SHM_LOCK | SQLITE_SHM_SHARED)
+       || flags==(SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE)
+       || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED)
+       || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE) );
+  assert( n==1 || (flags & SQLITE_SHM_EXCLUSIVE)!=0 );
+  assert( pShmNode->h>=0 || pDbFd->pInode->bProcessLock==1 );
+  assert( pShmNode->h<0 || pDbFd->pInode->bProcessLock==0 );
+
+  mask = (1<<(ofst+n)) - (1<<ofst);
+  assert( n>1 || mask==(1<<ofst) );
+  sqlite3_mutex_enter(pShmNode->mutex);
+  if( flags & SQLITE_SHM_UNLOCK ){
+    u16 allMask = 0; /* Mask of locks held by siblings */
+
+    /* See if any siblings hold this same lock */
+    for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
+      if( pX==p ) continue;
+      assert( (pX->exclMask & (p->exclMask|p->sharedMask))==0 );
+      allMask |= pX->sharedMask;
+    }
+
+    /* Unlock the system-level locks */
+    if( (mask & allMask)==0 ){
+      rc = unixShmSystemLock(pShmNode, F_UNLCK, ofst+UNIX_SHM_BASE, n);
+    }else{
+      rc = SQLITE_OK;
+    }
+
+    /* Undo the local locks */
+    if( rc==SQLITE_OK ){
+      p->exclMask &= ~mask;
+      p->sharedMask &= ~mask;
+    } 
+  }else if( flags & SQLITE_SHM_SHARED ){
+    u16 allShared = 0;  /* Union of locks held by connections other than "p" */
+
+    /* Find out which shared locks are already held by sibling connections.
+    ** If any sibling already holds an exclusive lock, go ahead and return
+    ** SQLITE_BUSY.
+    */
+    for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
+      if( (pX->exclMask & mask)!=0 ){
+        rc = SQLITE_BUSY;
+        break;
+      }
+      allShared |= pX->sharedMask;
+    }
+
+    /* Get shared locks at the system level, if necessary */
+    if( rc==SQLITE_OK ){
+      if( (allShared & mask)==0 ){
+        rc = unixShmSystemLock(pShmNode, F_RDLCK, ofst+UNIX_SHM_BASE, n);
+      }else{
+        rc = SQLITE_OK;
+      }
+    }
+
+    /* Get the local shared locks */
+    if( rc==SQLITE_OK ){
+      p->sharedMask |= mask;
+    }
+  }else{
+    /* Make sure no sibling connections hold locks that will block this
+    ** lock.  If any do, return SQLITE_BUSY right away.
+    */
+    for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
+      if( (pX->exclMask & mask)!=0 || (pX->sharedMask & mask)!=0 ){
+        rc = SQLITE_BUSY;
+        break;
+      }
+    }
+  
+    /* Get the exclusive locks at the system level.  Then if successful
+    ** also mark the local connection as being locked.
+    */
+    if( rc==SQLITE_OK ){
+      rc = unixShmSystemLock(pShmNode, F_WRLCK, ofst+UNIX_SHM_BASE, n);
+      if( rc==SQLITE_OK ){
+        assert( (p->sharedMask & mask)==0 );
+        p->exclMask |= mask;
+      }
+    }
+  }
+  sqlite3_mutex_leave(pShmNode->mutex);
+  OSTRACE(("SHM-LOCK shmid-%d, pid-%d got %03x,%03x\n",
+           p->id, getpid(), p->sharedMask, p->exclMask));
+  return rc;
+}
+
+/*
+** Implement a memory barrier or memory fence on shared memory.  
+**
+** All loads and stores begun before the barrier must complete before
+** any load or store begun after the barrier.
+*/
+static void unixShmBarrier(
+  sqlite3_file *fd                /* Database file holding the shared memory */
+){
+  UNUSED_PARAMETER(fd);
+  unixEnterMutex();
+  unixLeaveMutex();
+}
+
+/*
+** Close a connection to shared-memory.  Delete the underlying 
+** storage if deleteFlag is true.
+**
+** If there is no shared memory associated with the connection then this
+** routine is a harmless no-op.
+*/
+static int unixShmUnmap(
+  sqlite3_file *fd,               /* The underlying database file */
+  int deleteFlag                  /* Delete shared-memory if true */
+){
+  unixShm *p;                     /* The connection to be closed */
+  unixShmNode *pShmNode;          /* The underlying shared-memory file */
+  unixShm **pp;                   /* For looping over sibling connections */
+  unixFile *pDbFd;                /* The underlying database file */
+
+  pDbFd = (unixFile*)fd;
+  p = pDbFd->pShm;
+  if( p==0 ) return SQLITE_OK;
+  pShmNode = p->pShmNode;
+
+  assert( pShmNode==pDbFd->pInode->pShmNode );
+  assert( pShmNode->pInode==pDbFd->pInode );
+
+  /* Remove connection p from the set of connections associated
+  ** with pShmNode */
+  sqlite3_mutex_enter(pShmNode->mutex);
+  for(pp=&pShmNode->pFirst; (*pp)!=p; pp = &(*pp)->pNext){}
+  *pp = p->pNext;
+
+  /* Free the connection p */
+  sqlite3_free(p);
+  pDbFd->pShm = 0;
+  sqlite3_mutex_leave(pShmNode->mutex);
+
+  /* If pShmNode->nRef has reached 0, then close the underlying
+  ** shared-memory file, too */
+  unixEnterMutex();
+  assert( pShmNode->nRef>0 );
+  pShmNode->nRef--;
+  if( pShmNode->nRef==0 ){
+    if( deleteFlag && pShmNode->h>=0 ) unlink(pShmNode->zFilename);
+    unixShmPurge(pDbFd);
+  }
+  unixLeaveMutex();
+
+  return SQLITE_OK;
+}
+
+
+#else
+# define unixShmMap     0
+# define unixShmLock    0
+# define unixShmBarrier 0
+# define unixShmUnmap   0
+#endif /* #ifndef SQLITE_OMIT_WAL */
+
+/*
+** Here ends the implementation of all sqlite3_file methods.
+**
+********************** End sqlite3_file Methods *******************************
+******************************************************************************/
+
+/*
+** This division contains definitions of sqlite3_io_methods objects that
+** implement various file locking strategies.  It also contains definitions
+** of "finder" functions.  A finder-function is used to locate the appropriate
+** sqlite3_io_methods object for a particular database file.  The pAppData
+** field of the sqlite3_vfs VFS objects are initialized to be pointers to
+** the correct finder-function for that VFS.
+**
+** Most finder functions return a pointer to a fixed sqlite3_io_methods
+** object.  The only interesting finder-function is autolockIoFinder, which
+** looks at the filesystem type and tries to guess the best locking
+** strategy from that.
+**
+** For finder-funtion F, two objects are created:
+**
+**    (1) The real finder-function named "FImpt()".
+**
+**    (2) A constant pointer to this function named just "F".
+**
+**
+** A pointer to the F pointer is used as the pAppData value for VFS
+** objects.  We have to do this instead of letting pAppData point
+** directly at the finder-function since C90 rules prevent a void*
+** from be cast into a function pointer.
+**
+**
+** Each instance of this macro generates two objects:
+**
+**   *  A constant sqlite3_io_methods object call METHOD that has locking
+**      methods CLOSE, LOCK, UNLOCK, CKRESLOCK.
+**
+**   *  An I/O method finder function called FINDER that returns a pointer
+**      to the METHOD object in the previous bullet.
+*/
+#define IOMETHODS(FINDER, METHOD, VERSION, CLOSE, LOCK, UNLOCK, CKLOCK)      \
+static const sqlite3_io_methods METHOD = {                                   \
+   VERSION,                    /* iVersion */                                \
+   CLOSE,                      /* xClose */                                  \
+   unixRead,                   /* xRead */                                   \
+   unixWrite,                  /* xWrite */                                  \
+   unixTruncate,               /* xTruncate */                               \
+   unixSync,                   /* xSync */                                   \
+   unixFileSize,               /* xFileSize */                               \
+   LOCK,                       /* xLock */                                   \
+   UNLOCK,                     /* xUnlock */                                 \
+   CKLOCK,                     /* xCheckReservedLock */                      \
+   unixFileControl,            /* xFileControl */                            \
+   unixSectorSize,             /* xSectorSize */                             \
+   unixDeviceCharacteristics,  /* xDeviceCapabilities */                     \
+   unixShmMap,                 /* xShmMap */                                 \
+   unixShmLock,                /* xShmLock */                                \
+   unixShmBarrier,             /* xShmBarrier */                             \
+   unixShmUnmap                /* xShmUnmap */                               \
+};                                                                           \
+static const sqlite3_io_methods *FINDER##Impl(const char *z, unixFile *p){   \
+  UNUSED_PARAMETER(z); UNUSED_PARAMETER(p);                                  \
+  return &METHOD;                                                            \
+}                                                                            \
+static const sqlite3_io_methods *(*const FINDER)(const char*,unixFile *p)    \
+    = FINDER##Impl;
+
+/*
+** Here are all of the sqlite3_io_methods objects for each of the
+** locking strategies.  Functions that return pointers to these methods
+** are also created.
+*/
+IOMETHODS(
+  posixIoFinder,            /* Finder function name */
+  posixIoMethods,           /* sqlite3_io_methods object name */
+  2,                        /* shared memory is enabled */
+  unixClose,                /* xClose method */
+  unixLock,                 /* xLock method */
+  unixUnlock,               /* xUnlock method */
+  unixCheckReservedLock     /* xCheckReservedLock method */
+)
+IOMETHODS(
+  nolockIoFinder,           /* Finder function name */
+  nolockIoMethods,          /* sqlite3_io_methods object name */
+  1,                        /* shared memory is disabled */
+  nolockClose,              /* xClose method */
+  nolockLock,               /* xLock method */
+  nolockUnlock,             /* xUnlock method */
+  nolockCheckReservedLock   /* xCheckReservedLock method */
+)
+IOMETHODS(
+  dotlockIoFinder,          /* Finder function name */
+  dotlockIoMethods,         /* sqlite3_io_methods object name */
+  1,                        /* shared memory is disabled */
+  dotlockClose,             /* xClose method */
+  dotlockLock,              /* xLock method */
+  dotlockUnlock,            /* xUnlock method */
+  dotlockCheckReservedLock  /* xCheckReservedLock method */
+)
+
+#if SQLITE_ENABLE_LOCKING_STYLE && !OS_VXWORKS
+IOMETHODS(
+  flockIoFinder,            /* Finder function name */
+  flockIoMethods,           /* sqlite3_io_methods object name */
+  1,                        /* shared memory is disabled */
+  flockClose,               /* xClose method */
+  flockLock,                /* xLock method */
+  flockUnlock,              /* xUnlock method */
+  flockCheckReservedLock    /* xCheckReservedLock method */
+)
+#endif
+
+#if OS_VXWORKS
+IOMETHODS(
+  semIoFinder,              /* Finder function name */
+  semIoMethods,             /* sqlite3_io_methods object name */
+  1,                        /* shared memory is disabled */
+  semClose,                 /* xClose method */
+  semLock,                  /* xLock method */
+  semUnlock,                /* xUnlock method */
+  semCheckReservedLock      /* xCheckReservedLock method */
+)
+#endif
+
+#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
+IOMETHODS(
+  afpIoFinder,              /* Finder function name */
+  afpIoMethods,             /* sqlite3_io_methods object name */
+  1,                        /* shared memory is disabled */
+  afpClose,                 /* xClose method */
+  afpLock,                  /* xLock method */
+  afpUnlock,                /* xUnlock method */
+  afpCheckReservedLock      /* xCheckReservedLock method */
+)
+#endif
+
+/*
+** The proxy locking method is a "super-method" in the sense that it
+** opens secondary file descriptors for the conch and lock files and
+** it uses proxy, dot-file, AFP, and flock() locking methods on those
+** secondary files.  For this reason, the division that implements
+** proxy locking is located much further down in the file.  But we need
+** to go ahead and define the sqlite3_io_methods and finder function
+** for proxy locking here.  So we forward declare the I/O methods.
+*/
+#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
+static int proxyClose(sqlite3_file*);
+static int proxyLock(sqlite3_file*, int);
+static int proxyUnlock(sqlite3_file*, int);
+static int proxyCheckReservedLock(sqlite3_file*, int*);
+IOMETHODS(
+  proxyIoFinder,            /* Finder function name */
+  proxyIoMethods,           /* sqlite3_io_methods object name */
+  1,                        /* shared memory is disabled */
+  proxyClose,               /* xClose method */
+  proxyLock,                /* xLock method */
+  proxyUnlock,              /* xUnlock method */
+  proxyCheckReservedLock    /* xCheckReservedLock method */
+)
+#endif
+
+/* nfs lockd on OSX 10.3+ doesn't clear write locks when a read lock is set */
+#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
+IOMETHODS(
+  nfsIoFinder,               /* Finder function name */
+  nfsIoMethods,              /* sqlite3_io_methods object name */
+  1,                         /* shared memory is disabled */
+  unixClose,                 /* xClose method */
+  unixLock,                  /* xLock method */
+  nfsUnlock,                 /* xUnlock method */
+  unixCheckReservedLock      /* xCheckReservedLock method */
+)
+#endif
+
+#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
+/* 
+** This "finder" function attempts to determine the best locking strategy 
+** for the database file "filePath".  It then returns the sqlite3_io_methods
+** object that implements that strategy.
+**
+** This is for MacOSX only.
+*/
+static const sqlite3_io_methods *autolockIoFinderImpl(
+  const char *filePath,    /* name of the database file */
+  unixFile *pNew           /* open file object for the database file */
+){
+  static const struct Mapping {
+    const char *zFilesystem;              /* Filesystem type name */
+    const sqlite3_io_methods *pMethods;   /* Appropriate locking method */
+  } aMap[] = {
+    { "hfs",    &posixIoMethods },
+    { "ufs",    &posixIoMethods },
+    { "afpfs",  &afpIoMethods },
+    { "smbfs",  &afpIoMethods },
+    { "webdav", &nolockIoMethods },
+    { 0, 0 }
+  };
+  int i;
+  struct statfs fsInfo;
+  struct flock lockInfo;
+
+  if( !filePath ){
+    /* If filePath==NULL that means we are dealing with a transient file
+    ** that does not need to be locked. */
+    return &nolockIoMethods;
+  }
+  if( statfs(filePath, &fsInfo) != -1 ){
+    if( fsInfo.f_flags & MNT_RDONLY ){
+      return &nolockIoMethods;
+    }
+    for(i=0; aMap[i].zFilesystem; i++){
+      if( strcmp(fsInfo.f_fstypename, aMap[i].zFilesystem)==0 ){
+        return aMap[i].pMethods;
+      }
+    }
+  }
+
+  /* Default case. Handles, amongst others, "nfs".
+  ** Test byte-range lock using fcntl(). If the call succeeds, 
+  ** assume that the file-system supports POSIX style locks. 
+  */
+  lockInfo.l_len = 1;
+  lockInfo.l_start = 0;
+  lockInfo.l_whence = SEEK_SET;
+  lockInfo.l_type = F_RDLCK;
+  if( osFcntl(pNew->h, F_GETLK, &lockInfo)!=-1 ) {
+    if( strcmp(fsInfo.f_fstypename, "nfs")==0 ){
+      return &nfsIoMethods;
+    } else {
+      return &posixIoMethods;
+    }
+  }else{
+    return &dotlockIoMethods;
+  }
+}
+static const sqlite3_io_methods 
+  *(*const autolockIoFinder)(const char*,unixFile*) = autolockIoFinderImpl;
+
+#endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */
+
+#if OS_VXWORKS && SQLITE_ENABLE_LOCKING_STYLE
+/* 
+** This "finder" function attempts to determine the best locking strategy 
+** for the database file "filePath".  It then returns the sqlite3_io_methods
+** object that implements that strategy.
+**
+** This is for VXWorks only.
+*/
+static const sqlite3_io_methods *autolockIoFinderImpl(
+  const char *filePath,    /* name of the database file */
+  unixFile *pNew           /* the open file object */
+){
+  struct flock lockInfo;
+
+  if( !filePath ){
+    /* If filePath==NULL that means we are dealing with a transient file
+    ** that does not need to be locked. */
+    return &nolockIoMethods;
+  }
+
+  /* Test if fcntl() is supported and use POSIX style locks.
+  ** Otherwise fall back to the named semaphore method.
+  */
+  lockInfo.l_len = 1;
+  lockInfo.l_start = 0;
+  lockInfo.l_whence = SEEK_SET;
+  lockInfo.l_type = F_RDLCK;
+  if( osFcntl(pNew->h, F_GETLK, &lockInfo)!=-1 ) {
+    return &posixIoMethods;
+  }else{
+    return &semIoMethods;
+  }
+}
+static const sqlite3_io_methods 
+  *(*const autolockIoFinder)(const char*,unixFile*) = autolockIoFinderImpl;
+
+#endif /* OS_VXWORKS && SQLITE_ENABLE_LOCKING_STYLE */
+
+/*
+** An abstract type for a pointer to a IO method finder function:
+*/
+typedef const sqlite3_io_methods *(*finder_type)(const char*,unixFile*);
+
+
+/****************************************************************************
+**************************** sqlite3_vfs methods ****************************
+**
+** This division contains the implementation of methods on the
+** sqlite3_vfs object.
+*/
+
+/*
+** Initialize the contents of the unixFile structure pointed to by pId.
+*/
+static int fillInUnixFile(
+  sqlite3_vfs *pVfs,      /* Pointer to vfs object */
+  int h,                  /* Open file descriptor of file being opened */
+  int dirfd,              /* Directory file descriptor */
+  sqlite3_file *pId,      /* Write to the unixFile structure here */
+  const char *zFilename,  /* Name of the file being opened */
+  int noLock,             /* Omit locking if true */
+  int isDelete,           /* Delete on close if true */
+  int isReadOnly          /* True if the file is opened read-only */
+){
+  const sqlite3_io_methods *pLockingStyle;
+  unixFile *pNew = (unixFile *)pId;
+  int rc = SQLITE_OK;
+
+  assert( pNew->pInode==NULL );
+
+  /* Parameter isDelete is only used on vxworks. Express this explicitly 
+  ** here to prevent compiler warnings about unused parameters.
+  */
+  UNUSED_PARAMETER(isDelete);
+
+  /* Usually the path zFilename should not be a relative pathname. The
+  ** exception is when opening the proxy "conch" file in builds that
+  ** include the special Apple locking styles.
+  */
+#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
+  assert( zFilename==0 || zFilename[0]=='/' 
+    || pVfs->pAppData==(void*)&autolockIoFinder );
+#else
+  assert( zFilename==0 || zFilename[0]=='/' );
+#endif
+
+  OSTRACE(("OPEN    %-3d %s\n", h, zFilename));
+  pNew->h = h;
+  pNew->dirfd = dirfd;
+  pNew->zPath = zFilename;
+  if( memcmp(pVfs->zName,"unix-excl",10)==0 ){
+    pNew->ctrlFlags = UNIXFILE_EXCL;
+  }else{
+    pNew->ctrlFlags = 0;
+  }
+  if( isReadOnly ){
+    pNew->ctrlFlags |= UNIXFILE_RDONLY;
+  }
+
+#if OS_VXWORKS
+  pNew->pId = vxworksFindFileId(zFilename);
+  if( pNew->pId==0 ){
+    noLock = 1;
+    rc = SQLITE_NOMEM;
+  }
+#endif
+
+  if( noLock ){
+    pLockingStyle = &nolockIoMethods;
+  }else{
+    pLockingStyle = (**(finder_type*)pVfs->pAppData)(zFilename, pNew);
+#if SQLITE_ENABLE_LOCKING_STYLE
+    /* Cache zFilename in the locking context (AFP and dotlock override) for
+    ** proxyLock activation is possible (remote proxy is based on db name)
+    ** zFilename remains valid until file is closed, to support */
+    pNew->lockingContext = (void*)zFilename;
+#endif
+  }
+
+  if( pLockingStyle == &posixIoMethods
+#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
+    || pLockingStyle == &nfsIoMethods
+#endif
+  ){
+    unixEnterMutex();
+    rc = findInodeInfo(pNew, &pNew->pInode);
+    if( rc!=SQLITE_OK ){
+      /* If an error occured in findInodeInfo(), close the file descriptor
+      ** immediately, before releasing the mutex. findInodeInfo() may fail
+      ** in two scenarios:
+      **
+      **   (a) A call to fstat() failed.
+      **   (b) A malloc failed.
+      **
+      ** Scenario (b) may only occur if the process is holding no other
+      ** file descriptors open on the same file. If there were other file
+      ** descriptors on this file, then no malloc would be required by
+      ** findInodeInfo(). If this is the case, it is quite safe to close
+      ** handle h - as it is guaranteed that no posix locks will be released
+      ** by doing so.
+      **
+      ** If scenario (a) caused the error then things are not so safe. The
+      ** implicit assumption here is that if fstat() fails, things are in
+      ** such bad shape that dropping a lock or two doesn't matter much.
+      */
+      robust_close(pNew, h, __LINE__);
+      h = -1;
+    }
+    unixLeaveMutex();
+  }
+
+#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
+  else if( pLockingStyle == &afpIoMethods ){
+    /* AFP locking uses the file path so it needs to be included in
+    ** the afpLockingContext.
+    */
+    afpLockingContext *pCtx;
+    pNew->lockingContext = pCtx = sqlite3_malloc( sizeof(*pCtx) );
+    if( pCtx==0 ){
+      rc = SQLITE_NOMEM;
+    }else{
+      /* NB: zFilename exists and remains valid until the file is closed
+      ** according to requirement F11141.  So we do not need to make a
+      ** copy of the filename. */
+      pCtx->dbPath = zFilename;
+      pCtx->reserved = 0;
+      srandomdev();
+      unixEnterMutex();
+      rc = findInodeInfo(pNew, &pNew->pInode);
+      if( rc!=SQLITE_OK ){
+        sqlite3_free(pNew->lockingContext);
+        robust_close(pNew, h, __LINE__);
+        h = -1;
+      }
+      unixLeaveMutex();        
+    }
+  }
+#endif
+
+  else if( pLockingStyle == &dotlockIoMethods ){
+    /* Dotfile locking uses the file path so it needs to be included in
+    ** the dotlockLockingContext 
+    */
+    char *zLockFile;
+    int nFilename;
+    nFilename = (int)strlen(zFilename) + 6;
+    zLockFile = (char *)sqlite3_malloc(nFilename);
+    if( zLockFile==0 ){
+      rc = SQLITE_NOMEM;
+    }else{
+      sqlite3_snprintf(nFilename, zLockFile, "%s" DOTLOCK_SUFFIX, zFilename);
+    }
+    pNew->lockingContext = zLockFile;
+  }
+
+#if OS_VXWORKS
+  else if( pLockingStyle == &semIoMethods ){
+    /* Named semaphore locking uses the file path so it needs to be
+    ** included in the semLockingContext
+    */
+    unixEnterMutex();
+    rc = findInodeInfo(pNew, &pNew->pInode);
+    if( (rc==SQLITE_OK) && (pNew->pInode->pSem==NULL) ){
+      char *zSemName = pNew->pInode->aSemName;
+      int n;
+      sqlite3_snprintf(MAX_PATHNAME, zSemName, "/%s.sem",
+                       pNew->pId->zCanonicalName);
+      for( n=1; zSemName[n]; n++ )
+        if( zSemName[n]=='/' ) zSemName[n] = '_';
+      pNew->pInode->pSem = sem_open(zSemName, O_CREAT, 0666, 1);
+      if( pNew->pInode->pSem == SEM_FAILED ){
+        rc = SQLITE_NOMEM;
+        pNew->pInode->aSemName[0] = '\0';
+      }
+    }
+    unixLeaveMutex();
+  }
+#endif
+  
+  pNew->lastErrno = 0;
+#if OS_VXWORKS
+  if( rc!=SQLITE_OK ){
+    if( h>=0 ) robust_close(pNew, h, __LINE__);
+    h = -1;
+    unlink(zFilename);
+    isDelete = 0;
+  }
+  pNew->isDelete = isDelete;
+#endif
+  if( rc!=SQLITE_OK ){
+    if( dirfd>=0 ) robust_close(pNew, dirfd, __LINE__);
+    if( h>=0 ) robust_close(pNew, h, __LINE__);
+  }else{
+    pNew->pMethod = pLockingStyle;
+    OpenCounter(+1);
+  }
+  return rc;
+}
+
+/*
+** Open a file descriptor to the directory containing file zFilename.
+** If successful, *pFd is set to the opened file descriptor and
+** SQLITE_OK is returned. If an error occurs, either SQLITE_NOMEM
+** or SQLITE_CANTOPEN is returned and *pFd is set to an undefined
+** value.
+**
+** If SQLITE_OK is returned, the caller is responsible for closing
+** the file descriptor *pFd using close().
+*/
+static int openDirectory(const char *zFilename, int *pFd){
+  int ii;
+  int fd = -1;
+  char zDirname[MAX_PATHNAME+1];
+
+  sqlite3_snprintf(MAX_PATHNAME, zDirname, "%s", zFilename);
+  for(ii=(int)strlen(zDirname); ii>1 && zDirname[ii]!='/'; ii--);
+  if( ii>0 ){
+    zDirname[ii] = '\0';
+    fd = robust_open(zDirname, O_RDONLY|O_BINARY, 0);
+    if( fd>=0 ){
+#ifdef FD_CLOEXEC
+      osFcntl(fd, F_SETFD, osFcntl(fd, F_GETFD, 0) | FD_CLOEXEC);
+#endif
+      OSTRACE(("OPENDIR %-3d %s\n", fd, zDirname));
+    }
+  }
+  *pFd = fd;
+  return (fd>=0?SQLITE_OK:unixLogError(SQLITE_CANTOPEN_BKPT, "open", zDirname));
+}
+
+/*
+** Return the name of a directory in which to put temporary files.
+** If no suitable temporary file directory can be found, return NULL.
+*/
+static const char *unixTempFileDir(void){
+  static const char *azDirs[] = {
+     0,
+     0,
+     "/var/tmp",
+     "/usr/tmp",
+     "/tmp",
+     0        /* List terminator */
+  };
+  unsigned int i;
+  struct stat buf;
+  const char *zDir = 0;
+
+  azDirs[0] = sqlite3_temp_directory;
+  if( !azDirs[1] ) azDirs[1] = getenv("TMPDIR");
+  for(i=0; i<sizeof(azDirs)/sizeof(azDirs[0]); zDir=azDirs[i++]){
+    if( zDir==0 ) continue;
+    if( osStat(zDir, &buf) ) continue;
+    if( !S_ISDIR(buf.st_mode) ) continue;
+    if( osAccess(zDir, 07) ) continue;
+    break;
+  }
+  return zDir;
+}
+
+/*
+** Create a temporary file name in zBuf.  zBuf must be allocated
+** by the calling process and must be big enough to hold at least
+** pVfs->mxPathname bytes.
+*/
+static int unixGetTempname(int nBuf, char *zBuf){
+  static const unsigned char zChars[] =
+    "abcdefghijklmnopqrstuvwxyz"
+    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+    "0123456789";
+  unsigned int i, j;
+  const char *zDir;
+
+  /* It's odd to simulate an io-error here, but really this is just
+  ** using the io-error infrastructure to test that SQLite handles this
+  ** function failing. 
+  */
+  SimulateIOError( return SQLITE_IOERR );
+
+  zDir = unixTempFileDir();
+  if( zDir==0 ) zDir = ".";
+
+  /* Check that the output buffer is large enough for the temporary file 
+  ** name. If it is not, return SQLITE_ERROR.
+  */
+  if( (strlen(zDir) + strlen(SQLITE_TEMP_FILE_PREFIX) + 17) >= (size_t)nBuf ){
+    return SQLITE_ERROR;
+  }
+
+  do{
+    sqlite3_snprintf(nBuf-17, zBuf, "%s/"SQLITE_TEMP_FILE_PREFIX, zDir);
+    j = (int)strlen(zBuf);
+    sqlite3_randomness(15, &zBuf[j]);
+    for(i=0; i<15; i++, j++){
+      zBuf[j] = (char)zChars[ ((unsigned char)zBuf[j])%(sizeof(zChars)-1) ];
+    }
+    zBuf[j] = 0;
+  }while( osAccess(zBuf,0)==0 );
+  return SQLITE_OK;
+}
+
+#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
+/*
+** Routine to transform a unixFile into a proxy-locking unixFile.
+** Implementation in the proxy-lock division, but used by unixOpen()
+** if SQLITE_PREFER_PROXY_LOCKING is defined.
+*/
+static int proxyTransformUnixFile(unixFile*, const char*);
+#endif
+
+/*
+** Search for an unused file descriptor that was opened on the database 
+** file (not a journal or master-journal file) identified by pathname
+** zPath with SQLITE_OPEN_XXX flags matching those passed as the second
+** argument to this function.
+**
+** Such a file descriptor may exist if a database connection was closed
+** but the associated file descriptor could not be closed because some
+** other file descriptor open on the same file is holding a file-lock.
+** Refer to comments in the unixClose() function and the lengthy comment
+** describing "Posix Advisory Locking" at the start of this file for 
+** further details. Also, ticket #4018.
+**
+** If a suitable file descriptor is found, then it is returned. If no
+** such file descriptor is located, -1 is returned.
+*/
+static UnixUnusedFd *findReusableFd(const char *zPath, int flags){
+  UnixUnusedFd *pUnused = 0;
+
+  /* Do not search for an unused file descriptor on vxworks. Not because
+  ** vxworks would not benefit from the change (it might, we're not sure),
+  ** but because no way to test it is currently available. It is better 
+  ** not to risk breaking vxworks support for the sake of such an obscure 
+  ** feature.  */
+#if !OS_VXWORKS
+  struct stat sStat;                   /* Results of stat() call */
+
+  /* A stat() call may fail for various reasons. If this happens, it is
+  ** almost certain that an open() call on the same path will also fail.
+  ** For this reason, if an error occurs in the stat() call here, it is
+  ** ignored and -1 is returned. The caller will try to open a new file
+  ** descriptor on the same path, fail, and return an error to SQLite.
+  **
+  ** Even if a subsequent open() call does succeed, the consequences of
+  ** not searching for a resusable file descriptor are not dire.  */
+  if( 0==stat(zPath, &sStat) ){
+    unixInodeInfo *pInode;
+
+    unixEnterMutex();
+    pInode = inodeList;
+    while( pInode && (pInode->fileId.dev!=sStat.st_dev
+                     || pInode->fileId.ino!=sStat.st_ino) ){
+       pInode = pInode->pNext;
+    }
+    if( pInode ){
+      UnixUnusedFd **pp;
+      for(pp=&pInode->pUnused; *pp && (*pp)->flags!=flags; pp=&((*pp)->pNext));
+      pUnused = *pp;
+      if( pUnused ){
+        *pp = pUnused->pNext;
+      }
+    }
+    unixLeaveMutex();
+  }
+#endif    /* if !OS_VXWORKS */
+  return pUnused;
+}
+
+/*
+** This function is called by unixOpen() to determine the unix permissions
+** to create new files with. If no error occurs, then SQLITE_OK is returned
+** and a value suitable for passing as the third argument to open(2) is
+** written to *pMode. If an IO error occurs, an SQLite error code is 
+** returned and the value of *pMode is not modified.
+**
+** If the file being opened is a temporary file, it is always created with
+** the octal permissions 0600 (read/writable by owner only). If the file
+** is a database or master journal file, it is created with the permissions 
+** mask SQLITE_DEFAULT_FILE_PERMISSIONS.
+**
+** Finally, if the file being opened is a WAL or regular journal file, then 
+** this function queries the file-system for the permissions on the 
+** corresponding database file and sets *pMode to this value. Whenever 
+** possible, WAL and journal files are created using the same permissions 
+** as the associated database file.
+*/
+static int findCreateFileMode(
+  const char *zPath,              /* Path of file (possibly) being created */
+  int flags,                      /* Flags passed as 4th argument to xOpen() */
+  mode_t *pMode                   /* OUT: Permissions to open file with */
+){
+  int rc = SQLITE_OK;             /* Return Code */
+  if( flags & (SQLITE_OPEN_WAL|SQLITE_OPEN_MAIN_JOURNAL) ){
+    char zDb[MAX_PATHNAME+1];     /* Database file path */
+    int nDb;                      /* Number of valid bytes in zDb */
+    struct stat sStat;            /* Output of stat() on database file */
+
+    /* zPath is a path to a WAL or journal file. The following block derives
+    ** the path to the associated database file from zPath. This block handles
+    ** the following naming conventions:
+    **
+    **   "<path to db>-journal"
+    **   "<path to db>-wal"
+    **   "<path to db>-journal-NNNN"
+    **   "<path to db>-wal-NNNN"
+    **
+    ** where NNNN is a 4 digit decimal number. The NNNN naming schemes are 
+    ** used by the test_multiplex.c module.
+    */
+    nDb = sqlite3Strlen30(zPath) - 1; 
+    while( nDb>0 && zPath[nDb]!='l' ) nDb--;
+    nDb -= ((flags & SQLITE_OPEN_WAL) ? 3 : 7);
+    memcpy(zDb, zPath, nDb);
+    zDb[nDb] = '\0';
+
+    if( 0==stat(zDb, &sStat) ){
+      *pMode = sStat.st_mode & 0777;
+    }else{
+      rc = SQLITE_IOERR_FSTAT;
+    }
+  }else if( flags & SQLITE_OPEN_DELETEONCLOSE ){
+    *pMode = 0600;
+  }else{
+    *pMode = SQLITE_DEFAULT_FILE_PERMISSIONS;
+  }
+  return rc;
+}
+
+/*
+** Open the file zPath.
+** 
+** Previously, the SQLite OS layer used three functions in place of this
+** one:
+**
+**     sqlite3OsOpenReadWrite();
+**     sqlite3OsOpenReadOnly();
+**     sqlite3OsOpenExclusive();
+**
+** These calls correspond to the following combinations of flags:
+**
+**     ReadWrite() ->     (READWRITE | CREATE)
+**     ReadOnly()  ->     (READONLY) 
+**     OpenExclusive() -> (READWRITE | CREATE | EXCLUSIVE)
+**
+** The old OpenExclusive() accepted a boolean argument - "delFlag". If
+** true, the file was configured to be automatically deleted when the
+** file handle closed. To achieve the same effect using this new 
+** interface, add the DELETEONCLOSE flag to those specified above for 
+** OpenExclusive().
+*/
+static int unixOpen(
+  sqlite3_vfs *pVfs,           /* The VFS for which this is the xOpen method */
+  const char *zPath,           /* Pathname of file to be opened */
+  sqlite3_file *pFile,         /* The file descriptor to be filled in */
+  int flags,                   /* Input flags to control the opening */
+  int *pOutFlags               /* Output flags returned to SQLite core */
+){
+  unixFile *p = (unixFile *)pFile;
+  int fd = -1;                   /* File descriptor returned by open() */
+  int dirfd = -1;                /* Directory file descriptor */
+  int openFlags = 0;             /* Flags to pass to open() */
+  int eType = flags&0xFFFFFF00;  /* Type of file to open */
+  int noLock;                    /* True to omit locking primitives */
+  int rc = SQLITE_OK;            /* Function Return Code */
+
+  int isExclusive  = (flags & SQLITE_OPEN_EXCLUSIVE);
+  int isDelete     = (flags & SQLITE_OPEN_DELETEONCLOSE);
+  int isCreate     = (flags & SQLITE_OPEN_CREATE);
+  int isReadonly   = (flags & SQLITE_OPEN_READONLY);
+  int isReadWrite  = (flags & SQLITE_OPEN_READWRITE);
+#if SQLITE_ENABLE_LOCKING_STYLE
+  int isAutoProxy  = (flags & SQLITE_OPEN_AUTOPROXY);
+#endif
+
+  /* If creating a master or main-file journal, this function will open
+  ** a file-descriptor on the directory too. The first time unixSync()
+  ** is called the directory file descriptor will be fsync()ed and close()d.
+  */
+  int isOpenDirectory = (isCreate && (
+        eType==SQLITE_OPEN_MASTER_JOURNAL 
+     || eType==SQLITE_OPEN_MAIN_JOURNAL 
+     || eType==SQLITE_OPEN_WAL
+  ));
+
+  /* If argument zPath is a NULL pointer, this function is required to open
+  ** a temporary file. Use this buffer to store the file name in.
+  */
+  char zTmpname[MAX_PATHNAME+1];
+  const char *zName = zPath;
+
+  /* Check the following statements are true: 
+  **
+  **   (a) Exactly one of the READWRITE and READONLY flags must be set, and 
+  **   (b) if CREATE is set, then READWRITE must also be set, and
+  **   (c) if EXCLUSIVE is set, then CREATE must also be set.
+  **   (d) if DELETEONCLOSE is set, then CREATE must also be set.
+  */
+  assert((isReadonly==0 || isReadWrite==0) && (isReadWrite || isReadonly));
+  assert(isCreate==0 || isReadWrite);
+  assert(isExclusive==0 || isCreate);
+  assert(isDelete==0 || isCreate);
+
+  /* The main DB, main journal, WAL file and master journal are never 
+  ** automatically deleted. Nor are they ever temporary files.  */
+  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MAIN_DB );
+  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MAIN_JOURNAL );
+  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MASTER_JOURNAL );
+  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_WAL );
+
+  /* Assert that the upper layer has set one of the "file-type" flags. */
+  assert( eType==SQLITE_OPEN_MAIN_DB      || eType==SQLITE_OPEN_TEMP_DB 
+       || eType==SQLITE_OPEN_MAIN_JOURNAL || eType==SQLITE_OPEN_TEMP_JOURNAL 
+       || eType==SQLITE_OPEN_SUBJOURNAL   || eType==SQLITE_OPEN_MASTER_JOURNAL 
+       || eType==SQLITE_OPEN_TRANSIENT_DB || eType==SQLITE_OPEN_WAL
+  );
+
+  memset(p, 0, sizeof(unixFile));
+
+  if( eType==SQLITE_OPEN_MAIN_DB ){
+    UnixUnusedFd *pUnused;
+    pUnused = findReusableFd(zName, flags);
+    if( pUnused ){
+      fd = pUnused->fd;
+    }else{
+      pUnused = sqlite3_malloc(sizeof(*pUnused));
+      if( !pUnused ){
+        return SQLITE_NOMEM;
+      }
+    }
+    p->pUnused = pUnused;
+  }else if( !zName ){
+    /* If zName is NULL, the upper layer is requesting a temp file. */
+    assert(isDelete && !isOpenDirectory);
+    rc = unixGetTempname(MAX_PATHNAME+1, zTmpname);
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+    zName = zTmpname;
+  }
+
+  /* Determine the value of the flags parameter passed to POSIX function
+  ** open(). These must be calculated even if open() is not called, as
+  ** they may be stored as part of the file handle and used by the 
+  ** 'conch file' locking functions later on.  */
+  if( isReadonly )  openFlags |= O_RDONLY;
+  if( isReadWrite ) openFlags |= O_RDWR;
+  if( isCreate )    openFlags |= O_CREAT;
+  if( isExclusive ) openFlags |= (O_EXCL|O_NOFOLLOW);
+  openFlags |= (O_LARGEFILE|O_BINARY);
+
+  if( fd<0 ){
+    mode_t openMode;              /* Permissions to create file with */
+    rc = findCreateFileMode(zName, flags, &openMode);
+    if( rc!=SQLITE_OK ){
+      assert( !p->pUnused );
+      assert( eType==SQLITE_OPEN_WAL || eType==SQLITE_OPEN_MAIN_JOURNAL );
+      return rc;
+    }
+    fd = robust_open(zName, openFlags, openMode);
+    OSTRACE(("OPENX   %-3d %s 0%o\n", fd, zName, openFlags));
+    if( fd<0 && errno!=EISDIR && isReadWrite && !isExclusive ){
+      /* Failed to open the file for read/write access. Try read-only. */
+      flags &= ~(SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE);
+      openFlags &= ~(O_RDWR|O_CREAT);
+      flags |= SQLITE_OPEN_READONLY;
+      openFlags |= O_RDONLY;
+      isReadonly = 1;
+      fd = robust_open(zName, openFlags, openMode);
+    }
+    if( fd<0 ){
+      rc = unixLogError(SQLITE_CANTOPEN_BKPT, "open", zName);
+      goto open_finished;
+    }
+  }
+  assert( fd>=0 );
+  if( pOutFlags ){
+    *pOutFlags = flags;
+  }
+
+  if( p->pUnused ){
+    p->pUnused->fd = fd;
+    p->pUnused->flags = flags;
+  }
+
+  if( isDelete ){
+#if OS_VXWORKS
+    zPath = zName;
+#else
+    unlink(zName);
+#endif
+  }
+#if SQLITE_ENABLE_LOCKING_STYLE
+  else{
+    p->openFlags = openFlags;
+  }
+#endif
+
+  if( isOpenDirectory ){
+    rc = openDirectory(zPath, &dirfd);
+    if( rc!=SQLITE_OK ){
+      /* It is safe to close fd at this point, because it is guaranteed not
+      ** to be open on a database file. If it were open on a database file,
+      ** it would not be safe to close as this would release any locks held
+      ** on the file by this process.  */
+      assert( eType!=SQLITE_OPEN_MAIN_DB );
+      robust_close(p, fd, __LINE__);
+      goto open_finished;
+    }
+  }
+
+#ifdef FD_CLOEXEC
+  osFcntl(fd, F_SETFD, osFcntl(fd, F_GETFD, 0) | FD_CLOEXEC);
+#endif
+
+  noLock = eType!=SQLITE_OPEN_MAIN_DB;
+
+  
+#if defined(__APPLE__) || SQLITE_ENABLE_LOCKING_STYLE
+  struct statfs fsInfo;
+  if( fstatfs(fd, &fsInfo) == -1 ){
+    ((unixFile*)pFile)->lastErrno = errno;
+    if( dirfd>=0 ) robust_close(p, dirfd, __LINE__);
+    robust_close(p, fd, __LINE__);
+    return SQLITE_IOERR_ACCESS;
+  }
+  if (0 == strncmp("msdos", fsInfo.f_fstypename, 5)) {
+    ((unixFile*)pFile)->fsFlags |= SQLITE_FSFLAGS_IS_MSDOS;
+  }
+#endif
+  
+#if SQLITE_ENABLE_LOCKING_STYLE
+#if SQLITE_PREFER_PROXY_LOCKING
+  isAutoProxy = 1;
+#endif
+  if( isAutoProxy && (zPath!=NULL) && (!noLock) && pVfs->xOpen ){
+    char *envforce = getenv("SQLITE_FORCE_PROXY_LOCKING");
+    int useProxy = 0;
+
+    /* SQLITE_FORCE_PROXY_LOCKING==1 means force always use proxy, 0 means 
+    ** never use proxy, NULL means use proxy for non-local files only.  */
+    if( envforce!=NULL ){
+      useProxy = atoi(envforce)>0;
+    }else{
+      struct statfs fsInfo;
+      if( statfs(zPath, &fsInfo) == -1 ){
+        /* In theory, the close(fd) call is sub-optimal. If the file opened
+        ** with fd is a database file, and there are other connections open
+        ** on that file that are currently holding advisory locks on it,
+        ** then the call to close() will cancel those locks. In practice,
+        ** we're assuming that statfs() doesn't fail very often. At least
+        ** not while other file descriptors opened by the same process on
+        ** the same file are working.  */
+        p->lastErrno = errno;
+        if( dirfd>=0 ){
+          robust_close(p, dirfd, __LINE__);
+        }
+        robust_close(p, fd, __LINE__);
+        rc = SQLITE_IOERR_ACCESS;
+        goto open_finished;
+      }
+      useProxy = !(fsInfo.f_flags&MNT_LOCAL);
+    }
+    if( useProxy ){
+      rc = fillInUnixFile(pVfs, fd, dirfd, pFile, zPath, noLock,
+                          isDelete, isReadonly);
+      if( rc==SQLITE_OK ){
+        rc = proxyTransformUnixFile((unixFile*)pFile, ":auto:");
+        if( rc!=SQLITE_OK ){
+          /* Use unixClose to clean up the resources added in fillInUnixFile 
+          ** and clear all the structure's references.  Specifically, 
+          ** pFile->pMethods will be NULL so sqlite3OsClose will be a no-op 
+          */
+          unixClose(pFile);
+          return rc;
+        }
+      }
+      goto open_finished;
+    }
+  }
+#endif
+  
+  rc = fillInUnixFile(pVfs, fd, dirfd, pFile, zPath, noLock,
+                      isDelete, isReadonly);
+open_finished:
+  if( rc!=SQLITE_OK ){
+    sqlite3_free(p->pUnused);
+  }
+  return rc;
+}
+
+
+/*
+** Delete the file at zPath. If the dirSync argument is true, fsync()
+** the directory after deleting the file.
+*/
+static int unixDelete(
+  sqlite3_vfs *NotUsed,     /* VFS containing this as the xDelete method */
+  const char *zPath,        /* Name of file to be deleted */
+  int dirSync               /* If true, fsync() directory after deleting file */
+){
+  int rc = SQLITE_OK;
+  UNUSED_PARAMETER(NotUsed);
+  SimulateIOError(return SQLITE_IOERR_DELETE);
+  if( unlink(zPath)==(-1) && errno!=ENOENT ){
+    return unixLogError(SQLITE_IOERR_DELETE, "unlink", zPath);
+  }
+#ifndef SQLITE_DISABLE_DIRSYNC
+  if( dirSync ){
+    int fd;
+    rc = openDirectory(zPath, &fd);
+    if( rc==SQLITE_OK ){
+#if OS_VXWORKS
+      if( fsync(fd)==-1 )
+#else
+      if( fsync(fd) )
+#endif
+      {
+        rc = unixLogError(SQLITE_IOERR_DIR_FSYNC, "fsync", zPath);
+      }
+      robust_close(0, fd, __LINE__);
+    }
+  }
+#endif
+  return rc;
+}
+
+/*
+** Test the existance of or access permissions of file zPath. The
+** test performed depends on the value of flags:
+**
+**     SQLITE_ACCESS_EXISTS: Return 1 if the file exists
+**     SQLITE_ACCESS_READWRITE: Return 1 if the file is read and writable.
+**     SQLITE_ACCESS_READONLY: Return 1 if the file is readable.
+**
+** Otherwise return 0.
+*/
+static int unixAccess(
+  sqlite3_vfs *NotUsed,   /* The VFS containing this xAccess method */
+  const char *zPath,      /* Path of the file to examine */
+  int flags,              /* What do we want to learn about the zPath file? */
+  int *pResOut            /* Write result boolean here */
+){
+  int amode = 0;
+  UNUSED_PARAMETER(NotUsed);
+  SimulateIOError( return SQLITE_IOERR_ACCESS; );
+  switch( flags ){
+    case SQLITE_ACCESS_EXISTS:
+      amode = F_OK;
+      break;
+    case SQLITE_ACCESS_READWRITE:
+      amode = W_OK|R_OK;
+      break;
+    case SQLITE_ACCESS_READ:
+      amode = R_OK;
+      break;
+
+    default:
+      assert(!"Invalid flags argument");
+  }
+  *pResOut = (osAccess(zPath, amode)==0);
+  if( flags==SQLITE_ACCESS_EXISTS && *pResOut ){
+    struct stat buf;
+    if( 0==stat(zPath, &buf) && buf.st_size==0 ){
+      *pResOut = 0;
+    }
+  }
+  return SQLITE_OK;
+}
+
+
+/*
+** Turn a relative pathname into a full pathname. The relative path
+** is stored as a nul-terminated string in the buffer pointed to by
+** zPath. 
+**
+** zOut points to a buffer of at least sqlite3_vfs.mxPathname bytes 
+** (in this case, MAX_PATHNAME bytes). The full-path is written to
+** this buffer before returning.
+*/
+static int unixFullPathname(
+  sqlite3_vfs *pVfs,            /* Pointer to vfs object */
+  const char *zPath,            /* Possibly relative input path */
+  int nOut,                     /* Size of output buffer in bytes */
+  char *zOut                    /* Output buffer */
+){
+
+  /* It's odd to simulate an io-error here, but really this is just
+  ** using the io-error infrastructure to test that SQLite handles this
+  ** function failing. This function could fail if, for example, the
+  ** current working directory has been unlinked.
+  */
+  SimulateIOError( return SQLITE_ERROR );
+
+  assert( pVfs->mxPathname==MAX_PATHNAME );
+  UNUSED_PARAMETER(pVfs);
+
+  zOut[nOut-1] = '\0';
+  if( zPath[0]=='/' ){
+    sqlite3_snprintf(nOut, zOut, "%s", zPath);
+  }else{
+    int nCwd;
+    if( osGetcwd(zOut, nOut-1)==0 ){
+      return unixLogError(SQLITE_CANTOPEN_BKPT, "getcwd", zPath);
+    }
+    nCwd = (int)strlen(zOut);
+    sqlite3_snprintf(nOut-nCwd, &zOut[nCwd], "/%s", zPath);
+  }
+  return SQLITE_OK;
+}
+
+
+#ifndef SQLITE_OMIT_LOAD_EXTENSION
+/*
+** Interfaces for opening a shared library, finding entry points
+** within the shared library, and closing the shared library.
+*/
+#include <dlfcn.h>
+static void *unixDlOpen(sqlite3_vfs *NotUsed, const char *zFilename){
+  UNUSED_PARAMETER(NotUsed);
+  return dlopen(zFilename, RTLD_NOW | RTLD_GLOBAL);
+}
+
+/*
+** SQLite calls this function immediately after a call to unixDlSym() or
+** unixDlOpen() fails (returns a null pointer). If a more detailed error
+** message is available, it is written to zBufOut. If no error message
+** is available, zBufOut is left unmodified and SQLite uses a default
+** error message.
+*/
+static void unixDlError(sqlite3_vfs *NotUsed, int nBuf, char *zBufOut){
+  const char *zErr;
+  UNUSED_PARAMETER(NotUsed);
+  unixEnterMutex();
+  zErr = dlerror();
+  if( zErr ){
+    sqlite3_snprintf(nBuf, zBufOut, "%s", zErr);
+  }
+  unixLeaveMutex();
+}
+static void (*unixDlSym(sqlite3_vfs *NotUsed, void *p, const char*zSym))(void){
+  /* 
+  ** GCC with -pedantic-errors says that C90 does not allow a void* to be
+  ** cast into a pointer to a function.  And yet the library dlsym() routine
+  ** returns a void* which is really a pointer to a function.  So how do we
+  ** use dlsym() with -pedantic-errors?
+  **
+  ** Variable x below is defined to be a pointer to a function taking
+  ** parameters void* and const char* and returning a pointer to a function.
+  ** We initialize x by assigning it a pointer to the dlsym() function.
+  ** (That assignment requires a cast.)  Then we call the function that
+  ** x points to.  
+  **
+  ** This work-around is unlikely to work correctly on any system where
+  ** you really cannot cast a function pointer into void*.  But then, on the
+  ** other hand, dlsym() will not work on such a system either, so we have
+  ** not really lost anything.
+  */
+  void (*(*x)(void*,const char*))(void);
+  UNUSED_PARAMETER(NotUsed);
+  x = (void(*(*)(void*,const char*))(void))dlsym;
+  return (*x)(p, zSym);
+}
+static void unixDlClose(sqlite3_vfs *NotUsed, void *pHandle){
+  UNUSED_PARAMETER(NotUsed);
+  dlclose(pHandle);
+}
+#else /* if SQLITE_OMIT_LOAD_EXTENSION is defined: */
+  #define unixDlOpen  0
+  #define unixDlError 0
+  #define unixDlSym   0
+  #define unixDlClose 0
+#endif
+
+/*
+** Write nBuf bytes of random data to the supplied buffer zBuf.
+*/
+static int unixRandomness(sqlite3_vfs *NotUsed, int nBuf, char *zBuf){
+  UNUSED_PARAMETER(NotUsed);
+  assert((size_t)nBuf>=(sizeof(time_t)+sizeof(int)));
+
+  /* We have to initialize zBuf to prevent valgrind from reporting
+  ** errors.  The reports issued by valgrind are incorrect - we would
+  ** prefer that the randomness be increased by making use of the
+  ** uninitialized space in zBuf - but valgrind errors tend to worry
+  ** some users.  Rather than argue, it seems easier just to initialize
+  ** the whole array and silence valgrind, even if that means less randomness
+  ** in the random seed.
+  **
+  ** When testing, initializing zBuf[] to zero is all we do.  That means
+  ** that we always use the same random number sequence.  This makes the
+  ** tests repeatable.
+  */
+  memset(zBuf, 0, nBuf);
+#if !defined(SQLITE_TEST)
+  {
+    int pid, fd;
+    fd = robust_open("/dev/urandom", O_RDONLY, 0);
+    if( fd<0 ){
+      time_t t;
+      time(&t);
+      memcpy(zBuf, &t, sizeof(t));
+      pid = getpid();
+      memcpy(&zBuf[sizeof(t)], &pid, sizeof(pid));
+      assert( sizeof(t)+sizeof(pid)<=(size_t)nBuf );
+      nBuf = sizeof(t) + sizeof(pid);
+    }else{
+      do{ nBuf = osRead(fd, zBuf, nBuf); }while( nBuf<0 && errno==EINTR );
+      robust_close(0, fd, __LINE__);
+    }
+  }
+#endif
+  return nBuf;
+}
+
+
+/*
+** Sleep for a little while.  Return the amount of time slept.
+** The argument is the number of microseconds we want to sleep.
+** The return value is the number of microseconds of sleep actually
+** requested from the underlying operating system, a number which
+** might be greater than or equal to the argument, but not less
+** than the argument.
+*/
+static int unixSleep(sqlite3_vfs *NotUsed, int microseconds){
+#if OS_VXWORKS
+  struct timespec sp;
+
+  sp.tv_sec = microseconds / 1000000;
+  sp.tv_nsec = (microseconds % 1000000) * 1000;
+  nanosleep(&sp, NULL);
+  UNUSED_PARAMETER(NotUsed);
+  return microseconds;
+#elif defined(HAVE_USLEEP) && HAVE_USLEEP
+  usleep(microseconds);
+  UNUSED_PARAMETER(NotUsed);
+  return microseconds;
+#else
+  int seconds = (microseconds+999999)/1000000;
+  sleep(seconds);
+  UNUSED_PARAMETER(NotUsed);
+  return seconds*1000000;
+#endif
+}
+
+/*
+** The following variable, if set to a non-zero value, is interpreted as
+** the number of seconds since 1970 and is used to set the result of
+** sqlite3OsCurrentTime() during testing.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_current_time = 0;  /* Fake system time in seconds since 1970. */
+#endif
+
+/*
+** Find the current time (in Universal Coordinated Time).  Write into *piNow
+** the current time and date as a Julian Day number times 86_400_000.  In
+** other words, write into *piNow the number of milliseconds since the Julian
+** epoch of noon in Greenwich on November 24, 4714 B.C according to the
+** proleptic Gregorian calendar.
+**
+** On success, return 0.  Return 1 if the time and date cannot be found.
+*/
+static int unixCurrentTimeInt64(sqlite3_vfs *NotUsed, sqlite3_int64 *piNow){
+  static const sqlite3_int64 unixEpoch = 24405875*(sqlite3_int64)8640000;
+#if defined(NO_GETTOD)
+  time_t t;
+  time(&t);
+  *piNow = ((sqlite3_int64)t)*1000 + unixEpoch;
+#elif OS_VXWORKS
+  struct timespec sNow;
+  clock_gettime(CLOCK_REALTIME, &sNow);
+  *piNow = unixEpoch + 1000*(sqlite3_int64)sNow.tv_sec + sNow.tv_nsec/1000000;
+#else
+  struct timeval sNow;
+  gettimeofday(&sNow, 0);
+  *piNow = unixEpoch + 1000*(sqlite3_int64)sNow.tv_sec + sNow.tv_usec/1000;
+#endif
+
+#ifdef SQLITE_TEST
+  if( sqlite3_current_time ){
+    *piNow = 1000*(sqlite3_int64)sqlite3_current_time + unixEpoch;
+  }
+#endif
+  UNUSED_PARAMETER(NotUsed);
+  return 0;
+}
+
+/*
+** Find the current time (in Universal Coordinated Time).  Write the
+** current time and date as a Julian Day number into *prNow and
+** return 0.  Return 1 if the time and date cannot be found.
+*/
+static int unixCurrentTime(sqlite3_vfs *NotUsed, double *prNow){
+  sqlite3_int64 i;
+  UNUSED_PARAMETER(NotUsed);
+  unixCurrentTimeInt64(0, &i);
+  *prNow = i/86400000.0;
+  return 0;
+}
+
+/*
+** We added the xGetLastError() method with the intention of providing
+** better low-level error messages when operating-system problems come up
+** during SQLite operation.  But so far, none of that has been implemented
+** in the core.  So this routine is never called.  For now, it is merely
+** a place-holder.
+*/
+static int unixGetLastError(sqlite3_vfs *NotUsed, int NotUsed2, char *NotUsed3){
+  UNUSED_PARAMETER(NotUsed);
+  UNUSED_PARAMETER(NotUsed2);
+  UNUSED_PARAMETER(NotUsed3);
+  return 0;
+}
+
+
+/*
+************************ End of sqlite3_vfs methods ***************************
+******************************************************************************/
+
+/******************************************************************************
+************************** Begin Proxy Locking ********************************
+**
+** Proxy locking is a "uber-locking-method" in this sense:  It uses the
+** other locking methods on secondary lock files.  Proxy locking is a
+** meta-layer over top of the primitive locking implemented above.  For
+** this reason, the division that implements of proxy locking is deferred
+** until late in the file (here) after all of the other I/O methods have
+** been defined - so that the primitive locking methods are available
+** as services to help with the implementation of proxy locking.
+**
+****
+**
+** The default locking schemes in SQLite use byte-range locks on the
+** database file to coordinate safe, concurrent access by multiple readers
+** and writers [http://sqlite.org/lockingv3.html].  The five file locking
+** states (UNLOCKED, PENDING, SHARED, RESERVED, EXCLUSIVE) are implemented
+** as POSIX read & write locks over fixed set of locations (via fsctl),
+** on AFP and SMB only exclusive byte-range locks are available via fsctl
+** with _IOWR('z', 23, struct ByteRangeLockPB2) to track the same 5 states.
+** To simulate a F_RDLCK on the shared range, on AFP a randomly selected
+** address in the shared range is taken for a SHARED lock, the entire
+** shared range is taken for an EXCLUSIVE lock):
+**
+**      PENDING_BYTE        0x40000000		   	
+**      RESERVED_BYTE       0x40000001
+**      SHARED_RANGE        0x40000002 -> 0x40000200
+**
+** This works well on the local file system, but shows a nearly 100x
+** slowdown in read performance on AFP because the AFP client disables
+** the read cache when byte-range locks are present.  Enabling the read
+** cache exposes a cache coherency problem that is present on all OS X
+** supported network file systems.  NFS and AFP both observe the
+** close-to-open semantics for ensuring cache coherency
+** [http://nfs.sourceforge.net/#faq_a8], which does not effectively
+** address the requirements for concurrent database access by multiple
+** readers and writers
+** [http://www.nabble.com/SQLite-on-NFS-cache-coherency-td15655701.html].
+**
+** To address the performance and cache coherency issues, proxy file locking
+** changes the way database access is controlled by limiting access to a
+** single host at a time and moving file locks off of the database file
+** and onto a proxy file on the local file system.  
+**
+**
+** Using proxy locks
+** -----------------
+**
+** C APIs
+**
+**  sqlite3_file_control(db, dbname, SQLITE_SET_LOCKPROXYFILE,
+**                       <proxy_path> | ":auto:");
+**  sqlite3_file_control(db, dbname, SQLITE_GET_LOCKPROXYFILE, &<proxy_path>);
+**
+**
+** SQL pragmas
+**
+**  PRAGMA [database.]lock_proxy_file=<proxy_path> | :auto:
+**  PRAGMA [database.]lock_proxy_file
+**
+** Specifying ":auto:" means that if there is a conch file with a matching
+** host ID in it, the proxy path in the conch file will be used, otherwise
+** a proxy path based on the user's temp dir
+** (via confstr(_CS_DARWIN_USER_TEMP_DIR,...)) will be used and the
+** actual proxy file name is generated from the name and path of the
+** database file.  For example:
+**
+**       For database path "/Users/me/foo.db" 
+**       The lock path will be "<tmpdir>/sqliteplocks/_Users_me_foo.db:auto:")
+**
+** Once a lock proxy is configured for a database connection, it can not
+** be removed, however it may be switched to a different proxy path via
+** the above APIs (assuming the conch file is not being held by another
+** connection or process). 
+**
+**
+** How proxy locking works
+** -----------------------
+**
+** Proxy file locking relies primarily on two new supporting files: 
+**
+**   *  conch file to limit access to the database file to a single host
+**      at a time
+**
+**   *  proxy file to act as a proxy for the advisory locks normally
+**      taken on the database
+**
+** The conch file - to use a proxy file, sqlite must first "hold the conch"
+** by taking an sqlite-style shared lock on the conch file, reading the
+** contents and comparing the host's unique host ID (see below) and lock
+** proxy path against the values stored in the conch.  The conch file is
+** stored in the same directory as the database file and the file name
+** is patterned after the database file name as ".<databasename>-conch".
+** If the conch file does not exist, or it's contents do not match the
+** host ID and/or proxy path, then the lock is escalated to an exclusive
+** lock and the conch file contents is updated with the host ID and proxy
+** path and the lock is downgraded to a shared lock again.  If the conch
+** is held by another process (with a shared lock), the exclusive lock
+** will fail and SQLITE_BUSY is returned.
+**
+** The proxy file - a single-byte file used for all advisory file locks
+** normally taken on the database file.   This allows for safe sharing
+** of the database file for multiple readers and writers on the same
+** host (the conch ensures that they all use the same local lock file).
+**
+** Requesting the lock proxy does not immediately take the conch, it is
+** only taken when the first request to lock database file is made.  
+** This matches the semantics of the traditional locking behavior, where
+** opening a connection to a database file does not take a lock on it.
+** The shared lock and an open file descriptor are maintained until 
+** the connection to the database is closed. 
+**
+** The proxy file and the lock file are never deleted so they only need
+** to be created the first time they are used.
+**
+** Configuration options
+** ---------------------
+**
+**  SQLITE_PREFER_PROXY_LOCKING
+**
+**       Database files accessed on non-local file systems are
+**       automatically configured for proxy locking, lock files are
+**       named automatically using the same logic as
+**       PRAGMA lock_proxy_file=":auto:"
+**    
+**  SQLITE_PROXY_DEBUG
+**
+**       Enables the logging of error messages during host id file
+**       retrieval and creation
+**
+**  LOCKPROXYDIR
+**
+**       Overrides the default directory used for lock proxy files that
+**       are named automatically via the ":auto:" setting
+**
+**  SQLITE_DEFAULT_PROXYDIR_PERMISSIONS
+**
+**       Permissions to use when creating a directory for storing the
+**       lock proxy files, only used when LOCKPROXYDIR is not set.
+**    
+**    
+** As mentioned above, when compiled with SQLITE_PREFER_PROXY_LOCKING,
+** setting the environment variable SQLITE_FORCE_PROXY_LOCKING to 1 will
+** force proxy locking to be used for every database file opened, and 0
+** will force automatic proxy locking to be disabled for all database
+** files (explicity calling the SQLITE_SET_LOCKPROXYFILE pragma or
+** sqlite_file_control API is not affected by SQLITE_FORCE_PROXY_LOCKING).
+*/
+
+/*
+** Proxy locking is only available on MacOSX 
+*/
+#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
+
+/*
+** The proxyLockingContext has the path and file structures for the remote 
+** and local proxy files in it
+*/
+typedef struct proxyLockingContext proxyLockingContext;
+struct proxyLockingContext {
+  unixFile *conchFile;         /* Open conch file */
+  char *conchFilePath;         /* Name of the conch file */
+  unixFile *lockProxy;         /* Open proxy lock file */
+  char *lockProxyPath;         /* Name of the proxy lock file */
+  char *dbPath;                /* Name of the open file */
+  int conchHeld;               /* 1 if the conch is held, -1 if lockless */
+  void *oldLockingContext;     /* Original lockingcontext to restore on close */
+  sqlite3_io_methods const *pOldMethod;     /* Original I/O methods for close */
+};
+
+/* 
+** The proxy lock file path for the database at dbPath is written into lPath, 
+** which must point to valid, writable memory large enough for a maxLen length
+** file path. 
+*/
+static int proxyGetLockPath(const char *dbPath, char *lPath, size_t maxLen){
+  int len;
+  int dbLen;
+  int i;
+
+#ifdef LOCKPROXYDIR
+  len = strlcpy(lPath, LOCKPROXYDIR, maxLen);
+#else
+# ifdef _CS_DARWIN_USER_TEMP_DIR
+  {
+    if( !confstr(_CS_DARWIN_USER_TEMP_DIR, lPath, maxLen) ){
+      OSTRACE(("GETLOCKPATH  failed %s errno=%d pid=%d\n",
+               lPath, errno, getpid()));
+      return SQLITE_IOERR_LOCK;
+    }
+    len = strlcat(lPath, "sqliteplocks", maxLen);    
+  }
+# else
+  len = strlcpy(lPath, "/tmp/", maxLen);
+# endif
+#endif
+
+  if( lPath[len-1]!='/' ){
+    len = strlcat(lPath, "/", maxLen);
+  }
+  
+  /* transform the db path to a unique cache name */
+  dbLen = (int)strlen(dbPath);
+  for( i=0; i<dbLen && (i+len+7)<(int)maxLen; i++){
+    char c = dbPath[i];
+    lPath[i+len] = (c=='/')?'_':c;
+  }
+  lPath[i+len]='\0';
+  strlcat(lPath, ":auto:", maxLen);
+  OSTRACE(("GETLOCKPATH  proxy lock path=%s pid=%d\n", lPath, getpid()));
+  return SQLITE_OK;
+}
+
+/* 
+ ** Creates the lock file and any missing directories in lockPath
+ */
+static int proxyCreateLockPath(const char *lockPath){
+  int i, len;
+  char buf[MAXPATHLEN];
+  int start = 0;
+  
+  assert(lockPath!=NULL);
+  /* try to create all the intermediate directories */
+  len = (int)strlen(lockPath);
+  buf[0] = lockPath[0];
+  for( i=1; i<len; i++ ){
+    if( lockPath[i] == '/' && (i - start > 0) ){
+      /* only mkdir if leaf dir != "." or "/" or ".." */
+      if( i-start>2 || (i-start==1 && buf[start] != '.' && buf[start] != '/') 
+         || (i-start==2 && buf[start] != '.' && buf[start+1] != '.') ){
+        buf[i]='\0';
+        if( mkdir(buf, SQLITE_DEFAULT_PROXYDIR_PERMISSIONS) ){
+          int err=errno;
+          if( err!=EEXIST ) {
+            OSTRACE(("CREATELOCKPATH  FAILED creating %s, "
+                     "'%s' proxy lock path=%s pid=%d\n",
+                     buf, strerror(err), lockPath, getpid()));
+            return err;
+          }
+        }
+      }
+      start=i+1;
+    }
+    buf[i] = lockPath[i];
+  }
+  OSTRACE(("CREATELOCKPATH  proxy lock path=%s pid=%d\n", lockPath, getpid()));
+  return 0;
+}
+
+/*
+** Create a new VFS file descriptor (stored in memory obtained from
+** sqlite3_malloc) and open the file named "path" in the file descriptor.
+**
+** The caller is responsible not only for closing the file descriptor
+** but also for freeing the memory associated with the file descriptor.
+*/
+static int proxyCreateUnixFile(
+    const char *path,        /* path for the new unixFile */
+    unixFile **ppFile,       /* unixFile created and returned by ref */
+    int islockfile           /* if non zero missing dirs will be created */
+) {
+  int fd = -1;
+  int dirfd = -1;
+  unixFile *pNew;
+  int rc = SQLITE_OK;
+  int openFlags = O_RDWR | O_CREAT;
+  sqlite3_vfs dummyVfs;
+  int terrno = 0;
+  UnixUnusedFd *pUnused = NULL;
+
+  /* 1. first try to open/create the file
+  ** 2. if that fails, and this is a lock file (not-conch), try creating
+  ** the parent directories and then try again.
+  ** 3. if that fails, try to open the file read-only
+  ** otherwise return BUSY (if lock file) or CANTOPEN for the conch file
+  */
+  pUnused = findReusableFd(path, openFlags);
+  if( pUnused ){
+    fd = pUnused->fd;
+  }else{
+    pUnused = sqlite3_malloc(sizeof(*pUnused));
+    if( !pUnused ){
+      return SQLITE_NOMEM;
+    }
+  }
+  if( fd<0 ){
+    fd = robust_open(path, openFlags, SQLITE_DEFAULT_FILE_PERMISSIONS);
+    terrno = errno;
+    if( fd<0 && errno==ENOENT && islockfile ){
+      if( proxyCreateLockPath(path) == SQLITE_OK ){
+        fd = robust_open(path, openFlags, SQLITE_DEFAULT_FILE_PERMISSIONS);
+      }
+    }
+  }
+  if( fd<0 ){
+    openFlags = O_RDONLY;
+    fd = robust_open(path, openFlags, SQLITE_DEFAULT_FILE_PERMISSIONS);
+    terrno = errno;
+  }
+  if( fd<0 ){
+    if( islockfile ){
+      return SQLITE_BUSY;
+    }
+    switch (terrno) {
+      case EACCES:
+        return SQLITE_PERM;
+      case EIO: 
+        return SQLITE_IOERR_LOCK; /* even though it is the conch */
+      default:
+        return SQLITE_CANTOPEN_BKPT;
+    }
+  }
+  
+  pNew = (unixFile *)sqlite3_malloc(sizeof(*pNew));
+  if( pNew==NULL ){
+    rc = SQLITE_NOMEM;
+    goto end_create_proxy;
+  }
+  memset(pNew, 0, sizeof(unixFile));
+  pNew->openFlags = openFlags;
+  memset(&dummyVfs, 0, sizeof(dummyVfs));
+  dummyVfs.pAppData = (void*)&autolockIoFinder;
+  dummyVfs.zName = "dummy";
+  pUnused->fd = fd;
+  pUnused->flags = openFlags;
+  pNew->pUnused = pUnused;
+  
+  rc = fillInUnixFile(&dummyVfs, fd, dirfd, (sqlite3_file*)pNew, path, 0, 0, 0);
+  if( rc==SQLITE_OK ){
+    *ppFile = pNew;
+    return SQLITE_OK;
+  }
+end_create_proxy:    
+  robust_close(pNew, fd, __LINE__);
+  sqlite3_free(pNew);
+  sqlite3_free(pUnused);
+  return rc;
+}
+
+#ifdef SQLITE_TEST
+/* simulate multiple hosts by creating unique hostid file paths */
+SQLITE_API int sqlite3_hostid_num = 0;
+#endif
+
+#define PROXY_HOSTIDLEN    16  /* conch file host id length */
+
+/* Not always defined in the headers as it ought to be */
+extern int gethostuuid(uuid_t id, const struct timespec *wait);
+
+/* get the host ID via gethostuuid(), pHostID must point to PROXY_HOSTIDLEN 
+** bytes of writable memory.
+*/
+static int proxyGetHostID(unsigned char *pHostID, int *pError){
+  assert(PROXY_HOSTIDLEN == sizeof(uuid_t));
+  memset(pHostID, 0, PROXY_HOSTIDLEN);
+#if defined(__MAX_OS_X_VERSION_MIN_REQUIRED)\
+               && __MAC_OS_X_VERSION_MIN_REQUIRED<1050
+  {
+    static const struct timespec timeout = {1, 0}; /* 1 sec timeout */
+    if( gethostuuid(pHostID, &timeout) ){
+      int err = errno;
+      if( pError ){
+        *pError = err;
+      }
+      return SQLITE_IOERR;
+    }
+  }
+#endif
+#ifdef SQLITE_TEST
+  /* simulate multiple hosts by creating unique hostid file paths */
+  if( sqlite3_hostid_num != 0){
+    pHostID[0] = (char)(pHostID[0] + (char)(sqlite3_hostid_num & 0xFF));
+  }
+#endif
+  
+  return SQLITE_OK;
+}
+
+/* The conch file contains the header, host id and lock file path
+ */
+#define PROXY_CONCHVERSION 2   /* 1-byte header, 16-byte host id, path */
+#define PROXY_HEADERLEN    1   /* conch file header length */
+#define PROXY_PATHINDEX    (PROXY_HEADERLEN+PROXY_HOSTIDLEN)
+#define PROXY_MAXCONCHLEN  (PROXY_HEADERLEN+PROXY_HOSTIDLEN+MAXPATHLEN)
+
+/* 
+** Takes an open conch file, copies the contents to a new path and then moves 
+** it back.  The newly created file's file descriptor is assigned to the
+** conch file structure and finally the original conch file descriptor is 
+** closed.  Returns zero if successful.
+*/
+static int proxyBreakConchLock(unixFile *pFile, uuid_t myHostID){
+  proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext; 
+  unixFile *conchFile = pCtx->conchFile;
+  char tPath[MAXPATHLEN];
+  char buf[PROXY_MAXCONCHLEN];
+  char *cPath = pCtx->conchFilePath;
+  size_t readLen = 0;
+  size_t pathLen = 0;
+  char errmsg[64] = "";
+  int fd = -1;
+  int rc = -1;
+  UNUSED_PARAMETER(myHostID);
+
+  /* create a new path by replace the trailing '-conch' with '-break' */
+  pathLen = strlcpy(tPath, cPath, MAXPATHLEN);
+  if( pathLen>MAXPATHLEN || pathLen<6 || 
+     (strlcpy(&tPath[pathLen-5], "break", 6) != 5) ){
+    sqlite3_snprintf(sizeof(errmsg),errmsg,"path error (len %d)",(int)pathLen);
+    goto end_breaklock;
+  }
+  /* read the conch content */
+  readLen = osPread(conchFile->h, buf, PROXY_MAXCONCHLEN, 0);
+  if( readLen<PROXY_PATHINDEX ){
+    sqlite3_snprintf(sizeof(errmsg),errmsg,"read error (len %d)",(int)readLen);
+    goto end_breaklock;
+  }
+  /* write it out to the temporary break file */
+  fd = robust_open(tPath, (O_RDWR|O_CREAT|O_EXCL),
+                   SQLITE_DEFAULT_FILE_PERMISSIONS);
+  if( fd<0 ){
+    sqlite3_snprintf(sizeof(errmsg), errmsg, "create failed (%d)", errno);
+    goto end_breaklock;
+  }
+  if( osPwrite(fd, buf, readLen, 0) != (ssize_t)readLen ){
+    sqlite3_snprintf(sizeof(errmsg), errmsg, "write failed (%d)", errno);
+    goto end_breaklock;
+  }
+  if( rename(tPath, cPath) ){
+    sqlite3_snprintf(sizeof(errmsg), errmsg, "rename failed (%d)", errno);
+    goto end_breaklock;
+  }
+  rc = 0;
+  fprintf(stderr, "broke stale lock on %s\n", cPath);
+  robust_close(pFile, conchFile->h, __LINE__);
+  conchFile->h = fd;
+  conchFile->openFlags = O_RDWR | O_CREAT;
+
+end_breaklock:
+  if( rc ){
+    if( fd>=0 ){
+      unlink(tPath);
+      robust_close(pFile, fd, __LINE__);
+    }
+    fprintf(stderr, "failed to break stale lock on %s, %s\n", cPath, errmsg);
+  }
+  return rc;
+}
+
+/* Take the requested lock on the conch file and break a stale lock if the 
+** host id matches.
+*/
+static int proxyConchLock(unixFile *pFile, uuid_t myHostID, int lockType){
+  proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext; 
+  unixFile *conchFile = pCtx->conchFile;
+  int rc = SQLITE_OK;
+  int nTries = 0;
+  struct timespec conchModTime;
+  
+  do {
+    rc = conchFile->pMethod->xLock((sqlite3_file*)conchFile, lockType);
+    nTries ++;
+    if( rc==SQLITE_BUSY ){
+      /* If the lock failed (busy):
+       * 1st try: get the mod time of the conch, wait 0.5s and try again. 
+       * 2nd try: fail if the mod time changed or host id is different, wait 
+       *           10 sec and try again
+       * 3rd try: break the lock unless the mod time has changed.
+       */
+      struct stat buf;
+      if( osFstat(conchFile->h, &buf) ){
+        pFile->lastErrno = errno;
+        return SQLITE_IOERR_LOCK;
+      }
+      
+      if( nTries==1 ){
+        conchModTime = buf.st_mtimespec;
+        usleep(500000); /* wait 0.5 sec and try the lock again*/
+        continue;  
+      }
+
+      assert( nTries>1 );
+      if( conchModTime.tv_sec != buf.st_mtimespec.tv_sec || 
+         conchModTime.tv_nsec != buf.st_mtimespec.tv_nsec ){
+        return SQLITE_BUSY;
+      }
+      
+      if( nTries==2 ){  
+        char tBuf[PROXY_MAXCONCHLEN];
+        int len = osPread(conchFile->h, tBuf, PROXY_MAXCONCHLEN, 0);
+        if( len<0 ){
+          pFile->lastErrno = errno;
+          return SQLITE_IOERR_LOCK;
+        }
+        if( len>PROXY_PATHINDEX && tBuf[0]==(char)PROXY_CONCHVERSION){
+          /* don't break the lock if the host id doesn't match */
+          if( 0!=memcmp(&tBuf[PROXY_HEADERLEN], myHostID, PROXY_HOSTIDLEN) ){
+            return SQLITE_BUSY;
+          }
+        }else{
+          /* don't break the lock on short read or a version mismatch */
+          return SQLITE_BUSY;
+        }
+        usleep(10000000); /* wait 10 sec and try the lock again */
+        continue; 
+      }
+      
+      assert( nTries==3 );
+      if( 0==proxyBreakConchLock(pFile, myHostID) ){
+        rc = SQLITE_OK;
+        if( lockType==EXCLUSIVE_LOCK ){
+          rc = conchFile->pMethod->xLock((sqlite3_file*)conchFile, SHARED_LOCK);          
+        }
+        if( !rc ){
+          rc = conchFile->pMethod->xLock((sqlite3_file*)conchFile, lockType);
+        }
+      }
+    }
+  } while( rc==SQLITE_BUSY && nTries<3 );
+  
+  return rc;
+}
+
+/* Takes the conch by taking a shared lock and read the contents conch, if 
+** lockPath is non-NULL, the host ID and lock file path must match.  A NULL 
+** lockPath means that the lockPath in the conch file will be used if the 
+** host IDs match, or a new lock path will be generated automatically 
+** and written to the conch file.
+*/
+static int proxyTakeConch(unixFile *pFile){
+  proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext; 
+  
+  if( pCtx->conchHeld!=0 ){
+    return SQLITE_OK;
+  }else{
+    unixFile *conchFile = pCtx->conchFile;
+    uuid_t myHostID;
+    int pError = 0;
+    char readBuf[PROXY_MAXCONCHLEN];
+    char lockPath[MAXPATHLEN];
+    char *tempLockPath = NULL;
+    int rc = SQLITE_OK;
+    int createConch = 0;
+    int hostIdMatch = 0;
+    int readLen = 0;
+    int tryOldLockPath = 0;
+    int forceNewLockPath = 0;
+    
+    OSTRACE(("TAKECONCH  %d for %s pid=%d\n", conchFile->h,
+             (pCtx->lockProxyPath ? pCtx->lockProxyPath : ":auto:"), getpid()));
+
+    rc = proxyGetHostID(myHostID, &pError);
+    if( (rc&0xff)==SQLITE_IOERR ){
+      pFile->lastErrno = pError;
+      goto end_takeconch;
+    }
+    rc = proxyConchLock(pFile, myHostID, SHARED_LOCK);
+    if( rc!=SQLITE_OK ){
+      goto end_takeconch;
+    }
+    /* read the existing conch file */
+    readLen = seekAndRead((unixFile*)conchFile, 0, readBuf, PROXY_MAXCONCHLEN);
+    if( readLen<0 ){
+      /* I/O error: lastErrno set by seekAndRead */
+      pFile->lastErrno = conchFile->lastErrno;
+      rc = SQLITE_IOERR_READ;
+      goto end_takeconch;
+    }else if( readLen<=(PROXY_HEADERLEN+PROXY_HOSTIDLEN) || 
+             readBuf[0]!=(char)PROXY_CONCHVERSION ){
+      /* a short read or version format mismatch means we need to create a new 
+      ** conch file. 
+      */
+      createConch = 1;
+    }
+    /* if the host id matches and the lock path already exists in the conch
+    ** we'll try to use the path there, if we can't open that path, we'll 
+    ** retry with a new auto-generated path 
+    */
+    do { /* in case we need to try again for an :auto: named lock file */
+
+      if( !createConch && !forceNewLockPath ){
+        hostIdMatch = !memcmp(&readBuf[PROXY_HEADERLEN], myHostID, 
+                                  PROXY_HOSTIDLEN);
+        /* if the conch has data compare the contents */
+        if( !pCtx->lockProxyPath ){
+          /* for auto-named local lock file, just check the host ID and we'll
+           ** use the local lock file path that's already in there
+           */
+          if( hostIdMatch ){
+            size_t pathLen = (readLen - PROXY_PATHINDEX);
+            
+            if( pathLen>=MAXPATHLEN ){
+              pathLen=MAXPATHLEN-1;
+            }
+            memcpy(lockPath, &readBuf[PROXY_PATHINDEX], pathLen);
+            lockPath[pathLen] = 0;
+            tempLockPath = lockPath;
+            tryOldLockPath = 1;
+            /* create a copy of the lock path if the conch is taken */
+            goto end_takeconch;
+          }
+        }else if( hostIdMatch
+               && !strncmp(pCtx->lockProxyPath, &readBuf[PROXY_PATHINDEX],
+                           readLen-PROXY_PATHINDEX)
+        ){
+          /* conch host and lock path match */
+          goto end_takeconch; 
+        }
+      }
+      
+      /* if the conch isn't writable and doesn't match, we can't take it */
+      if( (conchFile->openFlags&O_RDWR) == 0 ){
+        rc = SQLITE_BUSY;
+        goto end_takeconch;
+      }
+      
+      /* either the conch didn't match or we need to create a new one */
+      if( !pCtx->lockProxyPath ){
+        proxyGetLockPath(pCtx->dbPath, lockPath, MAXPATHLEN);
+        tempLockPath = lockPath;
+        /* create a copy of the lock path _only_ if the conch is taken */
+      }
+      
+      /* update conch with host and path (this will fail if other process
+      ** has a shared lock already), if the host id matches, use the big
+      ** stick.
+      */
+      futimes(conchFile->h, NULL);
+      if( hostIdMatch && !createConch ){
+        if( conchFile->pInode && conchFile->pInode->nShared>1 ){
+          /* We are trying for an exclusive lock but another thread in this
+           ** same process is still holding a shared lock. */
+          rc = SQLITE_BUSY;
+        } else {          
+          rc = proxyConchLock(pFile, myHostID, EXCLUSIVE_LOCK);
+        }
+      }else{
+        rc = conchFile->pMethod->xLock((sqlite3_file*)conchFile, EXCLUSIVE_LOCK);
+      }
+      if( rc==SQLITE_OK ){
+        char writeBuffer[PROXY_MAXCONCHLEN];
+        int writeSize = 0;
+        
+        writeBuffer[0] = (char)PROXY_CONCHVERSION;
+        memcpy(&writeBuffer[PROXY_HEADERLEN], myHostID, PROXY_HOSTIDLEN);
+        if( pCtx->lockProxyPath!=NULL ){
+          strlcpy(&writeBuffer[PROXY_PATHINDEX], pCtx->lockProxyPath, MAXPATHLEN);
+        }else{
+          strlcpy(&writeBuffer[PROXY_PATHINDEX], tempLockPath, MAXPATHLEN);
+        }
+        writeSize = PROXY_PATHINDEX + strlen(&writeBuffer[PROXY_PATHINDEX]);
+        robust_ftruncate(conchFile->h, writeSize);
+        rc = unixWrite((sqlite3_file *)conchFile, writeBuffer, writeSize, 0);
+        fsync(conchFile->h);
+        /* If we created a new conch file (not just updated the contents of a 
+         ** valid conch file), try to match the permissions of the database 
+         */
+        if( rc==SQLITE_OK && createConch ){
+          struct stat buf;
+          int err = osFstat(pFile->h, &buf);
+          if( err==0 ){
+            mode_t cmode = buf.st_mode&(S_IRUSR|S_IWUSR | S_IRGRP|S_IWGRP |
+                                        S_IROTH|S_IWOTH);
+            /* try to match the database file R/W permissions, ignore failure */
+#ifndef SQLITE_PROXY_DEBUG
+            osFchmod(conchFile->h, cmode);
+#else
+            do{
+              rc = osFchmod(conchFile->h, cmode);
+            }while( rc==(-1) && errno==EINTR );
+            if( rc!=0 ){
+              int code = errno;
+              fprintf(stderr, "fchmod %o FAILED with %d %s\n",
+                      cmode, code, strerror(code));
+            } else {
+              fprintf(stderr, "fchmod %o SUCCEDED\n",cmode);
+            }
+          }else{
+            int code = errno;
+            fprintf(stderr, "STAT FAILED[%d] with %d %s\n", 
+                    err, code, strerror(code));
+#endif
+          }
+        }
+      }
+      conchFile->pMethod->xUnlock((sqlite3_file*)conchFile, SHARED_LOCK);
+      
+    end_takeconch:
+      OSTRACE(("TRANSPROXY: CLOSE  %d\n", pFile->h));
+      if( rc==SQLITE_OK && pFile->openFlags ){
+        if( pFile->h>=0 ){
+          robust_close(pFile, pFile->h, __LINE__);
+        }
+        pFile->h = -1;
+        int fd = robust_open(pCtx->dbPath, pFile->openFlags,
+                      SQLITE_DEFAULT_FILE_PERMISSIONS);
+        OSTRACE(("TRANSPROXY: OPEN  %d\n", fd));
+        if( fd>=0 ){
+          pFile->h = fd;
+        }else{
+          rc=SQLITE_CANTOPEN_BKPT; /* SQLITE_BUSY? proxyTakeConch called
+           during locking */
+        }
+      }
+      if( rc==SQLITE_OK && !pCtx->lockProxy ){
+        char *path = tempLockPath ? tempLockPath : pCtx->lockProxyPath;
+        rc = proxyCreateUnixFile(path, &pCtx->lockProxy, 1);
+        if( rc!=SQLITE_OK && rc!=SQLITE_NOMEM && tryOldLockPath ){
+          /* we couldn't create the proxy lock file with the old lock file path
+           ** so try again via auto-naming 
+           */
+          forceNewLockPath = 1;
+          tryOldLockPath = 0;
+          continue; /* go back to the do {} while start point, try again */
+        }
+      }
+      if( rc==SQLITE_OK ){
+        /* Need to make a copy of path if we extracted the value
+         ** from the conch file or the path was allocated on the stack
+         */
+        if( tempLockPath ){
+          pCtx->lockProxyPath = sqlite3DbStrDup(0, tempLockPath);
+          if( !pCtx->lockProxyPath ){
+            rc = SQLITE_NOMEM;
+          }
+        }
+      }
+      if( rc==SQLITE_OK ){
+        pCtx->conchHeld = 1;
+        
+        if( pCtx->lockProxy->pMethod == &afpIoMethods ){
+          afpLockingContext *afpCtx;
+          afpCtx = (afpLockingContext *)pCtx->lockProxy->lockingContext;
+          afpCtx->dbPath = pCtx->lockProxyPath;
+        }
+      } else {
+        conchFile->pMethod->xUnlock((sqlite3_file*)conchFile, NO_LOCK);
+      }
+      OSTRACE(("TAKECONCH  %d %s\n", conchFile->h,
+               rc==SQLITE_OK?"ok":"failed"));
+      return rc;
+    } while (1); /* in case we need to retry the :auto: lock file - 
+                 ** we should never get here except via the 'continue' call. */
+  }
+}
+
+/*
+** If pFile holds a lock on a conch file, then release that lock.
+*/
+static int proxyReleaseConch(unixFile *pFile){
+  int rc = SQLITE_OK;         /* Subroutine return code */
+  proxyLockingContext *pCtx;  /* The locking context for the proxy lock */
+  unixFile *conchFile;        /* Name of the conch file */
+
+  pCtx = (proxyLockingContext *)pFile->lockingContext;
+  conchFile = pCtx->conchFile;
+  OSTRACE(("RELEASECONCH  %d for %s pid=%d\n", conchFile->h,
+           (pCtx->lockProxyPath ? pCtx->lockProxyPath : ":auto:"), 
+           getpid()));
+  if( pCtx->conchHeld>0 ){
+    rc = conchFile->pMethod->xUnlock((sqlite3_file*)conchFile, NO_LOCK);
+  }
+  pCtx->conchHeld = 0;
+  OSTRACE(("RELEASECONCH  %d %s\n", conchFile->h,
+           (rc==SQLITE_OK ? "ok" : "failed")));
+  return rc;
+}
+
+/*
+** Given the name of a database file, compute the name of its conch file.
+** Store the conch filename in memory obtained from sqlite3_malloc().
+** Make *pConchPath point to the new name.  Return SQLITE_OK on success
+** or SQLITE_NOMEM if unable to obtain memory.
+**
+** The caller is responsible for ensuring that the allocated memory
+** space is eventually freed.
+**
+** *pConchPath is set to NULL if a memory allocation error occurs.
+*/
+static int proxyCreateConchPathname(char *dbPath, char **pConchPath){
+  int i;                        /* Loop counter */
+  int len = (int)strlen(dbPath); /* Length of database filename - dbPath */
+  char *conchPath;              /* buffer in which to construct conch name */
+
+  /* Allocate space for the conch filename and initialize the name to
+  ** the name of the original database file. */  
+  *pConchPath = conchPath = (char *)sqlite3_malloc(len + 8);
+  if( conchPath==0 ){
+    return SQLITE_NOMEM;
+  }
+  memcpy(conchPath, dbPath, len+1);
+  
+  /* now insert a "." before the last / character */
+  for( i=(len-1); i>=0; i-- ){
+    if( conchPath[i]=='/' ){
+      i++;
+      break;
+    }
+  }
+  conchPath[i]='.';
+  while ( i<len ){
+    conchPath[i+1]=dbPath[i];
+    i++;
+  }
+
+  /* append the "-conch" suffix to the file */
+  memcpy(&conchPath[i+1], "-conch", 7);
+  assert( (int)strlen(conchPath) == len+7 );
+
+  return SQLITE_OK;
+}
+
+
+/* Takes a fully configured proxy locking-style unix file and switches
+** the local lock file path 
+*/
+static int switchLockProxyPath(unixFile *pFile, const char *path) {
+  proxyLockingContext *pCtx = (proxyLockingContext*)pFile->lockingContext;
+  char *oldPath = pCtx->lockProxyPath;
+  int rc = SQLITE_OK;
+
+  if( pFile->eFileLock!=NO_LOCK ){
+    return SQLITE_BUSY;
+  }  
+
+  /* nothing to do if the path is NULL, :auto: or matches the existing path */
+  if( !path || path[0]=='\0' || !strcmp(path, ":auto:") ||
+    (oldPath && !strncmp(oldPath, path, MAXPATHLEN)) ){
+    return SQLITE_OK;
+  }else{
+    unixFile *lockProxy = pCtx->lockProxy;
+    pCtx->lockProxy=NULL;
+    pCtx->conchHeld = 0;
+    if( lockProxy!=NULL ){
+      rc=lockProxy->pMethod->xClose((sqlite3_file *)lockProxy);
+      if( rc ) return rc;
+      sqlite3_free(lockProxy);
+    }
+    sqlite3_free(oldPath);
+    pCtx->lockProxyPath = sqlite3DbStrDup(0, path);
+  }
+  
+  return rc;
+}
+
+/*
+** pFile is a file that has been opened by a prior xOpen call.  dbPath
+** is a string buffer at least MAXPATHLEN+1 characters in size.
+**
+** This routine find the filename associated with pFile and writes it
+** int dbPath.
+*/
+static int proxyGetDbPathForUnixFile(unixFile *pFile, char *dbPath){
+#if defined(__APPLE__)
+  if( pFile->pMethod == &afpIoMethods ){
+    /* afp style keeps a reference to the db path in the filePath field 
+    ** of the struct */
+    assert( (int)strlen((char*)pFile->lockingContext)<=MAXPATHLEN );
+    strlcpy(dbPath, ((afpLockingContext *)pFile->lockingContext)->dbPath, MAXPATHLEN);
+  } else
+#endif
+  if( pFile->pMethod == &dotlockIoMethods ){
+    /* dot lock style uses the locking context to store the dot lock
+    ** file path */
+    int len = strlen((char *)pFile->lockingContext) - strlen(DOTLOCK_SUFFIX);
+    memcpy(dbPath, (char *)pFile->lockingContext, len + 1);
+  }else{
+    /* all other styles use the locking context to store the db file path */
+    assert( strlen((char*)pFile->lockingContext)<=MAXPATHLEN );
+    strlcpy(dbPath, (char *)pFile->lockingContext, MAXPATHLEN);
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Takes an already filled in unix file and alters it so all file locking 
+** will be performed on the local proxy lock file.  The following fields
+** are preserved in the locking context so that they can be restored and 
+** the unix structure properly cleaned up at close time:
+**  ->lockingContext
+**  ->pMethod
+*/
+static int proxyTransformUnixFile(unixFile *pFile, const char *path) {
+  proxyLockingContext *pCtx;
+  char dbPath[MAXPATHLEN+1];       /* Name of the database file */
+  char *lockPath=NULL;
+  int rc = SQLITE_OK;
+  
+  if( pFile->eFileLock!=NO_LOCK ){
+    return SQLITE_BUSY;
+  }
+  proxyGetDbPathForUnixFile(pFile, dbPath);
+  if( !path || path[0]=='\0' || !strcmp(path, ":auto:") ){
+    lockPath=NULL;
+  }else{
+    lockPath=(char *)path;
+  }
+  
+  OSTRACE(("TRANSPROXY  %d for %s pid=%d\n", pFile->h,
+           (lockPath ? lockPath : ":auto:"), getpid()));
+
+  pCtx = sqlite3_malloc( sizeof(*pCtx) );
+  if( pCtx==0 ){
+    return SQLITE_NOMEM;
+  }
+  memset(pCtx, 0, sizeof(*pCtx));
+
+  rc = proxyCreateConchPathname(dbPath, &pCtx->conchFilePath);
+  if( rc==SQLITE_OK ){
+    rc = proxyCreateUnixFile(pCtx->conchFilePath, &pCtx->conchFile, 0);
+    if( rc==SQLITE_CANTOPEN && ((pFile->openFlags&O_RDWR) == 0) ){
+      /* if (a) the open flags are not O_RDWR, (b) the conch isn't there, and
+      ** (c) the file system is read-only, then enable no-locking access.
+      ** Ugh, since O_RDONLY==0x0000 we test for !O_RDWR since unixOpen asserts
+      ** that openFlags will have only one of O_RDONLY or O_RDWR.
+      */
+      struct statfs fsInfo;
+      struct stat conchInfo;
+      int goLockless = 0;
+
+      if( osStat(pCtx->conchFilePath, &conchInfo) == -1 ) {
+        int err = errno;
+        if( (err==ENOENT) && (statfs(dbPath, &fsInfo) != -1) ){
+          goLockless = (fsInfo.f_flags&MNT_RDONLY) == MNT_RDONLY;
+        }
+      }
+      if( goLockless ){
+        pCtx->conchHeld = -1; /* read only FS/ lockless */
+        rc = SQLITE_OK;
+      }
+    }
+  }  
+  if( rc==SQLITE_OK && lockPath ){
+    pCtx->lockProxyPath = sqlite3DbStrDup(0, lockPath);
+  }
+
+  if( rc==SQLITE_OK ){
+    pCtx->dbPath = sqlite3DbStrDup(0, dbPath);
+    if( pCtx->dbPath==NULL ){
+      rc = SQLITE_NOMEM;
+    }
+  }
+  if( rc==SQLITE_OK ){
+    /* all memory is allocated, proxys are created and assigned, 
+    ** switch the locking context and pMethod then return.
+    */
+    pCtx->oldLockingContext = pFile->lockingContext;
+    pFile->lockingContext = pCtx;
+    pCtx->pOldMethod = pFile->pMethod;
+    pFile->pMethod = &proxyIoMethods;
+  }else{
+    if( pCtx->conchFile ){ 
+      pCtx->conchFile->pMethod->xClose((sqlite3_file *)pCtx->conchFile);
+      sqlite3_free(pCtx->conchFile);
+    }
+    sqlite3DbFree(0, pCtx->lockProxyPath);
+    sqlite3_free(pCtx->conchFilePath); 
+    sqlite3_free(pCtx);
+  }
+  OSTRACE(("TRANSPROXY  %d %s\n", pFile->h,
+           (rc==SQLITE_OK ? "ok" : "failed")));
+  return rc;
+}
+
+
+/*
+** This routine handles sqlite3_file_control() calls that are specific
+** to proxy locking.
+*/
+static int proxyFileControl(sqlite3_file *id, int op, void *pArg){
+  switch( op ){
+    case SQLITE_GET_LOCKPROXYFILE: {
+      unixFile *pFile = (unixFile*)id;
+      if( pFile->pMethod == &proxyIoMethods ){
+        proxyLockingContext *pCtx = (proxyLockingContext*)pFile->lockingContext;
+        proxyTakeConch(pFile);
+        if( pCtx->lockProxyPath ){
+          *(const char **)pArg = pCtx->lockProxyPath;
+        }else{
+          *(const char **)pArg = ":auto: (not held)";
+        }
+      } else {
+        *(const char **)pArg = NULL;
+      }
+      return SQLITE_OK;
+    }
+    case SQLITE_SET_LOCKPROXYFILE: {
+      unixFile *pFile = (unixFile*)id;
+      int rc = SQLITE_OK;
+      int isProxyStyle = (pFile->pMethod == &proxyIoMethods);
+      if( pArg==NULL || (const char *)pArg==0 ){
+        if( isProxyStyle ){
+          /* turn off proxy locking - not supported */
+          rc = SQLITE_ERROR /*SQLITE_PROTOCOL? SQLITE_MISUSE?*/;
+        }else{
+          /* turn off proxy locking - already off - NOOP */
+          rc = SQLITE_OK;
+        }
+      }else{
+        const char *proxyPath = (const char *)pArg;
+        if( isProxyStyle ){
+          proxyLockingContext *pCtx = 
+            (proxyLockingContext*)pFile->lockingContext;
+          if( !strcmp(pArg, ":auto:") 
+           || (pCtx->lockProxyPath &&
+               !strncmp(pCtx->lockProxyPath, proxyPath, MAXPATHLEN))
+          ){
+            rc = SQLITE_OK;
+          }else{
+            rc = switchLockProxyPath(pFile, proxyPath);
+          }
+        }else{
+          /* turn on proxy file locking */
+          rc = proxyTransformUnixFile(pFile, proxyPath);
+        }
+      }
+      return rc;
+    }
+    default: {
+      assert( 0 );  /* The call assures that only valid opcodes are sent */
+    }
+  }
+  /*NOTREACHED*/
+  return SQLITE_ERROR;
+}
+
+/*
+** Within this division (the proxying locking implementation) the procedures
+** above this point are all utilities.  The lock-related methods of the
+** proxy-locking sqlite3_io_method object follow.
+*/
+
+
+/*
+** This routine checks if there is a RESERVED lock held on the specified
+** file by this or any other process. If such a lock is held, set *pResOut
+** to a non-zero value otherwise *pResOut is set to zero.  The return value
+** is set to SQLITE_OK unless an I/O error occurs during lock checking.
+*/
+static int proxyCheckReservedLock(sqlite3_file *id, int *pResOut) {
+  unixFile *pFile = (unixFile*)id;
+  int rc = proxyTakeConch(pFile);
+  if( rc==SQLITE_OK ){
+    proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext;
+    if( pCtx->conchHeld>0 ){
+      unixFile *proxy = pCtx->lockProxy;
+      return proxy->pMethod->xCheckReservedLock((sqlite3_file*)proxy, pResOut);
+    }else{ /* conchHeld < 0 is lockless */
+      pResOut=0;
+    }
+  }
+  return rc;
+}
+
+/*
+** Lock the file with the lock specified by parameter eFileLock - one
+** of the following:
+**
+**     (1) SHARED_LOCK
+**     (2) RESERVED_LOCK
+**     (3) PENDING_LOCK
+**     (4) EXCLUSIVE_LOCK
+**
+** Sometimes when requesting one lock state, additional lock states
+** are inserted in between.  The locking might fail on one of the later
+** transitions leaving the lock state different from what it started but
+** still short of its goal.  The following chart shows the allowed
+** transitions and the inserted intermediate states:
+**
+**    UNLOCKED -> SHARED
+**    SHARED -> RESERVED
+**    SHARED -> (PENDING) -> EXCLUSIVE
+**    RESERVED -> (PENDING) -> EXCLUSIVE
+**    PENDING -> EXCLUSIVE
+**
+** This routine will only increase a lock.  Use the sqlite3OsUnlock()
+** routine to lower a locking level.
+*/
+static int proxyLock(sqlite3_file *id, int eFileLock) {
+  unixFile *pFile = (unixFile*)id;
+  int rc = proxyTakeConch(pFile);
+  if( rc==SQLITE_OK ){
+    proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext;
+    if( pCtx->conchHeld>0 ){
+      unixFile *proxy = pCtx->lockProxy;
+      rc = proxy->pMethod->xLock((sqlite3_file*)proxy, eFileLock);
+      pFile->eFileLock = proxy->eFileLock;
+    }else{
+      /* conchHeld < 0 is lockless */
+    }
+  }
+  return rc;
+}
+
+
+/*
+** Lower the locking level on file descriptor pFile to eFileLock.  eFileLock
+** must be either NO_LOCK or SHARED_LOCK.
+**
+** If the locking level of the file descriptor is already at or below
+** the requested locking level, this routine is a no-op.
+*/
+static int proxyUnlock(sqlite3_file *id, int eFileLock) {
+  unixFile *pFile = (unixFile*)id;
+  int rc = proxyTakeConch(pFile);
+  if( rc==SQLITE_OK ){
+    proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext;
+    if( pCtx->conchHeld>0 ){
+      unixFile *proxy = pCtx->lockProxy;
+      rc = proxy->pMethod->xUnlock((sqlite3_file*)proxy, eFileLock);
+      pFile->eFileLock = proxy->eFileLock;
+    }else{
+      /* conchHeld < 0 is lockless */
+    }
+  }
+  return rc;
+}
+
+/*
+** Close a file that uses proxy locks.
+*/
+static int proxyClose(sqlite3_file *id) {
+  if( id ){
+    unixFile *pFile = (unixFile*)id;
+    proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext;
+    unixFile *lockProxy = pCtx->lockProxy;
+    unixFile *conchFile = pCtx->conchFile;
+    int rc = SQLITE_OK;
+    
+    if( lockProxy ){
+      rc = lockProxy->pMethod->xUnlock((sqlite3_file*)lockProxy, NO_LOCK);
+      if( rc ) return rc;
+      rc = lockProxy->pMethod->xClose((sqlite3_file*)lockProxy);
+      if( rc ) return rc;
+      sqlite3_free(lockProxy);
+      pCtx->lockProxy = 0;
+    }
+    if( conchFile ){
+      if( pCtx->conchHeld ){
+        rc = proxyReleaseConch(pFile);
+        if( rc ) return rc;
+      }
+      rc = conchFile->pMethod->xClose((sqlite3_file*)conchFile);
+      if( rc ) return rc;
+      sqlite3_free(conchFile);
+    }
+    sqlite3DbFree(0, pCtx->lockProxyPath);
+    sqlite3_free(pCtx->conchFilePath);
+    sqlite3DbFree(0, pCtx->dbPath);
+    /* restore the original locking context and pMethod then close it */
+    pFile->lockingContext = pCtx->oldLockingContext;
+    pFile->pMethod = pCtx->pOldMethod;
+    sqlite3_free(pCtx);
+    return pFile->pMethod->xClose(id);
+  }
+  return SQLITE_OK;
+}
+
+
+
+#endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */
+/*
+** The proxy locking style is intended for use with AFP filesystems.
+** And since AFP is only supported on MacOSX, the proxy locking is also
+** restricted to MacOSX.
+** 
+**
+******************* End of the proxy lock implementation **********************
+******************************************************************************/
+
+/*
+** Initialize the operating system interface.
+**
+** This routine registers all VFS implementations for unix-like operating
+** systems.  This routine, and the sqlite3_os_end() routine that follows,
+** should be the only routines in this file that are visible from other
+** files.
+**
+** This routine is called once during SQLite initialization and by a
+** single thread.  The memory allocation and mutex subsystems have not
+** necessarily been initialized when this routine is called, and so they
+** should not be used.
+*/
+SQLITE_API int sqlite3_os_init(void){ 
+  /* 
+  ** The following macro defines an initializer for an sqlite3_vfs object.
+  ** The name of the VFS is NAME.  The pAppData is a pointer to a pointer
+  ** to the "finder" function.  (pAppData is a pointer to a pointer because
+  ** silly C90 rules prohibit a void* from being cast to a function pointer
+  ** and so we have to go through the intermediate pointer to avoid problems
+  ** when compiling with -pedantic-errors on GCC.)
+  **
+  ** The FINDER parameter to this macro is the name of the pointer to the
+  ** finder-function.  The finder-function returns a pointer to the
+  ** sqlite_io_methods object that implements the desired locking
+  ** behaviors.  See the division above that contains the IOMETHODS
+  ** macro for addition information on finder-functions.
+  **
+  ** Most finders simply return a pointer to a fixed sqlite3_io_methods
+  ** object.  But the "autolockIoFinder" available on MacOSX does a little
+  ** more than that; it looks at the filesystem type that hosts the 
+  ** database file and tries to choose an locking method appropriate for
+  ** that filesystem time.
+  */
+  #define UNIXVFS(VFSNAME, FINDER) {                        \
+    3,                    /* iVersion */                    \
+    sizeof(unixFile),     /* szOsFile */                    \
+    MAX_PATHNAME,         /* mxPathname */                  \
+    0,                    /* pNext */                       \
+    VFSNAME,              /* zName */                       \
+    (void*)&FINDER,       /* pAppData */                    \
+    unixOpen,             /* xOpen */                       \
+    unixDelete,           /* xDelete */                     \
+    unixAccess,           /* xAccess */                     \
+    unixFullPathname,     /* xFullPathname */               \
+    unixDlOpen,           /* xDlOpen */                     \
+    unixDlError,          /* xDlError */                    \
+    unixDlSym,            /* xDlSym */                      \
+    unixDlClose,          /* xDlClose */                    \
+    unixRandomness,       /* xRandomness */                 \
+    unixSleep,            /* xSleep */                      \
+    unixCurrentTime,      /* xCurrentTime */                \
+    unixGetLastError,     /* xGetLastError */               \
+    unixCurrentTimeInt64, /* xCurrentTimeInt64 */           \
+    unixSetSystemCall,    /* xSetSystemCall */              \
+    unixGetSystemCall,    /* xGetSystemCall */              \
+    unixNextSystemCall,   /* xNextSystemCall */             \
+  }
+
+  /*
+  ** All default VFSes for unix are contained in the following array.
+  **
+  ** Note that the sqlite3_vfs.pNext field of the VFS object is modified
+  ** by the SQLite core when the VFS is registered.  So the following
+  ** array cannot be const.
+  */
+  static sqlite3_vfs aVfs[] = {
+#if SQLITE_ENABLE_LOCKING_STYLE && (OS_VXWORKS || defined(__APPLE__))
+    UNIXVFS("unix",          autolockIoFinder ),
+#else
+    UNIXVFS("unix",          posixIoFinder ),
+#endif
+    UNIXVFS("unix-none",     nolockIoFinder ),
+    UNIXVFS("unix-dotfile",  dotlockIoFinder ),
+    UNIXVFS("unix-excl",     posixIoFinder ),
+#if OS_VXWORKS
+    UNIXVFS("unix-namedsem", semIoFinder ),
+#endif
+#if SQLITE_ENABLE_LOCKING_STYLE
+    UNIXVFS("unix-posix",    posixIoFinder ),
+#if !OS_VXWORKS
+    UNIXVFS("unix-flock",    flockIoFinder ),
+#endif
+#endif
+#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
+    UNIXVFS("unix-afp",      afpIoFinder ),
+    UNIXVFS("unix-nfs",      nfsIoFinder ),
+    UNIXVFS("unix-proxy",    proxyIoFinder ),
+#endif
+  };
+  unsigned int i;          /* Loop counter */
+
+  /* Double-check that the aSyscall[] array has been constructed
+  ** correctly.  See ticket [bb3a86e890c8e96ab] */
+  assert( ArraySize(aSyscall)==16 );
+
+  /* Register all VFSes defined in the aVfs[] array */
+  for(i=0; i<(sizeof(aVfs)/sizeof(sqlite3_vfs)); i++){
+    sqlite3_vfs_register(&aVfs[i], i==0);
+  }
+  return SQLITE_OK; 
+}
+
+/*
+** Shutdown the operating system interface.
+**
+** Some operating systems might need to do some cleanup in this routine,
+** to release dynamically allocated objects.  But not on unix.
+** This routine is a no-op for unix.
+*/
+SQLITE_API int sqlite3_os_end(void){ 
+  return SQLITE_OK; 
+}
+ 
+#endif /* SQLITE_OS_UNIX */
+
+/************** End of os_unix.c *********************************************/
+/************** Begin file os_win.c ******************************************/
+/*
+** 2004 May 22
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains code that is specific to windows.
+*/
+#if SQLITE_OS_WIN               /* This file is used for windows only */
+
+
+/*
+** A Note About Memory Allocation:
+**
+** This driver uses malloc()/free() directly rather than going through
+** the SQLite-wrappers sqlite3_malloc()/sqlite3_free().  Those wrappers
+** are designed for use on embedded systems where memory is scarce and
+** malloc failures happen frequently.  Win32 does not typically run on
+** embedded systems, and when it does the developers normally have bigger
+** problems to worry about than running out of memory.  So there is not
+** a compelling need to use the wrappers.
+**
+** But there is a good reason to not use the wrappers.  If we use the
+** wrappers then we will get simulated malloc() failures within this
+** driver.  And that causes all kinds of problems for our tests.  We
+** could enhance SQLite to deal with simulated malloc failures within
+** the OS driver, but the code to deal with those failure would not
+** be exercised on Linux (which does not need to malloc() in the driver)
+** and so we would have difficulty writing coverage tests for that
+** code.  Better to leave the code out, we think.
+**
+** The point of this discussion is as follows:  When creating a new
+** OS layer for an embedded system, if you use this file as an example,
+** avoid the use of malloc()/free().  Those routines work ok on windows
+** desktops but not so well in embedded systems.
+*/
+
+#include <winbase.h>
+
+#ifdef __CYGWIN__
+# include <sys/cygwin.h>
+#endif
+
+/*
+** Macros used to determine whether or not to use threads.
+*/
+#if defined(THREADSAFE) && THREADSAFE
+# define SQLITE_W32_THREADS 1
+#endif
+
+/*
+** Include code that is common to all os_*.c files
+*/
+/************** Include os_common.h in the middle of os_win.c ****************/
+/************** Begin file os_common.h ***************************************/
+/*
+** 2004 May 22
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains macros and a little bit of code that is common to
+** all of the platform-specific files (os_*.c) and is #included into those
+** files.
+**
+** This file should be #included by the os_*.c files only.  It is not a
+** general purpose header file.
+*/
+#ifndef _OS_COMMON_H_
+#define _OS_COMMON_H_
+
+/*
+** At least two bugs have slipped in because we changed the MEMORY_DEBUG
+** macro to SQLITE_DEBUG and some older makefiles have not yet made the
+** switch.  The following code should catch this problem at compile-time.
+*/
+#ifdef MEMORY_DEBUG
+# error "The MEMORY_DEBUG macro is obsolete.  Use SQLITE_DEBUG instead."
+#endif
+
+#ifdef SQLITE_DEBUG
+SQLITE_PRIVATE int sqlite3OSTrace = 0;
+#define OSTRACE(X)          if( sqlite3OSTrace ) sqlite3DebugPrintf X
+#else
+#define OSTRACE(X)
+#endif
+
+/*
+** Macros for performance tracing.  Normally turned off.  Only works
+** on i486 hardware.
+*/
+#ifdef SQLITE_PERFORMANCE_TRACE
+
+/* 
+** hwtime.h contains inline assembler code for implementing 
+** high-performance timing routines.
+*/
+/************** Include hwtime.h in the middle of os_common.h ****************/
+/************** Begin file hwtime.h ******************************************/
+/*
+** 2008 May 27
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains inline asm code for retrieving "high-performance"
+** counters for x86 class CPUs.
+*/
+#ifndef _HWTIME_H_
+#define _HWTIME_H_
+
+/*
+** The following routine only works on pentium-class (or newer) processors.
+** It uses the RDTSC opcode to read the cycle count value out of the
+** processor and returns that value.  This can be used for high-res
+** profiling.
+*/
+#if (defined(__GNUC__) || defined(_MSC_VER)) && \
+      (defined(i386) || defined(__i386__) || defined(_M_IX86))
+
+  #if defined(__GNUC__)
+
+  __inline__ sqlite_uint64 sqlite3Hwtime(void){
+     unsigned int lo, hi;
+     __asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi));
+     return (sqlite_uint64)hi << 32 | lo;
+  }
+
+  #elif defined(_MSC_VER)
+
+  __declspec(naked) __inline sqlite_uint64 __cdecl sqlite3Hwtime(void){
+     __asm {
+        rdtsc
+        ret       ; return value at EDX:EAX
+     }
+  }
+
+  #endif
+
+#elif (defined(__GNUC__) && defined(__x86_64__))
+
+  __inline__ sqlite_uint64 sqlite3Hwtime(void){
+      unsigned long val;
+      __asm__ __volatile__ ("rdtsc" : "=A" (val));
+      return val;
+  }
+ 
+#elif (defined(__GNUC__) && defined(__ppc__))
+
+  __inline__ sqlite_uint64 sqlite3Hwtime(void){
+      unsigned long long retval;
+      unsigned long junk;
+      __asm__ __volatile__ ("\n\
+          1:      mftbu   %1\n\
+                  mftb    %L0\n\
+                  mftbu   %0\n\
+                  cmpw    %0,%1\n\
+                  bne     1b"
+                  : "=r" (retval), "=r" (junk));
+      return retval;
+  }
+
+#else
+
+  #error Need implementation of sqlite3Hwtime() for your platform.
+
+  /*
+  ** To compile without implementing sqlite3Hwtime() for your platform,
+  ** you can remove the above #error and use the following
+  ** stub function.  You will lose timing support for many
+  ** of the debugging and testing utilities, but it should at
+  ** least compile and run.
+  */
+SQLITE_PRIVATE   sqlite_uint64 sqlite3Hwtime(void){ return ((sqlite_uint64)0); }
+
+#endif
+
+#endif /* !defined(_HWTIME_H_) */
+
+/************** End of hwtime.h **********************************************/
+/************** Continuing where we left off in os_common.h ******************/
+
+static sqlite_uint64 g_start;
+static sqlite_uint64 g_elapsed;
+#define TIMER_START       g_start=sqlite3Hwtime()
+#define TIMER_END         g_elapsed=sqlite3Hwtime()-g_start
+#define TIMER_ELAPSED     g_elapsed
+#else
+#define TIMER_START
+#define TIMER_END
+#define TIMER_ELAPSED     ((sqlite_uint64)0)
+#endif
+
+/*
+** If we compile with the SQLITE_TEST macro set, then the following block
+** of code will give us the ability to simulate a disk I/O error.  This
+** is used for testing the I/O recovery logic.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_io_error_hit = 0;            /* Total number of I/O Errors */
+SQLITE_API int sqlite3_io_error_hardhit = 0;        /* Number of non-benign errors */
+SQLITE_API int sqlite3_io_error_pending = 0;        /* Count down to first I/O error */
+SQLITE_API int sqlite3_io_error_persist = 0;        /* True if I/O errors persist */
+SQLITE_API int sqlite3_io_error_benign = 0;         /* True if errors are benign */
+SQLITE_API int sqlite3_diskfull_pending = 0;
+SQLITE_API int sqlite3_diskfull = 0;
+#define SimulateIOErrorBenign(X) sqlite3_io_error_benign=(X)
+#define SimulateIOError(CODE)  \
+  if( (sqlite3_io_error_persist && sqlite3_io_error_hit) \
+       || sqlite3_io_error_pending-- == 1 )  \
+              { local_ioerr(); CODE; }
+static void local_ioerr(){
+  IOTRACE(("IOERR\n"));
+  sqlite3_io_error_hit++;
+  if( !sqlite3_io_error_benign ) sqlite3_io_error_hardhit++;
+}
+#define SimulateDiskfullError(CODE) \
+   if( sqlite3_diskfull_pending ){ \
+     if( sqlite3_diskfull_pending == 1 ){ \
+       local_ioerr(); \
+       sqlite3_diskfull = 1; \
+       sqlite3_io_error_hit = 1; \
+       CODE; \
+     }else{ \
+       sqlite3_diskfull_pending--; \
+     } \
+   }
+#else
+#define SimulateIOErrorBenign(X)
+#define SimulateIOError(A)
+#define SimulateDiskfullError(A)
+#endif
+
+/*
+** When testing, keep a count of the number of open files.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_open_file_count = 0;
+#define OpenCounter(X)  sqlite3_open_file_count+=(X)
+#else
+#define OpenCounter(X)
+#endif
+
+#endif /* !defined(_OS_COMMON_H_) */
+
+/************** End of os_common.h *******************************************/
+/************** Continuing where we left off in os_win.c *********************/
+
+/*
+** Some microsoft compilers lack this definition.
+*/
+#ifndef INVALID_FILE_ATTRIBUTES
+# define INVALID_FILE_ATTRIBUTES ((DWORD)-1) 
+#endif
+
+/*
+** Determine if we are dealing with WindowsCE - which has a much
+** reduced API.
+*/
+#if SQLITE_OS_WINCE
+# define AreFileApisANSI() 1
+# define FormatMessageW(a,b,c,d,e,f,g) 0
+#endif
+
+/* Forward references */
+typedef struct winShm winShm;           /* A connection to shared-memory */
+typedef struct winShmNode winShmNode;   /* A region of shared-memory */
+
+/*
+** WinCE lacks native support for file locking so we have to fake it
+** with some code of our own.
+*/
+#if SQLITE_OS_WINCE
+typedef struct winceLock {
+  int nReaders;       /* Number of reader locks obtained */
+  BOOL bPending;      /* Indicates a pending lock has been obtained */
+  BOOL bReserved;     /* Indicates a reserved lock has been obtained */
+  BOOL bExclusive;    /* Indicates an exclusive lock has been obtained */
+} winceLock;
+#endif
+
+/*
+** The winFile structure is a subclass of sqlite3_file* specific to the win32
+** portability layer.
+*/
+typedef struct winFile winFile;
+struct winFile {
+  const sqlite3_io_methods *pMethod; /*** Must be first ***/
+  sqlite3_vfs *pVfs;      /* The VFS used to open this file */
+  HANDLE h;               /* Handle for accessing the file */
+  unsigned char locktype; /* Type of lock currently held on this file */
+  short sharedLockByte;   /* Randomly chosen byte used as a shared lock */
+  DWORD lastErrno;        /* The Windows errno from the last I/O error */
+  DWORD sectorSize;       /* Sector size of the device file is on */
+  winShm *pShm;           /* Instance of shared memory on this file */
+  const char *zPath;      /* Full pathname of this file */
+  int szChunk;            /* Chunk size configured by FCNTL_CHUNK_SIZE */
+#if SQLITE_OS_WINCE
+  WCHAR *zDeleteOnClose;  /* Name of file to delete when closing */
+  HANDLE hMutex;          /* Mutex used to control access to shared lock */  
+  HANDLE hShared;         /* Shared memory segment used for locking */
+  winceLock local;        /* Locks obtained by this instance of winFile */
+  winceLock *shared;      /* Global shared lock memory for the file  */
+#endif
+};
+
+/*
+** Forward prototypes.
+*/
+static int getSectorSize(
+    sqlite3_vfs *pVfs,
+    const char *zRelative     /* UTF-8 file name */
+);
+
+/*
+** The following variable is (normally) set once and never changes
+** thereafter.  It records whether the operating system is Win95
+** or WinNT.
+**
+** 0:   Operating system unknown.
+** 1:   Operating system is Win95.
+** 2:   Operating system is WinNT.
+**
+** In order to facilitate testing on a WinNT system, the test fixture
+** can manually set this value to 1 to emulate Win98 behavior.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_os_type = 0;
+#else
+static int sqlite3_os_type = 0;
+#endif
+
+/*
+** Return true (non-zero) if we are running under WinNT, Win2K, WinXP,
+** or WinCE.  Return false (zero) for Win95, Win98, or WinME.
+**
+** Here is an interesting observation:  Win95, Win98, and WinME lack
+** the LockFileEx() API.  But we can still statically link against that
+** API as long as we don't call it when running Win95/98/ME.  A call to
+** this routine is used to determine if the host is Win95/98/ME or
+** WinNT/2K/XP so that we will know whether or not we can safely call
+** the LockFileEx() API.
+*/
+#if SQLITE_OS_WINCE
+# define isNT()  (1)
+#else
+  static int isNT(void){
+    if( sqlite3_os_type==0 ){
+      OSVERSIONINFO sInfo;
+      sInfo.dwOSVersionInfoSize = sizeof(sInfo);
+      GetVersionEx(&sInfo);
+      sqlite3_os_type = sInfo.dwPlatformId==VER_PLATFORM_WIN32_NT ? 2 : 1;
+    }
+    return sqlite3_os_type==2;
+  }
+#endif /* SQLITE_OS_WINCE */
+
+/*
+** Convert a UTF-8 string to microsoft unicode (UTF-16?). 
+**
+** Space to hold the returned string is obtained from malloc.
+*/
+static WCHAR *utf8ToUnicode(const char *zFilename){
+  int nChar;
+  WCHAR *zWideFilename;
+
+  nChar = MultiByteToWideChar(CP_UTF8, 0, zFilename, -1, NULL, 0);
+  zWideFilename = malloc( nChar*sizeof(zWideFilename[0]) );
+  if( zWideFilename==0 ){
+    return 0;
+  }
+  nChar = MultiByteToWideChar(CP_UTF8, 0, zFilename, -1, zWideFilename, nChar);
+  if( nChar==0 ){
+    free(zWideFilename);
+    zWideFilename = 0;
+  }
+  return zWideFilename;
+}
+
+/*
+** Convert microsoft unicode to UTF-8.  Space to hold the returned string is
+** obtained from malloc().
+*/
+static char *unicodeToUtf8(const WCHAR *zWideFilename){
+  int nByte;
+  char *zFilename;
+
+  nByte = WideCharToMultiByte(CP_UTF8, 0, zWideFilename, -1, 0, 0, 0, 0);
+  zFilename = malloc( nByte );
+  if( zFilename==0 ){
+    return 0;
+  }
+  nByte = WideCharToMultiByte(CP_UTF8, 0, zWideFilename, -1, zFilename, nByte,
+                              0, 0);
+  if( nByte == 0 ){
+    free(zFilename);
+    zFilename = 0;
+  }
+  return zFilename;
+}
+
+/*
+** Convert an ansi string to microsoft unicode, based on the
+** current codepage settings for file apis.
+** 
+** Space to hold the returned string is obtained
+** from malloc.
+*/
+static WCHAR *mbcsToUnicode(const char *zFilename){
+  int nByte;
+  WCHAR *zMbcsFilename;
+  int codepage = AreFileApisANSI() ? CP_ACP : CP_OEMCP;
+
+  nByte = MultiByteToWideChar(codepage, 0, zFilename, -1, NULL,0)*sizeof(WCHAR);
+  zMbcsFilename = malloc( nByte*sizeof(zMbcsFilename[0]) );
+  if( zMbcsFilename==0 ){
+    return 0;
+  }
+  nByte = MultiByteToWideChar(codepage, 0, zFilename, -1, zMbcsFilename, nByte);
+  if( nByte==0 ){
+    free(zMbcsFilename);
+    zMbcsFilename = 0;
+  }
+  return zMbcsFilename;
+}
+
+/*
+** Convert microsoft unicode to multibyte character string, based on the
+** user's Ansi codepage.
+**
+** Space to hold the returned string is obtained from
+** malloc().
+*/
+static char *unicodeToMbcs(const WCHAR *zWideFilename){
+  int nByte;
+  char *zFilename;
+  int codepage = AreFileApisANSI() ? CP_ACP : CP_OEMCP;
+
+  nByte = WideCharToMultiByte(codepage, 0, zWideFilename, -1, 0, 0, 0, 0);
+  zFilename = malloc( nByte );
+  if( zFilename==0 ){
+    return 0;
+  }
+  nByte = WideCharToMultiByte(codepage, 0, zWideFilename, -1, zFilename, nByte,
+                              0, 0);
+  if( nByte == 0 ){
+    free(zFilename);
+    zFilename = 0;
+  }
+  return zFilename;
+}
+
+/*
+** Convert multibyte character string to UTF-8.  Space to hold the
+** returned string is obtained from malloc().
+*/
+SQLITE_API char *sqlite3_win32_mbcs_to_utf8(const char *zFilename){
+  char *zFilenameUtf8;
+  WCHAR *zTmpWide;
+
+  zTmpWide = mbcsToUnicode(zFilename);
+  if( zTmpWide==0 ){
+    return 0;
+  }
+  zFilenameUtf8 = unicodeToUtf8(zTmpWide);
+  free(zTmpWide);
+  return zFilenameUtf8;
+}
+
+/*
+** Convert UTF-8 to multibyte character string.  Space to hold the 
+** returned string is obtained from malloc().
+*/
+static char *utf8ToMbcs(const char *zFilename){
+  char *zFilenameMbcs;
+  WCHAR *zTmpWide;
+
+  zTmpWide = utf8ToUnicode(zFilename);
+  if( zTmpWide==0 ){
+    return 0;
+  }
+  zFilenameMbcs = unicodeToMbcs(zTmpWide);
+  free(zTmpWide);
+  return zFilenameMbcs;
+}
+
+#if SQLITE_OS_WINCE
+/*************************************************************************
+** This section contains code for WinCE only.
+*/
+/*
+** WindowsCE does not have a localtime() function.  So create a
+** substitute.
+*/
+struct tm *__cdecl localtime(const time_t *t)
+{
+  static struct tm y;
+  FILETIME uTm, lTm;
+  SYSTEMTIME pTm;
+  sqlite3_int64 t64;
+  t64 = *t;
+  t64 = (t64 + 11644473600)*10000000;
+  uTm.dwLowDateTime = (DWORD)(t64 & 0xFFFFFFFF);
+  uTm.dwHighDateTime= (DWORD)(t64 >> 32);
+  FileTimeToLocalFileTime(&uTm,&lTm);
+  FileTimeToSystemTime(&lTm,&pTm);
+  y.tm_year = pTm.wYear - 1900;
+  y.tm_mon = pTm.wMonth - 1;
+  y.tm_wday = pTm.wDayOfWeek;
+  y.tm_mday = pTm.wDay;
+  y.tm_hour = pTm.wHour;
+  y.tm_min = pTm.wMinute;
+  y.tm_sec = pTm.wSecond;
+  return &y;
+}
+
+/* This will never be called, but defined to make the code compile */
+#define GetTempPathA(a,b)
+
+#define LockFile(a,b,c,d,e)       winceLockFile(&a, b, c, d, e)
+#define UnlockFile(a,b,c,d,e)     winceUnlockFile(&a, b, c, d, e)
+#define LockFileEx(a,b,c,d,e,f)   winceLockFileEx(&a, b, c, d, e, f)
+
+#define HANDLE_TO_WINFILE(a) (winFile*)&((char*)a)[-(int)offsetof(winFile,h)]
+
+/*
+** Acquire a lock on the handle h
+*/
+static void winceMutexAcquire(HANDLE h){
+   DWORD dwErr;
+   do {
+     dwErr = WaitForSingleObject(h, INFINITE);
+   } while (dwErr != WAIT_OBJECT_0 && dwErr != WAIT_ABANDONED);
+}
+/*
+** Release a lock acquired by winceMutexAcquire()
+*/
+#define winceMutexRelease(h) ReleaseMutex(h)
+
+/*
+** Create the mutex and shared memory used for locking in the file
+** descriptor pFile
+*/
+static BOOL winceCreateLock(const char *zFilename, winFile *pFile){
+  WCHAR *zTok;
+  WCHAR *zName = utf8ToUnicode(zFilename);
+  BOOL bInit = TRUE;
+
+  /* Initialize the local lockdata */
+  ZeroMemory(&pFile->local, sizeof(pFile->local));
+
+  /* Replace the backslashes from the filename and lowercase it
+  ** to derive a mutex name. */
+  zTok = CharLowerW(zName);
+  for (;*zTok;zTok++){
+    if (*zTok == '\\') *zTok = '_';
+  }
+
+  /* Create/open the named mutex */
+  pFile->hMutex = CreateMutexW(NULL, FALSE, zName);
+  if (!pFile->hMutex){
+    pFile->lastErrno = GetLastError();
+    free(zName);
+    return FALSE;
+  }
+
+  /* Acquire the mutex before continuing */
+  winceMutexAcquire(pFile->hMutex);
+  
+  /* Since the names of named mutexes, semaphores, file mappings etc are 
+  ** case-sensitive, take advantage of that by uppercasing the mutex name
+  ** and using that as the shared filemapping name.
+  */
+  CharUpperW(zName);
+  pFile->hShared = CreateFileMappingW(INVALID_HANDLE_VALUE, NULL,
+                                       PAGE_READWRITE, 0, sizeof(winceLock),
+                                       zName);  
+
+  /* Set a flag that indicates we're the first to create the memory so it 
+  ** must be zero-initialized */
+  if (GetLastError() == ERROR_ALREADY_EXISTS){
+    bInit = FALSE;
+  }
+
+  free(zName);
+
+  /* If we succeeded in making the shared memory handle, map it. */
+  if (pFile->hShared){
+    pFile->shared = (winceLock*)MapViewOfFile(pFile->hShared, 
+             FILE_MAP_READ|FILE_MAP_WRITE, 0, 0, sizeof(winceLock));
+    /* If mapping failed, close the shared memory handle and erase it */
+    if (!pFile->shared){
+      pFile->lastErrno = GetLastError();
+      CloseHandle(pFile->hShared);
+      pFile->hShared = NULL;
+    }
+  }
+
+  /* If shared memory could not be created, then close the mutex and fail */
+  if (pFile->hShared == NULL){
+    winceMutexRelease(pFile->hMutex);
+    CloseHandle(pFile->hMutex);
+    pFile->hMutex = NULL;
+    return FALSE;
+  }
+  
+  /* Initialize the shared memory if we're supposed to */
+  if (bInit) {
+    ZeroMemory(pFile->shared, sizeof(winceLock));
+  }
+
+  winceMutexRelease(pFile->hMutex);
+  return TRUE;
+}
+
+/*
+** Destroy the part of winFile that deals with wince locks
+*/
+static void winceDestroyLock(winFile *pFile){
+  if (pFile->hMutex){
+    /* Acquire the mutex */
+    winceMutexAcquire(pFile->hMutex);
+
+    /* The following blocks should probably assert in debug mode, but they
+       are to cleanup in case any locks remained open */
+    if (pFile->local.nReaders){
+      pFile->shared->nReaders --;
+    }
+    if (pFile->local.bReserved){
+      pFile->shared->bReserved = FALSE;
+    }
+    if (pFile->local.bPending){
+      pFile->shared->bPending = FALSE;
+    }
+    if (pFile->local.bExclusive){
+      pFile->shared->bExclusive = FALSE;
+    }
+
+    /* De-reference and close our copy of the shared memory handle */
+    UnmapViewOfFile(pFile->shared);
+    CloseHandle(pFile->hShared);
+
+    /* Done with the mutex */
+    winceMutexRelease(pFile->hMutex);    
+    CloseHandle(pFile->hMutex);
+    pFile->hMutex = NULL;
+  }
+}
+
+/* 
+** An implementation of the LockFile() API of windows for wince
+*/
+static BOOL winceLockFile(
+  HANDLE *phFile,
+  DWORD dwFileOffsetLow,
+  DWORD dwFileOffsetHigh,
+  DWORD nNumberOfBytesToLockLow,
+  DWORD nNumberOfBytesToLockHigh
+){
+  winFile *pFile = HANDLE_TO_WINFILE(phFile);
+  BOOL bReturn = FALSE;
+
+  UNUSED_PARAMETER(dwFileOffsetHigh);
+  UNUSED_PARAMETER(nNumberOfBytesToLockHigh);
+
+  if (!pFile->hMutex) return TRUE;
+  winceMutexAcquire(pFile->hMutex);
+
+  /* Wanting an exclusive lock? */
+  if (dwFileOffsetLow == (DWORD)SHARED_FIRST
+       && nNumberOfBytesToLockLow == (DWORD)SHARED_SIZE){
+    if (pFile->shared->nReaders == 0 && pFile->shared->bExclusive == 0){
+       pFile->shared->bExclusive = TRUE;
+       pFile->local.bExclusive = TRUE;
+       bReturn = TRUE;
+    }
+  }
+
+  /* Want a read-only lock? */
+  else if (dwFileOffsetLow == (DWORD)SHARED_FIRST &&
+           nNumberOfBytesToLockLow == 1){
+    if (pFile->shared->bExclusive == 0){
+      pFile->local.nReaders ++;
+      if (pFile->local.nReaders == 1){
+        pFile->shared->nReaders ++;
+      }
+      bReturn = TRUE;
+    }
+  }
+
+  /* Want a pending lock? */
+  else if (dwFileOffsetLow == (DWORD)PENDING_BYTE && nNumberOfBytesToLockLow == 1){
+    /* If no pending lock has been acquired, then acquire it */
+    if (pFile->shared->bPending == 0) {
+      pFile->shared->bPending = TRUE;
+      pFile->local.bPending = TRUE;
+      bReturn = TRUE;
+    }
+  }
+
+  /* Want a reserved lock? */
+  else if (dwFileOffsetLow == (DWORD)RESERVED_BYTE && nNumberOfBytesToLockLow == 1){
+    if (pFile->shared->bReserved == 0) {
+      pFile->shared->bReserved = TRUE;
+      pFile->local.bReserved = TRUE;
+      bReturn = TRUE;
+    }
+  }
+
+  winceMutexRelease(pFile->hMutex);
+  return bReturn;
+}
+
+/*
+** An implementation of the UnlockFile API of windows for wince
+*/
+static BOOL winceUnlockFile(
+  HANDLE *phFile,
+  DWORD dwFileOffsetLow,
+  DWORD dwFileOffsetHigh,
+  DWORD nNumberOfBytesToUnlockLow,
+  DWORD nNumberOfBytesToUnlockHigh
+){
+  winFile *pFile = HANDLE_TO_WINFILE(phFile);
+  BOOL bReturn = FALSE;
+
+  UNUSED_PARAMETER(dwFileOffsetHigh);
+  UNUSED_PARAMETER(nNumberOfBytesToUnlockHigh);
+
+  if (!pFile->hMutex) return TRUE;
+  winceMutexAcquire(pFile->hMutex);
+
+  /* Releasing a reader lock or an exclusive lock */
+  if (dwFileOffsetLow == (DWORD)SHARED_FIRST){
+    /* Did we have an exclusive lock? */
+    if (pFile->local.bExclusive){
+      assert(nNumberOfBytesToUnlockLow == (DWORD)SHARED_SIZE);
+      pFile->local.bExclusive = FALSE;
+      pFile->shared->bExclusive = FALSE;
+      bReturn = TRUE;
+    }
+
+    /* Did we just have a reader lock? */
+    else if (pFile->local.nReaders){
+      assert(nNumberOfBytesToUnlockLow == (DWORD)SHARED_SIZE || nNumberOfBytesToUnlockLow == 1);
+      pFile->local.nReaders --;
+      if (pFile->local.nReaders == 0)
+      {
+        pFile->shared->nReaders --;
+      }
+      bReturn = TRUE;
+    }
+  }
+
+  /* Releasing a pending lock */
+  else if (dwFileOffsetLow == (DWORD)PENDING_BYTE && nNumberOfBytesToUnlockLow == 1){
+    if (pFile->local.bPending){
+      pFile->local.bPending = FALSE;
+      pFile->shared->bPending = FALSE;
+      bReturn = TRUE;
+    }
+  }
+  /* Releasing a reserved lock */
+  else if (dwFileOffsetLow == (DWORD)RESERVED_BYTE && nNumberOfBytesToUnlockLow == 1){
+    if (pFile->local.bReserved) {
+      pFile->local.bReserved = FALSE;
+      pFile->shared->bReserved = FALSE;
+      bReturn = TRUE;
+    }
+  }
+
+  winceMutexRelease(pFile->hMutex);
+  return bReturn;
+}
+
+/*
+** An implementation of the LockFileEx() API of windows for wince
+*/
+static BOOL winceLockFileEx(
+  HANDLE *phFile,
+  DWORD dwFlags,
+  DWORD dwReserved,
+  DWORD nNumberOfBytesToLockLow,
+  DWORD nNumberOfBytesToLockHigh,
+  LPOVERLAPPED lpOverlapped
+){
+  UNUSED_PARAMETER(dwReserved);
+  UNUSED_PARAMETER(nNumberOfBytesToLockHigh);
+
+  /* If the caller wants a shared read lock, forward this call
+  ** to winceLockFile */
+  if (lpOverlapped->Offset == (DWORD)SHARED_FIRST &&
+      dwFlags == 1 &&
+      nNumberOfBytesToLockLow == (DWORD)SHARED_SIZE){
+    return winceLockFile(phFile, SHARED_FIRST, 0, 1, 0);
+  }
+  return FALSE;
+}
+/*
+** End of the special code for wince
+*****************************************************************************/
+#endif /* SQLITE_OS_WINCE */
+
+/*****************************************************************************
+** The next group of routines implement the I/O methods specified
+** by the sqlite3_io_methods object.
+******************************************************************************/
+
+/*
+** Some microsoft compilers lack this definition.
+*/
+#ifndef INVALID_SET_FILE_POINTER
+# define INVALID_SET_FILE_POINTER ((DWORD)-1)
+#endif
+
+/*
+** Move the current position of the file handle passed as the first 
+** argument to offset iOffset within the file. If successful, return 0. 
+** Otherwise, set pFile->lastErrno and return non-zero.
+*/
+static int seekWinFile(winFile *pFile, sqlite3_int64 iOffset){
+  LONG upperBits;                 /* Most sig. 32 bits of new offset */
+  LONG lowerBits;                 /* Least sig. 32 bits of new offset */
+  DWORD dwRet;                    /* Value returned by SetFilePointer() */
+
+  upperBits = (LONG)((iOffset>>32) & 0x7fffffff);
+  lowerBits = (LONG)(iOffset & 0xffffffff);
+
+  /* API oddity: If successful, SetFilePointer() returns a dword 
+  ** containing the lower 32-bits of the new file-offset. Or, if it fails,
+  ** it returns INVALID_SET_FILE_POINTER. However according to MSDN, 
+  ** INVALID_SET_FILE_POINTER may also be a valid new offset. So to determine 
+  ** whether an error has actually occured, it is also necessary to call 
+  ** GetLastError().
+  */
+  dwRet = SetFilePointer(pFile->h, lowerBits, &upperBits, FILE_BEGIN);
+  if( (dwRet==INVALID_SET_FILE_POINTER && GetLastError()!=NO_ERROR) ){
+    pFile->lastErrno = GetLastError();
+    return 1;
+  }
+
+  return 0;
+}
+
+/*
+** Close a file.
+**
+** It is reported that an attempt to close a handle might sometimes
+** fail.  This is a very unreasonable result, but windows is notorious
+** for being unreasonable so I do not doubt that it might happen.  If
+** the close fails, we pause for 100 milliseconds and try again.  As
+** many as MX_CLOSE_ATTEMPT attempts to close the handle are made before
+** giving up and returning an error.
+*/
+#define MX_CLOSE_ATTEMPT 3
+static int winClose(sqlite3_file *id){
+  int rc, cnt = 0;
+  winFile *pFile = (winFile*)id;
+
+  assert( id!=0 );
+  assert( pFile->pShm==0 );
+  OSTRACE(("CLOSE %d\n", pFile->h));
+  do{
+    rc = CloseHandle(pFile->h);
+    /* SimulateIOError( rc=0; cnt=MX_CLOSE_ATTEMPT; ); */
+  }while( rc==0 && ++cnt < MX_CLOSE_ATTEMPT && (Sleep(100), 1) );
+#if SQLITE_OS_WINCE
+#define WINCE_DELETION_ATTEMPTS 3
+  winceDestroyLock(pFile);
+  if( pFile->zDeleteOnClose ){
+    int cnt = 0;
+    while(
+           DeleteFileW(pFile->zDeleteOnClose)==0
+        && GetFileAttributesW(pFile->zDeleteOnClose)!=0xffffffff 
+        && cnt++ < WINCE_DELETION_ATTEMPTS
+    ){
+       Sleep(100);  /* Wait a little before trying again */
+    }
+    free(pFile->zDeleteOnClose);
+  }
+#endif
+  OSTRACE(("CLOSE %d %s\n", pFile->h, rc ? "ok" : "failed"));
+  OpenCounter(-1);
+  return rc ? SQLITE_OK : SQLITE_IOERR;
+}
+
+/*
+** Read data from a file into a buffer.  Return SQLITE_OK if all
+** bytes were read successfully and SQLITE_IOERR if anything goes
+** wrong.
+*/
+static int winRead(
+  sqlite3_file *id,          /* File to read from */
+  void *pBuf,                /* Write content into this buffer */
+  int amt,                   /* Number of bytes to read */
+  sqlite3_int64 offset       /* Begin reading at this offset */
+){
+  winFile *pFile = (winFile*)id;  /* file handle */
+  DWORD nRead;                    /* Number of bytes actually read from file */
+
+  assert( id!=0 );
+  SimulateIOError(return SQLITE_IOERR_READ);
+  OSTRACE(("READ %d lock=%d\n", pFile->h, pFile->locktype));
+
+  if( seekWinFile(pFile, offset) ){
+    return SQLITE_FULL;
+  }
+  if( !ReadFile(pFile->h, pBuf, amt, &nRead, 0) ){
+    pFile->lastErrno = GetLastError();
+    return SQLITE_IOERR_READ;
+  }
+  if( nRead<(DWORD)amt ){
+    /* Unread parts of the buffer must be zero-filled */
+    memset(&((char*)pBuf)[nRead], 0, amt-nRead);
+    return SQLITE_IOERR_SHORT_READ;
+  }
+
+  return SQLITE_OK;
+}
+
+/*
+** Write data from a buffer into a file.  Return SQLITE_OK on success
+** or some other error code on failure.
+*/
+static int winWrite(
+  sqlite3_file *id,               /* File to write into */
+  const void *pBuf,               /* The bytes to be written */
+  int amt,                        /* Number of bytes to write */
+  sqlite3_int64 offset            /* Offset into the file to begin writing at */
+){
+  int rc;                         /* True if error has occured, else false */
+  winFile *pFile = (winFile*)id;  /* File handle */
+
+  assert( amt>0 );
+  assert( pFile );
+  SimulateIOError(return SQLITE_IOERR_WRITE);
+  SimulateDiskfullError(return SQLITE_FULL);
+
+  OSTRACE(("WRITE %d lock=%d\n", pFile->h, pFile->locktype));
+
+  rc = seekWinFile(pFile, offset);
+  if( rc==0 ){
+    u8 *aRem = (u8 *)pBuf;        /* Data yet to be written */
+    int nRem = amt;               /* Number of bytes yet to be written */
+    DWORD nWrite;                 /* Bytes written by each WriteFile() call */
+
+    while( nRem>0 && WriteFile(pFile->h, aRem, nRem, &nWrite, 0) && nWrite>0 ){
+      aRem += nWrite;
+      nRem -= nWrite;
+    }
+    if( nRem>0 ){
+      pFile->lastErrno = GetLastError();
+      rc = 1;
+    }
+  }
+
+  if( rc ){
+    if( pFile->lastErrno==ERROR_HANDLE_DISK_FULL ){
+      return SQLITE_FULL;
+    }
+    return SQLITE_IOERR_WRITE;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Truncate an open file to a specified size
+*/
+static int winTruncate(sqlite3_file *id, sqlite3_int64 nByte){
+  winFile *pFile = (winFile*)id;  /* File handle object */
+  int rc = SQLITE_OK;             /* Return code for this function */
+
+  assert( pFile );
+
+  OSTRACE(("TRUNCATE %d %lld\n", pFile->h, nByte));
+  SimulateIOError(return SQLITE_IOERR_TRUNCATE);
+
+  /* If the user has configured a chunk-size for this file, truncate the
+  ** file so that it consists of an integer number of chunks (i.e. the
+  ** actual file size after the operation may be larger than the requested
+  ** size).
+  */
+  if( pFile->szChunk ){
+    nByte = ((nByte + pFile->szChunk - 1)/pFile->szChunk) * pFile->szChunk;
+  }
+
+  /* SetEndOfFile() returns non-zero when successful, or zero when it fails. */
+  if( seekWinFile(pFile, nByte) ){
+    rc = SQLITE_IOERR_TRUNCATE;
+  }else if( 0==SetEndOfFile(pFile->h) ){
+    pFile->lastErrno = GetLastError();
+    rc = SQLITE_IOERR_TRUNCATE;
+  }
+
+  OSTRACE(("TRUNCATE %d %lld %s\n", pFile->h, nByte, rc ? "failed" : "ok"));
+  return rc;
+}
+
+#ifdef SQLITE_TEST
+/*
+** Count the number of fullsyncs and normal syncs.  This is used to test
+** that syncs and fullsyncs are occuring at the right times.
+*/
+SQLITE_API int sqlite3_sync_count = 0;
+SQLITE_API int sqlite3_fullsync_count = 0;
+#endif
+
+/*
+** Make sure all writes to a particular file are committed to disk.
+*/
+static int winSync(sqlite3_file *id, int flags){
+#if !defined(NDEBUG) || !defined(SQLITE_NO_SYNC) || defined(SQLITE_DEBUG)
+  winFile *pFile = (winFile*)id;
+#else
+  UNUSED_PARAMETER(id);
+#endif
+
+  assert( pFile );
+  /* Check that one of SQLITE_SYNC_NORMAL or FULL was passed */
+  assert((flags&0x0F)==SQLITE_SYNC_NORMAL
+      || (flags&0x0F)==SQLITE_SYNC_FULL
+  );
+
+  OSTRACE(("SYNC %d lock=%d\n", pFile->h, pFile->locktype));
+
+#ifndef SQLITE_TEST
+  UNUSED_PARAMETER(flags);
+#else
+  if( flags & SQLITE_SYNC_FULL ){
+    sqlite3_fullsync_count++;
+  }
+  sqlite3_sync_count++;
+#endif
+
+  /* Unix cannot, but some systems may return SQLITE_FULL from here. This
+  ** line is to test that doing so does not cause any problems.
+  */
+  SimulateDiskfullError( return SQLITE_FULL );
+  SimulateIOError( return SQLITE_IOERR; );
+
+  /* If we compiled with the SQLITE_NO_SYNC flag, then syncing is a
+  ** no-op
+  */
+#ifdef SQLITE_NO_SYNC
+  return SQLITE_OK;
+#else
+  if( FlushFileBuffers(pFile->h) ){
+    return SQLITE_OK;
+  }else{
+    pFile->lastErrno = GetLastError();
+    return SQLITE_IOERR;
+  }
+#endif
+}
+
+/*
+** Determine the current size of a file in bytes
+*/
+static int winFileSize(sqlite3_file *id, sqlite3_int64 *pSize){
+  DWORD upperBits;
+  DWORD lowerBits;
+  winFile *pFile = (winFile*)id;
+  DWORD error;
+
+  assert( id!=0 );
+  SimulateIOError(return SQLITE_IOERR_FSTAT);
+  lowerBits = GetFileSize(pFile->h, &upperBits);
+  if(   (lowerBits == INVALID_FILE_SIZE)
+     && ((error = GetLastError()) != NO_ERROR) )
+  {
+    pFile->lastErrno = error;
+    return SQLITE_IOERR_FSTAT;
+  }
+  *pSize = (((sqlite3_int64)upperBits)<<32) + lowerBits;
+  return SQLITE_OK;
+}
+
+/*
+** LOCKFILE_FAIL_IMMEDIATELY is undefined on some Windows systems.
+*/
+#ifndef LOCKFILE_FAIL_IMMEDIATELY
+# define LOCKFILE_FAIL_IMMEDIATELY 1
+#endif
+
+/*
+** Acquire a reader lock.
+** Different API routines are called depending on whether or not this
+** is Win95 or WinNT.
+*/
+static int getReadLock(winFile *pFile){
+  int res;
+  if( isNT() ){
+    OVERLAPPED ovlp;
+    ovlp.Offset = SHARED_FIRST;
+    ovlp.OffsetHigh = 0;
+    ovlp.hEvent = 0;
+    res = LockFileEx(pFile->h, LOCKFILE_FAIL_IMMEDIATELY,
+                     0, SHARED_SIZE, 0, &ovlp);
+/* isNT() is 1 if SQLITE_OS_WINCE==1, so this else is never executed. 
+*/
+#if SQLITE_OS_WINCE==0
+  }else{
+    int lk;
+    sqlite3_randomness(sizeof(lk), &lk);
+    pFile->sharedLockByte = (short)((lk & 0x7fffffff)%(SHARED_SIZE - 1));
+    res = LockFile(pFile->h, SHARED_FIRST+pFile->sharedLockByte, 0, 1, 0);
+#endif
+  }
+  if( res == 0 ){
+    pFile->lastErrno = GetLastError();
+  }
+  return res;
+}
+
+/*
+** Undo a readlock
+*/
+static int unlockReadLock(winFile *pFile){
+  int res;
+  if( isNT() ){
+    res = UnlockFile(pFile->h, SHARED_FIRST, 0, SHARED_SIZE, 0);
+/* isNT() is 1 if SQLITE_OS_WINCE==1, so this else is never executed. 
+*/
+#if SQLITE_OS_WINCE==0
+  }else{
+    res = UnlockFile(pFile->h, SHARED_FIRST + pFile->sharedLockByte, 0, 1, 0);
+#endif
+  }
+  if( res == 0 ){
+    pFile->lastErrno = GetLastError();
+  }
+  return res;
+}
+
+/*
+** Lock the file with the lock specified by parameter locktype - one
+** of the following:
+**
+**     (1) SHARED_LOCK
+**     (2) RESERVED_LOCK
+**     (3) PENDING_LOCK
+**     (4) EXCLUSIVE_LOCK
+**
+** Sometimes when requesting one lock state, additional lock states
+** are inserted in between.  The locking might fail on one of the later
+** transitions leaving the lock state different from what it started but
+** still short of its goal.  The following chart shows the allowed
+** transitions and the inserted intermediate states:
+**
+**    UNLOCKED -> SHARED
+**    SHARED -> RESERVED
+**    SHARED -> (PENDING) -> EXCLUSIVE
+**    RESERVED -> (PENDING) -> EXCLUSIVE
+**    PENDING -> EXCLUSIVE
+**
+** This routine will only increase a lock.  The winUnlock() routine
+** erases all locks at once and returns us immediately to locking level 0.
+** It is not possible to lower the locking level one step at a time.  You
+** must go straight to locking level 0.
+*/
+static int winLock(sqlite3_file *id, int locktype){
+  int rc = SQLITE_OK;    /* Return code from subroutines */
+  int res = 1;           /* Result of a windows lock call */
+  int newLocktype;       /* Set pFile->locktype to this value before exiting */
+  int gotPendingLock = 0;/* True if we acquired a PENDING lock this time */
+  winFile *pFile = (winFile*)id;
+  DWORD error = NO_ERROR;
+
+  assert( id!=0 );
+  OSTRACE(("LOCK %d %d was %d(%d)\n",
+           pFile->h, locktype, pFile->locktype, pFile->sharedLockByte));
+
+  /* If there is already a lock of this type or more restrictive on the
+  ** OsFile, do nothing. Don't use the end_lock: exit path, as
+  ** sqlite3OsEnterMutex() hasn't been called yet.
+  */
+  if( pFile->locktype>=locktype ){
+    return SQLITE_OK;
+  }
+
+  /* Make sure the locking sequence is correct
+  */
+  assert( pFile->locktype!=NO_LOCK || locktype==SHARED_LOCK );
+  assert( locktype!=PENDING_LOCK );
+  assert( locktype!=RESERVED_LOCK || pFile->locktype==SHARED_LOCK );
+
+  /* Lock the PENDING_LOCK byte if we need to acquire a PENDING lock or
+  ** a SHARED lock.  If we are acquiring a SHARED lock, the acquisition of
+  ** the PENDING_LOCK byte is temporary.
+  */
+  newLocktype = pFile->locktype;
+  if(   (pFile->locktype==NO_LOCK)
+     || (   (locktype==EXCLUSIVE_LOCK)
+         && (pFile->locktype==RESERVED_LOCK))
+  ){
+    int cnt = 3;
+    while( cnt-->0 && (res = LockFile(pFile->h, PENDING_BYTE, 0, 1, 0))==0 ){
+      /* Try 3 times to get the pending lock.  The pending lock might be
+      ** held by another reader process who will release it momentarily.
+      */
+      OSTRACE(("could not get a PENDING lock. cnt=%d\n", cnt));
+      Sleep(1);
+    }
+    gotPendingLock = res;
+    if( !res ){
+      error = GetLastError();
+    }
+  }
+
+  /* Acquire a shared lock
+  */
+  if( locktype==SHARED_LOCK && res ){
+    assert( pFile->locktype==NO_LOCK );
+    res = getReadLock(pFile);
+    if( res ){
+      newLocktype = SHARED_LOCK;
+    }else{
+      error = GetLastError();
+    }
+  }
+
+  /* Acquire a RESERVED lock
+  */
+  if( locktype==RESERVED_LOCK && res ){
+    assert( pFile->locktype==SHARED_LOCK );
+    res = LockFile(pFile->h, RESERVED_BYTE, 0, 1, 0);
+    if( res ){
+      newLocktype = RESERVED_LOCK;
+    }else{
+      error = GetLastError();
+    }
+  }
+
+  /* Acquire a PENDING lock
+  */
+  if( locktype==EXCLUSIVE_LOCK && res ){
+    newLocktype = PENDING_LOCK;
+    gotPendingLock = 0;
+  }
+
+  /* Acquire an EXCLUSIVE lock
+  */
+  if( locktype==EXCLUSIVE_LOCK && res ){
+    assert( pFile->locktype>=SHARED_LOCK );
+    res = unlockReadLock(pFile);
+    OSTRACE(("unreadlock = %d\n", res));
+    res = LockFile(pFile->h, SHARED_FIRST, 0, SHARED_SIZE, 0);
+    if( res ){
+      newLocktype = EXCLUSIVE_LOCK;
+    }else{
+      error = GetLastError();
+      OSTRACE(("error-code = %d\n", error));
+      getReadLock(pFile);
+    }
+  }
+
+  /* If we are holding a PENDING lock that ought to be released, then
+  ** release it now.
+  */
+  if( gotPendingLock && locktype==SHARED_LOCK ){
+    UnlockFile(pFile->h, PENDING_BYTE, 0, 1, 0);
+  }
+
+  /* Update the state of the lock has held in the file descriptor then
+  ** return the appropriate result code.
+  */
+  if( res ){
+    rc = SQLITE_OK;
+  }else{
+    OSTRACE(("LOCK FAILED %d trying for %d but got %d\n", pFile->h,
+           locktype, newLocktype));
+    pFile->lastErrno = error;
+    rc = SQLITE_BUSY;
+  }
+  pFile->locktype = (u8)newLocktype;
+  return rc;
+}
+
+/*
+** This routine checks if there is a RESERVED lock held on the specified
+** file by this or any other process. If such a lock is held, return
+** non-zero, otherwise zero.
+*/
+static int winCheckReservedLock(sqlite3_file *id, int *pResOut){
+  int rc;
+  winFile *pFile = (winFile*)id;
+
+  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );
+
+  assert( id!=0 );
+  if( pFile->locktype>=RESERVED_LOCK ){
+    rc = 1;
+    OSTRACE(("TEST WR-LOCK %d %d (local)\n", pFile->h, rc));
+  }else{
+    rc = LockFile(pFile->h, RESERVED_BYTE, 0, 1, 0);
+    if( rc ){
+      UnlockFile(pFile->h, RESERVED_BYTE, 0, 1, 0);
+    }
+    rc = !rc;
+    OSTRACE(("TEST WR-LOCK %d %d (remote)\n", pFile->h, rc));
+  }
+  *pResOut = rc;
+  return SQLITE_OK;
+}
+
+/*
+** Lower the locking level on file descriptor id to locktype.  locktype
+** must be either NO_LOCK or SHARED_LOCK.
+**
+** If the locking level of the file descriptor is already at or below
+** the requested locking level, this routine is a no-op.
+**
+** It is not possible for this routine to fail if the second argument
+** is NO_LOCK.  If the second argument is SHARED_LOCK then this routine
+** might return SQLITE_IOERR;
+*/
+static int winUnlock(sqlite3_file *id, int locktype){
+  int type;
+  winFile *pFile = (winFile*)id;
+  int rc = SQLITE_OK;
+  assert( pFile!=0 );
+  assert( locktype<=SHARED_LOCK );
+  OSTRACE(("UNLOCK %d to %d was %d(%d)\n", pFile->h, locktype,
+          pFile->locktype, pFile->sharedLockByte));
+  type = pFile->locktype;
+  if( type>=EXCLUSIVE_LOCK ){
+    UnlockFile(pFile->h, SHARED_FIRST, 0, SHARED_SIZE, 0);
+    if( locktype==SHARED_LOCK && !getReadLock(pFile) ){
+      /* This should never happen.  We should always be able to
+      ** reacquire the read lock */
+      rc = SQLITE_IOERR_UNLOCK;
+    }
+  }
+  if( type>=RESERVED_LOCK ){
+    UnlockFile(pFile->h, RESERVED_BYTE, 0, 1, 0);
+  }
+  if( locktype==NO_LOCK && type>=SHARED_LOCK ){
+    unlockReadLock(pFile);
+  }
+  if( type>=PENDING_LOCK ){
+    UnlockFile(pFile->h, PENDING_BYTE, 0, 1, 0);
+  }
+  pFile->locktype = (u8)locktype;
+  return rc;
+}
+
+/*
+** Control and query of the open file handle.
+*/
+static int winFileControl(sqlite3_file *id, int op, void *pArg){
+  switch( op ){
+    case SQLITE_FCNTL_LOCKSTATE: {
+      *(int*)pArg = ((winFile*)id)->locktype;
+      return SQLITE_OK;
+    }
+    case SQLITE_LAST_ERRNO: {
+      *(int*)pArg = (int)((winFile*)id)->lastErrno;
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_CHUNK_SIZE: {
+      ((winFile*)id)->szChunk = *(int *)pArg;
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_SIZE_HINT: {
+      sqlite3_int64 sz = *(sqlite3_int64*)pArg;
+      SimulateIOErrorBenign(1);
+      winTruncate(id, sz);
+      SimulateIOErrorBenign(0);
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_SYNC_OMITTED: {
+      return SQLITE_OK;
+    }
+  }
+  return SQLITE_NOTFOUND;
+}
+
+/*
+** Return the sector size in bytes of the underlying block device for
+** the specified file. This is almost always 512 bytes, but may be
+** larger for some devices.
+**
+** SQLite code assumes this function cannot fail. It also assumes that
+** if two files are created in the same file-system directory (i.e.
+** a database and its journal file) that the sector size will be the
+** same for both.
+*/
+static int winSectorSize(sqlite3_file *id){
+  assert( id!=0 );
+  return (int)(((winFile*)id)->sectorSize);
+}
+
+/*
+** Return a vector of device characteristics.
+*/
+static int winDeviceCharacteristics(sqlite3_file *id){
+  UNUSED_PARAMETER(id);
+  return SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN;
+}
+
+#ifndef SQLITE_OMIT_WAL
+
+/* 
+** Windows will only let you create file view mappings
+** on allocation size granularity boundaries.
+** During sqlite3_os_init() we do a GetSystemInfo()
+** to get the granularity size.
+*/
+SYSTEM_INFO winSysInfo;
+
+/*
+** Helper functions to obtain and relinquish the global mutex. The
+** global mutex is used to protect the winLockInfo objects used by 
+** this file, all of which may be shared by multiple threads.
+**
+** Function winShmMutexHeld() is used to assert() that the global mutex 
+** is held when required. This function is only used as part of assert() 
+** statements. e.g.
+**
+**   winShmEnterMutex()
+**     assert( winShmMutexHeld() );
+**   winShmLeaveMutex()
+*/
+static void winShmEnterMutex(void){
+  sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
+}
+static void winShmLeaveMutex(void){
+  sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
+}
+#ifdef SQLITE_DEBUG
+static int winShmMutexHeld(void) {
+  return sqlite3_mutex_held(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
+}
+#endif
+
+/*
+** Object used to represent a single file opened and mmapped to provide
+** shared memory.  When multiple threads all reference the same
+** log-summary, each thread has its own winFile object, but they all
+** point to a single instance of this object.  In other words, each
+** log-summary is opened only once per process.
+**
+** winShmMutexHeld() must be true when creating or destroying
+** this object or while reading or writing the following fields:
+**
+**      nRef
+**      pNext 
+**
+** The following fields are read-only after the object is created:
+** 
+**      fid
+**      zFilename
+**
+** Either winShmNode.mutex must be held or winShmNode.nRef==0 and
+** winShmMutexHeld() is true when reading or writing any other field
+** in this structure.
+**
+*/
+struct winShmNode {
+  sqlite3_mutex *mutex;      /* Mutex to access this object */
+  char *zFilename;           /* Name of the file */
+  winFile hFile;             /* File handle from winOpen */
+
+  int szRegion;              /* Size of shared-memory regions */
+  int nRegion;               /* Size of array apRegion */
+  struct ShmRegion {
+    HANDLE hMap;             /* File handle from CreateFileMapping */
+    void *pMap;
+  } *aRegion;
+  DWORD lastErrno;           /* The Windows errno from the last I/O error */
+
+  int nRef;                  /* Number of winShm objects pointing to this */
+  winShm *pFirst;            /* All winShm objects pointing to this */
+  winShmNode *pNext;         /* Next in list of all winShmNode objects */
+#ifdef SQLITE_DEBUG
+  u8 nextShmId;              /* Next available winShm.id value */
+#endif
+};
+
+/*
+** A global array of all winShmNode objects.
+**
+** The winShmMutexHeld() must be true while reading or writing this list.
+*/
+static winShmNode *winShmNodeList = 0;
+
+/*
+** Structure used internally by this VFS to record the state of an
+** open shared memory connection.
+**
+** The following fields are initialized when this object is created and
+** are read-only thereafter:
+**
+**    winShm.pShmNode
+**    winShm.id
+**
+** All other fields are read/write.  The winShm.pShmNode->mutex must be held
+** while accessing any read/write fields.
+*/
+struct winShm {
+  winShmNode *pShmNode;      /* The underlying winShmNode object */
+  winShm *pNext;             /* Next winShm with the same winShmNode */
+  u8 hasMutex;               /* True if holding the winShmNode mutex */
+  u16 sharedMask;            /* Mask of shared locks held */
+  u16 exclMask;              /* Mask of exclusive locks held */
+#ifdef SQLITE_DEBUG
+  u8 id;                     /* Id of this connection with its winShmNode */
+#endif
+};
+
+/*
+** Constants used for locking
+*/
+#define WIN_SHM_BASE   ((22+SQLITE_SHM_NLOCK)*4)        /* first lock byte */
+#define WIN_SHM_DMS    (WIN_SHM_BASE+SQLITE_SHM_NLOCK)  /* deadman switch */
+
+/*
+** Apply advisory locks for all n bytes beginning at ofst.
+*/
+#define _SHM_UNLCK  1
+#define _SHM_RDLCK  2
+#define _SHM_WRLCK  3
+static int winShmSystemLock(
+  winShmNode *pFile,    /* Apply locks to this open shared-memory segment */
+  int lockType,         /* _SHM_UNLCK, _SHM_RDLCK, or _SHM_WRLCK */
+  int ofst,             /* Offset to first byte to be locked/unlocked */
+  int nByte             /* Number of bytes to lock or unlock */
+){
+  OVERLAPPED ovlp;
+  DWORD dwFlags;
+  int rc = 0;           /* Result code form Lock/UnlockFileEx() */
+
+  /* Access to the winShmNode object is serialized by the caller */
+  assert( sqlite3_mutex_held(pFile->mutex) || pFile->nRef==0 );
+
+  /* Initialize the locking parameters */
+  dwFlags = LOCKFILE_FAIL_IMMEDIATELY;
+  if( lockType == _SHM_WRLCK ) dwFlags |= LOCKFILE_EXCLUSIVE_LOCK;
+
+  memset(&ovlp, 0, sizeof(OVERLAPPED));
+  ovlp.Offset = ofst;
+
+  /* Release/Acquire the system-level lock */
+  if( lockType==_SHM_UNLCK ){
+    rc = UnlockFileEx(pFile->hFile.h, 0, nByte, 0, &ovlp);
+  }else{
+    rc = LockFileEx(pFile->hFile.h, dwFlags, 0, nByte, 0, &ovlp);
+  }
+  
+  if( rc!= 0 ){
+    rc = SQLITE_OK;
+  }else{
+    pFile->lastErrno =  GetLastError();
+    rc = SQLITE_BUSY;
+  }
+
+  OSTRACE(("SHM-LOCK %d %s %s 0x%08lx\n", 
+           pFile->hFile.h,
+           rc==SQLITE_OK ? "ok" : "failed",
+           lockType==_SHM_UNLCK ? "UnlockFileEx" : "LockFileEx",
+           pFile->lastErrno));
+
+  return rc;
+}
+
+/* Forward references to VFS methods */
+static int winOpen(sqlite3_vfs*,const char*,sqlite3_file*,int,int*);
+static int winDelete(sqlite3_vfs *,const char*,int);
+
+/*
+** Purge the winShmNodeList list of all entries with winShmNode.nRef==0.
+**
+** This is not a VFS shared-memory method; it is a utility function called
+** by VFS shared-memory methods.
+*/
+static void winShmPurge(sqlite3_vfs *pVfs, int deleteFlag){
+  winShmNode **pp;
+  winShmNode *p;
+  BOOL bRc;
+  assert( winShmMutexHeld() );
+  pp = &winShmNodeList;
+  while( (p = *pp)!=0 ){
+    if( p->nRef==0 ){
+      int i;
+      if( p->mutex ) sqlite3_mutex_free(p->mutex);
+      for(i=0; i<p->nRegion; i++){
+        bRc = UnmapViewOfFile(p->aRegion[i].pMap);
+        OSTRACE(("SHM-PURGE pid-%d unmap region=%d %s\n",
+                 (int)GetCurrentProcessId(), i,
+                 bRc ? "ok" : "failed"));
+        bRc = CloseHandle(p->aRegion[i].hMap);
+        OSTRACE(("SHM-PURGE pid-%d close region=%d %s\n",
+                 (int)GetCurrentProcessId(), i,
+                 bRc ? "ok" : "failed"));
+      }
+      if( p->hFile.h != INVALID_HANDLE_VALUE ){
+        SimulateIOErrorBenign(1);
+        winClose((sqlite3_file *)&p->hFile);
+        SimulateIOErrorBenign(0);
+      }
+      if( deleteFlag ){
+        SimulateIOErrorBenign(1);
+        winDelete(pVfs, p->zFilename, 0);
+        SimulateIOErrorBenign(0);
+      }
+      *pp = p->pNext;
+      sqlite3_free(p->aRegion);
+      sqlite3_free(p);
+    }else{
+      pp = &p->pNext;
+    }
+  }
+}
+
+/*
+** Open the shared-memory area associated with database file pDbFd.
+**
+** When opening a new shared-memory file, if no other instances of that
+** file are currently open, in this process or in other processes, then
+** the file must be truncated to zero length or have its header cleared.
+*/
+static int winOpenSharedMemory(winFile *pDbFd){
+  struct winShm *p;                  /* The connection to be opened */
+  struct winShmNode *pShmNode = 0;   /* The underlying mmapped file */
+  int rc;                            /* Result code */
+  struct winShmNode *pNew;           /* Newly allocated winShmNode */
+  int nName;                         /* Size of zName in bytes */
+
+  assert( pDbFd->pShm==0 );    /* Not previously opened */
+
+  /* Allocate space for the new sqlite3_shm object.  Also speculatively
+  ** allocate space for a new winShmNode and filename.
+  */
+  p = sqlite3_malloc( sizeof(*p) );
+  if( p==0 ) return SQLITE_NOMEM;
+  memset(p, 0, sizeof(*p));
+  nName = sqlite3Strlen30(pDbFd->zPath);
+  pNew = sqlite3_malloc( sizeof(*pShmNode) + nName + 15 );
+  if( pNew==0 ){
+    sqlite3_free(p);
+    return SQLITE_NOMEM;
+  }
+  memset(pNew, 0, sizeof(*pNew));
+  pNew->zFilename = (char*)&pNew[1];
+  sqlite3_snprintf(nName+15, pNew->zFilename, "%s-shm", pDbFd->zPath);
+
+  /* Look to see if there is an existing winShmNode that can be used.
+  ** If no matching winShmNode currently exists, create a new one.
+  */
+  winShmEnterMutex();
+  for(pShmNode = winShmNodeList; pShmNode; pShmNode=pShmNode->pNext){
+    /* TBD need to come up with better match here.  Perhaps
+    ** use FILE_ID_BOTH_DIR_INFO Structure.
+    */
+    if( sqlite3StrICmp(pShmNode->zFilename, pNew->zFilename)==0 ) break;
+  }
+  if( pShmNode ){
+    sqlite3_free(pNew);
+  }else{
+    pShmNode = pNew;
+    pNew = 0;
+    ((winFile*)(&pShmNode->hFile))->h = INVALID_HANDLE_VALUE;
+    pShmNode->pNext = winShmNodeList;
+    winShmNodeList = pShmNode;
+
+    pShmNode->mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
+    if( pShmNode->mutex==0 ){
+      rc = SQLITE_NOMEM;
+      goto shm_open_err;
+    }
+
+    rc = winOpen(pDbFd->pVfs,
+                 pShmNode->zFilename,             /* Name of the file (UTF-8) */
+                 (sqlite3_file*)&pShmNode->hFile,  /* File handle here */
+                 SQLITE_OPEN_WAL | SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE, /* Mode flags */
+                 0);
+    if( SQLITE_OK!=rc ){
+      rc = SQLITE_CANTOPEN_BKPT;
+      goto shm_open_err;
+    }
+
+    /* Check to see if another process is holding the dead-man switch.
+    ** If not, truncate the file to zero length. 
+    */
+    if( winShmSystemLock(pShmNode, _SHM_WRLCK, WIN_SHM_DMS, 1)==SQLITE_OK ){
+      rc = winTruncate((sqlite3_file *)&pShmNode->hFile, 0);
+      if( rc!=SQLITE_OK ){
+        rc = SQLITE_IOERR_SHMOPEN;
+      }
+    }
+    if( rc==SQLITE_OK ){
+      winShmSystemLock(pShmNode, _SHM_UNLCK, WIN_SHM_DMS, 1);
+      rc = winShmSystemLock(pShmNode, _SHM_RDLCK, WIN_SHM_DMS, 1);
+    }
+    if( rc ) goto shm_open_err;
+  }
+
+  /* Make the new connection a child of the winShmNode */
+  p->pShmNode = pShmNode;
+#ifdef SQLITE_DEBUG
+  p->id = pShmNode->nextShmId++;
+#endif
+  pShmNode->nRef++;
+  pDbFd->pShm = p;
+  winShmLeaveMutex();
+
+  /* The reference count on pShmNode has already been incremented under
+  ** the cover of the winShmEnterMutex() mutex and the pointer from the
+  ** new (struct winShm) object to the pShmNode has been set. All that is
+  ** left to do is to link the new object into the linked list starting
+  ** at pShmNode->pFirst. This must be done while holding the pShmNode->mutex 
+  ** mutex.
+  */
+  sqlite3_mutex_enter(pShmNode->mutex);
+  p->pNext = pShmNode->pFirst;
+  pShmNode->pFirst = p;
+  sqlite3_mutex_leave(pShmNode->mutex);
+  return SQLITE_OK;
+
+  /* Jump here on any error */
+shm_open_err:
+  winShmSystemLock(pShmNode, _SHM_UNLCK, WIN_SHM_DMS, 1);
+  winShmPurge(pDbFd->pVfs, 0);      /* This call frees pShmNode if required */
+  sqlite3_free(p);
+  sqlite3_free(pNew);
+  winShmLeaveMutex();
+  return rc;
+}
+
+/*
+** Close a connection to shared-memory.  Delete the underlying 
+** storage if deleteFlag is true.
+*/
+static int winShmUnmap(
+  sqlite3_file *fd,          /* Database holding shared memory */
+  int deleteFlag             /* Delete after closing if true */
+){
+  winFile *pDbFd;       /* Database holding shared-memory */
+  winShm *p;            /* The connection to be closed */
+  winShmNode *pShmNode; /* The underlying shared-memory file */
+  winShm **pp;          /* For looping over sibling connections */
+
+  pDbFd = (winFile*)fd;
+  p = pDbFd->pShm;
+  if( p==0 ) return SQLITE_OK;
+  pShmNode = p->pShmNode;
+
+  /* Remove connection p from the set of connections associated
+  ** with pShmNode */
+  sqlite3_mutex_enter(pShmNode->mutex);
+  for(pp=&pShmNode->pFirst; (*pp)!=p; pp = &(*pp)->pNext){}
+  *pp = p->pNext;
+
+  /* Free the connection p */
+  sqlite3_free(p);
+  pDbFd->pShm = 0;
+  sqlite3_mutex_leave(pShmNode->mutex);
+
+  /* If pShmNode->nRef has reached 0, then close the underlying
+  ** shared-memory file, too */
+  winShmEnterMutex();
+  assert( pShmNode->nRef>0 );
+  pShmNode->nRef--;
+  if( pShmNode->nRef==0 ){
+    winShmPurge(pDbFd->pVfs, deleteFlag);
+  }
+  winShmLeaveMutex();
+
+  return SQLITE_OK;
+}
+
+/*
+** Change the lock state for a shared-memory segment.
+*/
+static int winShmLock(
+  sqlite3_file *fd,          /* Database file holding the shared memory */
+  int ofst,                  /* First lock to acquire or release */
+  int n,                     /* Number of locks to acquire or release */
+  int flags                  /* What to do with the lock */
+){
+  winFile *pDbFd = (winFile*)fd;        /* Connection holding shared memory */
+  winShm *p = pDbFd->pShm;              /* The shared memory being locked */
+  winShm *pX;                           /* For looping over all siblings */
+  winShmNode *pShmNode = p->pShmNode;
+  int rc = SQLITE_OK;                   /* Result code */
+  u16 mask;                             /* Mask of locks to take or release */
+
+  assert( ofst>=0 && ofst+n<=SQLITE_SHM_NLOCK );
+  assert( n>=1 );
+  assert( flags==(SQLITE_SHM_LOCK | SQLITE_SHM_SHARED)
+       || flags==(SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE)
+       || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED)
+       || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE) );
+  assert( n==1 || (flags & SQLITE_SHM_EXCLUSIVE)!=0 );
+
+  mask = (u16)((1U<<(ofst+n)) - (1U<<ofst));
+  assert( n>1 || mask==(1<<ofst) );
+  sqlite3_mutex_enter(pShmNode->mutex);
+  if( flags & SQLITE_SHM_UNLOCK ){
+    u16 allMask = 0; /* Mask of locks held by siblings */
+
+    /* See if any siblings hold this same lock */
+    for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
+      if( pX==p ) continue;
+      assert( (pX->exclMask & (p->exclMask|p->sharedMask))==0 );
+      allMask |= pX->sharedMask;
+    }
+
+    /* Unlock the system-level locks */
+    if( (mask & allMask)==0 ){
+      rc = winShmSystemLock(pShmNode, _SHM_UNLCK, ofst+WIN_SHM_BASE, n);
+    }else{
+      rc = SQLITE_OK;
+    }
+
+    /* Undo the local locks */
+    if( rc==SQLITE_OK ){
+      p->exclMask &= ~mask;
+      p->sharedMask &= ~mask;
+    } 
+  }else if( flags & SQLITE_SHM_SHARED ){
+    u16 allShared = 0;  /* Union of locks held by connections other than "p" */
+
+    /* Find out which shared locks are already held by sibling connections.
+    ** If any sibling already holds an exclusive lock, go ahead and return
+    ** SQLITE_BUSY.
+    */
+    for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
+      if( (pX->exclMask & mask)!=0 ){
+        rc = SQLITE_BUSY;
+        break;
+      }
+      allShared |= pX->sharedMask;
+    }
+
+    /* Get shared locks at the system level, if necessary */
+    if( rc==SQLITE_OK ){
+      if( (allShared & mask)==0 ){
+        rc = winShmSystemLock(pShmNode, _SHM_RDLCK, ofst+WIN_SHM_BASE, n);
+      }else{
+        rc = SQLITE_OK;
+      }
+    }
+
+    /* Get the local shared locks */
+    if( rc==SQLITE_OK ){
+      p->sharedMask |= mask;
+    }
+  }else{
+    /* Make sure no sibling connections hold locks that will block this
+    ** lock.  If any do, return SQLITE_BUSY right away.
+    */
+    for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
+      if( (pX->exclMask & mask)!=0 || (pX->sharedMask & mask)!=0 ){
+        rc = SQLITE_BUSY;
+        break;
+      }
+    }
+  
+    /* Get the exclusive locks at the system level.  Then if successful
+    ** also mark the local connection as being locked.
+    */
+    if( rc==SQLITE_OK ){
+      rc = winShmSystemLock(pShmNode, _SHM_WRLCK, ofst+WIN_SHM_BASE, n);
+      if( rc==SQLITE_OK ){
+        assert( (p->sharedMask & mask)==0 );
+        p->exclMask |= mask;
+      }
+    }
+  }
+  sqlite3_mutex_leave(pShmNode->mutex);
+  OSTRACE(("SHM-LOCK shmid-%d, pid-%d got %03x,%03x %s\n",
+           p->id, (int)GetCurrentProcessId(), p->sharedMask, p->exclMask,
+           rc ? "failed" : "ok"));
+  return rc;
+}
+
+/*
+** Implement a memory barrier or memory fence on shared memory.  
+**
+** All loads and stores begun before the barrier must complete before
+** any load or store begun after the barrier.
+*/
+static void winShmBarrier(
+  sqlite3_file *fd          /* Database holding the shared memory */
+){
+  UNUSED_PARAMETER(fd);
+  /* MemoryBarrier(); // does not work -- do not know why not */
+  winShmEnterMutex();
+  winShmLeaveMutex();
+}
+
+/*
+** This function is called to obtain a pointer to region iRegion of the 
+** shared-memory associated with the database file fd. Shared-memory regions 
+** are numbered starting from zero. Each shared-memory region is szRegion 
+** bytes in size.
+**
+** If an error occurs, an error code is returned and *pp is set to NULL.
+**
+** Otherwise, if the isWrite parameter is 0 and the requested shared-memory
+** region has not been allocated (by any client, including one running in a
+** separate process), then *pp is set to NULL and SQLITE_OK returned. If 
+** isWrite is non-zero and the requested shared-memory region has not yet 
+** been allocated, it is allocated by this function.
+**
+** If the shared-memory region has already been allocated or is allocated by
+** this call as described above, then it is mapped into this processes 
+** address space (if it is not already), *pp is set to point to the mapped 
+** memory and SQLITE_OK returned.
+*/
+static int winShmMap(
+  sqlite3_file *fd,               /* Handle open on database file */
+  int iRegion,                    /* Region to retrieve */
+  int szRegion,                   /* Size of regions */
+  int isWrite,                    /* True to extend file if necessary */
+  void volatile **pp              /* OUT: Mapped memory */
+){
+  winFile *pDbFd = (winFile*)fd;
+  winShm *p = pDbFd->pShm;
+  winShmNode *pShmNode;
+  int rc = SQLITE_OK;
+
+  if( !p ){
+    rc = winOpenSharedMemory(pDbFd);
+    if( rc!=SQLITE_OK ) return rc;
+    p = pDbFd->pShm;
+  }
+  pShmNode = p->pShmNode;
+
+  sqlite3_mutex_enter(pShmNode->mutex);
+  assert( szRegion==pShmNode->szRegion || pShmNode->nRegion==0 );
+
+  if( pShmNode->nRegion<=iRegion ){
+    struct ShmRegion *apNew;           /* New aRegion[] array */
+    int nByte = (iRegion+1)*szRegion;  /* Minimum required file size */
+    sqlite3_int64 sz;                  /* Current size of wal-index file */
+
+    pShmNode->szRegion = szRegion;
+
+    /* The requested region is not mapped into this processes address space.
+    ** Check to see if it has been allocated (i.e. if the wal-index file is
+    ** large enough to contain the requested region).
+    */
+    rc = winFileSize((sqlite3_file *)&pShmNode->hFile, &sz);
+    if( rc!=SQLITE_OK ){
+      rc = SQLITE_IOERR_SHMSIZE;
+      goto shmpage_out;
+    }
+
+    if( sz<nByte ){
+      /* The requested memory region does not exist. If isWrite is set to
+      ** zero, exit early. *pp will be set to NULL and SQLITE_OK returned.
+      **
+      ** Alternatively, if isWrite is non-zero, use ftruncate() to allocate
+      ** the requested memory region.
+      */
+      if( !isWrite ) goto shmpage_out;
+      rc = winTruncate((sqlite3_file *)&pShmNode->hFile, nByte);
+      if( rc!=SQLITE_OK ){
+        rc = SQLITE_IOERR_SHMSIZE;
+        goto shmpage_out;
+      }
+    }
+
+    /* Map the requested memory region into this processes address space. */
+    apNew = (struct ShmRegion *)sqlite3_realloc(
+        pShmNode->aRegion, (iRegion+1)*sizeof(apNew[0])
+    );
+    if( !apNew ){
+      rc = SQLITE_IOERR_NOMEM;
+      goto shmpage_out;
+    }
+    pShmNode->aRegion = apNew;
+
+    while( pShmNode->nRegion<=iRegion ){
+      HANDLE hMap;                /* file-mapping handle */
+      void *pMap = 0;             /* Mapped memory region */
+     
+      hMap = CreateFileMapping(pShmNode->hFile.h, 
+          NULL, PAGE_READWRITE, 0, nByte, NULL
+      );
+      OSTRACE(("SHM-MAP pid-%d create region=%d nbyte=%d %s\n",
+               (int)GetCurrentProcessId(), pShmNode->nRegion, nByte,
+               hMap ? "ok" : "failed"));
+      if( hMap ){
+        int iOffset = pShmNode->nRegion*szRegion;
+        int iOffsetShift = iOffset % winSysInfo.dwAllocationGranularity;
+        pMap = MapViewOfFile(hMap, FILE_MAP_WRITE | FILE_MAP_READ,
+            0, iOffset - iOffsetShift, szRegion + iOffsetShift
+        );
+        OSTRACE(("SHM-MAP pid-%d map region=%d offset=%d size=%d %s\n",
+                 (int)GetCurrentProcessId(), pShmNode->nRegion, iOffset, szRegion,
+                 pMap ? "ok" : "failed"));
+      }
+      if( !pMap ){
+        pShmNode->lastErrno = GetLastError();
+        rc = SQLITE_IOERR;
+        if( hMap ) CloseHandle(hMap);
+        goto shmpage_out;
+      }
+
+      pShmNode->aRegion[pShmNode->nRegion].pMap = pMap;
+      pShmNode->aRegion[pShmNode->nRegion].hMap = hMap;
+      pShmNode->nRegion++;
+    }
+  }
+
+shmpage_out:
+  if( pShmNode->nRegion>iRegion ){
+    int iOffset = iRegion*szRegion;
+    int iOffsetShift = iOffset % winSysInfo.dwAllocationGranularity;
+    char *p = (char *)pShmNode->aRegion[iRegion].pMap;
+    *pp = (void *)&p[iOffsetShift];
+  }else{
+    *pp = 0;
+  }
+  sqlite3_mutex_leave(pShmNode->mutex);
+  return rc;
+}
+
+#else
+# define winShmMap     0
+# define winShmLock    0
+# define winShmBarrier 0
+# define winShmUnmap   0
+#endif /* #ifndef SQLITE_OMIT_WAL */
+
+/*
+** Here ends the implementation of all sqlite3_file methods.
+**
+********************** End sqlite3_file Methods *******************************
+******************************************************************************/
+
+/*
+** This vector defines all the methods that can operate on an
+** sqlite3_file for win32.
+*/
+static const sqlite3_io_methods winIoMethod = {
+  2,                              /* iVersion */
+  winClose,                       /* xClose */
+  winRead,                        /* xRead */
+  winWrite,                       /* xWrite */
+  winTruncate,                    /* xTruncate */
+  winSync,                        /* xSync */
+  winFileSize,                    /* xFileSize */
+  winLock,                        /* xLock */
+  winUnlock,                      /* xUnlock */
+  winCheckReservedLock,           /* xCheckReservedLock */
+  winFileControl,                 /* xFileControl */
+  winSectorSize,                  /* xSectorSize */
+  winDeviceCharacteristics,       /* xDeviceCharacteristics */
+  winShmMap,                      /* xShmMap */
+  winShmLock,                     /* xShmLock */
+  winShmBarrier,                  /* xShmBarrier */
+  winShmUnmap                     /* xShmUnmap */
+};
+
+/****************************************************************************
+**************************** sqlite3_vfs methods ****************************
+**
+** This division contains the implementation of methods on the
+** sqlite3_vfs object.
+*/
+
+/*
+** Convert a UTF-8 filename into whatever form the underlying
+** operating system wants filenames in.  Space to hold the result
+** is obtained from malloc and must be freed by the calling
+** function.
+*/
+static void *convertUtf8Filename(const char *zFilename){
+  void *zConverted = 0;
+  if( isNT() ){
+    zConverted = utf8ToUnicode(zFilename);
+/* isNT() is 1 if SQLITE_OS_WINCE==1, so this else is never executed. 
+*/
+#if SQLITE_OS_WINCE==0
+  }else{
+    zConverted = utf8ToMbcs(zFilename);
+#endif
+  }
+  /* caller will handle out of memory */
+  return zConverted;
+}
+
+/*
+** Create a temporary file name in zBuf.  zBuf must be big enough to
+** hold at pVfs->mxPathname characters.
+*/
+static int getTempname(int nBuf, char *zBuf){
+  static char zChars[] =
+    "abcdefghijklmnopqrstuvwxyz"
+    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+    "0123456789";
+  size_t i, j;
+  char zTempPath[MAX_PATH+1];
+
+  /* It's odd to simulate an io-error here, but really this is just
+  ** using the io-error infrastructure to test that SQLite handles this
+  ** function failing. 
+  */
+  SimulateIOError( return SQLITE_IOERR );
+
+  if( sqlite3_temp_directory ){
+    sqlite3_snprintf(MAX_PATH-30, zTempPath, "%s", sqlite3_temp_directory);
+  }else if( isNT() ){
+    char *zMulti;
+    WCHAR zWidePath[MAX_PATH];
+    GetTempPathW(MAX_PATH-30, zWidePath);
+    zMulti = unicodeToUtf8(zWidePath);
+    if( zMulti ){
+      sqlite3_snprintf(MAX_PATH-30, zTempPath, "%s", zMulti);
+      free(zMulti);
+    }else{
+      return SQLITE_NOMEM;
+    }
+/* isNT() is 1 if SQLITE_OS_WINCE==1, so this else is never executed. 
+** Since the ASCII version of these Windows API do not exist for WINCE,
+** it's important to not reference them for WINCE builds.
+*/
+#if SQLITE_OS_WINCE==0
+  }else{
+    char *zUtf8;
+    char zMbcsPath[MAX_PATH];
+    GetTempPathA(MAX_PATH-30, zMbcsPath);
+    zUtf8 = sqlite3_win32_mbcs_to_utf8(zMbcsPath);
+    if( zUtf8 ){
+      sqlite3_snprintf(MAX_PATH-30, zTempPath, "%s", zUtf8);
+      free(zUtf8);
+    }else{
+      return SQLITE_NOMEM;
+    }
+#endif
+  }
+
+  /* Check that the output buffer is large enough for the temporary file 
+  ** name. If it is not, return SQLITE_ERROR.
+  */
+  if( (sqlite3Strlen30(zTempPath) + sqlite3Strlen30(SQLITE_TEMP_FILE_PREFIX) + 17) >= nBuf ){
+    return SQLITE_ERROR;
+  }
+
+  for(i=sqlite3Strlen30(zTempPath); i>0 && zTempPath[i-1]=='\\'; i--){}
+  zTempPath[i] = 0;
+
+  sqlite3_snprintf(nBuf-17, zBuf,
+                   "%s\\"SQLITE_TEMP_FILE_PREFIX, zTempPath);
+  j = sqlite3Strlen30(zBuf);
+  sqlite3_randomness(15, &zBuf[j]);
+  for(i=0; i<15; i++, j++){
+    zBuf[j] = (char)zChars[ ((unsigned char)zBuf[j])%(sizeof(zChars)-1) ];
+  }
+  zBuf[j] = 0;
+
+  OSTRACE(("TEMP FILENAME: %s\n", zBuf));
+  return SQLITE_OK; 
+}
+
+/*
+** The return value of getLastErrorMsg
+** is zero if the error message fits in the buffer, or non-zero
+** otherwise (if the message was truncated).
+*/
+static int getLastErrorMsg(int nBuf, char *zBuf){
+  /* FormatMessage returns 0 on failure.  Otherwise it
+  ** returns the number of TCHARs written to the output
+  ** buffer, excluding the terminating null char.
+  */
+  DWORD error = GetLastError();
+  DWORD dwLen = 0;
+  char *zOut = 0;
+
+  if( isNT() ){
+    WCHAR *zTempWide = NULL;
+    dwLen = FormatMessageW(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
+                           NULL,
+                           error,
+                           0,
+                           (LPWSTR) &zTempWide,
+                           0,
+                           0);
+    if( dwLen > 0 ){
+      /* allocate a buffer and convert to UTF8 */
+      zOut = unicodeToUtf8(zTempWide);
+      /* free the system buffer allocated by FormatMessage */
+      LocalFree(zTempWide);
+    }
+/* isNT() is 1 if SQLITE_OS_WINCE==1, so this else is never executed. 
+** Since the ASCII version of these Windows API do not exist for WINCE,
+** it's important to not reference them for WINCE builds.
+*/
+#if SQLITE_OS_WINCE==0
+  }else{
+    char *zTemp = NULL;
+    dwLen = FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
+                           NULL,
+                           error,
+                           0,
+                           (LPSTR) &zTemp,
+                           0,
+                           0);
+    if( dwLen > 0 ){
+      /* allocate a buffer and convert to UTF8 */
+      zOut = sqlite3_win32_mbcs_to_utf8(zTemp);
+      /* free the system buffer allocated by FormatMessage */
+      LocalFree(zTemp);
+    }
+#endif
+  }
+  if( 0 == dwLen ){
+    sqlite3_snprintf(nBuf, zBuf, "OsError 0x%x (%u)", error, error);
+  }else{
+    /* copy a maximum of nBuf chars to output buffer */
+    sqlite3_snprintf(nBuf, zBuf, "%s", zOut);
+    /* free the UTF8 buffer */
+    free(zOut);
+  }
+  return 0;
+}
+
+/*
+** Open a file.
+*/
+static int winOpen(
+  sqlite3_vfs *pVfs,        /* Not used */
+  const char *zName,        /* Name of the file (UTF-8) */
+  sqlite3_file *id,         /* Write the SQLite file handle here */
+  int flags,                /* Open mode flags */
+  int *pOutFlags            /* Status return flags */
+){
+  HANDLE h;
+  DWORD dwDesiredAccess;
+  DWORD dwShareMode;
+  DWORD dwCreationDisposition;
+  DWORD dwFlagsAndAttributes = 0;
+#if SQLITE_OS_WINCE
+  int isTemp = 0;
+#endif
+  winFile *pFile = (winFile*)id;
+  void *zConverted;              /* Filename in OS encoding */
+  const char *zUtf8Name = zName; /* Filename in UTF-8 encoding */
+
+  /* If argument zPath is a NULL pointer, this function is required to open
+  ** a temporary file. Use this buffer to store the file name in.
+  */
+  char zTmpname[MAX_PATH+1];     /* Buffer used to create temp filename */
+
+  int rc = SQLITE_OK;            /* Function Return Code */
+#if !defined(NDEBUG) || SQLITE_OS_WINCE
+  int eType = flags&0xFFFFFF00;  /* Type of file to open */
+#endif
+
+  int isExclusive  = (flags & SQLITE_OPEN_EXCLUSIVE);
+  int isDelete     = (flags & SQLITE_OPEN_DELETEONCLOSE);
+  int isCreate     = (flags & SQLITE_OPEN_CREATE);
+#ifndef NDEBUG
+  int isReadonly   = (flags & SQLITE_OPEN_READONLY);
+#endif
+  int isReadWrite  = (flags & SQLITE_OPEN_READWRITE);
+
+#ifndef NDEBUG
+  int isOpenJournal = (isCreate && (
+        eType==SQLITE_OPEN_MASTER_JOURNAL 
+     || eType==SQLITE_OPEN_MAIN_JOURNAL 
+     || eType==SQLITE_OPEN_WAL
+  ));
+#endif
+
+  /* Check the following statements are true: 
+  **
+  **   (a) Exactly one of the READWRITE and READONLY flags must be set, and 
+  **   (b) if CREATE is set, then READWRITE must also be set, and
+  **   (c) if EXCLUSIVE is set, then CREATE must also be set.
+  **   (d) if DELETEONCLOSE is set, then CREATE must also be set.
+  */
+  assert((isReadonly==0 || isReadWrite==0) && (isReadWrite || isReadonly));
+  assert(isCreate==0 || isReadWrite);
+  assert(isExclusive==0 || isCreate);
+  assert(isDelete==0 || isCreate);
+
+  /* The main DB, main journal, WAL file and master journal are never 
+  ** automatically deleted. Nor are they ever temporary files.  */
+  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MAIN_DB );
+  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MAIN_JOURNAL );
+  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MASTER_JOURNAL );
+  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_WAL );
+
+  /* Assert that the upper layer has set one of the "file-type" flags. */
+  assert( eType==SQLITE_OPEN_MAIN_DB      || eType==SQLITE_OPEN_TEMP_DB 
+       || eType==SQLITE_OPEN_MAIN_JOURNAL || eType==SQLITE_OPEN_TEMP_JOURNAL 
+       || eType==SQLITE_OPEN_SUBJOURNAL   || eType==SQLITE_OPEN_MASTER_JOURNAL 
+       || eType==SQLITE_OPEN_TRANSIENT_DB || eType==SQLITE_OPEN_WAL
+  );
+
+  assert( id!=0 );
+  UNUSED_PARAMETER(pVfs);
+
+  pFile->h = INVALID_HANDLE_VALUE;
+
+  /* If the second argument to this function is NULL, generate a 
+  ** temporary file name to use 
+  */
+  if( !zUtf8Name ){
+    assert(isDelete && !isOpenJournal);
+    rc = getTempname(MAX_PATH+1, zTmpname);
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+    zUtf8Name = zTmpname;
+  }
+
+  /* Convert the filename to the system encoding. */
+  zConverted = convertUtf8Filename(zUtf8Name);
+  if( zConverted==0 ){
+    return SQLITE_NOMEM;
+  }
+
+  if( isReadWrite ){
+    dwDesiredAccess = GENERIC_READ | GENERIC_WRITE;
+  }else{
+    dwDesiredAccess = GENERIC_READ;
+  }
+
+  /* SQLITE_OPEN_EXCLUSIVE is used to make sure that a new file is 
+  ** created. SQLite doesn't use it to indicate "exclusive access" 
+  ** as it is usually understood.
+  */
+  if( isExclusive ){
+    /* Creates a new file, only if it does not already exist. */
+    /* If the file exists, it fails. */
+    dwCreationDisposition = CREATE_NEW;
+  }else if( isCreate ){
+    /* Open existing file, or create if it doesn't exist */
+    dwCreationDisposition = OPEN_ALWAYS;
+  }else{
+    /* Opens a file, only if it exists. */
+    dwCreationDisposition = OPEN_EXISTING;
+  }
+
+  dwShareMode = FILE_SHARE_READ | FILE_SHARE_WRITE;
+
+  if( isDelete ){
+#if SQLITE_OS_WINCE
+    dwFlagsAndAttributes = FILE_ATTRIBUTE_HIDDEN;
+    isTemp = 1;
+#else
+    dwFlagsAndAttributes = FILE_ATTRIBUTE_TEMPORARY
+                               | FILE_ATTRIBUTE_HIDDEN
+                               | FILE_FLAG_DELETE_ON_CLOSE;
+#endif
+  }else{
+    dwFlagsAndAttributes = FILE_ATTRIBUTE_NORMAL;
+  }
+  /* Reports from the internet are that performance is always
+  ** better if FILE_FLAG_RANDOM_ACCESS is used.  Ticket #2699. */
+#if SQLITE_OS_WINCE
+  dwFlagsAndAttributes |= FILE_FLAG_RANDOM_ACCESS;
+#endif
+
+  if( isNT() ){
+    h = CreateFileW((WCHAR*)zConverted,
+       dwDesiredAccess,
+       dwShareMode,
+       NULL,
+       dwCreationDisposition,
+       dwFlagsAndAttributes,
+       NULL
+    );
+/* isNT() is 1 if SQLITE_OS_WINCE==1, so this else is never executed. 
+** Since the ASCII version of these Windows API do not exist for WINCE,
+** it's important to not reference them for WINCE builds.
+*/
+#if SQLITE_OS_WINCE==0
+  }else{
+    h = CreateFileA((char*)zConverted,
+       dwDesiredAccess,
+       dwShareMode,
+       NULL,
+       dwCreationDisposition,
+       dwFlagsAndAttributes,
+       NULL
+    );
+#endif
+  }
+
+  OSTRACE(("OPEN %d %s 0x%lx %s\n", 
+           h, zName, dwDesiredAccess, 
+           h==INVALID_HANDLE_VALUE ? "failed" : "ok"));
+
+  if( h==INVALID_HANDLE_VALUE ){
+    pFile->lastErrno = GetLastError();
+    free(zConverted);
+    if( isReadWrite ){
+      return winOpen(pVfs, zName, id, 
+             ((flags|SQLITE_OPEN_READONLY)&~(SQLITE_OPEN_CREATE|SQLITE_OPEN_READWRITE)), pOutFlags);
+    }else{
+      return SQLITE_CANTOPEN_BKPT;
+    }
+  }
+
+  if( pOutFlags ){
+    if( isReadWrite ){
+      *pOutFlags = SQLITE_OPEN_READWRITE;
+    }else{
+      *pOutFlags = SQLITE_OPEN_READONLY;
+    }
+  }
+
+  memset(pFile, 0, sizeof(*pFile));
+  pFile->pMethod = &winIoMethod;
+  pFile->h = h;
+  pFile->lastErrno = NO_ERROR;
+  pFile->pVfs = pVfs;
+  pFile->pShm = 0;
+  pFile->zPath = zName;
+  pFile->sectorSize = getSectorSize(pVfs, zUtf8Name);
+
+#if SQLITE_OS_WINCE
+  if( isReadWrite && eType==SQLITE_OPEN_MAIN_DB
+       && !winceCreateLock(zName, pFile)
+  ){
+    CloseHandle(h);
+    free(zConverted);
+    return SQLITE_CANTOPEN_BKPT;
+  }
+  if( isTemp ){
+    pFile->zDeleteOnClose = zConverted;
+  }else
+#endif
+  {
+    free(zConverted);
+  }
+
+  OpenCounter(+1);
+  return rc;
+}
+
+/*
+** Delete the named file.
+**
+** Note that windows does not allow a file to be deleted if some other
+** process has it open.  Sometimes a virus scanner or indexing program
+** will open a journal file shortly after it is created in order to do
+** whatever it does.  While this other process is holding the
+** file open, we will be unable to delete it.  To work around this
+** problem, we delay 100 milliseconds and try to delete again.  Up
+** to MX_DELETION_ATTEMPTs deletion attempts are run before giving
+** up and returning an error.
+*/
+#define MX_DELETION_ATTEMPTS 5
+static int winDelete(
+  sqlite3_vfs *pVfs,          /* Not used on win32 */
+  const char *zFilename,      /* Name of file to delete */
+  int syncDir                 /* Not used on win32 */
+){
+  int cnt = 0;
+  DWORD rc;
+  DWORD error = 0;
+  void *zConverted;
+  UNUSED_PARAMETER(pVfs);
+  UNUSED_PARAMETER(syncDir);
+
+  SimulateIOError(return SQLITE_IOERR_DELETE);
+  zConverted = convertUtf8Filename(zFilename);
+  if( zConverted==0 ){
+    return SQLITE_NOMEM;
+  }
+  if( isNT() ){
+    do{
+      DeleteFileW(zConverted);
+    }while(   (   ((rc = GetFileAttributesW(zConverted)) != INVALID_FILE_ATTRIBUTES)
+               || ((error = GetLastError()) == ERROR_ACCESS_DENIED))
+           && (++cnt < MX_DELETION_ATTEMPTS)
+           && (Sleep(100), 1) );
+/* isNT() is 1 if SQLITE_OS_WINCE==1, so this else is never executed. 
+** Since the ASCII version of these Windows API do not exist for WINCE,
+** it's important to not reference them for WINCE builds.
+*/
+#if SQLITE_OS_WINCE==0
+  }else{
+    do{
+      DeleteFileA(zConverted);
+    }while(   (   ((rc = GetFileAttributesA(zConverted)) != INVALID_FILE_ATTRIBUTES)
+               || ((error = GetLastError()) == ERROR_ACCESS_DENIED))
+           && (++cnt < MX_DELETION_ATTEMPTS)
+           && (Sleep(100), 1) );
+#endif
+  }
+  free(zConverted);
+  OSTRACE(("DELETE \"%s\" %s\n", zFilename,
+       ( (rc==INVALID_FILE_ATTRIBUTES) && (error==ERROR_FILE_NOT_FOUND)) ?
+         "ok" : "failed" ));
+ 
+  return (   (rc == INVALID_FILE_ATTRIBUTES) 
+          && (error == ERROR_FILE_NOT_FOUND)) ? SQLITE_OK : SQLITE_IOERR_DELETE;
+}
+
+/*
+** Check the existance and status of a file.
+*/
+static int winAccess(
+  sqlite3_vfs *pVfs,         /* Not used on win32 */
+  const char *zFilename,     /* Name of file to check */
+  int flags,                 /* Type of test to make on this file */
+  int *pResOut               /* OUT: Result */
+){
+  DWORD attr;
+  int rc = 0;
+  void *zConverted;
+  UNUSED_PARAMETER(pVfs);
+
+  SimulateIOError( return SQLITE_IOERR_ACCESS; );
+  zConverted = convertUtf8Filename(zFilename);
+  if( zConverted==0 ){
+    return SQLITE_NOMEM;
+  }
+  if( isNT() ){
+    WIN32_FILE_ATTRIBUTE_DATA sAttrData;
+    memset(&sAttrData, 0, sizeof(sAttrData));
+    if( GetFileAttributesExW((WCHAR*)zConverted,
+                             GetFileExInfoStandard, 
+                             &sAttrData) ){
+      /* For an SQLITE_ACCESS_EXISTS query, treat a zero-length file
+      ** as if it does not exist.
+      */
+      if(    flags==SQLITE_ACCESS_EXISTS
+          && sAttrData.nFileSizeHigh==0 
+          && sAttrData.nFileSizeLow==0 ){
+        attr = INVALID_FILE_ATTRIBUTES;
+      }else{
+        attr = sAttrData.dwFileAttributes;
+      }
+    }else{
+      if( GetLastError()!=ERROR_FILE_NOT_FOUND ){
+        free(zConverted);
+        return SQLITE_IOERR_ACCESS;
+      }else{
+        attr = INVALID_FILE_ATTRIBUTES;
+      }
+    }
+/* isNT() is 1 if SQLITE_OS_WINCE==1, so this else is never executed. 
+** Since the ASCII version of these Windows API do not exist for WINCE,
+** it's important to not reference them for WINCE builds.
+*/
+#if SQLITE_OS_WINCE==0
+  }else{
+    attr = GetFileAttributesA((char*)zConverted);
+#endif
+  }
+  free(zConverted);
+  switch( flags ){
+    case SQLITE_ACCESS_READ:
+    case SQLITE_ACCESS_EXISTS:
+      rc = attr!=INVALID_FILE_ATTRIBUTES;
+      break;
+    case SQLITE_ACCESS_READWRITE:
+      rc = (attr & FILE_ATTRIBUTE_READONLY)==0;
+      break;
+    default:
+      assert(!"Invalid flags argument");
+  }
+  *pResOut = rc;
+  return SQLITE_OK;
+}
+
+
+/*
+** Turn a relative pathname into a full pathname.  Write the full
+** pathname into zOut[].  zOut[] will be at least pVfs->mxPathname
+** bytes in size.
+*/
+static int winFullPathname(
+  sqlite3_vfs *pVfs,            /* Pointer to vfs object */
+  const char *zRelative,        /* Possibly relative input path */
+  int nFull,                    /* Size of output buffer in bytes */
+  char *zFull                   /* Output buffer */
+){
+  
+#if defined(__CYGWIN__)
+  SimulateIOError( return SQLITE_ERROR );
+  UNUSED_PARAMETER(nFull);
+  cygwin_conv_to_full_win32_path(zRelative, zFull);
+  return SQLITE_OK;
+#endif
+
+#if SQLITE_OS_WINCE
+  SimulateIOError( return SQLITE_ERROR );
+  UNUSED_PARAMETER(nFull);
+  /* WinCE has no concept of a relative pathname, or so I am told. */
+  sqlite3_snprintf(pVfs->mxPathname, zFull, "%s", zRelative);
+  return SQLITE_OK;
+#endif
+
+#if !SQLITE_OS_WINCE && !defined(__CYGWIN__)
+  int nByte;
+  void *zConverted;
+  char *zOut;
+
+  /* It's odd to simulate an io-error here, but really this is just
+  ** using the io-error infrastructure to test that SQLite handles this
+  ** function failing. This function could fail if, for example, the
+  ** current working directory has been unlinked.
+  */
+  SimulateIOError( return SQLITE_ERROR );
+  UNUSED_PARAMETER(nFull);
+  zConverted = convertUtf8Filename(zRelative);
+  if( isNT() ){
+    WCHAR *zTemp;
+    nByte = GetFullPathNameW((WCHAR*)zConverted, 0, 0, 0) + 3;
+    zTemp = malloc( nByte*sizeof(zTemp[0]) );
+    if( zTemp==0 ){
+      free(zConverted);
+      return SQLITE_NOMEM;
+    }
+    GetFullPathNameW((WCHAR*)zConverted, nByte, zTemp, 0);
+    free(zConverted);
+    zOut = unicodeToUtf8(zTemp);
+    free(zTemp);
+/* isNT() is 1 if SQLITE_OS_WINCE==1, so this else is never executed. 
+** Since the ASCII version of these Windows API do not exist for WINCE,
+** it's important to not reference them for WINCE builds.
+*/
+#if SQLITE_OS_WINCE==0
+  }else{
+    char *zTemp;
+    nByte = GetFullPathNameA((char*)zConverted, 0, 0, 0) + 3;
+    zTemp = malloc( nByte*sizeof(zTemp[0]) );
+    if( zTemp==0 ){
+      free(zConverted);
+      return SQLITE_NOMEM;
+    }
+    GetFullPathNameA((char*)zConverted, nByte, zTemp, 0);
+    free(zConverted);
+    zOut = sqlite3_win32_mbcs_to_utf8(zTemp);
+    free(zTemp);
+#endif
+  }
+  if( zOut ){
+    sqlite3_snprintf(pVfs->mxPathname, zFull, "%s", zOut);
+    free(zOut);
+    return SQLITE_OK;
+  }else{
+    return SQLITE_NOMEM;
+  }
+#endif
+}
+
+/*
+** Get the sector size of the device used to store
+** file.
+*/
+static int getSectorSize(
+    sqlite3_vfs *pVfs,
+    const char *zRelative     /* UTF-8 file name */
+){
+  DWORD bytesPerSector = SQLITE_DEFAULT_SECTOR_SIZE;
+  /* GetDiskFreeSpace is not supported under WINCE */
+#if SQLITE_OS_WINCE
+  UNUSED_PARAMETER(pVfs);
+  UNUSED_PARAMETER(zRelative);
+#else
+  char zFullpath[MAX_PATH+1];
+  int rc;
+  DWORD dwRet = 0;
+  DWORD dwDummy;
+
+  /*
+  ** We need to get the full path name of the file
+  ** to get the drive letter to look up the sector
+  ** size.
+  */
+  SimulateIOErrorBenign(1);
+  rc = winFullPathname(pVfs, zRelative, MAX_PATH, zFullpath);
+  SimulateIOErrorBenign(0);
+  if( rc == SQLITE_OK )
+  {
+    void *zConverted = convertUtf8Filename(zFullpath);
+    if( zConverted ){
+      if( isNT() ){
+        /* trim path to just drive reference */
+        WCHAR *p = zConverted;
+        for(;*p;p++){
+          if( *p == '\\' ){
+            *p = '\0';
+            break;
+          }
+        }
+        dwRet = GetDiskFreeSpaceW((WCHAR*)zConverted,
+                                  &dwDummy,
+                                  &bytesPerSector,
+                                  &dwDummy,
+                                  &dwDummy);
+      }else{
+        /* trim path to just drive reference */
+        char *p = (char *)zConverted;
+        for(;*p;p++){
+          if( *p == '\\' ){
+            *p = '\0';
+            break;
+          }
+        }
+        dwRet = GetDiskFreeSpaceA((char*)zConverted,
+                                  &dwDummy,
+                                  &bytesPerSector,
+                                  &dwDummy,
+                                  &dwDummy);
+      }
+      free(zConverted);
+    }
+    if( !dwRet ){
+      bytesPerSector = SQLITE_DEFAULT_SECTOR_SIZE;
+    }
+  }
+#endif
+  return (int) bytesPerSector; 
+}
+
+#ifndef SQLITE_OMIT_LOAD_EXTENSION
+/*
+** Interfaces for opening a shared library, finding entry points
+** within the shared library, and closing the shared library.
+*/
+/*
+** Interfaces for opening a shared library, finding entry points
+** within the shared library, and closing the shared library.
+*/
+static void *winDlOpen(sqlite3_vfs *pVfs, const char *zFilename){
+  HANDLE h;
+  void *zConverted = convertUtf8Filename(zFilename);
+  UNUSED_PARAMETER(pVfs);
+  if( zConverted==0 ){
+    return 0;
+  }
+  if( isNT() ){
+    h = LoadLibraryW((WCHAR*)zConverted);
+/* isNT() is 1 if SQLITE_OS_WINCE==1, so this else is never executed. 
+** Since the ASCII version of these Windows API do not exist for WINCE,
+** it's important to not reference them for WINCE builds.
+*/
+#if SQLITE_OS_WINCE==0
+  }else{
+    h = LoadLibraryA((char*)zConverted);
+#endif
+  }
+  free(zConverted);
+  return (void*)h;
+}
+static void winDlError(sqlite3_vfs *pVfs, int nBuf, char *zBufOut){
+  UNUSED_PARAMETER(pVfs);
+  getLastErrorMsg(nBuf, zBufOut);
+}
+void (*winDlSym(sqlite3_vfs *pVfs, void *pHandle, const char *zSymbol))(void){
+  UNUSED_PARAMETER(pVfs);
+#if SQLITE_OS_WINCE
+  /* The GetProcAddressA() routine is only available on wince. */
+  return (void(*)(void))GetProcAddressA((HANDLE)pHandle, zSymbol);
+#else
+  /* All other windows platforms expect GetProcAddress() to take
+  ** an Ansi string regardless of the _UNICODE setting */
+  return (void(*)(void))GetProcAddress((HANDLE)pHandle, zSymbol);
+#endif
+}
+void winDlClose(sqlite3_vfs *pVfs, void *pHandle){
+  UNUSED_PARAMETER(pVfs);
+  FreeLibrary((HANDLE)pHandle);
+}
+#else /* if SQLITE_OMIT_LOAD_EXTENSION is defined: */
+  #define winDlOpen  0
+  #define winDlError 0
+  #define winDlSym   0
+  #define winDlClose 0
+#endif
+
+
+/*
+** Write up to nBuf bytes of randomness into zBuf.
+*/
+static int winRandomness(sqlite3_vfs *pVfs, int nBuf, char *zBuf){
+  int n = 0;
+  UNUSED_PARAMETER(pVfs);
+#if defined(SQLITE_TEST)
+  n = nBuf;
+  memset(zBuf, 0, nBuf);
+#else
+  if( sizeof(SYSTEMTIME)<=nBuf-n ){
+    SYSTEMTIME x;
+    GetSystemTime(&x);
+    memcpy(&zBuf[n], &x, sizeof(x));
+    n += sizeof(x);
+  }
+  if( sizeof(DWORD)<=nBuf-n ){
+    DWORD pid = GetCurrentProcessId();
+    memcpy(&zBuf[n], &pid, sizeof(pid));
+    n += sizeof(pid);
+  }
+  if( sizeof(DWORD)<=nBuf-n ){
+    DWORD cnt = GetTickCount();
+    memcpy(&zBuf[n], &cnt, sizeof(cnt));
+    n += sizeof(cnt);
+  }
+  if( sizeof(LARGE_INTEGER)<=nBuf-n ){
+    LARGE_INTEGER i;
+    QueryPerformanceCounter(&i);
+    memcpy(&zBuf[n], &i, sizeof(i));
+    n += sizeof(i);
+  }
+#endif
+  return n;
+}
+
+
+/*
+** Sleep for a little while.  Return the amount of time slept.
+*/
+static int winSleep(sqlite3_vfs *pVfs, int microsec){
+  Sleep((microsec+999)/1000);
+  UNUSED_PARAMETER(pVfs);
+  return ((microsec+999)/1000)*1000;
+}
+
+/*
+** The following variable, if set to a non-zero value, is interpreted as
+** the number of seconds since 1970 and is used to set the result of
+** sqlite3OsCurrentTime() during testing.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_current_time = 0;  /* Fake system time in seconds since 1970. */
+#endif
+
+/*
+** Find the current time (in Universal Coordinated Time).  Write into *piNow
+** the current time and date as a Julian Day number times 86_400_000.  In
+** other words, write into *piNow the number of milliseconds since the Julian
+** epoch of noon in Greenwich on November 24, 4714 B.C according to the
+** proleptic Gregorian calendar.
+**
+** On success, return 0.  Return 1 if the time and date cannot be found.
+*/
+static int winCurrentTimeInt64(sqlite3_vfs *pVfs, sqlite3_int64 *piNow){
+  /* FILETIME structure is a 64-bit value representing the number of 
+     100-nanosecond intervals since January 1, 1601 (= JD 2305813.5). 
+  */
+  FILETIME ft;
+  static const sqlite3_int64 winFiletimeEpoch = 23058135*(sqlite3_int64)8640000;
+#ifdef SQLITE_TEST
+  static const sqlite3_int64 unixEpoch = 24405875*(sqlite3_int64)8640000;
+#endif
+  /* 2^32 - to avoid use of LL and warnings in gcc */
+  static const sqlite3_int64 max32BitValue = 
+      (sqlite3_int64)2000000000 + (sqlite3_int64)2000000000 + (sqlite3_int64)294967296;
+
+#if SQLITE_OS_WINCE
+  SYSTEMTIME time;
+  GetSystemTime(&time);
+  /* if SystemTimeToFileTime() fails, it returns zero. */
+  if (!SystemTimeToFileTime(&time,&ft)){
+    return 1;
+  }
+#else
+  GetSystemTimeAsFileTime( &ft );
+#endif
+
+  *piNow = winFiletimeEpoch +
+            ((((sqlite3_int64)ft.dwHighDateTime)*max32BitValue) + 
+               (sqlite3_int64)ft.dwLowDateTime)/(sqlite3_int64)10000;
+
+#ifdef SQLITE_TEST
+  if( sqlite3_current_time ){
+    *piNow = 1000*(sqlite3_int64)sqlite3_current_time + unixEpoch;
+  }
+#endif
+  UNUSED_PARAMETER(pVfs);
+  return 0;
+}
+
+/*
+** Find the current time (in Universal Coordinated Time).  Write the
+** current time and date as a Julian Day number into *prNow and
+** return 0.  Return 1 if the time and date cannot be found.
+*/
+int winCurrentTime(sqlite3_vfs *pVfs, double *prNow){
+  int rc;
+  sqlite3_int64 i;
+  rc = winCurrentTimeInt64(pVfs, &i);
+  if( !rc ){
+    *prNow = i/86400000.0;
+  }
+  return rc;
+}
+
+/*
+** The idea is that this function works like a combination of
+** GetLastError() and FormatMessage() on windows (or errno and
+** strerror_r() on unix). After an error is returned by an OS
+** function, SQLite calls this function with zBuf pointing to
+** a buffer of nBuf bytes. The OS layer should populate the
+** buffer with a nul-terminated UTF-8 encoded error message
+** describing the last IO error to have occurred within the calling
+** thread.
+**
+** If the error message is too large for the supplied buffer,
+** it should be truncated. The return value of xGetLastError
+** is zero if the error message fits in the buffer, or non-zero
+** otherwise (if the message was truncated). If non-zero is returned,
+** then it is not necessary to include the nul-terminator character
+** in the output buffer.
+**
+** Not supplying an error message will have no adverse effect
+** on SQLite. It is fine to have an implementation that never
+** returns an error message:
+**
+**   int xGetLastError(sqlite3_vfs *pVfs, int nBuf, char *zBuf){
+**     assert(zBuf[0]=='\0');
+**     return 0;
+**   }
+**
+** However if an error message is supplied, it will be incorporated
+** by sqlite into the error message available to the user using
+** sqlite3_errmsg(), possibly making IO errors easier to debug.
+*/
+static int winGetLastError(sqlite3_vfs *pVfs, int nBuf, char *zBuf){
+  UNUSED_PARAMETER(pVfs);
+  return getLastErrorMsg(nBuf, zBuf);
+}
+
+
+
+/*
+** Initialize and deinitialize the operating system interface.
+*/
+SQLITE_API int sqlite3_os_init(void){
+  static sqlite3_vfs winVfs = {
+    3,                   /* iVersion */
+    sizeof(winFile),     /* szOsFile */
+    MAX_PATH,            /* mxPathname */
+    0,                   /* pNext */
+    "win32",             /* zName */
+    0,                   /* pAppData */
+    winOpen,             /* xOpen */
+    winDelete,           /* xDelete */
+    winAccess,           /* xAccess */
+    winFullPathname,     /* xFullPathname */
+    winDlOpen,           /* xDlOpen */
+    winDlError,          /* xDlError */
+    winDlSym,            /* xDlSym */
+    winDlClose,          /* xDlClose */
+    winRandomness,       /* xRandomness */
+    winSleep,            /* xSleep */
+    winCurrentTime,      /* xCurrentTime */
+    winGetLastError,     /* xGetLastError */
+    winCurrentTimeInt64, /* xCurrentTimeInt64 */
+    0,                   /* xSetSystemCall */
+    0,                   /* xGetSystemCall */
+    0,                   /* xNextSystemCall */
+  };
+
+#ifndef SQLITE_OMIT_WAL
+  /* get memory map allocation granularity */
+  memset(&winSysInfo, 0, sizeof(SYSTEM_INFO));
+  GetSystemInfo(&winSysInfo);
+  assert(winSysInfo.dwAllocationGranularity > 0);
+#endif
+
+  sqlite3_vfs_register(&winVfs, 1);
+  return SQLITE_OK; 
+}
+SQLITE_API int sqlite3_os_end(void){ 
+  return SQLITE_OK;
+}
+
+#endif /* SQLITE_OS_WIN */
+
+/************** End of os_win.c **********************************************/
+/************** Begin file bitvec.c ******************************************/
+/*
+** 2008 February 16
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file implements an object that represents a fixed-length
+** bitmap.  Bits are numbered starting with 1.
+**
+** A bitmap is used to record which pages of a database file have been
+** journalled during a transaction, or which pages have the "dont-write"
+** property.  Usually only a few pages are meet either condition.
+** So the bitmap is usually sparse and has low cardinality.
+** But sometimes (for example when during a DROP of a large table) most
+** or all of the pages in a database can get journalled.  In those cases, 
+** the bitmap becomes dense with high cardinality.  The algorithm needs 
+** to handle both cases well.
+**
+** The size of the bitmap is fixed when the object is created.
+**
+** All bits are clear when the bitmap is created.  Individual bits
+** may be set or cleared one at a time.
+**
+** Test operations are about 100 times more common that set operations.
+** Clear operations are exceedingly rare.  There are usually between
+** 5 and 500 set operations per Bitvec object, though the number of sets can
+** sometimes grow into tens of thousands or larger.  The size of the
+** Bitvec object is the number of pages in the database file at the
+** start of a transaction, and is thus usually less than a few thousand,
+** but can be as large as 2 billion for a really big database.
+*/
+
+/* Size of the Bitvec structure in bytes. */
+#define BITVEC_SZ        512
+
+/* Round the union size down to the nearest pointer boundary, since that's how 
+** it will be aligned within the Bitvec struct. */
+#define BITVEC_USIZE     (((BITVEC_SZ-(3*sizeof(u32)))/sizeof(Bitvec*))*sizeof(Bitvec*))
+
+/* Type of the array "element" for the bitmap representation. 
+** Should be a power of 2, and ideally, evenly divide into BITVEC_USIZE. 
+** Setting this to the "natural word" size of your CPU may improve
+** performance. */
+#define BITVEC_TELEM     u8
+/* Size, in bits, of the bitmap element. */
+#define BITVEC_SZELEM    8
+/* Number of elements in a bitmap array. */
+#define BITVEC_NELEM     (BITVEC_USIZE/sizeof(BITVEC_TELEM))
+/* Number of bits in the bitmap array. */
+#define BITVEC_NBIT      (BITVEC_NELEM*BITVEC_SZELEM)
+
+/* Number of u32 values in hash table. */
+#define BITVEC_NINT      (BITVEC_USIZE/sizeof(u32))
+/* Maximum number of entries in hash table before 
+** sub-dividing and re-hashing. */
+#define BITVEC_MXHASH    (BITVEC_NINT/2)
+/* Hashing function for the aHash representation.
+** Empirical testing showed that the *37 multiplier 
+** (an arbitrary prime)in the hash function provided 
+** no fewer collisions than the no-op *1. */
+#define BITVEC_HASH(X)   (((X)*1)%BITVEC_NINT)
+
+#define BITVEC_NPTR      (BITVEC_USIZE/sizeof(Bitvec *))
+
+
+/*
+** A bitmap is an instance of the following structure.
+**
+** This bitmap records the existance of zero or more bits
+** with values between 1 and iSize, inclusive.
+**
+** There are three possible representations of the bitmap.
+** If iSize<=BITVEC_NBIT, then Bitvec.u.aBitmap[] is a straight
+** bitmap.  The least significant bit is bit 1.
+**
+** If iSize>BITVEC_NBIT and iDivisor==0 then Bitvec.u.aHash[] is
+** a hash table that will hold up to BITVEC_MXHASH distinct values.
+**
+** Otherwise, the value i is redirected into one of BITVEC_NPTR
+** sub-bitmaps pointed to by Bitvec.u.apSub[].  Each subbitmap
+** handles up to iDivisor separate values of i.  apSub[0] holds
+** values between 1 and iDivisor.  apSub[1] holds values between
+** iDivisor+1 and 2*iDivisor.  apSub[N] holds values between
+** N*iDivisor+1 and (N+1)*iDivisor.  Each subbitmap is normalized
+** to hold deal with values between 1 and iDivisor.
+*/
+struct Bitvec {
+  u32 iSize;      /* Maximum bit index.  Max iSize is 4,294,967,296. */
+  u32 nSet;       /* Number of bits that are set - only valid for aHash
+                  ** element.  Max is BITVEC_NINT.  For BITVEC_SZ of 512,
+                  ** this would be 125. */
+  u32 iDivisor;   /* Number of bits handled by each apSub[] entry. */
+                  /* Should >=0 for apSub element. */
+                  /* Max iDivisor is max(u32) / BITVEC_NPTR + 1.  */
+                  /* For a BITVEC_SZ of 512, this would be 34,359,739. */
+  union {
+    BITVEC_TELEM aBitmap[BITVEC_NELEM];    /* Bitmap representation */
+    u32 aHash[BITVEC_NINT];      /* Hash table representation */
+    Bitvec *apSub[BITVEC_NPTR];  /* Recursive representation */
+  } u;
+};
+
+/*
+** Create a new bitmap object able to handle bits between 0 and iSize,
+** inclusive.  Return a pointer to the new object.  Return NULL if 
+** malloc fails.
+*/
+SQLITE_PRIVATE Bitvec *sqlite3BitvecCreate(u32 iSize){
+  Bitvec *p;
+  assert( sizeof(*p)==BITVEC_SZ );
+  p = sqlite3MallocZero( sizeof(*p) );
+  if( p ){
+    p->iSize = iSize;
+  }
+  return p;
+}
+
+/*
+** Check to see if the i-th bit is set.  Return true or false.
+** If p is NULL (if the bitmap has not been created) or if
+** i is out of range, then return false.
+*/
+SQLITE_PRIVATE int sqlite3BitvecTest(Bitvec *p, u32 i){
+  if( p==0 ) return 0;
+  if( i>p->iSize || i==0 ) return 0;
+  i--;
+  while( p->iDivisor ){
+    u32 bin = i/p->iDivisor;
+    i = i%p->iDivisor;
+    p = p->u.apSub[bin];
+    if (!p) {
+      return 0;
+    }
+  }
+  if( p->iSize<=BITVEC_NBIT ){
+    return (p->u.aBitmap[i/BITVEC_SZELEM] & (1<<(i&(BITVEC_SZELEM-1))))!=0;
+  } else{
+    u32 h = BITVEC_HASH(i++);
+    while( p->u.aHash[h] ){
+      if( p->u.aHash[h]==i ) return 1;
+      h = (h+1) % BITVEC_NINT;
+    }
+    return 0;
+  }
+}
+
+/*
+** Set the i-th bit.  Return 0 on success and an error code if
+** anything goes wrong.
+**
+** This routine might cause sub-bitmaps to be allocated.  Failing
+** to get the memory needed to hold the sub-bitmap is the only
+** that can go wrong with an insert, assuming p and i are valid.
+**
+** The calling function must ensure that p is a valid Bitvec object
+** and that the value for "i" is within range of the Bitvec object.
+** Otherwise the behavior is undefined.
+*/
+SQLITE_PRIVATE int sqlite3BitvecSet(Bitvec *p, u32 i){
+  u32 h;
+  if( p==0 ) return SQLITE_OK;
+  assert( i>0 );
+  assert( i<=p->iSize );
+  i--;
+  while((p->iSize > BITVEC_NBIT) && p->iDivisor) {
+    u32 bin = i/p->iDivisor;
+    i = i%p->iDivisor;
+    if( p->u.apSub[bin]==0 ){
+      p->u.apSub[bin] = sqlite3BitvecCreate( p->iDivisor );
+      if( p->u.apSub[bin]==0 ) return SQLITE_NOMEM;
+    }
+    p = p->u.apSub[bin];
+  }
+  if( p->iSize<=BITVEC_NBIT ){
+    p->u.aBitmap[i/BITVEC_SZELEM] |= 1 << (i&(BITVEC_SZELEM-1));
+    return SQLITE_OK;
+  }
+  h = BITVEC_HASH(i++);
+  /* if there wasn't a hash collision, and this doesn't */
+  /* completely fill the hash, then just add it without */
+  /* worring about sub-dividing and re-hashing. */
+  if( !p->u.aHash[h] ){
+    if (p->nSet<(BITVEC_NINT-1)) {
+      goto bitvec_set_end;
+    } else {
+      goto bitvec_set_rehash;
+    }
+  }
+  /* there was a collision, check to see if it's already */
+  /* in hash, if not, try to find a spot for it */
+  do {
+    if( p->u.aHash[h]==i ) return SQLITE_OK;
+    h++;
+    if( h>=BITVEC_NINT ) h = 0;
+  } while( p->u.aHash[h] );
+  /* we didn't find it in the hash.  h points to the first */
+  /* available free spot. check to see if this is going to */
+  /* make our hash too "full".  */
+bitvec_set_rehash:
+  if( p->nSet>=BITVEC_MXHASH ){
+    unsigned int j;
+    int rc;
+    u32 *aiValues = sqlite3StackAllocRaw(0, sizeof(p->u.aHash));
+    if( aiValues==0 ){
+      return SQLITE_NOMEM;
+    }else{
+      memcpy(aiValues, p->u.aHash, sizeof(p->u.aHash));
+      memset(p->u.apSub, 0, sizeof(p->u.apSub));
+      p->iDivisor = (p->iSize + BITVEC_NPTR - 1)/BITVEC_NPTR;
+      rc = sqlite3BitvecSet(p, i);
+      for(j=0; j<BITVEC_NINT; j++){
+        if( aiValues[j] ) rc |= sqlite3BitvecSet(p, aiValues[j]);
+      }
+      sqlite3StackFree(0, aiValues);
+      return rc;
+    }
+  }
+bitvec_set_end:
+  p->nSet++;
+  p->u.aHash[h] = i;
+  return SQLITE_OK;
+}
+
+/*
+** Clear the i-th bit.
+**
+** pBuf must be a pointer to at least BITVEC_SZ bytes of temporary storage
+** that BitvecClear can use to rebuilt its hash table.
+*/
+SQLITE_PRIVATE void sqlite3BitvecClear(Bitvec *p, u32 i, void *pBuf){
+  if( p==0 ) return;
+  assert( i>0 );
+  i--;
+  while( p->iDivisor ){
+    u32 bin = i/p->iDivisor;
+    i = i%p->iDivisor;
+    p = p->u.apSub[bin];
+    if (!p) {
+      return;
+    }
+  }
+  if( p->iSize<=BITVEC_NBIT ){
+    p->u.aBitmap[i/BITVEC_SZELEM] &= ~(1 << (i&(BITVEC_SZELEM-1)));
+  }else{
+    unsigned int j;
+    u32 *aiValues = pBuf;
+    memcpy(aiValues, p->u.aHash, sizeof(p->u.aHash));
+    memset(p->u.aHash, 0, sizeof(p->u.aHash));
+    p->nSet = 0;
+    for(j=0; j<BITVEC_NINT; j++){
+      if( aiValues[j] && aiValues[j]!=(i+1) ){
+        u32 h = BITVEC_HASH(aiValues[j]-1);
+        p->nSet++;
+        while( p->u.aHash[h] ){
+          h++;
+          if( h>=BITVEC_NINT ) h = 0;
+        }
+        p->u.aHash[h] = aiValues[j];
+      }
+    }
+  }
+}
+
+/*
+** Destroy a bitmap object.  Reclaim all memory used.
+*/
+SQLITE_PRIVATE void sqlite3BitvecDestroy(Bitvec *p){
+  if( p==0 ) return;
+  if( p->iDivisor ){
+    unsigned int i;
+    for(i=0; i<BITVEC_NPTR; i++){
+      sqlite3BitvecDestroy(p->u.apSub[i]);
+    }
+  }
+  sqlite3_free(p);
+}
+
+/*
+** Return the value of the iSize parameter specified when Bitvec *p
+** was created.
+*/
+SQLITE_PRIVATE u32 sqlite3BitvecSize(Bitvec *p){
+  return p->iSize;
+}
+
+#ifndef SQLITE_OMIT_BUILTIN_TEST
+/*
+** Let V[] be an array of unsigned characters sufficient to hold
+** up to N bits.  Let I be an integer between 0 and N.  0<=I<N.
+** Then the following macros can be used to set, clear, or test
+** individual bits within V.
+*/
+#define SETBIT(V,I)      V[I>>3] |= (1<<(I&7))
+#define CLEARBIT(V,I)    V[I>>3] &= ~(1<<(I&7))
+#define TESTBIT(V,I)     (V[I>>3]&(1<<(I&7)))!=0
+
+/*
+** This routine runs an extensive test of the Bitvec code.
+**
+** The input is an array of integers that acts as a program
+** to test the Bitvec.  The integers are opcodes followed
+** by 0, 1, or 3 operands, depending on the opcode.  Another
+** opcode follows immediately after the last operand.
+**
+** There are 6 opcodes numbered from 0 through 5.  0 is the
+** "halt" opcode and causes the test to end.
+**
+**    0          Halt and return the number of errors
+**    1 N S X    Set N bits beginning with S and incrementing by X
+**    2 N S X    Clear N bits beginning with S and incrementing by X
+**    3 N        Set N randomly chosen bits
+**    4 N        Clear N randomly chosen bits
+**    5 N S X    Set N bits from S increment X in array only, not in bitvec
+**
+** The opcodes 1 through 4 perform set and clear operations are performed
+** on both a Bitvec object and on a linear array of bits obtained from malloc.
+** Opcode 5 works on the linear array only, not on the Bitvec.
+** Opcode 5 is used to deliberately induce a fault in order to
+** confirm that error detection works.
+**
+** At the conclusion of the test the linear array is compared
+** against the Bitvec object.  If there are any differences,
+** an error is returned.  If they are the same, zero is returned.
+**
+** If a memory allocation error occurs, return -1.
+*/
+SQLITE_PRIVATE int sqlite3BitvecBuiltinTest(int sz, int *aOp){
+  Bitvec *pBitvec = 0;
+  unsigned char *pV = 0;
+  int rc = -1;
+  int i, nx, pc, op;
+  void *pTmpSpace;
+
+  /* Allocate the Bitvec to be tested and a linear array of
+  ** bits to act as the reference */
+  pBitvec = sqlite3BitvecCreate( sz );
+  pV = sqlite3_malloc( (sz+7)/8 + 1 );
+  pTmpSpace = sqlite3_malloc(BITVEC_SZ);
+  if( pBitvec==0 || pV==0 || pTmpSpace==0  ) goto bitvec_end;
+  memset(pV, 0, (sz+7)/8 + 1);
+
+  /* NULL pBitvec tests */
+  sqlite3BitvecSet(0, 1);
+  sqlite3BitvecClear(0, 1, pTmpSpace);
+
+  /* Run the program */
+  pc = 0;
+  while( (op = aOp[pc])!=0 ){
+    switch( op ){
+      case 1:
+      case 2:
+      case 5: {
+        nx = 4;
+        i = aOp[pc+2] - 1;
+        aOp[pc+2] += aOp[pc+3];
+        break;
+      }
+      case 3:
+      case 4: 
+      default: {
+        nx = 2;
+        sqlite3_randomness(sizeof(i), &i);
+        break;
+      }
+    }
+    if( (--aOp[pc+1]) > 0 ) nx = 0;
+    pc += nx;
+    i = (i & 0x7fffffff)%sz;
+    if( (op & 1)!=0 ){
+      SETBIT(pV, (i+1));
+      if( op!=5 ){
+        if( sqlite3BitvecSet(pBitvec, i+1) ) goto bitvec_end;
+      }
+    }else{
+      CLEARBIT(pV, (i+1));
+      sqlite3BitvecClear(pBitvec, i+1, pTmpSpace);
+    }
+  }
+
+  /* Test to make sure the linear array exactly matches the
+  ** Bitvec object.  Start with the assumption that they do
+  ** match (rc==0).  Change rc to non-zero if a discrepancy
+  ** is found.
+  */
+  rc = sqlite3BitvecTest(0,0) + sqlite3BitvecTest(pBitvec, sz+1)
+          + sqlite3BitvecTest(pBitvec, 0)
+          + (sqlite3BitvecSize(pBitvec) - sz);
+  for(i=1; i<=sz; i++){
+    if(  (TESTBIT(pV,i))!=sqlite3BitvecTest(pBitvec,i) ){
+      rc = i;
+      break;
+    }
+  }
+
+  /* Free allocated structure */
+bitvec_end:
+  sqlite3_free(pTmpSpace);
+  sqlite3_free(pV);
+  sqlite3BitvecDestroy(pBitvec);
+  return rc;
+}
+#endif /* SQLITE_OMIT_BUILTIN_TEST */
+
+/************** End of bitvec.c **********************************************/
+/************** Begin file pcache.c ******************************************/
+/*
+** 2008 August 05
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file implements that page cache.
+*/
+
+/*
+** A complete page cache is an instance of this structure.
+*/
+struct PCache {
+  PgHdr *pDirty, *pDirtyTail;         /* List of dirty pages in LRU order */
+  PgHdr *pSynced;                     /* Last synced page in dirty page list */
+  int nRef;                           /* Number of referenced pages */
+  int nMax;                           /* Configured cache size */
+  int szPage;                         /* Size of every page in this cache */
+  int szExtra;                        /* Size of extra space for each page */
+  int bPurgeable;                     /* True if pages are on backing store */
+  int (*xStress)(void*,PgHdr*);       /* Call to try make a page clean */
+  void *pStress;                      /* Argument to xStress */
+  sqlite3_pcache *pCache;             /* Pluggable cache module */
+  PgHdr *pPage1;                      /* Reference to page 1 */
+};
+
+/*
+** Some of the assert() macros in this code are too expensive to run
+** even during normal debugging.  Use them only rarely on long-running
+** tests.  Enable the expensive asserts using the
+** -DSQLITE_ENABLE_EXPENSIVE_ASSERT=1 compile-time option.
+*/
+#ifdef SQLITE_ENABLE_EXPENSIVE_ASSERT
+# define expensive_assert(X)  assert(X)
+#else
+# define expensive_assert(X)
+#endif
+
+/********************************** Linked List Management ********************/
+
+#if !defined(NDEBUG) && defined(SQLITE_ENABLE_EXPENSIVE_ASSERT)
+/*
+** Check that the pCache->pSynced variable is set correctly. If it
+** is not, either fail an assert or return zero. Otherwise, return
+** non-zero. This is only used in debugging builds, as follows:
+**
+**   expensive_assert( pcacheCheckSynced(pCache) );
+*/
+static int pcacheCheckSynced(PCache *pCache){
+  PgHdr *p;
+  for(p=pCache->pDirtyTail; p!=pCache->pSynced; p=p->pDirtyPrev){
+    assert( p->nRef || (p->flags&PGHDR_NEED_SYNC) );
+  }
+  return (p==0 || p->nRef || (p->flags&PGHDR_NEED_SYNC)==0);
+}
+#endif /* !NDEBUG && SQLITE_ENABLE_EXPENSIVE_ASSERT */
+
+/*
+** Remove page pPage from the list of dirty pages.
+*/
+static void pcacheRemoveFromDirtyList(PgHdr *pPage){
+  PCache *p = pPage->pCache;
+
+  assert( pPage->pDirtyNext || pPage==p->pDirtyTail );
+  assert( pPage->pDirtyPrev || pPage==p->pDirty );
+
+  /* Update the PCache1.pSynced variable if necessary. */
+  if( p->pSynced==pPage ){
+    PgHdr *pSynced = pPage->pDirtyPrev;
+    while( pSynced && (pSynced->flags&PGHDR_NEED_SYNC) ){
+      pSynced = pSynced->pDirtyPrev;
+    }
+    p->pSynced = pSynced;
+  }
+
+  if( pPage->pDirtyNext ){
+    pPage->pDirtyNext->pDirtyPrev = pPage->pDirtyPrev;
+  }else{
+    assert( pPage==p->pDirtyTail );
+    p->pDirtyTail = pPage->pDirtyPrev;
+  }
+  if( pPage->pDirtyPrev ){
+    pPage->pDirtyPrev->pDirtyNext = pPage->pDirtyNext;
+  }else{
+    assert( pPage==p->pDirty );
+    p->pDirty = pPage->pDirtyNext;
+  }
+  pPage->pDirtyNext = 0;
+  pPage->pDirtyPrev = 0;
+
+  expensive_assert( pcacheCheckSynced(p) );
+}
+
+/*
+** Add page pPage to the head of the dirty list (PCache1.pDirty is set to
+** pPage).
+*/
+static void pcacheAddToDirtyList(PgHdr *pPage){
+  PCache *p = pPage->pCache;
+
+  assert( pPage->pDirtyNext==0 && pPage->pDirtyPrev==0 && p->pDirty!=pPage );
+
+  pPage->pDirtyNext = p->pDirty;
+  if( pPage->pDirtyNext ){
+    assert( pPage->pDirtyNext->pDirtyPrev==0 );
+    pPage->pDirtyNext->pDirtyPrev = pPage;
+  }
+  p->pDirty = pPage;
+  if( !p->pDirtyTail ){
+    p->pDirtyTail = pPage;
+  }
+  if( !p->pSynced && 0==(pPage->flags&PGHDR_NEED_SYNC) ){
+    p->pSynced = pPage;
+  }
+  expensive_assert( pcacheCheckSynced(p) );
+}
+
+/*
+** Wrapper around the pluggable caches xUnpin method. If the cache is
+** being used for an in-memory database, this function is a no-op.
+*/
+static void pcacheUnpin(PgHdr *p){
+  PCache *pCache = p->pCache;
+  if( pCache->bPurgeable ){
+    if( p->pgno==1 ){
+      pCache->pPage1 = 0;
+    }
+    sqlite3GlobalConfig.pcache.xUnpin(pCache->pCache, p, 0);
+  }
+}
+
+/*************************************************** General Interfaces ******
+**
+** Initialize and shutdown the page cache subsystem. Neither of these 
+** functions are threadsafe.
+*/
+SQLITE_PRIVATE int sqlite3PcacheInitialize(void){
+  if( sqlite3GlobalConfig.pcache.xInit==0 ){
+    /* IMPLEMENTATION-OF: R-26801-64137 If the xInit() method is NULL, then the
+    ** built-in default page cache is used instead of the application defined
+    ** page cache. */
+    sqlite3PCacheSetDefault();
+  }
+  return sqlite3GlobalConfig.pcache.xInit(sqlite3GlobalConfig.pcache.pArg);
+}
+SQLITE_PRIVATE void sqlite3PcacheShutdown(void){
+  if( sqlite3GlobalConfig.pcache.xShutdown ){
+    /* IMPLEMENTATION-OF: R-26000-56589 The xShutdown() method may be NULL. */
+    sqlite3GlobalConfig.pcache.xShutdown(sqlite3GlobalConfig.pcache.pArg);
+  }
+}
+
+/*
+** Return the size in bytes of a PCache object.
+*/
+SQLITE_PRIVATE int sqlite3PcacheSize(void){ return sizeof(PCache); }
+
+/*
+** Create a new PCache object. Storage space to hold the object
+** has already been allocated and is passed in as the p pointer. 
+** The caller discovers how much space needs to be allocated by 
+** calling sqlite3PcacheSize().
+*/
+SQLITE_PRIVATE void sqlite3PcacheOpen(
+  int szPage,                  /* Size of every page */
+  int szExtra,                 /* Extra space associated with each page */
+  int bPurgeable,              /* True if pages are on backing store */
+  int (*xStress)(void*,PgHdr*),/* Call to try to make pages clean */
+  void *pStress,               /* Argument to xStress */
+  PCache *p                    /* Preallocated space for the PCache */
+){
+  memset(p, 0, sizeof(PCache));
+  p->szPage = szPage;
+  p->szExtra = szExtra;
+  p->bPurgeable = bPurgeable;
+  p->xStress = xStress;
+  p->pStress = pStress;
+  p->nMax = 100;
+}
+
+/*
+** Change the page size for PCache object. The caller must ensure that there
+** are no outstanding page references when this function is called.
+*/
+SQLITE_PRIVATE void sqlite3PcacheSetPageSize(PCache *pCache, int szPage){
+  assert( pCache->nRef==0 && pCache->pDirty==0 );
+  if( pCache->pCache ){
+    sqlite3GlobalConfig.pcache.xDestroy(pCache->pCache);
+    pCache->pCache = 0;
+    pCache->pPage1 = 0;
+  }
+  pCache->szPage = szPage;
+}
+
+/*
+** Try to obtain a page from the cache.
+*/
+SQLITE_PRIVATE int sqlite3PcacheFetch(
+  PCache *pCache,       /* Obtain the page from this cache */
+  Pgno pgno,            /* Page number to obtain */
+  int createFlag,       /* If true, create page if it does not exist already */
+  PgHdr **ppPage        /* Write the page here */
+){
+  PgHdr *pPage = 0;
+  int eCreate;
+
+  assert( pCache!=0 );
+  assert( createFlag==1 || createFlag==0 );
+  assert( pgno>0 );
+
+  /* If the pluggable cache (sqlite3_pcache*) has not been allocated,
+  ** allocate it now.
+  */
+  if( !pCache->pCache && createFlag ){
+    sqlite3_pcache *p;
+    int nByte;
+    nByte = pCache->szPage + pCache->szExtra + sizeof(PgHdr);
+    p = sqlite3GlobalConfig.pcache.xCreate(nByte, pCache->bPurgeable);
+    if( !p ){
+      return SQLITE_NOMEM;
+    }
+    sqlite3GlobalConfig.pcache.xCachesize(p, pCache->nMax);
+    pCache->pCache = p;
+  }
+
+  eCreate = createFlag * (1 + (!pCache->bPurgeable || !pCache->pDirty));
+  if( pCache->pCache ){
+    pPage = sqlite3GlobalConfig.pcache.xFetch(pCache->pCache, pgno, eCreate);
+  }
+
+  if( !pPage && eCreate==1 ){
+    PgHdr *pPg;
+
+    /* Find a dirty page to write-out and recycle. First try to find a 
+    ** page that does not require a journal-sync (one with PGHDR_NEED_SYNC
+    ** cleared), but if that is not possible settle for any other 
+    ** unreferenced dirty page.
+    */
+    expensive_assert( pcacheCheckSynced(pCache) );
+    for(pPg=pCache->pSynced; 
+        pPg && (pPg->nRef || (pPg->flags&PGHDR_NEED_SYNC)); 
+        pPg=pPg->pDirtyPrev
+    );
+    pCache->pSynced = pPg;
+    if( !pPg ){
+      for(pPg=pCache->pDirtyTail; pPg && pPg->nRef; pPg=pPg->pDirtyPrev);
+    }
+    if( pPg ){
+      int rc;
+      rc = pCache->xStress(pCache->pStress, pPg);
+      if( rc!=SQLITE_OK && rc!=SQLITE_BUSY ){
+        return rc;
+      }
+    }
+
+    pPage = sqlite3GlobalConfig.pcache.xFetch(pCache->pCache, pgno, 2);
+  }
+
+  if( pPage ){
+    if( !pPage->pData ){
+      memset(pPage, 0, sizeof(PgHdr));
+      pPage->pData = (void *)&pPage[1];
+      pPage->pExtra = (void*)&((char *)pPage->pData)[pCache->szPage];
+      memset(pPage->pExtra, 0, pCache->szExtra);
+      pPage->pCache = pCache;
+      pPage->pgno = pgno;
+    }
+    assert( pPage->pCache==pCache );
+    assert( pPage->pgno==pgno );
+    assert( pPage->pData==(void *)&pPage[1] );
+    assert( pPage->pExtra==(void *)&((char *)&pPage[1])[pCache->szPage] );
+
+    if( 0==pPage->nRef ){
+      pCache->nRef++;
+    }
+    pPage->nRef++;
+    if( pgno==1 ){
+      pCache->pPage1 = pPage;
+    }
+  }
+  *ppPage = pPage;
+  return (pPage==0 && eCreate) ? SQLITE_NOMEM : SQLITE_OK;
+}
+
+/*
+** Decrement the reference count on a page. If the page is clean and the
+** reference count drops to 0, then it is made elible for recycling.
+*/
+SQLITE_PRIVATE void sqlite3PcacheRelease(PgHdr *p){
+  assert( p->nRef>0 );
+  p->nRef--;
+  if( p->nRef==0 ){
+    PCache *pCache = p->pCache;
+    pCache->nRef--;
+    if( (p->flags&PGHDR_DIRTY)==0 ){
+      pcacheUnpin(p);
+    }else{
+      /* Move the page to the head of the dirty list. */
+      pcacheRemoveFromDirtyList(p);
+      pcacheAddToDirtyList(p);
+    }
+  }
+}
+
+/*
+** Increase the reference count of a supplied page by 1.
+*/
+SQLITE_PRIVATE void sqlite3PcacheRef(PgHdr *p){
+  assert(p->nRef>0);
+  p->nRef++;
+}
+
+/*
+** Drop a page from the cache. There must be exactly one reference to the
+** page. This function deletes that reference, so after it returns the
+** page pointed to by p is invalid.
+*/
+SQLITE_PRIVATE void sqlite3PcacheDrop(PgHdr *p){
+  PCache *pCache;
+  assert( p->nRef==1 );
+  if( p->flags&PGHDR_DIRTY ){
+    pcacheRemoveFromDirtyList(p);
+  }
+  pCache = p->pCache;
+  pCache->nRef--;
+  if( p->pgno==1 ){
+    pCache->pPage1 = 0;
+  }
+  sqlite3GlobalConfig.pcache.xUnpin(pCache->pCache, p, 1);
+}
+
+/*
+** Make sure the page is marked as dirty. If it isn't dirty already,
+** make it so.
+*/
+SQLITE_PRIVATE void sqlite3PcacheMakeDirty(PgHdr *p){
+  p->flags &= ~PGHDR_DONT_WRITE;
+  assert( p->nRef>0 );
+  if( 0==(p->flags & PGHDR_DIRTY) ){
+    p->flags |= PGHDR_DIRTY;
+    pcacheAddToDirtyList( p);
+  }
+}
+
+/*
+** Make sure the page is marked as clean. If it isn't clean already,
+** make it so.
+*/
+SQLITE_PRIVATE void sqlite3PcacheMakeClean(PgHdr *p){
+  if( (p->flags & PGHDR_DIRTY) ){
+    pcacheRemoveFromDirtyList(p);
+    p->flags &= ~(PGHDR_DIRTY|PGHDR_NEED_SYNC);
+    if( p->nRef==0 ){
+      pcacheUnpin(p);
+    }
+  }
+}
+
+/*
+** Make every page in the cache clean.
+*/
+SQLITE_PRIVATE void sqlite3PcacheCleanAll(PCache *pCache){
+  PgHdr *p;
+  while( (p = pCache->pDirty)!=0 ){
+    sqlite3PcacheMakeClean(p);
+  }
+}
+
+/*
+** Clear the PGHDR_NEED_SYNC flag from all dirty pages.
+*/
+SQLITE_PRIVATE void sqlite3PcacheClearSyncFlags(PCache *pCache){
+  PgHdr *p;
+  for(p=pCache->pDirty; p; p=p->pDirtyNext){
+    p->flags &= ~PGHDR_NEED_SYNC;
+  }
+  pCache->pSynced = pCache->pDirtyTail;
+}
+
+/*
+** Change the page number of page p to newPgno. 
+*/
+SQLITE_PRIVATE void sqlite3PcacheMove(PgHdr *p, Pgno newPgno){
+  PCache *pCache = p->pCache;
+  assert( p->nRef>0 );
+  assert( newPgno>0 );
+  sqlite3GlobalConfig.pcache.xRekey(pCache->pCache, p, p->pgno, newPgno);
+  p->pgno = newPgno;
+  if( (p->flags&PGHDR_DIRTY) && (p->flags&PGHDR_NEED_SYNC) ){
+    pcacheRemoveFromDirtyList(p);
+    pcacheAddToDirtyList(p);
+  }
+}
+
+/*
+** Drop every cache entry whose page number is greater than "pgno". The
+** caller must ensure that there are no outstanding references to any pages
+** other than page 1 with a page number greater than pgno.
+**
+** If there is a reference to page 1 and the pgno parameter passed to this
+** function is 0, then the data area associated with page 1 is zeroed, but
+** the page object is not dropped.
+*/
+SQLITE_PRIVATE void sqlite3PcacheTruncate(PCache *pCache, Pgno pgno){
+  if( pCache->pCache ){
+    PgHdr *p;
+    PgHdr *pNext;
+    for(p=pCache->pDirty; p; p=pNext){
+      pNext = p->pDirtyNext;
+      /* This routine never gets call with a positive pgno except right
+      ** after sqlite3PcacheCleanAll().  So if there are dirty pages,
+      ** it must be that pgno==0.
+      */
+      assert( p->pgno>0 );
+      if( ALWAYS(p->pgno>pgno) ){
+        assert( p->flags&PGHDR_DIRTY );
+        sqlite3PcacheMakeClean(p);
+      }
+    }
+    if( pgno==0 && pCache->pPage1 ){
+      memset(pCache->pPage1->pData, 0, pCache->szPage);
+      pgno = 1;
+    }
+    sqlite3GlobalConfig.pcache.xTruncate(pCache->pCache, pgno+1);
+  }
+}
+
+/*
+** Close a cache.
+*/
+SQLITE_PRIVATE void sqlite3PcacheClose(PCache *pCache){
+  if( pCache->pCache ){
+    sqlite3GlobalConfig.pcache.xDestroy(pCache->pCache);
+  }
+}
+
+/* 
+** Discard the contents of the cache.
+*/
+SQLITE_PRIVATE void sqlite3PcacheClear(PCache *pCache){
+  sqlite3PcacheTruncate(pCache, 0);
+}
+
+/*
+** Merge two lists of pages connected by pDirty and in pgno order.
+** Do not both fixing the pDirtyPrev pointers.
+*/
+static PgHdr *pcacheMergeDirtyList(PgHdr *pA, PgHdr *pB){
+  PgHdr result, *pTail;
+  pTail = &result;
+  while( pA && pB ){
+    if( pA->pgno<pB->pgno ){
+      pTail->pDirty = pA;
+      pTail = pA;
+      pA = pA->pDirty;
+    }else{
+      pTail->pDirty = pB;
+      pTail = pB;
+      pB = pB->pDirty;
+    }
+  }
+  if( pA ){
+    pTail->pDirty = pA;
+  }else if( pB ){
+    pTail->pDirty = pB;
+  }else{
+    pTail->pDirty = 0;
+  }
+  return result.pDirty;
+}
+
+/*
+** Sort the list of pages in accending order by pgno.  Pages are
+** connected by pDirty pointers.  The pDirtyPrev pointers are
+** corrupted by this sort.
+**
+** Since there cannot be more than 2^31 distinct pages in a database,
+** there cannot be more than 31 buckets required by the merge sorter.
+** One extra bucket is added to catch overflow in case something
+** ever changes to make the previous sentence incorrect.
+*/
+#define N_SORT_BUCKET  32
+static PgHdr *pcacheSortDirtyList(PgHdr *pIn){
+  PgHdr *a[N_SORT_BUCKET], *p;
+  int i;
+  memset(a, 0, sizeof(a));
+  while( pIn ){
+    p = pIn;
+    pIn = p->pDirty;
+    p->pDirty = 0;
+    for(i=0; ALWAYS(i<N_SORT_BUCKET-1); i++){
+      if( a[i]==0 ){
+        a[i] = p;
+        break;
+      }else{
+        p = pcacheMergeDirtyList(a[i], p);
+        a[i] = 0;
+      }
+    }
+    if( NEVER(i==N_SORT_BUCKET-1) ){
+      /* To get here, there need to be 2^(N_SORT_BUCKET) elements in
+      ** the input list.  But that is impossible.
+      */
+      a[i] = pcacheMergeDirtyList(a[i], p);
+    }
+  }
+  p = a[0];
+  for(i=1; i<N_SORT_BUCKET; i++){
+    p = pcacheMergeDirtyList(p, a[i]);
+  }
+  return p;
+}
+
+/*
+** Return a list of all dirty pages in the cache, sorted by page number.
+*/
+SQLITE_PRIVATE PgHdr *sqlite3PcacheDirtyList(PCache *pCache){
+  PgHdr *p;
+  for(p=pCache->pDirty; p; p=p->pDirtyNext){
+    p->pDirty = p->pDirtyNext;
+  }
+  return pcacheSortDirtyList(pCache->pDirty);
+}
+
+/* 
+** Return the total number of referenced pages held by the cache.
+*/
+SQLITE_PRIVATE int sqlite3PcacheRefCount(PCache *pCache){
+  return pCache->nRef;
+}
+
+/*
+** Return the number of references to the page supplied as an argument.
+*/
+SQLITE_PRIVATE int sqlite3PcachePageRefcount(PgHdr *p){
+  return p->nRef;
+}
+
+/* 
+** Return the total number of pages in the cache.
+*/
+SQLITE_PRIVATE int sqlite3PcachePagecount(PCache *pCache){
+  int nPage = 0;
+  if( pCache->pCache ){
+    nPage = sqlite3GlobalConfig.pcache.xPagecount(pCache->pCache);
+  }
+  return nPage;
+}
+
+#ifdef SQLITE_TEST
+/*
+** Get the suggested cache-size value.
+*/
+SQLITE_PRIVATE int sqlite3PcacheGetCachesize(PCache *pCache){
+  return pCache->nMax;
+}
+#endif
+
+/*
+** Set the suggested cache-size value.
+*/
+SQLITE_PRIVATE void sqlite3PcacheSetCachesize(PCache *pCache, int mxPage){
+  pCache->nMax = mxPage;
+  if( pCache->pCache ){
+    sqlite3GlobalConfig.pcache.xCachesize(pCache->pCache, mxPage);
+  }
+}
+
+#if defined(SQLITE_CHECK_PAGES) || defined(SQLITE_DEBUG)
+/*
+** For all dirty pages currently in the cache, invoke the specified
+** callback. This is only used if the SQLITE_CHECK_PAGES macro is
+** defined.
+*/
+SQLITE_PRIVATE void sqlite3PcacheIterateDirty(PCache *pCache, void (*xIter)(PgHdr *)){
+  PgHdr *pDirty;
+  for(pDirty=pCache->pDirty; pDirty; pDirty=pDirty->pDirtyNext){
+    xIter(pDirty);
+  }
+}
+#endif
+
+/************** End of pcache.c **********************************************/
+/************** Begin file pcache1.c *****************************************/
+/*
+** 2008 November 05
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file implements the default page cache implementation (the
+** sqlite3_pcache interface). It also contains part of the implementation
+** of the SQLITE_CONFIG_PAGECACHE and sqlite3_release_memory() features.
+** If the default page cache implementation is overriden, then neither of
+** these two features are available.
+*/
+
+
+typedef struct PCache1 PCache1;
+typedef struct PgHdr1 PgHdr1;
+typedef struct PgFreeslot PgFreeslot;
+typedef struct PGroup PGroup;
+
+/* Each page cache (or PCache) belongs to a PGroup.  A PGroup is a set 
+** of one or more PCaches that are able to recycle each others unpinned
+** pages when they are under memory pressure.  A PGroup is an instance of
+** the following object.
+**
+** This page cache implementation works in one of two modes:
+**
+**   (1)  Every PCache is the sole member of its own PGroup.  There is
+**        one PGroup per PCache.
+**
+**   (2)  There is a single global PGroup that all PCaches are a member
+**        of.
+**
+** Mode 1 uses more memory (since PCache instances are not able to rob
+** unused pages from other PCaches) but it also operates without a mutex,
+** and is therefore often faster.  Mode 2 requires a mutex in order to be
+** threadsafe, but is able recycle pages more efficient.
+**
+** For mode (1), PGroup.mutex is NULL.  For mode (2) there is only a single
+** PGroup which is the pcache1.grp global variable and its mutex is
+** SQLITE_MUTEX_STATIC_LRU.
+*/
+struct PGroup {
+  sqlite3_mutex *mutex;          /* MUTEX_STATIC_LRU or NULL */
+  int nMaxPage;                  /* Sum of nMax for purgeable caches */
+  int nMinPage;                  /* Sum of nMin for purgeable caches */
+  int mxPinned;                  /* nMaxpage + 10 - nMinPage */
+  int nCurrentPage;              /* Number of purgeable pages allocated */
+  PgHdr1 *pLruHead, *pLruTail;   /* LRU list of unpinned pages */
+};
+
+/* Each page cache is an instance of the following object.  Every
+** open database file (including each in-memory database and each
+** temporary or transient database) has a single page cache which
+** is an instance of this object.
+**
+** Pointers to structures of this type are cast and returned as 
+** opaque sqlite3_pcache* handles.
+*/
+struct PCache1 {
+  /* Cache configuration parameters. Page size (szPage) and the purgeable
+  ** flag (bPurgeable) are set when the cache is created. nMax may be 
+  ** modified at any time by a call to the pcache1CacheSize() method.
+  ** The PGroup mutex must be held when accessing nMax.
+  */
+  PGroup *pGroup;                     /* PGroup this cache belongs to */
+  int szPage;                         /* Size of allocated pages in bytes */
+  int bPurgeable;                     /* True if cache is purgeable */
+  unsigned int nMin;                  /* Minimum number of pages reserved */
+  unsigned int nMax;                  /* Configured "cache_size" value */
+  unsigned int n90pct;                /* nMax*9/10 */
+
+  /* Hash table of all pages. The following variables may only be accessed
+  ** when the accessor is holding the PGroup mutex.
+  */
+  unsigned int nRecyclable;           /* Number of pages in the LRU list */
+  unsigned int nPage;                 /* Total number of pages in apHash */
+  unsigned int nHash;                 /* Number of slots in apHash[] */
+  PgHdr1 **apHash;                    /* Hash table for fast lookup by key */
+
+  unsigned int iMaxKey;               /* Largest key seen since xTruncate() */
+};
+
+/*
+** Each cache entry is represented by an instance of the following 
+** structure. A buffer of PgHdr1.pCache->szPage bytes is allocated 
+** directly before this structure in memory (see the PGHDR1_TO_PAGE() 
+** macro below).
+*/
+struct PgHdr1 {
+  unsigned int iKey;             /* Key value (page number) */
+  PgHdr1 *pNext;                 /* Next in hash table chain */
+  PCache1 *pCache;               /* Cache that currently owns this page */
+  PgHdr1 *pLruNext;              /* Next in LRU list of unpinned pages */
+  PgHdr1 *pLruPrev;              /* Previous in LRU list of unpinned pages */
+};
+
+/*
+** Free slots in the allocator used to divide up the buffer provided using
+** the SQLITE_CONFIG_PAGECACHE mechanism.
+*/
+struct PgFreeslot {
+  PgFreeslot *pNext;  /* Next free slot */
+};
+
+/*
+** Global data used by this cache.
+*/
+static SQLITE_WSD struct PCacheGlobal {
+  PGroup grp;                    /* The global PGroup for mode (2) */
+
+  /* Variables related to SQLITE_CONFIG_PAGECACHE settings.  The
+  ** szSlot, nSlot, pStart, pEnd, nReserve, and isInit values are all
+  ** fixed at sqlite3_initialize() time and do not require mutex protection.
+  ** The nFreeSlot and pFree values do require mutex protection.
+  */
+  int isInit;                    /* True if initialized */
+  int szSlot;                    /* Size of each free slot */
+  int nSlot;                     /* The number of pcache slots */
+  int nReserve;                  /* Try to keep nFreeSlot above this */
+  void *pStart, *pEnd;           /* Bounds of pagecache malloc range */
+  /* Above requires no mutex.  Use mutex below for variable that follow. */
+  sqlite3_mutex *mutex;          /* Mutex for accessing the following: */
+  int nFreeSlot;                 /* Number of unused pcache slots */
+  PgFreeslot *pFree;             /* Free page blocks */
+  /* The following value requires a mutex to change.  We skip the mutex on
+  ** reading because (1) most platforms read a 32-bit integer atomically and
+  ** (2) even if an incorrect value is read, no great harm is done since this
+  ** is really just an optimization. */
+  int bUnderPressure;            /* True if low on PAGECACHE memory */
+} pcache1_g;
+
+/*
+** All code in this file should access the global structure above via the
+** alias "pcache1". This ensures that the WSD emulation is used when
+** compiling for systems that do not support real WSD.
+*/
+#define pcache1 (GLOBAL(struct PCacheGlobal, pcache1_g))
+
+/*
+** When a PgHdr1 structure is allocated, the associated PCache1.szPage
+** bytes of data are located directly before it in memory (i.e. the total
+** size of the allocation is sizeof(PgHdr1)+PCache1.szPage byte). The
+** PGHDR1_TO_PAGE() macro takes a pointer to a PgHdr1 structure as
+** an argument and returns a pointer to the associated block of szPage
+** bytes. The PAGE_TO_PGHDR1() macro does the opposite: its argument is
+** a pointer to a block of szPage bytes of data and the return value is
+** a pointer to the associated PgHdr1 structure.
+**
+**   assert( PGHDR1_TO_PAGE(PAGE_TO_PGHDR1(pCache, X))==X );
+*/
+#define PGHDR1_TO_PAGE(p)    (void*)(((char*)p) - p->pCache->szPage)
+#define PAGE_TO_PGHDR1(c, p) (PgHdr1*)(((char*)p) + c->szPage)
+
+/*
+** Macros to enter and leave the PCache LRU mutex.
+*/
+#define pcache1EnterMutex(X) sqlite3_mutex_enter((X)->mutex)
+#define pcache1LeaveMutex(X) sqlite3_mutex_leave((X)->mutex)
+
+/******************************************************************************/
+/******** Page Allocation/SQLITE_CONFIG_PCACHE Related Functions **************/
+
+/*
+** This function is called during initialization if a static buffer is 
+** supplied to use for the page-cache by passing the SQLITE_CONFIG_PAGECACHE
+** verb to sqlite3_config(). Parameter pBuf points to an allocation large
+** enough to contain 'n' buffers of 'sz' bytes each.
+**
+** This routine is called from sqlite3_initialize() and so it is guaranteed
+** to be serialized already.  There is no need for further mutexing.
+*/
+SQLITE_PRIVATE void sqlite3PCacheBufferSetup(void *pBuf, int sz, int n){
+  if( pcache1.isInit ){
+    PgFreeslot *p;
+    sz = ROUNDDOWN8(sz);
+    pcache1.szSlot = sz;
+    pcache1.nSlot = pcache1.nFreeSlot = n;
+    pcache1.nReserve = n>90 ? 10 : (n/10 + 1);
+    pcache1.pStart = pBuf;
+    pcache1.pFree = 0;
+    pcache1.bUnderPressure = 0;
+    while( n-- ){
+      p = (PgFreeslot*)pBuf;
+      p->pNext = pcache1.pFree;
+      pcache1.pFree = p;
+      pBuf = (void*)&((char*)pBuf)[sz];
+    }
+    pcache1.pEnd = pBuf;
+  }
+}
+
+/*
+** Malloc function used within this file to allocate space from the buffer
+** configured using sqlite3_config(SQLITE_CONFIG_PAGECACHE) option. If no 
+** such buffer exists or there is no space left in it, this function falls 
+** back to sqlite3Malloc().
+**
+** Multiple threads can run this routine at the same time.  Global variables
+** in pcache1 need to be protected via mutex.
+*/
+static void *pcache1Alloc(int nByte){
+  void *p = 0;
+  assert( sqlite3_mutex_notheld(pcache1.grp.mutex) );
+  sqlite3StatusSet(SQLITE_STATUS_PAGECACHE_SIZE, nByte);
+  if( nByte<=pcache1.szSlot ){
+    sqlite3_mutex_enter(pcache1.mutex);
+    p = (PgHdr1 *)pcache1.pFree;
+    if( p ){
+      pcache1.pFree = pcache1.pFree->pNext;
+      pcache1.nFreeSlot--;
+      pcache1.bUnderPressure = pcache1.nFreeSlot<pcache1.nReserve;
+      assert( pcache1.nFreeSlot>=0 );
+      sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_USED, 1);
+    }
+    sqlite3_mutex_leave(pcache1.mutex);
+  }
+  if( p==0 ){
+    /* Memory is not available in the SQLITE_CONFIG_PAGECACHE pool.  Get
+    ** it from sqlite3Malloc instead.
+    */
+    p = sqlite3Malloc(nByte);
+    if( p ){
+      int sz = sqlite3MallocSize(p);
+      sqlite3_mutex_enter(pcache1.mutex);
+      sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_OVERFLOW, sz);
+      sqlite3_mutex_leave(pcache1.mutex);
+    }
+    sqlite3MemdebugSetType(p, MEMTYPE_PCACHE);
+  }
+  return p;
+}
+
+/*
+** Free an allocated buffer obtained from pcache1Alloc().
+*/
+static void pcache1Free(void *p){
+  if( p==0 ) return;
+  if( p>=pcache1.pStart && p<pcache1.pEnd ){
+    PgFreeslot *pSlot;
+    sqlite3_mutex_enter(pcache1.mutex);
+    sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_USED, -1);
+    pSlot = (PgFreeslot*)p;
+    pSlot->pNext = pcache1.pFree;
+    pcache1.pFree = pSlot;
+    pcache1.nFreeSlot++;
+    pcache1.bUnderPressure = pcache1.nFreeSlot<pcache1.nReserve;
+    assert( pcache1.nFreeSlot<=pcache1.nSlot );
+    sqlite3_mutex_leave(pcache1.mutex);
+  }else{
+    int iSize;
+    assert( sqlite3MemdebugHasType(p, MEMTYPE_PCACHE) );
+    sqlite3MemdebugSetType(p, MEMTYPE_HEAP);
+    iSize = sqlite3MallocSize(p);
+    sqlite3_mutex_enter(pcache1.mutex);
+    sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_OVERFLOW, -iSize);
+    sqlite3_mutex_leave(pcache1.mutex);
+    sqlite3_free(p);
+  }
+}
+
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+/*
+** Return the size of a pcache allocation
+*/
+static int pcache1MemSize(void *p){
+  if( p>=pcache1.pStart && p<pcache1.pEnd ){
+    return pcache1.szSlot;
+  }else{
+    int iSize;
+    assert( sqlite3MemdebugHasType(p, MEMTYPE_PCACHE) );
+    sqlite3MemdebugSetType(p, MEMTYPE_HEAP);
+    iSize = sqlite3MallocSize(p);
+    sqlite3MemdebugSetType(p, MEMTYPE_PCACHE);
+    return iSize;
+  }
+}
+#endif /* SQLITE_ENABLE_MEMORY_MANAGEMENT */
+
+/*
+** Allocate a new page object initially associated with cache pCache.
+*/
+static PgHdr1 *pcache1AllocPage(PCache1 *pCache){
+  int nByte = sizeof(PgHdr1) + pCache->szPage;
+  void *pPg = pcache1Alloc(nByte);
+  PgHdr1 *p;
+  if( pPg ){
+    p = PAGE_TO_PGHDR1(pCache, pPg);
+    if( pCache->bPurgeable ){
+      pCache->pGroup->nCurrentPage++;
+    }
+  }else{
+    p = 0;
+  }
+  return p;
+}
+
+/*
+** Free a page object allocated by pcache1AllocPage().
+**
+** The pointer is allowed to be NULL, which is prudent.  But it turns out
+** that the current implementation happens to never call this routine
+** with a NULL pointer, so we mark the NULL test with ALWAYS().
+*/
+static void pcache1FreePage(PgHdr1 *p){
+  if( ALWAYS(p) ){
+    PCache1 *pCache = p->pCache;
+    if( pCache->bPurgeable ){
+      pCache->pGroup->nCurrentPage--;
+    }
+    pcache1Free(PGHDR1_TO_PAGE(p));
+  }
+}
+
+/*
+** Malloc function used by SQLite to obtain space from the buffer configured
+** using sqlite3_config(SQLITE_CONFIG_PAGECACHE) option. If no such buffer
+** exists, this function falls back to sqlite3Malloc().
+*/
+SQLITE_PRIVATE void *sqlite3PageMalloc(int sz){
+  return pcache1Alloc(sz);
+}
+
+/*
+** Free an allocated buffer obtained from sqlite3PageMalloc().
+*/
+SQLITE_PRIVATE void sqlite3PageFree(void *p){
+  pcache1Free(p);
+}
+
+
+/*
+** Return true if it desirable to avoid allocating a new page cache
+** entry.
+**
+** If memory was allocated specifically to the page cache using
+** SQLITE_CONFIG_PAGECACHE but that memory has all been used, then
+** it is desirable to avoid allocating a new page cache entry because
+** presumably SQLITE_CONFIG_PAGECACHE was suppose to be sufficient
+** for all page cache needs and we should not need to spill the
+** allocation onto the heap.
+**
+** Or, the heap is used for all page cache memory put the heap is
+** under memory pressure, then again it is desirable to avoid
+** allocating a new page cache entry in order to avoid stressing
+** the heap even further.
+*/
+static int pcache1UnderMemoryPressure(PCache1 *pCache){
+  if( pcache1.nSlot && pCache->szPage<=pcache1.szSlot ){
+    return pcache1.bUnderPressure;
+  }else{
+    return sqlite3HeapNearlyFull();
+  }
+}
+
+/******************************************************************************/
+/******** General Implementation Functions ************************************/
+
+/*
+** This function is used to resize the hash table used by the cache passed
+** as the first argument.
+**
+** The PCache mutex must be held when this function is called.
+*/
+static int pcache1ResizeHash(PCache1 *p){
+  PgHdr1 **apNew;
+  unsigned int nNew;
+  unsigned int i;
+
+  assert( sqlite3_mutex_held(p->pGroup->mutex) );
+
+  nNew = p->nHash*2;
+  if( nNew<256 ){
+    nNew = 256;
+  }
+
+  pcache1LeaveMutex(p->pGroup);
+  if( p->nHash ){ sqlite3BeginBenignMalloc(); }
+  apNew = (PgHdr1 **)sqlite3_malloc(sizeof(PgHdr1 *)*nNew);
+  if( p->nHash ){ sqlite3EndBenignMalloc(); }
+  pcache1EnterMutex(p->pGroup);
+  if( apNew ){
+    memset(apNew, 0, sizeof(PgHdr1 *)*nNew);
+    for(i=0; i<p->nHash; i++){
+      PgHdr1 *pPage;
+      PgHdr1 *pNext = p->apHash[i];
+      while( (pPage = pNext)!=0 ){
+        unsigned int h = pPage->iKey % nNew;
+        pNext = pPage->pNext;
+        pPage->pNext = apNew[h];
+        apNew[h] = pPage;
+      }
+    }
+    sqlite3_free(p->apHash);
+    p->apHash = apNew;
+    p->nHash = nNew;
+  }
+
+  return (p->apHash ? SQLITE_OK : SQLITE_NOMEM);
+}
+
+/*
+** This function is used internally to remove the page pPage from the 
+** PGroup LRU list, if is part of it. If pPage is not part of the PGroup
+** LRU list, then this function is a no-op.
+**
+** The PGroup mutex must be held when this function is called.
+**
+** If pPage is NULL then this routine is a no-op.
+*/
+static void pcache1PinPage(PgHdr1 *pPage){
+  PCache1 *pCache;
+  PGroup *pGroup;
+
+  if( pPage==0 ) return;
+  pCache = pPage->pCache;
+  pGroup = pCache->pGroup;
+  assert( sqlite3_mutex_held(pGroup->mutex) );
+  if( pPage->pLruNext || pPage==pGroup->pLruTail ){
+    if( pPage->pLruPrev ){
+      pPage->pLruPrev->pLruNext = pPage->pLruNext;
+    }
+    if( pPage->pLruNext ){
+      pPage->pLruNext->pLruPrev = pPage->pLruPrev;
+    }
+    if( pGroup->pLruHead==pPage ){
+      pGroup->pLruHead = pPage->pLruNext;
+    }
+    if( pGroup->pLruTail==pPage ){
+      pGroup->pLruTail = pPage->pLruPrev;
+    }
+    pPage->pLruNext = 0;
+    pPage->pLruPrev = 0;
+    pPage->pCache->nRecyclable--;
+  }
+}
+
+
+/*
+** Remove the page supplied as an argument from the hash table 
+** (PCache1.apHash structure) that it is currently stored in.
+**
+** The PGroup mutex must be held when this function is called.
+*/
+static void pcache1RemoveFromHash(PgHdr1 *pPage){
+  unsigned int h;
+  PCache1 *pCache = pPage->pCache;
+  PgHdr1 **pp;
+
+  assert( sqlite3_mutex_held(pCache->pGroup->mutex) );
+  h = pPage->iKey % pCache->nHash;
+  for(pp=&pCache->apHash[h]; (*pp)!=pPage; pp=&(*pp)->pNext);
+  *pp = (*pp)->pNext;
+
+  pCache->nPage--;
+}
+
+/*
+** If there are currently more than nMaxPage pages allocated, try
+** to recycle pages to reduce the number allocated to nMaxPage.
+*/
+static void pcache1EnforceMaxPage(PGroup *pGroup){
+  assert( sqlite3_mutex_held(pGroup->mutex) );
+  while( pGroup->nCurrentPage>pGroup->nMaxPage && pGroup->pLruTail ){
+    PgHdr1 *p = pGroup->pLruTail;
+    assert( p->pCache->pGroup==pGroup );
+    pcache1PinPage(p);
+    pcache1RemoveFromHash(p);
+    pcache1FreePage(p);
+  }
+}
+
+/*
+** Discard all pages from cache pCache with a page number (key value) 
+** greater than or equal to iLimit. Any pinned pages that meet this 
+** criteria are unpinned before they are discarded.
+**
+** The PCache mutex must be held when this function is called.
+*/
+static void pcache1TruncateUnsafe(
+  PCache1 *pCache,             /* The cache to truncate */
+  unsigned int iLimit          /* Drop pages with this pgno or larger */
+){
+  TESTONLY( unsigned int nPage = 0; )  /* To assert pCache->nPage is correct */
+  unsigned int h;
+  assert( sqlite3_mutex_held(pCache->pGroup->mutex) );
+  for(h=0; h<pCache->nHash; h++){
+    PgHdr1 **pp = &pCache->apHash[h]; 
+    PgHdr1 *pPage;
+    while( (pPage = *pp)!=0 ){
+      if( pPage->iKey>=iLimit ){
+        pCache->nPage--;
+        *pp = pPage->pNext;
+        pcache1PinPage(pPage);
+        pcache1FreePage(pPage);
+      }else{
+        pp = &pPage->pNext;
+        TESTONLY( nPage++; )
+      }
+    }
+  }
+  assert( pCache->nPage==nPage );
+}
+
+/******************************************************************************/
+/******** sqlite3_pcache Methods **********************************************/
+
+/*
+** Implementation of the sqlite3_pcache.xInit method.
+*/
+static int pcache1Init(void *NotUsed){
+  UNUSED_PARAMETER(NotUsed);
+  assert( pcache1.isInit==0 );
+  memset(&pcache1, 0, sizeof(pcache1));
+  if( sqlite3GlobalConfig.bCoreMutex ){
+    pcache1.grp.mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_LRU);
+    pcache1.mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_PMEM);
+  }
+  pcache1.grp.mxPinned = 10;
+  pcache1.isInit = 1;
+  return SQLITE_OK;
+}
+
+/*
+** Implementation of the sqlite3_pcache.xShutdown method.
+** Note that the static mutex allocated in xInit does 
+** not need to be freed.
+*/
+static void pcache1Shutdown(void *NotUsed){
+  UNUSED_PARAMETER(NotUsed);
+  assert( pcache1.isInit!=0 );
+  memset(&pcache1, 0, sizeof(pcache1));
+}
+
+/*
+** Implementation of the sqlite3_pcache.xCreate method.
+**
+** Allocate a new cache.
+*/
+static sqlite3_pcache *pcache1Create(int szPage, int bPurgeable){
+  PCache1 *pCache;      /* The newly created page cache */
+  PGroup *pGroup;       /* The group the new page cache will belong to */
+  int sz;               /* Bytes of memory required to allocate the new cache */
+
+  /*
+  ** The seperateCache variable is true if each PCache has its own private
+  ** PGroup.  In other words, separateCache is true for mode (1) where no
+  ** mutexing is required.
+  **
+  **   *  Always use a unified cache (mode-2) if ENABLE_MEMORY_MANAGEMENT
+  **
+  **   *  Always use a unified cache in single-threaded applications
+  **
+  **   *  Otherwise (if multi-threaded and ENABLE_MEMORY_MANAGEMENT is off)
+  **      use separate caches (mode-1)
+  */
+#if defined(SQLITE_ENABLE_MEMORY_MANAGEMENT) || SQLITE_THREADSAFE==0
+  const int separateCache = 0;
+#else
+  int separateCache = sqlite3GlobalConfig.bCoreMutex>0;
+#endif
+
+  sz = sizeof(PCache1) + sizeof(PGroup)*separateCache;
+  pCache = (PCache1 *)sqlite3_malloc(sz);
+  if( pCache ){
+    memset(pCache, 0, sz);
+    if( separateCache ){
+      pGroup = (PGroup*)&pCache[1];
+      pGroup->mxPinned = 10;
+    }else{
+      pGroup = &pcache1_g.grp;
+    }
+    pCache->pGroup = pGroup;
+    pCache->szPage = szPage;
+    pCache->bPurgeable = (bPurgeable ? 1 : 0);
+    if( bPurgeable ){
+      pCache->nMin = 10;
+      pcache1EnterMutex(pGroup);
+      pGroup->nMinPage += pCache->nMin;
+      pGroup->mxPinned = pGroup->nMaxPage + 10 - pGroup->nMinPage;
+      pcache1LeaveMutex(pGroup);
+    }
+  }
+  return (sqlite3_pcache *)pCache;
+}
+
+/*
+** Implementation of the sqlite3_pcache.xCachesize method. 
+**
+** Configure the cache_size limit for a cache.
+*/
+static void pcache1Cachesize(sqlite3_pcache *p, int nMax){
+  PCache1 *pCache = (PCache1 *)p;
+  if( pCache->bPurgeable ){
+    PGroup *pGroup = pCache->pGroup;
+    pcache1EnterMutex(pGroup);
+    pGroup->nMaxPage += (nMax - pCache->nMax);
+    pGroup->mxPinned = pGroup->nMaxPage + 10 - pGroup->nMinPage;
+    pCache->nMax = nMax;
+    pCache->n90pct = pCache->nMax*9/10;
+    pcache1EnforceMaxPage(pGroup);
+    pcache1LeaveMutex(pGroup);
+  }
+}
+
+/*
+** Implementation of the sqlite3_pcache.xPagecount method. 
+*/
+static int pcache1Pagecount(sqlite3_pcache *p){
+  int n;
+  PCache1 *pCache = (PCache1*)p;
+  pcache1EnterMutex(pCache->pGroup);
+  n = pCache->nPage;
+  pcache1LeaveMutex(pCache->pGroup);
+  return n;
+}
+
+/*
+** Implementation of the sqlite3_pcache.xFetch method. 
+**
+** Fetch a page by key value.
+**
+** Whether or not a new page may be allocated by this function depends on
+** the value of the createFlag argument.  0 means do not allocate a new
+** page.  1 means allocate a new page if space is easily available.  2 
+** means to try really hard to allocate a new page.
+**
+** For a non-purgeable cache (a cache used as the storage for an in-memory
+** database) there is really no difference between createFlag 1 and 2.  So
+** the calling function (pcache.c) will never have a createFlag of 1 on
+** a non-purgable cache.
+**
+** There are three different approaches to obtaining space for a page,
+** depending on the value of parameter createFlag (which may be 0, 1 or 2).
+**
+**   1. Regardless of the value of createFlag, the cache is searched for a 
+**      copy of the requested page. If one is found, it is returned.
+**
+**   2. If createFlag==0 and the page is not already in the cache, NULL is
+**      returned.
+**
+**   3. If createFlag is 1, and the page is not already in the cache, then
+**      return NULL (do not allocate a new page) if any of the following
+**      conditions are true:
+**
+**       (a) the number of pages pinned by the cache is greater than
+**           PCache1.nMax, or
+**
+**       (b) the number of pages pinned by the cache is greater than
+**           the sum of nMax for all purgeable caches, less the sum of 
+**           nMin for all other purgeable caches, or
+**
+**   4. If none of the first three conditions apply and the cache is marked
+**      as purgeable, and if one of the following is true:
+**
+**       (a) The number of pages allocated for the cache is already 
+**           PCache1.nMax, or
+**
+**       (b) The number of pages allocated for all purgeable caches is
+**           already equal to or greater than the sum of nMax for all
+**           purgeable caches,
+**
+**       (c) The system is under memory pressure and wants to avoid
+**           unnecessary pages cache entry allocations
+**
+**      then attempt to recycle a page from the LRU list. If it is the right
+**      size, return the recycled buffer. Otherwise, free the buffer and
+**      proceed to step 5. 
+**
+**   5. Otherwise, allocate and return a new page buffer.
+*/
+static void *pcache1Fetch(sqlite3_pcache *p, unsigned int iKey, int createFlag){
+  int nPinned;
+  PCache1 *pCache = (PCache1 *)p;
+  PGroup *pGroup;
+  PgHdr1 *pPage = 0;
+
+  assert( pCache->bPurgeable || createFlag!=1 );
+  assert( pCache->bPurgeable || pCache->nMin==0 );
+  assert( pCache->bPurgeable==0 || pCache->nMin==10 );
+  assert( pCache->nMin==0 || pCache->bPurgeable );
+  pcache1EnterMutex(pGroup = pCache->pGroup);
+
+  /* Step 1: Search the hash table for an existing entry. */
+  if( pCache->nHash>0 ){
+    unsigned int h = iKey % pCache->nHash;
+    for(pPage=pCache->apHash[h]; pPage&&pPage->iKey!=iKey; pPage=pPage->pNext);
+  }
+
+  /* Step 2: Abort if no existing page is found and createFlag is 0 */
+  if( pPage || createFlag==0 ){
+    pcache1PinPage(pPage);
+    goto fetch_out;
+  }
+
+  /* The pGroup local variable will normally be initialized by the
+  ** pcache1EnterMutex() macro above.  But if SQLITE_MUTEX_OMIT is defined,
+  ** then pcache1EnterMutex() is a no-op, so we have to initialize the
+  ** local variable here.  Delaying the initialization of pGroup is an
+  ** optimization:  The common case is to exit the module before reaching
+  ** this point.
+  */
+#ifdef SQLITE_MUTEX_OMIT
+  pGroup = pCache->pGroup;
+#endif
+
+
+  /* Step 3: Abort if createFlag is 1 but the cache is nearly full */
+  nPinned = pCache->nPage - pCache->nRecyclable;
+  assert( nPinned>=0 );
+  assert( pGroup->mxPinned == pGroup->nMaxPage + 10 - pGroup->nMinPage );
+  assert( pCache->n90pct == pCache->nMax*9/10 );
+  if( createFlag==1 && (
+        nPinned>=pGroup->mxPinned
+     || nPinned>=(int)pCache->n90pct
+     || pcache1UnderMemoryPressure(pCache)
+  )){
+    goto fetch_out;
+  }
+
+  if( pCache->nPage>=pCache->nHash && pcache1ResizeHash(pCache) ){
+    goto fetch_out;
+  }
+
+  /* Step 4. Try to recycle a page. */
+  if( pCache->bPurgeable && pGroup->pLruTail && (
+         (pCache->nPage+1>=pCache->nMax)
+      || pGroup->nCurrentPage>=pGroup->nMaxPage
+      || pcache1UnderMemoryPressure(pCache)
+  )){
+    PCache1 *pOtherCache;
+    pPage = pGroup->pLruTail;
+    pcache1RemoveFromHash(pPage);
+    pcache1PinPage(pPage);
+    if( (pOtherCache = pPage->pCache)->szPage!=pCache->szPage ){
+      pcache1FreePage(pPage);
+      pPage = 0;
+    }else{
+      pGroup->nCurrentPage -= 
+               (pOtherCache->bPurgeable - pCache->bPurgeable);
+    }
+  }
+
+  /* Step 5. If a usable page buffer has still not been found, 
+  ** attempt to allocate a new one. 
+  */
+  if( !pPage ){
+    if( createFlag==1 ) sqlite3BeginBenignMalloc();
+    pcache1LeaveMutex(pGroup);
+    pPage = pcache1AllocPage(pCache);
+    pcache1EnterMutex(pGroup);
+    if( createFlag==1 ) sqlite3EndBenignMalloc();
+  }
+
+  if( pPage ){
+    unsigned int h = iKey % pCache->nHash;
+    pCache->nPage++;
+    pPage->iKey = iKey;
+    pPage->pNext = pCache->apHash[h];
+    pPage->pCache = pCache;
+    pPage->pLruPrev = 0;
+    pPage->pLruNext = 0;
+    *(void **)(PGHDR1_TO_PAGE(pPage)) = 0;
+    pCache->apHash[h] = pPage;
+  }
+
+fetch_out:
+  if( pPage && iKey>pCache->iMaxKey ){
+    pCache->iMaxKey = iKey;
+  }
+  pcache1LeaveMutex(pGroup);
+  return (pPage ? PGHDR1_TO_PAGE(pPage) : 0);
+}
+
+
+/*
+** Implementation of the sqlite3_pcache.xUnpin method.
+**
+** Mark a page as unpinned (eligible for asynchronous recycling).
+*/
+static void pcache1Unpin(sqlite3_pcache *p, void *pPg, int reuseUnlikely){
+  PCache1 *pCache = (PCache1 *)p;
+  PgHdr1 *pPage = PAGE_TO_PGHDR1(pCache, pPg);
+  PGroup *pGroup = pCache->pGroup;
+ 
+  assert( pPage->pCache==pCache );
+  pcache1EnterMutex(pGroup);
+
+  /* It is an error to call this function if the page is already 
+  ** part of the PGroup LRU list.
+  */
+  assert( pPage->pLruPrev==0 && pPage->pLruNext==0 );
+  assert( pGroup->pLruHead!=pPage && pGroup->pLruTail!=pPage );
+
+  if( reuseUnlikely || pGroup->nCurrentPage>pGroup->nMaxPage ){
+    pcache1RemoveFromHash(pPage);
+    pcache1FreePage(pPage);
+  }else{
+    /* Add the page to the PGroup LRU list. */
+    if( pGroup->pLruHead ){
+      pGroup->pLruHead->pLruPrev = pPage;
+      pPage->pLruNext = pGroup->pLruHead;
+      pGroup->pLruHead = pPage;
+    }else{
+      pGroup->pLruTail = pPage;
+      pGroup->pLruHead = pPage;
+    }
+    pCache->nRecyclable++;
+  }
+
+  pcache1LeaveMutex(pCache->pGroup);
+}
+
+/*
+** Implementation of the sqlite3_pcache.xRekey method. 
+*/
+static void pcache1Rekey(
+  sqlite3_pcache *p,
+  void *pPg,
+  unsigned int iOld,
+  unsigned int iNew
+){
+  PCache1 *pCache = (PCache1 *)p;
+  PgHdr1 *pPage = PAGE_TO_PGHDR1(pCache, pPg);
+  PgHdr1 **pp;
+  unsigned int h; 
+  assert( pPage->iKey==iOld );
+  assert( pPage->pCache==pCache );
+
+  pcache1EnterMutex(pCache->pGroup);
+
+  h = iOld%pCache->nHash;
+  pp = &pCache->apHash[h];
+  while( (*pp)!=pPage ){
+    pp = &(*pp)->pNext;
+  }
+  *pp = pPage->pNext;
+
+  h = iNew%pCache->nHash;
+  pPage->iKey = iNew;
+  pPage->pNext = pCache->apHash[h];
+  pCache->apHash[h] = pPage;
+  if( iNew>pCache->iMaxKey ){
+    pCache->iMaxKey = iNew;
+  }
+
+  pcache1LeaveMutex(pCache->pGroup);
+}
+
+/*
+** Implementation of the sqlite3_pcache.xTruncate method. 
+**
+** Discard all unpinned pages in the cache with a page number equal to
+** or greater than parameter iLimit. Any pinned pages with a page number
+** equal to or greater than iLimit are implicitly unpinned.
+*/
+static void pcache1Truncate(sqlite3_pcache *p, unsigned int iLimit){
+  PCache1 *pCache = (PCache1 *)p;
+  pcache1EnterMutex(pCache->pGroup);
+  if( iLimit<=pCache->iMaxKey ){
+    pcache1TruncateUnsafe(pCache, iLimit);
+    pCache->iMaxKey = iLimit-1;
+  }
+  pcache1LeaveMutex(pCache->pGroup);
+}
+
+/*
+** Implementation of the sqlite3_pcache.xDestroy method. 
+**
+** Destroy a cache allocated using pcache1Create().
+*/
+static void pcache1Destroy(sqlite3_pcache *p){
+  PCache1 *pCache = (PCache1 *)p;
+  PGroup *pGroup = pCache->pGroup;
+  assert( pCache->bPurgeable || (pCache->nMax==0 && pCache->nMin==0) );
+  pcache1EnterMutex(pGroup);
+  pcache1TruncateUnsafe(pCache, 0);
+  pGroup->nMaxPage -= pCache->nMax;
+  pGroup->nMinPage -= pCache->nMin;
+  pGroup->mxPinned = pGroup->nMaxPage + 10 - pGroup->nMinPage;
+  pcache1EnforceMaxPage(pGroup);
+  pcache1LeaveMutex(pGroup);
+  sqlite3_free(pCache->apHash);
+  sqlite3_free(pCache);
+}
+
+/*
+** This function is called during initialization (sqlite3_initialize()) to
+** install the default pluggable cache module, assuming the user has not
+** already provided an alternative.
+*/
+SQLITE_PRIVATE void sqlite3PCacheSetDefault(void){
+  static const sqlite3_pcache_methods defaultMethods = {
+    0,                       /* pArg */
+    pcache1Init,             /* xInit */
+    pcache1Shutdown,         /* xShutdown */
+    pcache1Create,           /* xCreate */
+    pcache1Cachesize,        /* xCachesize */
+    pcache1Pagecount,        /* xPagecount */
+    pcache1Fetch,            /* xFetch */
+    pcache1Unpin,            /* xUnpin */
+    pcache1Rekey,            /* xRekey */
+    pcache1Truncate,         /* xTruncate */
+    pcache1Destroy           /* xDestroy */
+  };
+  sqlite3_config(SQLITE_CONFIG_PCACHE, &defaultMethods);
+}
+
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+/*
+** This function is called to free superfluous dynamically allocated memory
+** held by the pager system. Memory in use by any SQLite pager allocated
+** by the current thread may be sqlite3_free()ed.
+**
+** nReq is the number of bytes of memory required. Once this much has
+** been released, the function returns. The return value is the total number 
+** of bytes of memory released.
+*/
+SQLITE_PRIVATE int sqlite3PcacheReleaseMemory(int nReq){
+  int nFree = 0;
+  assert( sqlite3_mutex_notheld(pcache1.grp.mutex) );
+  assert( sqlite3_mutex_notheld(pcache1.mutex) );
+  if( pcache1.pStart==0 ){
+    PgHdr1 *p;
+    pcache1EnterMutex(&pcache1.grp);
+    while( (nReq<0 || nFree<nReq) && ((p=pcache1.grp.pLruTail)!=0) ){
+      nFree += pcache1MemSize(PGHDR1_TO_PAGE(p));
+      pcache1PinPage(p);
+      pcache1RemoveFromHash(p);
+      pcache1FreePage(p);
+    }
+    pcache1LeaveMutex(&pcache1.grp);
+  }
+  return nFree;
+}
+#endif /* SQLITE_ENABLE_MEMORY_MANAGEMENT */
+
+#ifdef SQLITE_TEST
+/*
+** This function is used by test procedures to inspect the internal state
+** of the global cache.
+*/
+SQLITE_PRIVATE void sqlite3PcacheStats(
+  int *pnCurrent,      /* OUT: Total number of pages cached */
+  int *pnMax,          /* OUT: Global maximum cache size */
+  int *pnMin,          /* OUT: Sum of PCache1.nMin for purgeable caches */
+  int *pnRecyclable    /* OUT: Total number of pages available for recycling */
+){
+  PgHdr1 *p;
+  int nRecyclable = 0;
+  for(p=pcache1.grp.pLruHead; p; p=p->pLruNext){
+    nRecyclable++;
+  }
+  *pnCurrent = pcache1.grp.nCurrentPage;
+  *pnMax = pcache1.grp.nMaxPage;
+  *pnMin = pcache1.grp.nMinPage;
+  *pnRecyclable = nRecyclable;
+}
+#endif
+
+/************** End of pcache1.c *********************************************/
+/************** Begin file rowset.c ******************************************/
+/*
+** 2008 December 3
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This module implements an object we call a "RowSet".
+**
+** The RowSet object is a collection of rowids.  Rowids
+** are inserted into the RowSet in an arbitrary order.  Inserts
+** can be intermixed with tests to see if a given rowid has been
+** previously inserted into the RowSet.
+**
+** After all inserts are finished, it is possible to extract the
+** elements of the RowSet in sorted order.  Once this extraction
+** process has started, no new elements may be inserted.
+**
+** Hence, the primitive operations for a RowSet are:
+**
+**    CREATE
+**    INSERT
+**    TEST
+**    SMALLEST
+**    DESTROY
+**
+** The CREATE and DESTROY primitives are the constructor and destructor,
+** obviously.  The INSERT primitive adds a new element to the RowSet.
+** TEST checks to see if an element is already in the RowSet.  SMALLEST
+** extracts the least value from the RowSet.
+**
+** The INSERT primitive might allocate additional memory.  Memory is
+** allocated in chunks so most INSERTs do no allocation.  There is an 
+** upper bound on the size of allocated memory.  No memory is freed
+** until DESTROY.
+**
+** The TEST primitive includes a "batch" number.  The TEST primitive
+** will only see elements that were inserted before the last change
+** in the batch number.  In other words, if an INSERT occurs between
+** two TESTs where the TESTs have the same batch nubmer, then the
+** value added by the INSERT will not be visible to the second TEST.
+** The initial batch number is zero, so if the very first TEST contains
+** a non-zero batch number, it will see all prior INSERTs.
+**
+** No INSERTs may occurs after a SMALLEST.  An assertion will fail if
+** that is attempted.
+**
+** The cost of an INSERT is roughly constant.  (Sometime new memory
+** has to be allocated on an INSERT.)  The cost of a TEST with a new
+** batch number is O(NlogN) where N is the number of elements in the RowSet.
+** The cost of a TEST using the same batch number is O(logN).  The cost
+** of the first SMALLEST is O(NlogN).  Second and subsequent SMALLEST
+** primitives are constant time.  The cost of DESTROY is O(N).
+**
+** There is an added cost of O(N) when switching between TEST and
+** SMALLEST primitives.
+*/
+
+
+/*
+** Target size for allocation chunks.
+*/
+#define ROWSET_ALLOCATION_SIZE 1024
+
+/*
+** The number of rowset entries per allocation chunk.
+*/
+#define ROWSET_ENTRY_PER_CHUNK  \
+                       ((ROWSET_ALLOCATION_SIZE-8)/sizeof(struct RowSetEntry))
+
+/*
+** Each entry in a RowSet is an instance of the following object.
+*/
+struct RowSetEntry {            
+  i64 v;                        /* ROWID value for this entry */
+  struct RowSetEntry *pRight;   /* Right subtree (larger entries) or list */
+  struct RowSetEntry *pLeft;    /* Left subtree (smaller entries) */
+};
+
+/*
+** RowSetEntry objects are allocated in large chunks (instances of the
+** following structure) to reduce memory allocation overhead.  The
+** chunks are kept on a linked list so that they can be deallocated
+** when the RowSet is destroyed.
+*/
+struct RowSetChunk {
+  struct RowSetChunk *pNextChunk;        /* Next chunk on list of them all */
+  struct RowSetEntry aEntry[ROWSET_ENTRY_PER_CHUNK]; /* Allocated entries */
+};
+
+/*
+** A RowSet in an instance of the following structure.
+**
+** A typedef of this structure if found in sqliteInt.h.
+*/
+struct RowSet {
+  struct RowSetChunk *pChunk;    /* List of all chunk allocations */
+  sqlite3 *db;                   /* The database connection */
+  struct RowSetEntry *pEntry;    /* List of entries using pRight */
+  struct RowSetEntry *pLast;     /* Last entry on the pEntry list */
+  struct RowSetEntry *pFresh;    /* Source of new entry objects */
+  struct RowSetEntry *pTree;     /* Binary tree of entries */
+  u16 nFresh;                    /* Number of objects on pFresh */
+  u8 isSorted;                   /* True if pEntry is sorted */
+  u8 iBatch;                     /* Current insert batch */
+};
+
+/*
+** Turn bulk memory into a RowSet object.  N bytes of memory
+** are available at pSpace.  The db pointer is used as a memory context
+** for any subsequent allocations that need to occur.
+** Return a pointer to the new RowSet object.
+**
+** It must be the case that N is sufficient to make a Rowset.  If not
+** an assertion fault occurs.
+** 
+** If N is larger than the minimum, use the surplus as an initial
+** allocation of entries available to be filled.
+*/
+SQLITE_PRIVATE RowSet *sqlite3RowSetInit(sqlite3 *db, void *pSpace, unsigned int N){
+  RowSet *p;
+  assert( N >= ROUND8(sizeof(*p)) );
+  p = pSpace;
+  p->pChunk = 0;
+  p->db = db;
+  p->pEntry = 0;
+  p->pLast = 0;
+  p->pTree = 0;
+  p->pFresh = (struct RowSetEntry*)(ROUND8(sizeof(*p)) + (char*)p);
+  p->nFresh = (u16)((N - ROUND8(sizeof(*p)))/sizeof(struct RowSetEntry));
+  p->isSorted = 1;
+  p->iBatch = 0;
+  return p;
+}
+
+/*
+** Deallocate all chunks from a RowSet.  This frees all memory that
+** the RowSet has allocated over its lifetime.  This routine is
+** the destructor for the RowSet.
+*/
+SQLITE_PRIVATE void sqlite3RowSetClear(RowSet *p){
+  struct RowSetChunk *pChunk, *pNextChunk;
+  for(pChunk=p->pChunk; pChunk; pChunk = pNextChunk){
+    pNextChunk = pChunk->pNextChunk;
+    sqlite3DbFree(p->db, pChunk);
+  }
+  p->pChunk = 0;
+  p->nFresh = 0;
+  p->pEntry = 0;
+  p->pLast = 0;
+  p->pTree = 0;
+  p->isSorted = 1;
+}
+
+/*
+** Insert a new value into a RowSet.
+**
+** The mallocFailed flag of the database connection is set if a
+** memory allocation fails.
+*/
+SQLITE_PRIVATE void sqlite3RowSetInsert(RowSet *p, i64 rowid){
+  struct RowSetEntry *pEntry;  /* The new entry */
+  struct RowSetEntry *pLast;   /* The last prior entry */
+  assert( p!=0 );
+  if( p->nFresh==0 ){
+    struct RowSetChunk *pNew;
+    pNew = sqlite3DbMallocRaw(p->db, sizeof(*pNew));
+    if( pNew==0 ){
+      return;
+    }
+    pNew->pNextChunk = p->pChunk;
+    p->pChunk = pNew;
+    p->pFresh = pNew->aEntry;
+    p->nFresh = ROWSET_ENTRY_PER_CHUNK;
+  }
+  pEntry = p->pFresh++;
+  p->nFresh--;
+  pEntry->v = rowid;
+  pEntry->pRight = 0;
+  pLast = p->pLast;
+  if( pLast ){
+    if( p->isSorted && rowid<=pLast->v ){
+      p->isSorted = 0;
+    }
+    pLast->pRight = pEntry;
+  }else{
+    assert( p->pEntry==0 ); /* Fires if INSERT after SMALLEST */
+    p->pEntry = pEntry;
+  }
+  p->pLast = pEntry;
+}
+
+/*
+** Merge two lists of RowSetEntry objects.  Remove duplicates.
+**
+** The input lists are connected via pRight pointers and are 
+** assumed to each already be in sorted order.
+*/
+static struct RowSetEntry *rowSetMerge(
+  struct RowSetEntry *pA,    /* First sorted list to be merged */
+  struct RowSetEntry *pB     /* Second sorted list to be merged */
+){
+  struct RowSetEntry head;
+  struct RowSetEntry *pTail;
+
+  pTail = &head;
+  while( pA && pB ){
+    assert( pA->pRight==0 || pA->v<=pA->pRight->v );
+    assert( pB->pRight==0 || pB->v<=pB->pRight->v );
+    if( pA->v<pB->v ){
+      pTail->pRight = pA;
+      pA = pA->pRight;
+      pTail = pTail->pRight;
+    }else if( pB->v<pA->v ){
+      pTail->pRight = pB;
+      pB = pB->pRight;
+      pTail = pTail->pRight;
+    }else{
+      pA = pA->pRight;
+    }
+  }
+  if( pA ){
+    assert( pA->pRight==0 || pA->v<=pA->pRight->v );
+    pTail->pRight = pA;
+  }else{
+    assert( pB==0 || pB->pRight==0 || pB->v<=pB->pRight->v );
+    pTail->pRight = pB;
+  }
+  return head.pRight;
+}
+
+/*
+** Sort all elements on the pEntry list of the RowSet into ascending order.
+*/ 
+static void rowSetSort(RowSet *p){
+  unsigned int i;
+  struct RowSetEntry *pEntry;
+  struct RowSetEntry *aBucket[40];
+
+  assert( p->isSorted==0 );
+  memset(aBucket, 0, sizeof(aBucket));
+  while( p->pEntry ){
+    pEntry = p->pEntry;
+    p->pEntry = pEntry->pRight;
+    pEntry->pRight = 0;
+    for(i=0; aBucket[i]; i++){
+      pEntry = rowSetMerge(aBucket[i], pEntry);
+      aBucket[i] = 0;
+    }
+    aBucket[i] = pEntry;
+  }
+  pEntry = 0;
+  for(i=0; i<sizeof(aBucket)/sizeof(aBucket[0]); i++){
+    pEntry = rowSetMerge(pEntry, aBucket[i]);
+  }
+  p->pEntry = pEntry;
+  p->pLast = 0;
+  p->isSorted = 1;
+}
+
+
+/*
+** The input, pIn, is a binary tree (or subtree) of RowSetEntry objects.
+** Convert this tree into a linked list connected by the pRight pointers
+** and return pointers to the first and last elements of the new list.
+*/
+static void rowSetTreeToList(
+  struct RowSetEntry *pIn,         /* Root of the input tree */
+  struct RowSetEntry **ppFirst,    /* Write head of the output list here */
+  struct RowSetEntry **ppLast      /* Write tail of the output list here */
+){
+  assert( pIn!=0 );
+  if( pIn->pLeft ){
+    struct RowSetEntry *p;
+    rowSetTreeToList(pIn->pLeft, ppFirst, &p);
+    p->pRight = pIn;
+  }else{
+    *ppFirst = pIn;
+  }
+  if( pIn->pRight ){
+    rowSetTreeToList(pIn->pRight, &pIn->pRight, ppLast);
+  }else{
+    *ppLast = pIn;
+  }
+  assert( (*ppLast)->pRight==0 );
+}
+
+
+/*
+** Convert a sorted list of elements (connected by pRight) into a binary
+** tree with depth of iDepth.  A depth of 1 means the tree contains a single
+** node taken from the head of *ppList.  A depth of 2 means a tree with
+** three nodes.  And so forth.
+**
+** Use as many entries from the input list as required and update the
+** *ppList to point to the unused elements of the list.  If the input
+** list contains too few elements, then construct an incomplete tree
+** and leave *ppList set to NULL.
+**
+** Return a pointer to the root of the constructed binary tree.
+*/
+static struct RowSetEntry *rowSetNDeepTree(
+  struct RowSetEntry **ppList,
+  int iDepth
+){
+  struct RowSetEntry *p;         /* Root of the new tree */
+  struct RowSetEntry *pLeft;     /* Left subtree */
+  if( *ppList==0 ){
+    return 0;
+  }
+  if( iDepth==1 ){
+    p = *ppList;
+    *ppList = p->pRight;
+    p->pLeft = p->pRight = 0;
+    return p;
+  }
+  pLeft = rowSetNDeepTree(ppList, iDepth-1);
+  p = *ppList;
+  if( p==0 ){
+    return pLeft;
+  }
+  p->pLeft = pLeft;
+  *ppList = p->pRight;
+  p->pRight = rowSetNDeepTree(ppList, iDepth-1);
+  return p;
+}
+
+/*
+** Convert a sorted list of elements into a binary tree. Make the tree
+** as deep as it needs to be in order to contain the entire list.
+*/
+static struct RowSetEntry *rowSetListToTree(struct RowSetEntry *pList){
+  int iDepth;           /* Depth of the tree so far */
+  struct RowSetEntry *p;       /* Current tree root */
+  struct RowSetEntry *pLeft;   /* Left subtree */
+
+  assert( pList!=0 );
+  p = pList;
+  pList = p->pRight;
+  p->pLeft = p->pRight = 0;
+  for(iDepth=1; pList; iDepth++){
+    pLeft = p;
+    p = pList;
+    pList = p->pRight;
+    p->pLeft = pLeft;
+    p->pRight = rowSetNDeepTree(&pList, iDepth);
+  }
+  return p;
+}
+
+/*
+** Convert the list in p->pEntry into a sorted list if it is not
+** sorted already.  If there is a binary tree on p->pTree, then
+** convert it into a list too and merge it into the p->pEntry list.
+*/
+static void rowSetToList(RowSet *p){
+  if( !p->isSorted ){
+    rowSetSort(p);
+  }
+  if( p->pTree ){
+    struct RowSetEntry *pHead, *pTail;
+    rowSetTreeToList(p->pTree, &pHead, &pTail);
+    p->pTree = 0;
+    p->pEntry = rowSetMerge(p->pEntry, pHead);
+  }
+}
+
+/*
+** Extract the smallest element from the RowSet.
+** Write the element into *pRowid.  Return 1 on success.  Return
+** 0 if the RowSet is already empty.
+**
+** After this routine has been called, the sqlite3RowSetInsert()
+** routine may not be called again.  
+*/
+SQLITE_PRIVATE int sqlite3RowSetNext(RowSet *p, i64 *pRowid){
+  rowSetToList(p);
+  if( p->pEntry ){
+    *pRowid = p->pEntry->v;
+    p->pEntry = p->pEntry->pRight;
+    if( p->pEntry==0 ){
+      sqlite3RowSetClear(p);
+    }
+    return 1;
+  }else{
+    return 0;
+  }
+}
+
+/*
+** Check to see if element iRowid was inserted into the the rowset as
+** part of any insert batch prior to iBatch.  Return 1 or 0.
+*/
+SQLITE_PRIVATE int sqlite3RowSetTest(RowSet *pRowSet, u8 iBatch, sqlite3_int64 iRowid){
+  struct RowSetEntry *p;
+  if( iBatch!=pRowSet->iBatch ){
+    if( pRowSet->pEntry ){
+      rowSetToList(pRowSet);
+      pRowSet->pTree = rowSetListToTree(pRowSet->pEntry);
+      pRowSet->pEntry = 0;
+      pRowSet->pLast = 0;
+    }
+    pRowSet->iBatch = iBatch;
+  }
+  p = pRowSet->pTree;
+  while( p ){
+    if( p->v<iRowid ){
+      p = p->pRight;
+    }else if( p->v>iRowid ){
+      p = p->pLeft;
+    }else{
+      return 1;
+    }
+  }
+  return 0;
+}
+
+/************** End of rowset.c **********************************************/
+/************** Begin file pager.c *******************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This is the implementation of the page cache subsystem or "pager".
+** 
+** The pager is used to access a database disk file.  It implements
+** atomic commit and rollback through the use of a journal file that
+** is separate from the database file.  The pager also implements file
+** locking to prevent two processes from writing the same database
+** file simultaneously, or one process from reading the database while
+** another is writing.
+*/
+#ifndef SQLITE_OMIT_DISKIO
+/************** Include wal.h in the middle of pager.c ***********************/
+/************** Begin file wal.h *********************************************/
+/*
+** 2010 February 1
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This header file defines the interface to the write-ahead logging 
+** system. Refer to the comments below and the header comment attached to 
+** the implementation of each function in log.c for further details.
+*/
+
+#ifndef _WAL_H_
+#define _WAL_H_
+
+
+#ifdef SQLITE_OMIT_WAL
+# define sqlite3WalOpen(x,y,z)                   0
+# define sqlite3WalClose(w,x,y,z)                0
+# define sqlite3WalBeginReadTransaction(y,z)     0
+# define sqlite3WalEndReadTransaction(z)
+# define sqlite3WalRead(v,w,x,y,z)               0
+# define sqlite3WalDbsize(y)                     0
+# define sqlite3WalBeginWriteTransaction(y)      0
+# define sqlite3WalEndWriteTransaction(x)        0
+# define sqlite3WalUndo(x,y,z)                   0
+# define sqlite3WalSavepoint(y,z)
+# define sqlite3WalSavepointUndo(y,z)            0
+# define sqlite3WalFrames(u,v,w,x,y,z)           0
+# define sqlite3WalCheckpoint(r,s,t,u,v,w,x,y,z) 0
+# define sqlite3WalCallback(z)                   0
+# define sqlite3WalExclusiveMode(y,z)            0
+# define sqlite3WalHeapMemory(z)                 0
+#else
+
+#define WAL_SAVEPOINT_NDATA 4
+
+/* Connection to a write-ahead log (WAL) file. 
+** There is one object of this type for each pager. 
+*/
+typedef struct Wal Wal;
+
+/* Open and close a connection to a write-ahead log. */
+SQLITE_PRIVATE int sqlite3WalOpen(sqlite3_vfs*, sqlite3_file*, const char *zName, int, Wal**);
+SQLITE_PRIVATE int sqlite3WalClose(Wal *pWal, int sync_flags, int, u8 *);
+
+/* Used by readers to open (lock) and close (unlock) a snapshot.  A 
+** snapshot is like a read-transaction.  It is the state of the database
+** at an instant in time.  sqlite3WalOpenSnapshot gets a read lock and
+** preserves the current state even if the other threads or processes
+** write to or checkpoint the WAL.  sqlite3WalCloseSnapshot() closes the
+** transaction and releases the lock.
+*/
+SQLITE_PRIVATE int sqlite3WalBeginReadTransaction(Wal *pWal, int *);
+SQLITE_PRIVATE void sqlite3WalEndReadTransaction(Wal *pWal);
+
+/* Read a page from the write-ahead log, if it is present. */
+SQLITE_PRIVATE int sqlite3WalRead(Wal *pWal, Pgno pgno, int *pInWal, int nOut, u8 *pOut);
+
+/* If the WAL is not empty, return the size of the database. */
+SQLITE_PRIVATE Pgno sqlite3WalDbsize(Wal *pWal);
+
+/* Obtain or release the WRITER lock. */
+SQLITE_PRIVATE int sqlite3WalBeginWriteTransaction(Wal *pWal);
+SQLITE_PRIVATE int sqlite3WalEndWriteTransaction(Wal *pWal);
+
+/* Undo any frames written (but not committed) to the log */
+SQLITE_PRIVATE int sqlite3WalUndo(Wal *pWal, int (*xUndo)(void *, Pgno), void *pUndoCtx);
+
+/* Return an integer that records the current (uncommitted) write
+** position in the WAL */
+SQLITE_PRIVATE void sqlite3WalSavepoint(Wal *pWal, u32 *aWalData);
+
+/* Move the write position of the WAL back to iFrame.  Called in
+** response to a ROLLBACK TO command. */
+SQLITE_PRIVATE int sqlite3WalSavepointUndo(Wal *pWal, u32 *aWalData);
+
+/* Write a frame or frames to the log. */
+SQLITE_PRIVATE int sqlite3WalFrames(Wal *pWal, int, PgHdr *, Pgno, int, int);
+
+/* Copy pages from the log to the database file */ 
+SQLITE_PRIVATE int sqlite3WalCheckpoint(
+  Wal *pWal,                      /* Write-ahead log connection */
+  int eMode,                      /* One of PASSIVE, FULL and RESTART */
+  int (*xBusy)(void*),            /* Function to call when busy */
+  void *pBusyArg,                 /* Context argument for xBusyHandler */
+  int sync_flags,                 /* Flags to sync db file with (or 0) */
+  int nBuf,                       /* Size of buffer nBuf */
+  u8 *zBuf,                       /* Temporary buffer to use */
+  int *pnLog,                     /* OUT: Number of frames in WAL */
+  int *pnCkpt                     /* OUT: Number of backfilled frames in WAL */
+);
+
+/* Return the value to pass to a sqlite3_wal_hook callback, the
+** number of frames in the WAL at the point of the last commit since
+** sqlite3WalCallback() was called.  If no commits have occurred since
+** the last call, then return 0.
+*/
+SQLITE_PRIVATE int sqlite3WalCallback(Wal *pWal);
+
+/* Tell the wal layer that an EXCLUSIVE lock has been obtained (or released)
+** by the pager layer on the database file.
+*/
+SQLITE_PRIVATE int sqlite3WalExclusiveMode(Wal *pWal, int op);
+
+/* Return true if the argument is non-NULL and the WAL module is using
+** heap-memory for the wal-index. Otherwise, if the argument is NULL or the
+** WAL module is using shared-memory, return false. 
+*/
+SQLITE_PRIVATE int sqlite3WalHeapMemory(Wal *pWal);
+
+#endif /* ifndef SQLITE_OMIT_WAL */
+#endif /* _WAL_H_ */
+
+/************** End of wal.h *************************************************/
+/************** Continuing where we left off in pager.c **********************/
+
+
+/******************* NOTES ON THE DESIGN OF THE PAGER ************************
+**
+** This comment block describes invariants that hold when using a rollback
+** journal.  These invariants do not apply for journal_mode=WAL,
+** journal_mode=MEMORY, or journal_mode=OFF.
+**
+** Within this comment block, a page is deemed to have been synced
+** automatically as soon as it is written when PRAGMA synchronous=OFF.
+** Otherwise, the page is not synced until the xSync method of the VFS
+** is called successfully on the file containing the page.
+**
+** Definition:  A page of the database file is said to be "overwriteable" if
+** one or more of the following are true about the page:
+** 
+**     (a)  The original content of the page as it was at the beginning of
+**          the transaction has been written into the rollback journal and
+**          synced.
+** 
+**     (b)  The page was a freelist leaf page at the start of the transaction.
+** 
+**     (c)  The page number is greater than the largest page that existed in
+**          the database file at the start of the transaction.
+** 
+** (1) A page of the database file is never overwritten unless one of the
+**     following are true:
+** 
+**     (a) The page and all other pages on the same sector are overwriteable.
+** 
+**     (b) The atomic page write optimization is enabled, and the entire
+**         transaction other than the update of the transaction sequence
+**         number consists of a single page change.
+** 
+** (2) The content of a page written into the rollback journal exactly matches
+**     both the content in the database when the rollback journal was written
+**     and the content in the database at the beginning of the current
+**     transaction.
+** 
+** (3) Writes to the database file are an integer multiple of the page size
+**     in length and are aligned on a page boundary.
+** 
+** (4) Reads from the database file are either aligned on a page boundary and
+**     an integer multiple of the page size in length or are taken from the
+**     first 100 bytes of the database file.
+** 
+** (5) All writes to the database file are synced prior to the rollback journal
+**     being deleted, truncated, or zeroed.
+** 
+** (6) If a master journal file is used, then all writes to the database file
+**     are synced prior to the master journal being deleted.
+** 
+** Definition: Two databases (or the same database at two points it time)
+** are said to be "logically equivalent" if they give the same answer to
+** all queries.  Note in particular the the content of freelist leaf
+** pages can be changed arbitarily without effecting the logical equivalence
+** of the database.
+** 
+** (7) At any time, if any subset, including the empty set and the total set,
+**     of the unsynced changes to a rollback journal are removed and the 
+**     journal is rolled back, the resulting database file will be logical
+**     equivalent to the database file at the beginning of the transaction.
+** 
+** (8) When a transaction is rolled back, the xTruncate method of the VFS
+**     is called to restore the database file to the same size it was at
+**     the beginning of the transaction.  (In some VFSes, the xTruncate
+**     method is a no-op, but that does not change the fact the SQLite will
+**     invoke it.)
+** 
+** (9) Whenever the database file is modified, at least one bit in the range
+**     of bytes from 24 through 39 inclusive will be changed prior to releasing
+**     the EXCLUSIVE lock, thus signaling other connections on the same
+**     database to flush their caches.
+**
+** (10) The pattern of bits in bytes 24 through 39 shall not repeat in less
+**      than one billion transactions.
+**
+** (11) A database file is well-formed at the beginning and at the conclusion
+**      of every transaction.
+**
+** (12) An EXCLUSIVE lock is held on the database file when writing to
+**      the database file.
+**
+** (13) A SHARED lock is held on the database file while reading any
+**      content out of the database file.
+**
+******************************************************************************/
+
+/*
+** Macros for troubleshooting.  Normally turned off
+*/
+#if 0
+int sqlite3PagerTrace=1;  /* True to enable tracing */
+#define sqlite3DebugPrintf printf
+#define PAGERTRACE(X)     if( sqlite3PagerTrace ){ sqlite3DebugPrintf X; }
+#else
+#define PAGERTRACE(X)
+#endif
+
+/*
+** The following two macros are used within the PAGERTRACE() macros above
+** to print out file-descriptors. 
+**
+** PAGERID() takes a pointer to a Pager struct as its argument. The
+** associated file-descriptor is returned. FILEHANDLEID() takes an sqlite3_file
+** struct as its argument.
+*/
+#define PAGERID(p) ((int)(p->fd))
+#define FILEHANDLEID(fd) ((int)fd)
+
+/*
+** The Pager.eState variable stores the current 'state' of a pager. A
+** pager may be in any one of the seven states shown in the following
+** state diagram.
+**
+**                            OPEN <------+------+
+**                              |         |      |
+**                              V         |      |
+**               +---------> READER-------+      |
+**               |              |                |
+**               |              V                |
+**               |<-------WRITER_LOCKED------> ERROR
+**               |              |                ^  
+**               |              V                |
+**               |<------WRITER_CACHEMOD-------->|
+**               |              |                |
+**               |              V                |
+**               |<-------WRITER_DBMOD---------->|
+**               |              |                |
+**               |              V                |
+**               +<------WRITER_FINISHED-------->+
+**
+**
+** List of state transitions and the C [function] that performs each:
+** 
+**   OPEN              -> READER              [sqlite3PagerSharedLock]
+**   READER            -> OPEN                [pager_unlock]
+**
+**   READER            -> WRITER_LOCKED       [sqlite3PagerBegin]
+**   WRITER_LOCKED     -> WRITER_CACHEMOD     [pager_open_journal]
+**   WRITER_CACHEMOD   -> WRITER_DBMOD        [syncJournal]
+**   WRITER_DBMOD      -> WRITER_FINISHED     [sqlite3PagerCommitPhaseOne]
+**   WRITER_***        -> READER              [pager_end_transaction]
+**
+**   WRITER_***        -> ERROR               [pager_error]
+**   ERROR             -> OPEN                [pager_unlock]
+** 
+**
+**  OPEN:
+**
+**    The pager starts up in this state. Nothing is guaranteed in this
+**    state - the file may or may not be locked and the database size is
+**    unknown. The database may not be read or written.
+**
+**    * No read or write transaction is active.
+**    * Any lock, or no lock at all, may be held on the database file.
+**    * The dbSize, dbOrigSize and dbFileSize variables may not be trusted.
+**
+**  READER:
+**
+**    In this state all the requirements for reading the database in 
+**    rollback (non-WAL) mode are met. Unless the pager is (or recently
+**    was) in exclusive-locking mode, a user-level read transaction is 
+**    open. The database size is known in this state.
+**
+**    A connection running with locking_mode=normal enters this state when
+**    it opens a read-transaction on the database and returns to state
+**    OPEN after the read-transaction is completed. However a connection
+**    running in locking_mode=exclusive (including temp databases) remains in
+**    this state even after the read-transaction is closed. The only way
+**    a locking_mode=exclusive connection can transition from READER to OPEN
+**    is via the ERROR state (see below).
+** 
+**    * A read transaction may be active (but a write-transaction cannot).
+**    * A SHARED or greater lock is held on the database file.
+**    * The dbSize variable may be trusted (even if a user-level read 
+**      transaction is not active). The dbOrigSize and dbFileSize variables
+**      may not be trusted at this point.
+**    * If the database is a WAL database, then the WAL connection is open.
+**    * Even if a read-transaction is not open, it is guaranteed that 
+**      there is no hot-journal in the file-system.
+**
+**  WRITER_LOCKED:
+**
+**    The pager moves to this state from READER when a write-transaction
+**    is first opened on the database. In WRITER_LOCKED state, all locks 
+**    required to start a write-transaction are held, but no actual 
+**    modifications to the cache or database have taken place.
+**
+**    In rollback mode, a RESERVED or (if the transaction was opened with 
+**    BEGIN EXCLUSIVE) EXCLUSIVE lock is obtained on the database file when
+**    moving to this state, but the journal file is not written to or opened 
+**    to in this state. If the transaction is committed or rolled back while 
+**    in WRITER_LOCKED state, all that is required is to unlock the database 
+**    file.
+**
+**    IN WAL mode, WalBeginWriteTransaction() is called to lock the log file.
+**    If the connection is running with locking_mode=exclusive, an attempt
+**    is made to obtain an EXCLUSIVE lock on the database file.
+**
+**    * A write transaction is active.
+**    * If the connection is open in rollback-mode, a RESERVED or greater 
+**      lock is held on the database file.
+**    * If the connection is open in WAL-mode, a WAL write transaction
+**      is open (i.e. sqlite3WalBeginWriteTransaction() has been successfully
+**      called).
+**    * The dbSize, dbOrigSize and dbFileSize variables are all valid.
+**    * The contents of the pager cache have not been modified.
+**    * The journal file may or may not be open.
+**    * Nothing (not even the first header) has been written to the journal.
+**
+**  WRITER_CACHEMOD:
+**
+**    A pager moves from WRITER_LOCKED state to this state when a page is
+**    first modified by the upper layer. In rollback mode the journal file
+**    is opened (if it is not already open) and a header written to the
+**    start of it. The database file on disk has not been modified.
+**
+**    * A write transaction is active.
+**    * A RESERVED or greater lock is held on the database file.
+**    * The journal file is open and the first header has been written 
+**      to it, but the header has not been synced to disk.
+**    * The contents of the page cache have been modified.
+**
+**  WRITER_DBMOD:
+**
+**    The pager transitions from WRITER_CACHEMOD into WRITER_DBMOD state
+**    when it modifies the contents of the database file. WAL connections
+**    never enter this state (since they do not modify the database file,
+**    just the log file).
+**
+**    * A write transaction is active.
+**    * An EXCLUSIVE or greater lock is held on the database file.
+**    * The journal file is open and the first header has been written 
+**      and synced to disk.
+**    * The contents of the page cache have been modified (and possibly
+**      written to disk).
+**
+**  WRITER_FINISHED:
+**
+**    It is not possible for a WAL connection to enter this state.
+**
+**    A rollback-mode pager changes to WRITER_FINISHED state from WRITER_DBMOD
+**    state after the entire transaction has been successfully written into the
+**    database file. In this state the transaction may be committed simply
+**    by finalizing the journal file. Once in WRITER_FINISHED state, it is 
+**    not possible to modify the database further. At this point, the upper 
+**    layer must either commit or rollback the transaction.
+**
+**    * A write transaction is active.
+**    * An EXCLUSIVE or greater lock is held on the database file.
+**    * All writing and syncing of journal and database data has finished.
+**      If no error occured, all that remains is to finalize the journal to
+**      commit the transaction. If an error did occur, the caller will need
+**      to rollback the transaction. 
+**
+**  ERROR:
+**
+**    The ERROR state is entered when an IO or disk-full error (including
+**    SQLITE_IOERR_NOMEM) occurs at a point in the code that makes it 
+**    difficult to be sure that the in-memory pager state (cache contents, 
+**    db size etc.) are consistent with the contents of the file-system.
+**
+**    Temporary pager files may enter the ERROR state, but in-memory pagers
+**    cannot.
+**
+**    For example, if an IO error occurs while performing a rollback, 
+**    the contents of the page-cache may be left in an inconsistent state.
+**    At this point it would be dangerous to change back to READER state
+**    (as usually happens after a rollback). Any subsequent readers might
+**    report database corruption (due to the inconsistent cache), and if
+**    they upgrade to writers, they may inadvertently corrupt the database
+**    file. To avoid this hazard, the pager switches into the ERROR state
+**    instead of READER following such an error.
+**
+**    Once it has entered the ERROR state, any attempt to use the pager
+**    to read or write data returns an error. Eventually, once all 
+**    outstanding transactions have been abandoned, the pager is able to
+**    transition back to OPEN state, discarding the contents of the 
+**    page-cache and any other in-memory state at the same time. Everything
+**    is reloaded from disk (and, if necessary, hot-journal rollback peformed)
+**    when a read-transaction is next opened on the pager (transitioning
+**    the pager into READER state). At that point the system has recovered 
+**    from the error.
+**
+**    Specifically, the pager jumps into the ERROR state if:
+**
+**      1. An error occurs while attempting a rollback. This happens in
+**         function sqlite3PagerRollback().
+**
+**      2. An error occurs while attempting to finalize a journal file
+**         following a commit in function sqlite3PagerCommitPhaseTwo().
+**
+**      3. An error occurs while attempting to write to the journal or
+**         database file in function pagerStress() in order to free up
+**         memory.
+**
+**    In other cases, the error is returned to the b-tree layer. The b-tree
+**    layer then attempts a rollback operation. If the error condition 
+**    persists, the pager enters the ERROR state via condition (1) above.
+**
+**    Condition (3) is necessary because it can be triggered by a read-only
+**    statement executed within a transaction. In this case, if the error
+**    code were simply returned to the user, the b-tree layer would not
+**    automatically attempt a rollback, as it assumes that an error in a
+**    read-only statement cannot leave the pager in an internally inconsistent 
+**    state.
+**
+**    * The Pager.errCode variable is set to something other than SQLITE_OK.
+**    * There are one or more outstanding references to pages (after the
+**      last reference is dropped the pager should move back to OPEN state).
+**    * The pager is not an in-memory pager.
+**    
+**
+** Notes:
+**
+**   * A pager is never in WRITER_DBMOD or WRITER_FINISHED state if the
+**     connection is open in WAL mode. A WAL connection is always in one
+**     of the first four states.
+**
+**   * Normally, a connection open in exclusive mode is never in PAGER_OPEN
+**     state. There are two exceptions: immediately after exclusive-mode has
+**     been turned on (and before any read or write transactions are 
+**     executed), and when the pager is leaving the "error state".
+**
+**   * See also: assert_pager_state().
+*/
+#define PAGER_OPEN                  0
+#define PAGER_READER                1
+#define PAGER_WRITER_LOCKED         2
+#define PAGER_WRITER_CACHEMOD       3
+#define PAGER_WRITER_DBMOD          4
+#define PAGER_WRITER_FINISHED       5
+#define PAGER_ERROR                 6
+
+/*
+** The Pager.eLock variable is almost always set to one of the 
+** following locking-states, according to the lock currently held on
+** the database file: NO_LOCK, SHARED_LOCK, RESERVED_LOCK or EXCLUSIVE_LOCK.
+** This variable is kept up to date as locks are taken and released by
+** the pagerLockDb() and pagerUnlockDb() wrappers.
+**
+** If the VFS xLock() or xUnlock() returns an error other than SQLITE_BUSY
+** (i.e. one of the SQLITE_IOERR subtypes), it is not clear whether or not
+** the operation was successful. In these circumstances pagerLockDb() and
+** pagerUnlockDb() take a conservative approach - eLock is always updated
+** when unlocking the file, and only updated when locking the file if the
+** VFS call is successful. This way, the Pager.eLock variable may be set
+** to a less exclusive (lower) value than the lock that is actually held
+** at the system level, but it is never set to a more exclusive value.
+**
+** This is usually safe. If an xUnlock fails or appears to fail, there may 
+** be a few redundant xLock() calls or a lock may be held for longer than
+** required, but nothing really goes wrong.
+**
+** The exception is when the database file is unlocked as the pager moves
+** from ERROR to OPEN state. At this point there may be a hot-journal file 
+** in the file-system that needs to be rolled back (as part of a OPEN->SHARED
+** transition, by the same pager or any other). If the call to xUnlock()
+** fails at this point and the pager is left holding an EXCLUSIVE lock, this
+** can confuse the call to xCheckReservedLock() call made later as part
+** of hot-journal detection.
+**
+** xCheckReservedLock() is defined as returning true "if there is a RESERVED 
+** lock held by this process or any others". So xCheckReservedLock may 
+** return true because the caller itself is holding an EXCLUSIVE lock (but
+** doesn't know it because of a previous error in xUnlock). If this happens
+** a hot-journal may be mistaken for a journal being created by an active
+** transaction in another process, causing SQLite to read from the database
+** without rolling it back.
+**
+** To work around this, if a call to xUnlock() fails when unlocking the
+** database in the ERROR state, Pager.eLock is set to UNKNOWN_LOCK. It
+** is only changed back to a real locking state after a successful call
+** to xLock(EXCLUSIVE). Also, the code to do the OPEN->SHARED state transition
+** omits the check for a hot-journal if Pager.eLock is set to UNKNOWN_LOCK 
+** lock. Instead, it assumes a hot-journal exists and obtains an EXCLUSIVE
+** lock on the database file before attempting to roll it back. See function
+** PagerSharedLock() for more detail.
+**
+** Pager.eLock may only be set to UNKNOWN_LOCK when the pager is in 
+** PAGER_OPEN state.
+*/
+#define UNKNOWN_LOCK                (EXCLUSIVE_LOCK+1)
+
+/*
+** A macro used for invoking the codec if there is one
+*/
+#ifdef SQLITE_HAS_CODEC
+# define CODEC1(P,D,N,X,E) \
+    if( P->xCodec && P->xCodec(P->pCodec,D,N,X)==0 ){ E; }
+# define CODEC2(P,D,N,X,E,O) \
+    if( P->xCodec==0 ){ O=(char*)D; }else \
+    if( (O=(char*)(P->xCodec(P->pCodec,D,N,X)))==0 ){ E; }
+#else
+# define CODEC1(P,D,N,X,E)   /* NO-OP */
+# define CODEC2(P,D,N,X,E,O) O=(char*)D
+#endif
+
+/*
+** The maximum allowed sector size. 64KiB. If the xSectorsize() method 
+** returns a value larger than this, then MAX_SECTOR_SIZE is used instead.
+** This could conceivably cause corruption following a power failure on
+** such a system. This is currently an undocumented limit.
+*/
+#define MAX_SECTOR_SIZE 0x10000
+
+/*
+** An instance of the following structure is allocated for each active
+** savepoint and statement transaction in the system. All such structures
+** are stored in the Pager.aSavepoint[] array, which is allocated and
+** resized using sqlite3Realloc().
+**
+** When a savepoint is created, the PagerSavepoint.iHdrOffset field is
+** set to 0. If a journal-header is written into the main journal while
+** the savepoint is active, then iHdrOffset is set to the byte offset 
+** immediately following the last journal record written into the main
+** journal before the journal-header. This is required during savepoint
+** rollback (see pagerPlaybackSavepoint()).
+*/
+typedef struct PagerSavepoint PagerSavepoint;
+struct PagerSavepoint {
+  i64 iOffset;                 /* Starting offset in main journal */
+  i64 iHdrOffset;              /* See above */
+  Bitvec *pInSavepoint;        /* Set of pages in this savepoint */
+  Pgno nOrig;                  /* Original number of pages in file */
+  Pgno iSubRec;                /* Index of first record in sub-journal */
+#ifndef SQLITE_OMIT_WAL
+  u32 aWalData[WAL_SAVEPOINT_NDATA];        /* WAL savepoint context */
+#endif
+};
+
+/*
+** A open page cache is an instance of struct Pager. A description of
+** some of the more important member variables follows:
+**
+** eState
+**
+**   The current 'state' of the pager object. See the comment and state
+**   diagram above for a description of the pager state.
+**
+** eLock
+**
+**   For a real on-disk database, the current lock held on the database file -
+**   NO_LOCK, SHARED_LOCK, RESERVED_LOCK or EXCLUSIVE_LOCK.
+**
+**   For a temporary or in-memory database (neither of which require any
+**   locks), this variable is always set to EXCLUSIVE_LOCK. Since such
+**   databases always have Pager.exclusiveMode==1, this tricks the pager
+**   logic into thinking that it already has all the locks it will ever
+**   need (and no reason to release them).
+**
+**   In some (obscure) circumstances, this variable may also be set to
+**   UNKNOWN_LOCK. See the comment above the #define of UNKNOWN_LOCK for
+**   details.
+**
+** changeCountDone
+**
+**   This boolean variable is used to make sure that the change-counter 
+**   (the 4-byte header field at byte offset 24 of the database file) is 
+**   not updated more often than necessary. 
+**
+**   It is set to true when the change-counter field is updated, which 
+**   can only happen if an exclusive lock is held on the database file.
+**   It is cleared (set to false) whenever an exclusive lock is 
+**   relinquished on the database file. Each time a transaction is committed,
+**   The changeCountDone flag is inspected. If it is true, the work of
+**   updating the change-counter is omitted for the current transaction.
+**
+**   This mechanism means that when running in exclusive mode, a connection 
+**   need only update the change-counter once, for the first transaction
+**   committed.
+**
+** setMaster
+**
+**   When PagerCommitPhaseOne() is called to commit a transaction, it may
+**   (or may not) specify a master-journal name to be written into the 
+**   journal file before it is synced to disk.
+**
+**   Whether or not a journal file contains a master-journal pointer affects 
+**   the way in which the journal file is finalized after the transaction is 
+**   committed or rolled back when running in "journal_mode=PERSIST" mode.
+**   If a journal file does not contain a master-journal pointer, it is
+**   finalized by overwriting the first journal header with zeroes. If
+**   it does contain a master-journal pointer the journal file is finalized 
+**   by truncating it to zero bytes, just as if the connection were 
+**   running in "journal_mode=truncate" mode.
+**
+**   Journal files that contain master journal pointers cannot be finalized
+**   simply by overwriting the first journal-header with zeroes, as the
+**   master journal pointer could interfere with hot-journal rollback of any
+**   subsequently interrupted transaction that reuses the journal file.
+**
+**   The flag is cleared as soon as the journal file is finalized (either
+**   by PagerCommitPhaseTwo or PagerRollback). If an IO error prevents the
+**   journal file from being successfully finalized, the setMaster flag
+**   is cleared anyway (and the pager will move to ERROR state).
+**
+** doNotSpill, doNotSyncSpill
+**
+**   These two boolean variables control the behaviour of cache-spills
+**   (calls made by the pcache module to the pagerStress() routine to
+**   write cached data to the file-system in order to free up memory).
+**
+**   When doNotSpill is non-zero, writing to the database from pagerStress()
+**   is disabled altogether. This is done in a very obscure case that
+**   comes up during savepoint rollback that requires the pcache module
+**   to allocate a new page to prevent the journal file from being written
+**   while it is being traversed by code in pager_playback().
+** 
+**   If doNotSyncSpill is non-zero, writing to the database from pagerStress()
+**   is permitted, but syncing the journal file is not. This flag is set
+**   by sqlite3PagerWrite() when the file-system sector-size is larger than
+**   the database page-size in order to prevent a journal sync from happening 
+**   in between the journalling of two pages on the same sector. 
+**
+** subjInMemory
+**
+**   This is a boolean variable. If true, then any required sub-journal
+**   is opened as an in-memory journal file. If false, then in-memory
+**   sub-journals are only used for in-memory pager files.
+**
+**   This variable is updated by the upper layer each time a new 
+**   write-transaction is opened.
+**
+** dbSize, dbOrigSize, dbFileSize
+**
+**   Variable dbSize is set to the number of pages in the database file.
+**   It is valid in PAGER_READER and higher states (all states except for
+**   OPEN and ERROR). 
+**
+**   dbSize is set based on the size of the database file, which may be 
+**   larger than the size of the database (the value stored at offset
+**   28 of the database header by the btree). If the size of the file
+**   is not an integer multiple of the page-size, the value stored in
+**   dbSize is rounded down (i.e. a 5KB file with 2K page-size has dbSize==2).
+**   Except, any file that is greater than 0 bytes in size is considered
+**   to have at least one page. (i.e. a 1KB file with 2K page-size leads
+**   to dbSize==1).
+**
+**   During a write-transaction, if pages with page-numbers greater than
+**   dbSize are modified in the cache, dbSize is updated accordingly.
+**   Similarly, if the database is truncated using PagerTruncateImage(), 
+**   dbSize is updated.
+**
+**   Variables dbOrigSize and dbFileSize are valid in states 
+**   PAGER_WRITER_LOCKED and higher. dbOrigSize is a copy of the dbSize
+**   variable at the start of the transaction. It is used during rollback,
+**   and to determine whether or not pages need to be journalled before
+**   being modified.
+**
+**   Throughout a write-transaction, dbFileSize contains the size of
+**   the file on disk in pages. It is set to a copy of dbSize when the
+**   write-transaction is first opened, and updated when VFS calls are made
+**   to write or truncate the database file on disk. 
+**
+**   The only reason the dbFileSize variable is required is to suppress 
+**   unnecessary calls to xTruncate() after committing a transaction. If, 
+**   when a transaction is committed, the dbFileSize variable indicates 
+**   that the database file is larger than the database image (Pager.dbSize), 
+**   pager_truncate() is called. The pager_truncate() call uses xFilesize()
+**   to measure the database file on disk, and then truncates it if required.
+**   dbFileSize is not used when rolling back a transaction. In this case
+**   pager_truncate() is called unconditionally (which means there may be
+**   a call to xFilesize() that is not strictly required). In either case,
+**   pager_truncate() may cause the file to become smaller or larger.
+**
+** dbHintSize
+**
+**   The dbHintSize variable is used to limit the number of calls made to
+**   the VFS xFileControl(FCNTL_SIZE_HINT) method. 
+**
+**   dbHintSize is set to a copy of the dbSize variable when a
+**   write-transaction is opened (at the same time as dbFileSize and
+**   dbOrigSize). If the xFileControl(FCNTL_SIZE_HINT) method is called,
+**   dbHintSize is increased to the number of pages that correspond to the
+**   size-hint passed to the method call. See pager_write_pagelist() for 
+**   details.
+**
+** errCode
+**
+**   The Pager.errCode variable is only ever used in PAGER_ERROR state. It
+**   is set to zero in all other states. In PAGER_ERROR state, Pager.errCode 
+**   is always set to SQLITE_FULL, SQLITE_IOERR or one of the SQLITE_IOERR_XXX 
+**   sub-codes.
+*/
+struct Pager {
+  sqlite3_vfs *pVfs;          /* OS functions to use for IO */
+  u8 exclusiveMode;           /* Boolean. True if locking_mode==EXCLUSIVE */
+  u8 journalMode;             /* One of the PAGER_JOURNALMODE_* values */
+  u8 useJournal;              /* Use a rollback journal on this file */
+  u8 noReadlock;              /* Do not bother to obtain readlocks */
+  u8 noSync;                  /* Do not sync the journal if true */
+  u8 fullSync;                /* Do extra syncs of the journal for robustness */
+  u8 ckptSyncFlags;           /* SYNC_NORMAL or SYNC_FULL for checkpoint */
+  u8 syncFlags;               /* SYNC_NORMAL or SYNC_FULL otherwise */
+  u8 tempFile;                /* zFilename is a temporary file */
+  u8 readOnly;                /* True for a read-only database */
+  u8 memDb;                   /* True to inhibit all file I/O */
+
+  /**************************************************************************
+  ** The following block contains those class members that change during
+  ** routine opertion.  Class members not in this block are either fixed
+  ** when the pager is first created or else only change when there is a
+  ** significant mode change (such as changing the page_size, locking_mode,
+  ** or the journal_mode).  From another view, these class members describe
+  ** the "state" of the pager, while other class members describe the
+  ** "configuration" of the pager.
+  */
+  u8 eState;                  /* Pager state (OPEN, READER, WRITER_LOCKED..) */
+  u8 eLock;                   /* Current lock held on database file */
+  u8 changeCountDone;         /* Set after incrementing the change-counter */
+  u8 setMaster;               /* True if a m-j name has been written to jrnl */
+  u8 doNotSpill;              /* Do not spill the cache when non-zero */
+  u8 doNotSyncSpill;          /* Do not do a spill that requires jrnl sync */
+  u8 subjInMemory;            /* True to use in-memory sub-journals */
+  Pgno dbSize;                /* Number of pages in the database */
+  Pgno dbOrigSize;            /* dbSize before the current transaction */
+  Pgno dbFileSize;            /* Number of pages in the database file */
+  Pgno dbHintSize;            /* Value passed to FCNTL_SIZE_HINT call */
+  int errCode;                /* One of several kinds of errors */
+  int nRec;                   /* Pages journalled since last j-header written */
+  u32 cksumInit;              /* Quasi-random value added to every checksum */
+  u32 nSubRec;                /* Number of records written to sub-journal */
+  Bitvec *pInJournal;         /* One bit for each page in the database file */
+  sqlite3_file *fd;           /* File descriptor for database */
+  sqlite3_file *jfd;          /* File descriptor for main journal */
+  sqlite3_file *sjfd;         /* File descriptor for sub-journal */
+  i64 journalOff;             /* Current write offset in the journal file */
+  i64 journalHdr;             /* Byte offset to previous journal header */
+  sqlite3_backup *pBackup;    /* Pointer to list of ongoing backup processes */
+  PagerSavepoint *aSavepoint; /* Array of active savepoints */
+  int nSavepoint;             /* Number of elements in aSavepoint[] */
+  char dbFileVers[16];        /* Changes whenever database file changes */
+  /*
+  ** End of the routinely-changing class members
+  ***************************************************************************/
+
+  u16 nExtra;                 /* Add this many bytes to each in-memory page */
+  i16 nReserve;               /* Number of unused bytes at end of each page */
+  u32 vfsFlags;               /* Flags for sqlite3_vfs.xOpen() */
+  u32 sectorSize;             /* Assumed sector size during rollback */
+  int pageSize;               /* Number of bytes in a page */
+  Pgno mxPgno;                /* Maximum allowed size of the database */
+  i64 journalSizeLimit;       /* Size limit for persistent journal files */
+  char *zFilename;            /* Name of the database file */
+  char *zJournal;             /* Name of the journal file */
+  int (*xBusyHandler)(void*); /* Function to call when busy */
+  void *pBusyHandlerArg;      /* Context argument for xBusyHandler */
+#ifdef SQLITE_TEST
+  int nHit, nMiss;            /* Cache hits and missing */
+  int nRead, nWrite;          /* Database pages read/written */
+#endif
+  void (*xReiniter)(DbPage*); /* Call this routine when reloading pages */
+#ifdef SQLITE_HAS_CODEC
+  void *(*xCodec)(void*,void*,Pgno,int); /* Routine for en/decoding data */
+  void (*xCodecSizeChng)(void*,int,int); /* Notify of page size changes */
+  void (*xCodecFree)(void*);             /* Destructor for the codec */
+  void *pCodec;               /* First argument to xCodec... methods */
+#endif
+  char *pTmpSpace;            /* Pager.pageSize bytes of space for tmp use */
+  PCache *pPCache;            /* Pointer to page cache object */
+#ifndef SQLITE_OMIT_WAL
+  Wal *pWal;                  /* Write-ahead log used by "journal_mode=wal" */
+  char *zWal;                 /* File name for write-ahead log */
+#endif
+};
+
+/*
+** The following global variables hold counters used for
+** testing purposes only.  These variables do not exist in
+** a non-testing build.  These variables are not thread-safe.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_pager_readdb_count = 0;    /* Number of full pages read from DB */
+SQLITE_API int sqlite3_pager_writedb_count = 0;   /* Number of full pages written to DB */
+SQLITE_API int sqlite3_pager_writej_count = 0;    /* Number of pages written to journal */
+# define PAGER_INCR(v)  v++
+#else
+# define PAGER_INCR(v)
+#endif
+
+
+
+/*
+** Journal files begin with the following magic string.  The data
+** was obtained from /dev/random.  It is used only as a sanity check.
+**
+** Since version 2.8.0, the journal format contains additional sanity
+** checking information.  If the power fails while the journal is being
+** written, semi-random garbage data might appear in the journal
+** file after power is restored.  If an attempt is then made
+** to roll the journal back, the database could be corrupted.  The additional
+** sanity checking data is an attempt to discover the garbage in the
+** journal and ignore it.
+**
+** The sanity checking information for the new journal format consists
+** of a 32-bit checksum on each page of data.  The checksum covers both
+** the page number and the pPager->pageSize bytes of data for the page.
+** This cksum is initialized to a 32-bit random value that appears in the
+** journal file right after the header.  The random initializer is important,
+** because garbage data that appears at the end of a journal is likely
+** data that was once in other files that have now been deleted.  If the
+** garbage data came from an obsolete journal file, the checksums might
+** be correct.  But by initializing the checksum to random value which
+** is different for every journal, we minimize that risk.
+*/
+static const unsigned char aJournalMagic[] = {
+  0xd9, 0xd5, 0x05, 0xf9, 0x20, 0xa1, 0x63, 0xd7,
+};
+
+/*
+** The size of the of each page record in the journal is given by
+** the following macro.
+*/
+#define JOURNAL_PG_SZ(pPager)  ((pPager->pageSize) + 8)
+
+/*
+** The journal header size for this pager. This is usually the same 
+** size as a single disk sector. See also setSectorSize().
+*/
+#define JOURNAL_HDR_SZ(pPager) (pPager->sectorSize)
+
+/*
+** The macro MEMDB is true if we are dealing with an in-memory database.
+** We do this as a macro so that if the SQLITE_OMIT_MEMORYDB macro is set,
+** the value of MEMDB will be a constant and the compiler will optimize
+** out code that would never execute.
+*/
+#ifdef SQLITE_OMIT_MEMORYDB
+# define MEMDB 0
+#else
+# define MEMDB pPager->memDb
+#endif
+
+/*
+** The maximum legal page number is (2^31 - 1).
+*/
+#define PAGER_MAX_PGNO 2147483647
+
+/*
+** The argument to this macro is a file descriptor (type sqlite3_file*).
+** Return 0 if it is not open, or non-zero (but not 1) if it is.
+**
+** This is so that expressions can be written as:
+**
+**   if( isOpen(pPager->jfd) ){ ...
+**
+** instead of
+**
+**   if( pPager->jfd->pMethods ){ ...
+*/
+#define isOpen(pFd) ((pFd)->pMethods)
+
+/*
+** Return true if this pager uses a write-ahead log instead of the usual
+** rollback journal. Otherwise false.
+*/
+#ifndef SQLITE_OMIT_WAL
+static int pagerUseWal(Pager *pPager){
+  return (pPager->pWal!=0);
+}
+#else
+# define pagerUseWal(x) 0
+# define pagerRollbackWal(x) 0
+# define pagerWalFrames(v,w,x,y,z) 0
+# define pagerOpenWalIfPresent(z) SQLITE_OK
+# define pagerBeginReadTransaction(z) SQLITE_OK
+#endif
+
+#ifndef NDEBUG 
+/*
+** Usage:
+**
+**   assert( assert_pager_state(pPager) );
+**
+** This function runs many asserts to try to find inconsistencies in
+** the internal state of the Pager object.
+*/
+static int assert_pager_state(Pager *p){
+  Pager *pPager = p;
+
+  /* State must be valid. */
+  assert( p->eState==PAGER_OPEN
+       || p->eState==PAGER_READER
+       || p->eState==PAGER_WRITER_LOCKED
+       || p->eState==PAGER_WRITER_CACHEMOD
+       || p->eState==PAGER_WRITER_DBMOD
+       || p->eState==PAGER_WRITER_FINISHED
+       || p->eState==PAGER_ERROR
+  );
+
+  /* Regardless of the current state, a temp-file connection always behaves
+  ** as if it has an exclusive lock on the database file. It never updates
+  ** the change-counter field, so the changeCountDone flag is always set.
+  */
+  assert( p->tempFile==0 || p->eLock==EXCLUSIVE_LOCK );
+  assert( p->tempFile==0 || pPager->changeCountDone );
+
+  /* If the useJournal flag is clear, the journal-mode must be "OFF". 
+  ** And if the journal-mode is "OFF", the journal file must not be open.
+  */
+  assert( p->journalMode==PAGER_JOURNALMODE_OFF || p->useJournal );
+  assert( p->journalMode!=PAGER_JOURNALMODE_OFF || !isOpen(p->jfd) );
+
+  /* Check that MEMDB implies noSync. And an in-memory journal. Since 
+  ** this means an in-memory pager performs no IO at all, it cannot encounter 
+  ** either SQLITE_IOERR or SQLITE_FULL during rollback or while finalizing 
+  ** a journal file. (although the in-memory journal implementation may 
+  ** return SQLITE_IOERR_NOMEM while the journal file is being written). It 
+  ** is therefore not possible for an in-memory pager to enter the ERROR 
+  ** state.
+  */
+  if( MEMDB ){
+    assert( p->noSync );
+    assert( p->journalMode==PAGER_JOURNALMODE_OFF 
+         || p->journalMode==PAGER_JOURNALMODE_MEMORY 
+    );
+    assert( p->eState!=PAGER_ERROR && p->eState!=PAGER_OPEN );
+    assert( pagerUseWal(p)==0 );
+  }
+
+  /* If changeCountDone is set, a RESERVED lock or greater must be held
+  ** on the file.
+  */
+  assert( pPager->changeCountDone==0 || pPager->eLock>=RESERVED_LOCK );
+  assert( p->eLock!=PENDING_LOCK );
+
+  switch( p->eState ){
+    case PAGER_OPEN:
+      assert( !MEMDB );
+      assert( pPager->errCode==SQLITE_OK );
+      assert( sqlite3PcacheRefCount(pPager->pPCache)==0 || pPager->tempFile );
+      break;
+
+    case PAGER_READER:
+      assert( pPager->errCode==SQLITE_OK );
+      assert( p->eLock!=UNKNOWN_LOCK );
+      assert( p->eLock>=SHARED_LOCK || p->noReadlock );
+      break;
+
+    case PAGER_WRITER_LOCKED:
+      assert( p->eLock!=UNKNOWN_LOCK );
+      assert( pPager->errCode==SQLITE_OK );
+      if( !pagerUseWal(pPager) ){
+        assert( p->eLock>=RESERVED_LOCK );
+      }
+      assert( pPager->dbSize==pPager->dbOrigSize );
+      assert( pPager->dbOrigSize==pPager->dbFileSize );
+      assert( pPager->dbOrigSize==pPager->dbHintSize );
+      assert( pPager->setMaster==0 );
+      break;
+
+    case PAGER_WRITER_CACHEMOD:
+      assert( p->eLock!=UNKNOWN_LOCK );
+      assert( pPager->errCode==SQLITE_OK );
+      if( !pagerUseWal(pPager) ){
+        /* It is possible that if journal_mode=wal here that neither the
+        ** journal file nor the WAL file are open. This happens during
+        ** a rollback transaction that switches from journal_mode=off
+        ** to journal_mode=wal.
+        */
+        assert( p->eLock>=RESERVED_LOCK );
+        assert( isOpen(p->jfd) 
+             || p->journalMode==PAGER_JOURNALMODE_OFF 
+             || p->journalMode==PAGER_JOURNALMODE_WAL 
+        );
+      }
+      assert( pPager->dbOrigSize==pPager->dbFileSize );
+      assert( pPager->dbOrigSize==pPager->dbHintSize );
+      break;
+
+    case PAGER_WRITER_DBMOD:
+      assert( p->eLock==EXCLUSIVE_LOCK );
+      assert( pPager->errCode==SQLITE_OK );
+      assert( !pagerUseWal(pPager) );
+      assert( p->eLock>=EXCLUSIVE_LOCK );
+      assert( isOpen(p->jfd) 
+           || p->journalMode==PAGER_JOURNALMODE_OFF 
+           || p->journalMode==PAGER_JOURNALMODE_WAL 
+      );
+      assert( pPager->dbOrigSize<=pPager->dbHintSize );
+      break;
+
+    case PAGER_WRITER_FINISHED:
+      assert( p->eLock==EXCLUSIVE_LOCK );
+      assert( pPager->errCode==SQLITE_OK );
+      assert( !pagerUseWal(pPager) );
+      assert( isOpen(p->jfd) 
+           || p->journalMode==PAGER_JOURNALMODE_OFF 
+           || p->journalMode==PAGER_JOURNALMODE_WAL 
+      );
+      break;
+
+    case PAGER_ERROR:
+      /* There must be at least one outstanding reference to the pager if
+      ** in ERROR state. Otherwise the pager should have already dropped
+      ** back to OPEN state.
+      */
+      assert( pPager->errCode!=SQLITE_OK );
+      assert( sqlite3PcacheRefCount(pPager->pPCache)>0 );
+      break;
+  }
+
+  return 1;
+}
+#endif /* ifndef NDEBUG */
+
+#ifdef SQLITE_DEBUG 
+/*
+** Return a pointer to a human readable string in a static buffer
+** containing the state of the Pager object passed as an argument. This
+** is intended to be used within debuggers. For example, as an alternative
+** to "print *pPager" in gdb:
+**
+** (gdb) printf "%s", print_pager_state(pPager)
+*/
+static char *print_pager_state(Pager *p){
+  static char zRet[1024];
+
+  sqlite3_snprintf(1024, zRet,
+      "Filename:      %s\n"
+      "State:         %s errCode=%d\n"
+      "Lock:          %s\n"
+      "Locking mode:  locking_mode=%s\n"
+      "Journal mode:  journal_mode=%s\n"
+      "Backing store: tempFile=%d memDb=%d useJournal=%d\n"
+      "Journal:       journalOff=%lld journalHdr=%lld\n"
+      "Size:          dbsize=%d dbOrigSize=%d dbFileSize=%d\n"
+      , p->zFilename
+      , p->eState==PAGER_OPEN            ? "OPEN" :
+        p->eState==PAGER_READER          ? "READER" :
+        p->eState==PAGER_WRITER_LOCKED   ? "WRITER_LOCKED" :
+        p->eState==PAGER_WRITER_CACHEMOD ? "WRITER_CACHEMOD" :
+        p->eState==PAGER_WRITER_DBMOD    ? "WRITER_DBMOD" :
+        p->eState==PAGER_WRITER_FINISHED ? "WRITER_FINISHED" :
+        p->eState==PAGER_ERROR           ? "ERROR" : "?error?"
+      , (int)p->errCode
+      , p->eLock==NO_LOCK         ? "NO_LOCK" :
+        p->eLock==RESERVED_LOCK   ? "RESERVED" :
+        p->eLock==EXCLUSIVE_LOCK  ? "EXCLUSIVE" :
+        p->eLock==SHARED_LOCK     ? "SHARED" :
+        p->eLock==UNKNOWN_LOCK    ? "UNKNOWN" : "?error?"
+      , p->exclusiveMode ? "exclusive" : "normal"
+      , p->journalMode==PAGER_JOURNALMODE_MEMORY   ? "memory" :
+        p->journalMode==PAGER_JOURNALMODE_OFF      ? "off" :
+        p->journalMode==PAGER_JOURNALMODE_DELETE   ? "delete" :
+        p->journalMode==PAGER_JOURNALMODE_PERSIST  ? "persist" :
+        p->journalMode==PAGER_JOURNALMODE_TRUNCATE ? "truncate" :
+        p->journalMode==PAGER_JOURNALMODE_WAL      ? "wal" : "?error?"
+      , (int)p->tempFile, (int)p->memDb, (int)p->useJournal
+      , p->journalOff, p->journalHdr
+      , (int)p->dbSize, (int)p->dbOrigSize, (int)p->dbFileSize
+  );
+
+  return zRet;
+}
+#endif
+
+/*
+** Return true if it is necessary to write page *pPg into the sub-journal.
+** A page needs to be written into the sub-journal if there exists one
+** or more open savepoints for which:
+**
+**   * The page-number is less than or equal to PagerSavepoint.nOrig, and
+**   * The bit corresponding to the page-number is not set in
+**     PagerSavepoint.pInSavepoint.
+*/
+static int subjRequiresPage(PgHdr *pPg){
+  Pgno pgno = pPg->pgno;
+  Pager *pPager = pPg->pPager;
+  int i;
+  for(i=0; i<pPager->nSavepoint; i++){
+    PagerSavepoint *p = &pPager->aSavepoint[i];
+    if( p->nOrig>=pgno && 0==sqlite3BitvecTest(p->pInSavepoint, pgno) ){
+      return 1;
+    }
+  }
+  return 0;
+}
+
+/*
+** Return true if the page is already in the journal file.
+*/
+static int pageInJournal(PgHdr *pPg){
+  return sqlite3BitvecTest(pPg->pPager->pInJournal, pPg->pgno);
+}
+
+/*
+** Read a 32-bit integer from the given file descriptor.  Store the integer
+** that is read in *pRes.  Return SQLITE_OK if everything worked, or an
+** error code is something goes wrong.
+**
+** All values are stored on disk as big-endian.
+*/
+static int read32bits(sqlite3_file *fd, i64 offset, u32 *pRes){
+  unsigned char ac[4];
+  int rc = sqlite3OsRead(fd, ac, sizeof(ac), offset);
+  if( rc==SQLITE_OK ){
+    *pRes = sqlite3Get4byte(ac);
+  }
+  return rc;
+}
+
+/*
+** Write a 32-bit integer into a string buffer in big-endian byte order.
+*/
+#define put32bits(A,B)  sqlite3Put4byte((u8*)A,B)
+
+
+/*
+** Write a 32-bit integer into the given file descriptor.  Return SQLITE_OK
+** on success or an error code is something goes wrong.
+*/
+static int write32bits(sqlite3_file *fd, i64 offset, u32 val){
+  char ac[4];
+  put32bits(ac, val);
+  return sqlite3OsWrite(fd, ac, 4, offset);
+}
+
+/*
+** Unlock the database file to level eLock, which must be either NO_LOCK
+** or SHARED_LOCK. Regardless of whether or not the call to xUnlock()
+** succeeds, set the Pager.eLock variable to match the (attempted) new lock.
+**
+** Except, if Pager.eLock is set to UNKNOWN_LOCK when this function is
+** called, do not modify it. See the comment above the #define of 
+** UNKNOWN_LOCK for an explanation of this.
+*/
+static int pagerUnlockDb(Pager *pPager, int eLock){
+  int rc = SQLITE_OK;
+
+  assert( !pPager->exclusiveMode || pPager->eLock==eLock );
+  assert( eLock==NO_LOCK || eLock==SHARED_LOCK );
+  assert( eLock!=NO_LOCK || pagerUseWal(pPager)==0 );
+  if( isOpen(pPager->fd) ){
+    assert( pPager->eLock>=eLock );
+    rc = sqlite3OsUnlock(pPager->fd, eLock);
+    if( pPager->eLock!=UNKNOWN_LOCK ){
+      pPager->eLock = (u8)eLock;
+    }
+    IOTRACE(("UNLOCK %p %d\n", pPager, eLock))
+  }
+  return rc;
+}
+
+/*
+** Lock the database file to level eLock, which must be either SHARED_LOCK,
+** RESERVED_LOCK or EXCLUSIVE_LOCK. If the caller is successful, set the
+** Pager.eLock variable to the new locking state. 
+**
+** Except, if Pager.eLock is set to UNKNOWN_LOCK when this function is 
+** called, do not modify it unless the new locking state is EXCLUSIVE_LOCK. 
+** See the comment above the #define of UNKNOWN_LOCK for an explanation 
+** of this.
+*/
+static int pagerLockDb(Pager *pPager, int eLock){
+  int rc = SQLITE_OK;
+
+  assert( eLock==SHARED_LOCK || eLock==RESERVED_LOCK || eLock==EXCLUSIVE_LOCK );
+  if( pPager->eLock<eLock || pPager->eLock==UNKNOWN_LOCK ){
+    rc = sqlite3OsLock(pPager->fd, eLock);
+    if( rc==SQLITE_OK && (pPager->eLock!=UNKNOWN_LOCK||eLock==EXCLUSIVE_LOCK) ){
+      pPager->eLock = (u8)eLock;
+      IOTRACE(("LOCK %p %d\n", pPager, eLock))
+    }
+  }
+  return rc;
+}
+
+/*
+** This function determines whether or not the atomic-write optimization
+** can be used with this pager. The optimization can be used if:
+**
+**  (a) the value returned by OsDeviceCharacteristics() indicates that
+**      a database page may be written atomically, and
+**  (b) the value returned by OsSectorSize() is less than or equal
+**      to the page size.
+**
+** The optimization is also always enabled for temporary files. It is
+** an error to call this function if pPager is opened on an in-memory
+** database.
+**
+** If the optimization cannot be used, 0 is returned. If it can be used,
+** then the value returned is the size of the journal file when it
+** contains rollback data for exactly one page.
+*/
+#ifdef SQLITE_ENABLE_ATOMIC_WRITE
+static int jrnlBufferSize(Pager *pPager){
+  assert( !MEMDB );
+  if( !pPager->tempFile ){
+    int dc;                           /* Device characteristics */
+    int nSector;                      /* Sector size */
+    int szPage;                       /* Page size */
+
+    assert( isOpen(pPager->fd) );
+    dc = sqlite3OsDeviceCharacteristics(pPager->fd);
+    nSector = pPager->sectorSize;
+    szPage = pPager->pageSize;
+
+    assert(SQLITE_IOCAP_ATOMIC512==(512>>8));
+    assert(SQLITE_IOCAP_ATOMIC64K==(65536>>8));
+    if( 0==(dc&(SQLITE_IOCAP_ATOMIC|(szPage>>8)) || nSector>szPage) ){
+      return 0;
+    }
+  }
+
+  return JOURNAL_HDR_SZ(pPager) + JOURNAL_PG_SZ(pPager);
+}
+#endif
+
+/*
+** If SQLITE_CHECK_PAGES is defined then we do some sanity checking
+** on the cache using a hash function.  This is used for testing
+** and debugging only.
+*/
+#ifdef SQLITE_CHECK_PAGES
+/*
+** Return a 32-bit hash of the page data for pPage.
+*/
+static u32 pager_datahash(int nByte, unsigned char *pData){
+  u32 hash = 0;
+  int i;
+  for(i=0; i<nByte; i++){
+    hash = (hash*1039) + pData[i];
+  }
+  return hash;
+}
+static u32 pager_pagehash(PgHdr *pPage){
+  return pager_datahash(pPage->pPager->pageSize, (unsigned char *)pPage->pData);
+}
+static void pager_set_pagehash(PgHdr *pPage){
+  pPage->pageHash = pager_pagehash(pPage);
+}
+
+/*
+** The CHECK_PAGE macro takes a PgHdr* as an argument. If SQLITE_CHECK_PAGES
+** is defined, and NDEBUG is not defined, an assert() statement checks
+** that the page is either dirty or still matches the calculated page-hash.
+*/
+#define CHECK_PAGE(x) checkPage(x)
+static void checkPage(PgHdr *pPg){
+  Pager *pPager = pPg->pPager;
+  assert( pPager->eState!=PAGER_ERROR );
+  assert( (pPg->flags&PGHDR_DIRTY) || pPg->pageHash==pager_pagehash(pPg) );
+}
+
+#else
+#define pager_datahash(X,Y)  0
+#define pager_pagehash(X)  0
+#define pager_set_pagehash(X)
+#define CHECK_PAGE(x)
+#endif  /* SQLITE_CHECK_PAGES */
+
+/*
+** When this is called the journal file for pager pPager must be open.
+** This function attempts to read a master journal file name from the 
+** end of the file and, if successful, copies it into memory supplied 
+** by the caller. See comments above writeMasterJournal() for the format
+** used to store a master journal file name at the end of a journal file.
+**
+** zMaster must point to a buffer of at least nMaster bytes allocated by
+** the caller. This should be sqlite3_vfs.mxPathname+1 (to ensure there is
+** enough space to write the master journal name). If the master journal
+** name in the journal is longer than nMaster bytes (including a
+** nul-terminator), then this is handled as if no master journal name
+** were present in the journal.
+**
+** If a master journal file name is present at the end of the journal
+** file, then it is copied into the buffer pointed to by zMaster. A
+** nul-terminator byte is appended to the buffer following the master
+** journal file name.
+**
+** If it is determined that no master journal file name is present 
+** zMaster[0] is set to 0 and SQLITE_OK returned.
+**
+** If an error occurs while reading from the journal file, an SQLite
+** error code is returned.
+*/
+static int readMasterJournal(sqlite3_file *pJrnl, char *zMaster, u32 nMaster){
+  int rc;                    /* Return code */
+  u32 len;                   /* Length in bytes of master journal name */
+  i64 szJ;                   /* Total size in bytes of journal file pJrnl */
+  u32 cksum;                 /* MJ checksum value read from journal */
+  u32 u;                     /* Unsigned loop counter */
+  unsigned char aMagic[8];   /* A buffer to hold the magic header */
+  zMaster[0] = '\0';
+
+  if( SQLITE_OK!=(rc = sqlite3OsFileSize(pJrnl, &szJ))
+   || szJ<16
+   || SQLITE_OK!=(rc = read32bits(pJrnl, szJ-16, &len))
+   || len>=nMaster 
+   || SQLITE_OK!=(rc = read32bits(pJrnl, szJ-12, &cksum))
+   || SQLITE_OK!=(rc = sqlite3OsRead(pJrnl, aMagic, 8, szJ-8))
+   || memcmp(aMagic, aJournalMagic, 8)
+   || SQLITE_OK!=(rc = sqlite3OsRead(pJrnl, zMaster, len, szJ-16-len))
+  ){
+    return rc;
+  }
+
+  /* See if the checksum matches the master journal name */
+  for(u=0; u<len; u++){
+    cksum -= zMaster[u];
+  }
+  if( cksum ){
+    /* If the checksum doesn't add up, then one or more of the disk sectors
+    ** containing the master journal filename is corrupted. This means
+    ** definitely roll back, so just return SQLITE_OK and report a (nul)
+    ** master-journal filename.
+    */
+    len = 0;
+  }
+  zMaster[len] = '\0';
+   
+  return SQLITE_OK;
+}
+
+/*
+** Return the offset of the sector boundary at or immediately 
+** following the value in pPager->journalOff, assuming a sector 
+** size of pPager->sectorSize bytes.
+**
+** i.e for a sector size of 512:
+**
+**   Pager.journalOff          Return value
+**   ---------------------------------------
+**   0                         0
+**   512                       512
+**   100                       512
+**   2000                      2048
+** 
+*/
+static i64 journalHdrOffset(Pager *pPager){
+  i64 offset = 0;
+  i64 c = pPager->journalOff;
+  if( c ){
+    offset = ((c-1)/JOURNAL_HDR_SZ(pPager) + 1) * JOURNAL_HDR_SZ(pPager);
+  }
+  assert( offset%JOURNAL_HDR_SZ(pPager)==0 );
+  assert( offset>=c );
+  assert( (offset-c)<JOURNAL_HDR_SZ(pPager) );
+  return offset;
+}
+
+/*
+** The journal file must be open when this function is called.
+**
+** This function is a no-op if the journal file has not been written to
+** within the current transaction (i.e. if Pager.journalOff==0).
+**
+** If doTruncate is non-zero or the Pager.journalSizeLimit variable is
+** set to 0, then truncate the journal file to zero bytes in size. Otherwise,
+** zero the 28-byte header at the start of the journal file. In either case, 
+** if the pager is not in no-sync mode, sync the journal file immediately 
+** after writing or truncating it.
+**
+** If Pager.journalSizeLimit is set to a positive, non-zero value, and
+** following the truncation or zeroing described above the size of the 
+** journal file in bytes is larger than this value, then truncate the
+** journal file to Pager.journalSizeLimit bytes. The journal file does
+** not need to be synced following this operation.
+**
+** If an IO error occurs, abandon processing and return the IO error code.
+** Otherwise, return SQLITE_OK.
+*/
+static int zeroJournalHdr(Pager *pPager, int doTruncate){
+  int rc = SQLITE_OK;                               /* Return code */
+  assert( isOpen(pPager->jfd) );
+  if( pPager->journalOff ){
+    const i64 iLimit = pPager->journalSizeLimit;    /* Local cache of jsl */
+
+    IOTRACE(("JZEROHDR %p\n", pPager))
+    if( doTruncate || iLimit==0 ){
+      rc = sqlite3OsTruncate(pPager->jfd, 0);
+    }else{
+      static const char zeroHdr[28] = {0};
+      rc = sqlite3OsWrite(pPager->jfd, zeroHdr, sizeof(zeroHdr), 0);
+    }
+    if( rc==SQLITE_OK && !pPager->noSync ){
+      rc = sqlite3OsSync(pPager->jfd, SQLITE_SYNC_DATAONLY|pPager->syncFlags);
+    }
+
+    /* At this point the transaction is committed but the write lock 
+    ** is still held on the file. If there is a size limit configured for 
+    ** the persistent journal and the journal file currently consumes more
+    ** space than that limit allows for, truncate it now. There is no need
+    ** to sync the file following this operation.
+    */
+    if( rc==SQLITE_OK && iLimit>0 ){
+      i64 sz;
+      rc = sqlite3OsFileSize(pPager->jfd, &sz);
+      if( rc==SQLITE_OK && sz>iLimit ){
+        rc = sqlite3OsTruncate(pPager->jfd, iLimit);
+      }
+    }
+  }
+  return rc;
+}
+
+/*
+** The journal file must be open when this routine is called. A journal
+** header (JOURNAL_HDR_SZ bytes) is written into the journal file at the
+** current location.
+**
+** The format for the journal header is as follows:
+** - 8 bytes: Magic identifying journal format.
+** - 4 bytes: Number of records in journal, or -1 no-sync mode is on.
+** - 4 bytes: Random number used for page hash.
+** - 4 bytes: Initial database page count.
+** - 4 bytes: Sector size used by the process that wrote this journal.
+** - 4 bytes: Database page size.
+** 
+** Followed by (JOURNAL_HDR_SZ - 28) bytes of unused space.
+*/
+static int writeJournalHdr(Pager *pPager){
+  int rc = SQLITE_OK;                 /* Return code */
+  char *zHeader = pPager->pTmpSpace;  /* Temporary space used to build header */
+  u32 nHeader = (u32)pPager->pageSize;/* Size of buffer pointed to by zHeader */
+  u32 nWrite;                         /* Bytes of header sector written */
+  int ii;                             /* Loop counter */
+
+  assert( isOpen(pPager->jfd) );      /* Journal file must be open. */
+
+  if( nHeader>JOURNAL_HDR_SZ(pPager) ){
+    nHeader = JOURNAL_HDR_SZ(pPager);
+  }
+
+  /* If there are active savepoints and any of them were created 
+  ** since the most recent journal header was written, update the 
+  ** PagerSavepoint.iHdrOffset fields now.
+  */
+  for(ii=0; ii<pPager->nSavepoint; ii++){
+    if( pPager->aSavepoint[ii].iHdrOffset==0 ){
+      pPager->aSavepoint[ii].iHdrOffset = pPager->journalOff;
+    }
+  }
+
+  pPager->journalHdr = pPager->journalOff = journalHdrOffset(pPager);
+
+  /* 
+  ** Write the nRec Field - the number of page records that follow this
+  ** journal header. Normally, zero is written to this value at this time.
+  ** After the records are added to the journal (and the journal synced, 
+  ** if in full-sync mode), the zero is overwritten with the true number
+  ** of records (see syncJournal()).
+  **
+  ** A faster alternative is to write 0xFFFFFFFF to the nRec field. When
+  ** reading the journal this value tells SQLite to assume that the
+  ** rest of the journal file contains valid page records. This assumption
+  ** is dangerous, as if a failure occurred whilst writing to the journal
+  ** file it may contain some garbage data. There are two scenarios
+  ** where this risk can be ignored:
+  **
+  **   * When the pager is in no-sync mode. Corruption can follow a
+  **     power failure in this case anyway.
+  **
+  **   * When the SQLITE_IOCAP_SAFE_APPEND flag is set. This guarantees
+  **     that garbage data is never appended to the journal file.
+  */
+  assert( isOpen(pPager->fd) || pPager->noSync );
+  if( pPager->noSync || (pPager->journalMode==PAGER_JOURNALMODE_MEMORY)
+   || (sqlite3OsDeviceCharacteristics(pPager->fd)&SQLITE_IOCAP_SAFE_APPEND) 
+  ){
+    memcpy(zHeader, aJournalMagic, sizeof(aJournalMagic));
+    put32bits(&zHeader[sizeof(aJournalMagic)], 0xffffffff);
+  }else{
+    memset(zHeader, 0, sizeof(aJournalMagic)+4);
+  }
+
+  /* The random check-hash initialiser */ 
+  sqlite3_randomness(sizeof(pPager->cksumInit), &pPager->cksumInit);
+  put32bits(&zHeader[sizeof(aJournalMagic)+4], pPager->cksumInit);
+  /* The initial database size */
+  put32bits(&zHeader[sizeof(aJournalMagic)+8], pPager->dbOrigSize);
+  /* The assumed sector size for this process */
+  put32bits(&zHeader[sizeof(aJournalMagic)+12], pPager->sectorSize);
+
+  /* The page size */
+  put32bits(&zHeader[sizeof(aJournalMagic)+16], pPager->pageSize);
+
+  /* Initializing the tail of the buffer is not necessary.  Everything
+  ** works find if the following memset() is omitted.  But initializing
+  ** the memory prevents valgrind from complaining, so we are willing to
+  ** take the performance hit.
+  */
+  memset(&zHeader[sizeof(aJournalMagic)+20], 0,
+         nHeader-(sizeof(aJournalMagic)+20));
+
+  /* In theory, it is only necessary to write the 28 bytes that the 
+  ** journal header consumes to the journal file here. Then increment the 
+  ** Pager.journalOff variable by JOURNAL_HDR_SZ so that the next 
+  ** record is written to the following sector (leaving a gap in the file
+  ** that will be implicitly filled in by the OS).
+  **
+  ** However it has been discovered that on some systems this pattern can 
+  ** be significantly slower than contiguously writing data to the file,
+  ** even if that means explicitly writing data to the block of 
+  ** (JOURNAL_HDR_SZ - 28) bytes that will not be used. So that is what
+  ** is done. 
+  **
+  ** The loop is required here in case the sector-size is larger than the 
+  ** database page size. Since the zHeader buffer is only Pager.pageSize
+  ** bytes in size, more than one call to sqlite3OsWrite() may be required
+  ** to populate the entire journal header sector.
+  */ 
+  for(nWrite=0; rc==SQLITE_OK&&nWrite<JOURNAL_HDR_SZ(pPager); nWrite+=nHeader){
+    IOTRACE(("JHDR %p %lld %d\n", pPager, pPager->journalHdr, nHeader))
+    rc = sqlite3OsWrite(pPager->jfd, zHeader, nHeader, pPager->journalOff);
+    assert( pPager->journalHdr <= pPager->journalOff );
+    pPager->journalOff += nHeader;
+  }
+
+  return rc;
+}
+
+/*
+** The journal file must be open when this is called. A journal header file
+** (JOURNAL_HDR_SZ bytes) is read from the current location in the journal
+** file. The current location in the journal file is given by
+** pPager->journalOff. See comments above function writeJournalHdr() for
+** a description of the journal header format.
+**
+** If the header is read successfully, *pNRec is set to the number of
+** page records following this header and *pDbSize is set to the size of the
+** database before the transaction began, in pages. Also, pPager->cksumInit
+** is set to the value read from the journal header. SQLITE_OK is returned
+** in this case.
+**
+** If the journal header file appears to be corrupted, SQLITE_DONE is
+** returned and *pNRec and *PDbSize are undefined.  If JOURNAL_HDR_SZ bytes
+** cannot be read from the journal file an error code is returned.
+*/
+static int readJournalHdr(
+  Pager *pPager,               /* Pager object */
+  int isHot,
+  i64 journalSize,             /* Size of the open journal file in bytes */
+  u32 *pNRec,                  /* OUT: Value read from the nRec field */
+  u32 *pDbSize                 /* OUT: Value of original database size field */
+){
+  int rc;                      /* Return code */
+  unsigned char aMagic[8];     /* A buffer to hold the magic header */
+  i64 iHdrOff;                 /* Offset of journal header being read */
+
+  assert( isOpen(pPager->jfd) );      /* Journal file must be open. */
+
+  /* Advance Pager.journalOff to the start of the next sector. If the
+  ** journal file is too small for there to be a header stored at this
+  ** point, return SQLITE_DONE.
+  */
+  pPager->journalOff = journalHdrOffset(pPager);
+  if( pPager->journalOff+JOURNAL_HDR_SZ(pPager) > journalSize ){
+    return SQLITE_DONE;
+  }
+  iHdrOff = pPager->journalOff;
+
+  /* Read in the first 8 bytes of the journal header. If they do not match
+  ** the  magic string found at the start of each journal header, return
+  ** SQLITE_DONE. If an IO error occurs, return an error code. Otherwise,
+  ** proceed.
+  */
+  if( isHot || iHdrOff!=pPager->journalHdr ){
+    rc = sqlite3OsRead(pPager->jfd, aMagic, sizeof(aMagic), iHdrOff);
+    if( rc ){
+      return rc;
+    }
+    if( memcmp(aMagic, aJournalMagic, sizeof(aMagic))!=0 ){
+      return SQLITE_DONE;
+    }
+  }
+
+  /* Read the first three 32-bit fields of the journal header: The nRec
+  ** field, the checksum-initializer and the database size at the start
+  ** of the transaction. Return an error code if anything goes wrong.
+  */
+  if( SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+8, pNRec))
+   || SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+12, &pPager->cksumInit))
+   || SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+16, pDbSize))
+  ){
+    return rc;
+  }
+
+  if( pPager->journalOff==0 ){
+    u32 iPageSize;               /* Page-size field of journal header */
+    u32 iSectorSize;             /* Sector-size field of journal header */
+
+    /* Read the page-size and sector-size journal header fields. */
+    if( SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+20, &iSectorSize))
+     || SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+24, &iPageSize))
+    ){
+      return rc;
+    }
+
+    /* Versions of SQLite prior to 3.5.8 set the page-size field of the
+    ** journal header to zero. In this case, assume that the Pager.pageSize
+    ** variable is already set to the correct page size.
+    */
+    if( iPageSize==0 ){
+      iPageSize = pPager->pageSize;
+    }
+
+    /* Check that the values read from the page-size and sector-size fields
+    ** are within range. To be 'in range', both values need to be a power
+    ** of two greater than or equal to 512 or 32, and not greater than their 
+    ** respective compile time maximum limits.
+    */
+    if( iPageSize<512                  || iSectorSize<32
+     || iPageSize>SQLITE_MAX_PAGE_SIZE || iSectorSize>MAX_SECTOR_SIZE
+     || ((iPageSize-1)&iPageSize)!=0   || ((iSectorSize-1)&iSectorSize)!=0 
+    ){
+      /* If the either the page-size or sector-size in the journal-header is 
+      ** invalid, then the process that wrote the journal-header must have 
+      ** crashed before the header was synced. In this case stop reading 
+      ** the journal file here.
+      */
+      return SQLITE_DONE;
+    }
+
+    /* Update the page-size to match the value read from the journal. 
+    ** Use a testcase() macro to make sure that malloc failure within 
+    ** PagerSetPagesize() is tested.
+    */
+    rc = sqlite3PagerSetPagesize(pPager, &iPageSize, -1);
+    testcase( rc!=SQLITE_OK );
+
+    /* Update the assumed sector-size to match the value used by 
+    ** the process that created this journal. If this journal was
+    ** created by a process other than this one, then this routine
+    ** is being called from within pager_playback(). The local value
+    ** of Pager.sectorSize is restored at the end of that routine.
+    */
+    pPager->sectorSize = iSectorSize;
+  }
+
+  pPager->journalOff += JOURNAL_HDR_SZ(pPager);
+  return rc;
+}
+
+
+/*
+** Write the supplied master journal name into the journal file for pager
+** pPager at the current location. The master journal name must be the last
+** thing written to a journal file. If the pager is in full-sync mode, the
+** journal file descriptor is advanced to the next sector boundary before
+** anything is written. The format is:
+**
+**   + 4 bytes: PAGER_MJ_PGNO.
+**   + N bytes: Master journal filename in utf-8.
+**   + 4 bytes: N (length of master journal name in bytes, no nul-terminator).
+**   + 4 bytes: Master journal name checksum.
+**   + 8 bytes: aJournalMagic[].
+**
+** The master journal page checksum is the sum of the bytes in the master
+** journal name, where each byte is interpreted as a signed 8-bit integer.
+**
+** If zMaster is a NULL pointer (occurs for a single database transaction), 
+** this call is a no-op.
+*/
+static int writeMasterJournal(Pager *pPager, const char *zMaster){
+  int rc;                          /* Return code */
+  int nMaster;                     /* Length of string zMaster */
+  i64 iHdrOff;                     /* Offset of header in journal file */
+  i64 jrnlSize;                    /* Size of journal file on disk */
+  u32 cksum = 0;                   /* Checksum of string zMaster */
+
+  assert( pPager->setMaster==0 );
+  assert( !pagerUseWal(pPager) );
+
+  if( !zMaster 
+   || pPager->journalMode==PAGER_JOURNALMODE_MEMORY 
+   || pPager->journalMode==PAGER_JOURNALMODE_OFF 
+  ){
+    return SQLITE_OK;
+  }
+  pPager->setMaster = 1;
+  assert( isOpen(pPager->jfd) );
+  assert( pPager->journalHdr <= pPager->journalOff );
+
+  /* Calculate the length in bytes and the checksum of zMaster */
+  for(nMaster=0; zMaster[nMaster]; nMaster++){
+    cksum += zMaster[nMaster];
+  }
+
+  /* If in full-sync mode, advance to the next disk sector before writing
+  ** the master journal name. This is in case the previous page written to
+  ** the journal has already been synced.
+  */
+  if( pPager->fullSync ){
+    pPager->journalOff = journalHdrOffset(pPager);
+  }
+  iHdrOff = pPager->journalOff;
+
+  /* Write the master journal data to the end of the journal file. If
+  ** an error occurs, return the error code to the caller.
+  */
+  if( (0 != (rc = write32bits(pPager->jfd, iHdrOff, PAGER_MJ_PGNO(pPager))))
+   || (0 != (rc = sqlite3OsWrite(pPager->jfd, zMaster, nMaster, iHdrOff+4)))
+   || (0 != (rc = write32bits(pPager->jfd, iHdrOff+4+nMaster, nMaster)))
+   || (0 != (rc = write32bits(pPager->jfd, iHdrOff+4+nMaster+4, cksum)))
+   || (0 != (rc = sqlite3OsWrite(pPager->jfd, aJournalMagic, 8, iHdrOff+4+nMaster+8)))
+  ){
+    return rc;
+  }
+  pPager->journalOff += (nMaster+20);
+
+  /* If the pager is in peristent-journal mode, then the physical 
+  ** journal-file may extend past the end of the master-journal name
+  ** and 8 bytes of magic data just written to the file. This is 
+  ** dangerous because the code to rollback a hot-journal file
+  ** will not be able to find the master-journal name to determine 
+  ** whether or not the journal is hot. 
+  **
+  ** Easiest thing to do in this scenario is to truncate the journal 
+  ** file to the required size.
+  */ 
+  if( SQLITE_OK==(rc = sqlite3OsFileSize(pPager->jfd, &jrnlSize))
+   && jrnlSize>pPager->journalOff
+  ){
+    rc = sqlite3OsTruncate(pPager->jfd, pPager->journalOff);
+  }
+  return rc;
+}
+
+/*
+** Find a page in the hash table given its page number. Return
+** a pointer to the page or NULL if the requested page is not 
+** already in memory.
+*/
+static PgHdr *pager_lookup(Pager *pPager, Pgno pgno){
+  PgHdr *p;                         /* Return value */
+
+  /* It is not possible for a call to PcacheFetch() with createFlag==0 to
+  ** fail, since no attempt to allocate dynamic memory will be made.
+  */
+  (void)sqlite3PcacheFetch(pPager->pPCache, pgno, 0, &p);
+  return p;
+}
+
+/*
+** Discard the entire contents of the in-memory page-cache.
+*/
+static void pager_reset(Pager *pPager){
+  sqlite3BackupRestart(pPager->pBackup);
+  sqlite3PcacheClear(pPager->pPCache);
+}
+
+/*
+** Free all structures in the Pager.aSavepoint[] array and set both
+** Pager.aSavepoint and Pager.nSavepoint to zero. Close the sub-journal
+** if it is open and the pager is not in exclusive mode.
+*/
+static void releaseAllSavepoints(Pager *pPager){
+  int ii;               /* Iterator for looping through Pager.aSavepoint */
+  for(ii=0; ii<pPager->nSavepoint; ii++){
+    sqlite3BitvecDestroy(pPager->aSavepoint[ii].pInSavepoint);
+  }
+  if( !pPager->exclusiveMode || sqlite3IsMemJournal(pPager->sjfd) ){
+    sqlite3OsClose(pPager->sjfd);
+  }
+  sqlite3_free(pPager->aSavepoint);
+  pPager->aSavepoint = 0;
+  pPager->nSavepoint = 0;
+  pPager->nSubRec = 0;
+}
+
+/*
+** Set the bit number pgno in the PagerSavepoint.pInSavepoint 
+** bitvecs of all open savepoints. Return SQLITE_OK if successful
+** or SQLITE_NOMEM if a malloc failure occurs.
+*/
+static int addToSavepointBitvecs(Pager *pPager, Pgno pgno){
+  int ii;                   /* Loop counter */
+  int rc = SQLITE_OK;       /* Result code */
+
+  for(ii=0; ii<pPager->nSavepoint; ii++){
+    PagerSavepoint *p = &pPager->aSavepoint[ii];
+    if( pgno<=p->nOrig ){
+      rc |= sqlite3BitvecSet(p->pInSavepoint, pgno);
+      testcase( rc==SQLITE_NOMEM );
+      assert( rc==SQLITE_OK || rc==SQLITE_NOMEM );
+    }
+  }
+  return rc;
+}
+
+/*
+** This function is a no-op if the pager is in exclusive mode and not
+** in the ERROR state. Otherwise, it switches the pager to PAGER_OPEN
+** state.
+**
+** If the pager is not in exclusive-access mode, the database file is
+** completely unlocked. If the file is unlocked and the file-system does
+** not exhibit the UNDELETABLE_WHEN_OPEN property, the journal file is
+** closed (if it is open).
+**
+** If the pager is in ERROR state when this function is called, the 
+** contents of the pager cache are discarded before switching back to 
+** the OPEN state. Regardless of whether the pager is in exclusive-mode
+** or not, any journal file left in the file-system will be treated
+** as a hot-journal and rolled back the next time a read-transaction
+** is opened (by this or by any other connection).
+*/
+static void pager_unlock(Pager *pPager){
+
+  assert( pPager->eState==PAGER_READER 
+       || pPager->eState==PAGER_OPEN 
+       || pPager->eState==PAGER_ERROR 
+  );
+
+  sqlite3BitvecDestroy(pPager->pInJournal);
+  pPager->pInJournal = 0;
+  releaseAllSavepoints(pPager);
+
+  if( pagerUseWal(pPager) ){
+    assert( !isOpen(pPager->jfd) );
+    sqlite3WalEndReadTransaction(pPager->pWal);
+    pPager->eState = PAGER_OPEN;
+  }else if( !pPager->exclusiveMode ){
+    int rc;                       /* Error code returned by pagerUnlockDb() */
+    int iDc = isOpen(pPager->fd)?sqlite3OsDeviceCharacteristics(pPager->fd):0;
+
+    /* If the operating system support deletion of open files, then
+    ** close the journal file when dropping the database lock.  Otherwise
+    ** another connection with journal_mode=delete might delete the file
+    ** out from under us.
+    */
+    assert( (PAGER_JOURNALMODE_MEMORY   & 5)!=1 );
+    assert( (PAGER_JOURNALMODE_OFF      & 5)!=1 );
+    assert( (PAGER_JOURNALMODE_WAL      & 5)!=1 );
+    assert( (PAGER_JOURNALMODE_DELETE   & 5)!=1 );
+    assert( (PAGER_JOURNALMODE_TRUNCATE & 5)==1 );
+    assert( (PAGER_JOURNALMODE_PERSIST  & 5)==1 );
+    if( 0==(iDc & SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN)
+     || 1!=(pPager->journalMode & 5)
+    ){
+      sqlite3OsClose(pPager->jfd);
+    }
+
+    /* If the pager is in the ERROR state and the call to unlock the database
+    ** file fails, set the current lock to UNKNOWN_LOCK. See the comment
+    ** above the #define for UNKNOWN_LOCK for an explanation of why this
+    ** is necessary.
+    */
+    rc = pagerUnlockDb(pPager, NO_LOCK);
+    if( rc!=SQLITE_OK && pPager->eState==PAGER_ERROR ){
+      pPager->eLock = UNKNOWN_LOCK;
+    }
+
+    /* The pager state may be changed from PAGER_ERROR to PAGER_OPEN here
+    ** without clearing the error code. This is intentional - the error
+    ** code is cleared and the cache reset in the block below.
+    */
+    assert( pPager->errCode || pPager->eState!=PAGER_ERROR );
+    pPager->changeCountDone = 0;
+    pPager->eState = PAGER_OPEN;
+  }
+
+  /* If Pager.errCode is set, the contents of the pager cache cannot be
+  ** trusted. Now that there are no outstanding references to the pager,
+  ** it can safely move back to PAGER_OPEN state. This happens in both
+  ** normal and exclusive-locking mode.
+  */
+  if( pPager->errCode ){
+    assert( !MEMDB );
+    pager_reset(pPager);
+    pPager->changeCountDone = pPager->tempFile;
+    pPager->eState = PAGER_OPEN;
+    pPager->errCode = SQLITE_OK;
+  }
+
+  pPager->journalOff = 0;
+  pPager->journalHdr = 0;
+  pPager->setMaster = 0;
+}
+
+/*
+** This function is called whenever an IOERR or FULL error that requires
+** the pager to transition into the ERROR state may ahve occurred.
+** The first argument is a pointer to the pager structure, the second 
+** the error-code about to be returned by a pager API function. The 
+** value returned is a copy of the second argument to this function. 
+**
+** If the second argument is SQLITE_FULL, SQLITE_IOERR or one of the
+** IOERR sub-codes, the pager enters the ERROR state and the error code
+** is stored in Pager.errCode. While the pager remains in the ERROR state,
+** all major API calls on the Pager will immediately return Pager.errCode.
+**
+** The ERROR state indicates that the contents of the pager-cache 
+** cannot be trusted. This state can be cleared by completely discarding 
+** the contents of the pager-cache. If a transaction was active when
+** the persistent error occurred, then the rollback journal may need
+** to be replayed to restore the contents of the database file (as if
+** it were a hot-journal).
+*/
+static int pager_error(Pager *pPager, int rc){
+  int rc2 = rc & 0xff;
+  assert( rc==SQLITE_OK || !MEMDB );
+  assert(
+       pPager->errCode==SQLITE_FULL ||
+       pPager->errCode==SQLITE_OK ||
+       (pPager->errCode & 0xff)==SQLITE_IOERR
+  );
+  if( rc2==SQLITE_FULL || rc2==SQLITE_IOERR ){
+    pPager->errCode = rc;
+    pPager->eState = PAGER_ERROR;
+  }
+  return rc;
+}
+
+/*
+** This routine ends a transaction. A transaction is usually ended by 
+** either a COMMIT or a ROLLBACK operation. This routine may be called 
+** after rollback of a hot-journal, or if an error occurs while opening
+** the journal file or writing the very first journal-header of a
+** database transaction.
+** 
+** This routine is never called in PAGER_ERROR state. If it is called
+** in PAGER_NONE or PAGER_SHARED state and the lock held is less
+** exclusive than a RESERVED lock, it is a no-op.
+**
+** Otherwise, any active savepoints are released.
+**
+** If the journal file is open, then it is "finalized". Once a journal 
+** file has been finalized it is not possible to use it to roll back a 
+** transaction. Nor will it be considered to be a hot-journal by this
+** or any other database connection. Exactly how a journal is finalized
+** depends on whether or not the pager is running in exclusive mode and
+** the current journal-mode (Pager.journalMode value), as follows:
+**
+**   journalMode==MEMORY
+**     Journal file descriptor is simply closed. This destroys an 
+**     in-memory journal.
+**
+**   journalMode==TRUNCATE
+**     Journal file is truncated to zero bytes in size.
+**
+**   journalMode==PERSIST
+**     The first 28 bytes of the journal file are zeroed. This invalidates
+**     the first journal header in the file, and hence the entire journal
+**     file. An invalid journal file cannot be rolled back.
+**
+**   journalMode==DELETE
+**     The journal file is closed and deleted using sqlite3OsDelete().
+**
+**     If the pager is running in exclusive mode, this method of finalizing
+**     the journal file is never used. Instead, if the journalMode is
+**     DELETE and the pager is in exclusive mode, the method described under
+**     journalMode==PERSIST is used instead.
+**
+** After the journal is finalized, the pager moves to PAGER_READER state.
+** If running in non-exclusive rollback mode, the lock on the file is 
+** downgraded to a SHARED_LOCK.
+**
+** SQLITE_OK is returned if no error occurs. If an error occurs during
+** any of the IO operations to finalize the journal file or unlock the
+** database then the IO error code is returned to the user. If the 
+** operation to finalize the journal file fails, then the code still
+** tries to unlock the database file if not in exclusive mode. If the
+** unlock operation fails as well, then the first error code related
+** to the first error encountered (the journal finalization one) is
+** returned.
+*/
+static int pager_end_transaction(Pager *pPager, int hasMaster){
+  int rc = SQLITE_OK;      /* Error code from journal finalization operation */
+  int rc2 = SQLITE_OK;     /* Error code from db file unlock operation */
+
+  /* Do nothing if the pager does not have an open write transaction
+  ** or at least a RESERVED lock. This function may be called when there
+  ** is no write-transaction active but a RESERVED or greater lock is
+  ** held under two circumstances:
+  **
+  **   1. After a successful hot-journal rollback, it is called with
+  **      eState==PAGER_NONE and eLock==EXCLUSIVE_LOCK.
+  **
+  **   2. If a connection with locking_mode=exclusive holding an EXCLUSIVE 
+  **      lock switches back to locking_mode=normal and then executes a
+  **      read-transaction, this function is called with eState==PAGER_READER 
+  **      and eLock==EXCLUSIVE_LOCK when the read-transaction is closed.
+  */
+  assert( assert_pager_state(pPager) );
+  assert( pPager->eState!=PAGER_ERROR );
+  if( pPager->eState<PAGER_WRITER_LOCKED && pPager->eLock<RESERVED_LOCK ){
+    return SQLITE_OK;
+  }
+
+  releaseAllSavepoints(pPager);
+  assert( isOpen(pPager->jfd) || pPager->pInJournal==0 );
+  if( isOpen(pPager->jfd) ){
+    assert( !pagerUseWal(pPager) );
+
+    /* Finalize the journal file. */
+    if( sqlite3IsMemJournal(pPager->jfd) ){
+      assert( pPager->journalMode==PAGER_JOURNALMODE_MEMORY );
+      sqlite3OsClose(pPager->jfd);
+    }else if( pPager->journalMode==PAGER_JOURNALMODE_TRUNCATE ){
+      if( pPager->journalOff==0 ){
+        rc = SQLITE_OK;
+      }else{
+        rc = sqlite3OsTruncate(pPager->jfd, 0);
+      }
+      pPager->journalOff = 0;
+    }else if( pPager->journalMode==PAGER_JOURNALMODE_PERSIST
+      || (pPager->exclusiveMode && pPager->journalMode!=PAGER_JOURNALMODE_WAL)
+    ){
+      rc = zeroJournalHdr(pPager, hasMaster);
+      pPager->journalOff = 0;
+    }else{
+      /* This branch may be executed with Pager.journalMode==MEMORY if
+      ** a hot-journal was just rolled back. In this case the journal
+      ** file should be closed and deleted. If this connection writes to
+      ** the database file, it will do so using an in-memory journal. 
+      */
+      assert( pPager->journalMode==PAGER_JOURNALMODE_DELETE 
+           || pPager->journalMode==PAGER_JOURNALMODE_MEMORY 
+           || pPager->journalMode==PAGER_JOURNALMODE_WAL 
+      );
+      sqlite3OsClose(pPager->jfd);
+      if( !pPager->tempFile ){
+        rc = sqlite3OsDelete(pPager->pVfs, pPager->zJournal, 0);
+      }
+    }
+  }
+
+#ifdef SQLITE_CHECK_PAGES
+  sqlite3PcacheIterateDirty(pPager->pPCache, pager_set_pagehash);
+  if( pPager->dbSize==0 && sqlite3PcacheRefCount(pPager->pPCache)>0 ){
+    PgHdr *p = pager_lookup(pPager, 1);
+    if( p ){
+      p->pageHash = 0;
+      sqlite3PagerUnref(p);
+    }
+  }
+#endif
+
+  sqlite3BitvecDestroy(pPager->pInJournal);
+  pPager->pInJournal = 0;
+  pPager->nRec = 0;
+  sqlite3PcacheCleanAll(pPager->pPCache);
+  sqlite3PcacheTruncate(pPager->pPCache, pPager->dbSize);
+
+  if( pagerUseWal(pPager) ){
+    /* Drop the WAL write-lock, if any. Also, if the connection was in 
+    ** locking_mode=exclusive mode but is no longer, drop the EXCLUSIVE 
+    ** lock held on the database file.
+    */
+    rc2 = sqlite3WalEndWriteTransaction(pPager->pWal);
+    assert( rc2==SQLITE_OK );
+  }
+  if( !pPager->exclusiveMode 
+   && (!pagerUseWal(pPager) || sqlite3WalExclusiveMode(pPager->pWal, 0))
+  ){
+    rc2 = pagerUnlockDb(pPager, SHARED_LOCK);
+    pPager->changeCountDone = 0;
+  }
+  pPager->eState = PAGER_READER;
+  pPager->setMaster = 0;
+
+  return (rc==SQLITE_OK?rc2:rc);
+}
+
+/*
+** Execute a rollback if a transaction is active and unlock the 
+** database file. 
+**
+** If the pager has already entered the ERROR state, do not attempt 
+** the rollback at this time. Instead, pager_unlock() is called. The
+** call to pager_unlock() will discard all in-memory pages, unlock
+** the database file and move the pager back to OPEN state. If this 
+** means that there is a hot-journal left in the file-system, the next 
+** connection to obtain a shared lock on the pager (which may be this one) 
+** will roll it back.
+**
+** If the pager has not already entered the ERROR state, but an IO or
+** malloc error occurs during a rollback, then this will itself cause 
+** the pager to enter the ERROR state. Which will be cleared by the
+** call to pager_unlock(), as described above.
+*/
+static void pagerUnlockAndRollback(Pager *pPager){
+  if( pPager->eState!=PAGER_ERROR && pPager->eState!=PAGER_OPEN ){
+    assert( assert_pager_state(pPager) );
+    if( pPager->eState>=PAGER_WRITER_LOCKED ){
+      sqlite3BeginBenignMalloc();
+      sqlite3PagerRollback(pPager);
+      sqlite3EndBenignMalloc();
+    }else if( !pPager->exclusiveMode ){
+      assert( pPager->eState==PAGER_READER );
+      pager_end_transaction(pPager, 0);
+    }
+  }
+  pager_unlock(pPager);
+}
+
+/*
+** Parameter aData must point to a buffer of pPager->pageSize bytes
+** of data. Compute and return a checksum based ont the contents of the 
+** page of data and the current value of pPager->cksumInit.
+**
+** This is not a real checksum. It is really just the sum of the 
+** random initial value (pPager->cksumInit) and every 200th byte
+** of the page data, starting with byte offset (pPager->pageSize%200).
+** Each byte is interpreted as an 8-bit unsigned integer.
+**
+** Changing the formula used to compute this checksum results in an
+** incompatible journal file format.
+**
+** If journal corruption occurs due to a power failure, the most likely 
+** scenario is that one end or the other of the record will be changed. 
+** It is much less likely that the two ends of the journal record will be
+** correct and the middle be corrupt.  Thus, this "checksum" scheme,
+** though fast and simple, catches the mostly likely kind of corruption.
+*/
+static u32 pager_cksum(Pager *pPager, const u8 *aData){
+  u32 cksum = pPager->cksumInit;         /* Checksum value to return */
+  int i = pPager->pageSize-200;          /* Loop counter */
+  while( i>0 ){
+    cksum += aData[i];
+    i -= 200;
+  }
+  return cksum;
+}
+
+/*
+** Report the current page size and number of reserved bytes back
+** to the codec.
+*/
+#ifdef SQLITE_HAS_CODEC
+static void pagerReportSize(Pager *pPager){
+  if( pPager->xCodecSizeChng ){
+    pPager->xCodecSizeChng(pPager->pCodec, pPager->pageSize,
+                           (int)pPager->nReserve);
+  }
+}
+#else
+# define pagerReportSize(X)     /* No-op if we do not support a codec */
+#endif
+
+/*
+** Read a single page from either the journal file (if isMainJrnl==1) or
+** from the sub-journal (if isMainJrnl==0) and playback that page.
+** The page begins at offset *pOffset into the file. The *pOffset
+** value is increased to the start of the next page in the journal.
+**
+** The main rollback journal uses checksums - the statement journal does 
+** not.
+**
+** If the page number of the page record read from the (sub-)journal file
+** is greater than the current value of Pager.dbSize, then playback is
+** skipped and SQLITE_OK is returned.
+**
+** If pDone is not NULL, then it is a record of pages that have already
+** been played back.  If the page at *pOffset has already been played back
+** (if the corresponding pDone bit is set) then skip the playback.
+** Make sure the pDone bit corresponding to the *pOffset page is set
+** prior to returning.
+**
+** If the page record is successfully read from the (sub-)journal file
+** and played back, then SQLITE_OK is returned. If an IO error occurs
+** while reading the record from the (sub-)journal file or while writing
+** to the database file, then the IO error code is returned. If data
+** is successfully read from the (sub-)journal file but appears to be
+** corrupted, SQLITE_DONE is returned. Data is considered corrupted in
+** two circumstances:
+** 
+**   * If the record page-number is illegal (0 or PAGER_MJ_PGNO), or
+**   * If the record is being rolled back from the main journal file
+**     and the checksum field does not match the record content.
+**
+** Neither of these two scenarios are possible during a savepoint rollback.
+**
+** If this is a savepoint rollback, then memory may have to be dynamically
+** allocated by this function. If this is the case and an allocation fails,
+** SQLITE_NOMEM is returned.
+*/
+static int pager_playback_one_page(
+  Pager *pPager,                /* The pager being played back */
+  i64 *pOffset,                 /* Offset of record to playback */
+  Bitvec *pDone,                /* Bitvec of pages already played back */
+  int isMainJrnl,               /* 1 -> main journal. 0 -> sub-journal. */
+  int isSavepnt                 /* True for a savepoint rollback */
+){
+  int rc;
+  PgHdr *pPg;                   /* An existing page in the cache */
+  Pgno pgno;                    /* The page number of a page in journal */
+  u32 cksum;                    /* Checksum used for sanity checking */
+  char *aData;                  /* Temporary storage for the page */
+  sqlite3_file *jfd;            /* The file descriptor for the journal file */
+  int isSynced;                 /* True if journal page is synced */
+
+  assert( (isMainJrnl&~1)==0 );      /* isMainJrnl is 0 or 1 */
+  assert( (isSavepnt&~1)==0 );       /* isSavepnt is 0 or 1 */
+  assert( isMainJrnl || pDone );     /* pDone always used on sub-journals */
+  assert( isSavepnt || pDone==0 );   /* pDone never used on non-savepoint */
+
+  aData = pPager->pTmpSpace;
+  assert( aData );         /* Temp storage must have already been allocated */
+  assert( pagerUseWal(pPager)==0 || (!isMainJrnl && isSavepnt) );
+
+  /* Either the state is greater than PAGER_WRITER_CACHEMOD (a transaction 
+  ** or savepoint rollback done at the request of the caller) or this is
+  ** a hot-journal rollback. If it is a hot-journal rollback, the pager
+  ** is in state OPEN and holds an EXCLUSIVE lock. Hot-journal rollback
+  ** only reads from the main journal, not the sub-journal.
+  */
+  assert( pPager->eState>=PAGER_WRITER_CACHEMOD
+       || (pPager->eState==PAGER_OPEN && pPager->eLock==EXCLUSIVE_LOCK)
+  );
+  assert( pPager->eState>=PAGER_WRITER_CACHEMOD || isMainJrnl );
+
+  /* Read the page number and page data from the journal or sub-journal
+  ** file. Return an error code to the caller if an IO error occurs.
+  */
+  jfd = isMainJrnl ? pPager->jfd : pPager->sjfd;
+  rc = read32bits(jfd, *pOffset, &pgno);
+  if( rc!=SQLITE_OK ) return rc;
+  rc = sqlite3OsRead(jfd, (u8*)aData, pPager->pageSize, (*pOffset)+4);
+  if( rc!=SQLITE_OK ) return rc;
+  *pOffset += pPager->pageSize + 4 + isMainJrnl*4;
+
+  /* Sanity checking on the page.  This is more important that I originally
+  ** thought.  If a power failure occurs while the journal is being written,
+  ** it could cause invalid data to be written into the journal.  We need to
+  ** detect this invalid data (with high probability) and ignore it.
+  */
+  if( pgno==0 || pgno==PAGER_MJ_PGNO(pPager) ){
+    assert( !isSavepnt );
+    return SQLITE_DONE;
+  }
+  if( pgno>(Pgno)pPager->dbSize || sqlite3BitvecTest(pDone, pgno) ){
+    return SQLITE_OK;
+  }
+  if( isMainJrnl ){
+    rc = read32bits(jfd, (*pOffset)-4, &cksum);
+    if( rc ) return rc;
+    if( !isSavepnt && pager_cksum(pPager, (u8*)aData)!=cksum ){
+      return SQLITE_DONE;
+    }
+  }
+
+  /* If this page has already been played by before during the current
+  ** rollback, then don't bother to play it back again.
+  */
+  if( pDone && (rc = sqlite3BitvecSet(pDone, pgno))!=SQLITE_OK ){
+    return rc;
+  }
+
+  /* When playing back page 1, restore the nReserve setting
+  */
+  if( pgno==1 && pPager->nReserve!=((u8*)aData)[20] ){
+    pPager->nReserve = ((u8*)aData)[20];
+    pagerReportSize(pPager);
+  }
+
+  /* If the pager is in CACHEMOD state, then there must be a copy of this
+  ** page in the pager cache. In this case just update the pager cache,
+  ** not the database file. The page is left marked dirty in this case.
+  **
+  ** An exception to the above rule: If the database is in no-sync mode
+  ** and a page is moved during an incremental vacuum then the page may
+  ** not be in the pager cache. Later: if a malloc() or IO error occurs
+  ** during a Movepage() call, then the page may not be in the cache
+  ** either. So the condition described in the above paragraph is not
+  ** assert()able.
+  **
+  ** If in WRITER_DBMOD, WRITER_FINISHED or OPEN state, then we update the
+  ** pager cache if it exists and the main file. The page is then marked 
+  ** not dirty. Since this code is only executed in PAGER_OPEN state for
+  ** a hot-journal rollback, it is guaranteed that the page-cache is empty
+  ** if the pager is in OPEN state.
+  **
+  ** Ticket #1171:  The statement journal might contain page content that is
+  ** different from the page content at the start of the transaction.
+  ** This occurs when a page is changed prior to the start of a statement
+  ** then changed again within the statement.  When rolling back such a
+  ** statement we must not write to the original database unless we know
+  ** for certain that original page contents are synced into the main rollback
+  ** journal.  Otherwise, a power loss might leave modified data in the
+  ** database file without an entry in the rollback journal that can
+  ** restore the database to its original form.  Two conditions must be
+  ** met before writing to the database files. (1) the database must be
+  ** locked.  (2) we know that the original page content is fully synced
+  ** in the main journal either because the page is not in cache or else
+  ** the page is marked as needSync==0.
+  **
+  ** 2008-04-14:  When attempting to vacuum a corrupt database file, it
+  ** is possible to fail a statement on a database that does not yet exist.
+  ** Do not attempt to write if database file has never been opened.
+  */
+  if( pagerUseWal(pPager) ){
+    pPg = 0;
+  }else{
+    pPg = pager_lookup(pPager, pgno);
+  }
+  assert( pPg || !MEMDB );
+  assert( pPager->eState!=PAGER_OPEN || pPg==0 );
+  PAGERTRACE(("PLAYBACK %d page %d hash(%08x) %s\n",
+           PAGERID(pPager), pgno, pager_datahash(pPager->pageSize, (u8*)aData),
+           (isMainJrnl?"main-journal":"sub-journal")
+  ));
+  if( isMainJrnl ){
+    isSynced = pPager->noSync || (*pOffset <= pPager->journalHdr);
+  }else{
+    isSynced = (pPg==0 || 0==(pPg->flags & PGHDR_NEED_SYNC));
+  }
+  if( isOpen(pPager->fd)
+   && (pPager->eState>=PAGER_WRITER_DBMOD || pPager->eState==PAGER_OPEN)
+   && isSynced
+  ){
+    i64 ofst = (pgno-1)*(i64)pPager->pageSize;
+    testcase( !isSavepnt && pPg!=0 && (pPg->flags&PGHDR_NEED_SYNC)!=0 );
+    assert( !pagerUseWal(pPager) );
+    rc = sqlite3OsWrite(pPager->fd, (u8*)aData, pPager->pageSize, ofst);
+    if( pgno>pPager->dbFileSize ){
+      pPager->dbFileSize = pgno;
+    }
+    if( pPager->pBackup ){
+      CODEC1(pPager, aData, pgno, 3, rc=SQLITE_NOMEM);
+      sqlite3BackupUpdate(pPager->pBackup, pgno, (u8*)aData);
+      CODEC2(pPager, aData, pgno, 7, rc=SQLITE_NOMEM, aData);
+    }
+  }else if( !isMainJrnl && pPg==0 ){
+    /* If this is a rollback of a savepoint and data was not written to
+    ** the database and the page is not in-memory, there is a potential
+    ** problem. When the page is next fetched by the b-tree layer, it 
+    ** will be read from the database file, which may or may not be 
+    ** current. 
+    **
+    ** There are a couple of different ways this can happen. All are quite
+    ** obscure. When running in synchronous mode, this can only happen 
+    ** if the page is on the free-list at the start of the transaction, then
+    ** populated, then moved using sqlite3PagerMovepage().
+    **
+    ** The solution is to add an in-memory page to the cache containing
+    ** the data just read from the sub-journal. Mark the page as dirty 
+    ** and if the pager requires a journal-sync, then mark the page as 
+    ** requiring a journal-sync before it is written.
+    */
+    assert( isSavepnt );
+    assert( pPager->doNotSpill==0 );
+    pPager->doNotSpill++;
+    rc = sqlite3PagerAcquire(pPager, pgno, &pPg, 1);
+    assert( pPager->doNotSpill==1 );
+    pPager->doNotSpill--;
+    if( rc!=SQLITE_OK ) return rc;
+    pPg->flags &= ~PGHDR_NEED_READ;
+    sqlite3PcacheMakeDirty(pPg);
+  }
+  if( pPg ){
+    /* No page should ever be explicitly rolled back that is in use, except
+    ** for page 1 which is held in use in order to keep the lock on the
+    ** database active. However such a page may be rolled back as a result
+    ** of an internal error resulting in an automatic call to
+    ** sqlite3PagerRollback().
+    */
+    void *pData;
+    pData = pPg->pData;
+    memcpy(pData, (u8*)aData, pPager->pageSize);
+    pPager->xReiniter(pPg);
+    if( isMainJrnl && (!isSavepnt || *pOffset<=pPager->journalHdr) ){
+      /* If the contents of this page were just restored from the main 
+      ** journal file, then its content must be as they were when the 
+      ** transaction was first opened. In this case we can mark the page
+      ** as clean, since there will be no need to write it out to the
+      ** database.
+      **
+      ** There is one exception to this rule. If the page is being rolled
+      ** back as part of a savepoint (or statement) rollback from an 
+      ** unsynced portion of the main journal file, then it is not safe
+      ** to mark the page as clean. This is because marking the page as
+      ** clean will clear the PGHDR_NEED_SYNC flag. Since the page is
+      ** already in the journal file (recorded in Pager.pInJournal) and
+      ** the PGHDR_NEED_SYNC flag is cleared, if the page is written to
+      ** again within this transaction, it will be marked as dirty but
+      ** the PGHDR_NEED_SYNC flag will not be set. It could then potentially
+      ** be written out into the database file before its journal file
+      ** segment is synced. If a crash occurs during or following this,
+      ** database corruption may ensue.
+      */
+      assert( !pagerUseWal(pPager) );
+      sqlite3PcacheMakeClean(pPg);
+    }
+    pager_set_pagehash(pPg);
+
+    /* If this was page 1, then restore the value of Pager.dbFileVers.
+    ** Do this before any decoding. */
+    if( pgno==1 ){
+      memcpy(&pPager->dbFileVers, &((u8*)pData)[24],sizeof(pPager->dbFileVers));
+    }
+
+    /* Decode the page just read from disk */
+    CODEC1(pPager, pData, pPg->pgno, 3, rc=SQLITE_NOMEM);
+    sqlite3PcacheRelease(pPg);
+  }
+  return rc;
+}
+
+/*
+** Parameter zMaster is the name of a master journal file. A single journal
+** file that referred to the master journal file has just been rolled back.
+** This routine checks if it is possible to delete the master journal file,
+** and does so if it is.
+**
+** Argument zMaster may point to Pager.pTmpSpace. So that buffer is not 
+** available for use within this function.
+**
+** When a master journal file is created, it is populated with the names 
+** of all of its child journals, one after another, formatted as utf-8 
+** encoded text. The end of each child journal file is marked with a 
+** nul-terminator byte (0x00). i.e. the entire contents of a master journal
+** file for a transaction involving two databases might be:
+**
+**   "/home/bill/a.db-journal\x00/home/bill/b.db-journal\x00"
+**
+** A master journal file may only be deleted once all of its child 
+** journals have been rolled back.
+**
+** This function reads the contents of the master-journal file into 
+** memory and loops through each of the child journal names. For
+** each child journal, it checks if:
+**
+**   * if the child journal exists, and if so
+**   * if the child journal contains a reference to master journal 
+**     file zMaster
+**
+** If a child journal can be found that matches both of the criteria
+** above, this function returns without doing anything. Otherwise, if
+** no such child journal can be found, file zMaster is deleted from
+** the file-system using sqlite3OsDelete().
+**
+** If an IO error within this function, an error code is returned. This
+** function allocates memory by calling sqlite3Malloc(). If an allocation
+** fails, SQLITE_NOMEM is returned. Otherwise, if no IO or malloc errors 
+** occur, SQLITE_OK is returned.
+**
+** TODO: This function allocates a single block of memory to load
+** the entire contents of the master journal file. This could be
+** a couple of kilobytes or so - potentially larger than the page 
+** size.
+*/
+static int pager_delmaster(Pager *pPager, const char *zMaster){
+  sqlite3_vfs *pVfs = pPager->pVfs;
+  int rc;                   /* Return code */
+  sqlite3_file *pMaster;    /* Malloc'd master-journal file descriptor */
+  sqlite3_file *pJournal;   /* Malloc'd child-journal file descriptor */
+  char *zMasterJournal = 0; /* Contents of master journal file */
+  i64 nMasterJournal;       /* Size of master journal file */
+  char *zJournal;           /* Pointer to one journal within MJ file */
+  char *zMasterPtr;         /* Space to hold MJ filename from a journal file */
+  int nMasterPtr;           /* Amount of space allocated to zMasterPtr[] */
+
+  /* Allocate space for both the pJournal and pMaster file descriptors.
+  ** If successful, open the master journal file for reading.
+  */
+  pMaster = (sqlite3_file *)sqlite3MallocZero(pVfs->szOsFile * 2);
+  pJournal = (sqlite3_file *)(((u8 *)pMaster) + pVfs->szOsFile);
+  if( !pMaster ){
+    rc = SQLITE_NOMEM;
+  }else{
+    const int flags = (SQLITE_OPEN_READONLY|SQLITE_OPEN_MASTER_JOURNAL);
+    rc = sqlite3OsOpen(pVfs, zMaster, pMaster, flags, 0);
+  }
+  if( rc!=SQLITE_OK ) goto delmaster_out;
+
+  /* Load the entire master journal file into space obtained from
+  ** sqlite3_malloc() and pointed to by zMasterJournal.   Also obtain
+  ** sufficient space (in zMasterPtr) to hold the names of master
+  ** journal files extracted from regular rollback-journals.
+  */
+  rc = sqlite3OsFileSize(pMaster, &nMasterJournal);
+  if( rc!=SQLITE_OK ) goto delmaster_out;
+  nMasterPtr = pVfs->mxPathname+1;
+  zMasterJournal = sqlite3Malloc((int)nMasterJournal + nMasterPtr + 1);
+  if( !zMasterJournal ){
+    rc = SQLITE_NOMEM;
+    goto delmaster_out;
+  }
+  zMasterPtr = &zMasterJournal[nMasterJournal+1];
+  rc = sqlite3OsRead(pMaster, zMasterJournal, (int)nMasterJournal, 0);
+  if( rc!=SQLITE_OK ) goto delmaster_out;
+  zMasterJournal[nMasterJournal] = 0;
+
+  zJournal = zMasterJournal;
+  while( (zJournal-zMasterJournal)<nMasterJournal ){
+    int exists;
+    rc = sqlite3OsAccess(pVfs, zJournal, SQLITE_ACCESS_EXISTS, &exists);
+    if( rc!=SQLITE_OK ){
+      goto delmaster_out;
+    }
+    if( exists ){
+      /* One of the journals pointed to by the master journal exists.
+      ** Open it and check if it points at the master journal. If
+      ** so, return without deleting the master journal file.
+      */
+      int c;
+      int flags = (SQLITE_OPEN_READONLY|SQLITE_OPEN_MAIN_JOURNAL);
+      rc = sqlite3OsOpen(pVfs, zJournal, pJournal, flags, 0);
+      if( rc!=SQLITE_OK ){
+        goto delmaster_out;
+      }
+
+      rc = readMasterJournal(pJournal, zMasterPtr, nMasterPtr);
+      sqlite3OsClose(pJournal);
+      if( rc!=SQLITE_OK ){
+        goto delmaster_out;
+      }
+
+      c = zMasterPtr[0]!=0 && strcmp(zMasterPtr, zMaster)==0;
+      if( c ){
+        /* We have a match. Do not delete the master journal file. */
+        goto delmaster_out;
+      }
+    }
+    zJournal += (sqlite3Strlen30(zJournal)+1);
+  }
+ 
+  sqlite3OsClose(pMaster);
+  rc = sqlite3OsDelete(pVfs, zMaster, 0);
+
+delmaster_out:
+  sqlite3_free(zMasterJournal);
+  if( pMaster ){
+    sqlite3OsClose(pMaster);
+    assert( !isOpen(pJournal) );
+    sqlite3_free(pMaster);
+  }
+  return rc;
+}
+
+
+/*
+** This function is used to change the actual size of the database 
+** file in the file-system. This only happens when committing a transaction,
+** or rolling back a transaction (including rolling back a hot-journal).
+**
+** If the main database file is not open, or the pager is not in either
+** DBMOD or OPEN state, this function is a no-op. Otherwise, the size 
+** of the file is changed to nPage pages (nPage*pPager->pageSize bytes). 
+** If the file on disk is currently larger than nPage pages, then use the VFS
+** xTruncate() method to truncate it.
+**
+** Or, it might might be the case that the file on disk is smaller than 
+** nPage pages. Some operating system implementations can get confused if 
+** you try to truncate a file to some size that is larger than it 
+** currently is, so detect this case and write a single zero byte to 
+** the end of the new file instead.
+**
+** If successful, return SQLITE_OK. If an IO error occurs while modifying
+** the database file, return the error code to the caller.
+*/
+static int pager_truncate(Pager *pPager, Pgno nPage){
+  int rc = SQLITE_OK;
+  assert( pPager->eState!=PAGER_ERROR );
+  assert( pPager->eState!=PAGER_READER );
+  
+  if( isOpen(pPager->fd) 
+   && (pPager->eState>=PAGER_WRITER_DBMOD || pPager->eState==PAGER_OPEN) 
+  ){
+    i64 currentSize, newSize;
+    int szPage = pPager->pageSize;
+    assert( pPager->eLock==EXCLUSIVE_LOCK );
+    /* TODO: Is it safe to use Pager.dbFileSize here? */
+    rc = sqlite3OsFileSize(pPager->fd, &currentSize);
+    newSize = szPage*(i64)nPage;
+    if( rc==SQLITE_OK && currentSize!=newSize ){
+      if( currentSize>newSize ){
+        rc = sqlite3OsTruncate(pPager->fd, newSize);
+      }else{
+        char *pTmp = pPager->pTmpSpace;
+        memset(pTmp, 0, szPage);
+        testcase( (newSize-szPage) <  currentSize );
+        testcase( (newSize-szPage) == currentSize );
+        testcase( (newSize-szPage) >  currentSize );
+        rc = sqlite3OsWrite(pPager->fd, pTmp, szPage, newSize-szPage);
+      }
+      if( rc==SQLITE_OK ){
+        pPager->dbFileSize = nPage;
+      }
+    }
+  }
+  return rc;
+}
+
+/*
+** Set the value of the Pager.sectorSize variable for the given
+** pager based on the value returned by the xSectorSize method
+** of the open database file. The sector size will be used used 
+** to determine the size and alignment of journal header and 
+** master journal pointers within created journal files.
+**
+** For temporary files the effective sector size is always 512 bytes.
+**
+** Otherwise, for non-temporary files, the effective sector size is
+** the value returned by the xSectorSize() method rounded up to 32 if
+** it is less than 32, or rounded down to MAX_SECTOR_SIZE if it
+** is greater than MAX_SECTOR_SIZE.
+*/
+static void setSectorSize(Pager *pPager){
+  assert( isOpen(pPager->fd) || pPager->tempFile );
+
+  if( !pPager->tempFile ){
+    /* Sector size doesn't matter for temporary files. Also, the file
+    ** may not have been opened yet, in which case the OsSectorSize()
+    ** call will segfault.
+    */
+    pPager->sectorSize = sqlite3OsSectorSize(pPager->fd);
+  }
+  if( pPager->sectorSize<32 ){
+    pPager->sectorSize = 512;
+  }
+  if( pPager->sectorSize>MAX_SECTOR_SIZE ){
+    assert( MAX_SECTOR_SIZE>=512 );
+    pPager->sectorSize = MAX_SECTOR_SIZE;
+  }
+}
+
+/*
+** Playback the journal and thus restore the database file to
+** the state it was in before we started making changes.  
+**
+** The journal file format is as follows: 
+**
+**  (1)  8 byte prefix.  A copy of aJournalMagic[].
+**  (2)  4 byte big-endian integer which is the number of valid page records
+**       in the journal.  If this value is 0xffffffff, then compute the
+**       number of page records from the journal size.
+**  (3)  4 byte big-endian integer which is the initial value for the 
+**       sanity checksum.
+**  (4)  4 byte integer which is the number of pages to truncate the
+**       database to during a rollback.
+**  (5)  4 byte big-endian integer which is the sector size.  The header
+**       is this many bytes in size.
+**  (6)  4 byte big-endian integer which is the page size.
+**  (7)  zero padding out to the next sector size.
+**  (8)  Zero or more pages instances, each as follows:
+**        +  4 byte page number.
+**        +  pPager->pageSize bytes of data.
+**        +  4 byte checksum
+**
+** When we speak of the journal header, we mean the first 7 items above.
+** Each entry in the journal is an instance of the 8th item.
+**
+** Call the value from the second bullet "nRec".  nRec is the number of
+** valid page entries in the journal.  In most cases, you can compute the
+** value of nRec from the size of the journal file.  But if a power
+** failure occurred while the journal was being written, it could be the
+** case that the size of the journal file had already been increased but
+** the extra entries had not yet made it safely to disk.  In such a case,
+** the value of nRec computed from the file size would be too large.  For
+** that reason, we always use the nRec value in the header.
+**
+** If the nRec value is 0xffffffff it means that nRec should be computed
+** from the file size.  This value is used when the user selects the
+** no-sync option for the journal.  A power failure could lead to corruption
+** in this case.  But for things like temporary table (which will be
+** deleted when the power is restored) we don't care.  
+**
+** If the file opened as the journal file is not a well-formed
+** journal file then all pages up to the first corrupted page are rolled
+** back (or no pages if the journal header is corrupted). The journal file
+** is then deleted and SQLITE_OK returned, just as if no corruption had
+** been encountered.
+**
+** If an I/O or malloc() error occurs, the journal-file is not deleted
+** and an error code is returned.
+**
+** The isHot parameter indicates that we are trying to rollback a journal
+** that might be a hot journal.  Or, it could be that the journal is 
+** preserved because of JOURNALMODE_PERSIST or JOURNALMODE_TRUNCATE.
+** If the journal really is hot, reset the pager cache prior rolling
+** back any content.  If the journal is merely persistent, no reset is
+** needed.
+*/
+static int pager_playback(Pager *pPager, int isHot){
+  sqlite3_vfs *pVfs = pPager->pVfs;
+  i64 szJ;                 /* Size of the journal file in bytes */
+  u32 nRec;                /* Number of Records in the journal */
+  u32 u;                   /* Unsigned loop counter */
+  Pgno mxPg = 0;           /* Size of the original file in pages */
+  int rc;                  /* Result code of a subroutine */
+  int res = 1;             /* Value returned by sqlite3OsAccess() */
+  char *zMaster = 0;       /* Name of master journal file if any */
+  int needPagerReset;      /* True to reset page prior to first page rollback */
+
+  /* Figure out how many records are in the journal.  Abort early if
+  ** the journal is empty.
+  */
+  assert( isOpen(pPager->jfd) );
+  rc = sqlite3OsFileSize(pPager->jfd, &szJ);
+  if( rc!=SQLITE_OK ){
+    goto end_playback;
+  }
+
+  /* Read the master journal name from the journal, if it is present.
+  ** If a master journal file name is specified, but the file is not
+  ** present on disk, then the journal is not hot and does not need to be
+  ** played back.
+  **
+  ** TODO: Technically the following is an error because it assumes that
+  ** buffer Pager.pTmpSpace is (mxPathname+1) bytes or larger. i.e. that
+  ** (pPager->pageSize >= pPager->pVfs->mxPathname+1). Using os_unix.c,
+  **  mxPathname is 512, which is the same as the minimum allowable value
+  ** for pageSize.
+  */
+  zMaster = pPager->pTmpSpace;
+  rc = readMasterJournal(pPager->jfd, zMaster, pPager->pVfs->mxPathname+1);
+  if( rc==SQLITE_OK && zMaster[0] ){
+    rc = sqlite3OsAccess(pVfs, zMaster, SQLITE_ACCESS_EXISTS, &res);
+  }
+  zMaster = 0;
+  if( rc!=SQLITE_OK || !res ){
+    goto end_playback;
+  }
+  pPager->journalOff = 0;
+  needPagerReset = isHot;
+
+  /* This loop terminates either when a readJournalHdr() or 
+  ** pager_playback_one_page() call returns SQLITE_DONE or an IO error 
+  ** occurs. 
+  */
+  while( 1 ){
+    /* Read the next journal header from the journal file.  If there are
+    ** not enough bytes left in the journal file for a complete header, or
+    ** it is corrupted, then a process must have failed while writing it.
+    ** This indicates nothing more needs to be rolled back.
+    */
+    rc = readJournalHdr(pPager, isHot, szJ, &nRec, &mxPg);
+    if( rc!=SQLITE_OK ){ 
+      if( rc==SQLITE_DONE ){
+        rc = SQLITE_OK;
+      }
+      goto end_playback;
+    }
+
+    /* If nRec is 0xffffffff, then this journal was created by a process
+    ** working in no-sync mode. This means that the rest of the journal
+    ** file consists of pages, there are no more journal headers. Compute
+    ** the value of nRec based on this assumption.
+    */
+    if( nRec==0xffffffff ){
+      assert( pPager->journalOff==JOURNAL_HDR_SZ(pPager) );
+      nRec = (int)((szJ - JOURNAL_HDR_SZ(pPager))/JOURNAL_PG_SZ(pPager));
+    }
+
+    /* If nRec is 0 and this rollback is of a transaction created by this
+    ** process and if this is the final header in the journal, then it means
+    ** that this part of the journal was being filled but has not yet been
+    ** synced to disk.  Compute the number of pages based on the remaining
+    ** size of the file.
+    **
+    ** The third term of the test was added to fix ticket #2565.
+    ** When rolling back a hot journal, nRec==0 always means that the next
+    ** chunk of the journal contains zero pages to be rolled back.  But
+    ** when doing a ROLLBACK and the nRec==0 chunk is the last chunk in
+    ** the journal, it means that the journal might contain additional
+    ** pages that need to be rolled back and that the number of pages 
+    ** should be computed based on the journal file size.
+    */
+    if( nRec==0 && !isHot &&
+        pPager->journalHdr+JOURNAL_HDR_SZ(pPager)==pPager->journalOff ){
+      nRec = (int)((szJ - pPager->journalOff) / JOURNAL_PG_SZ(pPager));
+    }
+
+    /* If this is the first header read from the journal, truncate the
+    ** database file back to its original size.
+    */
+    if( pPager->journalOff==JOURNAL_HDR_SZ(pPager) ){
+      rc = pager_truncate(pPager, mxPg);
+      if( rc!=SQLITE_OK ){
+        goto end_playback;
+      }
+      pPager->dbSize = mxPg;
+    }
+
+    /* Copy original pages out of the journal and back into the 
+    ** database file and/or page cache.
+    */
+    for(u=0; u<nRec; u++){
+      if( needPagerReset ){
+        pager_reset(pPager);
+        needPagerReset = 0;
+      }
+      rc = pager_playback_one_page(pPager,&pPager->journalOff,0,1,0);
+      if( rc!=SQLITE_OK ){
+        if( rc==SQLITE_DONE ){
+          rc = SQLITE_OK;
+          pPager->journalOff = szJ;
+          break;
+        }else if( rc==SQLITE_IOERR_SHORT_READ ){
+          /* If the journal has been truncated, simply stop reading and
+          ** processing the journal. This might happen if the journal was
+          ** not completely written and synced prior to a crash.  In that
+          ** case, the database should have never been written in the
+          ** first place so it is OK to simply abandon the rollback. */
+          rc = SQLITE_OK;
+          goto end_playback;
+        }else{
+          /* If we are unable to rollback, quit and return the error
+          ** code.  This will cause the pager to enter the error state
+          ** so that no further harm will be done.  Perhaps the next
+          ** process to come along will be able to rollback the database.
+          */
+          goto end_playback;
+        }
+      }
+    }
+  }
+  /*NOTREACHED*/
+  assert( 0 );
+
+end_playback:
+  /* Following a rollback, the database file should be back in its original
+  ** state prior to the start of the transaction, so invoke the
+  ** SQLITE_FCNTL_DB_UNCHANGED file-control method to disable the
+  ** assertion that the transaction counter was modified.
+  */
+  assert(
+    pPager->fd->pMethods==0 ||
+    sqlite3OsFileControl(pPager->fd,SQLITE_FCNTL_DB_UNCHANGED,0)>=SQLITE_OK
+  );
+
+  /* If this playback is happening automatically as a result of an IO or 
+  ** malloc error that occurred after the change-counter was updated but 
+  ** before the transaction was committed, then the change-counter 
+  ** modification may just have been reverted. If this happens in exclusive 
+  ** mode, then subsequent transactions performed by the connection will not
+  ** update the change-counter at all. This may lead to cache inconsistency
+  ** problems for other processes at some point in the future. So, just
+  ** in case this has happened, clear the changeCountDone flag now.
+  */
+  pPager->changeCountDone = pPager->tempFile;
+
+  if( rc==SQLITE_OK ){
+    zMaster = pPager->pTmpSpace;
+    rc = readMasterJournal(pPager->jfd, zMaster, pPager->pVfs->mxPathname+1);
+    testcase( rc!=SQLITE_OK );
+  }
+  if( rc==SQLITE_OK
+   && (pPager->eState>=PAGER_WRITER_DBMOD || pPager->eState==PAGER_OPEN)
+  ){
+    rc = sqlite3PagerSync(pPager);
+  }
+  if( rc==SQLITE_OK ){
+    rc = pager_end_transaction(pPager, zMaster[0]!='\0');
+    testcase( rc!=SQLITE_OK );
+  }
+  if( rc==SQLITE_OK && zMaster[0] && res ){
+    /* If there was a master journal and this routine will return success,
+    ** see if it is possible to delete the master journal.
+    */
+    rc = pager_delmaster(pPager, zMaster);
+    testcase( rc!=SQLITE_OK );
+  }
+
+  /* The Pager.sectorSize variable may have been updated while rolling
+  ** back a journal created by a process with a different sector size
+  ** value. Reset it to the correct value for this process.
+  */
+  setSectorSize(pPager);
+  return rc;
+}
+
+
+/*
+** Read the content for page pPg out of the database file and into 
+** pPg->pData. A shared lock or greater must be held on the database
+** file before this function is called.
+**
+** If page 1 is read, then the value of Pager.dbFileVers[] is set to
+** the value read from the database file.
+**
+** If an IO error occurs, then the IO error is returned to the caller.
+** Otherwise, SQLITE_OK is returned.
+*/
+static int readDbPage(PgHdr *pPg){
+  Pager *pPager = pPg->pPager; /* Pager object associated with page pPg */
+  Pgno pgno = pPg->pgno;       /* Page number to read */
+  int rc = SQLITE_OK;          /* Return code */
+  int isInWal = 0;             /* True if page is in log file */
+  int pgsz = pPager->pageSize; /* Number of bytes to read */
+
+  assert( pPager->eState>=PAGER_READER && !MEMDB );
+  assert( isOpen(pPager->fd) );
+
+  if( NEVER(!isOpen(pPager->fd)) ){
+    assert( pPager->tempFile );
+    memset(pPg->pData, 0, pPager->pageSize);
+    return SQLITE_OK;
+  }
+
+  if( pagerUseWal(pPager) ){
+    /* Try to pull the page from the write-ahead log. */
+    rc = sqlite3WalRead(pPager->pWal, pgno, &isInWal, pgsz, pPg->pData);
+  }
+  if( rc==SQLITE_OK && !isInWal ){
+    i64 iOffset = (pgno-1)*(i64)pPager->pageSize;
+    rc = sqlite3OsRead(pPager->fd, pPg->pData, pgsz, iOffset);
+    if( rc==SQLITE_IOERR_SHORT_READ ){
+      rc = SQLITE_OK;
+    }
+  }
+
+  if( pgno==1 ){
+    if( rc ){
+      /* If the read is unsuccessful, set the dbFileVers[] to something
+      ** that will never be a valid file version.  dbFileVers[] is a copy
+      ** of bytes 24..39 of the database.  Bytes 28..31 should always be
+      ** zero or the size of the database in page. Bytes 32..35 and 35..39
+      ** should be page numbers which are never 0xffffffff.  So filling
+      ** pPager->dbFileVers[] with all 0xff bytes should suffice.
+      **
+      ** For an encrypted database, the situation is more complex:  bytes
+      ** 24..39 of the database are white noise.  But the probability of
+      ** white noising equaling 16 bytes of 0xff is vanishingly small so
+      ** we should still be ok.
+      */
+      memset(pPager->dbFileVers, 0xff, sizeof(pPager->dbFileVers));
+    }else{
+      u8 *dbFileVers = &((u8*)pPg->pData)[24];
+      memcpy(&pPager->dbFileVers, dbFileVers, sizeof(pPager->dbFileVers));
+    }
+  }
+  CODEC1(pPager, pPg->pData, pgno, 3, rc = SQLITE_NOMEM);
+
+  PAGER_INCR(sqlite3_pager_readdb_count);
+  PAGER_INCR(pPager->nRead);
+  IOTRACE(("PGIN %p %d\n", pPager, pgno));
+  PAGERTRACE(("FETCH %d page %d hash(%08x)\n",
+               PAGERID(pPager), pgno, pager_pagehash(pPg)));
+
+  return rc;
+}
+
+/*
+** Update the value of the change-counter at offsets 24 and 92 in
+** the header and the sqlite version number at offset 96.
+**
+** This is an unconditional update.  See also the pager_incr_changecounter()
+** routine which only updates the change-counter if the update is actually
+** needed, as determined by the pPager->changeCountDone state variable.
+*/
+static void pager_write_changecounter(PgHdr *pPg){
+  u32 change_counter;
+
+  /* Increment the value just read and write it back to byte 24. */
+  change_counter = sqlite3Get4byte((u8*)pPg->pPager->dbFileVers)+1;
+  put32bits(((char*)pPg->pData)+24, change_counter);
+
+  /* Also store the SQLite version number in bytes 96..99 and in
+  ** bytes 92..95 store the change counter for which the version number
+  ** is valid. */
+  put32bits(((char*)pPg->pData)+92, change_counter);
+  put32bits(((char*)pPg->pData)+96, SQLITE_VERSION_NUMBER);
+}
+
+#ifndef SQLITE_OMIT_WAL
+/*
+** This function is invoked once for each page that has already been 
+** written into the log file when a WAL transaction is rolled back.
+** Parameter iPg is the page number of said page. The pCtx argument 
+** is actually a pointer to the Pager structure.
+**
+** If page iPg is present in the cache, and has no outstanding references,
+** it is discarded. Otherwise, if there are one or more outstanding
+** references, the page content is reloaded from the database. If the
+** attempt to reload content from the database is required and fails, 
+** return an SQLite error code. Otherwise, SQLITE_OK.
+*/
+static int pagerUndoCallback(void *pCtx, Pgno iPg){
+  int rc = SQLITE_OK;
+  Pager *pPager = (Pager *)pCtx;
+  PgHdr *pPg;
+
+  pPg = sqlite3PagerLookup(pPager, iPg);
+  if( pPg ){
+    if( sqlite3PcachePageRefcount(pPg)==1 ){
+      sqlite3PcacheDrop(pPg);
+    }else{
+      rc = readDbPage(pPg);
+      if( rc==SQLITE_OK ){
+        pPager->xReiniter(pPg);
+      }
+      sqlite3PagerUnref(pPg);
+    }
+  }
+
+  /* Normally, if a transaction is rolled back, any backup processes are
+  ** updated as data is copied out of the rollback journal and into the
+  ** database. This is not generally possible with a WAL database, as
+  ** rollback involves simply truncating the log file. Therefore, if one
+  ** or more frames have already been written to the log (and therefore 
+  ** also copied into the backup databases) as part of this transaction,
+  ** the backups must be restarted.
+  */
+  sqlite3BackupRestart(pPager->pBackup);
+
+  return rc;
+}
+
+/*
+** This function is called to rollback a transaction on a WAL database.
+*/
+static int pagerRollbackWal(Pager *pPager){
+  int rc;                         /* Return Code */
+  PgHdr *pList;                   /* List of dirty pages to revert */
+
+  /* For all pages in the cache that are currently dirty or have already
+  ** been written (but not committed) to the log file, do one of the 
+  ** following:
+  **
+  **   + Discard the cached page (if refcount==0), or
+  **   + Reload page content from the database (if refcount>0).
+  */
+  pPager->dbSize = pPager->dbOrigSize;
+  rc = sqlite3WalUndo(pPager->pWal, pagerUndoCallback, (void *)pPager);
+  pList = sqlite3PcacheDirtyList(pPager->pPCache);
+  while( pList && rc==SQLITE_OK ){
+    PgHdr *pNext = pList->pDirty;
+    rc = pagerUndoCallback((void *)pPager, pList->pgno);
+    pList = pNext;
+  }
+
+  return rc;
+}
+
+/*
+** This function is a wrapper around sqlite3WalFrames(). As well as logging
+** the contents of the list of pages headed by pList (connected by pDirty),
+** this function notifies any active backup processes that the pages have
+** changed. 
+**
+** The list of pages passed into this routine is always sorted by page number.
+** Hence, if page 1 appears anywhere on the list, it will be the first page.
+*/ 
+static int pagerWalFrames(
+  Pager *pPager,                  /* Pager object */
+  PgHdr *pList,                   /* List of frames to log */
+  Pgno nTruncate,                 /* Database size after this commit */
+  int isCommit,                   /* True if this is a commit */
+  int syncFlags                   /* Flags to pass to OsSync() (or 0) */
+){
+  int rc;                         /* Return code */
+#if defined(SQLITE_DEBUG) || defined(SQLITE_CHECK_PAGES)
+  PgHdr *p;                       /* For looping over pages */
+#endif
+
+  assert( pPager->pWal );
+#ifdef SQLITE_DEBUG
+  /* Verify that the page list is in accending order */
+  for(p=pList; p && p->pDirty; p=p->pDirty){
+    assert( p->pgno < p->pDirty->pgno );
+  }
+#endif
+
+  if( isCommit ){
+    /* If a WAL transaction is being committed, there is no point in writing
+    ** any pages with page numbers greater than nTruncate into the WAL file.
+    ** They will never be read by any client. So remove them from the pDirty
+    ** list here. */
+    PgHdr *p;
+    PgHdr **ppNext = &pList;
+    for(p=pList; (*ppNext = p); p=p->pDirty){
+      if( p->pgno<=nTruncate ) ppNext = &p->pDirty;
+    }
+    assert( pList );
+  }
+
+  if( pList->pgno==1 ) pager_write_changecounter(pList);
+  rc = sqlite3WalFrames(pPager->pWal, 
+      pPager->pageSize, pList, nTruncate, isCommit, syncFlags
+  );
+  if( rc==SQLITE_OK && pPager->pBackup ){
+    PgHdr *p;
+    for(p=pList; p; p=p->pDirty){
+      sqlite3BackupUpdate(pPager->pBackup, p->pgno, (u8 *)p->pData);
+    }
+  }
+
+#ifdef SQLITE_CHECK_PAGES
+  pList = sqlite3PcacheDirtyList(pPager->pPCache);
+  for(p=pList; p; p=p->pDirty){
+    pager_set_pagehash(p);
+  }
+#endif
+
+  return rc;
+}
+
+/*
+** Begin a read transaction on the WAL.
+**
+** This routine used to be called "pagerOpenSnapshot()" because it essentially
+** makes a snapshot of the database at the current point in time and preserves
+** that snapshot for use by the reader in spite of concurrently changes by
+** other writers or checkpointers.
+*/
+static int pagerBeginReadTransaction(Pager *pPager){
+  int rc;                         /* Return code */
+  int changed = 0;                /* True if cache must be reset */
+
+  assert( pagerUseWal(pPager) );
+  assert( pPager->eState==PAGER_OPEN || pPager->eState==PAGER_READER );
+
+  /* sqlite3WalEndReadTransaction() was not called for the previous
+  ** transaction in locking_mode=EXCLUSIVE.  So call it now.  If we
+  ** are in locking_mode=NORMAL and EndRead() was previously called,
+  ** the duplicate call is harmless.
+  */
+  sqlite3WalEndReadTransaction(pPager->pWal);
+
+  rc = sqlite3WalBeginReadTransaction(pPager->pWal, &changed);
+  if( rc!=SQLITE_OK || changed ){
+    pager_reset(pPager);
+  }
+
+  return rc;
+}
+#endif
+
+/*
+** This function is called as part of the transition from PAGER_OPEN
+** to PAGER_READER state to determine the size of the database file
+** in pages (assuming the page size currently stored in Pager.pageSize).
+**
+** If no error occurs, SQLITE_OK is returned and the size of the database
+** in pages is stored in *pnPage. Otherwise, an error code (perhaps
+** SQLITE_IOERR_FSTAT) is returned and *pnPage is left unmodified.
+*/
+static int pagerPagecount(Pager *pPager, Pgno *pnPage){
+  Pgno nPage;                     /* Value to return via *pnPage */
+
+  /* Query the WAL sub-system for the database size. The WalDbsize()
+  ** function returns zero if the WAL is not open (i.e. Pager.pWal==0), or
+  ** if the database size is not available. The database size is not
+  ** available from the WAL sub-system if the log file is empty or
+  ** contains no valid committed transactions.
+  */
+  assert( pPager->eState==PAGER_OPEN );
+  assert( pPager->eLock>=SHARED_LOCK || pPager->noReadlock );
+  nPage = sqlite3WalDbsize(pPager->pWal);
+
+  /* If the database size was not available from the WAL sub-system,
+  ** determine it based on the size of the database file. If the size
+  ** of the database file is not an integer multiple of the page-size,
+  ** round down to the nearest page. Except, any file larger than 0
+  ** bytes in size is considered to contain at least one page.
+  */
+  if( nPage==0 ){
+    i64 n = 0;                    /* Size of db file in bytes */
+    assert( isOpen(pPager->fd) || pPager->tempFile );
+    if( isOpen(pPager->fd) ){
+      int rc = sqlite3OsFileSize(pPager->fd, &n);
+      if( rc!=SQLITE_OK ){
+        return rc;
+      }
+    }
+    nPage = (Pgno)(n / pPager->pageSize);
+    if( nPage==0 && n>0 ){
+      nPage = 1;
+    }
+  }
+
+  /* If the current number of pages in the file is greater than the
+  ** configured maximum pager number, increase the allowed limit so
+  ** that the file can be read.
+  */
+  if( nPage>pPager->mxPgno ){
+    pPager->mxPgno = (Pgno)nPage;
+  }
+
+  *pnPage = nPage;
+  return SQLITE_OK;
+}
+
+#ifndef SQLITE_OMIT_WAL
+/*
+** Check if the *-wal file that corresponds to the database opened by pPager
+** exists if the database is not empy, or verify that the *-wal file does
+** not exist (by deleting it) if the database file is empty.
+**
+** If the database is not empty and the *-wal file exists, open the pager
+** in WAL mode.  If the database is empty or if no *-wal file exists and
+** if no error occurs, make sure Pager.journalMode is not set to
+** PAGER_JOURNALMODE_WAL.
+**
+** Return SQLITE_OK or an error code.
+**
+** The caller must hold a SHARED lock on the database file to call this
+** function. Because an EXCLUSIVE lock on the db file is required to delete 
+** a WAL on a none-empty database, this ensures there is no race condition 
+** between the xAccess() below and an xDelete() being executed by some 
+** other connection.
+*/
+static int pagerOpenWalIfPresent(Pager *pPager){
+  int rc = SQLITE_OK;
+  assert( pPager->eState==PAGER_OPEN );
+  assert( pPager->eLock>=SHARED_LOCK || pPager->noReadlock );
+
+  if( !pPager->tempFile ){
+    int isWal;                    /* True if WAL file exists */
+    Pgno nPage;                   /* Size of the database file */
+
+    rc = pagerPagecount(pPager, &nPage);
+    if( rc ) return rc;
+    if( nPage==0 ){
+      rc = sqlite3OsDelete(pPager->pVfs, pPager->zWal, 0);
+      isWal = 0;
+    }else{
+      rc = sqlite3OsAccess(
+          pPager->pVfs, pPager->zWal, SQLITE_ACCESS_EXISTS, &isWal
+      );
+    }
+    if( rc==SQLITE_OK ){
+      if( isWal ){
+        testcase( sqlite3PcachePagecount(pPager->pPCache)==0 );
+        rc = sqlite3PagerOpenWal(pPager, 0);
+      }else if( pPager->journalMode==PAGER_JOURNALMODE_WAL ){
+        pPager->journalMode = PAGER_JOURNALMODE_DELETE;
+      }
+    }
+  }
+  return rc;
+}
+#endif
+
+/*
+** Playback savepoint pSavepoint. Or, if pSavepoint==NULL, then playback
+** the entire master journal file. The case pSavepoint==NULL occurs when 
+** a ROLLBACK TO command is invoked on a SAVEPOINT that is a transaction 
+** savepoint.
+**
+** When pSavepoint is not NULL (meaning a non-transaction savepoint is 
+** being rolled back), then the rollback consists of up to three stages,
+** performed in the order specified:
+**
+**   * Pages are played back from the main journal starting at byte
+**     offset PagerSavepoint.iOffset and continuing to 
+**     PagerSavepoint.iHdrOffset, or to the end of the main journal
+**     file if PagerSavepoint.iHdrOffset is zero.
+**
+**   * If PagerSavepoint.iHdrOffset is not zero, then pages are played
+**     back starting from the journal header immediately following 
+**     PagerSavepoint.iHdrOffset to the end of the main journal file.
+**
+**   * Pages are then played back from the sub-journal file, starting
+**     with the PagerSavepoint.iSubRec and continuing to the end of
+**     the journal file.
+**
+** Throughout the rollback process, each time a page is rolled back, the
+** corresponding bit is set in a bitvec structure (variable pDone in the
+** implementation below). This is used to ensure that a page is only
+** rolled back the first time it is encountered in either journal.
+**
+** If pSavepoint is NULL, then pages are only played back from the main
+** journal file. There is no need for a bitvec in this case.
+**
+** In either case, before playback commences the Pager.dbSize variable
+** is reset to the value that it held at the start of the savepoint 
+** (or transaction). No page with a page-number greater than this value
+** is played back. If one is encountered it is simply skipped.
+*/
+static int pagerPlaybackSavepoint(Pager *pPager, PagerSavepoint *pSavepoint){
+  i64 szJ;                 /* Effective size of the main journal */
+  i64 iHdrOff;             /* End of first segment of main-journal records */
+  int rc = SQLITE_OK;      /* Return code */
+  Bitvec *pDone = 0;       /* Bitvec to ensure pages played back only once */
+
+  assert( pPager->eState!=PAGER_ERROR );
+  assert( pPager->eState>=PAGER_WRITER_LOCKED );
+
+  /* Allocate a bitvec to use to store the set of pages rolled back */
+  if( pSavepoint ){
+    pDone = sqlite3BitvecCreate(pSavepoint->nOrig);
+    if( !pDone ){
+      return SQLITE_NOMEM;
+    }
+  }
+
+  /* Set the database size back to the value it was before the savepoint 
+  ** being reverted was opened.
+  */
+  pPager->dbSize = pSavepoint ? pSavepoint->nOrig : pPager->dbOrigSize;
+  pPager->changeCountDone = pPager->tempFile;
+
+  if( !pSavepoint && pagerUseWal(pPager) ){
+    return pagerRollbackWal(pPager);
+  }
+
+  /* Use pPager->journalOff as the effective size of the main rollback
+  ** journal.  The actual file might be larger than this in
+  ** PAGER_JOURNALMODE_TRUNCATE or PAGER_JOURNALMODE_PERSIST.  But anything
+  ** past pPager->journalOff is off-limits to us.
+  */
+  szJ = pPager->journalOff;
+  assert( pagerUseWal(pPager)==0 || szJ==0 );
+
+  /* Begin by rolling back records from the main journal starting at
+  ** PagerSavepoint.iOffset and continuing to the next journal header.
+  ** There might be records in the main journal that have a page number
+  ** greater than the current database size (pPager->dbSize) but those
+  ** will be skipped automatically.  Pages are added to pDone as they
+  ** are played back.
+  */
+  if( pSavepoint && !pagerUseWal(pPager) ){
+    iHdrOff = pSavepoint->iHdrOffset ? pSavepoint->iHdrOffset : szJ;
+    pPager->journalOff = pSavepoint->iOffset;
+    while( rc==SQLITE_OK && pPager->journalOff<iHdrOff ){
+      rc = pager_playback_one_page(pPager, &pPager->journalOff, pDone, 1, 1);
+    }
+    assert( rc!=SQLITE_DONE );
+  }else{
+    pPager->journalOff = 0;
+  }
+
+  /* Continue rolling back records out of the main journal starting at
+  ** the first journal header seen and continuing until the effective end
+  ** of the main journal file.  Continue to skip out-of-range pages and
+  ** continue adding pages rolled back to pDone.
+  */
+  while( rc==SQLITE_OK && pPager->journalOff<szJ ){
+    u32 ii;            /* Loop counter */
+    u32 nJRec = 0;     /* Number of Journal Records */
+    u32 dummy;
+    rc = readJournalHdr(pPager, 0, szJ, &nJRec, &dummy);
+    assert( rc!=SQLITE_DONE );
+
+    /*
+    ** The "pPager->journalHdr+JOURNAL_HDR_SZ(pPager)==pPager->journalOff"
+    ** test is related to ticket #2565.  See the discussion in the
+    ** pager_playback() function for additional information.
+    */
+    if( nJRec==0 
+     && pPager->journalHdr+JOURNAL_HDR_SZ(pPager)==pPager->journalOff
+    ){
+      nJRec = (u32)((szJ - pPager->journalOff)/JOURNAL_PG_SZ(pPager));
+    }
+    for(ii=0; rc==SQLITE_OK && ii<nJRec && pPager->journalOff<szJ; ii++){
+      rc = pager_playback_one_page(pPager, &pPager->journalOff, pDone, 1, 1);
+    }
+    assert( rc!=SQLITE_DONE );
+  }
+  assert( rc!=SQLITE_OK || pPager->journalOff>=szJ );
+
+  /* Finally,  rollback pages from the sub-journal.  Page that were
+  ** previously rolled back out of the main journal (and are hence in pDone)
+  ** will be skipped.  Out-of-range pages are also skipped.
+  */
+  if( pSavepoint ){
+    u32 ii;            /* Loop counter */
+    i64 offset = pSavepoint->iSubRec*(4+pPager->pageSize);
+
+    if( pagerUseWal(pPager) ){
+      rc = sqlite3WalSavepointUndo(pPager->pWal, pSavepoint->aWalData);
+    }
+    for(ii=pSavepoint->iSubRec; rc==SQLITE_OK && ii<pPager->nSubRec; ii++){
+      assert( offset==ii*(4+pPager->pageSize) );
+      rc = pager_playback_one_page(pPager, &offset, pDone, 0, 1);
+    }
+    assert( rc!=SQLITE_DONE );
+  }
+
+  sqlite3BitvecDestroy(pDone);
+  if( rc==SQLITE_OK ){
+    pPager->journalOff = szJ;
+  }
+
+  return rc;
+}
+
+/*
+** Change the maximum number of in-memory pages that are allowed.
+*/
+SQLITE_PRIVATE void sqlite3PagerSetCachesize(Pager *pPager, int mxPage){
+  sqlite3PcacheSetCachesize(pPager->pPCache, mxPage);
+}
+
+/*
+** Adjust the robustness of the database to damage due to OS crashes
+** or power failures by changing the number of syncs()s when writing
+** the rollback journal.  There are three levels:
+**
+**    OFF       sqlite3OsSync() is never called.  This is the default
+**              for temporary and transient files.
+**
+**    NORMAL    The journal is synced once before writes begin on the
+**              database.  This is normally adequate protection, but
+**              it is theoretically possible, though very unlikely,
+**              that an inopertune power failure could leave the journal
+**              in a state which would cause damage to the database
+**              when it is rolled back.
+**
+**    FULL      The journal is synced twice before writes begin on the
+**              database (with some additional information - the nRec field
+**              of the journal header - being written in between the two
+**              syncs).  If we assume that writing a
+**              single disk sector is atomic, then this mode provides
+**              assurance that the journal will not be corrupted to the
+**              point of causing damage to the database during rollback.
+**
+** The above is for a rollback-journal mode.  For WAL mode, OFF continues
+** to mean that no syncs ever occur.  NORMAL means that the WAL is synced
+** prior to the start of checkpoint and that the database file is synced
+** at the conclusion of the checkpoint if the entire content of the WAL
+** was written back into the database.  But no sync operations occur for
+** an ordinary commit in NORMAL mode with WAL.  FULL means that the WAL
+** file is synced following each commit operation, in addition to the
+** syncs associated with NORMAL.
+**
+** Do not confuse synchronous=FULL with SQLITE_SYNC_FULL.  The
+** SQLITE_SYNC_FULL macro means to use the MacOSX-style full-fsync
+** using fcntl(F_FULLFSYNC).  SQLITE_SYNC_NORMAL means to do an
+** ordinary fsync() call.  There is no difference between SQLITE_SYNC_FULL
+** and SQLITE_SYNC_NORMAL on platforms other than MacOSX.  But the
+** synchronous=FULL versus synchronous=NORMAL setting determines when
+** the xSync primitive is called and is relevant to all platforms.
+**
+** Numeric values associated with these states are OFF==1, NORMAL=2,
+** and FULL=3.
+*/
+#ifndef SQLITE_OMIT_PAGER_PRAGMAS
+SQLITE_PRIVATE void sqlite3PagerSetSafetyLevel(
+  Pager *pPager,        /* The pager to set safety level for */
+  int level,            /* PRAGMA synchronous.  1=OFF, 2=NORMAL, 3=FULL */  
+  int bFullFsync,       /* PRAGMA fullfsync */
+  int bCkptFullFsync    /* PRAGMA checkpoint_fullfsync */
+){
+  assert( level>=1 && level<=3 );
+  pPager->noSync =  (level==1 || pPager->tempFile) ?1:0;
+  pPager->fullSync = (level==3 && !pPager->tempFile) ?1:0;
+  if( pPager->noSync ){
+    pPager->syncFlags = 0;
+    pPager->ckptSyncFlags = 0;
+  }else if( bFullFsync ){
+    pPager->syncFlags = SQLITE_SYNC_FULL;
+    pPager->ckptSyncFlags = SQLITE_SYNC_FULL;
+  }else if( bCkptFullFsync ){
+    pPager->syncFlags = SQLITE_SYNC_NORMAL;
+    pPager->ckptSyncFlags = SQLITE_SYNC_FULL;
+  }else{
+    pPager->syncFlags = SQLITE_SYNC_NORMAL;
+    pPager->ckptSyncFlags = SQLITE_SYNC_NORMAL;
+  }
+}
+#endif
+
+/*
+** The following global variable is incremented whenever the library
+** attempts to open a temporary file.  This information is used for
+** testing and analysis only.  
+*/
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_opentemp_count = 0;
+#endif
+
+/*
+** Open a temporary file.
+**
+** Write the file descriptor into *pFile. Return SQLITE_OK on success 
+** or some other error code if we fail. The OS will automatically 
+** delete the temporary file when it is closed.
+**
+** The flags passed to the VFS layer xOpen() call are those specified
+** by parameter vfsFlags ORed with the following:
+**
+**     SQLITE_OPEN_READWRITE
+**     SQLITE_OPEN_CREATE
+**     SQLITE_OPEN_EXCLUSIVE
+**     SQLITE_OPEN_DELETEONCLOSE
+*/
+static int pagerOpentemp(
+  Pager *pPager,        /* The pager object */
+  sqlite3_file *pFile,  /* Write the file descriptor here */
+  int vfsFlags          /* Flags passed through to the VFS */
+){
+  int rc;               /* Return code */
+
+#ifdef SQLITE_TEST
+  sqlite3_opentemp_count++;  /* Used for testing and analysis only */
+#endif
+
+  vfsFlags |=  SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE |
+            SQLITE_OPEN_EXCLUSIVE | SQLITE_OPEN_DELETEONCLOSE;
+  rc = sqlite3OsOpen(pPager->pVfs, 0, pFile, vfsFlags, 0);
+  assert( rc!=SQLITE_OK || isOpen(pFile) );
+  return rc;
+}
+
+/*
+** Set the busy handler function.
+**
+** The pager invokes the busy-handler if sqlite3OsLock() returns 
+** SQLITE_BUSY when trying to upgrade from no-lock to a SHARED lock,
+** or when trying to upgrade from a RESERVED lock to an EXCLUSIVE 
+** lock. It does *not* invoke the busy handler when upgrading from
+** SHARED to RESERVED, or when upgrading from SHARED to EXCLUSIVE
+** (which occurs during hot-journal rollback). Summary:
+**
+**   Transition                        | Invokes xBusyHandler
+**   --------------------------------------------------------
+**   NO_LOCK       -> SHARED_LOCK      | Yes
+**   SHARED_LOCK   -> RESERVED_LOCK    | No
+**   SHARED_LOCK   -> EXCLUSIVE_LOCK   | No
+**   RESERVED_LOCK -> EXCLUSIVE_LOCK   | Yes
+**
+** If the busy-handler callback returns non-zero, the lock is 
+** retried. If it returns zero, then the SQLITE_BUSY error is
+** returned to the caller of the pager API function.
+*/
+SQLITE_PRIVATE void sqlite3PagerSetBusyhandler(
+  Pager *pPager,                       /* Pager object */
+  int (*xBusyHandler)(void *),         /* Pointer to busy-handler function */
+  void *pBusyHandlerArg                /* Argument to pass to xBusyHandler */
+){  
+  pPager->xBusyHandler = xBusyHandler;
+  pPager->pBusyHandlerArg = pBusyHandlerArg;
+}
+
+/*
+** Change the page size used by the Pager object. The new page size 
+** is passed in *pPageSize.
+**
+** If the pager is in the error state when this function is called, it
+** is a no-op. The value returned is the error state error code (i.e. 
+** one of SQLITE_IOERR, an SQLITE_IOERR_xxx sub-code or SQLITE_FULL).
+**
+** Otherwise, if all of the following are true:
+**
+**   * the new page size (value of *pPageSize) is valid (a power 
+**     of two between 512 and SQLITE_MAX_PAGE_SIZE, inclusive), and
+**
+**   * there are no outstanding page references, and
+**
+**   * the database is either not an in-memory database or it is
+**     an in-memory database that currently consists of zero pages.
+**
+** then the pager object page size is set to *pPageSize.
+**
+** If the page size is changed, then this function uses sqlite3PagerMalloc() 
+** to obtain a new Pager.pTmpSpace buffer. If this allocation attempt 
+** fails, SQLITE_NOMEM is returned and the page size remains unchanged. 
+** In all other cases, SQLITE_OK is returned.
+**
+** If the page size is not changed, either because one of the enumerated
+** conditions above is not true, the pager was in error state when this
+** function was called, or because the memory allocation attempt failed, 
+** then *pPageSize is set to the old, retained page size before returning.
+*/
+SQLITE_PRIVATE int sqlite3PagerSetPagesize(Pager *pPager, u32 *pPageSize, int nReserve){
+  int rc = SQLITE_OK;
+
+  /* It is not possible to do a full assert_pager_state() here, as this
+  ** function may be called from within PagerOpen(), before the state
+  ** of the Pager object is internally consistent.
+  **
+  ** At one point this function returned an error if the pager was in 
+  ** PAGER_ERROR state. But since PAGER_ERROR state guarantees that
+  ** there is at least one outstanding page reference, this function
+  ** is a no-op for that case anyhow.
+  */
+
+  u32 pageSize = *pPageSize;
+  assert( pageSize==0 || (pageSize>=512 && pageSize<=SQLITE_MAX_PAGE_SIZE) );
+  if( (pPager->memDb==0 || pPager->dbSize==0)
+   && sqlite3PcacheRefCount(pPager->pPCache)==0 
+   && pageSize && pageSize!=(u32)pPager->pageSize 
+  ){
+    char *pNew = NULL;             /* New temp space */
+    i64 nByte = 0;
+
+    if( pPager->eState>PAGER_OPEN && isOpen(pPager->fd) ){
+      rc = sqlite3OsFileSize(pPager->fd, &nByte);
+    }
+    if( rc==SQLITE_OK ){
+      pNew = (char *)sqlite3PageMalloc(pageSize);
+      if( !pNew ) rc = SQLITE_NOMEM;
+    }
+
+    if( rc==SQLITE_OK ){
+      pager_reset(pPager);
+      pPager->dbSize = (Pgno)(nByte/pageSize);
+      pPager->pageSize = pageSize;
+      sqlite3PageFree(pPager->pTmpSpace);
+      pPager->pTmpSpace = pNew;
+      sqlite3PcacheSetPageSize(pPager->pPCache, pageSize);
+    }
+  }
+
+  *pPageSize = pPager->pageSize;
+  if( rc==SQLITE_OK ){
+    if( nReserve<0 ) nReserve = pPager->nReserve;
+    assert( nReserve>=0 && nReserve<1000 );
+    pPager->nReserve = (i16)nReserve;
+    pagerReportSize(pPager);
+  }
+  return rc;
+}
+
+/*
+** Return a pointer to the "temporary page" buffer held internally
+** by the pager.  This is a buffer that is big enough to hold the
+** entire content of a database page.  This buffer is used internally
+** during rollback and will be overwritten whenever a rollback
+** occurs.  But other modules are free to use it too, as long as
+** no rollbacks are happening.
+*/
+SQLITE_PRIVATE void *sqlite3PagerTempSpace(Pager *pPager){
+  return pPager->pTmpSpace;
+}
+
+/*
+** Attempt to set the maximum database page count if mxPage is positive. 
+** Make no changes if mxPage is zero or negative.  And never reduce the
+** maximum page count below the current size of the database.
+**
+** Regardless of mxPage, return the current maximum page count.
+*/
+SQLITE_PRIVATE int sqlite3PagerMaxPageCount(Pager *pPager, int mxPage){
+  if( mxPage>0 ){
+    pPager->mxPgno = mxPage;
+  }
+  assert( pPager->eState!=PAGER_OPEN );      /* Called only by OP_MaxPgcnt */
+  assert( pPager->mxPgno>=pPager->dbSize );  /* OP_MaxPgcnt enforces this */
+  return pPager->mxPgno;
+}
+
+/*
+** The following set of routines are used to disable the simulated
+** I/O error mechanism.  These routines are used to avoid simulated
+** errors in places where we do not care about errors.
+**
+** Unless -DSQLITE_TEST=1 is used, these routines are all no-ops
+** and generate no code.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API extern int sqlite3_io_error_pending;
+SQLITE_API extern int sqlite3_io_error_hit;
+static int saved_cnt;
+void disable_simulated_io_errors(void){
+  saved_cnt = sqlite3_io_error_pending;
+  sqlite3_io_error_pending = -1;
+}
+void enable_simulated_io_errors(void){
+  sqlite3_io_error_pending = saved_cnt;
+}
+#else
+# define disable_simulated_io_errors()
+# define enable_simulated_io_errors()
+#endif
+
+/*
+** Read the first N bytes from the beginning of the file into memory
+** that pDest points to. 
+**
+** If the pager was opened on a transient file (zFilename==""), or
+** opened on a file less than N bytes in size, the output buffer is
+** zeroed and SQLITE_OK returned. The rationale for this is that this 
+** function is used to read database headers, and a new transient or
+** zero sized database has a header than consists entirely of zeroes.
+**
+** If any IO error apart from SQLITE_IOERR_SHORT_READ is encountered,
+** the error code is returned to the caller and the contents of the
+** output buffer undefined.
+*/
+SQLITE_PRIVATE int sqlite3PagerReadFileheader(Pager *pPager, int N, unsigned char *pDest){
+  int rc = SQLITE_OK;
+  memset(pDest, 0, N);
+  assert( isOpen(pPager->fd) || pPager->tempFile );
+
+  /* This routine is only called by btree immediately after creating
+  ** the Pager object.  There has not been an opportunity to transition
+  ** to WAL mode yet.
+  */
+  assert( !pagerUseWal(pPager) );
+
+  if( isOpen(pPager->fd) ){
+    IOTRACE(("DBHDR %p 0 %d\n", pPager, N))
+    rc = sqlite3OsRead(pPager->fd, pDest, N, 0);
+    if( rc==SQLITE_IOERR_SHORT_READ ){
+      rc = SQLITE_OK;
+    }
+  }
+  return rc;
+}
+
+/*
+** This function may only be called when a read-transaction is open on
+** the pager. It returns the total number of pages in the database.
+**
+** However, if the file is between 1 and <page-size> bytes in size, then 
+** this is considered a 1 page file.
+*/
+SQLITE_PRIVATE void sqlite3PagerPagecount(Pager *pPager, int *pnPage){
+  assert( pPager->eState>=PAGER_READER );
+  assert( pPager->eState!=PAGER_WRITER_FINISHED );
+  *pnPage = (int)pPager->dbSize;
+}
+
+
+/*
+** Try to obtain a lock of type locktype on the database file. If
+** a similar or greater lock is already held, this function is a no-op
+** (returning SQLITE_OK immediately).
+**
+** Otherwise, attempt to obtain the lock using sqlite3OsLock(). Invoke 
+** the busy callback if the lock is currently not available. Repeat 
+** until the busy callback returns false or until the attempt to 
+** obtain the lock succeeds.
+**
+** Return SQLITE_OK on success and an error code if we cannot obtain
+** the lock. If the lock is obtained successfully, set the Pager.state 
+** variable to locktype before returning.
+*/
+static int pager_wait_on_lock(Pager *pPager, int locktype){
+  int rc;                              /* Return code */
+
+  /* Check that this is either a no-op (because the requested lock is 
+  ** already held, or one of the transistions that the busy-handler
+  ** may be invoked during, according to the comment above
+  ** sqlite3PagerSetBusyhandler().
+  */
+  assert( (pPager->eLock>=locktype)
+       || (pPager->eLock==NO_LOCK && locktype==SHARED_LOCK)
+       || (pPager->eLock==RESERVED_LOCK && locktype==EXCLUSIVE_LOCK)
+  );
+
+  do {
+    rc = pagerLockDb(pPager, locktype);
+  }while( rc==SQLITE_BUSY && pPager->xBusyHandler(pPager->pBusyHandlerArg) );
+  return rc;
+}
+
+/*
+** Function assertTruncateConstraint(pPager) checks that one of the 
+** following is true for all dirty pages currently in the page-cache:
+**
+**   a) The page number is less than or equal to the size of the 
+**      current database image, in pages, OR
+**
+**   b) if the page content were written at this time, it would not
+**      be necessary to write the current content out to the sub-journal
+**      (as determined by function subjRequiresPage()).
+**
+** If the condition asserted by this function were not true, and the
+** dirty page were to be discarded from the cache via the pagerStress()
+** routine, pagerStress() would not write the current page content to
+** the database file. If a savepoint transaction were rolled back after
+** this happened, the correct behaviour would be to restore the current
+** content of the page. However, since this content is not present in either
+** the database file or the portion of the rollback journal and 
+** sub-journal rolled back the content could not be restored and the
+** database image would become corrupt. It is therefore fortunate that 
+** this circumstance cannot arise.
+*/
+#if defined(SQLITE_DEBUG)
+static void assertTruncateConstraintCb(PgHdr *pPg){
+  assert( pPg->flags&PGHDR_DIRTY );
+  assert( !subjRequiresPage(pPg) || pPg->pgno<=pPg->pPager->dbSize );
+}
+static void assertTruncateConstraint(Pager *pPager){
+  sqlite3PcacheIterateDirty(pPager->pPCache, assertTruncateConstraintCb);
+}
+#else
+# define assertTruncateConstraint(pPager)
+#endif
+
+/*
+** Truncate the in-memory database file image to nPage pages. This 
+** function does not actually modify the database file on disk. It 
+** just sets the internal state of the pager object so that the 
+** truncation will be done when the current transaction is committed.
+*/
+SQLITE_PRIVATE void sqlite3PagerTruncateImage(Pager *pPager, Pgno nPage){
+  assert( pPager->dbSize>=nPage );
+  assert( pPager->eState>=PAGER_WRITER_CACHEMOD );
+  pPager->dbSize = nPage;
+  assertTruncateConstraint(pPager);
+}
+
+
+/*
+** This function is called before attempting a hot-journal rollback. It
+** syncs the journal file to disk, then sets pPager->journalHdr to the
+** size of the journal file so that the pager_playback() routine knows
+** that the entire journal file has been synced.
+**
+** Syncing a hot-journal to disk before attempting to roll it back ensures 
+** that if a power-failure occurs during the rollback, the process that
+** attempts rollback following system recovery sees the same journal
+** content as this process.
+**
+** If everything goes as planned, SQLITE_OK is returned. Otherwise, 
+** an SQLite error code.
+*/
+static int pagerSyncHotJournal(Pager *pPager){
+  int rc = SQLITE_OK;
+  if( !pPager->noSync ){
+    rc = sqlite3OsSync(pPager->jfd, SQLITE_SYNC_NORMAL);
+  }
+  if( rc==SQLITE_OK ){
+    rc = sqlite3OsFileSize(pPager->jfd, &pPager->journalHdr);
+  }
+  return rc;
+}
+
+/*
+** Shutdown the page cache.  Free all memory and close all files.
+**
+** If a transaction was in progress when this routine is called, that
+** transaction is rolled back.  All outstanding pages are invalidated
+** and their memory is freed.  Any attempt to use a page associated
+** with this page cache after this function returns will likely
+** result in a coredump.
+**
+** This function always succeeds. If a transaction is active an attempt
+** is made to roll it back. If an error occurs during the rollback 
+** a hot journal may be left in the filesystem but no error is returned
+** to the caller.
+*/
+SQLITE_PRIVATE int sqlite3PagerClose(Pager *pPager){
+  u8 *pTmp = (u8 *)pPager->pTmpSpace;
+
+  disable_simulated_io_errors();
+  sqlite3BeginBenignMalloc();
+  /* pPager->errCode = 0; */
+  pPager->exclusiveMode = 0;
+#ifndef SQLITE_OMIT_WAL
+  sqlite3WalClose(pPager->pWal, pPager->ckptSyncFlags, pPager->pageSize, pTmp);
+  pPager->pWal = 0;
+#endif
+  pager_reset(pPager);
+  if( MEMDB ){
+    pager_unlock(pPager);
+  }else{
+    /* If it is open, sync the journal file before calling UnlockAndRollback.
+    ** If this is not done, then an unsynced portion of the open journal 
+    ** file may be played back into the database. If a power failure occurs 
+    ** while this is happening, the database could become corrupt.
+    **
+    ** If an error occurs while trying to sync the journal, shift the pager
+    ** into the ERROR state. This causes UnlockAndRollback to unlock the
+    ** database and close the journal file without attempting to roll it
+    ** back or finalize it. The next database user will have to do hot-journal
+    ** rollback before accessing the database file.
+    */
+    if( isOpen(pPager->jfd) ){
+      pager_error(pPager, pagerSyncHotJournal(pPager));
+    }
+    pagerUnlockAndRollback(pPager);
+  }
+  sqlite3EndBenignMalloc();
+  enable_simulated_io_errors();
+  PAGERTRACE(("CLOSE %d\n", PAGERID(pPager)));
+  IOTRACE(("CLOSE %p\n", pPager))
+  sqlite3OsClose(pPager->jfd);
+  sqlite3OsClose(pPager->fd);
+  sqlite3PageFree(pTmp);
+  sqlite3PcacheClose(pPager->pPCache);
+
+#ifdef SQLITE_HAS_CODEC
+  if( pPager->xCodecFree ) pPager->xCodecFree(pPager->pCodec);
+#endif
+
+  assert( !pPager->aSavepoint && !pPager->pInJournal );
+  assert( !isOpen(pPager->jfd) && !isOpen(pPager->sjfd) );
+
+  sqlite3_free(pPager);
+  return SQLITE_OK;
+}
+
+#if !defined(NDEBUG) || defined(SQLITE_TEST)
+/*
+** Return the page number for page pPg.
+*/
+SQLITE_PRIVATE Pgno sqlite3PagerPagenumber(DbPage *pPg){
+  return pPg->pgno;
+}
+#endif
+
+/*
+** Increment the reference count for page pPg.
+*/
+SQLITE_PRIVATE void sqlite3PagerRef(DbPage *pPg){
+  sqlite3PcacheRef(pPg);
+}
+
+/*
+** Sync the journal. In other words, make sure all the pages that have
+** been written to the journal have actually reached the surface of the
+** disk and can be restored in the event of a hot-journal rollback.
+**
+** If the Pager.noSync flag is set, then this function is a no-op.
+** Otherwise, the actions required depend on the journal-mode and the 
+** device characteristics of the the file-system, as follows:
+**
+**   * If the journal file is an in-memory journal file, no action need
+**     be taken.
+**
+**   * Otherwise, if the device does not support the SAFE_APPEND property,
+**     then the nRec field of the most recently written journal header
+**     is updated to contain the number of journal records that have
+**     been written following it. If the pager is operating in full-sync
+**     mode, then the journal file is synced before this field is updated.
+**
+**   * If the device does not support the SEQUENTIAL property, then 
+**     journal file is synced.
+**
+** Or, in pseudo-code:
+**
+**   if( NOT <in-memory journal> ){
+**     if( NOT SAFE_APPEND ){
+**       if( <full-sync mode> ) xSync(<journal file>);
+**       <update nRec field>
+**     } 
+**     if( NOT SEQUENTIAL ) xSync(<journal file>);
+**   }
+**
+** If successful, this routine clears the PGHDR_NEED_SYNC flag of every 
+** page currently held in memory before returning SQLITE_OK. If an IO
+** error is encountered, then the IO error code is returned to the caller.
+*/
+static int syncJournal(Pager *pPager, int newHdr){
+  int rc;                         /* Return code */
+
+  assert( pPager->eState==PAGER_WRITER_CACHEMOD
+       || pPager->eState==PAGER_WRITER_DBMOD
+  );
+  assert( assert_pager_state(pPager) );
+  assert( !pagerUseWal(pPager) );
+
+  rc = sqlite3PagerExclusiveLock(pPager);
+  if( rc!=SQLITE_OK ) return rc;
+
+  if( !pPager->noSync ){
+    assert( !pPager->tempFile );
+    if( isOpen(pPager->jfd) && pPager->journalMode!=PAGER_JOURNALMODE_MEMORY ){
+      const int iDc = sqlite3OsDeviceCharacteristics(pPager->fd);
+      assert( isOpen(pPager->jfd) );
+
+      if( 0==(iDc&SQLITE_IOCAP_SAFE_APPEND) ){
+        /* This block deals with an obscure problem. If the last connection
+        ** that wrote to this database was operating in persistent-journal
+        ** mode, then the journal file may at this point actually be larger
+        ** than Pager.journalOff bytes. If the next thing in the journal
+        ** file happens to be a journal-header (written as part of the
+        ** previous connection's transaction), and a crash or power-failure 
+        ** occurs after nRec is updated but before this connection writes 
+        ** anything else to the journal file (or commits/rolls back its 
+        ** transaction), then SQLite may become confused when doing the 
+        ** hot-journal rollback following recovery. It may roll back all
+        ** of this connections data, then proceed to rolling back the old,
+        ** out-of-date data that follows it. Database corruption.
+        **
+        ** To work around this, if the journal file does appear to contain
+        ** a valid header following Pager.journalOff, then write a 0x00
+        ** byte to the start of it to prevent it from being recognized.
+        **
+        ** Variable iNextHdrOffset is set to the offset at which this
+        ** problematic header will occur, if it exists. aMagic is used 
+        ** as a temporary buffer to inspect the first couple of bytes of
+        ** the potential journal header.
+        */
+        i64 iNextHdrOffset;
+        u8 aMagic[8];
+        u8 zHeader[sizeof(aJournalMagic)+4];
+
+        memcpy(zHeader, aJournalMagic, sizeof(aJournalMagic));
+        put32bits(&zHeader[sizeof(aJournalMagic)], pPager->nRec);
+
+        iNextHdrOffset = journalHdrOffset(pPager);
+        rc = sqlite3OsRead(pPager->jfd, aMagic, 8, iNextHdrOffset);
+        if( rc==SQLITE_OK && 0==memcmp(aMagic, aJournalMagic, 8) ){
+          static const u8 zerobyte = 0;
+          rc = sqlite3OsWrite(pPager->jfd, &zerobyte, 1, iNextHdrOffset);
+        }
+        if( rc!=SQLITE_OK && rc!=SQLITE_IOERR_SHORT_READ ){
+          return rc;
+        }
+
+        /* Write the nRec value into the journal file header. If in
+        ** full-synchronous mode, sync the journal first. This ensures that
+        ** all data has really hit the disk before nRec is updated to mark
+        ** it as a candidate for rollback.
+        **
+        ** This is not required if the persistent media supports the
+        ** SAFE_APPEND property. Because in this case it is not possible 
+        ** for garbage data to be appended to the file, the nRec field
+        ** is populated with 0xFFFFFFFF when the journal header is written
+        ** and never needs to be updated.
+        */
+        if( pPager->fullSync && 0==(iDc&SQLITE_IOCAP_SEQUENTIAL) ){
+          PAGERTRACE(("SYNC journal of %d\n", PAGERID(pPager)));
+          IOTRACE(("JSYNC %p\n", pPager))
+          rc = sqlite3OsSync(pPager->jfd, pPager->syncFlags);
+          if( rc!=SQLITE_OK ) return rc;
+        }
+        IOTRACE(("JHDR %p %lld\n", pPager, pPager->journalHdr));
+        rc = sqlite3OsWrite(
+            pPager->jfd, zHeader, sizeof(zHeader), pPager->journalHdr
+        );
+        if( rc!=SQLITE_OK ) return rc;
+      }
+      if( 0==(iDc&SQLITE_IOCAP_SEQUENTIAL) ){
+        PAGERTRACE(("SYNC journal of %d\n", PAGERID(pPager)));
+        IOTRACE(("JSYNC %p\n", pPager))
+        rc = sqlite3OsSync(pPager->jfd, pPager->syncFlags| 
+          (pPager->syncFlags==SQLITE_SYNC_FULL?SQLITE_SYNC_DATAONLY:0)
+        );
+        if( rc!=SQLITE_OK ) return rc;
+      }
+
+      pPager->journalHdr = pPager->journalOff;
+      if( newHdr && 0==(iDc&SQLITE_IOCAP_SAFE_APPEND) ){
+        pPager->nRec = 0;
+        rc = writeJournalHdr(pPager);
+        if( rc!=SQLITE_OK ) return rc;
+      }
+    }else{
+      pPager->journalHdr = pPager->journalOff;
+    }
+  }
+
+  /* Unless the pager is in noSync mode, the journal file was just 
+  ** successfully synced. Either way, clear the PGHDR_NEED_SYNC flag on 
+  ** all pages.
+  */
+  sqlite3PcacheClearSyncFlags(pPager->pPCache);
+  pPager->eState = PAGER_WRITER_DBMOD;
+  assert( assert_pager_state(pPager) );
+  return SQLITE_OK;
+}
+
+/*
+** The argument is the first in a linked list of dirty pages connected
+** by the PgHdr.pDirty pointer. This function writes each one of the
+** in-memory pages in the list to the database file. The argument may
+** be NULL, representing an empty list. In this case this function is
+** a no-op.
+**
+** The pager must hold at least a RESERVED lock when this function
+** is called. Before writing anything to the database file, this lock
+** is upgraded to an EXCLUSIVE lock. If the lock cannot be obtained,
+** SQLITE_BUSY is returned and no data is written to the database file.
+** 
+** If the pager is a temp-file pager and the actual file-system file
+** is not yet open, it is created and opened before any data is 
+** written out.
+**
+** Once the lock has been upgraded and, if necessary, the file opened,
+** the pages are written out to the database file in list order. Writing
+** a page is skipped if it meets either of the following criteria:
+**
+**   * The page number is greater than Pager.dbSize, or
+**   * The PGHDR_DONT_WRITE flag is set on the page.
+**
+** If writing out a page causes the database file to grow, Pager.dbFileSize
+** is updated accordingly. If page 1 is written out, then the value cached
+** in Pager.dbFileVers[] is updated to match the new value stored in
+** the database file.
+**
+** If everything is successful, SQLITE_OK is returned. If an IO error 
+** occurs, an IO error code is returned. Or, if the EXCLUSIVE lock cannot
+** be obtained, SQLITE_BUSY is returned.
+*/
+static int pager_write_pagelist(Pager *pPager, PgHdr *pList){
+  int rc = SQLITE_OK;                  /* Return code */
+
+  /* This function is only called for rollback pagers in WRITER_DBMOD state. */
+  assert( !pagerUseWal(pPager) );
+  assert( pPager->eState==PAGER_WRITER_DBMOD );
+  assert( pPager->eLock==EXCLUSIVE_LOCK );
+
+  /* If the file is a temp-file has not yet been opened, open it now. It
+  ** is not possible for rc to be other than SQLITE_OK if this branch
+  ** is taken, as pager_wait_on_lock() is a no-op for temp-files.
+  */
+  if( !isOpen(pPager->fd) ){
+    assert( pPager->tempFile && rc==SQLITE_OK );
+    rc = pagerOpentemp(pPager, pPager->fd, pPager->vfsFlags);
+  }
+
+  /* Before the first write, give the VFS a hint of what the final
+  ** file size will be.
+  */
+  assert( rc!=SQLITE_OK || isOpen(pPager->fd) );
+  if( rc==SQLITE_OK && pPager->dbSize>pPager->dbHintSize ){
+    sqlite3_int64 szFile = pPager->pageSize * (sqlite3_int64)pPager->dbSize;
+    sqlite3OsFileControl(pPager->fd, SQLITE_FCNTL_SIZE_HINT, &szFile);
+    pPager->dbHintSize = pPager->dbSize;
+  }
+
+  while( rc==SQLITE_OK && pList ){
+    Pgno pgno = pList->pgno;
+
+    /* If there are dirty pages in the page cache with page numbers greater
+    ** than Pager.dbSize, this means sqlite3PagerTruncateImage() was called to
+    ** make the file smaller (presumably by auto-vacuum code). Do not write
+    ** any such pages to the file.
+    **
+    ** Also, do not write out any page that has the PGHDR_DONT_WRITE flag
+    ** set (set by sqlite3PagerDontWrite()).
+    */
+    if( pgno<=pPager->dbSize && 0==(pList->flags&PGHDR_DONT_WRITE) ){
+      i64 offset = (pgno-1)*(i64)pPager->pageSize;   /* Offset to write */
+      char *pData;                                   /* Data to write */    
+
+      assert( (pList->flags&PGHDR_NEED_SYNC)==0 );
+      if( pList->pgno==1 ) pager_write_changecounter(pList);
+
+      /* Encode the database */
+      CODEC2(pPager, pList->pData, pgno, 6, return SQLITE_NOMEM, pData);
+
+      /* Write out the page data. */
+      rc = sqlite3OsWrite(pPager->fd, pData, pPager->pageSize, offset);
+
+      /* If page 1 was just written, update Pager.dbFileVers to match
+      ** the value now stored in the database file. If writing this 
+      ** page caused the database file to grow, update dbFileSize. 
+      */
+      if( pgno==1 ){
+        memcpy(&pPager->dbFileVers, &pData[24], sizeof(pPager->dbFileVers));
+      }
+      if( pgno>pPager->dbFileSize ){
+        pPager->dbFileSize = pgno;
+      }
+
+      /* Update any backup objects copying the contents of this pager. */
+      sqlite3BackupUpdate(pPager->pBackup, pgno, (u8*)pList->pData);
+
+      PAGERTRACE(("STORE %d page %d hash(%08x)\n",
+                   PAGERID(pPager), pgno, pager_pagehash(pList)));
+      IOTRACE(("PGOUT %p %d\n", pPager, pgno));
+      PAGER_INCR(sqlite3_pager_writedb_count);
+      PAGER_INCR(pPager->nWrite);
+    }else{
+      PAGERTRACE(("NOSTORE %d page %d\n", PAGERID(pPager), pgno));
+    }
+    pager_set_pagehash(pList);
+    pList = pList->pDirty;
+  }
+
+  return rc;
+}
+
+/*
+** Ensure that the sub-journal file is open. If it is already open, this 
+** function is a no-op.
+**
+** SQLITE_OK is returned if everything goes according to plan. An 
+** SQLITE_IOERR_XXX error code is returned if a call to sqlite3OsOpen() 
+** fails.
+*/
+static int openSubJournal(Pager *pPager){
+  int rc = SQLITE_OK;
+  if( !isOpen(pPager->sjfd) ){
+    if( pPager->journalMode==PAGER_JOURNALMODE_MEMORY || pPager->subjInMemory ){
+      sqlite3MemJournalOpen(pPager->sjfd);
+    }else{
+      rc = pagerOpentemp(pPager, pPager->sjfd, SQLITE_OPEN_SUBJOURNAL);
+    }
+  }
+  return rc;
+}
+
+/*
+** Append a record of the current state of page pPg to the sub-journal. 
+** It is the callers responsibility to use subjRequiresPage() to check 
+** that it is really required before calling this function.
+**
+** If successful, set the bit corresponding to pPg->pgno in the bitvecs
+** for all open savepoints before returning.
+**
+** This function returns SQLITE_OK if everything is successful, an IO
+** error code if the attempt to write to the sub-journal fails, or 
+** SQLITE_NOMEM if a malloc fails while setting a bit in a savepoint
+** bitvec.
+*/
+static int subjournalPage(PgHdr *pPg){
+  int rc = SQLITE_OK;
+  Pager *pPager = pPg->pPager;
+  if( pPager->journalMode!=PAGER_JOURNALMODE_OFF ){
+
+    /* Open the sub-journal, if it has not already been opened */
+    assert( pPager->useJournal );
+    assert( isOpen(pPager->jfd) || pagerUseWal(pPager) );
+    assert( isOpen(pPager->sjfd) || pPager->nSubRec==0 );
+    assert( pagerUseWal(pPager) 
+         || pageInJournal(pPg) 
+         || pPg->pgno>pPager->dbOrigSize 
+    );
+    rc = openSubJournal(pPager);
+
+    /* If the sub-journal was opened successfully (or was already open),
+    ** write the journal record into the file.  */
+    if( rc==SQLITE_OK ){
+      void *pData = pPg->pData;
+      i64 offset = pPager->nSubRec*(4+pPager->pageSize);
+      char *pData2;
+  
+      CODEC2(pPager, pData, pPg->pgno, 7, return SQLITE_NOMEM, pData2);
+      PAGERTRACE(("STMT-JOURNAL %d page %d\n", PAGERID(pPager), pPg->pgno));
+      rc = write32bits(pPager->sjfd, offset, pPg->pgno);
+      if( rc==SQLITE_OK ){
+        rc = sqlite3OsWrite(pPager->sjfd, pData2, pPager->pageSize, offset+4);
+      }
+    }
+  }
+  if( rc==SQLITE_OK ){
+    pPager->nSubRec++;
+    assert( pPager->nSavepoint>0 );
+    rc = addToSavepointBitvecs(pPager, pPg->pgno);
+  }
+  return rc;
+}
+
+/*
+** This function is called by the pcache layer when it has reached some
+** soft memory limit. The first argument is a pointer to a Pager object
+** (cast as a void*). The pager is always 'purgeable' (not an in-memory
+** database). The second argument is a reference to a page that is 
+** currently dirty but has no outstanding references. The page
+** is always associated with the Pager object passed as the first 
+** argument.
+**
+** The job of this function is to make pPg clean by writing its contents
+** out to the database file, if possible. This may involve syncing the
+** journal file. 
+**
+** If successful, sqlite3PcacheMakeClean() is called on the page and
+** SQLITE_OK returned. If an IO error occurs while trying to make the
+** page clean, the IO error code is returned. If the page cannot be
+** made clean for some other reason, but no error occurs, then SQLITE_OK
+** is returned by sqlite3PcacheMakeClean() is not called.
+*/
+static int pagerStress(void *p, PgHdr *pPg){
+  Pager *pPager = (Pager *)p;
+  int rc = SQLITE_OK;
+
+  assert( pPg->pPager==pPager );
+  assert( pPg->flags&PGHDR_DIRTY );
+
+  /* The doNotSyncSpill flag is set during times when doing a sync of
+  ** journal (and adding a new header) is not allowed.  This occurs
+  ** during calls to sqlite3PagerWrite() while trying to journal multiple
+  ** pages belonging to the same sector.
+  **
+  ** The doNotSpill flag inhibits all cache spilling regardless of whether
+  ** or not a sync is required.  This is set during a rollback.
+  **
+  ** Spilling is also prohibited when in an error state since that could
+  ** lead to database corruption.   In the current implementaton it 
+  ** is impossible for sqlite3PCacheFetch() to be called with createFlag==1
+  ** while in the error state, hence it is impossible for this routine to
+  ** be called in the error state.  Nevertheless, we include a NEVER()
+  ** test for the error state as a safeguard against future changes.
+  */
+  if( NEVER(pPager->errCode) ) return SQLITE_OK;
+  if( pPager->doNotSpill ) return SQLITE_OK;
+  if( pPager->doNotSyncSpill && (pPg->flags & PGHDR_NEED_SYNC)!=0 ){
+    return SQLITE_OK;
+  }
+
+  pPg->pDirty = 0;
+  if( pagerUseWal(pPager) ){
+    /* Write a single frame for this page to the log. */
+    if( subjRequiresPage(pPg) ){ 
+      rc = subjournalPage(pPg); 
+    }
+    if( rc==SQLITE_OK ){
+      rc = pagerWalFrames(pPager, pPg, 0, 0, 0);
+    }
+  }else{
+  
+    /* Sync the journal file if required. */
+    if( pPg->flags&PGHDR_NEED_SYNC 
+     || pPager->eState==PAGER_WRITER_CACHEMOD
+    ){
+      rc = syncJournal(pPager, 1);
+    }
+  
+    /* If the page number of this page is larger than the current size of
+    ** the database image, it may need to be written to the sub-journal.
+    ** This is because the call to pager_write_pagelist() below will not
+    ** actually write data to the file in this case.
+    **
+    ** Consider the following sequence of events:
+    **
+    **   BEGIN;
+    **     <journal page X>
+    **     <modify page X>
+    **     SAVEPOINT sp;
+    **       <shrink database file to Y pages>
+    **       pagerStress(page X)
+    **     ROLLBACK TO sp;
+    **
+    ** If (X>Y), then when pagerStress is called page X will not be written
+    ** out to the database file, but will be dropped from the cache. Then,
+    ** following the "ROLLBACK TO sp" statement, reading page X will read
+    ** data from the database file. This will be the copy of page X as it
+    ** was when the transaction started, not as it was when "SAVEPOINT sp"
+    ** was executed.
+    **
+    ** The solution is to write the current data for page X into the 
+    ** sub-journal file now (if it is not already there), so that it will
+    ** be restored to its current value when the "ROLLBACK TO sp" is 
+    ** executed.
+    */
+    if( NEVER(
+        rc==SQLITE_OK && pPg->pgno>pPager->dbSize && subjRequiresPage(pPg)
+    ) ){
+      rc = subjournalPage(pPg);
+    }
+  
+    /* Write the contents of the page out to the database file. */
+    if( rc==SQLITE_OK ){
+      assert( (pPg->flags&PGHDR_NEED_SYNC)==0 );
+      rc = pager_write_pagelist(pPager, pPg);
+    }
+  }
+
+  /* Mark the page as clean. */
+  if( rc==SQLITE_OK ){
+    PAGERTRACE(("STRESS %d page %d\n", PAGERID(pPager), pPg->pgno));
+    sqlite3PcacheMakeClean(pPg);
+  }
+
+  return pager_error(pPager, rc); 
+}
+
+
+/*
+** Allocate and initialize a new Pager object and put a pointer to it
+** in *ppPager. The pager should eventually be freed by passing it
+** to sqlite3PagerClose().
+**
+** The zFilename argument is the path to the database file to open.
+** If zFilename is NULL then a randomly-named temporary file is created
+** and used as the file to be cached. Temporary files are be deleted
+** automatically when they are closed. If zFilename is ":memory:" then 
+** all information is held in cache. It is never written to disk. 
+** This can be used to implement an in-memory database.
+**
+** The nExtra parameter specifies the number of bytes of space allocated
+** along with each page reference. This space is available to the user
+** via the sqlite3PagerGetExtra() API.
+**
+** The flags argument is used to specify properties that affect the
+** operation of the pager. It should be passed some bitwise combination
+** of the PAGER_OMIT_JOURNAL and PAGER_NO_READLOCK flags.
+**
+** The vfsFlags parameter is a bitmask to pass to the flags parameter
+** of the xOpen() method of the supplied VFS when opening files. 
+**
+** If the pager object is allocated and the specified file opened 
+** successfully, SQLITE_OK is returned and *ppPager set to point to
+** the new pager object. If an error occurs, *ppPager is set to NULL
+** and error code returned. This function may return SQLITE_NOMEM
+** (sqlite3Malloc() is used to allocate memory), SQLITE_CANTOPEN or 
+** various SQLITE_IO_XXX errors.
+*/
+SQLITE_PRIVATE int sqlite3PagerOpen(
+  sqlite3_vfs *pVfs,       /* The virtual file system to use */
+  Pager **ppPager,         /* OUT: Return the Pager structure here */
+  const char *zFilename,   /* Name of the database file to open */
+  int nExtra,              /* Extra bytes append to each in-memory page */
+  int flags,               /* flags controlling this file */
+  int vfsFlags,            /* flags passed through to sqlite3_vfs.xOpen() */
+  void (*xReinit)(DbPage*) /* Function to reinitialize pages */
+){
+  u8 *pPtr;
+  Pager *pPager = 0;       /* Pager object to allocate and return */
+  int rc = SQLITE_OK;      /* Return code */
+  int tempFile = 0;        /* True for temp files (incl. in-memory files) */
+  int memDb = 0;           /* True if this is an in-memory file */
+  int readOnly = 0;        /* True if this is a read-only file */
+  int journalFileSize;     /* Bytes to allocate for each journal fd */
+  char *zPathname = 0;     /* Full path to database file */
+  int nPathname = 0;       /* Number of bytes in zPathname */
+  int useJournal = (flags & PAGER_OMIT_JOURNAL)==0; /* False to omit journal */
+  int noReadlock = (flags & PAGER_NO_READLOCK)!=0;  /* True to omit read-lock */
+  int pcacheSize = sqlite3PcacheSize();       /* Bytes to allocate for PCache */
+  u32 szPageDflt = SQLITE_DEFAULT_PAGE_SIZE;  /* Default page size */
+
+  /* Figure out how much space is required for each journal file-handle
+  ** (there are two of them, the main journal and the sub-journal). This
+  ** is the maximum space required for an in-memory journal file handle 
+  ** and a regular journal file-handle. Note that a "regular journal-handle"
+  ** may be a wrapper capable of caching the first portion of the journal
+  ** file in memory to implement the atomic-write optimization (see 
+  ** source file journal.c).
+  */
+  if( sqlite3JournalSize(pVfs)>sqlite3MemJournalSize() ){
+    journalFileSize = ROUND8(sqlite3JournalSize(pVfs));
+  }else{
+    journalFileSize = ROUND8(sqlite3MemJournalSize());
+  }
+
+  /* Set the output variable to NULL in case an error occurs. */
+  *ppPager = 0;
+
+#ifndef SQLITE_OMIT_MEMORYDB
+  if( flags & PAGER_MEMORY ){
+    memDb = 1;
+    zFilename = 0;
+  }
+#endif
+
+  /* Compute and store the full pathname in an allocated buffer pointed
+  ** to by zPathname, length nPathname. Or, if this is a temporary file,
+  ** leave both nPathname and zPathname set to 0.
+  */
+  if( zFilename && zFilename[0] ){
+    nPathname = pVfs->mxPathname+1;
+    zPathname = sqlite3Malloc(nPathname*2);
+    if( zPathname==0 ){
+      return SQLITE_NOMEM;
+    }
+    zPathname[0] = 0; /* Make sure initialized even if FullPathname() fails */
+    rc = sqlite3OsFullPathname(pVfs, zFilename, nPathname, zPathname);
+    nPathname = sqlite3Strlen30(zPathname);
+    if( rc==SQLITE_OK && nPathname+8>pVfs->mxPathname ){
+      /* This branch is taken when the journal path required by
+      ** the database being opened will be more than pVfs->mxPathname
+      ** bytes in length. This means the database cannot be opened,
+      ** as it will not be possible to open the journal file or even
+      ** check for a hot-journal before reading.
+      */
+      rc = SQLITE_CANTOPEN_BKPT;
+    }
+    if( rc!=SQLITE_OK ){
+      sqlite3_free(zPathname);
+      return rc;
+    }
+  }
+
+  /* Allocate memory for the Pager structure, PCache object, the
+  ** three file descriptors, the database file name and the journal 
+  ** file name. The layout in memory is as follows:
+  **
+  **     Pager object                    (sizeof(Pager) bytes)
+  **     PCache object                   (sqlite3PcacheSize() bytes)
+  **     Database file handle            (pVfs->szOsFile bytes)
+  **     Sub-journal file handle         (journalFileSize bytes)
+  **     Main journal file handle        (journalFileSize bytes)
+  **     Database file name              (nPathname+1 bytes)
+  **     Journal file name               (nPathname+8+1 bytes)
+  */
+  pPtr = (u8 *)sqlite3MallocZero(
+    ROUND8(sizeof(*pPager)) +      /* Pager structure */
+    ROUND8(pcacheSize) +           /* PCache object */
+    ROUND8(pVfs->szOsFile) +       /* The main db file */
+    journalFileSize * 2 +          /* The two journal files */ 
+    nPathname + 1 +                /* zFilename */
+    nPathname + 8 + 1              /* zJournal */
+#ifndef SQLITE_OMIT_WAL
+    + nPathname + 4 + 1              /* zWal */
+#endif
+  );
+  assert( EIGHT_BYTE_ALIGNMENT(SQLITE_INT_TO_PTR(journalFileSize)) );
+  if( !pPtr ){
+    sqlite3_free(zPathname);
+    return SQLITE_NOMEM;
+  }
+  pPager =              (Pager*)(pPtr);
+  pPager->pPCache =    (PCache*)(pPtr += ROUND8(sizeof(*pPager)));
+  pPager->fd =   (sqlite3_file*)(pPtr += ROUND8(pcacheSize));
+  pPager->sjfd = (sqlite3_file*)(pPtr += ROUND8(pVfs->szOsFile));
+  pPager->jfd =  (sqlite3_file*)(pPtr += journalFileSize);
+  pPager->zFilename =    (char*)(pPtr += journalFileSize);
+  assert( EIGHT_BYTE_ALIGNMENT(pPager->jfd) );
+
+  /* Fill in the Pager.zFilename and Pager.zJournal buffers, if required. */
+  if( zPathname ){
+    assert( nPathname>0 );
+    pPager->zJournal =   (char*)(pPtr += nPathname + 1);
+    memcpy(pPager->zFilename, zPathname, nPathname);
+    memcpy(pPager->zJournal, zPathname, nPathname);
+    memcpy(&pPager->zJournal[nPathname], "-journal", 8);
+#ifndef SQLITE_OMIT_WAL
+    pPager->zWal = &pPager->zJournal[nPathname+8+1];
+    memcpy(pPager->zWal, zPathname, nPathname);
+    memcpy(&pPager->zWal[nPathname], "-wal", 4);
+#endif
+    sqlite3_free(zPathname);
+  }
+  pPager->pVfs = pVfs;
+  pPager->vfsFlags = vfsFlags;
+
+  /* Open the pager file.
+  */
+  if( zFilename && zFilename[0] ){
+    int fout = 0;                    /* VFS flags returned by xOpen() */
+    rc = sqlite3OsOpen(pVfs, pPager->zFilename, pPager->fd, vfsFlags, &fout);
+    assert( !memDb );
+    readOnly = (fout&SQLITE_OPEN_READONLY);
+
+    /* If the file was successfully opened for read/write access,
+    ** choose a default page size in case we have to create the
+    ** database file. The default page size is the maximum of:
+    **
+    **    + SQLITE_DEFAULT_PAGE_SIZE,
+    **    + The value returned by sqlite3OsSectorSize()
+    **    + The largest page size that can be written atomically.
+    */
+    if( rc==SQLITE_OK && !readOnly ){
+      setSectorSize(pPager);
+      assert(SQLITE_DEFAULT_PAGE_SIZE<=SQLITE_MAX_DEFAULT_PAGE_SIZE);
+      if( szPageDflt<pPager->sectorSize ){
+        if( pPager->sectorSize>SQLITE_MAX_DEFAULT_PAGE_SIZE ){
+          szPageDflt = SQLITE_MAX_DEFAULT_PAGE_SIZE;
+        }else{
+          szPageDflt = (u32)pPager->sectorSize;
+        }
+      }
+#ifdef SQLITE_ENABLE_ATOMIC_WRITE
+      {
+        int iDc = sqlite3OsDeviceCharacteristics(pPager->fd);
+        int ii;
+        assert(SQLITE_IOCAP_ATOMIC512==(512>>8));
+        assert(SQLITE_IOCAP_ATOMIC64K==(65536>>8));
+        assert(SQLITE_MAX_DEFAULT_PAGE_SIZE<=65536);
+        for(ii=szPageDflt; ii<=SQLITE_MAX_DEFAULT_PAGE_SIZE; ii=ii*2){
+          if( iDc&(SQLITE_IOCAP_ATOMIC|(ii>>8)) ){
+            szPageDflt = ii;
+          }
+        }
+      }
+#endif
+    }
+  }else{
+    /* If a temporary file is requested, it is not opened immediately.
+    ** In this case we accept the default page size and delay actually
+    ** opening the file until the first call to OsWrite().
+    **
+    ** This branch is also run for an in-memory database. An in-memory
+    ** database is the same as a temp-file that is never written out to
+    ** disk and uses an in-memory rollback journal.
+    */ 
+    tempFile = 1;
+    pPager->eState = PAGER_READER;
+    pPager->eLock = EXCLUSIVE_LOCK;
+    readOnly = (vfsFlags&SQLITE_OPEN_READONLY);
+  }
+
+  /* The following call to PagerSetPagesize() serves to set the value of 
+  ** Pager.pageSize and to allocate the Pager.pTmpSpace buffer.
+  */
+  if( rc==SQLITE_OK ){
+    assert( pPager->memDb==0 );
+    rc = sqlite3PagerSetPagesize(pPager, &szPageDflt, -1);
+    testcase( rc!=SQLITE_OK );
+  }
+
+  /* If an error occurred in either of the blocks above, free the 
+  ** Pager structure and close the file.
+  */
+  if( rc!=SQLITE_OK ){
+    assert( !pPager->pTmpSpace );
+    sqlite3OsClose(pPager->fd);
+    sqlite3_free(pPager);
+    return rc;
+  }
+
+  /* Initialize the PCache object. */
+  assert( nExtra<1000 );
+  nExtra = ROUND8(nExtra);
+  sqlite3PcacheOpen(szPageDflt, nExtra, !memDb,
+                    !memDb?pagerStress:0, (void *)pPager, pPager->pPCache);
+
+  PAGERTRACE(("OPEN %d %s\n", FILEHANDLEID(pPager->fd), pPager->zFilename));
+  IOTRACE(("OPEN %p %s\n", pPager, pPager->zFilename))
+
+  pPager->useJournal = (u8)useJournal;
+  pPager->noReadlock = (noReadlock && readOnly) ?1:0;
+  /* pPager->stmtOpen = 0; */
+  /* pPager->stmtInUse = 0; */
+  /* pPager->nRef = 0; */
+  /* pPager->stmtSize = 0; */
+  /* pPager->stmtJSize = 0; */
+  /* pPager->nPage = 0; */
+  pPager->mxPgno = SQLITE_MAX_PAGE_COUNT;
+  /* pPager->state = PAGER_UNLOCK; */
+#if 0
+  assert( pPager->state == (tempFile ? PAGER_EXCLUSIVE : PAGER_UNLOCK) );
+#endif
+  /* pPager->errMask = 0; */
+  pPager->tempFile = (u8)tempFile;
+  assert( tempFile==PAGER_LOCKINGMODE_NORMAL 
+          || tempFile==PAGER_LOCKINGMODE_EXCLUSIVE );
+  assert( PAGER_LOCKINGMODE_EXCLUSIVE==1 );
+  pPager->exclusiveMode = (u8)tempFile; 
+  pPager->changeCountDone = pPager->tempFile;
+  pPager->memDb = (u8)memDb;
+  pPager->readOnly = (u8)readOnly;
+  assert( useJournal || pPager->tempFile );
+  pPager->noSync = pPager->tempFile;
+  pPager->fullSync = pPager->noSync ?0:1;
+  pPager->syncFlags = pPager->noSync ? 0 : SQLITE_SYNC_NORMAL;
+  pPager->ckptSyncFlags = pPager->syncFlags;
+  /* pPager->pFirst = 0; */
+  /* pPager->pFirstSynced = 0; */
+  /* pPager->pLast = 0; */
+  pPager->nExtra = (u16)nExtra;
+  pPager->journalSizeLimit = SQLITE_DEFAULT_JOURNAL_SIZE_LIMIT;
+  assert( isOpen(pPager->fd) || tempFile );
+  setSectorSize(pPager);
+  if( !useJournal ){
+    pPager->journalMode = PAGER_JOURNALMODE_OFF;
+  }else if( memDb ){
+    pPager->journalMode = PAGER_JOURNALMODE_MEMORY;
+  }
+  /* pPager->xBusyHandler = 0; */
+  /* pPager->pBusyHandlerArg = 0; */
+  pPager->xReiniter = xReinit;
+  /* memset(pPager->aHash, 0, sizeof(pPager->aHash)); */
+
+  *ppPager = pPager;
+  return SQLITE_OK;
+}
+
+
+
+/*
+** This function is called after transitioning from PAGER_UNLOCK to
+** PAGER_SHARED state. It tests if there is a hot journal present in
+** the file-system for the given pager. A hot journal is one that 
+** needs to be played back. According to this function, a hot-journal
+** file exists if the following criteria are met:
+**
+**   * The journal file exists in the file system, and
+**   * No process holds a RESERVED or greater lock on the database file, and
+**   * The database file itself is greater than 0 bytes in size, and
+**   * The first byte of the journal file exists and is not 0x00.
+**
+** If the current size of the database file is 0 but a journal file
+** exists, that is probably an old journal left over from a prior
+** database with the same name. In this case the journal file is
+** just deleted using OsDelete, *pExists is set to 0 and SQLITE_OK
+** is returned.
+**
+** This routine does not check if there is a master journal filename
+** at the end of the file. If there is, and that master journal file
+** does not exist, then the journal file is not really hot. In this
+** case this routine will return a false-positive. The pager_playback()
+** routine will discover that the journal file is not really hot and 
+** will not roll it back. 
+**
+** If a hot-journal file is found to exist, *pExists is set to 1 and 
+** SQLITE_OK returned. If no hot-journal file is present, *pExists is
+** set to 0 and SQLITE_OK returned. If an IO error occurs while trying
+** to determine whether or not a hot-journal file exists, the IO error
+** code is returned and the value of *pExists is undefined.
+*/
+static int hasHotJournal(Pager *pPager, int *pExists){
+  sqlite3_vfs * const pVfs = pPager->pVfs;
+  int rc = SQLITE_OK;           /* Return code */
+  int exists = 1;               /* True if a journal file is present */
+  int jrnlOpen = !!isOpen(pPager->jfd);
+
+  assert( pPager->useJournal );
+  assert( isOpen(pPager->fd) );
+  assert( pPager->eState==PAGER_OPEN );
+
+  assert( jrnlOpen==0 || ( sqlite3OsDeviceCharacteristics(pPager->jfd) &
+    SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN
+  ));
+
+  *pExists = 0;
+  if( !jrnlOpen ){
+    rc = sqlite3OsAccess(pVfs, pPager->zJournal, SQLITE_ACCESS_EXISTS, &exists);
+  }
+  if( rc==SQLITE_OK && exists ){
+    int locked = 0;             /* True if some process holds a RESERVED lock */
+
+    /* Race condition here:  Another process might have been holding the
+    ** the RESERVED lock and have a journal open at the sqlite3OsAccess() 
+    ** call above, but then delete the journal and drop the lock before
+    ** we get to the following sqlite3OsCheckReservedLock() call.  If that
+    ** is the case, this routine might think there is a hot journal when
+    ** in fact there is none.  This results in a false-positive which will
+    ** be dealt with by the playback routine.  Ticket #3883.
+    */
+    rc = sqlite3OsCheckReservedLock(pPager->fd, &locked);
+    if( rc==SQLITE_OK && !locked ){
+      Pgno nPage;                 /* Number of pages in database file */
+
+      /* Check the size of the database file. If it consists of 0 pages,
+      ** then delete the journal file. See the header comment above for 
+      ** the reasoning here.  Delete the obsolete journal file under
+      ** a RESERVED lock to avoid race conditions and to avoid violating
+      ** [H33020].
+      */
+      rc = pagerPagecount(pPager, &nPage);
+      if( rc==SQLITE_OK ){
+        if( nPage==0 ){
+          sqlite3BeginBenignMalloc();
+          if( pagerLockDb(pPager, RESERVED_LOCK)==SQLITE_OK ){
+            sqlite3OsDelete(pVfs, pPager->zJournal, 0);
+            if( !pPager->exclusiveMode ) pagerUnlockDb(pPager, SHARED_LOCK);
+          }
+          sqlite3EndBenignMalloc();
+        }else{
+          /* The journal file exists and no other connection has a reserved
+          ** or greater lock on the database file. Now check that there is
+          ** at least one non-zero bytes at the start of the journal file.
+          ** If there is, then we consider this journal to be hot. If not, 
+          ** it can be ignored.
+          */
+          if( !jrnlOpen ){
+            int f = SQLITE_OPEN_READONLY|SQLITE_OPEN_MAIN_JOURNAL;
+            rc = sqlite3OsOpen(pVfs, pPager->zJournal, pPager->jfd, f, &f);
+          }
+          if( rc==SQLITE_OK ){
+            u8 first = 0;
+            rc = sqlite3OsRead(pPager->jfd, (void *)&first, 1, 0);
+            if( rc==SQLITE_IOERR_SHORT_READ ){
+              rc = SQLITE_OK;
+            }
+            if( !jrnlOpen ){
+              sqlite3OsClose(pPager->jfd);
+            }
+            *pExists = (first!=0);
+          }else if( rc==SQLITE_CANTOPEN ){
+            /* If we cannot open the rollback journal file in order to see if
+            ** its has a zero header, that might be due to an I/O error, or
+            ** it might be due to the race condition described above and in
+            ** ticket #3883.  Either way, assume that the journal is hot.
+            ** This might be a false positive.  But if it is, then the
+            ** automatic journal playback and recovery mechanism will deal
+            ** with it under an EXCLUSIVE lock where we do not need to
+            ** worry so much with race conditions.
+            */
+            *pExists = 1;
+            rc = SQLITE_OK;
+          }
+        }
+      }
+    }
+  }
+
+  return rc;
+}
+
+/*
+** This function is called to obtain a shared lock on the database file.
+** It is illegal to call sqlite3PagerAcquire() until after this function
+** has been successfully called. If a shared-lock is already held when
+** this function is called, it is a no-op.
+**
+** The following operations are also performed by this function.
+**
+**   1) If the pager is currently in PAGER_OPEN state (no lock held
+**      on the database file), then an attempt is made to obtain a
+**      SHARED lock on the database file. Immediately after obtaining
+**      the SHARED lock, the file-system is checked for a hot-journal,
+**      which is played back if present. Following any hot-journal 
+**      rollback, the contents of the cache are validated by checking
+**      the 'change-counter' field of the database file header and
+**      discarded if they are found to be invalid.
+**
+**   2) If the pager is running in exclusive-mode, and there are currently
+**      no outstanding references to any pages, and is in the error state,
+**      then an attempt is made to clear the error state by discarding
+**      the contents of the page cache and rolling back any open journal
+**      file.
+**
+** If everything is successful, SQLITE_OK is returned. If an IO error 
+** occurs while locking the database, checking for a hot-journal file or 
+** rolling back a journal file, the IO error code is returned.
+*/
+SQLITE_PRIVATE int sqlite3PagerSharedLock(Pager *pPager){
+  int rc = SQLITE_OK;                /* Return code */
+
+  /* This routine is only called from b-tree and only when there are no
+  ** outstanding pages. This implies that the pager state should either
+  ** be OPEN or READER. READER is only possible if the pager is or was in 
+  ** exclusive access mode.
+  */
+  assert( sqlite3PcacheRefCount(pPager->pPCache)==0 );
+  assert( assert_pager_state(pPager) );
+  assert( pPager->eState==PAGER_OPEN || pPager->eState==PAGER_READER );
+  if( NEVER(MEMDB && pPager->errCode) ){ return pPager->errCode; }
+
+  if( !pagerUseWal(pPager) && pPager->eState==PAGER_OPEN ){
+    int bHotJournal = 1;          /* True if there exists a hot journal-file */
+
+    assert( !MEMDB );
+    assert( pPager->noReadlock==0 || pPager->readOnly );
+
+    if( pPager->noReadlock==0 ){
+      rc = pager_wait_on_lock(pPager, SHARED_LOCK);
+      if( rc!=SQLITE_OK ){
+        assert( pPager->eLock==NO_LOCK || pPager->eLock==UNKNOWN_LOCK );
+        goto failed;
+      }
+    }
+
+    /* If a journal file exists, and there is no RESERVED lock on the
+    ** database file, then it either needs to be played back or deleted.
+    */
+    if( pPager->eLock<=SHARED_LOCK ){
+      rc = hasHotJournal(pPager, &bHotJournal);
+    }
+    if( rc!=SQLITE_OK ){
+      goto failed;
+    }
+    if( bHotJournal ){
+      /* Get an EXCLUSIVE lock on the database file. At this point it is
+      ** important that a RESERVED lock is not obtained on the way to the
+      ** EXCLUSIVE lock. If it were, another process might open the
+      ** database file, detect the RESERVED lock, and conclude that the
+      ** database is safe to read while this process is still rolling the 
+      ** hot-journal back.
+      ** 
+      ** Because the intermediate RESERVED lock is not requested, any
+      ** other process attempting to access the database file will get to 
+      ** this point in the code and fail to obtain its own EXCLUSIVE lock 
+      ** on the database file.
+      **
+      ** Unless the pager is in locking_mode=exclusive mode, the lock is
+      ** downgraded to SHARED_LOCK before this function returns.
+      */
+      rc = pagerLockDb(pPager, EXCLUSIVE_LOCK);
+      if( rc!=SQLITE_OK ){
+        goto failed;
+      }
+ 
+      /* If it is not already open and the file exists on disk, open the 
+      ** journal for read/write access. Write access is required because 
+      ** in exclusive-access mode the file descriptor will be kept open 
+      ** and possibly used for a transaction later on. Also, write-access 
+      ** is usually required to finalize the journal in journal_mode=persist 
+      ** mode (and also for journal_mode=truncate on some systems).
+      **
+      ** If the journal does not exist, it usually means that some 
+      ** other connection managed to get in and roll it back before 
+      ** this connection obtained the exclusive lock above. Or, it 
+      ** may mean that the pager was in the error-state when this
+      ** function was called and the journal file does not exist.
+      */
+      if( !isOpen(pPager->jfd) ){
+        sqlite3_vfs * const pVfs = pPager->pVfs;
+        int bExists;              /* True if journal file exists */
+        rc = sqlite3OsAccess(
+            pVfs, pPager->zJournal, SQLITE_ACCESS_EXISTS, &bExists);
+        if( rc==SQLITE_OK && bExists ){
+          int fout = 0;
+          int f = SQLITE_OPEN_READWRITE|SQLITE_OPEN_MAIN_JOURNAL;
+          assert( !pPager->tempFile );
+          rc = sqlite3OsOpen(pVfs, pPager->zJournal, pPager->jfd, f, &fout);
+          assert( rc!=SQLITE_OK || isOpen(pPager->jfd) );
+          if( rc==SQLITE_OK && fout&SQLITE_OPEN_READONLY ){
+            rc = SQLITE_CANTOPEN_BKPT;
+            sqlite3OsClose(pPager->jfd);
+          }
+        }
+      }
+ 
+      /* Playback and delete the journal.  Drop the database write
+      ** lock and reacquire the read lock. Purge the cache before
+      ** playing back the hot-journal so that we don't end up with
+      ** an inconsistent cache.  Sync the hot journal before playing
+      ** it back since the process that crashed and left the hot journal
+      ** probably did not sync it and we are required to always sync
+      ** the journal before playing it back.
+      */
+      if( isOpen(pPager->jfd) ){
+        assert( rc==SQLITE_OK );
+        rc = pagerSyncHotJournal(pPager);
+        if( rc==SQLITE_OK ){
+          rc = pager_playback(pPager, 1);
+          pPager->eState = PAGER_OPEN;
+        }
+      }else if( !pPager->exclusiveMode ){
+        pagerUnlockDb(pPager, SHARED_LOCK);
+      }
+
+      if( rc!=SQLITE_OK ){
+        /* This branch is taken if an error occurs while trying to open
+        ** or roll back a hot-journal while holding an EXCLUSIVE lock. The
+        ** pager_unlock() routine will be called before returning to unlock
+        ** the file. If the unlock attempt fails, then Pager.eLock must be
+        ** set to UNKNOWN_LOCK (see the comment above the #define for 
+        ** UNKNOWN_LOCK above for an explanation). 
+        **
+        ** In order to get pager_unlock() to do this, set Pager.eState to
+        ** PAGER_ERROR now. This is not actually counted as a transition
+        ** to ERROR state in the state diagram at the top of this file,
+        ** since we know that the same call to pager_unlock() will very
+        ** shortly transition the pager object to the OPEN state. Calling
+        ** assert_pager_state() would fail now, as it should not be possible
+        ** to be in ERROR state when there are zero outstanding page 
+        ** references.
+        */
+        pager_error(pPager, rc);
+        goto failed;
+      }
+
+      assert( pPager->eState==PAGER_OPEN );
+      assert( (pPager->eLock==SHARED_LOCK)
+           || (pPager->exclusiveMode && pPager->eLock>SHARED_LOCK)
+      );
+    }
+
+    if( !pPager->tempFile 
+     && (pPager->pBackup || sqlite3PcachePagecount(pPager->pPCache)>0) 
+    ){
+      /* The shared-lock has just been acquired on the database file
+      ** and there are already pages in the cache (from a previous
+      ** read or write transaction).  Check to see if the database
+      ** has been modified.  If the database has changed, flush the
+      ** cache.
+      **
+      ** Database changes is detected by looking at 15 bytes beginning
+      ** at offset 24 into the file.  The first 4 of these 16 bytes are
+      ** a 32-bit counter that is incremented with each change.  The
+      ** other bytes change randomly with each file change when
+      ** a codec is in use.
+      ** 
+      ** There is a vanishingly small chance that a change will not be 
+      ** detected.  The chance of an undetected change is so small that
+      ** it can be neglected.
+      */
+      Pgno nPage = 0;
+      char dbFileVers[sizeof(pPager->dbFileVers)];
+
+      rc = pagerPagecount(pPager, &nPage);
+      if( rc ) goto failed;
+
+      if( nPage>0 ){
+        IOTRACE(("CKVERS %p %d\n", pPager, sizeof(dbFileVers)));
+        rc = sqlite3OsRead(pPager->fd, &dbFileVers, sizeof(dbFileVers), 24);
+        if( rc!=SQLITE_OK ){
+          goto failed;
+        }
+      }else{
+        memset(dbFileVers, 0, sizeof(dbFileVers));
+      }
+
+      if( memcmp(pPager->dbFileVers, dbFileVers, sizeof(dbFileVers))!=0 ){
+        pager_reset(pPager);
+      }
+    }
+
+    /* If there is a WAL file in the file-system, open this database in WAL
+    ** mode. Otherwise, the following function call is a no-op.
+    */
+    rc = pagerOpenWalIfPresent(pPager);
+#ifndef SQLITE_OMIT_WAL
+    assert( pPager->pWal==0 || rc==SQLITE_OK );
+#endif
+  }
+
+  if( pagerUseWal(pPager) ){
+    assert( rc==SQLITE_OK );
+    rc = pagerBeginReadTransaction(pPager);
+  }
+
+  if( pPager->eState==PAGER_OPEN && rc==SQLITE_OK ){
+    rc = pagerPagecount(pPager, &pPager->dbSize);
+  }
+
+ failed:
+  if( rc!=SQLITE_OK ){
+    assert( !MEMDB );
+    pager_unlock(pPager);
+    assert( pPager->eState==PAGER_OPEN );
+  }else{
+    pPager->eState = PAGER_READER;
+  }
+  return rc;
+}
+
+/*
+** If the reference count has reached zero, rollback any active
+** transaction and unlock the pager.
+**
+** Except, in locking_mode=EXCLUSIVE when there is nothing to in
+** the rollback journal, the unlock is not performed and there is
+** nothing to rollback, so this routine is a no-op.
+*/ 
+static void pagerUnlockIfUnused(Pager *pPager){
+  if( (sqlite3PcacheRefCount(pPager->pPCache)==0) ){
+    pagerUnlockAndRollback(pPager);
+  }
+}
+
+/*
+** Acquire a reference to page number pgno in pager pPager (a page
+** reference has type DbPage*). If the requested reference is 
+** successfully obtained, it is copied to *ppPage and SQLITE_OK returned.
+**
+** If the requested page is already in the cache, it is returned. 
+** Otherwise, a new page object is allocated and populated with data
+** read from the database file. In some cases, the pcache module may
+** choose not to allocate a new page object and may reuse an existing
+** object with no outstanding references.
+**
+** The extra data appended to a page is always initialized to zeros the 
+** first time a page is loaded into memory. If the page requested is 
+** already in the cache when this function is called, then the extra
+** data is left as it was when the page object was last used.
+**
+** If the database image is smaller than the requested page or if a 
+** non-zero value is passed as the noContent parameter and the 
+** requested page is not already stored in the cache, then no 
+** actual disk read occurs. In this case the memory image of the 
+** page is initialized to all zeros. 
+**
+** If noContent is true, it means that we do not care about the contents
+** of the page. This occurs in two seperate scenarios:
+**
+**   a) When reading a free-list leaf page from the database, and
+**
+**   b) When a savepoint is being rolled back and we need to load
+**      a new page into the cache to be filled with the data read
+**      from the savepoint journal.
+**
+** If noContent is true, then the data returned is zeroed instead of
+** being read from the database. Additionally, the bits corresponding
+** to pgno in Pager.pInJournal (bitvec of pages already written to the
+** journal file) and the PagerSavepoint.pInSavepoint bitvecs of any open
+** savepoints are set. This means if the page is made writable at any
+** point in the future, using a call to sqlite3PagerWrite(), its contents
+** will not be journaled. This saves IO.
+**
+** The acquisition might fail for several reasons.  In all cases,
+** an appropriate error code is returned and *ppPage is set to NULL.
+**
+** See also sqlite3PagerLookup().  Both this routine and Lookup() attempt
+** to find a page in the in-memory cache first.  If the page is not already
+** in memory, this routine goes to disk to read it in whereas Lookup()
+** just returns 0.  This routine acquires a read-lock the first time it
+** has to go to disk, and could also playback an old journal if necessary.
+** Since Lookup() never goes to disk, it never has to deal with locks
+** or journal files.
+*/
+SQLITE_PRIVATE int sqlite3PagerAcquire(
+  Pager *pPager,      /* The pager open on the database file */
+  Pgno pgno,          /* Page number to fetch */
+  DbPage **ppPage,    /* Write a pointer to the page here */
+  int noContent       /* Do not bother reading content from disk if true */
+){
+  int rc;
+  PgHdr *pPg;
+
+  assert( pPager->eState>=PAGER_READER );
+  assert( assert_pager_state(pPager) );
+
+  if( pgno==0 ){
+    return SQLITE_CORRUPT_BKPT;
+  }
+
+  /* If the pager is in the error state, return an error immediately. 
+  ** Otherwise, request the page from the PCache layer. */
+  if( pPager->errCode!=SQLITE_OK ){
+    rc = pPager->errCode;
+  }else{
+    rc = sqlite3PcacheFetch(pPager->pPCache, pgno, 1, ppPage);
+  }
+
+  if( rc!=SQLITE_OK ){
+    /* Either the call to sqlite3PcacheFetch() returned an error or the
+    ** pager was already in the error-state when this function was called.
+    ** Set pPg to 0 and jump to the exception handler.  */
+    pPg = 0;
+    goto pager_acquire_err;
+  }
+  assert( (*ppPage)->pgno==pgno );
+  assert( (*ppPage)->pPager==pPager || (*ppPage)->pPager==0 );
+
+  if( (*ppPage)->pPager && !noContent ){
+    /* In this case the pcache already contains an initialized copy of
+    ** the page. Return without further ado.  */
+    assert( pgno<=PAGER_MAX_PGNO && pgno!=PAGER_MJ_PGNO(pPager) );
+    PAGER_INCR(pPager->nHit);
+    return SQLITE_OK;
+
+  }else{
+    /* The pager cache has created a new page. Its content needs to 
+    ** be initialized.  */
+
+    PAGER_INCR(pPager->nMiss);
+    pPg = *ppPage;
+    pPg->pPager = pPager;
+
+    /* The maximum page number is 2^31. Return SQLITE_CORRUPT if a page
+    ** number greater than this, or the unused locking-page, is requested. */
+    if( pgno>PAGER_MAX_PGNO || pgno==PAGER_MJ_PGNO(pPager) ){
+      rc = SQLITE_CORRUPT_BKPT;
+      goto pager_acquire_err;
+    }
+
+    if( MEMDB || pPager->dbSize<pgno || noContent || !isOpen(pPager->fd) ){
+      if( pgno>pPager->mxPgno ){
+        rc = SQLITE_FULL;
+        goto pager_acquire_err;
+      }
+      if( noContent ){
+        /* Failure to set the bits in the InJournal bit-vectors is benign.
+        ** It merely means that we might do some extra work to journal a 
+        ** page that does not need to be journaled.  Nevertheless, be sure 
+        ** to test the case where a malloc error occurs while trying to set 
+        ** a bit in a bit vector.
+        */
+        sqlite3BeginBenignMalloc();
+        if( pgno<=pPager->dbOrigSize ){
+          TESTONLY( rc = ) sqlite3BitvecSet(pPager->pInJournal, pgno);
+          testcase( rc==SQLITE_NOMEM );
+        }
+        TESTONLY( rc = ) addToSavepointBitvecs(pPager, pgno);
+        testcase( rc==SQLITE_NOMEM );
+        sqlite3EndBenignMalloc();
+      }
+      memset(pPg->pData, 0, pPager->pageSize);
+      IOTRACE(("ZERO %p %d\n", pPager, pgno));
+    }else{
+      assert( pPg->pPager==pPager );
+      rc = readDbPage(pPg);
+      if( rc!=SQLITE_OK ){
+        goto pager_acquire_err;
+      }
+    }
+    pager_set_pagehash(pPg);
+  }
+
+  return SQLITE_OK;
+
+pager_acquire_err:
+  assert( rc!=SQLITE_OK );
+  if( pPg ){
+    sqlite3PcacheDrop(pPg);
+  }
+  pagerUnlockIfUnused(pPager);
+
+  *ppPage = 0;
+  return rc;
+}
+
+/*
+** Acquire a page if it is already in the in-memory cache.  Do
+** not read the page from disk.  Return a pointer to the page,
+** or 0 if the page is not in cache. 
+**
+** See also sqlite3PagerGet().  The difference between this routine
+** and sqlite3PagerGet() is that _get() will go to the disk and read
+** in the page if the page is not already in cache.  This routine
+** returns NULL if the page is not in cache or if a disk I/O error 
+** has ever happened.
+*/
+SQLITE_PRIVATE DbPage *sqlite3PagerLookup(Pager *pPager, Pgno pgno){
+  PgHdr *pPg = 0;
+  assert( pPager!=0 );
+  assert( pgno!=0 );
+  assert( pPager->pPCache!=0 );
+  assert( pPager->eState>=PAGER_READER && pPager->eState!=PAGER_ERROR );
+  sqlite3PcacheFetch(pPager->pPCache, pgno, 0, &pPg);
+  return pPg;
+}
+
+/*
+** Release a page reference.
+**
+** If the number of references to the page drop to zero, then the
+** page is added to the LRU list.  When all references to all pages
+** are released, a rollback occurs and the lock on the database is
+** removed.
+*/
+SQLITE_PRIVATE void sqlite3PagerUnref(DbPage *pPg){
+  if( pPg ){
+    Pager *pPager = pPg->pPager;
+    sqlite3PcacheRelease(pPg);
+    pagerUnlockIfUnused(pPager);
+  }
+}
+
+/*
+** This function is called at the start of every write transaction.
+** There must already be a RESERVED or EXCLUSIVE lock on the database 
+** file when this routine is called.
+**
+** Open the journal file for pager pPager and write a journal header
+** to the start of it. If there are active savepoints, open the sub-journal
+** as well. This function is only used when the journal file is being 
+** opened to write a rollback log for a transaction. It is not used 
+** when opening a hot journal file to roll it back.
+**
+** If the journal file is already open (as it may be in exclusive mode),
+** then this function just writes a journal header to the start of the
+** already open file. 
+**
+** Whether or not the journal file is opened by this function, the
+** Pager.pInJournal bitvec structure is allocated.
+**
+** Return SQLITE_OK if everything is successful. Otherwise, return 
+** SQLITE_NOMEM if the attempt to allocate Pager.pInJournal fails, or 
+** an IO error code if opening or writing the journal file fails.
+*/
+static int pager_open_journal(Pager *pPager){
+  int rc = SQLITE_OK;                        /* Return code */
+  sqlite3_vfs * const pVfs = pPager->pVfs;   /* Local cache of vfs pointer */
+
+  assert( pPager->eState==PAGER_WRITER_LOCKED );
+  assert( assert_pager_state(pPager) );
+  assert( pPager->pInJournal==0 );
+  
+  /* If already in the error state, this function is a no-op.  But on
+  ** the other hand, this routine is never called if we are already in
+  ** an error state. */
+  if( NEVER(pPager->errCode) ) return pPager->errCode;
+
+  if( !pagerUseWal(pPager) && pPager->journalMode!=PAGER_JOURNALMODE_OFF ){
+    pPager->pInJournal = sqlite3BitvecCreate(pPager->dbSize);
+    if( pPager->pInJournal==0 ){
+      return SQLITE_NOMEM;
+    }
+  
+    /* Open the journal file if it is not already open. */
+    if( !isOpen(pPager->jfd) ){
+      if( pPager->journalMode==PAGER_JOURNALMODE_MEMORY ){
+        sqlite3MemJournalOpen(pPager->jfd);
+      }else{
+        const int flags =                   /* VFS flags to open journal file */
+          SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE|
+          (pPager->tempFile ? 
+            (SQLITE_OPEN_DELETEONCLOSE|SQLITE_OPEN_TEMP_JOURNAL):
+            (SQLITE_OPEN_MAIN_JOURNAL)
+          );
+  #ifdef SQLITE_ENABLE_ATOMIC_WRITE
+        rc = sqlite3JournalOpen(
+            pVfs, pPager->zJournal, pPager->jfd, flags, jrnlBufferSize(pPager)
+        );
+  #else
+        rc = sqlite3OsOpen(pVfs, pPager->zJournal, pPager->jfd, flags, 0);
+  #endif
+      }
+      assert( rc!=SQLITE_OK || isOpen(pPager->jfd) );
+    }
+  
+  
+    /* Write the first journal header to the journal file and open 
+    ** the sub-journal if necessary.
+    */
+    if( rc==SQLITE_OK ){
+      /* TODO: Check if all of these are really required. */
+      pPager->nRec = 0;
+      pPager->journalOff = 0;
+      pPager->setMaster = 0;
+      pPager->journalHdr = 0;
+      rc = writeJournalHdr(pPager);
+    }
+  }
+
+  if( rc!=SQLITE_OK ){
+    sqlite3BitvecDestroy(pPager->pInJournal);
+    pPager->pInJournal = 0;
+  }else{
+    assert( pPager->eState==PAGER_WRITER_LOCKED );
+    pPager->eState = PAGER_WRITER_CACHEMOD;
+  }
+
+  return rc;
+}
+
+/*
+** Begin a write-transaction on the specified pager object. If a 
+** write-transaction has already been opened, this function is a no-op.
+**
+** If the exFlag argument is false, then acquire at least a RESERVED
+** lock on the database file. If exFlag is true, then acquire at least
+** an EXCLUSIVE lock. If such a lock is already held, no locking 
+** functions need be called.
+**
+** If the subjInMemory argument is non-zero, then any sub-journal opened
+** within this transaction will be opened as an in-memory file. This
+** has no effect if the sub-journal is already opened (as it may be when
+** running in exclusive mode) or if the transaction does not require a
+** sub-journal. If the subjInMemory argument is zero, then any required
+** sub-journal is implemented in-memory if pPager is an in-memory database, 
+** or using a temporary file otherwise.
+*/
+SQLITE_PRIVATE int sqlite3PagerBegin(Pager *pPager, int exFlag, int subjInMemory){
+  int rc = SQLITE_OK;
+
+  if( pPager->errCode ) return pPager->errCode;
+  assert( pPager->eState>=PAGER_READER && pPager->eState<PAGER_ERROR );
+  pPager->subjInMemory = (u8)subjInMemory;
+
+  if( ALWAYS(pPager->eState==PAGER_READER) ){
+    assert( pPager->pInJournal==0 );
+
+    if( pagerUseWal(pPager) ){
+      /* If the pager is configured to use locking_mode=exclusive, and an
+      ** exclusive lock on the database is not already held, obtain it now.
+      */
+      if( pPager->exclusiveMode && sqlite3WalExclusiveMode(pPager->pWal, -1) ){
+        rc = pagerLockDb(pPager, EXCLUSIVE_LOCK);
+        if( rc!=SQLITE_OK ){
+          return rc;
+        }
+        sqlite3WalExclusiveMode(pPager->pWal, 1);
+      }
+
+      /* Grab the write lock on the log file. If successful, upgrade to
+      ** PAGER_RESERVED state. Otherwise, return an error code to the caller.
+      ** The busy-handler is not invoked if another connection already
+      ** holds the write-lock. If possible, the upper layer will call it.
+      */
+      rc = sqlite3WalBeginWriteTransaction(pPager->pWal);
+    }else{
+      /* Obtain a RESERVED lock on the database file. If the exFlag parameter
+      ** is true, then immediately upgrade this to an EXCLUSIVE lock. The
+      ** busy-handler callback can be used when upgrading to the EXCLUSIVE
+      ** lock, but not when obtaining the RESERVED lock.
+      */
+      rc = pagerLockDb(pPager, RESERVED_LOCK);
+      if( rc==SQLITE_OK && exFlag ){
+        rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK);
+      }
+    }
+
+    if( rc==SQLITE_OK ){
+      /* Change to WRITER_LOCKED state.
+      **
+      ** WAL mode sets Pager.eState to PAGER_WRITER_LOCKED or CACHEMOD
+      ** when it has an open transaction, but never to DBMOD or FINISHED.
+      ** This is because in those states the code to roll back savepoint 
+      ** transactions may copy data from the sub-journal into the database 
+      ** file as well as into the page cache. Which would be incorrect in 
+      ** WAL mode.
+      */
+      pPager->eState = PAGER_WRITER_LOCKED;
+      pPager->dbHintSize = pPager->dbSize;
+      pPager->dbFileSize = pPager->dbSize;
+      pPager->dbOrigSize = pPager->dbSize;
+      pPager->journalOff = 0;
+    }
+
+    assert( rc==SQLITE_OK || pPager->eState==PAGER_READER );
+    assert( rc!=SQLITE_OK || pPager->eState==PAGER_WRITER_LOCKED );
+    assert( assert_pager_state(pPager) );
+  }
+
+  PAGERTRACE(("TRANSACTION %d\n", PAGERID(pPager)));
+  return rc;
+}
+
+/*
+** Mark a single data page as writeable. The page is written into the 
+** main journal or sub-journal as required. If the page is written into
+** one of the journals, the corresponding bit is set in the 
+** Pager.pInJournal bitvec and the PagerSavepoint.pInSavepoint bitvecs
+** of any open savepoints as appropriate.
+*/
+static int pager_write(PgHdr *pPg){
+  void *pData = pPg->pData;
+  Pager *pPager = pPg->pPager;
+  int rc = SQLITE_OK;
+
+  /* This routine is not called unless a write-transaction has already 
+  ** been started. The journal file may or may not be open at this point.
+  ** It is never called in the ERROR state.
+  */
+  assert( pPager->eState==PAGER_WRITER_LOCKED
+       || pPager->eState==PAGER_WRITER_CACHEMOD
+       || pPager->eState==PAGER_WRITER_DBMOD
+  );
+  assert( assert_pager_state(pPager) );
+
+  /* If an error has been previously detected, report the same error
+  ** again. This should not happen, but the check provides robustness. */
+  if( NEVER(pPager->errCode) )  return pPager->errCode;
+
+  /* Higher-level routines never call this function if database is not
+  ** writable.  But check anyway, just for robustness. */
+  if( NEVER(pPager->readOnly) ) return SQLITE_PERM;
+
+  CHECK_PAGE(pPg);
+
+  /* The journal file needs to be opened. Higher level routines have already
+  ** obtained the necessary locks to begin the write-transaction, but the
+  ** rollback journal might not yet be open. Open it now if this is the case.
+  **
+  ** This is done before calling sqlite3PcacheMakeDirty() on the page. 
+  ** Otherwise, if it were done after calling sqlite3PcacheMakeDirty(), then
+  ** an error might occur and the pager would end up in WRITER_LOCKED state
+  ** with pages marked as dirty in the cache.
+  */
+  if( pPager->eState==PAGER_WRITER_LOCKED ){
+    rc = pager_open_journal(pPager);
+    if( rc!=SQLITE_OK ) return rc;
+  }
+  assert( pPager->eState>=PAGER_WRITER_CACHEMOD );
+  assert( assert_pager_state(pPager) );
+
+  /* Mark the page as dirty.  If the page has already been written
+  ** to the journal then we can return right away.
+  */
+  sqlite3PcacheMakeDirty(pPg);
+  if( pageInJournal(pPg) && !subjRequiresPage(pPg) ){
+    assert( !pagerUseWal(pPager) );
+  }else{
+  
+    /* The transaction journal now exists and we have a RESERVED or an
+    ** EXCLUSIVE lock on the main database file.  Write the current page to
+    ** the transaction journal if it is not there already.
+    */
+    if( !pageInJournal(pPg) && !pagerUseWal(pPager) ){
+      assert( pagerUseWal(pPager)==0 );
+      if( pPg->pgno<=pPager->dbOrigSize && isOpen(pPager->jfd) ){
+        u32 cksum;
+        char *pData2;
+        i64 iOff = pPager->journalOff;
+
+        /* We should never write to the journal file the page that
+        ** contains the database locks.  The following assert verifies
+        ** that we do not. */
+        assert( pPg->pgno!=PAGER_MJ_PGNO(pPager) );
+
+        assert( pPager->journalHdr<=pPager->journalOff );
+        CODEC2(pPager, pData, pPg->pgno, 7, return SQLITE_NOMEM, pData2);
+        cksum = pager_cksum(pPager, (u8*)pData2);
+
+        /* Even if an IO or diskfull error occurs while journalling the
+        ** page in the block above, set the need-sync flag for the page.
+        ** Otherwise, when the transaction is rolled back, the logic in
+        ** playback_one_page() will think that the page needs to be restored
+        ** in the database file. And if an IO error occurs while doing so,
+        ** then corruption may follow.
+        */
+        pPg->flags |= PGHDR_NEED_SYNC;
+
+        rc = write32bits(pPager->jfd, iOff, pPg->pgno);
+        if( rc!=SQLITE_OK ) return rc;
+        rc = sqlite3OsWrite(pPager->jfd, pData2, pPager->pageSize, iOff+4);
+        if( rc!=SQLITE_OK ) return rc;
+        rc = write32bits(pPager->jfd, iOff+pPager->pageSize+4, cksum);
+        if( rc!=SQLITE_OK ) return rc;
+
+        IOTRACE(("JOUT %p %d %lld %d\n", pPager, pPg->pgno, 
+                 pPager->journalOff, pPager->pageSize));
+        PAGER_INCR(sqlite3_pager_writej_count);
+        PAGERTRACE(("JOURNAL %d page %d needSync=%d hash(%08x)\n",
+             PAGERID(pPager), pPg->pgno, 
+             ((pPg->flags&PGHDR_NEED_SYNC)?1:0), pager_pagehash(pPg)));
+
+        pPager->journalOff += 8 + pPager->pageSize;
+        pPager->nRec++;
+        assert( pPager->pInJournal!=0 );
+        rc = sqlite3BitvecSet(pPager->pInJournal, pPg->pgno);
+        testcase( rc==SQLITE_NOMEM );
+        assert( rc==SQLITE_OK || rc==SQLITE_NOMEM );
+        rc |= addToSavepointBitvecs(pPager, pPg->pgno);
+        if( rc!=SQLITE_OK ){
+          assert( rc==SQLITE_NOMEM );
+          return rc;
+        }
+      }else{
+        if( pPager->eState!=PAGER_WRITER_DBMOD ){
+          pPg->flags |= PGHDR_NEED_SYNC;
+        }
+        PAGERTRACE(("APPEND %d page %d needSync=%d\n",
+                PAGERID(pPager), pPg->pgno,
+               ((pPg->flags&PGHDR_NEED_SYNC)?1:0)));
+      }
+    }
+  
+    /* If the statement journal is open and the page is not in it,
+    ** then write the current page to the statement journal.  Note that
+    ** the statement journal format differs from the standard journal format
+    ** in that it omits the checksums and the header.
+    */
+    if( subjRequiresPage(pPg) ){
+      rc = subjournalPage(pPg);
+    }
+  }
+
+  /* Update the database size and return.
+  */
+  if( pPager->dbSize<pPg->pgno ){
+    pPager->dbSize = pPg->pgno;
+  }
+  return rc;
+}
+
+/*
+** Mark a data page as writeable. This routine must be called before 
+** making changes to a page. The caller must check the return value 
+** of this function and be careful not to change any page data unless 
+** this routine returns SQLITE_OK.
+**
+** The difference between this function and pager_write() is that this
+** function also deals with the special case where 2 or more pages
+** fit on a single disk sector. In this case all co-resident pages
+** must have been written to the journal file before returning.
+**
+** If an error occurs, SQLITE_NOMEM or an IO error code is returned
+** as appropriate. Otherwise, SQLITE_OK.
+*/
+SQLITE_PRIVATE int sqlite3PagerWrite(DbPage *pDbPage){
+  int rc = SQLITE_OK;
+
+  PgHdr *pPg = pDbPage;
+  Pager *pPager = pPg->pPager;
+  Pgno nPagePerSector = (pPager->sectorSize/pPager->pageSize);
+
+  assert( pPager->eState>=PAGER_WRITER_LOCKED );
+  assert( pPager->eState!=PAGER_ERROR );
+  assert( assert_pager_state(pPager) );
+
+  if( nPagePerSector>1 ){
+    Pgno nPageCount;          /* Total number of pages in database file */
+    Pgno pg1;                 /* First page of the sector pPg is located on. */
+    int nPage = 0;            /* Number of pages starting at pg1 to journal */
+    int ii;                   /* Loop counter */
+    int needSync = 0;         /* True if any page has PGHDR_NEED_SYNC */
+
+    /* Set the doNotSyncSpill flag to 1. This is because we cannot allow
+    ** a journal header to be written between the pages journaled by
+    ** this function.
+    */
+    assert( !MEMDB );
+    assert( pPager->doNotSyncSpill==0 );
+    pPager->doNotSyncSpill++;
+
+    /* This trick assumes that both the page-size and sector-size are
+    ** an integer power of 2. It sets variable pg1 to the identifier
+    ** of the first page of the sector pPg is located on.
+    */
+    pg1 = ((pPg->pgno-1) & ~(nPagePerSector-1)) + 1;
+
+    nPageCount = pPager->dbSize;
+    if( pPg->pgno>nPageCount ){
+      nPage = (pPg->pgno - pg1)+1;
+    }else if( (pg1+nPagePerSector-1)>nPageCount ){
+      nPage = nPageCount+1-pg1;
+    }else{
+      nPage = nPagePerSector;
+    }
+    assert(nPage>0);
+    assert(pg1<=pPg->pgno);
+    assert((pg1+nPage)>pPg->pgno);
+
+    for(ii=0; ii<nPage && rc==SQLITE_OK; ii++){
+      Pgno pg = pg1+ii;
+      PgHdr *pPage;
+      if( pg==pPg->pgno || !sqlite3BitvecTest(pPager->pInJournal, pg) ){
+        if( pg!=PAGER_MJ_PGNO(pPager) ){
+          rc = sqlite3PagerGet(pPager, pg, &pPage);
+          if( rc==SQLITE_OK ){
+            rc = pager_write(pPage);
+            if( pPage->flags&PGHDR_NEED_SYNC ){
+              needSync = 1;
+            }
+            sqlite3PagerUnref(pPage);
+          }
+        }
+      }else if( (pPage = pager_lookup(pPager, pg))!=0 ){
+        if( pPage->flags&PGHDR_NEED_SYNC ){
+          needSync = 1;
+        }
+        sqlite3PagerUnref(pPage);
+      }
+    }
+
+    /* If the PGHDR_NEED_SYNC flag is set for any of the nPage pages 
+    ** starting at pg1, then it needs to be set for all of them. Because
+    ** writing to any of these nPage pages may damage the others, the
+    ** journal file must contain sync()ed copies of all of them
+    ** before any of them can be written out to the database file.
+    */
+    if( rc==SQLITE_OK && needSync ){
+      assert( !MEMDB );
+      for(ii=0; ii<nPage; ii++){
+        PgHdr *pPage = pager_lookup(pPager, pg1+ii);
+        if( pPage ){
+          pPage->flags |= PGHDR_NEED_SYNC;
+          sqlite3PagerUnref(pPage);
+        }
+      }
+    }
+
+    assert( pPager->doNotSyncSpill==1 );
+    pPager->doNotSyncSpill--;
+  }else{
+    rc = pager_write(pDbPage);
+  }
+  return rc;
+}
+
+/*
+** Return TRUE if the page given in the argument was previously passed
+** to sqlite3PagerWrite().  In other words, return TRUE if it is ok
+** to change the content of the page.
+*/
+#ifndef NDEBUG
+SQLITE_PRIVATE int sqlite3PagerIswriteable(DbPage *pPg){
+  return pPg->flags&PGHDR_DIRTY;
+}
+#endif
+
+/*
+** A call to this routine tells the pager that it is not necessary to
+** write the information on page pPg back to the disk, even though
+** that page might be marked as dirty.  This happens, for example, when
+** the page has been added as a leaf of the freelist and so its
+** content no longer matters.
+**
+** The overlying software layer calls this routine when all of the data
+** on the given page is unused. The pager marks the page as clean so
+** that it does not get written to disk.
+**
+** Tests show that this optimization can quadruple the speed of large 
+** DELETE operations.
+*/
+SQLITE_PRIVATE void sqlite3PagerDontWrite(PgHdr *pPg){
+  Pager *pPager = pPg->pPager;
+  if( (pPg->flags&PGHDR_DIRTY) && pPager->nSavepoint==0 ){
+    PAGERTRACE(("DONT_WRITE page %d of %d\n", pPg->pgno, PAGERID(pPager)));
+    IOTRACE(("CLEAN %p %d\n", pPager, pPg->pgno))
+    pPg->flags |= PGHDR_DONT_WRITE;
+    pager_set_pagehash(pPg);
+  }
+}
+
+/*
+** This routine is called to increment the value of the database file 
+** change-counter, stored as a 4-byte big-endian integer starting at 
+** byte offset 24 of the pager file.  The secondary change counter at
+** 92 is also updated, as is the SQLite version number at offset 96.
+**
+** But this only happens if the pPager->changeCountDone flag is false.
+** To avoid excess churning of page 1, the update only happens once.
+** See also the pager_write_changecounter() routine that does an 
+** unconditional update of the change counters.
+**
+** If the isDirectMode flag is zero, then this is done by calling 
+** sqlite3PagerWrite() on page 1, then modifying the contents of the
+** page data. In this case the file will be updated when the current
+** transaction is committed.
+**
+** The isDirectMode flag may only be non-zero if the library was compiled
+** with the SQLITE_ENABLE_ATOMIC_WRITE macro defined. In this case,
+** if isDirect is non-zero, then the database file is updated directly
+** by writing an updated version of page 1 using a call to the 
+** sqlite3OsWrite() function.
+*/
+static int pager_incr_changecounter(Pager *pPager, int isDirectMode){
+  int rc = SQLITE_OK;
+
+  assert( pPager->eState==PAGER_WRITER_CACHEMOD
+       || pPager->eState==PAGER_WRITER_DBMOD
+  );
+  assert( assert_pager_state(pPager) );
+
+  /* Declare and initialize constant integer 'isDirect'. If the
+  ** atomic-write optimization is enabled in this build, then isDirect
+  ** is initialized to the value passed as the isDirectMode parameter
+  ** to this function. Otherwise, it is always set to zero.
+  **
+  ** The idea is that if the atomic-write optimization is not
+  ** enabled at compile time, the compiler can omit the tests of
+  ** 'isDirect' below, as well as the block enclosed in the
+  ** "if( isDirect )" condition.
+  */
+#ifndef SQLITE_ENABLE_ATOMIC_WRITE
+# define DIRECT_MODE 0
+  assert( isDirectMode==0 );
+  UNUSED_PARAMETER(isDirectMode);
+#else
+# define DIRECT_MODE isDirectMode
+#endif
+
+  if( !pPager->changeCountDone && pPager->dbSize>0 ){
+    PgHdr *pPgHdr;                /* Reference to page 1 */
+
+    assert( !pPager->tempFile && isOpen(pPager->fd) );
+
+    /* Open page 1 of the file for writing. */
+    rc = sqlite3PagerGet(pPager, 1, &pPgHdr);
+    assert( pPgHdr==0 || rc==SQLITE_OK );
+
+    /* If page one was fetched successfully, and this function is not
+    ** operating in direct-mode, make page 1 writable.  When not in 
+    ** direct mode, page 1 is always held in cache and hence the PagerGet()
+    ** above is always successful - hence the ALWAYS on rc==SQLITE_OK.
+    */
+    if( !DIRECT_MODE && ALWAYS(rc==SQLITE_OK) ){
+      rc = sqlite3PagerWrite(pPgHdr);
+    }
+
+    if( rc==SQLITE_OK ){
+      /* Actually do the update of the change counter */
+      pager_write_changecounter(pPgHdr);
+
+      /* If running in direct mode, write the contents of page 1 to the file. */
+      if( DIRECT_MODE ){
+        const void *zBuf;
+        assert( pPager->dbFileSize>0 );
+        CODEC2(pPager, pPgHdr->pData, 1, 6, rc=SQLITE_NOMEM, zBuf);
+        if( rc==SQLITE_OK ){
+          rc = sqlite3OsWrite(pPager->fd, zBuf, pPager->pageSize, 0);
+        }
+        if( rc==SQLITE_OK ){
+          pPager->changeCountDone = 1;
+        }
+      }else{
+        pPager->changeCountDone = 1;
+      }
+    }
+
+    /* Release the page reference. */
+    sqlite3PagerUnref(pPgHdr);
+  }
+  return rc;
+}
+
+/*
+** Sync the database file to disk. This is a no-op for in-memory databases
+** or pages with the Pager.noSync flag set.
+**
+** If successful, or if called on a pager for which it is a no-op, this
+** function returns SQLITE_OK. Otherwise, an IO error code is returned.
+*/
+SQLITE_PRIVATE int sqlite3PagerSync(Pager *pPager){
+  int rc = SQLITE_OK;
+  if( !pPager->noSync ){
+    assert( !MEMDB );
+    rc = sqlite3OsSync(pPager->fd, pPager->syncFlags);
+  }else if( isOpen(pPager->fd) ){
+    assert( !MEMDB );
+    sqlite3OsFileControl(pPager->fd, SQLITE_FCNTL_SYNC_OMITTED, (void *)&rc);
+  }
+  return rc;
+}
+
+/*
+** This function may only be called while a write-transaction is active in
+** rollback. If the connection is in WAL mode, this call is a no-op. 
+** Otherwise, if the connection does not already have an EXCLUSIVE lock on 
+** the database file, an attempt is made to obtain one.
+**
+** If the EXCLUSIVE lock is already held or the attempt to obtain it is
+** successful, or the connection is in WAL mode, SQLITE_OK is returned.
+** Otherwise, either SQLITE_BUSY or an SQLITE_IOERR_XXX error code is 
+** returned.
+*/
+SQLITE_PRIVATE int sqlite3PagerExclusiveLock(Pager *pPager){
+  int rc = SQLITE_OK;
+  assert( pPager->eState==PAGER_WRITER_CACHEMOD 
+       || pPager->eState==PAGER_WRITER_DBMOD 
+       || pPager->eState==PAGER_WRITER_LOCKED 
+  );
+  assert( assert_pager_state(pPager) );
+  if( 0==pagerUseWal(pPager) ){
+    rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK);
+  }
+  return rc;
+}
+
+/*
+** Sync the database file for the pager pPager. zMaster points to the name
+** of a master journal file that should be written into the individual
+** journal file. zMaster may be NULL, which is interpreted as no master
+** journal (a single database transaction).
+**
+** This routine ensures that:
+**
+**   * The database file change-counter is updated,
+**   * the journal is synced (unless the atomic-write optimization is used),
+**   * all dirty pages are written to the database file, 
+**   * the database file is truncated (if required), and
+**   * the database file synced. 
+**
+** The only thing that remains to commit the transaction is to finalize 
+** (delete, truncate or zero the first part of) the journal file (or 
+** delete the master journal file if specified).
+**
+** Note that if zMaster==NULL, this does not overwrite a previous value
+** passed to an sqlite3PagerCommitPhaseOne() call.
+**
+** If the final parameter - noSync - is true, then the database file itself
+** is not synced. The caller must call sqlite3PagerSync() directly to
+** sync the database file before calling CommitPhaseTwo() to delete the
+** journal file in this case.
+*/
+SQLITE_PRIVATE int sqlite3PagerCommitPhaseOne(
+  Pager *pPager,                  /* Pager object */
+  const char *zMaster,            /* If not NULL, the master journal name */
+  int noSync                      /* True to omit the xSync on the db file */
+){
+  int rc = SQLITE_OK;             /* Return code */
+
+  assert( pPager->eState==PAGER_WRITER_LOCKED
+       || pPager->eState==PAGER_WRITER_CACHEMOD
+       || pPager->eState==PAGER_WRITER_DBMOD
+       || pPager->eState==PAGER_ERROR
+  );
+  assert( assert_pager_state(pPager) );
+
+  /* If a prior error occurred, report that error again. */
+  if( NEVER(pPager->errCode) ) return pPager->errCode;
+
+  PAGERTRACE(("DATABASE SYNC: File=%s zMaster=%s nSize=%d\n", 
+      pPager->zFilename, zMaster, pPager->dbSize));
+
+  /* If no database changes have been made, return early. */
+  if( pPager->eState<PAGER_WRITER_CACHEMOD ) return SQLITE_OK;
+
+  if( MEMDB ){
+    /* If this is an in-memory db, or no pages have been written to, or this
+    ** function has already been called, it is mostly a no-op.  However, any
+    ** backup in progress needs to be restarted.
+    */
+    sqlite3BackupRestart(pPager->pBackup);
+  }else{
+    if( pagerUseWal(pPager) ){
+      PgHdr *pList = sqlite3PcacheDirtyList(pPager->pPCache);
+      PgHdr *pPageOne = 0;
+      if( pList==0 ){
+        /* Must have at least one page for the WAL commit flag.
+        ** Ticket [2d1a5c67dfc2363e44f29d9bbd57f] 2011-05-18 */
+        rc = sqlite3PagerGet(pPager, 1, &pPageOne);
+        pList = pPageOne;
+        pList->pDirty = 0;
+      }
+      assert( pList!=0 || rc!=SQLITE_OK );
+      if( pList ){
+        rc = pagerWalFrames(pPager, pList, pPager->dbSize, 1, 
+            (pPager->fullSync ? pPager->syncFlags : 0)
+        );
+      }
+      sqlite3PagerUnref(pPageOne);
+      if( rc==SQLITE_OK ){
+        sqlite3PcacheCleanAll(pPager->pPCache);
+      }
+    }else{
+      /* The following block updates the change-counter. Exactly how it
+      ** does this depends on whether or not the atomic-update optimization
+      ** was enabled at compile time, and if this transaction meets the 
+      ** runtime criteria to use the operation: 
+      **
+      **    * The file-system supports the atomic-write property for
+      **      blocks of size page-size, and 
+      **    * This commit is not part of a multi-file transaction, and
+      **    * Exactly one page has been modified and store in the journal file.
+      **
+      ** If the optimization was not enabled at compile time, then the
+      ** pager_incr_changecounter() function is called to update the change
+      ** counter in 'indirect-mode'. If the optimization is compiled in but
+      ** is not applicable to this transaction, call sqlite3JournalCreate()
+      ** to make sure the journal file has actually been created, then call
+      ** pager_incr_changecounter() to update the change-counter in indirect
+      ** mode. 
+      **
+      ** Otherwise, if the optimization is both enabled and applicable,
+      ** then call pager_incr_changecounter() to update the change-counter
+      ** in 'direct' mode. In this case the journal file will never be
+      ** created for this transaction.
+      */
+  #ifdef SQLITE_ENABLE_ATOMIC_WRITE
+      PgHdr *pPg;
+      assert( isOpen(pPager->jfd) 
+           || pPager->journalMode==PAGER_JOURNALMODE_OFF 
+           || pPager->journalMode==PAGER_JOURNALMODE_WAL 
+      );
+      if( !zMaster && isOpen(pPager->jfd) 
+       && pPager->journalOff==jrnlBufferSize(pPager) 
+       && pPager->dbSize>=pPager->dbOrigSize
+       && (0==(pPg = sqlite3PcacheDirtyList(pPager->pPCache)) || 0==pPg->pDirty)
+      ){
+        /* Update the db file change counter via the direct-write method. The 
+        ** following call will modify the in-memory representation of page 1 
+        ** to include the updated change counter and then write page 1 
+        ** directly to the database file. Because of the atomic-write 
+        ** property of the host file-system, this is safe.
+        */
+        rc = pager_incr_changecounter(pPager, 1);
+      }else{
+        rc = sqlite3JournalCreate(pPager->jfd);
+        if( rc==SQLITE_OK ){
+          rc = pager_incr_changecounter(pPager, 0);
+        }
+      }
+  #else
+      rc = pager_incr_changecounter(pPager, 0);
+  #endif
+      if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
+  
+      /* If this transaction has made the database smaller, then all pages
+      ** being discarded by the truncation must be written to the journal
+      ** file. This can only happen in auto-vacuum mode.
+      **
+      ** Before reading the pages with page numbers larger than the 
+      ** current value of Pager.dbSize, set dbSize back to the value
+      ** that it took at the start of the transaction. Otherwise, the
+      ** calls to sqlite3PagerGet() return zeroed pages instead of 
+      ** reading data from the database file.
+      */
+  #ifndef SQLITE_OMIT_AUTOVACUUM
+      if( pPager->dbSize<pPager->dbOrigSize 
+       && pPager->journalMode!=PAGER_JOURNALMODE_OFF
+      ){
+        Pgno i;                                   /* Iterator variable */
+        const Pgno iSkip = PAGER_MJ_PGNO(pPager); /* Pending lock page */
+        const Pgno dbSize = pPager->dbSize;       /* Database image size */ 
+        pPager->dbSize = pPager->dbOrigSize;
+        for( i=dbSize+1; i<=pPager->dbOrigSize; i++ ){
+          if( !sqlite3BitvecTest(pPager->pInJournal, i) && i!=iSkip ){
+            PgHdr *pPage;             /* Page to journal */
+            rc = sqlite3PagerGet(pPager, i, &pPage);
+            if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
+            rc = sqlite3PagerWrite(pPage);
+            sqlite3PagerUnref(pPage);
+            if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
+          }
+        }
+        pPager->dbSize = dbSize;
+      } 
+  #endif
+  
+      /* Write the master journal name into the journal file. If a master 
+      ** journal file name has already been written to the journal file, 
+      ** or if zMaster is NULL (no master journal), then this call is a no-op.
+      */
+      rc = writeMasterJournal(pPager, zMaster);
+      if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
+  
+      /* Sync the journal file and write all dirty pages to the database.
+      ** If the atomic-update optimization is being used, this sync will not 
+      ** create the journal file or perform any real IO.
+      **
+      ** Because the change-counter page was just modified, unless the
+      ** atomic-update optimization is used it is almost certain that the
+      ** journal requires a sync here. However, in locking_mode=exclusive
+      ** on a system under memory pressure it is just possible that this is 
+      ** not the case. In this case it is likely enough that the redundant
+      ** xSync() call will be changed to a no-op by the OS anyhow. 
+      */
+      rc = syncJournal(pPager, 0);
+      if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
+  
+      rc = pager_write_pagelist(pPager,sqlite3PcacheDirtyList(pPager->pPCache));
+      if( rc!=SQLITE_OK ){
+        assert( rc!=SQLITE_IOERR_BLOCKED );
+        goto commit_phase_one_exit;
+      }
+      sqlite3PcacheCleanAll(pPager->pPCache);
+  
+      /* If the file on disk is not the same size as the database image,
+      ** then use pager_truncate to grow or shrink the file here.
+      */
+      if( pPager->dbSize!=pPager->dbFileSize ){
+        Pgno nNew = pPager->dbSize - (pPager->dbSize==PAGER_MJ_PGNO(pPager));
+        assert( pPager->eState==PAGER_WRITER_DBMOD );
+        rc = pager_truncate(pPager, nNew);
+        if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
+      }
+  
+      /* Finally, sync the database file. */
+      if( !noSync ){
+        rc = sqlite3PagerSync(pPager);
+      }
+      IOTRACE(("DBSYNC %p\n", pPager))
+    }
+  }
+
+commit_phase_one_exit:
+  if( rc==SQLITE_OK && !pagerUseWal(pPager) ){
+    pPager->eState = PAGER_WRITER_FINISHED;
+  }
+  return rc;
+}
+
+
+/*
+** When this function is called, the database file has been completely
+** updated to reflect the changes made by the current transaction and
+** synced to disk. The journal file still exists in the file-system 
+** though, and if a failure occurs at this point it will eventually
+** be used as a hot-journal and the current transaction rolled back.
+**
+** This function finalizes the journal file, either by deleting, 
+** truncating or partially zeroing it, so that it cannot be used 
+** for hot-journal rollback. Once this is done the transaction is
+** irrevocably committed.
+**
+** If an error occurs, an IO error code is returned and the pager
+** moves into the error state. Otherwise, SQLITE_OK is returned.
+*/
+SQLITE_PRIVATE int sqlite3PagerCommitPhaseTwo(Pager *pPager){
+  int rc = SQLITE_OK;                  /* Return code */
+
+  /* This routine should not be called if a prior error has occurred.
+  ** But if (due to a coding error elsewhere in the system) it does get
+  ** called, just return the same error code without doing anything. */
+  if( NEVER(pPager->errCode) ) return pPager->errCode;
+
+  assert( pPager->eState==PAGER_WRITER_LOCKED
+       || pPager->eState==PAGER_WRITER_FINISHED
+       || (pagerUseWal(pPager) && pPager->eState==PAGER_WRITER_CACHEMOD)
+  );
+  assert( assert_pager_state(pPager) );
+
+  /* An optimization. If the database was not actually modified during
+  ** this transaction, the pager is running in exclusive-mode and is
+  ** using persistent journals, then this function is a no-op.
+  **
+  ** The start of the journal file currently contains a single journal 
+  ** header with the nRec field set to 0. If such a journal is used as
+  ** a hot-journal during hot-journal rollback, 0 changes will be made
+  ** to the database file. So there is no need to zero the journal 
+  ** header. Since the pager is in exclusive mode, there is no need
+  ** to drop any locks either.
+  */
+  if( pPager->eState==PAGER_WRITER_LOCKED 
+   && pPager->exclusiveMode 
+   && pPager->journalMode==PAGER_JOURNALMODE_PERSIST
+  ){
+    assert( pPager->journalOff==JOURNAL_HDR_SZ(pPager) || !pPager->journalOff );
+    pPager->eState = PAGER_READER;
+    return SQLITE_OK;
+  }
+
+  PAGERTRACE(("COMMIT %d\n", PAGERID(pPager)));
+  rc = pager_end_transaction(pPager, pPager->setMaster);
+  return pager_error(pPager, rc);
+}
+
+/*
+** If a write transaction is open, then all changes made within the 
+** transaction are reverted and the current write-transaction is closed.
+** The pager falls back to PAGER_READER state if successful, or PAGER_ERROR
+** state if an error occurs.
+**
+** If the pager is already in PAGER_ERROR state when this function is called,
+** it returns Pager.errCode immediately. No work is performed in this case.
+**
+** Otherwise, in rollback mode, this function performs two functions:
+**
+**   1) It rolls back the journal file, restoring all database file and 
+**      in-memory cache pages to the state they were in when the transaction
+**      was opened, and
+**
+**   2) It finalizes the journal file, so that it is not used for hot
+**      rollback at any point in the future.
+**
+** Finalization of the journal file (task 2) is only performed if the 
+** rollback is successful.
+**
+** In WAL mode, all cache-entries containing data modified within the
+** current transaction are either expelled from the cache or reverted to
+** their pre-transaction state by re-reading data from the database or
+** WAL files. The WAL transaction is then closed.
+*/
+SQLITE_PRIVATE int sqlite3PagerRollback(Pager *pPager){
+  int rc = SQLITE_OK;                  /* Return code */
+  PAGERTRACE(("ROLLBACK %d\n", PAGERID(pPager)));
+
+  /* PagerRollback() is a no-op if called in READER or OPEN state. If
+  ** the pager is already in the ERROR state, the rollback is not 
+  ** attempted here. Instead, the error code is returned to the caller.
+  */
+  assert( assert_pager_state(pPager) );
+  if( pPager->eState==PAGER_ERROR ) return pPager->errCode;
+  if( pPager->eState<=PAGER_READER ) return SQLITE_OK;
+
+  if( pagerUseWal(pPager) ){
+    int rc2;
+    rc = sqlite3PagerSavepoint(pPager, SAVEPOINT_ROLLBACK, -1);
+    rc2 = pager_end_transaction(pPager, pPager->setMaster);
+    if( rc==SQLITE_OK ) rc = rc2;
+  }else if( !isOpen(pPager->jfd) || pPager->eState==PAGER_WRITER_LOCKED ){
+    int eState = pPager->eState;
+    rc = pager_end_transaction(pPager, 0);
+    if( !MEMDB && eState>PAGER_WRITER_LOCKED ){
+      /* This can happen using journal_mode=off. Move the pager to the error 
+      ** state to indicate that the contents of the cache may not be trusted.
+      ** Any active readers will get SQLITE_ABORT.
+      */
+      pPager->errCode = SQLITE_ABORT;
+      pPager->eState = PAGER_ERROR;
+      return rc;
+    }
+  }else{
+    rc = pager_playback(pPager, 0);
+  }
+
+  assert( pPager->eState==PAGER_READER || rc!=SQLITE_OK );
+  assert( rc==SQLITE_OK || rc==SQLITE_FULL || (rc&0xFF)==SQLITE_IOERR );
+
+  /* If an error occurs during a ROLLBACK, we can no longer trust the pager
+  ** cache. So call pager_error() on the way out to make any error persistent.
+  */
+  return pager_error(pPager, rc);
+}
+
+/*
+** Return TRUE if the database file is opened read-only.  Return FALSE
+** if the database is (in theory) writable.
+*/
+SQLITE_PRIVATE u8 sqlite3PagerIsreadonly(Pager *pPager){
+  return pPager->readOnly;
+}
+
+/*
+** Return the number of references to the pager.
+*/
+SQLITE_PRIVATE int sqlite3PagerRefcount(Pager *pPager){
+  return sqlite3PcacheRefCount(pPager->pPCache);
+}
+
+/*
+** Return the approximate number of bytes of memory currently
+** used by the pager and its associated cache.
+*/
+SQLITE_PRIVATE int sqlite3PagerMemUsed(Pager *pPager){
+  int perPageSize = pPager->pageSize + pPager->nExtra + sizeof(PgHdr)
+                                     + 5*sizeof(void*);
+  return perPageSize*sqlite3PcachePagecount(pPager->pPCache)
+           + sqlite3MallocSize(pPager)
+           + pPager->pageSize;
+}
+
+/*
+** Return the number of references to the specified page.
+*/
+SQLITE_PRIVATE int sqlite3PagerPageRefcount(DbPage *pPage){
+  return sqlite3PcachePageRefcount(pPage);
+}
+
+#ifdef SQLITE_TEST
+/*
+** This routine is used for testing and analysis only.
+*/
+SQLITE_PRIVATE int *sqlite3PagerStats(Pager *pPager){
+  static int a[11];
+  a[0] = sqlite3PcacheRefCount(pPager->pPCache);
+  a[1] = sqlite3PcachePagecount(pPager->pPCache);
+  a[2] = sqlite3PcacheGetCachesize(pPager->pPCache);
+  a[3] = pPager->eState==PAGER_OPEN ? -1 : (int) pPager->dbSize;
+  a[4] = pPager->eState;
+  a[5] = pPager->errCode;
+  a[6] = pPager->nHit;
+  a[7] = pPager->nMiss;
+  a[8] = 0;  /* Used to be pPager->nOvfl */
+  a[9] = pPager->nRead;
+  a[10] = pPager->nWrite;
+  return a;
+}
+#endif
+
+/*
+** Return true if this is an in-memory pager.
+*/
+SQLITE_PRIVATE int sqlite3PagerIsMemdb(Pager *pPager){
+  return MEMDB;
+}
+
+/*
+** Check that there are at least nSavepoint savepoints open. If there are
+** currently less than nSavepoints open, then open one or more savepoints
+** to make up the difference. If the number of savepoints is already
+** equal to nSavepoint, then this function is a no-op.
+**
+** If a memory allocation fails, SQLITE_NOMEM is returned. If an error 
+** occurs while opening the sub-journal file, then an IO error code is
+** returned. Otherwise, SQLITE_OK.
+*/
+SQLITE_PRIVATE int sqlite3PagerOpenSavepoint(Pager *pPager, int nSavepoint){
+  int rc = SQLITE_OK;                       /* Return code */
+  int nCurrent = pPager->nSavepoint;        /* Current number of savepoints */
+
+  assert( pPager->eState>=PAGER_WRITER_LOCKED );
+  assert( assert_pager_state(pPager) );
+
+  if( nSavepoint>nCurrent && pPager->useJournal ){
+    int ii;                                 /* Iterator variable */
+    PagerSavepoint *aNew;                   /* New Pager.aSavepoint array */
+
+    /* Grow the Pager.aSavepoint array using realloc(). Return SQLITE_NOMEM
+    ** if the allocation fails. Otherwise, zero the new portion in case a 
+    ** malloc failure occurs while populating it in the for(...) loop below.
+    */
+    aNew = (PagerSavepoint *)sqlite3Realloc(
+        pPager->aSavepoint, sizeof(PagerSavepoint)*nSavepoint
+    );
+    if( !aNew ){
+      return SQLITE_NOMEM;
+    }
+    memset(&aNew[nCurrent], 0, (nSavepoint-nCurrent) * sizeof(PagerSavepoint));
+    pPager->aSavepoint = aNew;
+
+    /* Populate the PagerSavepoint structures just allocated. */
+    for(ii=nCurrent; ii<nSavepoint; ii++){
+      aNew[ii].nOrig = pPager->dbSize;
+      if( isOpen(pPager->jfd) && pPager->journalOff>0 ){
+        aNew[ii].iOffset = pPager->journalOff;
+      }else{
+        aNew[ii].iOffset = JOURNAL_HDR_SZ(pPager);
+      }
+      aNew[ii].iSubRec = pPager->nSubRec;
+      aNew[ii].pInSavepoint = sqlite3BitvecCreate(pPager->dbSize);
+      if( !aNew[ii].pInSavepoint ){
+        return SQLITE_NOMEM;
+      }
+      if( pagerUseWal(pPager) ){
+        sqlite3WalSavepoint(pPager->pWal, aNew[ii].aWalData);
+      }
+      pPager->nSavepoint = ii+1;
+    }
+    assert( pPager->nSavepoint==nSavepoint );
+    assertTruncateConstraint(pPager);
+  }
+
+  return rc;
+}
+
+/*
+** This function is called to rollback or release (commit) a savepoint.
+** The savepoint to release or rollback need not be the most recently 
+** created savepoint.
+**
+** Parameter op is always either SAVEPOINT_ROLLBACK or SAVEPOINT_RELEASE.
+** If it is SAVEPOINT_RELEASE, then release and destroy the savepoint with
+** index iSavepoint. If it is SAVEPOINT_ROLLBACK, then rollback all changes
+** that have occurred since the specified savepoint was created.
+**
+** The savepoint to rollback or release is identified by parameter 
+** iSavepoint. A value of 0 means to operate on the outermost savepoint
+** (the first created). A value of (Pager.nSavepoint-1) means operate
+** on the most recently created savepoint. If iSavepoint is greater than
+** (Pager.nSavepoint-1), then this function is a no-op.
+**
+** If a negative value is passed to this function, then the current
+** transaction is rolled back. This is different to calling 
+** sqlite3PagerRollback() because this function does not terminate
+** the transaction or unlock the database, it just restores the 
+** contents of the database to its original state. 
+**
+** In any case, all savepoints with an index greater than iSavepoint 
+** are destroyed. If this is a release operation (op==SAVEPOINT_RELEASE),
+** then savepoint iSavepoint is also destroyed.
+**
+** This function may return SQLITE_NOMEM if a memory allocation fails,
+** or an IO error code if an IO error occurs while rolling back a 
+** savepoint. If no errors occur, SQLITE_OK is returned.
+*/ 
+SQLITE_PRIVATE int sqlite3PagerSavepoint(Pager *pPager, int op, int iSavepoint){
+  int rc = pPager->errCode;       /* Return code */
+
+  assert( op==SAVEPOINT_RELEASE || op==SAVEPOINT_ROLLBACK );
+  assert( iSavepoint>=0 || op==SAVEPOINT_ROLLBACK );
+
+  if( rc==SQLITE_OK && iSavepoint<pPager->nSavepoint ){
+    int ii;            /* Iterator variable */
+    int nNew;          /* Number of remaining savepoints after this op. */
+
+    /* Figure out how many savepoints will still be active after this
+    ** operation. Store this value in nNew. Then free resources associated 
+    ** with any savepoints that are destroyed by this operation.
+    */
+    nNew = iSavepoint + (( op==SAVEPOINT_RELEASE ) ? 0 : 1);
+    for(ii=nNew; ii<pPager->nSavepoint; ii++){
+      sqlite3BitvecDestroy(pPager->aSavepoint[ii].pInSavepoint);
+    }
+    pPager->nSavepoint = nNew;
+
+    /* If this is a release of the outermost savepoint, truncate 
+    ** the sub-journal to zero bytes in size. */
+    if( op==SAVEPOINT_RELEASE ){
+      if( nNew==0 && isOpen(pPager->sjfd) ){
+        /* Only truncate if it is an in-memory sub-journal. */
+        if( sqlite3IsMemJournal(pPager->sjfd) ){
+          rc = sqlite3OsTruncate(pPager->sjfd, 0);
+          assert( rc==SQLITE_OK );
+        }
+        pPager->nSubRec = 0;
+      }
+    }
+    /* Else this is a rollback operation, playback the specified savepoint.
+    ** If this is a temp-file, it is possible that the journal file has
+    ** not yet been opened. In this case there have been no changes to
+    ** the database file, so the playback operation can be skipped.
+    */
+    else if( pagerUseWal(pPager) || isOpen(pPager->jfd) ){
+      PagerSavepoint *pSavepoint = (nNew==0)?0:&pPager->aSavepoint[nNew-1];
+      rc = pagerPlaybackSavepoint(pPager, pSavepoint);
+      assert(rc!=SQLITE_DONE);
+    }
+  }
+
+  return rc;
+}
+
+/*
+** Return the full pathname of the database file.
+*/
+SQLITE_PRIVATE const char *sqlite3PagerFilename(Pager *pPager){
+  return pPager->zFilename;
+}
+
+/*
+** Return the VFS structure for the pager.
+*/
+SQLITE_PRIVATE const sqlite3_vfs *sqlite3PagerVfs(Pager *pPager){
+  return pPager->pVfs;
+}
+
+/*
+** Return the file handle for the database file associated
+** with the pager.  This might return NULL if the file has
+** not yet been opened.
+*/
+SQLITE_PRIVATE sqlite3_file *sqlite3PagerFile(Pager *pPager){
+  return pPager->fd;
+}
+
+/*
+** Return the full pathname of the journal file.
+*/
+SQLITE_PRIVATE const char *sqlite3PagerJournalname(Pager *pPager){
+  return pPager->zJournal;
+}
+
+/*
+** Return true if fsync() calls are disabled for this pager.  Return FALSE
+** if fsync()s are executed normally.
+*/
+SQLITE_PRIVATE int sqlite3PagerNosync(Pager *pPager){
+  return pPager->noSync;
+}
+
+#ifdef SQLITE_HAS_CODEC
+/*
+** Set or retrieve the codec for this pager
+*/
+SQLITE_PRIVATE void sqlite3PagerSetCodec(
+  Pager *pPager,
+  void *(*xCodec)(void*,void*,Pgno,int),
+  void (*xCodecSizeChng)(void*,int,int),
+  void (*xCodecFree)(void*),
+  void *pCodec
+){
+  if( pPager->xCodecFree ) pPager->xCodecFree(pPager->pCodec);
+  pPager->xCodec = pPager->memDb ? 0 : xCodec;
+  pPager->xCodecSizeChng = xCodecSizeChng;
+  pPager->xCodecFree = xCodecFree;
+  pPager->pCodec = pCodec;
+  pagerReportSize(pPager);
+}
+SQLITE_PRIVATE void *sqlite3PagerGetCodec(Pager *pPager){
+  return pPager->pCodec;
+}
+#endif
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+/*
+** Move the page pPg to location pgno in the file.
+**
+** There must be no references to the page previously located at
+** pgno (which we call pPgOld) though that page is allowed to be
+** in cache.  If the page previously located at pgno is not already
+** in the rollback journal, it is not put there by by this routine.
+**
+** References to the page pPg remain valid. Updating any
+** meta-data associated with pPg (i.e. data stored in the nExtra bytes
+** allocated along with the page) is the responsibility of the caller.
+**
+** A transaction must be active when this routine is called. It used to be
+** required that a statement transaction was not active, but this restriction
+** has been removed (CREATE INDEX needs to move a page when a statement
+** transaction is active).
+**
+** If the fourth argument, isCommit, is non-zero, then this page is being
+** moved as part of a database reorganization just before the transaction 
+** is being committed. In this case, it is guaranteed that the database page 
+** pPg refers to will not be written to again within this transaction.
+**
+** This function may return SQLITE_NOMEM or an IO error code if an error
+** occurs. Otherwise, it returns SQLITE_OK.
+*/
+SQLITE_PRIVATE int sqlite3PagerMovepage(Pager *pPager, DbPage *pPg, Pgno pgno, int isCommit){
+  PgHdr *pPgOld;               /* The page being overwritten. */
+  Pgno needSyncPgno = 0;       /* Old value of pPg->pgno, if sync is required */
+  int rc;                      /* Return code */
+  Pgno origPgno;               /* The original page number */
+
+  assert( pPg->nRef>0 );
+  assert( pPager->eState==PAGER_WRITER_CACHEMOD
+       || pPager->eState==PAGER_WRITER_DBMOD
+  );
+  assert( assert_pager_state(pPager) );
+
+  /* In order to be able to rollback, an in-memory database must journal
+  ** the page we are moving from.
+  */
+  if( MEMDB ){
+    rc = sqlite3PagerWrite(pPg);
+    if( rc ) return rc;
+  }
+
+  /* If the page being moved is dirty and has not been saved by the latest
+  ** savepoint, then save the current contents of the page into the 
+  ** sub-journal now. This is required to handle the following scenario:
+  **
+  **   BEGIN;
+  **     <journal page X, then modify it in memory>
+  **     SAVEPOINT one;
+  **       <Move page X to location Y>
+  **     ROLLBACK TO one;
+  **
+  ** If page X were not written to the sub-journal here, it would not
+  ** be possible to restore its contents when the "ROLLBACK TO one"
+  ** statement were is processed.
+  **
+  ** subjournalPage() may need to allocate space to store pPg->pgno into
+  ** one or more savepoint bitvecs. This is the reason this function
+  ** may return SQLITE_NOMEM.
+  */
+  if( pPg->flags&PGHDR_DIRTY
+   && subjRequiresPage(pPg)
+   && SQLITE_OK!=(rc = subjournalPage(pPg))
+  ){
+    return rc;
+  }
+
+  PAGERTRACE(("MOVE %d page %d (needSync=%d) moves to %d\n", 
+      PAGERID(pPager), pPg->pgno, (pPg->flags&PGHDR_NEED_SYNC)?1:0, pgno));
+  IOTRACE(("MOVE %p %d %d\n", pPager, pPg->pgno, pgno))
+
+  /* If the journal needs to be sync()ed before page pPg->pgno can
+  ** be written to, store pPg->pgno in local variable needSyncPgno.
+  **
+  ** If the isCommit flag is set, there is no need to remember that
+  ** the journal needs to be sync()ed before database page pPg->pgno 
+  ** can be written to. The caller has already promised not to write to it.
+  */
+  if( (pPg->flags&PGHDR_NEED_SYNC) && !isCommit ){
+    needSyncPgno = pPg->pgno;
+    assert( pageInJournal(pPg) || pPg->pgno>pPager->dbOrigSize );
+    assert( pPg->flags&PGHDR_DIRTY );
+  }
+
+  /* If the cache contains a page with page-number pgno, remove it
+  ** from its hash chain. Also, if the PGHDR_NEED_SYNC flag was set for 
+  ** page pgno before the 'move' operation, it needs to be retained 
+  ** for the page moved there.
+  */
+  pPg->flags &= ~PGHDR_NEED_SYNC;
+  pPgOld = pager_lookup(pPager, pgno);
+  assert( !pPgOld || pPgOld->nRef==1 );
+  if( pPgOld ){
+    pPg->flags |= (pPgOld->flags&PGHDR_NEED_SYNC);
+    if( MEMDB ){
+      /* Do not discard pages from an in-memory database since we might
+      ** need to rollback later.  Just move the page out of the way. */
+      sqlite3PcacheMove(pPgOld, pPager->dbSize+1);
+    }else{
+      sqlite3PcacheDrop(pPgOld);
+    }
+  }
+
+  origPgno = pPg->pgno;
+  sqlite3PcacheMove(pPg, pgno);
+  sqlite3PcacheMakeDirty(pPg);
+
+  /* For an in-memory database, make sure the original page continues
+  ** to exist, in case the transaction needs to roll back.  Use pPgOld
+  ** as the original page since it has already been allocated.
+  */
+  if( MEMDB ){
+    assert( pPgOld );
+    sqlite3PcacheMove(pPgOld, origPgno);
+    sqlite3PagerUnref(pPgOld);
+  }
+
+  if( needSyncPgno ){
+    /* If needSyncPgno is non-zero, then the journal file needs to be 
+    ** sync()ed before any data is written to database file page needSyncPgno.
+    ** Currently, no such page exists in the page-cache and the 
+    ** "is journaled" bitvec flag has been set. This needs to be remedied by
+    ** loading the page into the pager-cache and setting the PGHDR_NEED_SYNC
+    ** flag.
+    **
+    ** If the attempt to load the page into the page-cache fails, (due
+    ** to a malloc() or IO failure), clear the bit in the pInJournal[]
+    ** array. Otherwise, if the page is loaded and written again in
+    ** this transaction, it may be written to the database file before
+    ** it is synced into the journal file. This way, it may end up in
+    ** the journal file twice, but that is not a problem.
+    */
+    PgHdr *pPgHdr;
+    rc = sqlite3PagerGet(pPager, needSyncPgno, &pPgHdr);
+    if( rc!=SQLITE_OK ){
+      if( needSyncPgno<=pPager->dbOrigSize ){
+        assert( pPager->pTmpSpace!=0 );
+        sqlite3BitvecClear(pPager->pInJournal, needSyncPgno, pPager->pTmpSpace);
+      }
+      return rc;
+    }
+    pPgHdr->flags |= PGHDR_NEED_SYNC;
+    sqlite3PcacheMakeDirty(pPgHdr);
+    sqlite3PagerUnref(pPgHdr);
+  }
+
+  return SQLITE_OK;
+}
+#endif
+
+/*
+** Return a pointer to the data for the specified page.
+*/
+SQLITE_PRIVATE void *sqlite3PagerGetData(DbPage *pPg){
+  assert( pPg->nRef>0 || pPg->pPager->memDb );
+  return pPg->pData;
+}
+
+/*
+** Return a pointer to the Pager.nExtra bytes of "extra" space 
+** allocated along with the specified page.
+*/
+SQLITE_PRIVATE void *sqlite3PagerGetExtra(DbPage *pPg){
+  return pPg->pExtra;
+}
+
+/*
+** Get/set the locking-mode for this pager. Parameter eMode must be one
+** of PAGER_LOCKINGMODE_QUERY, PAGER_LOCKINGMODE_NORMAL or 
+** PAGER_LOCKINGMODE_EXCLUSIVE. If the parameter is not _QUERY, then
+** the locking-mode is set to the value specified.
+**
+** The returned value is either PAGER_LOCKINGMODE_NORMAL or
+** PAGER_LOCKINGMODE_EXCLUSIVE, indicating the current (possibly updated)
+** locking-mode.
+*/
+SQLITE_PRIVATE int sqlite3PagerLockingMode(Pager *pPager, int eMode){
+  assert( eMode==PAGER_LOCKINGMODE_QUERY
+            || eMode==PAGER_LOCKINGMODE_NORMAL
+            || eMode==PAGER_LOCKINGMODE_EXCLUSIVE );
+  assert( PAGER_LOCKINGMODE_QUERY<0 );
+  assert( PAGER_LOCKINGMODE_NORMAL>=0 && PAGER_LOCKINGMODE_EXCLUSIVE>=0 );
+  assert( pPager->exclusiveMode || 0==sqlite3WalHeapMemory(pPager->pWal) );
+  if( eMode>=0 && !pPager->tempFile && !sqlite3WalHeapMemory(pPager->pWal) ){
+    pPager->exclusiveMode = (u8)eMode;
+  }
+  return (int)pPager->exclusiveMode;
+}
+
+/*
+** Set the journal-mode for this pager. Parameter eMode must be one of:
+**
+**    PAGER_JOURNALMODE_DELETE
+**    PAGER_JOURNALMODE_TRUNCATE
+**    PAGER_JOURNALMODE_PERSIST
+**    PAGER_JOURNALMODE_OFF
+**    PAGER_JOURNALMODE_MEMORY
+**    PAGER_JOURNALMODE_WAL
+**
+** The journalmode is set to the value specified if the change is allowed.
+** The change may be disallowed for the following reasons:
+**
+**   *  An in-memory database can only have its journal_mode set to _OFF
+**      or _MEMORY.
+**
+**   *  Temporary databases cannot have _WAL journalmode.
+**
+** The returned indicate the current (possibly updated) journal-mode.
+*/
+SQLITE_PRIVATE int sqlite3PagerSetJournalMode(Pager *pPager, int eMode){
+  u8 eOld = pPager->journalMode;    /* Prior journalmode */
+
+#ifdef SQLITE_DEBUG
+  /* The print_pager_state() routine is intended to be used by the debugger
+  ** only.  We invoke it once here to suppress a compiler warning. */
+  print_pager_state(pPager);
+#endif
+
+
+  /* The eMode parameter is always valid */
+  assert(      eMode==PAGER_JOURNALMODE_DELETE
+            || eMode==PAGER_JOURNALMODE_TRUNCATE
+            || eMode==PAGER_JOURNALMODE_PERSIST
+            || eMode==PAGER_JOURNALMODE_OFF 
+            || eMode==PAGER_JOURNALMODE_WAL 
+            || eMode==PAGER_JOURNALMODE_MEMORY );
+
+  /* This routine is only called from the OP_JournalMode opcode, and
+  ** the logic there will never allow a temporary file to be changed
+  ** to WAL mode.
+  */
+  assert( pPager->tempFile==0 || eMode!=PAGER_JOURNALMODE_WAL );
+
+  /* Do allow the journalmode of an in-memory database to be set to
+  ** anything other than MEMORY or OFF
+  */
+  if( MEMDB ){
+    assert( eOld==PAGER_JOURNALMODE_MEMORY || eOld==PAGER_JOURNALMODE_OFF );
+    if( eMode!=PAGER_JOURNALMODE_MEMORY && eMode!=PAGER_JOURNALMODE_OFF ){
+      eMode = eOld;
+    }
+  }
+
+  if( eMode!=eOld ){
+
+    /* Change the journal mode. */
+    assert( pPager->eState!=PAGER_ERROR );
+    pPager->journalMode = (u8)eMode;
+
+    /* When transistioning from TRUNCATE or PERSIST to any other journal
+    ** mode except WAL, unless the pager is in locking_mode=exclusive mode,
+    ** delete the journal file.
+    */
+    assert( (PAGER_JOURNALMODE_TRUNCATE & 5)==1 );
+    assert( (PAGER_JOURNALMODE_PERSIST & 5)==1 );
+    assert( (PAGER_JOURNALMODE_DELETE & 5)==0 );
+    assert( (PAGER_JOURNALMODE_MEMORY & 5)==4 );
+    assert( (PAGER_JOURNALMODE_OFF & 5)==0 );
+    assert( (PAGER_JOURNALMODE_WAL & 5)==5 );
+
+    assert( isOpen(pPager->fd) || pPager->exclusiveMode );
+    if( !pPager->exclusiveMode && (eOld & 5)==1 && (eMode & 1)==0 ){
+
+      /* In this case we would like to delete the journal file. If it is
+      ** not possible, then that is not a problem. Deleting the journal file
+      ** here is an optimization only.
+      **
+      ** Before deleting the journal file, obtain a RESERVED lock on the
+      ** database file. This ensures that the journal file is not deleted
+      ** while it is in use by some other client.
+      */
+      sqlite3OsClose(pPager->jfd);
+      if( pPager->eLock>=RESERVED_LOCK ){
+        sqlite3OsDelete(pPager->pVfs, pPager->zJournal, 0);
+      }else{
+        int rc = SQLITE_OK;
+        int state = pPager->eState;
+        assert( state==PAGER_OPEN || state==PAGER_READER );
+        if( state==PAGER_OPEN ){
+          rc = sqlite3PagerSharedLock(pPager);
+        }
+        if( pPager->eState==PAGER_READER ){
+          assert( rc==SQLITE_OK );
+          rc = pagerLockDb(pPager, RESERVED_LOCK);
+        }
+        if( rc==SQLITE_OK ){
+          sqlite3OsDelete(pPager->pVfs, pPager->zJournal, 0);
+        }
+        if( rc==SQLITE_OK && state==PAGER_READER ){
+          pagerUnlockDb(pPager, SHARED_LOCK);
+        }else if( state==PAGER_OPEN ){
+          pager_unlock(pPager);
+        }
+        assert( state==pPager->eState );
+      }
+    }
+  }
+
+  /* Return the new journal mode */
+  return (int)pPager->journalMode;
+}
+
+/*
+** Return the current journal mode.
+*/
+SQLITE_PRIVATE int sqlite3PagerGetJournalMode(Pager *pPager){
+  return (int)pPager->journalMode;
+}
+
+/*
+** Return TRUE if the pager is in a state where it is OK to change the
+** journalmode.  Journalmode changes can only happen when the database
+** is unmodified.
+*/
+SQLITE_PRIVATE int sqlite3PagerOkToChangeJournalMode(Pager *pPager){
+  assert( assert_pager_state(pPager) );
+  if( pPager->eState>=PAGER_WRITER_CACHEMOD ) return 0;
+  if( NEVER(isOpen(pPager->jfd) && pPager->journalOff>0) ) return 0;
+  return 1;
+}
+
+/*
+** Get/set the size-limit used for persistent journal files.
+**
+** Setting the size limit to -1 means no limit is enforced.
+** An attempt to set a limit smaller than -1 is a no-op.
+*/
+SQLITE_PRIVATE i64 sqlite3PagerJournalSizeLimit(Pager *pPager, i64 iLimit){
+  if( iLimit>=-1 ){
+    pPager->journalSizeLimit = iLimit;
+  }
+  return pPager->journalSizeLimit;
+}
+
+/*
+** Return a pointer to the pPager->pBackup variable. The backup module
+** in backup.c maintains the content of this variable. This module
+** uses it opaquely as an argument to sqlite3BackupRestart() and
+** sqlite3BackupUpdate() only.
+*/
+SQLITE_PRIVATE sqlite3_backup **sqlite3PagerBackupPtr(Pager *pPager){
+  return &pPager->pBackup;
+}
+
+#ifndef SQLITE_OMIT_WAL
+/*
+** This function is called when the user invokes "PRAGMA wal_checkpoint",
+** "PRAGMA wal_blocking_checkpoint" or calls the sqlite3_wal_checkpoint()
+** or wal_blocking_checkpoint() API functions.
+**
+** Parameter eMode is one of SQLITE_CHECKPOINT_PASSIVE, FULL or RESTART.
+*/
+SQLITE_PRIVATE int sqlite3PagerCheckpoint(Pager *pPager, int eMode, int *pnLog, int *pnCkpt){
+  int rc = SQLITE_OK;
+  if( pPager->pWal ){
+    rc = sqlite3WalCheckpoint(pPager->pWal, eMode,
+        pPager->xBusyHandler, pPager->pBusyHandlerArg,
+        pPager->ckptSyncFlags, pPager->pageSize, (u8 *)pPager->pTmpSpace,
+        pnLog, pnCkpt
+    );
+  }
+  return rc;
+}
+
+SQLITE_PRIVATE int sqlite3PagerWalCallback(Pager *pPager){
+  return sqlite3WalCallback(pPager->pWal);
+}
+
+/*
+** Return true if the underlying VFS for the given pager supports the
+** primitives necessary for write-ahead logging.
+*/
+SQLITE_PRIVATE int sqlite3PagerWalSupported(Pager *pPager){
+  const sqlite3_io_methods *pMethods = pPager->fd->pMethods;
+  return pPager->exclusiveMode || (pMethods->iVersion>=2 && pMethods->xShmMap);
+}
+
+/*
+** Attempt to take an exclusive lock on the database file. If a PENDING lock
+** is obtained instead, immediately release it.
+*/
+static int pagerExclusiveLock(Pager *pPager){
+  int rc;                         /* Return code */
+
+  assert( pPager->eLock==SHARED_LOCK || pPager->eLock==EXCLUSIVE_LOCK );
+  rc = pagerLockDb(pPager, EXCLUSIVE_LOCK);
+  if( rc!=SQLITE_OK ){
+    /* If the attempt to grab the exclusive lock failed, release the 
+    ** pending lock that may have been obtained instead.  */
+    pagerUnlockDb(pPager, SHARED_LOCK);
+  }
+
+  return rc;
+}
+
+/*
+** Call sqlite3WalOpen() to open the WAL handle. If the pager is in 
+** exclusive-locking mode when this function is called, take an EXCLUSIVE
+** lock on the database file and use heap-memory to store the wal-index
+** in. Otherwise, use the normal shared-memory.
+*/
+static int pagerOpenWal(Pager *pPager){
+  int rc = SQLITE_OK;
+
+  assert( pPager->pWal==0 && pPager->tempFile==0 );
+  assert( pPager->eLock==SHARED_LOCK || pPager->eLock==EXCLUSIVE_LOCK || pPager->noReadlock);
+
+  /* If the pager is already in exclusive-mode, the WAL module will use 
+  ** heap-memory for the wal-index instead of the VFS shared-memory 
+  ** implementation. Take the exclusive lock now, before opening the WAL
+  ** file, to make sure this is safe.
+  */
+  if( pPager->exclusiveMode ){
+    rc = pagerExclusiveLock(pPager);
+  }
+
+  /* Open the connection to the log file. If this operation fails, 
+  ** (e.g. due to malloc() failure), return an error code.
+  */
+  if( rc==SQLITE_OK ){
+    rc = sqlite3WalOpen(pPager->pVfs, 
+        pPager->fd, pPager->zWal, pPager->exclusiveMode, &pPager->pWal
+    );
+  }
+
+  return rc;
+}
+
+
+/*
+** The caller must be holding a SHARED lock on the database file to call
+** this function.
+**
+** If the pager passed as the first argument is open on a real database
+** file (not a temp file or an in-memory database), and the WAL file
+** is not already open, make an attempt to open it now. If successful,
+** return SQLITE_OK. If an error occurs or the VFS used by the pager does 
+** not support the xShmXXX() methods, return an error code. *pbOpen is
+** not modified in either case.
+**
+** If the pager is open on a temp-file (or in-memory database), or if
+** the WAL file is already open, set *pbOpen to 1 and return SQLITE_OK
+** without doing anything.
+*/
+SQLITE_PRIVATE int sqlite3PagerOpenWal(
+  Pager *pPager,                  /* Pager object */
+  int *pbOpen                     /* OUT: Set to true if call is a no-op */
+){
+  int rc = SQLITE_OK;             /* Return code */
+
+  assert( assert_pager_state(pPager) );
+  assert( pPager->eState==PAGER_OPEN   || pbOpen );
+  assert( pPager->eState==PAGER_READER || !pbOpen );
+  assert( pbOpen==0 || *pbOpen==0 );
+  assert( pbOpen!=0 || (!pPager->tempFile && !pPager->pWal) );
+
+  if( !pPager->tempFile && !pPager->pWal ){
+    if( !sqlite3PagerWalSupported(pPager) ) return SQLITE_CANTOPEN;
+
+    /* Close any rollback journal previously open */
+    sqlite3OsClose(pPager->jfd);
+
+    rc = pagerOpenWal(pPager);
+    if( rc==SQLITE_OK ){
+      pPager->journalMode = PAGER_JOURNALMODE_WAL;
+      pPager->eState = PAGER_OPEN;
+    }
+  }else{
+    *pbOpen = 1;
+  }
+
+  return rc;
+}
+
+/*
+** This function is called to close the connection to the log file prior
+** to switching from WAL to rollback mode.
+**
+** Before closing the log file, this function attempts to take an 
+** EXCLUSIVE lock on the database file. If this cannot be obtained, an
+** error (SQLITE_BUSY) is returned and the log connection is not closed.
+** If successful, the EXCLUSIVE lock is not released before returning.
+*/
+SQLITE_PRIVATE int sqlite3PagerCloseWal(Pager *pPager){
+  int rc = SQLITE_OK;
+
+  assert( pPager->journalMode==PAGER_JOURNALMODE_WAL );
+
+  /* If the log file is not already open, but does exist in the file-system,
+  ** it may need to be checkpointed before the connection can switch to
+  ** rollback mode. Open it now so this can happen.
+  */
+  if( !pPager->pWal ){
+    int logexists = 0;
+    rc = pagerLockDb(pPager, SHARED_LOCK);
+    if( rc==SQLITE_OK ){
+      rc = sqlite3OsAccess(
+          pPager->pVfs, pPager->zWal, SQLITE_ACCESS_EXISTS, &logexists
+      );
+    }
+    if( rc==SQLITE_OK && logexists ){
+      rc = pagerOpenWal(pPager);
+    }
+  }
+    
+  /* Checkpoint and close the log. Because an EXCLUSIVE lock is held on
+  ** the database file, the log and log-summary files will be deleted.
+  */
+  if( rc==SQLITE_OK && pPager->pWal ){
+    rc = pagerExclusiveLock(pPager);
+    if( rc==SQLITE_OK ){
+      rc = sqlite3WalClose(pPager->pWal, pPager->ckptSyncFlags,
+                           pPager->pageSize, (u8*)pPager->pTmpSpace);
+      pPager->pWal = 0;
+    }
+  }
+  return rc;
+}
+
+#ifdef SQLITE_HAS_CODEC
+/*
+** This function is called by the wal module when writing page content
+** into the log file.
+**
+** This function returns a pointer to a buffer containing the encrypted
+** page content. If a malloc fails, this function may return NULL.
+*/
+SQLITE_PRIVATE void *sqlite3PagerCodec(PgHdr *pPg){
+  void *aData = 0;
+  CODEC2(pPg->pPager, pPg->pData, pPg->pgno, 6, return 0, aData);
+  return aData;
+}
+#endif /* SQLITE_HAS_CODEC */
+
+#endif /* !SQLITE_OMIT_WAL */
+
+#endif /* SQLITE_OMIT_DISKIO */
+
+/************** End of pager.c ***********************************************/
+/************** Begin file wal.c *********************************************/
+/*
+** 2010 February 1
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains the implementation of a write-ahead log (WAL) used in 
+** "journal_mode=WAL" mode.
+**
+** WRITE-AHEAD LOG (WAL) FILE FORMAT
+**
+** A WAL file consists of a header followed by zero or more "frames".
+** Each frame records the revised content of a single page from the
+** database file.  All changes to the database are recorded by writing
+** frames into the WAL.  Transactions commit when a frame is written that
+** contains a commit marker.  A single WAL can and usually does record 
+** multiple transactions.  Periodically, the content of the WAL is
+** transferred back into the database file in an operation called a
+** "checkpoint".
+**
+** A single WAL file can be used multiple times.  In other words, the
+** WAL can fill up with frames and then be checkpointed and then new
+** frames can overwrite the old ones.  A WAL always grows from beginning
+** toward the end.  Checksums and counters attached to each frame are
+** used to determine which frames within the WAL are valid and which
+** are leftovers from prior checkpoints.
+**
+** The WAL header is 32 bytes in size and consists of the following eight
+** big-endian 32-bit unsigned integer values:
+**
+**     0: Magic number.  0x377f0682 or 0x377f0683
+**     4: File format version.  Currently 3007000
+**     8: Database page size.  Example: 1024
+**    12: Checkpoint sequence number
+**    16: Salt-1, random integer incremented with each checkpoint
+**    20: Salt-2, a different random integer changing with each ckpt
+**    24: Checksum-1 (first part of checksum for first 24 bytes of header).
+**    28: Checksum-2 (second part of checksum for first 24 bytes of header).
+**
+** Immediately following the wal-header are zero or more frames. Each
+** frame consists of a 24-byte frame-header followed by a <page-size> bytes
+** of page data. The frame-header is six big-endian 32-bit unsigned 
+** integer values, as follows:
+**
+**     0: Page number.
+**     4: For commit records, the size of the database image in pages 
+**        after the commit. For all other records, zero.
+**     8: Salt-1 (copied from the header)
+**    12: Salt-2 (copied from the header)
+**    16: Checksum-1.
+**    20: Checksum-2.
+**
+** A frame is considered valid if and only if the following conditions are
+** true:
+**
+**    (1) The salt-1 and salt-2 values in the frame-header match
+**        salt values in the wal-header
+**
+**    (2) The checksum values in the final 8 bytes of the frame-header
+**        exactly match the checksum computed consecutively on the
+**        WAL header and the first 8 bytes and the content of all frames
+**        up to and including the current frame.
+**
+** The checksum is computed using 32-bit big-endian integers if the
+** magic number in the first 4 bytes of the WAL is 0x377f0683 and it
+** is computed using little-endian if the magic number is 0x377f0682.
+** The checksum values are always stored in the frame header in a
+** big-endian format regardless of which byte order is used to compute
+** the checksum.  The checksum is computed by interpreting the input as
+** an even number of unsigned 32-bit integers: x[0] through x[N].  The
+** algorithm used for the checksum is as follows:
+** 
+**   for i from 0 to n-1 step 2:
+**     s0 += x[i] + s1;
+**     s1 += x[i+1] + s0;
+**   endfor
+**
+** Note that s0 and s1 are both weighted checksums using fibonacci weights
+** in reverse order (the largest fibonacci weight occurs on the first element
+** of the sequence being summed.)  The s1 value spans all 32-bit 
+** terms of the sequence whereas s0 omits the final term.
+**
+** On a checkpoint, the WAL is first VFS.xSync-ed, then valid content of the
+** WAL is transferred into the database, then the database is VFS.xSync-ed.
+** The VFS.xSync operations serve as write barriers - all writes launched
+** before the xSync must complete before any write that launches after the
+** xSync begins.
+**
+** After each checkpoint, the salt-1 value is incremented and the salt-2
+** value is randomized.  This prevents old and new frames in the WAL from
+** being considered valid at the same time and being checkpointing together
+** following a crash.
+**
+** READER ALGORITHM
+**
+** To read a page from the database (call it page number P), a reader
+** first checks the WAL to see if it contains page P.  If so, then the
+** last valid instance of page P that is a followed by a commit frame
+** or is a commit frame itself becomes the value read.  If the WAL
+** contains no copies of page P that are valid and which are a commit
+** frame or are followed by a commit frame, then page P is read from
+** the database file.
+**
+** To start a read transaction, the reader records the index of the last
+** valid frame in the WAL.  The reader uses this recorded "mxFrame" value
+** for all subsequent read operations.  New transactions can be appended
+** to the WAL, but as long as the reader uses its original mxFrame value
+** and ignores the newly appended content, it will see a consistent snapshot
+** of the database from a single point in time.  This technique allows
+** multiple concurrent readers to view different versions of the database
+** content simultaneously.
+**
+** The reader algorithm in the previous paragraphs works correctly, but 
+** because frames for page P can appear anywhere within the WAL, the
+** reader has to scan the entire WAL looking for page P frames.  If the
+** WAL is large (multiple megabytes is typical) that scan can be slow,
+** and read performance suffers.  To overcome this problem, a separate
+** data structure called the wal-index is maintained to expedite the
+** search for frames of a particular page.
+** 
+** WAL-INDEX FORMAT
+**
+** Conceptually, the wal-index is shared memory, though VFS implementations
+** might choose to implement the wal-index using a mmapped file.  Because
+** the wal-index is shared memory, SQLite does not support journal_mode=WAL 
+** on a network filesystem.  All users of the database must be able to
+** share memory.
+**
+** The wal-index is transient.  After a crash, the wal-index can (and should
+** be) reconstructed from the original WAL file.  In fact, the VFS is required
+** to either truncate or zero the header of the wal-index when the last
+** connection to it closes.  Because the wal-index is transient, it can
+** use an architecture-specific format; it does not have to be cross-platform.
+** Hence, unlike the database and WAL file formats which store all values
+** as big endian, the wal-index can store multi-byte values in the native
+** byte order of the host computer.
+**
+** The purpose of the wal-index is to answer this question quickly:  Given
+** a page number P, return the index of the last frame for page P in the WAL,
+** or return NULL if there are no frames for page P in the WAL.
+**
+** The wal-index consists of a header region, followed by an one or
+** more index blocks.  
+**
+** The wal-index header contains the total number of frames within the WAL
+** in the the mxFrame field.  
+**
+** Each index block except for the first contains information on 
+** HASHTABLE_NPAGE frames. The first index block contains information on
+** HASHTABLE_NPAGE_ONE frames. The values of HASHTABLE_NPAGE_ONE and 
+** HASHTABLE_NPAGE are selected so that together the wal-index header and
+** first index block are the same size as all other index blocks in the
+** wal-index.
+**
+** Each index block contains two sections, a page-mapping that contains the
+** database page number associated with each wal frame, and a hash-table 
+** that allows readers to query an index block for a specific page number.
+** The page-mapping is an array of HASHTABLE_NPAGE (or HASHTABLE_NPAGE_ONE
+** for the first index block) 32-bit page numbers. The first entry in the 
+** first index-block contains the database page number corresponding to the
+** first frame in the WAL file. The first entry in the second index block
+** in the WAL file corresponds to the (HASHTABLE_NPAGE_ONE+1)th frame in
+** the log, and so on.
+**
+** The last index block in a wal-index usually contains less than the full
+** complement of HASHTABLE_NPAGE (or HASHTABLE_NPAGE_ONE) page-numbers,
+** depending on the contents of the WAL file. This does not change the
+** allocated size of the page-mapping array - the page-mapping array merely
+** contains unused entries.
+**
+** Even without using the hash table, the last frame for page P
+** can be found by scanning the page-mapping sections of each index block
+** starting with the last index block and moving toward the first, and
+** within each index block, starting at the end and moving toward the
+** beginning.  The first entry that equals P corresponds to the frame
+** holding the content for that page.
+**
+** The hash table consists of HASHTABLE_NSLOT 16-bit unsigned integers.
+** HASHTABLE_NSLOT = 2*HASHTABLE_NPAGE, and there is one entry in the
+** hash table for each page number in the mapping section, so the hash 
+** table is never more than half full.  The expected number of collisions 
+** prior to finding a match is 1.  Each entry of the hash table is an
+** 1-based index of an entry in the mapping section of the same
+** index block.   Let K be the 1-based index of the largest entry in
+** the mapping section.  (For index blocks other than the last, K will
+** always be exactly HASHTABLE_NPAGE (4096) and for the last index block
+** K will be (mxFrame%HASHTABLE_NPAGE).)  Unused slots of the hash table
+** contain a value of 0.
+**
+** To look for page P in the hash table, first compute a hash iKey on
+** P as follows:
+**
+**      iKey = (P * 383) % HASHTABLE_NSLOT
+**
+** Then start scanning entries of the hash table, starting with iKey
+** (wrapping around to the beginning when the end of the hash table is
+** reached) until an unused hash slot is found. Let the first unused slot
+** be at index iUnused.  (iUnused might be less than iKey if there was
+** wrap-around.) Because the hash table is never more than half full,
+** the search is guaranteed to eventually hit an unused entry.  Let 
+** iMax be the value between iKey and iUnused, closest to iUnused,
+** where aHash[iMax]==P.  If there is no iMax entry (if there exists
+** no hash slot such that aHash[i]==p) then page P is not in the
+** current index block.  Otherwise the iMax-th mapping entry of the
+** current index block corresponds to the last entry that references 
+** page P.
+**
+** A hash search begins with the last index block and moves toward the
+** first index block, looking for entries corresponding to page P.  On
+** average, only two or three slots in each index block need to be
+** examined in order to either find the last entry for page P, or to
+** establish that no such entry exists in the block.  Each index block
+** holds over 4000 entries.  So two or three index blocks are sufficient
+** to cover a typical 10 megabyte WAL file, assuming 1K pages.  8 or 10
+** comparisons (on average) suffice to either locate a frame in the
+** WAL or to establish that the frame does not exist in the WAL.  This
+** is much faster than scanning the entire 10MB WAL.
+**
+** Note that entries are added in order of increasing K.  Hence, one
+** reader might be using some value K0 and a second reader that started
+** at a later time (after additional transactions were added to the WAL
+** and to the wal-index) might be using a different value K1, where K1>K0.
+** Both readers can use the same hash table and mapping section to get
+** the correct result.  There may be entries in the hash table with
+** K>K0 but to the first reader, those entries will appear to be unused
+** slots in the hash table and so the first reader will get an answer as
+** if no values greater than K0 had ever been inserted into the hash table
+** in the first place - which is what reader one wants.  Meanwhile, the
+** second reader using K1 will see additional values that were inserted
+** later, which is exactly what reader two wants.  
+**
+** When a rollback occurs, the value of K is decreased. Hash table entries
+** that correspond to frames greater than the new K value are removed
+** from the hash table at this point.
+*/
+#ifndef SQLITE_OMIT_WAL
+
+
+/*
+** Trace output macros
+*/
+#if defined(SQLITE_TEST) && defined(SQLITE_DEBUG)
+SQLITE_PRIVATE int sqlite3WalTrace = 0;
+# define WALTRACE(X)  if(sqlite3WalTrace) sqlite3DebugPrintf X
+#else
+# define WALTRACE(X)
+#endif
+
+/*
+** The maximum (and only) versions of the wal and wal-index formats
+** that may be interpreted by this version of SQLite.
+**
+** If a client begins recovering a WAL file and finds that (a) the checksum
+** values in the wal-header are correct and (b) the version field is not
+** WAL_MAX_VERSION, recovery fails and SQLite returns SQLITE_CANTOPEN.
+**
+** Similarly, if a client successfully reads a wal-index header (i.e. the 
+** checksum test is successful) and finds that the version field is not
+** WALINDEX_MAX_VERSION, then no read-transaction is opened and SQLite
+** returns SQLITE_CANTOPEN.
+*/
+#define WAL_MAX_VERSION      3007000
+#define WALINDEX_MAX_VERSION 3007000
+
+/*
+** Indices of various locking bytes.   WAL_NREADER is the number
+** of available reader locks and should be at least 3.
+*/
+#define WAL_WRITE_LOCK         0
+#define WAL_ALL_BUT_WRITE      1
+#define WAL_CKPT_LOCK          1
+#define WAL_RECOVER_LOCK       2
+#define WAL_READ_LOCK(I)       (3+(I))
+#define WAL_NREADER            (SQLITE_SHM_NLOCK-3)
+
+
+/* Object declarations */
+typedef struct WalIndexHdr WalIndexHdr;
+typedef struct WalIterator WalIterator;
+typedef struct WalCkptInfo WalCkptInfo;
+
+
+/*
+** The following object holds a copy of the wal-index header content.
+**
+** The actual header in the wal-index consists of two copies of this
+** object.
+**
+** The szPage value can be any power of 2 between 512 and 32768, inclusive.
+** Or it can be 1 to represent a 65536-byte page.  The latter case was
+** added in 3.7.1 when support for 64K pages was added.  
+*/
+struct WalIndexHdr {
+  u32 iVersion;                   /* Wal-index version */
+  u32 unused;                     /* Unused (padding) field */
+  u32 iChange;                    /* Counter incremented each transaction */
+  u8 isInit;                      /* 1 when initialized */
+  u8 bigEndCksum;                 /* True if checksums in WAL are big-endian */
+  u16 szPage;                     /* Database page size in bytes. 1==64K */
+  u32 mxFrame;                    /* Index of last valid frame in the WAL */
+  u32 nPage;                      /* Size of database in pages */
+  u32 aFrameCksum[2];             /* Checksum of last frame in log */
+  u32 aSalt[2];                   /* Two salt values copied from WAL header */
+  u32 aCksum[2];                  /* Checksum over all prior fields */
+};
+
+/*
+** A copy of the following object occurs in the wal-index immediately
+** following the second copy of the WalIndexHdr.  This object stores
+** information used by checkpoint.
+**
+** nBackfill is the number of frames in the WAL that have been written
+** back into the database. (We call the act of moving content from WAL to
+** database "backfilling".)  The nBackfill number is never greater than
+** WalIndexHdr.mxFrame.  nBackfill can only be increased by threads
+** holding the WAL_CKPT_LOCK lock (which includes a recovery thread).
+** However, a WAL_WRITE_LOCK thread can move the value of nBackfill from
+** mxFrame back to zero when the WAL is reset.
+**
+** There is one entry in aReadMark[] for each reader lock.  If a reader
+** holds read-lock K, then the value in aReadMark[K] is no greater than
+** the mxFrame for that reader.  The value READMARK_NOT_USED (0xffffffff)
+** for any aReadMark[] means that entry is unused.  aReadMark[0] is 
+** a special case; its value is never used and it exists as a place-holder
+** to avoid having to offset aReadMark[] indexs by one.  Readers holding
+** WAL_READ_LOCK(0) always ignore the entire WAL and read all content
+** directly from the database.
+**
+** The value of aReadMark[K] may only be changed by a thread that
+** is holding an exclusive lock on WAL_READ_LOCK(K).  Thus, the value of
+** aReadMark[K] cannot changed while there is a reader is using that mark
+** since the reader will be holding a shared lock on WAL_READ_LOCK(K).
+**
+** The checkpointer may only transfer frames from WAL to database where
+** the frame numbers are less than or equal to every aReadMark[] that is
+** in use (that is, every aReadMark[j] for which there is a corresponding
+** WAL_READ_LOCK(j)).  New readers (usually) pick the aReadMark[] with the
+** largest value and will increase an unused aReadMark[] to mxFrame if there
+** is not already an aReadMark[] equal to mxFrame.  The exception to the
+** previous sentence is when nBackfill equals mxFrame (meaning that everything
+** in the WAL has been backfilled into the database) then new readers
+** will choose aReadMark[0] which has value 0 and hence such reader will
+** get all their all content directly from the database file and ignore 
+** the WAL.
+**
+** Writers normally append new frames to the end of the WAL.  However,
+** if nBackfill equals mxFrame (meaning that all WAL content has been
+** written back into the database) and if no readers are using the WAL
+** (in other words, if there are no WAL_READ_LOCK(i) where i>0) then
+** the writer will first "reset" the WAL back to the beginning and start
+** writing new content beginning at frame 1.
+**
+** We assume that 32-bit loads are atomic and so no locks are needed in
+** order to read from any aReadMark[] entries.
+*/
+struct WalCkptInfo {
+  u32 nBackfill;                  /* Number of WAL frames backfilled into DB */
+  u32 aReadMark[WAL_NREADER];     /* Reader marks */
+};
+#define READMARK_NOT_USED  0xffffffff
+
+
+/* A block of WALINDEX_LOCK_RESERVED bytes beginning at
+** WALINDEX_LOCK_OFFSET is reserved for locks. Since some systems
+** only support mandatory file-locks, we do not read or write data
+** from the region of the file on which locks are applied.
+*/
+#define WALINDEX_LOCK_OFFSET   (sizeof(WalIndexHdr)*2 + sizeof(WalCkptInfo))
+#define WALINDEX_LOCK_RESERVED 16
+#define WALINDEX_HDR_SIZE      (WALINDEX_LOCK_OFFSET+WALINDEX_LOCK_RESERVED)
+
+/* Size of header before each frame in wal */
+#define WAL_FRAME_HDRSIZE 24
+
+/* Size of write ahead log header, including checksum. */
+/* #define WAL_HDRSIZE 24 */
+#define WAL_HDRSIZE 32
+
+/* WAL magic value. Either this value, or the same value with the least
+** significant bit also set (WAL_MAGIC | 0x00000001) is stored in 32-bit
+** big-endian format in the first 4 bytes of a WAL file.
+**
+** If the LSB is set, then the checksums for each frame within the WAL
+** file are calculated by treating all data as an array of 32-bit 
+** big-endian words. Otherwise, they are calculated by interpreting 
+** all data as 32-bit little-endian words.
+*/
+#define WAL_MAGIC 0x377f0682
+
+/*
+** Return the offset of frame iFrame in the write-ahead log file, 
+** assuming a database page size of szPage bytes. The offset returned
+** is to the start of the write-ahead log frame-header.
+*/
+#define walFrameOffset(iFrame, szPage) (                               \
+  WAL_HDRSIZE + ((iFrame)-1)*(i64)((szPage)+WAL_FRAME_HDRSIZE)         \
+)
+
+/*
+** An open write-ahead log file is represented by an instance of the
+** following object.
+*/
+struct Wal {
+  sqlite3_vfs *pVfs;         /* The VFS used to create pDbFd */
+  sqlite3_file *pDbFd;       /* File handle for the database file */
+  sqlite3_file *pWalFd;      /* File handle for WAL file */
+  u32 iCallback;             /* Value to pass to log callback (or 0) */
+  int nWiData;               /* Size of array apWiData */
+  volatile u32 **apWiData;   /* Pointer to wal-index content in memory */
+  u32 szPage;                /* Database page size */
+  i16 readLock;              /* Which read lock is being held.  -1 for none */
+  u8 exclusiveMode;          /* Non-zero if connection is in exclusive mode */
+  u8 writeLock;              /* True if in a write transaction */
+  u8 ckptLock;               /* True if holding a checkpoint lock */
+  u8 readOnly;               /* True if the WAL file is open read-only */
+  WalIndexHdr hdr;           /* Wal-index header for current transaction */
+  const char *zWalName;      /* Name of WAL file */
+  u32 nCkpt;                 /* Checkpoint sequence counter in the wal-header */
+#ifdef SQLITE_DEBUG
+  u8 lockError;              /* True if a locking error has occurred */
+#endif
+};
+
+/*
+** Candidate values for Wal.exclusiveMode.
+*/
+#define WAL_NORMAL_MODE     0
+#define WAL_EXCLUSIVE_MODE  1     
+#define WAL_HEAPMEMORY_MODE 2
+
+/*
+** Each page of the wal-index mapping contains a hash-table made up of
+** an array of HASHTABLE_NSLOT elements of the following type.
+*/
+typedef u16 ht_slot;
+
+/*
+** This structure is used to implement an iterator that loops through
+** all frames in the WAL in database page order. Where two or more frames
+** correspond to the same database page, the iterator visits only the 
+** frame most recently written to the WAL (in other words, the frame with
+** the largest index).
+**
+** The internals of this structure are only accessed by:
+**
+**   walIteratorInit() - Create a new iterator,
+**   walIteratorNext() - Step an iterator,
+**   walIteratorFree() - Free an iterator.
+**
+** This functionality is used by the checkpoint code (see walCheckpoint()).
+*/
+struct WalIterator {
+  int iPrior;                     /* Last result returned from the iterator */
+  int nSegment;                   /* Number of entries in aSegment[] */
+  struct WalSegment {
+    int iNext;                    /* Next slot in aIndex[] not yet returned */
+    ht_slot *aIndex;              /* i0, i1, i2... such that aPgno[iN] ascend */
+    u32 *aPgno;                   /* Array of page numbers. */
+    int nEntry;                   /* Nr. of entries in aPgno[] and aIndex[] */
+    int iZero;                    /* Frame number associated with aPgno[0] */
+  } aSegment[1];                  /* One for every 32KB page in the wal-index */
+};
+
+/*
+** Define the parameters of the hash tables in the wal-index file. There
+** is a hash-table following every HASHTABLE_NPAGE page numbers in the
+** wal-index.
+**
+** Changing any of these constants will alter the wal-index format and
+** create incompatibilities.
+*/
+#define HASHTABLE_NPAGE      4096                 /* Must be power of 2 */
+#define HASHTABLE_HASH_1     383                  /* Should be prime */
+#define HASHTABLE_NSLOT      (HASHTABLE_NPAGE*2)  /* Must be a power of 2 */
+
+/* 
+** The block of page numbers associated with the first hash-table in a
+** wal-index is smaller than usual. This is so that there is a complete
+** hash-table on each aligned 32KB page of the wal-index.
+*/
+#define HASHTABLE_NPAGE_ONE  (HASHTABLE_NPAGE - (WALINDEX_HDR_SIZE/sizeof(u32)))
+
+/* The wal-index is divided into pages of WALINDEX_PGSZ bytes each. */
+#define WALINDEX_PGSZ   (                                         \
+    sizeof(ht_slot)*HASHTABLE_NSLOT + HASHTABLE_NPAGE*sizeof(u32) \
+)
+
+/*
+** Obtain a pointer to the iPage'th page of the wal-index. The wal-index
+** is broken into pages of WALINDEX_PGSZ bytes. Wal-index pages are
+** numbered from zero.
+**
+** If this call is successful, *ppPage is set to point to the wal-index
+** page and SQLITE_OK is returned. If an error (an OOM or VFS error) occurs,
+** then an SQLite error code is returned and *ppPage is set to 0.
+*/
+static int walIndexPage(Wal *pWal, int iPage, volatile u32 **ppPage){
+  int rc = SQLITE_OK;
+
+  /* Enlarge the pWal->apWiData[] array if required */
+  if( pWal->nWiData<=iPage ){
+    int nByte = sizeof(u32*)*(iPage+1);
+    volatile u32 **apNew;
+    apNew = (volatile u32 **)sqlite3_realloc((void *)pWal->apWiData, nByte);
+    if( !apNew ){
+      *ppPage = 0;
+      return SQLITE_NOMEM;
+    }
+    memset((void*)&apNew[pWal->nWiData], 0,
+           sizeof(u32*)*(iPage+1-pWal->nWiData));
+    pWal->apWiData = apNew;
+    pWal->nWiData = iPage+1;
+  }
+
+  /* Request a pointer to the required page from the VFS */
+  if( pWal->apWiData[iPage]==0 ){
+    if( pWal->exclusiveMode==WAL_HEAPMEMORY_MODE ){
+      pWal->apWiData[iPage] = (u32 volatile *)sqlite3MallocZero(WALINDEX_PGSZ);
+      if( !pWal->apWiData[iPage] ) rc = SQLITE_NOMEM;
+    }else{
+      rc = sqlite3OsShmMap(pWal->pDbFd, iPage, WALINDEX_PGSZ, 
+          pWal->writeLock, (void volatile **)&pWal->apWiData[iPage]
+      );
+    }
+  }
+
+  *ppPage = pWal->apWiData[iPage];
+  assert( iPage==0 || *ppPage || rc!=SQLITE_OK );
+  return rc;
+}
+
+/*
+** Return a pointer to the WalCkptInfo structure in the wal-index.
+*/
+static volatile WalCkptInfo *walCkptInfo(Wal *pWal){
+  assert( pWal->nWiData>0 && pWal->apWiData[0] );
+  return (volatile WalCkptInfo*)&(pWal->apWiData[0][sizeof(WalIndexHdr)/2]);
+}
+
+/*
+** Return a pointer to the WalIndexHdr structure in the wal-index.
+*/
+static volatile WalIndexHdr *walIndexHdr(Wal *pWal){
+  assert( pWal->nWiData>0 && pWal->apWiData[0] );
+  return (volatile WalIndexHdr*)pWal->apWiData[0];
+}
+
+/*
+** The argument to this macro must be of type u32. On a little-endian
+** architecture, it returns the u32 value that results from interpreting
+** the 4 bytes as a big-endian value. On a big-endian architecture, it
+** returns the value that would be produced by intepreting the 4 bytes
+** of the input value as a little-endian integer.
+*/
+#define BYTESWAP32(x) ( \
+    (((x)&0x000000FF)<<24) + (((x)&0x0000FF00)<<8)  \
+  + (((x)&0x00FF0000)>>8)  + (((x)&0xFF000000)>>24) \
+)
+
+/*
+** Generate or extend an 8 byte checksum based on the data in 
+** array aByte[] and the initial values of aIn[0] and aIn[1] (or
+** initial values of 0 and 0 if aIn==NULL).
+**
+** The checksum is written back into aOut[] before returning.
+**
+** nByte must be a positive multiple of 8.
+*/
+static void walChecksumBytes(
+  int nativeCksum, /* True for native byte-order, false for non-native */
+  u8 *a,           /* Content to be checksummed */
+  int nByte,       /* Bytes of content in a[].  Must be a multiple of 8. */
+  const u32 *aIn,  /* Initial checksum value input */
+  u32 *aOut        /* OUT: Final checksum value output */
+){
+  u32 s1, s2;
+  u32 *aData = (u32 *)a;
+  u32 *aEnd = (u32 *)&a[nByte];
+
+  if( aIn ){
+    s1 = aIn[0];
+    s2 = aIn[1];
+  }else{
+    s1 = s2 = 0;
+  }
+
+  assert( nByte>=8 );
+  assert( (nByte&0x00000007)==0 );
+
+  if( nativeCksum ){
+    do {
+      s1 += *aData++ + s2;
+      s2 += *aData++ + s1;
+    }while( aData<aEnd );
+  }else{
+    do {
+      s1 += BYTESWAP32(aData[0]) + s2;
+      s2 += BYTESWAP32(aData[1]) + s1;
+      aData += 2;
+    }while( aData<aEnd );
+  }
+
+  aOut[0] = s1;
+  aOut[1] = s2;
+}
+
+static void walShmBarrier(Wal *pWal){
+  if( pWal->exclusiveMode!=WAL_HEAPMEMORY_MODE ){
+    sqlite3OsShmBarrier(pWal->pDbFd);
+  }
+}
+
+/*
+** Write the header information in pWal->hdr into the wal-index.
+**
+** The checksum on pWal->hdr is updated before it is written.
+*/
+static void walIndexWriteHdr(Wal *pWal){
+  volatile WalIndexHdr *aHdr = walIndexHdr(pWal);
+  const int nCksum = offsetof(WalIndexHdr, aCksum);
+
+  assert( pWal->writeLock );
+  pWal->hdr.isInit = 1;
+  pWal->hdr.iVersion = WALINDEX_MAX_VERSION;
+  walChecksumBytes(1, (u8*)&pWal->hdr, nCksum, 0, pWal->hdr.aCksum);
+  memcpy((void *)&aHdr[1], (void *)&pWal->hdr, sizeof(WalIndexHdr));
+  walShmBarrier(pWal);
+  memcpy((void *)&aHdr[0], (void *)&pWal->hdr, sizeof(WalIndexHdr));
+}
+
+/*
+** This function encodes a single frame header and writes it to a buffer
+** supplied by the caller. A frame-header is made up of a series of 
+** 4-byte big-endian integers, as follows:
+**
+**     0: Page number.
+**     4: For commit records, the size of the database image in pages 
+**        after the commit. For all other records, zero.
+**     8: Salt-1 (copied from the wal-header)
+**    12: Salt-2 (copied from the wal-header)
+**    16: Checksum-1.
+**    20: Checksum-2.
+*/
+static void walEncodeFrame(
+  Wal *pWal,                      /* The write-ahead log */
+  u32 iPage,                      /* Database page number for frame */
+  u32 nTruncate,                  /* New db size (or 0 for non-commit frames) */
+  u8 *aData,                      /* Pointer to page data */
+  u8 *aFrame                      /* OUT: Write encoded frame here */
+){
+  int nativeCksum;                /* True for native byte-order checksums */
+  u32 *aCksum = pWal->hdr.aFrameCksum;
+  assert( WAL_FRAME_HDRSIZE==24 );
+  sqlite3Put4byte(&aFrame[0], iPage);
+  sqlite3Put4byte(&aFrame[4], nTruncate);
+  memcpy(&aFrame[8], pWal->hdr.aSalt, 8);
+
+  nativeCksum = (pWal->hdr.bigEndCksum==SQLITE_BIGENDIAN);
+  walChecksumBytes(nativeCksum, aFrame, 8, aCksum, aCksum);
+  walChecksumBytes(nativeCksum, aData, pWal->szPage, aCksum, aCksum);
+
+  sqlite3Put4byte(&aFrame[16], aCksum[0]);
+  sqlite3Put4byte(&aFrame[20], aCksum[1]);
+}
+
+/*
+** Check to see if the frame with header in aFrame[] and content
+** in aData[] is valid.  If it is a valid frame, fill *piPage and
+** *pnTruncate and return true.  Return if the frame is not valid.
+*/
+static int walDecodeFrame(
+  Wal *pWal,                      /* The write-ahead log */
+  u32 *piPage,                    /* OUT: Database page number for frame */
+  u32 *pnTruncate,                /* OUT: New db size (or 0 if not commit) */
+  u8 *aData,                      /* Pointer to page data (for checksum) */
+  u8 *aFrame                      /* Frame data */
+){
+  int nativeCksum;                /* True for native byte-order checksums */
+  u32 *aCksum = pWal->hdr.aFrameCksum;
+  u32 pgno;                       /* Page number of the frame */
+  assert( WAL_FRAME_HDRSIZE==24 );
+
+  /* A frame is only valid if the salt values in the frame-header
+  ** match the salt values in the wal-header. 
+  */
+  if( memcmp(&pWal->hdr.aSalt, &aFrame[8], 8)!=0 ){
+    return 0;
+  }
+
+  /* A frame is only valid if the page number is creater than zero.
+  */
+  pgno = sqlite3Get4byte(&aFrame[0]);
+  if( pgno==0 ){
+    return 0;
+  }
+
+  /* A frame is only valid if a checksum of the WAL header,
+  ** all prior frams, the first 16 bytes of this frame-header, 
+  ** and the frame-data matches the checksum in the last 8 
+  ** bytes of this frame-header.
+  */
+  nativeCksum = (pWal->hdr.bigEndCksum==SQLITE_BIGENDIAN);
+  walChecksumBytes(nativeCksum, aFrame, 8, aCksum, aCksum);
+  walChecksumBytes(nativeCksum, aData, pWal->szPage, aCksum, aCksum);
+  if( aCksum[0]!=sqlite3Get4byte(&aFrame[16]) 
+   || aCksum[1]!=sqlite3Get4byte(&aFrame[20]) 
+  ){
+    /* Checksum failed. */
+    return 0;
+  }
+
+  /* If we reach this point, the frame is valid.  Return the page number
+  ** and the new database size.
+  */
+  *piPage = pgno;
+  *pnTruncate = sqlite3Get4byte(&aFrame[4]);
+  return 1;
+}
+
+
+#if defined(SQLITE_TEST) && defined(SQLITE_DEBUG)
+/*
+** Names of locks.  This routine is used to provide debugging output and is not
+** a part of an ordinary build.
+*/
+static const char *walLockName(int lockIdx){
+  if( lockIdx==WAL_WRITE_LOCK ){
+    return "WRITE-LOCK";
+  }else if( lockIdx==WAL_CKPT_LOCK ){
+    return "CKPT-LOCK";
+  }else if( lockIdx==WAL_RECOVER_LOCK ){
+    return "RECOVER-LOCK";
+  }else{
+    static char zName[15];
+    sqlite3_snprintf(sizeof(zName), zName, "READ-LOCK[%d]",
+                     lockIdx-WAL_READ_LOCK(0));
+    return zName;
+  }
+}
+#endif /*defined(SQLITE_TEST) || defined(SQLITE_DEBUG) */
+    
+
+/*
+** Set or release locks on the WAL.  Locks are either shared or exclusive.
+** A lock cannot be moved directly between shared and exclusive - it must go
+** through the unlocked state first.
+**
+** In locking_mode=EXCLUSIVE, all of these routines become no-ops.
+*/
+static int walLockShared(Wal *pWal, int lockIdx){
+  int rc;
+  if( pWal->exclusiveMode ) return SQLITE_OK;
+  rc = sqlite3OsShmLock(pWal->pDbFd, lockIdx, 1,
+                        SQLITE_SHM_LOCK | SQLITE_SHM_SHARED);
+  WALTRACE(("WAL%p: acquire SHARED-%s %s\n", pWal,
+            walLockName(lockIdx), rc ? "failed" : "ok"));
+  VVA_ONLY( pWal->lockError = (u8)(rc!=SQLITE_OK && rc!=SQLITE_BUSY); )
+  return rc;
+}
+static void walUnlockShared(Wal *pWal, int lockIdx){
+  if( pWal->exclusiveMode ) return;
+  (void)sqlite3OsShmLock(pWal->pDbFd, lockIdx, 1,
+                         SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED);
+  WALTRACE(("WAL%p: release SHARED-%s\n", pWal, walLockName(lockIdx)));
+}
+static int walLockExclusive(Wal *pWal, int lockIdx, int n){
+  int rc;
+  if( pWal->exclusiveMode ) return SQLITE_OK;
+  rc = sqlite3OsShmLock(pWal->pDbFd, lockIdx, n,
+                        SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE);
+  WALTRACE(("WAL%p: acquire EXCLUSIVE-%s cnt=%d %s\n", pWal,
+            walLockName(lockIdx), n, rc ? "failed" : "ok"));
+  VVA_ONLY( pWal->lockError = (u8)(rc!=SQLITE_OK && rc!=SQLITE_BUSY); )
+  return rc;
+}
+static void walUnlockExclusive(Wal *pWal, int lockIdx, int n){
+  if( pWal->exclusiveMode ) return;
+  (void)sqlite3OsShmLock(pWal->pDbFd, lockIdx, n,
+                         SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE);
+  WALTRACE(("WAL%p: release EXCLUSIVE-%s cnt=%d\n", pWal,
+             walLockName(lockIdx), n));
+}
+
+/*
+** Compute a hash on a page number.  The resulting hash value must land
+** between 0 and (HASHTABLE_NSLOT-1).  The walHashNext() function advances
+** the hash to the next value in the event of a collision.
+*/
+static int walHash(u32 iPage){
+  assert( iPage>0 );
+  assert( (HASHTABLE_NSLOT & (HASHTABLE_NSLOT-1))==0 );
+  return (iPage*HASHTABLE_HASH_1) & (HASHTABLE_NSLOT-1);
+}
+static int walNextHash(int iPriorHash){
+  return (iPriorHash+1)&(HASHTABLE_NSLOT-1);
+}
+
+/* 
+** Return pointers to the hash table and page number array stored on
+** page iHash of the wal-index. The wal-index is broken into 32KB pages
+** numbered starting from 0.
+**
+** Set output variable *paHash to point to the start of the hash table
+** in the wal-index file. Set *piZero to one less than the frame 
+** number of the first frame indexed by this hash table. If a
+** slot in the hash table is set to N, it refers to frame number 
+** (*piZero+N) in the log.
+**
+** Finally, set *paPgno so that *paPgno[1] is the page number of the
+** first frame indexed by the hash table, frame (*piZero+1).
+*/
+static int walHashGet(
+  Wal *pWal,                      /* WAL handle */
+  int iHash,                      /* Find the iHash'th table */
+  volatile ht_slot **paHash,      /* OUT: Pointer to hash index */
+  volatile u32 **paPgno,          /* OUT: Pointer to page number array */
+  u32 *piZero                     /* OUT: Frame associated with *paPgno[0] */
+){
+  int rc;                         /* Return code */
+  volatile u32 *aPgno;
+
+  rc = walIndexPage(pWal, iHash, &aPgno);
+  assert( rc==SQLITE_OK || iHash>0 );
+
+  if( rc==SQLITE_OK ){
+    u32 iZero;
+    volatile ht_slot *aHash;
+
+    aHash = (volatile ht_slot *)&aPgno[HASHTABLE_NPAGE];
+    if( iHash==0 ){
+      aPgno = &aPgno[WALINDEX_HDR_SIZE/sizeof(u32)];
+      iZero = 0;
+    }else{
+      iZero = HASHTABLE_NPAGE_ONE + (iHash-1)*HASHTABLE_NPAGE;
+    }
+  
+    *paPgno = &aPgno[-1];
+    *paHash = aHash;
+    *piZero = iZero;
+  }
+  return rc;
+}
+
+/*
+** Return the number of the wal-index page that contains the hash-table
+** and page-number array that contain entries corresponding to WAL frame
+** iFrame. The wal-index is broken up into 32KB pages. Wal-index pages 
+** are numbered starting from 0.
+*/
+static int walFramePage(u32 iFrame){
+  int iHash = (iFrame+HASHTABLE_NPAGE-HASHTABLE_NPAGE_ONE-1) / HASHTABLE_NPAGE;
+  assert( (iHash==0 || iFrame>HASHTABLE_NPAGE_ONE)
+       && (iHash>=1 || iFrame<=HASHTABLE_NPAGE_ONE)
+       && (iHash<=1 || iFrame>(HASHTABLE_NPAGE_ONE+HASHTABLE_NPAGE))
+       && (iHash>=2 || iFrame<=HASHTABLE_NPAGE_ONE+HASHTABLE_NPAGE)
+       && (iHash<=2 || iFrame>(HASHTABLE_NPAGE_ONE+2*HASHTABLE_NPAGE))
+  );
+  return iHash;
+}
+
+/*
+** Return the page number associated with frame iFrame in this WAL.
+*/
+static u32 walFramePgno(Wal *pWal, u32 iFrame){
+  int iHash = walFramePage(iFrame);
+  if( iHash==0 ){
+    return pWal->apWiData[0][WALINDEX_HDR_SIZE/sizeof(u32) + iFrame - 1];
+  }
+  return pWal->apWiData[iHash][(iFrame-1-HASHTABLE_NPAGE_ONE)%HASHTABLE_NPAGE];
+}
+
+/*
+** Remove entries from the hash table that point to WAL slots greater
+** than pWal->hdr.mxFrame.
+**
+** This function is called whenever pWal->hdr.mxFrame is decreased due
+** to a rollback or savepoint.
+**
+** At most only the hash table containing pWal->hdr.mxFrame needs to be
+** updated.  Any later hash tables will be automatically cleared when
+** pWal->hdr.mxFrame advances to the point where those hash tables are
+** actually needed.
+*/
+static void walCleanupHash(Wal *pWal){
+  volatile ht_slot *aHash = 0;    /* Pointer to hash table to clear */
+  volatile u32 *aPgno = 0;        /* Page number array for hash table */
+  u32 iZero = 0;                  /* frame == (aHash[x]+iZero) */
+  int iLimit = 0;                 /* Zero values greater than this */
+  int nByte;                      /* Number of bytes to zero in aPgno[] */
+  int i;                          /* Used to iterate through aHash[] */
+
+  assert( pWal->writeLock );
+  testcase( pWal->hdr.mxFrame==HASHTABLE_NPAGE_ONE-1 );
+  testcase( pWal->hdr.mxFrame==HASHTABLE_NPAGE_ONE );
+  testcase( pWal->hdr.mxFrame==HASHTABLE_NPAGE_ONE+1 );
+
+  if( pWal->hdr.mxFrame==0 ) return;
+
+  /* Obtain pointers to the hash-table and page-number array containing 
+  ** the entry that corresponds to frame pWal->hdr.mxFrame. It is guaranteed
+  ** that the page said hash-table and array reside on is already mapped.
+  */
+  assert( pWal->nWiData>walFramePage(pWal->hdr.mxFrame) );
+  assert( pWal->apWiData[walFramePage(pWal->hdr.mxFrame)] );
+  walHashGet(pWal, walFramePage(pWal->hdr.mxFrame), &aHash, &aPgno, &iZero);
+
+  /* Zero all hash-table entries that correspond to frame numbers greater
+  ** than pWal->hdr.mxFrame.
+  */
+  iLimit = pWal->hdr.mxFrame - iZero;
+  assert( iLimit>0 );
+  for(i=0; i<HASHTABLE_NSLOT; i++){
+    if( aHash[i]>iLimit ){
+      aHash[i] = 0;
+    }
+  }
+  
+  /* Zero the entries in the aPgno array that correspond to frames with
+  ** frame numbers greater than pWal->hdr.mxFrame. 
+  */
+  nByte = (int)((char *)aHash - (char *)&aPgno[iLimit+1]);
+  memset((void *)&aPgno[iLimit+1], 0, nByte);
+
+#ifdef SQLITE_ENABLE_EXPENSIVE_ASSERT
+  /* Verify that the every entry in the mapping region is still reachable
+  ** via the hash table even after the cleanup.
+  */
+  if( iLimit ){
+    int i;           /* Loop counter */
+    int iKey;        /* Hash key */
+    for(i=1; i<=iLimit; i++){
+      for(iKey=walHash(aPgno[i]); aHash[iKey]; iKey=walNextHash(iKey)){
+        if( aHash[iKey]==i ) break;
+      }
+      assert( aHash[iKey]==i );
+    }
+  }
+#endif /* SQLITE_ENABLE_EXPENSIVE_ASSERT */
+}
+
+
+/*
+** Set an entry in the wal-index that will map database page number
+** pPage into WAL frame iFrame.
+*/
+static int walIndexAppend(Wal *pWal, u32 iFrame, u32 iPage){
+  int rc;                         /* Return code */
+  u32 iZero = 0;                  /* One less than frame number of aPgno[1] */
+  volatile u32 *aPgno = 0;        /* Page number array */
+  volatile ht_slot *aHash = 0;    /* Hash table */
+
+  rc = walHashGet(pWal, walFramePage(iFrame), &aHash, &aPgno, &iZero);
+
+  /* Assuming the wal-index file was successfully mapped, populate the
+  ** page number array and hash table entry.
+  */
+  if( rc==SQLITE_OK ){
+    int iKey;                     /* Hash table key */
+    int idx;                      /* Value to write to hash-table slot */
+    int nCollide;                 /* Number of hash collisions */
+
+    idx = iFrame - iZero;
+    assert( idx <= HASHTABLE_NSLOT/2 + 1 );
+    
+    /* If this is the first entry to be added to this hash-table, zero the
+    ** entire hash table and aPgno[] array before proceding. 
+    */
+    if( idx==1 ){
+      int nByte = (int)((u8 *)&aHash[HASHTABLE_NSLOT] - (u8 *)&aPgno[1]);
+      memset((void*)&aPgno[1], 0, nByte);
+    }
+
+    /* If the entry in aPgno[] is already set, then the previous writer
+    ** must have exited unexpectedly in the middle of a transaction (after
+    ** writing one or more dirty pages to the WAL to free up memory). 
+    ** Remove the remnants of that writers uncommitted transaction from 
+    ** the hash-table before writing any new entries.
+    */
+    if( aPgno[idx] ){
+      walCleanupHash(pWal);
+      assert( !aPgno[idx] );
+    }
+
+    /* Write the aPgno[] array entry and the hash-table slot. */
+    nCollide = idx;
+    for(iKey=walHash(iPage); aHash[iKey]; iKey=walNextHash(iKey)){
+      if( (nCollide--)==0 ) return SQLITE_CORRUPT_BKPT;
+    }
+    aPgno[idx] = iPage;
+    aHash[iKey] = (ht_slot)idx;
+
+#ifdef SQLITE_ENABLE_EXPENSIVE_ASSERT
+    /* Verify that the number of entries in the hash table exactly equals
+    ** the number of entries in the mapping region.
+    */
+    {
+      int i;           /* Loop counter */
+      int nEntry = 0;  /* Number of entries in the hash table */
+      for(i=0; i<HASHTABLE_NSLOT; i++){ if( aHash[i] ) nEntry++; }
+      assert( nEntry==idx );
+    }
+
+    /* Verify that the every entry in the mapping region is reachable
+    ** via the hash table.  This turns out to be a really, really expensive
+    ** thing to check, so only do this occasionally - not on every
+    ** iteration.
+    */
+    if( (idx&0x3ff)==0 ){
+      int i;           /* Loop counter */
+      for(i=1; i<=idx; i++){
+        for(iKey=walHash(aPgno[i]); aHash[iKey]; iKey=walNextHash(iKey)){
+          if( aHash[iKey]==i ) break;
+        }
+        assert( aHash[iKey]==i );
+      }
+    }
+#endif /* SQLITE_ENABLE_EXPENSIVE_ASSERT */
+  }
+
+
+  return rc;
+}
+
+
+/*
+** Recover the wal-index by reading the write-ahead log file. 
+**
+** This routine first tries to establish an exclusive lock on the
+** wal-index to prevent other threads/processes from doing anything
+** with the WAL or wal-index while recovery is running.  The
+** WAL_RECOVER_LOCK is also held so that other threads will know
+** that this thread is running recovery.  If unable to establish
+** the necessary locks, this routine returns SQLITE_BUSY.
+*/
+static int walIndexRecover(Wal *pWal){
+  int rc;                         /* Return Code */
+  i64 nSize;                      /* Size of log file */
+  u32 aFrameCksum[2] = {0, 0};
+  int iLock;                      /* Lock offset to lock for checkpoint */
+  int nLock;                      /* Number of locks to hold */
+
+  /* Obtain an exclusive lock on all byte in the locking range not already
+  ** locked by the caller. The caller is guaranteed to have locked the
+  ** WAL_WRITE_LOCK byte, and may have also locked the WAL_CKPT_LOCK byte.
+  ** If successful, the same bytes that are locked here are unlocked before
+  ** this function returns.
+  */
+  assert( pWal->ckptLock==1 || pWal->ckptLock==0 );
+  assert( WAL_ALL_BUT_WRITE==WAL_WRITE_LOCK+1 );
+  assert( WAL_CKPT_LOCK==WAL_ALL_BUT_WRITE );
+  assert( pWal->writeLock );
+  iLock = WAL_ALL_BUT_WRITE + pWal->ckptLock;
+  nLock = SQLITE_SHM_NLOCK - iLock;
+  rc = walLockExclusive(pWal, iLock, nLock);
+  if( rc ){
+    return rc;
+  }
+  WALTRACE(("WAL%p: recovery begin...\n", pWal));
+
+  memset(&pWal->hdr, 0, sizeof(WalIndexHdr));
+
+  rc = sqlite3OsFileSize(pWal->pWalFd, &nSize);
+  if( rc!=SQLITE_OK ){
+    goto recovery_error;
+  }
+
+  if( nSize>WAL_HDRSIZE ){
+    u8 aBuf[WAL_HDRSIZE];         /* Buffer to load WAL header into */
+    u8 *aFrame = 0;               /* Malloc'd buffer to load entire frame */
+    int szFrame;                  /* Number of bytes in buffer aFrame[] */
+    u8 *aData;                    /* Pointer to data part of aFrame buffer */
+    int iFrame;                   /* Index of last frame read */
+    i64 iOffset;                  /* Next offset to read from log file */
+    int szPage;                   /* Page size according to the log */
+    u32 magic;                    /* Magic value read from WAL header */
+    u32 version;                  /* Magic value read from WAL header */
+
+    /* Read in the WAL header. */
+    rc = sqlite3OsRead(pWal->pWalFd, aBuf, WAL_HDRSIZE, 0);
+    if( rc!=SQLITE_OK ){
+      goto recovery_error;
+    }
+
+    /* If the database page size is not a power of two, or is greater than
+    ** SQLITE_MAX_PAGE_SIZE, conclude that the WAL file contains no valid 
+    ** data. Similarly, if the 'magic' value is invalid, ignore the whole
+    ** WAL file.
+    */
+    magic = sqlite3Get4byte(&aBuf[0]);
+    szPage = sqlite3Get4byte(&aBuf[8]);
+    if( (magic&0xFFFFFFFE)!=WAL_MAGIC 
+     || szPage&(szPage-1) 
+     || szPage>SQLITE_MAX_PAGE_SIZE 
+     || szPage<512 
+    ){
+      goto finished;
+    }
+    pWal->hdr.bigEndCksum = (u8)(magic&0x00000001);
+    pWal->szPage = szPage;
+    pWal->nCkpt = sqlite3Get4byte(&aBuf[12]);
+    memcpy(&pWal->hdr.aSalt, &aBuf[16], 8);
+
+    /* Verify that the WAL header checksum is correct */
+    walChecksumBytes(pWal->hdr.bigEndCksum==SQLITE_BIGENDIAN, 
+        aBuf, WAL_HDRSIZE-2*4, 0, pWal->hdr.aFrameCksum
+    );
+    if( pWal->hdr.aFrameCksum[0]!=sqlite3Get4byte(&aBuf[24])
+     || pWal->hdr.aFrameCksum[1]!=sqlite3Get4byte(&aBuf[28])
+    ){
+      goto finished;
+    }
+
+    /* Verify that the version number on the WAL format is one that
+    ** are able to understand */
+    version = sqlite3Get4byte(&aBuf[4]);
+    if( version!=WAL_MAX_VERSION ){
+      rc = SQLITE_CANTOPEN_BKPT;
+      goto finished;
+    }
+
+    /* Malloc a buffer to read frames into. */
+    szFrame = szPage + WAL_FRAME_HDRSIZE;
+    aFrame = (u8 *)sqlite3_malloc(szFrame);
+    if( !aFrame ){
+      rc = SQLITE_NOMEM;
+      goto recovery_error;
+    }
+    aData = &aFrame[WAL_FRAME_HDRSIZE];
+
+    /* Read all frames from the log file. */
+    iFrame = 0;
+    for(iOffset=WAL_HDRSIZE; (iOffset+szFrame)<=nSize; iOffset+=szFrame){
+      u32 pgno;                   /* Database page number for frame */
+      u32 nTruncate;              /* dbsize field from frame header */
+      int isValid;                /* True if this frame is valid */
+
+      /* Read and decode the next log frame. */
+      rc = sqlite3OsRead(pWal->pWalFd, aFrame, szFrame, iOffset);
+      if( rc!=SQLITE_OK ) break;
+      isValid = walDecodeFrame(pWal, &pgno, &nTruncate, aData, aFrame);
+      if( !isValid ) break;
+      rc = walIndexAppend(pWal, ++iFrame, pgno);
+      if( rc!=SQLITE_OK ) break;
+
+      /* If nTruncate is non-zero, this is a commit record. */
+      if( nTruncate ){
+        pWal->hdr.mxFrame = iFrame;
+        pWal->hdr.nPage = nTruncate;
+        pWal->hdr.szPage = (u16)((szPage&0xff00) | (szPage>>16));
+        testcase( szPage<=32768 );
+        testcase( szPage>=65536 );
+        aFrameCksum[0] = pWal->hdr.aFrameCksum[0];
+        aFrameCksum[1] = pWal->hdr.aFrameCksum[1];
+      }
+    }
+
+    sqlite3_free(aFrame);
+  }
+
+finished:
+  if( rc==SQLITE_OK ){
+    volatile WalCkptInfo *pInfo;
+    int i;
+    pWal->hdr.aFrameCksum[0] = aFrameCksum[0];
+    pWal->hdr.aFrameCksum[1] = aFrameCksum[1];
+    walIndexWriteHdr(pWal);
+
+    /* Reset the checkpoint-header. This is safe because this thread is 
+    ** currently holding locks that exclude all other readers, writers and
+    ** checkpointers.
+    */
+    pInfo = walCkptInfo(pWal);
+    pInfo->nBackfill = 0;
+    pInfo->aReadMark[0] = 0;
+    for(i=1; i<WAL_NREADER; i++) pInfo->aReadMark[i] = READMARK_NOT_USED;
+
+    /* If more than one frame was recovered from the log file, report an
+    ** event via sqlite3_log(). This is to help with identifying performance
+    ** problems caused by applications routinely shutting down without
+    ** checkpointing the log file.
+    */
+    if( pWal->hdr.nPage ){
+      sqlite3_log(SQLITE_OK, "Recovered %d frames from WAL file %s",
+          pWal->hdr.nPage, pWal->zWalName
+      );
+    }
+  }
+
+recovery_error:
+  WALTRACE(("WAL%p: recovery %s\n", pWal, rc ? "failed" : "ok"));
+  walUnlockExclusive(pWal, iLock, nLock);
+  return rc;
+}
+
+/*
+** Close an open wal-index.
+*/
+static void walIndexClose(Wal *pWal, int isDelete){
+  if( pWal->exclusiveMode==WAL_HEAPMEMORY_MODE ){
+    int i;
+    for(i=0; i<pWal->nWiData; i++){
+      sqlite3_free((void *)pWal->apWiData[i]);
+      pWal->apWiData[i] = 0;
+    }
+  }else{
+    sqlite3OsShmUnmap(pWal->pDbFd, isDelete);
+  }
+}
+
+/* 
+** Open a connection to the WAL file zWalName. The database file must 
+** already be opened on connection pDbFd. The buffer that zWalName points
+** to must remain valid for the lifetime of the returned Wal* handle.
+**
+** A SHARED lock should be held on the database file when this function
+** is called. The purpose of this SHARED lock is to prevent any other
+** client from unlinking the WAL or wal-index file. If another process
+** were to do this just after this client opened one of these files, the
+** system would be badly broken.
+**
+** If the log file is successfully opened, SQLITE_OK is returned and 
+** *ppWal is set to point to a new WAL handle. If an error occurs,
+** an SQLite error code is returned and *ppWal is left unmodified.
+*/
+SQLITE_PRIVATE int sqlite3WalOpen(
+  sqlite3_vfs *pVfs,              /* vfs module to open wal and wal-index */
+  sqlite3_file *pDbFd,            /* The open database file */
+  const char *zWalName,           /* Name of the WAL file */
+  int bNoShm,                     /* True to run in heap-memory mode */
+  Wal **ppWal                     /* OUT: Allocated Wal handle */
+){
+  int rc;                         /* Return Code */
+  Wal *pRet;                      /* Object to allocate and return */
+  int flags;                      /* Flags passed to OsOpen() */
+
+  assert( zWalName && zWalName[0] );
+  assert( pDbFd );
+
+  /* In the amalgamation, the os_unix.c and os_win.c source files come before
+  ** this source file.  Verify that the #defines of the locking byte offsets
+  ** in os_unix.c and os_win.c agree with the WALINDEX_LOCK_OFFSET value.
+  */
+#ifdef WIN_SHM_BASE
+  assert( WIN_SHM_BASE==WALINDEX_LOCK_OFFSET );
+#endif
+#ifdef UNIX_SHM_BASE
+  assert( UNIX_SHM_BASE==WALINDEX_LOCK_OFFSET );
+#endif
+
+
+  /* Allocate an instance of struct Wal to return. */
+  *ppWal = 0;
+  pRet = (Wal*)sqlite3MallocZero(sizeof(Wal) + pVfs->szOsFile);
+  if( !pRet ){
+    return SQLITE_NOMEM;
+  }
+
+  pRet->pVfs = pVfs;
+  pRet->pWalFd = (sqlite3_file *)&pRet[1];
+  pRet->pDbFd = pDbFd;
+  pRet->readLock = -1;
+  pRet->zWalName = zWalName;
+  pRet->exclusiveMode = (bNoShm ? WAL_HEAPMEMORY_MODE: WAL_NORMAL_MODE);
+
+  /* Open file handle on the write-ahead log file. */
+  flags = (SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE|SQLITE_OPEN_WAL);
+  rc = sqlite3OsOpen(pVfs, zWalName, pRet->pWalFd, flags, &flags);
+  if( rc==SQLITE_OK && flags&SQLITE_OPEN_READONLY ){
+    pRet->readOnly = 1;
+  }
+
+  if( rc!=SQLITE_OK ){
+    walIndexClose(pRet, 0);
+    sqlite3OsClose(pRet->pWalFd);
+    sqlite3_free(pRet);
+  }else{
+    *ppWal = pRet;
+    WALTRACE(("WAL%d: opened\n", pRet));
+  }
+  return rc;
+}
+
+/*
+** Find the smallest page number out of all pages held in the WAL that
+** has not been returned by any prior invocation of this method on the
+** same WalIterator object.   Write into *piFrame the frame index where
+** that page was last written into the WAL.  Write into *piPage the page
+** number.
+**
+** Return 0 on success.  If there are no pages in the WAL with a page
+** number larger than *piPage, then return 1.
+*/
+static int walIteratorNext(
+  WalIterator *p,               /* Iterator */
+  u32 *piPage,                  /* OUT: The page number of the next page */
+  u32 *piFrame                  /* OUT: Wal frame index of next page */
+){
+  u32 iMin;                     /* Result pgno must be greater than iMin */
+  u32 iRet = 0xFFFFFFFF;        /* 0xffffffff is never a valid page number */
+  int i;                        /* For looping through segments */
+
+  iMin = p->iPrior;
+  assert( iMin<0xffffffff );
+  for(i=p->nSegment-1; i>=0; i--){
+    struct WalSegment *pSegment = &p->aSegment[i];
+    while( pSegment->iNext<pSegment->nEntry ){
+      u32 iPg = pSegment->aPgno[pSegment->aIndex[pSegment->iNext]];
+      if( iPg>iMin ){
+        if( iPg<iRet ){
+          iRet = iPg;
+          *piFrame = pSegment->iZero + pSegment->aIndex[pSegment->iNext];
+        }
+        break;
+      }
+      pSegment->iNext++;
+    }
+  }
+
+  *piPage = p->iPrior = iRet;
+  return (iRet==0xFFFFFFFF);
+}
+
+/*
+** This function merges two sorted lists into a single sorted list.
+**
+** aLeft[] and aRight[] are arrays of indices.  The sort key is
+** aContent[aLeft[]] and aContent[aRight[]].  Upon entry, the following
+** is guaranteed for all J<K:
+**
+**        aContent[aLeft[J]] < aContent[aLeft[K]]
+**        aContent[aRight[J]] < aContent[aRight[K]]
+**
+** This routine overwrites aRight[] with a new (probably longer) sequence
+** of indices such that the aRight[] contains every index that appears in
+** either aLeft[] or the old aRight[] and such that the second condition
+** above is still met.
+**
+** The aContent[aLeft[X]] values will be unique for all X.  And the
+** aContent[aRight[X]] values will be unique too.  But there might be
+** one or more combinations of X and Y such that
+**
+**      aLeft[X]!=aRight[Y]  &&  aContent[aLeft[X]] == aContent[aRight[Y]]
+**
+** When that happens, omit the aLeft[X] and use the aRight[Y] index.
+*/
+static void walMerge(
+  const u32 *aContent,            /* Pages in wal - keys for the sort */
+  ht_slot *aLeft,                 /* IN: Left hand input list */
+  int nLeft,                      /* IN: Elements in array *paLeft */
+  ht_slot **paRight,              /* IN/OUT: Right hand input list */
+  int *pnRight,                   /* IN/OUT: Elements in *paRight */
+  ht_slot *aTmp                   /* Temporary buffer */
+){
+  int iLeft = 0;                  /* Current index in aLeft */
+  int iRight = 0;                 /* Current index in aRight */
+  int iOut = 0;                   /* Current index in output buffer */
+  int nRight = *pnRight;
+  ht_slot *aRight = *paRight;
+
+  assert( nLeft>0 && nRight>0 );
+  while( iRight<nRight || iLeft<nLeft ){
+    ht_slot logpage;
+    Pgno dbpage;
+
+    if( (iLeft<nLeft) 
+     && (iRight>=nRight || aContent[aLeft[iLeft]]<aContent[aRight[iRight]])
+    ){
+      logpage = aLeft[iLeft++];
+    }else{
+      logpage = aRight[iRight++];
+    }
+    dbpage = aContent[logpage];
+
+    aTmp[iOut++] = logpage;
+    if( iLeft<nLeft && aContent[aLeft[iLeft]]==dbpage ) iLeft++;
+
+    assert( iLeft>=nLeft || aContent[aLeft[iLeft]]>dbpage );
+    assert( iRight>=nRight || aContent[aRight[iRight]]>dbpage );
+  }
+
+  *paRight = aLeft;
+  *pnRight = iOut;
+  memcpy(aLeft, aTmp, sizeof(aTmp[0])*iOut);
+}
+
+/*
+** Sort the elements in list aList using aContent[] as the sort key.
+** Remove elements with duplicate keys, preferring to keep the
+** larger aList[] values.
+**
+** The aList[] entries are indices into aContent[].  The values in
+** aList[] are to be sorted so that for all J<K:
+**
+**      aContent[aList[J]] < aContent[aList[K]]
+**
+** For any X and Y such that
+**
+**      aContent[aList[X]] == aContent[aList[Y]]
+**
+** Keep the larger of the two values aList[X] and aList[Y] and discard
+** the smaller.
+*/
+static void walMergesort(
+  const u32 *aContent,            /* Pages in wal */
+  ht_slot *aBuffer,               /* Buffer of at least *pnList items to use */
+  ht_slot *aList,                 /* IN/OUT: List to sort */
+  int *pnList                     /* IN/OUT: Number of elements in aList[] */
+){
+  struct Sublist {
+    int nList;                    /* Number of elements in aList */
+    ht_slot *aList;               /* Pointer to sub-list content */
+  };
+
+  const int nList = *pnList;      /* Size of input list */
+  int nMerge = 0;                 /* Number of elements in list aMerge */
+  ht_slot *aMerge = 0;            /* List to be merged */
+  int iList;                      /* Index into input list */
+  int iSub = 0;                   /* Index into aSub array */
+  struct Sublist aSub[13];        /* Array of sub-lists */
+
+  memset(aSub, 0, sizeof(aSub));
+  assert( nList<=HASHTABLE_NPAGE && nList>0 );
+  assert( HASHTABLE_NPAGE==(1<<(ArraySize(aSub)-1)) );
+
+  for(iList=0; iList<nList; iList++){
+    nMerge = 1;
+    aMerge = &aList[iList];
+    for(iSub=0; iList & (1<<iSub); iSub++){
+      struct Sublist *p = &aSub[iSub];
+      assert( p->aList && p->nList<=(1<<iSub) );
+      assert( p->aList==&aList[iList&~((2<<iSub)-1)] );
+      walMerge(aContent, p->aList, p->nList, &aMerge, &nMerge, aBuffer);
+    }
+    aSub[iSub].aList = aMerge;
+    aSub[iSub].nList = nMerge;
+  }
+
+  for(iSub++; iSub<ArraySize(aSub); iSub++){
+    if( nList & (1<<iSub) ){
+      struct Sublist *p = &aSub[iSub];
+      assert( p->nList<=(1<<iSub) );
+      assert( p->aList==&aList[nList&~((2<<iSub)-1)] );
+      walMerge(aContent, p->aList, p->nList, &aMerge, &nMerge, aBuffer);
+    }
+  }
+  assert( aMerge==aList );
+  *pnList = nMerge;
+
+#ifdef SQLITE_DEBUG
+  {
+    int i;
+    for(i=1; i<*pnList; i++){
+      assert( aContent[aList[i]] > aContent[aList[i-1]] );
+    }
+  }
+#endif
+}
+
+/* 
+** Free an iterator allocated by walIteratorInit().
+*/
+static void walIteratorFree(WalIterator *p){
+  sqlite3ScratchFree(p);
+}
+
+/*
+** Construct a WalInterator object that can be used to loop over all 
+** pages in the WAL in ascending order. The caller must hold the checkpoint
+** lock.
+**
+** On success, make *pp point to the newly allocated WalInterator object
+** return SQLITE_OK. Otherwise, return an error code. If this routine
+** returns an error, the value of *pp is undefined.
+**
+** The calling routine should invoke walIteratorFree() to destroy the
+** WalIterator object when it has finished with it.
+*/
+static int walIteratorInit(Wal *pWal, WalIterator **pp){
+  WalIterator *p;                 /* Return value */
+  int nSegment;                   /* Number of segments to merge */
+  u32 iLast;                      /* Last frame in log */
+  int nByte;                      /* Number of bytes to allocate */
+  int i;                          /* Iterator variable */
+  ht_slot *aTmp;                  /* Temp space used by merge-sort */
+  int rc = SQLITE_OK;             /* Return Code */
+
+  /* This routine only runs while holding the checkpoint lock. And
+  ** it only runs if there is actually content in the log (mxFrame>0).
+  */
+  assert( pWal->ckptLock && pWal->hdr.mxFrame>0 );
+  iLast = pWal->hdr.mxFrame;
+
+  /* Allocate space for the WalIterator object. */
+  nSegment = walFramePage(iLast) + 1;
+  nByte = sizeof(WalIterator) 
+        + (nSegment-1)*sizeof(struct WalSegment)
+        + iLast*sizeof(ht_slot);
+  p = (WalIterator *)sqlite3ScratchMalloc(nByte);
+  if( !p ){
+    return SQLITE_NOMEM;
+  }
+  memset(p, 0, nByte);
+  p->nSegment = nSegment;
+
+  /* Allocate temporary space used by the merge-sort routine. This block
+  ** of memory will be freed before this function returns.
+  */
+  aTmp = (ht_slot *)sqlite3ScratchMalloc(
+      sizeof(ht_slot) * (iLast>HASHTABLE_NPAGE?HASHTABLE_NPAGE:iLast)
+  );
+  if( !aTmp ){
+    rc = SQLITE_NOMEM;
+  }
+
+  for(i=0; rc==SQLITE_OK && i<nSegment; i++){
+    volatile ht_slot *aHash;
+    u32 iZero;
+    volatile u32 *aPgno;
+
+    rc = walHashGet(pWal, i, &aHash, &aPgno, &iZero);
+    if( rc==SQLITE_OK ){
+      int j;                      /* Counter variable */
+      int nEntry;                 /* Number of entries in this segment */
+      ht_slot *aIndex;            /* Sorted index for this segment */
+
+      aPgno++;
+      if( (i+1)==nSegment ){
+        nEntry = (int)(iLast - iZero);
+      }else{
+        nEntry = (int)((u32*)aHash - (u32*)aPgno);
+      }
+      aIndex = &((ht_slot *)&p->aSegment[p->nSegment])[iZero];
+      iZero++;
+  
+      for(j=0; j<nEntry; j++){
+        aIndex[j] = (ht_slot)j;
+      }
+      walMergesort((u32 *)aPgno, aTmp, aIndex, &nEntry);
+      p->aSegment[i].iZero = iZero;
+      p->aSegment[i].nEntry = nEntry;
+      p->aSegment[i].aIndex = aIndex;
+      p->aSegment[i].aPgno = (u32 *)aPgno;
+    }
+  }
+  sqlite3ScratchFree(aTmp);
+
+  if( rc!=SQLITE_OK ){
+    walIteratorFree(p);
+  }
+  *pp = p;
+  return rc;
+}
+
+/*
+** Attempt to obtain the exclusive WAL lock defined by parameters lockIdx and
+** n. If the attempt fails and parameter xBusy is not NULL, then it is a
+** busy-handler function. Invoke it and retry the lock until either the
+** lock is successfully obtained or the busy-handler returns 0.
+*/
+static int walBusyLock(
+  Wal *pWal,                      /* WAL connection */
+  int (*xBusy)(void*),            /* Function to call when busy */
+  void *pBusyArg,                 /* Context argument for xBusyHandler */
+  int lockIdx,                    /* Offset of first byte to lock */
+  int n                           /* Number of bytes to lock */
+){
+  int rc;
+  do {
+    rc = walLockExclusive(pWal, lockIdx, n);
+  }while( xBusy && rc==SQLITE_BUSY && xBusy(pBusyArg) );
+  return rc;
+}
+
+/*
+** The cache of the wal-index header must be valid to call this function.
+** Return the page-size in bytes used by the database.
+*/
+static int walPagesize(Wal *pWal){
+  return (pWal->hdr.szPage&0xfe00) + ((pWal->hdr.szPage&0x0001)<<16);
+}
+
+/*
+** Copy as much content as we can from the WAL back into the database file
+** in response to an sqlite3_wal_checkpoint() request or the equivalent.
+**
+** The amount of information copies from WAL to database might be limited
+** by active readers.  This routine will never overwrite a database page
+** that a concurrent reader might be using.
+**
+** All I/O barrier operations (a.k.a fsyncs) occur in this routine when
+** SQLite is in WAL-mode in synchronous=NORMAL.  That means that if 
+** checkpoints are always run by a background thread or background 
+** process, foreground threads will never block on a lengthy fsync call.
+**
+** Fsync is called on the WAL before writing content out of the WAL and
+** into the database.  This ensures that if the new content is persistent
+** in the WAL and can be recovered following a power-loss or hard reset.
+**
+** Fsync is also called on the database file if (and only if) the entire
+** WAL content is copied into the database file.  This second fsync makes
+** it safe to delete the WAL since the new content will persist in the
+** database file.
+**
+** This routine uses and updates the nBackfill field of the wal-index header.
+** This is the only routine tha will increase the value of nBackfill.  
+** (A WAL reset or recovery will revert nBackfill to zero, but not increase
+** its value.)
+**
+** The caller must be holding sufficient locks to ensure that no other
+** checkpoint is running (in any other thread or process) at the same
+** time.
+*/
+static int walCheckpoint(
+  Wal *pWal,                      /* Wal connection */
+  int eMode,                      /* One of PASSIVE, FULL or RESTART */
+  int (*xBusyCall)(void*),        /* Function to call when busy */
+  void *pBusyArg,                 /* Context argument for xBusyHandler */
+  int sync_flags,                 /* Flags for OsSync() (or 0) */
+  u8 *zBuf                        /* Temporary buffer to use */
+){
+  int rc;                         /* Return code */
+  int szPage;                     /* Database page-size */
+  WalIterator *pIter = 0;         /* Wal iterator context */
+  u32 iDbpage = 0;                /* Next database page to write */
+  u32 iFrame = 0;                 /* Wal frame containing data for iDbpage */
+  u32 mxSafeFrame;                /* Max frame that can be backfilled */
+  u32 mxPage;                     /* Max database page to write */
+  int i;                          /* Loop counter */
+  volatile WalCkptInfo *pInfo;    /* The checkpoint status information */
+  int (*xBusy)(void*) = 0;        /* Function to call when waiting for locks */
+
+  szPage = walPagesize(pWal);
+  testcase( szPage<=32768 );
+  testcase( szPage>=65536 );
+  pInfo = walCkptInfo(pWal);
+  if( pInfo->nBackfill>=pWal->hdr.mxFrame ) return SQLITE_OK;
+
+  /* Allocate the iterator */
+  rc = walIteratorInit(pWal, &pIter);
+  if( rc!=SQLITE_OK ){
+    return rc;
+  }
+  assert( pIter );
+
+  if( eMode!=SQLITE_CHECKPOINT_PASSIVE ) xBusy = xBusyCall;
+
+  /* Compute in mxSafeFrame the index of the last frame of the WAL that is
+  ** safe to write into the database.  Frames beyond mxSafeFrame might
+  ** overwrite database pages that are in use by active readers and thus
+  ** cannot be backfilled from the WAL.
+  */
+  mxSafeFrame = pWal->hdr.mxFrame;
+  mxPage = pWal->hdr.nPage;
+  for(i=1; i<WAL_NREADER; i++){
+    u32 y = pInfo->aReadMark[i];
+    if( mxSafeFrame>y ){
+      assert( y<=pWal->hdr.mxFrame );
+      rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_READ_LOCK(i), 1);
+      if( rc==SQLITE_OK ){
+        pInfo->aReadMark[i] = READMARK_NOT_USED;
+        walUnlockExclusive(pWal, WAL_READ_LOCK(i), 1);
+      }else if( rc==SQLITE_BUSY ){
+        mxSafeFrame = y;
+        xBusy = 0;
+      }else{
+        goto walcheckpoint_out;
+      }
+    }
+  }
+
+  if( pInfo->nBackfill<mxSafeFrame
+   && (rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_READ_LOCK(0), 1))==SQLITE_OK
+  ){
+    i64 nSize;                    /* Current size of database file */
+    u32 nBackfill = pInfo->nBackfill;
+
+    /* Sync the WAL to disk */
+    if( sync_flags ){
+      rc = sqlite3OsSync(pWal->pWalFd, sync_flags);
+    }
+
+    /* If the database file may grow as a result of this checkpoint, hint
+    ** about the eventual size of the db file to the VFS layer. 
+    */
+    if( rc==SQLITE_OK ){
+      i64 nReq = ((i64)mxPage * szPage);
+      rc = sqlite3OsFileSize(pWal->pDbFd, &nSize);
+      if( rc==SQLITE_OK && nSize<nReq ){
+        sqlite3OsFileControl(pWal->pDbFd, SQLITE_FCNTL_SIZE_HINT, &nReq);
+      }
+    }
+
+    /* Iterate through the contents of the WAL, copying data to the db file. */
+    while( rc==SQLITE_OK && 0==walIteratorNext(pIter, &iDbpage, &iFrame) ){
+      i64 iOffset;
+      assert( walFramePgno(pWal, iFrame)==iDbpage );
+      if( iFrame<=nBackfill || iFrame>mxSafeFrame || iDbpage>mxPage ) continue;
+      iOffset = walFrameOffset(iFrame, szPage) + WAL_FRAME_HDRSIZE;
+      /* testcase( IS_BIG_INT(iOffset) ); // requires a 4GiB WAL file */
+      rc = sqlite3OsRead(pWal->pWalFd, zBuf, szPage, iOffset);
+      if( rc!=SQLITE_OK ) break;
+      iOffset = (iDbpage-1)*(i64)szPage;
+      testcase( IS_BIG_INT(iOffset) );
+      rc = sqlite3OsWrite(pWal->pDbFd, zBuf, szPage, iOffset);
+      if( rc!=SQLITE_OK ) break;
+    }
+
+    /* If work was actually accomplished... */
+    if( rc==SQLITE_OK ){
+      if( mxSafeFrame==walIndexHdr(pWal)->mxFrame ){
+        i64 szDb = pWal->hdr.nPage*(i64)szPage;
+        testcase( IS_BIG_INT(szDb) );
+        rc = sqlite3OsTruncate(pWal->pDbFd, szDb);
+        if( rc==SQLITE_OK && sync_flags ){
+          rc = sqlite3OsSync(pWal->pDbFd, sync_flags);
+        }
+      }
+      if( rc==SQLITE_OK ){
+        pInfo->nBackfill = mxSafeFrame;
+      }
+    }
+
+    /* Release the reader lock held while backfilling */
+    walUnlockExclusive(pWal, WAL_READ_LOCK(0), 1);
+  }
+
+  if( rc==SQLITE_BUSY ){
+    /* Reset the return code so as not to report a checkpoint failure
+    ** just because there are active readers.  */
+    rc = SQLITE_OK;
+  }
+
+  /* If this is an SQLITE_CHECKPOINT_RESTART operation, and the entire wal
+  ** file has been copied into the database file, then block until all
+  ** readers have finished using the wal file. This ensures that the next
+  ** process to write to the database restarts the wal file.
+  */
+  if( rc==SQLITE_OK && eMode!=SQLITE_CHECKPOINT_PASSIVE ){
+    assert( pWal->writeLock );
+    if( pInfo->nBackfill<pWal->hdr.mxFrame ){
+      rc = SQLITE_BUSY;
+    }else if( eMode==SQLITE_CHECKPOINT_RESTART ){
+      assert( mxSafeFrame==pWal->hdr.mxFrame );
+      rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_READ_LOCK(1), WAL_NREADER-1);
+      if( rc==SQLITE_OK ){
+        walUnlockExclusive(pWal, WAL_READ_LOCK(1), WAL_NREADER-1);
+      }
+    }
+  }
+
+ walcheckpoint_out:
+  walIteratorFree(pIter);
+  return rc;
+}
+
+/*
+** Close a connection to a log file.
+*/
+SQLITE_PRIVATE int sqlite3WalClose(
+  Wal *pWal,                      /* Wal to close */
+  int sync_flags,                 /* Flags to pass to OsSync() (or 0) */
+  int nBuf,
+  u8 *zBuf                        /* Buffer of at least nBuf bytes */
+){
+  int rc = SQLITE_OK;
+  if( pWal ){
+    int isDelete = 0;             /* True to unlink wal and wal-index files */
+
+    /* If an EXCLUSIVE lock can be obtained on the database file (using the
+    ** ordinary, rollback-mode locking methods, this guarantees that the
+    ** connection associated with this log file is the only connection to
+    ** the database. In this case checkpoint the database and unlink both
+    ** the wal and wal-index files.
+    **
+    ** The EXCLUSIVE lock is not released before returning.
+    */
+    rc = sqlite3OsLock(pWal->pDbFd, SQLITE_LOCK_EXCLUSIVE);
+    if( rc==SQLITE_OK ){
+      if( pWal->exclusiveMode==WAL_NORMAL_MODE ){
+        pWal->exclusiveMode = WAL_EXCLUSIVE_MODE;
+      }
+      rc = sqlite3WalCheckpoint(
+          pWal, SQLITE_CHECKPOINT_PASSIVE, 0, 0, sync_flags, nBuf, zBuf, 0, 0
+      );
+      if( rc==SQLITE_OK ){
+        isDelete = 1;
+      }
+    }
+
+    walIndexClose(pWal, isDelete);
+    sqlite3OsClose(pWal->pWalFd);
+    if( isDelete ){
+      sqlite3OsDelete(pWal->pVfs, pWal->zWalName, 0);
+    }
+    WALTRACE(("WAL%p: closed\n", pWal));
+    sqlite3_free((void *)pWal->apWiData);
+    sqlite3_free(pWal);
+  }
+  return rc;
+}
+
+/*
+** Try to read the wal-index header.  Return 0 on success and 1 if
+** there is a problem.
+**
+** The wal-index is in shared memory.  Another thread or process might
+** be writing the header at the same time this procedure is trying to
+** read it, which might result in inconsistency.  A dirty read is detected
+** by verifying that both copies of the header are the same and also by
+** a checksum on the header.
+**
+** If and only if the read is consistent and the header is different from
+** pWal->hdr, then pWal->hdr is updated to the content of the new header
+** and *pChanged is set to 1.
+**
+** If the checksum cannot be verified return non-zero. If the header
+** is read successfully and the checksum verified, return zero.
+*/
+static int walIndexTryHdr(Wal *pWal, int *pChanged){
+  u32 aCksum[2];                  /* Checksum on the header content */
+  WalIndexHdr h1, h2;             /* Two copies of the header content */
+  WalIndexHdr volatile *aHdr;     /* Header in shared memory */
+
+  /* The first page of the wal-index must be mapped at this point. */
+  assert( pWal->nWiData>0 && pWal->apWiData[0] );
+
+  /* Read the header. This might happen concurrently with a write to the
+  ** same area of shared memory on a different CPU in a SMP,
+  ** meaning it is possible that an inconsistent snapshot is read
+  ** from the file. If this happens, return non-zero.
+  **
+  ** There are two copies of the header at the beginning of the wal-index.
+  ** When reading, read [0] first then [1].  Writes are in the reverse order.
+  ** Memory barriers are used to prevent the compiler or the hardware from
+  ** reordering the reads and writes.
+  */
+  aHdr = walIndexHdr(pWal);
+  memcpy(&h1, (void *)&aHdr[0], sizeof(h1));
+  walShmBarrier(pWal);
+  memcpy(&h2, (void *)&aHdr[1], sizeof(h2));
+
+  if( memcmp(&h1, &h2, sizeof(h1))!=0 ){
+    return 1;   /* Dirty read */
+  }  
+  if( h1.isInit==0 ){
+    return 1;   /* Malformed header - probably all zeros */
+  }
+  walChecksumBytes(1, (u8*)&h1, sizeof(h1)-sizeof(h1.aCksum), 0, aCksum);
+  if( aCksum[0]!=h1.aCksum[0] || aCksum[1]!=h1.aCksum[1] ){
+    return 1;   /* Checksum does not match */
+  }
+
+  if( memcmp(&pWal->hdr, &h1, sizeof(WalIndexHdr)) ){
+    *pChanged = 1;
+    memcpy(&pWal->hdr, &h1, sizeof(WalIndexHdr));
+    pWal->szPage = (pWal->hdr.szPage&0xfe00) + ((pWal->hdr.szPage&0x0001)<<16);
+    testcase( pWal->szPage<=32768 );
+    testcase( pWal->szPage>=65536 );
+  }
+
+  /* The header was successfully read. Return zero. */
+  return 0;
+}
+
+/*
+** Read the wal-index header from the wal-index and into pWal->hdr.
+** If the wal-header appears to be corrupt, try to reconstruct the
+** wal-index from the WAL before returning.
+**
+** Set *pChanged to 1 if the wal-index header value in pWal->hdr is
+** changed by this opertion.  If pWal->hdr is unchanged, set *pChanged
+** to 0.
+**
+** If the wal-index header is successfully read, return SQLITE_OK. 
+** Otherwise an SQLite error code.
+*/
+static int walIndexReadHdr(Wal *pWal, int *pChanged){
+  int rc;                         /* Return code */
+  int badHdr;                     /* True if a header read failed */
+  volatile u32 *page0;            /* Chunk of wal-index containing header */
+
+  /* Ensure that page 0 of the wal-index (the page that contains the 
+  ** wal-index header) is mapped. Return early if an error occurs here.
+  */
+  assert( pChanged );
+  rc = walIndexPage(pWal, 0, &page0);
+  if( rc!=SQLITE_OK ){
+    return rc;
+  };
+  assert( page0 || pWal->writeLock==0 );
+
+  /* If the first page of the wal-index has been mapped, try to read the
+  ** wal-index header immediately, without holding any lock. This usually
+  ** works, but may fail if the wal-index header is corrupt or currently 
+  ** being modified by another thread or process.
+  */
+  badHdr = (page0 ? walIndexTryHdr(pWal, pChanged) : 1);
+
+  /* If the first attempt failed, it might have been due to a race
+  ** with a writer.  So get a WRITE lock and try again.
+  */
+  assert( badHdr==0 || pWal->writeLock==0 );
+  if( badHdr && SQLITE_OK==(rc = walLockExclusive(pWal, WAL_WRITE_LOCK, 1)) ){
+    pWal->writeLock = 1;
+    if( SQLITE_OK==(rc = walIndexPage(pWal, 0, &page0)) ){
+      badHdr = walIndexTryHdr(pWal, pChanged);
+      if( badHdr ){
+        /* If the wal-index header is still malformed even while holding
+        ** a WRITE lock, it can only mean that the header is corrupted and
+        ** needs to be reconstructed.  So run recovery to do exactly that.
+        */
+        rc = walIndexRecover(pWal);
+        *pChanged = 1;
+      }
+    }
+    pWal->writeLock = 0;
+    walUnlockExclusive(pWal, WAL_WRITE_LOCK, 1);
+  }
+
+  /* If the header is read successfully, check the version number to make
+  ** sure the wal-index was not constructed with some future format that
+  ** this version of SQLite cannot understand.
+  */
+  if( badHdr==0 && pWal->hdr.iVersion!=WALINDEX_MAX_VERSION ){
+    rc = SQLITE_CANTOPEN_BKPT;
+  }
+
+  return rc;
+}
+
+/*
+** This is the value that walTryBeginRead returns when it needs to
+** be retried.
+*/
+#define WAL_RETRY  (-1)
+
+/*
+** Attempt to start a read transaction.  This might fail due to a race or
+** other transient condition.  When that happens, it returns WAL_RETRY to
+** indicate to the caller that it is safe to retry immediately.
+**
+** On success return SQLITE_OK.  On a permanent failure (such an
+** I/O error or an SQLITE_BUSY because another process is running
+** recovery) return a positive error code.
+**
+** The useWal parameter is true to force the use of the WAL and disable
+** the case where the WAL is bypassed because it has been completely
+** checkpointed.  If useWal==0 then this routine calls walIndexReadHdr() 
+** to make a copy of the wal-index header into pWal->hdr.  If the 
+** wal-index header has changed, *pChanged is set to 1 (as an indication 
+** to the caller that the local paget cache is obsolete and needs to be 
+** flushed.)  When useWal==1, the wal-index header is assumed to already
+** be loaded and the pChanged parameter is unused.
+**
+** The caller must set the cnt parameter to the number of prior calls to
+** this routine during the current read attempt that returned WAL_RETRY.
+** This routine will start taking more aggressive measures to clear the
+** race conditions after multiple WAL_RETRY returns, and after an excessive
+** number of errors will ultimately return SQLITE_PROTOCOL.  The
+** SQLITE_PROTOCOL return indicates that some other process has gone rogue
+** and is not honoring the locking protocol.  There is a vanishingly small
+** chance that SQLITE_PROTOCOL could be returned because of a run of really
+** bad luck when there is lots of contention for the wal-index, but that
+** possibility is so small that it can be safely neglected, we believe.
+**
+** On success, this routine obtains a read lock on 
+** WAL_READ_LOCK(pWal->readLock).  The pWal->readLock integer is
+** in the range 0 <= pWal->readLock < WAL_NREADER.  If pWal->readLock==(-1)
+** that means the Wal does not hold any read lock.  The reader must not
+** access any database page that is modified by a WAL frame up to and
+** including frame number aReadMark[pWal->readLock].  The reader will
+** use WAL frames up to and including pWal->hdr.mxFrame if pWal->readLock>0
+** Or if pWal->readLock==0, then the reader will ignore the WAL
+** completely and get all content directly from the database file.
+** If the useWal parameter is 1 then the WAL will never be ignored and
+** this routine will always set pWal->readLock>0 on success.
+** When the read transaction is completed, the caller must release the
+** lock on WAL_READ_LOCK(pWal->readLock) and set pWal->readLock to -1.
+**
+** This routine uses the nBackfill and aReadMark[] fields of the header
+** to select a particular WAL_READ_LOCK() that strives to let the
+** checkpoint process do as much work as possible.  This routine might
+** update values of the aReadMark[] array in the header, but if it does
+** so it takes care to hold an exclusive lock on the corresponding
+** WAL_READ_LOCK() while changing values.
+*/
+static int walTryBeginRead(Wal *pWal, int *pChanged, int useWal, int cnt){
+  volatile WalCkptInfo *pInfo;    /* Checkpoint information in wal-index */
+  u32 mxReadMark;                 /* Largest aReadMark[] value */
+  int mxI;                        /* Index of largest aReadMark[] value */
+  int i;                          /* Loop counter */
+  int rc = SQLITE_OK;             /* Return code  */
+
+  assert( pWal->readLock<0 );     /* Not currently locked */
+
+  /* Take steps to avoid spinning forever if there is a protocol error.
+  **
+  ** Circumstances that cause a RETRY should only last for the briefest
+  ** instances of time.  No I/O or other system calls are done while the
+  ** locks are held, so the locks should not be held for very long. But 
+  ** if we are unlucky, another process that is holding a lock might get
+  ** paged out or take a page-fault that is time-consuming to resolve, 
+  ** during the few nanoseconds that it is holding the lock.  In that case,
+  ** it might take longer than normal for the lock to free.
+  **
+  ** After 5 RETRYs, we begin calling sqlite3OsSleep().  The first few
+  ** calls to sqlite3OsSleep() have a delay of 1 microsecond.  Really this
+  ** is more of a scheduler yield than an actual delay.  But on the 10th
+  ** an subsequent retries, the delays start becoming longer and longer, 
+  ** so that on the 100th (and last) RETRY we delay for 21 milliseconds.
+  ** The total delay time before giving up is less than 1 second.
+  */
+  if( cnt>5 ){
+    int nDelay = 1;                      /* Pause time in microseconds */
+    if( cnt>100 ){
+      VVA_ONLY( pWal->lockError = 1; )
+      return SQLITE_PROTOCOL;
+    }
+    if( cnt>=10 ) nDelay = (cnt-9)*238;  /* Max delay 21ms. Total delay 996ms */
+    sqlite3OsSleep(pWal->pVfs, nDelay);
+  }
+
+  if( !useWal ){
+    rc = walIndexReadHdr(pWal, pChanged);
+    if( rc==SQLITE_BUSY ){
+      /* If there is not a recovery running in another thread or process
+      ** then convert BUSY errors to WAL_RETRY.  If recovery is known to
+      ** be running, convert BUSY to BUSY_RECOVERY.  There is a race here
+      ** which might cause WAL_RETRY to be returned even if BUSY_RECOVERY
+      ** would be technically correct.  But the race is benign since with
+      ** WAL_RETRY this routine will be called again and will probably be
+      ** right on the second iteration.
+      */
+      if( pWal->apWiData[0]==0 ){
+        /* This branch is taken when the xShmMap() method returns SQLITE_BUSY.
+        ** We assume this is a transient condition, so return WAL_RETRY. The
+        ** xShmMap() implementation used by the default unix and win32 VFS 
+        ** modules may return SQLITE_BUSY due to a race condition in the 
+        ** code that determines whether or not the shared-memory region 
+        ** must be zeroed before the requested page is returned.
+        */
+        rc = WAL_RETRY;
+      }else if( SQLITE_OK==(rc = walLockShared(pWal, WAL_RECOVER_LOCK)) ){
+        walUnlockShared(pWal, WAL_RECOVER_LOCK);
+        rc = WAL_RETRY;
+      }else if( rc==SQLITE_BUSY ){
+        rc = SQLITE_BUSY_RECOVERY;
+      }
+    }
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+  }
+
+  pInfo = walCkptInfo(pWal);
+  if( !useWal && pInfo->nBackfill==pWal->hdr.mxFrame ){
+    /* The WAL has been completely backfilled (or it is empty).
+    ** and can be safely ignored.
+    */
+    rc = walLockShared(pWal, WAL_READ_LOCK(0));
+    walShmBarrier(pWal);
+    if( rc==SQLITE_OK ){
+      if( memcmp((void *)walIndexHdr(pWal), &pWal->hdr, sizeof(WalIndexHdr)) ){
+        /* It is not safe to allow the reader to continue here if frames
+        ** may have been appended to the log before READ_LOCK(0) was obtained.
+        ** When holding READ_LOCK(0), the reader ignores the entire log file,
+        ** which implies that the database file contains a trustworthy
+        ** snapshoT. Since holding READ_LOCK(0) prevents a checkpoint from
+        ** happening, this is usually correct.
+        **
+        ** However, if frames have been appended to the log (or if the log 
+        ** is wrapped and written for that matter) before the READ_LOCK(0)
+        ** is obtained, that is not necessarily true. A checkpointer may
+        ** have started to backfill the appended frames but crashed before
+        ** it finished. Leaving a corrupt image in the database file.
+        */
+        walUnlockShared(pWal, WAL_READ_LOCK(0));
+        return WAL_RETRY;
+      }
+      pWal->readLock = 0;
+      return SQLITE_OK;
+    }else if( rc!=SQLITE_BUSY ){
+      return rc;
+    }
+  }
+
+  /* If we get this far, it means that the reader will want to use
+  ** the WAL to get at content from recent commits.  The job now is
+  ** to select one of the aReadMark[] entries that is closest to
+  ** but not exceeding pWal->hdr.mxFrame and lock that entry.
+  */
+  mxReadMark = 0;
+  mxI = 0;
+  for(i=1; i<WAL_NREADER; i++){
+    u32 thisMark = pInfo->aReadMark[i];
+    if( mxReadMark<=thisMark && thisMark<=pWal->hdr.mxFrame ){
+      assert( thisMark!=READMARK_NOT_USED );
+      mxReadMark = thisMark;
+      mxI = i;
+    }
+  }
+  /* There was once an "if" here. The extra "{" is to preserve indentation. */
+  {
+    if( mxReadMark < pWal->hdr.mxFrame || mxI==0 ){
+      for(i=1; i<WAL_NREADER; i++){
+        rc = walLockExclusive(pWal, WAL_READ_LOCK(i), 1);
+        if( rc==SQLITE_OK ){
+          mxReadMark = pInfo->aReadMark[i] = pWal->hdr.mxFrame;
+          mxI = i;
+          walUnlockExclusive(pWal, WAL_READ_LOCK(i), 1);
+          break;
+        }else if( rc!=SQLITE_BUSY ){
+          return rc;
+        }
+      }
+    }
+    if( mxI==0 ){
+      assert( rc==SQLITE_BUSY );
+      return WAL_RETRY;
+    }
+
+    rc = walLockShared(pWal, WAL_READ_LOCK(mxI));
+    if( rc ){
+      return rc==SQLITE_BUSY ? WAL_RETRY : rc;
+    }
+    /* Now that the read-lock has been obtained, check that neither the
+    ** value in the aReadMark[] array or the contents of the wal-index
+    ** header have changed.
+    **
+    ** It is necessary to check that the wal-index header did not change
+    ** between the time it was read and when the shared-lock was obtained
+    ** on WAL_READ_LOCK(mxI) was obtained to account for the possibility
+    ** that the log file may have been wrapped by a writer, or that frames
+    ** that occur later in the log than pWal->hdr.mxFrame may have been
+    ** copied into the database by a checkpointer. If either of these things
+    ** happened, then reading the database with the current value of
+    ** pWal->hdr.mxFrame risks reading a corrupted snapshot. So, retry
+    ** instead.
+    **
+    ** This does not guarantee that the copy of the wal-index header is up to
+    ** date before proceeding. That would not be possible without somehow
+    ** blocking writers. It only guarantees that a dangerous checkpoint or 
+    ** log-wrap (either of which would require an exclusive lock on
+    ** WAL_READ_LOCK(mxI)) has not occurred since the snapshot was valid.
+    */
+    walShmBarrier(pWal);
+    if( pInfo->aReadMark[mxI]!=mxReadMark
+     || memcmp((void *)walIndexHdr(pWal), &pWal->hdr, sizeof(WalIndexHdr))
+    ){
+      walUnlockShared(pWal, WAL_READ_LOCK(mxI));
+      return WAL_RETRY;
+    }else{
+      assert( mxReadMark<=pWal->hdr.mxFrame );
+      pWal->readLock = (i16)mxI;
+    }
+  }
+  return rc;
+}
+
+/*
+** Begin a read transaction on the database.
+**
+** This routine used to be called sqlite3OpenSnapshot() and with good reason:
+** it takes a snapshot of the state of the WAL and wal-index for the current
+** instant in time.  The current thread will continue to use this snapshot.
+** Other threads might append new content to the WAL and wal-index but
+** that extra content is ignored by the current thread.
+**
+** If the database contents have changes since the previous read
+** transaction, then *pChanged is set to 1 before returning.  The
+** Pager layer will use this to know that is cache is stale and
+** needs to be flushed.
+*/
+SQLITE_PRIVATE int sqlite3WalBeginReadTransaction(Wal *pWal, int *pChanged){
+  int rc;                         /* Return code */
+  int cnt = 0;                    /* Number of TryBeginRead attempts */
+
+  do{
+    rc = walTryBeginRead(pWal, pChanged, 0, ++cnt);
+  }while( rc==WAL_RETRY );
+  testcase( (rc&0xff)==SQLITE_BUSY );
+  testcase( (rc&0xff)==SQLITE_IOERR );
+  testcase( rc==SQLITE_PROTOCOL );
+  testcase( rc==SQLITE_OK );
+  return rc;
+}
+
+/*
+** Finish with a read transaction.  All this does is release the
+** read-lock.
+*/
+SQLITE_PRIVATE void sqlite3WalEndReadTransaction(Wal *pWal){
+  sqlite3WalEndWriteTransaction(pWal);
+  if( pWal->readLock>=0 ){
+    walUnlockShared(pWal, WAL_READ_LOCK(pWal->readLock));
+    pWal->readLock = -1;
+  }
+}
+
+/*
+** Read a page from the WAL, if it is present in the WAL and if the 
+** current read transaction is configured to use the WAL.  
+**
+** The *pInWal is set to 1 if the requested page is in the WAL and
+** has been loaded.  Or *pInWal is set to 0 if the page was not in 
+** the WAL and needs to be read out of the database.
+*/
+SQLITE_PRIVATE int sqlite3WalRead(
+  Wal *pWal,                      /* WAL handle */
+  Pgno pgno,                      /* Database page number to read data for */
+  int *pInWal,                    /* OUT: True if data is read from WAL */
+  int nOut,                       /* Size of buffer pOut in bytes */
+  u8 *pOut                        /* Buffer to write page data to */
+){
+  u32 iRead = 0;                  /* If !=0, WAL frame to return data from */
+  u32 iLast = pWal->hdr.mxFrame;  /* Last page in WAL for this reader */
+  int iHash;                      /* Used to loop through N hash tables */
+
+  /* This routine is only be called from within a read transaction. */
+  assert( pWal->readLock>=0 || pWal->lockError );
+
+  /* If the "last page" field of the wal-index header snapshot is 0, then
+  ** no data will be read from the wal under any circumstances. Return early
+  ** in this case as an optimization.  Likewise, if pWal->readLock==0, 
+  ** then the WAL is ignored by the reader so return early, as if the 
+  ** WAL were empty.
+  */
+  if( iLast==0 || pWal->readLock==0 ){
+    *pInWal = 0;
+    return SQLITE_OK;
+  }
+
+  /* Search the hash table or tables for an entry matching page number
+  ** pgno. Each iteration of the following for() loop searches one
+  ** hash table (each hash table indexes up to HASHTABLE_NPAGE frames).
+  **
+  ** This code might run concurrently to the code in walIndexAppend()
+  ** that adds entries to the wal-index (and possibly to this hash 
+  ** table). This means the value just read from the hash 
+  ** slot (aHash[iKey]) may have been added before or after the 
+  ** current read transaction was opened. Values added after the
+  ** read transaction was opened may have been written incorrectly -
+  ** i.e. these slots may contain garbage data. However, we assume
+  ** that any slots written before the current read transaction was
+  ** opened remain unmodified.
+  **
+  ** For the reasons above, the if(...) condition featured in the inner
+  ** loop of the following block is more stringent that would be required 
+  ** if we had exclusive access to the hash-table:
+  **
+  **   (aPgno[iFrame]==pgno): 
+  **     This condition filters out normal hash-table collisions.
+  **
+  **   (iFrame<=iLast): 
+  **     This condition filters out entries that were added to the hash
+  **     table after the current read-transaction had started.
+  */
+  for(iHash=walFramePage(iLast); iHash>=0 && iRead==0; iHash--){
+    volatile ht_slot *aHash;      /* Pointer to hash table */
+    volatile u32 *aPgno;          /* Pointer to array of page numbers */
+    u32 iZero;                    /* Frame number corresponding to aPgno[0] */
+    int iKey;                     /* Hash slot index */
+    int nCollide;                 /* Number of hash collisions remaining */
+    int rc;                       /* Error code */
+
+    rc = walHashGet(pWal, iHash, &aHash, &aPgno, &iZero);
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+    nCollide = HASHTABLE_NSLOT;
+    for(iKey=walHash(pgno); aHash[iKey]; iKey=walNextHash(iKey)){
+      u32 iFrame = aHash[iKey] + iZero;
+      if( iFrame<=iLast && aPgno[aHash[iKey]]==pgno ){
+        assert( iFrame>iRead );
+        iRead = iFrame;
+      }
+      if( (nCollide--)==0 ){
+        return SQLITE_CORRUPT_BKPT;
+      }
+    }
+  }
+
+#ifdef SQLITE_ENABLE_EXPENSIVE_ASSERT
+  /* If expensive assert() statements are available, do a linear search
+  ** of the wal-index file content. Make sure the results agree with the
+  ** result obtained using the hash indexes above.  */
+  {
+    u32 iRead2 = 0;
+    u32 iTest;
+    for(iTest=iLast; iTest>0; iTest--){
+      if( walFramePgno(pWal, iTest)==pgno ){
+        iRead2 = iTest;
+        break;
+      }
+    }
+    assert( iRead==iRead2 );
+  }
+#endif
+
+  /* If iRead is non-zero, then it is the log frame number that contains the
+  ** required page. Read and return data from the log file.
+  */
+  if( iRead ){
+    int sz;
+    i64 iOffset;
+    sz = pWal->hdr.szPage;
+    sz = (pWal->hdr.szPage&0xfe00) + ((pWal->hdr.szPage&0x0001)<<16);
+    testcase( sz<=32768 );
+    testcase( sz>=65536 );
+    iOffset = walFrameOffset(iRead, sz) + WAL_FRAME_HDRSIZE;
+    *pInWal = 1;
+    /* testcase( IS_BIG_INT(iOffset) ); // requires a 4GiB WAL */
+    return sqlite3OsRead(pWal->pWalFd, pOut, nOut, iOffset);
+  }
+
+  *pInWal = 0;
+  return SQLITE_OK;
+}
+
+
+/* 
+** Return the size of the database in pages (or zero, if unknown).
+*/
+SQLITE_PRIVATE Pgno sqlite3WalDbsize(Wal *pWal){
+  if( pWal && ALWAYS(pWal->readLock>=0) ){
+    return pWal->hdr.nPage;
+  }
+  return 0;
+}
+
+
+/* 
+** This function starts a write transaction on the WAL.
+**
+** A read transaction must have already been started by a prior call
+** to sqlite3WalBeginReadTransaction().
+**
+** If another thread or process has written into the database since
+** the read transaction was started, then it is not possible for this
+** thread to write as doing so would cause a fork.  So this routine
+** returns SQLITE_BUSY in that case and no write transaction is started.
+**
+** There can only be a single writer active at a time.
+*/
+SQLITE_PRIVATE int sqlite3WalBeginWriteTransaction(Wal *pWal){
+  int rc;
+
+  /* Cannot start a write transaction without first holding a read
+  ** transaction. */
+  assert( pWal->readLock>=0 );
+
+  if( pWal->readOnly ){
+    return SQLITE_READONLY;
+  }
+
+  /* Only one writer allowed at a time.  Get the write lock.  Return
+  ** SQLITE_BUSY if unable.
+  */
+  rc = walLockExclusive(pWal, WAL_WRITE_LOCK, 1);
+  if( rc ){
+    return rc;
+  }
+  pWal->writeLock = 1;
+
+  /* If another connection has written to the database file since the
+  ** time the read transaction on this connection was started, then
+  ** the write is disallowed.
+  */
+  if( memcmp(&pWal->hdr, (void *)walIndexHdr(pWal), sizeof(WalIndexHdr))!=0 ){
+    walUnlockExclusive(pWal, WAL_WRITE_LOCK, 1);
+    pWal->writeLock = 0;
+    rc = SQLITE_BUSY;
+  }
+
+  return rc;
+}
+
+/*
+** End a write transaction.  The commit has already been done.  This
+** routine merely releases the lock.
+*/
+SQLITE_PRIVATE int sqlite3WalEndWriteTransaction(Wal *pWal){
+  if( pWal->writeLock ){
+    walUnlockExclusive(pWal, WAL_WRITE_LOCK, 1);
+    pWal->writeLock = 0;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** If any data has been written (but not committed) to the log file, this
+** function moves the write-pointer back to the start of the transaction.
+**
+** Additionally, the callback function is invoked for each frame written
+** to the WAL since the start of the transaction. If the callback returns
+** other than SQLITE_OK, it is not invoked again and the error code is
+** returned to the caller.
+**
+** Otherwise, if the callback function does not return an error, this
+** function returns SQLITE_OK.
+*/
+SQLITE_PRIVATE int sqlite3WalUndo(Wal *pWal, int (*xUndo)(void *, Pgno), void *pUndoCtx){
+  int rc = SQLITE_OK;
+  if( ALWAYS(pWal->writeLock) ){
+    Pgno iMax = pWal->hdr.mxFrame;
+    Pgno iFrame;
+  
+    /* Restore the clients cache of the wal-index header to the state it
+    ** was in before the client began writing to the database. 
+    */
+    memcpy(&pWal->hdr, (void *)walIndexHdr(pWal), sizeof(WalIndexHdr));
+
+    for(iFrame=pWal->hdr.mxFrame+1; 
+        ALWAYS(rc==SQLITE_OK) && iFrame<=iMax; 
+        iFrame++
+    ){
+      /* This call cannot fail. Unless the page for which the page number
+      ** is passed as the second argument is (a) in the cache and 
+      ** (b) has an outstanding reference, then xUndo is either a no-op
+      ** (if (a) is false) or simply expels the page from the cache (if (b)
+      ** is false).
+      **
+      ** If the upper layer is doing a rollback, it is guaranteed that there
+      ** are no outstanding references to any page other than page 1. And
+      ** page 1 is never written to the log until the transaction is
+      ** committed. As a result, the call to xUndo may not fail.
+      */
+      assert( walFramePgno(pWal, iFrame)!=1 );
+      rc = xUndo(pUndoCtx, walFramePgno(pWal, iFrame));
+    }
+    walCleanupHash(pWal);
+  }
+  assert( rc==SQLITE_OK );
+  return rc;
+}
+
+/* 
+** Argument aWalData must point to an array of WAL_SAVEPOINT_NDATA u32 
+** values. This function populates the array with values required to 
+** "rollback" the write position of the WAL handle back to the current 
+** point in the event of a savepoint rollback (via WalSavepointUndo()).
+*/
+SQLITE_PRIVATE void sqlite3WalSavepoint(Wal *pWal, u32 *aWalData){
+  assert( pWal->writeLock );
+  aWalData[0] = pWal->hdr.mxFrame;
+  aWalData[1] = pWal->hdr.aFrameCksum[0];
+  aWalData[2] = pWal->hdr.aFrameCksum[1];
+  aWalData[3] = pWal->nCkpt;
+}
+
+/* 
+** Move the write position of the WAL back to the point identified by
+** the values in the aWalData[] array. aWalData must point to an array
+** of WAL_SAVEPOINT_NDATA u32 values that has been previously populated
+** by a call to WalSavepoint().
+*/
+SQLITE_PRIVATE int sqlite3WalSavepointUndo(Wal *pWal, u32 *aWalData){
+  int rc = SQLITE_OK;
+
+  assert( pWal->writeLock );
+  assert( aWalData[3]!=pWal->nCkpt || aWalData[0]<=pWal->hdr.mxFrame );
+
+  if( aWalData[3]!=pWal->nCkpt ){
+    /* This savepoint was opened immediately after the write-transaction
+    ** was started. Right after that, the writer decided to wrap around
+    ** to the start of the log. Update the savepoint values to match.
+    */
+    aWalData[0] = 0;
+    aWalData[3] = pWal->nCkpt;
+  }
+
+  if( aWalData[0]<pWal->hdr.mxFrame ){
+    pWal->hdr.mxFrame = aWalData[0];
+    pWal->hdr.aFrameCksum[0] = aWalData[1];
+    pWal->hdr.aFrameCksum[1] = aWalData[2];
+    walCleanupHash(pWal);
+  }
+
+  return rc;
+}
+
+/*
+** This function is called just before writing a set of frames to the log
+** file (see sqlite3WalFrames()). It checks to see if, instead of appending
+** to the current log file, it is possible to overwrite the start of the
+** existing log file with the new frames (i.e. "reset" the log). If so,
+** it sets pWal->hdr.mxFrame to 0. Otherwise, pWal->hdr.mxFrame is left
+** unchanged.
+**
+** SQLITE_OK is returned if no error is encountered (regardless of whether
+** or not pWal->hdr.mxFrame is modified). An SQLite error code is returned
+** if an error occurs.
+*/
+static int walRestartLog(Wal *pWal){
+  int rc = SQLITE_OK;
+  int cnt;
+
+  if( pWal->readLock==0 ){
+    volatile WalCkptInfo *pInfo = walCkptInfo(pWal);
+    assert( pInfo->nBackfill==pWal->hdr.mxFrame );
+    if( pInfo->nBackfill>0 ){
+      u32 salt1;
+      sqlite3_randomness(4, &salt1);
+      rc = walLockExclusive(pWal, WAL_READ_LOCK(1), WAL_NREADER-1);
+      if( rc==SQLITE_OK ){
+        /* If all readers are using WAL_READ_LOCK(0) (in other words if no
+        ** readers are currently using the WAL), then the transactions
+        ** frames will overwrite the start of the existing log. Update the
+        ** wal-index header to reflect this.
+        **
+        ** In theory it would be Ok to update the cache of the header only
+        ** at this point. But updating the actual wal-index header is also
+        ** safe and means there is no special case for sqlite3WalUndo()
+        ** to handle if this transaction is rolled back.
+        */
+        int i;                    /* Loop counter */
+        u32 *aSalt = pWal->hdr.aSalt;       /* Big-endian salt values */
+        pWal->nCkpt++;
+        pWal->hdr.mxFrame = 0;
+        sqlite3Put4byte((u8*)&aSalt[0], 1 + sqlite3Get4byte((u8*)&aSalt[0]));
+        aSalt[1] = salt1;
+        walIndexWriteHdr(pWal);
+        pInfo->nBackfill = 0;
+        for(i=1; i<WAL_NREADER; i++) pInfo->aReadMark[i] = READMARK_NOT_USED;
+        assert( pInfo->aReadMark[0]==0 );
+        walUnlockExclusive(pWal, WAL_READ_LOCK(1), WAL_NREADER-1);
+      }else if( rc!=SQLITE_BUSY ){
+        return rc;
+      }
+    }
+    walUnlockShared(pWal, WAL_READ_LOCK(0));
+    pWal->readLock = -1;
+    cnt = 0;
+    do{
+      int notUsed;
+      rc = walTryBeginRead(pWal, &notUsed, 1, ++cnt);
+    }while( rc==WAL_RETRY );
+    assert( (rc&0xff)!=SQLITE_BUSY ); /* BUSY not possible when useWal==1 */
+    testcase( (rc&0xff)==SQLITE_IOERR );
+    testcase( rc==SQLITE_PROTOCOL );
+    testcase( rc==SQLITE_OK );
+  }
+  return rc;
+}
+
+/* 
+** Write a set of frames to the log. The caller must hold the write-lock
+** on the log file (obtained using sqlite3WalBeginWriteTransaction()).
+*/
+SQLITE_PRIVATE int sqlite3WalFrames(
+  Wal *pWal,                      /* Wal handle to write to */
+  int szPage,                     /* Database page-size in bytes */
+  PgHdr *pList,                   /* List of dirty pages to write */
+  Pgno nTruncate,                 /* Database size after this commit */
+  int isCommit,                   /* True if this is a commit */
+  int sync_flags                  /* Flags to pass to OsSync() (or 0) */
+){
+  int rc;                         /* Used to catch return codes */
+  u32 iFrame;                     /* Next frame address */
+  u8 aFrame[WAL_FRAME_HDRSIZE];   /* Buffer to assemble frame-header in */
+  PgHdr *p;                       /* Iterator to run through pList with. */
+  PgHdr *pLast = 0;               /* Last frame in list */
+  int nLast = 0;                  /* Number of extra copies of last page */
+
+  assert( pList );
+  assert( pWal->writeLock );
+
+#if defined(SQLITE_TEST) && defined(SQLITE_DEBUG)
+  { int cnt; for(cnt=0, p=pList; p; p=p->pDirty, cnt++){}
+    WALTRACE(("WAL%p: frame write begin. %d frames. mxFrame=%d. %s\n",
+              pWal, cnt, pWal->hdr.mxFrame, isCommit ? "Commit" : "Spill"));
+  }
+#endif
+
+  /* See if it is possible to write these frames into the start of the
+  ** log file, instead of appending to it at pWal->hdr.mxFrame.
+  */
+  if( SQLITE_OK!=(rc = walRestartLog(pWal)) ){
+    return rc;
+  }
+
+  /* If this is the first frame written into the log, write the WAL
+  ** header to the start of the WAL file. See comments at the top of
+  ** this source file for a description of the WAL header format.
+  */
+  iFrame = pWal->hdr.mxFrame;
+  if( iFrame==0 ){
+    u8 aWalHdr[WAL_HDRSIZE];      /* Buffer to assemble wal-header in */
+    u32 aCksum[2];                /* Checksum for wal-header */
+
+    sqlite3Put4byte(&aWalHdr[0], (WAL_MAGIC | SQLITE_BIGENDIAN));
+    sqlite3Put4byte(&aWalHdr[4], WAL_MAX_VERSION);
+    sqlite3Put4byte(&aWalHdr[8], szPage);
+    sqlite3Put4byte(&aWalHdr[12], pWal->nCkpt);
+    sqlite3_randomness(8, pWal->hdr.aSalt);
+    memcpy(&aWalHdr[16], pWal->hdr.aSalt, 8);
+    walChecksumBytes(1, aWalHdr, WAL_HDRSIZE-2*4, 0, aCksum);
+    sqlite3Put4byte(&aWalHdr[24], aCksum[0]);
+    sqlite3Put4byte(&aWalHdr[28], aCksum[1]);
+    
+    pWal->szPage = szPage;
+    pWal->hdr.bigEndCksum = SQLITE_BIGENDIAN;
+    pWal->hdr.aFrameCksum[0] = aCksum[0];
+    pWal->hdr.aFrameCksum[1] = aCksum[1];
+
+    rc = sqlite3OsWrite(pWal->pWalFd, aWalHdr, sizeof(aWalHdr), 0);
+    WALTRACE(("WAL%p: wal-header write %s\n", pWal, rc ? "failed" : "ok"));
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+  }
+  assert( (int)pWal->szPage==szPage );
+
+  /* Write the log file. */
+  for(p=pList; p; p=p->pDirty){
+    u32 nDbsize;                  /* Db-size field for frame header */
+    i64 iOffset;                  /* Write offset in log file */
+    void *pData;
+   
+    iOffset = walFrameOffset(++iFrame, szPage);
+    /* testcase( IS_BIG_INT(iOffset) ); // requires a 4GiB WAL */
+    
+    /* Populate and write the frame header */
+    nDbsize = (isCommit && p->pDirty==0) ? nTruncate : 0;
+#if defined(SQLITE_HAS_CODEC)
+    if( (pData = sqlite3PagerCodec(p))==0 ) return SQLITE_NOMEM;
+#else
+    pData = p->pData;
+#endif
+    walEncodeFrame(pWal, p->pgno, nDbsize, pData, aFrame);
+    rc = sqlite3OsWrite(pWal->pWalFd, aFrame, sizeof(aFrame), iOffset);
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+
+    /* Write the page data */
+    rc = sqlite3OsWrite(pWal->pWalFd, pData, szPage, iOffset+sizeof(aFrame));
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+    pLast = p;
+  }
+
+  /* Sync the log file if the 'isSync' flag was specified. */
+  if( sync_flags ){
+    i64 iSegment = sqlite3OsSectorSize(pWal->pWalFd);
+    i64 iOffset = walFrameOffset(iFrame+1, szPage);
+
+    assert( isCommit );
+    assert( iSegment>0 );
+
+    iSegment = (((iOffset+iSegment-1)/iSegment) * iSegment);
+    while( iOffset<iSegment ){
+      void *pData;
+#if defined(SQLITE_HAS_CODEC)
+      if( (pData = sqlite3PagerCodec(pLast))==0 ) return SQLITE_NOMEM;
+#else
+      pData = pLast->pData;
+#endif
+      walEncodeFrame(pWal, pLast->pgno, nTruncate, pData, aFrame);
+      /* testcase( IS_BIG_INT(iOffset) ); // requires a 4GiB WAL */
+      rc = sqlite3OsWrite(pWal->pWalFd, aFrame, sizeof(aFrame), iOffset);
+      if( rc!=SQLITE_OK ){
+        return rc;
+      }
+      iOffset += WAL_FRAME_HDRSIZE;
+      rc = sqlite3OsWrite(pWal->pWalFd, pData, szPage, iOffset); 
+      if( rc!=SQLITE_OK ){
+        return rc;
+      }
+      nLast++;
+      iOffset += szPage;
+    }
+
+    rc = sqlite3OsSync(pWal->pWalFd, sync_flags);
+  }
+
+  /* Append data to the wal-index. It is not necessary to lock the 
+  ** wal-index to do this as the SQLITE_SHM_WRITE lock held on the wal-index
+  ** guarantees that there are no other writers, and no data that may
+  ** be in use by existing readers is being overwritten.
+  */
+  iFrame = pWal->hdr.mxFrame;
+  for(p=pList; p && rc==SQLITE_OK; p=p->pDirty){
+    iFrame++;
+    rc = walIndexAppend(pWal, iFrame, p->pgno);
+  }
+  while( nLast>0 && rc==SQLITE_OK ){
+    iFrame++;
+    nLast--;
+    rc = walIndexAppend(pWal, iFrame, pLast->pgno);
+  }
+
+  if( rc==SQLITE_OK ){
+    /* Update the private copy of the header. */
+    pWal->hdr.szPage = (u16)((szPage&0xff00) | (szPage>>16));
+    testcase( szPage<=32768 );
+    testcase( szPage>=65536 );
+    pWal->hdr.mxFrame = iFrame;
+    if( isCommit ){
+      pWal->hdr.iChange++;
+      pWal->hdr.nPage = nTruncate;
+    }
+    /* If this is a commit, update the wal-index header too. */
+    if( isCommit ){
+      walIndexWriteHdr(pWal);
+      pWal->iCallback = iFrame;
+    }
+  }
+
+  WALTRACE(("WAL%p: frame write %s\n", pWal, rc ? "failed" : "ok"));
+  return rc;
+}
+
+/* 
+** This routine is called to implement sqlite3_wal_checkpoint() and
+** related interfaces.
+**
+** Obtain a CHECKPOINT lock and then backfill as much information as
+** we can from WAL into the database.
+**
+** If parameter xBusy is not NULL, it is a pointer to a busy-handler
+** callback. In this case this function runs a blocking checkpoint.
+*/
+SQLITE_PRIVATE int sqlite3WalCheckpoint(
+  Wal *pWal,                      /* Wal connection */
+  int eMode,                      /* PASSIVE, FULL or RESTART */
+  int (*xBusy)(void*),            /* Function to call when busy */
+  void *pBusyArg,                 /* Context argument for xBusyHandler */
+  int sync_flags,                 /* Flags to sync db file with (or 0) */
+  int nBuf,                       /* Size of temporary buffer */
+  u8 *zBuf,                       /* Temporary buffer to use */
+  int *pnLog,                     /* OUT: Number of frames in WAL */
+  int *pnCkpt                     /* OUT: Number of backfilled frames in WAL */
+){
+  int rc;                         /* Return code */
+  int isChanged = 0;              /* True if a new wal-index header is loaded */
+  int eMode2 = eMode;             /* Mode to pass to walCheckpoint() */
+
+  assert( pWal->ckptLock==0 );
+  assert( pWal->writeLock==0 );
+
+  WALTRACE(("WAL%p: checkpoint begins\n", pWal));
+  rc = walLockExclusive(pWal, WAL_CKPT_LOCK, 1);
+  if( rc ){
+    /* Usually this is SQLITE_BUSY meaning that another thread or process
+    ** is already running a checkpoint, or maybe a recovery.  But it might
+    ** also be SQLITE_IOERR. */
+    return rc;
+  }
+  pWal->ckptLock = 1;
+
+  /* If this is a blocking-checkpoint, then obtain the write-lock as well
+  ** to prevent any writers from running while the checkpoint is underway.
+  ** This has to be done before the call to walIndexReadHdr() below.
+  **
+  ** If the writer lock cannot be obtained, then a passive checkpoint is
+  ** run instead. Since the checkpointer is not holding the writer lock,
+  ** there is no point in blocking waiting for any readers. Assuming no 
+  ** other error occurs, this function will return SQLITE_BUSY to the caller.
+  */
+  if( eMode!=SQLITE_CHECKPOINT_PASSIVE ){
+    rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_WRITE_LOCK, 1);
+    if( rc==SQLITE_OK ){
+      pWal->writeLock = 1;
+    }else if( rc==SQLITE_BUSY ){
+      eMode2 = SQLITE_CHECKPOINT_PASSIVE;
+      rc = SQLITE_OK;
+    }
+  }
+
+  /* Read the wal-index header. */
+  if( rc==SQLITE_OK ){
+    rc = walIndexReadHdr(pWal, &isChanged);
+  }
+
+  /* Copy data from the log to the database file. */
+  if( rc==SQLITE_OK ){
+    if( pWal->hdr.mxFrame && walPagesize(pWal)!=nBuf ){
+      rc = SQLITE_CORRUPT_BKPT;
+    }else{
+      rc = walCheckpoint(pWal, eMode2, xBusy, pBusyArg, sync_flags, zBuf);
+    }
+
+    /* If no error occurred, set the output variables. */
+    if( rc==SQLITE_OK || rc==SQLITE_BUSY ){
+      if( pnLog ) *pnLog = (int)pWal->hdr.mxFrame;
+      if( pnCkpt ) *pnCkpt = (int)(walCkptInfo(pWal)->nBackfill);
+    }
+  }
+
+  if( isChanged ){
+    /* If a new wal-index header was loaded before the checkpoint was 
+    ** performed, then the pager-cache associated with pWal is now
+    ** out of date. So zero the cached wal-index header to ensure that
+    ** next time the pager opens a snapshot on this database it knows that
+    ** the cache needs to be reset.
+    */
+    memset(&pWal->hdr, 0, sizeof(WalIndexHdr));
+  }
+
+  /* Release the locks. */
+  sqlite3WalEndWriteTransaction(pWal);
+  walUnlockExclusive(pWal, WAL_CKPT_LOCK, 1);
+  pWal->ckptLock = 0;
+  WALTRACE(("WAL%p: checkpoint %s\n", pWal, rc ? "failed" : "ok"));
+  return (rc==SQLITE_OK && eMode!=eMode2 ? SQLITE_BUSY : rc);
+}
+
+/* Return the value to pass to a sqlite3_wal_hook callback, the
+** number of frames in the WAL at the point of the last commit since
+** sqlite3WalCallback() was called.  If no commits have occurred since
+** the last call, then return 0.
+*/
+SQLITE_PRIVATE int sqlite3WalCallback(Wal *pWal){
+  u32 ret = 0;
+  if( pWal ){
+    ret = pWal->iCallback;
+    pWal->iCallback = 0;
+  }
+  return (int)ret;
+}
+
+/*
+** This function is called to change the WAL subsystem into or out
+** of locking_mode=EXCLUSIVE.
+**
+** If op is zero, then attempt to change from locking_mode=EXCLUSIVE
+** into locking_mode=NORMAL.  This means that we must acquire a lock
+** on the pWal->readLock byte.  If the WAL is already in locking_mode=NORMAL
+** or if the acquisition of the lock fails, then return 0.  If the
+** transition out of exclusive-mode is successful, return 1.  This
+** operation must occur while the pager is still holding the exclusive
+** lock on the main database file.
+**
+** If op is one, then change from locking_mode=NORMAL into 
+** locking_mode=EXCLUSIVE.  This means that the pWal->readLock must
+** be released.  Return 1 if the transition is made and 0 if the
+** WAL is already in exclusive-locking mode - meaning that this
+** routine is a no-op.  The pager must already hold the exclusive lock
+** on the main database file before invoking this operation.
+**
+** If op is negative, then do a dry-run of the op==1 case but do
+** not actually change anything. The pager uses this to see if it
+** should acquire the database exclusive lock prior to invoking
+** the op==1 case.
+*/
+SQLITE_PRIVATE int sqlite3WalExclusiveMode(Wal *pWal, int op){
+  int rc;
+  assert( pWal->writeLock==0 );
+  assert( pWal->exclusiveMode!=WAL_HEAPMEMORY_MODE || op==-1 );
+
+  /* pWal->readLock is usually set, but might be -1 if there was a 
+  ** prior error while attempting to acquire are read-lock. This cannot 
+  ** happen if the connection is actually in exclusive mode (as no xShmLock
+  ** locks are taken in this case). Nor should the pager attempt to
+  ** upgrade to exclusive-mode following such an error.
+  */
+  assert( pWal->readLock>=0 || pWal->lockError );
+  assert( pWal->readLock>=0 || (op<=0 && pWal->exclusiveMode==0) );
+
+  if( op==0 ){
+    if( pWal->exclusiveMode ){
+      pWal->exclusiveMode = 0;
+      if( walLockShared(pWal, WAL_READ_LOCK(pWal->readLock))!=SQLITE_OK ){
+        pWal->exclusiveMode = 1;
+      }
+      rc = pWal->exclusiveMode==0;
+    }else{
+      /* Already in locking_mode=NORMAL */
+      rc = 0;
+    }
+  }else if( op>0 ){
+    assert( pWal->exclusiveMode==0 );
+    assert( pWal->readLock>=0 );
+    walUnlockShared(pWal, WAL_READ_LOCK(pWal->readLock));
+    pWal->exclusiveMode = 1;
+    rc = 1;
+  }else{
+    rc = pWal->exclusiveMode==0;
+  }
+  return rc;
+}
+
+/* 
+** Return true if the argument is non-NULL and the WAL module is using
+** heap-memory for the wal-index. Otherwise, if the argument is NULL or the
+** WAL module is using shared-memory, return false. 
+*/
+SQLITE_PRIVATE int sqlite3WalHeapMemory(Wal *pWal){
+  return (pWal && pWal->exclusiveMode==WAL_HEAPMEMORY_MODE );
+}
+
+#endif /* #ifndef SQLITE_OMIT_WAL */
+
+/************** End of wal.c *************************************************/
+/************** Begin file btmutex.c *****************************************/
+/*
+** 2007 August 27
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains code used to implement mutexes on Btree objects.
+** This code really belongs in btree.c.  But btree.c is getting too
+** big and we want to break it down some.  This packaged seemed like
+** a good breakout.
+*/
+/************** Include btreeInt.h in the middle of btmutex.c ****************/
+/************** Begin file btreeInt.h ****************************************/
+/*
+** 2004 April 6
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file implements a external (disk-based) database using BTrees.
+** For a detailed discussion of BTrees, refer to
+**
+**     Donald E. Knuth, THE ART OF COMPUTER PROGRAMMING, Volume 3:
+**     "Sorting And Searching", pages 473-480. Addison-Wesley
+**     Publishing Company, Reading, Massachusetts.
+**
+** The basic idea is that each page of the file contains N database
+** entries and N+1 pointers to subpages.
+**
+**   ----------------------------------------------------------------
+**   |  Ptr(0) | Key(0) | Ptr(1) | Key(1) | ... | Key(N-1) | Ptr(N) |
+**   ----------------------------------------------------------------
+**
+** All of the keys on the page that Ptr(0) points to have values less
+** than Key(0).  All of the keys on page Ptr(1) and its subpages have
+** values greater than Key(0) and less than Key(1).  All of the keys
+** on Ptr(N) and its subpages have values greater than Key(N-1).  And
+** so forth.
+**
+** Finding a particular key requires reading O(log(M)) pages from the 
+** disk where M is the number of entries in the tree.
+**
+** In this implementation, a single file can hold one or more separate 
+** BTrees.  Each BTree is identified by the index of its root page.  The
+** key and data for any entry are combined to form the "payload".  A
+** fixed amount of payload can be carried directly on the database
+** page.  If the payload is larger than the preset amount then surplus
+** bytes are stored on overflow pages.  The payload for an entry
+** and the preceding pointer are combined to form a "Cell".  Each 
+** page has a small header which contains the Ptr(N) pointer and other
+** information such as the size of key and data.
+**
+** FORMAT DETAILS
+**
+** The file is divided into pages.  The first page is called page 1,
+** the second is page 2, and so forth.  A page number of zero indicates
+** "no such page".  The page size can be any power of 2 between 512 and 65536.
+** Each page can be either a btree page, a freelist page, an overflow
+** page, or a pointer-map page.
+**
+** The first page is always a btree page.  The first 100 bytes of the first
+** page contain a special header (the "file header") that describes the file.
+** The format of the file header is as follows:
+**
+**   OFFSET   SIZE    DESCRIPTION
+**      0      16     Header string: "SQLite format 3\000"
+**     16       2     Page size in bytes.  
+**     18       1     File format write version
+**     19       1     File format read version
+**     20       1     Bytes of unused space at the end of each page
+**     21       1     Max embedded payload fraction
+**     22       1     Min embedded payload fraction
+**     23       1     Min leaf payload fraction
+**     24       4     File change counter
+**     28       4     Reserved for future use
+**     32       4     First freelist page
+**     36       4     Number of freelist pages in the file
+**     40      60     15 4-byte meta values passed to higher layers
+**
+**     40       4     Schema cookie
+**     44       4     File format of schema layer
+**     48       4     Size of page cache
+**     52       4     Largest root-page (auto/incr_vacuum)
+**     56       4     1=UTF-8 2=UTF16le 3=UTF16be
+**     60       4     User version
+**     64       4     Incremental vacuum mode
+**     68       4     unused
+**     72       4     unused
+**     76       4     unused
+**
+** All of the integer values are big-endian (most significant byte first).
+**
+** The file change counter is incremented when the database is changed
+** This counter allows other processes to know when the file has changed
+** and thus when they need to flush their cache.
+**
+** The max embedded payload fraction is the amount of the total usable
+** space in a page that can be consumed by a single cell for standard
+** B-tree (non-LEAFDATA) tables.  A value of 255 means 100%.  The default
+** is to limit the maximum cell size so that at least 4 cells will fit
+** on one page.  Thus the default max embedded payload fraction is 64.
+**
+** If the payload for a cell is larger than the max payload, then extra
+** payload is spilled to overflow pages.  Once an overflow page is allocated,
+** as many bytes as possible are moved into the overflow pages without letting
+** the cell size drop below the min embedded payload fraction.
+**
+** The min leaf payload fraction is like the min embedded payload fraction
+** except that it applies to leaf nodes in a LEAFDATA tree.  The maximum
+** payload fraction for a LEAFDATA tree is always 100% (or 255) and it
+** not specified in the header.
+**
+** Each btree pages is divided into three sections:  The header, the
+** cell pointer array, and the cell content area.  Page 1 also has a 100-byte
+** file header that occurs before the page header.
+**
+**      |----------------|
+**      | file header    |   100 bytes.  Page 1 only.
+**      |----------------|
+**      | page header    |   8 bytes for leaves.  12 bytes for interior nodes
+**      |----------------|
+**      | cell pointer   |   |  2 bytes per cell.  Sorted order.
+**      | array          |   |  Grows downward
+**      |                |   v
+**      |----------------|
+**      | unallocated    |
+**      | space          |
+**      |----------------|   ^  Grows upwards
+**      | cell content   |   |  Arbitrary order interspersed with freeblocks.
+**      | area           |   |  and free space fragments.
+**      |----------------|
+**
+** The page headers looks like this:
+**
+**   OFFSET   SIZE     DESCRIPTION
+**      0       1      Flags. 1: intkey, 2: zerodata, 4: leafdata, 8: leaf
+**      1       2      byte offset to the first freeblock
+**      3       2      number of cells on this page
+**      5       2      first byte of the cell content area
+**      7       1      number of fragmented free bytes
+**      8       4      Right child (the Ptr(N) value).  Omitted on leaves.
+**
+** The flags define the format of this btree page.  The leaf flag means that
+** this page has no children.  The zerodata flag means that this page carries
+** only keys and no data.  The intkey flag means that the key is a integer
+** which is stored in the key size entry of the cell header rather than in
+** the payload area.
+**
+** The cell pointer array begins on the first byte after the page header.
+** The cell pointer array contains zero or more 2-byte numbers which are
+** offsets from the beginning of the page to the cell content in the cell
+** content area.  The cell pointers occur in sorted order.  The system strives
+** to keep free space after the last cell pointer so that new cells can
+** be easily added without having to defragment the page.
+**
+** Cell content is stored at the very end of the page and grows toward the
+** beginning of the page.
+**
+** Unused space within the cell content area is collected into a linked list of
+** freeblocks.  Each freeblock is at least 4 bytes in size.  The byte offset
+** to the first freeblock is given in the header.  Freeblocks occur in
+** increasing order.  Because a freeblock must be at least 4 bytes in size,
+** any group of 3 or fewer unused bytes in the cell content area cannot
+** exist on the freeblock chain.  A group of 3 or fewer free bytes is called
+** a fragment.  The total number of bytes in all fragments is recorded.
+** in the page header at offset 7.
+**
+**    SIZE    DESCRIPTION
+**      2     Byte offset of the next freeblock
+**      2     Bytes in this freeblock
+**
+** Cells are of variable length.  Cells are stored in the cell content area at
+** the end of the page.  Pointers to the cells are in the cell pointer array
+** that immediately follows the page header.  Cells is not necessarily
+** contiguous or in order, but cell pointers are contiguous and in order.
+**
+** Cell content makes use of variable length integers.  A variable
+** length integer is 1 to 9 bytes where the lower 7 bits of each 
+** byte are used.  The integer consists of all bytes that have bit 8 set and
+** the first byte with bit 8 clear.  The most significant byte of the integer
+** appears first.  A variable-length integer may not be more than 9 bytes long.
+** As a special case, all 8 bytes of the 9th byte are used as data.  This
+** allows a 64-bit integer to be encoded in 9 bytes.
+**
+**    0x00                      becomes  0x00000000
+**    0x7f                      becomes  0x0000007f
+**    0x81 0x00                 becomes  0x00000080
+**    0x82 0x00                 becomes  0x00000100
+**    0x80 0x7f                 becomes  0x0000007f
+**    0x8a 0x91 0xd1 0xac 0x78  becomes  0x12345678
+**    0x81 0x81 0x81 0x81 0x01  becomes  0x10204081
+**
+** Variable length integers are used for rowids and to hold the number of
+** bytes of key and data in a btree cell.
+**
+** The content of a cell looks like this:
+**
+**    SIZE    DESCRIPTION
+**      4     Page number of the left child. Omitted if leaf flag is set.
+**     var    Number of bytes of data. Omitted if the zerodata flag is set.
+**     var    Number of bytes of key. Or the key itself if intkey flag is set.
+**      *     Payload
+**      4     First page of the overflow chain.  Omitted if no overflow
+**
+** Overflow pages form a linked list.  Each page except the last is completely
+** filled with data (pagesize - 4 bytes).  The last page can have as little
+** as 1 byte of data.
+**
+**    SIZE    DESCRIPTION
+**      4     Page number of next overflow page
+**      *     Data
+**
+** Freelist pages come in two subtypes: trunk pages and leaf pages.  The
+** file header points to the first in a linked list of trunk page.  Each trunk
+** page points to multiple leaf pages.  The content of a leaf page is
+** unspecified.  A trunk page looks like this:
+**
+**    SIZE    DESCRIPTION
+**      4     Page number of next trunk page
+**      4     Number of leaf pointers on this page
+**      *     zero or more pages numbers of leaves
+*/
+
+
+/* The following value is the maximum cell size assuming a maximum page
+** size give above.
+*/
+#define MX_CELL_SIZE(pBt)  ((int)(pBt->pageSize-8))
+
+/* The maximum number of cells on a single page of the database.  This
+** assumes a minimum cell size of 6 bytes  (4 bytes for the cell itself
+** plus 2 bytes for the index to the cell in the page header).  Such
+** small cells will be rare, but they are possible.
+*/
+#define MX_CELL(pBt) ((pBt->pageSize-8)/6)
+
+/* Forward declarations */
+typedef struct MemPage MemPage;
+typedef struct BtLock BtLock;
+
+/*
+** This is a magic string that appears at the beginning of every
+** SQLite database in order to identify the file as a real database.
+**
+** You can change this value at compile-time by specifying a
+** -DSQLITE_FILE_HEADER="..." on the compiler command-line.  The
+** header must be exactly 16 bytes including the zero-terminator so
+** the string itself should be 15 characters long.  If you change
+** the header, then your custom library will not be able to read 
+** databases generated by the standard tools and the standard tools
+** will not be able to read databases created by your custom library.
+*/
+#ifndef SQLITE_FILE_HEADER /* 123456789 123456 */
+#  define SQLITE_FILE_HEADER "SQLite format 3"
+#endif
+
+/*
+** Page type flags.  An ORed combination of these flags appear as the
+** first byte of on-disk image of every BTree page.
+*/
+#define PTF_INTKEY    0x01
+#define PTF_ZERODATA  0x02
+#define PTF_LEAFDATA  0x04
+#define PTF_LEAF      0x08
+
+/*
+** As each page of the file is loaded into memory, an instance of the following
+** structure is appended and initialized to zero.  This structure stores
+** information about the page that is decoded from the raw file page.
+**
+** The pParent field points back to the parent page.  This allows us to
+** walk up the BTree from any leaf to the root.  Care must be taken to
+** unref() the parent page pointer when this page is no longer referenced.
+** The pageDestructor() routine handles that chore.
+**
+** Access to all fields of this structure is controlled by the mutex
+** stored in MemPage.pBt->mutex.
+*/
+struct MemPage {
+  u8 isInit;           /* True if previously initialized. MUST BE FIRST! */
+  u8 nOverflow;        /* Number of overflow cell bodies in aCell[] */
+  u8 intKey;           /* True if intkey flag is set */
+  u8 leaf;             /* True if leaf flag is set */
+  u8 hasData;          /* True if this page stores data */
+  u8 hdrOffset;        /* 100 for page 1.  0 otherwise */
+  u8 childPtrSize;     /* 0 if leaf==1.  4 if leaf==0 */
+  u16 maxLocal;        /* Copy of BtShared.maxLocal or BtShared.maxLeaf */
+  u16 minLocal;        /* Copy of BtShared.minLocal or BtShared.minLeaf */
+  u16 cellOffset;      /* Index in aData of first cell pointer */
+  u16 nFree;           /* Number of free bytes on the page */
+  u16 nCell;           /* Number of cells on this page, local and ovfl */
+  u16 maskPage;        /* Mask for page offset */
+  struct _OvflCell {   /* Cells that will not fit on aData[] */
+    u8 *pCell;          /* Pointers to the body of the overflow cell */
+    u16 idx;            /* Insert this cell before idx-th non-overflow cell */
+  } aOvfl[5];
+  BtShared *pBt;       /* Pointer to BtShared that this page is part of */
+  u8 *aData;           /* Pointer to disk image of the page data */
+  DbPage *pDbPage;     /* Pager page handle */
+  Pgno pgno;           /* Page number for this page */
+};
+
+/*
+** The in-memory image of a disk page has the auxiliary information appended
+** to the end.  EXTRA_SIZE is the number of bytes of space needed to hold
+** that extra information.
+*/
+#define EXTRA_SIZE sizeof(MemPage)
+
+/*
+** A linked list of the following structures is stored at BtShared.pLock.
+** Locks are added (or upgraded from READ_LOCK to WRITE_LOCK) when a cursor 
+** is opened on the table with root page BtShared.iTable. Locks are removed
+** from this list when a transaction is committed or rolled back, or when
+** a btree handle is closed.
+*/
+struct BtLock {
+  Btree *pBtree;        /* Btree handle holding this lock */
+  Pgno iTable;          /* Root page of table */
+  u8 eLock;             /* READ_LOCK or WRITE_LOCK */
+  BtLock *pNext;        /* Next in BtShared.pLock list */
+};
+
+/* Candidate values for BtLock.eLock */
+#define READ_LOCK     1
+#define WRITE_LOCK    2
+
+/* A Btree handle
+**
+** A database connection contains a pointer to an instance of
+** this object for every database file that it has open.  This structure
+** is opaque to the database connection.  The database connection cannot
+** see the internals of this structure and only deals with pointers to
+** this structure.
+**
+** For some database files, the same underlying database cache might be 
+** shared between multiple connections.  In that case, each connection
+** has it own instance of this object.  But each instance of this object
+** points to the same BtShared object.  The database cache and the
+** schema associated with the database file are all contained within
+** the BtShared object.
+**
+** All fields in this structure are accessed under sqlite3.mutex.
+** The pBt pointer itself may not be changed while there exists cursors 
+** in the referenced BtShared that point back to this Btree since those
+** cursors have to go through this Btree to find their BtShared and
+** they often do so without holding sqlite3.mutex.
+*/
+struct Btree {
+  sqlite3 *db;       /* The database connection holding this btree */
+  BtShared *pBt;     /* Sharable content of this btree */
+  u8 inTrans;        /* TRANS_NONE, TRANS_READ or TRANS_WRITE */
+  u8 sharable;       /* True if we can share pBt with another db */
+  u8 locked;         /* True if db currently has pBt locked */
+  int wantToLock;    /* Number of nested calls to sqlite3BtreeEnter() */
+  int nBackup;       /* Number of backup operations reading this btree */
+  Btree *pNext;      /* List of other sharable Btrees from the same db */
+  Btree *pPrev;      /* Back pointer of the same list */
+#ifndef SQLITE_OMIT_SHARED_CACHE
+  BtLock lock;       /* Object used to lock page 1 */
+#endif
+};
+
+/*
+** Btree.inTrans may take one of the following values.
+**
+** If the shared-data extension is enabled, there may be multiple users
+** of the Btree structure. At most one of these may open a write transaction,
+** but any number may have active read transactions.
+*/
+#define TRANS_NONE  0
+#define TRANS_READ  1
+#define TRANS_WRITE 2
+
+/*
+** An instance of this object represents a single database file.
+** 
+** A single database file can be in use as the same time by two
+** or more database connections.  When two or more connections are
+** sharing the same database file, each connection has it own
+** private Btree object for the file and each of those Btrees points
+** to this one BtShared object.  BtShared.nRef is the number of
+** connections currently sharing this database file.
+**
+** Fields in this structure are accessed under the BtShared.mutex
+** mutex, except for nRef and pNext which are accessed under the
+** global SQLITE_MUTEX_STATIC_MASTER mutex.  The pPager field
+** may not be modified once it is initially set as long as nRef>0.
+** The pSchema field may be set once under BtShared.mutex and
+** thereafter is unchanged as long as nRef>0.
+**
+** isPending:
+**
+**   If a BtShared client fails to obtain a write-lock on a database
+**   table (because there exists one or more read-locks on the table),
+**   the shared-cache enters 'pending-lock' state and isPending is
+**   set to true.
+**
+**   The shared-cache leaves the 'pending lock' state when either of
+**   the following occur:
+**
+**     1) The current writer (BtShared.pWriter) concludes its transaction, OR
+**     2) The number of locks held by other connections drops to zero.
+**
+**   while in the 'pending-lock' state, no connection may start a new
+**   transaction.
+**
+**   This feature is included to help prevent writer-starvation.
+*/
+struct BtShared {
+  Pager *pPager;        /* The page cache */
+  sqlite3 *db;          /* Database connection currently using this Btree */
+  BtCursor *pCursor;    /* A list of all open cursors */
+  MemPage *pPage1;      /* First page of the database */
+  u8 readOnly;          /* True if the underlying file is readonly */
+  u8 pageSizeFixed;     /* True if the page size can no longer be changed */
+  u8 secureDelete;      /* True if secure_delete is enabled */
+  u8 initiallyEmpty;    /* Database is empty at start of transaction */
+  u8 openFlags;         /* Flags to sqlite3BtreeOpen() */
+#ifndef SQLITE_OMIT_AUTOVACUUM
+  u8 autoVacuum;        /* True if auto-vacuum is enabled */
+  u8 incrVacuum;        /* True if incr-vacuum is enabled */
+#endif
+  u8 inTransaction;     /* Transaction state */
+  u8 doNotUseWAL;       /* If true, do not open write-ahead-log file */
+  u16 maxLocal;         /* Maximum local payload in non-LEAFDATA tables */
+  u16 minLocal;         /* Minimum local payload in non-LEAFDATA tables */
+  u16 maxLeaf;          /* Maximum local payload in a LEAFDATA table */
+  u16 minLeaf;          /* Minimum local payload in a LEAFDATA table */
+  u32 pageSize;         /* Total number of bytes on a page */
+  u32 usableSize;       /* Number of usable bytes on each page */
+  int nTransaction;     /* Number of open transactions (read + write) */
+  u32 nPage;            /* Number of pages in the database */
+  void *pSchema;        /* Pointer to space allocated by sqlite3BtreeSchema() */
+  void (*xFreeSchema)(void*);  /* Destructor for BtShared.pSchema */
+  sqlite3_mutex *mutex; /* Non-recursive mutex required to access this object */
+  Bitvec *pHasContent;  /* Set of pages moved to free-list this transaction */
+#ifndef SQLITE_OMIT_SHARED_CACHE
+  int nRef;             /* Number of references to this structure */
+  BtShared *pNext;      /* Next on a list of sharable BtShared structs */
+  BtLock *pLock;        /* List of locks held on this shared-btree struct */
+  Btree *pWriter;       /* Btree with currently open write transaction */
+  u8 isExclusive;       /* True if pWriter has an EXCLUSIVE lock on the db */
+  u8 isPending;         /* If waiting for read-locks to clear */
+#endif
+  u8 *pTmpSpace;        /* BtShared.pageSize bytes of space for tmp use */
+};
+
+/*
+** An instance of the following structure is used to hold information
+** about a cell.  The parseCellPtr() function fills in this structure
+** based on information extract from the raw disk page.
+*/
+typedef struct CellInfo CellInfo;
+struct CellInfo {
+  i64 nKey;      /* The key for INTKEY tables, or number of bytes in key */
+  u8 *pCell;     /* Pointer to the start of cell content */
+  u32 nData;     /* Number of bytes of data */
+  u32 nPayload;  /* Total amount of payload */
+  u16 nHeader;   /* Size of the cell content header in bytes */
+  u16 nLocal;    /* Amount of payload held locally */
+  u16 iOverflow; /* Offset to overflow page number.  Zero if no overflow */
+  u16 nSize;     /* Size of the cell content on the main b-tree page */
+};
+
+/*
+** Maximum depth of an SQLite B-Tree structure. Any B-Tree deeper than
+** this will be declared corrupt. This value is calculated based on a
+** maximum database size of 2^31 pages a minimum fanout of 2 for a
+** root-node and 3 for all other internal nodes.
+**
+** If a tree that appears to be taller than this is encountered, it is
+** assumed that the database is corrupt.
+*/
+#define BTCURSOR_MAX_DEPTH 20
+
+/*
+** A cursor is a pointer to a particular entry within a particular
+** b-tree within a database file.
+**
+** The entry is identified by its MemPage and the index in
+** MemPage.aCell[] of the entry.
+**
+** A single database file can shared by two more database connections,
+** but cursors cannot be shared.  Each cursor is associated with a
+** particular database connection identified BtCursor.pBtree.db.
+**
+** Fields in this structure are accessed under the BtShared.mutex
+** found at self->pBt->mutex. 
+*/
+struct BtCursor {
+  Btree *pBtree;            /* The Btree to which this cursor belongs */
+  BtShared *pBt;            /* The BtShared this cursor points to */
+  BtCursor *pNext, *pPrev;  /* Forms a linked list of all cursors */
+  struct KeyInfo *pKeyInfo; /* Argument passed to comparison function */
+  Pgno pgnoRoot;            /* The root page of this tree */
+  sqlite3_int64 cachedRowid; /* Next rowid cache.  0 means not valid */
+  CellInfo info;            /* A parse of the cell we are pointing at */
+  i64 nKey;        /* Size of pKey, or last integer key */
+  void *pKey;      /* Saved key that was cursor's last known position */
+  int skipNext;    /* Prev() is noop if negative. Next() is noop if positive */
+  u8 wrFlag;                /* True if writable */
+  u8 atLast;                /* Cursor pointing to the last entry */
+  u8 validNKey;             /* True if info.nKey is valid */
+  u8 eState;                /* One of the CURSOR_XXX constants (see below) */
+#ifndef SQLITE_OMIT_INCRBLOB
+  Pgno *aOverflow;          /* Cache of overflow page locations */
+  u8 isIncrblobHandle;      /* True if this cursor is an incr. io handle */
+#endif
+  i16 iPage;                            /* Index of current page in apPage */
+  u16 aiIdx[BTCURSOR_MAX_DEPTH];        /* Current index in apPage[i] */
+  MemPage *apPage[BTCURSOR_MAX_DEPTH];  /* Pages from root to current page */
+};
+
+/*
+** Potential values for BtCursor.eState.
+**
+** CURSOR_VALID:
+**   Cursor points to a valid entry. getPayload() etc. may be called.
+**
+** CURSOR_INVALID:
+**   Cursor does not point to a valid entry. This can happen (for example) 
+**   because the table is empty or because BtreeCursorFirst() has not been
+**   called.
+**
+** CURSOR_REQUIRESEEK:
+**   The table that this cursor was opened on still exists, but has been 
+**   modified since the cursor was last used. The cursor position is saved
+**   in variables BtCursor.pKey and BtCursor.nKey. When a cursor is in 
+**   this state, restoreCursorPosition() can be called to attempt to
+**   seek the cursor to the saved position.
+**
+** CURSOR_FAULT:
+**   A unrecoverable error (an I/O error or a malloc failure) has occurred
+**   on a different connection that shares the BtShared cache with this
+**   cursor.  The error has left the cache in an inconsistent state.
+**   Do nothing else with this cursor.  Any attempt to use the cursor
+**   should return the error code stored in BtCursor.skip
+*/
+#define CURSOR_INVALID           0
+#define CURSOR_VALID             1
+#define CURSOR_REQUIRESEEK       2
+#define CURSOR_FAULT             3
+
+/* 
+** The database page the PENDING_BYTE occupies. This page is never used.
+*/
+# define PENDING_BYTE_PAGE(pBt) PAGER_MJ_PGNO(pBt)
+
+/*
+** These macros define the location of the pointer-map entry for a 
+** database page. The first argument to each is the number of usable
+** bytes on each page of the database (often 1024). The second is the
+** page number to look up in the pointer map.
+**
+** PTRMAP_PAGENO returns the database page number of the pointer-map
+** page that stores the required pointer. PTRMAP_PTROFFSET returns
+** the offset of the requested map entry.
+**
+** If the pgno argument passed to PTRMAP_PAGENO is a pointer-map page,
+** then pgno is returned. So (pgno==PTRMAP_PAGENO(pgsz, pgno)) can be
+** used to test if pgno is a pointer-map page. PTRMAP_ISPAGE implements
+** this test.
+*/
+#define PTRMAP_PAGENO(pBt, pgno) ptrmapPageno(pBt, pgno)
+#define PTRMAP_PTROFFSET(pgptrmap, pgno) (5*(pgno-pgptrmap-1))
+#define PTRMAP_ISPAGE(pBt, pgno) (PTRMAP_PAGENO((pBt),(pgno))==(pgno))
+
+/*
+** The pointer map is a lookup table that identifies the parent page for
+** each child page in the database file.  The parent page is the page that
+** contains a pointer to the child.  Every page in the database contains
+** 0 or 1 parent pages.  (In this context 'database page' refers
+** to any page that is not part of the pointer map itself.)  Each pointer map
+** entry consists of a single byte 'type' and a 4 byte parent page number.
+** The PTRMAP_XXX identifiers below are the valid types.
+**
+** The purpose of the pointer map is to facility moving pages from one
+** position in the file to another as part of autovacuum.  When a page
+** is moved, the pointer in its parent must be updated to point to the
+** new location.  The pointer map is used to locate the parent page quickly.
+**
+** PTRMAP_ROOTPAGE: The database page is a root-page. The page-number is not
+**                  used in this case.
+**
+** PTRMAP_FREEPAGE: The database page is an unused (free) page. The page-number 
+**                  is not used in this case.
+**
+** PTRMAP_OVERFLOW1: The database page is the first page in a list of 
+**                   overflow pages. The page number identifies the page that
+**                   contains the cell with a pointer to this overflow page.
+**
+** PTRMAP_OVERFLOW2: The database page is the second or later page in a list of
+**                   overflow pages. The page-number identifies the previous
+**                   page in the overflow page list.
+**
+** PTRMAP_BTREE: The database page is a non-root btree page. The page number
+**               identifies the parent page in the btree.
+*/
+#define PTRMAP_ROOTPAGE 1
+#define PTRMAP_FREEPAGE 2
+#define PTRMAP_OVERFLOW1 3
+#define PTRMAP_OVERFLOW2 4
+#define PTRMAP_BTREE 5
+
+/* A bunch of assert() statements to check the transaction state variables
+** of handle p (type Btree*) are internally consistent.
+*/
+#define btreeIntegrity(p) \
+  assert( p->pBt->inTransaction!=TRANS_NONE || p->pBt->nTransaction==0 ); \
+  assert( p->pBt->inTransaction>=p->inTrans ); 
+
+
+/*
+** The ISAUTOVACUUM macro is used within balance_nonroot() to determine
+** if the database supports auto-vacuum or not. Because it is used
+** within an expression that is an argument to another macro 
+** (sqliteMallocRaw), it is not possible to use conditional compilation.
+** So, this macro is defined instead.
+*/
+#ifndef SQLITE_OMIT_AUTOVACUUM
+#define ISAUTOVACUUM (pBt->autoVacuum)
+#else
+#define ISAUTOVACUUM 0
+#endif
+
+
+/*
+** This structure is passed around through all the sanity checking routines
+** in order to keep track of some global state information.
+*/
+typedef struct IntegrityCk IntegrityCk;
+struct IntegrityCk {
+  BtShared *pBt;    /* The tree being checked out */
+  Pager *pPager;    /* The associated pager.  Also accessible by pBt->pPager */
+  Pgno nPage;       /* Number of pages in the database */
+  int *anRef;       /* Number of times each page is referenced */
+  int mxErr;        /* Stop accumulating errors when this reaches zero */
+  int nErr;         /* Number of messages written to zErrMsg so far */
+  int mallocFailed; /* A memory allocation error has occurred */
+  StrAccum errMsg;  /* Accumulate the error message text here */
+};
+
+/*
+** Read or write a two- and four-byte big-endian integer values.
+*/
+#define get2byte(x)   ((x)[0]<<8 | (x)[1])
+#define put2byte(p,v) ((p)[0] = (u8)((v)>>8), (p)[1] = (u8)(v))
+#define get4byte sqlite3Get4byte
+#define put4byte sqlite3Put4byte
+
+/************** End of btreeInt.h ********************************************/
+/************** Continuing where we left off in btmutex.c ********************/
+#ifndef SQLITE_OMIT_SHARED_CACHE
+#if SQLITE_THREADSAFE
+
+/*
+** Obtain the BtShared mutex associated with B-Tree handle p. Also,
+** set BtShared.db to the database handle associated with p and the
+** p->locked boolean to true.
+*/
+static void lockBtreeMutex(Btree *p){
+  assert( p->locked==0 );
+  assert( sqlite3_mutex_notheld(p->pBt->mutex) );
+  assert( sqlite3_mutex_held(p->db->mutex) );
+
+  sqlite3_mutex_enter(p->pBt->mutex);
+  p->pBt->db = p->db;
+  p->locked = 1;
+}
+
+/*
+** Release the BtShared mutex associated with B-Tree handle p and
+** clear the p->locked boolean.
+*/
+static void unlockBtreeMutex(Btree *p){
+  BtShared *pBt = p->pBt;
+  assert( p->locked==1 );
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  assert( sqlite3_mutex_held(p->db->mutex) );
+  assert( p->db==pBt->db );
+
+  sqlite3_mutex_leave(pBt->mutex);
+  p->locked = 0;
+}
+
+/*
+** Enter a mutex on the given BTree object.
+**
+** If the object is not sharable, then no mutex is ever required
+** and this routine is a no-op.  The underlying mutex is non-recursive.
+** But we keep a reference count in Btree.wantToLock so the behavior
+** of this interface is recursive.
+**
+** To avoid deadlocks, multiple Btrees are locked in the same order
+** by all database connections.  The p->pNext is a list of other
+** Btrees belonging to the same database connection as the p Btree
+** which need to be locked after p.  If we cannot get a lock on
+** p, then first unlock all of the others on p->pNext, then wait
+** for the lock to become available on p, then relock all of the
+** subsequent Btrees that desire a lock.
+*/
+SQLITE_PRIVATE void sqlite3BtreeEnter(Btree *p){
+  Btree *pLater;
+
+  /* Some basic sanity checking on the Btree.  The list of Btrees
+  ** connected by pNext and pPrev should be in sorted order by
+  ** Btree.pBt value. All elements of the list should belong to
+  ** the same connection. Only shared Btrees are on the list. */
+  assert( p->pNext==0 || p->pNext->pBt>p->pBt );
+  assert( p->pPrev==0 || p->pPrev->pBt<p->pBt );
+  assert( p->pNext==0 || p->pNext->db==p->db );
+  assert( p->pPrev==0 || p->pPrev->db==p->db );
+  assert( p->sharable || (p->pNext==0 && p->pPrev==0) );
+
+  /* Check for locking consistency */
+  assert( !p->locked || p->wantToLock>0 );
+  assert( p->sharable || p->wantToLock==0 );
+
+  /* We should already hold a lock on the database connection */
+  assert( sqlite3_mutex_held(p->db->mutex) );
+
+  /* Unless the database is sharable and unlocked, then BtShared.db
+  ** should already be set correctly. */
+  assert( (p->locked==0 && p->sharable) || p->pBt->db==p->db );
+
+  if( !p->sharable ) return;
+  p->wantToLock++;
+  if( p->locked ) return;
+
+  /* In most cases, we should be able to acquire the lock we
+  ** want without having to go throught the ascending lock
+  ** procedure that follows.  Just be sure not to block.
+  */
+  if( sqlite3_mutex_try(p->pBt->mutex)==SQLITE_OK ){
+    p->pBt->db = p->db;
+    p->locked = 1;
+    return;
+  }
+
+  /* To avoid deadlock, first release all locks with a larger
+  ** BtShared address.  Then acquire our lock.  Then reacquire
+  ** the other BtShared locks that we used to hold in ascending
+  ** order.
+  */
+  for(pLater=p->pNext; pLater; pLater=pLater->pNext){
+    assert( pLater->sharable );
+    assert( pLater->pNext==0 || pLater->pNext->pBt>pLater->pBt );
+    assert( !pLater->locked || pLater->wantToLock>0 );
+    if( pLater->locked ){
+      unlockBtreeMutex(pLater);
+    }
+  }
+  lockBtreeMutex(p);
+  for(pLater=p->pNext; pLater; pLater=pLater->pNext){
+    if( pLater->wantToLock ){
+      lockBtreeMutex(pLater);
+    }
+  }
+}
+
+/*
+** Exit the recursive mutex on a Btree.
+*/
+SQLITE_PRIVATE void sqlite3BtreeLeave(Btree *p){
+  if( p->sharable ){
+    assert( p->wantToLock>0 );
+    p->wantToLock--;
+    if( p->wantToLock==0 ){
+      unlockBtreeMutex(p);
+    }
+  }
+}
+
+#ifndef NDEBUG
+/*
+** Return true if the BtShared mutex is held on the btree, or if the
+** B-Tree is not marked as sharable.
+**
+** This routine is used only from within assert() statements.
+*/
+SQLITE_PRIVATE int sqlite3BtreeHoldsMutex(Btree *p){
+  assert( p->sharable==0 || p->locked==0 || p->wantToLock>0 );
+  assert( p->sharable==0 || p->locked==0 || p->db==p->pBt->db );
+  assert( p->sharable==0 || p->locked==0 || sqlite3_mutex_held(p->pBt->mutex) );
+  assert( p->sharable==0 || p->locked==0 || sqlite3_mutex_held(p->db->mutex) );
+
+  return (p->sharable==0 || p->locked);
+}
+#endif
+
+
+#ifndef SQLITE_OMIT_INCRBLOB
+/*
+** Enter and leave a mutex on a Btree given a cursor owned by that
+** Btree.  These entry points are used by incremental I/O and can be
+** omitted if that module is not used.
+*/
+SQLITE_PRIVATE void sqlite3BtreeEnterCursor(BtCursor *pCur){
+  sqlite3BtreeEnter(pCur->pBtree);
+}
+SQLITE_PRIVATE void sqlite3BtreeLeaveCursor(BtCursor *pCur){
+  sqlite3BtreeLeave(pCur->pBtree);
+}
+#endif /* SQLITE_OMIT_INCRBLOB */
+
+
+/*
+** Enter the mutex on every Btree associated with a database
+** connection.  This is needed (for example) prior to parsing
+** a statement since we will be comparing table and column names
+** against all schemas and we do not want those schemas being
+** reset out from under us.
+**
+** There is a corresponding leave-all procedures.
+**
+** Enter the mutexes in accending order by BtShared pointer address
+** to avoid the possibility of deadlock when two threads with
+** two or more btrees in common both try to lock all their btrees
+** at the same instant.
+*/
+SQLITE_PRIVATE void sqlite3BtreeEnterAll(sqlite3 *db){
+  int i;
+  Btree *p;
+  assert( sqlite3_mutex_held(db->mutex) );
+  for(i=0; i<db->nDb; i++){
+    p = db->aDb[i].pBt;
+    if( p ) sqlite3BtreeEnter(p);
+  }
+}
+SQLITE_PRIVATE void sqlite3BtreeLeaveAll(sqlite3 *db){
+  int i;
+  Btree *p;
+  assert( sqlite3_mutex_held(db->mutex) );
+  for(i=0; i<db->nDb; i++){
+    p = db->aDb[i].pBt;
+    if( p ) sqlite3BtreeLeave(p);
+  }
+}
+
+/*
+** Return true if a particular Btree requires a lock.  Return FALSE if
+** no lock is ever required since it is not sharable.
+*/
+SQLITE_PRIVATE int sqlite3BtreeSharable(Btree *p){
+  return p->sharable;
+}
+
+#ifndef NDEBUG
+/*
+** Return true if the current thread holds the database connection
+** mutex and all required BtShared mutexes.
+**
+** This routine is used inside assert() statements only.
+*/
+SQLITE_PRIVATE int sqlite3BtreeHoldsAllMutexes(sqlite3 *db){
+  int i;
+  if( !sqlite3_mutex_held(db->mutex) ){
+    return 0;
+  }
+  for(i=0; i<db->nDb; i++){
+    Btree *p;
+    p = db->aDb[i].pBt;
+    if( p && p->sharable &&
+         (p->wantToLock==0 || !sqlite3_mutex_held(p->pBt->mutex)) ){
+      return 0;
+    }
+  }
+  return 1;
+}
+#endif /* NDEBUG */
+
+#ifndef NDEBUG
+/*
+** Return true if the correct mutexes are held for accessing the
+** db->aDb[iDb].pSchema structure.  The mutexes required for schema
+** access are:
+**
+**   (1) The mutex on db
+**   (2) if iDb!=1, then the mutex on db->aDb[iDb].pBt.
+**
+** If pSchema is not NULL, then iDb is computed from pSchema and
+** db using sqlite3SchemaToIndex().
+*/
+SQLITE_PRIVATE int sqlite3SchemaMutexHeld(sqlite3 *db, int iDb, Schema *pSchema){
+  Btree *p;
+  assert( db!=0 );
+  if( pSchema ) iDb = sqlite3SchemaToIndex(db, pSchema);
+  assert( iDb>=0 && iDb<db->nDb );
+  if( !sqlite3_mutex_held(db->mutex) ) return 0;
+  if( iDb==1 ) return 1;
+  p = db->aDb[iDb].pBt;
+  assert( p!=0 );
+  return p->sharable==0 || p->locked==1;
+}
+#endif /* NDEBUG */
+
+#else /* SQLITE_THREADSAFE>0 above.  SQLITE_THREADSAFE==0 below */
+/*
+** The following are special cases for mutex enter routines for use
+** in single threaded applications that use shared cache.  Except for
+** these two routines, all mutex operations are no-ops in that case and
+** are null #defines in btree.h.
+**
+** If shared cache is disabled, then all btree mutex routines, including
+** the ones below, are no-ops and are null #defines in btree.h.
+*/
+
+SQLITE_PRIVATE void sqlite3BtreeEnter(Btree *p){
+  p->pBt->db = p->db;
+}
+SQLITE_PRIVATE void sqlite3BtreeEnterAll(sqlite3 *db){
+  int i;
+  for(i=0; i<db->nDb; i++){
+    Btree *p = db->aDb[i].pBt;
+    if( p ){
+      p->pBt->db = p->db;
+    }
+  }
+}
+#endif /* if SQLITE_THREADSAFE */
+#endif /* ifndef SQLITE_OMIT_SHARED_CACHE */
+
+/************** End of btmutex.c *********************************************/
+/************** Begin file btree.c *******************************************/
+/*
+** 2004 April 6
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file implements a external (disk-based) database using BTrees.
+** See the header comment on "btreeInt.h" for additional information.
+** Including a description of file format and an overview of operation.
+*/
+
+/*
+** The header string that appears at the beginning of every
+** SQLite database.
+*/
+static const char zMagicHeader[] = SQLITE_FILE_HEADER;
+
+/*
+** Set this global variable to 1 to enable tracing using the TRACE
+** macro.
+*/
+#if 0
+int sqlite3BtreeTrace=1;  /* True to enable tracing */
+# define TRACE(X)  if(sqlite3BtreeTrace){printf X;fflush(stdout);}
+#else
+# define TRACE(X)
+#endif
+
+/*
+** Extract a 2-byte big-endian integer from an array of unsigned bytes.
+** But if the value is zero, make it 65536.
+**
+** This routine is used to extract the "offset to cell content area" value
+** from the header of a btree page.  If the page size is 65536 and the page
+** is empty, the offset should be 65536, but the 2-byte value stores zero.
+** This routine makes the necessary adjustment to 65536.
+*/
+#define get2byteNotZero(X)  (((((int)get2byte(X))-1)&0xffff)+1)
+
+#ifndef SQLITE_OMIT_SHARED_CACHE
+/*
+** A list of BtShared objects that are eligible for participation
+** in shared cache.  This variable has file scope during normal builds,
+** but the test harness needs to access it so we make it global for 
+** test builds.
+**
+** Access to this variable is protected by SQLITE_MUTEX_STATIC_MASTER.
+*/
+#ifdef SQLITE_TEST
+SQLITE_PRIVATE BtShared *SQLITE_WSD sqlite3SharedCacheList = 0;
+#else
+static BtShared *SQLITE_WSD sqlite3SharedCacheList = 0;
+#endif
+#endif /* SQLITE_OMIT_SHARED_CACHE */
+
+#ifndef SQLITE_OMIT_SHARED_CACHE
+/*
+** Enable or disable the shared pager and schema features.
+**
+** This routine has no effect on existing database connections.
+** The shared cache setting effects only future calls to
+** sqlite3_open(), sqlite3_open16(), or sqlite3_open_v2().
+*/
+SQLITE_API int sqlite3_enable_shared_cache(int enable){
+  sqlite3GlobalConfig.sharedCacheEnabled = enable;
+  return SQLITE_OK;
+}
+#endif
+
+
+
+#ifdef SQLITE_OMIT_SHARED_CACHE
+  /*
+  ** The functions querySharedCacheTableLock(), setSharedCacheTableLock(),
+  ** and clearAllSharedCacheTableLocks()
+  ** manipulate entries in the BtShared.pLock linked list used to store
+  ** shared-cache table level locks. If the library is compiled with the
+  ** shared-cache feature disabled, then there is only ever one user
+  ** of each BtShared structure and so this locking is not necessary. 
+  ** So define the lock related functions as no-ops.
+  */
+  #define querySharedCacheTableLock(a,b,c) SQLITE_OK
+  #define setSharedCacheTableLock(a,b,c) SQLITE_OK
+  #define clearAllSharedCacheTableLocks(a)
+  #define downgradeAllSharedCacheTableLocks(a)
+  #define hasSharedCacheTableLock(a,b,c,d) 1
+  #define hasReadConflicts(a, b) 0
+#endif
+
+#ifndef SQLITE_OMIT_SHARED_CACHE
+
+#ifdef SQLITE_DEBUG
+/*
+**** This function is only used as part of an assert() statement. ***
+**
+** Check to see if pBtree holds the required locks to read or write to the 
+** table with root page iRoot.   Return 1 if it does and 0 if not.
+**
+** For example, when writing to a table with root-page iRoot via 
+** Btree connection pBtree:
+**
+**    assert( hasSharedCacheTableLock(pBtree, iRoot, 0, WRITE_LOCK) );
+**
+** When writing to an index that resides in a sharable database, the 
+** caller should have first obtained a lock specifying the root page of
+** the corresponding table. This makes things a bit more complicated,
+** as this module treats each table as a separate structure. To determine
+** the table corresponding to the index being written, this
+** function has to search through the database schema.
+**
+** Instead of a lock on the table/index rooted at page iRoot, the caller may
+** hold a write-lock on the schema table (root page 1). This is also
+** acceptable.
+*/
+static int hasSharedCacheTableLock(
+  Btree *pBtree,         /* Handle that must hold lock */
+  Pgno iRoot,            /* Root page of b-tree */
+  int isIndex,           /* True if iRoot is the root of an index b-tree */
+  int eLockType          /* Required lock type (READ_LOCK or WRITE_LOCK) */
+){
+  Schema *pSchema = (Schema *)pBtree->pBt->pSchema;
+  Pgno iTab = 0;
+  BtLock *pLock;
+
+  /* If this database is not shareable, or if the client is reading
+  ** and has the read-uncommitted flag set, then no lock is required. 
+  ** Return true immediately.
+  */
+  if( (pBtree->sharable==0)
+   || (eLockType==READ_LOCK && (pBtree->db->flags & SQLITE_ReadUncommitted))
+  ){
+    return 1;
+  }
+
+  /* If the client is reading  or writing an index and the schema is
+  ** not loaded, then it is too difficult to actually check to see if
+  ** the correct locks are held.  So do not bother - just return true.
+  ** This case does not come up very often anyhow.
+  */
+  if( isIndex && (!pSchema || (pSchema->flags&DB_SchemaLoaded)==0) ){
+    return 1;
+  }
+
+  /* Figure out the root-page that the lock should be held on. For table
+  ** b-trees, this is just the root page of the b-tree being read or
+  ** written. For index b-trees, it is the root page of the associated
+  ** table.  */
+  if( isIndex ){
+    HashElem *p;
+    for(p=sqliteHashFirst(&pSchema->idxHash); p; p=sqliteHashNext(p)){
+      Index *pIdx = (Index *)sqliteHashData(p);
+      if( pIdx->tnum==(int)iRoot ){
+        iTab = pIdx->pTable->tnum;
+      }
+    }
+  }else{
+    iTab = iRoot;
+  }
+
+  /* Search for the required lock. Either a write-lock on root-page iTab, a 
+  ** write-lock on the schema table, or (if the client is reading) a
+  ** read-lock on iTab will suffice. Return 1 if any of these are found.  */
+  for(pLock=pBtree->pBt->pLock; pLock; pLock=pLock->pNext){
+    if( pLock->pBtree==pBtree 
+     && (pLock->iTable==iTab || (pLock->eLock==WRITE_LOCK && pLock->iTable==1))
+     && pLock->eLock>=eLockType 
+    ){
+      return 1;
+    }
+  }
+
+  /* Failed to find the required lock. */
+  return 0;
+}
+#endif /* SQLITE_DEBUG */
+
+#ifdef SQLITE_DEBUG
+/*
+**** This function may be used as part of assert() statements only. ****
+**
+** Return true if it would be illegal for pBtree to write into the
+** table or index rooted at iRoot because other shared connections are
+** simultaneously reading that same table or index.
+**
+** It is illegal for pBtree to write if some other Btree object that
+** shares the same BtShared object is currently reading or writing
+** the iRoot table.  Except, if the other Btree object has the
+** read-uncommitted flag set, then it is OK for the other object to
+** have a read cursor.
+**
+** For example, before writing to any part of the table or index
+** rooted at page iRoot, one should call:
+**
+**    assert( !hasReadConflicts(pBtree, iRoot) );
+*/
+static int hasReadConflicts(Btree *pBtree, Pgno iRoot){
+  BtCursor *p;
+  for(p=pBtree->pBt->pCursor; p; p=p->pNext){
+    if( p->pgnoRoot==iRoot 
+     && p->pBtree!=pBtree
+     && 0==(p->pBtree->db->flags & SQLITE_ReadUncommitted)
+    ){
+      return 1;
+    }
+  }
+  return 0;
+}
+#endif    /* #ifdef SQLITE_DEBUG */
+
+/*
+** Query to see if Btree handle p may obtain a lock of type eLock 
+** (READ_LOCK or WRITE_LOCK) on the table with root-page iTab. Return
+** SQLITE_OK if the lock may be obtained (by calling
+** setSharedCacheTableLock()), or SQLITE_LOCKED if not.
+*/
+static int querySharedCacheTableLock(Btree *p, Pgno iTab, u8 eLock){
+  BtShared *pBt = p->pBt;
+  BtLock *pIter;
+
+  assert( sqlite3BtreeHoldsMutex(p) );
+  assert( eLock==READ_LOCK || eLock==WRITE_LOCK );
+  assert( p->db!=0 );
+  assert( !(p->db->flags&SQLITE_ReadUncommitted)||eLock==WRITE_LOCK||iTab==1 );
+  
+  /* If requesting a write-lock, then the Btree must have an open write
+  ** transaction on this file. And, obviously, for this to be so there 
+  ** must be an open write transaction on the file itself.
+  */
+  assert( eLock==READ_LOCK || (p==pBt->pWriter && p->inTrans==TRANS_WRITE) );
+  assert( eLock==READ_LOCK || pBt->inTransaction==TRANS_WRITE );
+  
+  /* This routine is a no-op if the shared-cache is not enabled */
+  if( !p->sharable ){
+    return SQLITE_OK;
+  }
+
+  /* If some other connection is holding an exclusive lock, the
+  ** requested lock may not be obtained.
+  */
+  if( pBt->pWriter!=p && pBt->isExclusive ){
+    sqlite3ConnectionBlocked(p->db, pBt->pWriter->db);
+    return SQLITE_LOCKED_SHAREDCACHE;
+  }
+
+  for(pIter=pBt->pLock; pIter; pIter=pIter->pNext){
+    /* The condition (pIter->eLock!=eLock) in the following if(...) 
+    ** statement is a simplification of:
+    **
+    **   (eLock==WRITE_LOCK || pIter->eLock==WRITE_LOCK)
+    **
+    ** since we know that if eLock==WRITE_LOCK, then no other connection
+    ** may hold a WRITE_LOCK on any table in this file (since there can
+    ** only be a single writer).
+    */
+    assert( pIter->eLock==READ_LOCK || pIter->eLock==WRITE_LOCK );
+    assert( eLock==READ_LOCK || pIter->pBtree==p || pIter->eLock==READ_LOCK);
+    if( pIter->pBtree!=p && pIter->iTable==iTab && pIter->eLock!=eLock ){
+      sqlite3ConnectionBlocked(p->db, pIter->pBtree->db);
+      if( eLock==WRITE_LOCK ){
+        assert( p==pBt->pWriter );
+        pBt->isPending = 1;
+      }
+      return SQLITE_LOCKED_SHAREDCACHE;
+    }
+  }
+  return SQLITE_OK;
+}
+#endif /* !SQLITE_OMIT_SHARED_CACHE */
+
+#ifndef SQLITE_OMIT_SHARED_CACHE
+/*
+** Add a lock on the table with root-page iTable to the shared-btree used
+** by Btree handle p. Parameter eLock must be either READ_LOCK or 
+** WRITE_LOCK.
+**
+** This function assumes the following:
+**
+**   (a) The specified Btree object p is connected to a sharable
+**       database (one with the BtShared.sharable flag set), and
+**
+**   (b) No other Btree objects hold a lock that conflicts
+**       with the requested lock (i.e. querySharedCacheTableLock() has
+**       already been called and returned SQLITE_OK).
+**
+** SQLITE_OK is returned if the lock is added successfully. SQLITE_NOMEM 
+** is returned if a malloc attempt fails.
+*/
+static int setSharedCacheTableLock(Btree *p, Pgno iTable, u8 eLock){
+  BtShared *pBt = p->pBt;
+  BtLock *pLock = 0;
+  BtLock *pIter;
+
+  assert( sqlite3BtreeHoldsMutex(p) );
+  assert( eLock==READ_LOCK || eLock==WRITE_LOCK );
+  assert( p->db!=0 );
+
+  /* A connection with the read-uncommitted flag set will never try to
+  ** obtain a read-lock using this function. The only read-lock obtained
+  ** by a connection in read-uncommitted mode is on the sqlite_master 
+  ** table, and that lock is obtained in BtreeBeginTrans().  */
+  assert( 0==(p->db->flags&SQLITE_ReadUncommitted) || eLock==WRITE_LOCK );
+
+  /* This function should only be called on a sharable b-tree after it 
+  ** has been determined that no other b-tree holds a conflicting lock.  */
+  assert( p->sharable );
+  assert( SQLITE_OK==querySharedCacheTableLock(p, iTable, eLock) );
+
+  /* First search the list for an existing lock on this table. */
+  for(pIter=pBt->pLock; pIter; pIter=pIter->pNext){
+    if( pIter->iTable==iTable && pIter->pBtree==p ){
+      pLock = pIter;
+      break;
+    }
+  }
+
+  /* If the above search did not find a BtLock struct associating Btree p
+  ** with table iTable, allocate one and link it into the list.
+  */
+  if( !pLock ){
+    pLock = (BtLock *)sqlite3MallocZero(sizeof(BtLock));
+    if( !pLock ){
+      return SQLITE_NOMEM;
+    }
+    pLock->iTable = iTable;
+    pLock->pBtree = p;
+    pLock->pNext = pBt->pLock;
+    pBt->pLock = pLock;
+  }
+
+  /* Set the BtLock.eLock variable to the maximum of the current lock
+  ** and the requested lock. This means if a write-lock was already held
+  ** and a read-lock requested, we don't incorrectly downgrade the lock.
+  */
+  assert( WRITE_LOCK>READ_LOCK );
+  if( eLock>pLock->eLock ){
+    pLock->eLock = eLock;
+  }
+
+  return SQLITE_OK;
+}
+#endif /* !SQLITE_OMIT_SHARED_CACHE */
+
+#ifndef SQLITE_OMIT_SHARED_CACHE
+/*
+** Release all the table locks (locks obtained via calls to
+** the setSharedCacheTableLock() procedure) held by Btree object p.
+**
+** This function assumes that Btree p has an open read or write 
+** transaction. If it does not, then the BtShared.isPending variable
+** may be incorrectly cleared.
+*/
+static void clearAllSharedCacheTableLocks(Btree *p){
+  BtShared *pBt = p->pBt;
+  BtLock **ppIter = &pBt->pLock;
+
+  assert( sqlite3BtreeHoldsMutex(p) );
+  assert( p->sharable || 0==*ppIter );
+  assert( p->inTrans>0 );
+
+  while( *ppIter ){
+    BtLock *pLock = *ppIter;
+    assert( pBt->isExclusive==0 || pBt->pWriter==pLock->pBtree );
+    assert( pLock->pBtree->inTrans>=pLock->eLock );
+    if( pLock->pBtree==p ){
+      *ppIter = pLock->pNext;
+      assert( pLock->iTable!=1 || pLock==&p->lock );
+      if( pLock->iTable!=1 ){
+        sqlite3_free(pLock);
+      }
+    }else{
+      ppIter = &pLock->pNext;
+    }
+  }
+
+  assert( pBt->isPending==0 || pBt->pWriter );
+  if( pBt->pWriter==p ){
+    pBt->pWriter = 0;
+    pBt->isExclusive = 0;
+    pBt->isPending = 0;
+  }else if( pBt->nTransaction==2 ){
+    /* This function is called when Btree p is concluding its 
+    ** transaction. If there currently exists a writer, and p is not
+    ** that writer, then the number of locks held by connections other
+    ** than the writer must be about to drop to zero. In this case
+    ** set the isPending flag to 0.
+    **
+    ** If there is not currently a writer, then BtShared.isPending must
+    ** be zero already. So this next line is harmless in that case.
+    */
+    pBt->isPending = 0;
+  }
+}
+
+/*
+** This function changes all write-locks held by Btree p into read-locks.
+*/
+static void downgradeAllSharedCacheTableLocks(Btree *p){
+  BtShared *pBt = p->pBt;
+  if( pBt->pWriter==p ){
+    BtLock *pLock;
+    pBt->pWriter = 0;
+    pBt->isExclusive = 0;
+    pBt->isPending = 0;
+    for(pLock=pBt->pLock; pLock; pLock=pLock->pNext){
+      assert( pLock->eLock==READ_LOCK || pLock->pBtree==p );
+      pLock->eLock = READ_LOCK;
+    }
+  }
+}
+
+#endif /* SQLITE_OMIT_SHARED_CACHE */
+
+static void releasePage(MemPage *pPage);  /* Forward reference */
+
+/*
+***** This routine is used inside of assert() only ****
+**
+** Verify that the cursor holds the mutex on its BtShared
+*/
+#ifdef SQLITE_DEBUG
+static int cursorHoldsMutex(BtCursor *p){
+  return sqlite3_mutex_held(p->pBt->mutex);
+}
+#endif
+
+
+#ifndef SQLITE_OMIT_INCRBLOB
+/*
+** Invalidate the overflow page-list cache for cursor pCur, if any.
+*/
+static void invalidateOverflowCache(BtCursor *pCur){
+  assert( cursorHoldsMutex(pCur) );
+  sqlite3_free(pCur->aOverflow);
+  pCur->aOverflow = 0;
+}
+
+/*
+** Invalidate the overflow page-list cache for all cursors opened
+** on the shared btree structure pBt.
+*/
+static void invalidateAllOverflowCache(BtShared *pBt){
+  BtCursor *p;
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  for(p=pBt->pCursor; p; p=p->pNext){
+    invalidateOverflowCache(p);
+  }
+}
+
+/*
+** This function is called before modifying the contents of a table
+** to invalidate any incrblob cursors that are open on the
+** row or one of the rows being modified.
+**
+** If argument isClearTable is true, then the entire contents of the
+** table is about to be deleted. In this case invalidate all incrblob
+** cursors open on any row within the table with root-page pgnoRoot.
+**
+** Otherwise, if argument isClearTable is false, then the row with
+** rowid iRow is being replaced or deleted. In this case invalidate
+** only those incrblob cursors open on that specific row.
+*/
+static void invalidateIncrblobCursors(
+  Btree *pBtree,          /* The database file to check */
+  i64 iRow,               /* The rowid that might be changing */
+  int isClearTable        /* True if all rows are being deleted */
+){
+  BtCursor *p;
+  BtShared *pBt = pBtree->pBt;
+  assert( sqlite3BtreeHoldsMutex(pBtree) );
+  for(p=pBt->pCursor; p; p=p->pNext){
+    if( p->isIncrblobHandle && (isClearTable || p->info.nKey==iRow) ){
+      p->eState = CURSOR_INVALID;
+    }
+  }
+}
+
+#else
+  /* Stub functions when INCRBLOB is omitted */
+  #define invalidateOverflowCache(x)
+  #define invalidateAllOverflowCache(x)
+  #define invalidateIncrblobCursors(x,y,z)
+#endif /* SQLITE_OMIT_INCRBLOB */
+
+/*
+** Set bit pgno of the BtShared.pHasContent bitvec. This is called 
+** when a page that previously contained data becomes a free-list leaf 
+** page.
+**
+** The BtShared.pHasContent bitvec exists to work around an obscure
+** bug caused by the interaction of two useful IO optimizations surrounding
+** free-list leaf pages:
+**
+**   1) When all data is deleted from a page and the page becomes
+**      a free-list leaf page, the page is not written to the database
+**      (as free-list leaf pages contain no meaningful data). Sometimes
+**      such a page is not even journalled (as it will not be modified,
+**      why bother journalling it?).
+**
+**   2) When a free-list leaf page is reused, its content is not read
+**      from the database or written to the journal file (why should it
+**      be, if it is not at all meaningful?).
+**
+** By themselves, these optimizations work fine and provide a handy
+** performance boost to bulk delete or insert operations. However, if
+** a page is moved to the free-list and then reused within the same
+** transaction, a problem comes up. If the page is not journalled when
+** it is moved to the free-list and it is also not journalled when it
+** is extracted from the free-list and reused, then the original data
+** may be lost. In the event of a rollback, it may not be possible
+** to restore the database to its original configuration.
+**
+** The solution is the BtShared.pHasContent bitvec. Whenever a page is 
+** moved to become a free-list leaf page, the corresponding bit is
+** set in the bitvec. Whenever a leaf page is extracted from the free-list,
+** optimization 2 above is omitted if the corresponding bit is already
+** set in BtShared.pHasContent. The contents of the bitvec are cleared
+** at the end of every transaction.
+*/
+static int btreeSetHasContent(BtShared *pBt, Pgno pgno){
+  int rc = SQLITE_OK;
+  if( !pBt->pHasContent ){
+    assert( pgno<=pBt->nPage );
+    pBt->pHasContent = sqlite3BitvecCreate(pBt->nPage);
+    if( !pBt->pHasContent ){
+      rc = SQLITE_NOMEM;
+    }
+  }
+  if( rc==SQLITE_OK && pgno<=sqlite3BitvecSize(pBt->pHasContent) ){
+    rc = sqlite3BitvecSet(pBt->pHasContent, pgno);
+  }
+  return rc;
+}
+
+/*
+** Query the BtShared.pHasContent vector.
+**
+** This function is called when a free-list leaf page is removed from the
+** free-list for reuse. It returns false if it is safe to retrieve the
+** page from the pager layer with the 'no-content' flag set. True otherwise.
+*/
+static int btreeGetHasContent(BtShared *pBt, Pgno pgno){
+  Bitvec *p = pBt->pHasContent;
+  return (p && (pgno>sqlite3BitvecSize(p) || sqlite3BitvecTest(p, pgno)));
+}
+
+/*
+** Clear (destroy) the BtShared.pHasContent bitvec. This should be
+** invoked at the conclusion of each write-transaction.
+*/
+static void btreeClearHasContent(BtShared *pBt){
+  sqlite3BitvecDestroy(pBt->pHasContent);
+  pBt->pHasContent = 0;
+}
+
+/*
+** Save the current cursor position in the variables BtCursor.nKey 
+** and BtCursor.pKey. The cursor's state is set to CURSOR_REQUIRESEEK.
+**
+** The caller must ensure that the cursor is valid (has eState==CURSOR_VALID)
+** prior to calling this routine.  
+*/
+static int saveCursorPosition(BtCursor *pCur){
+  int rc;
+
+  assert( CURSOR_VALID==pCur->eState );
+  assert( 0==pCur->pKey );
+  assert( cursorHoldsMutex(pCur) );
+
+  rc = sqlite3BtreeKeySize(pCur, &pCur->nKey);
+  assert( rc==SQLITE_OK );  /* KeySize() cannot fail */
+
+  /* If this is an intKey table, then the above call to BtreeKeySize()
+  ** stores the integer key in pCur->nKey. In this case this value is
+  ** all that is required. Otherwise, if pCur is not open on an intKey
+  ** table, then malloc space for and store the pCur->nKey bytes of key 
+  ** data.
+  */
+  if( 0==pCur->apPage[0]->intKey ){
+    void *pKey = sqlite3Malloc( (int)pCur->nKey );
+    if( pKey ){
+      rc = sqlite3BtreeKey(pCur, 0, (int)pCur->nKey, pKey);
+      if( rc==SQLITE_OK ){
+        pCur->pKey = pKey;
+      }else{
+        sqlite3_free(pKey);
+      }
+    }else{
+      rc = SQLITE_NOMEM;
+    }
+  }
+  assert( !pCur->apPage[0]->intKey || !pCur->pKey );
+
+  if( rc==SQLITE_OK ){
+    int i;
+    for(i=0; i<=pCur->iPage; i++){
+      releasePage(pCur->apPage[i]);
+      pCur->apPage[i] = 0;
+    }
+    pCur->iPage = -1;
+    pCur->eState = CURSOR_REQUIRESEEK;
+  }
+
+  invalidateOverflowCache(pCur);
+  return rc;
+}
+
+/*
+** Save the positions of all cursors (except pExcept) that are open on
+** the table  with root-page iRoot. Usually, this is called just before cursor
+** pExcept is used to modify the table (BtreeDelete() or BtreeInsert()).
+*/
+static int saveAllCursors(BtShared *pBt, Pgno iRoot, BtCursor *pExcept){
+  BtCursor *p;
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  assert( pExcept==0 || pExcept->pBt==pBt );
+  for(p=pBt->pCursor; p; p=p->pNext){
+    if( p!=pExcept && (0==iRoot || p->pgnoRoot==iRoot) && 
+        p->eState==CURSOR_VALID ){
+      int rc = saveCursorPosition(p);
+      if( SQLITE_OK!=rc ){
+        return rc;
+      }
+    }
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Clear the current cursor position.
+*/
+SQLITE_PRIVATE void sqlite3BtreeClearCursor(BtCursor *pCur){
+  assert( cursorHoldsMutex(pCur) );
+  sqlite3_free(pCur->pKey);
+  pCur->pKey = 0;
+  pCur->eState = CURSOR_INVALID;
+}
+
+/*
+** In this version of BtreeMoveto, pKey is a packed index record
+** such as is generated by the OP_MakeRecord opcode.  Unpack the
+** record and then call BtreeMovetoUnpacked() to do the work.
+*/
+static int btreeMoveto(
+  BtCursor *pCur,     /* Cursor open on the btree to be searched */
+  const void *pKey,   /* Packed key if the btree is an index */
+  i64 nKey,           /* Integer key for tables.  Size of pKey for indices */
+  int bias,           /* Bias search to the high end */
+  int *pRes           /* Write search results here */
+){
+  int rc;                    /* Status code */
+  UnpackedRecord *pIdxKey;   /* Unpacked index key */
+  char aSpace[150];          /* Temp space for pIdxKey - to avoid a malloc */
+
+  if( pKey ){
+    assert( nKey==(i64)(int)nKey );
+    pIdxKey = sqlite3VdbeRecordUnpack(pCur->pKeyInfo, (int)nKey, pKey,
+                                      aSpace, sizeof(aSpace));
+    if( pIdxKey==0 ) return SQLITE_NOMEM;
+  }else{
+    pIdxKey = 0;
+  }
+  rc = sqlite3BtreeMovetoUnpacked(pCur, pIdxKey, nKey, bias, pRes);
+  if( pKey ){
+    sqlite3VdbeDeleteUnpackedRecord(pIdxKey);
+  }
+  return rc;
+}
+
+/*
+** Restore the cursor to the position it was in (or as close to as possible)
+** when saveCursorPosition() was called. Note that this call deletes the 
+** saved position info stored by saveCursorPosition(), so there can be
+** at most one effective restoreCursorPosition() call after each 
+** saveCursorPosition().
+*/
+static int btreeRestoreCursorPosition(BtCursor *pCur){
+  int rc;
+  assert( cursorHoldsMutex(pCur) );
+  assert( pCur->eState>=CURSOR_REQUIRESEEK );
+  if( pCur->eState==CURSOR_FAULT ){
+    return pCur->skipNext;
+  }
+  pCur->eState = CURSOR_INVALID;
+  rc = btreeMoveto(pCur, pCur->pKey, pCur->nKey, 0, &pCur->skipNext);
+  if( rc==SQLITE_OK ){
+    sqlite3_free(pCur->pKey);
+    pCur->pKey = 0;
+    assert( pCur->eState==CURSOR_VALID || pCur->eState==CURSOR_INVALID );
+  }
+  return rc;
+}
+
+#define restoreCursorPosition(p) \
+  (p->eState>=CURSOR_REQUIRESEEK ? \
+         btreeRestoreCursorPosition(p) : \
+         SQLITE_OK)
+
+/*
+** Determine whether or not a cursor has moved from the position it
+** was last placed at.  Cursors can move when the row they are pointing
+** at is deleted out from under them.
+**
+** This routine returns an error code if something goes wrong.  The
+** integer *pHasMoved is set to one if the cursor has moved and 0 if not.
+*/
+SQLITE_PRIVATE int sqlite3BtreeCursorHasMoved(BtCursor *pCur, int *pHasMoved){
+  int rc;
+
+  rc = restoreCursorPosition(pCur);
+  if( rc ){
+    *pHasMoved = 1;
+    return rc;
+  }
+  if( pCur->eState!=CURSOR_VALID || pCur->skipNext!=0 ){
+    *pHasMoved = 1;
+  }else{
+    *pHasMoved = 0;
+  }
+  return SQLITE_OK;
+}
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+/*
+** Given a page number of a regular database page, return the page
+** number for the pointer-map page that contains the entry for the
+** input page number.
+**
+** Return 0 (not a valid page) for pgno==1 since there is
+** no pointer map associated with page 1.  The integrity_check logic
+** requires that ptrmapPageno(*,1)!=1.
+*/
+static Pgno ptrmapPageno(BtShared *pBt, Pgno pgno){
+  int nPagesPerMapPage;
+  Pgno iPtrMap, ret;
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  if( pgno<2 ) return 0;
+  nPagesPerMapPage = (pBt->usableSize/5)+1;
+  iPtrMap = (pgno-2)/nPagesPerMapPage;
+  ret = (iPtrMap*nPagesPerMapPage) + 2; 
+  if( ret==PENDING_BYTE_PAGE(pBt) ){
+    ret++;
+  }
+  return ret;
+}
+
+/*
+** Write an entry into the pointer map.
+**
+** This routine updates the pointer map entry for page number 'key'
+** so that it maps to type 'eType' and parent page number 'pgno'.
+**
+** If *pRC is initially non-zero (non-SQLITE_OK) then this routine is
+** a no-op.  If an error occurs, the appropriate error code is written
+** into *pRC.
+*/
+static void ptrmapPut(BtShared *pBt, Pgno key, u8 eType, Pgno parent, int *pRC){
+  DbPage *pDbPage;  /* The pointer map page */
+  u8 *pPtrmap;      /* The pointer map data */
+  Pgno iPtrmap;     /* The pointer map page number */
+  int offset;       /* Offset in pointer map page */
+  int rc;           /* Return code from subfunctions */
+
+  if( *pRC ) return;
+
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  /* The master-journal page number must never be used as a pointer map page */
+  assert( 0==PTRMAP_ISPAGE(pBt, PENDING_BYTE_PAGE(pBt)) );
+
+  assert( pBt->autoVacuum );
+  if( key==0 ){
+    *pRC = SQLITE_CORRUPT_BKPT;
+    return;
+  }
+  iPtrmap = PTRMAP_PAGENO(pBt, key);
+  rc = sqlite3PagerGet(pBt->pPager, iPtrmap, &pDbPage);
+  if( rc!=SQLITE_OK ){
+    *pRC = rc;
+    return;
+  }
+  offset = PTRMAP_PTROFFSET(iPtrmap, key);
+  if( offset<0 ){
+    *pRC = SQLITE_CORRUPT_BKPT;
+    goto ptrmap_exit;
+  }
+  pPtrmap = (u8 *)sqlite3PagerGetData(pDbPage);
+
+  if( eType!=pPtrmap[offset] || get4byte(&pPtrmap[offset+1])!=parent ){
+    TRACE(("PTRMAP_UPDATE: %d->(%d,%d)\n", key, eType, parent));
+    *pRC= rc = sqlite3PagerWrite(pDbPage);
+    if( rc==SQLITE_OK ){
+      pPtrmap[offset] = eType;
+      put4byte(&pPtrmap[offset+1], parent);
+    }
+  }
+
+ptrmap_exit:
+  sqlite3PagerUnref(pDbPage);
+}
+
+/*
+** Read an entry from the pointer map.
+**
+** This routine retrieves the pointer map entry for page 'key', writing
+** the type and parent page number to *pEType and *pPgno respectively.
+** An error code is returned if something goes wrong, otherwise SQLITE_OK.
+*/
+static int ptrmapGet(BtShared *pBt, Pgno key, u8 *pEType, Pgno *pPgno){
+  DbPage *pDbPage;   /* The pointer map page */
+  int iPtrmap;       /* Pointer map page index */
+  u8 *pPtrmap;       /* Pointer map page data */
+  int offset;        /* Offset of entry in pointer map */
+  int rc;
+
+  assert( sqlite3_mutex_held(pBt->mutex) );
+
+  iPtrmap = PTRMAP_PAGENO(pBt, key);
+  rc = sqlite3PagerGet(pBt->pPager, iPtrmap, &pDbPage);
+  if( rc!=0 ){
+    return rc;
+  }
+  pPtrmap = (u8 *)sqlite3PagerGetData(pDbPage);
+
+  offset = PTRMAP_PTROFFSET(iPtrmap, key);
+  assert( pEType!=0 );
+  *pEType = pPtrmap[offset];
+  if( pPgno ) *pPgno = get4byte(&pPtrmap[offset+1]);
+
+  sqlite3PagerUnref(pDbPage);
+  if( *pEType<1 || *pEType>5 ) return SQLITE_CORRUPT_BKPT;
+  return SQLITE_OK;
+}
+
+#else /* if defined SQLITE_OMIT_AUTOVACUUM */
+  #define ptrmapPut(w,x,y,z,rc)
+  #define ptrmapGet(w,x,y,z) SQLITE_OK
+  #define ptrmapPutOvflPtr(x, y, rc)
+#endif
+
+/*
+** Given a btree page and a cell index (0 means the first cell on
+** the page, 1 means the second cell, and so forth) return a pointer
+** to the cell content.
+**
+** This routine works only for pages that do not contain overflow cells.
+*/
+#define findCell(P,I) \
+  ((P)->aData + ((P)->maskPage & get2byte(&(P)->aData[(P)->cellOffset+2*(I)])))
+
+/*
+** This a more complex version of findCell() that works for
+** pages that do contain overflow cells.
+*/
+static u8 *findOverflowCell(MemPage *pPage, int iCell){
+  int i;
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  for(i=pPage->nOverflow-1; i>=0; i--){
+    int k;
+    struct _OvflCell *pOvfl;
+    pOvfl = &pPage->aOvfl[i];
+    k = pOvfl->idx;
+    if( k<=iCell ){
+      if( k==iCell ){
+        return pOvfl->pCell;
+      }
+      iCell--;
+    }
+  }
+  return findCell(pPage, iCell);
+}
+
+/*
+** Parse a cell content block and fill in the CellInfo structure.  There
+** are two versions of this function.  btreeParseCell() takes a 
+** cell index as the second argument and btreeParseCellPtr() 
+** takes a pointer to the body of the cell as its second argument.
+**
+** Within this file, the parseCell() macro can be called instead of
+** btreeParseCellPtr(). Using some compilers, this will be faster.
+*/
+static void btreeParseCellPtr(
+  MemPage *pPage,         /* Page containing the cell */
+  u8 *pCell,              /* Pointer to the cell text. */
+  CellInfo *pInfo         /* Fill in this structure */
+){
+  u16 n;                  /* Number bytes in cell content header */
+  u32 nPayload;           /* Number of bytes of cell payload */
+
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+
+  pInfo->pCell = pCell;
+  assert( pPage->leaf==0 || pPage->leaf==1 );
+  n = pPage->childPtrSize;
+  assert( n==4-4*pPage->leaf );
+  if( pPage->intKey ){
+    if( pPage->hasData ){
+      n += getVarint32(&pCell[n], nPayload);
+    }else{
+      nPayload = 0;
+    }
+    n += getVarint(&pCell[n], (u64*)&pInfo->nKey);
+    pInfo->nData = nPayload;
+  }else{
+    pInfo->nData = 0;
+    n += getVarint32(&pCell[n], nPayload);
+    pInfo->nKey = nPayload;
+  }
+  pInfo->nPayload = nPayload;
+  pInfo->nHeader = n;
+  testcase( nPayload==pPage->maxLocal );
+  testcase( nPayload==pPage->maxLocal+1 );
+  if( likely(nPayload<=pPage->maxLocal) ){
+    /* This is the (easy) common case where the entire payload fits
+    ** on the local page.  No overflow is required.
+    */
+    if( (pInfo->nSize = (u16)(n+nPayload))<4 ) pInfo->nSize = 4;
+    pInfo->nLocal = (u16)nPayload;
+    pInfo->iOverflow = 0;
+  }else{
+    /* If the payload will not fit completely on the local page, we have
+    ** to decide how much to store locally and how much to spill onto
+    ** overflow pages.  The strategy is to minimize the amount of unused
+    ** space on overflow pages while keeping the amount of local storage
+    ** in between minLocal and maxLocal.
+    **
+    ** Warning:  changing the way overflow payload is distributed in any
+    ** way will result in an incompatible file format.
+    */
+    int minLocal;  /* Minimum amount of payload held locally */
+    int maxLocal;  /* Maximum amount of payload held locally */
+    int surplus;   /* Overflow payload available for local storage */
+
+    minLocal = pPage->minLocal;
+    maxLocal = pPage->maxLocal;
+    surplus = minLocal + (nPayload - minLocal)%(pPage->pBt->usableSize - 4);
+    testcase( surplus==maxLocal );
+    testcase( surplus==maxLocal+1 );
+    if( surplus <= maxLocal ){
+      pInfo->nLocal = (u16)surplus;
+    }else{
+      pInfo->nLocal = (u16)minLocal;
+    }
+    pInfo->iOverflow = (u16)(pInfo->nLocal + n);
+    pInfo->nSize = pInfo->iOverflow + 4;
+  }
+}
+#define parseCell(pPage, iCell, pInfo) \
+  btreeParseCellPtr((pPage), findCell((pPage), (iCell)), (pInfo))
+static void btreeParseCell(
+  MemPage *pPage,         /* Page containing the cell */
+  int iCell,              /* The cell index.  First cell is 0 */
+  CellInfo *pInfo         /* Fill in this structure */
+){
+  parseCell(pPage, iCell, pInfo);
+}
+
+/*
+** Compute the total number of bytes that a Cell needs in the cell
+** data area of the btree-page.  The return number includes the cell
+** data header and the local payload, but not any overflow page or
+** the space used by the cell pointer.
+*/
+static u16 cellSizePtr(MemPage *pPage, u8 *pCell){
+  u8 *pIter = &pCell[pPage->childPtrSize];
+  u32 nSize;
+
+#ifdef SQLITE_DEBUG
+  /* The value returned by this function should always be the same as
+  ** the (CellInfo.nSize) value found by doing a full parse of the
+  ** cell. If SQLITE_DEBUG is defined, an assert() at the bottom of
+  ** this function verifies that this invariant is not violated. */
+  CellInfo debuginfo;
+  btreeParseCellPtr(pPage, pCell, &debuginfo);
+#endif
+
+  if( pPage->intKey ){
+    u8 *pEnd;
+    if( pPage->hasData ){
+      pIter += getVarint32(pIter, nSize);
+    }else{
+      nSize = 0;
+    }
+
+    /* pIter now points at the 64-bit integer key value, a variable length 
+    ** integer. The following block moves pIter to point at the first byte
+    ** past the end of the key value. */
+    pEnd = &pIter[9];
+    while( (*pIter++)&0x80 && pIter<pEnd );
+  }else{
+    pIter += getVarint32(pIter, nSize);
+  }
+
+  testcase( nSize==pPage->maxLocal );
+  testcase( nSize==pPage->maxLocal+1 );
+  if( nSize>pPage->maxLocal ){
+    int minLocal = pPage->minLocal;
+    nSize = minLocal + (nSize - minLocal) % (pPage->pBt->usableSize - 4);
+    testcase( nSize==pPage->maxLocal );
+    testcase( nSize==pPage->maxLocal+1 );
+    if( nSize>pPage->maxLocal ){
+      nSize = minLocal;
+    }
+    nSize += 4;
+  }
+  nSize += (u32)(pIter - pCell);
+
+  /* The minimum size of any cell is 4 bytes. */
+  if( nSize<4 ){
+    nSize = 4;
+  }
+
+  assert( nSize==debuginfo.nSize );
+  return (u16)nSize;
+}
+
+#ifdef SQLITE_DEBUG
+/* This variation on cellSizePtr() is used inside of assert() statements
+** only. */
+static u16 cellSize(MemPage *pPage, int iCell){
+  return cellSizePtr(pPage, findCell(pPage, iCell));
+}
+#endif
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+/*
+** If the cell pCell, part of page pPage contains a pointer
+** to an overflow page, insert an entry into the pointer-map
+** for the overflow page.
+*/
+static void ptrmapPutOvflPtr(MemPage *pPage, u8 *pCell, int *pRC){
+  CellInfo info;
+  if( *pRC ) return;
+  assert( pCell!=0 );
+  btreeParseCellPtr(pPage, pCell, &info);
+  assert( (info.nData+(pPage->intKey?0:info.nKey))==info.nPayload );
+  if( info.iOverflow ){
+    Pgno ovfl = get4byte(&pCell[info.iOverflow]);
+    ptrmapPut(pPage->pBt, ovfl, PTRMAP_OVERFLOW1, pPage->pgno, pRC);
+  }
+}
+#endif
+
+
+/*
+** Defragment the page given.  All Cells are moved to the
+** end of the page and all free space is collected into one
+** big FreeBlk that occurs in between the header and cell
+** pointer array and the cell content area.
+*/
+static int defragmentPage(MemPage *pPage){
+  int i;                     /* Loop counter */
+  int pc;                    /* Address of a i-th cell */
+  int hdr;                   /* Offset to the page header */
+  int size;                  /* Size of a cell */
+  int usableSize;            /* Number of usable bytes on a page */
+  int cellOffset;            /* Offset to the cell pointer array */
+  int cbrk;                  /* Offset to the cell content area */
+  int nCell;                 /* Number of cells on the page */
+  unsigned char *data;       /* The page data */
+  unsigned char *temp;       /* Temp area for cell content */
+  int iCellFirst;            /* First allowable cell index */
+  int iCellLast;             /* Last possible cell index */
+
+
+  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
+  assert( pPage->pBt!=0 );
+  assert( pPage->pBt->usableSize <= SQLITE_MAX_PAGE_SIZE );
+  assert( pPage->nOverflow==0 );
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  temp = sqlite3PagerTempSpace(pPage->pBt->pPager);
+  data = pPage->aData;
+  hdr = pPage->hdrOffset;
+  cellOffset = pPage->cellOffset;
+  nCell = pPage->nCell;
+  assert( nCell==get2byte(&data[hdr+3]) );
+  usableSize = pPage->pBt->usableSize;
+  cbrk = get2byte(&data[hdr+5]);
+  memcpy(&temp[cbrk], &data[cbrk], usableSize - cbrk);
+  cbrk = usableSize;
+  iCellFirst = cellOffset + 2*nCell;
+  iCellLast = usableSize - 4;
+  for(i=0; i<nCell; i++){
+    u8 *pAddr;     /* The i-th cell pointer */
+    pAddr = &data[cellOffset + i*2];
+    pc = get2byte(pAddr);
+    testcase( pc==iCellFirst );
+    testcase( pc==iCellLast );
+#if !defined(SQLITE_ENABLE_OVERSIZE_CELL_CHECK)
+    /* These conditions have already been verified in btreeInitPage()
+    ** if SQLITE_ENABLE_OVERSIZE_CELL_CHECK is defined 
+    */
+    if( pc<iCellFirst || pc>iCellLast ){
+      return SQLITE_CORRUPT_BKPT;
+    }
+#endif
+    assert( pc>=iCellFirst && pc<=iCellLast );
+    size = cellSizePtr(pPage, &temp[pc]);
+    cbrk -= size;
+#if defined(SQLITE_ENABLE_OVERSIZE_CELL_CHECK)
+    if( cbrk<iCellFirst ){
+      return SQLITE_CORRUPT_BKPT;
+    }
+#else
+    if( cbrk<iCellFirst || pc+size>usableSize ){
+      return SQLITE_CORRUPT_BKPT;
+    }
+#endif
+    assert( cbrk+size<=usableSize && cbrk>=iCellFirst );
+    testcase( cbrk+size==usableSize );
+    testcase( pc+size==usableSize );
+    memcpy(&data[cbrk], &temp[pc], size);
+    put2byte(pAddr, cbrk);
+  }
+  assert( cbrk>=iCellFirst );
+  put2byte(&data[hdr+5], cbrk);
+  data[hdr+1] = 0;
+  data[hdr+2] = 0;
+  data[hdr+7] = 0;
+  memset(&data[iCellFirst], 0, cbrk-iCellFirst);
+  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
+  if( cbrk-iCellFirst!=pPage->nFree ){
+    return SQLITE_CORRUPT_BKPT;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Allocate nByte bytes of space from within the B-Tree page passed
+** as the first argument. Write into *pIdx the index into pPage->aData[]
+** of the first byte of allocated space. Return either SQLITE_OK or
+** an error code (usually SQLITE_CORRUPT).
+**
+** The caller guarantees that there is sufficient space to make the
+** allocation.  This routine might need to defragment in order to bring
+** all the space together, however.  This routine will avoid using
+** the first two bytes past the cell pointer area since presumably this
+** allocation is being made in order to insert a new cell, so we will
+** also end up needing a new cell pointer.
+*/
+static int allocateSpace(MemPage *pPage, int nByte, int *pIdx){
+  const int hdr = pPage->hdrOffset;    /* Local cache of pPage->hdrOffset */
+  u8 * const data = pPage->aData;      /* Local cache of pPage->aData */
+  int nFrag;                           /* Number of fragmented bytes on pPage */
+  int top;                             /* First byte of cell content area */
+  int gap;        /* First byte of gap between cell pointers and cell content */
+  int rc;         /* Integer return code */
+  int usableSize; /* Usable size of the page */
+  
+  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
+  assert( pPage->pBt );
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  assert( nByte>=0 );  /* Minimum cell size is 4 */
+  assert( pPage->nFree>=nByte );
+  assert( pPage->nOverflow==0 );
+  usableSize = pPage->pBt->usableSize;
+  assert( nByte < usableSize-8 );
+
+  nFrag = data[hdr+7];
+  assert( pPage->cellOffset == hdr + 12 - 4*pPage->leaf );
+  gap = pPage->cellOffset + 2*pPage->nCell;
+  top = get2byteNotZero(&data[hdr+5]);
+  if( gap>top ) return SQLITE_CORRUPT_BKPT;
+  testcase( gap+2==top );
+  testcase( gap+1==top );
+  testcase( gap==top );
+
+  if( nFrag>=60 ){
+    /* Always defragment highly fragmented pages */
+    rc = defragmentPage(pPage);
+    if( rc ) return rc;
+    top = get2byteNotZero(&data[hdr+5]);
+  }else if( gap+2<=top ){
+    /* Search the freelist looking for a free slot big enough to satisfy 
+    ** the request. The allocation is made from the first free slot in 
+    ** the list that is large enough to accomadate it.
+    */
+    int pc, addr;
+    for(addr=hdr+1; (pc = get2byte(&data[addr]))>0; addr=pc){
+      int size;            /* Size of the free slot */
+      if( pc>usableSize-4 || pc<addr+4 ){
+        return SQLITE_CORRUPT_BKPT;
+      }
+      size = get2byte(&data[pc+2]);
+      if( size>=nByte ){
+        int x = size - nByte;
+        testcase( x==4 );
+        testcase( x==3 );
+        if( x<4 ){
+          /* Remove the slot from the free-list. Update the number of
+          ** fragmented bytes within the page. */
+          memcpy(&data[addr], &data[pc], 2);
+          data[hdr+7] = (u8)(nFrag + x);
+        }else if( size+pc > usableSize ){
+          return SQLITE_CORRUPT_BKPT;
+        }else{
+          /* The slot remains on the free-list. Reduce its size to account
+          ** for the portion used by the new allocation. */
+          put2byte(&data[pc+2], x);
+        }
+        *pIdx = pc + x;
+        return SQLITE_OK;
+      }
+    }
+  }
+
+  /* Check to make sure there is enough space in the gap to satisfy
+  ** the allocation.  If not, defragment.
+  */
+  testcase( gap+2+nByte==top );
+  if( gap+2+nByte>top ){
+    rc = defragmentPage(pPage);
+    if( rc ) return rc;
+    top = get2byteNotZero(&data[hdr+5]);
+    assert( gap+nByte<=top );
+  }
+
+
+  /* Allocate memory from the gap in between the cell pointer array
+  ** and the cell content area.  The btreeInitPage() call has already
+  ** validated the freelist.  Given that the freelist is valid, there
+  ** is no way that the allocation can extend off the end of the page.
+  ** The assert() below verifies the previous sentence.
+  */
+  top -= nByte;
+  put2byte(&data[hdr+5], top);
+  assert( top+nByte <= (int)pPage->pBt->usableSize );
+  *pIdx = top;
+  return SQLITE_OK;
+}
+
+/*
+** Return a section of the pPage->aData to the freelist.
+** The first byte of the new free block is pPage->aDisk[start]
+** and the size of the block is "size" bytes.
+**
+** Most of the effort here is involved in coalesing adjacent
+** free blocks into a single big free block.
+*/
+static int freeSpace(MemPage *pPage, int start, int size){
+  int addr, pbegin, hdr;
+  int iLast;                        /* Largest possible freeblock offset */
+  unsigned char *data = pPage->aData;
+
+  assert( pPage->pBt!=0 );
+  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
+  assert( start>=pPage->hdrOffset+6+pPage->childPtrSize );
+  assert( (start + size) <= (int)pPage->pBt->usableSize );
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  assert( size>=0 );   /* Minimum cell size is 4 */
+
+  if( pPage->pBt->secureDelete ){
+    /* Overwrite deleted information with zeros when the secure_delete
+    ** option is enabled */
+    memset(&data[start], 0, size);
+  }
+
+  /* Add the space back into the linked list of freeblocks.  Note that
+  ** even though the freeblock list was checked by btreeInitPage(),
+  ** btreeInitPage() did not detect overlapping cells or
+  ** freeblocks that overlapped cells.   Nor does it detect when the
+  ** cell content area exceeds the value in the page header.  If these
+  ** situations arise, then subsequent insert operations might corrupt
+  ** the freelist.  So we do need to check for corruption while scanning
+  ** the freelist.
+  */
+  hdr = pPage->hdrOffset;
+  addr = hdr + 1;
+  iLast = pPage->pBt->usableSize - 4;
+  assert( start<=iLast );
+  while( (pbegin = get2byte(&data[addr]))<start && pbegin>0 ){
+    if( pbegin<addr+4 ){
+      return SQLITE_CORRUPT_BKPT;
+    }
+    addr = pbegin;
+  }
+  if( pbegin>iLast ){
+    return SQLITE_CORRUPT_BKPT;
+  }
+  assert( pbegin>addr || pbegin==0 );
+  put2byte(&data[addr], start);
+  put2byte(&data[start], pbegin);
+  put2byte(&data[start+2], size);
+  pPage->nFree = pPage->nFree + (u16)size;
+
+  /* Coalesce adjacent free blocks */
+  addr = hdr + 1;
+  while( (pbegin = get2byte(&data[addr]))>0 ){
+    int pnext, psize, x;
+    assert( pbegin>addr );
+    assert( pbegin <= (int)pPage->pBt->usableSize-4 );
+    pnext = get2byte(&data[pbegin]);
+    psize = get2byte(&data[pbegin+2]);
+    if( pbegin + psize + 3 >= pnext && pnext>0 ){
+      int frag = pnext - (pbegin+psize);
+      if( (frag<0) || (frag>(int)data[hdr+7]) ){
+        return SQLITE_CORRUPT_BKPT;
+      }
+      data[hdr+7] -= (u8)frag;
+      x = get2byte(&data[pnext]);
+      put2byte(&data[pbegin], x);
+      x = pnext + get2byte(&data[pnext+2]) - pbegin;
+      put2byte(&data[pbegin+2], x);
+    }else{
+      addr = pbegin;
+    }
+  }
+
+  /* If the cell content area begins with a freeblock, remove it. */
+  if( data[hdr+1]==data[hdr+5] && data[hdr+2]==data[hdr+6] ){
+    int top;
+    pbegin = get2byte(&data[hdr+1]);
+    memcpy(&data[hdr+1], &data[pbegin], 2);
+    top = get2byte(&data[hdr+5]) + get2byte(&data[pbegin+2]);
+    put2byte(&data[hdr+5], top);
+  }
+  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
+  return SQLITE_OK;
+}
+
+/*
+** Decode the flags byte (the first byte of the header) for a page
+** and initialize fields of the MemPage structure accordingly.
+**
+** Only the following combinations are supported.  Anything different
+** indicates a corrupt database files:
+**
+**         PTF_ZERODATA
+**         PTF_ZERODATA | PTF_LEAF
+**         PTF_LEAFDATA | PTF_INTKEY
+**         PTF_LEAFDATA | PTF_INTKEY | PTF_LEAF
+*/
+static int decodeFlags(MemPage *pPage, int flagByte){
+  BtShared *pBt;     /* A copy of pPage->pBt */
+
+  assert( pPage->hdrOffset==(pPage->pgno==1 ? 100 : 0) );
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  pPage->leaf = (u8)(flagByte>>3);  assert( PTF_LEAF == 1<<3 );
+  flagByte &= ~PTF_LEAF;
+  pPage->childPtrSize = 4-4*pPage->leaf;
+  pBt = pPage->pBt;
+  if( flagByte==(PTF_LEAFDATA | PTF_INTKEY) ){
+    pPage->intKey = 1;
+    pPage->hasData = pPage->leaf;
+    pPage->maxLocal = pBt->maxLeaf;
+    pPage->minLocal = pBt->minLeaf;
+  }else if( flagByte==PTF_ZERODATA ){
+    pPage->intKey = 0;
+    pPage->hasData = 0;
+    pPage->maxLocal = pBt->maxLocal;
+    pPage->minLocal = pBt->minLocal;
+  }else{
+    return SQLITE_CORRUPT_BKPT;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Initialize the auxiliary information for a disk block.
+**
+** Return SQLITE_OK on success.  If we see that the page does
+** not contain a well-formed database page, then return 
+** SQLITE_CORRUPT.  Note that a return of SQLITE_OK does not
+** guarantee that the page is well-formed.  It only shows that
+** we failed to detect any corruption.
+*/
+static int btreeInitPage(MemPage *pPage){
+
+  assert( pPage->pBt!=0 );
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  assert( pPage->pgno==sqlite3PagerPagenumber(pPage->pDbPage) );
+  assert( pPage == sqlite3PagerGetExtra(pPage->pDbPage) );
+  assert( pPage->aData == sqlite3PagerGetData(pPage->pDbPage) );
+
+  if( !pPage->isInit ){
+    u16 pc;            /* Address of a freeblock within pPage->aData[] */
+    u8 hdr;            /* Offset to beginning of page header */
+    u8 *data;          /* Equal to pPage->aData */
+    BtShared *pBt;        /* The main btree structure */
+    int usableSize;    /* Amount of usable space on each page */
+    u16 cellOffset;    /* Offset from start of page to first cell pointer */
+    int nFree;         /* Number of unused bytes on the page */
+    int top;           /* First byte of the cell content area */
+    int iCellFirst;    /* First allowable cell or freeblock offset */
+    int iCellLast;     /* Last possible cell or freeblock offset */
+
+    pBt = pPage->pBt;
+
+    hdr = pPage->hdrOffset;
+    data = pPage->aData;
+    if( decodeFlags(pPage, data[hdr]) ) return SQLITE_CORRUPT_BKPT;
+    assert( pBt->pageSize>=512 && pBt->pageSize<=65536 );
+    pPage->maskPage = (u16)(pBt->pageSize - 1);
+    pPage->nOverflow = 0;
+    usableSize = pBt->usableSize;
+    pPage->cellOffset = cellOffset = hdr + 12 - 4*pPage->leaf;
+    top = get2byteNotZero(&data[hdr+5]);
+    pPage->nCell = get2byte(&data[hdr+3]);
+    if( pPage->nCell>MX_CELL(pBt) ){
+      /* To many cells for a single page.  The page must be corrupt */
+      return SQLITE_CORRUPT_BKPT;
+    }
+    testcase( pPage->nCell==MX_CELL(pBt) );
+
+    /* A malformed database page might cause us to read past the end
+    ** of page when parsing a cell.  
+    **
+    ** The following block of code checks early to see if a cell extends
+    ** past the end of a page boundary and causes SQLITE_CORRUPT to be 
+    ** returned if it does.
+    */
+    iCellFirst = cellOffset + 2*pPage->nCell;
+    iCellLast = usableSize - 4;
+#if defined(SQLITE_ENABLE_OVERSIZE_CELL_CHECK)
+    {
+      int i;            /* Index into the cell pointer array */
+      int sz;           /* Size of a cell */
+
+      if( !pPage->leaf ) iCellLast--;
+      for(i=0; i<pPage->nCell; i++){
+        pc = get2byte(&data[cellOffset+i*2]);
+        testcase( pc==iCellFirst );
+        testcase( pc==iCellLast );
+        if( pc<iCellFirst || pc>iCellLast ){
+          return SQLITE_CORRUPT_BKPT;
+        }
+        sz = cellSizePtr(pPage, &data[pc]);
+        testcase( pc+sz==usableSize );
+        if( pc+sz>usableSize ){
+          return SQLITE_CORRUPT_BKPT;
+        }
+      }
+      if( !pPage->leaf ) iCellLast++;
+    }  
+#endif
+
+    /* Compute the total free space on the page */
+    pc = get2byte(&data[hdr+1]);
+    nFree = data[hdr+7] + top;
+    while( pc>0 ){
+      u16 next, size;
+      if( pc<iCellFirst || pc>iCellLast ){
+        /* Start of free block is off the page */
+        return SQLITE_CORRUPT_BKPT; 
+      }
+      next = get2byte(&data[pc]);
+      size = get2byte(&data[pc+2]);
+      if( (next>0 && next<=pc+size+3) || pc+size>usableSize ){
+        /* Free blocks must be in ascending order. And the last byte of
+	** the free-block must lie on the database page.  */
+        return SQLITE_CORRUPT_BKPT; 
+      }
+      nFree = nFree + size;
+      pc = next;
+    }
+
+    /* At this point, nFree contains the sum of the offset to the start
+    ** of the cell-content area plus the number of free bytes within
+    ** the cell-content area. If this is greater than the usable-size
+    ** of the page, then the page must be corrupted. This check also
+    ** serves to verify that the offset to the start of the cell-content
+    ** area, according to the page header, lies within the page.
+    */
+    if( nFree>usableSize ){
+      return SQLITE_CORRUPT_BKPT; 
+    }
+    pPage->nFree = (u16)(nFree - iCellFirst);
+    pPage->isInit = 1;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Set up a raw page so that it looks like a database page holding
+** no entries.
+*/
+static void zeroPage(MemPage *pPage, int flags){
+  unsigned char *data = pPage->aData;
+  BtShared *pBt = pPage->pBt;
+  u8 hdr = pPage->hdrOffset;
+  u16 first;
+
+  assert( sqlite3PagerPagenumber(pPage->pDbPage)==pPage->pgno );
+  assert( sqlite3PagerGetExtra(pPage->pDbPage) == (void*)pPage );
+  assert( sqlite3PagerGetData(pPage->pDbPage) == data );
+  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  if( pBt->secureDelete ){
+    memset(&data[hdr], 0, pBt->usableSize - hdr);
+  }
+  data[hdr] = (char)flags;
+  first = hdr + 8 + 4*((flags&PTF_LEAF)==0 ?1:0);
+  memset(&data[hdr+1], 0, 4);
+  data[hdr+7] = 0;
+  put2byte(&data[hdr+5], pBt->usableSize);
+  pPage->nFree = (u16)(pBt->usableSize - first);
+  decodeFlags(pPage, flags);
+  pPage->hdrOffset = hdr;
+  pPage->cellOffset = first;
+  pPage->nOverflow = 0;
+  assert( pBt->pageSize>=512 && pBt->pageSize<=65536 );
+  pPage->maskPage = (u16)(pBt->pageSize - 1);
+  pPage->nCell = 0;
+  pPage->isInit = 1;
+}
+
+
+/*
+** Convert a DbPage obtained from the pager into a MemPage used by
+** the btree layer.
+*/
+static MemPage *btreePageFromDbPage(DbPage *pDbPage, Pgno pgno, BtShared *pBt){
+  MemPage *pPage = (MemPage*)sqlite3PagerGetExtra(pDbPage);
+  pPage->aData = sqlite3PagerGetData(pDbPage);
+  pPage->pDbPage = pDbPage;
+  pPage->pBt = pBt;
+  pPage->pgno = pgno;
+  pPage->hdrOffset = pPage->pgno==1 ? 100 : 0;
+  return pPage; 
+}
+
+/*
+** Get a page from the pager.  Initialize the MemPage.pBt and
+** MemPage.aData elements if needed.
+**
+** If the noContent flag is set, it means that we do not care about
+** the content of the page at this time.  So do not go to the disk
+** to fetch the content.  Just fill in the content with zeros for now.
+** If in the future we call sqlite3PagerWrite() on this page, that
+** means we have started to be concerned about content and the disk
+** read should occur at that point.
+*/
+static int btreeGetPage(
+  BtShared *pBt,       /* The btree */
+  Pgno pgno,           /* Number of the page to fetch */
+  MemPage **ppPage,    /* Return the page in this parameter */
+  int noContent        /* Do not load page content if true */
+){
+  int rc;
+  DbPage *pDbPage;
+
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  rc = sqlite3PagerAcquire(pBt->pPager, pgno, (DbPage**)&pDbPage, noContent);
+  if( rc ) return rc;
+  *ppPage = btreePageFromDbPage(pDbPage, pgno, pBt);
+  return SQLITE_OK;
+}
+
+/*
+** Retrieve a page from the pager cache. If the requested page is not
+** already in the pager cache return NULL. Initialize the MemPage.pBt and
+** MemPage.aData elements if needed.
+*/
+static MemPage *btreePageLookup(BtShared *pBt, Pgno pgno){
+  DbPage *pDbPage;
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  pDbPage = sqlite3PagerLookup(pBt->pPager, pgno);
+  if( pDbPage ){
+    return btreePageFromDbPage(pDbPage, pgno, pBt);
+  }
+  return 0;
+}
+
+/*
+** Return the size of the database file in pages. If there is any kind of
+** error, return ((unsigned int)-1).
+*/
+static Pgno btreePagecount(BtShared *pBt){
+  return pBt->nPage;
+}
+SQLITE_PRIVATE u32 sqlite3BtreeLastPage(Btree *p){
+  assert( sqlite3BtreeHoldsMutex(p) );
+  assert( ((p->pBt->nPage)&0x8000000)==0 );
+  return (int)btreePagecount(p->pBt);
+}
+
+/*
+** Get a page from the pager and initialize it.  This routine is just a
+** convenience wrapper around separate calls to btreeGetPage() and 
+** btreeInitPage().
+**
+** If an error occurs, then the value *ppPage is set to is undefined. It
+** may remain unchanged, or it may be set to an invalid value.
+*/
+static int getAndInitPage(
+  BtShared *pBt,          /* The database file */
+  Pgno pgno,           /* Number of the page to get */
+  MemPage **ppPage     /* Write the page pointer here */
+){
+  int rc;
+  assert( sqlite3_mutex_held(pBt->mutex) );
+
+  if( pgno>btreePagecount(pBt) ){
+    rc = SQLITE_CORRUPT_BKPT;
+  }else{
+    rc = btreeGetPage(pBt, pgno, ppPage, 0);
+    if( rc==SQLITE_OK ){
+      rc = btreeInitPage(*ppPage);
+      if( rc!=SQLITE_OK ){
+        releasePage(*ppPage);
+      }
+    }
+  }
+
+  testcase( pgno==0 );
+  assert( pgno!=0 || rc==SQLITE_CORRUPT );
+  return rc;
+}
+
+/*
+** Release a MemPage.  This should be called once for each prior
+** call to btreeGetPage.
+*/
+static void releasePage(MemPage *pPage){
+  if( pPage ){
+    assert( pPage->aData );
+    assert( pPage->pBt );
+    assert( sqlite3PagerGetExtra(pPage->pDbPage) == (void*)pPage );
+    assert( sqlite3PagerGetData(pPage->pDbPage)==pPage->aData );
+    assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+    sqlite3PagerUnref(pPage->pDbPage);
+  }
+}
+
+/*
+** During a rollback, when the pager reloads information into the cache
+** so that the cache is restored to its original state at the start of
+** the transaction, for each page restored this routine is called.
+**
+** This routine needs to reset the extra data section at the end of the
+** page to agree with the restored data.
+*/
+static void pageReinit(DbPage *pData){
+  MemPage *pPage;
+  pPage = (MemPage *)sqlite3PagerGetExtra(pData);
+  assert( sqlite3PagerPageRefcount(pData)>0 );
+  if( pPage->isInit ){
+    assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+    pPage->isInit = 0;
+    if( sqlite3PagerPageRefcount(pData)>1 ){
+      /* pPage might not be a btree page;  it might be an overflow page
+      ** or ptrmap page or a free page.  In those cases, the following
+      ** call to btreeInitPage() will likely return SQLITE_CORRUPT.
+      ** But no harm is done by this.  And it is very important that
+      ** btreeInitPage() be called on every btree page so we make
+      ** the call for every page that comes in for re-initing. */
+      btreeInitPage(pPage);
+    }
+  }
+}
+
+/*
+** Invoke the busy handler for a btree.
+*/
+static int btreeInvokeBusyHandler(void *pArg){
+  BtShared *pBt = (BtShared*)pArg;
+  assert( pBt->db );
+  assert( sqlite3_mutex_held(pBt->db->mutex) );
+  return sqlite3InvokeBusyHandler(&pBt->db->busyHandler);
+}
+
+/*
+** Open a database file.
+** 
+** zFilename is the name of the database file.  If zFilename is NULL
+** then an ephemeral database is created.  The ephemeral database might
+** be exclusively in memory, or it might use a disk-based memory cache.
+** Either way, the ephemeral database will be automatically deleted 
+** when sqlite3BtreeClose() is called.
+**
+** If zFilename is ":memory:" then an in-memory database is created
+** that is automatically destroyed when it is closed.
+**
+** The "flags" parameter is a bitmask that might contain bits
+** BTREE_OMIT_JOURNAL and/or BTREE_NO_READLOCK.  The BTREE_NO_READLOCK
+** bit is also set if the SQLITE_NoReadlock flags is set in db->flags.
+** These flags are passed through into sqlite3PagerOpen() and must
+** be the same values as PAGER_OMIT_JOURNAL and PAGER_NO_READLOCK.
+**
+** If the database is already opened in the same database connection
+** and we are in shared cache mode, then the open will fail with an
+** SQLITE_CONSTRAINT error.  We cannot allow two or more BtShared
+** objects in the same database connection since doing so will lead
+** to problems with locking.
+*/
+SQLITE_PRIVATE int sqlite3BtreeOpen(
+  const char *zFilename,  /* Name of the file containing the BTree database */
+  sqlite3 *db,            /* Associated database handle */
+  Btree **ppBtree,        /* Pointer to new Btree object written here */
+  int flags,              /* Options */
+  int vfsFlags            /* Flags passed through to sqlite3_vfs.xOpen() */
+){
+  sqlite3_vfs *pVfs;             /* The VFS to use for this btree */
+  BtShared *pBt = 0;             /* Shared part of btree structure */
+  Btree *p;                      /* Handle to return */
+  sqlite3_mutex *mutexOpen = 0;  /* Prevents a race condition. Ticket #3537 */
+  int rc = SQLITE_OK;            /* Result code from this function */
+  u8 nReserve;                   /* Byte of unused space on each page */
+  unsigned char zDbHeader[100];  /* Database header content */
+
+  /* True if opening an ephemeral, temporary database */
+  const int isTempDb = zFilename==0 || zFilename[0]==0;
+
+  /* Set the variable isMemdb to true for an in-memory database, or 
+  ** false for a file-based database.
+  */
+#ifdef SQLITE_OMIT_MEMORYDB
+  const int isMemdb = 0;
+#else
+  const int isMemdb = (zFilename && strcmp(zFilename, ":memory:")==0)
+                       || (isTempDb && sqlite3TempInMemory(db));
+#endif
+
+  assert( db!=0 );
+  assert( sqlite3_mutex_held(db->mutex) );
+  assert( (flags&0xff)==flags );   /* flags fit in 8 bits */
+
+  /* Only a BTREE_SINGLE database can be BTREE_UNORDERED */
+  assert( (flags & BTREE_UNORDERED)==0 || (flags & BTREE_SINGLE)!=0 );
+
+  /* A BTREE_SINGLE database is always a temporary and/or ephemeral */
+  assert( (flags & BTREE_SINGLE)==0 || isTempDb );
+
+  if( db->flags & SQLITE_NoReadlock ){
+    flags |= BTREE_NO_READLOCK;
+  }
+  if( isMemdb ){
+    flags |= BTREE_MEMORY;
+  }
+  if( (vfsFlags & SQLITE_OPEN_MAIN_DB)!=0 && (isMemdb || isTempDb) ){
+    vfsFlags = (vfsFlags & ~SQLITE_OPEN_MAIN_DB) | SQLITE_OPEN_TEMP_DB;
+  }
+  pVfs = db->pVfs;
+  p = sqlite3MallocZero(sizeof(Btree));
+  if( !p ){
+    return SQLITE_NOMEM;
+  }
+  p->inTrans = TRANS_NONE;
+  p->db = db;
+#ifndef SQLITE_OMIT_SHARED_CACHE
+  p->lock.pBtree = p;
+  p->lock.iTable = 1;
+#endif
+
+#if !defined(SQLITE_OMIT_SHARED_CACHE) && !defined(SQLITE_OMIT_DISKIO)
+  /*
+  ** If this Btree is a candidate for shared cache, try to find an
+  ** existing BtShared object that we can share with
+  */
+  if( isMemdb==0 && isTempDb==0 ){
+    if( vfsFlags & SQLITE_OPEN_SHAREDCACHE ){
+      int nFullPathname = pVfs->mxPathname+1;
+      char *zFullPathname = sqlite3Malloc(nFullPathname);
+      sqlite3_mutex *mutexShared;
+      p->sharable = 1;
+      if( !zFullPathname ){
+        sqlite3_free(p);
+        return SQLITE_NOMEM;
+      }
+      sqlite3OsFullPathname(pVfs, zFilename, nFullPathname, zFullPathname);
+      mutexOpen = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_OPEN);
+      sqlite3_mutex_enter(mutexOpen);
+      mutexShared = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
+      sqlite3_mutex_enter(mutexShared);
+      for(pBt=GLOBAL(BtShared*,sqlite3SharedCacheList); pBt; pBt=pBt->pNext){
+        assert( pBt->nRef>0 );
+        if( 0==strcmp(zFullPathname, sqlite3PagerFilename(pBt->pPager))
+                 && sqlite3PagerVfs(pBt->pPager)==pVfs ){
+          int iDb;
+          for(iDb=db->nDb-1; iDb>=0; iDb--){
+            Btree *pExisting = db->aDb[iDb].pBt;
+            if( pExisting && pExisting->pBt==pBt ){
+              sqlite3_mutex_leave(mutexShared);
+              sqlite3_mutex_leave(mutexOpen);
+              sqlite3_free(zFullPathname);
+              sqlite3_free(p);
+              return SQLITE_CONSTRAINT;
+            }
+          }
+          p->pBt = pBt;
+          pBt->nRef++;
+          break;
+        }
+      }
+      sqlite3_mutex_leave(mutexShared);
+      sqlite3_free(zFullPathname);
+    }
+#ifdef SQLITE_DEBUG
+    else{
+      /* In debug mode, we mark all persistent databases as sharable
+      ** even when they are not.  This exercises the locking code and
+      ** gives more opportunity for asserts(sqlite3_mutex_held())
+      ** statements to find locking problems.
+      */
+      p->sharable = 1;
+    }
+#endif
+  }
+#endif
+  if( pBt==0 ){
+    /*
+    ** The following asserts make sure that structures used by the btree are
+    ** the right size.  This is to guard against size changes that result
+    ** when compiling on a different architecture.
+    */
+    assert( sizeof(i64)==8 || sizeof(i64)==4 );
+    assert( sizeof(u64)==8 || sizeof(u64)==4 );
+    assert( sizeof(u32)==4 );
+    assert( sizeof(u16)==2 );
+    assert( sizeof(Pgno)==4 );
+  
+    pBt = sqlite3MallocZero( sizeof(*pBt) );
+    if( pBt==0 ){
+      rc = SQLITE_NOMEM;
+      goto btree_open_out;
+    }
+    rc = sqlite3PagerOpen(pVfs, &pBt->pPager, zFilename,
+                          EXTRA_SIZE, flags, vfsFlags, pageReinit);
+    if( rc==SQLITE_OK ){
+      rc = sqlite3PagerReadFileheader(pBt->pPager,sizeof(zDbHeader),zDbHeader);
+    }
+    if( rc!=SQLITE_OK ){
+      goto btree_open_out;
+    }
+    pBt->openFlags = (u8)flags;
+    pBt->db = db;
+    sqlite3PagerSetBusyhandler(pBt->pPager, btreeInvokeBusyHandler, pBt);
+    p->pBt = pBt;
+  
+    pBt->pCursor = 0;
+    pBt->pPage1 = 0;
+    pBt->readOnly = sqlite3PagerIsreadonly(pBt->pPager);
+#ifdef SQLITE_SECURE_DELETE
+    pBt->secureDelete = 1;
+#endif
+    pBt->pageSize = (zDbHeader[16]<<8) | (zDbHeader[17]<<16);
+    if( pBt->pageSize<512 || pBt->pageSize>SQLITE_MAX_PAGE_SIZE
+         || ((pBt->pageSize-1)&pBt->pageSize)!=0 ){
+      pBt->pageSize = 0;
+#ifndef SQLITE_OMIT_AUTOVACUUM
+      /* If the magic name ":memory:" will create an in-memory database, then
+      ** leave the autoVacuum mode at 0 (do not auto-vacuum), even if
+      ** SQLITE_DEFAULT_AUTOVACUUM is true. On the other hand, if
+      ** SQLITE_OMIT_MEMORYDB has been defined, then ":memory:" is just a
+      ** regular file-name. In this case the auto-vacuum applies as per normal.
+      */
+      if( zFilename && !isMemdb ){
+        pBt->autoVacuum = (SQLITE_DEFAULT_AUTOVACUUM ? 1 : 0);
+        pBt->incrVacuum = (SQLITE_DEFAULT_AUTOVACUUM==2 ? 1 : 0);
+      }
+#endif
+      nReserve = 0;
+    }else{
+      nReserve = zDbHeader[20];
+      pBt->pageSizeFixed = 1;
+#ifndef SQLITE_OMIT_AUTOVACUUM
+      pBt->autoVacuum = (get4byte(&zDbHeader[36 + 4*4])?1:0);
+      pBt->incrVacuum = (get4byte(&zDbHeader[36 + 7*4])?1:0);
+#endif
+    }
+    rc = sqlite3PagerSetPagesize(pBt->pPager, &pBt->pageSize, nReserve);
+    if( rc ) goto btree_open_out;
+    pBt->usableSize = pBt->pageSize - nReserve;
+    assert( (pBt->pageSize & 7)==0 );  /* 8-byte alignment of pageSize */
+   
+#if !defined(SQLITE_OMIT_SHARED_CACHE) && !defined(SQLITE_OMIT_DISKIO)
+    /* Add the new BtShared object to the linked list sharable BtShareds.
+    */
+    if( p->sharable ){
+      sqlite3_mutex *mutexShared;
+      pBt->nRef = 1;
+      mutexShared = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
+      if( SQLITE_THREADSAFE && sqlite3GlobalConfig.bCoreMutex ){
+        pBt->mutex = sqlite3MutexAlloc(SQLITE_MUTEX_FAST);
+        if( pBt->mutex==0 ){
+          rc = SQLITE_NOMEM;
+          db->mallocFailed = 0;
+          goto btree_open_out;
+        }
+      }
+      sqlite3_mutex_enter(mutexShared);
+      pBt->pNext = GLOBAL(BtShared*,sqlite3SharedCacheList);
+      GLOBAL(BtShared*,sqlite3SharedCacheList) = pBt;
+      sqlite3_mutex_leave(mutexShared);
+    }
+#endif
+  }
+
+#if !defined(SQLITE_OMIT_SHARED_CACHE) && !defined(SQLITE_OMIT_DISKIO)
+  /* If the new Btree uses a sharable pBtShared, then link the new
+  ** Btree into the list of all sharable Btrees for the same connection.
+  ** The list is kept in ascending order by pBt address.
+  */
+  if( p->sharable ){
+    int i;
+    Btree *pSib;
+    for(i=0; i<db->nDb; i++){
+      if( (pSib = db->aDb[i].pBt)!=0 && pSib->sharable ){
+        while( pSib->pPrev ){ pSib = pSib->pPrev; }
+        if( p->pBt<pSib->pBt ){
+          p->pNext = pSib;
+          p->pPrev = 0;
+          pSib->pPrev = p;
+        }else{
+          while( pSib->pNext && pSib->pNext->pBt<p->pBt ){
+            pSib = pSib->pNext;
+          }
+          p->pNext = pSib->pNext;
+          p->pPrev = pSib;
+          if( p->pNext ){
+            p->pNext->pPrev = p;
+          }
+          pSib->pNext = p;
+        }
+        break;
+      }
+    }
+  }
+#endif
+  *ppBtree = p;
+
+btree_open_out:
+  if( rc!=SQLITE_OK ){
+    if( pBt && pBt->pPager ){
+      sqlite3PagerClose(pBt->pPager);
+    }
+    sqlite3_free(pBt);
+    sqlite3_free(p);
+    *ppBtree = 0;
+  }else{
+    /* If the B-Tree was successfully opened, set the pager-cache size to the
+    ** default value. Except, when opening on an existing shared pager-cache,
+    ** do not change the pager-cache size.
+    */
+    if( sqlite3BtreeSchema(p, 0, 0)==0 ){
+      sqlite3PagerSetCachesize(p->pBt->pPager, SQLITE_DEFAULT_CACHE_SIZE);
+    }
+  }
+  if( mutexOpen ){
+    assert( sqlite3_mutex_held(mutexOpen) );
+    sqlite3_mutex_leave(mutexOpen);
+  }
+  return rc;
+}
+
+/*
+** Decrement the BtShared.nRef counter.  When it reaches zero,
+** remove the BtShared structure from the sharing list.  Return
+** true if the BtShared.nRef counter reaches zero and return
+** false if it is still positive.
+*/
+static int removeFromSharingList(BtShared *pBt){
+#ifndef SQLITE_OMIT_SHARED_CACHE
+  sqlite3_mutex *pMaster;
+  BtShared *pList;
+  int removed = 0;
+
+  assert( sqlite3_mutex_notheld(pBt->mutex) );
+  pMaster = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
+  sqlite3_mutex_enter(pMaster);
+  pBt->nRef--;
+  if( pBt->nRef<=0 ){
+    if( GLOBAL(BtShared*,sqlite3SharedCacheList)==pBt ){
+      GLOBAL(BtShared*,sqlite3SharedCacheList) = pBt->pNext;
+    }else{
+      pList = GLOBAL(BtShared*,sqlite3SharedCacheList);
+      while( ALWAYS(pList) && pList->pNext!=pBt ){
+        pList=pList->pNext;
+      }
+      if( ALWAYS(pList) ){
+        pList->pNext = pBt->pNext;
+      }
+    }
+    if( SQLITE_THREADSAFE ){
+      sqlite3_mutex_free(pBt->mutex);
+    }
+    removed = 1;
+  }
+  sqlite3_mutex_leave(pMaster);
+  return removed;
+#else
+  return 1;
+#endif
+}
+
+/*
+** Make sure pBt->pTmpSpace points to an allocation of 
+** MX_CELL_SIZE(pBt) bytes.
+*/
+static void allocateTempSpace(BtShared *pBt){
+  if( !pBt->pTmpSpace ){
+    pBt->pTmpSpace = sqlite3PageMalloc( pBt->pageSize );
+  }
+}
+
+/*
+** Free the pBt->pTmpSpace allocation
+*/
+static void freeTempSpace(BtShared *pBt){
+  sqlite3PageFree( pBt->pTmpSpace);
+  pBt->pTmpSpace = 0;
+}
+
+/*
+** Close an open database and invalidate all cursors.
+*/
+SQLITE_PRIVATE int sqlite3BtreeClose(Btree *p){
+  BtShared *pBt = p->pBt;
+  BtCursor *pCur;
+
+  /* Close all cursors opened via this handle.  */
+  assert( sqlite3_mutex_held(p->db->mutex) );
+  sqlite3BtreeEnter(p);
+  pCur = pBt->pCursor;
+  while( pCur ){
+    BtCursor *pTmp = pCur;
+    pCur = pCur->pNext;
+    if( pTmp->pBtree==p ){
+      sqlite3BtreeCloseCursor(pTmp);
+    }
+  }
+
+  /* Rollback any active transaction and free the handle structure.
+  ** The call to sqlite3BtreeRollback() drops any table-locks held by
+  ** this handle.
+  */
+  sqlite3BtreeRollback(p);
+  sqlite3BtreeLeave(p);
+
+  /* If there are still other outstanding references to the shared-btree
+  ** structure, return now. The remainder of this procedure cleans 
+  ** up the shared-btree.
+  */
+  assert( p->wantToLock==0 && p->locked==0 );
+  if( !p->sharable || removeFromSharingList(pBt) ){
+    /* The pBt is no longer on the sharing list, so we can access
+    ** it without having to hold the mutex.
+    **
+    ** Clean out and delete the BtShared object.
+    */
+    assert( !pBt->pCursor );
+    sqlite3PagerClose(pBt->pPager);
+    if( pBt->xFreeSchema && pBt->pSchema ){
+      pBt->xFreeSchema(pBt->pSchema);
+    }
+    sqlite3DbFree(0, pBt->pSchema);
+    freeTempSpace(pBt);
+    sqlite3_free(pBt);
+  }
+
+#ifndef SQLITE_OMIT_SHARED_CACHE
+  assert( p->wantToLock==0 );
+  assert( p->locked==0 );
+  if( p->pPrev ) p->pPrev->pNext = p->pNext;
+  if( p->pNext ) p->pNext->pPrev = p->pPrev;
+#endif
+
+  sqlite3_free(p);
+  return SQLITE_OK;
+}
+
+/*
+** Change the limit on the number of pages allowed in the cache.
+**
+** The maximum number of cache pages is set to the absolute
+** value of mxPage.  If mxPage is negative, the pager will
+** operate asynchronously - it will not stop to do fsync()s
+** to insure data is written to the disk surface before
+** continuing.  Transactions still work if synchronous is off,
+** and the database cannot be corrupted if this program
+** crashes.  But if the operating system crashes or there is
+** an abrupt power failure when synchronous is off, the database
+** could be left in an inconsistent and unrecoverable state.
+** Synchronous is on by default so database corruption is not
+** normally a worry.
+*/
+SQLITE_PRIVATE int sqlite3BtreeSetCacheSize(Btree *p, int mxPage){
+  BtShared *pBt = p->pBt;
+  assert( sqlite3_mutex_held(p->db->mutex) );
+  sqlite3BtreeEnter(p);
+  sqlite3PagerSetCachesize(pBt->pPager, mxPage);
+  sqlite3BtreeLeave(p);
+  return SQLITE_OK;
+}
+
+/*
+** Change the way data is synced to disk in order to increase or decrease
+** how well the database resists damage due to OS crashes and power
+** failures.  Level 1 is the same as asynchronous (no syncs() occur and
+** there is a high probability of damage)  Level 2 is the default.  There
+** is a very low but non-zero probability of damage.  Level 3 reduces the
+** probability of damage to near zero but with a write performance reduction.
+*/
+#ifndef SQLITE_OMIT_PAGER_PRAGMAS
+SQLITE_PRIVATE int sqlite3BtreeSetSafetyLevel(
+  Btree *p,              /* The btree to set the safety level on */
+  int level,             /* PRAGMA synchronous.  1=OFF, 2=NORMAL, 3=FULL */
+  int fullSync,          /* PRAGMA fullfsync. */
+  int ckptFullSync       /* PRAGMA checkpoint_fullfync */
+){
+  BtShared *pBt = p->pBt;
+  assert( sqlite3_mutex_held(p->db->mutex) );
+  assert( level>=1 && level<=3 );
+  sqlite3BtreeEnter(p);
+  sqlite3PagerSetSafetyLevel(pBt->pPager, level, fullSync, ckptFullSync);
+  sqlite3BtreeLeave(p);
+  return SQLITE_OK;
+}
+#endif
+
+/*
+** Return TRUE if the given btree is set to safety level 1.  In other
+** words, return TRUE if no sync() occurs on the disk files.
+*/
+SQLITE_PRIVATE int sqlite3BtreeSyncDisabled(Btree *p){
+  BtShared *pBt = p->pBt;
+  int rc;
+  assert( sqlite3_mutex_held(p->db->mutex) );  
+  sqlite3BtreeEnter(p);
+  assert( pBt && pBt->pPager );
+  rc = sqlite3PagerNosync(pBt->pPager);
+  sqlite3BtreeLeave(p);
+  return rc;
+}
+
+/*
+** Change the default pages size and the number of reserved bytes per page.
+** Or, if the page size has already been fixed, return SQLITE_READONLY 
+** without changing anything.
+**
+** The page size must be a power of 2 between 512 and 65536.  If the page
+** size supplied does not meet this constraint then the page size is not
+** changed.
+**
+** Page sizes are constrained to be a power of two so that the region
+** of the database file used for locking (beginning at PENDING_BYTE,
+** the first byte past the 1GB boundary, 0x40000000) needs to occur
+** at the beginning of a page.
+**
+** If parameter nReserve is less than zero, then the number of reserved
+** bytes per page is left unchanged.
+**
+** If the iFix!=0 then the pageSizeFixed flag is set so that the page size
+** and autovacuum mode can no longer be changed.
+*/
+SQLITE_PRIVATE int sqlite3BtreeSetPageSize(Btree *p, int pageSize, int nReserve, int iFix){
+  int rc = SQLITE_OK;
+  BtShared *pBt = p->pBt;
+  assert( nReserve>=-1 && nReserve<=255 );
+  sqlite3BtreeEnter(p);
+  if( pBt->pageSizeFixed ){
+    sqlite3BtreeLeave(p);
+    return SQLITE_READONLY;
+  }
+  if( nReserve<0 ){
+    nReserve = pBt->pageSize - pBt->usableSize;
+  }
+  assert( nReserve>=0 && nReserve<=255 );
+  if( pageSize>=512 && pageSize<=SQLITE_MAX_PAGE_SIZE &&
+        ((pageSize-1)&pageSize)==0 ){
+    assert( (pageSize & 7)==0 );
+    assert( !pBt->pPage1 && !pBt->pCursor );
+    pBt->pageSize = (u32)pageSize;
+    freeTempSpace(pBt);
+  }
+  rc = sqlite3PagerSetPagesize(pBt->pPager, &pBt->pageSize, nReserve);
+  pBt->usableSize = pBt->pageSize - (u16)nReserve;
+  if( iFix ) pBt->pageSizeFixed = 1;
+  sqlite3BtreeLeave(p);
+  return rc;
+}
+
+/*
+** Return the currently defined page size
+*/
+SQLITE_PRIVATE int sqlite3BtreeGetPageSize(Btree *p){
+  return p->pBt->pageSize;
+}
+
+#if !defined(SQLITE_OMIT_PAGER_PRAGMAS) || !defined(SQLITE_OMIT_VACUUM)
+/*
+** Return the number of bytes of space at the end of every page that
+** are intentually left unused.  This is the "reserved" space that is
+** sometimes used by extensions.
+*/
+SQLITE_PRIVATE int sqlite3BtreeGetReserve(Btree *p){
+  int n;
+  sqlite3BtreeEnter(p);
+  n = p->pBt->pageSize - p->pBt->usableSize;
+  sqlite3BtreeLeave(p);
+  return n;
+}
+
+/*
+** Set the maximum page count for a database if mxPage is positive.
+** No changes are made if mxPage is 0 or negative.
+** Regardless of the value of mxPage, return the maximum page count.
+*/
+SQLITE_PRIVATE int sqlite3BtreeMaxPageCount(Btree *p, int mxPage){
+  int n;
+  sqlite3BtreeEnter(p);
+  n = sqlite3PagerMaxPageCount(p->pBt->pPager, mxPage);
+  sqlite3BtreeLeave(p);
+  return n;
+}
+
+/*
+** Set the secureDelete flag if newFlag is 0 or 1.  If newFlag is -1,
+** then make no changes.  Always return the value of the secureDelete
+** setting after the change.
+*/
+SQLITE_PRIVATE int sqlite3BtreeSecureDelete(Btree *p, int newFlag){
+  int b;
+  if( p==0 ) return 0;
+  sqlite3BtreeEnter(p);
+  if( newFlag>=0 ){
+    p->pBt->secureDelete = (newFlag!=0) ? 1 : 0;
+  } 
+  b = p->pBt->secureDelete;
+  sqlite3BtreeLeave(p);
+  return b;
+}
+#endif /* !defined(SQLITE_OMIT_PAGER_PRAGMAS) || !defined(SQLITE_OMIT_VACUUM) */
+
+/*
+** Change the 'auto-vacuum' property of the database. If the 'autoVacuum'
+** parameter is non-zero, then auto-vacuum mode is enabled. If zero, it
+** is disabled. The default value for the auto-vacuum property is 
+** determined by the SQLITE_DEFAULT_AUTOVACUUM macro.
+*/
+SQLITE_PRIVATE int sqlite3BtreeSetAutoVacuum(Btree *p, int autoVacuum){
+#ifdef SQLITE_OMIT_AUTOVACUUM
+  return SQLITE_READONLY;
+#else
+  BtShared *pBt = p->pBt;
+  int rc = SQLITE_OK;
+  u8 av = (u8)autoVacuum;
+
+  sqlite3BtreeEnter(p);
+  if( pBt->pageSizeFixed && (av ?1:0)!=pBt->autoVacuum ){
+    rc = SQLITE_READONLY;
+  }else{
+    pBt->autoVacuum = av ?1:0;
+    pBt->incrVacuum = av==2 ?1:0;
+  }
+  sqlite3BtreeLeave(p);
+  return rc;
+#endif
+}
+
+/*
+** Return the value of the 'auto-vacuum' property. If auto-vacuum is 
+** enabled 1 is returned. Otherwise 0.
+*/
+SQLITE_PRIVATE int sqlite3BtreeGetAutoVacuum(Btree *p){
+#ifdef SQLITE_OMIT_AUTOVACUUM
+  return BTREE_AUTOVACUUM_NONE;
+#else
+  int rc;
+  sqlite3BtreeEnter(p);
+  rc = (
+    (!p->pBt->autoVacuum)?BTREE_AUTOVACUUM_NONE:
+    (!p->pBt->incrVacuum)?BTREE_AUTOVACUUM_FULL:
+    BTREE_AUTOVACUUM_INCR
+  );
+  sqlite3BtreeLeave(p);
+  return rc;
+#endif
+}
+
+
+/*
+** Get a reference to pPage1 of the database file.  This will
+** also acquire a readlock on that file.
+**
+** SQLITE_OK is returned on success.  If the file is not a
+** well-formed database file, then SQLITE_CORRUPT is returned.
+** SQLITE_BUSY is returned if the database is locked.  SQLITE_NOMEM
+** is returned if we run out of memory. 
+*/
+static int lockBtree(BtShared *pBt){
+  int rc;              /* Result code from subfunctions */
+  MemPage *pPage1;     /* Page 1 of the database file */
+  int nPage;           /* Number of pages in the database */
+  int nPageFile = 0;   /* Number of pages in the database file */
+  int nPageHeader;     /* Number of pages in the database according to hdr */
+
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  assert( pBt->pPage1==0 );
+  rc = sqlite3PagerSharedLock(pBt->pPager);
+  if( rc!=SQLITE_OK ) return rc;
+  rc = btreeGetPage(pBt, 1, &pPage1, 0);
+  if( rc!=SQLITE_OK ) return rc;
+
+  /* Do some checking to help insure the file we opened really is
+  ** a valid database file. 
+  */
+  nPage = nPageHeader = get4byte(28+(u8*)pPage1->aData);
+  sqlite3PagerPagecount(pBt->pPager, &nPageFile);
+  if( nPage==0 || memcmp(24+(u8*)pPage1->aData, 92+(u8*)pPage1->aData,4)!=0 ){
+    nPage = nPageFile;
+  }
+  if( nPage>0 ){
+    u32 pageSize;
+    u32 usableSize;
+    u8 *page1 = pPage1->aData;
+    rc = SQLITE_NOTADB;
+    if( memcmp(page1, zMagicHeader, 16)!=0 ){
+      goto page1_init_failed;
+    }
+
+#ifdef SQLITE_OMIT_WAL
+    if( page1[18]>1 ){
+      pBt->readOnly = 1;
+    }
+    if( page1[19]>1 ){
+      goto page1_init_failed;
+    }
+#else
+    if( page1[18]>2 ){
+      pBt->readOnly = 1;
+    }
+    if( page1[19]>2 ){
+      goto page1_init_failed;
+    }
+
+    /* If the write version is set to 2, this database should be accessed
+    ** in WAL mode. If the log is not already open, open it now. Then 
+    ** return SQLITE_OK and return without populating BtShared.pPage1.
+    ** The caller detects this and calls this function again. This is
+    ** required as the version of page 1 currently in the page1 buffer
+    ** may not be the latest version - there may be a newer one in the log
+    ** file.
+    */
+    if( page1[19]==2 && pBt->doNotUseWAL==0 ){
+      int isOpen = 0;
+      rc = sqlite3PagerOpenWal(pBt->pPager, &isOpen);
+      if( rc!=SQLITE_OK ){
+        goto page1_init_failed;
+      }else if( isOpen==0 ){
+        releasePage(pPage1);
+        return SQLITE_OK;
+      }
+      rc = SQLITE_NOTADB;
+    }
+#endif
+
+    /* The maximum embedded fraction must be exactly 25%.  And the minimum
+    ** embedded fraction must be 12.5% for both leaf-data and non-leaf-data.
+    ** The original design allowed these amounts to vary, but as of
+    ** version 3.6.0, we require them to be fixed.
+    */
+    if( memcmp(&page1[21], "\100\040\040",3)!=0 ){
+      goto page1_init_failed;
+    }
+    pageSize = (page1[16]<<8) | (page1[17]<<16);
+    if( ((pageSize-1)&pageSize)!=0
+     || pageSize>SQLITE_MAX_PAGE_SIZE 
+     || pageSize<=256 
+    ){
+      goto page1_init_failed;
+    }
+    assert( (pageSize & 7)==0 );
+    usableSize = pageSize - page1[20];
+    if( (u32)pageSize!=pBt->pageSize ){
+      /* After reading the first page of the database assuming a page size
+      ** of BtShared.pageSize, we have discovered that the page-size is
+      ** actually pageSize. Unlock the database, leave pBt->pPage1 at
+      ** zero and return SQLITE_OK. The caller will call this function
+      ** again with the correct page-size.
+      */
+      releasePage(pPage1);
+      pBt->usableSize = usableSize;
+      pBt->pageSize = pageSize;
+      freeTempSpace(pBt);
+      rc = sqlite3PagerSetPagesize(pBt->pPager, &pBt->pageSize,
+                                   pageSize-usableSize);
+      return rc;
+    }
+    if( (pBt->db->flags & SQLITE_RecoveryMode)==0 && nPage>nPageFile ){
+      rc = SQLITE_CORRUPT_BKPT;
+      goto page1_init_failed;
+    }
+    if( usableSize<480 ){
+      goto page1_init_failed;
+    }
+    pBt->pageSize = pageSize;
+    pBt->usableSize = usableSize;
+#ifndef SQLITE_OMIT_AUTOVACUUM
+    pBt->autoVacuum = (get4byte(&page1[36 + 4*4])?1:0);
+    pBt->incrVacuum = (get4byte(&page1[36 + 7*4])?1:0);
+#endif
+  }
+
+  /* maxLocal is the maximum amount of payload to store locally for
+  ** a cell.  Make sure it is small enough so that at least minFanout
+  ** cells can will fit on one page.  We assume a 10-byte page header.
+  ** Besides the payload, the cell must store:
+  **     2-byte pointer to the cell
+  **     4-byte child pointer
+  **     9-byte nKey value
+  **     4-byte nData value
+  **     4-byte overflow page pointer
+  ** So a cell consists of a 2-byte pointer, a header which is as much as
+  ** 17 bytes long, 0 to N bytes of payload, and an optional 4 byte overflow
+  ** page pointer.
+  */
+  pBt->maxLocal = (u16)((pBt->usableSize-12)*64/255 - 23);
+  pBt->minLocal = (u16)((pBt->usableSize-12)*32/255 - 23);
+  pBt->maxLeaf = (u16)(pBt->usableSize - 35);
+  pBt->minLeaf = (u16)((pBt->usableSize-12)*32/255 - 23);
+  assert( pBt->maxLeaf + 23 <= MX_CELL_SIZE(pBt) );
+  pBt->pPage1 = pPage1;
+  pBt->nPage = nPage;
+  return SQLITE_OK;
+
+page1_init_failed:
+  releasePage(pPage1);
+  pBt->pPage1 = 0;
+  return rc;
+}
+
+/*
+** If there are no outstanding cursors and we are not in the middle
+** of a transaction but there is a read lock on the database, then
+** this routine unrefs the first page of the database file which 
+** has the effect of releasing the read lock.
+**
+** If there is a transaction in progress, this routine is a no-op.
+*/
+static void unlockBtreeIfUnused(BtShared *pBt){
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  assert( pBt->pCursor==0 || pBt->inTransaction>TRANS_NONE );
+  if( pBt->inTransaction==TRANS_NONE && pBt->pPage1!=0 ){
+    assert( pBt->pPage1->aData );
+    assert( sqlite3PagerRefcount(pBt->pPager)==1 );
+    assert( pBt->pPage1->aData );
+    releasePage(pBt->pPage1);
+    pBt->pPage1 = 0;
+  }
+}
+
+/*
+** If pBt points to an empty file then convert that empty file
+** into a new empty database by initializing the first page of
+** the database.
+*/
+static int newDatabase(BtShared *pBt){
+  MemPage *pP1;
+  unsigned char *data;
+  int rc;
+
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  if( pBt->nPage>0 ){
+    return SQLITE_OK;
+  }
+  pP1 = pBt->pPage1;
+  assert( pP1!=0 );
+  data = pP1->aData;
+  rc = sqlite3PagerWrite(pP1->pDbPage);
+  if( rc ) return rc;
+  memcpy(data, zMagicHeader, sizeof(zMagicHeader));
+  assert( sizeof(zMagicHeader)==16 );
+  data[16] = (u8)((pBt->pageSize>>8)&0xff);
+  data[17] = (u8)((pBt->pageSize>>16)&0xff);
+  data[18] = 1;
+  data[19] = 1;
+  assert( pBt->usableSize<=pBt->pageSize && pBt->usableSize+255>=pBt->pageSize);
+  data[20] = (u8)(pBt->pageSize - pBt->usableSize);
+  data[21] = 64;
+  data[22] = 32;
+  data[23] = 32;
+  memset(&data[24], 0, 100-24);
+  zeroPage(pP1, PTF_INTKEY|PTF_LEAF|PTF_LEAFDATA );
+  pBt->pageSizeFixed = 1;
+#ifndef SQLITE_OMIT_AUTOVACUUM
+  assert( pBt->autoVacuum==1 || pBt->autoVacuum==0 );
+  assert( pBt->incrVacuum==1 || pBt->incrVacuum==0 );
+  put4byte(&data[36 + 4*4], pBt->autoVacuum);
+  put4byte(&data[36 + 7*4], pBt->incrVacuum);
+#endif
+  pBt->nPage = 1;
+  data[31] = 1;
+  return SQLITE_OK;
+}
+
+/*
+** Attempt to start a new transaction. A write-transaction
+** is started if the second argument is nonzero, otherwise a read-
+** transaction.  If the second argument is 2 or more and exclusive
+** transaction is started, meaning that no other process is allowed
+** to access the database.  A preexisting transaction may not be
+** upgraded to exclusive by calling this routine a second time - the
+** exclusivity flag only works for a new transaction.
+**
+** A write-transaction must be started before attempting any 
+** changes to the database.  None of the following routines 
+** will work unless a transaction is started first:
+**
+**      sqlite3BtreeCreateTable()
+**      sqlite3BtreeCreateIndex()
+**      sqlite3BtreeClearTable()
+**      sqlite3BtreeDropTable()
+**      sqlite3BtreeInsert()
+**      sqlite3BtreeDelete()
+**      sqlite3BtreeUpdateMeta()
+**
+** If an initial attempt to acquire the lock fails because of lock contention
+** and the database was previously unlocked, then invoke the busy handler
+** if there is one.  But if there was previously a read-lock, do not
+** invoke the busy handler - just return SQLITE_BUSY.  SQLITE_BUSY is 
+** returned when there is already a read-lock in order to avoid a deadlock.
+**
+** Suppose there are two processes A and B.  A has a read lock and B has
+** a reserved lock.  B tries to promote to exclusive but is blocked because
+** of A's read lock.  A tries to promote to reserved but is blocked by B.
+** One or the other of the two processes must give way or there can be
+** no progress.  By returning SQLITE_BUSY and not invoking the busy callback
+** when A already has a read lock, we encourage A to give up and let B
+** proceed.
+*/
+SQLITE_PRIVATE int sqlite3BtreeBeginTrans(Btree *p, int wrflag){
+  sqlite3 *pBlock = 0;
+  BtShared *pBt = p->pBt;
+  int rc = SQLITE_OK;
+
+  sqlite3BtreeEnter(p);
+  btreeIntegrity(p);
+
+  /* If the btree is already in a write-transaction, or it
+  ** is already in a read-transaction and a read-transaction
+  ** is requested, this is a no-op.
+  */
+  if( p->inTrans==TRANS_WRITE || (p->inTrans==TRANS_READ && !wrflag) ){
+    goto trans_begun;
+  }
+
+  /* Write transactions are not possible on a read-only database */
+  if( pBt->readOnly && wrflag ){
+    rc = SQLITE_READONLY;
+    goto trans_begun;
+  }
+
+#ifndef SQLITE_OMIT_SHARED_CACHE
+  /* If another database handle has already opened a write transaction 
+  ** on this shared-btree structure and a second write transaction is
+  ** requested, return SQLITE_LOCKED.
+  */
+  if( (wrflag && pBt->inTransaction==TRANS_WRITE) || pBt->isPending ){
+    pBlock = pBt->pWriter->db;
+  }else if( wrflag>1 ){
+    BtLock *pIter;
+    for(pIter=pBt->pLock; pIter; pIter=pIter->pNext){
+      if( pIter->pBtree!=p ){
+        pBlock = pIter->pBtree->db;
+        break;
+      }
+    }
+  }
+  if( pBlock ){
+    sqlite3ConnectionBlocked(p->db, pBlock);
+    rc = SQLITE_LOCKED_SHAREDCACHE;
+    goto trans_begun;
+  }
+#endif
+
+  /* Any read-only or read-write transaction implies a read-lock on 
+  ** page 1. So if some other shared-cache client already has a write-lock 
+  ** on page 1, the transaction cannot be opened. */
+  rc = querySharedCacheTableLock(p, MASTER_ROOT, READ_LOCK);
+  if( SQLITE_OK!=rc ) goto trans_begun;
+
+  pBt->initiallyEmpty = (u8)(pBt->nPage==0);
+  do {
+    /* Call lockBtree() until either pBt->pPage1 is populated or
+    ** lockBtree() returns something other than SQLITE_OK. lockBtree()
+    ** may return SQLITE_OK but leave pBt->pPage1 set to 0 if after
+    ** reading page 1 it discovers that the page-size of the database 
+    ** file is not pBt->pageSize. In this case lockBtree() will update
+    ** pBt->pageSize to the page-size of the file on disk.
+    */
+    while( pBt->pPage1==0 && SQLITE_OK==(rc = lockBtree(pBt)) );
+
+    if( rc==SQLITE_OK && wrflag ){
+      if( pBt->readOnly ){
+        rc = SQLITE_READONLY;
+      }else{
+        rc = sqlite3PagerBegin(pBt->pPager,wrflag>1,sqlite3TempInMemory(p->db));
+        if( rc==SQLITE_OK ){
+          rc = newDatabase(pBt);
+        }
+      }
+    }
+  
+    if( rc!=SQLITE_OK ){
+      unlockBtreeIfUnused(pBt);
+    }
+  }while( (rc&0xFF)==SQLITE_BUSY && pBt->inTransaction==TRANS_NONE &&
+          btreeInvokeBusyHandler(pBt) );
+
+  if( rc==SQLITE_OK ){
+    if( p->inTrans==TRANS_NONE ){
+      pBt->nTransaction++;
+#ifndef SQLITE_OMIT_SHARED_CACHE
+      if( p->sharable ){
+	assert( p->lock.pBtree==p && p->lock.iTable==1 );
+        p->lock.eLock = READ_LOCK;
+        p->lock.pNext = pBt->pLock;
+        pBt->pLock = &p->lock;
+      }
+#endif
+    }
+    p->inTrans = (wrflag?TRANS_WRITE:TRANS_READ);
+    if( p->inTrans>pBt->inTransaction ){
+      pBt->inTransaction = p->inTrans;
+    }
+    if( wrflag ){
+      MemPage *pPage1 = pBt->pPage1;
+#ifndef SQLITE_OMIT_SHARED_CACHE
+      assert( !pBt->pWriter );
+      pBt->pWriter = p;
+      pBt->isExclusive = (u8)(wrflag>1);
+#endif
+
+      /* If the db-size header field is incorrect (as it may be if an old
+      ** client has been writing the database file), update it now. Doing
+      ** this sooner rather than later means the database size can safely 
+      ** re-read the database size from page 1 if a savepoint or transaction
+      ** rollback occurs within the transaction.
+      */
+      if( pBt->nPage!=get4byte(&pPage1->aData[28]) ){
+        rc = sqlite3PagerWrite(pPage1->pDbPage);
+        if( rc==SQLITE_OK ){
+          put4byte(&pPage1->aData[28], pBt->nPage);
+        }
+      }
+    }
+  }
+
+
+trans_begun:
+  if( rc==SQLITE_OK && wrflag ){
+    /* This call makes sure that the pager has the correct number of
+    ** open savepoints. If the second parameter is greater than 0 and
+    ** the sub-journal is not already open, then it will be opened here.
+    */
+    rc = sqlite3PagerOpenSavepoint(pBt->pPager, p->db->nSavepoint);
+  }
+
+  btreeIntegrity(p);
+  sqlite3BtreeLeave(p);
+  return rc;
+}
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+
+/*
+** Set the pointer-map entries for all children of page pPage. Also, if
+** pPage contains cells that point to overflow pages, set the pointer
+** map entries for the overflow pages as well.
+*/
+static int setChildPtrmaps(MemPage *pPage){
+  int i;                             /* Counter variable */
+  int nCell;                         /* Number of cells in page pPage */
+  int rc;                            /* Return code */
+  BtShared *pBt = pPage->pBt;
+  u8 isInitOrig = pPage->isInit;
+  Pgno pgno = pPage->pgno;
+
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  rc = btreeInitPage(pPage);
+  if( rc!=SQLITE_OK ){
+    goto set_child_ptrmaps_out;
+  }
+  nCell = pPage->nCell;
+
+  for(i=0; i<nCell; i++){
+    u8 *pCell = findCell(pPage, i);
+
+    ptrmapPutOvflPtr(pPage, pCell, &rc);
+
+    if( !pPage->leaf ){
+      Pgno childPgno = get4byte(pCell);
+      ptrmapPut(pBt, childPgno, PTRMAP_BTREE, pgno, &rc);
+    }
+  }
+
+  if( !pPage->leaf ){
+    Pgno childPgno = get4byte(&pPage->aData[pPage->hdrOffset+8]);
+    ptrmapPut(pBt, childPgno, PTRMAP_BTREE, pgno, &rc);
+  }
+
+set_child_ptrmaps_out:
+  pPage->isInit = isInitOrig;
+  return rc;
+}
+
+/*
+** Somewhere on pPage is a pointer to page iFrom.  Modify this pointer so
+** that it points to iTo. Parameter eType describes the type of pointer to
+** be modified, as  follows:
+**
+** PTRMAP_BTREE:     pPage is a btree-page. The pointer points at a child 
+**                   page of pPage.
+**
+** PTRMAP_OVERFLOW1: pPage is a btree-page. The pointer points at an overflow
+**                   page pointed to by one of the cells on pPage.
+**
+** PTRMAP_OVERFLOW2: pPage is an overflow-page. The pointer points at the next
+**                   overflow page in the list.
+*/
+static int modifyPagePointer(MemPage *pPage, Pgno iFrom, Pgno iTo, u8 eType){
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
+  if( eType==PTRMAP_OVERFLOW2 ){
+    /* The pointer is always the first 4 bytes of the page in this case.  */
+    if( get4byte(pPage->aData)!=iFrom ){
+      return SQLITE_CORRUPT_BKPT;
+    }
+    put4byte(pPage->aData, iTo);
+  }else{
+    u8 isInitOrig = pPage->isInit;
+    int i;
+    int nCell;
+
+    btreeInitPage(pPage);
+    nCell = pPage->nCell;
+
+    for(i=0; i<nCell; i++){
+      u8 *pCell = findCell(pPage, i);
+      if( eType==PTRMAP_OVERFLOW1 ){
+        CellInfo info;
+        btreeParseCellPtr(pPage, pCell, &info);
+        if( info.iOverflow ){
+          if( iFrom==get4byte(&pCell[info.iOverflow]) ){
+            put4byte(&pCell[info.iOverflow], iTo);
+            break;
+          }
+        }
+      }else{
+        if( get4byte(pCell)==iFrom ){
+          put4byte(pCell, iTo);
+          break;
+        }
+      }
+    }
+  
+    if( i==nCell ){
+      if( eType!=PTRMAP_BTREE || 
+          get4byte(&pPage->aData[pPage->hdrOffset+8])!=iFrom ){
+        return SQLITE_CORRUPT_BKPT;
+      }
+      put4byte(&pPage->aData[pPage->hdrOffset+8], iTo);
+    }
+
+    pPage->isInit = isInitOrig;
+  }
+  return SQLITE_OK;
+}
+
+
+/*
+** Move the open database page pDbPage to location iFreePage in the 
+** database. The pDbPage reference remains valid.
+**
+** The isCommit flag indicates that there is no need to remember that
+** the journal needs to be sync()ed before database page pDbPage->pgno 
+** can be written to. The caller has already promised not to write to that
+** page.
+*/
+static int relocatePage(
+  BtShared *pBt,           /* Btree */
+  MemPage *pDbPage,        /* Open page to move */
+  u8 eType,                /* Pointer map 'type' entry for pDbPage */
+  Pgno iPtrPage,           /* Pointer map 'page-no' entry for pDbPage */
+  Pgno iFreePage,          /* The location to move pDbPage to */
+  int isCommit             /* isCommit flag passed to sqlite3PagerMovepage */
+){
+  MemPage *pPtrPage;   /* The page that contains a pointer to pDbPage */
+  Pgno iDbPage = pDbPage->pgno;
+  Pager *pPager = pBt->pPager;
+  int rc;
+
+  assert( eType==PTRMAP_OVERFLOW2 || eType==PTRMAP_OVERFLOW1 || 
+      eType==PTRMAP_BTREE || eType==PTRMAP_ROOTPAGE );
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  assert( pDbPage->pBt==pBt );
+
+  /* Move page iDbPage from its current location to page number iFreePage */
+  TRACE(("AUTOVACUUM: Moving %d to free page %d (ptr page %d type %d)\n", 
+      iDbPage, iFreePage, iPtrPage, eType));
+  rc = sqlite3PagerMovepage(pPager, pDbPage->pDbPage, iFreePage, isCommit);
+  if( rc!=SQLITE_OK ){
+    return rc;
+  }
+  pDbPage->pgno = iFreePage;
+
+  /* If pDbPage was a btree-page, then it may have child pages and/or cells
+  ** that point to overflow pages. The pointer map entries for all these
+  ** pages need to be changed.
+  **
+  ** If pDbPage is an overflow page, then the first 4 bytes may store a
+  ** pointer to a subsequent overflow page. If this is the case, then
+  ** the pointer map needs to be updated for the subsequent overflow page.
+  */
+  if( eType==PTRMAP_BTREE || eType==PTRMAP_ROOTPAGE ){
+    rc = setChildPtrmaps(pDbPage);
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+  }else{
+    Pgno nextOvfl = get4byte(pDbPage->aData);
+    if( nextOvfl!=0 ){
+      ptrmapPut(pBt, nextOvfl, PTRMAP_OVERFLOW2, iFreePage, &rc);
+      if( rc!=SQLITE_OK ){
+        return rc;
+      }
+    }
+  }
+
+  /* Fix the database pointer on page iPtrPage that pointed at iDbPage so
+  ** that it points at iFreePage. Also fix the pointer map entry for
+  ** iPtrPage.
+  */
+  if( eType!=PTRMAP_ROOTPAGE ){
+    rc = btreeGetPage(pBt, iPtrPage, &pPtrPage, 0);
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+    rc = sqlite3PagerWrite(pPtrPage->pDbPage);
+    if( rc!=SQLITE_OK ){
+      releasePage(pPtrPage);
+      return rc;
+    }
+    rc = modifyPagePointer(pPtrPage, iDbPage, iFreePage, eType);
+    releasePage(pPtrPage);
+    if( rc==SQLITE_OK ){
+      ptrmapPut(pBt, iFreePage, eType, iPtrPage, &rc);
+    }
+  }
+  return rc;
+}
+
+/* Forward declaration required by incrVacuumStep(). */
+static int allocateBtreePage(BtShared *, MemPage **, Pgno *, Pgno, u8);
+
+/*
+** Perform a single step of an incremental-vacuum. If successful,
+** return SQLITE_OK. If there is no work to do (and therefore no
+** point in calling this function again), return SQLITE_DONE.
+**
+** More specificly, this function attempts to re-organize the 
+** database so that the last page of the file currently in use
+** is no longer in use.
+**
+** If the nFin parameter is non-zero, this function assumes
+** that the caller will keep calling incrVacuumStep() until
+** it returns SQLITE_DONE or an error, and that nFin is the
+** number of pages the database file will contain after this 
+** process is complete.  If nFin is zero, it is assumed that
+** incrVacuumStep() will be called a finite amount of times
+** which may or may not empty the freelist.  A full autovacuum
+** has nFin>0.  A "PRAGMA incremental_vacuum" has nFin==0.
+*/
+static int incrVacuumStep(BtShared *pBt, Pgno nFin, Pgno iLastPg){
+  Pgno nFreeList;           /* Number of pages still on the free-list */
+  int rc;
+
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  assert( iLastPg>nFin );
+
+  if( !PTRMAP_ISPAGE(pBt, iLastPg) && iLastPg!=PENDING_BYTE_PAGE(pBt) ){
+    u8 eType;
+    Pgno iPtrPage;
+
+    nFreeList = get4byte(&pBt->pPage1->aData[36]);
+    if( nFreeList==0 ){
+      return SQLITE_DONE;
+    }
+
+    rc = ptrmapGet(pBt, iLastPg, &eType, &iPtrPage);
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+    if( eType==PTRMAP_ROOTPAGE ){
+      return SQLITE_CORRUPT_BKPT;
+    }
+
+    if( eType==PTRMAP_FREEPAGE ){
+      if( nFin==0 ){
+        /* Remove the page from the files free-list. This is not required
+        ** if nFin is non-zero. In that case, the free-list will be
+        ** truncated to zero after this function returns, so it doesn't 
+        ** matter if it still contains some garbage entries.
+        */
+        Pgno iFreePg;
+        MemPage *pFreePg;
+        rc = allocateBtreePage(pBt, &pFreePg, &iFreePg, iLastPg, 1);
+        if( rc!=SQLITE_OK ){
+          return rc;
+        }
+        assert( iFreePg==iLastPg );
+        releasePage(pFreePg);
+      }
+    } else {
+      Pgno iFreePg;             /* Index of free page to move pLastPg to */
+      MemPage *pLastPg;
+
+      rc = btreeGetPage(pBt, iLastPg, &pLastPg, 0);
+      if( rc!=SQLITE_OK ){
+        return rc;
+      }
+
+      /* If nFin is zero, this loop runs exactly once and page pLastPg
+      ** is swapped with the first free page pulled off the free list.
+      **
+      ** On the other hand, if nFin is greater than zero, then keep
+      ** looping until a free-page located within the first nFin pages
+      ** of the file is found.
+      */
+      do {
+        MemPage *pFreePg;
+        rc = allocateBtreePage(pBt, &pFreePg, &iFreePg, 0, 0);
+        if( rc!=SQLITE_OK ){
+          releasePage(pLastPg);
+          return rc;
+        }
+        releasePage(pFreePg);
+      }while( nFin!=0 && iFreePg>nFin );
+      assert( iFreePg<iLastPg );
+      
+      rc = sqlite3PagerWrite(pLastPg->pDbPage);
+      if( rc==SQLITE_OK ){
+        rc = relocatePage(pBt, pLastPg, eType, iPtrPage, iFreePg, nFin!=0);
+      }
+      releasePage(pLastPg);
+      if( rc!=SQLITE_OK ){
+        return rc;
+      }
+    }
+  }
+
+  if( nFin==0 ){
+    iLastPg--;
+    while( iLastPg==PENDING_BYTE_PAGE(pBt)||PTRMAP_ISPAGE(pBt, iLastPg) ){
+      if( PTRMAP_ISPAGE(pBt, iLastPg) ){
+        MemPage *pPg;
+        rc = btreeGetPage(pBt, iLastPg, &pPg, 0);
+        if( rc!=SQLITE_OK ){
+          return rc;
+        }
+        rc = sqlite3PagerWrite(pPg->pDbPage);
+        releasePage(pPg);
+        if( rc!=SQLITE_OK ){
+          return rc;
+        }
+      }
+      iLastPg--;
+    }
+    sqlite3PagerTruncateImage(pBt->pPager, iLastPg);
+    pBt->nPage = iLastPg;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** A write-transaction must be opened before calling this function.
+** It performs a single unit of work towards an incremental vacuum.
+**
+** If the incremental vacuum is finished after this function has run,
+** SQLITE_DONE is returned. If it is not finished, but no error occurred,
+** SQLITE_OK is returned. Otherwise an SQLite error code. 
+*/
+SQLITE_PRIVATE int sqlite3BtreeIncrVacuum(Btree *p){
+  int rc;
+  BtShared *pBt = p->pBt;
+
+  sqlite3BtreeEnter(p);
+  assert( pBt->inTransaction==TRANS_WRITE && p->inTrans==TRANS_WRITE );
+  if( !pBt->autoVacuum ){
+    rc = SQLITE_DONE;
+  }else{
+    invalidateAllOverflowCache(pBt);
+    rc = incrVacuumStep(pBt, 0, btreePagecount(pBt));
+    if( rc==SQLITE_OK ){
+      rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
+      put4byte(&pBt->pPage1->aData[28], pBt->nPage);
+    }
+  }
+  sqlite3BtreeLeave(p);
+  return rc;
+}
+
+/*
+** This routine is called prior to sqlite3PagerCommit when a transaction
+** is commited for an auto-vacuum database.
+**
+** If SQLITE_OK is returned, then *pnTrunc is set to the number of pages
+** the database file should be truncated to during the commit process. 
+** i.e. the database has been reorganized so that only the first *pnTrunc
+** pages are in use.
+*/
+static int autoVacuumCommit(BtShared *pBt){
+  int rc = SQLITE_OK;
+  Pager *pPager = pBt->pPager;
+  VVA_ONLY( int nRef = sqlite3PagerRefcount(pPager) );
+
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  invalidateAllOverflowCache(pBt);
+  assert(pBt->autoVacuum);
+  if( !pBt->incrVacuum ){
+    Pgno nFin;         /* Number of pages in database after autovacuuming */
+    Pgno nFree;        /* Number of pages on the freelist initially */
+    Pgno nPtrmap;      /* Number of PtrMap pages to be freed */
+    Pgno iFree;        /* The next page to be freed */
+    int nEntry;        /* Number of entries on one ptrmap page */
+    Pgno nOrig;        /* Database size before freeing */
+
+    nOrig = btreePagecount(pBt);
+    if( PTRMAP_ISPAGE(pBt, nOrig) || nOrig==PENDING_BYTE_PAGE(pBt) ){
+      /* It is not possible to create a database for which the final page
+      ** is either a pointer-map page or the pending-byte page. If one
+      ** is encountered, this indicates corruption.
+      */
+      return SQLITE_CORRUPT_BKPT;
+    }
+
+    nFree = get4byte(&pBt->pPage1->aData[36]);
+    nEntry = pBt->usableSize/5;
+    nPtrmap = (nFree-nOrig+PTRMAP_PAGENO(pBt, nOrig)+nEntry)/nEntry;
+    nFin = nOrig - nFree - nPtrmap;
+    if( nOrig>PENDING_BYTE_PAGE(pBt) && nFin<PENDING_BYTE_PAGE(pBt) ){
+      nFin--;
+    }
+    while( PTRMAP_ISPAGE(pBt, nFin) || nFin==PENDING_BYTE_PAGE(pBt) ){
+      nFin--;
+    }
+    if( nFin>nOrig ) return SQLITE_CORRUPT_BKPT;
+
+    for(iFree=nOrig; iFree>nFin && rc==SQLITE_OK; iFree--){
+      rc = incrVacuumStep(pBt, nFin, iFree);
+    }
+    if( (rc==SQLITE_DONE || rc==SQLITE_OK) && nFree>0 ){
+      rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
+      put4byte(&pBt->pPage1->aData[32], 0);
+      put4byte(&pBt->pPage1->aData[36], 0);
+      put4byte(&pBt->pPage1->aData[28], nFin);
+      sqlite3PagerTruncateImage(pBt->pPager, nFin);
+      pBt->nPage = nFin;
+    }
+    if( rc!=SQLITE_OK ){
+      sqlite3PagerRollback(pPager);
+    }
+  }
+
+  assert( nRef==sqlite3PagerRefcount(pPager) );
+  return rc;
+}
+
+#else /* ifndef SQLITE_OMIT_AUTOVACUUM */
+# define setChildPtrmaps(x) SQLITE_OK
+#endif
+
+/*
+** This routine does the first phase of a two-phase commit.  This routine
+** causes a rollback journal to be created (if it does not already exist)
+** and populated with enough information so that if a power loss occurs
+** the database can be restored to its original state by playing back
+** the journal.  Then the contents of the journal are flushed out to
+** the disk.  After the journal is safely on oxide, the changes to the
+** database are written into the database file and flushed to oxide.
+** At the end of this call, the rollback journal still exists on the
+** disk and we are still holding all locks, so the transaction has not
+** committed.  See sqlite3BtreeCommitPhaseTwo() for the second phase of the
+** commit process.
+**
+** This call is a no-op if no write-transaction is currently active on pBt.
+**
+** Otherwise, sync the database file for the btree pBt. zMaster points to
+** the name of a master journal file that should be written into the
+** individual journal file, or is NULL, indicating no master journal file 
+** (single database transaction).
+**
+** When this is called, the master journal should already have been
+** created, populated with this journal pointer and synced to disk.
+**
+** Once this is routine has returned, the only thing required to commit
+** the write-transaction for this database file is to delete the journal.
+*/
+SQLITE_PRIVATE int sqlite3BtreeCommitPhaseOne(Btree *p, const char *zMaster){
+  int rc = SQLITE_OK;
+  if( p->inTrans==TRANS_WRITE ){
+    BtShared *pBt = p->pBt;
+    sqlite3BtreeEnter(p);
+#ifndef SQLITE_OMIT_AUTOVACUUM
+    if( pBt->autoVacuum ){
+      rc = autoVacuumCommit(pBt);
+      if( rc!=SQLITE_OK ){
+        sqlite3BtreeLeave(p);
+        return rc;
+      }
+    }
+#endif
+    rc = sqlite3PagerCommitPhaseOne(pBt->pPager, zMaster, 0);
+    sqlite3BtreeLeave(p);
+  }
+  return rc;
+}
+
+/*
+** This function is called from both BtreeCommitPhaseTwo() and BtreeRollback()
+** at the conclusion of a transaction.
+*/
+static void btreeEndTransaction(Btree *p){
+  BtShared *pBt = p->pBt;
+  assert( sqlite3BtreeHoldsMutex(p) );
+
+  btreeClearHasContent(pBt);
+  if( p->inTrans>TRANS_NONE && p->db->activeVdbeCnt>1 ){
+    /* If there are other active statements that belong to this database
+    ** handle, downgrade to a read-only transaction. The other statements
+    ** may still be reading from the database.  */
+    downgradeAllSharedCacheTableLocks(p);
+    p->inTrans = TRANS_READ;
+  }else{
+    /* If the handle had any kind of transaction open, decrement the 
+    ** transaction count of the shared btree. If the transaction count 
+    ** reaches 0, set the shared state to TRANS_NONE. The unlockBtreeIfUnused()
+    ** call below will unlock the pager.  */
+    if( p->inTrans!=TRANS_NONE ){
+      clearAllSharedCacheTableLocks(p);
+      pBt->nTransaction--;
+      if( 0==pBt->nTransaction ){
+        pBt->inTransaction = TRANS_NONE;
+      }
+    }
+
+    /* Set the current transaction state to TRANS_NONE and unlock the 
+    ** pager if this call closed the only read or write transaction.  */
+    p->inTrans = TRANS_NONE;
+    unlockBtreeIfUnused(pBt);
+  }
+
+  btreeIntegrity(p);
+}
+
+/*
+** Commit the transaction currently in progress.
+**
+** This routine implements the second phase of a 2-phase commit.  The
+** sqlite3BtreeCommitPhaseOne() routine does the first phase and should
+** be invoked prior to calling this routine.  The sqlite3BtreeCommitPhaseOne()
+** routine did all the work of writing information out to disk and flushing the
+** contents so that they are written onto the disk platter.  All this
+** routine has to do is delete or truncate or zero the header in the
+** the rollback journal (which causes the transaction to commit) and
+** drop locks.
+**
+** Normally, if an error occurs while the pager layer is attempting to 
+** finalize the underlying journal file, this function returns an error and
+** the upper layer will attempt a rollback. However, if the second argument
+** is non-zero then this b-tree transaction is part of a multi-file 
+** transaction. In this case, the transaction has already been committed 
+** (by deleting a master journal file) and the caller will ignore this 
+** functions return code. So, even if an error occurs in the pager layer,
+** reset the b-tree objects internal state to indicate that the write
+** transaction has been closed. This is quite safe, as the pager will have
+** transitioned to the error state.
+**
+** This will release the write lock on the database file.  If there
+** are no active cursors, it also releases the read lock.
+*/
+SQLITE_PRIVATE int sqlite3BtreeCommitPhaseTwo(Btree *p, int bCleanup){
+
+  if( p->inTrans==TRANS_NONE ) return SQLITE_OK;
+  sqlite3BtreeEnter(p);
+  btreeIntegrity(p);
+
+  /* If the handle has a write-transaction open, commit the shared-btrees 
+  ** transaction and set the shared state to TRANS_READ.
+  */
+  if( p->inTrans==TRANS_WRITE ){
+    int rc;
+    BtShared *pBt = p->pBt;
+    assert( pBt->inTransaction==TRANS_WRITE );
+    assert( pBt->nTransaction>0 );
+    rc = sqlite3PagerCommitPhaseTwo(pBt->pPager);
+    if( rc!=SQLITE_OK && bCleanup==0 ){
+      sqlite3BtreeLeave(p);
+      return rc;
+    }
+    pBt->inTransaction = TRANS_READ;
+  }
+
+  btreeEndTransaction(p);
+  sqlite3BtreeLeave(p);
+  return SQLITE_OK;
+}
+
+/*
+** Do both phases of a commit.
+*/
+SQLITE_PRIVATE int sqlite3BtreeCommit(Btree *p){
+  int rc;
+  sqlite3BtreeEnter(p);
+  rc = sqlite3BtreeCommitPhaseOne(p, 0);
+  if( rc==SQLITE_OK ){
+    rc = sqlite3BtreeCommitPhaseTwo(p, 0);
+  }
+  sqlite3BtreeLeave(p);
+  return rc;
+}
+
+#ifndef NDEBUG
+/*
+** Return the number of write-cursors open on this handle. This is for use
+** in assert() expressions, so it is only compiled if NDEBUG is not
+** defined.
+**
+** For the purposes of this routine, a write-cursor is any cursor that
+** is capable of writing to the databse.  That means the cursor was
+** originally opened for writing and the cursor has not be disabled
+** by having its state changed to CURSOR_FAULT.
+*/
+static int countWriteCursors(BtShared *pBt){
+  BtCursor *pCur;
+  int r = 0;
+  for(pCur=pBt->pCursor; pCur; pCur=pCur->pNext){
+    if( pCur->wrFlag && pCur->eState!=CURSOR_FAULT ) r++; 
+  }
+  return r;
+}
+#endif
+
+/*
+** This routine sets the state to CURSOR_FAULT and the error
+** code to errCode for every cursor on BtShared that pBtree
+** references.
+**
+** Every cursor is tripped, including cursors that belong
+** to other database connections that happen to be sharing
+** the cache with pBtree.
+**
+** This routine gets called when a rollback occurs.
+** All cursors using the same cache must be tripped
+** to prevent them from trying to use the btree after
+** the rollback.  The rollback may have deleted tables
+** or moved root pages, so it is not sufficient to
+** save the state of the cursor.  The cursor must be
+** invalidated.
+*/
+SQLITE_PRIVATE void sqlite3BtreeTripAllCursors(Btree *pBtree, int errCode){
+  BtCursor *p;
+  sqlite3BtreeEnter(pBtree);
+  for(p=pBtree->pBt->pCursor; p; p=p->pNext){
+    int i;
+    sqlite3BtreeClearCursor(p);
+    p->eState = CURSOR_FAULT;
+    p->skipNext = errCode;
+    for(i=0; i<=p->iPage; i++){
+      releasePage(p->apPage[i]);
+      p->apPage[i] = 0;
+    }
+  }
+  sqlite3BtreeLeave(pBtree);
+}
+
+/*
+** Rollback the transaction in progress.  All cursors will be
+** invalided by this operation.  Any attempt to use a cursor
+** that was open at the beginning of this operation will result
+** in an error.
+**
+** This will release the write lock on the database file.  If there
+** are no active cursors, it also releases the read lock.
+*/
+SQLITE_PRIVATE int sqlite3BtreeRollback(Btree *p){
+  int rc;
+  BtShared *pBt = p->pBt;
+  MemPage *pPage1;
+
+  sqlite3BtreeEnter(p);
+  rc = saveAllCursors(pBt, 0, 0);
+#ifndef SQLITE_OMIT_SHARED_CACHE
+  if( rc!=SQLITE_OK ){
+    /* This is a horrible situation. An IO or malloc() error occurred whilst
+    ** trying to save cursor positions. If this is an automatic rollback (as
+    ** the result of a constraint, malloc() failure or IO error) then 
+    ** the cache may be internally inconsistent (not contain valid trees) so
+    ** we cannot simply return the error to the caller. Instead, abort 
+    ** all queries that may be using any of the cursors that failed to save.
+    */
+    sqlite3BtreeTripAllCursors(p, rc);
+  }
+#endif
+  btreeIntegrity(p);
+
+  if( p->inTrans==TRANS_WRITE ){
+    int rc2;
+
+    assert( TRANS_WRITE==pBt->inTransaction );
+    rc2 = sqlite3PagerRollback(pBt->pPager);
+    if( rc2!=SQLITE_OK ){
+      rc = rc2;
+    }
+
+    /* The rollback may have destroyed the pPage1->aData value.  So
+    ** call btreeGetPage() on page 1 again to make
+    ** sure pPage1->aData is set correctly. */
+    if( btreeGetPage(pBt, 1, &pPage1, 0)==SQLITE_OK ){
+      int nPage = get4byte(28+(u8*)pPage1->aData);
+      testcase( nPage==0 );
+      if( nPage==0 ) sqlite3PagerPagecount(pBt->pPager, &nPage);
+      testcase( pBt->nPage!=nPage );
+      pBt->nPage = nPage;
+      releasePage(pPage1);
+    }
+    assert( countWriteCursors(pBt)==0 );
+    pBt->inTransaction = TRANS_READ;
+  }
+
+  btreeEndTransaction(p);
+  sqlite3BtreeLeave(p);
+  return rc;
+}
+
+/*
+** Start a statement subtransaction. The subtransaction can can be rolled
+** back independently of the main transaction. You must start a transaction 
+** before starting a subtransaction. The subtransaction is ended automatically 
+** if the main transaction commits or rolls back.
+**
+** Statement subtransactions are used around individual SQL statements
+** that are contained within a BEGIN...COMMIT block.  If a constraint
+** error occurs within the statement, the effect of that one statement
+** can be rolled back without having to rollback the entire transaction.
+**
+** A statement sub-transaction is implemented as an anonymous savepoint. The
+** value passed as the second parameter is the total number of savepoints,
+** including the new anonymous savepoint, open on the B-Tree. i.e. if there
+** are no active savepoints and no other statement-transactions open,
+** iStatement is 1. This anonymous savepoint can be released or rolled back
+** using the sqlite3BtreeSavepoint() function.
+*/
+SQLITE_PRIVATE int sqlite3BtreeBeginStmt(Btree *p, int iStatement){
+  int rc;
+  BtShared *pBt = p->pBt;
+  sqlite3BtreeEnter(p);
+  assert( p->inTrans==TRANS_WRITE );
+  assert( pBt->readOnly==0 );
+  assert( iStatement>0 );
+  assert( iStatement>p->db->nSavepoint );
+  assert( pBt->inTransaction==TRANS_WRITE );
+  /* At the pager level, a statement transaction is a savepoint with
+  ** an index greater than all savepoints created explicitly using
+  ** SQL statements. It is illegal to open, release or rollback any
+  ** such savepoints while the statement transaction savepoint is active.
+  */
+  rc = sqlite3PagerOpenSavepoint(pBt->pPager, iStatement);
+  sqlite3BtreeLeave(p);
+  return rc;
+}
+
+/*
+** The second argument to this function, op, is always SAVEPOINT_ROLLBACK
+** or SAVEPOINT_RELEASE. This function either releases or rolls back the
+** savepoint identified by parameter iSavepoint, depending on the value 
+** of op.
+**
+** Normally, iSavepoint is greater than or equal to zero. However, if op is
+** SAVEPOINT_ROLLBACK, then iSavepoint may also be -1. In this case the 
+** contents of the entire transaction are rolled back. This is different
+** from a normal transaction rollback, as no locks are released and the
+** transaction remains open.
+*/
+SQLITE_PRIVATE int sqlite3BtreeSavepoint(Btree *p, int op, int iSavepoint){
+  int rc = SQLITE_OK;
+  if( p && p->inTrans==TRANS_WRITE ){
+    BtShared *pBt = p->pBt;
+    assert( op==SAVEPOINT_RELEASE || op==SAVEPOINT_ROLLBACK );
+    assert( iSavepoint>=0 || (iSavepoint==-1 && op==SAVEPOINT_ROLLBACK) );
+    sqlite3BtreeEnter(p);
+    rc = sqlite3PagerSavepoint(pBt->pPager, op, iSavepoint);
+    if( rc==SQLITE_OK ){
+      if( iSavepoint<0 && pBt->initiallyEmpty ) pBt->nPage = 0;
+      rc = newDatabase(pBt);
+      pBt->nPage = get4byte(28 + pBt->pPage1->aData);
+
+      /* The database size was written into the offset 28 of the header
+      ** when the transaction started, so we know that the value at offset
+      ** 28 is nonzero. */
+      assert( pBt->nPage>0 );
+    }
+    sqlite3BtreeLeave(p);
+  }
+  return rc;
+}
+
+/*
+** Create a new cursor for the BTree whose root is on the page
+** iTable. If a read-only cursor is requested, it is assumed that
+** the caller already has at least a read-only transaction open
+** on the database already. If a write-cursor is requested, then
+** the caller is assumed to have an open write transaction.
+**
+** If wrFlag==0, then the cursor can only be used for reading.
+** If wrFlag==1, then the cursor can be used for reading or for
+** writing if other conditions for writing are also met.  These
+** are the conditions that must be met in order for writing to
+** be allowed:
+**
+** 1:  The cursor must have been opened with wrFlag==1
+**
+** 2:  Other database connections that share the same pager cache
+**     but which are not in the READ_UNCOMMITTED state may not have
+**     cursors open with wrFlag==0 on the same table.  Otherwise
+**     the changes made by this write cursor would be visible to
+**     the read cursors in the other database connection.
+**
+** 3:  The database must be writable (not on read-only media)
+**
+** 4:  There must be an active transaction.
+**
+** No checking is done to make sure that page iTable really is the
+** root page of a b-tree.  If it is not, then the cursor acquired
+** will not work correctly.
+**
+** It is assumed that the sqlite3BtreeCursorZero() has been called
+** on pCur to initialize the memory space prior to invoking this routine.
+*/
+static int btreeCursor(
+  Btree *p,                              /* The btree */
+  int iTable,                            /* Root page of table to open */
+  int wrFlag,                            /* 1 to write. 0 read-only */
+  struct KeyInfo *pKeyInfo,              /* First arg to comparison function */
+  BtCursor *pCur                         /* Space for new cursor */
+){
+  BtShared *pBt = p->pBt;                /* Shared b-tree handle */
+
+  assert( sqlite3BtreeHoldsMutex(p) );
+  assert( wrFlag==0 || wrFlag==1 );
+
+  /* The following assert statements verify that if this is a sharable 
+  ** b-tree database, the connection is holding the required table locks, 
+  ** and that no other connection has any open cursor that conflicts with 
+  ** this lock.  */
+  assert( hasSharedCacheTableLock(p, iTable, pKeyInfo!=0, wrFlag+1) );
+  assert( wrFlag==0 || !hasReadConflicts(p, iTable) );
+
+  /* Assert that the caller has opened the required transaction. */
+  assert( p->inTrans>TRANS_NONE );
+  assert( wrFlag==0 || p->inTrans==TRANS_WRITE );
+  assert( pBt->pPage1 && pBt->pPage1->aData );
+
+  if( NEVER(wrFlag && pBt->readOnly) ){
+    return SQLITE_READONLY;
+  }
+  if( iTable==1 && btreePagecount(pBt)==0 ){
+    return SQLITE_EMPTY;
+  }
+
+  /* Now that no other errors can occur, finish filling in the BtCursor
+  ** variables and link the cursor into the BtShared list.  */
+  pCur->pgnoRoot = (Pgno)iTable;
+  pCur->iPage = -1;
+  pCur->pKeyInfo = pKeyInfo;
+  pCur->pBtree = p;
+  pCur->pBt = pBt;
+  pCur->wrFlag = (u8)wrFlag;
+  pCur->pNext = pBt->pCursor;
+  if( pCur->pNext ){
+    pCur->pNext->pPrev = pCur;
+  }
+  pBt->pCursor = pCur;
+  pCur->eState = CURSOR_INVALID;
+  pCur->cachedRowid = 0;
+  return SQLITE_OK;
+}
+SQLITE_PRIVATE int sqlite3BtreeCursor(
+  Btree *p,                                   /* The btree */
+  int iTable,                                 /* Root page of table to open */
+  int wrFlag,                                 /* 1 to write. 0 read-only */
+  struct KeyInfo *pKeyInfo,                   /* First arg to xCompare() */
+  BtCursor *pCur                              /* Write new cursor here */
+){
+  int rc;
+  sqlite3BtreeEnter(p);
+  rc = btreeCursor(p, iTable, wrFlag, pKeyInfo, pCur);
+  sqlite3BtreeLeave(p);
+  return rc;
+}
+
+/*
+** Return the size of a BtCursor object in bytes.
+**
+** This interfaces is needed so that users of cursors can preallocate
+** sufficient storage to hold a cursor.  The BtCursor object is opaque
+** to users so they cannot do the sizeof() themselves - they must call
+** this routine.
+*/
+SQLITE_PRIVATE int sqlite3BtreeCursorSize(void){
+  return ROUND8(sizeof(BtCursor));
+}
+
+/*
+** Initialize memory that will be converted into a BtCursor object.
+**
+** The simple approach here would be to memset() the entire object
+** to zero.  But it turns out that the apPage[] and aiIdx[] arrays
+** do not need to be zeroed and they are large, so we can save a lot
+** of run-time by skipping the initialization of those elements.
+*/
+SQLITE_PRIVATE void sqlite3BtreeCursorZero(BtCursor *p){
+  memset(p, 0, offsetof(BtCursor, iPage));
+}
+
+/*
+** Set the cached rowid value of every cursor in the same database file
+** as pCur and having the same root page number as pCur.  The value is
+** set to iRowid.
+**
+** Only positive rowid values are considered valid for this cache.
+** The cache is initialized to zero, indicating an invalid cache.
+** A btree will work fine with zero or negative rowids.  We just cannot
+** cache zero or negative rowids, which means tables that use zero or
+** negative rowids might run a little slower.  But in practice, zero
+** or negative rowids are very uncommon so this should not be a problem.
+*/
+SQLITE_PRIVATE void sqlite3BtreeSetCachedRowid(BtCursor *pCur, sqlite3_int64 iRowid){
+  BtCursor *p;
+  for(p=pCur->pBt->pCursor; p; p=p->pNext){
+    if( p->pgnoRoot==pCur->pgnoRoot ) p->cachedRowid = iRowid;
+  }
+  assert( pCur->cachedRowid==iRowid );
+}
+
+/*
+** Return the cached rowid for the given cursor.  A negative or zero
+** return value indicates that the rowid cache is invalid and should be
+** ignored.  If the rowid cache has never before been set, then a
+** zero is returned.
+*/
+SQLITE_PRIVATE sqlite3_int64 sqlite3BtreeGetCachedRowid(BtCursor *pCur){
+  return pCur->cachedRowid;
+}
+
+/*
+** Close a cursor.  The read lock on the database file is released
+** when the last cursor is closed.
+*/
+SQLITE_PRIVATE int sqlite3BtreeCloseCursor(BtCursor *pCur){
+  Btree *pBtree = pCur->pBtree;
+  if( pBtree ){
+    int i;
+    BtShared *pBt = pCur->pBt;
+    sqlite3BtreeEnter(pBtree);
+    sqlite3BtreeClearCursor(pCur);
+    if( pCur->pPrev ){
+      pCur->pPrev->pNext = pCur->pNext;
+    }else{
+      pBt->pCursor = pCur->pNext;
+    }
+    if( pCur->pNext ){
+      pCur->pNext->pPrev = pCur->pPrev;
+    }
+    for(i=0; i<=pCur->iPage; i++){
+      releasePage(pCur->apPage[i]);
+    }
+    unlockBtreeIfUnused(pBt);
+    invalidateOverflowCache(pCur);
+    /* sqlite3_free(pCur); */
+    sqlite3BtreeLeave(pBtree);
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Make sure the BtCursor* given in the argument has a valid
+** BtCursor.info structure.  If it is not already valid, call
+** btreeParseCell() to fill it in.
+**
+** BtCursor.info is a cache of the information in the current cell.
+** Using this cache reduces the number of calls to btreeParseCell().
+**
+** 2007-06-25:  There is a bug in some versions of MSVC that cause the
+** compiler to crash when getCellInfo() is implemented as a macro.
+** But there is a measureable speed advantage to using the macro on gcc
+** (when less compiler optimizations like -Os or -O0 are used and the
+** compiler is not doing agressive inlining.)  So we use a real function
+** for MSVC and a macro for everything else.  Ticket #2457.
+*/
+#ifndef NDEBUG
+  static void assertCellInfo(BtCursor *pCur){
+    CellInfo info;
+    int iPage = pCur->iPage;
+    memset(&info, 0, sizeof(info));
+    btreeParseCell(pCur->apPage[iPage], pCur->aiIdx[iPage], &info);
+    assert( memcmp(&info, &pCur->info, sizeof(info))==0 );
+  }
+#else
+  #define assertCellInfo(x)
+#endif
+#ifdef _MSC_VER
+  /* Use a real function in MSVC to work around bugs in that compiler. */
+  static void getCellInfo(BtCursor *pCur){
+    if( pCur->info.nSize==0 ){
+      int iPage = pCur->iPage;
+      btreeParseCell(pCur->apPage[iPage],pCur->aiIdx[iPage],&pCur->info);
+      pCur->validNKey = 1;
+    }else{
+      assertCellInfo(pCur);
+    }
+  }
+#else /* if not _MSC_VER */
+  /* Use a macro in all other compilers so that the function is inlined */
+#define getCellInfo(pCur)                                                      \
+  if( pCur->info.nSize==0 ){                                                   \
+    int iPage = pCur->iPage;                                                   \
+    btreeParseCell(pCur->apPage[iPage],pCur->aiIdx[iPage],&pCur->info); \
+    pCur->validNKey = 1;                                                       \
+  }else{                                                                       \
+    assertCellInfo(pCur);                                                      \
+  }
+#endif /* _MSC_VER */
+
+#ifndef NDEBUG  /* The next routine used only within assert() statements */
+/*
+** Return true if the given BtCursor is valid.  A valid cursor is one
+** that is currently pointing to a row in a (non-empty) table.
+** This is a verification routine is used only within assert() statements.
+*/
+SQLITE_PRIVATE int sqlite3BtreeCursorIsValid(BtCursor *pCur){
+  return pCur && pCur->eState==CURSOR_VALID;
+}
+#endif /* NDEBUG */
+
+/*
+** Set *pSize to the size of the buffer needed to hold the value of
+** the key for the current entry.  If the cursor is not pointing
+** to a valid entry, *pSize is set to 0. 
+**
+** For a table with the INTKEY flag set, this routine returns the key
+** itself, not the number of bytes in the key.
+**
+** The caller must position the cursor prior to invoking this routine.
+** 
+** This routine cannot fail.  It always returns SQLITE_OK.  
+*/
+SQLITE_PRIVATE int sqlite3BtreeKeySize(BtCursor *pCur, i64 *pSize){
+  assert( cursorHoldsMutex(pCur) );
+  assert( pCur->eState==CURSOR_INVALID || pCur->eState==CURSOR_VALID );
+  if( pCur->eState!=CURSOR_VALID ){
+    *pSize = 0;
+  }else{
+    getCellInfo(pCur);
+    *pSize = pCur->info.nKey;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Set *pSize to the number of bytes of data in the entry the
+** cursor currently points to.
+**
+** The caller must guarantee that the cursor is pointing to a non-NULL
+** valid entry.  In other words, the calling procedure must guarantee
+** that the cursor has Cursor.eState==CURSOR_VALID.
+**
+** Failure is not possible.  This function always returns SQLITE_OK.
+** It might just as well be a procedure (returning void) but we continue
+** to return an integer result code for historical reasons.
+*/
+SQLITE_PRIVATE int sqlite3BtreeDataSize(BtCursor *pCur, u32 *pSize){
+  assert( cursorHoldsMutex(pCur) );
+  assert( pCur->eState==CURSOR_VALID );
+  getCellInfo(pCur);
+  *pSize = pCur->info.nData;
+  return SQLITE_OK;
+}
+
+/*
+** Given the page number of an overflow page in the database (parameter
+** ovfl), this function finds the page number of the next page in the 
+** linked list of overflow pages. If possible, it uses the auto-vacuum
+** pointer-map data instead of reading the content of page ovfl to do so. 
+**
+** If an error occurs an SQLite error code is returned. Otherwise:
+**
+** The page number of the next overflow page in the linked list is 
+** written to *pPgnoNext. If page ovfl is the last page in its linked 
+** list, *pPgnoNext is set to zero. 
+**
+** If ppPage is not NULL, and a reference to the MemPage object corresponding
+** to page number pOvfl was obtained, then *ppPage is set to point to that
+** reference. It is the responsibility of the caller to call releasePage()
+** on *ppPage to free the reference. In no reference was obtained (because
+** the pointer-map was used to obtain the value for *pPgnoNext), then
+** *ppPage is set to zero.
+*/
+static int getOverflowPage(
+  BtShared *pBt,               /* The database file */
+  Pgno ovfl,                   /* Current overflow page number */
+  MemPage **ppPage,            /* OUT: MemPage handle (may be NULL) */
+  Pgno *pPgnoNext              /* OUT: Next overflow page number */
+){
+  Pgno next = 0;
+  MemPage *pPage = 0;
+  int rc = SQLITE_OK;
+
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  assert(pPgnoNext);
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+  /* Try to find the next page in the overflow list using the
+  ** autovacuum pointer-map pages. Guess that the next page in 
+  ** the overflow list is page number (ovfl+1). If that guess turns 
+  ** out to be wrong, fall back to loading the data of page 
+  ** number ovfl to determine the next page number.
+  */
+  if( pBt->autoVacuum ){
+    Pgno pgno;
+    Pgno iGuess = ovfl+1;
+    u8 eType;
+
+    while( PTRMAP_ISPAGE(pBt, iGuess) || iGuess==PENDING_BYTE_PAGE(pBt) ){
+      iGuess++;
+    }
+
+    if( iGuess<=btreePagecount(pBt) ){
+      rc = ptrmapGet(pBt, iGuess, &eType, &pgno);
+      if( rc==SQLITE_OK && eType==PTRMAP_OVERFLOW2 && pgno==ovfl ){
+        next = iGuess;
+        rc = SQLITE_DONE;
+      }
+    }
+  }
+#endif
+
+  assert( next==0 || rc==SQLITE_DONE );
+  if( rc==SQLITE_OK ){
+    rc = btreeGetPage(pBt, ovfl, &pPage, 0);
+    assert( rc==SQLITE_OK || pPage==0 );
+    if( rc==SQLITE_OK ){
+      next = get4byte(pPage->aData);
+    }
+  }
+
+  *pPgnoNext = next;
+  if( ppPage ){
+    *ppPage = pPage;
+  }else{
+    releasePage(pPage);
+  }
+  return (rc==SQLITE_DONE ? SQLITE_OK : rc);
+}
+
+/*
+** Copy data from a buffer to a page, or from a page to a buffer.
+**
+** pPayload is a pointer to data stored on database page pDbPage.
+** If argument eOp is false, then nByte bytes of data are copied
+** from pPayload to the buffer pointed at by pBuf. If eOp is true,
+** then sqlite3PagerWrite() is called on pDbPage and nByte bytes
+** of data are copied from the buffer pBuf to pPayload.
+**
+** SQLITE_OK is returned on success, otherwise an error code.
+*/
+static int copyPayload(
+  void *pPayload,           /* Pointer to page data */
+  void *pBuf,               /* Pointer to buffer */
+  int nByte,                /* Number of bytes to copy */
+  int eOp,                  /* 0 -> copy from page, 1 -> copy to page */
+  DbPage *pDbPage           /* Page containing pPayload */
+){
+  if( eOp ){
+    /* Copy data from buffer to page (a write operation) */
+    int rc = sqlite3PagerWrite(pDbPage);
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+    memcpy(pPayload, pBuf, nByte);
+  }else{
+    /* Copy data from page to buffer (a read operation) */
+    memcpy(pBuf, pPayload, nByte);
+  }
+  return SQLITE_OK;
+}
+
+/*
+** This function is used to read or overwrite payload information
+** for the entry that the pCur cursor is pointing to. If the eOp
+** parameter is 0, this is a read operation (data copied into
+** buffer pBuf). If it is non-zero, a write (data copied from
+** buffer pBuf).
+**
+** A total of "amt" bytes are read or written beginning at "offset".
+** Data is read to or from the buffer pBuf.
+**
+** The content being read or written might appear on the main page
+** or be scattered out on multiple overflow pages.
+**
+** If the BtCursor.isIncrblobHandle flag is set, and the current
+** cursor entry uses one or more overflow pages, this function
+** allocates space for and lazily popluates the overflow page-list 
+** cache array (BtCursor.aOverflow). Subsequent calls use this
+** cache to make seeking to the supplied offset more efficient.
+**
+** Once an overflow page-list cache has been allocated, it may be
+** invalidated if some other cursor writes to the same table, or if
+** the cursor is moved to a different row. Additionally, in auto-vacuum
+** mode, the following events may invalidate an overflow page-list cache.
+**
+**   * An incremental vacuum,
+**   * A commit in auto_vacuum="full" mode,
+**   * Creating a table (may require moving an overflow page).
+*/
+static int accessPayload(
+  BtCursor *pCur,      /* Cursor pointing to entry to read from */
+  u32 offset,          /* Begin reading this far into payload */
+  u32 amt,             /* Read this many bytes */
+  unsigned char *pBuf, /* Write the bytes into this buffer */ 
+  int eOp              /* zero to read. non-zero to write. */
+){
+  unsigned char *aPayload;
+  int rc = SQLITE_OK;
+  u32 nKey;
+  int iIdx = 0;
+  MemPage *pPage = pCur->apPage[pCur->iPage]; /* Btree page of current entry */
+  BtShared *pBt = pCur->pBt;                  /* Btree this cursor belongs to */
+
+  assert( pPage );
+  assert( pCur->eState==CURSOR_VALID );
+  assert( pCur->aiIdx[pCur->iPage]<pPage->nCell );
+  assert( cursorHoldsMutex(pCur) );
+
+  getCellInfo(pCur);
+  aPayload = pCur->info.pCell + pCur->info.nHeader;
+  nKey = (pPage->intKey ? 0 : (int)pCur->info.nKey);
+
+  if( NEVER(offset+amt > nKey+pCur->info.nData) 
+   || &aPayload[pCur->info.nLocal] > &pPage->aData[pBt->usableSize]
+  ){
+    /* Trying to read or write past the end of the data is an error */
+    return SQLITE_CORRUPT_BKPT;
+  }
+
+  /* Check if data must be read/written to/from the btree page itself. */
+  if( offset<pCur->info.nLocal ){
+    int a = amt;
+    if( a+offset>pCur->info.nLocal ){
+      a = pCur->info.nLocal - offset;
+    }
+    rc = copyPayload(&aPayload[offset], pBuf, a, eOp, pPage->pDbPage);
+    offset = 0;
+    pBuf += a;
+    amt -= a;
+  }else{
+    offset -= pCur->info.nLocal;
+  }
+
+  if( rc==SQLITE_OK && amt>0 ){
+    const u32 ovflSize = pBt->usableSize - 4;  /* Bytes content per ovfl page */
+    Pgno nextPage;
+
+    nextPage = get4byte(&aPayload[pCur->info.nLocal]);
+
+#ifndef SQLITE_OMIT_INCRBLOB
+    /* If the isIncrblobHandle flag is set and the BtCursor.aOverflow[]
+    ** has not been allocated, allocate it now. The array is sized at
+    ** one entry for each overflow page in the overflow chain. The
+    ** page number of the first overflow page is stored in aOverflow[0],
+    ** etc. A value of 0 in the aOverflow[] array means "not yet known"
+    ** (the cache is lazily populated).
+    */
+    if( pCur->isIncrblobHandle && !pCur->aOverflow ){
+      int nOvfl = (pCur->info.nPayload-pCur->info.nLocal+ovflSize-1)/ovflSize;
+      pCur->aOverflow = (Pgno *)sqlite3MallocZero(sizeof(Pgno)*nOvfl);
+      /* nOvfl is always positive.  If it were zero, fetchPayload would have
+      ** been used instead of this routine. */
+      if( ALWAYS(nOvfl) && !pCur->aOverflow ){
+        rc = SQLITE_NOMEM;
+      }
+    }
+
+    /* If the overflow page-list cache has been allocated and the
+    ** entry for the first required overflow page is valid, skip
+    ** directly to it.
+    */
+    if( pCur->aOverflow && pCur->aOverflow[offset/ovflSize] ){
+      iIdx = (offset/ovflSize);
+      nextPage = pCur->aOverflow[iIdx];
+      offset = (offset%ovflSize);
+    }
+#endif
+
+    for( ; rc==SQLITE_OK && amt>0 && nextPage; iIdx++){
+
+#ifndef SQLITE_OMIT_INCRBLOB
+      /* If required, populate the overflow page-list cache. */
+      if( pCur->aOverflow ){
+        assert(!pCur->aOverflow[iIdx] || pCur->aOverflow[iIdx]==nextPage);
+        pCur->aOverflow[iIdx] = nextPage;
+      }
+#endif
+
+      if( offset>=ovflSize ){
+        /* The only reason to read this page is to obtain the page
+        ** number for the next page in the overflow chain. The page
+        ** data is not required. So first try to lookup the overflow
+        ** page-list cache, if any, then fall back to the getOverflowPage()
+        ** function.
+        */
+#ifndef SQLITE_OMIT_INCRBLOB
+        if( pCur->aOverflow && pCur->aOverflow[iIdx+1] ){
+          nextPage = pCur->aOverflow[iIdx+1];
+        } else 
+#endif
+          rc = getOverflowPage(pBt, nextPage, 0, &nextPage);
+        offset -= ovflSize;
+      }else{
+        /* Need to read this page properly. It contains some of the
+        ** range of data that is being read (eOp==0) or written (eOp!=0).
+        */
+        DbPage *pDbPage;
+        int a = amt;
+        rc = sqlite3PagerGet(pBt->pPager, nextPage, &pDbPage);
+        if( rc==SQLITE_OK ){
+          aPayload = sqlite3PagerGetData(pDbPage);
+          nextPage = get4byte(aPayload);
+          if( a + offset > ovflSize ){
+            a = ovflSize - offset;
+          }
+          rc = copyPayload(&aPayload[offset+4], pBuf, a, eOp, pDbPage);
+          sqlite3PagerUnref(pDbPage);
+          offset = 0;
+          amt -= a;
+          pBuf += a;
+        }
+      }
+    }
+  }
+
+  if( rc==SQLITE_OK && amt>0 ){
+    return SQLITE_CORRUPT_BKPT;
+  }
+  return rc;
+}
+
+/*
+** Read part of the key associated with cursor pCur.  Exactly
+** "amt" bytes will be transfered into pBuf[].  The transfer
+** begins at "offset".
+**
+** The caller must ensure that pCur is pointing to a valid row
+** in the table.
+**
+** Return SQLITE_OK on success or an error code if anything goes
+** wrong.  An error is returned if "offset+amt" is larger than
+** the available payload.
+*/
+SQLITE_PRIVATE int sqlite3BtreeKey(BtCursor *pCur, u32 offset, u32 amt, void *pBuf){
+  assert( cursorHoldsMutex(pCur) );
+  assert( pCur->eState==CURSOR_VALID );
+  assert( pCur->iPage>=0 && pCur->apPage[pCur->iPage] );
+  assert( pCur->aiIdx[pCur->iPage]<pCur->apPage[pCur->iPage]->nCell );
+  return accessPayload(pCur, offset, amt, (unsigned char*)pBuf, 0);
+}
+
+/*
+** Read part of the data associated with cursor pCur.  Exactly
+** "amt" bytes will be transfered into pBuf[].  The transfer
+** begins at "offset".
+**
+** Return SQLITE_OK on success or an error code if anything goes
+** wrong.  An error is returned if "offset+amt" is larger than
+** the available payload.
+*/
+SQLITE_PRIVATE int sqlite3BtreeData(BtCursor *pCur, u32 offset, u32 amt, void *pBuf){
+  int rc;
+
+#ifndef SQLITE_OMIT_INCRBLOB
+  if ( pCur->eState==CURSOR_INVALID ){
+    return SQLITE_ABORT;
+  }
+#endif
+
+  assert( cursorHoldsMutex(pCur) );
+  rc = restoreCursorPosition(pCur);
+  if( rc==SQLITE_OK ){
+    assert( pCur->eState==CURSOR_VALID );
+    assert( pCur->iPage>=0 && pCur->apPage[pCur->iPage] );
+    assert( pCur->aiIdx[pCur->iPage]<pCur->apPage[pCur->iPage]->nCell );
+    rc = accessPayload(pCur, offset, amt, pBuf, 0);
+  }
+  return rc;
+}
+
+/*
+** Return a pointer to payload information from the entry that the 
+** pCur cursor is pointing to.  The pointer is to the beginning of
+** the key if skipKey==0 and it points to the beginning of data if
+** skipKey==1.  The number of bytes of available key/data is written
+** into *pAmt.  If *pAmt==0, then the value returned will not be
+** a valid pointer.
+**
+** This routine is an optimization.  It is common for the entire key
+** and data to fit on the local page and for there to be no overflow
+** pages.  When that is so, this routine can be used to access the
+** key and data without making a copy.  If the key and/or data spills
+** onto overflow pages, then accessPayload() must be used to reassemble
+** the key/data and copy it into a preallocated buffer.
+**
+** The pointer returned by this routine looks directly into the cached
+** page of the database.  The data might change or move the next time
+** any btree routine is called.
+*/
+static const unsigned char *fetchPayload(
+  BtCursor *pCur,      /* Cursor pointing to entry to read from */
+  int *pAmt,           /* Write the number of available bytes here */
+  int skipKey          /* read beginning at data if this is true */
+){
+  unsigned char *aPayload;
+  MemPage *pPage;
+  u32 nKey;
+  u32 nLocal;
+
+  assert( pCur!=0 && pCur->iPage>=0 && pCur->apPage[pCur->iPage]);
+  assert( pCur->eState==CURSOR_VALID );
+  assert( cursorHoldsMutex(pCur) );
+  pPage = pCur->apPage[pCur->iPage];
+  assert( pCur->aiIdx[pCur->iPage]<pPage->nCell );
+  if( NEVER(pCur->info.nSize==0) ){
+    btreeParseCell(pCur->apPage[pCur->iPage], pCur->aiIdx[pCur->iPage],
+                   &pCur->info);
+  }
+  aPayload = pCur->info.pCell;
+  aPayload += pCur->info.nHeader;
+  if( pPage->intKey ){
+    nKey = 0;
+  }else{
+    nKey = (int)pCur->info.nKey;
+  }
+  if( skipKey ){
+    aPayload += nKey;
+    nLocal = pCur->info.nLocal - nKey;
+  }else{
+    nLocal = pCur->info.nLocal;
+    assert( nLocal<=nKey );
+  }
+  *pAmt = nLocal;
+  return aPayload;
+}
+
+
+/*
+** For the entry that cursor pCur is point to, return as
+** many bytes of the key or data as are available on the local
+** b-tree page.  Write the number of available bytes into *pAmt.
+**
+** The pointer returned is ephemeral.  The key/data may move
+** or be destroyed on the next call to any Btree routine,
+** including calls from other threads against the same cache.
+** Hence, a mutex on the BtShared should be held prior to calling
+** this routine.
+**
+** These routines is used to get quick access to key and data
+** in the common case where no overflow pages are used.
+*/
+SQLITE_PRIVATE const void *sqlite3BtreeKeyFetch(BtCursor *pCur, int *pAmt){
+  const void *p = 0;
+  assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
+  assert( cursorHoldsMutex(pCur) );
+  if( ALWAYS(pCur->eState==CURSOR_VALID) ){
+    p = (const void*)fetchPayload(pCur, pAmt, 0);
+  }
+  return p;
+}
+SQLITE_PRIVATE const void *sqlite3BtreeDataFetch(BtCursor *pCur, int *pAmt){
+  const void *p = 0;
+  assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
+  assert( cursorHoldsMutex(pCur) );
+  if( ALWAYS(pCur->eState==CURSOR_VALID) ){
+    p = (const void*)fetchPayload(pCur, pAmt, 1);
+  }
+  return p;
+}
+
+
+/*
+** Move the cursor down to a new child page.  The newPgno argument is the
+** page number of the child page to move to.
+**
+** This function returns SQLITE_CORRUPT if the page-header flags field of
+** the new child page does not match the flags field of the parent (i.e.
+** if an intkey page appears to be the parent of a non-intkey page, or
+** vice-versa).
+*/
+static int moveToChild(BtCursor *pCur, u32 newPgno){
+  int rc;
+  int i = pCur->iPage;
+  MemPage *pNewPage;
+  BtShared *pBt = pCur->pBt;
+
+  assert( cursorHoldsMutex(pCur) );
+  assert( pCur->eState==CURSOR_VALID );
+  assert( pCur->iPage<BTCURSOR_MAX_DEPTH );
+  if( pCur->iPage>=(BTCURSOR_MAX_DEPTH-1) ){
+    return SQLITE_CORRUPT_BKPT;
+  }
+  rc = getAndInitPage(pBt, newPgno, &pNewPage);
+  if( rc ) return rc;
+  pCur->apPage[i+1] = pNewPage;
+  pCur->aiIdx[i+1] = 0;
+  pCur->iPage++;
+
+  pCur->info.nSize = 0;
+  pCur->validNKey = 0;
+  if( pNewPage->nCell<1 || pNewPage->intKey!=pCur->apPage[i]->intKey ){
+    return SQLITE_CORRUPT_BKPT;
+  }
+  return SQLITE_OK;
+}
+
+#ifndef NDEBUG
+/*
+** Page pParent is an internal (non-leaf) tree page. This function 
+** asserts that page number iChild is the left-child if the iIdx'th
+** cell in page pParent. Or, if iIdx is equal to the total number of
+** cells in pParent, that page number iChild is the right-child of
+** the page.
+*/
+static void assertParentIndex(MemPage *pParent, int iIdx, Pgno iChild){
+  assert( iIdx<=pParent->nCell );
+  if( iIdx==pParent->nCell ){
+    assert( get4byte(&pParent->aData[pParent->hdrOffset+8])==iChild );
+  }else{
+    assert( get4byte(findCell(pParent, iIdx))==iChild );
+  }
+}
+#else
+#  define assertParentIndex(x,y,z) 
+#endif
+
+/*
+** Move the cursor up to the parent page.
+**
+** pCur->idx is set to the cell index that contains the pointer
+** to the page we are coming from.  If we are coming from the
+** right-most child page then pCur->idx is set to one more than
+** the largest cell index.
+*/
+static void moveToParent(BtCursor *pCur){
+  assert( cursorHoldsMutex(pCur) );
+  assert( pCur->eState==CURSOR_VALID );
+  assert( pCur->iPage>0 );
+  assert( pCur->apPage[pCur->iPage] );
+  assertParentIndex(
+    pCur->apPage[pCur->iPage-1], 
+    pCur->aiIdx[pCur->iPage-1], 
+    pCur->apPage[pCur->iPage]->pgno
+  );
+  releasePage(pCur->apPage[pCur->iPage]);
+  pCur->iPage--;
+  pCur->info.nSize = 0;
+  pCur->validNKey = 0;
+}
+
+/*
+** Move the cursor to point to the root page of its b-tree structure.
+**
+** If the table has a virtual root page, then the cursor is moved to point
+** to the virtual root page instead of the actual root page. A table has a
+** virtual root page when the actual root page contains no cells and a 
+** single child page. This can only happen with the table rooted at page 1.
+**
+** If the b-tree structure is empty, the cursor state is set to 
+** CURSOR_INVALID. Otherwise, the cursor is set to point to the first
+** cell located on the root (or virtual root) page and the cursor state
+** is set to CURSOR_VALID.
+**
+** If this function returns successfully, it may be assumed that the
+** page-header flags indicate that the [virtual] root-page is the expected 
+** kind of b-tree page (i.e. if when opening the cursor the caller did not
+** specify a KeyInfo structure the flags byte is set to 0x05 or 0x0D,
+** indicating a table b-tree, or if the caller did specify a KeyInfo 
+** structure the flags byte is set to 0x02 or 0x0A, indicating an index
+** b-tree).
+*/
+static int moveToRoot(BtCursor *pCur){
+  MemPage *pRoot;
+  int rc = SQLITE_OK;
+  Btree *p = pCur->pBtree;
+  BtShared *pBt = p->pBt;
+
+  assert( cursorHoldsMutex(pCur) );
+  assert( CURSOR_INVALID < CURSOR_REQUIRESEEK );
+  assert( CURSOR_VALID   < CURSOR_REQUIRESEEK );
+  assert( CURSOR_FAULT   > CURSOR_REQUIRESEEK );
+  if( pCur->eState>=CURSOR_REQUIRESEEK ){
+    if( pCur->eState==CURSOR_FAULT ){
+      assert( pCur->skipNext!=SQLITE_OK );
+      return pCur->skipNext;
+    }
+    sqlite3BtreeClearCursor(pCur);
+  }
+
+  if( pCur->iPage>=0 ){
+    int i;
+    for(i=1; i<=pCur->iPage; i++){
+      releasePage(pCur->apPage[i]);
+    }
+    pCur->iPage = 0;
+  }else{
+    rc = getAndInitPage(pBt, pCur->pgnoRoot, &pCur->apPage[0]);
+    if( rc!=SQLITE_OK ){
+      pCur->eState = CURSOR_INVALID;
+      return rc;
+    }
+    pCur->iPage = 0;
+
+    /* If pCur->pKeyInfo is not NULL, then the caller that opened this cursor
+    ** expected to open it on an index b-tree. Otherwise, if pKeyInfo is
+    ** NULL, the caller expects a table b-tree. If this is not the case,
+    ** return an SQLITE_CORRUPT error.  */
+    assert( pCur->apPage[0]->intKey==1 || pCur->apPage[0]->intKey==0 );
+    if( (pCur->pKeyInfo==0)!=pCur->apPage[0]->intKey ){
+      return SQLITE_CORRUPT_BKPT;
+    }
+  }
+
+  /* Assert that the root page is of the correct type. This must be the
+  ** case as the call to this function that loaded the root-page (either
+  ** this call or a previous invocation) would have detected corruption 
+  ** if the assumption were not true, and it is not possible for the flags 
+  ** byte to have been modified while this cursor is holding a reference
+  ** to the page.  */
+  pRoot = pCur->apPage[0];
+  assert( pRoot->pgno==pCur->pgnoRoot );
+  assert( pRoot->isInit && (pCur->pKeyInfo==0)==pRoot->intKey );
+
+  pCur->aiIdx[0] = 0;
+  pCur->info.nSize = 0;
+  pCur->atLast = 0;
+  pCur->validNKey = 0;
+
+  if( pRoot->nCell==0 && !pRoot->leaf ){
+    Pgno subpage;
+    if( pRoot->pgno!=1 ) return SQLITE_CORRUPT_BKPT;
+    subpage = get4byte(&pRoot->aData[pRoot->hdrOffset+8]);
+    pCur->eState = CURSOR_VALID;
+    rc = moveToChild(pCur, subpage);
+  }else{
+    pCur->eState = ((pRoot->nCell>0)?CURSOR_VALID:CURSOR_INVALID);
+  }
+  return rc;
+}
+
+/*
+** Move the cursor down to the left-most leaf entry beneath the
+** entry to which it is currently pointing.
+**
+** The left-most leaf is the one with the smallest key - the first
+** in ascending order.
+*/
+static int moveToLeftmost(BtCursor *pCur){
+  Pgno pgno;
+  int rc = SQLITE_OK;
+  MemPage *pPage;
+
+  assert( cursorHoldsMutex(pCur) );
+  assert( pCur->eState==CURSOR_VALID );
+  while( rc==SQLITE_OK && !(pPage = pCur->apPage[pCur->iPage])->leaf ){
+    assert( pCur->aiIdx[pCur->iPage]<pPage->nCell );
+    pgno = get4byte(findCell(pPage, pCur->aiIdx[pCur->iPage]));
+    rc = moveToChild(pCur, pgno);
+  }
+  return rc;
+}
+
+/*
+** Move the cursor down to the right-most leaf entry beneath the
+** page to which it is currently pointing.  Notice the difference
+** between moveToLeftmost() and moveToRightmost().  moveToLeftmost()
+** finds the left-most entry beneath the *entry* whereas moveToRightmost()
+** finds the right-most entry beneath the *page*.
+**
+** The right-most entry is the one with the largest key - the last
+** key in ascending order.
+*/
+static int moveToRightmost(BtCursor *pCur){
+  Pgno pgno;
+  int rc = SQLITE_OK;
+  MemPage *pPage = 0;
+
+  assert( cursorHoldsMutex(pCur) );
+  assert( pCur->eState==CURSOR_VALID );
+  while( rc==SQLITE_OK && !(pPage = pCur->apPage[pCur->iPage])->leaf ){
+    pgno = get4byte(&pPage->aData[pPage->hdrOffset+8]);
+    pCur->aiIdx[pCur->iPage] = pPage->nCell;
+    rc = moveToChild(pCur, pgno);
+  }
+  if( rc==SQLITE_OK ){
+    pCur->aiIdx[pCur->iPage] = pPage->nCell-1;
+    pCur->info.nSize = 0;
+    pCur->validNKey = 0;
+  }
+  return rc;
+}
+
+/* Move the cursor to the first entry in the table.  Return SQLITE_OK
+** on success.  Set *pRes to 0 if the cursor actually points to something
+** or set *pRes to 1 if the table is empty.
+*/
+SQLITE_PRIVATE int sqlite3BtreeFirst(BtCursor *pCur, int *pRes){
+  int rc;
+
+  assert( cursorHoldsMutex(pCur) );
+  assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
+  rc = moveToRoot(pCur);
+  if( rc==SQLITE_OK ){
+    if( pCur->eState==CURSOR_INVALID ){
+      assert( pCur->apPage[pCur->iPage]->nCell==0 );
+      *pRes = 1;
+    }else{
+      assert( pCur->apPage[pCur->iPage]->nCell>0 );
+      *pRes = 0;
+      rc = moveToLeftmost(pCur);
+    }
+  }
+  return rc;
+}
+
+/* Move the cursor to the last entry in the table.  Return SQLITE_OK
+** on success.  Set *pRes to 0 if the cursor actually points to something
+** or set *pRes to 1 if the table is empty.
+*/
+SQLITE_PRIVATE int sqlite3BtreeLast(BtCursor *pCur, int *pRes){
+  int rc;
+ 
+  assert( cursorHoldsMutex(pCur) );
+  assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
+
+  /* If the cursor already points to the last entry, this is a no-op. */
+  if( CURSOR_VALID==pCur->eState && pCur->atLast ){
+#ifdef SQLITE_DEBUG
+    /* This block serves to assert() that the cursor really does point 
+    ** to the last entry in the b-tree. */
+    int ii;
+    for(ii=0; ii<pCur->iPage; ii++){
+      assert( pCur->aiIdx[ii]==pCur->apPage[ii]->nCell );
+    }
+    assert( pCur->aiIdx[pCur->iPage]==pCur->apPage[pCur->iPage]->nCell-1 );
+    assert( pCur->apPage[pCur->iPage]->leaf );
+#endif
+    return SQLITE_OK;
+  }
+
+  rc = moveToRoot(pCur);
+  if( rc==SQLITE_OK ){
+    if( CURSOR_INVALID==pCur->eState ){
+      assert( pCur->apPage[pCur->iPage]->nCell==0 );
+      *pRes = 1;
+    }else{
+      assert( pCur->eState==CURSOR_VALID );
+      *pRes = 0;
+      rc = moveToRightmost(pCur);
+      pCur->atLast = rc==SQLITE_OK ?1:0;
+    }
+  }
+  return rc;
+}
+
+/* Move the cursor so that it points to an entry near the key 
+** specified by pIdxKey or intKey.   Return a success code.
+**
+** For INTKEY tables, the intKey parameter is used.  pIdxKey 
+** must be NULL.  For index tables, pIdxKey is used and intKey
+** is ignored.
+**
+** If an exact match is not found, then the cursor is always
+** left pointing at a leaf page which would hold the entry if it
+** were present.  The cursor might point to an entry that comes
+** before or after the key.
+**
+** An integer is written into *pRes which is the result of
+** comparing the key with the entry to which the cursor is 
+** pointing.  The meaning of the integer written into
+** *pRes is as follows:
+**
+**     *pRes<0      The cursor is left pointing at an entry that
+**                  is smaller than intKey/pIdxKey or if the table is empty
+**                  and the cursor is therefore left point to nothing.
+**
+**     *pRes==0     The cursor is left pointing at an entry that
+**                  exactly matches intKey/pIdxKey.
+**
+**     *pRes>0      The cursor is left pointing at an entry that
+**                  is larger than intKey/pIdxKey.
+**
+*/
+SQLITE_PRIVATE int sqlite3BtreeMovetoUnpacked(
+  BtCursor *pCur,          /* The cursor to be moved */
+  UnpackedRecord *pIdxKey, /* Unpacked index key */
+  i64 intKey,              /* The table key */
+  int biasRight,           /* If true, bias the search to the high end */
+  int *pRes                /* Write search results here */
+){
+  int rc;
+
+  assert( cursorHoldsMutex(pCur) );
+  assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
+  assert( pRes );
+  assert( (pIdxKey==0)==(pCur->pKeyInfo==0) );
+
+  /* If the cursor is already positioned at the point we are trying
+  ** to move to, then just return without doing any work */
+  if( pCur->eState==CURSOR_VALID && pCur->validNKey 
+   && pCur->apPage[0]->intKey 
+  ){
+    if( pCur->info.nKey==intKey ){
+      *pRes = 0;
+      return SQLITE_OK;
+    }
+    if( pCur->atLast && pCur->info.nKey<intKey ){
+      *pRes = -1;
+      return SQLITE_OK;
+    }
+  }
+
+  rc = moveToRoot(pCur);
+  if( rc ){
+    return rc;
+  }
+  assert( pCur->apPage[pCur->iPage] );
+  assert( pCur->apPage[pCur->iPage]->isInit );
+  assert( pCur->apPage[pCur->iPage]->nCell>0 || pCur->eState==CURSOR_INVALID );
+  if( pCur->eState==CURSOR_INVALID ){
+    *pRes = -1;
+    assert( pCur->apPage[pCur->iPage]->nCell==0 );
+    return SQLITE_OK;
+  }
+  assert( pCur->apPage[0]->intKey || pIdxKey );
+  for(;;){
+    int lwr, upr;
+    Pgno chldPg;
+    MemPage *pPage = pCur->apPage[pCur->iPage];
+    int c;
+
+    /* pPage->nCell must be greater than zero. If this is the root-page
+    ** the cursor would have been INVALID above and this for(;;) loop
+    ** not run. If this is not the root-page, then the moveToChild() routine
+    ** would have already detected db corruption. Similarly, pPage must
+    ** be the right kind (index or table) of b-tree page. Otherwise
+    ** a moveToChild() or moveToRoot() call would have detected corruption.  */
+    assert( pPage->nCell>0 );
+    assert( pPage->intKey==(pIdxKey==0) );
+    lwr = 0;
+    upr = pPage->nCell-1;
+    if( biasRight ){
+      pCur->aiIdx[pCur->iPage] = (u16)upr;
+    }else{
+      pCur->aiIdx[pCur->iPage] = (u16)((upr+lwr)/2);
+    }
+    for(;;){
+      int idx = pCur->aiIdx[pCur->iPage]; /* Index of current cell in pPage */
+      u8 *pCell;                          /* Pointer to current cell in pPage */
+
+      pCur->info.nSize = 0;
+      pCell = findCell(pPage, idx) + pPage->childPtrSize;
+      if( pPage->intKey ){
+        i64 nCellKey;
+        if( pPage->hasData ){
+          u32 dummy;
+          pCell += getVarint32(pCell, dummy);
+        }
+        getVarint(pCell, (u64*)&nCellKey);
+        if( nCellKey==intKey ){
+          c = 0;
+        }else if( nCellKey<intKey ){
+          c = -1;
+        }else{
+          assert( nCellKey>intKey );
+          c = +1;
+        }
+        pCur->validNKey = 1;
+        pCur->info.nKey = nCellKey;
+      }else{
+        /* The maximum supported page-size is 65536 bytes. This means that
+        ** the maximum number of record bytes stored on an index B-Tree
+        ** page is less than 16384 bytes and may be stored as a 2-byte
+        ** varint. This information is used to attempt to avoid parsing 
+        ** the entire cell by checking for the cases where the record is 
+        ** stored entirely within the b-tree page by inspecting the first 
+        ** 2 bytes of the cell.
+        */
+        int nCell = pCell[0];
+        if( !(nCell & 0x80) && nCell<=pPage->maxLocal ){
+          /* This branch runs if the record-size field of the cell is a
+          ** single byte varint and the record fits entirely on the main
+          ** b-tree page.  */
+          c = sqlite3VdbeRecordCompare(nCell, (void*)&pCell[1], pIdxKey);
+        }else if( !(pCell[1] & 0x80) 
+          && (nCell = ((nCell&0x7f)<<7) + pCell[1])<=pPage->maxLocal
+        ){
+          /* The record-size field is a 2 byte varint and the record 
+          ** fits entirely on the main b-tree page.  */
+          c = sqlite3VdbeRecordCompare(nCell, (void*)&pCell[2], pIdxKey);
+        }else{
+          /* The record flows over onto one or more overflow pages. In
+          ** this case the whole cell needs to be parsed, a buffer allocated
+          ** and accessPayload() used to retrieve the record into the
+          ** buffer before VdbeRecordCompare() can be called. */
+          void *pCellKey;
+          u8 * const pCellBody = pCell - pPage->childPtrSize;
+          btreeParseCellPtr(pPage, pCellBody, &pCur->info);
+          nCell = (int)pCur->info.nKey;
+          pCellKey = sqlite3Malloc( nCell );
+          if( pCellKey==0 ){
+            rc = SQLITE_NOMEM;
+            goto moveto_finish;
+          }
+          rc = accessPayload(pCur, 0, nCell, (unsigned char*)pCellKey, 0);
+          if( rc ){
+            sqlite3_free(pCellKey);
+            goto moveto_finish;
+          }
+          c = sqlite3VdbeRecordCompare(nCell, pCellKey, pIdxKey);
+          sqlite3_free(pCellKey);
+        }
+      }
+      if( c==0 ){
+        if( pPage->intKey && !pPage->leaf ){
+          lwr = idx;
+          upr = lwr - 1;
+          break;
+        }else{
+          *pRes = 0;
+          rc = SQLITE_OK;
+          goto moveto_finish;
+        }
+      }
+      if( c<0 ){
+        lwr = idx+1;
+      }else{
+        upr = idx-1;
+      }
+      if( lwr>upr ){
+        break;
+      }
+      pCur->aiIdx[pCur->iPage] = (u16)((lwr+upr)/2);
+    }
+    assert( lwr==upr+1 );
+    assert( pPage->isInit );
+    if( pPage->leaf ){
+      chldPg = 0;
+    }else if( lwr>=pPage->nCell ){
+      chldPg = get4byte(&pPage->aData[pPage->hdrOffset+8]);
+    }else{
+      chldPg = get4byte(findCell(pPage, lwr));
+    }
+    if( chldPg==0 ){
+      assert( pCur->aiIdx[pCur->iPage]<pCur->apPage[pCur->iPage]->nCell );
+      *pRes = c;
+      rc = SQLITE_OK;
+      goto moveto_finish;
+    }
+    pCur->aiIdx[pCur->iPage] = (u16)lwr;
+    pCur->info.nSize = 0;
+    pCur->validNKey = 0;
+    rc = moveToChild(pCur, chldPg);
+    if( rc ) goto moveto_finish;
+  }
+moveto_finish:
+  return rc;
+}
+
+
+/*
+** Return TRUE if the cursor is not pointing at an entry of the table.
+**
+** TRUE will be returned after a call to sqlite3BtreeNext() moves
+** past the last entry in the table or sqlite3BtreePrev() moves past
+** the first entry.  TRUE is also returned if the table is empty.
+*/
+SQLITE_PRIVATE int sqlite3BtreeEof(BtCursor *pCur){
+  /* TODO: What if the cursor is in CURSOR_REQUIRESEEK but all table entries
+  ** have been deleted? This API will need to change to return an error code
+  ** as well as the boolean result value.
+  */
+  return (CURSOR_VALID!=pCur->eState);
+}
+
+/*
+** Advance the cursor to the next entry in the database.  If
+** successful then set *pRes=0.  If the cursor
+** was already pointing to the last entry in the database before
+** this routine was called, then set *pRes=1.
+*/
+SQLITE_PRIVATE int sqlite3BtreeNext(BtCursor *pCur, int *pRes){
+  int rc;
+  int idx;
+  MemPage *pPage;
+
+  assert( cursorHoldsMutex(pCur) );
+  rc = restoreCursorPosition(pCur);
+  if( rc!=SQLITE_OK ){
+    return rc;
+  }
+  assert( pRes!=0 );
+  if( CURSOR_INVALID==pCur->eState ){
+    *pRes = 1;
+    return SQLITE_OK;
+  }
+  if( pCur->skipNext>0 ){
+    pCur->skipNext = 0;
+    *pRes = 0;
+    return SQLITE_OK;
+  }
+  pCur->skipNext = 0;
+
+  pPage = pCur->apPage[pCur->iPage];
+  idx = ++pCur->aiIdx[pCur->iPage];
+  assert( pPage->isInit );
+  assert( idx<=pPage->nCell );
+
+  pCur->info.nSize = 0;
+  pCur->validNKey = 0;
+  if( idx>=pPage->nCell ){
+    if( !pPage->leaf ){
+      rc = moveToChild(pCur, get4byte(&pPage->aData[pPage->hdrOffset+8]));
+      if( rc ) return rc;
+      rc = moveToLeftmost(pCur);
+      *pRes = 0;
+      return rc;
+    }
+    do{
+      if( pCur->iPage==0 ){
+        *pRes = 1;
+        pCur->eState = CURSOR_INVALID;
+        return SQLITE_OK;
+      }
+      moveToParent(pCur);
+      pPage = pCur->apPage[pCur->iPage];
+    }while( pCur->aiIdx[pCur->iPage]>=pPage->nCell );
+    *pRes = 0;
+    if( pPage->intKey ){
+      rc = sqlite3BtreeNext(pCur, pRes);
+    }else{
+      rc = SQLITE_OK;
+    }
+    return rc;
+  }
+  *pRes = 0;
+  if( pPage->leaf ){
+    return SQLITE_OK;
+  }
+  rc = moveToLeftmost(pCur);
+  return rc;
+}
+
+
+/*
+** Step the cursor to the back to the previous entry in the database.  If
+** successful then set *pRes=0.  If the cursor
+** was already pointing to the first entry in the database before
+** this routine was called, then set *pRes=1.
+*/
+SQLITE_PRIVATE int sqlite3BtreePrevious(BtCursor *pCur, int *pRes){
+  int rc;
+  MemPage *pPage;
+
+  assert( cursorHoldsMutex(pCur) );
+  rc = restoreCursorPosition(pCur);
+  if( rc!=SQLITE_OK ){
+    return rc;
+  }
+  pCur->atLast = 0;
+  if( CURSOR_INVALID==pCur->eState ){
+    *pRes = 1;
+    return SQLITE_OK;
+  }
+  if( pCur->skipNext<0 ){
+    pCur->skipNext = 0;
+    *pRes = 0;
+    return SQLITE_OK;
+  }
+  pCur->skipNext = 0;
+
+  pPage = pCur->apPage[pCur->iPage];
+  assert( pPage->isInit );
+  if( !pPage->leaf ){
+    int idx = pCur->aiIdx[pCur->iPage];
+    rc = moveToChild(pCur, get4byte(findCell(pPage, idx)));
+    if( rc ){
+      return rc;
+    }
+    rc = moveToRightmost(pCur);
+  }else{
+    while( pCur->aiIdx[pCur->iPage]==0 ){
+      if( pCur->iPage==0 ){
+        pCur->eState = CURSOR_INVALID;
+        *pRes = 1;
+        return SQLITE_OK;
+      }
+      moveToParent(pCur);
+    }
+    pCur->info.nSize = 0;
+    pCur->validNKey = 0;
+
+    pCur->aiIdx[pCur->iPage]--;
+    pPage = pCur->apPage[pCur->iPage];
+    if( pPage->intKey && !pPage->leaf ){
+      rc = sqlite3BtreePrevious(pCur, pRes);
+    }else{
+      rc = SQLITE_OK;
+    }
+  }
+  *pRes = 0;
+  return rc;
+}
+
+/*
+** Allocate a new page from the database file.
+**
+** The new page is marked as dirty.  (In other words, sqlite3PagerWrite()
+** has already been called on the new page.)  The new page has also
+** been referenced and the calling routine is responsible for calling
+** sqlite3PagerUnref() on the new page when it is done.
+**
+** SQLITE_OK is returned on success.  Any other return value indicates
+** an error.  *ppPage and *pPgno are undefined in the event of an error.
+** Do not invoke sqlite3PagerUnref() on *ppPage if an error is returned.
+**
+** If the "nearby" parameter is not 0, then a (feeble) effort is made to 
+** locate a page close to the page number "nearby".  This can be used in an
+** attempt to keep related pages close to each other in the database file,
+** which in turn can make database access faster.
+**
+** If the "exact" parameter is not 0, and the page-number nearby exists 
+** anywhere on the free-list, then it is guarenteed to be returned. This
+** is only used by auto-vacuum databases when allocating a new table.
+*/
+static int allocateBtreePage(
+  BtShared *pBt, 
+  MemPage **ppPage, 
+  Pgno *pPgno, 
+  Pgno nearby,
+  u8 exact
+){
+  MemPage *pPage1;
+  int rc;
+  u32 n;     /* Number of pages on the freelist */
+  u32 k;     /* Number of leaves on the trunk of the freelist */
+  MemPage *pTrunk = 0;
+  MemPage *pPrevTrunk = 0;
+  Pgno mxPage;     /* Total size of the database file */
+
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  pPage1 = pBt->pPage1;
+  mxPage = btreePagecount(pBt);
+  n = get4byte(&pPage1->aData[36]);
+  testcase( n==mxPage-1 );
+  if( n>=mxPage ){
+    return SQLITE_CORRUPT_BKPT;
+  }
+  if( n>0 ){
+    /* There are pages on the freelist.  Reuse one of those pages. */
+    Pgno iTrunk;
+    u8 searchList = 0; /* If the free-list must be searched for 'nearby' */
+    
+    /* If the 'exact' parameter was true and a query of the pointer-map
+    ** shows that the page 'nearby' is somewhere on the free-list, then
+    ** the entire-list will be searched for that page.
+    */
+#ifndef SQLITE_OMIT_AUTOVACUUM
+    if( exact && nearby<=mxPage ){
+      u8 eType;
+      assert( nearby>0 );
+      assert( pBt->autoVacuum );
+      rc = ptrmapGet(pBt, nearby, &eType, 0);
+      if( rc ) return rc;
+      if( eType==PTRMAP_FREEPAGE ){
+        searchList = 1;
+      }
+      *pPgno = nearby;
+    }
+#endif
+
+    /* Decrement the free-list count by 1. Set iTrunk to the index of the
+    ** first free-list trunk page. iPrevTrunk is initially 1.
+    */
+    rc = sqlite3PagerWrite(pPage1->pDbPage);
+    if( rc ) return rc;
+    put4byte(&pPage1->aData[36], n-1);
+
+    /* The code within this loop is run only once if the 'searchList' variable
+    ** is not true. Otherwise, it runs once for each trunk-page on the
+    ** free-list until the page 'nearby' is located.
+    */
+    do {
+      pPrevTrunk = pTrunk;
+      if( pPrevTrunk ){
+        iTrunk = get4byte(&pPrevTrunk->aData[0]);
+      }else{
+        iTrunk = get4byte(&pPage1->aData[32]);
+      }
+      testcase( iTrunk==mxPage );
+      if( iTrunk>mxPage ){
+        rc = SQLITE_CORRUPT_BKPT;
+      }else{
+        rc = btreeGetPage(pBt, iTrunk, &pTrunk, 0);
+      }
+      if( rc ){
+        pTrunk = 0;
+        goto end_allocate_page;
+      }
+
+      k = get4byte(&pTrunk->aData[4]); /* # of leaves on this trunk page */
+      if( k==0 && !searchList ){
+        /* The trunk has no leaves and the list is not being searched. 
+        ** So extract the trunk page itself and use it as the newly 
+        ** allocated page */
+        assert( pPrevTrunk==0 );
+        rc = sqlite3PagerWrite(pTrunk->pDbPage);
+        if( rc ){
+          goto end_allocate_page;
+        }
+        *pPgno = iTrunk;
+        memcpy(&pPage1->aData[32], &pTrunk->aData[0], 4);
+        *ppPage = pTrunk;
+        pTrunk = 0;
+        TRACE(("ALLOCATE: %d trunk - %d free pages left\n", *pPgno, n-1));
+      }else if( k>(u32)(pBt->usableSize/4 - 2) ){
+        /* Value of k is out of range.  Database corruption */
+        rc = SQLITE_CORRUPT_BKPT;
+        goto end_allocate_page;
+#ifndef SQLITE_OMIT_AUTOVACUUM
+      }else if( searchList && nearby==iTrunk ){
+        /* The list is being searched and this trunk page is the page
+        ** to allocate, regardless of whether it has leaves.
+        */
+        assert( *pPgno==iTrunk );
+        *ppPage = pTrunk;
+        searchList = 0;
+        rc = sqlite3PagerWrite(pTrunk->pDbPage);
+        if( rc ){
+          goto end_allocate_page;
+        }
+        if( k==0 ){
+          if( !pPrevTrunk ){
+            memcpy(&pPage1->aData[32], &pTrunk->aData[0], 4);
+          }else{
+            rc = sqlite3PagerWrite(pPrevTrunk->pDbPage);
+            if( rc!=SQLITE_OK ){
+              goto end_allocate_page;
+            }
+            memcpy(&pPrevTrunk->aData[0], &pTrunk->aData[0], 4);
+          }
+        }else{
+          /* The trunk page is required by the caller but it contains 
+          ** pointers to free-list leaves. The first leaf becomes a trunk
+          ** page in this case.
+          */
+          MemPage *pNewTrunk;
+          Pgno iNewTrunk = get4byte(&pTrunk->aData[8]);
+          if( iNewTrunk>mxPage ){ 
+            rc = SQLITE_CORRUPT_BKPT;
+            goto end_allocate_page;
+          }
+          testcase( iNewTrunk==mxPage );
+          rc = btreeGetPage(pBt, iNewTrunk, &pNewTrunk, 0);
+          if( rc!=SQLITE_OK ){
+            goto end_allocate_page;
+          }
+          rc = sqlite3PagerWrite(pNewTrunk->pDbPage);
+          if( rc!=SQLITE_OK ){
+            releasePage(pNewTrunk);
+            goto end_allocate_page;
+          }
+          memcpy(&pNewTrunk->aData[0], &pTrunk->aData[0], 4);
+          put4byte(&pNewTrunk->aData[4], k-1);
+          memcpy(&pNewTrunk->aData[8], &pTrunk->aData[12], (k-1)*4);
+          releasePage(pNewTrunk);
+          if( !pPrevTrunk ){
+            assert( sqlite3PagerIswriteable(pPage1->pDbPage) );
+            put4byte(&pPage1->aData[32], iNewTrunk);
+          }else{
+            rc = sqlite3PagerWrite(pPrevTrunk->pDbPage);
+            if( rc ){
+              goto end_allocate_page;
+            }
+            put4byte(&pPrevTrunk->aData[0], iNewTrunk);
+          }
+        }
+        pTrunk = 0;
+        TRACE(("ALLOCATE: %d trunk - %d free pages left\n", *pPgno, n-1));
+#endif
+      }else if( k>0 ){
+        /* Extract a leaf from the trunk */
+        u32 closest;
+        Pgno iPage;
+        unsigned char *aData = pTrunk->aData;
+        if( nearby>0 ){
+          u32 i;
+          int dist;
+          closest = 0;
+          dist = sqlite3AbsInt32(get4byte(&aData[8]) - nearby);
+          for(i=1; i<k; i++){
+            int d2 = sqlite3AbsInt32(get4byte(&aData[8+i*4]) - nearby);
+            if( d2<dist ){
+              closest = i;
+              dist = d2;
+            }
+          }
+        }else{
+          closest = 0;
+        }
+
+        iPage = get4byte(&aData[8+closest*4]);
+        testcase( iPage==mxPage );
+        if( iPage>mxPage ){
+          rc = SQLITE_CORRUPT_BKPT;
+          goto end_allocate_page;
+        }
+        testcase( iPage==mxPage );
+        if( !searchList || iPage==nearby ){
+          int noContent;
+          *pPgno = iPage;
+          TRACE(("ALLOCATE: %d was leaf %d of %d on trunk %d"
+                 ": %d more free pages\n",
+                 *pPgno, closest+1, k, pTrunk->pgno, n-1));
+          rc = sqlite3PagerWrite(pTrunk->pDbPage);
+          if( rc ) goto end_allocate_page;
+          if( closest<k-1 ){
+            memcpy(&aData[8+closest*4], &aData[4+k*4], 4);
+          }
+          put4byte(&aData[4], k-1);
+          noContent = !btreeGetHasContent(pBt, *pPgno);
+          rc = btreeGetPage(pBt, *pPgno, ppPage, noContent);
+          if( rc==SQLITE_OK ){
+            rc = sqlite3PagerWrite((*ppPage)->pDbPage);
+            if( rc!=SQLITE_OK ){
+              releasePage(*ppPage);
+            }
+          }
+          searchList = 0;
+        }
+      }
+      releasePage(pPrevTrunk);
+      pPrevTrunk = 0;
+    }while( searchList );
+  }else{
+    /* There are no pages on the freelist, so create a new page at the
+    ** end of the file */
+    rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
+    if( rc ) return rc;
+    pBt->nPage++;
+    if( pBt->nPage==PENDING_BYTE_PAGE(pBt) ) pBt->nPage++;
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+    if( pBt->autoVacuum && PTRMAP_ISPAGE(pBt, pBt->nPage) ){
+      /* If *pPgno refers to a pointer-map page, allocate two new pages
+      ** at the end of the file instead of one. The first allocated page
+      ** becomes a new pointer-map page, the second is used by the caller.
+      */
+      MemPage *pPg = 0;
+      TRACE(("ALLOCATE: %d from end of file (pointer-map page)\n", pBt->nPage));
+      assert( pBt->nPage!=PENDING_BYTE_PAGE(pBt) );
+      rc = btreeGetPage(pBt, pBt->nPage, &pPg, 1);
+      if( rc==SQLITE_OK ){
+        rc = sqlite3PagerWrite(pPg->pDbPage);
+        releasePage(pPg);
+      }
+      if( rc ) return rc;
+      pBt->nPage++;
+      if( pBt->nPage==PENDING_BYTE_PAGE(pBt) ){ pBt->nPage++; }
+    }
+#endif
+    put4byte(28 + (u8*)pBt->pPage1->aData, pBt->nPage);
+    *pPgno = pBt->nPage;
+
+    assert( *pPgno!=PENDING_BYTE_PAGE(pBt) );
+    rc = btreeGetPage(pBt, *pPgno, ppPage, 1);
+    if( rc ) return rc;
+    rc = sqlite3PagerWrite((*ppPage)->pDbPage);
+    if( rc!=SQLITE_OK ){
+      releasePage(*ppPage);
+    }
+    TRACE(("ALLOCATE: %d from end of file\n", *pPgno));
+  }
+
+  assert( *pPgno!=PENDING_BYTE_PAGE(pBt) );
+
+end_allocate_page:
+  releasePage(pTrunk);
+  releasePage(pPrevTrunk);
+  if( rc==SQLITE_OK ){
+    if( sqlite3PagerPageRefcount((*ppPage)->pDbPage)>1 ){
+      releasePage(*ppPage);
+      return SQLITE_CORRUPT_BKPT;
+    }
+    (*ppPage)->isInit = 0;
+  }else{
+    *ppPage = 0;
+  }
+  assert( rc!=SQLITE_OK || sqlite3PagerIswriteable((*ppPage)->pDbPage) );
+  return rc;
+}
+
+/*
+** This function is used to add page iPage to the database file free-list. 
+** It is assumed that the page is not already a part of the free-list.
+**
+** The value passed as the second argument to this function is optional.
+** If the caller happens to have a pointer to the MemPage object 
+** corresponding to page iPage handy, it may pass it as the second value. 
+** Otherwise, it may pass NULL.
+**
+** If a pointer to a MemPage object is passed as the second argument,
+** its reference count is not altered by this function.
+*/
+static int freePage2(BtShared *pBt, MemPage *pMemPage, Pgno iPage){
+  MemPage *pTrunk = 0;                /* Free-list trunk page */
+  Pgno iTrunk = 0;                    /* Page number of free-list trunk page */ 
+  MemPage *pPage1 = pBt->pPage1;      /* Local reference to page 1 */
+  MemPage *pPage;                     /* Page being freed. May be NULL. */
+  int rc;                             /* Return Code */
+  int nFree;                          /* Initial number of pages on free-list */
+
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  assert( iPage>1 );
+  assert( !pMemPage || pMemPage->pgno==iPage );
+
+  if( pMemPage ){
+    pPage = pMemPage;
+    sqlite3PagerRef(pPage->pDbPage);
+  }else{
+    pPage = btreePageLookup(pBt, iPage);
+  }
+
+  /* Increment the free page count on pPage1 */
+  rc = sqlite3PagerWrite(pPage1->pDbPage);
+  if( rc ) goto freepage_out;
+  nFree = get4byte(&pPage1->aData[36]);
+  put4byte(&pPage1->aData[36], nFree+1);
+
+  if( pBt->secureDelete ){
+    /* If the secure_delete option is enabled, then
+    ** always fully overwrite deleted information with zeros.
+    */
+    if( (!pPage && ((rc = btreeGetPage(pBt, iPage, &pPage, 0))!=0) )
+     ||            ((rc = sqlite3PagerWrite(pPage->pDbPage))!=0)
+    ){
+      goto freepage_out;
+    }
+    memset(pPage->aData, 0, pPage->pBt->pageSize);
+  }
+
+  /* If the database supports auto-vacuum, write an entry in the pointer-map
+  ** to indicate that the page is free.
+  */
+  if( ISAUTOVACUUM ){
+    ptrmapPut(pBt, iPage, PTRMAP_FREEPAGE, 0, &rc);
+    if( rc ) goto freepage_out;
+  }
+
+  /* Now manipulate the actual database free-list structure. There are two
+  ** possibilities. If the free-list is currently empty, or if the first
+  ** trunk page in the free-list is full, then this page will become a
+  ** new free-list trunk page. Otherwise, it will become a leaf of the
+  ** first trunk page in the current free-list. This block tests if it
+  ** is possible to add the page as a new free-list leaf.
+  */
+  if( nFree!=0 ){
+    u32 nLeaf;                /* Initial number of leaf cells on trunk page */
+
+    iTrunk = get4byte(&pPage1->aData[32]);
+    rc = btreeGetPage(pBt, iTrunk, &pTrunk, 0);
+    if( rc!=SQLITE_OK ){
+      goto freepage_out;
+    }
+
+    nLeaf = get4byte(&pTrunk->aData[4]);
+    assert( pBt->usableSize>32 );
+    if( nLeaf > (u32)pBt->usableSize/4 - 2 ){
+      rc = SQLITE_CORRUPT_BKPT;
+      goto freepage_out;
+    }
+    if( nLeaf < (u32)pBt->usableSize/4 - 8 ){
+      /* In this case there is room on the trunk page to insert the page
+      ** being freed as a new leaf.
+      **
+      ** Note that the trunk page is not really full until it contains
+      ** usableSize/4 - 2 entries, not usableSize/4 - 8 entries as we have
+      ** coded.  But due to a coding error in versions of SQLite prior to
+      ** 3.6.0, databases with freelist trunk pages holding more than
+      ** usableSize/4 - 8 entries will be reported as corrupt.  In order
+      ** to maintain backwards compatibility with older versions of SQLite,
+      ** we will continue to restrict the number of entries to usableSize/4 - 8
+      ** for now.  At some point in the future (once everyone has upgraded
+      ** to 3.6.0 or later) we should consider fixing the conditional above
+      ** to read "usableSize/4-2" instead of "usableSize/4-8".
+      */
+      rc = sqlite3PagerWrite(pTrunk->pDbPage);
+      if( rc==SQLITE_OK ){
+        put4byte(&pTrunk->aData[4], nLeaf+1);
+        put4byte(&pTrunk->aData[8+nLeaf*4], iPage);
+        if( pPage && !pBt->secureDelete ){
+          sqlite3PagerDontWrite(pPage->pDbPage);
+        }
+        rc = btreeSetHasContent(pBt, iPage);
+      }
+      TRACE(("FREE-PAGE: %d leaf on trunk page %d\n",pPage->pgno,pTrunk->pgno));
+      goto freepage_out;
+    }
+  }
+
+  /* If control flows to this point, then it was not possible to add the
+  ** the page being freed as a leaf page of the first trunk in the free-list.
+  ** Possibly because the free-list is empty, or possibly because the 
+  ** first trunk in the free-list is full. Either way, the page being freed
+  ** will become the new first trunk page in the free-list.
+  */
+  if( pPage==0 && SQLITE_OK!=(rc = btreeGetPage(pBt, iPage, &pPage, 0)) ){
+    goto freepage_out;
+  }
+  rc = sqlite3PagerWrite(pPage->pDbPage);
+  if( rc!=SQLITE_OK ){
+    goto freepage_out;
+  }
+  put4byte(pPage->aData, iTrunk);
+  put4byte(&pPage->aData[4], 0);
+  put4byte(&pPage1->aData[32], iPage);
+  TRACE(("FREE-PAGE: %d new trunk page replacing %d\n", pPage->pgno, iTrunk));
+
+freepage_out:
+  if( pPage ){
+    pPage->isInit = 0;
+  }
+  releasePage(pPage);
+  releasePage(pTrunk);
+  return rc;
+}
+static void freePage(MemPage *pPage, int *pRC){
+  if( (*pRC)==SQLITE_OK ){
+    *pRC = freePage2(pPage->pBt, pPage, pPage->pgno);
+  }
+}
+
+/*
+** Free any overflow pages associated with the given Cell.
+*/
+static int clearCell(MemPage *pPage, unsigned char *pCell){
+  BtShared *pBt = pPage->pBt;
+  CellInfo info;
+  Pgno ovflPgno;
+  int rc;
+  int nOvfl;
+  u32 ovflPageSize;
+
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  btreeParseCellPtr(pPage, pCell, &info);
+  if( info.iOverflow==0 ){
+    return SQLITE_OK;  /* No overflow pages. Return without doing anything */
+  }
+  ovflPgno = get4byte(&pCell[info.iOverflow]);
+  assert( pBt->usableSize > 4 );
+  ovflPageSize = pBt->usableSize - 4;
+  nOvfl = (info.nPayload - info.nLocal + ovflPageSize - 1)/ovflPageSize;
+  assert( ovflPgno==0 || nOvfl>0 );
+  while( nOvfl-- ){
+    Pgno iNext = 0;
+    MemPage *pOvfl = 0;
+    if( ovflPgno<2 || ovflPgno>btreePagecount(pBt) ){
+      /* 0 is not a legal page number and page 1 cannot be an 
+      ** overflow page. Therefore if ovflPgno<2 or past the end of the 
+      ** file the database must be corrupt. */
+      return SQLITE_CORRUPT_BKPT;
+    }
+    if( nOvfl ){
+      rc = getOverflowPage(pBt, ovflPgno, &pOvfl, &iNext);
+      if( rc ) return rc;
+    }
+
+    if( ( pOvfl || ((pOvfl = btreePageLookup(pBt, ovflPgno))!=0) )
+     && sqlite3PagerPageRefcount(pOvfl->pDbPage)!=1
+    ){
+      /* There is no reason any cursor should have an outstanding reference 
+      ** to an overflow page belonging to a cell that is being deleted/updated.
+      ** So if there exists more than one reference to this page, then it 
+      ** must not really be an overflow page and the database must be corrupt. 
+      ** It is helpful to detect this before calling freePage2(), as 
+      ** freePage2() may zero the page contents if secure-delete mode is
+      ** enabled. If this 'overflow' page happens to be a page that the
+      ** caller is iterating through or using in some other way, this
+      ** can be problematic.
+      */
+      rc = SQLITE_CORRUPT_BKPT;
+    }else{
+      rc = freePage2(pBt, pOvfl, ovflPgno);
+    }
+
+    if( pOvfl ){
+      sqlite3PagerUnref(pOvfl->pDbPage);
+    }
+    if( rc ) return rc;
+    ovflPgno = iNext;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Create the byte sequence used to represent a cell on page pPage
+** and write that byte sequence into pCell[].  Overflow pages are
+** allocated and filled in as necessary.  The calling procedure
+** is responsible for making sure sufficient space has been allocated
+** for pCell[].
+**
+** Note that pCell does not necessary need to point to the pPage->aData
+** area.  pCell might point to some temporary storage.  The cell will
+** be constructed in this temporary area then copied into pPage->aData
+** later.
+*/
+static int fillInCell(
+  MemPage *pPage,                /* The page that contains the cell */
+  unsigned char *pCell,          /* Complete text of the cell */
+  const void *pKey, i64 nKey,    /* The key */
+  const void *pData,int nData,   /* The data */
+  int nZero,                     /* Extra zero bytes to append to pData */
+  int *pnSize                    /* Write cell size here */
+){
+  int nPayload;
+  const u8 *pSrc;
+  int nSrc, n, rc;
+  int spaceLeft;
+  MemPage *pOvfl = 0;
+  MemPage *pToRelease = 0;
+  unsigned char *pPrior;
+  unsigned char *pPayload;
+  BtShared *pBt = pPage->pBt;
+  Pgno pgnoOvfl = 0;
+  int nHeader;
+  CellInfo info;
+
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+
+  /* pPage is not necessarily writeable since pCell might be auxiliary
+  ** buffer space that is separate from the pPage buffer area */
+  assert( pCell<pPage->aData || pCell>=&pPage->aData[pBt->pageSize]
+            || sqlite3PagerIswriteable(pPage->pDbPage) );
+
+  /* Fill in the header. */
+  nHeader = 0;
+  if( !pPage->leaf ){
+    nHeader += 4;
+  }
+  if( pPage->hasData ){
+    nHeader += putVarint(&pCell[nHeader], nData+nZero);
+  }else{
+    nData = nZero = 0;
+  }
+  nHeader += putVarint(&pCell[nHeader], *(u64*)&nKey);
+  btreeParseCellPtr(pPage, pCell, &info);
+  assert( info.nHeader==nHeader );
+  assert( info.nKey==nKey );
+  assert( info.nData==(u32)(nData+nZero) );
+  
+  /* Fill in the payload */
+  nPayload = nData + nZero;
+  if( pPage->intKey ){
+    pSrc = pData;
+    nSrc = nData;
+    nData = 0;
+  }else{ 
+    if( NEVER(nKey>0x7fffffff || pKey==0) ){
+      return SQLITE_CORRUPT_BKPT;
+    }
+    nPayload += (int)nKey;
+    pSrc = pKey;
+    nSrc = (int)nKey;
+  }
+  *pnSize = info.nSize;
+  spaceLeft = info.nLocal;
+  pPayload = &pCell[nHeader];
+  pPrior = &pCell[info.iOverflow];
+
+  while( nPayload>0 ){
+    if( spaceLeft==0 ){
+#ifndef SQLITE_OMIT_AUTOVACUUM
+      Pgno pgnoPtrmap = pgnoOvfl; /* Overflow page pointer-map entry page */
+      if( pBt->autoVacuum ){
+        do{
+          pgnoOvfl++;
+        } while( 
+          PTRMAP_ISPAGE(pBt, pgnoOvfl) || pgnoOvfl==PENDING_BYTE_PAGE(pBt) 
+        );
+      }
+#endif
+      rc = allocateBtreePage(pBt, &pOvfl, &pgnoOvfl, pgnoOvfl, 0);
+#ifndef SQLITE_OMIT_AUTOVACUUM
+      /* If the database supports auto-vacuum, and the second or subsequent
+      ** overflow page is being allocated, add an entry to the pointer-map
+      ** for that page now. 
+      **
+      ** If this is the first overflow page, then write a partial entry 
+      ** to the pointer-map. If we write nothing to this pointer-map slot,
+      ** then the optimistic overflow chain processing in clearCell()
+      ** may misinterpret the uninitialised values and delete the
+      ** wrong pages from the database.
+      */
+      if( pBt->autoVacuum && rc==SQLITE_OK ){
+        u8 eType = (pgnoPtrmap?PTRMAP_OVERFLOW2:PTRMAP_OVERFLOW1);
+        ptrmapPut(pBt, pgnoOvfl, eType, pgnoPtrmap, &rc);
+        if( rc ){
+          releasePage(pOvfl);
+        }
+      }
+#endif
+      if( rc ){
+        releasePage(pToRelease);
+        return rc;
+      }
+
+      /* If pToRelease is not zero than pPrior points into the data area
+      ** of pToRelease.  Make sure pToRelease is still writeable. */
+      assert( pToRelease==0 || sqlite3PagerIswriteable(pToRelease->pDbPage) );
+
+      /* If pPrior is part of the data area of pPage, then make sure pPage
+      ** is still writeable */
+      assert( pPrior<pPage->aData || pPrior>=&pPage->aData[pBt->pageSize]
+            || sqlite3PagerIswriteable(pPage->pDbPage) );
+
+      put4byte(pPrior, pgnoOvfl);
+      releasePage(pToRelease);
+      pToRelease = pOvfl;
+      pPrior = pOvfl->aData;
+      put4byte(pPrior, 0);
+      pPayload = &pOvfl->aData[4];
+      spaceLeft = pBt->usableSize - 4;
+    }
+    n = nPayload;
+    if( n>spaceLeft ) n = spaceLeft;
+
+    /* If pToRelease is not zero than pPayload points into the data area
+    ** of pToRelease.  Make sure pToRelease is still writeable. */
+    assert( pToRelease==0 || sqlite3PagerIswriteable(pToRelease->pDbPage) );
+
+    /* If pPayload is part of the data area of pPage, then make sure pPage
+    ** is still writeable */
+    assert( pPayload<pPage->aData || pPayload>=&pPage->aData[pBt->pageSize]
+            || sqlite3PagerIswriteable(pPage->pDbPage) );
+
+    if( nSrc>0 ){
+      if( n>nSrc ) n = nSrc;
+      assert( pSrc );
+      memcpy(pPayload, pSrc, n);
+    }else{
+      memset(pPayload, 0, n);
+    }
+    nPayload -= n;
+    pPayload += n;
+    pSrc += n;
+    nSrc -= n;
+    spaceLeft -= n;
+    if( nSrc==0 ){
+      nSrc = nData;
+      pSrc = pData;
+    }
+  }
+  releasePage(pToRelease);
+  return SQLITE_OK;
+}
+
+/*
+** Remove the i-th cell from pPage.  This routine effects pPage only.
+** The cell content is not freed or deallocated.  It is assumed that
+** the cell content has been copied someplace else.  This routine just
+** removes the reference to the cell from pPage.
+**
+** "sz" must be the number of bytes in the cell.
+*/
+static void dropCell(MemPage *pPage, int idx, int sz, int *pRC){
+  int i;          /* Loop counter */
+  u32 pc;         /* Offset to cell content of cell being deleted */
+  u8 *data;       /* pPage->aData */
+  u8 *ptr;        /* Used to move bytes around within data[] */
+  int rc;         /* The return code */
+  int hdr;        /* Beginning of the header.  0 most pages.  100 page 1 */
+
+  if( *pRC ) return;
+
+  assert( idx>=0 && idx<pPage->nCell );
+  assert( sz==cellSize(pPage, idx) );
+  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  data = pPage->aData;
+  ptr = &data[pPage->cellOffset + 2*idx];
+  pc = get2byte(ptr);
+  hdr = pPage->hdrOffset;
+  testcase( pc==get2byte(&data[hdr+5]) );
+  testcase( pc+sz==pPage->pBt->usableSize );
+  if( pc < (u32)get2byte(&data[hdr+5]) || pc+sz > pPage->pBt->usableSize ){
+    *pRC = SQLITE_CORRUPT_BKPT;
+    return;
+  }
+  rc = freeSpace(pPage, pc, sz);
+  if( rc ){
+    *pRC = rc;
+    return;
+  }
+  for(i=idx+1; i<pPage->nCell; i++, ptr+=2){
+    ptr[0] = ptr[2];
+    ptr[1] = ptr[3];
+  }
+  pPage->nCell--;
+  put2byte(&data[hdr+3], pPage->nCell);
+  pPage->nFree += 2;
+}
+
+/*
+** Insert a new cell on pPage at cell index "i".  pCell points to the
+** content of the cell.
+**
+** If the cell content will fit on the page, then put it there.  If it
+** will not fit, then make a copy of the cell content into pTemp if
+** pTemp is not null.  Regardless of pTemp, allocate a new entry
+** in pPage->aOvfl[] and make it point to the cell content (either
+** in pTemp or the original pCell) and also record its index. 
+** Allocating a new entry in pPage->aCell[] implies that 
+** pPage->nOverflow is incremented.
+**
+** If nSkip is non-zero, then do not copy the first nSkip bytes of the
+** cell. The caller will overwrite them after this function returns. If
+** nSkip is non-zero, then pCell may not point to an invalid memory location 
+** (but pCell+nSkip is always valid).
+*/
+static void insertCell(
+  MemPage *pPage,   /* Page into which we are copying */
+  int i,            /* New cell becomes the i-th cell of the page */
+  u8 *pCell,        /* Content of the new cell */
+  int sz,           /* Bytes of content in pCell */
+  u8 *pTemp,        /* Temp storage space for pCell, if needed */
+  Pgno iChild,      /* If non-zero, replace first 4 bytes with this value */
+  int *pRC          /* Read and write return code from here */
+){
+  int idx = 0;      /* Where to write new cell content in data[] */
+  int j;            /* Loop counter */
+  int end;          /* First byte past the last cell pointer in data[] */
+  int ins;          /* Index in data[] where new cell pointer is inserted */
+  int cellOffset;   /* Address of first cell pointer in data[] */
+  u8 *data;         /* The content of the whole page */
+  u8 *ptr;          /* Used for moving information around in data[] */
+
+  int nSkip = (iChild ? 4 : 0);
+
+  if( *pRC ) return;
+
+  assert( i>=0 && i<=pPage->nCell+pPage->nOverflow );
+  assert( pPage->nCell<=MX_CELL(pPage->pBt) && MX_CELL(pPage->pBt)<=10921 );
+  assert( pPage->nOverflow<=ArraySize(pPage->aOvfl) );
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  /* The cell should normally be sized correctly.  However, when moving a
+  ** malformed cell from a leaf page to an interior page, if the cell size
+  ** wanted to be less than 4 but got rounded up to 4 on the leaf, then size
+  ** might be less than 8 (leaf-size + pointer) on the interior node.  Hence
+  ** the term after the || in the following assert(). */
+  assert( sz==cellSizePtr(pPage, pCell) || (sz==8 && iChild>0) );
+  if( pPage->nOverflow || sz+2>pPage->nFree ){
+    if( pTemp ){
+      memcpy(pTemp+nSkip, pCell+nSkip, sz-nSkip);
+      pCell = pTemp;
+    }
+    if( iChild ){
+      put4byte(pCell, iChild);
+    }
+    j = pPage->nOverflow++;
+    assert( j<(int)(sizeof(pPage->aOvfl)/sizeof(pPage->aOvfl[0])) );
+    pPage->aOvfl[j].pCell = pCell;
+    pPage->aOvfl[j].idx = (u16)i;
+  }else{
+    int rc = sqlite3PagerWrite(pPage->pDbPage);
+    if( rc!=SQLITE_OK ){
+      *pRC = rc;
+      return;
+    }
+    assert( sqlite3PagerIswriteable(pPage->pDbPage) );
+    data = pPage->aData;
+    cellOffset = pPage->cellOffset;
+    end = cellOffset + 2*pPage->nCell;
+    ins = cellOffset + 2*i;
+    rc = allocateSpace(pPage, sz, &idx);
+    if( rc ){ *pRC = rc; return; }
+    /* The allocateSpace() routine guarantees the following two properties
+    ** if it returns success */
+    assert( idx >= end+2 );
+    assert( idx+sz <= (int)pPage->pBt->usableSize );
+    pPage->nCell++;
+    pPage->nFree -= (u16)(2 + sz);
+    memcpy(&data[idx+nSkip], pCell+nSkip, sz-nSkip);
+    if( iChild ){
+      put4byte(&data[idx], iChild);
+    }
+    for(j=end, ptr=&data[j]; j>ins; j-=2, ptr-=2){
+      ptr[0] = ptr[-2];
+      ptr[1] = ptr[-1];
+    }
+    put2byte(&data[ins], idx);
+    put2byte(&data[pPage->hdrOffset+3], pPage->nCell);
+#ifndef SQLITE_OMIT_AUTOVACUUM
+    if( pPage->pBt->autoVacuum ){
+      /* The cell may contain a pointer to an overflow page. If so, write
+      ** the entry for the overflow page into the pointer map.
+      */
+      ptrmapPutOvflPtr(pPage, pCell, pRC);
+    }
+#endif
+  }
+}
+
+/*
+** Add a list of cells to a page.  The page should be initially empty.
+** The cells are guaranteed to fit on the page.
+*/
+static void assemblePage(
+  MemPage *pPage,   /* The page to be assemblied */
+  int nCell,        /* The number of cells to add to this page */
+  u8 **apCell,      /* Pointers to cell bodies */
+  u16 *aSize        /* Sizes of the cells */
+){
+  int i;            /* Loop counter */
+  u8 *pCellptr;     /* Address of next cell pointer */
+  int cellbody;     /* Address of next cell body */
+  u8 * const data = pPage->aData;             /* Pointer to data for pPage */
+  const int hdr = pPage->hdrOffset;           /* Offset of header on pPage */
+  const int nUsable = pPage->pBt->usableSize; /* Usable size of page */
+
+  assert( pPage->nOverflow==0 );
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  assert( nCell>=0 && nCell<=(int)MX_CELL(pPage->pBt)
+            && (int)MX_CELL(pPage->pBt)<=10921);
+  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
+
+  /* Check that the page has just been zeroed by zeroPage() */
+  assert( pPage->nCell==0 );
+  assert( get2byteNotZero(&data[hdr+5])==nUsable );
+
+  pCellptr = &data[pPage->cellOffset + nCell*2];
+  cellbody = nUsable;
+  for(i=nCell-1; i>=0; i--){
+    pCellptr -= 2;
+    cellbody -= aSize[i];
+    put2byte(pCellptr, cellbody);
+    memcpy(&data[cellbody], apCell[i], aSize[i]);
+  }
+  put2byte(&data[hdr+3], nCell);
+  put2byte(&data[hdr+5], cellbody);
+  pPage->nFree -= (nCell*2 + nUsable - cellbody);
+  pPage->nCell = (u16)nCell;
+}
+
+/*
+** The following parameters determine how many adjacent pages get involved
+** in a balancing operation.  NN is the number of neighbors on either side
+** of the page that participate in the balancing operation.  NB is the
+** total number of pages that participate, including the target page and
+** NN neighbors on either side.
+**
+** The minimum value of NN is 1 (of course).  Increasing NN above 1
+** (to 2 or 3) gives a modest improvement in SELECT and DELETE performance
+** in exchange for a larger degradation in INSERT and UPDATE performance.
+** The value of NN appears to give the best results overall.
+*/
+#define NN 1             /* Number of neighbors on either side of pPage */
+#define NB (NN*2+1)      /* Total pages involved in the balance */
+
+
+#ifndef SQLITE_OMIT_QUICKBALANCE
+/*
+** This version of balance() handles the common special case where
+** a new entry is being inserted on the extreme right-end of the
+** tree, in other words, when the new entry will become the largest
+** entry in the tree.
+**
+** Instead of trying to balance the 3 right-most leaf pages, just add
+** a new page to the right-hand side and put the one new entry in
+** that page.  This leaves the right side of the tree somewhat
+** unbalanced.  But odds are that we will be inserting new entries
+** at the end soon afterwards so the nearly empty page will quickly
+** fill up.  On average.
+**
+** pPage is the leaf page which is the right-most page in the tree.
+** pParent is its parent.  pPage must have a single overflow entry
+** which is also the right-most entry on the page.
+**
+** The pSpace buffer is used to store a temporary copy of the divider
+** cell that will be inserted into pParent. Such a cell consists of a 4
+** byte page number followed by a variable length integer. In other
+** words, at most 13 bytes. Hence the pSpace buffer must be at
+** least 13 bytes in size.
+*/
+static int balance_quick(MemPage *pParent, MemPage *pPage, u8 *pSpace){
+  BtShared *const pBt = pPage->pBt;    /* B-Tree Database */
+  MemPage *pNew;                       /* Newly allocated page */
+  int rc;                              /* Return Code */
+  Pgno pgnoNew;                        /* Page number of pNew */
+
+  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
+  assert( sqlite3PagerIswriteable(pParent->pDbPage) );
+  assert( pPage->nOverflow==1 );
+
+  /* This error condition is now caught prior to reaching this function */
+  if( pPage->nCell<=0 ) return SQLITE_CORRUPT_BKPT;
+
+  /* Allocate a new page. This page will become the right-sibling of 
+  ** pPage. Make the parent page writable, so that the new divider cell
+  ** may be inserted. If both these operations are successful, proceed.
+  */
+  rc = allocateBtreePage(pBt, &pNew, &pgnoNew, 0, 0);
+
+  if( rc==SQLITE_OK ){
+
+    u8 *pOut = &pSpace[4];
+    u8 *pCell = pPage->aOvfl[0].pCell;
+    u16 szCell = cellSizePtr(pPage, pCell);
+    u8 *pStop;
+
+    assert( sqlite3PagerIswriteable(pNew->pDbPage) );
+    assert( pPage->aData[0]==(PTF_INTKEY|PTF_LEAFDATA|PTF_LEAF) );
+    zeroPage(pNew, PTF_INTKEY|PTF_LEAFDATA|PTF_LEAF);
+    assemblePage(pNew, 1, &pCell, &szCell);
+
+    /* If this is an auto-vacuum database, update the pointer map
+    ** with entries for the new page, and any pointer from the 
+    ** cell on the page to an overflow page. If either of these
+    ** operations fails, the return code is set, but the contents
+    ** of the parent page are still manipulated by thh code below.
+    ** That is Ok, at this point the parent page is guaranteed to
+    ** be marked as dirty. Returning an error code will cause a
+    ** rollback, undoing any changes made to the parent page.
+    */
+    if( ISAUTOVACUUM ){
+      ptrmapPut(pBt, pgnoNew, PTRMAP_BTREE, pParent->pgno, &rc);
+      if( szCell>pNew->minLocal ){
+        ptrmapPutOvflPtr(pNew, pCell, &rc);
+      }
+    }
+  
+    /* Create a divider cell to insert into pParent. The divider cell
+    ** consists of a 4-byte page number (the page number of pPage) and
+    ** a variable length key value (which must be the same value as the
+    ** largest key on pPage).
+    **
+    ** To find the largest key value on pPage, first find the right-most 
+    ** cell on pPage. The first two fields of this cell are the 
+    ** record-length (a variable length integer at most 32-bits in size)
+    ** and the key value (a variable length integer, may have any value).
+    ** The first of the while(...) loops below skips over the record-length
+    ** field. The second while(...) loop copies the key value from the
+    ** cell on pPage into the pSpace buffer.
+    */
+    pCell = findCell(pPage, pPage->nCell-1);
+    pStop = &pCell[9];
+    while( (*(pCell++)&0x80) && pCell<pStop );
+    pStop = &pCell[9];
+    while( ((*(pOut++) = *(pCell++))&0x80) && pCell<pStop );
+
+    /* Insert the new divider cell into pParent. */
+    insertCell(pParent, pParent->nCell, pSpace, (int)(pOut-pSpace),
+               0, pPage->pgno, &rc);
+
+    /* Set the right-child pointer of pParent to point to the new page. */
+    put4byte(&pParent->aData[pParent->hdrOffset+8], pgnoNew);
+  
+    /* Release the reference to the new page. */
+    releasePage(pNew);
+  }
+
+  return rc;
+}
+#endif /* SQLITE_OMIT_QUICKBALANCE */
+
+#if 0
+/*
+** This function does not contribute anything to the operation of SQLite.
+** it is sometimes activated temporarily while debugging code responsible 
+** for setting pointer-map entries.
+*/
+static int ptrmapCheckPages(MemPage **apPage, int nPage){
+  int i, j;
+  for(i=0; i<nPage; i++){
+    Pgno n;
+    u8 e;
+    MemPage *pPage = apPage[i];
+    BtShared *pBt = pPage->pBt;
+    assert( pPage->isInit );
+
+    for(j=0; j<pPage->nCell; j++){
+      CellInfo info;
+      u8 *z;
+     
+      z = findCell(pPage, j);
+      btreeParseCellPtr(pPage, z, &info);
+      if( info.iOverflow ){
+        Pgno ovfl = get4byte(&z[info.iOverflow]);
+        ptrmapGet(pBt, ovfl, &e, &n);
+        assert( n==pPage->pgno && e==PTRMAP_OVERFLOW1 );
+      }
+      if( !pPage->leaf ){
+        Pgno child = get4byte(z);
+        ptrmapGet(pBt, child, &e, &n);
+        assert( n==pPage->pgno && e==PTRMAP_BTREE );
+      }
+    }
+    if( !pPage->leaf ){
+      Pgno child = get4byte(&pPage->aData[pPage->hdrOffset+8]);
+      ptrmapGet(pBt, child, &e, &n);
+      assert( n==pPage->pgno && e==PTRMAP_BTREE );
+    }
+  }
+  return 1;
+}
+#endif
+
+/*
+** This function is used to copy the contents of the b-tree node stored 
+** on page pFrom to page pTo. If page pFrom was not a leaf page, then
+** the pointer-map entries for each child page are updated so that the
+** parent page stored in the pointer map is page pTo. If pFrom contained
+** any cells with overflow page pointers, then the corresponding pointer
+** map entries are also updated so that the parent page is page pTo.
+**
+** If pFrom is currently carrying any overflow cells (entries in the
+** MemPage.aOvfl[] array), they are not copied to pTo. 
+**
+** Before returning, page pTo is reinitialized using btreeInitPage().
+**
+** The performance of this function is not critical. It is only used by 
+** the balance_shallower() and balance_deeper() procedures, neither of
+** which are called often under normal circumstances.
+*/
+static void copyNodeContent(MemPage *pFrom, MemPage *pTo, int *pRC){
+  if( (*pRC)==SQLITE_OK ){
+    BtShared * const pBt = pFrom->pBt;
+    u8 * const aFrom = pFrom->aData;
+    u8 * const aTo = pTo->aData;
+    int const iFromHdr = pFrom->hdrOffset;
+    int const iToHdr = ((pTo->pgno==1) ? 100 : 0);
+    int rc;
+    int iData;
+  
+  
+    assert( pFrom->isInit );
+    assert( pFrom->nFree>=iToHdr );
+    assert( get2byte(&aFrom[iFromHdr+5]) <= (int)pBt->usableSize );
+  
+    /* Copy the b-tree node content from page pFrom to page pTo. */
+    iData = get2byte(&aFrom[iFromHdr+5]);
+    memcpy(&aTo[iData], &aFrom[iData], pBt->usableSize-iData);
+    memcpy(&aTo[iToHdr], &aFrom[iFromHdr], pFrom->cellOffset + 2*pFrom->nCell);
+  
+    /* Reinitialize page pTo so that the contents of the MemPage structure
+    ** match the new data. The initialization of pTo can actually fail under
+    ** fairly obscure circumstances, even though it is a copy of initialized 
+    ** page pFrom.
+    */
+    pTo->isInit = 0;
+    rc = btreeInitPage(pTo);
+    if( rc!=SQLITE_OK ){
+      *pRC = rc;
+      return;
+    }
+  
+    /* If this is an auto-vacuum database, update the pointer-map entries
+    ** for any b-tree or overflow pages that pTo now contains the pointers to.
+    */
+    if( ISAUTOVACUUM ){
+      *pRC = setChildPtrmaps(pTo);
+    }
+  }
+}
+
+/*
+** This routine redistributes cells on the iParentIdx'th child of pParent
+** (hereafter "the page") and up to 2 siblings so that all pages have about the
+** same amount of free space. Usually a single sibling on either side of the
+** page are used in the balancing, though both siblings might come from one
+** side if the page is the first or last child of its parent. If the page 
+** has fewer than 2 siblings (something which can only happen if the page
+** is a root page or a child of a root page) then all available siblings
+** participate in the balancing.
+**
+** The number of siblings of the page might be increased or decreased by 
+** one or two in an effort to keep pages nearly full but not over full. 
+**
+** Note that when this routine is called, some of the cells on the page
+** might not actually be stored in MemPage.aData[]. This can happen
+** if the page is overfull. This routine ensures that all cells allocated
+** to the page and its siblings fit into MemPage.aData[] before returning.
+**
+** In the course of balancing the page and its siblings, cells may be
+** inserted into or removed from the parent page (pParent). Doing so
+** may cause the parent page to become overfull or underfull. If this
+** happens, it is the responsibility of the caller to invoke the correct
+** balancing routine to fix this problem (see the balance() routine). 
+**
+** If this routine fails for any reason, it might leave the database
+** in a corrupted state. So if this routine fails, the database should
+** be rolled back.
+**
+** The third argument to this function, aOvflSpace, is a pointer to a
+** buffer big enough to hold one page. If while inserting cells into the parent
+** page (pParent) the parent page becomes overfull, this buffer is
+** used to store the parent's overflow cells. Because this function inserts
+** a maximum of four divider cells into the parent page, and the maximum
+** size of a cell stored within an internal node is always less than 1/4
+** of the page-size, the aOvflSpace[] buffer is guaranteed to be large
+** enough for all overflow cells.
+**
+** If aOvflSpace is set to a null pointer, this function returns 
+** SQLITE_NOMEM.
+*/
+static int balance_nonroot(
+  MemPage *pParent,               /* Parent page of siblings being balanced */
+  int iParentIdx,                 /* Index of "the page" in pParent */
+  u8 *aOvflSpace,                 /* page-size bytes of space for parent ovfl */
+  int isRoot                      /* True if pParent is a root-page */
+){
+  BtShared *pBt;               /* The whole database */
+  int nCell = 0;               /* Number of cells in apCell[] */
+  int nMaxCells = 0;           /* Allocated size of apCell, szCell, aFrom. */
+  int nNew = 0;                /* Number of pages in apNew[] */
+  int nOld;                    /* Number of pages in apOld[] */
+  int i, j, k;                 /* Loop counters */
+  int nxDiv;                   /* Next divider slot in pParent->aCell[] */
+  int rc = SQLITE_OK;          /* The return code */
+  u16 leafCorrection;          /* 4 if pPage is a leaf.  0 if not */
+  int leafData;                /* True if pPage is a leaf of a LEAFDATA tree */
+  int usableSpace;             /* Bytes in pPage beyond the header */
+  int pageFlags;               /* Value of pPage->aData[0] */
+  int subtotal;                /* Subtotal of bytes in cells on one page */
+  int iSpace1 = 0;             /* First unused byte of aSpace1[] */
+  int iOvflSpace = 0;          /* First unused byte of aOvflSpace[] */
+  int szScratch;               /* Size of scratch memory requested */
+  MemPage *apOld[NB];          /* pPage and up to two siblings */
+  MemPage *apCopy[NB];         /* Private copies of apOld[] pages */
+  MemPage *apNew[NB+2];        /* pPage and up to NB siblings after balancing */
+  u8 *pRight;                  /* Location in parent of right-sibling pointer */
+  u8 *apDiv[NB-1];             /* Divider cells in pParent */
+  int cntNew[NB+2];            /* Index in aCell[] of cell after i-th page */
+  int szNew[NB+2];             /* Combined size of cells place on i-th page */
+  u8 **apCell = 0;             /* All cells begin balanced */
+  u16 *szCell;                 /* Local size of all cells in apCell[] */
+  u8 *aSpace1;                 /* Space for copies of dividers cells */
+  Pgno pgno;                   /* Temp var to store a page number in */
+
+  pBt = pParent->pBt;
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  assert( sqlite3PagerIswriteable(pParent->pDbPage) );
+
+#if 0
+  TRACE(("BALANCE: begin page %d child of %d\n", pPage->pgno, pParent->pgno));
+#endif
+
+  /* At this point pParent may have at most one overflow cell. And if
+  ** this overflow cell is present, it must be the cell with 
+  ** index iParentIdx. This scenario comes about when this function
+  ** is called (indirectly) from sqlite3BtreeDelete().
+  */
+  assert( pParent->nOverflow==0 || pParent->nOverflow==1 );
+  assert( pParent->nOverflow==0 || pParent->aOvfl[0].idx==iParentIdx );
+
+  if( !aOvflSpace ){
+    return SQLITE_NOMEM;
+  }
+
+  /* Find the sibling pages to balance. Also locate the cells in pParent 
+  ** that divide the siblings. An attempt is made to find NN siblings on 
+  ** either side of pPage. More siblings are taken from one side, however, 
+  ** if there are fewer than NN siblings on the other side. If pParent
+  ** has NB or fewer children then all children of pParent are taken.  
+  **
+  ** This loop also drops the divider cells from the parent page. This
+  ** way, the remainder of the function does not have to deal with any
+  ** overflow cells in the parent page, since if any existed they will
+  ** have already been removed.
+  */
+  i = pParent->nOverflow + pParent->nCell;
+  if( i<2 ){
+    nxDiv = 0;
+    nOld = i+1;
+  }else{
+    nOld = 3;
+    if( iParentIdx==0 ){                 
+      nxDiv = 0;
+    }else if( iParentIdx==i ){
+      nxDiv = i-2;
+    }else{
+      nxDiv = iParentIdx-1;
+    }
+    i = 2;
+  }
+  if( (i+nxDiv-pParent->nOverflow)==pParent->nCell ){
+    pRight = &pParent->aData[pParent->hdrOffset+8];
+  }else{
+    pRight = findCell(pParent, i+nxDiv-pParent->nOverflow);
+  }
+  pgno = get4byte(pRight);
+  while( 1 ){
+    rc = getAndInitPage(pBt, pgno, &apOld[i]);
+    if( rc ){
+      memset(apOld, 0, (i+1)*sizeof(MemPage*));
+      goto balance_cleanup;
+    }
+    nMaxCells += 1+apOld[i]->nCell+apOld[i]->nOverflow;
+    if( (i--)==0 ) break;
+
+    if( i+nxDiv==pParent->aOvfl[0].idx && pParent->nOverflow ){
+      apDiv[i] = pParent->aOvfl[0].pCell;
+      pgno = get4byte(apDiv[i]);
+      szNew[i] = cellSizePtr(pParent, apDiv[i]);
+      pParent->nOverflow = 0;
+    }else{
+      apDiv[i] = findCell(pParent, i+nxDiv-pParent->nOverflow);
+      pgno = get4byte(apDiv[i]);
+      szNew[i] = cellSizePtr(pParent, apDiv[i]);
+
+      /* Drop the cell from the parent page. apDiv[i] still points to
+      ** the cell within the parent, even though it has been dropped.
+      ** This is safe because dropping a cell only overwrites the first
+      ** four bytes of it, and this function does not need the first
+      ** four bytes of the divider cell. So the pointer is safe to use
+      ** later on.  
+      **
+      ** Unless SQLite is compiled in secure-delete mode. In this case,
+      ** the dropCell() routine will overwrite the entire cell with zeroes.
+      ** In this case, temporarily copy the cell into the aOvflSpace[]
+      ** buffer. It will be copied out again as soon as the aSpace[] buffer
+      ** is allocated.  */
+      if( pBt->secureDelete ){
+        int iOff = SQLITE_PTR_TO_INT(apDiv[i]) - SQLITE_PTR_TO_INT(pParent->aData);
+        if( (iOff+szNew[i])>(int)pBt->usableSize ){
+          rc = SQLITE_CORRUPT_BKPT;
+          memset(apOld, 0, (i+1)*sizeof(MemPage*));
+          goto balance_cleanup;
+        }else{
+          memcpy(&aOvflSpace[iOff], apDiv[i], szNew[i]);
+          apDiv[i] = &aOvflSpace[apDiv[i]-pParent->aData];
+        }
+      }
+      dropCell(pParent, i+nxDiv-pParent->nOverflow, szNew[i], &rc);
+    }
+  }
+
+  /* Make nMaxCells a multiple of 4 in order to preserve 8-byte
+  ** alignment */
+  nMaxCells = (nMaxCells + 3)&~3;
+
+  /*
+  ** Allocate space for memory structures
+  */
+  k = pBt->pageSize + ROUND8(sizeof(MemPage));
+  szScratch =
+       nMaxCells*sizeof(u8*)                       /* apCell */
+     + nMaxCells*sizeof(u16)                       /* szCell */
+     + pBt->pageSize                               /* aSpace1 */
+     + k*nOld;                                     /* Page copies (apCopy) */
+  apCell = sqlite3ScratchMalloc( szScratch ); 
+  if( apCell==0 ){
+    rc = SQLITE_NOMEM;
+    goto balance_cleanup;
+  }
+  szCell = (u16*)&apCell[nMaxCells];
+  aSpace1 = (u8*)&szCell[nMaxCells];
+  assert( EIGHT_BYTE_ALIGNMENT(aSpace1) );
+
+  /*
+  ** Load pointers to all cells on sibling pages and the divider cells
+  ** into the local apCell[] array.  Make copies of the divider cells
+  ** into space obtained from aSpace1[] and remove the the divider Cells
+  ** from pParent.
+  **
+  ** If the siblings are on leaf pages, then the child pointers of the
+  ** divider cells are stripped from the cells before they are copied
+  ** into aSpace1[].  In this way, all cells in apCell[] are without
+  ** child pointers.  If siblings are not leaves, then all cell in
+  ** apCell[] include child pointers.  Either way, all cells in apCell[]
+  ** are alike.
+  **
+  ** leafCorrection:  4 if pPage is a leaf.  0 if pPage is not a leaf.
+  **       leafData:  1 if pPage holds key+data and pParent holds only keys.
+  */
+  leafCorrection = apOld[0]->leaf*4;
+  leafData = apOld[0]->hasData;
+  for(i=0; i<nOld; i++){
+    int limit;
+    
+    /* Before doing anything else, take a copy of the i'th original sibling
+    ** The rest of this function will use data from the copies rather
+    ** that the original pages since the original pages will be in the
+    ** process of being overwritten.  */
+    MemPage *pOld = apCopy[i] = (MemPage*)&aSpace1[pBt->pageSize + k*i];
+    memcpy(pOld, apOld[i], sizeof(MemPage));
+    pOld->aData = (void*)&pOld[1];
+    memcpy(pOld->aData, apOld[i]->aData, pBt->pageSize);
+
+    limit = pOld->nCell+pOld->nOverflow;
+    for(j=0; j<limit; j++){
+      assert( nCell<nMaxCells );
+      apCell[nCell] = findOverflowCell(pOld, j);
+      szCell[nCell] = cellSizePtr(pOld, apCell[nCell]);
+      nCell++;
+    }
+    if( i<nOld-1 && !leafData){
+      u16 sz = (u16)szNew[i];
+      u8 *pTemp;
+      assert( nCell<nMaxCells );
+      szCell[nCell] = sz;
+      pTemp = &aSpace1[iSpace1];
+      iSpace1 += sz;
+      assert( sz<=pBt->maxLocal+23 );
+      assert( iSpace1 <= (int)pBt->pageSize );
+      memcpy(pTemp, apDiv[i], sz);
+      apCell[nCell] = pTemp+leafCorrection;
+      assert( leafCorrection==0 || leafCorrection==4 );
+      szCell[nCell] = szCell[nCell] - leafCorrection;
+      if( !pOld->leaf ){
+        assert( leafCorrection==0 );
+        assert( pOld->hdrOffset==0 );
+        /* The right pointer of the child page pOld becomes the left
+        ** pointer of the divider cell */
+        memcpy(apCell[nCell], &pOld->aData[8], 4);
+      }else{
+        assert( leafCorrection==4 );
+        if( szCell[nCell]<4 ){
+          /* Do not allow any cells smaller than 4 bytes. */
+          szCell[nCell] = 4;
+        }
+      }
+      nCell++;
+    }
+  }
+
+  /*
+  ** Figure out the number of pages needed to hold all nCell cells.
+  ** Store this number in "k".  Also compute szNew[] which is the total
+  ** size of all cells on the i-th page and cntNew[] which is the index
+  ** in apCell[] of the cell that divides page i from page i+1.  
+  ** cntNew[k] should equal nCell.
+  **
+  ** Values computed by this block:
+  **
+  **           k: The total number of sibling pages
+  **    szNew[i]: Spaced used on the i-th sibling page.
+  **   cntNew[i]: Index in apCell[] and szCell[] for the first cell to
+  **              the right of the i-th sibling page.
+  ** usableSpace: Number of bytes of space available on each sibling.
+  ** 
+  */
+  usableSpace = pBt->usableSize - 12 + leafCorrection;
+  for(subtotal=k=i=0; i<nCell; i++){
+    assert( i<nMaxCells );
+    subtotal += szCell[i] + 2;
+    if( subtotal > usableSpace ){
+      szNew[k] = subtotal - szCell[i];
+      cntNew[k] = i;
+      if( leafData ){ i--; }
+      subtotal = 0;
+      k++;
+      if( k>NB+1 ){ rc = SQLITE_CORRUPT_BKPT; goto balance_cleanup; }
+    }
+  }
+  szNew[k] = subtotal;
+  cntNew[k] = nCell;
+  k++;
+
+  /*
+  ** The packing computed by the previous block is biased toward the siblings
+  ** on the left side.  The left siblings are always nearly full, while the
+  ** right-most sibling might be nearly empty.  This block of code attempts
+  ** to adjust the packing of siblings to get a better balance.
+  **
+  ** This adjustment is more than an optimization.  The packing above might
+  ** be so out of balance as to be illegal.  For example, the right-most
+  ** sibling might be completely empty.  This adjustment is not optional.
+  */
+  for(i=k-1; i>0; i--){
+    int szRight = szNew[i];  /* Size of sibling on the right */
+    int szLeft = szNew[i-1]; /* Size of sibling on the left */
+    int r;              /* Index of right-most cell in left sibling */
+    int d;              /* Index of first cell to the left of right sibling */
+
+    r = cntNew[i-1] - 1;
+    d = r + 1 - leafData;
+    assert( d<nMaxCells );
+    assert( r<nMaxCells );
+    while( szRight==0 || szRight+szCell[d]+2<=szLeft-(szCell[r]+2) ){
+      szRight += szCell[d] + 2;
+      szLeft -= szCell[r] + 2;
+      cntNew[i-1]--;
+      r = cntNew[i-1] - 1;
+      d = r + 1 - leafData;
+    }
+    szNew[i] = szRight;
+    szNew[i-1] = szLeft;
+  }
+
+  /* Either we found one or more cells (cntnew[0])>0) or pPage is
+  ** a virtual root page.  A virtual root page is when the real root
+  ** page is page 1 and we are the only child of that page.
+  */
+  assert( cntNew[0]>0 || (pParent->pgno==1 && pParent->nCell==0) );
+
+  TRACE(("BALANCE: old: %d %d %d  ",
+    apOld[0]->pgno, 
+    nOld>=2 ? apOld[1]->pgno : 0,
+    nOld>=3 ? apOld[2]->pgno : 0
+  ));
+
+  /*
+  ** Allocate k new pages.  Reuse old pages where possible.
+  */
+  if( apOld[0]->pgno<=1 ){
+    rc = SQLITE_CORRUPT_BKPT;
+    goto balance_cleanup;
+  }
+  pageFlags = apOld[0]->aData[0];
+  for(i=0; i<k; i++){
+    MemPage *pNew;
+    if( i<nOld ){
+      pNew = apNew[i] = apOld[i];
+      apOld[i] = 0;
+      rc = sqlite3PagerWrite(pNew->pDbPage);
+      nNew++;
+      if( rc ) goto balance_cleanup;
+    }else{
+      assert( i>0 );
+      rc = allocateBtreePage(pBt, &pNew, &pgno, pgno, 0);
+      if( rc ) goto balance_cleanup;
+      apNew[i] = pNew;
+      nNew++;
+
+      /* Set the pointer-map entry for the new sibling page. */
+      if( ISAUTOVACUUM ){
+        ptrmapPut(pBt, pNew->pgno, PTRMAP_BTREE, pParent->pgno, &rc);
+        if( rc!=SQLITE_OK ){
+          goto balance_cleanup;
+        }
+      }
+    }
+  }
+
+  /* Free any old pages that were not reused as new pages.
+  */
+  while( i<nOld ){
+    freePage(apOld[i], &rc);
+    if( rc ) goto balance_cleanup;
+    releasePage(apOld[i]);
+    apOld[i] = 0;
+    i++;
+  }
+
+  /*
+  ** Put the new pages in accending order.  This helps to
+  ** keep entries in the disk file in order so that a scan
+  ** of the table is a linear scan through the file.  That
+  ** in turn helps the operating system to deliver pages
+  ** from the disk more rapidly.
+  **
+  ** An O(n^2) insertion sort algorithm is used, but since
+  ** n is never more than NB (a small constant), that should
+  ** not be a problem.
+  **
+  ** When NB==3, this one optimization makes the database
+  ** about 25% faster for large insertions and deletions.
+  */
+  for(i=0; i<k-1; i++){
+    int minV = apNew[i]->pgno;
+    int minI = i;
+    for(j=i+1; j<k; j++){
+      if( apNew[j]->pgno<(unsigned)minV ){
+        minI = j;
+        minV = apNew[j]->pgno;
+      }
+    }
+    if( minI>i ){
+      MemPage *pT;
+      pT = apNew[i];
+      apNew[i] = apNew[minI];
+      apNew[minI] = pT;
+    }
+  }
+  TRACE(("new: %d(%d) %d(%d) %d(%d) %d(%d) %d(%d)\n",
+    apNew[0]->pgno, szNew[0],
+    nNew>=2 ? apNew[1]->pgno : 0, nNew>=2 ? szNew[1] : 0,
+    nNew>=3 ? apNew[2]->pgno : 0, nNew>=3 ? szNew[2] : 0,
+    nNew>=4 ? apNew[3]->pgno : 0, nNew>=4 ? szNew[3] : 0,
+    nNew>=5 ? apNew[4]->pgno : 0, nNew>=5 ? szNew[4] : 0));
+
+  assert( sqlite3PagerIswriteable(pParent->pDbPage) );
+  put4byte(pRight, apNew[nNew-1]->pgno);
+
+  /*
+  ** Evenly distribute the data in apCell[] across the new pages.
+  ** Insert divider cells into pParent as necessary.
+  */
+  j = 0;
+  for(i=0; i<nNew; i++){
+    /* Assemble the new sibling page. */
+    MemPage *pNew = apNew[i];
+    assert( j<nMaxCells );
+    zeroPage(pNew, pageFlags);
+    assemblePage(pNew, cntNew[i]-j, &apCell[j], &szCell[j]);
+    assert( pNew->nCell>0 || (nNew==1 && cntNew[0]==0) );
+    assert( pNew->nOverflow==0 );
+
+    j = cntNew[i];
+
+    /* If the sibling page assembled above was not the right-most sibling,
+    ** insert a divider cell into the parent page.
+    */
+    assert( i<nNew-1 || j==nCell );
+    if( j<nCell ){
+      u8 *pCell;
+      u8 *pTemp;
+      int sz;
+
+      assert( j<nMaxCells );
+      pCell = apCell[j];
+      sz = szCell[j] + leafCorrection;
+      pTemp = &aOvflSpace[iOvflSpace];
+      if( !pNew->leaf ){
+        memcpy(&pNew->aData[8], pCell, 4);
+      }else if( leafData ){
+        /* If the tree is a leaf-data tree, and the siblings are leaves, 
+        ** then there is no divider cell in apCell[]. Instead, the divider 
+        ** cell consists of the integer key for the right-most cell of 
+        ** the sibling-page assembled above only.
+        */
+        CellInfo info;
+        j--;
+        btreeParseCellPtr(pNew, apCell[j], &info);
+        pCell = pTemp;
+        sz = 4 + putVarint(&pCell[4], info.nKey);
+        pTemp = 0;
+      }else{
+        pCell -= 4;
+        /* Obscure case for non-leaf-data trees: If the cell at pCell was
+        ** previously stored on a leaf node, and its reported size was 4
+        ** bytes, then it may actually be smaller than this 
+        ** (see btreeParseCellPtr(), 4 bytes is the minimum size of
+        ** any cell). But it is important to pass the correct size to 
+        ** insertCell(), so reparse the cell now.
+        **
+        ** Note that this can never happen in an SQLite data file, as all
+        ** cells are at least 4 bytes. It only happens in b-trees used
+        ** to evaluate "IN (SELECT ...)" and similar clauses.
+        */
+        if( szCell[j]==4 ){
+          assert(leafCorrection==4);
+          sz = cellSizePtr(pParent, pCell);
+        }
+      }
+      iOvflSpace += sz;
+      assert( sz<=pBt->maxLocal+23 );
+      assert( iOvflSpace <= (int)pBt->pageSize );
+      insertCell(pParent, nxDiv, pCell, sz, pTemp, pNew->pgno, &rc);
+      if( rc!=SQLITE_OK ) goto balance_cleanup;
+      assert( sqlite3PagerIswriteable(pParent->pDbPage) );
+
+      j++;
+      nxDiv++;
+    }
+  }
+  assert( j==nCell );
+  assert( nOld>0 );
+  assert( nNew>0 );
+  if( (pageFlags & PTF_LEAF)==0 ){
+    u8 *zChild = &apCopy[nOld-1]->aData[8];
+    memcpy(&apNew[nNew-1]->aData[8], zChild, 4);
+  }
+
+  if( isRoot && pParent->nCell==0 && pParent->hdrOffset<=apNew[0]->nFree ){
+    /* The root page of the b-tree now contains no cells. The only sibling
+    ** page is the right-child of the parent. Copy the contents of the
+    ** child page into the parent, decreasing the overall height of the
+    ** b-tree structure by one. This is described as the "balance-shallower"
+    ** sub-algorithm in some documentation.
+    **
+    ** If this is an auto-vacuum database, the call to copyNodeContent() 
+    ** sets all pointer-map entries corresponding to database image pages 
+    ** for which the pointer is stored within the content being copied.
+    **
+    ** The second assert below verifies that the child page is defragmented
+    ** (it must be, as it was just reconstructed using assemblePage()). This
+    ** is important if the parent page happens to be page 1 of the database
+    ** image.  */
+    assert( nNew==1 );
+    assert( apNew[0]->nFree == 
+        (get2byte(&apNew[0]->aData[5])-apNew[0]->cellOffset-apNew[0]->nCell*2) 
+    );
+    copyNodeContent(apNew[0], pParent, &rc);
+    freePage(apNew[0], &rc);
+  }else if( ISAUTOVACUUM ){
+    /* Fix the pointer-map entries for all the cells that were shifted around. 
+    ** There are several different types of pointer-map entries that need to
+    ** be dealt with by this routine. Some of these have been set already, but
+    ** many have not. The following is a summary:
+    **
+    **   1) The entries associated with new sibling pages that were not
+    **      siblings when this function was called. These have already
+    **      been set. We don't need to worry about old siblings that were
+    **      moved to the free-list - the freePage() code has taken care
+    **      of those.
+    **
+    **   2) The pointer-map entries associated with the first overflow
+    **      page in any overflow chains used by new divider cells. These 
+    **      have also already been taken care of by the insertCell() code.
+    **
+    **   3) If the sibling pages are not leaves, then the child pages of
+    **      cells stored on the sibling pages may need to be updated.
+    **
+    **   4) If the sibling pages are not internal intkey nodes, then any
+    **      overflow pages used by these cells may need to be updated
+    **      (internal intkey nodes never contain pointers to overflow pages).
+    **
+    **   5) If the sibling pages are not leaves, then the pointer-map
+    **      entries for the right-child pages of each sibling may need
+    **      to be updated.
+    **
+    ** Cases 1 and 2 are dealt with above by other code. The next
+    ** block deals with cases 3 and 4 and the one after that, case 5. Since
+    ** setting a pointer map entry is a relatively expensive operation, this
+    ** code only sets pointer map entries for child or overflow pages that have
+    ** actually moved between pages.  */
+    MemPage *pNew = apNew[0];
+    MemPage *pOld = apCopy[0];
+    int nOverflow = pOld->nOverflow;
+    int iNextOld = pOld->nCell + nOverflow;
+    int iOverflow = (nOverflow ? pOld->aOvfl[0].idx : -1);
+    j = 0;                             /* Current 'old' sibling page */
+    k = 0;                             /* Current 'new' sibling page */
+    for(i=0; i<nCell; i++){
+      int isDivider = 0;
+      while( i==iNextOld ){
+        /* Cell i is the cell immediately following the last cell on old
+        ** sibling page j. If the siblings are not leaf pages of an
+        ** intkey b-tree, then cell i was a divider cell. */
+        pOld = apCopy[++j];
+        iNextOld = i + !leafData + pOld->nCell + pOld->nOverflow;
+        if( pOld->nOverflow ){
+          nOverflow = pOld->nOverflow;
+          iOverflow = i + !leafData + pOld->aOvfl[0].idx;
+        }
+        isDivider = !leafData;  
+      }
+
+      assert(nOverflow>0 || iOverflow<i );
+      assert(nOverflow<2 || pOld->aOvfl[0].idx==pOld->aOvfl[1].idx-1);
+      assert(nOverflow<3 || pOld->aOvfl[1].idx==pOld->aOvfl[2].idx-1);
+      if( i==iOverflow ){
+        isDivider = 1;
+        if( (--nOverflow)>0 ){
+          iOverflow++;
+        }
+      }
+
+      if( i==cntNew[k] ){
+        /* Cell i is the cell immediately following the last cell on new
+        ** sibling page k. If the siblings are not leaf pages of an
+        ** intkey b-tree, then cell i is a divider cell.  */
+        pNew = apNew[++k];
+        if( !leafData ) continue;
+      }
+      assert( j<nOld );
+      assert( k<nNew );
+
+      /* If the cell was originally divider cell (and is not now) or
+      ** an overflow cell, or if the cell was located on a different sibling
+      ** page before the balancing, then the pointer map entries associated
+      ** with any child or overflow pages need to be updated.  */
+      if( isDivider || pOld->pgno!=pNew->pgno ){
+        if( !leafCorrection ){
+          ptrmapPut(pBt, get4byte(apCell[i]), PTRMAP_BTREE, pNew->pgno, &rc);
+        }
+        if( szCell[i]>pNew->minLocal ){
+          ptrmapPutOvflPtr(pNew, apCell[i], &rc);
+        }
+      }
+    }
+
+    if( !leafCorrection ){
+      for(i=0; i<nNew; i++){
+        u32 key = get4byte(&apNew[i]->aData[8]);
+        ptrmapPut(pBt, key, PTRMAP_BTREE, apNew[i]->pgno, &rc);
+      }
+    }
+
+#if 0
+    /* The ptrmapCheckPages() contains assert() statements that verify that
+    ** all pointer map pages are set correctly. This is helpful while 
+    ** debugging. This is usually disabled because a corrupt database may
+    ** cause an assert() statement to fail.  */
+    ptrmapCheckPages(apNew, nNew);
+    ptrmapCheckPages(&pParent, 1);
+#endif
+  }
+
+  assert( pParent->isInit );
+  TRACE(("BALANCE: finished: old=%d new=%d cells=%d\n",
+          nOld, nNew, nCell));
+
+  /*
+  ** Cleanup before returning.
+  */
+balance_cleanup:
+  sqlite3ScratchFree(apCell);
+  for(i=0; i<nOld; i++){
+    releasePage(apOld[i]);
+  }
+  for(i=0; i<nNew; i++){
+    releasePage(apNew[i]);
+  }
+
+  return rc;
+}
+
+
+/*
+** This function is called when the root page of a b-tree structure is
+** overfull (has one or more overflow pages).
+**
+** A new child page is allocated and the contents of the current root
+** page, including overflow cells, are copied into the child. The root
+** page is then overwritten to make it an empty page with the right-child 
+** pointer pointing to the new page.
+**
+** Before returning, all pointer-map entries corresponding to pages 
+** that the new child-page now contains pointers to are updated. The
+** entry corresponding to the new right-child pointer of the root
+** page is also updated.
+**
+** If successful, *ppChild is set to contain a reference to the child 
+** page and SQLITE_OK is returned. In this case the caller is required
+** to call releasePage() on *ppChild exactly once. If an error occurs,
+** an error code is returned and *ppChild is set to 0.
+*/
+static int balance_deeper(MemPage *pRoot, MemPage **ppChild){
+  int rc;                        /* Return value from subprocedures */
+  MemPage *pChild = 0;           /* Pointer to a new child page */
+  Pgno pgnoChild = 0;            /* Page number of the new child page */
+  BtShared *pBt = pRoot->pBt;    /* The BTree */
+
+  assert( pRoot->nOverflow>0 );
+  assert( sqlite3_mutex_held(pBt->mutex) );
+
+  /* Make pRoot, the root page of the b-tree, writable. Allocate a new 
+  ** page that will become the new right-child of pPage. Copy the contents
+  ** of the node stored on pRoot into the new child page.
+  */
+  rc = sqlite3PagerWrite(pRoot->pDbPage);
+  if( rc==SQLITE_OK ){
+    rc = allocateBtreePage(pBt,&pChild,&pgnoChild,pRoot->pgno,0);
+    copyNodeContent(pRoot, pChild, &rc);
+    if( ISAUTOVACUUM ){
+      ptrmapPut(pBt, pgnoChild, PTRMAP_BTREE, pRoot->pgno, &rc);
+    }
+  }
+  if( rc ){
+    *ppChild = 0;
+    releasePage(pChild);
+    return rc;
+  }
+  assert( sqlite3PagerIswriteable(pChild->pDbPage) );
+  assert( sqlite3PagerIswriteable(pRoot->pDbPage) );
+  assert( pChild->nCell==pRoot->nCell );
+
+  TRACE(("BALANCE: copy root %d into %d\n", pRoot->pgno, pChild->pgno));
+
+  /* Copy the overflow cells from pRoot to pChild */
+  memcpy(pChild->aOvfl, pRoot->aOvfl, pRoot->nOverflow*sizeof(pRoot->aOvfl[0]));
+  pChild->nOverflow = pRoot->nOverflow;
+
+  /* Zero the contents of pRoot. Then install pChild as the right-child. */
+  zeroPage(pRoot, pChild->aData[0] & ~PTF_LEAF);
+  put4byte(&pRoot->aData[pRoot->hdrOffset+8], pgnoChild);
+
+  *ppChild = pChild;
+  return SQLITE_OK;
+}
+
+/*
+** The page that pCur currently points to has just been modified in
+** some way. This function figures out if this modification means the
+** tree needs to be balanced, and if so calls the appropriate balancing 
+** routine. Balancing routines are:
+**
+**   balance_quick()
+**   balance_deeper()
+**   balance_nonroot()
+*/
+static int balance(BtCursor *pCur){
+  int rc = SQLITE_OK;
+  const int nMin = pCur->pBt->usableSize * 2 / 3;
+  u8 aBalanceQuickSpace[13];
+  u8 *pFree = 0;
+
+  TESTONLY( int balance_quick_called = 0 );
+  TESTONLY( int balance_deeper_called = 0 );
+
+  do {
+    int iPage = pCur->iPage;
+    MemPage *pPage = pCur->apPage[iPage];
+
+    if( iPage==0 ){
+      if( pPage->nOverflow ){
+        /* The root page of the b-tree is overfull. In this case call the
+        ** balance_deeper() function to create a new child for the root-page
+        ** and copy the current contents of the root-page to it. The
+        ** next iteration of the do-loop will balance the child page.
+        */ 
+        assert( (balance_deeper_called++)==0 );
+        rc = balance_deeper(pPage, &pCur->apPage[1]);
+        if( rc==SQLITE_OK ){
+          pCur->iPage = 1;
+          pCur->aiIdx[0] = 0;
+          pCur->aiIdx[1] = 0;
+          assert( pCur->apPage[1]->nOverflow );
+        }
+      }else{
+        break;
+      }
+    }else if( pPage->nOverflow==0 && pPage->nFree<=nMin ){
+      break;
+    }else{
+      MemPage * const pParent = pCur->apPage[iPage-1];
+      int const iIdx = pCur->aiIdx[iPage-1];
+
+      rc = sqlite3PagerWrite(pParent->pDbPage);
+      if( rc==SQLITE_OK ){
+#ifndef SQLITE_OMIT_QUICKBALANCE
+        if( pPage->hasData
+         && pPage->nOverflow==1
+         && pPage->aOvfl[0].idx==pPage->nCell
+         && pParent->pgno!=1
+         && pParent->nCell==iIdx
+        ){
+          /* Call balance_quick() to create a new sibling of pPage on which
+          ** to store the overflow cell. balance_quick() inserts a new cell
+          ** into pParent, which may cause pParent overflow. If this
+          ** happens, the next interation of the do-loop will balance pParent 
+          ** use either balance_nonroot() or balance_deeper(). Until this
+          ** happens, the overflow cell is stored in the aBalanceQuickSpace[]
+          ** buffer. 
+          **
+          ** The purpose of the following assert() is to check that only a
+          ** single call to balance_quick() is made for each call to this
+          ** function. If this were not verified, a subtle bug involving reuse
+          ** of the aBalanceQuickSpace[] might sneak in.
+          */
+          assert( (balance_quick_called++)==0 );
+          rc = balance_quick(pParent, pPage, aBalanceQuickSpace);
+        }else
+#endif
+        {
+          /* In this case, call balance_nonroot() to redistribute cells
+          ** between pPage and up to 2 of its sibling pages. This involves
+          ** modifying the contents of pParent, which may cause pParent to
+          ** become overfull or underfull. The next iteration of the do-loop
+          ** will balance the parent page to correct this.
+          ** 
+          ** If the parent page becomes overfull, the overflow cell or cells
+          ** are stored in the pSpace buffer allocated immediately below. 
+          ** A subsequent iteration of the do-loop will deal with this by
+          ** calling balance_nonroot() (balance_deeper() may be called first,
+          ** but it doesn't deal with overflow cells - just moves them to a
+          ** different page). Once this subsequent call to balance_nonroot() 
+          ** has completed, it is safe to release the pSpace buffer used by
+          ** the previous call, as the overflow cell data will have been 
+          ** copied either into the body of a database page or into the new
+          ** pSpace buffer passed to the latter call to balance_nonroot().
+          */
+          u8 *pSpace = sqlite3PageMalloc(pCur->pBt->pageSize);
+          rc = balance_nonroot(pParent, iIdx, pSpace, iPage==1);
+          if( pFree ){
+            /* If pFree is not NULL, it points to the pSpace buffer used 
+            ** by a previous call to balance_nonroot(). Its contents are
+            ** now stored either on real database pages or within the 
+            ** new pSpace buffer, so it may be safely freed here. */
+            sqlite3PageFree(pFree);
+          }
+
+          /* The pSpace buffer will be freed after the next call to
+          ** balance_nonroot(), or just before this function returns, whichever
+          ** comes first. */
+          pFree = pSpace;
+        }
+      }
+
+      pPage->nOverflow = 0;
+
+      /* The next iteration of the do-loop balances the parent page. */
+      releasePage(pPage);
+      pCur->iPage--;
+    }
+  }while( rc==SQLITE_OK );
+
+  if( pFree ){
+    sqlite3PageFree(pFree);
+  }
+  return rc;
+}
+
+
+/*
+** Insert a new record into the BTree.  The key is given by (pKey,nKey)
+** and the data is given by (pData,nData).  The cursor is used only to
+** define what table the record should be inserted into.  The cursor
+** is left pointing at a random location.
+**
+** For an INTKEY table, only the nKey value of the key is used.  pKey is
+** ignored.  For a ZERODATA table, the pData and nData are both ignored.
+**
+** If the seekResult parameter is non-zero, then a successful call to
+** MovetoUnpacked() to seek cursor pCur to (pKey, nKey) has already
+** been performed. seekResult is the search result returned (a negative
+** number if pCur points at an entry that is smaller than (pKey, nKey), or
+** a positive value if pCur points at an etry that is larger than 
+** (pKey, nKey)). 
+**
+** If the seekResult parameter is non-zero, then the caller guarantees that
+** cursor pCur is pointing at the existing copy of a row that is to be
+** overwritten.  If the seekResult parameter is 0, then cursor pCur may
+** point to any entry or to no entry at all and so this function has to seek
+** the cursor before the new key can be inserted.
+*/
+SQLITE_PRIVATE int sqlite3BtreeInsert(
+  BtCursor *pCur,                /* Insert data into the table of this cursor */
+  const void *pKey, i64 nKey,    /* The key of the new record */
+  const void *pData, int nData,  /* The data of the new record */
+  int nZero,                     /* Number of extra 0 bytes to append to data */
+  int appendBias,                /* True if this is likely an append */
+  int seekResult                 /* Result of prior MovetoUnpacked() call */
+){
+  int rc;
+  int loc = seekResult;          /* -1: before desired location  +1: after */
+  int szNew = 0;
+  int idx;
+  MemPage *pPage;
+  Btree *p = pCur->pBtree;
+  BtShared *pBt = p->pBt;
+  unsigned char *oldCell;
+  unsigned char *newCell = 0;
+
+  if( pCur->eState==CURSOR_FAULT ){
+    assert( pCur->skipNext!=SQLITE_OK );
+    return pCur->skipNext;
+  }
+
+  assert( cursorHoldsMutex(pCur) );
+  assert( pCur->wrFlag && pBt->inTransaction==TRANS_WRITE && !pBt->readOnly );
+  assert( hasSharedCacheTableLock(p, pCur->pgnoRoot, pCur->pKeyInfo!=0, 2) );
+
+  /* Assert that the caller has been consistent. If this cursor was opened
+  ** expecting an index b-tree, then the caller should be inserting blob
+  ** keys with no associated data. If the cursor was opened expecting an
+  ** intkey table, the caller should be inserting integer keys with a
+  ** blob of associated data.  */
+  assert( (pKey==0)==(pCur->pKeyInfo==0) );
+
+  /* If this is an insert into a table b-tree, invalidate any incrblob 
+  ** cursors open on the row being replaced (assuming this is a replace
+  ** operation - if it is not, the following is a no-op).  */
+  if( pCur->pKeyInfo==0 ){
+    invalidateIncrblobCursors(p, nKey, 0);
+  }
+
+  /* Save the positions of any other cursors open on this table.
+  **
+  ** In some cases, the call to btreeMoveto() below is a no-op. For
+  ** example, when inserting data into a table with auto-generated integer
+  ** keys, the VDBE layer invokes sqlite3BtreeLast() to figure out the 
+  ** integer key to use. It then calls this function to actually insert the 
+  ** data into the intkey B-Tree. In this case btreeMoveto() recognizes
+  ** that the cursor is already where it needs to be and returns without
+  ** doing any work. To avoid thwarting these optimizations, it is important
+  ** not to clear the cursor here.
+  */
+  rc = saveAllCursors(pBt, pCur->pgnoRoot, pCur);
+  if( rc ) return rc;
+  if( !loc ){
+    rc = btreeMoveto(pCur, pKey, nKey, appendBias, &loc);
+    if( rc ) return rc;
+  }
+  assert( pCur->eState==CURSOR_VALID || (pCur->eState==CURSOR_INVALID && loc) );
+
+  pPage = pCur->apPage[pCur->iPage];
+  assert( pPage->intKey || nKey>=0 );
+  assert( pPage->leaf || !pPage->intKey );
+
+  TRACE(("INSERT: table=%d nkey=%lld ndata=%d page=%d %s\n",
+          pCur->pgnoRoot, nKey, nData, pPage->pgno,
+          loc==0 ? "overwrite" : "new entry"));
+  assert( pPage->isInit );
+  allocateTempSpace(pBt);
+  newCell = pBt->pTmpSpace;
+  if( newCell==0 ) return SQLITE_NOMEM;
+  rc = fillInCell(pPage, newCell, pKey, nKey, pData, nData, nZero, &szNew);
+  if( rc ) goto end_insert;
+  assert( szNew==cellSizePtr(pPage, newCell) );
+  assert( szNew <= MX_CELL_SIZE(pBt) );
+  idx = pCur->aiIdx[pCur->iPage];
+  if( loc==0 ){
+    u16 szOld;
+    assert( idx<pPage->nCell );
+    rc = sqlite3PagerWrite(pPage->pDbPage);
+    if( rc ){
+      goto end_insert;
+    }
+    oldCell = findCell(pPage, idx);
+    if( !pPage->leaf ){
+      memcpy(newCell, oldCell, 4);
+    }
+    szOld = cellSizePtr(pPage, oldCell);
+    rc = clearCell(pPage, oldCell);
+    dropCell(pPage, idx, szOld, &rc);
+    if( rc ) goto end_insert;
+  }else if( loc<0 && pPage->nCell>0 ){
+    assert( pPage->leaf );
+    idx = ++pCur->aiIdx[pCur->iPage];
+  }else{
+    assert( pPage->leaf );
+  }
+  insertCell(pPage, idx, newCell, szNew, 0, 0, &rc);
+  assert( rc!=SQLITE_OK || pPage->nCell>0 || pPage->nOverflow>0 );
+
+  /* If no error has occured and pPage has an overflow cell, call balance() 
+  ** to redistribute the cells within the tree. Since balance() may move
+  ** the cursor, zero the BtCursor.info.nSize and BtCursor.validNKey
+  ** variables.
+  **
+  ** Previous versions of SQLite called moveToRoot() to move the cursor
+  ** back to the root page as balance() used to invalidate the contents
+  ** of BtCursor.apPage[] and BtCursor.aiIdx[]. Instead of doing that,
+  ** set the cursor state to "invalid". This makes common insert operations
+  ** slightly faster.
+  **
+  ** There is a subtle but important optimization here too. When inserting
+  ** multiple records into an intkey b-tree using a single cursor (as can
+  ** happen while processing an "INSERT INTO ... SELECT" statement), it
+  ** is advantageous to leave the cursor pointing to the last entry in
+  ** the b-tree if possible. If the cursor is left pointing to the last
+  ** entry in the table, and the next row inserted has an integer key
+  ** larger than the largest existing key, it is possible to insert the
+  ** row without seeking the cursor. This can be a big performance boost.
+  */
+  pCur->info.nSize = 0;
+  pCur->validNKey = 0;
+  if( rc==SQLITE_OK && pPage->nOverflow ){
+    rc = balance(pCur);
+
+    /* Must make sure nOverflow is reset to zero even if the balance()
+    ** fails. Internal data structure corruption will result otherwise. 
+    ** Also, set the cursor state to invalid. This stops saveCursorPosition()
+    ** from trying to save the current position of the cursor.  */
+    pCur->apPage[pCur->iPage]->nOverflow = 0;
+    pCur->eState = CURSOR_INVALID;
+  }
+  assert( pCur->apPage[pCur->iPage]->nOverflow==0 );
+
+end_insert:
+  return rc;
+}
+
+/*
+** Delete the entry that the cursor is pointing to.  The cursor
+** is left pointing at a arbitrary location.
+*/
+SQLITE_PRIVATE int sqlite3BtreeDelete(BtCursor *pCur){
+  Btree *p = pCur->pBtree;
+  BtShared *pBt = p->pBt;              
+  int rc;                              /* Return code */
+  MemPage *pPage;                      /* Page to delete cell from */
+  unsigned char *pCell;                /* Pointer to cell to delete */
+  int iCellIdx;                        /* Index of cell to delete */
+  int iCellDepth;                      /* Depth of node containing pCell */ 
+
+  assert( cursorHoldsMutex(pCur) );
+  assert( pBt->inTransaction==TRANS_WRITE );
+  assert( !pBt->readOnly );
+  assert( pCur->wrFlag );
+  assert( hasSharedCacheTableLock(p, pCur->pgnoRoot, pCur->pKeyInfo!=0, 2) );
+  assert( !hasReadConflicts(p, pCur->pgnoRoot) );
+
+  if( NEVER(pCur->aiIdx[pCur->iPage]>=pCur->apPage[pCur->iPage]->nCell) 
+   || NEVER(pCur->eState!=CURSOR_VALID)
+  ){
+    return SQLITE_ERROR;  /* Something has gone awry. */
+  }
+
+  /* If this is a delete operation to remove a row from a table b-tree,
+  ** invalidate any incrblob cursors open on the row being deleted.  */
+  if( pCur->pKeyInfo==0 ){
+    invalidateIncrblobCursors(p, pCur->info.nKey, 0);
+  }
+
+  iCellDepth = pCur->iPage;
+  iCellIdx = pCur->aiIdx[iCellDepth];
+  pPage = pCur->apPage[iCellDepth];
+  pCell = findCell(pPage, iCellIdx);
+
+  /* If the page containing the entry to delete is not a leaf page, move
+  ** the cursor to the largest entry in the tree that is smaller than
+  ** the entry being deleted. This cell will replace the cell being deleted
+  ** from the internal node. The 'previous' entry is used for this instead
+  ** of the 'next' entry, as the previous entry is always a part of the
+  ** sub-tree headed by the child page of the cell being deleted. This makes
+  ** balancing the tree following the delete operation easier.  */
+  if( !pPage->leaf ){
+    int notUsed;
+    rc = sqlite3BtreePrevious(pCur, &notUsed);
+    if( rc ) return rc;
+  }
+
+  /* Save the positions of any other cursors open on this table before
+  ** making any modifications. Make the page containing the entry to be 
+  ** deleted writable. Then free any overflow pages associated with the 
+  ** entry and finally remove the cell itself from within the page.  
+  */
+  rc = saveAllCursors(pBt, pCur->pgnoRoot, pCur);
+  if( rc ) return rc;
+  rc = sqlite3PagerWrite(pPage->pDbPage);
+  if( rc ) return rc;
+  rc = clearCell(pPage, pCell);
+  dropCell(pPage, iCellIdx, cellSizePtr(pPage, pCell), &rc);
+  if( rc ) return rc;
+
+  /* If the cell deleted was not located on a leaf page, then the cursor
+  ** is currently pointing to the largest entry in the sub-tree headed
+  ** by the child-page of the cell that was just deleted from an internal
+  ** node. The cell from the leaf node needs to be moved to the internal
+  ** node to replace the deleted cell.  */
+  if( !pPage->leaf ){
+    MemPage *pLeaf = pCur->apPage[pCur->iPage];
+    int nCell;
+    Pgno n = pCur->apPage[iCellDepth+1]->pgno;
+    unsigned char *pTmp;
+
+    pCell = findCell(pLeaf, pLeaf->nCell-1);
+    nCell = cellSizePtr(pLeaf, pCell);
+    assert( MX_CELL_SIZE(pBt) >= nCell );
+
+    allocateTempSpace(pBt);
+    pTmp = pBt->pTmpSpace;
+
+    rc = sqlite3PagerWrite(pLeaf->pDbPage);
+    insertCell(pPage, iCellIdx, pCell-4, nCell+4, pTmp, n, &rc);
+    dropCell(pLeaf, pLeaf->nCell-1, nCell, &rc);
+    if( rc ) return rc;
+  }
+
+  /* Balance the tree. If the entry deleted was located on a leaf page,
+  ** then the cursor still points to that page. In this case the first
+  ** call to balance() repairs the tree, and the if(...) condition is
+  ** never true.
+  **
+  ** Otherwise, if the entry deleted was on an internal node page, then
+  ** pCur is pointing to the leaf page from which a cell was removed to
+  ** replace the cell deleted from the internal node. This is slightly
+  ** tricky as the leaf node may be underfull, and the internal node may
+  ** be either under or overfull. In this case run the balancing algorithm
+  ** on the leaf node first. If the balance proceeds far enough up the
+  ** tree that we can be sure that any problem in the internal node has
+  ** been corrected, so be it. Otherwise, after balancing the leaf node,
+  ** walk the cursor up the tree to the internal node and balance it as 
+  ** well.  */
+  rc = balance(pCur);
+  if( rc==SQLITE_OK && pCur->iPage>iCellDepth ){
+    while( pCur->iPage>iCellDepth ){
+      releasePage(pCur->apPage[pCur->iPage--]);
+    }
+    rc = balance(pCur);
+  }
+
+  if( rc==SQLITE_OK ){
+    moveToRoot(pCur);
+  }
+  return rc;
+}
+
+/*
+** Create a new BTree table.  Write into *piTable the page
+** number for the root page of the new table.
+**
+** The type of type is determined by the flags parameter.  Only the
+** following values of flags are currently in use.  Other values for
+** flags might not work:
+**
+**     BTREE_INTKEY|BTREE_LEAFDATA     Used for SQL tables with rowid keys
+**     BTREE_ZERODATA                  Used for SQL indices
+*/
+static int btreeCreateTable(Btree *p, int *piTable, int createTabFlags){
+  BtShared *pBt = p->pBt;
+  MemPage *pRoot;
+  Pgno pgnoRoot;
+  int rc;
+  int ptfFlags;          /* Page-type flage for the root page of new table */
+
+  assert( sqlite3BtreeHoldsMutex(p) );
+  assert( pBt->inTransaction==TRANS_WRITE );
+  assert( !pBt->readOnly );
+
+#ifdef SQLITE_OMIT_AUTOVACUUM
+  rc = allocateBtreePage(pBt, &pRoot, &pgnoRoot, 1, 0);
+  if( rc ){
+    return rc;
+  }
+#else
+  if( pBt->autoVacuum ){
+    Pgno pgnoMove;      /* Move a page here to make room for the root-page */
+    MemPage *pPageMove; /* The page to move to. */
+
+    /* Creating a new table may probably require moving an existing database
+    ** to make room for the new tables root page. In case this page turns
+    ** out to be an overflow page, delete all overflow page-map caches
+    ** held by open cursors.
+    */
+    invalidateAllOverflowCache(pBt);
+
+    /* Read the value of meta[3] from the database to determine where the
+    ** root page of the new table should go. meta[3] is the largest root-page
+    ** created so far, so the new root-page is (meta[3]+1).
+    */
+    sqlite3BtreeGetMeta(p, BTREE_LARGEST_ROOT_PAGE, &pgnoRoot);
+    pgnoRoot++;
+
+    /* The new root-page may not be allocated on a pointer-map page, or the
+    ** PENDING_BYTE page.
+    */
+    while( pgnoRoot==PTRMAP_PAGENO(pBt, pgnoRoot) ||
+        pgnoRoot==PENDING_BYTE_PAGE(pBt) ){
+      pgnoRoot++;
+    }
+    assert( pgnoRoot>=3 );
+
+    /* Allocate a page. The page that currently resides at pgnoRoot will
+    ** be moved to the allocated page (unless the allocated page happens
+    ** to reside at pgnoRoot).
+    */
+    rc = allocateBtreePage(pBt, &pPageMove, &pgnoMove, pgnoRoot, 1);
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+
+    if( pgnoMove!=pgnoRoot ){
+      /* pgnoRoot is the page that will be used for the root-page of
+      ** the new table (assuming an error did not occur). But we were
+      ** allocated pgnoMove. If required (i.e. if it was not allocated
+      ** by extending the file), the current page at position pgnoMove
+      ** is already journaled.
+      */
+      u8 eType = 0;
+      Pgno iPtrPage = 0;
+
+      releasePage(pPageMove);
+
+      /* Move the page currently at pgnoRoot to pgnoMove. */
+      rc = btreeGetPage(pBt, pgnoRoot, &pRoot, 0);
+      if( rc!=SQLITE_OK ){
+        return rc;
+      }
+      rc = ptrmapGet(pBt, pgnoRoot, &eType, &iPtrPage);
+      if( eType==PTRMAP_ROOTPAGE || eType==PTRMAP_FREEPAGE ){
+        rc = SQLITE_CORRUPT_BKPT;
+      }
+      if( rc!=SQLITE_OK ){
+        releasePage(pRoot);
+        return rc;
+      }
+      assert( eType!=PTRMAP_ROOTPAGE );
+      assert( eType!=PTRMAP_FREEPAGE );
+      rc = relocatePage(pBt, pRoot, eType, iPtrPage, pgnoMove, 0);
+      releasePage(pRoot);
+
+      /* Obtain the page at pgnoRoot */
+      if( rc!=SQLITE_OK ){
+        return rc;
+      }
+      rc = btreeGetPage(pBt, pgnoRoot, &pRoot, 0);
+      if( rc!=SQLITE_OK ){
+        return rc;
+      }
+      rc = sqlite3PagerWrite(pRoot->pDbPage);
+      if( rc!=SQLITE_OK ){
+        releasePage(pRoot);
+        return rc;
+      }
+    }else{
+      pRoot = pPageMove;
+    } 
+
+    /* Update the pointer-map and meta-data with the new root-page number. */
+    ptrmapPut(pBt, pgnoRoot, PTRMAP_ROOTPAGE, 0, &rc);
+    if( rc ){
+      releasePage(pRoot);
+      return rc;
+    }
+
+    /* When the new root page was allocated, page 1 was made writable in
+    ** order either to increase the database filesize, or to decrement the
+    ** freelist count.  Hence, the sqlite3BtreeUpdateMeta() call cannot fail.
+    */
+    assert( sqlite3PagerIswriteable(pBt->pPage1->pDbPage) );
+    rc = sqlite3BtreeUpdateMeta(p, 4, pgnoRoot);
+    if( NEVER(rc) ){
+      releasePage(pRoot);
+      return rc;
+    }
+
+  }else{
+    rc = allocateBtreePage(pBt, &pRoot, &pgnoRoot, 1, 0);
+    if( rc ) return rc;
+  }
+#endif
+  assert( sqlite3PagerIswriteable(pRoot->pDbPage) );
+  if( createTabFlags & BTREE_INTKEY ){
+    ptfFlags = PTF_INTKEY | PTF_LEAFDATA | PTF_LEAF;
+  }else{
+    ptfFlags = PTF_ZERODATA | PTF_LEAF;
+  }
+  zeroPage(pRoot, ptfFlags);
+  sqlite3PagerUnref(pRoot->pDbPage);
+  assert( (pBt->openFlags & BTREE_SINGLE)==0 || pgnoRoot==2 );
+  *piTable = (int)pgnoRoot;
+  return SQLITE_OK;
+}
+SQLITE_PRIVATE int sqlite3BtreeCreateTable(Btree *p, int *piTable, int flags){
+  int rc;
+  sqlite3BtreeEnter(p);
+  rc = btreeCreateTable(p, piTable, flags);
+  sqlite3BtreeLeave(p);
+  return rc;
+}
+
+/*
+** Erase the given database page and all its children.  Return
+** the page to the freelist.
+*/
+static int clearDatabasePage(
+  BtShared *pBt,           /* The BTree that contains the table */
+  Pgno pgno,               /* Page number to clear */
+  int freePageFlag,        /* Deallocate page if true */
+  int *pnChange            /* Add number of Cells freed to this counter */
+){
+  MemPage *pPage;
+  int rc;
+  unsigned char *pCell;
+  int i;
+
+  assert( sqlite3_mutex_held(pBt->mutex) );
+  if( pgno>btreePagecount(pBt) ){
+    return SQLITE_CORRUPT_BKPT;
+  }
+
+  rc = getAndInitPage(pBt, pgno, &pPage);
+  if( rc ) return rc;
+  for(i=0; i<pPage->nCell; i++){
+    pCell = findCell(pPage, i);
+    if( !pPage->leaf ){
+      rc = clearDatabasePage(pBt, get4byte(pCell), 1, pnChange);
+      if( rc ) goto cleardatabasepage_out;
+    }
+    rc = clearCell(pPage, pCell);
+    if( rc ) goto cleardatabasepage_out;
+  }
+  if( !pPage->leaf ){
+    rc = clearDatabasePage(pBt, get4byte(&pPage->aData[8]), 1, pnChange);
+    if( rc ) goto cleardatabasepage_out;
+  }else if( pnChange ){
+    assert( pPage->intKey );
+    *pnChange += pPage->nCell;
+  }
+  if( freePageFlag ){
+    freePage(pPage, &rc);
+  }else if( (rc = sqlite3PagerWrite(pPage->pDbPage))==0 ){
+    zeroPage(pPage, pPage->aData[0] | PTF_LEAF);
+  }
+
+cleardatabasepage_out:
+  releasePage(pPage);
+  return rc;
+}
+
+/*
+** Delete all information from a single table in the database.  iTable is
+** the page number of the root of the table.  After this routine returns,
+** the root page is empty, but still exists.
+**
+** This routine will fail with SQLITE_LOCKED if there are any open
+** read cursors on the table.  Open write cursors are moved to the
+** root of the table.
+**
+** If pnChange is not NULL, then table iTable must be an intkey table. The
+** integer value pointed to by pnChange is incremented by the number of
+** entries in the table.
+*/
+SQLITE_PRIVATE int sqlite3BtreeClearTable(Btree *p, int iTable, int *pnChange){
+  int rc;
+  BtShared *pBt = p->pBt;
+  sqlite3BtreeEnter(p);
+  assert( p->inTrans==TRANS_WRITE );
+
+  /* Invalidate all incrblob cursors open on table iTable (assuming iTable
+  ** is the root of a table b-tree - if it is not, the following call is
+  ** a no-op).  */
+  invalidateIncrblobCursors(p, 0, 1);
+
+  rc = saveAllCursors(pBt, (Pgno)iTable, 0);
+  if( SQLITE_OK==rc ){
+    rc = clearDatabasePage(pBt, (Pgno)iTable, 0, pnChange);
+  }
+  sqlite3BtreeLeave(p);
+  return rc;
+}
+
+/*
+** Erase all information in a table and add the root of the table to
+** the freelist.  Except, the root of the principle table (the one on
+** page 1) is never added to the freelist.
+**
+** This routine will fail with SQLITE_LOCKED if there are any open
+** cursors on the table.
+**
+** If AUTOVACUUM is enabled and the page at iTable is not the last
+** root page in the database file, then the last root page 
+** in the database file is moved into the slot formerly occupied by
+** iTable and that last slot formerly occupied by the last root page
+** is added to the freelist instead of iTable.  In this say, all
+** root pages are kept at the beginning of the database file, which
+** is necessary for AUTOVACUUM to work right.  *piMoved is set to the 
+** page number that used to be the last root page in the file before
+** the move.  If no page gets moved, *piMoved is set to 0.
+** The last root page is recorded in meta[3] and the value of
+** meta[3] is updated by this procedure.
+*/
+static int btreeDropTable(Btree *p, Pgno iTable, int *piMoved){
+  int rc;
+  MemPage *pPage = 0;
+  BtShared *pBt = p->pBt;
+
+  assert( sqlite3BtreeHoldsMutex(p) );
+  assert( p->inTrans==TRANS_WRITE );
+
+  /* It is illegal to drop a table if any cursors are open on the
+  ** database. This is because in auto-vacuum mode the backend may
+  ** need to move another root-page to fill a gap left by the deleted
+  ** root page. If an open cursor was using this page a problem would 
+  ** occur.
+  **
+  ** This error is caught long before control reaches this point.
+  */
+  if( NEVER(pBt->pCursor) ){
+    sqlite3ConnectionBlocked(p->db, pBt->pCursor->pBtree->db);
+    return SQLITE_LOCKED_SHAREDCACHE;
+  }
+
+  rc = btreeGetPage(pBt, (Pgno)iTable, &pPage, 0);
+  if( rc ) return rc;
+  rc = sqlite3BtreeClearTable(p, iTable, 0);
+  if( rc ){
+    releasePage(pPage);
+    return rc;
+  }
+
+  *piMoved = 0;
+
+  if( iTable>1 ){
+#ifdef SQLITE_OMIT_AUTOVACUUM
+    freePage(pPage, &rc);
+    releasePage(pPage);
+#else
+    if( pBt->autoVacuum ){
+      Pgno maxRootPgno;
+      sqlite3BtreeGetMeta(p, BTREE_LARGEST_ROOT_PAGE, &maxRootPgno);
+
+      if( iTable==maxRootPgno ){
+        /* If the table being dropped is the table with the largest root-page
+        ** number in the database, put the root page on the free list. 
+        */
+        freePage(pPage, &rc);
+        releasePage(pPage);
+        if( rc!=SQLITE_OK ){
+          return rc;
+        }
+      }else{
+        /* The table being dropped does not have the largest root-page
+        ** number in the database. So move the page that does into the 
+        ** gap left by the deleted root-page.
+        */
+        MemPage *pMove;
+        releasePage(pPage);
+        rc = btreeGetPage(pBt, maxRootPgno, &pMove, 0);
+        if( rc!=SQLITE_OK ){
+          return rc;
+        }
+        rc = relocatePage(pBt, pMove, PTRMAP_ROOTPAGE, 0, iTable, 0);
+        releasePage(pMove);
+        if( rc!=SQLITE_OK ){
+          return rc;
+        }
+        pMove = 0;
+        rc = btreeGetPage(pBt, maxRootPgno, &pMove, 0);
+        freePage(pMove, &rc);
+        releasePage(pMove);
+        if( rc!=SQLITE_OK ){
+          return rc;
+        }
+        *piMoved = maxRootPgno;
+      }
+
+      /* Set the new 'max-root-page' value in the database header. This
+      ** is the old value less one, less one more if that happens to
+      ** be a root-page number, less one again if that is the
+      ** PENDING_BYTE_PAGE.
+      */
+      maxRootPgno--;
+      while( maxRootPgno==PENDING_BYTE_PAGE(pBt)
+             || PTRMAP_ISPAGE(pBt, maxRootPgno) ){
+        maxRootPgno--;
+      }
+      assert( maxRootPgno!=PENDING_BYTE_PAGE(pBt) );
+
+      rc = sqlite3BtreeUpdateMeta(p, 4, maxRootPgno);
+    }else{
+      freePage(pPage, &rc);
+      releasePage(pPage);
+    }
+#endif
+  }else{
+    /* If sqlite3BtreeDropTable was called on page 1.
+    ** This really never should happen except in a corrupt
+    ** database. 
+    */
+    zeroPage(pPage, PTF_INTKEY|PTF_LEAF );
+    releasePage(pPage);
+  }
+  return rc;  
+}
+SQLITE_PRIVATE int sqlite3BtreeDropTable(Btree *p, int iTable, int *piMoved){
+  int rc;
+  sqlite3BtreeEnter(p);
+  rc = btreeDropTable(p, iTable, piMoved);
+  sqlite3BtreeLeave(p);
+  return rc;
+}
+
+
+/*
+** This function may only be called if the b-tree connection already
+** has a read or write transaction open on the database.
+**
+** Read the meta-information out of a database file.  Meta[0]
+** is the number of free pages currently in the database.  Meta[1]
+** through meta[15] are available for use by higher layers.  Meta[0]
+** is read-only, the others are read/write.
+** 
+** The schema layer numbers meta values differently.  At the schema
+** layer (and the SetCookie and ReadCookie opcodes) the number of
+** free pages is not visible.  So Cookie[0] is the same as Meta[1].
+*/
+SQLITE_PRIVATE void sqlite3BtreeGetMeta(Btree *p, int idx, u32 *pMeta){
+  BtShared *pBt = p->pBt;
+
+  sqlite3BtreeEnter(p);
+  assert( p->inTrans>TRANS_NONE );
+  assert( SQLITE_OK==querySharedCacheTableLock(p, MASTER_ROOT, READ_LOCK) );
+  assert( pBt->pPage1 );
+  assert( idx>=0 && idx<=15 );
+
+  *pMeta = get4byte(&pBt->pPage1->aData[36 + idx*4]);
+
+  /* If auto-vacuum is disabled in this build and this is an auto-vacuum
+  ** database, mark the database as read-only.  */
+#ifdef SQLITE_OMIT_AUTOVACUUM
+  if( idx==BTREE_LARGEST_ROOT_PAGE && *pMeta>0 ) pBt->readOnly = 1;
+#endif
+
+  sqlite3BtreeLeave(p);
+}
+
+/*
+** Write meta-information back into the database.  Meta[0] is
+** read-only and may not be written.
+*/
+SQLITE_PRIVATE int sqlite3BtreeUpdateMeta(Btree *p, int idx, u32 iMeta){
+  BtShared *pBt = p->pBt;
+  unsigned char *pP1;
+  int rc;
+  assert( idx>=1 && idx<=15 );
+  sqlite3BtreeEnter(p);
+  assert( p->inTrans==TRANS_WRITE );
+  assert( pBt->pPage1!=0 );
+  pP1 = pBt->pPage1->aData;
+  rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
+  if( rc==SQLITE_OK ){
+    put4byte(&pP1[36 + idx*4], iMeta);
+#ifndef SQLITE_OMIT_AUTOVACUUM
+    if( idx==BTREE_INCR_VACUUM ){
+      assert( pBt->autoVacuum || iMeta==0 );
+      assert( iMeta==0 || iMeta==1 );
+      pBt->incrVacuum = (u8)iMeta;
+    }
+#endif
+  }
+  sqlite3BtreeLeave(p);
+  return rc;
+}
+
+#ifndef SQLITE_OMIT_BTREECOUNT
+/*
+** The first argument, pCur, is a cursor opened on some b-tree. Count the
+** number of entries in the b-tree and write the result to *pnEntry.
+**
+** SQLITE_OK is returned if the operation is successfully executed. 
+** Otherwise, if an error is encountered (i.e. an IO error or database
+** corruption) an SQLite error code is returned.
+*/
+SQLITE_PRIVATE int sqlite3BtreeCount(BtCursor *pCur, i64 *pnEntry){
+  i64 nEntry = 0;                      /* Value to return in *pnEntry */
+  int rc;                              /* Return code */
+  rc = moveToRoot(pCur);
+
+  /* Unless an error occurs, the following loop runs one iteration for each
+  ** page in the B-Tree structure (not including overflow pages). 
+  */
+  while( rc==SQLITE_OK ){
+    int iIdx;                          /* Index of child node in parent */
+    MemPage *pPage;                    /* Current page of the b-tree */
+
+    /* If this is a leaf page or the tree is not an int-key tree, then 
+    ** this page contains countable entries. Increment the entry counter
+    ** accordingly.
+    */
+    pPage = pCur->apPage[pCur->iPage];
+    if( pPage->leaf || !pPage->intKey ){
+      nEntry += pPage->nCell;
+    }
+
+    /* pPage is a leaf node. This loop navigates the cursor so that it 
+    ** points to the first interior cell that it points to the parent of
+    ** the next page in the tree that has not yet been visited. The
+    ** pCur->aiIdx[pCur->iPage] value is set to the index of the parent cell
+    ** of the page, or to the number of cells in the page if the next page
+    ** to visit is the right-child of its parent.
+    **
+    ** If all pages in the tree have been visited, return SQLITE_OK to the
+    ** caller.
+    */
+    if( pPage->leaf ){
+      do {
+        if( pCur->iPage==0 ){
+          /* All pages of the b-tree have been visited. Return successfully. */
+          *pnEntry = nEntry;
+          return SQLITE_OK;
+        }
+        moveToParent(pCur);
+      }while ( pCur->aiIdx[pCur->iPage]>=pCur->apPage[pCur->iPage]->nCell );
+
+      pCur->aiIdx[pCur->iPage]++;
+      pPage = pCur->apPage[pCur->iPage];
+    }
+
+    /* Descend to the child node of the cell that the cursor currently 
+    ** points at. This is the right-child if (iIdx==pPage->nCell).
+    */
+    iIdx = pCur->aiIdx[pCur->iPage];
+    if( iIdx==pPage->nCell ){
+      rc = moveToChild(pCur, get4byte(&pPage->aData[pPage->hdrOffset+8]));
+    }else{
+      rc = moveToChild(pCur, get4byte(findCell(pPage, iIdx)));
+    }
+  }
+
+  /* An error has occurred. Return an error code. */
+  return rc;
+}
+#endif
+
+/*
+** Return the pager associated with a BTree.  This routine is used for
+** testing and debugging only.
+*/
+SQLITE_PRIVATE Pager *sqlite3BtreePager(Btree *p){
+  return p->pBt->pPager;
+}
+
+#ifndef SQLITE_OMIT_INTEGRITY_CHECK
+/*
+** Append a message to the error message string.
+*/
+static void checkAppendMsg(
+  IntegrityCk *pCheck,
+  char *zMsg1,
+  const char *zFormat,
+  ...
+){
+  va_list ap;
+  if( !pCheck->mxErr ) return;
+  pCheck->mxErr--;
+  pCheck->nErr++;
+  va_start(ap, zFormat);
+  if( pCheck->errMsg.nChar ){
+    sqlite3StrAccumAppend(&pCheck->errMsg, "\n", 1);
+  }
+  if( zMsg1 ){
+    sqlite3StrAccumAppend(&pCheck->errMsg, zMsg1, -1);
+  }
+  sqlite3VXPrintf(&pCheck->errMsg, 1, zFormat, ap);
+  va_end(ap);
+  if( pCheck->errMsg.mallocFailed ){
+    pCheck->mallocFailed = 1;
+  }
+}
+#endif /* SQLITE_OMIT_INTEGRITY_CHECK */
+
+#ifndef SQLITE_OMIT_INTEGRITY_CHECK
+/*
+** Add 1 to the reference count for page iPage.  If this is the second
+** reference to the page, add an error message to pCheck->zErrMsg.
+** Return 1 if there are 2 ore more references to the page and 0 if
+** if this is the first reference to the page.
+**
+** Also check that the page number is in bounds.
+*/
+static int checkRef(IntegrityCk *pCheck, Pgno iPage, char *zContext){
+  if( iPage==0 ) return 1;
+  if( iPage>pCheck->nPage ){
+    checkAppendMsg(pCheck, zContext, "invalid page number %d", iPage);
+    return 1;
+  }
+  if( pCheck->anRef[iPage]==1 ){
+    checkAppendMsg(pCheck, zContext, "2nd reference to page %d", iPage);
+    return 1;
+  }
+  return  (pCheck->anRef[iPage]++)>1;
+}
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+/*
+** Check that the entry in the pointer-map for page iChild maps to 
+** page iParent, pointer type ptrType. If not, append an error message
+** to pCheck.
+*/
+static void checkPtrmap(
+  IntegrityCk *pCheck,   /* Integrity check context */
+  Pgno iChild,           /* Child page number */
+  u8 eType,              /* Expected pointer map type */
+  Pgno iParent,          /* Expected pointer map parent page number */
+  char *zContext         /* Context description (used for error msg) */
+){
+  int rc;
+  u8 ePtrmapType;
+  Pgno iPtrmapParent;
+
+  rc = ptrmapGet(pCheck->pBt, iChild, &ePtrmapType, &iPtrmapParent);
+  if( rc!=SQLITE_OK ){
+    if( rc==SQLITE_NOMEM || rc==SQLITE_IOERR_NOMEM ) pCheck->mallocFailed = 1;
+    checkAppendMsg(pCheck, zContext, "Failed to read ptrmap key=%d", iChild);
+    return;
+  }
+
+  if( ePtrmapType!=eType || iPtrmapParent!=iParent ){
+    checkAppendMsg(pCheck, zContext, 
+      "Bad ptr map entry key=%d expected=(%d,%d) got=(%d,%d)", 
+      iChild, eType, iParent, ePtrmapType, iPtrmapParent);
+  }
+}
+#endif
+
+/*
+** Check the integrity of the freelist or of an overflow page list.
+** Verify that the number of pages on the list is N.
+*/
+static void checkList(
+  IntegrityCk *pCheck,  /* Integrity checking context */
+  int isFreeList,       /* True for a freelist.  False for overflow page list */
+  int iPage,            /* Page number for first page in the list */
+  int N,                /* Expected number of pages in the list */
+  char *zContext        /* Context for error messages */
+){
+  int i;
+  int expected = N;
+  int iFirst = iPage;
+  while( N-- > 0 && pCheck->mxErr ){
+    DbPage *pOvflPage;
+    unsigned char *pOvflData;
+    if( iPage<1 ){
+      checkAppendMsg(pCheck, zContext,
+         "%d of %d pages missing from overflow list starting at %d",
+          N+1, expected, iFirst);
+      break;
+    }
+    if( checkRef(pCheck, iPage, zContext) ) break;
+    if( sqlite3PagerGet(pCheck->pPager, (Pgno)iPage, &pOvflPage) ){
+      checkAppendMsg(pCheck, zContext, "failed to get page %d", iPage);
+      break;
+    }
+    pOvflData = (unsigned char *)sqlite3PagerGetData(pOvflPage);
+    if( isFreeList ){
+      int n = get4byte(&pOvflData[4]);
+#ifndef SQLITE_OMIT_AUTOVACUUM
+      if( pCheck->pBt->autoVacuum ){
+        checkPtrmap(pCheck, iPage, PTRMAP_FREEPAGE, 0, zContext);
+      }
+#endif
+      if( n>(int)pCheck->pBt->usableSize/4-2 ){
+        checkAppendMsg(pCheck, zContext,
+           "freelist leaf count too big on page %d", iPage);
+        N--;
+      }else{
+        for(i=0; i<n; i++){
+          Pgno iFreePage = get4byte(&pOvflData[8+i*4]);
+#ifndef SQLITE_OMIT_AUTOVACUUM
+          if( pCheck->pBt->autoVacuum ){
+            checkPtrmap(pCheck, iFreePage, PTRMAP_FREEPAGE, 0, zContext);
+          }
+#endif
+          checkRef(pCheck, iFreePage, zContext);
+        }
+        N -= n;
+      }
+    }
+#ifndef SQLITE_OMIT_AUTOVACUUM
+    else{
+      /* If this database supports auto-vacuum and iPage is not the last
+      ** page in this overflow list, check that the pointer-map entry for
+      ** the following page matches iPage.
+      */
+      if( pCheck->pBt->autoVacuum && N>0 ){
+        i = get4byte(pOvflData);
+        checkPtrmap(pCheck, i, PTRMAP_OVERFLOW2, iPage, zContext);
+      }
+    }
+#endif
+    iPage = get4byte(pOvflData);
+    sqlite3PagerUnref(pOvflPage);
+  }
+}
+#endif /* SQLITE_OMIT_INTEGRITY_CHECK */
+
+#ifndef SQLITE_OMIT_INTEGRITY_CHECK
+/*
+** Do various sanity checks on a single page of a tree.  Return
+** the tree depth.  Root pages return 0.  Parents of root pages
+** return 1, and so forth.
+** 
+** These checks are done:
+**
+**      1.  Make sure that cells and freeblocks do not overlap
+**          but combine to completely cover the page.
+**  NO  2.  Make sure cell keys are in order.
+**  NO  3.  Make sure no key is less than or equal to zLowerBound.
+**  NO  4.  Make sure no key is greater than or equal to zUpperBound.
+**      5.  Check the integrity of overflow pages.
+**      6.  Recursively call checkTreePage on all children.
+**      7.  Verify that the depth of all children is the same.
+**      8.  Make sure this page is at least 33% full or else it is
+**          the root of the tree.
+*/
+static int checkTreePage(
+  IntegrityCk *pCheck,  /* Context for the sanity check */
+  int iPage,            /* Page number of the page to check */
+  char *zParentContext, /* Parent context */
+  i64 *pnParentMinKey, 
+  i64 *pnParentMaxKey
+){
+  MemPage *pPage;
+  int i, rc, depth, d2, pgno, cnt;
+  int hdr, cellStart;
+  int nCell;
+  u8 *data;
+  BtShared *pBt;
+  int usableSize;
+  char zContext[100];
+  char *hit = 0;
+  i64 nMinKey = 0;
+  i64 nMaxKey = 0;
+
+  sqlite3_snprintf(sizeof(zContext), zContext, "Page %d: ", iPage);
+
+  /* Check that the page exists
+  */
+  pBt = pCheck->pBt;
+  usableSize = pBt->usableSize;
+  if( iPage==0 ) return 0;
+  if( checkRef(pCheck, iPage, zParentContext) ) return 0;
+  if( (rc = btreeGetPage(pBt, (Pgno)iPage, &pPage, 0))!=0 ){
+    checkAppendMsg(pCheck, zContext,
+       "unable to get the page. error code=%d", rc);
+    return 0;
+  }
+
+  /* Clear MemPage.isInit to make sure the corruption detection code in
+  ** btreeInitPage() is executed.  */
+  pPage->isInit = 0;
+  if( (rc = btreeInitPage(pPage))!=0 ){
+    assert( rc==SQLITE_CORRUPT );  /* The only possible error from InitPage */
+    checkAppendMsg(pCheck, zContext, 
+                   "btreeInitPage() returns error code %d", rc);
+    releasePage(pPage);
+    return 0;
+  }
+
+  /* Check out all the cells.
+  */
+  depth = 0;
+  for(i=0; i<pPage->nCell && pCheck->mxErr; i++){
+    u8 *pCell;
+    u32 sz;
+    CellInfo info;
+
+    /* Check payload overflow pages
+    */
+    sqlite3_snprintf(sizeof(zContext), zContext,
+             "On tree page %d cell %d: ", iPage, i);
+    pCell = findCell(pPage,i);
+    btreeParseCellPtr(pPage, pCell, &info);
+    sz = info.nData;
+    if( !pPage->intKey ) sz += (int)info.nKey;
+    /* For intKey pages, check that the keys are in order.
+    */
+    else if( i==0 ) nMinKey = nMaxKey = info.nKey;
+    else{
+      if( info.nKey <= nMaxKey ){
+        checkAppendMsg(pCheck, zContext, 
+            "Rowid %lld out of order (previous was %lld)", info.nKey, nMaxKey);
+      }
+      nMaxKey = info.nKey;
+    }
+    assert( sz==info.nPayload );
+    if( (sz>info.nLocal) 
+     && (&pCell[info.iOverflow]<=&pPage->aData[pBt->usableSize])
+    ){
+      int nPage = (sz - info.nLocal + usableSize - 5)/(usableSize - 4);
+      Pgno pgnoOvfl = get4byte(&pCell[info.iOverflow]);
+#ifndef SQLITE_OMIT_AUTOVACUUM
+      if( pBt->autoVacuum ){
+        checkPtrmap(pCheck, pgnoOvfl, PTRMAP_OVERFLOW1, iPage, zContext);
+      }
+#endif
+      checkList(pCheck, 0, pgnoOvfl, nPage, zContext);
+    }
+
+    /* Check sanity of left child page.
+    */
+    if( !pPage->leaf ){
+      pgno = get4byte(pCell);
+#ifndef SQLITE_OMIT_AUTOVACUUM
+      if( pBt->autoVacuum ){
+        checkPtrmap(pCheck, pgno, PTRMAP_BTREE, iPage, zContext);
+      }
+#endif
+      d2 = checkTreePage(pCheck, pgno, zContext, &nMinKey, i==0 ? NULL : &nMaxKey);
+      if( i>0 && d2!=depth ){
+        checkAppendMsg(pCheck, zContext, "Child page depth differs");
+      }
+      depth = d2;
+    }
+  }
+
+  if( !pPage->leaf ){
+    pgno = get4byte(&pPage->aData[pPage->hdrOffset+8]);
+    sqlite3_snprintf(sizeof(zContext), zContext, 
+                     "On page %d at right child: ", iPage);
+#ifndef SQLITE_OMIT_AUTOVACUUM
+    if( pBt->autoVacuum ){
+      checkPtrmap(pCheck, pgno, PTRMAP_BTREE, iPage, zContext);
+    }
+#endif
+    checkTreePage(pCheck, pgno, zContext, NULL, !pPage->nCell ? NULL : &nMaxKey);
+  }
+ 
+  /* For intKey leaf pages, check that the min/max keys are in order
+  ** with any left/parent/right pages.
+  */
+  if( pPage->leaf && pPage->intKey ){
+    /* if we are a left child page */
+    if( pnParentMinKey ){
+      /* if we are the left most child page */
+      if( !pnParentMaxKey ){
+        if( nMaxKey > *pnParentMinKey ){
+          checkAppendMsg(pCheck, zContext, 
+              "Rowid %lld out of order (max larger than parent min of %lld)",
+              nMaxKey, *pnParentMinKey);
+        }
+      }else{
+        if( nMinKey <= *pnParentMinKey ){
+          checkAppendMsg(pCheck, zContext, 
+              "Rowid %lld out of order (min less than parent min of %lld)",
+              nMinKey, *pnParentMinKey);
+        }
+        if( nMaxKey > *pnParentMaxKey ){
+          checkAppendMsg(pCheck, zContext, 
+              "Rowid %lld out of order (max larger than parent max of %lld)",
+              nMaxKey, *pnParentMaxKey);
+        }
+        *pnParentMinKey = nMaxKey;
+      }
+    /* else if we're a right child page */
+    } else if( pnParentMaxKey ){
+      if( nMinKey <= *pnParentMaxKey ){
+        checkAppendMsg(pCheck, zContext, 
+            "Rowid %lld out of order (min less than parent max of %lld)",
+            nMinKey, *pnParentMaxKey);
+      }
+    }
+  }
+
+  /* Check for complete coverage of the page
+  */
+  data = pPage->aData;
+  hdr = pPage->hdrOffset;
+  hit = sqlite3PageMalloc( pBt->pageSize );
+  if( hit==0 ){
+    pCheck->mallocFailed = 1;
+  }else{
+    int contentOffset = get2byteNotZero(&data[hdr+5]);
+    assert( contentOffset<=usableSize );  /* Enforced by btreeInitPage() */
+    memset(hit+contentOffset, 0, usableSize-contentOffset);
+    memset(hit, 1, contentOffset);
+    nCell = get2byte(&data[hdr+3]);
+    cellStart = hdr + 12 - 4*pPage->leaf;
+    for(i=0; i<nCell; i++){
+      int pc = get2byte(&data[cellStart+i*2]);
+      u32 size = 65536;
+      int j;
+      if( pc<=usableSize-4 ){
+        size = cellSizePtr(pPage, &data[pc]);
+      }
+      if( (int)(pc+size-1)>=usableSize ){
+        checkAppendMsg(pCheck, 0, 
+            "Corruption detected in cell %d on page %d",i,iPage);
+      }else{
+        for(j=pc+size-1; j>=pc; j--) hit[j]++;
+      }
+    }
+    i = get2byte(&data[hdr+1]);
+    while( i>0 ){
+      int size, j;
+      assert( i<=usableSize-4 );     /* Enforced by btreeInitPage() */
+      size = get2byte(&data[i+2]);
+      assert( i+size<=usableSize );  /* Enforced by btreeInitPage() */
+      for(j=i+size-1; j>=i; j--) hit[j]++;
+      j = get2byte(&data[i]);
+      assert( j==0 || j>i+size );  /* Enforced by btreeInitPage() */
+      assert( j<=usableSize-4 );   /* Enforced by btreeInitPage() */
+      i = j;
+    }
+    for(i=cnt=0; i<usableSize; i++){
+      if( hit[i]==0 ){
+        cnt++;
+      }else if( hit[i]>1 ){
+        checkAppendMsg(pCheck, 0,
+          "Multiple uses for byte %d of page %d", i, iPage);
+        break;
+      }
+    }
+    if( cnt!=data[hdr+7] ){
+      checkAppendMsg(pCheck, 0, 
+          "Fragmentation of %d bytes reported as %d on page %d",
+          cnt, data[hdr+7], iPage);
+    }
+  }
+  sqlite3PageFree(hit);
+  releasePage(pPage);
+  return depth+1;
+}
+#endif /* SQLITE_OMIT_INTEGRITY_CHECK */
+
+#ifndef SQLITE_OMIT_INTEGRITY_CHECK
+/*
+** This routine does a complete check of the given BTree file.  aRoot[] is
+** an array of pages numbers were each page number is the root page of
+** a table.  nRoot is the number of entries in aRoot.
+**
+** A read-only or read-write transaction must be opened before calling
+** this function.
+**
+** Write the number of error seen in *pnErr.  Except for some memory
+** allocation errors,  an error message held in memory obtained from
+** malloc is returned if *pnErr is non-zero.  If *pnErr==0 then NULL is
+** returned.  If a memory allocation error occurs, NULL is returned.
+*/
+SQLITE_PRIVATE char *sqlite3BtreeIntegrityCheck(
+  Btree *p,     /* The btree to be checked */
+  int *aRoot,   /* An array of root pages numbers for individual trees */
+  int nRoot,    /* Number of entries in aRoot[] */
+  int mxErr,    /* Stop reporting errors after this many */
+  int *pnErr    /* Write number of errors seen to this variable */
+){
+  Pgno i;
+  int nRef;
+  IntegrityCk sCheck;
+  BtShared *pBt = p->pBt;
+  char zErr[100];
+
+  sqlite3BtreeEnter(p);
+  assert( p->inTrans>TRANS_NONE && pBt->inTransaction>TRANS_NONE );
+  nRef = sqlite3PagerRefcount(pBt->pPager);
+  sCheck.pBt = pBt;
+  sCheck.pPager = pBt->pPager;
+  sCheck.nPage = btreePagecount(sCheck.pBt);
+  sCheck.mxErr = mxErr;
+  sCheck.nErr = 0;
+  sCheck.mallocFailed = 0;
+  *pnErr = 0;
+  if( sCheck.nPage==0 ){
+    sqlite3BtreeLeave(p);
+    return 0;
+  }
+  sCheck.anRef = sqlite3Malloc( (sCheck.nPage+1)*sizeof(sCheck.anRef[0]) );
+  if( !sCheck.anRef ){
+    *pnErr = 1;
+    sqlite3BtreeLeave(p);
+    return 0;
+  }
+  for(i=0; i<=sCheck.nPage; i++){ sCheck.anRef[i] = 0; }
+  i = PENDING_BYTE_PAGE(pBt);
+  if( i<=sCheck.nPage ){
+    sCheck.anRef[i] = 1;
+  }
+  sqlite3StrAccumInit(&sCheck.errMsg, zErr, sizeof(zErr), 20000);
+  sCheck.errMsg.useMalloc = 2;
+
+  /* Check the integrity of the freelist
+  */
+  checkList(&sCheck, 1, get4byte(&pBt->pPage1->aData[32]),
+            get4byte(&pBt->pPage1->aData[36]), "Main freelist: ");
+
+  /* Check all the tables.
+  */
+  for(i=0; (int)i<nRoot && sCheck.mxErr; i++){
+    if( aRoot[i]==0 ) continue;
+#ifndef SQLITE_OMIT_AUTOVACUUM
+    if( pBt->autoVacuum && aRoot[i]>1 ){
+      checkPtrmap(&sCheck, aRoot[i], PTRMAP_ROOTPAGE, 0, 0);
+    }
+#endif
+    checkTreePage(&sCheck, aRoot[i], "List of tree roots: ", NULL, NULL);
+  }
+
+  /* Make sure every page in the file is referenced
+  */
+  for(i=1; i<=sCheck.nPage && sCheck.mxErr; i++){
+#ifdef SQLITE_OMIT_AUTOVACUUM
+    if( sCheck.anRef[i]==0 ){
+      checkAppendMsg(&sCheck, 0, "Page %d is never used", i);
+    }
+#else
+    /* If the database supports auto-vacuum, make sure no tables contain
+    ** references to pointer-map pages.
+    */
+    if( sCheck.anRef[i]==0 && 
+       (PTRMAP_PAGENO(pBt, i)!=i || !pBt->autoVacuum) ){
+      checkAppendMsg(&sCheck, 0, "Page %d is never used", i);
+    }
+    if( sCheck.anRef[i]!=0 && 
+       (PTRMAP_PAGENO(pBt, i)==i && pBt->autoVacuum) ){
+      checkAppendMsg(&sCheck, 0, "Pointer map page %d is referenced", i);
+    }
+#endif
+  }
+
+  /* Make sure this analysis did not leave any unref() pages.
+  ** This is an internal consistency check; an integrity check
+  ** of the integrity check.
+  */
+  if( NEVER(nRef != sqlite3PagerRefcount(pBt->pPager)) ){
+    checkAppendMsg(&sCheck, 0, 
+      "Outstanding page count goes from %d to %d during this analysis",
+      nRef, sqlite3PagerRefcount(pBt->pPager)
+    );
+  }
+
+  /* Clean  up and report errors.
+  */
+  sqlite3BtreeLeave(p);
+  sqlite3_free(sCheck.anRef);
+  if( sCheck.mallocFailed ){
+    sqlite3StrAccumReset(&sCheck.errMsg);
+    *pnErr = sCheck.nErr+1;
+    return 0;
+  }
+  *pnErr = sCheck.nErr;
+  if( sCheck.nErr==0 ) sqlite3StrAccumReset(&sCheck.errMsg);
+  return sqlite3StrAccumFinish(&sCheck.errMsg);
+}
+#endif /* SQLITE_OMIT_INTEGRITY_CHECK */
+
+/*
+** Return the full pathname of the underlying database file.
+**
+** The pager filename is invariant as long as the pager is
+** open so it is safe to access without the BtShared mutex.
+*/
+SQLITE_PRIVATE const char *sqlite3BtreeGetFilename(Btree *p){
+  assert( p->pBt->pPager!=0 );
+  return sqlite3PagerFilename(p->pBt->pPager);
+}
+
+/*
+** Return the pathname of the journal file for this database. The return
+** value of this routine is the same regardless of whether the journal file
+** has been created or not.
+**
+** The pager journal filename is invariant as long as the pager is
+** open so it is safe to access without the BtShared mutex.
+*/
+SQLITE_PRIVATE const char *sqlite3BtreeGetJournalname(Btree *p){
+  assert( p->pBt->pPager!=0 );
+  return sqlite3PagerJournalname(p->pBt->pPager);
+}
+
+/*
+** Return non-zero if a transaction is active.
+*/
+SQLITE_PRIVATE int sqlite3BtreeIsInTrans(Btree *p){
+  assert( p==0 || sqlite3_mutex_held(p->db->mutex) );
+  return (p && (p->inTrans==TRANS_WRITE));
+}
+
+#ifndef SQLITE_OMIT_WAL
+/*
+** Run a checkpoint on the Btree passed as the first argument.
+**
+** Return SQLITE_LOCKED if this or any other connection has an open 
+** transaction on the shared-cache the argument Btree is connected to.
+**
+** Parameter eMode is one of SQLITE_CHECKPOINT_PASSIVE, FULL or RESTART.
+*/
+SQLITE_PRIVATE int sqlite3BtreeCheckpoint(Btree *p, int eMode, int *pnLog, int *pnCkpt){
+  int rc = SQLITE_OK;
+  if( p ){
+    BtShared *pBt = p->pBt;
+    sqlite3BtreeEnter(p);
+    if( pBt->inTransaction!=TRANS_NONE ){
+      rc = SQLITE_LOCKED;
+    }else{
+      rc = sqlite3PagerCheckpoint(pBt->pPager, eMode, pnLog, pnCkpt);
+    }
+    sqlite3BtreeLeave(p);
+  }
+  return rc;
+}
+#endif
+
+/*
+** Return non-zero if a read (or write) transaction is active.
+*/
+SQLITE_PRIVATE int sqlite3BtreeIsInReadTrans(Btree *p){
+  assert( p );
+  assert( sqlite3_mutex_held(p->db->mutex) );
+  return p->inTrans!=TRANS_NONE;
+}
+
+SQLITE_PRIVATE int sqlite3BtreeIsInBackup(Btree *p){
+  assert( p );
+  assert( sqlite3_mutex_held(p->db->mutex) );
+  return p->nBackup!=0;
+}
+
+/*
+** This function returns a pointer to a blob of memory associated with
+** a single shared-btree. The memory is used by client code for its own
+** purposes (for example, to store a high-level schema associated with 
+** the shared-btree). The btree layer manages reference counting issues.
+**
+** The first time this is called on a shared-btree, nBytes bytes of memory
+** are allocated, zeroed, and returned to the caller. For each subsequent 
+** call the nBytes parameter is ignored and a pointer to the same blob
+** of memory returned. 
+**
+** If the nBytes parameter is 0 and the blob of memory has not yet been
+** allocated, a null pointer is returned. If the blob has already been
+** allocated, it is returned as normal.
+**
+** Just before the shared-btree is closed, the function passed as the 
+** xFree argument when the memory allocation was made is invoked on the 
+** blob of allocated memory. The xFree function should not call sqlite3_free()
+** on the memory, the btree layer does that.
+*/
+SQLITE_PRIVATE void *sqlite3BtreeSchema(Btree *p, int nBytes, void(*xFree)(void *)){
+  BtShared *pBt = p->pBt;
+  sqlite3BtreeEnter(p);
+  if( !pBt->pSchema && nBytes ){
+    pBt->pSchema = sqlite3DbMallocZero(0, nBytes);
+    pBt->xFreeSchema = xFree;
+  }
+  sqlite3BtreeLeave(p);
+  return pBt->pSchema;
+}
+
+/*
+** Return SQLITE_LOCKED_SHAREDCACHE if another user of the same shared 
+** btree as the argument handle holds an exclusive lock on the 
+** sqlite_master table. Otherwise SQLITE_OK.
+*/
+SQLITE_PRIVATE int sqlite3BtreeSchemaLocked(Btree *p){
+  int rc;
+  assert( sqlite3_mutex_held(p->db->mutex) );
+  sqlite3BtreeEnter(p);
+  rc = querySharedCacheTableLock(p, MASTER_ROOT, READ_LOCK);
+  assert( rc==SQLITE_OK || rc==SQLITE_LOCKED_SHAREDCACHE );
+  sqlite3BtreeLeave(p);
+  return rc;
+}
+
+
+#ifndef SQLITE_OMIT_SHARED_CACHE
+/*
+** Obtain a lock on the table whose root page is iTab.  The
+** lock is a write lock if isWritelock is true or a read lock
+** if it is false.
+*/
+SQLITE_PRIVATE int sqlite3BtreeLockTable(Btree *p, int iTab, u8 isWriteLock){
+  int rc = SQLITE_OK;
+  assert( p->inTrans!=TRANS_NONE );
+  if( p->sharable ){
+    u8 lockType = READ_LOCK + isWriteLock;
+    assert( READ_LOCK+1==WRITE_LOCK );
+    assert( isWriteLock==0 || isWriteLock==1 );
+
+    sqlite3BtreeEnter(p);
+    rc = querySharedCacheTableLock(p, iTab, lockType);
+    if( rc==SQLITE_OK ){
+      rc = setSharedCacheTableLock(p, iTab, lockType);
+    }
+    sqlite3BtreeLeave(p);
+  }
+  return rc;
+}
+#endif
+
+#ifndef SQLITE_OMIT_INCRBLOB
+/*
+** Argument pCsr must be a cursor opened for writing on an 
+** INTKEY table currently pointing at a valid table entry. 
+** This function modifies the data stored as part of that entry.
+**
+** Only the data content may only be modified, it is not possible to 
+** change the length of the data stored. If this function is called with
+** parameters that attempt to write past the end of the existing data,
+** no modifications are made and SQLITE_CORRUPT is returned.
+*/
+SQLITE_PRIVATE int sqlite3BtreePutData(BtCursor *pCsr, u32 offset, u32 amt, void *z){
+  int rc;
+  assert( cursorHoldsMutex(pCsr) );
+  assert( sqlite3_mutex_held(pCsr->pBtree->db->mutex) );
+  assert( pCsr->isIncrblobHandle );
+
+  rc = restoreCursorPosition(pCsr);
+  if( rc!=SQLITE_OK ){
+    return rc;
+  }
+  assert( pCsr->eState!=CURSOR_REQUIRESEEK );
+  if( pCsr->eState!=CURSOR_VALID ){
+    return SQLITE_ABORT;
+  }
+
+  /* Check some assumptions: 
+  **   (a) the cursor is open for writing,
+  **   (b) there is a read/write transaction open,
+  **   (c) the connection holds a write-lock on the table (if required),
+  **   (d) there are no conflicting read-locks, and
+  **   (e) the cursor points at a valid row of an intKey table.
+  */
+  if( !pCsr->wrFlag ){
+    return SQLITE_READONLY;
+  }
+  assert( !pCsr->pBt->readOnly && pCsr->pBt->inTransaction==TRANS_WRITE );
+  assert( hasSharedCacheTableLock(pCsr->pBtree, pCsr->pgnoRoot, 0, 2) );
+  assert( !hasReadConflicts(pCsr->pBtree, pCsr->pgnoRoot) );
+  assert( pCsr->apPage[pCsr->iPage]->intKey );
+
+  return accessPayload(pCsr, offset, amt, (unsigned char *)z, 1);
+}
+
+/* 
+** Set a flag on this cursor to cache the locations of pages from the 
+** overflow list for the current row. This is used by cursors opened
+** for incremental blob IO only.
+**
+** This function sets a flag only. The actual page location cache
+** (stored in BtCursor.aOverflow[]) is allocated and used by function
+** accessPayload() (the worker function for sqlite3BtreeData() and
+** sqlite3BtreePutData()).
+*/
+SQLITE_PRIVATE void sqlite3BtreeCacheOverflow(BtCursor *pCur){
+  assert( cursorHoldsMutex(pCur) );
+  assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
+  invalidateOverflowCache(pCur);
+  pCur->isIncrblobHandle = 1;
+}
+#endif
+
+/*
+** Set both the "read version" (single byte at byte offset 18) and 
+** "write version" (single byte at byte offset 19) fields in the database
+** header to iVersion.
+*/
+SQLITE_PRIVATE int sqlite3BtreeSetVersion(Btree *pBtree, int iVersion){
+  BtShared *pBt = pBtree->pBt;
+  int rc;                         /* Return code */
+ 
+  assert( pBtree->inTrans==TRANS_NONE );
+  assert( iVersion==1 || iVersion==2 );
+
+  /* If setting the version fields to 1, do not automatically open the
+  ** WAL connection, even if the version fields are currently set to 2.
+  */
+  pBt->doNotUseWAL = (u8)(iVersion==1);
+
+  rc = sqlite3BtreeBeginTrans(pBtree, 0);
+  if( rc==SQLITE_OK ){
+    u8 *aData = pBt->pPage1->aData;
+    if( aData[18]!=(u8)iVersion || aData[19]!=(u8)iVersion ){
+      rc = sqlite3BtreeBeginTrans(pBtree, 2);
+      if( rc==SQLITE_OK ){
+        rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
+        if( rc==SQLITE_OK ){
+          aData[18] = (u8)iVersion;
+          aData[19] = (u8)iVersion;
+        }
+      }
+    }
+  }
+
+  pBt->doNotUseWAL = 0;
+  return rc;
+}
+
+/************** End of btree.c ***********************************************/
+/************** Begin file backup.c ******************************************/
+/*
+** 2009 January 28
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains the implementation of the sqlite3_backup_XXX() 
+** API functions and the related features.
+*/
+
+/* Macro to find the minimum of two numeric values.
+*/
+#ifndef MIN
+# define MIN(x,y) ((x)<(y)?(x):(y))
+#endif
+
+/*
+** Structure allocated for each backup operation.
+*/
+struct sqlite3_backup {
+  sqlite3* pDestDb;        /* Destination database handle */
+  Btree *pDest;            /* Destination b-tree file */
+  u32 iDestSchema;         /* Original schema cookie in destination */
+  int bDestLocked;         /* True once a write-transaction is open on pDest */
+
+  Pgno iNext;              /* Page number of the next source page to copy */
+  sqlite3* pSrcDb;         /* Source database handle */
+  Btree *pSrc;             /* Source b-tree file */
+
+  int rc;                  /* Backup process error code */
+
+  /* These two variables are set by every call to backup_step(). They are
+  ** read by calls to backup_remaining() and backup_pagecount().
+  */
+  Pgno nRemaining;         /* Number of pages left to copy */
+  Pgno nPagecount;         /* Total number of pages to copy */
+
+  int isAttached;          /* True once backup has been registered with pager */
+  sqlite3_backup *pNext;   /* Next backup associated with source pager */
+};
+
+/*
+** THREAD SAFETY NOTES:
+**
+**   Once it has been created using backup_init(), a single sqlite3_backup
+**   structure may be accessed via two groups of thread-safe entry points:
+**
+**     * Via the sqlite3_backup_XXX() API function backup_step() and 
+**       backup_finish(). Both these functions obtain the source database
+**       handle mutex and the mutex associated with the source BtShared 
+**       structure, in that order.
+**
+**     * Via the BackupUpdate() and BackupRestart() functions, which are
+**       invoked by the pager layer to report various state changes in
+**       the page cache associated with the source database. The mutex
+**       associated with the source database BtShared structure will always 
+**       be held when either of these functions are invoked.
+**
+**   The other sqlite3_backup_XXX() API functions, backup_remaining() and
+**   backup_pagecount() are not thread-safe functions. If they are called
+**   while some other thread is calling backup_step() or backup_finish(),
+**   the values returned may be invalid. There is no way for a call to
+**   BackupUpdate() or BackupRestart() to interfere with backup_remaining()
+**   or backup_pagecount().
+**
+**   Depending on the SQLite configuration, the database handles and/or
+**   the Btree objects may have their own mutexes that require locking.
+**   Non-sharable Btrees (in-memory databases for example), do not have
+**   associated mutexes.
+*/
+
+/*
+** Return a pointer corresponding to database zDb (i.e. "main", "temp")
+** in connection handle pDb. If such a database cannot be found, return
+** a NULL pointer and write an error message to pErrorDb.
+**
+** If the "temp" database is requested, it may need to be opened by this 
+** function. If an error occurs while doing so, return 0 and write an 
+** error message to pErrorDb.
+*/
+static Btree *findBtree(sqlite3 *pErrorDb, sqlite3 *pDb, const char *zDb){
+  int i = sqlite3FindDbName(pDb, zDb);
+
+  if( i==1 ){
+    Parse *pParse;
+    int rc = 0;
+    pParse = sqlite3StackAllocZero(pErrorDb, sizeof(*pParse));
+    if( pParse==0 ){
+      sqlite3Error(pErrorDb, SQLITE_NOMEM, "out of memory");
+      rc = SQLITE_NOMEM;
+    }else{
+      pParse->db = pDb;
+      if( sqlite3OpenTempDatabase(pParse) ){
+        sqlite3Error(pErrorDb, pParse->rc, "%s", pParse->zErrMsg);
+        rc = SQLITE_ERROR;
+      }
+      sqlite3DbFree(pErrorDb, pParse->zErrMsg);
+      sqlite3StackFree(pErrorDb, pParse);
+    }
+    if( rc ){
+      return 0;
+    }
+  }
+
+  if( i<0 ){
+    sqlite3Error(pErrorDb, SQLITE_ERROR, "unknown database %s", zDb);
+    return 0;
+  }
+
+  return pDb->aDb[i].pBt;
+}
+
+/*
+** Attempt to set the page size of the destination to match the page size
+** of the source.
+*/
+static int setDestPgsz(sqlite3_backup *p){
+  int rc;
+  rc = sqlite3BtreeSetPageSize(p->pDest,sqlite3BtreeGetPageSize(p->pSrc),-1,0);
+  return rc;
+}
+
+/*
+** Create an sqlite3_backup process to copy the contents of zSrcDb from
+** connection handle pSrcDb to zDestDb in pDestDb. If successful, return
+** a pointer to the new sqlite3_backup object.
+**
+** If an error occurs, NULL is returned and an error code and error message
+** stored in database handle pDestDb.
+*/
+SQLITE_API sqlite3_backup *sqlite3_backup_init(
+  sqlite3* pDestDb,                     /* Database to write to */
+  const char *zDestDb,                  /* Name of database within pDestDb */
+  sqlite3* pSrcDb,                      /* Database connection to read from */
+  const char *zSrcDb                    /* Name of database within pSrcDb */
+){
+  sqlite3_backup *p;                    /* Value to return */
+
+  /* Lock the source database handle. The destination database
+  ** handle is not locked in this routine, but it is locked in
+  ** sqlite3_backup_step(). The user is required to ensure that no
+  ** other thread accesses the destination handle for the duration
+  ** of the backup operation.  Any attempt to use the destination
+  ** database connection while a backup is in progress may cause
+  ** a malfunction or a deadlock.
+  */
+  sqlite3_mutex_enter(pSrcDb->mutex);
+  sqlite3_mutex_enter(pDestDb->mutex);
+
+  if( pSrcDb==pDestDb ){
+    sqlite3Error(
+        pDestDb, SQLITE_ERROR, "source and destination must be distinct"
+    );
+    p = 0;
+  }else {
+    /* Allocate space for a new sqlite3_backup object...
+    ** EVIDENCE-OF: R-64852-21591 The sqlite3_backup object is created by a
+    ** call to sqlite3_backup_init() and is destroyed by a call to
+    ** sqlite3_backup_finish(). */
+    p = (sqlite3_backup *)sqlite3_malloc(sizeof(sqlite3_backup));
+    if( !p ){
+      sqlite3Error(pDestDb, SQLITE_NOMEM, 0);
+    }
+  }
+
+  /* If the allocation succeeded, populate the new object. */
+  if( p ){
+    memset(p, 0, sizeof(sqlite3_backup));
+    p->pSrc = findBtree(pDestDb, pSrcDb, zSrcDb);
+    p->pDest = findBtree(pDestDb, pDestDb, zDestDb);
+    p->pDestDb = pDestDb;
+    p->pSrcDb = pSrcDb;
+    p->iNext = 1;
+    p->isAttached = 0;
+
+    if( 0==p->pSrc || 0==p->pDest || setDestPgsz(p)==SQLITE_NOMEM ){
+      /* One (or both) of the named databases did not exist or an OOM
+      ** error was hit.  The error has already been written into the
+      ** pDestDb handle.  All that is left to do here is free the
+      ** sqlite3_backup structure.
+      */
+      sqlite3_free(p);
+      p = 0;
+    }
+  }
+  if( p ){
+    p->pSrc->nBackup++;
+  }
+
+  sqlite3_mutex_leave(pDestDb->mutex);
+  sqlite3_mutex_leave(pSrcDb->mutex);
+  return p;
+}
+
+/*
+** Argument rc is an SQLite error code. Return true if this error is 
+** considered fatal if encountered during a backup operation. All errors
+** are considered fatal except for SQLITE_BUSY and SQLITE_LOCKED.
+*/
+static int isFatalError(int rc){
+  return (rc!=SQLITE_OK && rc!=SQLITE_BUSY && ALWAYS(rc!=SQLITE_LOCKED));
+}
+
+/*
+** Parameter zSrcData points to a buffer containing the data for 
+** page iSrcPg from the source database. Copy this data into the 
+** destination database.
+*/
+static int backupOnePage(sqlite3_backup *p, Pgno iSrcPg, const u8 *zSrcData){
+  Pager * const pDestPager = sqlite3BtreePager(p->pDest);
+  const int nSrcPgsz = sqlite3BtreeGetPageSize(p->pSrc);
+  int nDestPgsz = sqlite3BtreeGetPageSize(p->pDest);
+  const int nCopy = MIN(nSrcPgsz, nDestPgsz);
+  const i64 iEnd = (i64)iSrcPg*(i64)nSrcPgsz;
+#ifdef SQLITE_HAS_CODEC
+  int nSrcReserve = sqlite3BtreeGetReserve(p->pSrc);
+  int nDestReserve = sqlite3BtreeGetReserve(p->pDest);
+#endif
+
+  int rc = SQLITE_OK;
+  i64 iOff;
+
+  assert( p->bDestLocked );
+  assert( !isFatalError(p->rc) );
+  assert( iSrcPg!=PENDING_BYTE_PAGE(p->pSrc->pBt) );
+  assert( zSrcData );
+
+  /* Catch the case where the destination is an in-memory database and the
+  ** page sizes of the source and destination differ. 
+  */
+  if( nSrcPgsz!=nDestPgsz && sqlite3PagerIsMemdb(pDestPager) ){
+    rc = SQLITE_READONLY;
+  }
+
+#ifdef SQLITE_HAS_CODEC
+  /* Backup is not possible if the page size of the destination is changing
+  ** and a codec is in use.
+  */
+  if( nSrcPgsz!=nDestPgsz && sqlite3PagerGetCodec(pDestPager)!=0 ){
+    rc = SQLITE_READONLY;
+  }
+
+  /* Backup is not possible if the number of bytes of reserve space differ
+  ** between source and destination.  If there is a difference, try to
+  ** fix the destination to agree with the source.  If that is not possible,
+  ** then the backup cannot proceed.
+  */
+  if( nSrcReserve!=nDestReserve ){
+    u32 newPgsz = nSrcPgsz;
+    rc = sqlite3PagerSetPagesize(pDestPager, &newPgsz, nSrcReserve);
+    if( rc==SQLITE_OK && newPgsz!=nSrcPgsz ) rc = SQLITE_READONLY;
+  }
+#endif
+
+  /* This loop runs once for each destination page spanned by the source 
+  ** page. For each iteration, variable iOff is set to the byte offset
+  ** of the destination page.
+  */
+  for(iOff=iEnd-(i64)nSrcPgsz; rc==SQLITE_OK && iOff<iEnd; iOff+=nDestPgsz){
+    DbPage *pDestPg = 0;
+    Pgno iDest = (Pgno)(iOff/nDestPgsz)+1;
+    if( iDest==PENDING_BYTE_PAGE(p->pDest->pBt) ) continue;
+    if( SQLITE_OK==(rc = sqlite3PagerGet(pDestPager, iDest, &pDestPg))
+     && SQLITE_OK==(rc = sqlite3PagerWrite(pDestPg))
+    ){
+      const u8 *zIn = &zSrcData[iOff%nSrcPgsz];
+      u8 *zDestData = sqlite3PagerGetData(pDestPg);
+      u8 *zOut = &zDestData[iOff%nDestPgsz];
+
+      /* Copy the data from the source page into the destination page.
+      ** Then clear the Btree layer MemPage.isInit flag. Both this module
+      ** and the pager code use this trick (clearing the first byte
+      ** of the page 'extra' space to invalidate the Btree layers
+      ** cached parse of the page). MemPage.isInit is marked 
+      ** "MUST BE FIRST" for this purpose.
+      */
+      memcpy(zOut, zIn, nCopy);
+      ((u8 *)sqlite3PagerGetExtra(pDestPg))[0] = 0;
+    }
+    sqlite3PagerUnref(pDestPg);
+  }
+
+  return rc;
+}
+
+/*
+** If pFile is currently larger than iSize bytes, then truncate it to
+** exactly iSize bytes. If pFile is not larger than iSize bytes, then
+** this function is a no-op.
+**
+** Return SQLITE_OK if everything is successful, or an SQLite error 
+** code if an error occurs.
+*/
+static int backupTruncateFile(sqlite3_file *pFile, i64 iSize){
+  i64 iCurrent;
+  int rc = sqlite3OsFileSize(pFile, &iCurrent);
+  if( rc==SQLITE_OK && iCurrent>iSize ){
+    rc = sqlite3OsTruncate(pFile, iSize);
+  }
+  return rc;
+}
+
+/*
+** Register this backup object with the associated source pager for
+** callbacks when pages are changed or the cache invalidated.
+*/
+static void attachBackupObject(sqlite3_backup *p){
+  sqlite3_backup **pp;
+  assert( sqlite3BtreeHoldsMutex(p->pSrc) );
+  pp = sqlite3PagerBackupPtr(sqlite3BtreePager(p->pSrc));
+  p->pNext = *pp;
+  *pp = p;
+  p->isAttached = 1;
+}
+
+/*
+** Copy nPage pages from the source b-tree to the destination.
+*/
+SQLITE_API int sqlite3_backup_step(sqlite3_backup *p, int nPage){
+  int rc;
+  int destMode;       /* Destination journal mode */
+  int pgszSrc = 0;    /* Source page size */
+  int pgszDest = 0;   /* Destination page size */
+
+  sqlite3_mutex_enter(p->pSrcDb->mutex);
+  sqlite3BtreeEnter(p->pSrc);
+  if( p->pDestDb ){
+    sqlite3_mutex_enter(p->pDestDb->mutex);
+  }
+
+  rc = p->rc;
+  if( !isFatalError(rc) ){
+    Pager * const pSrcPager = sqlite3BtreePager(p->pSrc);     /* Source pager */
+    Pager * const pDestPager = sqlite3BtreePager(p->pDest);   /* Dest pager */
+    int ii;                            /* Iterator variable */
+    int nSrcPage = -1;                 /* Size of source db in pages */
+    int bCloseTrans = 0;               /* True if src db requires unlocking */
+
+    /* If the source pager is currently in a write-transaction, return
+    ** SQLITE_BUSY immediately.
+    */
+    if( p->pDestDb && p->pSrc->pBt->inTransaction==TRANS_WRITE ){
+      rc = SQLITE_BUSY;
+    }else{
+      rc = SQLITE_OK;
+    }
+
+    /* Lock the destination database, if it is not locked already. */
+    if( SQLITE_OK==rc && p->bDestLocked==0
+     && SQLITE_OK==(rc = sqlite3BtreeBeginTrans(p->pDest, 2)) 
+    ){
+      p->bDestLocked = 1;
+      sqlite3BtreeGetMeta(p->pDest, BTREE_SCHEMA_VERSION, &p->iDestSchema);
+    }
+
+    /* If there is no open read-transaction on the source database, open
+    ** one now. If a transaction is opened here, then it will be closed
+    ** before this function exits.
+    */
+    if( rc==SQLITE_OK && 0==sqlite3BtreeIsInReadTrans(p->pSrc) ){
+      rc = sqlite3BtreeBeginTrans(p->pSrc, 0);
+      bCloseTrans = 1;
+    }
+
+    /* Do not allow backup if the destination database is in WAL mode
+    ** and the page sizes are different between source and destination */
+    pgszSrc = sqlite3BtreeGetPageSize(p->pSrc);
+    pgszDest = sqlite3BtreeGetPageSize(p->pDest);
+    destMode = sqlite3PagerGetJournalMode(sqlite3BtreePager(p->pDest));
+    if( SQLITE_OK==rc && destMode==PAGER_JOURNALMODE_WAL && pgszSrc!=pgszDest ){
+      rc = SQLITE_READONLY;
+    }
+  
+    /* Now that there is a read-lock on the source database, query the
+    ** source pager for the number of pages in the database.
+    */
+    nSrcPage = (int)sqlite3BtreeLastPage(p->pSrc);
+    assert( nSrcPage>=0 );
+    for(ii=0; (nPage<0 || ii<nPage) && p->iNext<=(Pgno)nSrcPage && !rc; ii++){
+      const Pgno iSrcPg = p->iNext;                 /* Source page number */
+      if( iSrcPg!=PENDING_BYTE_PAGE(p->pSrc->pBt) ){
+        DbPage *pSrcPg;                             /* Source page object */
+        rc = sqlite3PagerGet(pSrcPager, iSrcPg, &pSrcPg);
+        if( rc==SQLITE_OK ){
+          rc = backupOnePage(p, iSrcPg, sqlite3PagerGetData(pSrcPg));
+          sqlite3PagerUnref(pSrcPg);
+        }
+      }
+      p->iNext++;
+    }
+    if( rc==SQLITE_OK ){
+      p->nPagecount = nSrcPage;
+      p->nRemaining = nSrcPage+1-p->iNext;
+      if( p->iNext>(Pgno)nSrcPage ){
+        rc = SQLITE_DONE;
+      }else if( !p->isAttached ){
+        attachBackupObject(p);
+      }
+    }
+  
+    /* Update the schema version field in the destination database. This
+    ** is to make sure that the schema-version really does change in
+    ** the case where the source and destination databases have the
+    ** same schema version.
+    */
+    if( rc==SQLITE_DONE 
+     && (rc = sqlite3BtreeUpdateMeta(p->pDest,1,p->iDestSchema+1))==SQLITE_OK
+    ){
+      int nDestTruncate;
+  
+      if( p->pDestDb ){
+        sqlite3ResetInternalSchema(p->pDestDb, -1);
+      }
+
+      /* Set nDestTruncate to the final number of pages in the destination
+      ** database. The complication here is that the destination page
+      ** size may be different to the source page size. 
+      **
+      ** If the source page size is smaller than the destination page size, 
+      ** round up. In this case the call to sqlite3OsTruncate() below will
+      ** fix the size of the file. However it is important to call
+      ** sqlite3PagerTruncateImage() here so that any pages in the 
+      ** destination file that lie beyond the nDestTruncate page mark are
+      ** journalled by PagerCommitPhaseOne() before they are destroyed
+      ** by the file truncation.
+      */
+      assert( pgszSrc==sqlite3BtreeGetPageSize(p->pSrc) );
+      assert( pgszDest==sqlite3BtreeGetPageSize(p->pDest) );
+      if( pgszSrc<pgszDest ){
+        int ratio = pgszDest/pgszSrc;
+        nDestTruncate = (nSrcPage+ratio-1)/ratio;
+        if( nDestTruncate==(int)PENDING_BYTE_PAGE(p->pDest->pBt) ){
+          nDestTruncate--;
+        }
+      }else{
+        nDestTruncate = nSrcPage * (pgszSrc/pgszDest);
+      }
+      sqlite3PagerTruncateImage(pDestPager, nDestTruncate);
+
+      if( pgszSrc<pgszDest ){
+        /* If the source page-size is smaller than the destination page-size,
+        ** two extra things may need to happen:
+        **
+        **   * The destination may need to be truncated, and
+        **
+        **   * Data stored on the pages immediately following the 
+        **     pending-byte page in the source database may need to be
+        **     copied into the destination database.
+        */
+        const i64 iSize = (i64)pgszSrc * (i64)nSrcPage;
+        sqlite3_file * const pFile = sqlite3PagerFile(pDestPager);
+        i64 iOff;
+        i64 iEnd;
+
+        assert( pFile );
+        assert( (i64)nDestTruncate*(i64)pgszDest >= iSize || (
+              nDestTruncate==(int)(PENDING_BYTE_PAGE(p->pDest->pBt)-1)
+           && iSize>=PENDING_BYTE && iSize<=PENDING_BYTE+pgszDest
+        ));
+
+        /* This call ensures that all data required to recreate the original
+        ** database has been stored in the journal for pDestPager and the
+        ** journal synced to disk. So at this point we may safely modify
+        ** the database file in any way, knowing that if a power failure
+        ** occurs, the original database will be reconstructed from the 
+        ** journal file.  */
+        rc = sqlite3PagerCommitPhaseOne(pDestPager, 0, 1);
+
+        /* Write the extra pages and truncate the database file as required. */
+        iEnd = MIN(PENDING_BYTE + pgszDest, iSize);
+        for(
+          iOff=PENDING_BYTE+pgszSrc; 
+          rc==SQLITE_OK && iOff<iEnd; 
+          iOff+=pgszSrc
+        ){
+          PgHdr *pSrcPg = 0;
+          const Pgno iSrcPg = (Pgno)((iOff/pgszSrc)+1);
+          rc = sqlite3PagerGet(pSrcPager, iSrcPg, &pSrcPg);
+          if( rc==SQLITE_OK ){
+            u8 *zData = sqlite3PagerGetData(pSrcPg);
+            rc = sqlite3OsWrite(pFile, zData, pgszSrc, iOff);
+          }
+          sqlite3PagerUnref(pSrcPg);
+        }
+        if( rc==SQLITE_OK ){
+          rc = backupTruncateFile(pFile, iSize);
+        }
+
+        /* Sync the database file to disk. */
+        if( rc==SQLITE_OK ){
+          rc = sqlite3PagerSync(pDestPager);
+        }
+      }else{
+        rc = sqlite3PagerCommitPhaseOne(pDestPager, 0, 0);
+      }
+  
+      /* Finish committing the transaction to the destination database. */
+      if( SQLITE_OK==rc
+       && SQLITE_OK==(rc = sqlite3BtreeCommitPhaseTwo(p->pDest, 0))
+      ){
+        rc = SQLITE_DONE;
+      }
+    }
+  
+    /* If bCloseTrans is true, then this function opened a read transaction
+    ** on the source database. Close the read transaction here. There is
+    ** no need to check the return values of the btree methods here, as
+    ** "committing" a read-only transaction cannot fail.
+    */
+    if( bCloseTrans ){
+      TESTONLY( int rc2 );
+      TESTONLY( rc2  = ) sqlite3BtreeCommitPhaseOne(p->pSrc, 0);
+      TESTONLY( rc2 |= ) sqlite3BtreeCommitPhaseTwo(p->pSrc, 0);
+      assert( rc2==SQLITE_OK );
+    }
+  
+    if( rc==SQLITE_IOERR_NOMEM ){
+      rc = SQLITE_NOMEM;
+    }
+    p->rc = rc;
+  }
+  if( p->pDestDb ){
+    sqlite3_mutex_leave(p->pDestDb->mutex);
+  }
+  sqlite3BtreeLeave(p->pSrc);
+  sqlite3_mutex_leave(p->pSrcDb->mutex);
+  return rc;
+}
+
+/*
+** Release all resources associated with an sqlite3_backup* handle.
+*/
+SQLITE_API int sqlite3_backup_finish(sqlite3_backup *p){
+  sqlite3_backup **pp;                 /* Ptr to head of pagers backup list */
+  sqlite3_mutex *mutex;                /* Mutex to protect source database */
+  int rc;                              /* Value to return */
+
+  /* Enter the mutexes */
+  if( p==0 ) return SQLITE_OK;
+  sqlite3_mutex_enter(p->pSrcDb->mutex);
+  sqlite3BtreeEnter(p->pSrc);
+  mutex = p->pSrcDb->mutex;
+  if( p->pDestDb ){
+    sqlite3_mutex_enter(p->pDestDb->mutex);
+  }
+
+  /* Detach this backup from the source pager. */
+  if( p->pDestDb ){
+    p->pSrc->nBackup--;
+  }
+  if( p->isAttached ){
+    pp = sqlite3PagerBackupPtr(sqlite3BtreePager(p->pSrc));
+    while( *pp!=p ){
+      pp = &(*pp)->pNext;
+    }
+    *pp = p->pNext;
+  }
+
+  /* If a transaction is still open on the Btree, roll it back. */
+  sqlite3BtreeRollback(p->pDest);
+
+  /* Set the error code of the destination database handle. */
+  rc = (p->rc==SQLITE_DONE) ? SQLITE_OK : p->rc;
+  sqlite3Error(p->pDestDb, rc, 0);
+
+  /* Exit the mutexes and free the backup context structure. */
+  if( p->pDestDb ){
+    sqlite3_mutex_leave(p->pDestDb->mutex);
+  }
+  sqlite3BtreeLeave(p->pSrc);
+  if( p->pDestDb ){
+    /* EVIDENCE-OF: R-64852-21591 The sqlite3_backup object is created by a
+    ** call to sqlite3_backup_init() and is destroyed by a call to
+    ** sqlite3_backup_finish(). */
+    sqlite3_free(p);
+  }
+  sqlite3_mutex_leave(mutex);
+  return rc;
+}
+
+/*
+** Return the number of pages still to be backed up as of the most recent
+** call to sqlite3_backup_step().
+*/
+SQLITE_API int sqlite3_backup_remaining(sqlite3_backup *p){
+  return p->nRemaining;
+}
+
+/*
+** Return the total number of pages in the source database as of the most 
+** recent call to sqlite3_backup_step().
+*/
+SQLITE_API int sqlite3_backup_pagecount(sqlite3_backup *p){
+  return p->nPagecount;
+}
+
+/*
+** This function is called after the contents of page iPage of the
+** source database have been modified. If page iPage has already been 
+** copied into the destination database, then the data written to the
+** destination is now invalidated. The destination copy of iPage needs
+** to be updated with the new data before the backup operation is
+** complete.
+**
+** It is assumed that the mutex associated with the BtShared object
+** corresponding to the source database is held when this function is
+** called.
+*/
+SQLITE_PRIVATE void sqlite3BackupUpdate(sqlite3_backup *pBackup, Pgno iPage, const u8 *aData){
+  sqlite3_backup *p;                   /* Iterator variable */
+  for(p=pBackup; p; p=p->pNext){
+    assert( sqlite3_mutex_held(p->pSrc->pBt->mutex) );
+    if( !isFatalError(p->rc) && iPage<p->iNext ){
+      /* The backup process p has already copied page iPage. But now it
+      ** has been modified by a transaction on the source pager. Copy
+      ** the new data into the backup.
+      */
+      int rc;
+      assert( p->pDestDb );
+      sqlite3_mutex_enter(p->pDestDb->mutex);
+      rc = backupOnePage(p, iPage, aData);
+      sqlite3_mutex_leave(p->pDestDb->mutex);
+      assert( rc!=SQLITE_BUSY && rc!=SQLITE_LOCKED );
+      if( rc!=SQLITE_OK ){
+        p->rc = rc;
+      }
+    }
+  }
+}
+
+/*
+** Restart the backup process. This is called when the pager layer
+** detects that the database has been modified by an external database
+** connection. In this case there is no way of knowing which of the
+** pages that have been copied into the destination database are still 
+** valid and which are not, so the entire process needs to be restarted.
+**
+** It is assumed that the mutex associated with the BtShared object
+** corresponding to the source database is held when this function is
+** called.
+*/
+SQLITE_PRIVATE void sqlite3BackupRestart(sqlite3_backup *pBackup){
+  sqlite3_backup *p;                   /* Iterator variable */
+  for(p=pBackup; p; p=p->pNext){
+    assert( sqlite3_mutex_held(p->pSrc->pBt->mutex) );
+    p->iNext = 1;
+  }
+}
+
+#ifndef SQLITE_OMIT_VACUUM
+/*
+** Copy the complete content of pBtFrom into pBtTo.  A transaction
+** must be active for both files.
+**
+** The size of file pTo may be reduced by this operation. If anything 
+** goes wrong, the transaction on pTo is rolled back. If successful, the 
+** transaction is committed before returning.
+*/
+SQLITE_PRIVATE int sqlite3BtreeCopyFile(Btree *pTo, Btree *pFrom){
+  int rc;
+  sqlite3_backup b;
+  sqlite3BtreeEnter(pTo);
+  sqlite3BtreeEnter(pFrom);
+
+  /* Set up an sqlite3_backup object. sqlite3_backup.pDestDb must be set
+  ** to 0. This is used by the implementations of sqlite3_backup_step()
+  ** and sqlite3_backup_finish() to detect that they are being called
+  ** from this function, not directly by the user.
+  */
+  memset(&b, 0, sizeof(b));
+  b.pSrcDb = pFrom->db;
+  b.pSrc = pFrom;
+  b.pDest = pTo;
+  b.iNext = 1;
+
+  /* 0x7FFFFFFF is the hard limit for the number of pages in a database
+  ** file. By passing this as the number of pages to copy to
+  ** sqlite3_backup_step(), we can guarantee that the copy finishes 
+  ** within a single call (unless an error occurs). The assert() statement
+  ** checks this assumption - (p->rc) should be set to either SQLITE_DONE 
+  ** or an error code.
+  */
+  sqlite3_backup_step(&b, 0x7FFFFFFF);
+  assert( b.rc!=SQLITE_OK );
+  rc = sqlite3_backup_finish(&b);
+  if( rc==SQLITE_OK ){
+    pTo->pBt->pageSizeFixed = 0;
+  }
+
+  sqlite3BtreeLeave(pFrom);
+  sqlite3BtreeLeave(pTo);
+  return rc;
+}
+#endif /* SQLITE_OMIT_VACUUM */
+
+/************** End of backup.c **********************************************/
+/************** Begin file vdbemem.c *****************************************/
+/*
+** 2004 May 26
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains code use to manipulate "Mem" structure.  A "Mem"
+** stores a single value in the VDBE.  Mem is an opaque structure visible
+** only within the VDBE.  Interface routines refer to a Mem using the
+** name sqlite_value
+*/
+
+/*
+** Call sqlite3VdbeMemExpandBlob() on the supplied value (type Mem*)
+** P if required.
+*/
+#define expandBlob(P) (((P)->flags&MEM_Zero)?sqlite3VdbeMemExpandBlob(P):0)
+
+/*
+** If pMem is an object with a valid string representation, this routine
+** ensures the internal encoding for the string representation is
+** 'desiredEnc', one of SQLITE_UTF8, SQLITE_UTF16LE or SQLITE_UTF16BE.
+**
+** If pMem is not a string object, or the encoding of the string
+** representation is already stored using the requested encoding, then this
+** routine is a no-op.
+**
+** SQLITE_OK is returned if the conversion is successful (or not required).
+** SQLITE_NOMEM may be returned if a malloc() fails during conversion
+** between formats.
+*/
+SQLITE_PRIVATE int sqlite3VdbeChangeEncoding(Mem *pMem, int desiredEnc){
+  int rc;
+  assert( (pMem->flags&MEM_RowSet)==0 );
+  assert( desiredEnc==SQLITE_UTF8 || desiredEnc==SQLITE_UTF16LE
+           || desiredEnc==SQLITE_UTF16BE );
+  if( !(pMem->flags&MEM_Str) || pMem->enc==desiredEnc ){
+    return SQLITE_OK;
+  }
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+#ifdef SQLITE_OMIT_UTF16
+  return SQLITE_ERROR;
+#else
+
+  /* MemTranslate() may return SQLITE_OK or SQLITE_NOMEM. If NOMEM is returned,
+  ** then the encoding of the value may not have changed.
+  */
+  rc = sqlite3VdbeMemTranslate(pMem, (u8)desiredEnc);
+  assert(rc==SQLITE_OK    || rc==SQLITE_NOMEM);
+  assert(rc==SQLITE_OK    || pMem->enc!=desiredEnc);
+  assert(rc==SQLITE_NOMEM || pMem->enc==desiredEnc);
+  return rc;
+#endif
+}
+
+/*
+** Make sure pMem->z points to a writable allocation of at least 
+** n bytes.
+**
+** If the memory cell currently contains string or blob data
+** and the third argument passed to this function is true, the 
+** current content of the cell is preserved. Otherwise, it may
+** be discarded.  
+**
+** This function sets the MEM_Dyn flag and clears any xDel callback.
+** It also clears MEM_Ephem and MEM_Static. If the preserve flag is 
+** not set, Mem.n is zeroed.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMemGrow(Mem *pMem, int n, int preserve){
+  assert( 1 >=
+    ((pMem->zMalloc && pMem->zMalloc==pMem->z) ? 1 : 0) +
+    (((pMem->flags&MEM_Dyn)&&pMem->xDel) ? 1 : 0) + 
+    ((pMem->flags&MEM_Ephem) ? 1 : 0) + 
+    ((pMem->flags&MEM_Static) ? 1 : 0)
+  );
+  assert( (pMem->flags&MEM_RowSet)==0 );
+
+  if( n<32 ) n = 32;
+  if( sqlite3DbMallocSize(pMem->db, pMem->zMalloc)<n ){
+    if( preserve && pMem->z==pMem->zMalloc ){
+      pMem->z = pMem->zMalloc = sqlite3DbReallocOrFree(pMem->db, pMem->z, n);
+      preserve = 0;
+    }else{
+      sqlite3DbFree(pMem->db, pMem->zMalloc);
+      pMem->zMalloc = sqlite3DbMallocRaw(pMem->db, n);
+    }
+  }
+
+  if( pMem->z && preserve && pMem->zMalloc && pMem->z!=pMem->zMalloc ){
+    memcpy(pMem->zMalloc, pMem->z, pMem->n);
+  }
+  if( pMem->flags&MEM_Dyn && pMem->xDel ){
+    pMem->xDel((void *)(pMem->z));
+  }
+
+  pMem->z = pMem->zMalloc;
+  if( pMem->z==0 ){
+    pMem->flags = MEM_Null;
+  }else{
+    pMem->flags &= ~(MEM_Ephem|MEM_Static);
+  }
+  pMem->xDel = 0;
+  return (pMem->z ? SQLITE_OK : SQLITE_NOMEM);
+}
+
+/*
+** Make the given Mem object MEM_Dyn.  In other words, make it so
+** that any TEXT or BLOB content is stored in memory obtained from
+** malloc().  In this way, we know that the memory is safe to be
+** overwritten or altered.
+**
+** Return SQLITE_OK on success or SQLITE_NOMEM if malloc fails.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMemMakeWriteable(Mem *pMem){
+  int f;
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  assert( (pMem->flags&MEM_RowSet)==0 );
+  expandBlob(pMem);
+  f = pMem->flags;
+  if( (f&(MEM_Str|MEM_Blob)) && pMem->z!=pMem->zMalloc ){
+    if( sqlite3VdbeMemGrow(pMem, pMem->n + 2, 1) ){
+      return SQLITE_NOMEM;
+    }
+    pMem->z[pMem->n] = 0;
+    pMem->z[pMem->n+1] = 0;
+    pMem->flags |= MEM_Term;
+#ifdef SQLITE_DEBUG
+    pMem->pScopyFrom = 0;
+#endif
+  }
+
+  return SQLITE_OK;
+}
+
+/*
+** If the given Mem* has a zero-filled tail, turn it into an ordinary
+** blob stored in dynamically allocated space.
+*/
+#ifndef SQLITE_OMIT_INCRBLOB
+SQLITE_PRIVATE int sqlite3VdbeMemExpandBlob(Mem *pMem){
+  if( pMem->flags & MEM_Zero ){
+    int nByte;
+    assert( pMem->flags&MEM_Blob );
+    assert( (pMem->flags&MEM_RowSet)==0 );
+    assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+
+    /* Set nByte to the number of bytes required to store the expanded blob. */
+    nByte = pMem->n + pMem->u.nZero;
+    if( nByte<=0 ){
+      nByte = 1;
+    }
+    if( sqlite3VdbeMemGrow(pMem, nByte, 1) ){
+      return SQLITE_NOMEM;
+    }
+
+    memset(&pMem->z[pMem->n], 0, pMem->u.nZero);
+    pMem->n += pMem->u.nZero;
+    pMem->flags &= ~(MEM_Zero|MEM_Term);
+  }
+  return SQLITE_OK;
+}
+#endif
+
+
+/*
+** Make sure the given Mem is \u0000 terminated.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMemNulTerminate(Mem *pMem){
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  if( (pMem->flags & MEM_Term)!=0 || (pMem->flags & MEM_Str)==0 ){
+    return SQLITE_OK;   /* Nothing to do */
+  }
+  if( sqlite3VdbeMemGrow(pMem, pMem->n+2, 1) ){
+    return SQLITE_NOMEM;
+  }
+  pMem->z[pMem->n] = 0;
+  pMem->z[pMem->n+1] = 0;
+  pMem->flags |= MEM_Term;
+  return SQLITE_OK;
+}
+
+/*
+** Add MEM_Str to the set of representations for the given Mem.  Numbers
+** are converted using sqlite3_snprintf().  Converting a BLOB to a string
+** is a no-op.
+**
+** Existing representations MEM_Int and MEM_Real are *not* invalidated.
+**
+** A MEM_Null value will never be passed to this function. This function is
+** used for converting values to text for returning to the user (i.e. via
+** sqlite3_value_text()), or for ensuring that values to be used as btree
+** keys are strings. In the former case a NULL pointer is returned the
+** user and the later is an internal programming error.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMemStringify(Mem *pMem, int enc){
+  int rc = SQLITE_OK;
+  int fg = pMem->flags;
+  const int nByte = 32;
+
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  assert( !(fg&MEM_Zero) );
+  assert( !(fg&(MEM_Str|MEM_Blob)) );
+  assert( fg&(MEM_Int|MEM_Real) );
+  assert( (pMem->flags&MEM_RowSet)==0 );
+  assert( EIGHT_BYTE_ALIGNMENT(pMem) );
+
+
+  if( sqlite3VdbeMemGrow(pMem, nByte, 0) ){
+    return SQLITE_NOMEM;
+  }
+
+  /* For a Real or Integer, use sqlite3_mprintf() to produce the UTF-8
+  ** string representation of the value. Then, if the required encoding
+  ** is UTF-16le or UTF-16be do a translation.
+  ** 
+  ** FIX ME: It would be better if sqlite3_snprintf() could do UTF-16.
+  */
+  if( fg & MEM_Int ){
+    sqlite3_snprintf(nByte, pMem->z, "%lld", pMem->u.i);
+  }else{
+    assert( fg & MEM_Real );
+    sqlite3_snprintf(nByte, pMem->z, "%!.15g", pMem->r);
+  }
+  pMem->n = sqlite3Strlen30(pMem->z);
+  pMem->enc = SQLITE_UTF8;
+  pMem->flags |= MEM_Str|MEM_Term;
+  sqlite3VdbeChangeEncoding(pMem, enc);
+  return rc;
+}
+
+/*
+** Memory cell pMem contains the context of an aggregate function.
+** This routine calls the finalize method for that function.  The
+** result of the aggregate is stored back into pMem.
+**
+** Return SQLITE_ERROR if the finalizer reports an error.  SQLITE_OK
+** otherwise.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMemFinalize(Mem *pMem, FuncDef *pFunc){
+  int rc = SQLITE_OK;
+  if( ALWAYS(pFunc && pFunc->xFinalize) ){
+    sqlite3_context ctx;
+    assert( (pMem->flags & MEM_Null)!=0 || pFunc==pMem->u.pDef );
+    assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+    memset(&ctx, 0, sizeof(ctx));
+    ctx.s.flags = MEM_Null;
+    ctx.s.db = pMem->db;
+    ctx.pMem = pMem;
+    ctx.pFunc = pFunc;
+    pFunc->xFinalize(&ctx); /* IMP: R-24505-23230 */
+    assert( 0==(pMem->flags&MEM_Dyn) && !pMem->xDel );
+    sqlite3DbFree(pMem->db, pMem->zMalloc);
+    memcpy(pMem, &ctx.s, sizeof(ctx.s));
+    rc = ctx.isError;
+  }
+  return rc;
+}
+
+/*
+** If the memory cell contains a string value that must be freed by
+** invoking an external callback, free it now. Calling this function
+** does not free any Mem.zMalloc buffer.
+*/
+SQLITE_PRIVATE void sqlite3VdbeMemReleaseExternal(Mem *p){
+  assert( p->db==0 || sqlite3_mutex_held(p->db->mutex) );
+  testcase( p->flags & MEM_Agg );
+  testcase( p->flags & MEM_Dyn );
+  testcase( p->flags & MEM_RowSet );
+  testcase( p->flags & MEM_Frame );
+  if( p->flags&(MEM_Agg|MEM_Dyn|MEM_RowSet|MEM_Frame) ){
+    if( p->flags&MEM_Agg ){
+      sqlite3VdbeMemFinalize(p, p->u.pDef);
+      assert( (p->flags & MEM_Agg)==0 );
+      sqlite3VdbeMemRelease(p);
+    }else if( p->flags&MEM_Dyn && p->xDel ){
+      assert( (p->flags&MEM_RowSet)==0 );
+      p->xDel((void *)p->z);
+      p->xDel = 0;
+    }else if( p->flags&MEM_RowSet ){
+      sqlite3RowSetClear(p->u.pRowSet);
+    }else if( p->flags&MEM_Frame ){
+      sqlite3VdbeMemSetNull(p);
+    }
+  }
+}
+
+/*
+** Release any memory held by the Mem. This may leave the Mem in an
+** inconsistent state, for example with (Mem.z==0) and
+** (Mem.type==SQLITE_TEXT).
+*/
+SQLITE_PRIVATE void sqlite3VdbeMemRelease(Mem *p){
+  sqlite3VdbeMemReleaseExternal(p);
+  sqlite3DbFree(p->db, p->zMalloc);
+  p->z = 0;
+  p->zMalloc = 0;
+  p->xDel = 0;
+}
+
+/*
+** Convert a 64-bit IEEE double into a 64-bit signed integer.
+** If the double is too large, return 0x8000000000000000.
+**
+** Most systems appear to do this simply by assigning
+** variables and without the extra range tests.  But
+** there are reports that windows throws an expection
+** if the floating point value is out of range. (See ticket #2880.)
+** Because we do not completely understand the problem, we will
+** take the conservative approach and always do range tests
+** before attempting the conversion.
+*/
+static i64 doubleToInt64(double r){
+#ifdef SQLITE_OMIT_FLOATING_POINT
+  /* When floating-point is omitted, double and int64 are the same thing */
+  return r;
+#else
+  /*
+  ** Many compilers we encounter do not define constants for the
+  ** minimum and maximum 64-bit integers, or they define them
+  ** inconsistently.  And many do not understand the "LL" notation.
+  ** So we define our own static constants here using nothing
+  ** larger than a 32-bit integer constant.
+  */
+  static const i64 maxInt = LARGEST_INT64;
+  static const i64 minInt = SMALLEST_INT64;
+
+  if( r<(double)minInt ){
+    return minInt;
+  }else if( r>(double)maxInt ){
+    /* minInt is correct here - not maxInt.  It turns out that assigning
+    ** a very large positive number to an integer results in a very large
+    ** negative integer.  This makes no sense, but it is what x86 hardware
+    ** does so for compatibility we will do the same in software. */
+    return minInt;
+  }else{
+    return (i64)r;
+  }
+#endif
+}
+
+/*
+** Return some kind of integer value which is the best we can do
+** at representing the value that *pMem describes as an integer.
+** If pMem is an integer, then the value is exact.  If pMem is
+** a floating-point then the value returned is the integer part.
+** If pMem is a string or blob, then we make an attempt to convert
+** it into a integer and return that.  If pMem represents an
+** an SQL-NULL value, return 0.
+**
+** If pMem represents a string value, its encoding might be changed.
+*/
+SQLITE_PRIVATE i64 sqlite3VdbeIntValue(Mem *pMem){
+  int flags;
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  assert( EIGHT_BYTE_ALIGNMENT(pMem) );
+  flags = pMem->flags;
+  if( flags & MEM_Int ){
+    return pMem->u.i;
+  }else if( flags & MEM_Real ){
+    return doubleToInt64(pMem->r);
+  }else if( flags & (MEM_Str|MEM_Blob) ){
+    i64 value = 0;
+    assert( pMem->z || pMem->n==0 );
+    testcase( pMem->z==0 );
+    sqlite3Atoi64(pMem->z, &value, pMem->n, pMem->enc);
+    return value;
+  }else{
+    return 0;
+  }
+}
+
+/*
+** Return the best representation of pMem that we can get into a
+** double.  If pMem is already a double or an integer, return its
+** value.  If it is a string or blob, try to convert it to a double.
+** If it is a NULL, return 0.0.
+*/
+SQLITE_PRIVATE double sqlite3VdbeRealValue(Mem *pMem){
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  assert( EIGHT_BYTE_ALIGNMENT(pMem) );
+  if( pMem->flags & MEM_Real ){
+    return pMem->r;
+  }else if( pMem->flags & MEM_Int ){
+    return (double)pMem->u.i;
+  }else if( pMem->flags & (MEM_Str|MEM_Blob) ){
+    /* (double)0 In case of SQLITE_OMIT_FLOATING_POINT... */
+    double val = (double)0;
+    sqlite3AtoF(pMem->z, &val, pMem->n, pMem->enc);
+    return val;
+  }else{
+    /* (double)0 In case of SQLITE_OMIT_FLOATING_POINT... */
+    return (double)0;
+  }
+}
+
+/*
+** The MEM structure is already a MEM_Real.  Try to also make it a
+** MEM_Int if we can.
+*/
+SQLITE_PRIVATE void sqlite3VdbeIntegerAffinity(Mem *pMem){
+  assert( pMem->flags & MEM_Real );
+  assert( (pMem->flags & MEM_RowSet)==0 );
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  assert( EIGHT_BYTE_ALIGNMENT(pMem) );
+
+  pMem->u.i = doubleToInt64(pMem->r);
+
+  /* Only mark the value as an integer if
+  **
+  **    (1) the round-trip conversion real->int->real is a no-op, and
+  **    (2) The integer is neither the largest nor the smallest
+  **        possible integer (ticket #3922)
+  **
+  ** The second and third terms in the following conditional enforces
+  ** the second condition under the assumption that addition overflow causes
+  ** values to wrap around.  On x86 hardware, the third term is always
+  ** true and could be omitted.  But we leave it in because other
+  ** architectures might behave differently.
+  */
+  if( pMem->r==(double)pMem->u.i && pMem->u.i>SMALLEST_INT64
+      && ALWAYS(pMem->u.i<LARGEST_INT64) ){
+    pMem->flags |= MEM_Int;
+  }
+}
+
+/*
+** Convert pMem to type integer.  Invalidate any prior representations.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMemIntegerify(Mem *pMem){
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  assert( (pMem->flags & MEM_RowSet)==0 );
+  assert( EIGHT_BYTE_ALIGNMENT(pMem) );
+
+  pMem->u.i = sqlite3VdbeIntValue(pMem);
+  MemSetTypeFlag(pMem, MEM_Int);
+  return SQLITE_OK;
+}
+
+/*
+** Convert pMem so that it is of type MEM_Real.
+** Invalidate any prior representations.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMemRealify(Mem *pMem){
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  assert( EIGHT_BYTE_ALIGNMENT(pMem) );
+
+  pMem->r = sqlite3VdbeRealValue(pMem);
+  MemSetTypeFlag(pMem, MEM_Real);
+  return SQLITE_OK;
+}
+
+/*
+** Convert pMem so that it has types MEM_Real or MEM_Int or both.
+** Invalidate any prior representations.
+**
+** Every effort is made to force the conversion, even if the input
+** is a string that does not look completely like a number.  Convert
+** as much of the string as we can and ignore the rest.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMemNumerify(Mem *pMem){
+  if( (pMem->flags & (MEM_Int|MEM_Real|MEM_Null))==0 ){
+    assert( (pMem->flags & (MEM_Blob|MEM_Str))!=0 );
+    assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+    if( 0==sqlite3Atoi64(pMem->z, &pMem->u.i, pMem->n, pMem->enc) ){
+      MemSetTypeFlag(pMem, MEM_Int);
+    }else{
+      pMem->r = sqlite3VdbeRealValue(pMem);
+      MemSetTypeFlag(pMem, MEM_Real);
+      sqlite3VdbeIntegerAffinity(pMem);
+    }
+  }
+  assert( (pMem->flags & (MEM_Int|MEM_Real|MEM_Null))!=0 );
+  pMem->flags &= ~(MEM_Str|MEM_Blob);
+  return SQLITE_OK;
+}
+
+/*
+** Delete any previous value and set the value stored in *pMem to NULL.
+*/
+SQLITE_PRIVATE void sqlite3VdbeMemSetNull(Mem *pMem){
+  if( pMem->flags & MEM_Frame ){
+    VdbeFrame *pFrame = pMem->u.pFrame;
+    pFrame->pParent = pFrame->v->pDelFrame;
+    pFrame->v->pDelFrame = pFrame;
+  }
+  if( pMem->flags & MEM_RowSet ){
+    sqlite3RowSetClear(pMem->u.pRowSet);
+  }
+  MemSetTypeFlag(pMem, MEM_Null);
+  pMem->type = SQLITE_NULL;
+}
+
+/*
+** Delete any previous value and set the value to be a BLOB of length
+** n containing all zeros.
+*/
+SQLITE_PRIVATE void sqlite3VdbeMemSetZeroBlob(Mem *pMem, int n){
+  sqlite3VdbeMemRelease(pMem);
+  pMem->flags = MEM_Blob|MEM_Zero;
+  pMem->type = SQLITE_BLOB;
+  pMem->n = 0;
+  if( n<0 ) n = 0;
+  pMem->u.nZero = n;
+  pMem->enc = SQLITE_UTF8;
+
+#ifdef SQLITE_OMIT_INCRBLOB
+  sqlite3VdbeMemGrow(pMem, n, 0);
+  if( pMem->z ){
+    pMem->n = n;
+    memset(pMem->z, 0, n);
+  }
+#endif
+}
+
+/*
+** Delete any previous value and set the value stored in *pMem to val,
+** manifest type INTEGER.
+*/
+SQLITE_PRIVATE void sqlite3VdbeMemSetInt64(Mem *pMem, i64 val){
+  sqlite3VdbeMemRelease(pMem);
+  pMem->u.i = val;
+  pMem->flags = MEM_Int;
+  pMem->type = SQLITE_INTEGER;
+}
+
+#ifndef SQLITE_OMIT_FLOATING_POINT
+/*
+** Delete any previous value and set the value stored in *pMem to val,
+** manifest type REAL.
+*/
+SQLITE_PRIVATE void sqlite3VdbeMemSetDouble(Mem *pMem, double val){
+  if( sqlite3IsNaN(val) ){
+    sqlite3VdbeMemSetNull(pMem);
+  }else{
+    sqlite3VdbeMemRelease(pMem);
+    pMem->r = val;
+    pMem->flags = MEM_Real;
+    pMem->type = SQLITE_FLOAT;
+  }
+}
+#endif
+
+/*
+** Delete any previous value and set the value of pMem to be an
+** empty boolean index.
+*/
+SQLITE_PRIVATE void sqlite3VdbeMemSetRowSet(Mem *pMem){
+  sqlite3 *db = pMem->db;
+  assert( db!=0 );
+  assert( (pMem->flags & MEM_RowSet)==0 );
+  sqlite3VdbeMemRelease(pMem);
+  pMem->zMalloc = sqlite3DbMallocRaw(db, 64);
+  if( db->mallocFailed ){
+    pMem->flags = MEM_Null;
+  }else{
+    assert( pMem->zMalloc );
+    pMem->u.pRowSet = sqlite3RowSetInit(db, pMem->zMalloc, 
+                                       sqlite3DbMallocSize(db, pMem->zMalloc));
+    assert( pMem->u.pRowSet!=0 );
+    pMem->flags = MEM_RowSet;
+  }
+}
+
+/*
+** Return true if the Mem object contains a TEXT or BLOB that is
+** too large - whose size exceeds SQLITE_MAX_LENGTH.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMemTooBig(Mem *p){
+  assert( p->db!=0 );
+  if( p->flags & (MEM_Str|MEM_Blob) ){
+    int n = p->n;
+    if( p->flags & MEM_Zero ){
+      n += p->u.nZero;
+    }
+    return n>p->db->aLimit[SQLITE_LIMIT_LENGTH];
+  }
+  return 0; 
+}
+
+#ifdef SQLITE_DEBUG
+/*
+** This routine prepares a memory cell for modication by breaking
+** its link to a shallow copy and by marking any current shallow
+** copies of this cell as invalid.
+**
+** This is used for testing and debugging only - to make sure shallow
+** copies are not misused.
+*/
+SQLITE_PRIVATE void sqlite3VdbeMemPrepareToChange(Vdbe *pVdbe, Mem *pMem){
+  int i;
+  Mem *pX;
+  for(i=1, pX=&pVdbe->aMem[1]; i<=pVdbe->nMem; i++, pX++){
+    if( pX->pScopyFrom==pMem ){
+      pX->flags |= MEM_Invalid;
+      pX->pScopyFrom = 0;
+    }
+  }
+  pMem->pScopyFrom = 0;
+}
+#endif /* SQLITE_DEBUG */
+
+/*
+** Size of struct Mem not including the Mem.zMalloc member.
+*/
+#define MEMCELLSIZE (size_t)(&(((Mem *)0)->zMalloc))
+
+/*
+** Make an shallow copy of pFrom into pTo.  Prior contents of
+** pTo are freed.  The pFrom->z field is not duplicated.  If
+** pFrom->z is used, then pTo->z points to the same thing as pFrom->z
+** and flags gets srcType (either MEM_Ephem or MEM_Static).
+*/
+SQLITE_PRIVATE void sqlite3VdbeMemShallowCopy(Mem *pTo, const Mem *pFrom, int srcType){
+  assert( (pFrom->flags & MEM_RowSet)==0 );
+  sqlite3VdbeMemReleaseExternal(pTo);
+  memcpy(pTo, pFrom, MEMCELLSIZE);
+  pTo->xDel = 0;
+  if( (pFrom->flags&MEM_Static)==0 ){
+    pTo->flags &= ~(MEM_Dyn|MEM_Static|MEM_Ephem);
+    assert( srcType==MEM_Ephem || srcType==MEM_Static );
+    pTo->flags |= srcType;
+  }
+}
+
+/*
+** Make a full copy of pFrom into pTo.  Prior contents of pTo are
+** freed before the copy is made.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMemCopy(Mem *pTo, const Mem *pFrom){
+  int rc = SQLITE_OK;
+
+  assert( (pFrom->flags & MEM_RowSet)==0 );
+  sqlite3VdbeMemReleaseExternal(pTo);
+  memcpy(pTo, pFrom, MEMCELLSIZE);
+  pTo->flags &= ~MEM_Dyn;
+
+  if( pTo->flags&(MEM_Str|MEM_Blob) ){
+    if( 0==(pFrom->flags&MEM_Static) ){
+      pTo->flags |= MEM_Ephem;
+      rc = sqlite3VdbeMemMakeWriteable(pTo);
+    }
+  }
+
+  return rc;
+}
+
+/*
+** Transfer the contents of pFrom to pTo. Any existing value in pTo is
+** freed. If pFrom contains ephemeral data, a copy is made.
+**
+** pFrom contains an SQL NULL when this routine returns.
+*/
+SQLITE_PRIVATE void sqlite3VdbeMemMove(Mem *pTo, Mem *pFrom){
+  assert( pFrom->db==0 || sqlite3_mutex_held(pFrom->db->mutex) );
+  assert( pTo->db==0 || sqlite3_mutex_held(pTo->db->mutex) );
+  assert( pFrom->db==0 || pTo->db==0 || pFrom->db==pTo->db );
+
+  sqlite3VdbeMemRelease(pTo);
+  memcpy(pTo, pFrom, sizeof(Mem));
+  pFrom->flags = MEM_Null;
+  pFrom->xDel = 0;
+  pFrom->zMalloc = 0;
+}
+
+/*
+** Change the value of a Mem to be a string or a BLOB.
+**
+** The memory management strategy depends on the value of the xDel
+** parameter. If the value passed is SQLITE_TRANSIENT, then the 
+** string is copied into a (possibly existing) buffer managed by the 
+** Mem structure. Otherwise, any existing buffer is freed and the
+** pointer copied.
+**
+** If the string is too large (if it exceeds the SQLITE_LIMIT_LENGTH
+** size limit) then no memory allocation occurs.  If the string can be
+** stored without allocating memory, then it is.  If a memory allocation
+** is required to store the string, then value of pMem is unchanged.  In
+** either case, SQLITE_TOOBIG is returned.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMemSetStr(
+  Mem *pMem,          /* Memory cell to set to string value */
+  const char *z,      /* String pointer */
+  int n,              /* Bytes in string, or negative */
+  u8 enc,             /* Encoding of z.  0 for BLOBs */
+  void (*xDel)(void*) /* Destructor function */
+){
+  int nByte = n;      /* New value for pMem->n */
+  int iLimit;         /* Maximum allowed string or blob size */
+  u16 flags = 0;      /* New value for pMem->flags */
+
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  assert( (pMem->flags & MEM_RowSet)==0 );
+
+  /* If z is a NULL pointer, set pMem to contain an SQL NULL. */
+  if( !z ){
+    sqlite3VdbeMemSetNull(pMem);
+    return SQLITE_OK;
+  }
+
+  if( pMem->db ){
+    iLimit = pMem->db->aLimit[SQLITE_LIMIT_LENGTH];
+  }else{
+    iLimit = SQLITE_MAX_LENGTH;
+  }
+  flags = (enc==0?MEM_Blob:MEM_Str);
+  if( nByte<0 ){
+    assert( enc!=0 );
+    if( enc==SQLITE_UTF8 ){
+      for(nByte=0; nByte<=iLimit && z[nByte]; nByte++){}
+    }else{
+      for(nByte=0; nByte<=iLimit && (z[nByte] | z[nByte+1]); nByte+=2){}
+    }
+    flags |= MEM_Term;
+  }
+
+  /* The following block sets the new values of Mem.z and Mem.xDel. It
+  ** also sets a flag in local variable "flags" to indicate the memory
+  ** management (one of MEM_Dyn or MEM_Static).
+  */
+  if( xDel==SQLITE_TRANSIENT ){
+    int nAlloc = nByte;
+    if( flags&MEM_Term ){
+      nAlloc += (enc==SQLITE_UTF8?1:2);
+    }
+    if( nByte>iLimit ){
+      return SQLITE_TOOBIG;
+    }
+    if( sqlite3VdbeMemGrow(pMem, nAlloc, 0) ){
+      return SQLITE_NOMEM;
+    }
+    memcpy(pMem->z, z, nAlloc);
+  }else if( xDel==SQLITE_DYNAMIC ){
+    sqlite3VdbeMemRelease(pMem);
+    pMem->zMalloc = pMem->z = (char *)z;
+    pMem->xDel = 0;
+  }else{
+    sqlite3VdbeMemRelease(pMem);
+    pMem->z = (char *)z;
+    pMem->xDel = xDel;
+    flags |= ((xDel==SQLITE_STATIC)?MEM_Static:MEM_Dyn);
+  }
+
+  pMem->n = nByte;
+  pMem->flags = flags;
+  pMem->enc = (enc==0 ? SQLITE_UTF8 : enc);
+  pMem->type = (enc==0 ? SQLITE_BLOB : SQLITE_TEXT);
+
+#ifndef SQLITE_OMIT_UTF16
+  if( pMem->enc!=SQLITE_UTF8 && sqlite3VdbeMemHandleBom(pMem) ){
+    return SQLITE_NOMEM;
+  }
+#endif
+
+  if( nByte>iLimit ){
+    return SQLITE_TOOBIG;
+  }
+
+  return SQLITE_OK;
+}
+
+/*
+** Compare the values contained by the two memory cells, returning
+** negative, zero or positive if pMem1 is less than, equal to, or greater
+** than pMem2. Sorting order is NULL's first, followed by numbers (integers
+** and reals) sorted numerically, followed by text ordered by the collating
+** sequence pColl and finally blob's ordered by memcmp().
+**
+** Two NULL values are considered equal by this function.
+*/
+SQLITE_PRIVATE int sqlite3MemCompare(const Mem *pMem1, const Mem *pMem2, const CollSeq *pColl){
+  int rc;
+  int f1, f2;
+  int combined_flags;
+
+  f1 = pMem1->flags;
+  f2 = pMem2->flags;
+  combined_flags = f1|f2;
+  assert( (combined_flags & MEM_RowSet)==0 );
+ 
+  /* If one value is NULL, it is less than the other. If both values
+  ** are NULL, return 0.
+  */
+  if( combined_flags&MEM_Null ){
+    return (f2&MEM_Null) - (f1&MEM_Null);
+  }
+
+  /* If one value is a number and the other is not, the number is less.
+  ** If both are numbers, compare as reals if one is a real, or as integers
+  ** if both values are integers.
+  */
+  if( combined_flags&(MEM_Int|MEM_Real) ){
+    if( !(f1&(MEM_Int|MEM_Real)) ){
+      return 1;
+    }
+    if( !(f2&(MEM_Int|MEM_Real)) ){
+      return -1;
+    }
+    if( (f1 & f2 & MEM_Int)==0 ){
+      double r1, r2;
+      if( (f1&MEM_Real)==0 ){
+        r1 = (double)pMem1->u.i;
+      }else{
+        r1 = pMem1->r;
+      }
+      if( (f2&MEM_Real)==0 ){
+        r2 = (double)pMem2->u.i;
+      }else{
+        r2 = pMem2->r;
+      }
+      if( r1<r2 ) return -1;
+      if( r1>r2 ) return 1;
+      return 0;
+    }else{
+      assert( f1&MEM_Int );
+      assert( f2&MEM_Int );
+      if( pMem1->u.i < pMem2->u.i ) return -1;
+      if( pMem1->u.i > pMem2->u.i ) return 1;
+      return 0;
+    }
+  }
+
+  /* If one value is a string and the other is a blob, the string is less.
+  ** If both are strings, compare using the collating functions.
+  */
+  if( combined_flags&MEM_Str ){
+    if( (f1 & MEM_Str)==0 ){
+      return 1;
+    }
+    if( (f2 & MEM_Str)==0 ){
+      return -1;
+    }
+
+    assert( pMem1->enc==pMem2->enc );
+    assert( pMem1->enc==SQLITE_UTF8 || 
+            pMem1->enc==SQLITE_UTF16LE || pMem1->enc==SQLITE_UTF16BE );
+
+    /* The collation sequence must be defined at this point, even if
+    ** the user deletes the collation sequence after the vdbe program is
+    ** compiled (this was not always the case).
+    */
+    assert( !pColl || pColl->xCmp );
+
+    if( pColl ){
+      if( pMem1->enc==pColl->enc ){
+        /* The strings are already in the correct encoding.  Call the
+        ** comparison function directly */
+        return pColl->xCmp(pColl->pUser,pMem1->n,pMem1->z,pMem2->n,pMem2->z);
+      }else{
+        const void *v1, *v2;
+        int n1, n2;
+        Mem c1;
+        Mem c2;
+        memset(&c1, 0, sizeof(c1));
+        memset(&c2, 0, sizeof(c2));
+        sqlite3VdbeMemShallowCopy(&c1, pMem1, MEM_Ephem);
+        sqlite3VdbeMemShallowCopy(&c2, pMem2, MEM_Ephem);
+        v1 = sqlite3ValueText((sqlite3_value*)&c1, pColl->enc);
+        n1 = v1==0 ? 0 : c1.n;
+        v2 = sqlite3ValueText((sqlite3_value*)&c2, pColl->enc);
+        n2 = v2==0 ? 0 : c2.n;
+        rc = pColl->xCmp(pColl->pUser, n1, v1, n2, v2);
+        sqlite3VdbeMemRelease(&c1);
+        sqlite3VdbeMemRelease(&c2);
+        return rc;
+      }
+    }
+    /* If a NULL pointer was passed as the collate function, fall through
+    ** to the blob case and use memcmp().  */
+  }
+ 
+  /* Both values must be blobs.  Compare using memcmp().  */
+  rc = memcmp(pMem1->z, pMem2->z, (pMem1->n>pMem2->n)?pMem2->n:pMem1->n);
+  if( rc==0 ){
+    rc = pMem1->n - pMem2->n;
+  }
+  return rc;
+}
+
+/*
+** Move data out of a btree key or data field and into a Mem structure.
+** The data or key is taken from the entry that pCur is currently pointing
+** to.  offset and amt determine what portion of the data or key to retrieve.
+** key is true to get the key or false to get data.  The result is written
+** into the pMem element.
+**
+** The pMem structure is assumed to be uninitialized.  Any prior content
+** is overwritten without being freed.
+**
+** If this routine fails for any reason (malloc returns NULL or unable
+** to read from the disk) then the pMem is left in an inconsistent state.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMemFromBtree(
+  BtCursor *pCur,   /* Cursor pointing at record to retrieve. */
+  int offset,       /* Offset from the start of data to return bytes from. */
+  int amt,          /* Number of bytes to return. */
+  int key,          /* If true, retrieve from the btree key, not data. */
+  Mem *pMem         /* OUT: Return data in this Mem structure. */
+){
+  char *zData;        /* Data from the btree layer */
+  int available = 0;  /* Number of bytes available on the local btree page */
+  int rc = SQLITE_OK; /* Return code */
+
+  assert( sqlite3BtreeCursorIsValid(pCur) );
+
+  /* Note: the calls to BtreeKeyFetch() and DataFetch() below assert() 
+  ** that both the BtShared and database handle mutexes are held. */
+  assert( (pMem->flags & MEM_RowSet)==0 );
+  if( key ){
+    zData = (char *)sqlite3BtreeKeyFetch(pCur, &available);
+  }else{
+    zData = (char *)sqlite3BtreeDataFetch(pCur, &available);
+  }
+  assert( zData!=0 );
+
+  if( offset+amt<=available && (pMem->flags&MEM_Dyn)==0 ){
+    sqlite3VdbeMemRelease(pMem);
+    pMem->z = &zData[offset];
+    pMem->flags = MEM_Blob|MEM_Ephem;
+  }else if( SQLITE_OK==(rc = sqlite3VdbeMemGrow(pMem, amt+2, 0)) ){
+    pMem->flags = MEM_Blob|MEM_Dyn|MEM_Term;
+    pMem->enc = 0;
+    pMem->type = SQLITE_BLOB;
+    if( key ){
+      rc = sqlite3BtreeKey(pCur, offset, amt, pMem->z);
+    }else{
+      rc = sqlite3BtreeData(pCur, offset, amt, pMem->z);
+    }
+    pMem->z[amt] = 0;
+    pMem->z[amt+1] = 0;
+    if( rc!=SQLITE_OK ){
+      sqlite3VdbeMemRelease(pMem);
+    }
+  }
+  pMem->n = amt;
+
+  return rc;
+}
+
+/* This function is only available internally, it is not part of the
+** external API. It works in a similar way to sqlite3_value_text(),
+** except the data returned is in the encoding specified by the second
+** parameter, which must be one of SQLITE_UTF16BE, SQLITE_UTF16LE or
+** SQLITE_UTF8.
+**
+** (2006-02-16:)  The enc value can be or-ed with SQLITE_UTF16_ALIGNED.
+** If that is the case, then the result must be aligned on an even byte
+** boundary.
+*/
+SQLITE_PRIVATE const void *sqlite3ValueText(sqlite3_value* pVal, u8 enc){
+  if( !pVal ) return 0;
+
+  assert( pVal->db==0 || sqlite3_mutex_held(pVal->db->mutex) );
+  assert( (enc&3)==(enc&~SQLITE_UTF16_ALIGNED) );
+  assert( (pVal->flags & MEM_RowSet)==0 );
+
+  if( pVal->flags&MEM_Null ){
+    return 0;
+  }
+  assert( (MEM_Blob>>3) == MEM_Str );
+  pVal->flags |= (pVal->flags & MEM_Blob)>>3;
+  expandBlob(pVal);
+  if( pVal->flags&MEM_Str ){
+    sqlite3VdbeChangeEncoding(pVal, enc & ~SQLITE_UTF16_ALIGNED);
+    if( (enc & SQLITE_UTF16_ALIGNED)!=0 && 1==(1&SQLITE_PTR_TO_INT(pVal->z)) ){
+      assert( (pVal->flags & (MEM_Ephem|MEM_Static))!=0 );
+      if( sqlite3VdbeMemMakeWriteable(pVal)!=SQLITE_OK ){
+        return 0;
+      }
+    }
+    sqlite3VdbeMemNulTerminate(pVal); /* IMP: R-59893-45467 */
+  }else{
+    assert( (pVal->flags&MEM_Blob)==0 );
+    sqlite3VdbeMemStringify(pVal, enc);
+    assert( 0==(1&SQLITE_PTR_TO_INT(pVal->z)) );
+  }
+  assert(pVal->enc==(enc & ~SQLITE_UTF16_ALIGNED) || pVal->db==0
+              || pVal->db->mallocFailed );
+  if( pVal->enc==(enc & ~SQLITE_UTF16_ALIGNED) ){
+    return pVal->z;
+  }else{
+    return 0;
+  }
+}
+
+/*
+** Create a new sqlite3_value object.
+*/
+SQLITE_PRIVATE sqlite3_value *sqlite3ValueNew(sqlite3 *db){
+  Mem *p = sqlite3DbMallocZero(db, sizeof(*p));
+  if( p ){
+    p->flags = MEM_Null;
+    p->type = SQLITE_NULL;
+    p->db = db;
+  }
+  return p;
+}
+
+/*
+** Create a new sqlite3_value object, containing the value of pExpr.
+**
+** This only works for very simple expressions that consist of one constant
+** token (i.e. "5", "5.1", "'a string'"). If the expression can
+** be converted directly into a value, then the value is allocated and
+** a pointer written to *ppVal. The caller is responsible for deallocating
+** the value by passing it to sqlite3ValueFree() later on. If the expression
+** cannot be converted to a value, then *ppVal is set to NULL.
+*/
+SQLITE_PRIVATE int sqlite3ValueFromExpr(
+  sqlite3 *db,              /* The database connection */
+  Expr *pExpr,              /* The expression to evaluate */
+  u8 enc,                   /* Encoding to use */
+  u8 affinity,              /* Affinity to use */
+  sqlite3_value **ppVal     /* Write the new value here */
+){
+  int op;
+  char *zVal = 0;
+  sqlite3_value *pVal = 0;
+  int negInt = 1;
+  const char *zNeg = "";
+
+  if( !pExpr ){
+    *ppVal = 0;
+    return SQLITE_OK;
+  }
+  op = pExpr->op;
+
+  /* op can only be TK_REGISTER if we have compiled with SQLITE_ENABLE_STAT2.
+  ** The ifdef here is to enable us to achieve 100% branch test coverage even
+  ** when SQLITE_ENABLE_STAT2 is omitted.
+  */
+#ifdef SQLITE_ENABLE_STAT2
+  if( op==TK_REGISTER ) op = pExpr->op2;
+#else
+  if( NEVER(op==TK_REGISTER) ) op = pExpr->op2;
+#endif
+
+  /* Handle negative integers in a single step.  This is needed in the
+  ** case when the value is -9223372036854775808.
+  */
+  if( op==TK_UMINUS
+   && (pExpr->pLeft->op==TK_INTEGER || pExpr->pLeft->op==TK_FLOAT) ){
+    pExpr = pExpr->pLeft;
+    op = pExpr->op;
+    negInt = -1;
+    zNeg = "-";
+  }
+
+  if( op==TK_STRING || op==TK_FLOAT || op==TK_INTEGER ){
+    pVal = sqlite3ValueNew(db);
+    if( pVal==0 ) goto no_mem;
+    if( ExprHasProperty(pExpr, EP_IntValue) ){
+      sqlite3VdbeMemSetInt64(pVal, (i64)pExpr->u.iValue*negInt);
+    }else{
+      zVal = sqlite3MPrintf(db, "%s%s", zNeg, pExpr->u.zToken);
+      if( zVal==0 ) goto no_mem;
+      sqlite3ValueSetStr(pVal, -1, zVal, SQLITE_UTF8, SQLITE_DYNAMIC);
+      if( op==TK_FLOAT ) pVal->type = SQLITE_FLOAT;
+    }
+    if( (op==TK_INTEGER || op==TK_FLOAT ) && affinity==SQLITE_AFF_NONE ){
+      sqlite3ValueApplyAffinity(pVal, SQLITE_AFF_NUMERIC, SQLITE_UTF8);
+    }else{
+      sqlite3ValueApplyAffinity(pVal, affinity, SQLITE_UTF8);
+    }
+    if( pVal->flags & (MEM_Int|MEM_Real) ) pVal->flags &= ~MEM_Str;
+    if( enc!=SQLITE_UTF8 ){
+      sqlite3VdbeChangeEncoding(pVal, enc);
+    }
+  }else if( op==TK_UMINUS ) {
+    /* This branch happens for multiple negative signs.  Ex: -(-5) */
+    if( SQLITE_OK==sqlite3ValueFromExpr(db,pExpr->pLeft,enc,affinity,&pVal) ){
+      sqlite3VdbeMemNumerify(pVal);
+      if( pVal->u.i==SMALLEST_INT64 ){
+        pVal->flags &= MEM_Int;
+        pVal->flags |= MEM_Real;
+        pVal->r = (double)LARGEST_INT64;
+      }else{
+        pVal->u.i = -pVal->u.i;
+      }
+      pVal->r = -pVal->r;
+      sqlite3ValueApplyAffinity(pVal, affinity, enc);
+    }
+  }else if( op==TK_NULL ){
+    pVal = sqlite3ValueNew(db);
+    if( pVal==0 ) goto no_mem;
+  }
+#ifndef SQLITE_OMIT_BLOB_LITERAL
+  else if( op==TK_BLOB ){
+    int nVal;
+    assert( pExpr->u.zToken[0]=='x' || pExpr->u.zToken[0]=='X' );
+    assert( pExpr->u.zToken[1]=='\'' );
+    pVal = sqlite3ValueNew(db);
+    if( !pVal ) goto no_mem;
+    zVal = &pExpr->u.zToken[2];
+    nVal = sqlite3Strlen30(zVal)-1;
+    assert( zVal[nVal]=='\'' );
+    sqlite3VdbeMemSetStr(pVal, sqlite3HexToBlob(db, zVal, nVal), nVal/2,
+                         0, SQLITE_DYNAMIC);
+  }
+#endif
+
+  if( pVal ){
+    sqlite3VdbeMemStoreType(pVal);
+  }
+  *ppVal = pVal;
+  return SQLITE_OK;
+
+no_mem:
+  db->mallocFailed = 1;
+  sqlite3DbFree(db, zVal);
+  sqlite3ValueFree(pVal);
+  *ppVal = 0;
+  return SQLITE_NOMEM;
+}
+
+/*
+** Change the string value of an sqlite3_value object
+*/
+SQLITE_PRIVATE void sqlite3ValueSetStr(
+  sqlite3_value *v,     /* Value to be set */
+  int n,                /* Length of string z */
+  const void *z,        /* Text of the new string */
+  u8 enc,               /* Encoding to use */
+  void (*xDel)(void*)   /* Destructor for the string */
+){
+  if( v ) sqlite3VdbeMemSetStr((Mem *)v, z, n, enc, xDel);
+}
+
+/*
+** Free an sqlite3_value object
+*/
+SQLITE_PRIVATE void sqlite3ValueFree(sqlite3_value *v){
+  if( !v ) return;
+  sqlite3VdbeMemRelease((Mem *)v);
+  sqlite3DbFree(((Mem*)v)->db, v);
+}
+
+/*
+** Return the number of bytes in the sqlite3_value object assuming
+** that it uses the encoding "enc"
+*/
+SQLITE_PRIVATE int sqlite3ValueBytes(sqlite3_value *pVal, u8 enc){
+  Mem *p = (Mem*)pVal;
+  if( (p->flags & MEM_Blob)!=0 || sqlite3ValueText(pVal, enc) ){
+    if( p->flags & MEM_Zero ){
+      return p->n + p->u.nZero;
+    }else{
+      return p->n;
+    }
+  }
+  return 0;
+}
+
+/************** End of vdbemem.c *********************************************/
+/************** Begin file vdbeaux.c *****************************************/
+/*
+** 2003 September 6
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains code used for creating, destroying, and populating
+** a VDBE (or an "sqlite3_stmt" as it is known to the outside world.)  Prior
+** to version 2.8.7, all this code was combined into the vdbe.c source file.
+** But that file was getting too big so this subroutines were split out.
+*/
+
+
+
+/*
+** When debugging the code generator in a symbolic debugger, one can
+** set the sqlite3VdbeAddopTrace to 1 and all opcodes will be printed
+** as they are added to the instruction stream.
+*/
+#ifdef SQLITE_DEBUG
+SQLITE_PRIVATE int sqlite3VdbeAddopTrace = 0;
+#endif
+
+
+/*
+** Create a new virtual database engine.
+*/
+SQLITE_PRIVATE Vdbe *sqlite3VdbeCreate(sqlite3 *db){
+  Vdbe *p;
+  p = sqlite3DbMallocZero(db, sizeof(Vdbe) );
+  if( p==0 ) return 0;
+  p->db = db;
+  if( db->pVdbe ){
+    db->pVdbe->pPrev = p;
+  }
+  p->pNext = db->pVdbe;
+  p->pPrev = 0;
+  db->pVdbe = p;
+  p->magic = VDBE_MAGIC_INIT;
+  return p;
+}
+
+/*
+** Remember the SQL string for a prepared statement.
+*/
+SQLITE_PRIVATE void sqlite3VdbeSetSql(Vdbe *p, const char *z, int n, int isPrepareV2){
+  assert( isPrepareV2==1 || isPrepareV2==0 );
+  if( p==0 ) return;
+#ifdef SQLITE_OMIT_TRACE
+  if( !isPrepareV2 ) return;
+#endif
+  assert( p->zSql==0 );
+  p->zSql = sqlite3DbStrNDup(p->db, z, n);
+  p->isPrepareV2 = (u8)isPrepareV2;
+}
+
+/*
+** Return the SQL associated with a prepared statement
+*/
+SQLITE_API const char *sqlite3_sql(sqlite3_stmt *pStmt){
+  Vdbe *p = (Vdbe *)pStmt;
+  return (p && p->isPrepareV2) ? p->zSql : 0;
+}
+
+/*
+** Swap all content between two VDBE structures.
+*/
+SQLITE_PRIVATE void sqlite3VdbeSwap(Vdbe *pA, Vdbe *pB){
+  Vdbe tmp, *pTmp;
+  char *zTmp;
+  tmp = *pA;
+  *pA = *pB;
+  *pB = tmp;
+  pTmp = pA->pNext;
+  pA->pNext = pB->pNext;
+  pB->pNext = pTmp;
+  pTmp = pA->pPrev;
+  pA->pPrev = pB->pPrev;
+  pB->pPrev = pTmp;
+  zTmp = pA->zSql;
+  pA->zSql = pB->zSql;
+  pB->zSql = zTmp;
+  pB->isPrepareV2 = pA->isPrepareV2;
+}
+
+#ifdef SQLITE_DEBUG
+/*
+** Turn tracing on or off
+*/
+SQLITE_PRIVATE void sqlite3VdbeTrace(Vdbe *p, FILE *trace){
+  p->trace = trace;
+}
+#endif
+
+/*
+** Resize the Vdbe.aOp array so that it is at least one op larger than 
+** it was.
+**
+** If an out-of-memory error occurs while resizing the array, return
+** SQLITE_NOMEM. In this case Vdbe.aOp and Vdbe.nOpAlloc remain 
+** unchanged (this is so that any opcodes already allocated can be 
+** correctly deallocated along with the rest of the Vdbe).
+*/
+static int growOpArray(Vdbe *p){
+  VdbeOp *pNew;
+  int nNew = (p->nOpAlloc ? p->nOpAlloc*2 : (int)(1024/sizeof(Op)));
+  pNew = sqlite3DbRealloc(p->db, p->aOp, nNew*sizeof(Op));
+  if( pNew ){
+    p->nOpAlloc = sqlite3DbMallocSize(p->db, pNew)/sizeof(Op);
+    p->aOp = pNew;
+  }
+  return (pNew ? SQLITE_OK : SQLITE_NOMEM);
+}
+
+/*
+** Add a new instruction to the list of instructions current in the
+** VDBE.  Return the address of the new instruction.
+**
+** Parameters:
+**
+**    p               Pointer to the VDBE
+**
+**    op              The opcode for this instruction
+**
+**    p1, p2, p3      Operands
+**
+** Use the sqlite3VdbeResolveLabel() function to fix an address and
+** the sqlite3VdbeChangeP4() function to change the value of the P4
+** operand.
+*/
+SQLITE_PRIVATE int sqlite3VdbeAddOp3(Vdbe *p, int op, int p1, int p2, int p3){
+  int i;
+  VdbeOp *pOp;
+
+  i = p->nOp;
+  assert( p->magic==VDBE_MAGIC_INIT );
+  assert( op>0 && op<0xff );
+  if( p->nOpAlloc<=i ){
+    if( growOpArray(p) ){
+      return 1;
+    }
+  }
+  p->nOp++;
+  pOp = &p->aOp[i];
+  pOp->opcode = (u8)op;
+  pOp->p5 = 0;
+  pOp->p1 = p1;
+  pOp->p2 = p2;
+  pOp->p3 = p3;
+  pOp->p4.p = 0;
+  pOp->p4type = P4_NOTUSED;
+  p->expired = 0;
+  if( op==OP_ParseSchema ){
+    /* Any program that uses the OP_ParseSchema opcode needs to lock
+    ** all btrees. */
+    int j;
+    for(j=0; j<p->db->nDb; j++) sqlite3VdbeUsesBtree(p, j);
+  }
+#ifdef SQLITE_DEBUG
+  pOp->zComment = 0;
+  if( sqlite3VdbeAddopTrace ) sqlite3VdbePrintOp(0, i, &p->aOp[i]);
+#endif
+#ifdef VDBE_PROFILE
+  pOp->cycles = 0;
+  pOp->cnt = 0;
+#endif
+  return i;
+}
+SQLITE_PRIVATE int sqlite3VdbeAddOp0(Vdbe *p, int op){
+  return sqlite3VdbeAddOp3(p, op, 0, 0, 0);
+}
+SQLITE_PRIVATE int sqlite3VdbeAddOp1(Vdbe *p, int op, int p1){
+  return sqlite3VdbeAddOp3(p, op, p1, 0, 0);
+}
+SQLITE_PRIVATE int sqlite3VdbeAddOp2(Vdbe *p, int op, int p1, int p2){
+  return sqlite3VdbeAddOp3(p, op, p1, p2, 0);
+}
+
+
+/*
+** Add an opcode that includes the p4 value as a pointer.
+*/
+SQLITE_PRIVATE int sqlite3VdbeAddOp4(
+  Vdbe *p,            /* Add the opcode to this VM */
+  int op,             /* The new opcode */
+  int p1,             /* The P1 operand */
+  int p2,             /* The P2 operand */
+  int p3,             /* The P3 operand */
+  const char *zP4,    /* The P4 operand */
+  int p4type          /* P4 operand type */
+){
+  int addr = sqlite3VdbeAddOp3(p, op, p1, p2, p3);
+  sqlite3VdbeChangeP4(p, addr, zP4, p4type);
+  return addr;
+}
+
+/*
+** Add an opcode that includes the p4 value as an integer.
+*/
+SQLITE_PRIVATE int sqlite3VdbeAddOp4Int(
+  Vdbe *p,            /* Add the opcode to this VM */
+  int op,             /* The new opcode */
+  int p1,             /* The P1 operand */
+  int p2,             /* The P2 operand */
+  int p3,             /* The P3 operand */
+  int p4              /* The P4 operand as an integer */
+){
+  int addr = sqlite3VdbeAddOp3(p, op, p1, p2, p3);
+  sqlite3VdbeChangeP4(p, addr, SQLITE_INT_TO_PTR(p4), P4_INT32);
+  return addr;
+}
+
+/*
+** Create a new symbolic label for an instruction that has yet to be
+** coded.  The symbolic label is really just a negative number.  The
+** label can be used as the P2 value of an operation.  Later, when
+** the label is resolved to a specific address, the VDBE will scan
+** through its operation list and change all values of P2 which match
+** the label into the resolved address.
+**
+** The VDBE knows that a P2 value is a label because labels are
+** always negative and P2 values are suppose to be non-negative.
+** Hence, a negative P2 value is a label that has yet to be resolved.
+**
+** Zero is returned if a malloc() fails.
+*/
+SQLITE_PRIVATE int sqlite3VdbeMakeLabel(Vdbe *p){
+  int i;
+  i = p->nLabel++;
+  assert( p->magic==VDBE_MAGIC_INIT );
+  if( i>=p->nLabelAlloc ){
+    int n = p->nLabelAlloc*2 + 5;
+    p->aLabel = sqlite3DbReallocOrFree(p->db, p->aLabel,
+                                       n*sizeof(p->aLabel[0]));
+    p->nLabelAlloc = sqlite3DbMallocSize(p->db, p->aLabel)/sizeof(p->aLabel[0]);
+  }
+  if( p->aLabel ){
+    p->aLabel[i] = -1;
+  }
+  return -1-i;
+}
+
+/*
+** Resolve label "x" to be the address of the next instruction to
+** be inserted.  The parameter "x" must have been obtained from
+** a prior call to sqlite3VdbeMakeLabel().
+*/
+SQLITE_PRIVATE void sqlite3VdbeResolveLabel(Vdbe *p, int x){
+  int j = -1-x;
+  assert( p->magic==VDBE_MAGIC_INIT );
+  assert( j>=0 && j<p->nLabel );
+  if( p->aLabel ){
+    p->aLabel[j] = p->nOp;
+  }
+}
+
+/*
+** Mark the VDBE as one that can only be run one time.
+*/
+SQLITE_PRIVATE void sqlite3VdbeRunOnlyOnce(Vdbe *p){
+  p->runOnlyOnce = 1;
+}
+
+#ifdef SQLITE_DEBUG /* sqlite3AssertMayAbort() logic */
+
+/*
+** The following type and function are used to iterate through all opcodes
+** in a Vdbe main program and each of the sub-programs (triggers) it may 
+** invoke directly or indirectly. It should be used as follows:
+**
+**   Op *pOp;
+**   VdbeOpIter sIter;
+**
+**   memset(&sIter, 0, sizeof(sIter));
+**   sIter.v = v;                            // v is of type Vdbe* 
+**   while( (pOp = opIterNext(&sIter)) ){
+**     // Do something with pOp
+**   }
+**   sqlite3DbFree(v->db, sIter.apSub);
+** 
+*/
+typedef struct VdbeOpIter VdbeOpIter;
+struct VdbeOpIter {
+  Vdbe *v;                   /* Vdbe to iterate through the opcodes of */
+  SubProgram **apSub;        /* Array of subprograms */
+  int nSub;                  /* Number of entries in apSub */
+  int iAddr;                 /* Address of next instruction to return */
+  int iSub;                  /* 0 = main program, 1 = first sub-program etc. */
+};
+static Op *opIterNext(VdbeOpIter *p){
+  Vdbe *v = p->v;
+  Op *pRet = 0;
+  Op *aOp;
+  int nOp;
+
+  if( p->iSub<=p->nSub ){
+
+    if( p->iSub==0 ){
+      aOp = v->aOp;
+      nOp = v->nOp;
+    }else{
+      aOp = p->apSub[p->iSub-1]->aOp;
+      nOp = p->apSub[p->iSub-1]->nOp;
+    }
+    assert( p->iAddr<nOp );
+
+    pRet = &aOp[p->iAddr];
+    p->iAddr++;
+    if( p->iAddr==nOp ){
+      p->iSub++;
+      p->iAddr = 0;
+    }
+  
+    if( pRet->p4type==P4_SUBPROGRAM ){
+      int nByte = (p->nSub+1)*sizeof(SubProgram*);
+      int j;
+      for(j=0; j<p->nSub; j++){
+        if( p->apSub[j]==pRet->p4.pProgram ) break;
+      }
+      if( j==p->nSub ){
+        p->apSub = sqlite3DbReallocOrFree(v->db, p->apSub, nByte);
+        if( !p->apSub ){
+          pRet = 0;
+        }else{
+          p->apSub[p->nSub++] = pRet->p4.pProgram;
+        }
+      }
+    }
+  }
+
+  return pRet;
+}
+
+/*
+** Check if the program stored in the VM associated with pParse may
+** throw an ABORT exception (causing the statement, but not entire transaction
+** to be rolled back). This condition is true if the main program or any
+** sub-programs contains any of the following:
+**
+**   *  OP_Halt with P1=SQLITE_CONSTRAINT and P2=OE_Abort.
+**   *  OP_HaltIfNull with P1=SQLITE_CONSTRAINT and P2=OE_Abort.
+**   *  OP_Destroy
+**   *  OP_VUpdate
+**   *  OP_VRename
+**   *  OP_FkCounter with P2==0 (immediate foreign key constraint)
+**
+** Then check that the value of Parse.mayAbort is true if an
+** ABORT may be thrown, or false otherwise. Return true if it does
+** match, or false otherwise. This function is intended to be used as
+** part of an assert statement in the compiler. Similar to:
+**
+**   assert( sqlite3VdbeAssertMayAbort(pParse->pVdbe, pParse->mayAbort) );
+*/
+SQLITE_PRIVATE int sqlite3VdbeAssertMayAbort(Vdbe *v, int mayAbort){
+  int hasAbort = 0;
+  Op *pOp;
+  VdbeOpIter sIter;
+  memset(&sIter, 0, sizeof(sIter));
+  sIter.v = v;
+
+  while( (pOp = opIterNext(&sIter))!=0 ){
+    int opcode = pOp->opcode;
+    if( opcode==OP_Destroy || opcode==OP_VUpdate || opcode==OP_VRename 
+#ifndef SQLITE_OMIT_FOREIGN_KEY
+     || (opcode==OP_FkCounter && pOp->p1==0 && pOp->p2==1) 
+#endif
+     || ((opcode==OP_Halt || opcode==OP_HaltIfNull) 
+      && (pOp->p1==SQLITE_CONSTRAINT && pOp->p2==OE_Abort))
+    ){
+      hasAbort = 1;
+      break;
+    }
+  }
+  sqlite3DbFree(v->db, sIter.apSub);
+
+  /* Return true if hasAbort==mayAbort. Or if a malloc failure occured.
+  ** If malloc failed, then the while() loop above may not have iterated
+  ** through all opcodes and hasAbort may be set incorrectly. Return
+  ** true for this case to prevent the assert() in the callers frame
+  ** from failing.  */
+  return ( v->db->mallocFailed || hasAbort==mayAbort );
+}
+#endif /* SQLITE_DEBUG - the sqlite3AssertMayAbort() function */
+
+/*
+** Loop through the program looking for P2 values that are negative
+** on jump instructions.  Each such value is a label.  Resolve the
+** label by setting the P2 value to its correct non-zero value.
+**
+** This routine is called once after all opcodes have been inserted.
+**
+** Variable *pMaxFuncArgs is set to the maximum value of any P2 argument 
+** to an OP_Function, OP_AggStep or OP_VFilter opcode. This is used by 
+** sqlite3VdbeMakeReady() to size the Vdbe.apArg[] array.
+**
+** The Op.opflags field is set on all opcodes.
+*/
+static void resolveP2Values(Vdbe *p, int *pMaxFuncArgs){
+  int i;
+  int nMaxArgs = *pMaxFuncArgs;
+  Op *pOp;
+  int *aLabel = p->aLabel;
+  p->readOnly = 1;
+  for(pOp=p->aOp, i=p->nOp-1; i>=0; i--, pOp++){
+    u8 opcode = pOp->opcode;
+
+    pOp->opflags = sqlite3OpcodeProperty[opcode];
+    if( opcode==OP_Function || opcode==OP_AggStep ){
+      if( pOp->p5>nMaxArgs ) nMaxArgs = pOp->p5;
+    }else if( (opcode==OP_Transaction && pOp->p2!=0) || opcode==OP_Vacuum ){
+      p->readOnly = 0;
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+    }else if( opcode==OP_VUpdate ){
+      if( pOp->p2>nMaxArgs ) nMaxArgs = pOp->p2;
+    }else if( opcode==OP_VFilter ){
+      int n;
+      assert( p->nOp - i >= 3 );
+      assert( pOp[-1].opcode==OP_Integer );
+      n = pOp[-1].p1;
+      if( n>nMaxArgs ) nMaxArgs = n;
+#endif
+    }
+
+    if( (pOp->opflags & OPFLG_JUMP)!=0 && pOp->p2<0 ){
+      assert( -1-pOp->p2<p->nLabel );
+      pOp->p2 = aLabel[-1-pOp->p2];
+    }
+  }
+  sqlite3DbFree(p->db, p->aLabel);
+  p->aLabel = 0;
+
+  *pMaxFuncArgs = nMaxArgs;
+}
+
+/*
+** Return the address of the next instruction to be inserted.
+*/
+SQLITE_PRIVATE int sqlite3VdbeCurrentAddr(Vdbe *p){
+  assert( p->magic==VDBE_MAGIC_INIT );
+  return p->nOp;
+}
+
+/*
+** This function returns a pointer to the array of opcodes associated with
+** the Vdbe passed as the first argument. It is the callers responsibility
+** to arrange for the returned array to be eventually freed using the 
+** vdbeFreeOpArray() function.
+**
+** Before returning, *pnOp is set to the number of entries in the returned
+** array. Also, *pnMaxArg is set to the larger of its current value and 
+** the number of entries in the Vdbe.apArg[] array required to execute the 
+** returned program.
+*/
+SQLITE_PRIVATE VdbeOp *sqlite3VdbeTakeOpArray(Vdbe *p, int *pnOp, int *pnMaxArg){
+  VdbeOp *aOp = p->aOp;
+  assert( aOp && !p->db->mallocFailed );
+
+  /* Check that sqlite3VdbeUsesBtree() was not called on this VM */
+  assert( p->btreeMask==0 );
+
+  resolveP2Values(p, pnMaxArg);
+  *pnOp = p->nOp;
+  p->aOp = 0;
+  return aOp;
+}
+
+/*
+** Add a whole list of operations to the operation stack.  Return the
+** address of the first operation added.
+*/
+SQLITE_PRIVATE int sqlite3VdbeAddOpList(Vdbe *p, int nOp, VdbeOpList const *aOp){
+  int addr;
+  assert( p->magic==VDBE_MAGIC_INIT );
+  if( p->nOp + nOp > p->nOpAlloc && growOpArray(p) ){
+    return 0;
+  }
+  addr = p->nOp;
+  if( ALWAYS(nOp>0) ){
+    int i;
+    VdbeOpList const *pIn = aOp;
+    for(i=0; i<nOp; i++, pIn++){
+      int p2 = pIn->p2;
+      VdbeOp *pOut = &p->aOp[i+addr];
+      pOut->opcode = pIn->opcode;
+      pOut->p1 = pIn->p1;
+      if( p2<0 && (sqlite3OpcodeProperty[pOut->opcode] & OPFLG_JUMP)!=0 ){
+        pOut->p2 = addr + ADDR(p2);
+      }else{
+        pOut->p2 = p2;
+      }
+      pOut->p3 = pIn->p3;
+      pOut->p4type = P4_NOTUSED;
+      pOut->p4.p = 0;
+      pOut->p5 = 0;
+#ifdef SQLITE_DEBUG
+      pOut->zComment = 0;
+      if( sqlite3VdbeAddopTrace ){
+        sqlite3VdbePrintOp(0, i+addr, &p->aOp[i+addr]);
+      }
+#endif
+    }
+    p->nOp += nOp;
+  }
+  return addr;
+}
+
+/*
+** Change the value of the P1 operand for a specific instruction.
+** This routine is useful when a large program is loaded from a
+** static array using sqlite3VdbeAddOpList but we want to make a
+** few minor changes to the program.
+*/
+SQLITE_PRIVATE void sqlite3VdbeChangeP1(Vdbe *p, int addr, int val){
+  assert( p!=0 );
+  assert( addr>=0 );
+  if( p->nOp>addr ){
+    p->aOp[addr].p1 = val;
+  }
+}
+
+/*
+** Change the value of the P2 operand for a specific instruction.
+** This routine is useful for setting a jump destination.
+*/
+SQLITE_PRIVATE void sqlite3VdbeChangeP2(Vdbe *p, int addr, int val){
+  assert( p!=0 );
+  assert( addr>=0 );
+  if( p->nOp>addr ){
+    p->aOp[addr].p2 = val;
+  }
+}
+
+/*
+** Change the value of the P3 operand for a specific instruction.
+*/
+SQLITE_PRIVATE void sqlite3VdbeChangeP3(Vdbe *p, int addr, int val){
+  assert( p!=0 );
+  assert( addr>=0 );
+  if( p->nOp>addr ){
+    p->aOp[addr].p3 = val;
+  }
+}
+
+/*
+** Change the value of the P5 operand for the most recently
+** added operation.
+*/
+SQLITE_PRIVATE void sqlite3VdbeChangeP5(Vdbe *p, u8 val){
+  assert( p!=0 );
+  if( p->aOp ){
+    assert( p->nOp>0 );
+    p->aOp[p->nOp-1].p5 = val;
+  }
+}
+
+/*
+** Change the P2 operand of instruction addr so that it points to
+** the address of the next instruction to be coded.
+*/
+SQLITE_PRIVATE void sqlite3VdbeJumpHere(Vdbe *p, int addr){
+  assert( addr>=0 );
+  sqlite3VdbeChangeP2(p, addr, p->nOp);
+}
+
+
+/*
+** If the input FuncDef structure is ephemeral, then free it.  If
+** the FuncDef is not ephermal, then do nothing.
+*/
+static void freeEphemeralFunction(sqlite3 *db, FuncDef *pDef){
+  if( ALWAYS(pDef) && (pDef->flags & SQLITE_FUNC_EPHEM)!=0 ){
+    sqlite3DbFree(db, pDef);
+  }
+}
+
+static void vdbeFreeOpArray(sqlite3 *, Op *, int);
+
+/*
+** Delete a P4 value if necessary.
+*/
+static void freeP4(sqlite3 *db, int p4type, void *p4){
+  if( p4 ){
+    assert( db );
+    switch( p4type ){
+      case P4_REAL:
+      case P4_INT64:
+      case P4_DYNAMIC:
+      case P4_KEYINFO:
+      case P4_INTARRAY:
+      case P4_KEYINFO_HANDOFF: {
+        sqlite3DbFree(db, p4);
+        break;
+      }
+      case P4_MPRINTF: {
+        if( db->pnBytesFreed==0 ) sqlite3_free(p4);
+        break;
+      }
+      case P4_VDBEFUNC: {
+        VdbeFunc *pVdbeFunc = (VdbeFunc *)p4;
+        freeEphemeralFunction(db, pVdbeFunc->pFunc);
+        if( db->pnBytesFreed==0 ) sqlite3VdbeDeleteAuxData(pVdbeFunc, 0);
+        sqlite3DbFree(db, pVdbeFunc);
+        break;
+      }
+      case P4_FUNCDEF: {
+        freeEphemeralFunction(db, (FuncDef*)p4);
+        break;
+      }
+      case P4_MEM: {
+        if( db->pnBytesFreed==0 ){
+          sqlite3ValueFree((sqlite3_value*)p4);
+        }else{
+          Mem *p = (Mem*)p4;
+          sqlite3DbFree(db, p->zMalloc);
+          sqlite3DbFree(db, p);
+        }
+        break;
+      }
+      case P4_VTAB : {
+        if( db->pnBytesFreed==0 ) sqlite3VtabUnlock((VTable *)p4);
+        break;
+      }
+    }
+  }
+}
+
+/*
+** Free the space allocated for aOp and any p4 values allocated for the
+** opcodes contained within. If aOp is not NULL it is assumed to contain 
+** nOp entries. 
+*/
+static void vdbeFreeOpArray(sqlite3 *db, Op *aOp, int nOp){
+  if( aOp ){
+    Op *pOp;
+    for(pOp=aOp; pOp<&aOp[nOp]; pOp++){
+      freeP4(db, pOp->p4type, pOp->p4.p);
+#ifdef SQLITE_DEBUG
+      sqlite3DbFree(db, pOp->zComment);
+#endif     
+    }
+  }
+  sqlite3DbFree(db, aOp);
+}
+
+/*
+** Link the SubProgram object passed as the second argument into the linked
+** list at Vdbe.pSubProgram. This list is used to delete all sub-program
+** objects when the VM is no longer required.
+*/
+SQLITE_PRIVATE void sqlite3VdbeLinkSubProgram(Vdbe *pVdbe, SubProgram *p){
+  p->pNext = pVdbe->pProgram;
+  pVdbe->pProgram = p;
+}
+
+/*
+** Change N opcodes starting at addr to No-ops.
+*/
+SQLITE_PRIVATE void sqlite3VdbeChangeToNoop(Vdbe *p, int addr, int N){
+  if( p->aOp ){
+    VdbeOp *pOp = &p->aOp[addr];
+    sqlite3 *db = p->db;
+    while( N-- ){
+      freeP4(db, pOp->p4type, pOp->p4.p);
+      memset(pOp, 0, sizeof(pOp[0]));
+      pOp->opcode = OP_Noop;
+      pOp++;
+    }
+  }
+}
+
+/*
+** Change the value of the P4 operand for a specific instruction.
+** This routine is useful when a large program is loaded from a
+** static array using sqlite3VdbeAddOpList but we want to make a
+** few minor changes to the program.
+**
+** If n>=0 then the P4 operand is dynamic, meaning that a copy of
+** the string is made into memory obtained from sqlite3_malloc().
+** A value of n==0 means copy bytes of zP4 up to and including the
+** first null byte.  If n>0 then copy n+1 bytes of zP4.
+**
+** If n==P4_KEYINFO it means that zP4 is a pointer to a KeyInfo structure.
+** A copy is made of the KeyInfo structure into memory obtained from
+** sqlite3_malloc, to be freed when the Vdbe is finalized.
+** n==P4_KEYINFO_HANDOFF indicates that zP4 points to a KeyInfo structure
+** stored in memory that the caller has obtained from sqlite3_malloc. The 
+** caller should not free the allocation, it will be freed when the Vdbe is
+** finalized.
+** 
+** Other values of n (P4_STATIC, P4_COLLSEQ etc.) indicate that zP4 points
+** to a string or structure that is guaranteed to exist for the lifetime of
+** the Vdbe. In these cases we can just copy the pointer.
+**
+** If addr<0 then change P4 on the most recently inserted instruction.
+*/
+SQLITE_PRIVATE void sqlite3VdbeChangeP4(Vdbe *p, int addr, const char *zP4, int n){
+  Op *pOp;
+  sqlite3 *db;
+  assert( p!=0 );
+  db = p->db;
+  assert( p->magic==VDBE_MAGIC_INIT );
+  if( p->aOp==0 || db->mallocFailed ){
+    if ( n!=P4_KEYINFO && n!=P4_VTAB ) {
+      freeP4(db, n, (void*)*(char**)&zP4);
+    }
+    return;
+  }
+  assert( p->nOp>0 );
+  assert( addr<p->nOp );
+  if( addr<0 ){
+    addr = p->nOp - 1;
+  }
+  pOp = &p->aOp[addr];
+  freeP4(db, pOp->p4type, pOp->p4.p);
+  pOp->p4.p = 0;
+  if( n==P4_INT32 ){
+    /* Note: this cast is safe, because the origin data point was an int
+    ** that was cast to a (const char *). */
+    pOp->p4.i = SQLITE_PTR_TO_INT(zP4);
+    pOp->p4type = P4_INT32;
+  }else if( zP4==0 ){
+    pOp->p4.p = 0;
+    pOp->p4type = P4_NOTUSED;
+  }else if( n==P4_KEYINFO ){
+    KeyInfo *pKeyInfo;
+    int nField, nByte;
+
+    nField = ((KeyInfo*)zP4)->nField;
+    nByte = sizeof(*pKeyInfo) + (nField-1)*sizeof(pKeyInfo->aColl[0]) + nField;
+    pKeyInfo = sqlite3DbMallocRaw(0, nByte);
+    pOp->p4.pKeyInfo = pKeyInfo;
+    if( pKeyInfo ){
+      u8 *aSortOrder;
+      memcpy((char*)pKeyInfo, zP4, nByte - nField);
+      aSortOrder = pKeyInfo->aSortOrder;
+      if( aSortOrder ){
+        pKeyInfo->aSortOrder = (unsigned char*)&pKeyInfo->aColl[nField];
+        memcpy(pKeyInfo->aSortOrder, aSortOrder, nField);
+      }
+      pOp->p4type = P4_KEYINFO;
+    }else{
+      p->db->mallocFailed = 1;
+      pOp->p4type = P4_NOTUSED;
+    }
+  }else if( n==P4_KEYINFO_HANDOFF ){
+    pOp->p4.p = (void*)zP4;
+    pOp->p4type = P4_KEYINFO;
+  }else if( n==P4_VTAB ){
+    pOp->p4.p = (void*)zP4;
+    pOp->p4type = P4_VTAB;
+    sqlite3VtabLock((VTable *)zP4);
+    assert( ((VTable *)zP4)->db==p->db );
+  }else if( n<0 ){
+    pOp->p4.p = (void*)zP4;
+    pOp->p4type = (signed char)n;
+  }else{
+    if( n==0 ) n = sqlite3Strlen30(zP4);
+    pOp->p4.z = sqlite3DbStrNDup(p->db, zP4, n);
+    pOp->p4type = P4_DYNAMIC;
+  }
+}
+
+#ifndef NDEBUG
+/*
+** Change the comment on the the most recently coded instruction.  Or
+** insert a No-op and add the comment to that new instruction.  This
+** makes the code easier to read during debugging.  None of this happens
+** in a production build.
+*/
+SQLITE_PRIVATE void sqlite3VdbeComment(Vdbe *p, const char *zFormat, ...){
+  va_list ap;
+  if( !p ) return;
+  assert( p->nOp>0 || p->aOp==0 );
+  assert( p->aOp==0 || p->aOp[p->nOp-1].zComment==0 || p->db->mallocFailed );
+  if( p->nOp ){
+    char **pz = &p->aOp[p->nOp-1].zComment;
+    va_start(ap, zFormat);
+    sqlite3DbFree(p->db, *pz);
+    *pz = sqlite3VMPrintf(p->db, zFormat, ap);
+    va_end(ap);
+  }
+}
+SQLITE_PRIVATE void sqlite3VdbeNoopComment(Vdbe *p, const char *zFormat, ...){
+  va_list ap;
+  if( !p ) return;
+  sqlite3VdbeAddOp0(p, OP_Noop);
+  assert( p->nOp>0 || p->aOp==0 );
+  assert( p->aOp==0 || p->aOp[p->nOp-1].zComment==0 || p->db->mallocFailed );
+  if( p->nOp ){
+    char **pz = &p->aOp[p->nOp-1].zComment;
+    va_start(ap, zFormat);
+    sqlite3DbFree(p->db, *pz);
+    *pz = sqlite3VMPrintf(p->db, zFormat, ap);
+    va_end(ap);
+  }
+}
+#endif  /* NDEBUG */
+
+/*
+** Return the opcode for a given address.  If the address is -1, then
+** return the most recently inserted opcode.
+**
+** If a memory allocation error has occurred prior to the calling of this
+** routine, then a pointer to a dummy VdbeOp will be returned.  That opcode
+** is readable but not writable, though it is cast to a writable value.
+** The return of a dummy opcode allows the call to continue functioning
+** after a OOM fault without having to check to see if the return from 
+** this routine is a valid pointer.  But because the dummy.opcode is 0,
+** dummy will never be written to.  This is verified by code inspection and
+** by running with Valgrind.
+**
+** About the #ifdef SQLITE_OMIT_TRACE:  Normally, this routine is never called
+** unless p->nOp>0.  This is because in the absense of SQLITE_OMIT_TRACE,
+** an OP_Trace instruction is always inserted by sqlite3VdbeGet() as soon as
+** a new VDBE is created.  So we are free to set addr to p->nOp-1 without
+** having to double-check to make sure that the result is non-negative. But
+** if SQLITE_OMIT_TRACE is defined, the OP_Trace is omitted and we do need to
+** check the value of p->nOp-1 before continuing.
+*/
+SQLITE_PRIVATE VdbeOp *sqlite3VdbeGetOp(Vdbe *p, int addr){
+  /* C89 specifies that the constant "dummy" will be initialized to all
+  ** zeros, which is correct.  MSVC generates a warning, nevertheless. */
+  static const VdbeOp dummy;  /* Ignore the MSVC warning about no initializer */
+  assert( p->magic==VDBE_MAGIC_INIT );
+  if( addr<0 ){
+#ifdef SQLITE_OMIT_TRACE
+    if( p->nOp==0 ) return (VdbeOp*)&dummy;
+#endif
+    addr = p->nOp - 1;
+  }
+  assert( (addr>=0 && addr<p->nOp) || p->db->mallocFailed );
+  if( p->db->mallocFailed ){
+    return (VdbeOp*)&dummy;
+  }else{
+    return &p->aOp[addr];
+  }
+}
+
+#if !defined(SQLITE_OMIT_EXPLAIN) || !defined(NDEBUG) \
+     || defined(VDBE_PROFILE) || defined(SQLITE_DEBUG)
+/*
+** Compute a string that describes the P4 parameter for an opcode.
+** Use zTemp for any required temporary buffer space.
+*/
+static char *displayP4(Op *pOp, char *zTemp, int nTemp){
+  char *zP4 = zTemp;
+  assert( nTemp>=20 );
+  switch( pOp->p4type ){
+    case P4_KEYINFO_STATIC:
+    case P4_KEYINFO: {
+      int i, j;
+      KeyInfo *pKeyInfo = pOp->p4.pKeyInfo;
+      sqlite3_snprintf(nTemp, zTemp, "keyinfo(%d", pKeyInfo->nField);
+      i = sqlite3Strlen30(zTemp);
+      for(j=0; j<pKeyInfo->nField; j++){
+        CollSeq *pColl = pKeyInfo->aColl[j];
+        if( pColl ){
+          int n = sqlite3Strlen30(pColl->zName);
+          if( i+n>nTemp-6 ){
+            memcpy(&zTemp[i],",...",4);
+            break;
+          }
+          zTemp[i++] = ',';
+          if( pKeyInfo->aSortOrder && pKeyInfo->aSortOrder[j] ){
+            zTemp[i++] = '-';
+          }
+          memcpy(&zTemp[i], pColl->zName,n+1);
+          i += n;
+        }else if( i+4<nTemp-6 ){
+          memcpy(&zTemp[i],",nil",4);
+          i += 4;
+        }
+      }
+      zTemp[i++] = ')';
+      zTemp[i] = 0;
+      assert( i<nTemp );
+      break;
+    }
+    case P4_COLLSEQ: {
+      CollSeq *pColl = pOp->p4.pColl;
+      sqlite3_snprintf(nTemp, zTemp, "collseq(%.20s)", pColl->zName);
+      break;
+    }
+    case P4_FUNCDEF: {
+      FuncDef *pDef = pOp->p4.pFunc;
+      sqlite3_snprintf(nTemp, zTemp, "%s(%d)", pDef->zName, pDef->nArg);
+      break;
+    }
+    case P4_INT64: {
+      sqlite3_snprintf(nTemp, zTemp, "%lld", *pOp->p4.pI64);
+      break;
+    }
+    case P4_INT32: {
+      sqlite3_snprintf(nTemp, zTemp, "%d", pOp->p4.i);
+      break;
+    }
+    case P4_REAL: {
+      sqlite3_snprintf(nTemp, zTemp, "%.16g", *pOp->p4.pReal);
+      break;
+    }
+    case P4_MEM: {
+      Mem *pMem = pOp->p4.pMem;
+      assert( (pMem->flags & MEM_Null)==0 );
+      if( pMem->flags & MEM_Str ){
+        zP4 = pMem->z;
+      }else if( pMem->flags & MEM_Int ){
+        sqlite3_snprintf(nTemp, zTemp, "%lld", pMem->u.i);
+      }else if( pMem->flags & MEM_Real ){
+        sqlite3_snprintf(nTemp, zTemp, "%.16g", pMem->r);
+      }else{
+        assert( pMem->flags & MEM_Blob );
+        zP4 = "(blob)";
+      }
+      break;
+    }
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+    case P4_VTAB: {
+      sqlite3_vtab *pVtab = pOp->p4.pVtab->pVtab;
+      sqlite3_snprintf(nTemp, zTemp, "vtab:%p:%p", pVtab, pVtab->pModule);
+      break;
+    }
+#endif
+    case P4_INTARRAY: {
+      sqlite3_snprintf(nTemp, zTemp, "intarray");
+      break;
+    }
+    case P4_SUBPROGRAM: {
+      sqlite3_snprintf(nTemp, zTemp, "program");
+      break;
+    }
+    default: {
+      zP4 = pOp->p4.z;
+      if( zP4==0 ){
+        zP4 = zTemp;
+        zTemp[0] = 0;
+      }
+    }
+  }
+  assert( zP4!=0 );
+  return zP4;
+}
+#endif
+
+/*
+** Declare to the Vdbe that the BTree object at db->aDb[i] is used.
+**
+** The prepared statements need to know in advance the complete set of
+** attached databases that they will be using.  A mask of these databases
+** is maintained in p->btreeMask and is used for locking and other purposes.
+*/
+SQLITE_PRIVATE void sqlite3VdbeUsesBtree(Vdbe *p, int i){
+  assert( i>=0 && i<p->db->nDb && i<(int)sizeof(yDbMask)*8 );
+  assert( i<(int)sizeof(p->btreeMask)*8 );
+  p->btreeMask |= ((yDbMask)1)<<i;
+  if( i!=1 && sqlite3BtreeSharable(p->db->aDb[i].pBt) ){
+    p->lockMask |= ((yDbMask)1)<<i;
+  }
+}
+
+#if !defined(SQLITE_OMIT_SHARED_CACHE) && SQLITE_THREADSAFE>0
+/*
+** If SQLite is compiled to support shared-cache mode and to be threadsafe,
+** this routine obtains the mutex associated with each BtShared structure
+** that may be accessed by the VM passed as an argument. In doing so it also
+** sets the BtShared.db member of each of the BtShared structures, ensuring
+** that the correct busy-handler callback is invoked if required.
+**
+** If SQLite is not threadsafe but does support shared-cache mode, then
+** sqlite3BtreeEnter() is invoked to set the BtShared.db variables
+** of all of BtShared structures accessible via the database handle 
+** associated with the VM.
+**
+** If SQLite is not threadsafe and does not support shared-cache mode, this
+** function is a no-op.
+**
+** The p->btreeMask field is a bitmask of all btrees that the prepared 
+** statement p will ever use.  Let N be the number of bits in p->btreeMask
+** corresponding to btrees that use shared cache.  Then the runtime of
+** this routine is N*N.  But as N is rarely more than 1, this should not
+** be a problem.
+*/
+SQLITE_PRIVATE void sqlite3VdbeEnter(Vdbe *p){
+  int i;
+  yDbMask mask;
+  sqlite3 *db;
+  Db *aDb;
+  int nDb;
+  if( p->lockMask==0 ) return;  /* The common case */
+  db = p->db;
+  aDb = db->aDb;
+  nDb = db->nDb;
+  for(i=0, mask=1; i<nDb; i++, mask += mask){
+    if( i!=1 && (mask & p->lockMask)!=0 && ALWAYS(aDb[i].pBt!=0) ){
+      sqlite3BtreeEnter(aDb[i].pBt);
+    }
+  }
+}
+#endif
+
+#if !defined(SQLITE_OMIT_SHARED_CACHE) && SQLITE_THREADSAFE>0
+/*
+** Unlock all of the btrees previously locked by a call to sqlite3VdbeEnter().
+*/
+SQLITE_PRIVATE void sqlite3VdbeLeave(Vdbe *p){
+  int i;
+  yDbMask mask;
+  sqlite3 *db;
+  Db *aDb;
+  int nDb;
+  if( p->lockMask==0 ) return;  /* The common case */
+  db = p->db;
+  aDb = db->aDb;
+  nDb = db->nDb;
+  for(i=0, mask=1; i<nDb; i++, mask += mask){
+    if( i!=1 && (mask & p->lockMask)!=0 && ALWAYS(aDb[i].pBt!=0) ){
+      sqlite3BtreeLeave(aDb[i].pBt);
+    }
+  }
+}
+#endif
+
+#if defined(VDBE_PROFILE) || defined(SQLITE_DEBUG)
+/*
+** Print a single opcode.  This routine is used for debugging only.
+*/
+SQLITE_PRIVATE void sqlite3VdbePrintOp(FILE *pOut, int pc, Op *pOp){
+  char *zP4;
+  char zPtr[50];
+  static const char *zFormat1 = "%4d %-13s %4d %4d %4d %-4s %.2X %s\n";
+  if( pOut==0 ) pOut = stdout;
+  zP4 = displayP4(pOp, zPtr, sizeof(zPtr));
+  fprintf(pOut, zFormat1, pc, 
+      sqlite3OpcodeName(pOp->opcode), pOp->p1, pOp->p2, pOp->p3, zP4, pOp->p5,
+#ifdef SQLITE_DEBUG
+      pOp->zComment ? pOp->zComment : ""
+#else
+      ""
+#endif
+  );
+  fflush(pOut);
+}
+#endif
+
+/*
+** Release an array of N Mem elements
+*/
+static void releaseMemArray(Mem *p, int N){
+  if( p && N ){
+    Mem *pEnd;
+    sqlite3 *db = p->db;
+    u8 malloc_failed = db->mallocFailed;
+    if( db->pnBytesFreed ){
+      for(pEnd=&p[N]; p<pEnd; p++){
+        sqlite3DbFree(db, p->zMalloc);
+      }
+      return;
+    }
+    for(pEnd=&p[N]; p<pEnd; p++){
+      assert( (&p[1])==pEnd || p[0].db==p[1].db );
+
+      /* This block is really an inlined version of sqlite3VdbeMemRelease()
+      ** that takes advantage of the fact that the memory cell value is 
+      ** being set to NULL after releasing any dynamic resources.
+      **
+      ** The justification for duplicating code is that according to 
+      ** callgrind, this causes a certain test case to hit the CPU 4.7 
+      ** percent less (x86 linux, gcc version 4.1.2, -O6) than if 
+      ** sqlite3MemRelease() were called from here. With -O2, this jumps
+      ** to 6.6 percent. The test case is inserting 1000 rows into a table 
+      ** with no indexes using a single prepared INSERT statement, bind() 
+      ** and reset(). Inserts are grouped into a transaction.
+      */
+      if( p->flags&(MEM_Agg|MEM_Dyn|MEM_Frame|MEM_RowSet) ){
+        sqlite3VdbeMemRelease(p);
+      }else if( p->zMalloc ){
+        sqlite3DbFree(db, p->zMalloc);
+        p->zMalloc = 0;
+      }
+
+      p->flags = MEM_Null;
+    }
+    db->mallocFailed = malloc_failed;
+  }
+}
+
+/*
+** Delete a VdbeFrame object and its contents. VdbeFrame objects are
+** allocated by the OP_Program opcode in sqlite3VdbeExec().
+*/
+SQLITE_PRIVATE void sqlite3VdbeFrameDelete(VdbeFrame *p){
+  int i;
+  Mem *aMem = VdbeFrameMem(p);
+  VdbeCursor **apCsr = (VdbeCursor **)&aMem[p->nChildMem];
+  for(i=0; i<p->nChildCsr; i++){
+    sqlite3VdbeFreeCursor(p->v, apCsr[i]);
+  }
+  releaseMemArray(aMem, p->nChildMem);
+  sqlite3DbFree(p->v->db, p);
+}
+
+#ifndef SQLITE_OMIT_EXPLAIN
+/*
+** Give a listing of the program in the virtual machine.
+**
+** The interface is the same as sqlite3VdbeExec().  But instead of
+** running the code, it invokes the callback once for each instruction.
+** This feature is used to implement "EXPLAIN".
+**
+** When p->explain==1, each instruction is listed.  When
+** p->explain==2, only OP_Explain instructions are listed and these
+** are shown in a different format.  p->explain==2 is used to implement
+** EXPLAIN QUERY PLAN.
+**
+** When p->explain==1, first the main program is listed, then each of
+** the trigger subprograms are listed one by one.
+*/
+SQLITE_PRIVATE int sqlite3VdbeList(
+  Vdbe *p                   /* The VDBE */
+){
+  int nRow;                            /* Stop when row count reaches this */
+  int nSub = 0;                        /* Number of sub-vdbes seen so far */
+  SubProgram **apSub = 0;              /* Array of sub-vdbes */
+  Mem *pSub = 0;                       /* Memory cell hold array of subprogs */
+  sqlite3 *db = p->db;                 /* The database connection */
+  int i;                               /* Loop counter */
+  int rc = SQLITE_OK;                  /* Return code */
+  Mem *pMem = p->pResultSet = &p->aMem[1];  /* First Mem of result set */
+
+  assert( p->explain );
+  assert( p->magic==VDBE_MAGIC_RUN );
+  assert( p->rc==SQLITE_OK || p->rc==SQLITE_BUSY || p->rc==SQLITE_NOMEM );
+
+  /* Even though this opcode does not use dynamic strings for
+  ** the result, result columns may become dynamic if the user calls
+  ** sqlite3_column_text16(), causing a translation to UTF-16 encoding.
+  */
+  releaseMemArray(pMem, 8);
+
+  if( p->rc==SQLITE_NOMEM ){
+    /* This happens if a malloc() inside a call to sqlite3_column_text() or
+    ** sqlite3_column_text16() failed.  */
+    db->mallocFailed = 1;
+    return SQLITE_ERROR;
+  }
+
+  /* When the number of output rows reaches nRow, that means the
+  ** listing has finished and sqlite3_step() should return SQLITE_DONE.
+  ** nRow is the sum of the number of rows in the main program, plus
+  ** the sum of the number of rows in all trigger subprograms encountered
+  ** so far.  The nRow value will increase as new trigger subprograms are
+  ** encountered, but p->pc will eventually catch up to nRow.
+  */
+  nRow = p->nOp;
+  if( p->explain==1 ){
+    /* The first 8 memory cells are used for the result set.  So we will
+    ** commandeer the 9th cell to use as storage for an array of pointers
+    ** to trigger subprograms.  The VDBE is guaranteed to have at least 9
+    ** cells.  */
+    assert( p->nMem>9 );
+    pSub = &p->aMem[9];
+    if( pSub->flags&MEM_Blob ){
+      /* On the first call to sqlite3_step(), pSub will hold a NULL.  It is
+      ** initialized to a BLOB by the P4_SUBPROGRAM processing logic below */
+      nSub = pSub->n/sizeof(Vdbe*);
+      apSub = (SubProgram **)pSub->z;
+    }
+    for(i=0; i<nSub; i++){
+      nRow += apSub[i]->nOp;
+    }
+  }
+
+  do{
+    i = p->pc++;
+  }while( i<nRow && p->explain==2 && p->aOp[i].opcode!=OP_Explain );
+  if( i>=nRow ){
+    p->rc = SQLITE_OK;
+    rc = SQLITE_DONE;
+  }else if( db->u1.isInterrupted ){
+    p->rc = SQLITE_INTERRUPT;
+    rc = SQLITE_ERROR;
+    sqlite3SetString(&p->zErrMsg, db, "%s", sqlite3ErrStr(p->rc));
+  }else{
+    char *z;
+    Op *pOp;
+    if( i<p->nOp ){
+      /* The output line number is small enough that we are still in the
+      ** main program. */
+      pOp = &p->aOp[i];
+    }else{
+      /* We are currently listing subprograms.  Figure out which one and
+      ** pick up the appropriate opcode. */
+      int j;
+      i -= p->nOp;
+      for(j=0; i>=apSub[j]->nOp; j++){
+        i -= apSub[j]->nOp;
+      }
+      pOp = &apSub[j]->aOp[i];
+    }
+    if( p->explain==1 ){
+      pMem->flags = MEM_Int;
+      pMem->type = SQLITE_INTEGER;
+      pMem->u.i = i;                                /* Program counter */
+      pMem++;
+  
+      pMem->flags = MEM_Static|MEM_Str|MEM_Term;
+      pMem->z = (char*)sqlite3OpcodeName(pOp->opcode);  /* Opcode */
+      assert( pMem->z!=0 );
+      pMem->n = sqlite3Strlen30(pMem->z);
+      pMem->type = SQLITE_TEXT;
+      pMem->enc = SQLITE_UTF8;
+      pMem++;
+
+      /* When an OP_Program opcode is encounter (the only opcode that has
+      ** a P4_SUBPROGRAM argument), expand the size of the array of subprograms
+      ** kept in p->aMem[9].z to hold the new program - assuming this subprogram
+      ** has not already been seen.
+      */
+      if( pOp->p4type==P4_SUBPROGRAM ){
+        int nByte = (nSub+1)*sizeof(SubProgram*);
+        int j;
+        for(j=0; j<nSub; j++){
+          if( apSub[j]==pOp->p4.pProgram ) break;
+        }
+        if( j==nSub && SQLITE_OK==sqlite3VdbeMemGrow(pSub, nByte, 1) ){
+          apSub = (SubProgram **)pSub->z;
+          apSub[nSub++] = pOp->p4.pProgram;
+          pSub->flags |= MEM_Blob;
+          pSub->n = nSub*sizeof(SubProgram*);
+        }
+      }
+    }
+
+    pMem->flags = MEM_Int;
+    pMem->u.i = pOp->p1;                          /* P1 */
+    pMem->type = SQLITE_INTEGER;
+    pMem++;
+
+    pMem->flags = MEM_Int;
+    pMem->u.i = pOp->p2;                          /* P2 */
+    pMem->type = SQLITE_INTEGER;
+    pMem++;
+
+    pMem->flags = MEM_Int;
+    pMem->u.i = pOp->p3;                          /* P3 */
+    pMem->type = SQLITE_INTEGER;
+    pMem++;
+
+    if( sqlite3VdbeMemGrow(pMem, 32, 0) ){            /* P4 */
+      assert( p->db->mallocFailed );
+      return SQLITE_ERROR;
+    }
+    pMem->flags = MEM_Dyn|MEM_Str|MEM_Term;
+    z = displayP4(pOp, pMem->z, 32);
+    if( z!=pMem->z ){
+      sqlite3VdbeMemSetStr(pMem, z, -1, SQLITE_UTF8, 0);
+    }else{
+      assert( pMem->z!=0 );
+      pMem->n = sqlite3Strlen30(pMem->z);
+      pMem->enc = SQLITE_UTF8;
+    }
+    pMem->type = SQLITE_TEXT;
+    pMem++;
+
+    if( p->explain==1 ){
+      if( sqlite3VdbeMemGrow(pMem, 4, 0) ){
+        assert( p->db->mallocFailed );
+        return SQLITE_ERROR;
+      }
+      pMem->flags = MEM_Dyn|MEM_Str|MEM_Term;
+      pMem->n = 2;
+      sqlite3_snprintf(3, pMem->z, "%.2x", pOp->p5);   /* P5 */
+      pMem->type = SQLITE_TEXT;
+      pMem->enc = SQLITE_UTF8;
+      pMem++;
+  
+#ifdef SQLITE_DEBUG
+      if( pOp->zComment ){
+        pMem->flags = MEM_Str|MEM_Term;
+        pMem->z = pOp->zComment;
+        pMem->n = sqlite3Strlen30(pMem->z);
+        pMem->enc = SQLITE_UTF8;
+        pMem->type = SQLITE_TEXT;
+      }else
+#endif
+      {
+        pMem->flags = MEM_Null;                       /* Comment */
+        pMem->type = SQLITE_NULL;
+      }
+    }
+
+    p->nResColumn = 8 - 4*(p->explain-1);
+    p->rc = SQLITE_OK;
+    rc = SQLITE_ROW;
+  }
+  return rc;
+}
+#endif /* SQLITE_OMIT_EXPLAIN */
+
+#ifdef SQLITE_DEBUG
+/*
+** Print the SQL that was used to generate a VDBE program.
+*/
+SQLITE_PRIVATE void sqlite3VdbePrintSql(Vdbe *p){
+  int nOp = p->nOp;
+  VdbeOp *pOp;
+  if( nOp<1 ) return;
+  pOp = &p->aOp[0];
+  if( pOp->opcode==OP_Trace && pOp->p4.z!=0 ){
+    const char *z = pOp->p4.z;
+    while( sqlite3Isspace(*z) ) z++;
+    printf("SQL: [%s]\n", z);
+  }
+}
+#endif
+
+#if !defined(SQLITE_OMIT_TRACE) && defined(SQLITE_ENABLE_IOTRACE)
+/*
+** Print an IOTRACE message showing SQL content.
+*/
+SQLITE_PRIVATE void sqlite3VdbeIOTraceSql(Vdbe *p){
+  int nOp = p->nOp;
+  VdbeOp *pOp;
+  if( sqlite3IoTrace==0 ) return;
+  if( nOp<1 ) return;
+  pOp = &p->aOp[0];
+  if( pOp->opcode==OP_Trace && pOp->p4.z!=0 ){
+    int i, j;
+    char z[1000];
+    sqlite3_snprintf(sizeof(z), z, "%s", pOp->p4.z);
+    for(i=0; sqlite3Isspace(z[i]); i++){}
+    for(j=0; z[i]; i++){
+      if( sqlite3Isspace(z[i]) ){
+        if( z[i-1]!=' ' ){
+          z[j++] = ' ';
+        }
+      }else{
+        z[j++] = z[i];
+      }
+    }
+    z[j] = 0;
+    sqlite3IoTrace("SQL %s\n", z);
+  }
+}
+#endif /* !SQLITE_OMIT_TRACE && SQLITE_ENABLE_IOTRACE */
+
+/*
+** Allocate space from a fixed size buffer and return a pointer to
+** that space.  If insufficient space is available, return NULL.
+**
+** The pBuf parameter is the initial value of a pointer which will
+** receive the new memory.  pBuf is normally NULL.  If pBuf is not
+** NULL, it means that memory space has already been allocated and that
+** this routine should not allocate any new memory.  When pBuf is not
+** NULL simply return pBuf.  Only allocate new memory space when pBuf
+** is NULL.
+**
+** nByte is the number of bytes of space needed.
+**
+** *ppFrom points to available space and pEnd points to the end of the
+** available space.  When space is allocated, *ppFrom is advanced past
+** the end of the allocated space.
+**
+** *pnByte is a counter of the number of bytes of space that have failed
+** to allocate.  If there is insufficient space in *ppFrom to satisfy the
+** request, then increment *pnByte by the amount of the request.
+*/
+static void *allocSpace(
+  void *pBuf,          /* Where return pointer will be stored */
+  int nByte,           /* Number of bytes to allocate */
+  u8 **ppFrom,         /* IN/OUT: Allocate from *ppFrom */
+  u8 *pEnd,            /* Pointer to 1 byte past the end of *ppFrom buffer */
+  int *pnByte          /* If allocation cannot be made, increment *pnByte */
+){
+  assert( EIGHT_BYTE_ALIGNMENT(*ppFrom) );
+  if( pBuf ) return pBuf;
+  nByte = ROUND8(nByte);
+  if( &(*ppFrom)[nByte] <= pEnd ){
+    pBuf = (void*)*ppFrom;
+    *ppFrom += nByte;
+  }else{
+    *pnByte += nByte;
+  }
+  return pBuf;
+}
+
+/*
+** Prepare a virtual machine for execution.  This involves things such
+** as allocating stack space and initializing the program counter.
+** After the VDBE has be prepped, it can be executed by one or more
+** calls to sqlite3VdbeExec().  
+**
+** This is the only way to move a VDBE from VDBE_MAGIC_INIT to
+** VDBE_MAGIC_RUN.
+**
+** This function may be called more than once on a single virtual machine.
+** The first call is made while compiling the SQL statement. Subsequent
+** calls are made as part of the process of resetting a statement to be
+** re-executed (from a call to sqlite3_reset()). The nVar, nMem, nCursor 
+** and isExplain parameters are only passed correct values the first time
+** the function is called. On subsequent calls, from sqlite3_reset(), nVar
+** is passed -1 and nMem, nCursor and isExplain are all passed zero.
+*/
+SQLITE_PRIVATE void sqlite3VdbeMakeReady(
+  Vdbe *p,                       /* The VDBE */
+  int nVar,                      /* Number of '?' see in the SQL statement */
+  int nMem,                      /* Number of memory cells to allocate */
+  int nCursor,                   /* Number of cursors to allocate */
+  int nArg,                      /* Maximum number of args in SubPrograms */
+  int isExplain,                 /* True if the EXPLAIN keywords is present */
+  int usesStmtJournal            /* True to set Vdbe.usesStmtJournal */
+){
+  int n;
+  sqlite3 *db = p->db;
+
+  assert( p!=0 );
+  assert( p->magic==VDBE_MAGIC_INIT );
+
+  /* There should be at least one opcode.
+  */
+  assert( p->nOp>0 );
+
+  /* Set the magic to VDBE_MAGIC_RUN sooner rather than later. */
+  p->magic = VDBE_MAGIC_RUN;
+
+  /* For each cursor required, also allocate a memory cell. Memory
+  ** cells (nMem+1-nCursor)..nMem, inclusive, will never be used by
+  ** the vdbe program. Instead they are used to allocate space for
+  ** VdbeCursor/BtCursor structures. The blob of memory associated with 
+  ** cursor 0 is stored in memory cell nMem. Memory cell (nMem-1)
+  ** stores the blob of memory associated with cursor 1, etc.
+  **
+  ** See also: allocateCursor().
+  */
+  nMem += nCursor;
+
+  /* Allocate space for memory registers, SQL variables, VDBE cursors and 
+  ** an array to marshal SQL function arguments in. This is only done the
+  ** first time this function is called for a given VDBE, not when it is
+  ** being called from sqlite3_reset() to reset the virtual machine.
+  */
+  if( nVar>=0 && ALWAYS(db->mallocFailed==0) ){
+    u8 *zCsr = (u8 *)&p->aOp[p->nOp];       /* Memory avaliable for alloation */
+    u8 *zEnd = (u8 *)&p->aOp[p->nOpAlloc];  /* First byte past available mem */
+    int nByte;                              /* How much extra memory needed */
+
+    resolveP2Values(p, &nArg);
+    p->usesStmtJournal = (u8)usesStmtJournal;
+    if( isExplain && nMem<10 ){
+      nMem = 10;
+    }
+    memset(zCsr, 0, zEnd-zCsr);
+    zCsr += (zCsr - (u8*)0)&7;
+    assert( EIGHT_BYTE_ALIGNMENT(zCsr) );
+
+    /* Memory for registers, parameters, cursor, etc, is allocated in two
+    ** passes.  On the first pass, we try to reuse unused space at the 
+    ** end of the opcode array.  If we are unable to satisfy all memory
+    ** requirements by reusing the opcode array tail, then the second
+    ** pass will fill in the rest using a fresh allocation.  
+    **
+    ** This two-pass approach that reuses as much memory as possible from
+    ** the leftover space at the end of the opcode array can significantly
+    ** reduce the amount of memory held by a prepared statement.
+    */
+    do {
+      nByte = 0;
+      p->aMem = allocSpace(p->aMem, nMem*sizeof(Mem), &zCsr, zEnd, &nByte);
+      p->aVar = allocSpace(p->aVar, nVar*sizeof(Mem), &zCsr, zEnd, &nByte);
+      p->apArg = allocSpace(p->apArg, nArg*sizeof(Mem*), &zCsr, zEnd, &nByte);
+      p->azVar = allocSpace(p->azVar, nVar*sizeof(char*), &zCsr, zEnd, &nByte);
+      p->apCsr = allocSpace(p->apCsr, nCursor*sizeof(VdbeCursor*),
+                            &zCsr, zEnd, &nByte);
+      if( nByte ){
+        p->pFree = sqlite3DbMallocZero(db, nByte);
+      }
+      zCsr = p->pFree;
+      zEnd = &zCsr[nByte];
+    }while( nByte && !db->mallocFailed );
+
+    p->nCursor = (u16)nCursor;
+    if( p->aVar ){
+      p->nVar = (ynVar)nVar;
+      for(n=0; n<nVar; n++){
+        p->aVar[n].flags = MEM_Null;
+        p->aVar[n].db = db;
+      }
+    }
+    if( p->aMem ){
+      p->aMem--;                      /* aMem[] goes from 1..nMem */
+      p->nMem = nMem;                 /*       not from 0..nMem-1 */
+      for(n=1; n<=nMem; n++){
+        p->aMem[n].flags = MEM_Null;
+        p->aMem[n].db = db;
+      }
+    }
+  }
+#ifdef SQLITE_DEBUG
+  for(n=1; n<p->nMem; n++){
+    assert( p->aMem[n].db==db );
+  }
+#endif
+
+  p->pc = -1;
+  p->rc = SQLITE_OK;
+  p->errorAction = OE_Abort;
+  p->explain |= isExplain;
+  p->magic = VDBE_MAGIC_RUN;
+  p->nChange = 0;
+  p->cacheCtr = 1;
+  p->minWriteFileFormat = 255;
+  p->iStatement = 0;
+  p->nFkConstraint = 0;
+#ifdef VDBE_PROFILE
+  {
+    int i;
+    for(i=0; i<p->nOp; i++){
+      p->aOp[i].cnt = 0;
+      p->aOp[i].cycles = 0;
+    }
+  }
+#endif
+}
+
+/*
+** Close a VDBE cursor and release all the resources that cursor 
+** happens to hold.
+*/
+SQLITE_PRIVATE void sqlite3VdbeFreeCursor(Vdbe *p, VdbeCursor *pCx){
+  if( pCx==0 ){
+    return;
+  }
+  if( pCx->pBt ){
+    sqlite3BtreeClose(pCx->pBt);
+    /* The pCx->pCursor will be close automatically, if it exists, by
+    ** the call above. */
+  }else if( pCx->pCursor ){
+    sqlite3BtreeCloseCursor(pCx->pCursor);
+  }
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  if( pCx->pVtabCursor ){
+    sqlite3_vtab_cursor *pVtabCursor = pCx->pVtabCursor;
+    const sqlite3_module *pModule = pCx->pModule;
+    p->inVtabMethod = 1;
+    pModule->xClose(pVtabCursor);
+    p->inVtabMethod = 0;
+  }
+#endif
+}
+
+/*
+** Copy the values stored in the VdbeFrame structure to its Vdbe. This
+** is used, for example, when a trigger sub-program is halted to restore
+** control to the main program.
+*/
+SQLITE_PRIVATE int sqlite3VdbeFrameRestore(VdbeFrame *pFrame){
+  Vdbe *v = pFrame->v;
+  v->aOp = pFrame->aOp;
+  v->nOp = pFrame->nOp;
+  v->aMem = pFrame->aMem;
+  v->nMem = pFrame->nMem;
+  v->apCsr = pFrame->apCsr;
+  v->nCursor = pFrame->nCursor;
+  v->db->lastRowid = pFrame->lastRowid;
+  v->nChange = pFrame->nChange;
+  return pFrame->pc;
+}
+
+/*
+** Close all cursors.
+**
+** Also release any dynamic memory held by the VM in the Vdbe.aMem memory 
+** cell array. This is necessary as the memory cell array may contain
+** pointers to VdbeFrame objects, which may in turn contain pointers to
+** open cursors.
+*/
+static void closeAllCursors(Vdbe *p){
+  if( p->pFrame ){
+    VdbeFrame *pFrame;
+    for(pFrame=p->pFrame; pFrame->pParent; pFrame=pFrame->pParent);
+    sqlite3VdbeFrameRestore(pFrame);
+  }
+  p->pFrame = 0;
+  p->nFrame = 0;
+
+  if( p->apCsr ){
+    int i;
+    for(i=0; i<p->nCursor; i++){
+      VdbeCursor *pC = p->apCsr[i];
+      if( pC ){
+        sqlite3VdbeFreeCursor(p, pC);
+        p->apCsr[i] = 0;
+      }
+    }
+  }
+  if( p->aMem ){
+    releaseMemArray(&p->aMem[1], p->nMem);
+  }
+  while( p->pDelFrame ){
+    VdbeFrame *pDel = p->pDelFrame;
+    p->pDelFrame = pDel->pParent;
+    sqlite3VdbeFrameDelete(pDel);
+  }
+}
+
+/*
+** Clean up the VM after execution.
+**
+** This routine will automatically close any cursors, lists, and/or
+** sorters that were left open.  It also deletes the values of
+** variables in the aVar[] array.
+*/
+static void Cleanup(Vdbe *p){
+  sqlite3 *db = p->db;
+
+#ifdef SQLITE_DEBUG
+  /* Execute assert() statements to ensure that the Vdbe.apCsr[] and 
+  ** Vdbe.aMem[] arrays have already been cleaned up.  */
+  int i;
+  for(i=0; i<p->nCursor; i++) assert( p->apCsr==0 || p->apCsr[i]==0 );
+  for(i=1; i<=p->nMem; i++) assert( p->aMem==0 || p->aMem[i].flags==MEM_Null );
+#endif
+
+  sqlite3DbFree(db, p->zErrMsg);
+  p->zErrMsg = 0;
+  p->pResultSet = 0;
+}
+
+/*
+** Set the number of result columns that will be returned by this SQL
+** statement. This is now set at compile time, rather than during
+** execution of the vdbe program so that sqlite3_column_count() can
+** be called on an SQL statement before sqlite3_step().
+*/
+SQLITE_PRIVATE void sqlite3VdbeSetNumCols(Vdbe *p, int nResColumn){
+  Mem *pColName;
+  int n;
+  sqlite3 *db = p->db;
+
+  releaseMemArray(p->aColName, p->nResColumn*COLNAME_N);
+  sqlite3DbFree(db, p->aColName);
+  n = nResColumn*COLNAME_N;
+  p->nResColumn = (u16)nResColumn;
+  p->aColName = pColName = (Mem*)sqlite3DbMallocZero(db, sizeof(Mem)*n );
+  if( p->aColName==0 ) return;
+  while( n-- > 0 ){
+    pColName->flags = MEM_Null;
+    pColName->db = p->db;
+    pColName++;
+  }
+}
+
+/*
+** Set the name of the idx'th column to be returned by the SQL statement.
+** zName must be a pointer to a nul terminated string.
+**
+** This call must be made after a call to sqlite3VdbeSetNumCols().
+**
+** The final parameter, xDel, must be one of SQLITE_DYNAMIC, SQLITE_STATIC
+** or SQLITE_TRANSIENT. If it is SQLITE_DYNAMIC, then the buffer pointed
+** to by zName will be freed by sqlite3DbFree() when the vdbe is destroyed.
+*/
+SQLITE_PRIVATE int sqlite3VdbeSetColName(
+  Vdbe *p,                         /* Vdbe being configured */
+  int idx,                         /* Index of column zName applies to */
+  int var,                         /* One of the COLNAME_* constants */
+  const char *zName,               /* Pointer to buffer containing name */
+  void (*xDel)(void*)              /* Memory management strategy for zName */
+){
+  int rc;
+  Mem *pColName;
+  assert( idx<p->nResColumn );
+  assert( var<COLNAME_N );
+  if( p->db->mallocFailed ){
+    assert( !zName || xDel!=SQLITE_DYNAMIC );
+    return SQLITE_NOMEM;
+  }
+  assert( p->aColName!=0 );
+  pColName = &(p->aColName[idx+var*p->nResColumn]);
+  rc = sqlite3VdbeMemSetStr(pColName, zName, -1, SQLITE_UTF8, xDel);
+  assert( rc!=0 || !zName || (pColName->flags&MEM_Term)!=0 );
+  return rc;
+}
+
+/*
+** A read or write transaction may or may not be active on database handle
+** db. If a transaction is active, commit it. If there is a
+** write-transaction spanning more than one database file, this routine
+** takes care of the master journal trickery.
+*/
+static int vdbeCommit(sqlite3 *db, Vdbe *p){
+  int i;
+  int nTrans = 0;  /* Number of databases with an active write-transaction */
+  int rc = SQLITE_OK;
+  int needXcommit = 0;
+
+#ifdef SQLITE_OMIT_VIRTUALTABLE
+  /* With this option, sqlite3VtabSync() is defined to be simply 
+  ** SQLITE_OK so p is not used. 
+  */
+  UNUSED_PARAMETER(p);
+#endif
+
+  /* Before doing anything else, call the xSync() callback for any
+  ** virtual module tables written in this transaction. This has to
+  ** be done before determining whether a master journal file is 
+  ** required, as an xSync() callback may add an attached database
+  ** to the transaction.
+  */
+  rc = sqlite3VtabSync(db, &p->zErrMsg);
+
+  /* This loop determines (a) if the commit hook should be invoked and
+  ** (b) how many database files have open write transactions, not 
+  ** including the temp database. (b) is important because if more than 
+  ** one database file has an open write transaction, a master journal
+  ** file is required for an atomic commit.
+  */ 
+  for(i=0; rc==SQLITE_OK && i<db->nDb; i++){ 
+    Btree *pBt = db->aDb[i].pBt;
+    if( sqlite3BtreeIsInTrans(pBt) ){
+      needXcommit = 1;
+      if( i!=1 ) nTrans++;
+      rc = sqlite3PagerExclusiveLock(sqlite3BtreePager(pBt));
+    }
+  }
+  if( rc!=SQLITE_OK ){
+    return rc;
+  }
+
+  /* If there are any write-transactions at all, invoke the commit hook */
+  if( needXcommit && db->xCommitCallback ){
+    rc = db->xCommitCallback(db->pCommitArg);
+    if( rc ){
+      return SQLITE_CONSTRAINT;
+    }
+  }
+
+  /* The simple case - no more than one database file (not counting the
+  ** TEMP database) has a transaction active.   There is no need for the
+  ** master-journal.
+  **
+  ** If the return value of sqlite3BtreeGetFilename() is a zero length
+  ** string, it means the main database is :memory: or a temp file.  In 
+  ** that case we do not support atomic multi-file commits, so use the 
+  ** simple case then too.
+  */
+  if( 0==sqlite3Strlen30(sqlite3BtreeGetFilename(db->aDb[0].pBt))
+   || nTrans<=1
+  ){
+    for(i=0; rc==SQLITE_OK && i<db->nDb; i++){
+      Btree *pBt = db->aDb[i].pBt;
+      if( pBt ){
+        rc = sqlite3BtreeCommitPhaseOne(pBt, 0);
+      }
+    }
+
+    /* Do the commit only if all databases successfully complete phase 1. 
+    ** If one of the BtreeCommitPhaseOne() calls fails, this indicates an
+    ** IO error while deleting or truncating a journal file. It is unlikely,
+    ** but could happen. In this case abandon processing and return the error.
+    */
+    for(i=0; rc==SQLITE_OK && i<db->nDb; i++){
+      Btree *pBt = db->aDb[i].pBt;
+      if( pBt ){
+        rc = sqlite3BtreeCommitPhaseTwo(pBt, 0);
+      }
+    }
+    if( rc==SQLITE_OK ){
+      sqlite3VtabCommit(db);
+    }
+  }
+
+  /* The complex case - There is a multi-file write-transaction active.
+  ** This requires a master journal file to ensure the transaction is
+  ** committed atomicly.
+  */
+#ifndef SQLITE_OMIT_DISKIO
+  else{
+    sqlite3_vfs *pVfs = db->pVfs;
+    int needSync = 0;
+    char *zMaster = 0;   /* File-name for the master journal */
+    char const *zMainFile = sqlite3BtreeGetFilename(db->aDb[0].pBt);
+    sqlite3_file *pMaster = 0;
+    i64 offset = 0;
+    int res;
+
+    /* Select a master journal file name */
+    do {
+      u32 iRandom;
+      sqlite3DbFree(db, zMaster);
+      sqlite3_randomness(sizeof(iRandom), &iRandom);
+      zMaster = sqlite3MPrintf(db, "%s-mj%08X", zMainFile, iRandom&0x7fffffff);
+      if( !zMaster ){
+        return SQLITE_NOMEM;
+      }
+      rc = sqlite3OsAccess(pVfs, zMaster, SQLITE_ACCESS_EXISTS, &res);
+    }while( rc==SQLITE_OK && res );
+    if( rc==SQLITE_OK ){
+      /* Open the master journal. */
+      rc = sqlite3OsOpenMalloc(pVfs, zMaster, &pMaster, 
+          SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE|
+          SQLITE_OPEN_EXCLUSIVE|SQLITE_OPEN_MASTER_JOURNAL, 0
+      );
+    }
+    if( rc!=SQLITE_OK ){
+      sqlite3DbFree(db, zMaster);
+      return rc;
+    }
+ 
+    /* Write the name of each database file in the transaction into the new
+    ** master journal file. If an error occurs at this point close
+    ** and delete the master journal file. All the individual journal files
+    ** still have 'null' as the master journal pointer, so they will roll
+    ** back independently if a failure occurs.
+    */
+    for(i=0; i<db->nDb; i++){
+      Btree *pBt = db->aDb[i].pBt;
+      if( sqlite3BtreeIsInTrans(pBt) ){
+        char const *zFile = sqlite3BtreeGetJournalname(pBt);
+        if( zFile==0 ){
+          continue;  /* Ignore TEMP and :memory: databases */
+        }
+        assert( zFile[0]!=0 );
+        if( !needSync && !sqlite3BtreeSyncDisabled(pBt) ){
+          needSync = 1;
+        }
+        rc = sqlite3OsWrite(pMaster, zFile, sqlite3Strlen30(zFile)+1, offset);
+        offset += sqlite3Strlen30(zFile)+1;
+        if( rc!=SQLITE_OK ){
+          sqlite3OsCloseFree(pMaster);
+          sqlite3OsDelete(pVfs, zMaster, 0);
+          sqlite3DbFree(db, zMaster);
+          return rc;
+        }
+      }
+    }
+
+    /* Sync the master journal file. If the IOCAP_SEQUENTIAL device
+    ** flag is set this is not required.
+    */
+    if( needSync 
+     && 0==(sqlite3OsDeviceCharacteristics(pMaster)&SQLITE_IOCAP_SEQUENTIAL)
+     && SQLITE_OK!=(rc = sqlite3OsSync(pMaster, SQLITE_SYNC_NORMAL))
+    ){
+      sqlite3OsCloseFree(pMaster);
+      sqlite3OsDelete(pVfs, zMaster, 0);
+      sqlite3DbFree(db, zMaster);
+      return rc;
+    }
+
+    /* Sync all the db files involved in the transaction. The same call
+    ** sets the master journal pointer in each individual journal. If
+    ** an error occurs here, do not delete the master journal file.
+    **
+    ** If the error occurs during the first call to
+    ** sqlite3BtreeCommitPhaseOne(), then there is a chance that the
+    ** master journal file will be orphaned. But we cannot delete it,
+    ** in case the master journal file name was written into the journal
+    ** file before the failure occurred.
+    */
+    for(i=0; rc==SQLITE_OK && i<db->nDb; i++){ 
+      Btree *pBt = db->aDb[i].pBt;
+      if( pBt ){
+        rc = sqlite3BtreeCommitPhaseOne(pBt, zMaster);
+      }
+    }
+    sqlite3OsCloseFree(pMaster);
+    assert( rc!=SQLITE_BUSY );
+    if( rc!=SQLITE_OK ){
+      sqlite3DbFree(db, zMaster);
+      return rc;
+    }
+
+    /* Delete the master journal file. This commits the transaction. After
+    ** doing this the directory is synced again before any individual
+    ** transaction files are deleted.
+    */
+    rc = sqlite3OsDelete(pVfs, zMaster, 1);
+    sqlite3DbFree(db, zMaster);
+    zMaster = 0;
+    if( rc ){
+      return rc;
+    }
+
+    /* All files and directories have already been synced, so the following
+    ** calls to sqlite3BtreeCommitPhaseTwo() are only closing files and
+    ** deleting or truncating journals. If something goes wrong while
+    ** this is happening we don't really care. The integrity of the
+    ** transaction is already guaranteed, but some stray 'cold' journals
+    ** may be lying around. Returning an error code won't help matters.
+    */
+    disable_simulated_io_errors();
+    sqlite3BeginBenignMalloc();
+    for(i=0; i<db->nDb; i++){ 
+      Btree *pBt = db->aDb[i].pBt;
+      if( pBt ){
+        sqlite3BtreeCommitPhaseTwo(pBt, 1);
+      }
+    }
+    sqlite3EndBenignMalloc();
+    enable_simulated_io_errors();
+
+    sqlite3VtabCommit(db);
+  }
+#endif
+
+  return rc;
+}
+
+/* 
+** This routine checks that the sqlite3.activeVdbeCnt count variable
+** matches the number of vdbe's in the list sqlite3.pVdbe that are
+** currently active. An assertion fails if the two counts do not match.
+** This is an internal self-check only - it is not an essential processing
+** step.
+**
+** This is a no-op if NDEBUG is defined.
+*/
+#ifndef NDEBUG
+static void checkActiveVdbeCnt(sqlite3 *db){
+  Vdbe *p;
+  int cnt = 0;
+  int nWrite = 0;
+  p = db->pVdbe;
+  while( p ){
+    if( p->magic==VDBE_MAGIC_RUN && p->pc>=0 ){
+      cnt++;
+      if( p->readOnly==0 ) nWrite++;
+    }
+    p = p->pNext;
+  }
+  assert( cnt==db->activeVdbeCnt );
+  assert( nWrite==db->writeVdbeCnt );
+}
+#else
+#define checkActiveVdbeCnt(x)
+#endif
+
+/*
+** For every Btree that in database connection db which 
+** has been modified, "trip" or invalidate each cursor in
+** that Btree might have been modified so that the cursor
+** can never be used again.  This happens when a rollback
+*** occurs.  We have to trip all the other cursors, even
+** cursor from other VMs in different database connections,
+** so that none of them try to use the data at which they
+** were pointing and which now may have been changed due
+** to the rollback.
+**
+** Remember that a rollback can delete tables complete and
+** reorder rootpages.  So it is not sufficient just to save
+** the state of the cursor.  We have to invalidate the cursor
+** so that it is never used again.
+*/
+static void invalidateCursorsOnModifiedBtrees(sqlite3 *db){
+  int i;
+  for(i=0; i<db->nDb; i++){
+    Btree *p = db->aDb[i].pBt;
+    if( p && sqlite3BtreeIsInTrans(p) ){
+      sqlite3BtreeTripAllCursors(p, SQLITE_ABORT);
+    }
+  }
+}
+
+/*
+** If the Vdbe passed as the first argument opened a statement-transaction,
+** close it now. Argument eOp must be either SAVEPOINT_ROLLBACK or
+** SAVEPOINT_RELEASE. If it is SAVEPOINT_ROLLBACK, then the statement
+** transaction is rolled back. If eOp is SAVEPOINT_RELEASE, then the 
+** statement transaction is commtted.
+**
+** If an IO error occurs, an SQLITE_IOERR_XXX error code is returned. 
+** Otherwise SQLITE_OK.
+*/
+SQLITE_PRIVATE int sqlite3VdbeCloseStatement(Vdbe *p, int eOp){
+  sqlite3 *const db = p->db;
+  int rc = SQLITE_OK;
+
+  /* If p->iStatement is greater than zero, then this Vdbe opened a 
+  ** statement transaction that should be closed here. The only exception
+  ** is that an IO error may have occured, causing an emergency rollback.
+  ** In this case (db->nStatement==0), and there is nothing to do.
+  */
+  if( db->nStatement && p->iStatement ){
+    int i;
+    const int iSavepoint = p->iStatement-1;
+
+    assert( eOp==SAVEPOINT_ROLLBACK || eOp==SAVEPOINT_RELEASE);
+    assert( db->nStatement>0 );
+    assert( p->iStatement==(db->nStatement+db->nSavepoint) );
+
+    for(i=0; i<db->nDb; i++){ 
+      int rc2 = SQLITE_OK;
+      Btree *pBt = db->aDb[i].pBt;
+      if( pBt ){
+        if( eOp==SAVEPOINT_ROLLBACK ){
+          rc2 = sqlite3BtreeSavepoint(pBt, SAVEPOINT_ROLLBACK, iSavepoint);
+        }
+        if( rc2==SQLITE_OK ){
+          rc2 = sqlite3BtreeSavepoint(pBt, SAVEPOINT_RELEASE, iSavepoint);
+        }
+        if( rc==SQLITE_OK ){
+          rc = rc2;
+        }
+      }
+    }
+    db->nStatement--;
+    p->iStatement = 0;
+
+    /* If the statement transaction is being rolled back, also restore the 
+    ** database handles deferred constraint counter to the value it had when 
+    ** the statement transaction was opened.  */
+    if( eOp==SAVEPOINT_ROLLBACK ){
+      db->nDeferredCons = p->nStmtDefCons;
+    }
+  }
+  return rc;
+}
+
+/*
+** This function is called when a transaction opened by the database 
+** handle associated with the VM passed as an argument is about to be 
+** committed. If there are outstanding deferred foreign key constraint
+** violations, return SQLITE_ERROR. Otherwise, SQLITE_OK.
+**
+** If there are outstanding FK violations and this function returns 
+** SQLITE_ERROR, set the result of the VM to SQLITE_CONSTRAINT and write
+** an error message to it. Then return SQLITE_ERROR.
+*/
+#ifndef SQLITE_OMIT_FOREIGN_KEY
+SQLITE_PRIVATE int sqlite3VdbeCheckFk(Vdbe *p, int deferred){
+  sqlite3 *db = p->db;
+  if( (deferred && db->nDeferredCons>0) || (!deferred && p->nFkConstraint>0) ){
+    p->rc = SQLITE_CONSTRAINT;
+    p->errorAction = OE_Abort;
+    sqlite3SetString(&p->zErrMsg, db, "foreign key constraint failed");
+    return SQLITE_ERROR;
+  }
+  return SQLITE_OK;
+}
+#endif
+
+/*
+** This routine is called the when a VDBE tries to halt.  If the VDBE
+** has made changes and is in autocommit mode, then commit those
+** changes.  If a rollback is needed, then do the rollback.
+**
+** This routine is the only way to move the state of a VM from
+** SQLITE_MAGIC_RUN to SQLITE_MAGIC_HALT.  It is harmless to
+** call this on a VM that is in the SQLITE_MAGIC_HALT state.
+**
+** Return an error code.  If the commit could not complete because of
+** lock contention, return SQLITE_BUSY.  If SQLITE_BUSY is returned, it
+** means the close did not happen and needs to be repeated.
+*/
+SQLITE_PRIVATE int sqlite3VdbeHalt(Vdbe *p){
+  int rc;                         /* Used to store transient return codes */
+  sqlite3 *db = p->db;
+
+  /* This function contains the logic that determines if a statement or
+  ** transaction will be committed or rolled back as a result of the
+  ** execution of this virtual machine. 
+  **
+  ** If any of the following errors occur:
+  **
+  **     SQLITE_NOMEM
+  **     SQLITE_IOERR
+  **     SQLITE_FULL
+  **     SQLITE_INTERRUPT
+  **
+  ** Then the internal cache might have been left in an inconsistent
+  ** state.  We need to rollback the statement transaction, if there is
+  ** one, or the complete transaction if there is no statement transaction.
+  */
+
+  if( p->db->mallocFailed ){
+    p->rc = SQLITE_NOMEM;
+  }
+  closeAllCursors(p);
+  if( p->magic!=VDBE_MAGIC_RUN ){
+    return SQLITE_OK;
+  }
+  checkActiveVdbeCnt(db);
+
+  /* No commit or rollback needed if the program never started */
+  if( p->pc>=0 ){
+    int mrc;   /* Primary error code from p->rc */
+    int eStatementOp = 0;
+    int isSpecialError;            /* Set to true if a 'special' error */
+
+    /* Lock all btrees used by the statement */
+    sqlite3VdbeEnter(p);
+
+    /* Check for one of the special errors */
+    mrc = p->rc & 0xff;
+    assert( p->rc!=SQLITE_IOERR_BLOCKED );  /* This error no longer exists */
+    isSpecialError = mrc==SQLITE_NOMEM || mrc==SQLITE_IOERR
+                     || mrc==SQLITE_INTERRUPT || mrc==SQLITE_FULL;
+    if( isSpecialError ){
+      /* If the query was read-only and the error code is SQLITE_INTERRUPT, 
+      ** no rollback is necessary. Otherwise, at least a savepoint 
+      ** transaction must be rolled back to restore the database to a 
+      ** consistent state.
+      **
+      ** Even if the statement is read-only, it is important to perform
+      ** a statement or transaction rollback operation. If the error 
+      ** occured while writing to the journal, sub-journal or database
+      ** file as part of an effort to free up cache space (see function
+      ** pagerStress() in pager.c), the rollback is required to restore 
+      ** the pager to a consistent state.
+      */
+      if( !p->readOnly || mrc!=SQLITE_INTERRUPT ){
+        if( (mrc==SQLITE_NOMEM || mrc==SQLITE_FULL) && p->usesStmtJournal ){
+          eStatementOp = SAVEPOINT_ROLLBACK;
+        }else{
+          /* We are forced to roll back the active transaction. Before doing
+          ** so, abort any other statements this handle currently has active.
+          */
+          invalidateCursorsOnModifiedBtrees(db);
+          sqlite3RollbackAll(db);
+          sqlite3CloseSavepoints(db);
+          db->autoCommit = 1;
+        }
+      }
+    }
+
+    /* Check for immediate foreign key violations. */
+    if( p->rc==SQLITE_OK ){
+      sqlite3VdbeCheckFk(p, 0);
+    }
+  
+    /* If the auto-commit flag is set and this is the only active writer 
+    ** VM, then we do either a commit or rollback of the current transaction. 
+    **
+    ** Note: This block also runs if one of the special errors handled 
+    ** above has occurred. 
+    */
+    if( !sqlite3VtabInSync(db) 
+     && db->autoCommit 
+     && db->writeVdbeCnt==(p->readOnly==0) 
+    ){
+      if( p->rc==SQLITE_OK || (p->errorAction==OE_Fail && !isSpecialError) ){
+        rc = sqlite3VdbeCheckFk(p, 1);
+        if( rc!=SQLITE_OK ){
+          if( NEVER(p->readOnly) ){
+            sqlite3VdbeLeave(p);
+            return SQLITE_ERROR;
+          }
+          rc = SQLITE_CONSTRAINT;
+        }else{ 
+          /* The auto-commit flag is true, the vdbe program was successful 
+          ** or hit an 'OR FAIL' constraint and there are no deferred foreign
+          ** key constraints to hold up the transaction. This means a commit 
+          ** is required. */
+          rc = vdbeCommit(db, p);
+        }
+        if( rc==SQLITE_BUSY && p->readOnly ){
+          sqlite3VdbeLeave(p);
+          return SQLITE_BUSY;
+        }else if( rc!=SQLITE_OK ){
+          p->rc = rc;
+          sqlite3RollbackAll(db);
+        }else{
+          db->nDeferredCons = 0;
+          sqlite3CommitInternalChanges(db);
+        }
+      }else{
+        sqlite3RollbackAll(db);
+      }
+      db->nStatement = 0;
+    }else if( eStatementOp==0 ){
+      if( p->rc==SQLITE_OK || p->errorAction==OE_Fail ){
+        eStatementOp = SAVEPOINT_RELEASE;
+      }else if( p->errorAction==OE_Abort ){
+        eStatementOp = SAVEPOINT_ROLLBACK;
+      }else{
+        invalidateCursorsOnModifiedBtrees(db);
+        sqlite3RollbackAll(db);
+        sqlite3CloseSavepoints(db);
+        db->autoCommit = 1;
+      }
+    }
+  
+    /* If eStatementOp is non-zero, then a statement transaction needs to
+    ** be committed or rolled back. Call sqlite3VdbeCloseStatement() to
+    ** do so. If this operation returns an error, and the current statement
+    ** error code is SQLITE_OK or SQLITE_CONSTRAINT, then promote the
+    ** current statement error code.
+    **
+    ** Note that sqlite3VdbeCloseStatement() can only fail if eStatementOp
+    ** is SAVEPOINT_ROLLBACK.  But if p->rc==SQLITE_OK then eStatementOp
+    ** must be SAVEPOINT_RELEASE.  Hence the NEVER(p->rc==SQLITE_OK) in 
+    ** the following code.
+    */
+    if( eStatementOp ){
+      rc = sqlite3VdbeCloseStatement(p, eStatementOp);
+      if( rc ){
+        assert( eStatementOp==SAVEPOINT_ROLLBACK );
+        if( NEVER(p->rc==SQLITE_OK) || p->rc==SQLITE_CONSTRAINT ){
+          p->rc = rc;
+          sqlite3DbFree(db, p->zErrMsg);
+          p->zErrMsg = 0;
+        }
+        invalidateCursorsOnModifiedBtrees(db);
+        sqlite3RollbackAll(db);
+        sqlite3CloseSavepoints(db);
+        db->autoCommit = 1;
+      }
+    }
+  
+    /* If this was an INSERT, UPDATE or DELETE and no statement transaction
+    ** has been rolled back, update the database connection change-counter. 
+    */
+    if( p->changeCntOn ){
+      if( eStatementOp!=SAVEPOINT_ROLLBACK ){
+        sqlite3VdbeSetChanges(db, p->nChange);
+      }else{
+        sqlite3VdbeSetChanges(db, 0);
+      }
+      p->nChange = 0;
+    }
+  
+    /* Rollback or commit any schema changes that occurred. */
+    if( p->rc!=SQLITE_OK && db->flags&SQLITE_InternChanges ){
+      sqlite3ResetInternalSchema(db, -1);
+      db->flags = (db->flags | SQLITE_InternChanges);
+    }
+
+    /* Release the locks */
+    sqlite3VdbeLeave(p);
+  }
+
+  /* We have successfully halted and closed the VM.  Record this fact. */
+  if( p->pc>=0 ){
+    db->activeVdbeCnt--;
+    if( !p->readOnly ){
+      db->writeVdbeCnt--;
+    }
+    assert( db->activeVdbeCnt>=db->writeVdbeCnt );
+  }
+  p->magic = VDBE_MAGIC_HALT;
+  checkActiveVdbeCnt(db);
+  if( p->db->mallocFailed ){
+    p->rc = SQLITE_NOMEM;
+  }
+
+  /* If the auto-commit flag is set to true, then any locks that were held
+  ** by connection db have now been released. Call sqlite3ConnectionUnlocked() 
+  ** to invoke any required unlock-notify callbacks.
+  */
+  if( db->autoCommit ){
+    sqlite3ConnectionUnlocked(db);
+  }
+
+  assert( db->activeVdbeCnt>0 || db->autoCommit==0 || db->nStatement==0 );
+  return (p->rc==SQLITE_BUSY ? SQLITE_BUSY : SQLITE_OK);
+}
+
+
+/*
+** Each VDBE holds the result of the most recent sqlite3_step() call
+** in p->rc.  This routine sets that result back to SQLITE_OK.
+*/
+SQLITE_PRIVATE void sqlite3VdbeResetStepResult(Vdbe *p){
+  p->rc = SQLITE_OK;
+}
+
+/*
+** Clean up a VDBE after execution but do not delete the VDBE just yet.
+** Write any error messages into *pzErrMsg.  Return the result code.
+**
+** After this routine is run, the VDBE should be ready to be executed
+** again.
+**
+** To look at it another way, this routine resets the state of the
+** virtual machine from VDBE_MAGIC_RUN or VDBE_MAGIC_HALT back to
+** VDBE_MAGIC_INIT.
+*/
+SQLITE_PRIVATE int sqlite3VdbeReset(Vdbe *p){
+  sqlite3 *db;
+  db = p->db;
+
+  /* If the VM did not run to completion or if it encountered an
+  ** error, then it might not have been halted properly.  So halt
+  ** it now.
+  */
+  sqlite3VdbeHalt(p);
+
+  /* If the VDBE has be run even partially, then transfer the error code
+  ** and error message from the VDBE into the main database structure.  But
+  ** if the VDBE has just been set to run but has not actually executed any
+  ** instructions yet, leave the main database error information unchanged.
+  */
+  if( p->pc>=0 ){
+    if( p->zErrMsg ){
+      sqlite3BeginBenignMalloc();
+      sqlite3ValueSetStr(db->pErr,-1,p->zErrMsg,SQLITE_UTF8,SQLITE_TRANSIENT);
+      sqlite3EndBenignMalloc();
+      db->errCode = p->rc;
+      sqlite3DbFree(db, p->zErrMsg);
+      p->zErrMsg = 0;
+    }else if( p->rc ){
+      sqlite3Error(db, p->rc, 0);
+    }else{
+      sqlite3Error(db, SQLITE_OK, 0);
+    }
+    if( p->runOnlyOnce ) p->expired = 1;
+  }else if( p->rc && p->expired ){
+    /* The expired flag was set on the VDBE before the first call
+    ** to sqlite3_step(). For consistency (since sqlite3_step() was
+    ** called), set the database error in this case as well.
+    */
+    sqlite3Error(db, p->rc, 0);
+    sqlite3ValueSetStr(db->pErr, -1, p->zErrMsg, SQLITE_UTF8, SQLITE_TRANSIENT);
+    sqlite3DbFree(db, p->zErrMsg);
+    p->zErrMsg = 0;
+  }
+
+  /* Reclaim all memory used by the VDBE
+  */
+  Cleanup(p);
+
+  /* Save profiling information from this VDBE run.
+  */
+#ifdef VDBE_PROFILE
+  {
+    FILE *out = fopen("vdbe_profile.out", "a");
+    if( out ){
+      int i;
+      fprintf(out, "---- ");
+      for(i=0; i<p->nOp; i++){
+        fprintf(out, "%02x", p->aOp[i].opcode);
+      }
+      fprintf(out, "\n");
+      for(i=0; i<p->nOp; i++){
+        fprintf(out, "%6d %10lld %8lld ",
+           p->aOp[i].cnt,
+           p->aOp[i].cycles,
+           p->aOp[i].cnt>0 ? p->aOp[i].cycles/p->aOp[i].cnt : 0
+        );
+        sqlite3VdbePrintOp(out, i, &p->aOp[i]);
+      }
+      fclose(out);
+    }
+  }
+#endif
+  p->magic = VDBE_MAGIC_INIT;
+  return p->rc & db->errMask;
+}
+ 
+/*
+** Clean up and delete a VDBE after execution.  Return an integer which is
+** the result code.  Write any error message text into *pzErrMsg.
+*/
+SQLITE_PRIVATE int sqlite3VdbeFinalize(Vdbe *p){
+  int rc = SQLITE_OK;
+  if( p->magic==VDBE_MAGIC_RUN || p->magic==VDBE_MAGIC_HALT ){
+    rc = sqlite3VdbeReset(p);
+    assert( (rc & p->db->errMask)==rc );
+  }
+  sqlite3VdbeDelete(p);
+  return rc;
+}
+
+/*
+** Call the destructor for each auxdata entry in pVdbeFunc for which
+** the corresponding bit in mask is clear.  Auxdata entries beyond 31
+** are always destroyed.  To destroy all auxdata entries, call this
+** routine with mask==0.
+*/
+SQLITE_PRIVATE void sqlite3VdbeDeleteAuxData(VdbeFunc *pVdbeFunc, int mask){
+  int i;
+  for(i=0; i<pVdbeFunc->nAux; i++){
+    struct AuxData *pAux = &pVdbeFunc->apAux[i];
+    if( (i>31 || !(mask&(((u32)1)<<i))) && pAux->pAux ){
+      if( pAux->xDelete ){
+        pAux->xDelete(pAux->pAux);
+      }
+      pAux->pAux = 0;
+    }
+  }
+}
+
+/*
+** Free all memory associated with the Vdbe passed as the second argument.
+** The difference between this function and sqlite3VdbeDelete() is that
+** VdbeDelete() also unlinks the Vdbe from the list of VMs associated with
+** the database connection.
+*/
+SQLITE_PRIVATE void sqlite3VdbeDeleteObject(sqlite3 *db, Vdbe *p){
+  SubProgram *pSub, *pNext;
+  assert( p->db==0 || p->db==db );
+  releaseMemArray(p->aVar, p->nVar);
+  releaseMemArray(p->aColName, p->nResColumn*COLNAME_N);
+  for(pSub=p->pProgram; pSub; pSub=pNext){
+    pNext = pSub->pNext;
+    vdbeFreeOpArray(db, pSub->aOp, pSub->nOp);
+    sqlite3DbFree(db, pSub);
+  }
+  vdbeFreeOpArray(db, p->aOp, p->nOp);
+  sqlite3DbFree(db, p->aLabel);
+  sqlite3DbFree(db, p->aColName);
+  sqlite3DbFree(db, p->zSql);
+  sqlite3DbFree(db, p->pFree);
+  sqlite3DbFree(db, p);
+}
+
+/*
+** Delete an entire VDBE.
+*/
+SQLITE_PRIVATE void sqlite3VdbeDelete(Vdbe *p){
+  sqlite3 *db;
+
+  if( NEVER(p==0) ) return;
+  db = p->db;
+  if( p->pPrev ){
+    p->pPrev->pNext = p->pNext;
+  }else{
+    assert( db->pVdbe==p );
+    db->pVdbe = p->pNext;
+  }
+  if( p->pNext ){
+    p->pNext->pPrev = p->pPrev;
+  }
+  p->magic = VDBE_MAGIC_DEAD;
+  p->db = 0;
+  sqlite3VdbeDeleteObject(db, p);
+}
+
+/*
+** Make sure the cursor p is ready to read or write the row to which it
+** was last positioned.  Return an error code if an OOM fault or I/O error
+** prevents us from positioning the cursor to its correct position.
+**
+** If a MoveTo operation is pending on the given cursor, then do that
+** MoveTo now.  If no move is pending, check to see if the row has been
+** deleted out from under the cursor and if it has, mark the row as
+** a NULL row.
+**
+** If the cursor is already pointing to the correct row and that row has
+** not been deleted out from under the cursor, then this routine is a no-op.
+*/
+SQLITE_PRIVATE int sqlite3VdbeCursorMoveto(VdbeCursor *p){
+  if( p->deferredMoveto ){
+    int res, rc;
+#ifdef SQLITE_TEST
+    extern int sqlite3_search_count;
+#endif
+    assert( p->isTable );
+    rc = sqlite3BtreeMovetoUnpacked(p->pCursor, 0, p->movetoTarget, 0, &res);
+    if( rc ) return rc;
+    p->lastRowid = p->movetoTarget;
+    if( res!=0 ) return SQLITE_CORRUPT_BKPT;
+    p->rowidIsValid = 1;
+#ifdef SQLITE_TEST
+    sqlite3_search_count++;
+#endif
+    p->deferredMoveto = 0;
+    p->cacheStatus = CACHE_STALE;
+  }else if( ALWAYS(p->pCursor) ){
+    int hasMoved;
+    int rc = sqlite3BtreeCursorHasMoved(p->pCursor, &hasMoved);
+    if( rc ) return rc;
+    if( hasMoved ){
+      p->cacheStatus = CACHE_STALE;
+      p->nullRow = 1;
+    }
+  }
+  return SQLITE_OK;
+}
+
+/*
+** The following functions:
+**
+** sqlite3VdbeSerialType()
+** sqlite3VdbeSerialTypeLen()
+** sqlite3VdbeSerialLen()
+** sqlite3VdbeSerialPut()
+** sqlite3VdbeSerialGet()
+**
+** encapsulate the code that serializes values for storage in SQLite
+** data and index records. Each serialized value consists of a
+** 'serial-type' and a blob of data. The serial type is an 8-byte unsigned
+** integer, stored as a varint.
+**
+** In an SQLite index record, the serial type is stored directly before
+** the blob of data that it corresponds to. In a table record, all serial
+** types are stored at the start of the record, and the blobs of data at
+** the end. Hence these functions allow the caller to handle the
+** serial-type and data blob seperately.
+**
+** The following table describes the various storage classes for data:
+**
+**   serial type        bytes of data      type
+**   --------------     ---------------    ---------------
+**      0                     0            NULL
+**      1                     1            signed integer
+**      2                     2            signed integer
+**      3                     3            signed integer
+**      4                     4            signed integer
+**      5                     6            signed integer
+**      6                     8            signed integer
+**      7                     8            IEEE float
+**      8                     0            Integer constant 0
+**      9                     0            Integer constant 1
+**     10,11                               reserved for expansion
+**    N>=12 and even       (N-12)/2        BLOB
+**    N>=13 and odd        (N-13)/2        text
+**
+** The 8 and 9 types were added in 3.3.0, file format 4.  Prior versions
+** of SQLite will not understand those serial types.
+*/
+
+/*
+** Return the serial-type for the value stored in pMem.
+*/
+SQLITE_PRIVATE u32 sqlite3VdbeSerialType(Mem *pMem, int file_format){
+  int flags = pMem->flags;
+  int n;
+
+  if( flags&MEM_Null ){
+    return 0;
+  }
+  if( flags&MEM_Int ){
+    /* Figure out whether to use 1, 2, 4, 6 or 8 bytes. */
+#   define MAX_6BYTE ((((i64)0x00008000)<<32)-1)
+    i64 i = pMem->u.i;
+    u64 u;
+    if( file_format>=4 && (i&1)==i ){
+      return 8+(u32)i;
+    }
+    if( i<0 ){
+      if( i<(-MAX_6BYTE) ) return 6;
+      /* Previous test prevents:  u = -(-9223372036854775808) */
+      u = -i;
+    }else{
+      u = i;
+    }
+    if( u<=127 ) return 1;
+    if( u<=32767 ) return 2;
+    if( u<=8388607 ) return 3;
+    if( u<=2147483647 ) return 4;
+    if( u<=MAX_6BYTE ) return 5;
+    return 6;
+  }
+  if( flags&MEM_Real ){
+    return 7;
+  }
+  assert( pMem->db->mallocFailed || flags&(MEM_Str|MEM_Blob) );
+  n = pMem->n;
+  if( flags & MEM_Zero ){
+    n += pMem->u.nZero;
+  }
+  assert( n>=0 );
+  return ((n*2) + 12 + ((flags&MEM_Str)!=0));
+}
+
+/*
+** Return the length of the data corresponding to the supplied serial-type.
+*/
+SQLITE_PRIVATE u32 sqlite3VdbeSerialTypeLen(u32 serial_type){
+  if( serial_type>=12 ){
+    return (serial_type-12)/2;
+  }else{
+    static const u8 aSize[] = { 0, 1, 2, 3, 4, 6, 8, 8, 0, 0, 0, 0 };
+    return aSize[serial_type];
+  }
+}
+
+/*
+** If we are on an architecture with mixed-endian floating 
+** points (ex: ARM7) then swap the lower 4 bytes with the 
+** upper 4 bytes.  Return the result.
+**
+** For most architectures, this is a no-op.
+**
+** (later):  It is reported to me that the mixed-endian problem
+** on ARM7 is an issue with GCC, not with the ARM7 chip.  It seems
+** that early versions of GCC stored the two words of a 64-bit
+** float in the wrong order.  And that error has been propagated
+** ever since.  The blame is not necessarily with GCC, though.
+** GCC might have just copying the problem from a prior compiler.
+** I am also told that newer versions of GCC that follow a different
+** ABI get the byte order right.
+**
+** Developers using SQLite on an ARM7 should compile and run their
+** application using -DSQLITE_DEBUG=1 at least once.  With DEBUG
+** enabled, some asserts below will ensure that the byte order of
+** floating point values is correct.
+**
+** (2007-08-30)  Frank van Vugt has studied this problem closely
+** and has send his findings to the SQLite developers.  Frank
+** writes that some Linux kernels offer floating point hardware
+** emulation that uses only 32-bit mantissas instead of a full 
+** 48-bits as required by the IEEE standard.  (This is the
+** CONFIG_FPE_FASTFPE option.)  On such systems, floating point
+** byte swapping becomes very complicated.  To avoid problems,
+** the necessary byte swapping is carried out using a 64-bit integer
+** rather than a 64-bit float.  Frank assures us that the code here
+** works for him.  We, the developers, have no way to independently
+** verify this, but Frank seems to know what he is talking about
+** so we trust him.
+*/
+#ifdef SQLITE_MIXED_ENDIAN_64BIT_FLOAT
+static u64 floatSwap(u64 in){
+  union {
+    u64 r;
+    u32 i[2];
+  } u;
+  u32 t;
+
+  u.r = in;
+  t = u.i[0];
+  u.i[0] = u.i[1];
+  u.i[1] = t;
+  return u.r;
+}
+# define swapMixedEndianFloat(X)  X = floatSwap(X)
+#else
+# define swapMixedEndianFloat(X)
+#endif
+
+/*
+** Write the serialized data blob for the value stored in pMem into 
+** buf. It is assumed that the caller has allocated sufficient space.
+** Return the number of bytes written.
+**
+** nBuf is the amount of space left in buf[].  nBuf must always be
+** large enough to hold the entire field.  Except, if the field is
+** a blob with a zero-filled tail, then buf[] might be just the right
+** size to hold everything except for the zero-filled tail.  If buf[]
+** is only big enough to hold the non-zero prefix, then only write that
+** prefix into buf[].  But if buf[] is large enough to hold both the
+** prefix and the tail then write the prefix and set the tail to all
+** zeros.
+**
+** Return the number of bytes actually written into buf[].  The number
+** of bytes in the zero-filled tail is included in the return value only
+** if those bytes were zeroed in buf[].
+*/ 
+SQLITE_PRIVATE u32 sqlite3VdbeSerialPut(u8 *buf, int nBuf, Mem *pMem, int file_format){
+  u32 serial_type = sqlite3VdbeSerialType(pMem, file_format);
+  u32 len;
+
+  /* Integer and Real */
+  if( serial_type<=7 && serial_type>0 ){
+    u64 v;
+    u32 i;
+    if( serial_type==7 ){
+      assert( sizeof(v)==sizeof(pMem->r) );
+      memcpy(&v, &pMem->r, sizeof(v));
+      swapMixedEndianFloat(v);
+    }else{
+      v = pMem->u.i;
+    }
+    len = i = sqlite3VdbeSerialTypeLen(serial_type);
+    assert( len<=(u32)nBuf );
+    while( i-- ){
+      buf[i] = (u8)(v&0xFF);
+      v >>= 8;
+    }
+    return len;
+  }
+
+  /* String or blob */
+  if( serial_type>=12 ){
+    assert( pMem->n + ((pMem->flags & MEM_Zero)?pMem->u.nZero:0)
+             == (int)sqlite3VdbeSerialTypeLen(serial_type) );
+    assert( pMem->n<=nBuf );
+    len = pMem->n;
+    memcpy(buf, pMem->z, len);
+    if( pMem->flags & MEM_Zero ){
+      len += pMem->u.nZero;
+      assert( nBuf>=0 );
+      if( len > (u32)nBuf ){
+        len = (u32)nBuf;
+      }
+      memset(&buf[pMem->n], 0, len-pMem->n);
+    }
+    return len;
+  }
+
+  /* NULL or constants 0 or 1 */
+  return 0;
+}
+
+/*
+** Deserialize the data blob pointed to by buf as serial type serial_type
+** and store the result in pMem.  Return the number of bytes read.
+*/ 
+SQLITE_PRIVATE u32 sqlite3VdbeSerialGet(
+  const unsigned char *buf,     /* Buffer to deserialize from */
+  u32 serial_type,              /* Serial type to deserialize */
+  Mem *pMem                     /* Memory cell to write value into */
+){
+  switch( serial_type ){
+    case 10:   /* Reserved for future use */
+    case 11:   /* Reserved for future use */
+    case 0: {  /* NULL */
+      pMem->flags = MEM_Null;
+      break;
+    }
+    case 1: { /* 1-byte signed integer */
+      pMem->u.i = (signed char)buf[0];
+      pMem->flags = MEM_Int;
+      return 1;
+    }
+    case 2: { /* 2-byte signed integer */
+      pMem->u.i = (((signed char)buf[0])<<8) | buf[1];
+      pMem->flags = MEM_Int;
+      return 2;
+    }
+    case 3: { /* 3-byte signed integer */
+      pMem->u.i = (((signed char)buf[0])<<16) | (buf[1]<<8) | buf[2];
+      pMem->flags = MEM_Int;
+      return 3;
+    }
+    case 4: { /* 4-byte signed integer */
+      pMem->u.i = (buf[0]<<24) | (buf[1]<<16) | (buf[2]<<8) | buf[3];
+      pMem->flags = MEM_Int;
+      return 4;
+    }
+    case 5: { /* 6-byte signed integer */
+      u64 x = (((signed char)buf[0])<<8) | buf[1];
+      u32 y = (buf[2]<<24) | (buf[3]<<16) | (buf[4]<<8) | buf[5];
+      x = (x<<32) | y;
+      pMem->u.i = *(i64*)&x;
+      pMem->flags = MEM_Int;
+      return 6;
+    }
+    case 6:   /* 8-byte signed integer */
+    case 7: { /* IEEE floating point */
+      u64 x;
+      u32 y;
+#if !defined(NDEBUG) && !defined(SQLITE_OMIT_FLOATING_POINT)
+      /* Verify that integers and floating point values use the same
+      ** byte order.  Or, that if SQLITE_MIXED_ENDIAN_64BIT_FLOAT is
+      ** defined that 64-bit floating point values really are mixed
+      ** endian.
+      */
+      static const u64 t1 = ((u64)0x3ff00000)<<32;
+      static const double r1 = 1.0;
+      u64 t2 = t1;
+      swapMixedEndianFloat(t2);
+      assert( sizeof(r1)==sizeof(t2) && memcmp(&r1, &t2, sizeof(r1))==0 );
+#endif
+
+      x = (buf[0]<<24) | (buf[1]<<16) | (buf[2]<<8) | buf[3];
+      y = (buf[4]<<24) | (buf[5]<<16) | (buf[6]<<8) | buf[7];
+      x = (x<<32) | y;
+      if( serial_type==6 ){
+        pMem->u.i = *(i64*)&x;
+        pMem->flags = MEM_Int;
+      }else{
+        assert( sizeof(x)==8 && sizeof(pMem->r)==8 );
+        swapMixedEndianFloat(x);
+        memcpy(&pMem->r, &x, sizeof(x));
+        pMem->flags = sqlite3IsNaN(pMem->r) ? MEM_Null : MEM_Real;
+      }
+      return 8;
+    }
+    case 8:    /* Integer 0 */
+    case 9: {  /* Integer 1 */
+      pMem->u.i = serial_type-8;
+      pMem->flags = MEM_Int;
+      return 0;
+    }
+    default: {
+      u32 len = (serial_type-12)/2;
+      pMem->z = (char *)buf;
+      pMem->n = len;
+      pMem->xDel = 0;
+      if( serial_type&0x01 ){
+        pMem->flags = MEM_Str | MEM_Ephem;
+      }else{
+        pMem->flags = MEM_Blob | MEM_Ephem;
+      }
+      return len;
+    }
+  }
+  return 0;
+}
+
+
+/*
+** Given the nKey-byte encoding of a record in pKey[], parse the
+** record into a UnpackedRecord structure.  Return a pointer to
+** that structure.
+**
+** The calling function might provide szSpace bytes of memory
+** space at pSpace.  This space can be used to hold the returned
+** VDbeParsedRecord structure if it is large enough.  If it is
+** not big enough, space is obtained from sqlite3_malloc().
+**
+** The returned structure should be closed by a call to
+** sqlite3VdbeDeleteUnpackedRecord().
+*/ 
+SQLITE_PRIVATE UnpackedRecord *sqlite3VdbeRecordUnpack(
+  KeyInfo *pKeyInfo,     /* Information about the record format */
+  int nKey,              /* Size of the binary record */
+  const void *pKey,      /* The binary record */
+  char *pSpace,          /* Unaligned space available to hold the object */
+  int szSpace            /* Size of pSpace[] in bytes */
+){
+  const unsigned char *aKey = (const unsigned char *)pKey;
+  UnpackedRecord *p;  /* The unpacked record that we will return */
+  int nByte;          /* Memory space needed to hold p, in bytes */
+  int d;
+  u32 idx;
+  u16 u;              /* Unsigned loop counter */
+  u32 szHdr;
+  Mem *pMem;
+  int nOff;           /* Increase pSpace by this much to 8-byte align it */
+  
+  /*
+  ** We want to shift the pointer pSpace up such that it is 8-byte aligned.
+  ** Thus, we need to calculate a value, nOff, between 0 and 7, to shift 
+  ** it by.  If pSpace is already 8-byte aligned, nOff should be zero.
+  */
+  nOff = (8 - (SQLITE_PTR_TO_INT(pSpace) & 7)) & 7;
+  pSpace += nOff;
+  szSpace -= nOff;
+  nByte = ROUND8(sizeof(UnpackedRecord)) + sizeof(Mem)*(pKeyInfo->nField+1);
+  if( nByte>szSpace ){
+    p = sqlite3DbMallocRaw(pKeyInfo->db, nByte);
+    if( p==0 ) return 0;
+    p->flags = UNPACKED_NEED_FREE | UNPACKED_NEED_DESTROY;
+  }else{
+    p = (UnpackedRecord*)pSpace;
+    p->flags = UNPACKED_NEED_DESTROY;
+  }
+  p->pKeyInfo = pKeyInfo;
+  p->nField = pKeyInfo->nField + 1;
+  p->aMem = pMem = (Mem*)&((char*)p)[ROUND8(sizeof(UnpackedRecord))];
+  assert( EIGHT_BYTE_ALIGNMENT(pMem) );
+  idx = getVarint32(aKey, szHdr);
+  d = szHdr;
+  u = 0;
+  while( idx<szHdr && u<p->nField && d<=nKey ){
+    u32 serial_type;
+
+    idx += getVarint32(&aKey[idx], serial_type);
+    pMem->enc = pKeyInfo->enc;
+    pMem->db = pKeyInfo->db;
+    pMem->flags = 0;
+    pMem->zMalloc = 0;
+    d += sqlite3VdbeSerialGet(&aKey[d], serial_type, pMem);
+    pMem++;
+    u++;
+  }
+  assert( u<=pKeyInfo->nField + 1 );
+  p->nField = u;
+  return (void*)p;
+}
+
+/*
+** This routine destroys a UnpackedRecord object.
+*/
+SQLITE_PRIVATE void sqlite3VdbeDeleteUnpackedRecord(UnpackedRecord *p){
+  int i;
+  Mem *pMem;
+
+  assert( p!=0 );
+  assert( p->flags & UNPACKED_NEED_DESTROY );
+  for(i=0, pMem=p->aMem; i<p->nField; i++, pMem++){
+    /* The unpacked record is always constructed by the
+    ** sqlite3VdbeUnpackRecord() function above, which makes all
+    ** strings and blobs static.  And none of the elements are
+    ** ever transformed, so there is never anything to delete.
+    */
+    if( NEVER(pMem->zMalloc) ) sqlite3VdbeMemRelease(pMem);
+  }
+  if( p->flags & UNPACKED_NEED_FREE ){
+    sqlite3DbFree(p->pKeyInfo->db, p);
+  }
+}
+
+/*
+** This function compares the two table rows or index records
+** specified by {nKey1, pKey1} and pPKey2.  It returns a negative, zero
+** or positive integer if key1 is less than, equal to or 
+** greater than key2.  The {nKey1, pKey1} key must be a blob
+** created by th OP_MakeRecord opcode of the VDBE.  The pPKey2
+** key must be a parsed key such as obtained from
+** sqlite3VdbeParseRecord.
+**
+** Key1 and Key2 do not have to contain the same number of fields.
+** The key with fewer fields is usually compares less than the 
+** longer key.  However if the UNPACKED_INCRKEY flags in pPKey2 is set
+** and the common prefixes are equal, then key1 is less than key2.
+** Or if the UNPACKED_MATCH_PREFIX flag is set and the prefixes are
+** equal, then the keys are considered to be equal and
+** the parts beyond the common prefix are ignored.
+**
+** If the UNPACKED_IGNORE_ROWID flag is set, then the last byte of
+** the header of pKey1 is ignored.  It is assumed that pKey1 is
+** an index key, and thus ends with a rowid value.  The last byte
+** of the header will therefore be the serial type of the rowid:
+** one of 1, 2, 3, 4, 5, 6, 8, or 9 - the integer serial types.
+** The serial type of the final rowid will always be a single byte.
+** By ignoring this last byte of the header, we force the comparison
+** to ignore the rowid at the end of key1.
+*/
+SQLITE_PRIVATE int sqlite3VdbeRecordCompare(
+  int nKey1, const void *pKey1, /* Left key */
+  UnpackedRecord *pPKey2        /* Right key */
+){
+  int d1;            /* Offset into aKey[] of next data element */
+  u32 idx1;          /* Offset into aKey[] of next header element */
+  u32 szHdr1;        /* Number of bytes in header */
+  int i = 0;
+  int nField;
+  int rc = 0;
+  const unsigned char *aKey1 = (const unsigned char *)pKey1;
+  KeyInfo *pKeyInfo;
+  Mem mem1;
+
+  pKeyInfo = pPKey2->pKeyInfo;
+  mem1.enc = pKeyInfo->enc;
+  mem1.db = pKeyInfo->db;
+  /* mem1.flags = 0;  // Will be initialized by sqlite3VdbeSerialGet() */
+  VVA_ONLY( mem1.zMalloc = 0; ) /* Only needed by assert() statements */
+
+  /* Compilers may complain that mem1.u.i is potentially uninitialized.
+  ** We could initialize it, as shown here, to silence those complaints.
+  ** But in fact, mem1.u.i will never actually be used initialized, and doing 
+  ** the unnecessary initialization has a measurable negative performance
+  ** impact, since this routine is a very high runner.  And so, we choose
+  ** to ignore the compiler warnings and leave this variable uninitialized.
+  */
+  /*  mem1.u.i = 0;  // not needed, here to silence compiler warning */
+  
+  idx1 = getVarint32(aKey1, szHdr1);
+  d1 = szHdr1;
+  if( pPKey2->flags & UNPACKED_IGNORE_ROWID ){
+    szHdr1--;
+  }
+  nField = pKeyInfo->nField;
+  while( idx1<szHdr1 && i<pPKey2->nField ){
+    u32 serial_type1;
+
+    /* Read the serial types for the next element in each key. */
+    idx1 += getVarint32( aKey1+idx1, serial_type1 );
+    if( d1>=nKey1 && sqlite3VdbeSerialTypeLen(serial_type1)>0 ) break;
+
+    /* Extract the values to be compared.
+    */
+    d1 += sqlite3VdbeSerialGet(&aKey1[d1], serial_type1, &mem1);
+
+    /* Do the comparison
+    */
+    rc = sqlite3MemCompare(&mem1, &pPKey2->aMem[i],
+                           i<nField ? pKeyInfo->aColl[i] : 0);
+    if( rc!=0 ){
+      assert( mem1.zMalloc==0 );  /* See comment below */
+
+      /* Invert the result if we are using DESC sort order. */
+      if( pKeyInfo->aSortOrder && i<nField && pKeyInfo->aSortOrder[i] ){
+        rc = -rc;
+      }
+    
+      /* If the PREFIX_SEARCH flag is set and all fields except the final
+      ** rowid field were equal, then clear the PREFIX_SEARCH flag and set 
+      ** pPKey2->rowid to the value of the rowid field in (pKey1, nKey1).
+      ** This is used by the OP_IsUnique opcode.
+      */
+      if( (pPKey2->flags & UNPACKED_PREFIX_SEARCH) && i==(pPKey2->nField-1) ){
+        assert( idx1==szHdr1 && rc );
+        assert( mem1.flags & MEM_Int );
+        pPKey2->flags &= ~UNPACKED_PREFIX_SEARCH;
+        pPKey2->rowid = mem1.u.i;
+      }
+    
+      return rc;
+    }
+    i++;
+  }
+
+  /* No memory allocation is ever used on mem1.  Prove this using
+  ** the following assert().  If the assert() fails, it indicates a
+  ** memory leak and a need to call sqlite3VdbeMemRelease(&mem1).
+  */
+  assert( mem1.zMalloc==0 );
+
+  /* rc==0 here means that one of the keys ran out of fields and
+  ** all the fields up to that point were equal. If the UNPACKED_INCRKEY
+  ** flag is set, then break the tie by treating key2 as larger.
+  ** If the UPACKED_PREFIX_MATCH flag is set, then keys with common prefixes
+  ** are considered to be equal.  Otherwise, the longer key is the 
+  ** larger.  As it happens, the pPKey2 will always be the longer
+  ** if there is a difference.
+  */
+  assert( rc==0 );
+  if( pPKey2->flags & UNPACKED_INCRKEY ){
+    rc = -1;
+  }else if( pPKey2->flags & UNPACKED_PREFIX_MATCH ){
+    /* Leave rc==0 */
+  }else if( idx1<szHdr1 ){
+    rc = 1;
+  }
+  return rc;
+}
+ 
+
+/*
+** pCur points at an index entry created using the OP_MakeRecord opcode.
+** Read the rowid (the last field in the record) and store it in *rowid.
+** Return SQLITE_OK if everything works, or an error code otherwise.
+**
+** pCur might be pointing to text obtained from a corrupt database file.
+** So the content cannot be trusted.  Do appropriate checks on the content.
+*/
+SQLITE_PRIVATE int sqlite3VdbeIdxRowid(sqlite3 *db, BtCursor *pCur, i64 *rowid){
+  i64 nCellKey = 0;
+  int rc;
+  u32 szHdr;        /* Size of the header */
+  u32 typeRowid;    /* Serial type of the rowid */
+  u32 lenRowid;     /* Size of the rowid */
+  Mem m, v;
+
+  UNUSED_PARAMETER(db);
+
+  /* Get the size of the index entry.  Only indices entries of less
+  ** than 2GiB are support - anything large must be database corruption.
+  ** Any corruption is detected in sqlite3BtreeParseCellPtr(), though, so
+  ** this code can safely assume that nCellKey is 32-bits  
+  */
+  assert( sqlite3BtreeCursorIsValid(pCur) );
+  rc = sqlite3BtreeKeySize(pCur, &nCellKey);
+  assert( rc==SQLITE_OK );     /* pCur is always valid so KeySize cannot fail */
+  assert( (nCellKey & SQLITE_MAX_U32)==(u64)nCellKey );
+
+  /* Read in the complete content of the index entry */
+  memset(&m, 0, sizeof(m));
+  rc = sqlite3VdbeMemFromBtree(pCur, 0, (int)nCellKey, 1, &m);
+  if( rc ){
+    return rc;
+  }
+
+  /* The index entry must begin with a header size */
+  (void)getVarint32((u8*)m.z, szHdr);
+  testcase( szHdr==3 );
+  testcase( szHdr==m.n );
+  if( unlikely(szHdr<3 || (int)szHdr>m.n) ){
+    goto idx_rowid_corruption;
+  }
+
+  /* The last field of the index should be an integer - the ROWID.
+  ** Verify that the last entry really is an integer. */
+  (void)getVarint32((u8*)&m.z[szHdr-1], typeRowid);
+  testcase( typeRowid==1 );
+  testcase( typeRowid==2 );
+  testcase( typeRowid==3 );
+  testcase( typeRowid==4 );
+  testcase( typeRowid==5 );
+  testcase( typeRowid==6 );
+  testcase( typeRowid==8 );
+  testcase( typeRowid==9 );
+  if( unlikely(typeRowid<1 || typeRowid>9 || typeRowid==7) ){
+    goto idx_rowid_corruption;
+  }
+  lenRowid = sqlite3VdbeSerialTypeLen(typeRowid);
+  testcase( (u32)m.n==szHdr+lenRowid );
+  if( unlikely((u32)m.n<szHdr+lenRowid) ){
+    goto idx_rowid_corruption;
+  }
+
+  /* Fetch the integer off the end of the index record */
+  sqlite3VdbeSerialGet((u8*)&m.z[m.n-lenRowid], typeRowid, &v);
+  *rowid = v.u.i;
+  sqlite3VdbeMemRelease(&m);
+  return SQLITE_OK;
+
+  /* Jump here if database corruption is detected after m has been
+  ** allocated.  Free the m object and return SQLITE_CORRUPT. */
+idx_rowid_corruption:
+  testcase( m.zMalloc!=0 );
+  sqlite3VdbeMemRelease(&m);
+  return SQLITE_CORRUPT_BKPT;
+}
+
+/*
+** Compare the key of the index entry that cursor pC is pointing to against
+** the key string in pUnpacked.  Write into *pRes a number
+** that is negative, zero, or positive if pC is less than, equal to,
+** or greater than pUnpacked.  Return SQLITE_OK on success.
+**
+** pUnpacked is either created without a rowid or is truncated so that it
+** omits the rowid at the end.  The rowid at the end of the index entry
+** is ignored as well.  Hence, this routine only compares the prefixes 
+** of the keys prior to the final rowid, not the entire key.
+*/
+SQLITE_PRIVATE int sqlite3VdbeIdxKeyCompare(
+  VdbeCursor *pC,             /* The cursor to compare against */
+  UnpackedRecord *pUnpacked,  /* Unpacked version of key to compare against */
+  int *res                    /* Write the comparison result here */
+){
+  i64 nCellKey = 0;
+  int rc;
+  BtCursor *pCur = pC->pCursor;
+  Mem m;
+
+  assert( sqlite3BtreeCursorIsValid(pCur) );
+  rc = sqlite3BtreeKeySize(pCur, &nCellKey);
+  assert( rc==SQLITE_OK );    /* pCur is always valid so KeySize cannot fail */
+  /* nCellKey will always be between 0 and 0xffffffff because of the say
+  ** that btreeParseCellPtr() and sqlite3GetVarint32() are implemented */
+  if( nCellKey<=0 || nCellKey>0x7fffffff ){
+    *res = 0;
+    return SQLITE_CORRUPT_BKPT;
+  }
+  memset(&m, 0, sizeof(m));
+  rc = sqlite3VdbeMemFromBtree(pC->pCursor, 0, (int)nCellKey, 1, &m);
+  if( rc ){
+    return rc;
+  }
+  assert( pUnpacked->flags & UNPACKED_IGNORE_ROWID );
+  *res = sqlite3VdbeRecordCompare(m.n, m.z, pUnpacked);
+  sqlite3VdbeMemRelease(&m);
+  return SQLITE_OK;
+}
+
+/*
+** This routine sets the value to be returned by subsequent calls to
+** sqlite3_changes() on the database handle 'db'. 
+*/
+SQLITE_PRIVATE void sqlite3VdbeSetChanges(sqlite3 *db, int nChange){
+  assert( sqlite3_mutex_held(db->mutex) );
+  db->nChange = nChange;
+  db->nTotalChange += nChange;
+}
+
+/*
+** Set a flag in the vdbe to update the change counter when it is finalised
+** or reset.
+*/
+SQLITE_PRIVATE void sqlite3VdbeCountChanges(Vdbe *v){
+  v->changeCntOn = 1;
+}
+
+/*
+** Mark every prepared statement associated with a database connection
+** as expired.
+**
+** An expired statement means that recompilation of the statement is
+** recommend.  Statements expire when things happen that make their
+** programs obsolete.  Removing user-defined functions or collating
+** sequences, or changing an authorization function are the types of
+** things that make prepared statements obsolete.
+*/
+SQLITE_PRIVATE void sqlite3ExpirePreparedStatements(sqlite3 *db){
+  Vdbe *p;
+  for(p = db->pVdbe; p; p=p->pNext){
+    p->expired = 1;
+  }
+}
+
+/*
+** Return the database associated with the Vdbe.
+*/
+SQLITE_PRIVATE sqlite3 *sqlite3VdbeDb(Vdbe *v){
+  return v->db;
+}
+
+/*
+** Return a pointer to an sqlite3_value structure containing the value bound
+** parameter iVar of VM v. Except, if the value is an SQL NULL, return 
+** 0 instead. Unless it is NULL, apply affinity aff (one of the SQLITE_AFF_*
+** constants) to the value before returning it.
+**
+** The returned value must be freed by the caller using sqlite3ValueFree().
+*/
+SQLITE_PRIVATE sqlite3_value *sqlite3VdbeGetValue(Vdbe *v, int iVar, u8 aff){
+  assert( iVar>0 );
+  if( v ){
+    Mem *pMem = &v->aVar[iVar-1];
+    if( 0==(pMem->flags & MEM_Null) ){
+      sqlite3_value *pRet = sqlite3ValueNew(v->db);
+      if( pRet ){
+        sqlite3VdbeMemCopy((Mem *)pRet, pMem);
+        sqlite3ValueApplyAffinity(pRet, aff, SQLITE_UTF8);
+        sqlite3VdbeMemStoreType((Mem *)pRet);
+      }
+      return pRet;
+    }
+  }
+  return 0;
+}
+
+/*
+** Configure SQL variable iVar so that binding a new value to it signals
+** to sqlite3_reoptimize() that re-preparing the statement may result
+** in a better query plan.
+*/
+SQLITE_PRIVATE void sqlite3VdbeSetVarmask(Vdbe *v, int iVar){
+  assert( iVar>0 );
+  if( iVar>32 ){
+    v->expmask = 0xffffffff;
+  }else{
+    v->expmask |= ((u32)1 << (iVar-1));
+  }
+}
+
+/************** End of vdbeaux.c *********************************************/
+/************** Begin file vdbeapi.c *****************************************/
+/*
+** 2004 May 26
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains code use to implement APIs that are part of the
+** VDBE.
+*/
+
+#ifndef SQLITE_OMIT_DEPRECATED
+/*
+** Return TRUE (non-zero) of the statement supplied as an argument needs
+** to be recompiled.  A statement needs to be recompiled whenever the
+** execution environment changes in a way that would alter the program
+** that sqlite3_prepare() generates.  For example, if new functions or
+** collating sequences are registered or if an authorizer function is
+** added or changed.
+*/
+SQLITE_API int sqlite3_expired(sqlite3_stmt *pStmt){
+  Vdbe *p = (Vdbe*)pStmt;
+  return p==0 || p->expired;
+}
+#endif
+
+/*
+** Check on a Vdbe to make sure it has not been finalized.  Log
+** an error and return true if it has been finalized (or is otherwise
+** invalid).  Return false if it is ok.
+*/
+static int vdbeSafety(Vdbe *p){
+  if( p->db==0 ){
+    sqlite3_log(SQLITE_MISUSE, "API called with finalized prepared statement");
+    return 1;
+  }else{
+    return 0;
+  }
+}
+static int vdbeSafetyNotNull(Vdbe *p){
+  if( p==0 ){
+    sqlite3_log(SQLITE_MISUSE, "API called with NULL prepared statement");
+    return 1;
+  }else{
+    return vdbeSafety(p);
+  }
+}
+
+/*
+** The following routine destroys a virtual machine that is created by
+** the sqlite3_compile() routine. The integer returned is an SQLITE_
+** success/failure code that describes the result of executing the virtual
+** machine.
+**
+** This routine sets the error code and string returned by
+** sqlite3_errcode(), sqlite3_errmsg() and sqlite3_errmsg16().
+*/
+SQLITE_API int sqlite3_finalize(sqlite3_stmt *pStmt){
+  int rc;
+  if( pStmt==0 ){
+    /* IMPLEMENTATION-OF: R-57228-12904 Invoking sqlite3_finalize() on a NULL
+    ** pointer is a harmless no-op. */
+    rc = SQLITE_OK;
+  }else{
+    Vdbe *v = (Vdbe*)pStmt;
+    sqlite3 *db = v->db;
+#if SQLITE_THREADSAFE
+    sqlite3_mutex *mutex;
+#endif
+    if( vdbeSafety(v) ) return SQLITE_MISUSE_BKPT;
+#if SQLITE_THREADSAFE
+    mutex = v->db->mutex;
+#endif
+    sqlite3_mutex_enter(mutex);
+    rc = sqlite3VdbeFinalize(v);
+    rc = sqlite3ApiExit(db, rc);
+    sqlite3_mutex_leave(mutex);
+  }
+  return rc;
+}
+
+/*
+** Terminate the current execution of an SQL statement and reset it
+** back to its starting state so that it can be reused. A success code from
+** the prior execution is returned.
+**
+** This routine sets the error code and string returned by
+** sqlite3_errcode(), sqlite3_errmsg() and sqlite3_errmsg16().
+*/
+SQLITE_API int sqlite3_reset(sqlite3_stmt *pStmt){
+  int rc;
+  if( pStmt==0 ){
+    rc = SQLITE_OK;
+  }else{
+    Vdbe *v = (Vdbe*)pStmt;
+    sqlite3_mutex_enter(v->db->mutex);
+    rc = sqlite3VdbeReset(v);
+    sqlite3VdbeMakeReady(v, -1, 0, 0, 0, 0, 0);
+    assert( (rc & (v->db->errMask))==rc );
+    rc = sqlite3ApiExit(v->db, rc);
+    sqlite3_mutex_leave(v->db->mutex);
+  }
+  return rc;
+}
+
+/*
+** Set all the parameters in the compiled SQL statement to NULL.
+*/
+SQLITE_API int sqlite3_clear_bindings(sqlite3_stmt *pStmt){
+  int i;
+  int rc = SQLITE_OK;
+  Vdbe *p = (Vdbe*)pStmt;
+#if SQLITE_THREADSAFE
+  sqlite3_mutex *mutex = ((Vdbe*)pStmt)->db->mutex;
+#endif
+  sqlite3_mutex_enter(mutex);
+  for(i=0; i<p->nVar; i++){
+    sqlite3VdbeMemRelease(&p->aVar[i]);
+    p->aVar[i].flags = MEM_Null;
+  }
+  if( p->isPrepareV2 && p->expmask ){
+    p->expired = 1;
+  }
+  sqlite3_mutex_leave(mutex);
+  return rc;
+}
+
+
+/**************************** sqlite3_value_  *******************************
+** The following routines extract information from a Mem or sqlite3_value
+** structure.
+*/
+SQLITE_API const void *sqlite3_value_blob(sqlite3_value *pVal){
+  Mem *p = (Mem*)pVal;
+  if( p->flags & (MEM_Blob|MEM_Str) ){
+    sqlite3VdbeMemExpandBlob(p);
+    p->flags &= ~MEM_Str;
+    p->flags |= MEM_Blob;
+    return p->n ? p->z : 0;
+  }else{
+    return sqlite3_value_text(pVal);
+  }
+}
+SQLITE_API int sqlite3_value_bytes(sqlite3_value *pVal){
+  return sqlite3ValueBytes(pVal, SQLITE_UTF8);
+}
+SQLITE_API int sqlite3_value_bytes16(sqlite3_value *pVal){
+  return sqlite3ValueBytes(pVal, SQLITE_UTF16NATIVE);
+}
+SQLITE_API double sqlite3_value_double(sqlite3_value *pVal){
+  return sqlite3VdbeRealValue((Mem*)pVal);
+}
+SQLITE_API int sqlite3_value_int(sqlite3_value *pVal){
+  return (int)sqlite3VdbeIntValue((Mem*)pVal);
+}
+SQLITE_API sqlite_int64 sqlite3_value_int64(sqlite3_value *pVal){
+  return sqlite3VdbeIntValue((Mem*)pVal);
+}
+SQLITE_API const unsigned char *sqlite3_value_text(sqlite3_value *pVal){
+  return (const unsigned char *)sqlite3ValueText(pVal, SQLITE_UTF8);
+}
+#ifndef SQLITE_OMIT_UTF16
+SQLITE_API const void *sqlite3_value_text16(sqlite3_value* pVal){
+  return sqlite3ValueText(pVal, SQLITE_UTF16NATIVE);
+}
+SQLITE_API const void *sqlite3_value_text16be(sqlite3_value *pVal){
+  return sqlite3ValueText(pVal, SQLITE_UTF16BE);
+}
+SQLITE_API const void *sqlite3_value_text16le(sqlite3_value *pVal){
+  return sqlite3ValueText(pVal, SQLITE_UTF16LE);
+}
+#endif /* SQLITE_OMIT_UTF16 */
+SQLITE_API int sqlite3_value_type(sqlite3_value* pVal){
+  return pVal->type;
+}
+
+/**************************** sqlite3_result_  *******************************
+** The following routines are used by user-defined functions to specify
+** the function result.
+**
+** The setStrOrError() funtion calls sqlite3VdbeMemSetStr() to store the
+** result as a string or blob but if the string or blob is too large, it
+** then sets the error code to SQLITE_TOOBIG
+*/
+static void setResultStrOrError(
+  sqlite3_context *pCtx,  /* Function context */
+  const char *z,          /* String pointer */
+  int n,                  /* Bytes in string, or negative */
+  u8 enc,                 /* Encoding of z.  0 for BLOBs */
+  void (*xDel)(void*)     /* Destructor function */
+){
+  if( sqlite3VdbeMemSetStr(&pCtx->s, z, n, enc, xDel)==SQLITE_TOOBIG ){
+    sqlite3_result_error_toobig(pCtx);
+  }
+}
+SQLITE_API void sqlite3_result_blob(
+  sqlite3_context *pCtx, 
+  const void *z, 
+  int n, 
+  void (*xDel)(void *)
+){
+  assert( n>=0 );
+  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
+  setResultStrOrError(pCtx, z, n, 0, xDel);
+}
+SQLITE_API void sqlite3_result_double(sqlite3_context *pCtx, double rVal){
+  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
+  sqlite3VdbeMemSetDouble(&pCtx->s, rVal);
+}
+SQLITE_API void sqlite3_result_error(sqlite3_context *pCtx, const char *z, int n){
+  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
+  pCtx->isError = SQLITE_ERROR;
+  sqlite3VdbeMemSetStr(&pCtx->s, z, n, SQLITE_UTF8, SQLITE_TRANSIENT);
+}
+#ifndef SQLITE_OMIT_UTF16
+SQLITE_API void sqlite3_result_error16(sqlite3_context *pCtx, const void *z, int n){
+  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
+  pCtx->isError = SQLITE_ERROR;
+  sqlite3VdbeMemSetStr(&pCtx->s, z, n, SQLITE_UTF16NATIVE, SQLITE_TRANSIENT);
+}
+#endif
+SQLITE_API void sqlite3_result_int(sqlite3_context *pCtx, int iVal){
+  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
+  sqlite3VdbeMemSetInt64(&pCtx->s, (i64)iVal);
+}
+SQLITE_API void sqlite3_result_int64(sqlite3_context *pCtx, i64 iVal){
+  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
+  sqlite3VdbeMemSetInt64(&pCtx->s, iVal);
+}
+SQLITE_API void sqlite3_result_null(sqlite3_context *pCtx){
+  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
+  sqlite3VdbeMemSetNull(&pCtx->s);
+}
+SQLITE_API void sqlite3_result_text(
+  sqlite3_context *pCtx, 
+  const char *z, 
+  int n,
+  void (*xDel)(void *)
+){
+  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
+  setResultStrOrError(pCtx, z, n, SQLITE_UTF8, xDel);
+}
+#ifndef SQLITE_OMIT_UTF16
+SQLITE_API void sqlite3_result_text16(
+  sqlite3_context *pCtx, 
+  const void *z, 
+  int n, 
+  void (*xDel)(void *)
+){
+  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
+  setResultStrOrError(pCtx, z, n, SQLITE_UTF16NATIVE, xDel);
+}
+SQLITE_API void sqlite3_result_text16be(
+  sqlite3_context *pCtx, 
+  const void *z, 
+  int n, 
+  void (*xDel)(void *)
+){
+  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
+  setResultStrOrError(pCtx, z, n, SQLITE_UTF16BE, xDel);
+}
+SQLITE_API void sqlite3_result_text16le(
+  sqlite3_context *pCtx, 
+  const void *z, 
+  int n, 
+  void (*xDel)(void *)
+){
+  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
+  setResultStrOrError(pCtx, z, n, SQLITE_UTF16LE, xDel);
+}
+#endif /* SQLITE_OMIT_UTF16 */
+SQLITE_API void sqlite3_result_value(sqlite3_context *pCtx, sqlite3_value *pValue){
+  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
+  sqlite3VdbeMemCopy(&pCtx->s, pValue);
+}
+SQLITE_API void sqlite3_result_zeroblob(sqlite3_context *pCtx, int n){
+  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
+  sqlite3VdbeMemSetZeroBlob(&pCtx->s, n);
+}
+SQLITE_API void sqlite3_result_error_code(sqlite3_context *pCtx, int errCode){
+  pCtx->isError = errCode;
+  if( pCtx->s.flags & MEM_Null ){
+    sqlite3VdbeMemSetStr(&pCtx->s, sqlite3ErrStr(errCode), -1, 
+                         SQLITE_UTF8, SQLITE_STATIC);
+  }
+}
+
+/* Force an SQLITE_TOOBIG error. */
+SQLITE_API void sqlite3_result_error_toobig(sqlite3_context *pCtx){
+  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
+  pCtx->isError = SQLITE_TOOBIG;
+  sqlite3VdbeMemSetStr(&pCtx->s, "string or blob too big", -1, 
+                       SQLITE_UTF8, SQLITE_STATIC);
+}
+
+/* An SQLITE_NOMEM error. */
+SQLITE_API void sqlite3_result_error_nomem(sqlite3_context *pCtx){
+  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
+  sqlite3VdbeMemSetNull(&pCtx->s);
+  pCtx->isError = SQLITE_NOMEM;
+  pCtx->s.db->mallocFailed = 1;
+}
+
+/*
+** This function is called after a transaction has been committed. It 
+** invokes callbacks registered with sqlite3_wal_hook() as required.
+*/
+static int doWalCallbacks(sqlite3 *db){
+  int rc = SQLITE_OK;
+#ifndef SQLITE_OMIT_WAL
+  int i;
+  for(i=0; i<db->nDb; i++){
+    Btree *pBt = db->aDb[i].pBt;
+    if( pBt ){
+      int nEntry = sqlite3PagerWalCallback(sqlite3BtreePager(pBt));
+      if( db->xWalCallback && nEntry>0 && rc==SQLITE_OK ){
+        rc = db->xWalCallback(db->pWalArg, db, db->aDb[i].zName, nEntry);
+      }
+    }
+  }
+#endif
+  return rc;
+}
+
+/*
+** Execute the statement pStmt, either until a row of data is ready, the
+** statement is completely executed or an error occurs.
+**
+** This routine implements the bulk of the logic behind the sqlite_step()
+** API.  The only thing omitted is the automatic recompile if a 
+** schema change has occurred.  That detail is handled by the
+** outer sqlite3_step() wrapper procedure.
+*/
+static int sqlite3Step(Vdbe *p){
+  sqlite3 *db;
+  int rc;
+
+  assert(p);
+  if( p->magic!=VDBE_MAGIC_RUN ){
+    /* We used to require that sqlite3_reset() be called before retrying
+    ** sqlite3_step() after any error or after SQLITE_DONE.  But beginning
+    ** with version 3.7.0, we changed this so that sqlite3_reset() would
+    ** be called automatically instead of throwing the SQLITE_MISUSE error.
+    ** This "automatic-reset" change is not technically an incompatibility, 
+    ** since any application that receives an SQLITE_MISUSE is broken by
+    ** definition.
+    **
+    ** Nevertheless, some published applications that were originally written
+    ** for version 3.6.23 or earlier do in fact depend on SQLITE_MISUSE 
+    ** returns, and the so were broken by the automatic-reset change.  As a
+    ** a work-around, the SQLITE_OMIT_AUTORESET compile-time restores the
+    ** legacy behavior of returning SQLITE_MISUSE for cases where the 
+    ** previous sqlite3_step() returned something other than a SQLITE_LOCKED
+    ** or SQLITE_BUSY error.
+    */
+#ifdef SQLITE_OMIT_AUTORESET
+    if( p->rc==SQLITE_BUSY || p->rc==SQLITE_LOCKED ){
+      sqlite3_reset((sqlite3_stmt*)p);
+    }else{
+      return SQLITE_MISUSE_BKPT;
+    }
+#else
+    sqlite3_reset((sqlite3_stmt*)p);
+#endif
+  }
+
+  /* Check that malloc() has not failed. If it has, return early. */
+  db = p->db;
+  if( db->mallocFailed ){
+    p->rc = SQLITE_NOMEM;
+    return SQLITE_NOMEM;
+  }
+
+  if( p->pc<=0 && p->expired ){
+    p->rc = SQLITE_SCHEMA;
+    rc = SQLITE_ERROR;
+    goto end_of_step;
+  }
+  if( p->pc<0 ){
+    /* If there are no other statements currently running, then
+    ** reset the interrupt flag.  This prevents a call to sqlite3_interrupt
+    ** from interrupting a statement that has not yet started.
+    */
+    if( db->activeVdbeCnt==0 ){
+      db->u1.isInterrupted = 0;
+    }
+
+    assert( db->writeVdbeCnt>0 || db->autoCommit==0 || db->nDeferredCons==0 );
+
+#ifndef SQLITE_OMIT_TRACE
+    if( db->xProfile && !db->init.busy ){
+      sqlite3OsCurrentTimeInt64(db->pVfs, &p->startTime);
+    }
+#endif
+
+    db->activeVdbeCnt++;
+    if( p->readOnly==0 ) db->writeVdbeCnt++;
+    p->pc = 0;
+  }
+#ifndef SQLITE_OMIT_EXPLAIN
+  if( p->explain ){
+    rc = sqlite3VdbeList(p);
+  }else
+#endif /* SQLITE_OMIT_EXPLAIN */
+  {
+    db->vdbeExecCnt++;
+    rc = sqlite3VdbeExec(p);
+    db->vdbeExecCnt--;
+  }
+
+#ifndef SQLITE_OMIT_TRACE
+  /* Invoke the profile callback if there is one
+  */
+  if( rc!=SQLITE_ROW && db->xProfile && !db->init.busy && p->zSql ){
+    sqlite3_int64 iNow;
+    sqlite3OsCurrentTimeInt64(db->pVfs, &iNow);
+    db->xProfile(db->pProfileArg, p->zSql, (iNow - p->startTime)*1000000);
+  }
+#endif
+
+  if( rc==SQLITE_DONE ){
+    assert( p->rc==SQLITE_OK );
+    p->rc = doWalCallbacks(db);
+    if( p->rc!=SQLITE_OK ){
+      rc = SQLITE_ERROR;
+    }
+  }
+
+  db->errCode = rc;
+  if( SQLITE_NOMEM==sqlite3ApiExit(p->db, p->rc) ){
+    p->rc = SQLITE_NOMEM;
+  }
+end_of_step:
+  /* At this point local variable rc holds the value that should be 
+  ** returned if this statement was compiled using the legacy 
+  ** sqlite3_prepare() interface. According to the docs, this can only
+  ** be one of the values in the first assert() below. Variable p->rc 
+  ** contains the value that would be returned if sqlite3_finalize() 
+  ** were called on statement p.
+  */
+  assert( rc==SQLITE_ROW  || rc==SQLITE_DONE   || rc==SQLITE_ERROR 
+       || rc==SQLITE_BUSY || rc==SQLITE_MISUSE
+  );
+  assert( p->rc!=SQLITE_ROW && p->rc!=SQLITE_DONE );
+  if( p->isPrepareV2 && rc!=SQLITE_ROW && rc!=SQLITE_DONE ){
+    /* If this statement was prepared using sqlite3_prepare_v2(), and an
+    ** error has occured, then return the error code in p->rc to the
+    ** caller. Set the error code in the database handle to the same value.
+    */ 
+    rc = db->errCode = p->rc;
+  }
+  return (rc&db->errMask);
+}
+
+/*
+** This is the top-level implementation of sqlite3_step().  Call
+** sqlite3Step() to do most of the work.  If a schema error occurs,
+** call sqlite3Reprepare() and try again.
+*/
+SQLITE_API int sqlite3_step(sqlite3_stmt *pStmt){
+  int rc = SQLITE_OK;      /* Result from sqlite3Step() */
+  int rc2 = SQLITE_OK;     /* Result from sqlite3Reprepare() */
+  Vdbe *v = (Vdbe*)pStmt;  /* the prepared statement */
+  int cnt = 0;             /* Counter to prevent infinite loop of reprepares */
+  sqlite3 *db;             /* The database connection */
+
+  if( vdbeSafetyNotNull(v) ){
+    return SQLITE_MISUSE_BKPT;
+  }
+  db = v->db;
+  sqlite3_mutex_enter(db->mutex);
+  while( (rc = sqlite3Step(v))==SQLITE_SCHEMA
+         && cnt++ < 5
+         && (rc2 = rc = sqlite3Reprepare(v))==SQLITE_OK ){
+    sqlite3_reset(pStmt);
+    v->expired = 0;
+  }
+  if( rc2!=SQLITE_OK && ALWAYS(v->isPrepareV2) && ALWAYS(db->pErr) ){
+    /* This case occurs after failing to recompile an sql statement. 
+    ** The error message from the SQL compiler has already been loaded 
+    ** into the database handle. This block copies the error message 
+    ** from the database handle into the statement and sets the statement
+    ** program counter to 0 to ensure that when the statement is 
+    ** finalized or reset the parser error message is available via
+    ** sqlite3_errmsg() and sqlite3_errcode().
+    */
+    const char *zErr = (const char *)sqlite3_value_text(db->pErr); 
+    sqlite3DbFree(db, v->zErrMsg);
+    if( !db->mallocFailed ){
+      v->zErrMsg = sqlite3DbStrDup(db, zErr);
+      v->rc = rc2;
+    } else {
+      v->zErrMsg = 0;
+      v->rc = rc = SQLITE_NOMEM;
+    }
+  }
+  rc = sqlite3ApiExit(db, rc);
+  sqlite3_mutex_leave(db->mutex);
+  return rc;
+}
+
+/*
+** Extract the user data from a sqlite3_context structure and return a
+** pointer to it.
+*/
+SQLITE_API void *sqlite3_user_data(sqlite3_context *p){
+  assert( p && p->pFunc );
+  return p->pFunc->pUserData;
+}
+
+/*
+** Extract the user data from a sqlite3_context structure and return a
+** pointer to it.
+**
+** IMPLEMENTATION-OF: R-46798-50301 The sqlite3_context_db_handle() interface
+** returns a copy of the pointer to the database connection (the 1st
+** parameter) of the sqlite3_create_function() and
+** sqlite3_create_function16() routines that originally registered the
+** application defined function.
+*/
+SQLITE_API sqlite3 *sqlite3_context_db_handle(sqlite3_context *p){
+  assert( p && p->pFunc );
+  return p->s.db;
+}
+
+/*
+** The following is the implementation of an SQL function that always
+** fails with an error message stating that the function is used in the
+** wrong context.  The sqlite3_overload_function() API might construct
+** SQL function that use this routine so that the functions will exist
+** for name resolution but are actually overloaded by the xFindFunction
+** method of virtual tables.
+*/
+SQLITE_PRIVATE void sqlite3InvalidFunction(
+  sqlite3_context *context,  /* The function calling context */
+  int NotUsed,               /* Number of arguments to the function */
+  sqlite3_value **NotUsed2   /* Value of each argument */
+){
+  const char *zName = context->pFunc->zName;
+  char *zErr;
+  UNUSED_PARAMETER2(NotUsed, NotUsed2);
+  zErr = sqlite3_mprintf(
+      "unable to use function %s in the requested context", zName);
+  sqlite3_result_error(context, zErr, -1);
+  sqlite3_free(zErr);
+}
+
+/*
+** Allocate or return the aggregate context for a user function.  A new
+** context is allocated on the first call.  Subsequent calls return the
+** same context that was returned on prior calls.
+*/
+SQLITE_API void *sqlite3_aggregate_context(sqlite3_context *p, int nByte){
+  Mem *pMem;
+  assert( p && p->pFunc && p->pFunc->xStep );
+  assert( sqlite3_mutex_held(p->s.db->mutex) );
+  pMem = p->pMem;
+  testcase( nByte<0 );
+  if( (pMem->flags & MEM_Agg)==0 ){
+    if( nByte<=0 ){
+      sqlite3VdbeMemReleaseExternal(pMem);
+      pMem->flags = MEM_Null;
+      pMem->z = 0;
+    }else{
+      sqlite3VdbeMemGrow(pMem, nByte, 0);
+      pMem->flags = MEM_Agg;
+      pMem->u.pDef = p->pFunc;
+      if( pMem->z ){
+        memset(pMem->z, 0, nByte);
+      }
+    }
+  }
+  return (void*)pMem->z;
+}
+
+/*
+** Return the auxilary data pointer, if any, for the iArg'th argument to
+** the user-function defined by pCtx.
+*/
+SQLITE_API void *sqlite3_get_auxdata(sqlite3_context *pCtx, int iArg){
+  VdbeFunc *pVdbeFunc;
+
+  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
+  pVdbeFunc = pCtx->pVdbeFunc;
+  if( !pVdbeFunc || iArg>=pVdbeFunc->nAux || iArg<0 ){
+    return 0;
+  }
+  return pVdbeFunc->apAux[iArg].pAux;
+}
+
+/*
+** Set the auxilary data pointer and delete function, for the iArg'th
+** argument to the user-function defined by pCtx. Any previous value is
+** deleted by calling the delete function specified when it was set.
+*/
+SQLITE_API void sqlite3_set_auxdata(
+  sqlite3_context *pCtx, 
+  int iArg, 
+  void *pAux, 
+  void (*xDelete)(void*)
+){
+  struct AuxData *pAuxData;
+  VdbeFunc *pVdbeFunc;
+  if( iArg<0 ) goto failed;
+
+  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
+  pVdbeFunc = pCtx->pVdbeFunc;
+  if( !pVdbeFunc || pVdbeFunc->nAux<=iArg ){
+    int nAux = (pVdbeFunc ? pVdbeFunc->nAux : 0);
+    int nMalloc = sizeof(VdbeFunc) + sizeof(struct AuxData)*iArg;
+    pVdbeFunc = sqlite3DbRealloc(pCtx->s.db, pVdbeFunc, nMalloc);
+    if( !pVdbeFunc ){
+      goto failed;
+    }
+    pCtx->pVdbeFunc = pVdbeFunc;
+    memset(&pVdbeFunc->apAux[nAux], 0, sizeof(struct AuxData)*(iArg+1-nAux));
+    pVdbeFunc->nAux = iArg+1;
+    pVdbeFunc->pFunc = pCtx->pFunc;
+  }
+
+  pAuxData = &pVdbeFunc->apAux[iArg];
+  if( pAuxData->pAux && pAuxData->xDelete ){
+    pAuxData->xDelete(pAuxData->pAux);
+  }
+  pAuxData->pAux = pAux;
+  pAuxData->xDelete = xDelete;
+  return;
+
+failed:
+  if( xDelete ){
+    xDelete(pAux);
+  }
+}
+
+#ifndef SQLITE_OMIT_DEPRECATED
+/*
+** Return the number of times the Step function of a aggregate has been 
+** called.
+**
+** This function is deprecated.  Do not use it for new code.  It is
+** provide only to avoid breaking legacy code.  New aggregate function
+** implementations should keep their own counts within their aggregate
+** context.
+*/
+SQLITE_API int sqlite3_aggregate_count(sqlite3_context *p){
+  assert( p && p->pMem && p->pFunc && p->pFunc->xStep );
+  return p->pMem->n;
+}
+#endif
+
+/*
+** Return the number of columns in the result set for the statement pStmt.
+*/
+SQLITE_API int sqlite3_column_count(sqlite3_stmt *pStmt){
+  Vdbe *pVm = (Vdbe *)pStmt;
+  return pVm ? pVm->nResColumn : 0;
+}
+
+/*
+** Return the number of values available from the current row of the
+** currently executing statement pStmt.
+*/
+SQLITE_API int sqlite3_data_count(sqlite3_stmt *pStmt){
+  Vdbe *pVm = (Vdbe *)pStmt;
+  if( pVm==0 || pVm->pResultSet==0 ) return 0;
+  return pVm->nResColumn;
+}
+
+
+/*
+** Check to see if column iCol of the given statement is valid.  If
+** it is, return a pointer to the Mem for the value of that column.
+** If iCol is not valid, return a pointer to a Mem which has a value
+** of NULL.
+*/
+static Mem *columnMem(sqlite3_stmt *pStmt, int i){
+  Vdbe *pVm;
+  Mem *pOut;
+
+  pVm = (Vdbe *)pStmt;
+  if( pVm && pVm->pResultSet!=0 && i<pVm->nResColumn && i>=0 ){
+    sqlite3_mutex_enter(pVm->db->mutex);
+    pOut = &pVm->pResultSet[i];
+  }else{
+    /* If the value passed as the second argument is out of range, return
+    ** a pointer to the following static Mem object which contains the
+    ** value SQL NULL. Even though the Mem structure contains an element
+    ** of type i64, on certain architecture (x86) with certain compiler
+    ** switches (-Os), gcc may align this Mem object on a 4-byte boundary
+    ** instead of an 8-byte one. This all works fine, except that when
+    ** running with SQLITE_DEBUG defined the SQLite code sometimes assert()s
+    ** that a Mem structure is located on an 8-byte boundary. To prevent
+    ** this assert() from failing, when building with SQLITE_DEBUG defined
+    ** using gcc, force nullMem to be 8-byte aligned using the magical
+    ** __attribute__((aligned(8))) macro.  */
+    static const Mem nullMem 
+#if defined(SQLITE_DEBUG) && defined(__GNUC__)
+      __attribute__((aligned(8))) 
+#endif
+      = {0, "", (double)0, {0}, 0, MEM_Null, SQLITE_NULL, 0,
+#ifdef SQLITE_DEBUG
+         0, 0,  /* pScopyFrom, pFiller */
+#endif
+         0, 0 };
+
+    if( pVm && ALWAYS(pVm->db) ){
+      sqlite3_mutex_enter(pVm->db->mutex);
+      sqlite3Error(pVm->db, SQLITE_RANGE, 0);
+    }
+    pOut = (Mem*)&nullMem;
+  }
+  return pOut;
+}
+
+/*
+** This function is called after invoking an sqlite3_value_XXX function on a 
+** column value (i.e. a value returned by evaluating an SQL expression in the
+** select list of a SELECT statement) that may cause a malloc() failure. If 
+** malloc() has failed, the threads mallocFailed flag is cleared and the result
+** code of statement pStmt set to SQLITE_NOMEM.
+**
+** Specifically, this is called from within:
+**
+**     sqlite3_column_int()
+**     sqlite3_column_int64()
+**     sqlite3_column_text()
+**     sqlite3_column_text16()
+**     sqlite3_column_real()
+**     sqlite3_column_bytes()
+**     sqlite3_column_bytes16()
+**     sqiite3_column_blob()
+*/
+static void columnMallocFailure(sqlite3_stmt *pStmt)
+{
+  /* If malloc() failed during an encoding conversion within an
+  ** sqlite3_column_XXX API, then set the return code of the statement to
+  ** SQLITE_NOMEM. The next call to _step() (if any) will return SQLITE_ERROR
+  ** and _finalize() will return NOMEM.
+  */
+  Vdbe *p = (Vdbe *)pStmt;
+  if( p ){
+    p->rc = sqlite3ApiExit(p->db, p->rc);
+    sqlite3_mutex_leave(p->db->mutex);
+  }
+}
+
+/**************************** sqlite3_column_  *******************************
+** The following routines are used to access elements of the current row
+** in the result set.
+*/
+SQLITE_API const void *sqlite3_column_blob(sqlite3_stmt *pStmt, int i){
+  const void *val;
+  val = sqlite3_value_blob( columnMem(pStmt,i) );
+  /* Even though there is no encoding conversion, value_blob() might
+  ** need to call malloc() to expand the result of a zeroblob() 
+  ** expression. 
+  */
+  columnMallocFailure(pStmt);
+  return val;
+}
+SQLITE_API int sqlite3_column_bytes(sqlite3_stmt *pStmt, int i){
+  int val = sqlite3_value_bytes( columnMem(pStmt,i) );
+  columnMallocFailure(pStmt);
+  return val;
+}
+SQLITE_API int sqlite3_column_bytes16(sqlite3_stmt *pStmt, int i){
+  int val = sqlite3_value_bytes16( columnMem(pStmt,i) );
+  columnMallocFailure(pStmt);
+  return val;
+}
+SQLITE_API double sqlite3_column_double(sqlite3_stmt *pStmt, int i){
+  double val = sqlite3_value_double( columnMem(pStmt,i) );
+  columnMallocFailure(pStmt);
+  return val;
+}
+SQLITE_API int sqlite3_column_int(sqlite3_stmt *pStmt, int i){
+  int val = sqlite3_value_int( columnMem(pStmt,i) );
+  columnMallocFailure(pStmt);
+  return val;
+}
+SQLITE_API sqlite_int64 sqlite3_column_int64(sqlite3_stmt *pStmt, int i){
+  sqlite_int64 val = sqlite3_value_int64( columnMem(pStmt,i) );
+  columnMallocFailure(pStmt);
+  return val;
+}
+SQLITE_API const unsigned char *sqlite3_column_text(sqlite3_stmt *pStmt, int i){
+  const unsigned char *val = sqlite3_value_text( columnMem(pStmt,i) );
+  columnMallocFailure(pStmt);
+  return val;
+}
+SQLITE_API sqlite3_value *sqlite3_column_value(sqlite3_stmt *pStmt, int i){
+  Mem *pOut = columnMem(pStmt, i);
+  if( pOut->flags&MEM_Static ){
+    pOut->flags &= ~MEM_Static;
+    pOut->flags |= MEM_Ephem;
+  }
+  columnMallocFailure(pStmt);
+  return (sqlite3_value *)pOut;
+}
+#ifndef SQLITE_OMIT_UTF16
+SQLITE_API const void *sqlite3_column_text16(sqlite3_stmt *pStmt, int i){
+  const void *val = sqlite3_value_text16( columnMem(pStmt,i) );
+  columnMallocFailure(pStmt);
+  return val;
+}
+#endif /* SQLITE_OMIT_UTF16 */
+SQLITE_API int sqlite3_column_type(sqlite3_stmt *pStmt, int i){
+  int iType = sqlite3_value_type( columnMem(pStmt,i) );
+  columnMallocFailure(pStmt);
+  return iType;
+}
+
+/* The following function is experimental and subject to change or
+** removal */
+/*int sqlite3_column_numeric_type(sqlite3_stmt *pStmt, int i){
+**  return sqlite3_value_numeric_type( columnMem(pStmt,i) );
+**}
+*/
+
+/*
+** Convert the N-th element of pStmt->pColName[] into a string using
+** xFunc() then return that string.  If N is out of range, return 0.
+**
+** There are up to 5 names for each column.  useType determines which
+** name is returned.  Here are the names:
+**
+**    0      The column name as it should be displayed for output
+**    1      The datatype name for the column
+**    2      The name of the database that the column derives from
+**    3      The name of the table that the column derives from
+**    4      The name of the table column that the result column derives from
+**
+** If the result is not a simple column reference (if it is an expression
+** or a constant) then useTypes 2, 3, and 4 return NULL.
+*/
+static const void *columnName(
+  sqlite3_stmt *pStmt,
+  int N,
+  const void *(*xFunc)(Mem*),
+  int useType
+){
+  const void *ret = 0;
+  Vdbe *p = (Vdbe *)pStmt;
+  int n;
+  sqlite3 *db = p->db;
+  
+  assert( db!=0 );
+  n = sqlite3_column_count(pStmt);
+  if( N<n && N>=0 ){
+    N += useType*n;
+    sqlite3_mutex_enter(db->mutex);
+    assert( db->mallocFailed==0 );
+    ret = xFunc(&p->aColName[N]);
+     /* A malloc may have failed inside of the xFunc() call. If this
+    ** is the case, clear the mallocFailed flag and return NULL.
+    */
+    if( db->mallocFailed ){
+      db->mallocFailed = 0;
+      ret = 0;
+    }
+    sqlite3_mutex_leave(db->mutex);
+  }
+  return ret;
+}
+
+/*
+** Return the name of the Nth column of the result set returned by SQL
+** statement pStmt.
+*/
+SQLITE_API const char *sqlite3_column_name(sqlite3_stmt *pStmt, int N){
+  return columnName(
+      pStmt, N, (const void*(*)(Mem*))sqlite3_value_text, COLNAME_NAME);
+}
+#ifndef SQLITE_OMIT_UTF16
+SQLITE_API const void *sqlite3_column_name16(sqlite3_stmt *pStmt, int N){
+  return columnName(
+      pStmt, N, (const void*(*)(Mem*))sqlite3_value_text16, COLNAME_NAME);
+}
+#endif
+
+/*
+** Constraint:  If you have ENABLE_COLUMN_METADATA then you must
+** not define OMIT_DECLTYPE.
+*/
+#if defined(SQLITE_OMIT_DECLTYPE) && defined(SQLITE_ENABLE_COLUMN_METADATA)
+# error "Must not define both SQLITE_OMIT_DECLTYPE \
+         and SQLITE_ENABLE_COLUMN_METADATA"
+#endif
+
+#ifndef SQLITE_OMIT_DECLTYPE
+/*
+** Return the column declaration type (if applicable) of the 'i'th column
+** of the result set of SQL statement pStmt.
+*/
+SQLITE_API const char *sqlite3_column_decltype(sqlite3_stmt *pStmt, int N){
+  return columnName(
+      pStmt, N, (const void*(*)(Mem*))sqlite3_value_text, COLNAME_DECLTYPE);
+}
+#ifndef SQLITE_OMIT_UTF16
+SQLITE_API const void *sqlite3_column_decltype16(sqlite3_stmt *pStmt, int N){
+  return columnName(
+      pStmt, N, (const void*(*)(Mem*))sqlite3_value_text16, COLNAME_DECLTYPE);
+}
+#endif /* SQLITE_OMIT_UTF16 */
+#endif /* SQLITE_OMIT_DECLTYPE */
+
+#ifdef SQLITE_ENABLE_COLUMN_METADATA
+/*
+** Return the name of the database from which a result column derives.
+** NULL is returned if the result column is an expression or constant or
+** anything else which is not an unabiguous reference to a database column.
+*/
+SQLITE_API const char *sqlite3_column_database_name(sqlite3_stmt *pStmt, int N){
+  return columnName(
+      pStmt, N, (const void*(*)(Mem*))sqlite3_value_text, COLNAME_DATABASE);
+}
+#ifndef SQLITE_OMIT_UTF16
+SQLITE_API const void *sqlite3_column_database_name16(sqlite3_stmt *pStmt, int N){
+  return columnName(
+      pStmt, N, (const void*(*)(Mem*))sqlite3_value_text16, COLNAME_DATABASE);
+}
+#endif /* SQLITE_OMIT_UTF16 */
+
+/*
+** Return the name of the table from which a result column derives.
+** NULL is returned if the result column is an expression or constant or
+** anything else which is not an unabiguous reference to a database column.
+*/
+SQLITE_API const char *sqlite3_column_table_name(sqlite3_stmt *pStmt, int N){
+  return columnName(
+      pStmt, N, (const void*(*)(Mem*))sqlite3_value_text, COLNAME_TABLE);
+}
+#ifndef SQLITE_OMIT_UTF16
+SQLITE_API const void *sqlite3_column_table_name16(sqlite3_stmt *pStmt, int N){
+  return columnName(
+      pStmt, N, (const void*(*)(Mem*))sqlite3_value_text16, COLNAME_TABLE);
+}
+#endif /* SQLITE_OMIT_UTF16 */
+
+/*
+** Return the name of the table column from which a result column derives.
+** NULL is returned if the result column is an expression or constant or
+** anything else which is not an unabiguous reference to a database column.
+*/
+SQLITE_API const char *sqlite3_column_origin_name(sqlite3_stmt *pStmt, int N){
+  return columnName(
+      pStmt, N, (const void*(*)(Mem*))sqlite3_value_text, COLNAME_COLUMN);
+}
+#ifndef SQLITE_OMIT_UTF16
+SQLITE_API const void *sqlite3_column_origin_name16(sqlite3_stmt *pStmt, int N){
+  return columnName(
+      pStmt, N, (const void*(*)(Mem*))sqlite3_value_text16, COLNAME_COLUMN);
+}
+#endif /* SQLITE_OMIT_UTF16 */
+#endif /* SQLITE_ENABLE_COLUMN_METADATA */
+
+
+/******************************* sqlite3_bind_  ***************************
+** 
+** Routines used to attach values to wildcards in a compiled SQL statement.
+*/
+/*
+** Unbind the value bound to variable i in virtual machine p. This is the 
+** the same as binding a NULL value to the column. If the "i" parameter is
+** out of range, then SQLITE_RANGE is returned. Othewise SQLITE_OK.
+**
+** A successful evaluation of this routine acquires the mutex on p.
+** the mutex is released if any kind of error occurs.
+**
+** The error code stored in database p->db is overwritten with the return
+** value in any case.
+*/
+static int vdbeUnbind(Vdbe *p, int i){
+  Mem *pVar;
+  if( vdbeSafetyNotNull(p) ){
+    return SQLITE_MISUSE_BKPT;
+  }
+  sqlite3_mutex_enter(p->db->mutex);
+  if( p->magic!=VDBE_MAGIC_RUN || p->pc>=0 ){
+    sqlite3Error(p->db, SQLITE_MISUSE, 0);
+    sqlite3_mutex_leave(p->db->mutex);
+    sqlite3_log(SQLITE_MISUSE, 
+        "bind on a busy prepared statement: [%s]", p->zSql);
+    return SQLITE_MISUSE_BKPT;
+  }
+  if( i<1 || i>p->nVar ){
+    sqlite3Error(p->db, SQLITE_RANGE, 0);
+    sqlite3_mutex_leave(p->db->mutex);
+    return SQLITE_RANGE;
+  }
+  i--;
+  pVar = &p->aVar[i];
+  sqlite3VdbeMemRelease(pVar);
+  pVar->flags = MEM_Null;
+  sqlite3Error(p->db, SQLITE_OK, 0);
+
+  /* If the bit corresponding to this variable in Vdbe.expmask is set, then 
+  ** binding a new value to this variable invalidates the current query plan.
+  **
+  ** IMPLEMENTATION-OF: R-48440-37595 If the specific value bound to host
+  ** parameter in the WHERE clause might influence the choice of query plan
+  ** for a statement, then the statement will be automatically recompiled,
+  ** as if there had been a schema change, on the first sqlite3_step() call
+  ** following any change to the bindings of that parameter.
+  */
+  if( p->isPrepareV2 &&
+     ((i<32 && p->expmask & ((u32)1 << i)) || p->expmask==0xffffffff)
+  ){
+    p->expired = 1;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Bind a text or BLOB value.
+*/
+static int bindText(
+  sqlite3_stmt *pStmt,   /* The statement to bind against */
+  int i,                 /* Index of the parameter to bind */
+  const void *zData,     /* Pointer to the data to be bound */
+  int nData,             /* Number of bytes of data to be bound */
+  void (*xDel)(void*),   /* Destructor for the data */
+  u8 encoding            /* Encoding for the data */
+){
+  Vdbe *p = (Vdbe *)pStmt;
+  Mem *pVar;
+  int rc;
+
+  rc = vdbeUnbind(p, i);
+  if( rc==SQLITE_OK ){
+    if( zData!=0 ){
+      pVar = &p->aVar[i-1];
+      rc = sqlite3VdbeMemSetStr(pVar, zData, nData, encoding, xDel);
+      if( rc==SQLITE_OK && encoding!=0 ){
+        rc = sqlite3VdbeChangeEncoding(pVar, ENC(p->db));
+      }
+      sqlite3Error(p->db, rc, 0);
+      rc = sqlite3ApiExit(p->db, rc);
+    }
+    sqlite3_mutex_leave(p->db->mutex);
+  }else if( xDel!=SQLITE_STATIC && xDel!=SQLITE_TRANSIENT ){
+    xDel((void*)zData);
+  }
+  return rc;
+}
+
+
+/*
+** Bind a blob value to an SQL statement variable.
+*/
+SQLITE_API int sqlite3_bind_blob(
+  sqlite3_stmt *pStmt, 
+  int i, 
+  const void *zData, 
+  int nData, 
+  void (*xDel)(void*)
+){
+  return bindText(pStmt, i, zData, nData, xDel, 0);
+}
+SQLITE_API int sqlite3_bind_double(sqlite3_stmt *pStmt, int i, double rValue){
+  int rc;
+  Vdbe *p = (Vdbe *)pStmt;
+  rc = vdbeUnbind(p, i);
+  if( rc==SQLITE_OK ){
+    sqlite3VdbeMemSetDouble(&p->aVar[i-1], rValue);
+    sqlite3_mutex_leave(p->db->mutex);
+  }
+  return rc;
+}
+SQLITE_API int sqlite3_bind_int(sqlite3_stmt *p, int i, int iValue){
+  return sqlite3_bind_int64(p, i, (i64)iValue);
+}
+SQLITE_API int sqlite3_bind_int64(sqlite3_stmt *pStmt, int i, sqlite_int64 iValue){
+  int rc;
+  Vdbe *p = (Vdbe *)pStmt;
+  rc = vdbeUnbind(p, i);
+  if( rc==SQLITE_OK ){
+    sqlite3VdbeMemSetInt64(&p->aVar[i-1], iValue);
+    sqlite3_mutex_leave(p->db->mutex);
+  }
+  return rc;
+}
+SQLITE_API int sqlite3_bind_null(sqlite3_stmt *pStmt, int i){
+  int rc;
+  Vdbe *p = (Vdbe*)pStmt;
+  rc = vdbeUnbind(p, i);
+  if( rc==SQLITE_OK ){
+    sqlite3_mutex_leave(p->db->mutex);
+  }
+  return rc;
+}
+SQLITE_API int sqlite3_bind_text( 
+  sqlite3_stmt *pStmt, 
+  int i, 
+  const char *zData, 
+  int nData, 
+  void (*xDel)(void*)
+){
+  return bindText(pStmt, i, zData, nData, xDel, SQLITE_UTF8);
+}
+#ifndef SQLITE_OMIT_UTF16
+SQLITE_API int sqlite3_bind_text16(
+  sqlite3_stmt *pStmt, 
+  int i, 
+  const void *zData, 
+  int nData, 
+  void (*xDel)(void*)
+){
+  return bindText(pStmt, i, zData, nData, xDel, SQLITE_UTF16NATIVE);
+}
+#endif /* SQLITE_OMIT_UTF16 */
+SQLITE_API int sqlite3_bind_value(sqlite3_stmt *pStmt, int i, const sqlite3_value *pValue){
+  int rc;
+  switch( pValue->type ){
+    case SQLITE_INTEGER: {
+      rc = sqlite3_bind_int64(pStmt, i, pValue->u.i);
+      break;
+    }
+    case SQLITE_FLOAT: {
+      rc = sqlite3_bind_double(pStmt, i, pValue->r);
+      break;
+    }
+    case SQLITE_BLOB: {
+      if( pValue->flags & MEM_Zero ){
+        rc = sqlite3_bind_zeroblob(pStmt, i, pValue->u.nZero);
+      }else{
+        rc = sqlite3_bind_blob(pStmt, i, pValue->z, pValue->n,SQLITE_TRANSIENT);
+      }
+      break;
+    }
+    case SQLITE_TEXT: {
+      rc = bindText(pStmt,i,  pValue->z, pValue->n, SQLITE_TRANSIENT,
+                              pValue->enc);
+      break;
+    }
+    default: {
+      rc = sqlite3_bind_null(pStmt, i);
+      break;
+    }
+  }
+  return rc;
+}
+SQLITE_API int sqlite3_bind_zeroblob(sqlite3_stmt *pStmt, int i, int n){
+  int rc;
+  Vdbe *p = (Vdbe *)pStmt;
+  rc = vdbeUnbind(p, i);
+  if( rc==SQLITE_OK ){
+    sqlite3VdbeMemSetZeroBlob(&p->aVar[i-1], n);
+    sqlite3_mutex_leave(p->db->mutex);
+  }
+  return rc;
+}
+
+/*
+** Return the number of wildcards that can be potentially bound to.
+** This routine is added to support DBD::SQLite.  
+*/
+SQLITE_API int sqlite3_bind_parameter_count(sqlite3_stmt *pStmt){
+  Vdbe *p = (Vdbe*)pStmt;
+  return p ? p->nVar : 0;
+}
+
+/*
+** Create a mapping from variable numbers to variable names
+** in the Vdbe.azVar[] array, if such a mapping does not already
+** exist.
+*/
+static void createVarMap(Vdbe *p){
+  if( !p->okVar ){
+    int j;
+    Op *pOp;
+    sqlite3_mutex_enter(p->db->mutex);
+    /* The race condition here is harmless.  If two threads call this
+    ** routine on the same Vdbe at the same time, they both might end
+    ** up initializing the Vdbe.azVar[] array.  That is a little extra
+    ** work but it results in the same answer.
+    */
+    for(j=0, pOp=p->aOp; j<p->nOp; j++, pOp++){
+      if( pOp->opcode==OP_Variable ){
+        assert( pOp->p1>0 && pOp->p1<=p->nVar );
+        p->azVar[pOp->p1-1] = pOp->p4.z;
+      }
+    }
+    p->okVar = 1;
+    sqlite3_mutex_leave(p->db->mutex);
+  }
+}
+
+/*
+** Return the name of a wildcard parameter.  Return NULL if the index
+** is out of range or if the wildcard is unnamed.
+**
+** The result is always UTF-8.
+*/
+SQLITE_API const char *sqlite3_bind_parameter_name(sqlite3_stmt *pStmt, int i){
+  Vdbe *p = (Vdbe*)pStmt;
+  if( p==0 || i<1 || i>p->nVar ){
+    return 0;
+  }
+  createVarMap(p);
+  return p->azVar[i-1];
+}
+
+/*
+** Given a wildcard parameter name, return the index of the variable
+** with that name.  If there is no variable with the given name,
+** return 0.
+*/
+SQLITE_PRIVATE int sqlite3VdbeParameterIndex(Vdbe *p, const char *zName, int nName){
+  int i;
+  if( p==0 ){
+    return 0;
+  }
+  createVarMap(p); 
+  if( zName ){
+    for(i=0; i<p->nVar; i++){
+      const char *z = p->azVar[i];
+      if( z && memcmp(z,zName,nName)==0 && z[nName]==0 ){
+        return i+1;
+      }
+    }
+  }
+  return 0;
+}
+SQLITE_API int sqlite3_bind_parameter_index(sqlite3_stmt *pStmt, const char *zName){
+  return sqlite3VdbeParameterIndex((Vdbe*)pStmt, zName, sqlite3Strlen30(zName));
+}
+
+/*
+** Transfer all bindings from the first statement over to the second.
+*/
+SQLITE_PRIVATE int sqlite3TransferBindings(sqlite3_stmt *pFromStmt, sqlite3_stmt *pToStmt){
+  Vdbe *pFrom = (Vdbe*)pFromStmt;
+  Vdbe *pTo = (Vdbe*)pToStmt;
+  int i;
+  assert( pTo->db==pFrom->db );
+  assert( pTo->nVar==pFrom->nVar );
+  sqlite3_mutex_enter(pTo->db->mutex);
+  for(i=0; i<pFrom->nVar; i++){
+    sqlite3VdbeMemMove(&pTo->aVar[i], &pFrom->aVar[i]);
+  }
+  sqlite3_mutex_leave(pTo->db->mutex);
+  return SQLITE_OK;
+}
+
+#ifndef SQLITE_OMIT_DEPRECATED
+/*
+** Deprecated external interface.  Internal/core SQLite code
+** should call sqlite3TransferBindings.
+**
+** Is is misuse to call this routine with statements from different
+** database connections.  But as this is a deprecated interface, we
+** will not bother to check for that condition.
+**
+** If the two statements contain a different number of bindings, then
+** an SQLITE_ERROR is returned.  Nothing else can go wrong, so otherwise
+** SQLITE_OK is returned.
+*/
+SQLITE_API int sqlite3_transfer_bindings(sqlite3_stmt *pFromStmt, sqlite3_stmt *pToStmt){
+  Vdbe *pFrom = (Vdbe*)pFromStmt;
+  Vdbe *pTo = (Vdbe*)pToStmt;
+  if( pFrom->nVar!=pTo->nVar ){
+    return SQLITE_ERROR;
+  }
+  if( pTo->isPrepareV2 && pTo->expmask ){
+    pTo->expired = 1;
+  }
+  if( pFrom->isPrepareV2 && pFrom->expmask ){
+    pFrom->expired = 1;
+  }
+  return sqlite3TransferBindings(pFromStmt, pToStmt);
+}
+#endif
+
+/*
+** Return the sqlite3* database handle to which the prepared statement given
+** in the argument belongs.  This is the same database handle that was
+** the first argument to the sqlite3_prepare() that was used to create
+** the statement in the first place.
+*/
+SQLITE_API sqlite3 *sqlite3_db_handle(sqlite3_stmt *pStmt){
+  return pStmt ? ((Vdbe*)pStmt)->db : 0;
+}
+
+/*
+** Return true if the prepared statement is guaranteed to not modify the
+** database.
+*/
+SQLITE_API int sqlite3_stmt_readonly(sqlite3_stmt *pStmt){
+  return pStmt ? ((Vdbe*)pStmt)->readOnly : 1;
+}
+
+/*
+** Return a pointer to the next prepared statement after pStmt associated
+** with database connection pDb.  If pStmt is NULL, return the first
+** prepared statement for the database connection.  Return NULL if there
+** are no more.
+*/
+SQLITE_API sqlite3_stmt *sqlite3_next_stmt(sqlite3 *pDb, sqlite3_stmt *pStmt){
+  sqlite3_stmt *pNext;
+  sqlite3_mutex_enter(pDb->mutex);
+  if( pStmt==0 ){
+    pNext = (sqlite3_stmt*)pDb->pVdbe;
+  }else{
+    pNext = (sqlite3_stmt*)((Vdbe*)pStmt)->pNext;
+  }
+  sqlite3_mutex_leave(pDb->mutex);
+  return pNext;
+}
+
+/*
+** Return the value of a status counter for a prepared statement
+*/
+SQLITE_API int sqlite3_stmt_status(sqlite3_stmt *pStmt, int op, int resetFlag){
+  Vdbe *pVdbe = (Vdbe*)pStmt;
+  int v = pVdbe->aCounter[op-1];
+  if( resetFlag ) pVdbe->aCounter[op-1] = 0;
+  return v;
+}
+
+/************** End of vdbeapi.c *********************************************/
+/************** Begin file vdbetrace.c ***************************************/
+/*
+** 2009 November 25
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file contains code used to insert the values of host parameters
+** (aka "wildcards") into the SQL text output by sqlite3_trace().
+*/
+
+#ifndef SQLITE_OMIT_TRACE
+
+/*
+** zSql is a zero-terminated string of UTF-8 SQL text.  Return the number of
+** bytes in this text up to but excluding the first character in
+** a host parameter.  If the text contains no host parameters, return
+** the total number of bytes in the text.
+*/
+static int findNextHostParameter(const char *zSql, int *pnToken){
+  int tokenType;
+  int nTotal = 0;
+  int n;
+
+  *pnToken = 0;
+  while( zSql[0] ){
+    n = sqlite3GetToken((u8*)zSql, &tokenType);
+    assert( n>0 && tokenType!=TK_ILLEGAL );
+    if( tokenType==TK_VARIABLE ){
+      *pnToken = n;
+      break;
+    }
+    nTotal += n;
+    zSql += n;
+  }
+  return nTotal;
+}
+
+/*
+** This function returns a pointer to a nul-terminated string in memory
+** obtained from sqlite3DbMalloc(). If sqlite3.vdbeExecCnt is 1, then the
+** string contains a copy of zRawSql but with host parameters expanded to 
+** their current bindings. Or, if sqlite3.vdbeExecCnt is greater than 1, 
+** then the returned string holds a copy of zRawSql with "-- " prepended
+** to each line of text.
+**
+** The calling function is responsible for making sure the memory returned
+** is eventually freed.
+**
+** ALGORITHM:  Scan the input string looking for host parameters in any of
+** these forms:  ?, ?N, $A, @A, :A.  Take care to avoid text within
+** string literals, quoted identifier names, and comments.  For text forms,
+** the host parameter index is found by scanning the perpared
+** statement for the corresponding OP_Variable opcode.  Once the host
+** parameter index is known, locate the value in p->aVar[].  Then render
+** the value as a literal in place of the host parameter name.
+*/
+SQLITE_PRIVATE char *sqlite3VdbeExpandSql(
+  Vdbe *p,                 /* The prepared statement being evaluated */
+  const char *zRawSql      /* Raw text of the SQL statement */
+){
+  sqlite3 *db;             /* The database connection */
+  int idx = 0;             /* Index of a host parameter */
+  int nextIndex = 1;       /* Index of next ? host parameter */
+  int n;                   /* Length of a token prefix */
+  int nToken;              /* Length of the parameter token */
+  int i;                   /* Loop counter */
+  Mem *pVar;               /* Value of a host parameter */
+  StrAccum out;            /* Accumulate the output here */
+  char zBase[100];         /* Initial working space */
+
+  db = p->db;
+  sqlite3StrAccumInit(&out, zBase, sizeof(zBase), 
+                      db->aLimit[SQLITE_LIMIT_LENGTH]);
+  out.db = db;
+  if( db->vdbeExecCnt>1 ){
+    while( *zRawSql ){
+      const char *zStart = zRawSql;
+      while( *(zRawSql++)!='\n' && *zRawSql );
+      sqlite3StrAccumAppend(&out, "-- ", 3);
+      sqlite3StrAccumAppend(&out, zStart, (int)(zRawSql-zStart));
+    }
+  }else{
+    while( zRawSql[0] ){
+      n = findNextHostParameter(zRawSql, &nToken);
+      assert( n>0 );
+      sqlite3StrAccumAppend(&out, zRawSql, n);
+      zRawSql += n;
+      assert( zRawSql[0] || nToken==0 );
+      if( nToken==0 ) break;
+      if( zRawSql[0]=='?' ){
+        if( nToken>1 ){
+          assert( sqlite3Isdigit(zRawSql[1]) );
+          sqlite3GetInt32(&zRawSql[1], &idx);
+        }else{
+          idx = nextIndex;
+        }
+      }else{
+        assert( zRawSql[0]==':' || zRawSql[0]=='$' || zRawSql[0]=='@' );
+        testcase( zRawSql[0]==':' );
+        testcase( zRawSql[0]=='$' );
+        testcase( zRawSql[0]=='@' );
+        idx = sqlite3VdbeParameterIndex(p, zRawSql, nToken);
+        assert( idx>0 );
+      }
+      zRawSql += nToken;
+      nextIndex = idx + 1;
+      assert( idx>0 && idx<=p->nVar );
+      pVar = &p->aVar[idx-1];
+      if( pVar->flags & MEM_Null ){
+        sqlite3StrAccumAppend(&out, "NULL", 4);
+      }else if( pVar->flags & MEM_Int ){
+        sqlite3XPrintf(&out, "%lld", pVar->u.i);
+      }else if( pVar->flags & MEM_Real ){
+        sqlite3XPrintf(&out, "%!.15g", pVar->r);
+      }else if( pVar->flags & MEM_Str ){
+#ifndef SQLITE_OMIT_UTF16
+        u8 enc = ENC(db);
+        if( enc!=SQLITE_UTF8 ){
+          Mem utf8;
+          memset(&utf8, 0, sizeof(utf8));
+          utf8.db = db;
+          sqlite3VdbeMemSetStr(&utf8, pVar->z, pVar->n, enc, SQLITE_STATIC);
+          sqlite3VdbeChangeEncoding(&utf8, SQLITE_UTF8);
+          sqlite3XPrintf(&out, "'%.*q'", utf8.n, utf8.z);
+          sqlite3VdbeMemRelease(&utf8);
+        }else
+#endif
+        {
+          sqlite3XPrintf(&out, "'%.*q'", pVar->n, pVar->z);
+        }
+      }else if( pVar->flags & MEM_Zero ){
+        sqlite3XPrintf(&out, "zeroblob(%d)", pVar->u.nZero);
+      }else{
+        assert( pVar->flags & MEM_Blob );
+        sqlite3StrAccumAppend(&out, "x'", 2);
+        for(i=0; i<pVar->n; i++){
+          sqlite3XPrintf(&out, "%02x", pVar->z[i]&0xff);
+        }
+        sqlite3StrAccumAppend(&out, "'", 1);
+      }
+    }
+  }
+  return sqlite3StrAccumFinish(&out);
+}
+
+#endif /* #ifndef SQLITE_OMIT_TRACE */
+
+/************** End of vdbetrace.c *******************************************/
+/************** Begin file vdbe.c ********************************************/
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** The code in this file implements execution method of the 
+** Virtual Database Engine (VDBE).  A separate file ("vdbeaux.c")
+** handles housekeeping details such as creating and deleting
+** VDBE instances.  This file is solely interested in executing
+** the VDBE program.
+**
+** In the external interface, an "sqlite3_stmt*" is an opaque pointer
+** to a VDBE.
+**
+** The SQL parser generates a program which is then executed by
+** the VDBE to do the work of the SQL statement.  VDBE programs are 
+** similar in form to assembly language.  The program consists of
+** a linear sequence of operations.  Each operation has an opcode 
+** and 5 operands.  Operands P1, P2, and P3 are integers.  Operand P4 
+** is a null-terminated string.  Operand P5 is an unsigned character.
+** Few opcodes use all 5 operands.
+**
+** Computation results are stored on a set of registers numbered beginning
+** with 1 and going up to Vdbe.nMem.  Each register can store
+** either an integer, a null-terminated string, a floating point
+** number, or the SQL "NULL" value.  An implicit conversion from one
+** type to the other occurs as necessary.
+** 
+** Most of the code in this file is taken up by the sqlite3VdbeExec()
+** function which does the work of interpreting a VDBE program.
+** But other routines are also provided to help in building up
+** a program instruction by instruction.
+**
+** Various scripts scan this source file in order to generate HTML
+** documentation, headers files, or other derived files.  The formatting
+** of the code in this file is, therefore, important.  See other comments
+** in this file for details.  If in doubt, do not deviate from existing
+** commenting and indentation practices when changing or adding code.
+*/
+
+/*
+** Invoke this macro on memory cells just prior to changing the
+** value of the cell.  This macro verifies that shallow copies are
+** not misused.
+*/
+#ifdef SQLITE_DEBUG
+# define memAboutToChange(P,M) sqlite3VdbeMemPrepareToChange(P,M)
+#else
+# define memAboutToChange(P,M)
+#endif
+
+/*
+** The following global variable is incremented every time a cursor
+** moves, either by the OP_SeekXX, OP_Next, or OP_Prev opcodes.  The test
+** procedures use this information to make sure that indices are
+** working correctly.  This variable has no function other than to
+** help verify the correct operation of the library.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_search_count = 0;
+#endif
+
+/*
+** When this global variable is positive, it gets decremented once before
+** each instruction in the VDBE.  When reaches zero, the u1.isInterrupted
+** field of the sqlite3 structure is set in order to simulate and interrupt.
+**
+** This facility is used for testing purposes only.  It does not function
+** in an ordinary build.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_interrupt_count = 0;
+#endif
+
+/*
+** The next global variable is incremented each type the OP_Sort opcode
+** is executed.  The test procedures use this information to make sure that
+** sorting is occurring or not occurring at appropriate times.   This variable
+** has no function other than to help verify the correct operation of the
+** library.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_sort_count = 0;
+#endif
+
+/*
+** The next global variable records the size of the largest MEM_Blob
+** or MEM_Str that has been used by a VDBE opcode.  The test procedures
+** use this information to make sure that the zero-blob functionality
+** is working correctly.   This variable has no function other than to
+** help verify the correct operation of the library.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_max_blobsize = 0;
+static void updateMaxBlobsize(Mem *p){
+  if( (p->flags & (MEM_Str|MEM_Blob))!=0 && p->n>sqlite3_max_blobsize ){
+    sqlite3_max_blobsize = p->n;
+  }
+}
+#endif
+
+/*
+** The next global variable is incremented each type the OP_Found opcode
+** is executed. This is used to test whether or not the foreign key
+** operation implemented using OP_FkIsZero is working. This variable
+** has no function other than to help verify the correct operation of the
+** library.
+*/
+#ifdef SQLITE_TEST
+SQLITE_API int sqlite3_found_count = 0;
+#endif
+
+/*
+** Test a register to see if it exceeds the current maximum blob size.
+** If it does, record the new maximum blob size.
+*/
+#if defined(SQLITE_TEST) && !defined(SQLITE_OMIT_BUILTIN_TEST)
+# define UPDATE_MAX_BLOBSIZE(P)  updateMaxBlobsize(P)
+#else
+# define UPDATE_MAX_BLOBSIZE(P)
+#endif
+
+/*
+** Convert the given register into a string if it isn't one
+** already. Return non-zero if a malloc() fails.
+*/
+#define Stringify(P, enc) \
+   if(((P)->flags&(MEM_Str|MEM_Blob))==0 && sqlite3VdbeMemStringify(P,enc)) \
+     { goto no_mem; }
+
+/*
+** An ephemeral string value (signified by the MEM_Ephem flag) contains
+** a pointer to a dynamically allocated string where some other entity
+** is responsible for deallocating that string.  Because the register
+** does not control the string, it might be deleted without the register
+** knowing it.
+**
+** This routine converts an ephemeral string into a dynamically allocated
+** string that the register itself controls.  In other words, it
+** converts an MEM_Ephem string into an MEM_Dyn string.
+*/
+#define Deephemeralize(P) \
+   if( ((P)->flags&MEM_Ephem)!=0 \
+       && sqlite3VdbeMemMakeWriteable(P) ){ goto no_mem;}
+
+/*
+** Call sqlite3VdbeMemExpandBlob() on the supplied value (type Mem*)
+** P if required.
+*/
+#define ExpandBlob(P) (((P)->flags&MEM_Zero)?sqlite3VdbeMemExpandBlob(P):0)
+
+/*
+** Argument pMem points at a register that will be passed to a
+** user-defined function or returned to the user as the result of a query.
+** This routine sets the pMem->type variable used by the sqlite3_value_*() 
+** routines.
+*/
+SQLITE_PRIVATE void sqlite3VdbeMemStoreType(Mem *pMem){
+  int flags = pMem->flags;
+  if( flags & MEM_Null ){
+    pMem->type = SQLITE_NULL;
+  }
+  else if( flags & MEM_Int ){
+    pMem->type = SQLITE_INTEGER;
+  }
+  else if( flags & MEM_Real ){
+    pMem->type = SQLITE_FLOAT;
+  }
+  else if( flags & MEM_Str ){
+    pMem->type = SQLITE_TEXT;
+  }else{
+    pMem->type = SQLITE_BLOB;
+  }
+}
+
+/*
+** Allocate VdbeCursor number iCur.  Return a pointer to it.  Return NULL
+** if we run out of memory.
+*/
+static VdbeCursor *allocateCursor(
+  Vdbe *p,              /* The virtual machine */
+  int iCur,             /* Index of the new VdbeCursor */
+  int nField,           /* Number of fields in the table or index */
+  int iDb,              /* When database the cursor belongs to, or -1 */
+  int isBtreeCursor     /* True for B-Tree.  False for pseudo-table or vtab */
+){
+  /* Find the memory cell that will be used to store the blob of memory
+  ** required for this VdbeCursor structure. It is convenient to use a 
+  ** vdbe memory cell to manage the memory allocation required for a
+  ** VdbeCursor structure for the following reasons:
+  **
+  **   * Sometimes cursor numbers are used for a couple of different
+  **     purposes in a vdbe program. The different uses might require
+  **     different sized allocations. Memory cells provide growable
+  **     allocations.
+  **
+  **   * When using ENABLE_MEMORY_MANAGEMENT, memory cell buffers can
+  **     be freed lazily via the sqlite3_release_memory() API. This
+  **     minimizes the number of malloc calls made by the system.
+  **
+  ** Memory cells for cursors are allocated at the top of the address
+  ** space. Memory cell (p->nMem) corresponds to cursor 0. Space for
+  ** cursor 1 is managed by memory cell (p->nMem-1), etc.
+  */
+  Mem *pMem = &p->aMem[p->nMem-iCur];
+
+  int nByte;
+  VdbeCursor *pCx = 0;
+  nByte = 
+      ROUND8(sizeof(VdbeCursor)) + 
+      (isBtreeCursor?sqlite3BtreeCursorSize():0) + 
+      2*nField*sizeof(u32);
+
+  assert( iCur<p->nCursor );
+  if( p->apCsr[iCur] ){
+    sqlite3VdbeFreeCursor(p, p->apCsr[iCur]);
+    p->apCsr[iCur] = 0;
+  }
+  if( SQLITE_OK==sqlite3VdbeMemGrow(pMem, nByte, 0) ){
+    p->apCsr[iCur] = pCx = (VdbeCursor*)pMem->z;
+    memset(pCx, 0, sizeof(VdbeCursor));
+    pCx->iDb = iDb;
+    pCx->nField = nField;
+    if( nField ){
+      pCx->aType = (u32 *)&pMem->z[ROUND8(sizeof(VdbeCursor))];
+    }
+    if( isBtreeCursor ){
+      pCx->pCursor = (BtCursor*)
+          &pMem->z[ROUND8(sizeof(VdbeCursor))+2*nField*sizeof(u32)];
+      sqlite3BtreeCursorZero(pCx->pCursor);
+    }
+  }
+  return pCx;
+}
+
+/*
+** Try to convert a value into a numeric representation if we can
+** do so without loss of information.  In other words, if the string
+** looks like a number, convert it into a number.  If it does not
+** look like a number, leave it alone.
+*/
+static void applyNumericAffinity(Mem *pRec){
+  if( (pRec->flags & (MEM_Real|MEM_Int))==0 ){
+    double rValue;
+    i64 iValue;
+    u8 enc = pRec->enc;
+    if( (pRec->flags&MEM_Str)==0 ) return;
+    if( sqlite3AtoF(pRec->z, &rValue, pRec->n, enc)==0 ) return;
+    if( 0==sqlite3Atoi64(pRec->z, &iValue, pRec->n, enc) ){
+      pRec->u.i = iValue;
+      pRec->flags |= MEM_Int;
+    }else{
+      pRec->r = rValue;
+      pRec->flags |= MEM_Real;
+    }
+  }
+}
+
+/*
+** Processing is determine by the affinity parameter:
+**
+** SQLITE_AFF_INTEGER:
+** SQLITE_AFF_REAL:
+** SQLITE_AFF_NUMERIC:
+**    Try to convert pRec to an integer representation or a 
+**    floating-point representation if an integer representation
+**    is not possible.  Note that the integer representation is
+**    always preferred, even if the affinity is REAL, because
+**    an integer representation is more space efficient on disk.
+**
+** SQLITE_AFF_TEXT:
+**    Convert pRec to a text representation.
+**
+** SQLITE_AFF_NONE:
+**    No-op.  pRec is unchanged.
+*/
+static void applyAffinity(
+  Mem *pRec,          /* The value to apply affinity to */
+  char affinity,      /* The affinity to be applied */
+  u8 enc              /* Use this text encoding */
+){
+  if( affinity==SQLITE_AFF_TEXT ){
+    /* Only attempt the conversion to TEXT if there is an integer or real
+    ** representation (blob and NULL do not get converted) but no string
+    ** representation.
+    */
+    if( 0==(pRec->flags&MEM_Str) && (pRec->flags&(MEM_Real|MEM_Int)) ){
+      sqlite3VdbeMemStringify(pRec, enc);
+    }
+    pRec->flags &= ~(MEM_Real|MEM_Int);
+  }else if( affinity!=SQLITE_AFF_NONE ){
+    assert( affinity==SQLITE_AFF_INTEGER || affinity==SQLITE_AFF_REAL
+             || affinity==SQLITE_AFF_NUMERIC );
+    applyNumericAffinity(pRec);
+    if( pRec->flags & MEM_Real ){
+      sqlite3VdbeIntegerAffinity(pRec);
+    }
+  }
+}
+
+/*
+** Try to convert the type of a function argument or a result column
+** into a numeric representation.  Use either INTEGER or REAL whichever
+** is appropriate.  But only do the conversion if it is possible without
+** loss of information and return the revised type of the argument.
+*/
+SQLITE_API int sqlite3_value_numeric_type(sqlite3_value *pVal){
+  Mem *pMem = (Mem*)pVal;
+  if( pMem->type==SQLITE_TEXT ){
+    applyNumericAffinity(pMem);
+    sqlite3VdbeMemStoreType(pMem);
+  }
+  return pMem->type;
+}
+
+/*
+** Exported version of applyAffinity(). This one works on sqlite3_value*, 
+** not the internal Mem* type.
+*/
+SQLITE_PRIVATE void sqlite3ValueApplyAffinity(
+  sqlite3_value *pVal, 
+  u8 affinity, 
+  u8 enc
+){
+  applyAffinity((Mem *)pVal, affinity, enc);
+}
+
+#ifdef SQLITE_DEBUG
+/*
+** Write a nice string representation of the contents of cell pMem
+** into buffer zBuf, length nBuf.
+*/
+SQLITE_PRIVATE void sqlite3VdbeMemPrettyPrint(Mem *pMem, char *zBuf){
+  char *zCsr = zBuf;
+  int f = pMem->flags;
+
+  static const char *const encnames[] = {"(X)", "(8)", "(16LE)", "(16BE)"};
+
+  if( f&MEM_Blob ){
+    int i;
+    char c;
+    if( f & MEM_Dyn ){
+      c = 'z';
+      assert( (f & (MEM_Static|MEM_Ephem))==0 );
+    }else if( f & MEM_Static ){
+      c = 't';
+      assert( (f & (MEM_Dyn|MEM_Ephem))==0 );
+    }else if( f & MEM_Ephem ){
+      c = 'e';
+      assert( (f & (MEM_Static|MEM_Dyn))==0 );
+    }else{
+      c = 's';
+    }
+
+    sqlite3_snprintf(100, zCsr, "%c", c);
+    zCsr += sqlite3Strlen30(zCsr);
+    sqlite3_snprintf(100, zCsr, "%d[", pMem->n);
+    zCsr += sqlite3Strlen30(zCsr);
+    for(i=0; i<16 && i<pMem->n; i++){
+      sqlite3_snprintf(100, zCsr, "%02X", ((int)pMem->z[i] & 0xFF));
+      zCsr += sqlite3Strlen30(zCsr);
+    }
+    for(i=0; i<16 && i<pMem->n; i++){
+      char z = pMem->z[i];
+      if( z<32 || z>126 ) *zCsr++ = '.';
+      else *zCsr++ = z;
+    }
+
+    sqlite3_snprintf(100, zCsr, "]%s", encnames[pMem->enc]);
+    zCsr += sqlite3Strlen30(zCsr);
+    if( f & MEM_Zero ){
+      sqlite3_snprintf(100, zCsr,"+%dz",pMem->u.nZero);
+      zCsr += sqlite3Strlen30(zCsr);
+    }
+    *zCsr = '\0';
+  }else if( f & MEM_Str ){
+    int j, k;
+    zBuf[0] = ' ';
+    if( f & MEM_Dyn ){
+      zBuf[1] = 'z';
+      assert( (f & (MEM_Static|MEM_Ephem))==0 );
+    }else if( f & MEM_Static ){
+      zBuf[1] = 't';
+      assert( (f & (MEM_Dyn|MEM_Ephem))==0 );
+    }else if( f & MEM_Ephem ){
+      zBuf[1] = 'e';
+      assert( (f & (MEM_Static|MEM_Dyn))==0 );
+    }else{
+      zBuf[1] = 's';
+    }
+    k = 2;
+    sqlite3_snprintf(100, &zBuf[k], "%d", pMem->n);
+    k += sqlite3Strlen30(&zBuf[k]);
+    zBuf[k++] = '[';
+    for(j=0; j<15 && j<pMem->n; j++){
+      u8 c = pMem->z[j];
+      if( c>=0x20 && c<0x7f ){
+        zBuf[k++] = c;
+      }else{
+        zBuf[k++] = '.';
+      }
+    }
+    zBuf[k++] = ']';
+    sqlite3_snprintf(100,&zBuf[k], encnames[pMem->enc]);
+    k += sqlite3Strlen30(&zBuf[k]);
+    zBuf[k++] = 0;
+  }
+}
+#endif
+
+#ifdef SQLITE_DEBUG
+/*
+** Print the value of a register for tracing purposes:
+*/
+static void memTracePrint(FILE *out, Mem *p){
+  if( p->flags & MEM_Null ){
+    fprintf(out, " NULL");
+  }else if( (p->flags & (MEM_Int|MEM_Str))==(MEM_Int|MEM_Str) ){
+    fprintf(out, " si:%lld", p->u.i);
+  }else if( p->flags & MEM_Int ){
+    fprintf(out, " i:%lld", p->u.i);
+#ifndef SQLITE_OMIT_FLOATING_POINT
+  }else if( p->flags & MEM_Real ){
+    fprintf(out, " r:%g", p->r);
+#endif
+  }else if( p->flags & MEM_RowSet ){
+    fprintf(out, " (rowset)");
+  }else{
+    char zBuf[200];
+    sqlite3VdbeMemPrettyPrint(p, zBuf);
+    fprintf(out, " ");
+    fprintf(out, "%s", zBuf);
+  }
+}
+static void registerTrace(FILE *out, int iReg, Mem *p){
+  fprintf(out, "REG[%d] = ", iReg);
+  memTracePrint(out, p);
+  fprintf(out, "\n");
+}
+#endif
+
+#ifdef SQLITE_DEBUG
+#  define REGISTER_TRACE(R,M) if(p->trace)registerTrace(p->trace,R,M)
+#else
+#  define REGISTER_TRACE(R,M)
+#endif
+
+
+#ifdef VDBE_PROFILE
+
+/* 
+** hwtime.h contains inline assembler code for implementing 
+** high-performance timing routines.
+*/
+/************** Include hwtime.h in the middle of vdbe.c *********************/
+/************** Begin file hwtime.h ******************************************/
+/*
+** 2008 May 27
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains inline asm code for retrieving "high-performance"
+** counters for x86 class CPUs.
+*/
+#ifndef _HWTIME_H_
+#define _HWTIME_H_
+
+/*
+** The following routine only works on pentium-class (or newer) processors.
+** It uses the RDTSC opcode to read the cycle count value out of the
+** processor and returns that value.  This can be used for high-res
+** profiling.
+*/
+#if (defined(__GNUC__) || defined(_MSC_VER)) && \
+      (defined(i386) || defined(__i386__) || defined(_M_IX86))
+
+  #if defined(__GNUC__)
+
+  __inline__ sqlite_uint64 sqlite3Hwtime(void){
+     unsigned int lo, hi;
+     __asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi));
+     return (sqlite_uint64)hi << 32 | lo;
+  }
+
+  #elif defined(_MSC_VER)
+
+  __declspec(naked) __inline sqlite_uint64 __cdecl sqlite3Hwtime(void){
+     __asm {
+        rdtsc
+        ret       ; return value at EDX:EAX
+     }
+  }
+
+  #endif
+
+#elif (defined(__GNUC__) && defined(__x86_64__))
+
+  __inline__ sqlite_uint64 sqlite3Hwtime(void){
+      unsigned long val;
+      __asm__ __volatile__ ("rdtsc" : "=A" (val));
+      return val;
+  }
+ 
+#elif (defined(__GNUC__) && defined(__ppc__))
+
+  __inline__ sqlite_uint64 sqlite3Hwtime(void){
+      unsigned long long retval;
+      unsigned long junk;
+      __asm__ __volatile__ ("\n\
+          1:      mftbu   %1\n\
+                  mftb    %L0\n\
+                  mftbu   %0\n\
+                  cmpw    %0,%1\n\
+                  bne     1b"
+                  : "=r" (retval), "=r" (junk));
+      return retval;
+  }
+
+#else
+
+  #error Need implementation of sqlite3Hwtime() for your platform.
+
+  /*
+  ** To compile without implementing sqlite3Hwtime() for your platform,
+  ** you can remove the above #error and use the following
+  ** stub function.  You will lose timing support for many
+  ** of the debugging and testing utilities, but it should at
+  ** least compile and run.
+  */
+SQLITE_PRIVATE   sqlite_uint64 sqlite3Hwtime(void){ return ((sqlite_uint64)0); }
+
+#endif
+
+#endif /* !defined(_HWTIME_H_) */
+
+/************** End of hwtime.h **********************************************/
+/************** Continuing where we left off in vdbe.c ***********************/
+
+#endif
+
+/*
+** The CHECK_FOR_INTERRUPT macro defined here looks to see if the
+** sqlite3_interrupt() routine has been called.  If it has been, then
+** processing of the VDBE program is interrupted.
+**
+** This macro added to every instruction that does a jump in order to
+** implement a loop.  This test used to be on every single instruction,
+** but that meant we more testing that we needed.  By only testing the
+** flag on jump instructions, we get a (small) speed improvement.
+*/
+#define CHECK_FOR_INTERRUPT \
+   if( db->u1.isInterrupted ) goto abort_due_to_interrupt;
+
+
+#ifndef NDEBUG
+/*
+** This function is only called from within an assert() expression. It
+** checks that the sqlite3.nTransaction variable is correctly set to
+** the number of non-transaction savepoints currently in the 
+** linked list starting at sqlite3.pSavepoint.
+** 
+** Usage:
+**
+**     assert( checkSavepointCount(db) );
+*/
+static int checkSavepointCount(sqlite3 *db){
+  int n = 0;
+  Savepoint *p;
+  for(p=db->pSavepoint; p; p=p->pNext) n++;
+  assert( n==(db->nSavepoint + db->isTransactionSavepoint) );
+  return 1;
+}
+#endif
+
+/*
+** Transfer error message text from an sqlite3_vtab.zErrMsg (text stored
+** in memory obtained from sqlite3_malloc) into a Vdbe.zErrMsg (text stored
+** in memory obtained from sqlite3DbMalloc).
+*/
+static void importVtabErrMsg(Vdbe *p, sqlite3_vtab *pVtab){
+  sqlite3 *db = p->db;
+  sqlite3DbFree(db, p->zErrMsg);
+  p->zErrMsg = sqlite3DbStrDup(db, pVtab->zErrMsg);
+  sqlite3_free(pVtab->zErrMsg);
+  pVtab->zErrMsg = 0;
+}
+
+
+/*
+** Execute as much of a VDBE program as we can then return.
+**
+** sqlite3VdbeMakeReady() must be called before this routine in order to
+** close the program with a final OP_Halt and to set up the callbacks
+** and the error message pointer.
+**
+** Whenever a row or result data is available, this routine will either
+** invoke the result callback (if there is one) or return with
+** SQLITE_ROW.
+**
+** If an attempt is made to open a locked database, then this routine
+** will either invoke the busy callback (if there is one) or it will
+** return SQLITE_BUSY.
+**
+** If an error occurs, an error message is written to memory obtained
+** from sqlite3_malloc() and p->zErrMsg is made to point to that memory.
+** The error code is stored in p->rc and this routine returns SQLITE_ERROR.
+**
+** If the callback ever returns non-zero, then the program exits
+** immediately.  There will be no error message but the p->rc field is
+** set to SQLITE_ABORT and this routine will return SQLITE_ERROR.
+**
+** A memory allocation error causes p->rc to be set to SQLITE_NOMEM and this
+** routine to return SQLITE_ERROR.
+**
+** Other fatal errors return SQLITE_ERROR.
+**
+** After this routine has finished, sqlite3VdbeFinalize() should be
+** used to clean up the mess that was left behind.
+*/
+SQLITE_PRIVATE int sqlite3VdbeExec(
+  Vdbe *p                    /* The VDBE */
+){
+  int pc=0;                  /* The program counter */
+  Op *aOp = p->aOp;          /* Copy of p->aOp */
+  Op *pOp;                   /* Current operation */
+  int rc = SQLITE_OK;        /* Value to return */
+  sqlite3 *db = p->db;       /* The database */
+  u8 resetSchemaOnFault = 0; /* Reset schema after an error if positive */
+  u8 encoding = ENC(db);     /* The database encoding */
+#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
+  int checkProgress;         /* True if progress callbacks are enabled */
+  int nProgressOps = 0;      /* Opcodes executed since progress callback. */
+#endif
+  Mem *aMem = p->aMem;       /* Copy of p->aMem */
+  Mem *pIn1 = 0;             /* 1st input operand */
+  Mem *pIn2 = 0;             /* 2nd input operand */
+  Mem *pIn3 = 0;             /* 3rd input operand */
+  Mem *pOut = 0;             /* Output operand */
+  int iCompare = 0;          /* Result of last OP_Compare operation */
+  int *aPermute = 0;         /* Permutation of columns for OP_Compare */
+#ifdef VDBE_PROFILE
+  u64 start;                 /* CPU clock count at start of opcode */
+  int origPc;                /* Program counter at start of opcode */
+#endif
+  /********************************************************************
+  ** Automatically generated code
+  **
+  ** The following union is automatically generated by the
+  ** vdbe-compress.tcl script.  The purpose of this union is to
+  ** reduce the amount of stack space required by this function.
+  ** See comments in the vdbe-compress.tcl script for details.
+  */
+  union vdbeExecUnion {
+    struct OP_Yield_stack_vars {
+      int pcDest;
+    } aa;
+    struct OP_Variable_stack_vars {
+      Mem *pVar;       /* Value being transferred */
+    } ab;
+    struct OP_Move_stack_vars {
+      char *zMalloc;   /* Holding variable for allocated memory */
+      int n;           /* Number of registers left to copy */
+      int p1;          /* Register to copy from */
+      int p2;          /* Register to copy to */
+    } ac;
+    struct OP_ResultRow_stack_vars {
+      Mem *pMem;
+      int i;
+    } ad;
+    struct OP_Concat_stack_vars {
+      i64 nByte;
+    } ae;
+    struct OP_Remainder_stack_vars {
+      int flags;      /* Combined MEM_* flags from both inputs */
+      i64 iA;         /* Integer value of left operand */
+      i64 iB;         /* Integer value of right operand */
+      double rA;      /* Real value of left operand */
+      double rB;      /* Real value of right operand */
+    } af;
+    struct OP_Function_stack_vars {
+      int i;
+      Mem *pArg;
+      sqlite3_context ctx;
+      sqlite3_value **apVal;
+      int n;
+    } ag;
+    struct OP_ShiftRight_stack_vars {
+      i64 iA;
+      u64 uA;
+      i64 iB;
+      u8 op;
+    } ah;
+    struct OP_Ge_stack_vars {
+      int res;            /* Result of the comparison of pIn1 against pIn3 */
+      char affinity;      /* Affinity to use for comparison */
+      u16 flags1;         /* Copy of initial value of pIn1->flags */
+      u16 flags3;         /* Copy of initial value of pIn3->flags */
+    } ai;
+    struct OP_Compare_stack_vars {
+      int n;
+      int i;
+      int p1;
+      int p2;
+      const KeyInfo *pKeyInfo;
+      int idx;
+      CollSeq *pColl;    /* Collating sequence to use on this term */
+      int bRev;          /* True for DESCENDING sort order */
+    } aj;
+    struct OP_Or_stack_vars {
+      int v1;    /* Left operand:  0==FALSE, 1==TRUE, 2==UNKNOWN or NULL */
+      int v2;    /* Right operand: 0==FALSE, 1==TRUE, 2==UNKNOWN or NULL */
+    } ak;
+    struct OP_IfNot_stack_vars {
+      int c;
+    } al;
+    struct OP_Column_stack_vars {
+      u32 payloadSize;   /* Number of bytes in the record */
+      i64 payloadSize64; /* Number of bytes in the record */
+      int p1;            /* P1 value of the opcode */
+      int p2;            /* column number to retrieve */
+      VdbeCursor *pC;    /* The VDBE cursor */
+      char *zRec;        /* Pointer to complete record-data */
+      BtCursor *pCrsr;   /* The BTree cursor */
+      u32 *aType;        /* aType[i] holds the numeric type of the i-th column */
+      u32 *aOffset;      /* aOffset[i] is offset to start of data for i-th column */
+      int nField;        /* number of fields in the record */
+      int len;           /* The length of the serialized data for the column */
+      int i;             /* Loop counter */
+      char *zData;       /* Part of the record being decoded */
+      Mem *pDest;        /* Where to write the extracted value */
+      Mem sMem;          /* For storing the record being decoded */
+      u8 *zIdx;          /* Index into header */
+      u8 *zEndHdr;       /* Pointer to first byte after the header */
+      u32 offset;        /* Offset into the data */
+      u32 szField;       /* Number of bytes in the content of a field */
+      int szHdr;         /* Size of the header size field at start of record */
+      int avail;         /* Number of bytes of available data */
+      Mem *pReg;         /* PseudoTable input register */
+    } am;
+    struct OP_Affinity_stack_vars {
+      const char *zAffinity;   /* The affinity to be applied */
+      char cAff;               /* A single character of affinity */
+    } an;
+    struct OP_MakeRecord_stack_vars {
+      u8 *zNewRecord;        /* A buffer to hold the data for the new record */
+      Mem *pRec;             /* The new record */
+      u64 nData;             /* Number of bytes of data space */
+      int nHdr;              /* Number of bytes of header space */
+      i64 nByte;             /* Data space required for this record */
+      int nZero;             /* Number of zero bytes at the end of the record */
+      int nVarint;           /* Number of bytes in a varint */
+      u32 serial_type;       /* Type field */
+      Mem *pData0;           /* First field to be combined into the record */
+      Mem *pLast;            /* Last field of the record */
+      int nField;            /* Number of fields in the record */
+      char *zAffinity;       /* The affinity string for the record */
+      int file_format;       /* File format to use for encoding */
+      int i;                 /* Space used in zNewRecord[] */
+      int len;               /* Length of a field */
+    } ao;
+    struct OP_Count_stack_vars {
+      i64 nEntry;
+      BtCursor *pCrsr;
+    } ap;
+    struct OP_Savepoint_stack_vars {
+      int p1;                         /* Value of P1 operand */
+      char *zName;                    /* Name of savepoint */
+      int nName;
+      Savepoint *pNew;
+      Savepoint *pSavepoint;
+      Savepoint *pTmp;
+      int iSavepoint;
+      int ii;
+    } aq;
+    struct OP_AutoCommit_stack_vars {
+      int desiredAutoCommit;
+      int iRollback;
+      int turnOnAC;
+    } ar;
+    struct OP_Transaction_stack_vars {
+      Btree *pBt;
+    } as;
+    struct OP_ReadCookie_stack_vars {
+      int iMeta;
+      int iDb;
+      int iCookie;
+    } at;
+    struct OP_SetCookie_stack_vars {
+      Db *pDb;
+    } au;
+    struct OP_VerifyCookie_stack_vars {
+      int iMeta;
+      int iGen;
+      Btree *pBt;
+    } av;
+    struct OP_OpenWrite_stack_vars {
+      int nField;
+      KeyInfo *pKeyInfo;
+      int p2;
+      int iDb;
+      int wrFlag;
+      Btree *pX;
+      VdbeCursor *pCur;
+      Db *pDb;
+    } aw;
+    struct OP_OpenEphemeral_stack_vars {
+      VdbeCursor *pCx;
+    } ax;
+    struct OP_OpenPseudo_stack_vars {
+      VdbeCursor *pCx;
+    } ay;
+    struct OP_SeekGt_stack_vars {
+      int res;
+      int oc;
+      VdbeCursor *pC;
+      UnpackedRecord r;
+      int nField;
+      i64 iKey;      /* The rowid we are to seek to */
+    } az;
+    struct OP_Seek_stack_vars {
+      VdbeCursor *pC;
+    } ba;
+    struct OP_Found_stack_vars {
+      int alreadyExists;
+      VdbeCursor *pC;
+      int res;
+      UnpackedRecord *pIdxKey;
+      UnpackedRecord r;
+      char aTempRec[ROUND8(sizeof(UnpackedRecord)) + sizeof(Mem)*3 + 7];
+    } bb;
+    struct OP_IsUnique_stack_vars {
+      u16 ii;
+      VdbeCursor *pCx;
+      BtCursor *pCrsr;
+      u16 nField;
+      Mem *aMx;
+      UnpackedRecord r;                  /* B-Tree index search key */
+      i64 R;                             /* Rowid stored in register P3 */
+    } bc;
+    struct OP_NotExists_stack_vars {
+      VdbeCursor *pC;
+      BtCursor *pCrsr;
+      int res;
+      u64 iKey;
+    } bd;
+    struct OP_NewRowid_stack_vars {
+      i64 v;                 /* The new rowid */
+      VdbeCursor *pC;        /* Cursor of table to get the new rowid */
+      int res;               /* Result of an sqlite3BtreeLast() */
+      int cnt;               /* Counter to limit the number of searches */
+      Mem *pMem;             /* Register holding largest rowid for AUTOINCREMENT */
+      VdbeFrame *pFrame;     /* Root frame of VDBE */
+    } be;
+    struct OP_InsertInt_stack_vars {
+      Mem *pData;       /* MEM cell holding data for the record to be inserted */
+      Mem *pKey;        /* MEM cell holding key  for the record */
+      i64 iKey;         /* The integer ROWID or key for the record to be inserted */
+      VdbeCursor *pC;   /* Cursor to table into which insert is written */
+      int nZero;        /* Number of zero-bytes to append */
+      int seekResult;   /* Result of prior seek or 0 if no USESEEKRESULT flag */
+      const char *zDb;  /* database name - used by the update hook */
+      const char *zTbl; /* Table name - used by the opdate hook */
+      int op;           /* Opcode for update hook: SQLITE_UPDATE or SQLITE_INSERT */
+    } bf;
+    struct OP_Delete_stack_vars {
+      i64 iKey;
+      VdbeCursor *pC;
+    } bg;
+    struct OP_RowData_stack_vars {
+      VdbeCursor *pC;
+      BtCursor *pCrsr;
+      u32 n;
+      i64 n64;
+    } bh;
+    struct OP_Rowid_stack_vars {
+      VdbeCursor *pC;
+      i64 v;
+      sqlite3_vtab *pVtab;
+      const sqlite3_module *pModule;
+    } bi;
+    struct OP_NullRow_stack_vars {
+      VdbeCursor *pC;
+    } bj;
+    struct OP_Last_stack_vars {
+      VdbeCursor *pC;
+      BtCursor *pCrsr;
+      int res;
+    } bk;
+    struct OP_Rewind_stack_vars {
+      VdbeCursor *pC;
+      BtCursor *pCrsr;
+      int res;
+    } bl;
+    struct OP_Next_stack_vars {
+      VdbeCursor *pC;
+      BtCursor *pCrsr;
+      int res;
+    } bm;
+    struct OP_IdxInsert_stack_vars {
+      VdbeCursor *pC;
+      BtCursor *pCrsr;
+      int nKey;
+      const char *zKey;
+    } bn;
+    struct OP_IdxDelete_stack_vars {
+      VdbeCursor *pC;
+      BtCursor *pCrsr;
+      int res;
+      UnpackedRecord r;
+    } bo;
+    struct OP_IdxRowid_stack_vars {
+      BtCursor *pCrsr;
+      VdbeCursor *pC;
+      i64 rowid;
+    } bp;
+    struct OP_IdxGE_stack_vars {
+      VdbeCursor *pC;
+      int res;
+      UnpackedRecord r;
+    } bq;
+    struct OP_Destroy_stack_vars {
+      int iMoved;
+      int iCnt;
+      Vdbe *pVdbe;
+      int iDb;
+    } br;
+    struct OP_Clear_stack_vars {
+      int nChange;
+    } bs;
+    struct OP_CreateTable_stack_vars {
+      int pgno;
+      int flags;
+      Db *pDb;
+    } bt;
+    struct OP_ParseSchema_stack_vars {
+      int iDb;
+      const char *zMaster;
+      char *zSql;
+      InitData initData;
+    } bu;
+    struct OP_IntegrityCk_stack_vars {
+      int nRoot;      /* Number of tables to check.  (Number of root pages.) */
+      int *aRoot;     /* Array of rootpage numbers for tables to be checked */
+      int j;          /* Loop counter */
+      int nErr;       /* Number of errors reported */
+      char *z;        /* Text of the error report */
+      Mem *pnErr;     /* Register keeping track of errors remaining */
+    } bv;
+    struct OP_RowSetRead_stack_vars {
+      i64 val;
+    } bw;
+    struct OP_RowSetTest_stack_vars {
+      int iSet;
+      int exists;
+    } bx;
+    struct OP_Program_stack_vars {
+      int nMem;               /* Number of memory registers for sub-program */
+      int nByte;              /* Bytes of runtime space required for sub-program */
+      Mem *pRt;               /* Register to allocate runtime space */
+      Mem *pMem;              /* Used to iterate through memory cells */
+      Mem *pEnd;              /* Last memory cell in new array */
+      VdbeFrame *pFrame;      /* New vdbe frame to execute in */
+      SubProgram *pProgram;   /* Sub-program to execute */
+      void *t;                /* Token identifying trigger */
+    } by;
+    struct OP_Param_stack_vars {
+      VdbeFrame *pFrame;
+      Mem *pIn;
+    } bz;
+    struct OP_MemMax_stack_vars {
+      Mem *pIn1;
+      VdbeFrame *pFrame;
+    } ca;
+    struct OP_AggStep_stack_vars {
+      int n;
+      int i;
+      Mem *pMem;
+      Mem *pRec;
+      sqlite3_context ctx;
+      sqlite3_value **apVal;
+    } cb;
+    struct OP_AggFinal_stack_vars {
+      Mem *pMem;
+    } cc;
+    struct OP_Checkpoint_stack_vars {
+      int i;                          /* Loop counter */
+      int aRes[3];                    /* Results */
+      Mem *pMem;                      /* Write results here */
+    } cd;
+    struct OP_JournalMode_stack_vars {
+      Btree *pBt;                     /* Btree to change journal mode of */
+      Pager *pPager;                  /* Pager associated with pBt */
+      int eNew;                       /* New journal mode */
+      int eOld;                       /* The old journal mode */
+      const char *zFilename;          /* Name of database file for pPager */
+    } ce;
+    struct OP_IncrVacuum_stack_vars {
+      Btree *pBt;
+    } cf;
+    struct OP_VBegin_stack_vars {
+      VTable *pVTab;
+    } cg;
+    struct OP_VOpen_stack_vars {
+      VdbeCursor *pCur;
+      sqlite3_vtab_cursor *pVtabCursor;
+      sqlite3_vtab *pVtab;
+      sqlite3_module *pModule;
+    } ch;
+    struct OP_VFilter_stack_vars {
+      int nArg;
+      int iQuery;
+      const sqlite3_module *pModule;
+      Mem *pQuery;
+      Mem *pArgc;
+      sqlite3_vtab_cursor *pVtabCursor;
+      sqlite3_vtab *pVtab;
+      VdbeCursor *pCur;
+      int res;
+      int i;
+      Mem **apArg;
+    } ci;
+    struct OP_VColumn_stack_vars {
+      sqlite3_vtab *pVtab;
+      const sqlite3_module *pModule;
+      Mem *pDest;
+      sqlite3_context sContext;
+    } cj;
+    struct OP_VNext_stack_vars {
+      sqlite3_vtab *pVtab;
+      const sqlite3_module *pModule;
+      int res;
+      VdbeCursor *pCur;
+    } ck;
+    struct OP_VRename_stack_vars {
+      sqlite3_vtab *pVtab;
+      Mem *pName;
+    } cl;
+    struct OP_VUpdate_stack_vars {
+      sqlite3_vtab *pVtab;
+      sqlite3_module *pModule;
+      int nArg;
+      int i;
+      sqlite_int64 rowid;
+      Mem **apArg;
+      Mem *pX;
+    } cm;
+    struct OP_Trace_stack_vars {
+      char *zTrace;
+    } cn;
+  } u;
+  /* End automatically generated code
+  ********************************************************************/
+
+  assert( p->magic==VDBE_MAGIC_RUN );  /* sqlite3_step() verifies this */
+  sqlite3VdbeEnter(p);
+  if( p->rc==SQLITE_NOMEM ){
+    /* This happens if a malloc() inside a call to sqlite3_column_text() or
+    ** sqlite3_column_text16() failed.  */
+    goto no_mem;
+  }
+  assert( p->rc==SQLITE_OK || p->rc==SQLITE_BUSY );
+  p->rc = SQLITE_OK;
+  assert( p->explain==0 );
+  p->pResultSet = 0;
+  db->busyHandler.nBusy = 0;
+  CHECK_FOR_INTERRUPT;
+  sqlite3VdbeIOTraceSql(p);
+#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
+  checkProgress = db->xProgress!=0;
+#endif
+#ifdef SQLITE_DEBUG
+  sqlite3BeginBenignMalloc();
+  if( p->pc==0  && (p->db->flags & SQLITE_VdbeListing)!=0 ){
+    int i;
+    printf("VDBE Program Listing:\n");
+    sqlite3VdbePrintSql(p);
+    for(i=0; i<p->nOp; i++){
+      sqlite3VdbePrintOp(stdout, i, &aOp[i]);
+    }
+  }
+  sqlite3EndBenignMalloc();
+#endif
+  for(pc=p->pc; rc==SQLITE_OK; pc++){
+    assert( pc>=0 && pc<p->nOp );
+    if( db->mallocFailed ) goto no_mem;
+#ifdef VDBE_PROFILE
+    origPc = pc;
+    start = sqlite3Hwtime();
+#endif
+    pOp = &aOp[pc];
+
+    /* Only allow tracing if SQLITE_DEBUG is defined.
+    */
+#ifdef SQLITE_DEBUG
+    if( p->trace ){
+      if( pc==0 ){
+        printf("VDBE Execution Trace:\n");
+        sqlite3VdbePrintSql(p);
+      }
+      sqlite3VdbePrintOp(p->trace, pc, pOp);
+    }
+#endif
+      
+
+    /* Check to see if we need to simulate an interrupt.  This only happens
+    ** if we have a special test build.
+    */
+#ifdef SQLITE_TEST
+    if( sqlite3_interrupt_count>0 ){
+      sqlite3_interrupt_count--;
+      if( sqlite3_interrupt_count==0 ){
+        sqlite3_interrupt(db);
+      }
+    }
+#endif
+
+#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
+    /* Call the progress callback if it is configured and the required number
+    ** of VDBE ops have been executed (either since this invocation of
+    ** sqlite3VdbeExec() or since last time the progress callback was called).
+    ** If the progress callback returns non-zero, exit the virtual machine with
+    ** a return code SQLITE_ABORT.
+    */
+    if( checkProgress ){
+      if( db->nProgressOps==nProgressOps ){
+        int prc;
+        prc = db->xProgress(db->pProgressArg);
+        if( prc!=0 ){
+          rc = SQLITE_INTERRUPT;
+          goto vdbe_error_halt;
+        }
+        nProgressOps = 0;
+      }
+      nProgressOps++;
+    }
+#endif
+
+    /* On any opcode with the "out2-prerelase" tag, free any
+    ** external allocations out of mem[p2] and set mem[p2] to be
+    ** an undefined integer.  Opcodes will either fill in the integer
+    ** value or convert mem[p2] to a different type.
+    */
+    assert( pOp->opflags==sqlite3OpcodeProperty[pOp->opcode] );
+    if( pOp->opflags & OPFLG_OUT2_PRERELEASE ){
+      assert( pOp->p2>0 );
+      assert( pOp->p2<=p->nMem );
+      pOut = &aMem[pOp->p2];
+      memAboutToChange(p, pOut);
+      sqlite3VdbeMemReleaseExternal(pOut);
+      pOut->flags = MEM_Int;
+    }
+
+    /* Sanity checking on other operands */
+#ifdef SQLITE_DEBUG
+    if( (pOp->opflags & OPFLG_IN1)!=0 ){
+      assert( pOp->p1>0 );
+      assert( pOp->p1<=p->nMem );
+      assert( memIsValid(&aMem[pOp->p1]) );
+      REGISTER_TRACE(pOp->p1, &aMem[pOp->p1]);
+    }
+    if( (pOp->opflags & OPFLG_IN2)!=0 ){
+      assert( pOp->p2>0 );
+      assert( pOp->p2<=p->nMem );
+      assert( memIsValid(&aMem[pOp->p2]) );
+      REGISTER_TRACE(pOp->p2, &aMem[pOp->p2]);
+    }
+    if( (pOp->opflags & OPFLG_IN3)!=0 ){
+      assert( pOp->p3>0 );
+      assert( pOp->p3<=p->nMem );
+      assert( memIsValid(&aMem[pOp->p3]) );
+      REGISTER_TRACE(pOp->p3, &aMem[pOp->p3]);
+    }
+    if( (pOp->opflags & OPFLG_OUT2)!=0 ){
+      assert( pOp->p2>0 );
+      assert( pOp->p2<=p->nMem );
+      memAboutToChange(p, &aMem[pOp->p2]);
+    }
+    if( (pOp->opflags & OPFLG_OUT3)!=0 ){
+      assert( pOp->p3>0 );
+      assert( pOp->p3<=p->nMem );
+      memAboutToChange(p, &aMem[pOp->p3]);
+    }
+#endif
+  
+    switch( pOp->opcode ){
+
+/*****************************************************************************
+** What follows is a massive switch statement where each case implements a
+** separate instruction in the virtual machine.  If we follow the usual
+** indentation conventions, each case should be indented by 6 spaces.  But
+** that is a lot of wasted space on the left margin.  So the code within
+** the switch statement will break with convention and be flush-left. Another
+** big comment (similar to this one) will mark the point in the code where
+** we transition back to normal indentation.
+**
+** The formatting of each case is important.  The makefile for SQLite
+** generates two C files "opcodes.h" and "opcodes.c" by scanning this
+** file looking for lines that begin with "case OP_".  The opcodes.h files
+** will be filled with #defines that give unique integer values to each
+** opcode and the opcodes.c file is filled with an array of strings where
+** each string is the symbolic name for the corresponding opcode.  If the
+** case statement is followed by a comment of the form "/# same as ... #/"
+** that comment is used to determine the particular value of the opcode.
+**
+** Other keywords in the comment that follows each case are used to
+** construct the OPFLG_INITIALIZER value that initializes opcodeProperty[].
+** Keywords include: in1, in2, in3, out2_prerelease, out2, out3.  See
+** the mkopcodeh.awk script for additional information.
+**
+** Documentation about VDBE opcodes is generated by scanning this file
+** for lines of that contain "Opcode:".  That line and all subsequent
+** comment lines are used in the generation of the opcode.html documentation
+** file.
+**
+** SUMMARY:
+**
+**     Formatting is important to scripts that scan this file.
+**     Do not deviate from the formatting style currently in use.
+**
+*****************************************************************************/
+
+/* Opcode:  Goto * P2 * * *
+**
+** An unconditional jump to address P2.
+** The next instruction executed will be 
+** the one at index P2 from the beginning of
+** the program.
+*/
+case OP_Goto: {             /* jump */
+  CHECK_FOR_INTERRUPT;
+  pc = pOp->p2 - 1;
+  break;
+}
+
+/* Opcode:  Gosub P1 P2 * * *
+**
+** Write the current address onto register P1
+** and then jump to address P2.
+*/
+case OP_Gosub: {            /* jump, in1 */
+  pIn1 = &aMem[pOp->p1];
+  assert( (pIn1->flags & MEM_Dyn)==0 );
+  memAboutToChange(p, pIn1);
+  pIn1->flags = MEM_Int;
+  pIn1->u.i = pc;
+  REGISTER_TRACE(pOp->p1, pIn1);
+  pc = pOp->p2 - 1;
+  break;
+}
+
+/* Opcode:  Return P1 * * * *
+**
+** Jump to the next instruction after the address in register P1.
+*/
+case OP_Return: {           /* in1 */
+  pIn1 = &aMem[pOp->p1];
+  assert( pIn1->flags & MEM_Int );
+  pc = (int)pIn1->u.i;
+  break;
+}
+
+/* Opcode:  Yield P1 * * * *
+**
+** Swap the program counter with the value in register P1.
+*/
+case OP_Yield: {            /* in1 */
+#if 0  /* local variables moved into u.aa */
+  int pcDest;
+#endif /* local variables moved into u.aa */
+  pIn1 = &aMem[pOp->p1];
+  assert( (pIn1->flags & MEM_Dyn)==0 );
+  pIn1->flags = MEM_Int;
+  u.aa.pcDest = (int)pIn1->u.i;
+  pIn1->u.i = pc;
+  REGISTER_TRACE(pOp->p1, pIn1);
+  pc = u.aa.pcDest;
+  break;
+}
+
+/* Opcode:  HaltIfNull  P1 P2 P3 P4 *
+**
+** Check the value in register P3.  If is is NULL then Halt using
+** parameter P1, P2, and P4 as if this were a Halt instruction.  If the
+** value in register P3 is not NULL, then this routine is a no-op.
+*/
+case OP_HaltIfNull: {      /* in3 */
+  pIn3 = &aMem[pOp->p3];
+  if( (pIn3->flags & MEM_Null)==0 ) break;
+  /* Fall through into OP_Halt */
+}
+
+/* Opcode:  Halt P1 P2 * P4 *
+**
+** Exit immediately.  All open cursors, etc are closed
+** automatically.
+**
+** P1 is the result code returned by sqlite3_exec(), sqlite3_reset(),
+** or sqlite3_finalize().  For a normal halt, this should be SQLITE_OK (0).
+** For errors, it can be some other value.  If P1!=0 then P2 will determine
+** whether or not to rollback the current transaction.  Do not rollback
+** if P2==OE_Fail. Do the rollback if P2==OE_Rollback.  If P2==OE_Abort,
+** then back out all changes that have occurred during this execution of the
+** VDBE, but do not rollback the transaction. 
+**
+** If P4 is not null then it is an error message string.
+**
+** There is an implied "Halt 0 0 0" instruction inserted at the very end of
+** every program.  So a jump past the last instruction of the program
+** is the same as executing Halt.
+*/
+case OP_Halt: {
+  if( pOp->p1==SQLITE_OK && p->pFrame ){
+    /* Halt the sub-program. Return control to the parent frame. */
+    VdbeFrame *pFrame = p->pFrame;
+    p->pFrame = pFrame->pParent;
+    p->nFrame--;
+    sqlite3VdbeSetChanges(db, p->nChange);
+    pc = sqlite3VdbeFrameRestore(pFrame);
+    if( pOp->p2==OE_Ignore ){
+      /* Instruction pc is the OP_Program that invoked the sub-program 
+      ** currently being halted. If the p2 instruction of this OP_Halt
+      ** instruction is set to OE_Ignore, then the sub-program is throwing
+      ** an IGNORE exception. In this case jump to the address specified
+      ** as the p2 of the calling OP_Program.  */
+      pc = p->aOp[pc].p2-1;
+    }
+    aOp = p->aOp;
+    aMem = p->aMem;
+    break;
+  }
+
+  p->rc = pOp->p1;
+  p->errorAction = (u8)pOp->p2;
+  p->pc = pc;
+  if( pOp->p4.z ){
+    assert( p->rc!=SQLITE_OK );
+    sqlite3SetString(&p->zErrMsg, db, "%s", pOp->p4.z);
+    testcase( sqlite3GlobalConfig.xLog!=0 );
+    sqlite3_log(pOp->p1, "abort at %d in [%s]: %s", pc, p->zSql, pOp->p4.z);
+  }else if( p->rc ){
+    testcase( sqlite3GlobalConfig.xLog!=0 );
+    sqlite3_log(pOp->p1, "constraint failed at %d in [%s]", pc, p->zSql);
+  }
+  rc = sqlite3VdbeHalt(p);
+  assert( rc==SQLITE_BUSY || rc==SQLITE_OK || rc==SQLITE_ERROR );
+  if( rc==SQLITE_BUSY ){
+    p->rc = rc = SQLITE_BUSY;
+  }else{
+    assert( rc==SQLITE_OK || p->rc==SQLITE_CONSTRAINT );
+    assert( rc==SQLITE_OK || db->nDeferredCons>0 );
+    rc = p->rc ? SQLITE_ERROR : SQLITE_DONE;
+  }
+  goto vdbe_return;
+}
+
+/* Opcode: Integer P1 P2 * * *
+**
+** The 32-bit integer value P1 is written into register P2.
+*/
+case OP_Integer: {         /* out2-prerelease */
+  pOut->u.i = pOp->p1;
+  break;
+}
+
+/* Opcode: Int64 * P2 * P4 *
+**
+** P4 is a pointer to a 64-bit integer value.
+** Write that value into register P2.
+*/
+case OP_Int64: {           /* out2-prerelease */
+  assert( pOp->p4.pI64!=0 );
+  pOut->u.i = *pOp->p4.pI64;
+  break;
+}
+
+#ifndef SQLITE_OMIT_FLOATING_POINT
+/* Opcode: Real * P2 * P4 *
+**
+** P4 is a pointer to a 64-bit floating point value.
+** Write that value into register P2.
+*/
+case OP_Real: {            /* same as TK_FLOAT, out2-prerelease */
+  pOut->flags = MEM_Real;
+  assert( !sqlite3IsNaN(*pOp->p4.pReal) );
+  pOut->r = *pOp->p4.pReal;
+  break;
+}
+#endif
+
+/* Opcode: String8 * P2 * P4 *
+**
+** P4 points to a nul terminated UTF-8 string. This opcode is transformed 
+** into an OP_String before it is executed for the first time.
+*/
+case OP_String8: {         /* same as TK_STRING, out2-prerelease */
+  assert( pOp->p4.z!=0 );
+  pOp->opcode = OP_String;
+  pOp->p1 = sqlite3Strlen30(pOp->p4.z);
+
+#ifndef SQLITE_OMIT_UTF16
+  if( encoding!=SQLITE_UTF8 ){
+    rc = sqlite3VdbeMemSetStr(pOut, pOp->p4.z, -1, SQLITE_UTF8, SQLITE_STATIC);
+    if( rc==SQLITE_TOOBIG ) goto too_big;
+    if( SQLITE_OK!=sqlite3VdbeChangeEncoding(pOut, encoding) ) goto no_mem;
+    assert( pOut->zMalloc==pOut->z );
+    assert( pOut->flags & MEM_Dyn );
+    pOut->zMalloc = 0;
+    pOut->flags |= MEM_Static;
+    pOut->flags &= ~MEM_Dyn;
+    if( pOp->p4type==P4_DYNAMIC ){
+      sqlite3DbFree(db, pOp->p4.z);
+    }
+    pOp->p4type = P4_DYNAMIC;
+    pOp->p4.z = pOut->z;
+    pOp->p1 = pOut->n;
+  }
+#endif
+  if( pOp->p1>db->aLimit[SQLITE_LIMIT_LENGTH] ){
+    goto too_big;
+  }
+  /* Fall through to the next case, OP_String */
+}
+  
+/* Opcode: String P1 P2 * P4 *
+**
+** The string value P4 of length P1 (bytes) is stored in register P2.
+*/
+case OP_String: {          /* out2-prerelease */
+  assert( pOp->p4.z!=0 );
+  pOut->flags = MEM_Str|MEM_Static|MEM_Term;
+  pOut->z = pOp->p4.z;
+  pOut->n = pOp->p1;
+  pOut->enc = encoding;
+  UPDATE_MAX_BLOBSIZE(pOut);
+  break;
+}
+
+/* Opcode: Null * P2 * * *
+**
+** Write a NULL into register P2.
+*/
+case OP_Null: {           /* out2-prerelease */
+  pOut->flags = MEM_Null;
+  break;
+}
+
+
+/* Opcode: Blob P1 P2 * P4
+**
+** P4 points to a blob of data P1 bytes long.  Store this
+** blob in register P2.
+*/
+case OP_Blob: {                /* out2-prerelease */
+  assert( pOp->p1 <= SQLITE_MAX_LENGTH );
+  sqlite3VdbeMemSetStr(pOut, pOp->p4.z, pOp->p1, 0, 0);
+  pOut->enc = encoding;
+  UPDATE_MAX_BLOBSIZE(pOut);
+  break;
+}
+
+/* Opcode: Variable P1 P2 * P4 *
+**
+** Transfer the values of bound parameter P1 into register P2
+**
+** If the parameter is named, then its name appears in P4 and P3==1.
+** The P4 value is used by sqlite3_bind_parameter_name().
+*/
+case OP_Variable: {            /* out2-prerelease */
+#if 0  /* local variables moved into u.ab */
+  Mem *pVar;       /* Value being transferred */
+#endif /* local variables moved into u.ab */
+
+  assert( pOp->p1>0 && pOp->p1<=p->nVar );
+  u.ab.pVar = &p->aVar[pOp->p1 - 1];
+  if( sqlite3VdbeMemTooBig(u.ab.pVar) ){
+    goto too_big;
+  }
+  sqlite3VdbeMemShallowCopy(pOut, u.ab.pVar, MEM_Static);
+  UPDATE_MAX_BLOBSIZE(pOut);
+  break;
+}
+
+/* Opcode: Move P1 P2 P3 * *
+**
+** Move the values in register P1..P1+P3-1 over into
+** registers P2..P2+P3-1.  Registers P1..P1+P1-1 are
+** left holding a NULL.  It is an error for register ranges
+** P1..P1+P3-1 and P2..P2+P3-1 to overlap.
+*/
+case OP_Move: {
+#if 0  /* local variables moved into u.ac */
+  char *zMalloc;   /* Holding variable for allocated memory */
+  int n;           /* Number of registers left to copy */
+  int p1;          /* Register to copy from */
+  int p2;          /* Register to copy to */
+#endif /* local variables moved into u.ac */
+
+  u.ac.n = pOp->p3;
+  u.ac.p1 = pOp->p1;
+  u.ac.p2 = pOp->p2;
+  assert( u.ac.n>0 && u.ac.p1>0 && u.ac.p2>0 );
+  assert( u.ac.p1+u.ac.n<=u.ac.p2 || u.ac.p2+u.ac.n<=u.ac.p1 );
+
+  pIn1 = &aMem[u.ac.p1];
+  pOut = &aMem[u.ac.p2];
+  while( u.ac.n-- ){
+    assert( pOut<=&aMem[p->nMem] );
+    assert( pIn1<=&aMem[p->nMem] );
+    assert( memIsValid(pIn1) );
+    memAboutToChange(p, pOut);
+    u.ac.zMalloc = pOut->zMalloc;
+    pOut->zMalloc = 0;
+    sqlite3VdbeMemMove(pOut, pIn1);
+    pIn1->zMalloc = u.ac.zMalloc;
+    REGISTER_TRACE(u.ac.p2++, pOut);
+    pIn1++;
+    pOut++;
+  }
+  break;
+}
+
+/* Opcode: Copy P1 P2 * * *
+**
+** Make a copy of register P1 into register P2.
+**
+** This instruction makes a deep copy of the value.  A duplicate
+** is made of any string or blob constant.  See also OP_SCopy.
+*/
+case OP_Copy: {             /* in1, out2 */
+  pIn1 = &aMem[pOp->p1];
+  pOut = &aMem[pOp->p2];
+  assert( pOut!=pIn1 );
+  sqlite3VdbeMemShallowCopy(pOut, pIn1, MEM_Ephem);
+  Deephemeralize(pOut);
+  REGISTER_TRACE(pOp->p2, pOut);
+  break;
+}
+
+/* Opcode: SCopy P1 P2 * * *
+**
+** Make a shallow copy of register P1 into register P2.
+**
+** This instruction makes a shallow copy of the value.  If the value
+** is a string or blob, then the copy is only a pointer to the
+** original and hence if the original changes so will the copy.
+** Worse, if the original is deallocated, the copy becomes invalid.
+** Thus the program must guarantee that the original will not change
+** during the lifetime of the copy.  Use OP_Copy to make a complete
+** copy.
+*/
+case OP_SCopy: {            /* in1, out2 */
+  pIn1 = &aMem[pOp->p1];
+  pOut = &aMem[pOp->p2];
+  assert( pOut!=pIn1 );
+  sqlite3VdbeMemShallowCopy(pOut, pIn1, MEM_Ephem);
+#ifdef SQLITE_DEBUG
+  if( pOut->pScopyFrom==0 ) pOut->pScopyFrom = pIn1;
+#endif
+  REGISTER_TRACE(pOp->p2, pOut);
+  break;
+}
+
+/* Opcode: ResultRow P1 P2 * * *
+**
+** The registers P1 through P1+P2-1 contain a single row of
+** results. This opcode causes the sqlite3_step() call to terminate
+** with an SQLITE_ROW return code and it sets up the sqlite3_stmt
+** structure to provide access to the top P1 values as the result
+** row.
+*/
+case OP_ResultRow: {
+#if 0  /* local variables moved into u.ad */
+  Mem *pMem;
+  int i;
+#endif /* local variables moved into u.ad */
+  assert( p->nResColumn==pOp->p2 );
+  assert( pOp->p1>0 );
+  assert( pOp->p1+pOp->p2<=p->nMem+1 );
+
+  /* If this statement has violated immediate foreign key constraints, do
+  ** not return the number of rows modified. And do not RELEASE the statement
+  ** transaction. It needs to be rolled back.  */
+  if( SQLITE_OK!=(rc = sqlite3VdbeCheckFk(p, 0)) ){
+    assert( db->flags&SQLITE_CountRows );
+    assert( p->usesStmtJournal );
+    break;
+  }
+
+  /* If the SQLITE_CountRows flag is set in sqlite3.flags mask, then
+  ** DML statements invoke this opcode to return the number of rows
+  ** modified to the user. This is the only way that a VM that
+  ** opens a statement transaction may invoke this opcode.
+  **
+  ** In case this is such a statement, close any statement transaction
+  ** opened by this VM before returning control to the user. This is to
+  ** ensure that statement-transactions are always nested, not overlapping.
+  ** If the open statement-transaction is not closed here, then the user
+  ** may step another VM that opens its own statement transaction. This
+  ** may lead to overlapping statement transactions.
+  **
+  ** The statement transaction is never a top-level transaction.  Hence
+  ** the RELEASE call below can never fail.
+  */
+  assert( p->iStatement==0 || db->flags&SQLITE_CountRows );
+  rc = sqlite3VdbeCloseStatement(p, SAVEPOINT_RELEASE);
+  if( NEVER(rc!=SQLITE_OK) ){
+    break;
+  }
+
+  /* Invalidate all ephemeral cursor row caches */
+  p->cacheCtr = (p->cacheCtr + 2)|1;
+
+  /* Make sure the results of the current row are \000 terminated
+  ** and have an assigned type.  The results are de-ephemeralized as
+  ** as side effect.
+  */
+  u.ad.pMem = p->pResultSet = &aMem[pOp->p1];
+  for(u.ad.i=0; u.ad.i<pOp->p2; u.ad.i++){
+    assert( memIsValid(&u.ad.pMem[u.ad.i]) );
+    Deephemeralize(&u.ad.pMem[u.ad.i]);
+    assert( (u.ad.pMem[u.ad.i].flags & MEM_Ephem)==0
+            || (u.ad.pMem[u.ad.i].flags & (MEM_Str|MEM_Blob))==0 );
+    sqlite3VdbeMemNulTerminate(&u.ad.pMem[u.ad.i]);
+    sqlite3VdbeMemStoreType(&u.ad.pMem[u.ad.i]);
+    REGISTER_TRACE(pOp->p1+u.ad.i, &u.ad.pMem[u.ad.i]);
+  }
+  if( db->mallocFailed ) goto no_mem;
+
+  /* Return SQLITE_ROW
+  */
+  p->pc = pc + 1;
+  rc = SQLITE_ROW;
+  goto vdbe_return;
+}
+
+/* Opcode: Concat P1 P2 P3 * *
+**
+** Add the text in register P1 onto the end of the text in
+** register P2 and store the result in register P3.
+** If either the P1 or P2 text are NULL then store NULL in P3.
+**
+**   P3 = P2 || P1
+**
+** It is illegal for P1 and P3 to be the same register. Sometimes,
+** if P3 is the same register as P2, the implementation is able
+** to avoid a memcpy().
+*/
+case OP_Concat: {           /* same as TK_CONCAT, in1, in2, out3 */
+#if 0  /* local variables moved into u.ae */
+  i64 nByte;
+#endif /* local variables moved into u.ae */
+
+  pIn1 = &aMem[pOp->p1];
+  pIn2 = &aMem[pOp->p2];
+  pOut = &aMem[pOp->p3];
+  assert( pIn1!=pOut );
+  if( (pIn1->flags | pIn2->flags) & MEM_Null ){
+    sqlite3VdbeMemSetNull(pOut);
+    break;
+  }
+  if( ExpandBlob(pIn1) || ExpandBlob(pIn2) ) goto no_mem;
+  Stringify(pIn1, encoding);
+  Stringify(pIn2, encoding);
+  u.ae.nByte = pIn1->n + pIn2->n;
+  if( u.ae.nByte>db->aLimit[SQLITE_LIMIT_LENGTH] ){
+    goto too_big;
+  }
+  MemSetTypeFlag(pOut, MEM_Str);
+  if( sqlite3VdbeMemGrow(pOut, (int)u.ae.nByte+2, pOut==pIn2) ){
+    goto no_mem;
+  }
+  if( pOut!=pIn2 ){
+    memcpy(pOut->z, pIn2->z, pIn2->n);
+  }
+  memcpy(&pOut->z[pIn2->n], pIn1->z, pIn1->n);
+  pOut->z[u.ae.nByte] = 0;
+  pOut->z[u.ae.nByte+1] = 0;
+  pOut->flags |= MEM_Term;
+  pOut->n = (int)u.ae.nByte;
+  pOut->enc = encoding;
+  UPDATE_MAX_BLOBSIZE(pOut);
+  break;
+}
+
+/* Opcode: Add P1 P2 P3 * *
+**
+** Add the value in register P1 to the value in register P2
+** and store the result in register P3.
+** If either input is NULL, the result is NULL.
+*/
+/* Opcode: Multiply P1 P2 P3 * *
+**
+**
+** Multiply the value in register P1 by the value in register P2
+** and store the result in register P3.
+** If either input is NULL, the result is NULL.
+*/
+/* Opcode: Subtract P1 P2 P3 * *
+**
+** Subtract the value in register P1 from the value in register P2
+** and store the result in register P3.
+** If either input is NULL, the result is NULL.
+*/
+/* Opcode: Divide P1 P2 P3 * *
+**
+** Divide the value in register P1 by the value in register P2
+** and store the result in register P3 (P3=P2/P1). If the value in 
+** register P1 is zero, then the result is NULL. If either input is 
+** NULL, the result is NULL.
+*/
+/* Opcode: Remainder P1 P2 P3 * *
+**
+** Compute the remainder after integer division of the value in
+** register P1 by the value in register P2 and store the result in P3. 
+** If the value in register P2 is zero the result is NULL.
+** If either operand is NULL, the result is NULL.
+*/
+case OP_Add:                   /* same as TK_PLUS, in1, in2, out3 */
+case OP_Subtract:              /* same as TK_MINUS, in1, in2, out3 */
+case OP_Multiply:              /* same as TK_STAR, in1, in2, out3 */
+case OP_Divide:                /* same as TK_SLASH, in1, in2, out3 */
+case OP_Remainder: {           /* same as TK_REM, in1, in2, out3 */
+#if 0  /* local variables moved into u.af */
+  int flags;      /* Combined MEM_* flags from both inputs */
+  i64 iA;         /* Integer value of left operand */
+  i64 iB;         /* Integer value of right operand */
+  double rA;      /* Real value of left operand */
+  double rB;      /* Real value of right operand */
+#endif /* local variables moved into u.af */
+
+  pIn1 = &aMem[pOp->p1];
+  applyNumericAffinity(pIn1);
+  pIn2 = &aMem[pOp->p2];
+  applyNumericAffinity(pIn2);
+  pOut = &aMem[pOp->p3];
+  u.af.flags = pIn1->flags | pIn2->flags;
+  if( (u.af.flags & MEM_Null)!=0 ) goto arithmetic_result_is_null;
+  if( (pIn1->flags & pIn2->flags & MEM_Int)==MEM_Int ){
+    u.af.iA = pIn1->u.i;
+    u.af.iB = pIn2->u.i;
+    switch( pOp->opcode ){
+      case OP_Add:       if( sqlite3AddInt64(&u.af.iB,u.af.iA) ) goto fp_math;  break;
+      case OP_Subtract:  if( sqlite3SubInt64(&u.af.iB,u.af.iA) ) goto fp_math;  break;
+      case OP_Multiply:  if( sqlite3MulInt64(&u.af.iB,u.af.iA) ) goto fp_math;  break;
+      case OP_Divide: {
+        if( u.af.iA==0 ) goto arithmetic_result_is_null;
+        if( u.af.iA==-1 && u.af.iB==SMALLEST_INT64 ) goto fp_math;
+        u.af.iB /= u.af.iA;
+        break;
+      }
+      default: {
+        if( u.af.iA==0 ) goto arithmetic_result_is_null;
+        if( u.af.iA==-1 ) u.af.iA = 1;
+        u.af.iB %= u.af.iA;
+        break;
+      }
+    }
+    pOut->u.i = u.af.iB;
+    MemSetTypeFlag(pOut, MEM_Int);
+  }else{
+fp_math:
+    u.af.rA = sqlite3VdbeRealValue(pIn1);
+    u.af.rB = sqlite3VdbeRealValue(pIn2);
+    switch( pOp->opcode ){
+      case OP_Add:         u.af.rB += u.af.rA;       break;
+      case OP_Subtract:    u.af.rB -= u.af.rA;       break;
+      case OP_Multiply:    u.af.rB *= u.af.rA;       break;
+      case OP_Divide: {
+        /* (double)0 In case of SQLITE_OMIT_FLOATING_POINT... */
+        if( u.af.rA==(double)0 ) goto arithmetic_result_is_null;
+        u.af.rB /= u.af.rA;
+        break;
+      }
+      default: {
+        u.af.iA = (i64)u.af.rA;
+        u.af.iB = (i64)u.af.rB;
+        if( u.af.iA==0 ) goto arithmetic_result_is_null;
+        if( u.af.iA==-1 ) u.af.iA = 1;
+        u.af.rB = (double)(u.af.iB % u.af.iA);
+        break;
+      }
+    }
+#ifdef SQLITE_OMIT_FLOATING_POINT
+    pOut->u.i = u.af.rB;
+    MemSetTypeFlag(pOut, MEM_Int);
+#else
+    if( sqlite3IsNaN(u.af.rB) ){
+      goto arithmetic_result_is_null;
+    }
+    pOut->r = u.af.rB;
+    MemSetTypeFlag(pOut, MEM_Real);
+    if( (u.af.flags & MEM_Real)==0 ){
+      sqlite3VdbeIntegerAffinity(pOut);
+    }
+#endif
+  }
+  break;
+
+arithmetic_result_is_null:
+  sqlite3VdbeMemSetNull(pOut);
+  break;
+}
+
+/* Opcode: CollSeq * * P4
+**
+** P4 is a pointer to a CollSeq struct. If the next call to a user function
+** or aggregate calls sqlite3GetFuncCollSeq(), this collation sequence will
+** be returned. This is used by the built-in min(), max() and nullif()
+** functions.
+**
+** The interface used by the implementation of the aforementioned functions
+** to retrieve the collation sequence set by this opcode is not available
+** publicly, only to user functions defined in func.c.
+*/
+case OP_CollSeq: {
+  assert( pOp->p4type==P4_COLLSEQ );
+  break;
+}
+
+/* Opcode: Function P1 P2 P3 P4 P5
+**
+** Invoke a user function (P4 is a pointer to a Function structure that
+** defines the function) with P5 arguments taken from register P2 and
+** successors.  The result of the function is stored in register P3.
+** Register P3 must not be one of the function inputs.
+**
+** P1 is a 32-bit bitmask indicating whether or not each argument to the 
+** function was determined to be constant at compile time. If the first
+** argument was constant then bit 0 of P1 is set. This is used to determine
+** whether meta data associated with a user function argument using the
+** sqlite3_set_auxdata() API may be safely retained until the next
+** invocation of this opcode.
+**
+** See also: AggStep and AggFinal
+*/
+case OP_Function: {
+#if 0  /* local variables moved into u.ag */
+  int i;
+  Mem *pArg;
+  sqlite3_context ctx;
+  sqlite3_value **apVal;
+  int n;
+#endif /* local variables moved into u.ag */
+
+  u.ag.n = pOp->p5;
+  u.ag.apVal = p->apArg;
+  assert( u.ag.apVal || u.ag.n==0 );
+  assert( pOp->p3>0 && pOp->p3<=p->nMem );
+  pOut = &aMem[pOp->p3];
+  memAboutToChange(p, pOut);
+
+  assert( u.ag.n==0 || (pOp->p2>0 && pOp->p2+u.ag.n<=p->nMem+1) );
+  assert( pOp->p3<pOp->p2 || pOp->p3>=pOp->p2+u.ag.n );
+  u.ag.pArg = &aMem[pOp->p2];
+  for(u.ag.i=0; u.ag.i<u.ag.n; u.ag.i++, u.ag.pArg++){
+    assert( memIsValid(u.ag.pArg) );
+    u.ag.apVal[u.ag.i] = u.ag.pArg;
+    Deephemeralize(u.ag.pArg);
+    sqlite3VdbeMemStoreType(u.ag.pArg);
+    REGISTER_TRACE(pOp->p2+u.ag.i, u.ag.pArg);
+  }
+
+  assert( pOp->p4type==P4_FUNCDEF || pOp->p4type==P4_VDBEFUNC );
+  if( pOp->p4type==P4_FUNCDEF ){
+    u.ag.ctx.pFunc = pOp->p4.pFunc;
+    u.ag.ctx.pVdbeFunc = 0;
+  }else{
+    u.ag.ctx.pVdbeFunc = (VdbeFunc*)pOp->p4.pVdbeFunc;
+    u.ag.ctx.pFunc = u.ag.ctx.pVdbeFunc->pFunc;
+  }
+
+  u.ag.ctx.s.flags = MEM_Null;
+  u.ag.ctx.s.db = db;
+  u.ag.ctx.s.xDel = 0;
+  u.ag.ctx.s.zMalloc = 0;
+
+  /* The output cell may already have a buffer allocated. Move
+  ** the pointer to u.ag.ctx.s so in case the user-function can use
+  ** the already allocated buffer instead of allocating a new one.
+  */
+  sqlite3VdbeMemMove(&u.ag.ctx.s, pOut);
+  MemSetTypeFlag(&u.ag.ctx.s, MEM_Null);
+
+  u.ag.ctx.isError = 0;
+  if( u.ag.ctx.pFunc->flags & SQLITE_FUNC_NEEDCOLL ){
+    assert( pOp>aOp );
+    assert( pOp[-1].p4type==P4_COLLSEQ );
+    assert( pOp[-1].opcode==OP_CollSeq );
+    u.ag.ctx.pColl = pOp[-1].p4.pColl;
+  }
+  (*u.ag.ctx.pFunc->xFunc)(&u.ag.ctx, u.ag.n, u.ag.apVal); /* IMP: R-24505-23230 */
+  if( db->mallocFailed ){
+    /* Even though a malloc() has failed, the implementation of the
+    ** user function may have called an sqlite3_result_XXX() function
+    ** to return a value. The following call releases any resources
+    ** associated with such a value.
+    */
+    sqlite3VdbeMemRelease(&u.ag.ctx.s);
+    goto no_mem;
+  }
+
+  /* If any auxiliary data functions have been called by this user function,
+  ** immediately call the destructor for any non-static values.
+  */
+  if( u.ag.ctx.pVdbeFunc ){
+    sqlite3VdbeDeleteAuxData(u.ag.ctx.pVdbeFunc, pOp->p1);
+    pOp->p4.pVdbeFunc = u.ag.ctx.pVdbeFunc;
+    pOp->p4type = P4_VDBEFUNC;
+  }
+
+  /* If the function returned an error, throw an exception */
+  if( u.ag.ctx.isError ){
+    sqlite3SetString(&p->zErrMsg, db, "%s", sqlite3_value_text(&u.ag.ctx.s));
+    rc = u.ag.ctx.isError;
+  }
+
+  /* Copy the result of the function into register P3 */
+  sqlite3VdbeChangeEncoding(&u.ag.ctx.s, encoding);
+  sqlite3VdbeMemMove(pOut, &u.ag.ctx.s);
+  if( sqlite3VdbeMemTooBig(pOut) ){
+    goto too_big;
+  }
+
+#if 0
+  /* The app-defined function has done something that as caused this
+  ** statement to expire.  (Perhaps the function called sqlite3_exec()
+  ** with a CREATE TABLE statement.)
+  */
+  if( p->expired ) rc = SQLITE_ABORT;
+#endif
+
+  REGISTER_TRACE(pOp->p3, pOut);
+  UPDATE_MAX_BLOBSIZE(pOut);
+  break;
+}
+
+/* Opcode: BitAnd P1 P2 P3 * *
+**
+** Take the bit-wise AND of the values in register P1 and P2 and
+** store the result in register P3.
+** If either input is NULL, the result is NULL.
+*/
+/* Opcode: BitOr P1 P2 P3 * *
+**
+** Take the bit-wise OR of the values in register P1 and P2 and
+** store the result in register P3.
+** If either input is NULL, the result is NULL.
+*/
+/* Opcode: ShiftLeft P1 P2 P3 * *
+**
+** Shift the integer value in register P2 to the left by the
+** number of bits specified by the integer in register P1.
+** Store the result in register P3.
+** If either input is NULL, the result is NULL.
+*/
+/* Opcode: ShiftRight P1 P2 P3 * *
+**
+** Shift the integer value in register P2 to the right by the
+** number of bits specified by the integer in register P1.
+** Store the result in register P3.
+** If either input is NULL, the result is NULL.
+*/
+case OP_BitAnd:                 /* same as TK_BITAND, in1, in2, out3 */
+case OP_BitOr:                  /* same as TK_BITOR, in1, in2, out3 */
+case OP_ShiftLeft:              /* same as TK_LSHIFT, in1, in2, out3 */
+case OP_ShiftRight: {           /* same as TK_RSHIFT, in1, in2, out3 */
+#if 0  /* local variables moved into u.ah */
+  i64 iA;
+  u64 uA;
+  i64 iB;
+  u8 op;
+#endif /* local variables moved into u.ah */
+
+  pIn1 = &aMem[pOp->p1];
+  pIn2 = &aMem[pOp->p2];
+  pOut = &aMem[pOp->p3];
+  if( (pIn1->flags | pIn2->flags) & MEM_Null ){
+    sqlite3VdbeMemSetNull(pOut);
+    break;
+  }
+  u.ah.iA = sqlite3VdbeIntValue(pIn2);
+  u.ah.iB = sqlite3VdbeIntValue(pIn1);
+  u.ah.op = pOp->opcode;
+  if( u.ah.op==OP_BitAnd ){
+    u.ah.iA &= u.ah.iB;
+  }else if( u.ah.op==OP_BitOr ){
+    u.ah.iA |= u.ah.iB;
+  }else if( u.ah.iB!=0 ){
+    assert( u.ah.op==OP_ShiftRight || u.ah.op==OP_ShiftLeft );
+
+    /* If shifting by a negative amount, shift in the other direction */
+    if( u.ah.iB<0 ){
+      assert( OP_ShiftRight==OP_ShiftLeft+1 );
+      u.ah.op = 2*OP_ShiftLeft + 1 - u.ah.op;
+      u.ah.iB = u.ah.iB>(-64) ? -u.ah.iB : 64;
+    }
+
+    if( u.ah.iB>=64 ){
+      u.ah.iA = (u.ah.iA>=0 || u.ah.op==OP_ShiftLeft) ? 0 : -1;
+    }else{
+      memcpy(&u.ah.uA, &u.ah.iA, sizeof(u.ah.uA));
+      if( u.ah.op==OP_ShiftLeft ){
+        u.ah.uA <<= u.ah.iB;
+      }else{
+        u.ah.uA >>= u.ah.iB;
+        /* Sign-extend on a right shift of a negative number */
+        if( u.ah.iA<0 ) u.ah.uA |= ((((u64)0xffffffff)<<32)|0xffffffff) << (64-u.ah.iB);
+      }
+      memcpy(&u.ah.iA, &u.ah.uA, sizeof(u.ah.iA));
+    }
+  }
+  pOut->u.i = u.ah.iA;
+  MemSetTypeFlag(pOut, MEM_Int);
+  break;
+}
+
+/* Opcode: AddImm  P1 P2 * * *
+** 
+** Add the constant P2 to the value in register P1.
+** The result is always an integer.
+**
+** To force any register to be an integer, just add 0.
+*/
+case OP_AddImm: {            /* in1 */
+  pIn1 = &aMem[pOp->p1];
+  memAboutToChange(p, pIn1);
+  sqlite3VdbeMemIntegerify(pIn1);
+  pIn1->u.i += pOp->p2;
+  break;
+}
+
+/* Opcode: MustBeInt P1 P2 * * *
+** 
+** Force the value in register P1 to be an integer.  If the value
+** in P1 is not an integer and cannot be converted into an integer
+** without data loss, then jump immediately to P2, or if P2==0
+** raise an SQLITE_MISMATCH exception.
+*/
+case OP_MustBeInt: {            /* jump, in1 */
+  pIn1 = &aMem[pOp->p1];
+  applyAffinity(pIn1, SQLITE_AFF_NUMERIC, encoding);
+  if( (pIn1->flags & MEM_Int)==0 ){
+    if( pOp->p2==0 ){
+      rc = SQLITE_MISMATCH;
+      goto abort_due_to_error;
+    }else{
+      pc = pOp->p2 - 1;
+    }
+  }else{
+    MemSetTypeFlag(pIn1, MEM_Int);
+  }
+  break;
+}
+
+#ifndef SQLITE_OMIT_FLOATING_POINT
+/* Opcode: RealAffinity P1 * * * *
+**
+** If register P1 holds an integer convert it to a real value.
+**
+** This opcode is used when extracting information from a column that
+** has REAL affinity.  Such column values may still be stored as
+** integers, for space efficiency, but after extraction we want them
+** to have only a real value.
+*/
+case OP_RealAffinity: {                  /* in1 */
+  pIn1 = &aMem[pOp->p1];
+  if( pIn1->flags & MEM_Int ){
+    sqlite3VdbeMemRealify(pIn1);
+  }
+  break;
+}
+#endif
+
+#ifndef SQLITE_OMIT_CAST
+/* Opcode: ToText P1 * * * *
+**
+** Force the value in register P1 to be text.
+** If the value is numeric, convert it to a string using the
+** equivalent of printf().  Blob values are unchanged and
+** are afterwards simply interpreted as text.
+**
+** A NULL value is not changed by this routine.  It remains NULL.
+*/
+case OP_ToText: {                  /* same as TK_TO_TEXT, in1 */
+  pIn1 = &aMem[pOp->p1];
+  memAboutToChange(p, pIn1);
+  if( pIn1->flags & MEM_Null ) break;
+  assert( MEM_Str==(MEM_Blob>>3) );
+  pIn1->flags |= (pIn1->flags&MEM_Blob)>>3;
+  applyAffinity(pIn1, SQLITE_AFF_TEXT, encoding);
+  rc = ExpandBlob(pIn1);
+  assert( pIn1->flags & MEM_Str || db->mallocFailed );
+  pIn1->flags &= ~(MEM_Int|MEM_Real|MEM_Blob|MEM_Zero);
+  UPDATE_MAX_BLOBSIZE(pIn1);
+  break;
+}
+
+/* Opcode: ToBlob P1 * * * *
+**
+** Force the value in register P1 to be a BLOB.
+** If the value is numeric, convert it to a string first.
+** Strings are simply reinterpreted as blobs with no change
+** to the underlying data.
+**
+** A NULL value is not changed by this routine.  It remains NULL.
+*/
+case OP_ToBlob: {                  /* same as TK_TO_BLOB, in1 */
+  pIn1 = &aMem[pOp->p1];
+  if( pIn1->flags & MEM_Null ) break;
+  if( (pIn1->flags & MEM_Blob)==0 ){
+    applyAffinity(pIn1, SQLITE_AFF_TEXT, encoding);
+    assert( pIn1->flags & MEM_Str || db->mallocFailed );
+    MemSetTypeFlag(pIn1, MEM_Blob);
+  }else{
+    pIn1->flags &= ~(MEM_TypeMask&~MEM_Blob);
+  }
+  UPDATE_MAX_BLOBSIZE(pIn1);
+  break;
+}
+
+/* Opcode: ToNumeric P1 * * * *
+**
+** Force the value in register P1 to be numeric (either an
+** integer or a floating-point number.)
+** If the value is text or blob, try to convert it to an using the
+** equivalent of atoi() or atof() and store 0 if no such conversion 
+** is possible.
+**
+** A NULL value is not changed by this routine.  It remains NULL.
+*/
+case OP_ToNumeric: {                  /* same as TK_TO_NUMERIC, in1 */
+  pIn1 = &aMem[pOp->p1];
+  sqlite3VdbeMemNumerify(pIn1);
+  break;
+}
+#endif /* SQLITE_OMIT_CAST */
+
+/* Opcode: ToInt P1 * * * *
+**
+** Force the value in register P1 to be an integer.  If
+** The value is currently a real number, drop its fractional part.
+** If the value is text or blob, try to convert it to an integer using the
+** equivalent of atoi() and store 0 if no such conversion is possible.
+**
+** A NULL value is not changed by this routine.  It remains NULL.
+*/
+case OP_ToInt: {                  /* same as TK_TO_INT, in1 */
+  pIn1 = &aMem[pOp->p1];
+  if( (pIn1->flags & MEM_Null)==0 ){
+    sqlite3VdbeMemIntegerify(pIn1);
+  }
+  break;
+}
+
+#if !defined(SQLITE_OMIT_CAST) && !defined(SQLITE_OMIT_FLOATING_POINT)
+/* Opcode: ToReal P1 * * * *
+**
+** Force the value in register P1 to be a floating point number.
+** If The value is currently an integer, convert it.
+** If the value is text or blob, try to convert it to an integer using the
+** equivalent of atoi() and store 0.0 if no such conversion is possible.
+**
+** A NULL value is not changed by this routine.  It remains NULL.
+*/
+case OP_ToReal: {                  /* same as TK_TO_REAL, in1 */
+  pIn1 = &aMem[pOp->p1];
+  memAboutToChange(p, pIn1);
+  if( (pIn1->flags & MEM_Null)==0 ){
+    sqlite3VdbeMemRealify(pIn1);
+  }
+  break;
+}
+#endif /* !defined(SQLITE_OMIT_CAST) && !defined(SQLITE_OMIT_FLOATING_POINT) */
+
+/* Opcode: Lt P1 P2 P3 P4 P5
+**
+** Compare the values in register P1 and P3.  If reg(P3)<reg(P1) then
+** jump to address P2.  
+**
+** If the SQLITE_JUMPIFNULL bit of P5 is set and either reg(P1) or
+** reg(P3) is NULL then take the jump.  If the SQLITE_JUMPIFNULL 
+** bit is clear then fall through if either operand is NULL.
+**
+** The SQLITE_AFF_MASK portion of P5 must be an affinity character -
+** SQLITE_AFF_TEXT, SQLITE_AFF_INTEGER, and so forth. An attempt is made 
+** to coerce both inputs according to this affinity before the
+** comparison is made. If the SQLITE_AFF_MASK is 0x00, then numeric
+** affinity is used. Note that the affinity conversions are stored
+** back into the input registers P1 and P3.  So this opcode can cause
+** persistent changes to registers P1 and P3.
+**
+** Once any conversions have taken place, and neither value is NULL, 
+** the values are compared. If both values are blobs then memcmp() is
+** used to determine the results of the comparison.  If both values
+** are text, then the appropriate collating function specified in
+** P4 is  used to do the comparison.  If P4 is not specified then
+** memcmp() is used to compare text string.  If both values are
+** numeric, then a numeric comparison is used. If the two values
+** are of different types, then numbers are considered less than
+** strings and strings are considered less than blobs.
+**
+** If the SQLITE_STOREP2 bit of P5 is set, then do not jump.  Instead,
+** store a boolean result (either 0, or 1, or NULL) in register P2.
+*/
+/* Opcode: Ne P1 P2 P3 P4 P5
+**
+** This works just like the Lt opcode except that the jump is taken if
+** the operands in registers P1 and P3 are not equal.  See the Lt opcode for
+** additional information.
+**
+** If SQLITE_NULLEQ is set in P5 then the result of comparison is always either
+** true or false and is never NULL.  If both operands are NULL then the result
+** of comparison is false.  If either operand is NULL then the result is true.
+** If neither operand is NULL the the result is the same as it would be if
+** the SQLITE_NULLEQ flag were omitted from P5.
+*/
+/* Opcode: Eq P1 P2 P3 P4 P5
+**
+** This works just like the Lt opcode except that the jump is taken if
+** the operands in registers P1 and P3 are equal.
+** See the Lt opcode for additional information.
+**
+** If SQLITE_NULLEQ is set in P5 then the result of comparison is always either
+** true or false and is never NULL.  If both operands are NULL then the result
+** of comparison is true.  If either operand is NULL then the result is false.
+** If neither operand is NULL the the result is the same as it would be if
+** the SQLITE_NULLEQ flag were omitted from P5.
+*/
+/* Opcode: Le P1 P2 P3 P4 P5
+**
+** This works just like the Lt opcode except that the jump is taken if
+** the content of register P3 is less than or equal to the content of
+** register P1.  See the Lt opcode for additional information.
+*/
+/* Opcode: Gt P1 P2 P3 P4 P5
+**
+** This works just like the Lt opcode except that the jump is taken if
+** the content of register P3 is greater than the content of
+** register P1.  See the Lt opcode for additional information.
+*/
+/* Opcode: Ge P1 P2 P3 P4 P5
+**
+** This works just like the Lt opcode except that the jump is taken if
+** the content of register P3 is greater than or equal to the content of
+** register P1.  See the Lt opcode for additional information.
+*/
+case OP_Eq:               /* same as TK_EQ, jump, in1, in3 */
+case OP_Ne:               /* same as TK_NE, jump, in1, in3 */
+case OP_Lt:               /* same as TK_LT, jump, in1, in3 */
+case OP_Le:               /* same as TK_LE, jump, in1, in3 */
+case OP_Gt:               /* same as TK_GT, jump, in1, in3 */
+case OP_Ge: {             /* same as TK_GE, jump, in1, in3 */
+#if 0  /* local variables moved into u.ai */
+  int res;            /* Result of the comparison of pIn1 against pIn3 */
+  char affinity;      /* Affinity to use for comparison */
+  u16 flags1;         /* Copy of initial value of pIn1->flags */
+  u16 flags3;         /* Copy of initial value of pIn3->flags */
+#endif /* local variables moved into u.ai */
+
+  pIn1 = &aMem[pOp->p1];
+  pIn3 = &aMem[pOp->p3];
+  u.ai.flags1 = pIn1->flags;
+  u.ai.flags3 = pIn3->flags;
+  if( (pIn1->flags | pIn3->flags)&MEM_Null ){
+    /* One or both operands are NULL */
+    if( pOp->p5 & SQLITE_NULLEQ ){
+      /* If SQLITE_NULLEQ is set (which will only happen if the operator is
+      ** OP_Eq or OP_Ne) then take the jump or not depending on whether
+      ** or not both operands are null.
+      */
+      assert( pOp->opcode==OP_Eq || pOp->opcode==OP_Ne );
+      u.ai.res = (pIn1->flags & pIn3->flags & MEM_Null)==0;
+    }else{
+      /* SQLITE_NULLEQ is clear and at least one operand is NULL,
+      ** then the result is always NULL.
+      ** The jump is taken if the SQLITE_JUMPIFNULL bit is set.
+      */
+      if( pOp->p5 & SQLITE_STOREP2 ){
+        pOut = &aMem[pOp->p2];
+        MemSetTypeFlag(pOut, MEM_Null);
+        REGISTER_TRACE(pOp->p2, pOut);
+      }else if( pOp->p5 & SQLITE_JUMPIFNULL ){
+        pc = pOp->p2-1;
+      }
+      break;
+    }
+  }else{
+    /* Neither operand is NULL.  Do a comparison. */
+    u.ai.affinity = pOp->p5 & SQLITE_AFF_MASK;
+    if( u.ai.affinity ){
+      applyAffinity(pIn1, u.ai.affinity, encoding);
+      applyAffinity(pIn3, u.ai.affinity, encoding);
+      if( db->mallocFailed ) goto no_mem;
+    }
+
+    assert( pOp->p4type==P4_COLLSEQ || pOp->p4.pColl==0 );
+    ExpandBlob(pIn1);
+    ExpandBlob(pIn3);
+    u.ai.res = sqlite3MemCompare(pIn3, pIn1, pOp->p4.pColl);
+  }
+  switch( pOp->opcode ){
+    case OP_Eq:    u.ai.res = u.ai.res==0;     break;
+    case OP_Ne:    u.ai.res = u.ai.res!=0;     break;
+    case OP_Lt:    u.ai.res = u.ai.res<0;      break;
+    case OP_Le:    u.ai.res = u.ai.res<=0;     break;
+    case OP_Gt:    u.ai.res = u.ai.res>0;      break;
+    default:       u.ai.res = u.ai.res>=0;     break;
+  }
+
+  if( pOp->p5 & SQLITE_STOREP2 ){
+    pOut = &aMem[pOp->p2];
+    memAboutToChange(p, pOut);
+    MemSetTypeFlag(pOut, MEM_Int);
+    pOut->u.i = u.ai.res;
+    REGISTER_TRACE(pOp->p2, pOut);
+  }else if( u.ai.res ){
+    pc = pOp->p2-1;
+  }
+
+  /* Undo any changes made by applyAffinity() to the input registers. */
+  pIn1->flags = (pIn1->flags&~MEM_TypeMask) | (u.ai.flags1&MEM_TypeMask);
+  pIn3->flags = (pIn3->flags&~MEM_TypeMask) | (u.ai.flags3&MEM_TypeMask);
+  break;
+}
+
+/* Opcode: Permutation * * * P4 *
+**
+** Set the permutation used by the OP_Compare operator to be the array
+** of integers in P4.
+**
+** The permutation is only valid until the next OP_Permutation, OP_Compare,
+** OP_Halt, or OP_ResultRow.  Typically the OP_Permutation should occur
+** immediately prior to the OP_Compare.
+*/
+case OP_Permutation: {
+  assert( pOp->p4type==P4_INTARRAY );
+  assert( pOp->p4.ai );
+  aPermute = pOp->p4.ai;
+  break;
+}
+
+/* Opcode: Compare P1 P2 P3 P4 *
+**
+** Compare two vectors of registers in reg(P1)..reg(P1+P3-1) (call this
+** vector "A") and in reg(P2)..reg(P2+P3-1) ("B").  Save the result of
+** the comparison for use by the next OP_Jump instruct.
+**
+** P4 is a KeyInfo structure that defines collating sequences and sort
+** orders for the comparison.  The permutation applies to registers
+** only.  The KeyInfo elements are used sequentially.
+**
+** The comparison is a sort comparison, so NULLs compare equal,
+** NULLs are less than numbers, numbers are less than strings,
+** and strings are less than blobs.
+*/
+case OP_Compare: {
+#if 0  /* local variables moved into u.aj */
+  int n;
+  int i;
+  int p1;
+  int p2;
+  const KeyInfo *pKeyInfo;
+  int idx;
+  CollSeq *pColl;    /* Collating sequence to use on this term */
+  int bRev;          /* True for DESCENDING sort order */
+#endif /* local variables moved into u.aj */
+
+  u.aj.n = pOp->p3;
+  u.aj.pKeyInfo = pOp->p4.pKeyInfo;
+  assert( u.aj.n>0 );
+  assert( u.aj.pKeyInfo!=0 );
+  u.aj.p1 = pOp->p1;
+  u.aj.p2 = pOp->p2;
+#if SQLITE_DEBUG
+  if( aPermute ){
+    int k, mx = 0;
+    for(k=0; k<u.aj.n; k++) if( aPermute[k]>mx ) mx = aPermute[k];
+    assert( u.aj.p1>0 && u.aj.p1+mx<=p->nMem+1 );
+    assert( u.aj.p2>0 && u.aj.p2+mx<=p->nMem+1 );
+  }else{
+    assert( u.aj.p1>0 && u.aj.p1+u.aj.n<=p->nMem+1 );
+    assert( u.aj.p2>0 && u.aj.p2+u.aj.n<=p->nMem+1 );
+  }
+#endif /* SQLITE_DEBUG */
+  for(u.aj.i=0; u.aj.i<u.aj.n; u.aj.i++){
+    u.aj.idx = aPermute ? aPermute[u.aj.i] : u.aj.i;
+    assert( memIsValid(&aMem[u.aj.p1+u.aj.idx]) );
+    assert( memIsValid(&aMem[u.aj.p2+u.aj.idx]) );
+    REGISTER_TRACE(u.aj.p1+u.aj.idx, &aMem[u.aj.p1+u.aj.idx]);
+    REGISTER_TRACE(u.aj.p2+u.aj.idx, &aMem[u.aj.p2+u.aj.idx]);
+    assert( u.aj.i<u.aj.pKeyInfo->nField );
+    u.aj.pColl = u.aj.pKeyInfo->aColl[u.aj.i];
+    u.aj.bRev = u.aj.pKeyInfo->aSortOrder[u.aj.i];
+    iCompare = sqlite3MemCompare(&aMem[u.aj.p1+u.aj.idx], &aMem[u.aj.p2+u.aj.idx], u.aj.pColl);
+    if( iCompare ){
+      if( u.aj.bRev ) iCompare = -iCompare;
+      break;
+    }
+  }
+  aPermute = 0;
+  break;
+}
+
+/* Opcode: Jump P1 P2 P3 * *
+**
+** Jump to the instruction at address P1, P2, or P3 depending on whether
+** in the most recent OP_Compare instruction the P1 vector was less than
+** equal to, or greater than the P2 vector, respectively.
+*/
+case OP_Jump: {             /* jump */
+  if( iCompare<0 ){
+    pc = pOp->p1 - 1;
+  }else if( iCompare==0 ){
+    pc = pOp->p2 - 1;
+  }else{
+    pc = pOp->p3 - 1;
+  }
+  break;
+}
+
+/* Opcode: And P1 P2 P3 * *
+**
+** Take the logical AND of the values in registers P1 and P2 and
+** write the result into register P3.
+**
+** If either P1 or P2 is 0 (false) then the result is 0 even if
+** the other input is NULL.  A NULL and true or two NULLs give
+** a NULL output.
+*/
+/* Opcode: Or P1 P2 P3 * *
+**
+** Take the logical OR of the values in register P1 and P2 and
+** store the answer in register P3.
+**
+** If either P1 or P2 is nonzero (true) then the result is 1 (true)
+** even if the other input is NULL.  A NULL and false or two NULLs
+** give a NULL output.
+*/
+case OP_And:              /* same as TK_AND, in1, in2, out3 */
+case OP_Or: {             /* same as TK_OR, in1, in2, out3 */
+#if 0  /* local variables moved into u.ak */
+  int v1;    /* Left operand:  0==FALSE, 1==TRUE, 2==UNKNOWN or NULL */
+  int v2;    /* Right operand: 0==FALSE, 1==TRUE, 2==UNKNOWN or NULL */
+#endif /* local variables moved into u.ak */
+
+  pIn1 = &aMem[pOp->p1];
+  if( pIn1->flags & MEM_Null ){
+    u.ak.v1 = 2;
+  }else{
+    u.ak.v1 = sqlite3VdbeIntValue(pIn1)!=0;
+  }
+  pIn2 = &aMem[pOp->p2];
+  if( pIn2->flags & MEM_Null ){
+    u.ak.v2 = 2;
+  }else{
+    u.ak.v2 = sqlite3VdbeIntValue(pIn2)!=0;
+  }
+  if( pOp->opcode==OP_And ){
+    static const unsigned char and_logic[] = { 0, 0, 0, 0, 1, 2, 0, 2, 2 };
+    u.ak.v1 = and_logic[u.ak.v1*3+u.ak.v2];
+  }else{
+    static const unsigned char or_logic[] = { 0, 1, 2, 1, 1, 1, 2, 1, 2 };
+    u.ak.v1 = or_logic[u.ak.v1*3+u.ak.v2];
+  }
+  pOut = &aMem[pOp->p3];
+  if( u.ak.v1==2 ){
+    MemSetTypeFlag(pOut, MEM_Null);
+  }else{
+    pOut->u.i = u.ak.v1;
+    MemSetTypeFlag(pOut, MEM_Int);
+  }
+  break;
+}
+
+/* Opcode: Not P1 P2 * * *
+**
+** Interpret the value in register P1 as a boolean value.  Store the
+** boolean complement in register P2.  If the value in register P1 is 
+** NULL, then a NULL is stored in P2.
+*/
+case OP_Not: {                /* same as TK_NOT, in1, out2 */
+  pIn1 = &aMem[pOp->p1];
+  pOut = &aMem[pOp->p2];
+  if( pIn1->flags & MEM_Null ){
+    sqlite3VdbeMemSetNull(pOut);
+  }else{
+    sqlite3VdbeMemSetInt64(pOut, !sqlite3VdbeIntValue(pIn1));
+  }
+  break;
+}
+
+/* Opcode: BitNot P1 P2 * * *
+**
+** Interpret the content of register P1 as an integer.  Store the
+** ones-complement of the P1 value into register P2.  If P1 holds
+** a NULL then store a NULL in P2.
+*/
+case OP_BitNot: {             /* same as TK_BITNOT, in1, out2 */
+  pIn1 = &aMem[pOp->p1];
+  pOut = &aMem[pOp->p2];
+  if( pIn1->flags & MEM_Null ){
+    sqlite3VdbeMemSetNull(pOut);
+  }else{
+    sqlite3VdbeMemSetInt64(pOut, ~sqlite3VdbeIntValue(pIn1));
+  }
+  break;
+}
+
+/* Opcode: If P1 P2 P3 * *
+**
+** Jump to P2 if the value in register P1 is true.  The value is
+** is considered true if it is numeric and non-zero.  If the value
+** in P1 is NULL then take the jump if P3 is true.
+*/
+/* Opcode: IfNot P1 P2 P3 * *
+**
+** Jump to P2 if the value in register P1 is False.  The value is
+** is considered true if it has a numeric value of zero.  If the value
+** in P1 is NULL then take the jump if P3 is true.
+*/
+case OP_If:                 /* jump, in1 */
+case OP_IfNot: {            /* jump, in1 */
+#if 0  /* local variables moved into u.al */
+  int c;
+#endif /* local variables moved into u.al */
+  pIn1 = &aMem[pOp->p1];
+  if( pIn1->flags & MEM_Null ){
+    u.al.c = pOp->p3;
+  }else{
+#ifdef SQLITE_OMIT_FLOATING_POINT
+    u.al.c = sqlite3VdbeIntValue(pIn1)!=0;
+#else
+    u.al.c = sqlite3VdbeRealValue(pIn1)!=0.0;
+#endif
+    if( pOp->opcode==OP_IfNot ) u.al.c = !u.al.c;
+  }
+  if( u.al.c ){
+    pc = pOp->p2-1;
+  }
+  break;
+}
+
+/* Opcode: IsNull P1 P2 * * *
+**
+** Jump to P2 if the value in register P1 is NULL.
+*/
+case OP_IsNull: {            /* same as TK_ISNULL, jump, in1 */
+  pIn1 = &aMem[pOp->p1];
+  if( (pIn1->flags & MEM_Null)!=0 ){
+    pc = pOp->p2 - 1;
+  }
+  break;
+}
+
+/* Opcode: NotNull P1 P2 * * *
+**
+** Jump to P2 if the value in register P1 is not NULL.  
+*/
+case OP_NotNull: {            /* same as TK_NOTNULL, jump, in1 */
+  pIn1 = &aMem[pOp->p1];
+  if( (pIn1->flags & MEM_Null)==0 ){
+    pc = pOp->p2 - 1;
+  }
+  break;
+}
+
+/* Opcode: Column P1 P2 P3 P4 P5
+**
+** Interpret the data that cursor P1 points to as a structure built using
+** the MakeRecord instruction.  (See the MakeRecord opcode for additional
+** information about the format of the data.)  Extract the P2-th column
+** from this record.  If there are less that (P2+1) 
+** values in the record, extract a NULL.
+**
+** The value extracted is stored in register P3.
+**
+** If the column contains fewer than P2 fields, then extract a NULL.  Or,
+** if the P4 argument is a P4_MEM use the value of the P4 argument as
+** the result.
+**
+** If the OPFLAG_CLEARCACHE bit is set on P5 and P1 is a pseudo-table cursor,
+** then the cache of the cursor is reset prior to extracting the column.
+** The first OP_Column against a pseudo-table after the value of the content
+** register has changed should have this bit set.
+*/
+case OP_Column: {
+#if 0  /* local variables moved into u.am */
+  u32 payloadSize;   /* Number of bytes in the record */
+  i64 payloadSize64; /* Number of bytes in the record */
+  int p1;            /* P1 value of the opcode */
+  int p2;            /* column number to retrieve */
+  VdbeCursor *pC;    /* The VDBE cursor */
+  char *zRec;        /* Pointer to complete record-data */
+  BtCursor *pCrsr;   /* The BTree cursor */
+  u32 *aType;        /* aType[i] holds the numeric type of the i-th column */
+  u32 *aOffset;      /* aOffset[i] is offset to start of data for i-th column */
+  int nField;        /* number of fields in the record */
+  int len;           /* The length of the serialized data for the column */
+  int i;             /* Loop counter */
+  char *zData;       /* Part of the record being decoded */
+  Mem *pDest;        /* Where to write the extracted value */
+  Mem sMem;          /* For storing the record being decoded */
+  u8 *zIdx;          /* Index into header */
+  u8 *zEndHdr;       /* Pointer to first byte after the header */
+  u32 offset;        /* Offset into the data */
+  u32 szField;       /* Number of bytes in the content of a field */
+  int szHdr;         /* Size of the header size field at start of record */
+  int avail;         /* Number of bytes of available data */
+  Mem *pReg;         /* PseudoTable input register */
+#endif /* local variables moved into u.am */
+
+
+  u.am.p1 = pOp->p1;
+  u.am.p2 = pOp->p2;
+  u.am.pC = 0;
+  memset(&u.am.sMem, 0, sizeof(u.am.sMem));
+  assert( u.am.p1<p->nCursor );
+  assert( pOp->p3>0 && pOp->p3<=p->nMem );
+  u.am.pDest = &aMem[pOp->p3];
+  memAboutToChange(p, u.am.pDest);
+  MemSetTypeFlag(u.am.pDest, MEM_Null);
+  u.am.zRec = 0;
+
+  /* This block sets the variable u.am.payloadSize to be the total number of
+  ** bytes in the record.
+  **
+  ** u.am.zRec is set to be the complete text of the record if it is available.
+  ** The complete record text is always available for pseudo-tables
+  ** If the record is stored in a cursor, the complete record text
+  ** might be available in the  u.am.pC->aRow cache.  Or it might not be.
+  ** If the data is unavailable,  u.am.zRec is set to NULL.
+  **
+  ** We also compute the number of columns in the record.  For cursors,
+  ** the number of columns is stored in the VdbeCursor.nField element.
+  */
+  u.am.pC = p->apCsr[u.am.p1];
+  assert( u.am.pC!=0 );
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  assert( u.am.pC->pVtabCursor==0 );
+#endif
+  u.am.pCrsr = u.am.pC->pCursor;
+  if( u.am.pCrsr!=0 ){
+    /* The record is stored in a B-Tree */
+    rc = sqlite3VdbeCursorMoveto(u.am.pC);
+    if( rc ) goto abort_due_to_error;
+    if( u.am.pC->nullRow ){
+      u.am.payloadSize = 0;
+    }else if( u.am.pC->cacheStatus==p->cacheCtr ){
+      u.am.payloadSize = u.am.pC->payloadSize;
+      u.am.zRec = (char*)u.am.pC->aRow;
+    }else if( u.am.pC->isIndex ){
+      assert( sqlite3BtreeCursorIsValid(u.am.pCrsr) );
+      rc = sqlite3BtreeKeySize(u.am.pCrsr, &u.am.payloadSize64);
+      assert( rc==SQLITE_OK );   /* True because of CursorMoveto() call above */
+      /* sqlite3BtreeParseCellPtr() uses getVarint32() to extract the
+      ** payload size, so it is impossible for u.am.payloadSize64 to be
+      ** larger than 32 bits. */
+      assert( (u.am.payloadSize64 & SQLITE_MAX_U32)==(u64)u.am.payloadSize64 );
+      u.am.payloadSize = (u32)u.am.payloadSize64;
+    }else{
+      assert( sqlite3BtreeCursorIsValid(u.am.pCrsr) );
+      rc = sqlite3BtreeDataSize(u.am.pCrsr, &u.am.payloadSize);
+      assert( rc==SQLITE_OK );   /* DataSize() cannot fail */
+    }
+  }else if( u.am.pC->pseudoTableReg>0 ){
+    u.am.pReg = &aMem[u.am.pC->pseudoTableReg];
+    assert( u.am.pReg->flags & MEM_Blob );
+    assert( memIsValid(u.am.pReg) );
+    u.am.payloadSize = u.am.pReg->n;
+    u.am.zRec = u.am.pReg->z;
+    u.am.pC->cacheStatus = (pOp->p5&OPFLAG_CLEARCACHE) ? CACHE_STALE : p->cacheCtr;
+    assert( u.am.payloadSize==0 || u.am.zRec!=0 );
+  }else{
+    /* Consider the row to be NULL */
+    u.am.payloadSize = 0;
+  }
+
+  /* If u.am.payloadSize is 0, then just store a NULL */
+  if( u.am.payloadSize==0 ){
+    assert( u.am.pDest->flags&MEM_Null );
+    goto op_column_out;
+  }
+  assert( db->aLimit[SQLITE_LIMIT_LENGTH]>=0 );
+  if( u.am.payloadSize > (u32)db->aLimit[SQLITE_LIMIT_LENGTH] ){
+    goto too_big;
+  }
+
+  u.am.nField = u.am.pC->nField;
+  assert( u.am.p2<u.am.nField );
+
+  /* Read and parse the table header.  Store the results of the parse
+  ** into the record header cache fields of the cursor.
+  */
+  u.am.aType = u.am.pC->aType;
+  if( u.am.pC->cacheStatus==p->cacheCtr ){
+    u.am.aOffset = u.am.pC->aOffset;
+  }else{
+    assert(u.am.aType);
+    u.am.avail = 0;
+    u.am.pC->aOffset = u.am.aOffset = &u.am.aType[u.am.nField];
+    u.am.pC->payloadSize = u.am.payloadSize;
+    u.am.pC->cacheStatus = p->cacheCtr;
+
+    /* Figure out how many bytes are in the header */
+    if( u.am.zRec ){
+      u.am.zData = u.am.zRec;
+    }else{
+      if( u.am.pC->isIndex ){
+        u.am.zData = (char*)sqlite3BtreeKeyFetch(u.am.pCrsr, &u.am.avail);
+      }else{
+        u.am.zData = (char*)sqlite3BtreeDataFetch(u.am.pCrsr, &u.am.avail);
+      }
+      /* If KeyFetch()/DataFetch() managed to get the entire payload,
+      ** save the payload in the u.am.pC->aRow cache.  That will save us from
+      ** having to make additional calls to fetch the content portion of
+      ** the record.
+      */
+      assert( u.am.avail>=0 );
+      if( u.am.payloadSize <= (u32)u.am.avail ){
+        u.am.zRec = u.am.zData;
+        u.am.pC->aRow = (u8*)u.am.zData;
+      }else{
+        u.am.pC->aRow = 0;
+      }
+    }
+    /* The following assert is true in all cases accept when
+    ** the database file has been corrupted externally.
+    **    assert( u.am.zRec!=0 || u.am.avail>=u.am.payloadSize || u.am.avail>=9 ); */
+    u.am.szHdr = getVarint32((u8*)u.am.zData, u.am.offset);
+
+    /* Make sure a corrupt database has not given us an oversize header.
+    ** Do this now to avoid an oversize memory allocation.
+    **
+    ** Type entries can be between 1 and 5 bytes each.  But 4 and 5 byte
+    ** types use so much data space that there can only be 4096 and 32 of
+    ** them, respectively.  So the maximum header length results from a
+    ** 3-byte type for each of the maximum of 32768 columns plus three
+    ** extra bytes for the header length itself.  32768*3 + 3 = 98307.
+    */
+    if( u.am.offset > 98307 ){
+      rc = SQLITE_CORRUPT_BKPT;
+      goto op_column_out;
+    }
+
+    /* Compute in u.am.len the number of bytes of data we need to read in order
+    ** to get u.am.nField type values.  u.am.offset is an upper bound on this.  But
+    ** u.am.nField might be significantly less than the true number of columns
+    ** in the table, and in that case, 5*u.am.nField+3 might be smaller than u.am.offset.
+    ** We want to minimize u.am.len in order to limit the size of the memory
+    ** allocation, especially if a corrupt database file has caused u.am.offset
+    ** to be oversized. Offset is limited to 98307 above.  But 98307 might
+    ** still exceed Robson memory allocation limits on some configurations.
+    ** On systems that cannot tolerate large memory allocations, u.am.nField*5+3
+    ** will likely be much smaller since u.am.nField will likely be less than
+    ** 20 or so.  This insures that Robson memory allocation limits are
+    ** not exceeded even for corrupt database files.
+    */
+    u.am.len = u.am.nField*5 + 3;
+    if( u.am.len > (int)u.am.offset ) u.am.len = (int)u.am.offset;
+
+    /* The KeyFetch() or DataFetch() above are fast and will get the entire
+    ** record header in most cases.  But they will fail to get the complete
+    ** record header if the record header does not fit on a single page
+    ** in the B-Tree.  When that happens, use sqlite3VdbeMemFromBtree() to
+    ** acquire the complete header text.
+    */
+    if( !u.am.zRec && u.am.avail<u.am.len ){
+      u.am.sMem.flags = 0;
+      u.am.sMem.db = 0;
+      rc = sqlite3VdbeMemFromBtree(u.am.pCrsr, 0, u.am.len, u.am.pC->isIndex, &u.am.sMem);
+      if( rc!=SQLITE_OK ){
+        goto op_column_out;
+      }
+      u.am.zData = u.am.sMem.z;
+    }
+    u.am.zEndHdr = (u8 *)&u.am.zData[u.am.len];
+    u.am.zIdx = (u8 *)&u.am.zData[u.am.szHdr];
+
+    /* Scan the header and use it to fill in the u.am.aType[] and u.am.aOffset[]
+    ** arrays.  u.am.aType[u.am.i] will contain the type integer for the u.am.i-th
+    ** column and u.am.aOffset[u.am.i] will contain the u.am.offset from the beginning
+    ** of the record to the start of the data for the u.am.i-th column
+    */
+    for(u.am.i=0; u.am.i<u.am.nField; u.am.i++){
+      if( u.am.zIdx<u.am.zEndHdr ){
+        u.am.aOffset[u.am.i] = u.am.offset;
+        u.am.zIdx += getVarint32(u.am.zIdx, u.am.aType[u.am.i]);
+        u.am.szField = sqlite3VdbeSerialTypeLen(u.am.aType[u.am.i]);
+        u.am.offset += u.am.szField;
+        if( u.am.offset<u.am.szField ){  /* True if u.am.offset overflows */
+          u.am.zIdx = &u.am.zEndHdr[1];  /* Forces SQLITE_CORRUPT return below */
+          break;
+        }
+      }else{
+        /* If u.am.i is less that u.am.nField, then there are less fields in this
+        ** record than SetNumColumns indicated there are columns in the
+        ** table. Set the u.am.offset for any extra columns not present in
+        ** the record to 0. This tells code below to store a NULL
+        ** instead of deserializing a value from the record.
+        */
+        u.am.aOffset[u.am.i] = 0;
+      }
+    }
+    sqlite3VdbeMemRelease(&u.am.sMem);
+    u.am.sMem.flags = MEM_Null;
+
+    /* If we have read more header data than was contained in the header,
+    ** or if the end of the last field appears to be past the end of the
+    ** record, or if the end of the last field appears to be before the end
+    ** of the record (when all fields present), then we must be dealing
+    ** with a corrupt database.
+    */
+    if( (u.am.zIdx > u.am.zEndHdr) || (u.am.offset > u.am.payloadSize)
+         || (u.am.zIdx==u.am.zEndHdr && u.am.offset!=u.am.payloadSize) ){
+      rc = SQLITE_CORRUPT_BKPT;
+      goto op_column_out;
+    }
+  }
+
+  /* Get the column information. If u.am.aOffset[u.am.p2] is non-zero, then
+  ** deserialize the value from the record. If u.am.aOffset[u.am.p2] is zero,
+  ** then there are not enough fields in the record to satisfy the
+  ** request.  In this case, set the value NULL or to P4 if P4 is
+  ** a pointer to a Mem object.
+  */
+  if( u.am.aOffset[u.am.p2] ){
+    assert( rc==SQLITE_OK );
+    if( u.am.zRec ){
+      sqlite3VdbeMemReleaseExternal(u.am.pDest);
+      sqlite3VdbeSerialGet((u8 *)&u.am.zRec[u.am.aOffset[u.am.p2]], u.am.aType[u.am.p2], u.am.pDest);
+    }else{
+      u.am.len = sqlite3VdbeSerialTypeLen(u.am.aType[u.am.p2]);
+      sqlite3VdbeMemMove(&u.am.sMem, u.am.pDest);
+      rc = sqlite3VdbeMemFromBtree(u.am.pCrsr, u.am.aOffset[u.am.p2], u.am.len, u.am.pC->isIndex, &u.am.sMem);
+      if( rc!=SQLITE_OK ){
+        goto op_column_out;
+      }
+      u.am.zData = u.am.sMem.z;
+      sqlite3VdbeSerialGet((u8*)u.am.zData, u.am.aType[u.am.p2], u.am.pDest);
+    }
+    u.am.pDest->enc = encoding;
+  }else{
+    if( pOp->p4type==P4_MEM ){
+      sqlite3VdbeMemShallowCopy(u.am.pDest, pOp->p4.pMem, MEM_Static);
+    }else{
+      assert( u.am.pDest->flags&MEM_Null );
+    }
+  }
+
+  /* If we dynamically allocated space to hold the data (in the
+  ** sqlite3VdbeMemFromBtree() call above) then transfer control of that
+  ** dynamically allocated space over to the u.am.pDest structure.
+  ** This prevents a memory copy.
+  */
+  if( u.am.sMem.zMalloc ){
+    assert( u.am.sMem.z==u.am.sMem.zMalloc );
+    assert( !(u.am.pDest->flags & MEM_Dyn) );
+    assert( !(u.am.pDest->flags & (MEM_Blob|MEM_Str)) || u.am.pDest->z==u.am.sMem.z );
+    u.am.pDest->flags &= ~(MEM_Ephem|MEM_Static);
+    u.am.pDest->flags |= MEM_Term;
+    u.am.pDest->z = u.am.sMem.z;
+    u.am.pDest->zMalloc = u.am.sMem.zMalloc;
+  }
+
+  rc = sqlite3VdbeMemMakeWriteable(u.am.pDest);
+
+op_column_out:
+  UPDATE_MAX_BLOBSIZE(u.am.pDest);
+  REGISTER_TRACE(pOp->p3, u.am.pDest);
+  break;
+}
+
+/* Opcode: Affinity P1 P2 * P4 *
+**
+** Apply affinities to a range of P2 registers starting with P1.
+**
+** P4 is a string that is P2 characters long. The nth character of the
+** string indicates the column affinity that should be used for the nth
+** memory cell in the range.
+*/
+case OP_Affinity: {
+#if 0  /* local variables moved into u.an */
+  const char *zAffinity;   /* The affinity to be applied */
+  char cAff;               /* A single character of affinity */
+#endif /* local variables moved into u.an */
+
+  u.an.zAffinity = pOp->p4.z;
+  assert( u.an.zAffinity!=0 );
+  assert( u.an.zAffinity[pOp->p2]==0 );
+  pIn1 = &aMem[pOp->p1];
+  while( (u.an.cAff = *(u.an.zAffinity++))!=0 ){
+    assert( pIn1 <= &p->aMem[p->nMem] );
+    assert( memIsValid(pIn1) );
+    ExpandBlob(pIn1);
+    applyAffinity(pIn1, u.an.cAff, encoding);
+    pIn1++;
+  }
+  break;
+}
+
+/* Opcode: MakeRecord P1 P2 P3 P4 *
+**
+** Convert P2 registers beginning with P1 into the [record format]
+** use as a data record in a database table or as a key
+** in an index.  The OP_Column opcode can decode the record later.
+**
+** P4 may be a string that is P2 characters long.  The nth character of the
+** string indicates the column affinity that should be used for the nth
+** field of the index key.
+**
+** The mapping from character to affinity is given by the SQLITE_AFF_
+** macros defined in sqliteInt.h.
+**
+** If P4 is NULL then all index fields have the affinity NONE.
+*/
+case OP_MakeRecord: {
+#if 0  /* local variables moved into u.ao */
+  u8 *zNewRecord;        /* A buffer to hold the data for the new record */
+  Mem *pRec;             /* The new record */
+  u64 nData;             /* Number of bytes of data space */
+  int nHdr;              /* Number of bytes of header space */
+  i64 nByte;             /* Data space required for this record */
+  int nZero;             /* Number of zero bytes at the end of the record */
+  int nVarint;           /* Number of bytes in a varint */
+  u32 serial_type;       /* Type field */
+  Mem *pData0;           /* First field to be combined into the record */
+  Mem *pLast;            /* Last field of the record */
+  int nField;            /* Number of fields in the record */
+  char *zAffinity;       /* The affinity string for the record */
+  int file_format;       /* File format to use for encoding */
+  int i;                 /* Space used in zNewRecord[] */
+  int len;               /* Length of a field */
+#endif /* local variables moved into u.ao */
+
+  /* Assuming the record contains N fields, the record format looks
+  ** like this:
+  **
+  ** ------------------------------------------------------------------------
+  ** | hdr-size | type 0 | type 1 | ... | type N-1 | data0 | ... | data N-1 |
+  ** ------------------------------------------------------------------------
+  **
+  ** Data(0) is taken from register P1.  Data(1) comes from register P1+1
+  ** and so froth.
+  **
+  ** Each type field is a varint representing the serial type of the
+  ** corresponding data element (see sqlite3VdbeSerialType()). The
+  ** hdr-size field is also a varint which is the offset from the beginning
+  ** of the record to data0.
+  */
+  u.ao.nData = 0;         /* Number of bytes of data space */
+  u.ao.nHdr = 0;          /* Number of bytes of header space */
+  u.ao.nZero = 0;         /* Number of zero bytes at the end of the record */
+  u.ao.nField = pOp->p1;
+  u.ao.zAffinity = pOp->p4.z;
+  assert( u.ao.nField>0 && pOp->p2>0 && pOp->p2+u.ao.nField<=p->nMem+1 );
+  u.ao.pData0 = &aMem[u.ao.nField];
+  u.ao.nField = pOp->p2;
+  u.ao.pLast = &u.ao.pData0[u.ao.nField-1];
+  u.ao.file_format = p->minWriteFileFormat;
+
+  /* Identify the output register */
+  assert( pOp->p3<pOp->p1 || pOp->p3>=pOp->p1+pOp->p2 );
+  pOut = &aMem[pOp->p3];
+  memAboutToChange(p, pOut);
+
+  /* Loop through the elements that will make up the record to figure
+  ** out how much space is required for the new record.
+  */
+  for(u.ao.pRec=u.ao.pData0; u.ao.pRec<=u.ao.pLast; u.ao.pRec++){
+    assert( memIsValid(u.ao.pRec) );
+    if( u.ao.zAffinity ){
+      applyAffinity(u.ao.pRec, u.ao.zAffinity[u.ao.pRec-u.ao.pData0], encoding);
+    }
+    if( u.ao.pRec->flags&MEM_Zero && u.ao.pRec->n>0 ){
+      sqlite3VdbeMemExpandBlob(u.ao.pRec);
+    }
+    u.ao.serial_type = sqlite3VdbeSerialType(u.ao.pRec, u.ao.file_format);
+    u.ao.len = sqlite3VdbeSerialTypeLen(u.ao.serial_type);
+    u.ao.nData += u.ao.len;
+    u.ao.nHdr += sqlite3VarintLen(u.ao.serial_type);
+    if( u.ao.pRec->flags & MEM_Zero ){
+      /* Only pure zero-filled BLOBs can be input to this Opcode.
+      ** We do not allow blobs with a prefix and a zero-filled tail. */
+      u.ao.nZero += u.ao.pRec->u.nZero;
+    }else if( u.ao.len ){
+      u.ao.nZero = 0;
+    }
+  }
+
+  /* Add the initial header varint and total the size */
+  u.ao.nHdr += u.ao.nVarint = sqlite3VarintLen(u.ao.nHdr);
+  if( u.ao.nVarint<sqlite3VarintLen(u.ao.nHdr) ){
+    u.ao.nHdr++;
+  }
+  u.ao.nByte = u.ao.nHdr+u.ao.nData-u.ao.nZero;
+  if( u.ao.nByte>db->aLimit[SQLITE_LIMIT_LENGTH] ){
+    goto too_big;
+  }
+
+  /* Make sure the output register has a buffer large enough to store
+  ** the new record. The output register (pOp->p3) is not allowed to
+  ** be one of the input registers (because the following call to
+  ** sqlite3VdbeMemGrow() could clobber the value before it is used).
+  */
+  if( sqlite3VdbeMemGrow(pOut, (int)u.ao.nByte, 0) ){
+    goto no_mem;
+  }
+  u.ao.zNewRecord = (u8 *)pOut->z;
+
+  /* Write the record */
+  u.ao.i = putVarint32(u.ao.zNewRecord, u.ao.nHdr);
+  for(u.ao.pRec=u.ao.pData0; u.ao.pRec<=u.ao.pLast; u.ao.pRec++){
+    u.ao.serial_type = sqlite3VdbeSerialType(u.ao.pRec, u.ao.file_format);
+    u.ao.i += putVarint32(&u.ao.zNewRecord[u.ao.i], u.ao.serial_type);      /* serial type */
+  }
+  for(u.ao.pRec=u.ao.pData0; u.ao.pRec<=u.ao.pLast; u.ao.pRec++){  /* serial data */
+    u.ao.i += sqlite3VdbeSerialPut(&u.ao.zNewRecord[u.ao.i], (int)(u.ao.nByte-u.ao.i), u.ao.pRec,u.ao.file_format);
+  }
+  assert( u.ao.i==u.ao.nByte );
+
+  assert( pOp->p3>0 && pOp->p3<=p->nMem );
+  pOut->n = (int)u.ao.nByte;
+  pOut->flags = MEM_Blob | MEM_Dyn;
+  pOut->xDel = 0;
+  if( u.ao.nZero ){
+    pOut->u.nZero = u.ao.nZero;
+    pOut->flags |= MEM_Zero;
+  }
+  pOut->enc = SQLITE_UTF8;  /* In case the blob is ever converted to text */
+  REGISTER_TRACE(pOp->p3, pOut);
+  UPDATE_MAX_BLOBSIZE(pOut);
+  break;
+}
+
+/* Opcode: Count P1 P2 * * *
+**
+** Store the number of entries (an integer value) in the table or index 
+** opened by cursor P1 in register P2
+*/
+#ifndef SQLITE_OMIT_BTREECOUNT
+case OP_Count: {         /* out2-prerelease */
+#if 0  /* local variables moved into u.ap */
+  i64 nEntry;
+  BtCursor *pCrsr;
+#endif /* local variables moved into u.ap */
+
+  u.ap.pCrsr = p->apCsr[pOp->p1]->pCursor;
+  if( u.ap.pCrsr ){
+    rc = sqlite3BtreeCount(u.ap.pCrsr, &u.ap.nEntry);
+  }else{
+    u.ap.nEntry = 0;
+  }
+  pOut->u.i = u.ap.nEntry;
+  break;
+}
+#endif
+
+/* Opcode: Savepoint P1 * * P4 *
+**
+** Open, release or rollback the savepoint named by parameter P4, depending
+** on the value of P1. To open a new savepoint, P1==0. To release (commit) an
+** existing savepoint, P1==1, or to rollback an existing savepoint P1==2.
+*/
+case OP_Savepoint: {
+#if 0  /* local variables moved into u.aq */
+  int p1;                         /* Value of P1 operand */
+  char *zName;                    /* Name of savepoint */
+  int nName;
+  Savepoint *pNew;
+  Savepoint *pSavepoint;
+  Savepoint *pTmp;
+  int iSavepoint;
+  int ii;
+#endif /* local variables moved into u.aq */
+
+  u.aq.p1 = pOp->p1;
+  u.aq.zName = pOp->p4.z;
+
+  /* Assert that the u.aq.p1 parameter is valid. Also that if there is no open
+  ** transaction, then there cannot be any savepoints.
+  */
+  assert( db->pSavepoint==0 || db->autoCommit==0 );
+  assert( u.aq.p1==SAVEPOINT_BEGIN||u.aq.p1==SAVEPOINT_RELEASE||u.aq.p1==SAVEPOINT_ROLLBACK );
+  assert( db->pSavepoint || db->isTransactionSavepoint==0 );
+  assert( checkSavepointCount(db) );
+
+  if( u.aq.p1==SAVEPOINT_BEGIN ){
+    if( db->writeVdbeCnt>0 ){
+      /* A new savepoint cannot be created if there are active write
+      ** statements (i.e. open read/write incremental blob handles).
+      */
+      sqlite3SetString(&p->zErrMsg, db, "cannot open savepoint - "
+        "SQL statements in progress");
+      rc = SQLITE_BUSY;
+    }else{
+      u.aq.nName = sqlite3Strlen30(u.aq.zName);
+
+      /* Create a new savepoint structure. */
+      u.aq.pNew = sqlite3DbMallocRaw(db, sizeof(Savepoint)+u.aq.nName+1);
+      if( u.aq.pNew ){
+        u.aq.pNew->zName = (char *)&u.aq.pNew[1];
+        memcpy(u.aq.pNew->zName, u.aq.zName, u.aq.nName+1);
+
+        /* If there is no open transaction, then mark this as a special
+        ** "transaction savepoint". */
+        if( db->autoCommit ){
+          db->autoCommit = 0;
+          db->isTransactionSavepoint = 1;
+        }else{
+          db->nSavepoint++;
+        }
+
+        /* Link the new savepoint into the database handle's list. */
+        u.aq.pNew->pNext = db->pSavepoint;
+        db->pSavepoint = u.aq.pNew;
+        u.aq.pNew->nDeferredCons = db->nDeferredCons;
+      }
+    }
+  }else{
+    u.aq.iSavepoint = 0;
+
+    /* Find the named savepoint. If there is no such savepoint, then an
+    ** an error is returned to the user.  */
+    for(
+      u.aq.pSavepoint = db->pSavepoint;
+      u.aq.pSavepoint && sqlite3StrICmp(u.aq.pSavepoint->zName, u.aq.zName);
+      u.aq.pSavepoint = u.aq.pSavepoint->pNext
+    ){
+      u.aq.iSavepoint++;
+    }
+    if( !u.aq.pSavepoint ){
+      sqlite3SetString(&p->zErrMsg, db, "no such savepoint: %s", u.aq.zName);
+      rc = SQLITE_ERROR;
+    }else if(
+        db->writeVdbeCnt>0 || (u.aq.p1==SAVEPOINT_ROLLBACK && db->activeVdbeCnt>1)
+    ){
+      /* It is not possible to release (commit) a savepoint if there are
+      ** active write statements. It is not possible to rollback a savepoint
+      ** if there are any active statements at all.
+      */
+      sqlite3SetString(&p->zErrMsg, db,
+        "cannot %s savepoint - SQL statements in progress",
+        (u.aq.p1==SAVEPOINT_ROLLBACK ? "rollback": "release")
+      );
+      rc = SQLITE_BUSY;
+    }else{
+
+      /* Determine whether or not this is a transaction savepoint. If so,
+      ** and this is a RELEASE command, then the current transaction
+      ** is committed.
+      */
+      int isTransaction = u.aq.pSavepoint->pNext==0 && db->isTransactionSavepoint;
+      if( isTransaction && u.aq.p1==SAVEPOINT_RELEASE ){
+        if( (rc = sqlite3VdbeCheckFk(p, 1))!=SQLITE_OK ){
+          goto vdbe_return;
+        }
+        db->autoCommit = 1;
+        if( sqlite3VdbeHalt(p)==SQLITE_BUSY ){
+          p->pc = pc;
+          db->autoCommit = 0;
+          p->rc = rc = SQLITE_BUSY;
+          goto vdbe_return;
+        }
+        db->isTransactionSavepoint = 0;
+        rc = p->rc;
+      }else{
+        u.aq.iSavepoint = db->nSavepoint - u.aq.iSavepoint - 1;
+        for(u.aq.ii=0; u.aq.ii<db->nDb; u.aq.ii++){
+          rc = sqlite3BtreeSavepoint(db->aDb[u.aq.ii].pBt, u.aq.p1, u.aq.iSavepoint);
+          if( rc!=SQLITE_OK ){
+            goto abort_due_to_error;
+          }
+        }
+        if( u.aq.p1==SAVEPOINT_ROLLBACK && (db->flags&SQLITE_InternChanges)!=0 ){
+          sqlite3ExpirePreparedStatements(db);
+          sqlite3ResetInternalSchema(db, -1);
+          db->flags = (db->flags | SQLITE_InternChanges);
+        }
+      }
+
+      /* Regardless of whether this is a RELEASE or ROLLBACK, destroy all
+      ** savepoints nested inside of the savepoint being operated on. */
+      while( db->pSavepoint!=u.aq.pSavepoint ){
+        u.aq.pTmp = db->pSavepoint;
+        db->pSavepoint = u.aq.pTmp->pNext;
+        sqlite3DbFree(db, u.aq.pTmp);
+        db->nSavepoint--;
+      }
+
+      /* If it is a RELEASE, then destroy the savepoint being operated on
+      ** too. If it is a ROLLBACK TO, then set the number of deferred
+      ** constraint violations present in the database to the value stored
+      ** when the savepoint was created.  */
+      if( u.aq.p1==SAVEPOINT_RELEASE ){
+        assert( u.aq.pSavepoint==db->pSavepoint );
+        db->pSavepoint = u.aq.pSavepoint->pNext;
+        sqlite3DbFree(db, u.aq.pSavepoint);
+        if( !isTransaction ){
+          db->nSavepoint--;
+        }
+      }else{
+        db->nDeferredCons = u.aq.pSavepoint->nDeferredCons;
+      }
+    }
+  }
+
+  break;
+}
+
+/* Opcode: AutoCommit P1 P2 * * *
+**
+** Set the database auto-commit flag to P1 (1 or 0). If P2 is true, roll
+** back any currently active btree transactions. If there are any active
+** VMs (apart from this one), then a ROLLBACK fails.  A COMMIT fails if
+** there are active writing VMs or active VMs that use shared cache.
+**
+** This instruction causes the VM to halt.
+*/
+case OP_AutoCommit: {
+#if 0  /* local variables moved into u.ar */
+  int desiredAutoCommit;
+  int iRollback;
+  int turnOnAC;
+#endif /* local variables moved into u.ar */
+
+  u.ar.desiredAutoCommit = pOp->p1;
+  u.ar.iRollback = pOp->p2;
+  u.ar.turnOnAC = u.ar.desiredAutoCommit && !db->autoCommit;
+  assert( u.ar.desiredAutoCommit==1 || u.ar.desiredAutoCommit==0 );
+  assert( u.ar.desiredAutoCommit==1 || u.ar.iRollback==0 );
+  assert( db->activeVdbeCnt>0 );  /* At least this one VM is active */
+
+  if( u.ar.turnOnAC && u.ar.iRollback && db->activeVdbeCnt>1 ){
+    /* If this instruction implements a ROLLBACK and other VMs are
+    ** still running, and a transaction is active, return an error indicating
+    ** that the other VMs must complete first.
+    */
+    sqlite3SetString(&p->zErrMsg, db, "cannot rollback transaction - "
+        "SQL statements in progress");
+    rc = SQLITE_BUSY;
+  }else if( u.ar.turnOnAC && !u.ar.iRollback && db->writeVdbeCnt>0 ){
+    /* If this instruction implements a COMMIT and other VMs are writing
+    ** return an error indicating that the other VMs must complete first.
+    */
+    sqlite3SetString(&p->zErrMsg, db, "cannot commit transaction - "
+        "SQL statements in progress");
+    rc = SQLITE_BUSY;
+  }else if( u.ar.desiredAutoCommit!=db->autoCommit ){
+    if( u.ar.iRollback ){
+      assert( u.ar.desiredAutoCommit==1 );
+      sqlite3RollbackAll(db);
+      db->autoCommit = 1;
+    }else if( (rc = sqlite3VdbeCheckFk(p, 1))!=SQLITE_OK ){
+      goto vdbe_return;
+    }else{
+      db->autoCommit = (u8)u.ar.desiredAutoCommit;
+      if( sqlite3VdbeHalt(p)==SQLITE_BUSY ){
+        p->pc = pc;
+        db->autoCommit = (u8)(1-u.ar.desiredAutoCommit);
+        p->rc = rc = SQLITE_BUSY;
+        goto vdbe_return;
+      }
+    }
+    assert( db->nStatement==0 );
+    sqlite3CloseSavepoints(db);
+    if( p->rc==SQLITE_OK ){
+      rc = SQLITE_DONE;
+    }else{
+      rc = SQLITE_ERROR;
+    }
+    goto vdbe_return;
+  }else{
+    sqlite3SetString(&p->zErrMsg, db,
+        (!u.ar.desiredAutoCommit)?"cannot start a transaction within a transaction":(
+        (u.ar.iRollback)?"cannot rollback - no transaction is active":
+                   "cannot commit - no transaction is active"));
+
+    rc = SQLITE_ERROR;
+  }
+  break;
+}
+
+/* Opcode: Transaction P1 P2 * * *
+**
+** Begin a transaction.  The transaction ends when a Commit or Rollback
+** opcode is encountered.  Depending on the ON CONFLICT setting, the
+** transaction might also be rolled back if an error is encountered.
+**
+** P1 is the index of the database file on which the transaction is
+** started.  Index 0 is the main database file and index 1 is the
+** file used for temporary tables.  Indices of 2 or more are used for
+** attached databases.
+**
+** If P2 is non-zero, then a write-transaction is started.  A RESERVED lock is
+** obtained on the database file when a write-transaction is started.  No
+** other process can start another write transaction while this transaction is
+** underway.  Starting a write transaction also creates a rollback journal. A
+** write transaction must be started before any changes can be made to the
+** database.  If P2 is 2 or greater then an EXCLUSIVE lock is also obtained
+** on the file.
+**
+** If a write-transaction is started and the Vdbe.usesStmtJournal flag is
+** true (this flag is set if the Vdbe may modify more than one row and may
+** throw an ABORT exception), a statement transaction may also be opened.
+** More specifically, a statement transaction is opened iff the database
+** connection is currently not in autocommit mode, or if there are other
+** active statements. A statement transaction allows the affects of this
+** VDBE to be rolled back after an error without having to roll back the
+** entire transaction. If no error is encountered, the statement transaction
+** will automatically commit when the VDBE halts.
+**
+** If P2 is zero, then a read-lock is obtained on the database file.
+*/
+case OP_Transaction: {
+#if 0  /* local variables moved into u.as */
+  Btree *pBt;
+#endif /* local variables moved into u.as */
+
+  assert( pOp->p1>=0 && pOp->p1<db->nDb );
+  assert( (p->btreeMask & (((yDbMask)1)<<pOp->p1))!=0 );
+  u.as.pBt = db->aDb[pOp->p1].pBt;
+
+  if( u.as.pBt ){
+    rc = sqlite3BtreeBeginTrans(u.as.pBt, pOp->p2);
+    if( rc==SQLITE_BUSY ){
+      p->pc = pc;
+      p->rc = rc = SQLITE_BUSY;
+      goto vdbe_return;
+    }
+    if( rc!=SQLITE_OK ){
+      goto abort_due_to_error;
+    }
+
+    if( pOp->p2 && p->usesStmtJournal
+     && (db->autoCommit==0 || db->activeVdbeCnt>1)
+    ){
+      assert( sqlite3BtreeIsInTrans(u.as.pBt) );
+      if( p->iStatement==0 ){
+        assert( db->nStatement>=0 && db->nSavepoint>=0 );
+        db->nStatement++;
+        p->iStatement = db->nSavepoint + db->nStatement;
+      }
+      rc = sqlite3BtreeBeginStmt(u.as.pBt, p->iStatement);
+
+      /* Store the current value of the database handles deferred constraint
+      ** counter. If the statement transaction needs to be rolled back,
+      ** the value of this counter needs to be restored too.  */
+      p->nStmtDefCons = db->nDeferredCons;
+    }
+  }
+  break;
+}
+
+/* Opcode: ReadCookie P1 P2 P3 * *
+**
+** Read cookie number P3 from database P1 and write it into register P2.
+** P3==1 is the schema version.  P3==2 is the database format.
+** P3==3 is the recommended pager cache size, and so forth.  P1==0 is
+** the main database file and P1==1 is the database file used to store
+** temporary tables.
+**
+** There must be a read-lock on the database (either a transaction
+** must be started or there must be an open cursor) before
+** executing this instruction.
+*/
+case OP_ReadCookie: {               /* out2-prerelease */
+#if 0  /* local variables moved into u.at */
+  int iMeta;
+  int iDb;
+  int iCookie;
+#endif /* local variables moved into u.at */
+
+  u.at.iDb = pOp->p1;
+  u.at.iCookie = pOp->p3;
+  assert( pOp->p3<SQLITE_N_BTREE_META );
+  assert( u.at.iDb>=0 && u.at.iDb<db->nDb );
+  assert( db->aDb[u.at.iDb].pBt!=0 );
+  assert( (p->btreeMask & (((yDbMask)1)<<u.at.iDb))!=0 );
+
+  sqlite3BtreeGetMeta(db->aDb[u.at.iDb].pBt, u.at.iCookie, (u32 *)&u.at.iMeta);
+  pOut->u.i = u.at.iMeta;
+  break;
+}
+
+/* Opcode: SetCookie P1 P2 P3 * *
+**
+** Write the content of register P3 (interpreted as an integer)
+** into cookie number P2 of database P1.  P2==1 is the schema version.  
+** P2==2 is the database format. P2==3 is the recommended pager cache 
+** size, and so forth.  P1==0 is the main database file and P1==1 is the 
+** database file used to store temporary tables.
+**
+** A transaction must be started before executing this opcode.
+*/
+case OP_SetCookie: {       /* in3 */
+#if 0  /* local variables moved into u.au */
+  Db *pDb;
+#endif /* local variables moved into u.au */
+  assert( pOp->p2<SQLITE_N_BTREE_META );
+  assert( pOp->p1>=0 && pOp->p1<db->nDb );
+  assert( (p->btreeMask & (((yDbMask)1)<<pOp->p1))!=0 );
+  u.au.pDb = &db->aDb[pOp->p1];
+  assert( u.au.pDb->pBt!=0 );
+  assert( sqlite3SchemaMutexHeld(db, pOp->p1, 0) );
+  pIn3 = &aMem[pOp->p3];
+  sqlite3VdbeMemIntegerify(pIn3);
+  /* See note about index shifting on OP_ReadCookie */
+  rc = sqlite3BtreeUpdateMeta(u.au.pDb->pBt, pOp->p2, (int)pIn3->u.i);
+  if( pOp->p2==BTREE_SCHEMA_VERSION ){
+    /* When the schema cookie changes, record the new cookie internally */
+    u.au.pDb->pSchema->schema_cookie = (int)pIn3->u.i;
+    db->flags |= SQLITE_InternChanges;
+  }else if( pOp->p2==BTREE_FILE_FORMAT ){
+    /* Record changes in the file format */
+    u.au.pDb->pSchema->file_format = (u8)pIn3->u.i;
+  }
+  if( pOp->p1==1 ){
+    /* Invalidate all prepared statements whenever the TEMP database
+    ** schema is changed.  Ticket #1644 */
+    sqlite3ExpirePreparedStatements(db);
+    p->expired = 0;
+  }
+  break;
+}
+
+/* Opcode: VerifyCookie P1 P2 P3 * *
+**
+** Check the value of global database parameter number 0 (the
+** schema version) and make sure it is equal to P2 and that the
+** generation counter on the local schema parse equals P3.
+**
+** P1 is the database number which is 0 for the main database file
+** and 1 for the file holding temporary tables and some higher number
+** for auxiliary databases.
+**
+** The cookie changes its value whenever the database schema changes.
+** This operation is used to detect when that the cookie has changed
+** and that the current process needs to reread the schema.
+**
+** Either a transaction needs to have been started or an OP_Open needs
+** to be executed (to establish a read lock) before this opcode is
+** invoked.
+*/
+case OP_VerifyCookie: {
+#if 0  /* local variables moved into u.av */
+  int iMeta;
+  int iGen;
+  Btree *pBt;
+#endif /* local variables moved into u.av */
+
+  assert( pOp->p1>=0 && pOp->p1<db->nDb );
+  assert( (p->btreeMask & (((yDbMask)1)<<pOp->p1))!=0 );
+  assert( sqlite3SchemaMutexHeld(db, pOp->p1, 0) );
+  u.av.pBt = db->aDb[pOp->p1].pBt;
+  if( u.av.pBt ){
+    sqlite3BtreeGetMeta(u.av.pBt, BTREE_SCHEMA_VERSION, (u32 *)&u.av.iMeta);
+    u.av.iGen = db->aDb[pOp->p1].pSchema->iGeneration;
+  }else{
+    u.av.iGen = u.av.iMeta = 0;
+  }
+  if( u.av.iMeta!=pOp->p2 || u.av.iGen!=pOp->p3 ){
+    sqlite3DbFree(db, p->zErrMsg);
+    p->zErrMsg = sqlite3DbStrDup(db, "database schema has changed");
+    /* If the schema-cookie from the database file matches the cookie
+    ** stored with the in-memory representation of the schema, do
+    ** not reload the schema from the database file.
+    **
+    ** If virtual-tables are in use, this is not just an optimization.
+    ** Often, v-tables store their data in other SQLite tables, which
+    ** are queried from within xNext() and other v-table methods using
+    ** prepared queries. If such a query is out-of-date, we do not want to
+    ** discard the database schema, as the user code implementing the
+    ** v-table would have to be ready for the sqlite3_vtab structure itself
+    ** to be invalidated whenever sqlite3_step() is called from within
+    ** a v-table method.
+    */
+    if( db->aDb[pOp->p1].pSchema->schema_cookie!=u.av.iMeta ){
+      sqlite3ResetInternalSchema(db, pOp->p1);
+    }
+
+    p->expired = 1;
+    rc = SQLITE_SCHEMA;
+  }
+  break;
+}
+
+/* Opcode: OpenRead P1 P2 P3 P4 P5
+**
+** Open a read-only cursor for the database table whose root page is
+** P2 in a database file.  The database file is determined by P3. 
+** P3==0 means the main database, P3==1 means the database used for 
+** temporary tables, and P3>1 means used the corresponding attached
+** database.  Give the new cursor an identifier of P1.  The P1
+** values need not be contiguous but all P1 values should be small integers.
+** It is an error for P1 to be negative.
+**
+** If P5!=0 then use the content of register P2 as the root page, not
+** the value of P2 itself.
+**
+** There will be a read lock on the database whenever there is an
+** open cursor.  If the database was unlocked prior to this instruction
+** then a read lock is acquired as part of this instruction.  A read
+** lock allows other processes to read the database but prohibits
+** any other process from modifying the database.  The read lock is
+** released when all cursors are closed.  If this instruction attempts
+** to get a read lock but fails, the script terminates with an
+** SQLITE_BUSY error code.
+**
+** The P4 value may be either an integer (P4_INT32) or a pointer to
+** a KeyInfo structure (P4_KEYINFO). If it is a pointer to a KeyInfo 
+** structure, then said structure defines the content and collating 
+** sequence of the index being opened. Otherwise, if P4 is an integer 
+** value, it is set to the number of columns in the table.
+**
+** See also OpenWrite.
+*/
+/* Opcode: OpenWrite P1 P2 P3 P4 P5
+**
+** Open a read/write cursor named P1 on the table or index whose root
+** page is P2.  Or if P5!=0 use the content of register P2 to find the
+** root page.
+**
+** The P4 value may be either an integer (P4_INT32) or a pointer to
+** a KeyInfo structure (P4_KEYINFO). If it is a pointer to a KeyInfo 
+** structure, then said structure defines the content and collating 
+** sequence of the index being opened. Otherwise, if P4 is an integer 
+** value, it is set to the number of columns in the table, or to the
+** largest index of any column of the table that is actually used.
+**
+** This instruction works just like OpenRead except that it opens the cursor
+** in read/write mode.  For a given table, there can be one or more read-only
+** cursors or a single read/write cursor but not both.
+**
+** See also OpenRead.
+*/
+case OP_OpenRead:
+case OP_OpenWrite: {
+#if 0  /* local variables moved into u.aw */
+  int nField;
+  KeyInfo *pKeyInfo;
+  int p2;
+  int iDb;
+  int wrFlag;
+  Btree *pX;
+  VdbeCursor *pCur;
+  Db *pDb;
+#endif /* local variables moved into u.aw */
+
+  if( p->expired ){
+    rc = SQLITE_ABORT;
+    break;
+  }
+
+  u.aw.nField = 0;
+  u.aw.pKeyInfo = 0;
+  u.aw.p2 = pOp->p2;
+  u.aw.iDb = pOp->p3;
+  assert( u.aw.iDb>=0 && u.aw.iDb<db->nDb );
+  assert( (p->btreeMask & (((yDbMask)1)<<u.aw.iDb))!=0 );
+  u.aw.pDb = &db->aDb[u.aw.iDb];
+  u.aw.pX = u.aw.pDb->pBt;
+  assert( u.aw.pX!=0 );
+  if( pOp->opcode==OP_OpenWrite ){
+    u.aw.wrFlag = 1;
+    assert( sqlite3SchemaMutexHeld(db, u.aw.iDb, 0) );
+    if( u.aw.pDb->pSchema->file_format < p->minWriteFileFormat ){
+      p->minWriteFileFormat = u.aw.pDb->pSchema->file_format;
+    }
+  }else{
+    u.aw.wrFlag = 0;
+  }
+  if( pOp->p5 ){
+    assert( u.aw.p2>0 );
+    assert( u.aw.p2<=p->nMem );
+    pIn2 = &aMem[u.aw.p2];
+    assert( memIsValid(pIn2) );
+    assert( (pIn2->flags & MEM_Int)!=0 );
+    sqlite3VdbeMemIntegerify(pIn2);
+    u.aw.p2 = (int)pIn2->u.i;
+    /* The u.aw.p2 value always comes from a prior OP_CreateTable opcode and
+    ** that opcode will always set the u.aw.p2 value to 2 or more or else fail.
+    ** If there were a failure, the prepared statement would have halted
+    ** before reaching this instruction. */
+    if( NEVER(u.aw.p2<2) ) {
+      rc = SQLITE_CORRUPT_BKPT;
+      goto abort_due_to_error;
+    }
+  }
+  if( pOp->p4type==P4_KEYINFO ){
+    u.aw.pKeyInfo = pOp->p4.pKeyInfo;
+    u.aw.pKeyInfo->enc = ENC(p->db);
+    u.aw.nField = u.aw.pKeyInfo->nField+1;
+  }else if( pOp->p4type==P4_INT32 ){
+    u.aw.nField = pOp->p4.i;
+  }
+  assert( pOp->p1>=0 );
+  u.aw.pCur = allocateCursor(p, pOp->p1, u.aw.nField, u.aw.iDb, 1);
+  if( u.aw.pCur==0 ) goto no_mem;
+  u.aw.pCur->nullRow = 1;
+  u.aw.pCur->isOrdered = 1;
+  rc = sqlite3BtreeCursor(u.aw.pX, u.aw.p2, u.aw.wrFlag, u.aw.pKeyInfo, u.aw.pCur->pCursor);
+  u.aw.pCur->pKeyInfo = u.aw.pKeyInfo;
+
+  /* Since it performs no memory allocation or IO, the only values that
+  ** sqlite3BtreeCursor() may return are SQLITE_EMPTY and SQLITE_OK.
+  ** SQLITE_EMPTY is only returned when attempting to open the table
+  ** rooted at page 1 of a zero-byte database.  */
+  assert( rc==SQLITE_EMPTY || rc==SQLITE_OK );
+  if( rc==SQLITE_EMPTY ){
+    u.aw.pCur->pCursor = 0;
+    rc = SQLITE_OK;
+  }
+
+  /* Set the VdbeCursor.isTable and isIndex variables. Previous versions of
+  ** SQLite used to check if the root-page flags were sane at this point
+  ** and report database corruption if they were not, but this check has
+  ** since moved into the btree layer.  */
+  u.aw.pCur->isTable = pOp->p4type!=P4_KEYINFO;
+  u.aw.pCur->isIndex = !u.aw.pCur->isTable;
+  break;
+}
+
+/* Opcode: OpenEphemeral P1 P2 * P4 *
+**
+** Open a new cursor P1 to a transient table.
+** The cursor is always opened read/write even if 
+** the main database is read-only.  The ephemeral
+** table is deleted automatically when the cursor is closed.
+**
+** P2 is the number of columns in the ephemeral table.
+** The cursor points to a BTree table if P4==0 and to a BTree index
+** if P4 is not 0.  If P4 is not NULL, it points to a KeyInfo structure
+** that defines the format of keys in the index.
+**
+** This opcode was once called OpenTemp.  But that created
+** confusion because the term "temp table", might refer either
+** to a TEMP table at the SQL level, or to a table opened by
+** this opcode.  Then this opcode was call OpenVirtual.  But
+** that created confusion with the whole virtual-table idea.
+*/
+/* Opcode: OpenAutoindex P1 P2 * P4 *
+**
+** This opcode works the same as OP_OpenEphemeral.  It has a
+** different name to distinguish its use.  Tables created using
+** by this opcode will be used for automatically created transient
+** indices in joins.
+*/
+case OP_OpenAutoindex: 
+case OP_OpenEphemeral: {
+#if 0  /* local variables moved into u.ax */
+  VdbeCursor *pCx;
+#endif /* local variables moved into u.ax */
+  static const int vfsFlags =
+      SQLITE_OPEN_READWRITE |
+      SQLITE_OPEN_CREATE |
+      SQLITE_OPEN_EXCLUSIVE |
+      SQLITE_OPEN_DELETEONCLOSE |
+      SQLITE_OPEN_TRANSIENT_DB;
+
+  assert( pOp->p1>=0 );
+  u.ax.pCx = allocateCursor(p, pOp->p1, pOp->p2, -1, 1);
+  if( u.ax.pCx==0 ) goto no_mem;
+  u.ax.pCx->nullRow = 1;
+  rc = sqlite3BtreeOpen(0, db, &u.ax.pCx->pBt,
+                        BTREE_OMIT_JOURNAL | BTREE_SINGLE | pOp->p5, vfsFlags);
+  if( rc==SQLITE_OK ){
+    rc = sqlite3BtreeBeginTrans(u.ax.pCx->pBt, 1);
+  }
+  if( rc==SQLITE_OK ){
+    /* If a transient index is required, create it by calling
+    ** sqlite3BtreeCreateTable() with the BTREE_BLOBKEY flag before
+    ** opening it. If a transient table is required, just use the
+    ** automatically created table with root-page 1 (an BLOB_INTKEY table).
+    */
+    if( pOp->p4.pKeyInfo ){
+      int pgno;
+      assert( pOp->p4type==P4_KEYINFO );
+      rc = sqlite3BtreeCreateTable(u.ax.pCx->pBt, &pgno, BTREE_BLOBKEY);
+      if( rc==SQLITE_OK ){
+        assert( pgno==MASTER_ROOT+1 );
+        rc = sqlite3BtreeCursor(u.ax.pCx->pBt, pgno, 1,
+                                (KeyInfo*)pOp->p4.z, u.ax.pCx->pCursor);
+        u.ax.pCx->pKeyInfo = pOp->p4.pKeyInfo;
+        u.ax.pCx->pKeyInfo->enc = ENC(p->db);
+      }
+      u.ax.pCx->isTable = 0;
+    }else{
+      rc = sqlite3BtreeCursor(u.ax.pCx->pBt, MASTER_ROOT, 1, 0, u.ax.pCx->pCursor);
+      u.ax.pCx->isTable = 1;
+    }
+  }
+  u.ax.pCx->isOrdered = (pOp->p5!=BTREE_UNORDERED);
+  u.ax.pCx->isIndex = !u.ax.pCx->isTable;
+  break;
+}
+
+/* Opcode: OpenPseudo P1 P2 P3 * *
+**
+** Open a new cursor that points to a fake table that contains a single
+** row of data.  The content of that one row in the content of memory
+** register P2.  In other words, cursor P1 becomes an alias for the 
+** MEM_Blob content contained in register P2.
+**
+** A pseudo-table created by this opcode is used to hold a single
+** row output from the sorter so that the row can be decomposed into
+** individual columns using the OP_Column opcode.  The OP_Column opcode
+** is the only cursor opcode that works with a pseudo-table.
+**
+** P3 is the number of fields in the records that will be stored by
+** the pseudo-table.
+*/
+case OP_OpenPseudo: {
+#if 0  /* local variables moved into u.ay */
+  VdbeCursor *pCx;
+#endif /* local variables moved into u.ay */
+
+  assert( pOp->p1>=0 );
+  u.ay.pCx = allocateCursor(p, pOp->p1, pOp->p3, -1, 0);
+  if( u.ay.pCx==0 ) goto no_mem;
+  u.ay.pCx->nullRow = 1;
+  u.ay.pCx->pseudoTableReg = pOp->p2;
+  u.ay.pCx->isTable = 1;
+  u.ay.pCx->isIndex = 0;
+  break;
+}
+
+/* Opcode: Close P1 * * * *
+**
+** Close a cursor previously opened as P1.  If P1 is not
+** currently open, this instruction is a no-op.
+*/
+case OP_Close: {
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  sqlite3VdbeFreeCursor(p, p->apCsr[pOp->p1]);
+  p->apCsr[pOp->p1] = 0;
+  break;
+}
+
+/* Opcode: SeekGe P1 P2 P3 P4 *
+**
+** If cursor P1 refers to an SQL table (B-Tree that uses integer keys), 
+** use the value in register P3 as the key.  If cursor P1 refers 
+** to an SQL index, then P3 is the first in an array of P4 registers 
+** that are used as an unpacked index key. 
+**
+** Reposition cursor P1 so that  it points to the smallest entry that 
+** is greater than or equal to the key value. If there are no records 
+** greater than or equal to the key and P2 is not zero, then jump to P2.
+**
+** See also: Found, NotFound, Distinct, SeekLt, SeekGt, SeekLe
+*/
+/* Opcode: SeekGt P1 P2 P3 P4 *
+**
+** If cursor P1 refers to an SQL table (B-Tree that uses integer keys), 
+** use the value in register P3 as a key. If cursor P1 refers 
+** to an SQL index, then P3 is the first in an array of P4 registers 
+** that are used as an unpacked index key. 
+**
+** Reposition cursor P1 so that  it points to the smallest entry that 
+** is greater than the key value. If there are no records greater than 
+** the key and P2 is not zero, then jump to P2.
+**
+** See also: Found, NotFound, Distinct, SeekLt, SeekGe, SeekLe
+*/
+/* Opcode: SeekLt P1 P2 P3 P4 * 
+**
+** If cursor P1 refers to an SQL table (B-Tree that uses integer keys), 
+** use the value in register P3 as a key. If cursor P1 refers 
+** to an SQL index, then P3 is the first in an array of P4 registers 
+** that are used as an unpacked index key. 
+**
+** Reposition cursor P1 so that  it points to the largest entry that 
+** is less than the key value. If there are no records less than 
+** the key and P2 is not zero, then jump to P2.
+**
+** See also: Found, NotFound, Distinct, SeekGt, SeekGe, SeekLe
+*/
+/* Opcode: SeekLe P1 P2 P3 P4 *
+**
+** If cursor P1 refers to an SQL table (B-Tree that uses integer keys), 
+** use the value in register P3 as a key. If cursor P1 refers 
+** to an SQL index, then P3 is the first in an array of P4 registers 
+** that are used as an unpacked index key. 
+**
+** Reposition cursor P1 so that it points to the largest entry that 
+** is less than or equal to the key value. If there are no records 
+** less than or equal to the key and P2 is not zero, then jump to P2.
+**
+** See also: Found, NotFound, Distinct, SeekGt, SeekGe, SeekLt
+*/
+case OP_SeekLt:         /* jump, in3 */
+case OP_SeekLe:         /* jump, in3 */
+case OP_SeekGe:         /* jump, in3 */
+case OP_SeekGt: {       /* jump, in3 */
+#if 0  /* local variables moved into u.az */
+  int res;
+  int oc;
+  VdbeCursor *pC;
+  UnpackedRecord r;
+  int nField;
+  i64 iKey;      /* The rowid we are to seek to */
+#endif /* local variables moved into u.az */
+
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  assert( pOp->p2!=0 );
+  u.az.pC = p->apCsr[pOp->p1];
+  assert( u.az.pC!=0 );
+  assert( u.az.pC->pseudoTableReg==0 );
+  assert( OP_SeekLe == OP_SeekLt+1 );
+  assert( OP_SeekGe == OP_SeekLt+2 );
+  assert( OP_SeekGt == OP_SeekLt+3 );
+  assert( u.az.pC->isOrdered );
+  if( u.az.pC->pCursor!=0 ){
+    u.az.oc = pOp->opcode;
+    u.az.pC->nullRow = 0;
+    if( u.az.pC->isTable ){
+      /* The input value in P3 might be of any type: integer, real, string,
+      ** blob, or NULL.  But it needs to be an integer before we can do
+      ** the seek, so covert it. */
+      pIn3 = &aMem[pOp->p3];
+      applyNumericAffinity(pIn3);
+      u.az.iKey = sqlite3VdbeIntValue(pIn3);
+      u.az.pC->rowidIsValid = 0;
+
+      /* If the P3 value could not be converted into an integer without
+      ** loss of information, then special processing is required... */
+      if( (pIn3->flags & MEM_Int)==0 ){
+        if( (pIn3->flags & MEM_Real)==0 ){
+          /* If the P3 value cannot be converted into any kind of a number,
+          ** then the seek is not possible, so jump to P2 */
+          pc = pOp->p2 - 1;
+          break;
+        }
+        /* If we reach this point, then the P3 value must be a floating
+        ** point number. */
+        assert( (pIn3->flags & MEM_Real)!=0 );
+
+        if( u.az.iKey==SMALLEST_INT64 && (pIn3->r<(double)u.az.iKey || pIn3->r>0) ){
+          /* The P3 value is too large in magnitude to be expressed as an
+          ** integer. */
+          u.az.res = 1;
+          if( pIn3->r<0 ){
+            if( u.az.oc>=OP_SeekGe ){  assert( u.az.oc==OP_SeekGe || u.az.oc==OP_SeekGt );
+              rc = sqlite3BtreeFirst(u.az.pC->pCursor, &u.az.res);
+              if( rc!=SQLITE_OK ) goto abort_due_to_error;
+            }
+          }else{
+            if( u.az.oc<=OP_SeekLe ){  assert( u.az.oc==OP_SeekLt || u.az.oc==OP_SeekLe );
+              rc = sqlite3BtreeLast(u.az.pC->pCursor, &u.az.res);
+              if( rc!=SQLITE_OK ) goto abort_due_to_error;
+            }
+          }
+          if( u.az.res ){
+            pc = pOp->p2 - 1;
+          }
+          break;
+        }else if( u.az.oc==OP_SeekLt || u.az.oc==OP_SeekGe ){
+          /* Use the ceiling() function to convert real->int */
+          if( pIn3->r > (double)u.az.iKey ) u.az.iKey++;
+        }else{
+          /* Use the floor() function to convert real->int */
+          assert( u.az.oc==OP_SeekLe || u.az.oc==OP_SeekGt );
+          if( pIn3->r < (double)u.az.iKey ) u.az.iKey--;
+        }
+      }
+      rc = sqlite3BtreeMovetoUnpacked(u.az.pC->pCursor, 0, (u64)u.az.iKey, 0, &u.az.res);
+      if( rc!=SQLITE_OK ){
+        goto abort_due_to_error;
+      }
+      if( u.az.res==0 ){
+        u.az.pC->rowidIsValid = 1;
+        u.az.pC->lastRowid = u.az.iKey;
+      }
+    }else{
+      u.az.nField = pOp->p4.i;
+      assert( pOp->p4type==P4_INT32 );
+      assert( u.az.nField>0 );
+      u.az.r.pKeyInfo = u.az.pC->pKeyInfo;
+      u.az.r.nField = (u16)u.az.nField;
+
+      /* The next line of code computes as follows, only faster:
+      **   if( u.az.oc==OP_SeekGt || u.az.oc==OP_SeekLe ){
+      **     u.az.r.flags = UNPACKED_INCRKEY;
+      **   }else{
+      **     u.az.r.flags = 0;
+      **   }
+      */
+      u.az.r.flags = (u16)(UNPACKED_INCRKEY * (1 & (u.az.oc - OP_SeekLt)));
+      assert( u.az.oc!=OP_SeekGt || u.az.r.flags==UNPACKED_INCRKEY );
+      assert( u.az.oc!=OP_SeekLe || u.az.r.flags==UNPACKED_INCRKEY );
+      assert( u.az.oc!=OP_SeekGe || u.az.r.flags==0 );
+      assert( u.az.oc!=OP_SeekLt || u.az.r.flags==0 );
+
+      u.az.r.aMem = &aMem[pOp->p3];
+#ifdef SQLITE_DEBUG
+      { int i; for(i=0; i<u.az.r.nField; i++) assert( memIsValid(&u.az.r.aMem[i]) ); }
+#endif
+      ExpandBlob(u.az.r.aMem);
+      rc = sqlite3BtreeMovetoUnpacked(u.az.pC->pCursor, &u.az.r, 0, 0, &u.az.res);
+      if( rc!=SQLITE_OK ){
+        goto abort_due_to_error;
+      }
+      u.az.pC->rowidIsValid = 0;
+    }
+    u.az.pC->deferredMoveto = 0;
+    u.az.pC->cacheStatus = CACHE_STALE;
+#ifdef SQLITE_TEST
+    sqlite3_search_count++;
+#endif
+    if( u.az.oc>=OP_SeekGe ){  assert( u.az.oc==OP_SeekGe || u.az.oc==OP_SeekGt );
+      if( u.az.res<0 || (u.az.res==0 && u.az.oc==OP_SeekGt) ){
+        rc = sqlite3BtreeNext(u.az.pC->pCursor, &u.az.res);
+        if( rc!=SQLITE_OK ) goto abort_due_to_error;
+        u.az.pC->rowidIsValid = 0;
+      }else{
+        u.az.res = 0;
+      }
+    }else{
+      assert( u.az.oc==OP_SeekLt || u.az.oc==OP_SeekLe );
+      if( u.az.res>0 || (u.az.res==0 && u.az.oc==OP_SeekLt) ){
+        rc = sqlite3BtreePrevious(u.az.pC->pCursor, &u.az.res);
+        if( rc!=SQLITE_OK ) goto abort_due_to_error;
+        u.az.pC->rowidIsValid = 0;
+      }else{
+        /* u.az.res might be negative because the table is empty.  Check to
+        ** see if this is the case.
+        */
+        u.az.res = sqlite3BtreeEof(u.az.pC->pCursor);
+      }
+    }
+    assert( pOp->p2>0 );
+    if( u.az.res ){
+      pc = pOp->p2 - 1;
+    }
+  }else{
+    /* This happens when attempting to open the sqlite3_master table
+    ** for read access returns SQLITE_EMPTY. In this case always
+    ** take the jump (since there are no records in the table).
+    */
+    pc = pOp->p2 - 1;
+  }
+  break;
+}
+
+/* Opcode: Seek P1 P2 * * *
+**
+** P1 is an open table cursor and P2 is a rowid integer.  Arrange
+** for P1 to move so that it points to the rowid given by P2.
+**
+** This is actually a deferred seek.  Nothing actually happens until
+** the cursor is used to read a record.  That way, if no reads
+** occur, no unnecessary I/O happens.
+*/
+case OP_Seek: {    /* in2 */
+#if 0  /* local variables moved into u.ba */
+  VdbeCursor *pC;
+#endif /* local variables moved into u.ba */
+
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  u.ba.pC = p->apCsr[pOp->p1];
+  assert( u.ba.pC!=0 );
+  if( ALWAYS(u.ba.pC->pCursor!=0) ){
+    assert( u.ba.pC->isTable );
+    u.ba.pC->nullRow = 0;
+    pIn2 = &aMem[pOp->p2];
+    u.ba.pC->movetoTarget = sqlite3VdbeIntValue(pIn2);
+    u.ba.pC->rowidIsValid = 0;
+    u.ba.pC->deferredMoveto = 1;
+  }
+  break;
+}
+  
+
+/* Opcode: Found P1 P2 P3 P4 *
+**
+** If P4==0 then register P3 holds a blob constructed by MakeRecord.  If
+** P4>0 then register P3 is the first of P4 registers that form an unpacked
+** record.
+**
+** Cursor P1 is on an index btree.  If the record identified by P3 and P4
+** is a prefix of any entry in P1 then a jump is made to P2 and
+** P1 is left pointing at the matching entry.
+*/
+/* Opcode: NotFound P1 P2 P3 P4 *
+**
+** If P4==0 then register P3 holds a blob constructed by MakeRecord.  If
+** P4>0 then register P3 is the first of P4 registers that form an unpacked
+** record.
+** 
+** Cursor P1 is on an index btree.  If the record identified by P3 and P4
+** is not the prefix of any entry in P1 then a jump is made to P2.  If P1 
+** does contain an entry whose prefix matches the P3/P4 record then control
+** falls through to the next instruction and P1 is left pointing at the
+** matching entry.
+**
+** See also: Found, NotExists, IsUnique
+*/
+case OP_NotFound:       /* jump, in3 */
+case OP_Found: {        /* jump, in3 */
+#if 0  /* local variables moved into u.bb */
+  int alreadyExists;
+  VdbeCursor *pC;
+  int res;
+  UnpackedRecord *pIdxKey;
+  UnpackedRecord r;
+  char aTempRec[ROUND8(sizeof(UnpackedRecord)) + sizeof(Mem)*3 + 7];
+#endif /* local variables moved into u.bb */
+
+#ifdef SQLITE_TEST
+  sqlite3_found_count++;
+#endif
+
+  u.bb.alreadyExists = 0;
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  assert( pOp->p4type==P4_INT32 );
+  u.bb.pC = p->apCsr[pOp->p1];
+  assert( u.bb.pC!=0 );
+  pIn3 = &aMem[pOp->p3];
+  if( ALWAYS(u.bb.pC->pCursor!=0) ){
+
+    assert( u.bb.pC->isTable==0 );
+    if( pOp->p4.i>0 ){
+      u.bb.r.pKeyInfo = u.bb.pC->pKeyInfo;
+      u.bb.r.nField = (u16)pOp->p4.i;
+      u.bb.r.aMem = pIn3;
+#ifdef SQLITE_DEBUG
+      { int i; for(i=0; i<u.bb.r.nField; i++) assert( memIsValid(&u.bb.r.aMem[i]) ); }
+#endif
+      u.bb.r.flags = UNPACKED_PREFIX_MATCH;
+      u.bb.pIdxKey = &u.bb.r;
+    }else{
+      assert( pIn3->flags & MEM_Blob );
+      assert( (pIn3->flags & MEM_Zero)==0 );  /* zeroblobs already expanded */
+      u.bb.pIdxKey = sqlite3VdbeRecordUnpack(u.bb.pC->pKeyInfo, pIn3->n, pIn3->z,
+                                        u.bb.aTempRec, sizeof(u.bb.aTempRec));
+      if( u.bb.pIdxKey==0 ){
+        goto no_mem;
+      }
+      u.bb.pIdxKey->flags |= UNPACKED_PREFIX_MATCH;
+    }
+    rc = sqlite3BtreeMovetoUnpacked(u.bb.pC->pCursor, u.bb.pIdxKey, 0, 0, &u.bb.res);
+    if( pOp->p4.i==0 ){
+      sqlite3VdbeDeleteUnpackedRecord(u.bb.pIdxKey);
+    }
+    if( rc!=SQLITE_OK ){
+      break;
+    }
+    u.bb.alreadyExists = (u.bb.res==0);
+    u.bb.pC->deferredMoveto = 0;
+    u.bb.pC->cacheStatus = CACHE_STALE;
+  }
+  if( pOp->opcode==OP_Found ){
+    if( u.bb.alreadyExists ) pc = pOp->p2 - 1;
+  }else{
+    if( !u.bb.alreadyExists ) pc = pOp->p2 - 1;
+  }
+  break;
+}
+
+/* Opcode: IsUnique P1 P2 P3 P4 *
+**
+** Cursor P1 is open on an index b-tree - that is to say, a btree which
+** no data and where the key are records generated by OP_MakeRecord with
+** the list field being the integer ROWID of the entry that the index
+** entry refers to.
+**
+** The P3 register contains an integer record number. Call this record 
+** number R. Register P4 is the first in a set of N contiguous registers
+** that make up an unpacked index key that can be used with cursor P1.
+** The value of N can be inferred from the cursor. N includes the rowid
+** value appended to the end of the index record. This rowid value may
+** or may not be the same as R.
+**
+** If any of the N registers beginning with register P4 contains a NULL
+** value, jump immediately to P2.
+**
+** Otherwise, this instruction checks if cursor P1 contains an entry
+** where the first (N-1) fields match but the rowid value at the end
+** of the index entry is not R. If there is no such entry, control jumps
+** to instruction P2. Otherwise, the rowid of the conflicting index
+** entry is copied to register P3 and control falls through to the next
+** instruction.
+**
+** See also: NotFound, NotExists, Found
+*/
+case OP_IsUnique: {        /* jump, in3 */
+#if 0  /* local variables moved into u.bc */
+  u16 ii;
+  VdbeCursor *pCx;
+  BtCursor *pCrsr;
+  u16 nField;
+  Mem *aMx;
+  UnpackedRecord r;                  /* B-Tree index search key */
+  i64 R;                             /* Rowid stored in register P3 */
+#endif /* local variables moved into u.bc */
+
+  pIn3 = &aMem[pOp->p3];
+  u.bc.aMx = &aMem[pOp->p4.i];
+  /* Assert that the values of parameters P1 and P4 are in range. */
+  assert( pOp->p4type==P4_INT32 );
+  assert( pOp->p4.i>0 && pOp->p4.i<=p->nMem );
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+
+  /* Find the index cursor. */
+  u.bc.pCx = p->apCsr[pOp->p1];
+  assert( u.bc.pCx->deferredMoveto==0 );
+  u.bc.pCx->seekResult = 0;
+  u.bc.pCx->cacheStatus = CACHE_STALE;
+  u.bc.pCrsr = u.bc.pCx->pCursor;
+
+  /* If any of the values are NULL, take the jump. */
+  u.bc.nField = u.bc.pCx->pKeyInfo->nField;
+  for(u.bc.ii=0; u.bc.ii<u.bc.nField; u.bc.ii++){
+    if( u.bc.aMx[u.bc.ii].flags & MEM_Null ){
+      pc = pOp->p2 - 1;
+      u.bc.pCrsr = 0;
+      break;
+    }
+  }
+  assert( (u.bc.aMx[u.bc.nField].flags & MEM_Null)==0 );
+
+  if( u.bc.pCrsr!=0 ){
+    /* Populate the index search key. */
+    u.bc.r.pKeyInfo = u.bc.pCx->pKeyInfo;
+    u.bc.r.nField = u.bc.nField + 1;
+    u.bc.r.flags = UNPACKED_PREFIX_SEARCH;
+    u.bc.r.aMem = u.bc.aMx;
+#ifdef SQLITE_DEBUG
+    { int i; for(i=0; i<u.bc.r.nField; i++) assert( memIsValid(&u.bc.r.aMem[i]) ); }
+#endif
+
+    /* Extract the value of u.bc.R from register P3. */
+    sqlite3VdbeMemIntegerify(pIn3);
+    u.bc.R = pIn3->u.i;
+
+    /* Search the B-Tree index. If no conflicting record is found, jump
+    ** to P2. Otherwise, copy the rowid of the conflicting record to
+    ** register P3 and fall through to the next instruction.  */
+    rc = sqlite3BtreeMovetoUnpacked(u.bc.pCrsr, &u.bc.r, 0, 0, &u.bc.pCx->seekResult);
+    if( (u.bc.r.flags & UNPACKED_PREFIX_SEARCH) || u.bc.r.rowid==u.bc.R ){
+      pc = pOp->p2 - 1;
+    }else{
+      pIn3->u.i = u.bc.r.rowid;
+    }
+  }
+  break;
+}
+
+/* Opcode: NotExists P1 P2 P3 * *
+**
+** Use the content of register P3 as a integer key.  If a record 
+** with that key does not exist in table of P1, then jump to P2. 
+** If the record does exist, then fall through.  The cursor is left 
+** pointing to the record if it exists.
+**
+** The difference between this operation and NotFound is that this
+** operation assumes the key is an integer and that P1 is a table whereas
+** NotFound assumes key is a blob constructed from MakeRecord and
+** P1 is an index.
+**
+** See also: Found, NotFound, IsUnique
+*/
+case OP_NotExists: {        /* jump, in3 */
+#if 0  /* local variables moved into u.bd */
+  VdbeCursor *pC;
+  BtCursor *pCrsr;
+  int res;
+  u64 iKey;
+#endif /* local variables moved into u.bd */
+
+  pIn3 = &aMem[pOp->p3];
+  assert( pIn3->flags & MEM_Int );
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  u.bd.pC = p->apCsr[pOp->p1];
+  assert( u.bd.pC!=0 );
+  assert( u.bd.pC->isTable );
+  assert( u.bd.pC->pseudoTableReg==0 );
+  u.bd.pCrsr = u.bd.pC->pCursor;
+  if( u.bd.pCrsr!=0 ){
+    u.bd.res = 0;
+    u.bd.iKey = pIn3->u.i;
+    rc = sqlite3BtreeMovetoUnpacked(u.bd.pCrsr, 0, u.bd.iKey, 0, &u.bd.res);
+    u.bd.pC->lastRowid = pIn3->u.i;
+    u.bd.pC->rowidIsValid = u.bd.res==0 ?1:0;
+    u.bd.pC->nullRow = 0;
+    u.bd.pC->cacheStatus = CACHE_STALE;
+    u.bd.pC->deferredMoveto = 0;
+    if( u.bd.res!=0 ){
+      pc = pOp->p2 - 1;
+      assert( u.bd.pC->rowidIsValid==0 );
+    }
+    u.bd.pC->seekResult = u.bd.res;
+  }else{
+    /* This happens when an attempt to open a read cursor on the
+    ** sqlite_master table returns SQLITE_EMPTY.
+    */
+    pc = pOp->p2 - 1;
+    assert( u.bd.pC->rowidIsValid==0 );
+    u.bd.pC->seekResult = 0;
+  }
+  break;
+}
+
+/* Opcode: Sequence P1 P2 * * *
+**
+** Find the next available sequence number for cursor P1.
+** Write the sequence number into register P2.
+** The sequence number on the cursor is incremented after this
+** instruction.  
+*/
+case OP_Sequence: {           /* out2-prerelease */
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  assert( p->apCsr[pOp->p1]!=0 );
+  pOut->u.i = p->apCsr[pOp->p1]->seqCount++;
+  break;
+}
+
+
+/* Opcode: NewRowid P1 P2 P3 * *
+**
+** Get a new integer record number (a.k.a "rowid") used as the key to a table.
+** The record number is not previously used as a key in the database
+** table that cursor P1 points to.  The new record number is written
+** written to register P2.
+**
+** If P3>0 then P3 is a register in the root frame of this VDBE that holds 
+** the largest previously generated record number. No new record numbers are
+** allowed to be less than this value. When this value reaches its maximum, 
+** a SQLITE_FULL error is generated. The P3 register is updated with the '
+** generated record number. This P3 mechanism is used to help implement the
+** AUTOINCREMENT feature.
+*/
+case OP_NewRowid: {           /* out2-prerelease */
+#if 0  /* local variables moved into u.be */
+  i64 v;                 /* The new rowid */
+  VdbeCursor *pC;        /* Cursor of table to get the new rowid */
+  int res;               /* Result of an sqlite3BtreeLast() */
+  int cnt;               /* Counter to limit the number of searches */
+  Mem *pMem;             /* Register holding largest rowid for AUTOINCREMENT */
+  VdbeFrame *pFrame;     /* Root frame of VDBE */
+#endif /* local variables moved into u.be */
+
+  u.be.v = 0;
+  u.be.res = 0;
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  u.be.pC = p->apCsr[pOp->p1];
+  assert( u.be.pC!=0 );
+  if( NEVER(u.be.pC->pCursor==0) ){
+    /* The zero initialization above is all that is needed */
+  }else{
+    /* The next rowid or record number (different terms for the same
+    ** thing) is obtained in a two-step algorithm.
+    **
+    ** First we attempt to find the largest existing rowid and add one
+    ** to that.  But if the largest existing rowid is already the maximum
+    ** positive integer, we have to fall through to the second
+    ** probabilistic algorithm
+    **
+    ** The second algorithm is to select a rowid at random and see if
+    ** it already exists in the table.  If it does not exist, we have
+    ** succeeded.  If the random rowid does exist, we select a new one
+    ** and try again, up to 100 times.
+    */
+    assert( u.be.pC->isTable );
+
+#ifdef SQLITE_32BIT_ROWID
+#   define MAX_ROWID 0x7fffffff
+#else
+    /* Some compilers complain about constants of the form 0x7fffffffffffffff.
+    ** Others complain about 0x7ffffffffffffffffLL.  The following macro seems
+    ** to provide the constant while making all compilers happy.
+    */
+#   define MAX_ROWID  (i64)( (((u64)0x7fffffff)<<32) | (u64)0xffffffff )
+#endif
+
+    if( !u.be.pC->useRandomRowid ){
+      u.be.v = sqlite3BtreeGetCachedRowid(u.be.pC->pCursor);
+      if( u.be.v==0 ){
+        rc = sqlite3BtreeLast(u.be.pC->pCursor, &u.be.res);
+        if( rc!=SQLITE_OK ){
+          goto abort_due_to_error;
+        }
+        if( u.be.res ){
+          u.be.v = 1;   /* IMP: R-61914-48074 */
+        }else{
+          assert( sqlite3BtreeCursorIsValid(u.be.pC->pCursor) );
+          rc = sqlite3BtreeKeySize(u.be.pC->pCursor, &u.be.v);
+          assert( rc==SQLITE_OK );   /* Cannot fail following BtreeLast() */
+          if( u.be.v==MAX_ROWID ){
+            u.be.pC->useRandomRowid = 1;
+          }else{
+            u.be.v++;   /* IMP: R-29538-34987 */
+          }
+        }
+      }
+
+#ifndef SQLITE_OMIT_AUTOINCREMENT
+      if( pOp->p3 ){
+        /* Assert that P3 is a valid memory cell. */
+        assert( pOp->p3>0 );
+        if( p->pFrame ){
+          for(u.be.pFrame=p->pFrame; u.be.pFrame->pParent; u.be.pFrame=u.be.pFrame->pParent);
+          /* Assert that P3 is a valid memory cell. */
+          assert( pOp->p3<=u.be.pFrame->nMem );
+          u.be.pMem = &u.be.pFrame->aMem[pOp->p3];
+        }else{
+          /* Assert that P3 is a valid memory cell. */
+          assert( pOp->p3<=p->nMem );
+          u.be.pMem = &aMem[pOp->p3];
+          memAboutToChange(p, u.be.pMem);
+        }
+        assert( memIsValid(u.be.pMem) );
+
+        REGISTER_TRACE(pOp->p3, u.be.pMem);
+        sqlite3VdbeMemIntegerify(u.be.pMem);
+        assert( (u.be.pMem->flags & MEM_Int)!=0 );  /* mem(P3) holds an integer */
+        if( u.be.pMem->u.i==MAX_ROWID || u.be.pC->useRandomRowid ){
+          rc = SQLITE_FULL;   /* IMP: R-12275-61338 */
+          goto abort_due_to_error;
+        }
+        if( u.be.v<u.be.pMem->u.i+1 ){
+          u.be.v = u.be.pMem->u.i + 1;
+        }
+        u.be.pMem->u.i = u.be.v;
+      }
+#endif
+
+      sqlite3BtreeSetCachedRowid(u.be.pC->pCursor, u.be.v<MAX_ROWID ? u.be.v+1 : 0);
+    }
+    if( u.be.pC->useRandomRowid ){
+      /* IMPLEMENTATION-OF: R-07677-41881 If the largest ROWID is equal to the
+      ** largest possible integer (9223372036854775807) then the database
+      ** engine starts picking positive candidate ROWIDs at random until
+      ** it finds one that is not previously used. */
+      assert( pOp->p3==0 );  /* We cannot be in random rowid mode if this is
+                             ** an AUTOINCREMENT table. */
+      /* on the first attempt, simply do one more than previous */
+      u.be.v = db->lastRowid;
+      u.be.v &= (MAX_ROWID>>1); /* ensure doesn't go negative */
+      u.be.v++; /* ensure non-zero */
+      u.be.cnt = 0;
+      while(   ((rc = sqlite3BtreeMovetoUnpacked(u.be.pC->pCursor, 0, (u64)u.be.v,
+                                                 0, &u.be.res))==SQLITE_OK)
+            && (u.be.res==0)
+            && (++u.be.cnt<100)){
+        /* collision - try another random rowid */
+        sqlite3_randomness(sizeof(u.be.v), &u.be.v);
+        if( u.be.cnt<5 ){
+          /* try "small" random rowids for the initial attempts */
+          u.be.v &= 0xffffff;
+        }else{
+          u.be.v &= (MAX_ROWID>>1); /* ensure doesn't go negative */
+        }
+        u.be.v++; /* ensure non-zero */
+      }
+      if( rc==SQLITE_OK && u.be.res==0 ){
+        rc = SQLITE_FULL;   /* IMP: R-38219-53002 */
+        goto abort_due_to_error;
+      }
+      assert( u.be.v>0 );  /* EV: R-40812-03570 */
+    }
+    u.be.pC->rowidIsValid = 0;
+    u.be.pC->deferredMoveto = 0;
+    u.be.pC->cacheStatus = CACHE_STALE;
+  }
+  pOut->u.i = u.be.v;
+  break;
+}
+
+/* Opcode: Insert P1 P2 P3 P4 P5
+**
+** Write an entry into the table of cursor P1.  A new entry is
+** created if it doesn't already exist or the data for an existing
+** entry is overwritten.  The data is the value MEM_Blob stored in register
+** number P2. The key is stored in register P3. The key must
+** be a MEM_Int.
+**
+** If the OPFLAG_NCHANGE flag of P5 is set, then the row change count is
+** incremented (otherwise not).  If the OPFLAG_LASTROWID flag of P5 is set,
+** then rowid is stored for subsequent return by the
+** sqlite3_last_insert_rowid() function (otherwise it is unmodified).
+**
+** If the OPFLAG_USESEEKRESULT flag of P5 is set and if the result of
+** the last seek operation (OP_NotExists) was a success, then this
+** operation will not attempt to find the appropriate row before doing
+** the insert but will instead overwrite the row that the cursor is
+** currently pointing to.  Presumably, the prior OP_NotExists opcode
+** has already positioned the cursor correctly.  This is an optimization
+** that boosts performance by avoiding redundant seeks.
+**
+** If the OPFLAG_ISUPDATE flag is set, then this opcode is part of an
+** UPDATE operation.  Otherwise (if the flag is clear) then this opcode
+** is part of an INSERT operation.  The difference is only important to
+** the update hook.
+**
+** Parameter P4 may point to a string containing the table-name, or
+** may be NULL. If it is not NULL, then the update-hook 
+** (sqlite3.xUpdateCallback) is invoked following a successful insert.
+**
+** (WARNING/TODO: If P1 is a pseudo-cursor and P2 is dynamically
+** allocated, then ownership of P2 is transferred to the pseudo-cursor
+** and register P2 becomes ephemeral.  If the cursor is changed, the
+** value of register P2 will then change.  Make sure this does not
+** cause any problems.)
+**
+** This instruction only works on tables.  The equivalent instruction
+** for indices is OP_IdxInsert.
+*/
+/* Opcode: InsertInt P1 P2 P3 P4 P5
+**
+** This works exactly like OP_Insert except that the key is the
+** integer value P3, not the value of the integer stored in register P3.
+*/
+case OP_Insert: 
+case OP_InsertInt: {
+#if 0  /* local variables moved into u.bf */
+  Mem *pData;       /* MEM cell holding data for the record to be inserted */
+  Mem *pKey;        /* MEM cell holding key  for the record */
+  i64 iKey;         /* The integer ROWID or key for the record to be inserted */
+  VdbeCursor *pC;   /* Cursor to table into which insert is written */
+  int nZero;        /* Number of zero-bytes to append */
+  int seekResult;   /* Result of prior seek or 0 if no USESEEKRESULT flag */
+  const char *zDb;  /* database name - used by the update hook */
+  const char *zTbl; /* Table name - used by the opdate hook */
+  int op;           /* Opcode for update hook: SQLITE_UPDATE or SQLITE_INSERT */
+#endif /* local variables moved into u.bf */
+
+  u.bf.pData = &aMem[pOp->p2];
+  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
+  assert( memIsValid(u.bf.pData) );
+  u.bf.pC = p->apCsr[pOp->p1];
+  assert( u.bf.pC!=0 );
+  assert( u.bf.pC->pCursor!=0 );
+  assert( u.bf.pC->pseudoTableReg==0 );
+  assert( u.bf.pC->isTable );
+  REGISTER_TRACE(pOp->p2, u.bf.pData);
+
+  if( pOp->opcode==OP_Insert ){
+    u.bf.pKey = &aMem[pOp->p3];
+    assert( u.bf.pKey->flags & MEM_Int );
+    assert( memIsValid(u.bf.pKey) );
+    REGISTER_TRACE(pOp->p3, u.bf.pKey);
+    u.bf.iKey = u.bf.pKey->u.i;
+  }else{
+    assert( pOp->opcode==OP_InsertInt );
+    u.bf.iKey = pOp->p3;
+  }
+
+  if( pOp->p5 & OPFLAG_NCHANGE ) p->nChange++;
+  if( pOp->p5 & OPFLAG_LASTROWID ) db->lastRowid = u.bf.iKey;
+  if( u.bf.pData->flags & MEM_Null ){
+    u.bf.pData->z = 0;
+    u.bf.pData->n = 0;
+  }else{
+    assert( u.bf.pData->flags & (MEM_Blob|MEM_Str) );
+  }
+  u.bf.seekResult = ((pOp->p5 & OPFLAG_USESEEKRESULT) ? u.bf.pC->seekResult : 0);
+  if( u.bf.pData->flags & MEM_Zero ){
+    u.bf.nZero = u.bf.pData->u.nZero;
+  }else{
+    u.bf.nZero = 0;
+  }
+  sqlite3BtreeSetCachedRowid(u.bf.pC->pCursor, 0);
+  rc = sqlite3BtreeInsert(u.bf.pC->pCursor, 0, u.bf.iKey,
+                          u.bf.pData->z, u.bf.pData->n, u.bf.nZero,
+                          pOp->p5 & OPFLAG_APPEND, u.bf.seekResult
+  );
+  u.bf.pC->rowidIsValid = 0;
+  u.bf.pC->deferredMoveto = 0;
+  u.bf.pC->cacheStatus = CACHE_STALE;
+
+  /* Invoke the update-hook if required. */
+  if( rc==SQLITE_OK && db->xUpdateCallback && pOp->p4.z ){
+    u.bf.zDb = db->aDb[u.bf.pC->iDb].zName;
+    u.bf.zTbl = pOp->p4.z;
+    u.bf.op = ((pOp->p5 & OPFLAG_ISUPDATE) ? SQLITE_UPDATE : SQLITE_INSERT);
+    assert( u.bf.pC->isTable );
+    db->xUpdateCallback(db->pUpdateArg, u.bf.op, u.bf.zDb, u.bf.zTbl, u.bf.iKey);
+    assert( u.bf.pC->iDb>=0 );
+  }
+  break;
+}
+
+/* Opcode: Delete P1 P2 * P4 *
+**
+** Delete the record at which the P1 cursor is currently pointing.
+**
+** The cursor will be left pointing at either the next or the previous
+** record in the table. If it is left pointing at the next record, then
+** the next Next instruction will be a no-op.  Hence it is OK to delete
+** a record from within an Next loop.
author	sfan5 <sfan5@live.de>	2021-03-12 19:30:56 +0100
committer	sfan5 <sfan5@live.de>	2021-03-12 20:56:02 +0100
commit	cff35cf0b328635b2c77c024343f8e7f2d016990 (patch)
tree	a347f326ca6fa00b75f8a23f1be5ea08b7b49134 /src/mapsector.h
parent	f213376b35795982edbdeb2caeb7ca9495b3848e (diff)
download	minetest-cff35cf0b328635b2c77c024343f8e7f2d016990.tar.gz minetest-cff35cf0b328635b2c77c024343f8e7f2d016990.tar.bz2 minetest-cff35cf0b328635b2c77c024343f8e7f2d016990.zip