Refactor logging

- Add warning log level
- Change debug_log_level setting to enumeration string
- Map Irrlicht log events to MT log events
- Encapsulate log_* functions and global variables into a class, Logger
- Unify dstream with standard logging mechanism
- Unify core.debug() with standard core.log() script API

25 files changed, 574 insertions, 627 deletions

diff --git a/builtin/common/strict.lua b/builtin/common/strict.lua
index c7b86461f..05ceadf7a 100644
--- a/builtin/common/strict.lua
+++ b/builtin/common/strict.lua
@@ -9,11 +9,6 @@ function core.global_exists(name)
 end
 
 
-local function warn(message)
-	print(os.date("%H:%M:%S: WARNING: ")..message)
-end
-
-
 local meta = {}
 local declared = {}
 -- Key is source file, line, and variable name; seperated by NULs
@@ -27,7 +22,7 @@ function meta:__newindex(name, value)
 				info.currentline, name)
 		if not warned[warn_key] and info.what ~= "main" and
 				info.what ~= "C" then
-			warn(("Assignment to undeclared "..
+			core.log("warning", ("Assignment to undeclared "..
 					"global %q inside a function at %s.")
 				:format(name, desc))
 			warned[warn_key] = true
@@ -35,9 +30,8 @@ function meta:__newindex(name, value)
 		declared[name] = true
 	end
 	-- Ignore mod namespaces
-	if WARN_INIT and (not core.get_current_modname or
-			name ~= core.get_current_modname()) then
-		warn(("Global variable %q created at %s.")
+	if WARN_INIT and name ~= core.get_current_modname() then
+		core.log("warning", ("Global variable %q created at %s.")
 			:format(name, desc))
 	end
 	rawset(self, name, value)
@@ -48,7 +42,7 @@ function meta:__index(name)
 	local info = debug.getinfo(2, "Sl")
 	local warn_key = ("%s\0%d\0%s"):format(info.source, info.currentline, name)
 	if not declared[name] and not warned[warn_key] and info.what ~= "C" then
-		warn(("Undeclared global variable %q accessed at %s:%s")
+		core.log("warning", ("Undeclared global variable %q accessed at %s:%s")
 				:format(name, info.short_src, info.currentline))
 		warned[warn_key] = true
 	end
diff --git a/builtin/fstk/ui.lua b/builtin/fstk/ui.lua
index 8128c5035..3ac0386ca 100644
--- a/builtin/fstk/ui.lua
+++ b/builtin/fstk/ui.lua
@@ -127,11 +127,13 @@ function ui.update()
 		end
 
 		if (active_toplevel_ui_elements > 1) then
-			print("WARNING: ui manager detected more then one active ui element, self most likely isn't intended")
+			core.log("warning", "more than one active ui "..
+				"element, self most likely isn't intended")
 		end
 
 		if (active_toplevel_ui_elements == 0) then
-			print("WARNING: not a single toplevel ui element active switching to default")
+			core.log("warning", "no toplevel ui element "..
+					"active; switching to default")
 			ui.childlist[ui.default]:show()
 			formspec = ui.childlist[ui.default]:get_formspec()
 		end
diff --git a/builtin/game/deprecated.lua b/builtin/game/deprecated.lua
index 405e599da..cd1cf5e2d 100644
--- a/builtin/game/deprecated.lua
+++ b/builtin/game/deprecated.lua
@@ -4,8 +4,7 @@
 -- Default material types
 --
 local function digprop_err()
-	core.log("info", debug.traceback())
-	core.log("info", "WARNING: The core.digprop_* functions are obsolete and need to be replaced by item groups.")
+	core.log("deprecated", "The core.digprop_* functions are obsolete and need to be replaced by item groups.")
 end
 
 core.digprop_constanttime = digprop_err
@@ -16,12 +15,12 @@ core.digprop_woodlike = digprop_err
 core.digprop_leaveslike = digprop_err
 core.digprop_glasslike = digprop_err
 
-core.node_metadata_inventory_move_allow_all = function()
-	core.log("info", "WARNING: core.node_metadata_inventory_move_allow_all is obsolete and does nothing.")
+function core.node_metadata_inventory_move_allow_all()
+	core.log("deprecated", "core.node_metadata_inventory_move_allow_all is obsolete and does nothing.")
 end
 
-core.add_to_creative_inventory = function(itemstring)
-	core.log('info', "WARNING: core.add_to_creative_inventory: This function is deprecated and does nothing.")
+function core.add_to_creative_inventory(itemstring)
+	core.log("deprecated", "core.add_to_creative_inventory: This function is deprecated and does nothing.")
 end
 
 --
@@ -32,7 +31,7 @@ local envref_deprecation_message_printed = false
 setmetatable(core.env, {
 	__index = function(table, key)
 		if not envref_deprecation_message_printed then
-			core.log("info", "WARNING: core.env:[...] is deprecated and should be replaced with core.[...]")
+			core.log("deprecated", "core.env:[...] is deprecated and should be replaced with core.[...]")
 			envref_deprecation_message_printed = true
 		end
 		local func = core[key]
diff --git a/builtin/game/register.lua b/builtin/game/register.lua
index d0e04bfc3..840ade127 100644
--- a/builtin/game/register.lua
+++ b/builtin/game/register.lua
@@ -221,7 +221,7 @@ function core.register_alias(name, convert_to)
 		error("Unable to register alias: Name is forbidden: " .. name)
 	end
 	if core.registered_items[name] ~= nil then
-		core.log("WARNING: Not registering alias, item with same name" ..
+		core.log("warning", "Not registering alias, item with same name" ..
 			" is already defined: " .. name .. " -> " .. convert_to)
 	else
 		--core.log("Registering alias: " .. name .. " -> " .. convert_to)
diff --git a/builtin/init.lua b/builtin/init.lua
index 095771d19..02fb9db93 100644
--- a/builtin/init.lua
+++ b/builtin/init.lua
@@ -6,7 +6,7 @@
 --
 
 -- Initialize some very basic things
-print = core.debug
+function core.debug(...) core.log(table.concat({...}, "\t")) end
 math.randomseed(os.time())
 os.setlocale("C", "numeric")
 minetest = core
diff --git a/doc/lua_api.txt b/doc/lua_api.txt
index 926282976..f0f70d073 100644
--- a/doc/lua_api.txt
+++ b/doc/lua_api.txt
@@ -1774,11 +1774,11 @@ Helper functions
       * false: return only file names.
 
 ### Logging
-* `minetest.debug(line)`
-    * Always printed to `stderr` and logfile (`print()` is redirected here)
-* `minetest.log(line)`
-* `minetest.log(loglevel, line)`
-    * `loglevel` is one of `"error"`, `"action"`, `"info"`, `"verbose"`
+* `minetest.debug(...)`
+    * Equivalent to `minetest.log(table.concat({...}, "\t"))`
+* `minetest.log([level,] text)`
+    * `level` is one of `"none"`, `"error"`, `"warning"`, `"action"`,
+      `"info"`, or `"verbose"`.  Default is `"none"`.
 
 ### Registration functions
 Call these functions only at load time!
diff --git a/minetest.conf.example b/minetest.conf.example
index 695e413c9..15d0abbf3 100644
--- a/minetest.conf.example
+++ b/minetest.conf.example
@@ -612,8 +612,9 @@
 #remote_media =
 
 #    Level of logging to be written to debug.txt:
-#    0 = none, 1 = errors and debug, 2 = action, 3 = info, 4 = verbose.
-#debug_log_level = 2
+#      <nothing> (no logging), none (messages with no level), error,
+#      warning, action, info, or verbose.
+#debug_log_level = action
 
 #    Maximum number of blocks that can be queued for loading
 #emergequeue_limit_total = 256
diff --git a/src/client/clientlauncher.cpp b/src/client/clientlauncher.cpp
index 60eb21674..772bbaf23 100644
--- a/src/client/clientlauncher.cpp
+++ b/src/client/clientlauncher.cpp
@@ -89,7 +89,7 @@ bool ClientLauncher::run(GameParams &game_params, const Settings &cmd_args)
 	if (list_video_modes)
 		return print_video_modes();
 
-	if (!init_engine(game_params.log_level)) {
+	if (!init_engine()) {
 		errorstream << "Could not initialize game engine." << std::endl;
 		return false;
 	}
@@ -321,10 +321,10 @@ void ClientLauncher::init_args(GameParams &game_params, const Settings &cmd_args
 			|| cmd_args.getFlag("random-input");
 }
 
-bool ClientLauncher::init_engine(int log_level)
+bool ClientLauncher::init_engine()
 {
 	receiver = new MyEventReceiver();
-	create_engine_device(log_level);
+	create_engine_device();
 	return device != NULL;
 }
 
@@ -455,7 +455,7 @@ bool ClientLauncher::launch_game(std::string &error_message,
 
 		if (game_params.game_spec.isValid() &&
 				game_params.game_spec.id != worldspec.gameid) {
-			errorstream << "WARNING: Overriding gamespec from \""
+			warningstream << "Overriding gamespec from \""
 			            << worldspec.gameid << "\" to \""
 			            << game_params.game_spec.id << "\"" << std::endl;
 			gamespec = game_params.game_spec;
@@ -500,20 +500,8 @@ void ClientLauncher::main_menu(MainMenuData *menudata)
 	smgr->clear();	/* leave scene manager in a clean state */
 }
 
-bool ClientLauncher::create_engine_device(int log_level)
+bool ClientLauncher::create_engine_device()
 {
-	static const irr::ELOG_LEVEL irr_log_level[5] = {
-		ELL_NONE,
-		ELL_ERROR,
-		ELL_WARNING,
-		ELL_INFORMATION,
-#if (IRRLICHT_VERSION_MAJOR == 1 && IRRLICHT_VERSION_MINOR < 8)
-		ELL_INFORMATION
-#else
-		ELL_DEBUG
-#endif
-	};
-
 	// Resolution selection
 	bool fullscreen = g_settings->getBool("fullscreen");
 	u16 screenW = g_settings->getU16("screenW");
@@ -561,10 +549,6 @@ bool ClientLauncher::create_engine_device(int log_level)
 	device = createDeviceEx(params);
 
 	if (device) {
-		// Map our log level to irrlicht engine one.
-		ILogger* irr_logger = device->getLogger();
-		irr_logger->setLogLevel(irr_log_level[log_level]);
-
 		porting::initIrrlicht(device);
 	}
 
diff --git a/src/client/clientlauncher.h b/src/client/clientlauncher.h
index 49ceefc52..b10bbebc9 100644
--- a/src/client/clientlauncher.h
+++ b/src/client/clientlauncher.h
@@ -90,13 +90,13 @@ public:
 
 protected:
 	void init_args(GameParams &game_params, const Settings &cmd_args);
-	bool init_engine(int log_level);
+	bool init_engine();
 
 	bool launch_game(std::string &error_message, bool reconnect_requested,
 		GameParams &game_params, const Settings &cmd_args);
 
 	void main_menu(MainMenuData *menudata);
-	bool create_engine_device(int log_level);
+	bool create_engine_device();
 
 	void speed_tests();
 	bool print_video_modes();
diff --git a/src/client/inputhandler.h b/src/client/inputhandler.h
index a894e35aa..69e4b25fa 100644
--- a/src/client/inputhandler.h
+++ b/src/client/inputhandler.h
@@ -17,8 +17,8 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
-#ifndef __INPUT_HANDLER_H__
-#define __INPUT_HANDLER_H__
+#ifndef INPUT_HANDLER_H
+#define INPUT_HANDLER_H
 
 #include "irrlichttypes_extrabloated.h"
 
@@ -86,16 +86,16 @@ public:
 				}
 			}
 		} else if (event.EventType == irr::EET_LOG_TEXT_EVENT) {
-			static const enum LogMessageLevel irr_loglev_conv[] = {
-				LMT_VERBOSE, // ELL_DEBUG
-				LMT_INFO,    // ELL_INFORMATION
-				LMT_ACTION,  // ELL_WARNING
-				LMT_ERROR,   // ELL_ERROR
-				LMT_ERROR,   // ELL_NONE
+			static const LogLevel irr_loglev_conv[] = {
+				LL_VERBOSE, // ELL_DEBUG
+				LL_INFO,    // ELL_INFORMATION
+				LL_WARNING, // ELL_WARNING
+				LL_ERROR,   // ELL_ERROR
+				LL_NONE,    // ELL_NONE
 			};
 			assert(event.LogEvent.Level < ARRLEN(irr_loglev_conv));
-			log_printline(irr_loglev_conv[event.LogEvent.Level],
-				std::string("Irrlicht: ") + (const char *)event.LogEvent.Text);
+			g_logger.log(irr_loglev_conv[event.LogEvent.Level],
+				std::string("Irrlicht: ") + (const char*) event.LogEvent.Text);
 			return true;
 		}
 		/* always return false in order to continue processing events */
diff --git a/src/debug.cpp b/src/debug.cpp
index 3608f42d2..82aa6d519 100644
--- a/src/debug.cpp
+++ b/src/debug.cpp
@@ -26,6 +26,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include <stdlib.h>
 #include <cstring>
 #include <map>
+#include <sstream>
 #include "threading/mutex.h"
 #include "threading/mutex_auto_lock.h"
 #include "config.h"
@@ -37,114 +38,18 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #endif
 
 /*
-	Debug output
-*/
-
-#define DEBUGSTREAM_COUNT 2
-
-FILE *g_debugstreams[DEBUGSTREAM_COUNT] = {stderr, NULL};
-
-#define DEBUGPRINT(...)\
-{\
-	for(int i=0; i<DEBUGSTREAM_COUNT; i++)\
-	{\
-		if(g_debugstreams[i] != NULL){\
-			fprintf(g_debugstreams[i], __VA_ARGS__);\
-			fflush(g_debugstreams[i]);\
-		}\
-	}\
-}
-
-void debugstreams_init(bool disable_stderr, const char *filename)
-{
-	if(disable_stderr)
-		g_debugstreams[0] = NULL;
-	else
-		g_debugstreams[0] = stderr;
-
-	if(filename)
-		g_debugstreams[1] = fopen(filename, "a");
-
-	if(g_debugstreams[1])
-	{
-		fprintf(g_debugstreams[1], "\n\n-------------\n");
-		fprintf(g_debugstreams[1],     "  Separator  \n");
-		fprintf(g_debugstreams[1],     "-------------\n\n");
-	}
-}
-
-void debugstreams_deinit()
-{
-	if(g_debugstreams[1] != NULL)
-		fclose(g_debugstreams[1]);
-}
-
-class Debugbuf : public std::streambuf
-{
-public:
-	Debugbuf(bool disable_stderr)
-	{
-		m_disable_stderr = disable_stderr;
-	}
-
-	int overflow(int c)
-	{
-		for(int i=0; i<DEBUGSTREAM_COUNT; i++)
-		{
-			if(g_debugstreams[i] == stderr && m_disable_stderr)
-				continue;
-			if(g_debugstreams[i] != NULL)
-				(void)fwrite(&c, 1, 1, g_debugstreams[i]);
-			//TODO: Is this slow?
-			fflush(g_debugstreams[i]);
-		}
-
-		return c;
-	}
-	std::streamsize xsputn(const char *s, std::streamsize n)
-	{
-#ifdef __ANDROID__
-		__android_log_print(ANDROID_LOG_VERBOSE, PROJECT_NAME, "%s", s);
-#endif
-		for(int i=0; i<DEBUGSTREAM_COUNT; i++)
-		{
-			if(g_debugstreams[i] == stderr && m_disable_stderr)
-				continue;
-			if(g_debugstreams[i] != NULL)
-				(void)fwrite(s, 1, n, g_debugstreams[i]);
-			//TODO: Is this slow?
-			fflush(g_debugstreams[i]);
-		}
-
-		return n;
-	}
-
-private:
-	bool m_disable_stderr;
-};
-
-Debugbuf debugbuf(false);
-std::ostream dstream(&debugbuf);
-Debugbuf debugbuf_no_stderr(true);
-std::ostream dstream_no_stderr(&debugbuf_no_stderr);
-Nullstream dummyout;
-
-/*
 	Assert
 */
 
 void sanity_check_fn(const char *assertion, const char *file,
 		unsigned int line, const char *function)
 {
-	DEBUGPRINT("\nIn thread %lx:\n"
-			"%s:%u: %s: An engine assumption '%s' failed.\n",
-			(unsigned long)get_current_thread_id(),
-			file, line, function, assertion);
-
-	debug_stacks_print();
+	errorstream << std::endl << "In thread " << std::hex
+		<< (unsigned long)get_current_thread_id() << ":" << std::endl;
+	errorstream << file << ":" << line << ": " << function
+		<< ": An engine assumption '" << assertion << "' failed." << std::endl;
 
-	if(g_debugstreams[1])
-		fclose(g_debugstreams[1]);
+	debug_stacks_print_to(errorstream);
 
 	abort();
 }
@@ -152,15 +57,12 @@ void sanity_check_fn(const char *assertion, const char *file,
 void fatal_error_fn(const char *msg, const char *file,
 		unsigned int line, const char *function)
 {
-	DEBUGPRINT("\nIn thread %lx:\n"
-			"%s:%u: %s: A fatal error occurred: %s\n",
-			(unsigned long)get_current_thread_id(),
-			file, line, function, msg);
+	errorstream << std::endl << "In thread " << std::hex
+		<< (unsigned long)get_current_thread_id() << ":" << std::endl;
+	errorstream << file << ":" << line << ": " << function
+		<< ": A fatal error occured: " << msg << std::endl;
 
-	debug_stacks_print();
-
-	if(g_debugstreams[1])
-		fclose(g_debugstreams[1]);
+	debug_stacks_print_to(errorstream);
 
 	abort();
 }
@@ -251,22 +153,7 @@ void debug_stacks_print_to(std::ostream &os)
 
 void debug_stacks_print()
 {
-	MutexAutoLock lock(g_debug_stacks_mutex);
-
-	DEBUGPRINT("Debug stacks:\n");
-
-	for(std::map<threadid_t, DebugStack*>::iterator
-			i = g_debug_stacks.begin();
-			i != g_debug_stacks.end(); ++i)
-	{
-		DebugStack *stack = i->second;
-
-		for(int i=0; i<DEBUGSTREAM_COUNT; i++)
-		{
-			if(g_debugstreams[i] != NULL)
-				stack->print(g_debugstreams[i], true);
-		}
-	}
+	debug_stacks_print_to(errorstream);
 }
 
 DebugStacker::DebugStacker(const char *text)
diff --git a/src/debug.h b/src/debug.h
index 2ccbe58ba..b7521fec2 100644
--- a/src/debug.h
+++ b/src/debug.h
@@ -24,6 +24,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include <exception>
 #include <assert.h>
 #include "gettime.h"
+#include "log.h"
 
 #if (defined(WIN32) || defined(_WIN32_WCE))
 	#define WIN32_LEAN_AND_MEAN
@@ -36,9 +37,13 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 	#endif
 	#define __NORETURN __declspec(noreturn)
 	#define __FUNCTION_NAME __FUNCTION__
+	#define NORETURN __declspec(noreturn)
+	#define FUNCTION_NAME __FUNCTION__
 #else
 	#define __NORETURN __attribute__ ((__noreturn__))
 	#define __FUNCTION_NAME __PRETTY_FUNCTION__
+	#define NORETURN __attribute__ ((__noreturn__))
+	#define FUNCTION_NAME __PRETTY_FUNCTION__
 #endif
 
 // Whether to catch all std::exceptions.
@@ -50,30 +55,6 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 	#define CATCH_UNHANDLED_EXCEPTIONS 0
 #endif
 
-/*
-	Debug output
-*/
-
-#define DTIME (getTimestamp()+": ")
-
-extern void debugstreams_init(bool disable_stderr, const char *filename);
-extern void debugstreams_deinit();
-
-// This is used to redirect output to /dev/null
-class Nullstream : public std::ostream {
-public:
-	Nullstream():
-		std::ostream(0)
-	{
-	}
-private:
-};
-
-extern std::ostream dstream;
-extern std::ostream dstream_no_stderr;
-extern Nullstream dummyout;
-
-
 /* Abort program execution immediately
  */
 __NORETURN extern void fatal_error_fn(
@@ -108,6 +89,8 @@ __NORETURN extern void sanity_check_fn(
 
 void debug_set_exception_handler();
 
+#define DTIME ""
+
 /*
 	DebugStack
 */
diff --git a/src/defaultsettings.cpp b/src/defaultsettings.cpp
index dd5332a3b..ac62b2060 100644
--- a/src/defaultsettings.cpp
+++ b/src/defaultsettings.cpp
@@ -279,7 +279,7 @@ void set_default_settings(Settings *settings)
 	settings->setDefault("dedicated_server_step", "0.1");
 	settings->setDefault("ignore_world_load_errors", "false");
 	settings->setDefault("remote_media", "");
-	settings->setDefault("debug_log_level", "2");
+	settings->setDefault("debug_log_level", "action");
 	settings->setDefault("emergequeue_limit_total", "256");
 	settings->setDefault("emergequeue_limit_diskonly", "32");
 	settings->setDefault("emergequeue_limit_generate", "32");
diff --git a/src/game.cpp b/src/game.cpp
index 840d627b6..e966920a6 100644
--- a/src/game.cpp
+++ b/src/game.cpp
@@ -40,7 +40,6 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "guiPasswordChange.h"
 #include "guiVolumeChange.h"
 #include "hud.h"
-#include "logoutputbuffer.h"
 #include "mainmenumanager.h"
 #include "mapblock.h"
 #include "nodedef.h"         // Needed for determining pointing to nodes
@@ -1163,7 +1162,7 @@ static void updateChat(Client &client, f32 dtime, bool show_debug,
 		ChatBackend &chat_backend, gui::IGUIStaticText *guitext_chat)
 {
 	// Add chat log output for errors to be shown in chat
-	static LogOutputBuffer chat_log_error_buf(LMT_ERROR);
+	static LogOutputBuffer chat_log_error_buf(g_logger, LL_ERROR);
 
 	// Get new messages from error log buffer
 	while (!chat_log_error_buf.empty()) {
@@ -2675,7 +2674,7 @@ void Game::processKeyboardInput(VolatileRunFlags *flags,
 		// Print debug stacks
 		dstream << "-----------------------------------------"
 		        << std::endl;
-		dstream << DTIME << "Printing debug stacks:" << std::endl;
+		dstream << "Printing debug stacks:" << std::endl;
 		dstream << "-----------------------------------------"
 		        << std::endl;
 		debug_stacks_print();
diff --git a/src/gameparams.h b/src/gameparams.h
index b50e943d2..bf9953c39 100644
--- a/src/gameparams.h
+++ b/src/gameparams.h
@@ -17,17 +17,18 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
-#ifndef __GAME_PARAMS_H__
-#define __GAME_PARAMS_H__
+#ifndef GAME_PARAMS_H
+#define GAME_PARAMS_H
 
-#include "irrlichttypes_extrabloated.h"
+#include "irrlichttypes.h"
+
+struct SubgameSpec;
 
 struct GameParams {
 	u16 socket_port;
 	std::string world_path;
 	SubgameSpec game_spec;
 	bool is_dedicated_server;
-	int log_level;
 };
 
 #endif
diff --git a/src/log.cpp b/src/log.cpp
index c584d126a..4f77101f9 100644
--- a/src/log.cpp
+++ b/src/log.cpp
@@ -19,19 +19,91 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #include "log.h"
 
-#include <map>
-#include <list>
-#include <sstream>
-#include <algorithm>
-#include "threads.h"
 #include "threading/mutex_auto_lock.h"
 #include "debug.h"
 #include "gettime.h"
 #include "porting.h"
 #include "config.h"
+#include "exceptions.h"
+#include "util/numeric.h"
+#include "log.h"
+
+#include <sstream>
+#include <iostream>
+#include <algorithm>
+#include <cerrno>
+#include <cstring>
+
+class StringBuffer : public std::streambuf {
+public:
+	StringBuffer() {}
+
+	int overflow(int c);
+	virtual void flush(const std::string &buf) = 0;
+	std::streamsize xsputn(const char *s, std::streamsize n);
+	void push_back(char c);
+
+private:
+	std::string buffer;
+};
+
+
+class LogBuffer : public StringBuffer {
+public:
+	LogBuffer(Logger &logger, LogLevel lev) :
+		logger(logger),
+		level(lev)
+	{}
+
+	void flush(const std::string &buffer);
+
+private:
+	Logger &logger;
+	LogLevel level;
+};
+
+
+class RawLogBuffer : public StringBuffer {
+public:
+	void flush(const std::string &buffer);
+};
+
+
+#ifdef __ANDROID__
+static unsigned int level_to_android[] = {
+	ANDROID_LOG_INFO,     // LL_NONE
+	//ANDROID_LOG_FATAL,
+	ANDROID_LOG_ERROR,    // LL_ERROR
+	ANDROID_LOG_WARN,     // LL_WARNING
+	ANDROID_LOG_WARN,     // LL_ACTION
+	//ANDROID_LOG_INFO,
+	ANDROID_LOG_DEBUG,    // LL_INFO
+	ANDROID_LOG_VERBOSE,  // LL_VERBOSE
+
+};
+#endif
+
+////
+//// Globals
+////
+
+Logger g_logger;
+
+StreamLogOutput stdout_output(std::cout);
+StreamLogOutput stderr_output(std::cerr);
+std::ostream null_stream(NULL);
+
+RawLogBuffer raw_buf;
+
+LogBuffer none_buf(g_logger, LL_NONE);
+LogBuffer error_buf(g_logger, LL_ERROR);
+LogBuffer warning_buf(g_logger, LL_WARNING);
+LogBuffer action_buf(g_logger, LL_ACTION);
+LogBuffer info_buf(g_logger, LL_INFO);
+LogBuffer verbose_buf(g_logger, LL_VERBOSE);
 
 // Connection
-std::ostream *dout_con_ptr = &dummyout;
+std::ostream *dout_con_ptr = &null_stream;
 std::ostream *derr_con_ptr = &verbosestream;
 
 // Server
@@ -44,170 +116,211 @@ std::ostream *dout_client_ptr = &infostream;
 std::ostream *derr_client_ptr = &errorstream;
 #endif
 
-#ifdef __ANDROID__
-unsigned int android_log_level_mapping[] = {
-		/* LMT_ERROR */   ANDROID_LOG_ERROR,
-		/* LMT_ACTION */  ANDROID_LOG_WARN,
-		/* LMT_INFO */    ANDROID_LOG_INFO,
-		/* LMT_VERBOSE */ ANDROID_LOG_VERBOSE
-	};
-#endif
+std::ostream rawstream(&raw_buf);
+std::ostream dstream(&none_buf);
+std::ostream errorstream(&error_buf);
+std::ostream warningstream(&warning_buf);
+std::ostream actionstream(&action_buf);
+std::ostream infostream(&info_buf);
+std::ostream verbosestream(&verbose_buf);
+
 
-std::vector<ILogOutput*> log_outputs[LMT_NUM_VALUES];
-std::map<threadid_t, std::string> log_thread_names;
-Mutex log_thread_name_mutex;
+///////////////////////////////////////////////////////////////////////////////
 
-void log_add_output(ILogOutput *out, enum LogMessageLevel lev)
+
+////
+//// Logger
+////
+
+LogLevel Logger::stringToLevel(const std::string &name)
 {
-	log_outputs[lev].push_back(out);
+	if (name == "none")
+		return LL_NONE;
+	else if (name == "error")
+		return LL_ERROR;
+	else if (name == "warning")
+		return LL_WARNING;
+	else if (name == "action")
+		return LL_ACTION;
+	else if (name == "info")
+		return LL_INFO;
+	else if (name == "verbose")
+		return LL_VERBOSE;
+	else
+		return LL_MAX;
 }
 
-void log_add_output_maxlev(ILogOutput *out, enum LogMessageLevel lev)
+void Logger::addOutput(ILogOutput *out)
 {
-	for(int i=0; i<=lev; i++)
-		log_outputs[i].push_back(out);
+	addOutputMaxLevel(out, LL_MAX);
 }
 
-void log_add_output_all_levs(ILogOutput *out)
+void Logger::addOutput(ILogOutput *out, LogLevel lev)
 {
-	for(int i=0; i<LMT_NUM_VALUES; i++)
-		log_outputs[i].push_back(out);
+	m_outputs[lev].push_back(out);
 }
 
-void log_remove_output(ILogOutput *out)
+void Logger::addOutputMaxLevel(ILogOutput *out, LogLevel lev)
 {
-	for(int i=0; i<LMT_NUM_VALUES; i++){
-		std::vector<ILogOutput*>::iterator it =
-				std::find(log_outputs[i].begin(), log_outputs[i].end(), out);
-		if(it != log_outputs[i].end())
-			log_outputs[i].erase(it);
-	}
+	for (size_t i = 0; i <= lev; i++)
+		m_outputs[i].push_back(out);
 }
 
-void log_set_lev_silence(enum LogMessageLevel lev, bool silence)
+void Logger::removeOutput(ILogOutput *out)
 {
-	MutexAutoLock lock(log_thread_name_mutex);
+	for (size_t i = 0; i < LL_MAX; i++) {
+		std::vector<ILogOutput *>::iterator it;
 
-	for (std::vector<ILogOutput *>::iterator it = log_outputs[lev].begin();
-			it != log_outputs[lev].end(); ++it) {
-		ILogOutput *out = *it;
-		out->silence = silence;
+		it = std::find(m_outputs[i].begin(), m_outputs[i].end(), out);
+		if (it != m_outputs[i].end())
+			m_outputs[i].erase(it);
 	}
 }
 
-void log_register_thread(const std::string &name)
+void Logger::setLevelSilenced(LogLevel lev, bool silenced)
 {
-	threadid_t id = get_current_thread_id();
-	MutexAutoLock lock(log_thread_name_mutex);
-
-	log_thread_names[id] = name;
+	m_silenced_levels[lev] = silenced;
 }
 
-void log_deregister_thread()
+void Logger::registerThread(const std::string &name)
 {
 	threadid_t id = get_current_thread_id();
-	MutexAutoLock lock(log_thread_name_mutex);
+	MutexAutoLock lock(m_mutex);
+	m_thread_names[id] = name;
+}
 
-	log_thread_names.erase(id);
+void Logger::deregisterThread()
+{
+	threadid_t id = get_current_thread_id();
+	MutexAutoLock lock(m_mutex);
+	m_thread_names.erase(id);
 }
 
-static std::string get_lev_string(enum LogMessageLevel lev)
+const std::string Logger::getLevelLabel(LogLevel lev)
 {
-	switch(lev){
-	case LMT_ERROR:
-		return "ERROR";
-	case LMT_ACTION:
-		return "ACTION";
-	case LMT_INFO:
-		return "INFO";
-	case LMT_VERBOSE:
-		return "VERBOSE";
-	case LMT_NUM_VALUES:
-		break;
-	}
-	return "(unknown level)";
+	static const std::string names[] = {
+		"",
+		"ERROR",
+		"WARNING",
+		"ACTION",
+		"INFO",
+		"VERBOSE",
+	};
+	assert(lev < LL_MAX && lev >= 0);
+	assert(ARRLEN(names) == LL_MAX);
+	return names[lev];
 }
 
-void log_printline(enum LogMessageLevel lev, const std::string &text)
+const std::string Logger::getThreadName()
 {
-	MutexAutoLock lock(log_thread_name_mutex);
-	std::string threadname = "(unknown thread)";
-	std::map<threadid_t, std::string>::const_iterator i;
-	i = log_thread_names.find(get_current_thread_id());
-	if(i != log_thread_names.end())
-		threadname = i->second;
-	std::string levelname = get_lev_string(lev);
-	std::ostringstream os(std::ios_base::binary);
-	os << getTimestamp() << ": " << levelname << "["<<threadname<<"]: " << text;
+	std::map<threadid_t, std::string>::const_iterator it;
 
-	for(std::vector<ILogOutput*>::iterator i = log_outputs[lev].begin();
-			i != log_outputs[lev].end(); ++i) {
-		ILogOutput *out = *i;
-		if (out->silence)
-			continue;
+	threadid_t id = get_current_thread_id();
+	it = m_thread_names.find(id);
+	if (it != m_thread_names.end())
+		return it->second;
 
-		out->printLog(os.str());
-		out->printLog(os.str(), lev);
-		out->printLog(lev, text);
-	}
+	std::ostringstream os;
+	os << "#0x" << std::hex << id;
+	return os.str();
 }
 
-class Logbuf : public std::streambuf
+void Logger::log(LogLevel lev, const std::string &text)
 {
-public:
-	Logbuf(enum LogMessageLevel lev):
-		m_lev(lev)
-	{
-	}
+	if (m_silenced_levels[lev])
+		return;
 
-	~Logbuf()
-	{
-	}
+	const std::string thread_name = getThreadName();
+	const std::string label = getLevelLabel(lev);
+	std::ostringstream os(std::ios_base::binary);
+	os << getTimestamp() << ": " << label << "[" << thread_name << "]: " << text;
 
-	int overflow(int c)
-	{
-		bufchar(c);
-		return c;
-	}
-	std::streamsize xsputn(const char *s, std::streamsize n)
-	{
-		for(int i=0; i<n; i++)
-			bufchar(s[i]);
-		return n;
-	}
+	logToSystem(lev, text);
+	logToOutputs(lev, os.str());
+}
 
-	void printbuf()
-	{
-		log_printline(m_lev, m_buf);
+void Logger::logRaw(LogLevel lev, const std::string &text)
+{
+	if (m_silenced_levels[lev])
+		return;
+
+	logToSystem(lev, text);
+	logToOutputs(lev, text);
+}
+
+void Logger::logToSystem(LogLevel lev, const std::string &text)
+{
 #ifdef __ANDROID__
-		__android_log_print(android_log_level_mapping[m_lev], PROJECT_NAME, "%s", m_buf.c_str());
+	assert(ARRLEN(level_to_android) == LL_MAX);
+	__android_log_print(level_to_android[lev],
+		PROJECT_NAME_C, "%s", text.c_str());
 #endif
-	}
+}
+
+void Logger::logToOutputs(LogLevel lev, const std::string &text)
+{
+	MutexAutoLock lock(m_mutex);
+	for (size_t i = 0; i != m_outputs[lev].size(); i++)
+		m_outputs[lev][i]->log(text);
+}
+
 
-	void bufchar(char c)
-	{
-		if(c == '\n' || c == '\r'){
-			if(m_buf != "")
-				printbuf();
-			m_buf = "";
-			return;
-		}
-		m_buf += c;
+////
+//// *LogOutput methods
+////
+
+void FileLogOutput::open(const std::string &filename)
+{
+	stream.open(filename.c_str(), std::ios::app | std::ios::ate);
+	if (!stream.good())
+		throw FileNotGoodException("Failed to open log file " +
+			filename + ": " + strerror(errno));
+	stream << "\n\n"
+		   "-------------" << std::endl
+		<< "  Separator" << std::endl
+		<< "-------------\n" << std::endl;
+}
+
+
+
+////
+//// *Buffer methods
+////
+
+int StringBuffer::overflow(int c)
+{
+	push_back(c);
+	return c;
+}
+
+
+std::streamsize StringBuffer::xsputn(const char *s, std::streamsize n)
+{
+	for (int i = 0; i < n; ++i)
+		push_back(s[i]);
+	return n;
+}
+
+void StringBuffer::push_back(char c)
+{
+	if (c == '\n' || c == '\r') {
+		if (!buffer.empty())
+			flush(buffer);
+		buffer.clear();
+	} else {
+		buffer.push_back(c);
 	}
+}
 
-private:
-	enum LogMessageLevel m_lev;
-	std::string m_buf;
-};
 
-Logbuf errorbuf(LMT_ERROR);
-Logbuf actionbuf(LMT_ACTION);
-Logbuf infobuf(LMT_INFO);
-Logbuf verbosebuf(LMT_VERBOSE);
-std::ostream errorstream(&errorbuf);
-std::ostream actionstream(&actionbuf);
-std::ostream infostream(&infobuf);
-std::ostream verbosestream(&verbosebuf);
 
-bool log_trace_level_enabled = false;
 
+void LogBuffer::flush(const std::string &buffer)
+{
+	logger.log(level, buffer);
+}
+
+void RawLogBuffer::flush(const std::string &buffer)
+{
+	g_logger.logRaw(LL_NONE, buffer);
+}
diff --git a/src/log.h b/src/log.h
index bd223927a..0e63041cc 100644
--- a/src/log.h
+++ b/src/log.h
@@ -20,83 +20,177 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #ifndef LOG_HEADER
 #define LOG_HEADER
 
+#include <map>
+#include <queue>
 #include <string>
+#include <fstream>
+#include "threads.h"
+
+class ILogOutput;
+
+enum LogLevel {
+	LL_NONE, // Special level that is always printed
+	LL_ERROR,
+	LL_WARNING,
+	LL_ACTION,  // In-game actions
+	LL_INFO,
+	LL_VERBOSE,
+	LL_MAX,
+};
 
-/*
-	Use this for logging everything.
+class Logger {
+public:
+	void addOutput(ILogOutput *out);
+	void addOutput(ILogOutput *out, LogLevel lev);
+	void addOutputMaxLevel(ILogOutput *out, LogLevel lev);
+	void removeOutput(ILogOutput *out);
+	void setLevelSilenced(LogLevel lev, bool silenced);
 
-	If you need to explicitly print something, use dstream or cout or cerr.
-*/
+	void registerThread(const std::string &name);
+	void deregisterThread();
+
+	void log(LogLevel lev, const std::string &text);
+	// Logs without a prefix
+	void logRaw(LogLevel lev, const std::string &text);
+
+	void setTraceEnabled(bool enable) { m_trace_enabled = enable; }
+	bool getTraceEnabled() { return m_trace_enabled; }
+
+	static LogLevel stringToLevel(const std::string &name);
+
+private:
+	void logToSystem(LogLevel, const std::string &text);
+	void logToOutputs(LogLevel, const std::string &text);
+
+	const std::string getLevelLabel(LogLevel lev);
+	const std::string getThreadName();
+
+	std::vector<ILogOutput *> m_outputs[LL_MAX];
 
-enum LogMessageLevel {
-	LMT_ERROR, /* Something failed ("invalid map data on disk, block (2,2,1)") */
-	LMT_ACTION, /* In-game actions ("celeron55 placed block at (12,4,-5)") */
-	LMT_INFO, /* More deep info ("saving map on disk (only_modified=true)") */
-	LMT_VERBOSE, /* Flood-style ("loaded block (2,2,2) from disk") */
-	LMT_NUM_VALUES,
+	// Should implement atomic loads and stores (even though it's only
+	// written to when one thread has access currently).
+	// Works on all known architectures (x86, ARM, MIPS).
+	volatile bool m_silenced_levels[LL_MAX];
+	std::map<threadid_t, std::string> m_thread_names;
+	mutable Mutex m_mutex;
+	bool m_trace_enabled;
 };
 
-class ILogOutput
-{
+class ILogOutput {
 public:
-	ILogOutput() :
-		silence(false)
-	{}
-
-	/* line: Full line with timestamp, level and thread */
-	virtual void printLog(const std::string &line){};
-	/* line: Full line with timestamp, level and thread */
-	virtual void printLog(const std::string &line, enum LogMessageLevel lev){};
-	/* line: Only actual printed text */
-	virtual void printLog(enum LogMessageLevel lev, const std::string &line){};
-
-	bool silence;
+	virtual void log(const std::string &line) = 0;
 };
 
-void log_add_output(ILogOutput *out, enum LogMessageLevel lev);
-void log_add_output_maxlev(ILogOutput *out, enum LogMessageLevel lev);
-void log_add_output_all_levs(ILogOutput *out);
-void log_remove_output(ILogOutput *out);
-void log_set_lev_silence(enum LogMessageLevel lev, bool silence);
+class StreamLogOutput : public ILogOutput {
+public:
+	StreamLogOutput(std::ostream &stream) :
+		stream(stream)
+	{
+	}
+
+	void log(const std::string &line)
+	{
+		stream << line << std::endl;
+	}
+
+private:
+	std::ostream &stream;
+};
 
-void log_register_thread(const std::string &name);
-void log_deregister_thread();
+class FileLogOutput : public ILogOutput {
+public:
+	void open(const std::string &filename);
 
-void log_printline(enum LogMessageLevel lev, const std::string &text);
+	void log(const std::string &line)
+	{
+		stream << line << std::endl;
+	}
 
-#define LOGLINEF(lev, ...)\
-{\
-	char buf[10000];\
-	snprintf(buf, 10000, __VA_ARGS__);\
-	log_printline(lev, buf);\
-}
+private:
+	std::ofstream stream;
+};
 
-extern std::ostream errorstream;
-extern std::ostream actionstream;
-extern std::ostream infostream;
-extern std::ostream verbosestream;
+class LogOutputBuffer : public ILogOutput {
+public:
+	LogOutputBuffer(Logger &logger, LogLevel lev) :
+		logger(logger)
+	{
+		logger.addOutput(this, lev);
+	}
+
+	~LogOutputBuffer()
+	{
+		logger.removeOutput(this);
+	}
+
+	virtual void log(const std::string &line)
+	{
+		buffer.push(line);
+	}
+
+	bool empty()
+	{
+		return buffer.empty();
+	}
+
+	std::string get()
+	{
+		if (empty())
+			return "";
+		std::string s = buffer.front();
+		buffer.pop();
+		return s;
+	}
+
+private:
+	std::queue<std::string> buffer;
+	Logger &logger;
+};
 
-extern bool log_trace_level_enabled;
 
-#define TRACESTREAM(x){ if(log_trace_level_enabled) verbosestream x; }
-#define TRACEDO(x){ if(log_trace_level_enabled){ x ;} }
+extern StreamLogOutput stdout_output;
+extern StreamLogOutput stderr_output;
+extern std::ostream null_stream;
 
 extern std::ostream *dout_con_ptr;
 extern std::ostream *derr_con_ptr;
 extern std::ostream *dout_server_ptr;
 extern std::ostream *derr_server_ptr;
+
+#ifndef SERVER
+extern std::ostream *dout_client_ptr;
+extern std::ostream *derr_client_ptr;
+#endif
+
+extern Logger g_logger;
+
+// Writes directly to all LL_NONE log outputs for g_logger with no prefix.
+extern std::ostream rawstream;
+
+extern std::ostream errorstream;
+extern std::ostream warningstream;
+extern std::ostream actionstream;
+extern std::ostream infostream;
+extern std::ostream verbosestream;
+extern std::ostream dstream;
+
+#define TRACEDO(x) do {               \
+	if (g_logger.getTraceEnabled()) { \
+		x;                            \
+	}                                 \
+} while (0)
+
+#define TRACESTREAM(x) TRACEDO(verbosestream x)
+
 #define dout_con (*dout_con_ptr)
 #define derr_con (*derr_con_ptr)
 #define dout_server (*dout_server_ptr)
 #define derr_server (*derr_server_ptr)
 
 #ifndef SERVER
-extern std::ostream *dout_client_ptr;
-extern std::ostream *derr_client_ptr;
-#define dout_client (*dout_client_ptr)
-#define derr_client (*derr_client_ptr)
-
+	#define dout_client (*dout_client_ptr)
+	#define derr_client (*derr_client_ptr)
 #endif
 
-#endif
 
+#endif
diff --git a/src/logoutputbuffer.h b/src/logoutputbuffer.h
deleted file mode 100644
index 69f06c444..000000000
--- a/src/logoutputbuffer.h
+++ /dev/null
@@ -1,58 +0,0 @@
-/*
-Minetest
-Copyright (C) 2013 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 Lesser General Public License as published by
-the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
-
-You should have received a copy of the GNU Lesser 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 LOGOUTPUTBUFFER_HEADER
-#define LOGOUTPUTBUFFER_HEADER
-
-#include "log.h"
-#include <queue>
-
-class LogOutputBuffer : public ILogOutput
-{
-public:
-	LogOutputBuffer(LogMessageLevel maxlev)
-	{
-		log_add_output(this, maxlev);
-	}
-	~LogOutputBuffer()
-	{
-		log_remove_output(this);
-	}
-	virtual void printLog(const std::string &line)
-	{
-		m_buf.push(line);
-	}
-	std::string get()
-	{
-		if(empty())
-			return "";
-		std::string s = m_buf.front();
-		m_buf.pop();
-		return s;
-	}
-	bool empty()
-	{
-		return m_buf.empty();
-	}
-private:
-	std::queue<std::string> m_buf;
-};
-
-#endif
-
diff --git a/src/main.cpp b/src/main.cpp
index dece27428..cc8b4bcaa 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -80,10 +80,10 @@ static void list_game_ids();
 static void list_worlds();
 static void setup_log_params(const Settings &cmd_args);
 static bool create_userdata_path();
-static bool init_common(int *log_level, const Settings &cmd_args, int argc, char *argv[]);
+static bool init_common(const Settings &cmd_args, int argc, char *argv[]);
 static void startup_message();
 static bool read_config_file(const Settings &cmd_args);
-static void init_debug_streams(int *log_level, const Settings &cmd_args);
+static void init_log_streams(const Settings &cmd_args);
 
 static bool game_configure(GameParams *game_params, const Settings &cmd_args);
 static void game_configure_port(GameParams *game_params, const Settings &cmd_args);
@@ -122,25 +122,7 @@ u32 getTime(TimePrecision prec)
 
 #endif
 
-class StderrLogOutput: public ILogOutput
-{
-public:
-	/* line: Full line with timestamp, level and thread */
-	void printLog(const std::string &line)
-	{
-		std::cerr << line << std::endl;
-	}
-} main_stderr_log_out;
-
-class DstreamNoStderrLogOutput: public ILogOutput
-{
-public:
-	/* line: Full line with timestamp, level and thread */
-	void printLog(const std::string &line)
-	{
-		dstream_no_stderr << line << std::endl;
-	}
-} main_dstream_no_stderr_log_out;
+FileLogOutput file_log_output;
 
 static OptionList allowed_options;
 
@@ -150,10 +132,8 @@ int main(int argc, char *argv[])
 
 	debug_set_exception_handler();
 
-	log_add_output_maxlev(&main_stderr_log_out, LMT_ACTION);
-	log_add_output_all_levs(&main_dstream_no_stderr_log_out);
-
-	log_register_thread("Main");
+	g_logger.registerThread("Main");
+	g_logger.addOutputMaxLevel(&stderr_output, LL_ACTION);
 
 	Settings cmd_args;
 	bool cmd_args_ok = get_cmdline_opts(argc, argv, &cmd_args);
@@ -180,8 +160,7 @@ int main(int argc, char *argv[])
 	}
 
 	// Initialize debug stacks
-	debug_stacks_init();
-	DSTACK(__FUNCTION_NAME);
+	DSTACK(FUNCTION_NAME);
 
 	// Debug handler
 	BEGIN_DEBUG_EXCEPTION_HANDLER
@@ -198,8 +177,7 @@ int main(int argc, char *argv[])
 		return 0;
 	}
 
-	GameParams game_params;
-	if (!init_common(&game_params.log_level, cmd_args, argc, argv))
+	if (!init_common(cmd_args, argc, argv))
 		return 1;
 
 #ifndef __ANDROID__
@@ -210,6 +188,7 @@ int main(int argc, char *argv[])
 	}
 #endif
 
+	GameParams game_params;
 #ifdef SERVER
 	game_params.is_dedicated_server = true;
 #else
@@ -219,7 +198,7 @@ int main(int argc, char *argv[])
 	if (!game_configure(&game_params, cmd_args))
 		return 1;
 
-	sanity_check(game_params.world_path != "");
+	sanity_check(!game_params.world_path.empty());
 
 	infostream << "Using commanded world path ["
 	           << game_params.world_path << "]" << std::endl;
@@ -247,7 +226,7 @@ int main(int argc, char *argv[])
 	// Stop httpfetch thread (if started)
 	httpfetch_cleanup();
 
-	END_DEBUG_EXCEPTION_HANDLER(errorstream)
+	END_DEBUG_EXCEPTION_HANDLER(errorstream);
 
 	return retval;
 }
@@ -403,26 +382,26 @@ static void setup_log_params(const Settings &cmd_args)
 {
 	// Quiet mode, print errors only
 	if (cmd_args.getFlag("quiet")) {
-		log_remove_output(&main_stderr_log_out);
-		log_add_output_maxlev(&main_stderr_log_out, LMT_ERROR);
+		g_logger.removeOutput(&stderr_output);
+		g_logger.addOutputMaxLevel(&stderr_output, LL_ERROR);
 	}
 
 	// If trace is enabled, enable logging of certain things
 	if (cmd_args.getFlag("trace")) {
 		dstream << _("Enabling trace level debug output") << std::endl;
-		log_trace_level_enabled = true;
-		dout_con_ptr = &verbosestream; // this is somewhat old crap
-		socket_enable_debug_output = true; // socket doesn't use log.h
+		g_logger.setTraceEnabled(true);
+		dout_con_ptr = &verbosestream; // This is somewhat old
+		socket_enable_debug_output = true; // Sockets doesn't use log.h
 	}
 
 	// In certain cases, output info level on stderr
 	if (cmd_args.getFlag("info") || cmd_args.getFlag("verbose") ||
 			cmd_args.getFlag("trace") || cmd_args.getFlag("speedtests"))
-		log_add_output(&main_stderr_log_out, LMT_INFO);
+		g_logger.addOutput(&stderr_output, LL_INFO);
 
 	// In certain cases, output verbose level on stderr
 	if (cmd_args.getFlag("verbose") || cmd_args.getFlag("trace"))
-		log_add_output(&main_stderr_log_out, LMT_VERBOSE);
+		g_logger.addOutput(&stderr_output, LL_VERBOSE);
 }
 
 static bool create_userdata_path()
@@ -450,7 +429,7 @@ static bool create_userdata_path()
 	return success;
 }
 
-static bool init_common(int *log_level, const Settings &cmd_args, int argc, char *argv[])
+static bool init_common(const Settings &cmd_args, int argc, char *argv[])
 {
 	startup_message();
 	set_default_settings(g_settings);
@@ -462,7 +441,7 @@ static bool init_common(int *log_level, const Settings &cmd_args, int argc, char
 	if (!read_config_file(cmd_args))
 		return false;
 
-	init_debug_streams(log_level, cmd_args);
+	init_log_streams(cmd_args);
 
 	// Initialize random seed
 	srand(time(0));
@@ -533,38 +512,47 @@ static bool read_config_file(const Settings &cmd_args)
 	return true;
 }
 
-static void init_debug_streams(int *log_level, const Settings &cmd_args)
+static void init_log_streams(const Settings &cmd_args)
 {
 #if RUN_IN_PLACE
-	std::string logfile = DEBUGFILE;
+	std::string log_filename = DEBUGFILE;
 #else
-	std::string logfile = porting::path_user + DIR_DELIM + DEBUGFILE;
+	std::string log_filename = porting::path_user + DIR_DELIM + DEBUGFILE;
 #endif
 	if (cmd_args.exists("logfile"))
-		logfile = cmd_args.get("logfile");
-
-	log_remove_output(&main_dstream_no_stderr_log_out);
-	*log_level = g_settings->getS32("debug_log_level");
-
-	if (*log_level == 0) //no logging
-		logfile = "";
-	if (*log_level < 0) {
-		dstream << "WARNING: Supplied debug_log_level < 0; Using 0" << std::endl;
-		*log_level = 0;
-	} else if (*log_level > LMT_NUM_VALUES) {
-		dstream << "WARNING: Supplied debug_log_level > " << LMT_NUM_VALUES
-		        << "; Using " << LMT_NUM_VALUES << std::endl;
-		*log_level = LMT_NUM_VALUES;
+		log_filename = cmd_args.get("logfile");
+
+	g_logger.removeOutput(&file_log_output);
+	std::string conf_loglev = g_settings->get("debug_log_level");
+
+	// Old integer format
+	if (std::isdigit(conf_loglev[0])) {
+		warningstream << "Deprecated use of debug_log_level with an "
+			"integer value; please update your configuration." << std::endl;
+		static const char *lev_name[] =
+			{"", "error", "action", "info", "verbose"};
+		int lev_i = atoi(conf_loglev.c_str());
+		if (lev_i < 0 || lev_i >= (int)ARRLEN(lev_name)) {
+			warningstream << "Supplied invalid debug_log_level!"
+				"  Assuming action level." << std::endl;
+			lev_i = 2;
+		}
+		conf_loglev = lev_name[lev_i];
 	}
 
-	log_add_output_maxlev(&main_dstream_no_stderr_log_out,
-			(LogMessageLevel)(*log_level - 1));
+	if (conf_loglev.empty())  // No logging
+		return;
 
-	debugstreams_init(false, logfile == "" ? NULL : logfile.c_str());
+	LogLevel log_level = Logger::stringToLevel(conf_loglev);
+	if (log_level == LL_MAX) {
+		warningstream << "Supplied unrecognized debug_log_level; "
+			"using maximum." << std::endl;
+	}
 
-	infostream << "logfile = " << logfile << std::endl;
+	verbosestream << "log_filename = " << log_filename << std::endl;
 
-	atexit(debugstreams_deinit);
+	file_log_output.open(log_filename.c_str());
+	g_logger.addOutputMaxLevel(&file_log_output, log_level);
 }
 
 static bool game_configure(GameParams *game_params, const Settings &cmd_args)
@@ -678,10 +666,10 @@ static bool auto_select_world(GameParams *game_params)
 		        << world_path << "]" << std::endl;
 	// If there are multiple worlds, list them
 	} else if (worldspecs.size() > 1 && game_params->is_dedicated_server) {
-		dstream << _("Multiple worlds are available.") << std::endl;
-		dstream << _("Please select one using --worldname <name>"
+		std::cerr << _("Multiple worlds are available.") << std::endl;
+		std::cerr << _("Please select one using --worldname <name>"
 				" or --world <path>") << std::endl;
-		print_worldspecs(worldspecs, dstream);
+		print_worldspecs(worldspecs, std::cerr);
 		return false;
 	// If there are no worlds, automatically create a new one
 	} else {
@@ -774,7 +762,7 @@ static bool determine_subgame(GameParams *game_params)
 		if (game_params->game_spec.isValid()) {
 			gamespec = game_params->game_spec;
 			if (game_params->game_spec.id != world_gameid) {
-				errorstream << "WARNING: Using commanded gameid ["
+				warningstream << "Using commanded gameid ["
 				            << gamespec.id << "]" << " instead of world gameid ["
 				            << world_gameid << "]" << std::endl;
 			}
@@ -835,9 +823,8 @@ static bool run_dedicated_server(const GameParams &game_params, const Settings &
 		return migrate_database(game_params, cmd_args);
 
 	// Create server
-	Server server(game_params.world_path,
-			game_params.game_spec, false, bind_addr.isIPv6());
-
+	Server server(game_params.world_path, game_params.game_spec, false,
+		bind_addr.isIPv6());
 	server.start(bind_addr);
 
 	// Run server
diff --git a/src/minimap.cpp b/src/minimap.cpp
index 7eb7247ca..a6eff0680 100644
--- a/src/minimap.cpp
+++ b/src/minimap.cpp
@@ -18,8 +18,6 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 */
 
 #include "minimap.h"
-#include <math.h>
-#include "logoutputbuffer.h"
 #include "threading/mutex_auto_lock.h"
 #include "threading/semaphore.h"
 #include "clientmap.h"
@@ -28,6 +26,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "porting.h"
 #include "util/numeric.h"
 #include "util/string.h"
+#include <math.h>
 
 
 ////
diff --git a/src/script/lua_api/l_util.cpp b/src/script/lua_api/l_util.cpp
index 4b8b6d351..a4f01af07 100644
--- a/src/script/lua_api/l_util.cpp
+++ b/src/script/lua_api/l_util.cpp
@@ -26,7 +26,6 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "json/json.h"
 #include "cpp_api/s_security.h"
 #include "areastore.h"
-#include "debug.h"
 #include "porting.h"
 #include "log.h"
 #include "tool.h"
@@ -35,35 +34,6 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "util/auth.h"
 #include <algorithm>
 
-// debug(...)
-// Writes a line to dstream
-int ModApiUtil::l_debug(lua_State *L)
-{
-	NO_MAP_LOCK_REQUIRED;
-	// Handle multiple parameters to behave like standard lua print()
-	int n = lua_gettop(L);
-	lua_getglobal(L, "tostring");
-	for (int i = 1; i <= n; i++) {
-		/*
-			Call tostring(i-th argument).
-			This is what print() does, and it behaves a bit
-			differently from directly calling lua_tostring.
-		*/
-		lua_pushvalue(L, -1);  /* function to be called */
-		lua_pushvalue(L, i);   /* value to print */
-		lua_call(L, 1, 1);
-		size_t len;
-		const char *s = lua_tolstring(L, -1, &len);
-		if (i > 1)
-			dstream << "\t";
-		if (s)
-			dstream << std::string(s, len);
-		lua_pop(L, 1);
-	}
-	dstream << std::endl;
-	return 0;
-}
-
 // log([level,] text)
 // Writes a line to the logger.
 // The one-argument version logs to infostream.
@@ -72,26 +42,24 @@ int ModApiUtil::l_log(lua_State *L)
 {
 	NO_MAP_LOCK_REQUIRED;
 	std::string text;
-	LogMessageLevel level = LMT_INFO;
+	LogLevel level = LL_NONE;
 	if (lua_isnone(L, 2)) {
-		text = lua_tostring(L, 1);
-	}
-	else {
-		std::string levelname = luaL_checkstring(L, 1);
+		text = luaL_checkstring(L, 1);
+	} else {
+		std::string name = luaL_checkstring(L, 1);
 		text = luaL_checkstring(L, 2);
-		if(levelname == "error")
-			level = LMT_ERROR;
-		else if(levelname == "action")
-			level = LMT_ACTION;
-		else if(levelname == "verbose")
-			level = LMT_VERBOSE;
-		else if (levelname == "deprecated") {
-			log_deprecated(L,text);
+		if (name == "deprecated") {
+			log_deprecated(L, text);
 			return 0;
 		}
-
+		level = Logger::stringToLevel(name);
+		if (level == LL_MAX) {
+			warningstream << "Tried to log at unknown level '" << name
+				<< "'.  Defaulting to \"none\"." << std::endl;
+			level = LL_NONE;
+		}
 	}
-	log_printline(level, text);
+	g_logger.log(level, text);
 	return 0;
 }
 
@@ -390,7 +358,6 @@ int ModApiUtil::l_request_insecure_environment(lua_State *L)
 
 void ModApiUtil::Initialize(lua_State *L, int top)
 {
-	API_FCT(debug);
 	API_FCT(log);
 
 	API_FCT(setting_set);
@@ -422,7 +389,6 @@ void ModApiUtil::Initialize(lua_State *L, int top)
 
 void ModApiUtil::InitializeAsync(AsyncEngine& engine)
 {
-	ASYNC_API_FCT(debug);
 	ASYNC_API_FCT(log);
 
 	//ASYNC_API_FCT(setting_set);
diff --git a/src/script/lua_api/l_util.h b/src/script/lua_api/l_util.h
index e75aa28cb..4b55b1966 100644
--- a/src/script/lua_api/l_util.h
+++ b/src/script/lua_api/l_util.h
@@ -35,10 +35,6 @@ private:
 		GUIEngine instance should be in here.
 	*/
 
-	// debug(text)
-	// Writes a line to dstream
-	static int l_debug(lua_State *L);
-
 	// log([level,] text)
 	// Writes a line to the logger.
 	// The one-argument version logs to infostream.
diff --git a/src/threading/thread.cpp b/src/threading/thread.cpp
index 73a951194..1f9b54795 100644
--- a/src/threading/thread.cpp
+++ b/src/threading/thread.cpp
@@ -222,11 +222,11 @@ void *Thread::theThread(void *param)
 	th->running = true;
 
 	th->setName();
-	log_register_thread(th->name);
+	g_logger.registerThread(th->name);
 
 	th->retval = th->run();
 
-	log_deregister_thread();
+	g_logger.deregisterThread();
 
 	th->running = false;
 #if __cplusplus < 201103L
diff --git a/src/unittest/test.cpp b/src/unittest/test.cpp
index d0ffb423f..de4711802 100644
--- a/src/unittest/test.cpp
+++ b/src/unittest/test.cpp
@@ -19,7 +19,6 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #include "test.h"
 
-#include "debug.h"
 #include "log.h"
 #include "nodedef.h"
 #include "itemdef.h"
@@ -223,7 +222,7 @@ void run_tests()
 	u32 t1 = porting::getTime(PRECISION_MILLI);
 	TestGameDef gamedef;
 
-	log_set_lev_silence(LMT_ERROR, true);
+	g_logger.setLevelSilenced(LL_ERROR, true);
 
 	u32 num_modules_failed     = 0;
 	u32 num_total_tests_failed = 0;
@@ -239,11 +238,11 @@ void run_tests()
 
 	u32 tdiff = porting::getTime(PRECISION_MILLI) - t1;
 
-	log_set_lev_silence(LMT_ERROR, false);
+	g_logger.setLevelSilenced(LL_ERROR, false);
 
 	const char *overall_status = (num_modules_failed == 0) ? "PASSED" : "FAILED";
 
-	dstream
+	rawstream
 		<< "++++++++++++++++++++++++++++++++++++++++"
 		<< "++++++++++++++++++++++++++++++++++++++++" << std::endl
 		<< "Unit Test Results: " << overall_status << std::endl
@@ -264,14 +263,14 @@ void run_tests()
 
 bool TestBase::testModule(IGameDef *gamedef)
 {
-	dstream << "======== Testing module " << getName() << std::endl;
+	rawstream << "======== Testing module " << getName() << std::endl;
 	u32 t1 = porting::getTime(PRECISION_MILLI);
 
 
 	runTests(gamedef);
 
 	u32 tdiff = porting::getTime(PRECISION_MILLI) - t1;
-	dstream << "======== Module " << getName() << " "
+	rawstream << "======== Module " << getName() << " "
 		<< (num_tests_failed ? "failed" : "passed") << " (" << num_tests_failed
 		<< " failures / " << num_tests_run << " tests) - " << tdiff
 		<< "ms" << std::endl;
diff --git a/src/unittest/test.h b/src/unittest/test.h
index 47a441e02..f6c4711a5 100644
--- a/src/unittest/test.h
+++ b/src/unittest/test.h
@@ -32,60 +32,61 @@ class TestFailedException : public std::exception {
 };
 
 // Runs a unit test and reports results
-#define TEST(fxn, ...) do {                                                 \
-	u32 t1 = porting::getTime(PRECISION_MILLI);                             \
-	try {                                                                   \
-		fxn(__VA_ARGS__);                                                   \
-		dstream << "[PASS] ";                                               \
-	} catch (TestFailedException &e) {                                      \
-		dstream << "[FAIL] ";                                               \
-		num_tests_failed++;                                                 \
-	} catch (std::exception &e) {                                           \
-		dstream << "Caught unhandled exception: " << e.what() << std::endl; \
-		dstream << "[FAIL] ";                                               \
-		num_tests_failed++;                                                 \
-	}                                                                       \
-	num_tests_run++;                                                        \
-	u32 tdiff = porting::getTime(PRECISION_MILLI) - t1;                     \
-	dstream << #fxn << " - " << tdiff << "ms" << std::endl;                 \
+#define TEST(fxn, ...) do {                                                   \
+	u32 t1 = porting::getTime(PRECISION_MILLI);                               \
+	try {                                                                     \
+		fxn(__VA_ARGS__);                                                     \
+		rawstream << "[PASS] ";                                               \
+	} catch (TestFailedException &e) {                                        \
+		rawstream << "[FAIL] ";                                               \
+		num_tests_failed++;                                                   \
+	} catch (std::exception &e) {                                             \
+		rawstream << "Caught unhandled exception: " << e.what() << std::endl; \
+		rawstream << "[FAIL] ";                                               \
+		num_tests_failed++;                                                   \
+	}                                                                         \
+	num_tests_run++;                                                          \
+	u32 tdiff = porting::getTime(PRECISION_MILLI) - t1;                       \
+	rawstream << #fxn << " - " << tdiff << "ms" << std::endl;                 \
 } while (0)
 
 // Asserts the specified condition is true, or fails the current unit test
-#define UASSERT(x) do {                                       \
-	if (!(x)) {                                               \
-		dstream << "Test assertion failed: " #x << std::endl  \
-			<< "    at " << fs::GetFilenameFromPath(__FILE__) \
-			<< ":" << __LINE__ << std::endl;                  \
-		throw TestFailedException();                          \
-	}                                                         \
+#define UASSERT(x) do {                                         \
+	if (!(x)) {                                                 \
+		rawstream << "Test assertion failed: " #x << std::endl  \
+			<< "    at " << fs::GetFilenameFromPath(__FILE__)   \
+			<< ":" << __LINE__ << std::endl;                    \
+		throw TestFailedException();                            \
+	}                                                           \
 } while (0)
 
 // Asserts the specified condition is true, or fails the current unit test
 // and prints the format specifier fmt
-#define UTEST(x, fmt, ...) do {                                        \
-	if (!(x)) {                                                        \
-		char utest_buf[1024];                                          \
-		snprintf(utest_buf, sizeof(utest_buf), fmt, __VA_ARGS__);      \
-		dstream << "Test assertion failed: " << utest_buf << std::endl \
-			<< "    at " << fs::GetFilenameFromPath(__FILE__)          \
-			<< ":" << __LINE__ << std::endl;                           \
-		throw TestFailedException();                                   \
-	}                                                                  \
+#define UTEST(x, fmt, ...) do {                                          \
+	if (!(x)) {                                                          \
+		char utest_buf[1024];                                            \
+		snprintf(utest_buf, sizeof(utest_buf), fmt, __VA_ARGS__);        \
+		rawstream << "Test assertion failed: " << utest_buf << std::endl \
+			<< "    at " << fs::GetFilenameFromPath(__FILE__)            \
+			<< ":" << __LINE__ << std::endl;                             \
+		throw TestFailedException();                                     \
+	}                                                                    \
 } while (0)
 
 // Asserts the comparison specified by CMP is true, or fails the current unit test
-#define UASSERTCMP(T, CMP, actual, expected) do {                             \
-	T a = (actual);                                                           \
-	T e = (expected);                                                         \
-	if (!(a CMP e)) {                                                         \
-		dstream << "Test assertion failed: " << #actual << " " << #CMP << " " \
-			<< #expected << std::endl                                         \
-			<< "    at " << fs::GetFilenameFromPath(__FILE__) << ":"          \
-			<< __LINE__ << std::endl                                          \
-			<< "    actual:   " << a << std::endl << "    expected: "         \
-			<< e << std::endl;                                                \
-		throw TestFailedException();                                          \
-	}                                                                         \
+#define UASSERTCMP(T, CMP, actual, expected) do {                         \
+	T a = (actual);                                                       \
+	T e = (expected);                                                     \
+	if (!(a CMP e)) {                                                     \
+		rawstream                                                         \
+			<< "Test assertion failed: " << #actual << " " << #CMP << " " \
+			<< #expected << std::endl                                     \
+			<< "    at " << fs::GetFilenameFromPath(__FILE__) << ":"      \
+			<< __LINE__ << std::endl                                      \
+			<< "    actual:   " << a << std::endl << "    expected: "     \
+			<< e << std::endl;                                            \
+		throw TestFailedException();                                      \
+	}                                                                     \
 } while (0)
 
 #define UASSERTEQ(T, actual, expected) UASSERTCMP(T, ==, actual, expected)