Schematic: Properly deal with before/after node resolving and document (#11011)

This fixes an out-of-bounds index access when the node resolver was already applied to the schematic (i.e. biome decoration).
Also improves the handling of the two cases: prior node resolving (m_nodenames), and after node resolving (manual lookup)

7 files changed, 153 insertions, 86 deletions

diff --git a/src/mapgen/mg_schematic.cpp b/src/mapgen/mg_schematic.cpp
index e70e97e48..653bad4fe 100644
--- a/src/mapgen/mg_schematic.cpp
+++ b/src/mapgen/mg_schematic.cpp
@@ -76,10 +76,6 @@ void SchematicManager::clear()
 ///////////////////////////////////////////////////////////////////////////////
 
 
-Schematic::Schematic()
-= default;
-
-
 Schematic::~Schematic()
 {
 	delete []schemdata;
@@ -108,13 +104,19 @@ ObjDef *Schematic::clone() const
 
 void Schematic::resolveNodeNames()
 {
+	c_nodes.clear();
 	getIdsFromNrBacklog(&c_nodes, true, CONTENT_AIR);
 
 	size_t bufsize = size.X * size.Y * size.Z;
 	for (size_t i = 0; i != bufsize; i++) {
 		content_t c_original = schemdata[i].getContent();
-		content_t c_new = c_nodes[c_original];
-		schemdata[i].setContent(c_new);
+		if (c_original >= c_nodes.size()) {
+			errorstream << "Corrupt schematic. name=\"" << name
+				<< "\" at index " << i << std::endl;
+			c_original = 0;
+		}
+		// Unfold condensed ID layout to content_t
+		schemdata[i].setContent(c_nodes[c_original]);
 	}
 }
 
@@ -279,8 +281,7 @@ void Schematic::placeOnMap(ServerMap *map, v3s16 p, u32 flags,
 }
 
 
-bool Schematic::deserializeFromMts(std::istream *is,
-	std::vector<std::string> *names)
+bool Schematic::deserializeFromMts(std::istream *is)
 {
 	std::istream &ss = *is;
 	content_t cignore = CONTENT_IGNORE;
@@ -312,6 +313,8 @@ bool Schematic::deserializeFromMts(std::istream *is,
 		slice_probs[y] = (version >= 3) ? readU8(ss) : MTSCHEM_PROB_ALWAYS_OLD;
 
 	//// Read node names
+	NodeResolver::reset();
+
 	u16 nidmapcount = readU16(ss);
 	for (int i = 0; i != nidmapcount; i++) {
 		std::string name = deSerializeString16(ss);
@@ -324,9 +327,12 @@ bool Schematic::deserializeFromMts(std::istream *is,
 			have_cignore = true;
 		}
 
-		names->push_back(name);
+		m_nodenames.push_back(name);
 	}
 
+	// Prepare for node resolver
+	m_nnlistsizes.push_back(m_nodenames.size());
+
 	//// Read node data
 	size_t nodecount = size.X * size.Y * size.Z;
 
@@ -358,9 +364,11 @@ bool Schematic::deserializeFromMts(std::istream *is,
 }
 
 
-bool Schematic::serializeToMts(std::ostream *os,
-	const std::vector<std::string> &names) const
+bool Schematic::serializeToMts(std::ostream *os) const
 {
+	// Nodes must not be resolved (-> condensed)
+	// checking here is not possible because "schemdata" might be temporary.
+
 	std::ostream &ss = *os;
 
 	writeU32(ss, MTSCHEM_FILE_SIGNATURE);         // signature
@@ -370,9 +378,10 @@ bool Schematic::serializeToMts(std::ostream *os,
 	for (int y = 0; y != size.Y; y++)             // Y slice probabilities
 		writeU8(ss, slice_probs[y]);
 
-	writeU16(ss, names.size()); // name count
-	for (size_t i = 0; i != names.size(); i++)
-		ss << serializeString16(names[i]); // node names
+	writeU16(ss, m_nodenames.size()); // name count
+	for (size_t i = 0; i != m_nodenames.size(); i++) {
+		ss << serializeString16(m_nodenames[i]); // node names
+	}
 
 	// compressed bulk node data
 	MapNode::serializeBulk(ss, SER_FMT_VER_HIGHEST_WRITE,
@@ -382,8 +391,7 @@ bool Schematic::serializeToMts(std::ostream *os,
 }
 
 
-bool Schematic::serializeToLua(std::ostream *os,
-	const std::vector<std::string> &names, bool use_comments,
+bool Schematic::serializeToLua(std::ostream *os, bool use_comments,
 	u32 indent_spaces) const
 {
 	std::ostream &ss = *os;
@@ -392,6 +400,9 @@ bool Schematic::serializeToLua(std::ostream *os,
 	if (indent_spaces > 0)
 		indent.assign(indent_spaces, ' ');
 
+	bool resolve_done = isResolveDone();
+	FATAL_ERROR_IF(resolve_done && !m_ndef, "serializeToLua: NodeDefManager is required");
+
 	//// Write header
 	{
 		ss << "schematic = {" << std::endl;
@@ -436,9 +447,22 @@ bool Schematic::serializeToLua(std::ostream *os,
 				u8 probability   = schemdata[i].param1 & MTSCHEM_PROB_MASK;
 				bool force_place = schemdata[i].param1 & MTSCHEM_FORCE_PLACE;
 
-				ss << indent << indent << "{"
-					<< "name=\"" << names[schemdata[i].getContent()]
-					<< "\", prob=" << (u16)probability * 2
+				// After node resolving: real content_t, lookup using NodeDefManager
+				// Prior node resolving: condensed ID, lookup using m_nodenames
+				content_t c = schemdata[i].getContent();
+
+				ss << indent << indent << "{" << "name=\"";
+
+				if (!resolve_done) {
+					// Prior node resolving (eg. direct schematic load)
+					FATAL_ERROR_IF(c >= m_nodenames.size(), "Invalid node list");
+					ss << m_nodenames[c];
+				} else  {
+					// After node resolving (eg. biome decoration)
+					ss << m_ndef->get(c).name;
+				}
+
+				ss << "\", prob=" << (u16)probability * 2
 					<< ", param2=" << (u16)schemdata[i].param2;
 
 				if (force_place)
@@ -467,25 +491,24 @@ bool Schematic::loadSchematicFromFile(const std::string &filename,
 		return false;
 	}
 
-	size_t origsize = m_nodenames.size();
-	if (!deserializeFromMts(&is, &m_nodenames))
-		return false;
+	if (!m_ndef)
+		m_ndef = ndef;
 
-	m_nnlistsizes.push_back(m_nodenames.size() - origsize);
+	if (!deserializeFromMts(&is))
+		return false;
 
 	name = filename;
 
 	if (replace_names) {
-		for (size_t i = origsize; i < m_nodenames.size(); i++) {
-			std::string &node_name = m_nodenames[i];
+		for (std::string &node_name : m_nodenames) {
 			StringMap::iterator it = replace_names->find(node_name);
 			if (it != replace_names->end())
 				node_name = it->second;
 		}
 	}
 
-	if (ndef)
-		ndef->pendNodeResolve(this);
+	if (m_ndef)
+		m_ndef->pendNodeResolve(this);
 
 	return true;
 }
@@ -494,33 +517,26 @@ bool Schematic::loadSchematicFromFile(const std::string &filename,
 bool Schematic::saveSchematicToFile(const std::string &filename,
 	const NodeDefManager *ndef)
 {
-	MapNode *orig_schemdata = schemdata;
-	std::vector<std::string> ndef_nodenames;
-	std::vector<std::string> *names;
+	Schematic *schem = this;
 
-	if (m_resolve_done && ndef == NULL)
-		ndef = m_ndef;
+	bool needs_condense = isResolveDone();
 
-	if (ndef) {
-		names = &ndef_nodenames;
+	if (!m_ndef)
+		m_ndef = ndef;
 
-		u32 volume = size.X * size.Y * size.Z;
-		schemdata = new MapNode[volume];
-		for (u32 i = 0; i != volume; i++)
-			schemdata[i] = orig_schemdata[i];
+	if (needs_condense) {
+		if (!m_ndef)
+			return false;
 
-		generate_nodelist_and_update_ids(schemdata, volume, names, ndef);
-	} else { // otherwise, use the names we have on hand in the list
-		names = &m_nodenames;
+		schem = (Schematic *)this->clone();
+		schem->condenseContentIds();
 	}
 
 	std::ostringstream os(std::ios_base::binary);
-	bool status = serializeToMts(&os, *names);
+	bool status = schem->serializeToMts(&os);
 
-	if (ndef) {
-		delete []schemdata;
-		schemdata = orig_schemdata;
-	}
+	if (needs_condense)
+		delete schem;
 
 	if (!status)
 		return false;
@@ -556,6 +572,10 @@ bool Schematic::getSchematicFromMap(Map *map, v3s16 p1, v3s16 p2)
 	}
 
 	delete vm;
+
+	// Reset and mark as complete
+	NodeResolver::reset(true);
+
 	return true;
 }
 
@@ -584,26 +604,29 @@ void Schematic::applyProbabilities(v3s16 p0,
 }
 
 
-void generate_nodelist_and_update_ids(MapNode *nodes, size_t nodecount,
-	std::vector<std::string> *usednodes, const NodeDefManager *ndef)
+void Schematic::condenseContentIds()
 {
 	std::unordered_map<content_t, content_t> nodeidmap;
 	content_t numids = 0;
 
+	// Reset node resolve fields
+	NodeResolver::reset();
+
+	size_t nodecount = size.X * size.Y * size.Z;
 	for (size_t i = 0; i != nodecount; i++) {
 		content_t id;
-		content_t c = nodes[i].getContent();
+		content_t c = schemdata[i].getContent();
 
-		std::unordered_map<content_t, content_t>::const_iterator it = nodeidmap.find(c);
+		auto it = nodeidmap.find(c);
 		if (it == nodeidmap.end()) {
 			id = numids;
 			numids++;
 
-			usednodes->push_back(ndef->get(c).name);
-			nodeidmap.insert(std::make_pair(c, id));
+			m_nodenames.push_back(m_ndef->get(c).name);
+			nodeidmap.emplace(std::make_pair(c, id));
 		} else {
 			id = it->second;
 		}
-		nodes[i].setContent(id);
+		schemdata[i].setContent(id);
 	}
 }
diff --git a/src/mapgen/mg_schematic.h b/src/mapgen/mg_schematic.h
index 6b31251b6..5f64ea280 100644
--- a/src/mapgen/mg_schematic.h
+++ b/src/mapgen/mg_schematic.h
@@ -92,7 +92,7 @@ enum SchematicFormatType {
 
 class Schematic : public ObjDef, public NodeResolver {
 public:
-	Schematic();
+	Schematic() = default;
 	virtual ~Schematic();
 
 	ObjDef *clone() const;
@@ -105,11 +105,9 @@ public:
 		const NodeDefManager *ndef);
 	bool getSchematicFromMap(Map *map, v3s16 p1, v3s16 p2);
 
-	bool deserializeFromMts(std::istream *is, std::vector<std::string> *names);
-	bool serializeToMts(std::ostream *os,
-		const std::vector<std::string> &names) const;
-	bool serializeToLua(std::ostream *os, const std::vector<std::string> &names,
-		bool use_comments, u32 indent_spaces) const;
+	bool deserializeFromMts(std::istream *is);
+	bool serializeToMts(std::ostream *os) const;
+	bool serializeToLua(std::ostream *os, bool use_comments, u32 indent_spaces) const;
 
 	void blitToVManip(MMVManip *vm, v3s16 p, Rotation rot, bool force_place);
 	bool placeOnVManip(MMVManip *vm, v3s16 p, u32 flags, Rotation rot, bool force_place);
@@ -124,6 +122,10 @@ public:
 	v3s16 size;
 	MapNode *schemdata = nullptr;
 	u8 *slice_probs = nullptr;
+
+private:
+	// Counterpart to the node resolver: Condense content_t to a sequential "m_nodenames" list
+	void condenseContentIds();
 };
 
 class SchematicManager : public ObjDefManager {
@@ -151,5 +153,3 @@ private:
 	Server *m_server;
 };
 
-void generate_nodelist_and_update_ids(MapNode *nodes, size_t nodecount,
-	std::vector<std::string> *usednodes, const NodeDefManager *ndef);
diff --git a/src/nodedef.cpp b/src/nodedef.cpp
index 57d4c008f..8a1f6203b 100644
--- a/src/nodedef.cpp
+++ b/src/nodedef.cpp
@@ -1675,8 +1675,7 @@ bool NodeDefManager::nodeboxConnects(MapNode from, MapNode to,
 
 NodeResolver::NodeResolver()
 {
-	m_nodenames.reserve(16);
-	m_nnlistsizes.reserve(4);
+	reset();
 }
 
 
@@ -1779,3 +1778,16 @@ bool NodeResolver::getIdsFromNrBacklog(std::vector<content_t> *result_out,
 
 	return success;
 }
+
+void NodeResolver::reset(bool resolve_done)
+{
+	m_nodenames.clear();
+	m_nodenames_idx = 0;
+	m_nnlistsizes.clear();
+	m_nnlistsizes_idx = 0;
+
+	m_resolve_done = resolve_done;
+
+	m_nodenames.reserve(16);
+	m_nnlistsizes.reserve(4);
+}
diff --git a/src/nodedef.h b/src/nodedef.h
index 6fc20518d..3e77624eb 100644
--- a/src/nodedef.h
+++ b/src/nodedef.h
@@ -44,6 +44,9 @@ class ITextureSource;
 class IShaderSource;
 class IGameDef;
 class NodeResolver;
+#if BUILD_UNITTESTS
+class TestSchematic;
+#endif
 
 enum ContentParamType
 {
@@ -789,10 +792,13 @@ private:
 
 NodeDefManager *createNodeDefManager();
 
+// NodeResolver: Queue for node names which are then translated
+// to content_t after the NodeDefManager was initialized
 class NodeResolver {
 public:
 	NodeResolver();
 	virtual ~NodeResolver();
+	// Callback which is run as soon NodeDefManager is ready
 	virtual void resolveNodeNames() = 0;
 
 	// required because this class is used as mixin for ObjDef
@@ -804,12 +810,31 @@ public:
 	bool getIdsFromNrBacklog(std::vector<content_t> *result_out,
 		bool all_required = false, content_t c_fallback = CONTENT_IGNORE);
 
-	void nodeResolveInternal();
+	inline bool isResolveDone() const { return m_resolve_done; }
+	void reset(bool resolve_done = false);
 
-	u32 m_nodenames_idx = 0;
-	u32 m_nnlistsizes_idx = 0;
+	// Vector containing all node names in the resolve "queue"
 	std::vector<std::string> m_nodenames;
+	// Specifies the "set size" of node names which are to be processed
+	// this is used for getIdsFromNrBacklog
+	// TODO: replace or remove
 	std::vector<size_t> m_nnlistsizes;
+
+protected:
+	friend class NodeDefManager; // m_ndef
+
 	const NodeDefManager *m_ndef = nullptr;
+	// Index of the next "m_nodenames" entry to resolve
+	u32 m_nodenames_idx = 0;
+
+private:
+#if BUILD_UNITTESTS
+	// Unittest requires access to m_resolve_done
+	friend class TestSchematic;
+#endif
+	void nodeResolveInternal();
+
+	// Index of the next "m_nnlistsizes" entry to process
+	u32 m_nnlistsizes_idx = 0;
 	bool m_resolve_done = false;
 };
diff --git a/src/script/lua_api/l_mapgen.cpp b/src/script/lua_api/l_mapgen.cpp
index 12a497b1e..cc93bdbd0 100644
--- a/src/script/lua_api/l_mapgen.cpp
+++ b/src/script/lua_api/l_mapgen.cpp
@@ -1734,11 +1734,10 @@ int ModApiMapgen::l_serialize_schematic(lua_State *L)
 	std::ostringstream os(std::ios_base::binary);
 	switch (schem_format) {
 	case SCHEM_FMT_MTS:
-		schem->serializeToMts(&os, schem->m_nodenames);
+		schem->serializeToMts(&os);
 		break;
 	case SCHEM_FMT_LUA:
-		schem->serializeToLua(&os, schem->m_nodenames,
-			use_comments, indent_spaces);
+		schem->serializeToLua(&os, use_comments, indent_spaces);
 		break;
 	default:
 		return 0;
diff --git a/src/unittest/test_noderesolver.cpp b/src/unittest/test_noderesolver.cpp
index 28da43620..ed66093a9 100644
--- a/src/unittest/test_noderesolver.cpp
+++ b/src/unittest/test_noderesolver.cpp
@@ -56,6 +56,8 @@ void TestNodeResolver::runTests(IGameDef *gamedef)
 
 class Foobar : public NodeResolver {
 public:
+	friend class TestNodeResolver; // m_ndef
+
 	void resolveNodeNames();
 
 	content_t test_nr_node1;
diff --git a/src/unittest/test_schematic.cpp b/src/unittest/test_schematic.cpp
index da4ce50d2..d2f027eb4 100644
--- a/src/unittest/test_schematic.cpp
+++ b/src/unittest/test_schematic.cpp
@@ -66,13 +66,14 @@ void TestSchematic::testMtsSerializeDeserialize(const NodeDefManager *ndef)
 	std::stringstream ss(std::ios_base::binary |
 		std::ios_base::in | std::ios_base::out);
 
-	std::vector<std::string> names;
-	names.emplace_back("foo");
-	names.emplace_back("bar");
-	names.emplace_back("baz");
-	names.emplace_back("qux");
-
-	Schematic schem, schem2;
+	Schematic schem;
+	{
+		std::vector<std::string> &names = schem.m_nodenames;
+		names.emplace_back("foo");
+		names.emplace_back("bar");
+		names.emplace_back("baz");
+		names.emplace_back("qux");
+	}
 
 	schem.flags       = 0;
 	schem.size        = size;
@@ -83,18 +84,21 @@ void TestSchematic::testMtsSerializeDeserialize(const NodeDefManager *ndef)
 	for (s16 y = 0; y != size.Y; y++)
 		schem.slice_probs[y] = MTSCHEM_PROB_ALWAYS;
 
-	UASSERT(schem.serializeToMts(&ss, names));
+	UASSERT(schem.serializeToMts(&ss));
 
 	ss.seekg(0);
-	names.clear();
 
-	UASSERT(schem2.deserializeFromMts(&ss, &names));
+	Schematic schem2;
+	UASSERT(schem2.deserializeFromMts(&ss));
 
-	UASSERTEQ(size_t, names.size(), 4);
-	UASSERTEQ(std::string, names[0], "foo");
-	UASSERTEQ(std::string, names[1], "bar");
-	UASSERTEQ(std::string, names[2], "baz");
-	UASSERTEQ(std::string, names[3], "qux");
+	{
+		std::vector<std::string> &names = schem2.m_nodenames;
+		UASSERTEQ(size_t, names.size(), 4);
+		UASSERTEQ(std::string, names[0], "foo");
+		UASSERTEQ(std::string, names[1], "bar");
+		UASSERTEQ(std::string, names[2], "baz");
+		UASSERTEQ(std::string, names[3], "qux");
+	}
 
 	UASSERT(schem2.size == size);
 	for (size_t i = 0; i != volume; i++)
@@ -120,14 +124,14 @@ void TestSchematic::testLuaTableSerialize(const NodeDefManager *ndef)
 	for (s16 y = 0; y != size.Y; y++)
 		schem.slice_probs[y] = MTSCHEM_PROB_ALWAYS;
 
-	std::vector<std::string> names;
+	std::vector<std::string> &names = schem.m_nodenames;
 	names.emplace_back("air");
 	names.emplace_back("default:lava_source");
 	names.emplace_back("default:glass");
 
 	std::ostringstream ss(std::ios_base::binary);
 
-	UASSERT(schem.serializeToLua(&ss, names, false, 0));
+	UASSERT(schem.serializeToLua(&ss, false, 0));
 	UASSERTEQ(std::string, ss.str(), expected_lua_output);
 }
 
@@ -159,6 +163,8 @@ void TestSchematic::testFileSerializeDeserialize(const NodeDefManager *ndef)
 	schem1.slice_probs[0] = 80;
 	schem1.slice_probs[1] = 160;
 	schem1.slice_probs[2] = 240;
+	// Node resolving happened manually.
+	schem1.m_resolve_done = true;
 
 	for (size_t i = 0; i != volume; i++) {
 		content_t c = content_map[test_schem2_data[i]];