Add ability to delete MapBlocks from map

Also add a Lua API and chatcommand for this

builtin/game/chatcommands.lua

@@ -403,6 +403,46 @@ core.register_chatcommand("set", {
 	end,
 })
 
+core.register_chatcommand("deleteblocks", {
+	params = "[here] [<pos1> <pos2>]",
+	description = "delete map blocks contained in area pos1 to pos2",
+	privs = {server=true},
+	func = function(name, param)
+		local p1 = {}
+		local p2 = {}
+		if param == "here" then
+			local player = core.get_player_by_name(name)
+			if player == nil then
+				core.log("error", "player is nil")
+				return false, "Unable to get current position; player is nil"
+			end
+			p1 = player:getpos()
+			p2 = p1
+		else
+			p1.x, p1.y, p1.z, p2.x, p2.y, p2.z = string.match(param,
+				"^%(([%d.-]+), *([%d.-]+), *([%d.-]+)%) *%(([%d.-]+), *([%d.-]+), *([%d.-]+)%)$")
+			p1.x = tonumber(p1.x)
+			p1.y = tonumber(p1.y)
+			p1.z = tonumber(p1.z)
+			p2.x = tonumber(p2.x)
+			p2.y = tonumber(p2.y)
+			p2.z = tonumber(p2.z)
+
+			if p1.x == nil or p1.y == nil or p1.z == nil or
+				p2.x == nil or p2.y == nil or p2.z == nil then
+				return false, "Incorrect area format. Expected: (x1,y1,z1) (x2,y2,z2)"
+			end
+		end
+
+		if core.delete_area(p1, p2) then
+			return true, "Successfully cleared area ranging from " ..
+				core.pos_to_string(p1) .. " to " .. core.pos_to_string(p2)
+		else
+			return false, "Failed to clear one or more blocks in area"
+		end
+	end,
+})
+
 core.register_chatcommand("mods", {
 	params = "",
 	description = "List mods installed on the server",

doc/lua_api.txt

@@ -1880,6 +1880,8 @@ and `minetest.auth_reload` call the authetification handler.
    * Generate all registered decorations within the VoxelManip specified by `vm`.
 * `minetest.clear_objects()`
     * clear all objects in the environments
+* `minetest.delete_area(pos1, pos2)`
+    * delete all mapblocks in the area from pos1 to pos2, inclusive
 * `minetest.line_of_sight(pos1, pos2, stepsize)`: returns `boolean, pos`
     * Check if there is a direct line of sight between `pos1` and `pos2`
     * Returns the position of the blocking node when `false`

src/database-dummy.cpp

@@ -59,6 +59,11 @@ std::string Database_Dummy::loadBlock(v3s16 blockpos)
 		return "";
 }
 
+bool Database_Dummy::deleteBlock(v3s16 blockpos)
+{
+	m_database.erase(getBlockAsInteger(blockpos));
+}
+
 void Database_Dummy::listAllLoadableBlocks(std::list<v3s16> &dst)
 {
 	for(std::map<u64, std::string>::iterator x = m_database.begin(); x != m_database.end(); ++x)

src/database-dummy.h

@@ -35,6 +35,7 @@ public:
 	virtual void endSave();
 	virtual bool saveBlock(v3s16 blockpos, std::string &data);
 	virtual std::string loadBlock(v3s16 blockpos);
+	virtual bool deleteBlock(v3s16 blockpos);
 	virtual void listAllLoadableBlocks(std::list<v3s16> &dst);
 	virtual int Initialized(void);
 	~Database_Dummy();

src/database-leveldb.cpp

@@ -80,6 +80,19 @@ std::string Database_LevelDB::loadBlock(v3s16 blockpos)
 		return "";
 }
 
+bool Database_LevelDB::deleteBlock(v3s16 blockpos)
+{
+	leveldb::Status status = m_database->Delete(leveldb::WriteOptions(),
+			i64tos(getBlockAsInteger(blockpos)));
+	if (!status.ok()) {
+		errorstream << "WARNING: deleteBlock: LevelDB error deleting block "
+			<< PP(blockpos) << ": " << status.ToString() << std::endl;
+		return false;
+	}
+
+	return true;
+}
+
 void Database_LevelDB::listAllLoadableBlocks(std::list<v3s16> &dst)
 {
 	leveldb::Iterator* it = m_database->NewIterator(leveldb::ReadOptions());

src/database-leveldb.h

@@ -38,6 +38,7 @@ public:
 	virtual void endSave();
 	virtual bool saveBlock(v3s16 blockpos, std::string &data);
 	virtual std::string loadBlock(v3s16 blockpos);
+	virtual bool deleteBlock(v3s16 blockpos);
 	virtual void listAllLoadableBlocks(std::list<v3s16> &dst);
 	virtual int Initialized(void);
 	~Database_LevelDB();

src/database-redis.cpp

@@ -123,6 +123,30 @@ std::string Database_Redis::loadBlock(v3s16 blockpos)
 	return str;
 }
 
+bool Database_Redis::deleteBlock(v3s16 blockpos)
+{
+	std::string tmp = i64tos(getBlockAsInteger(blockpos));
+
+	redisReply *reply = (redisReply *)redisCommand(ctx, "HDEL %s %s",
+		hash.c_str(), tmp.c_str());
+	if (!reply) {
+		errorstream << "WARNING: deleteBlock: redis command 'HDEL' failed on "
+			"block " << PP(blockpos) << ": " << ctx->errstr << std::endl;
+		freeReplyObject(reply);
+		return false;
+	}
+
+	if (reply->type == REDIS_REPLY_ERROR) {
+		errorstream << "WARNING: deleteBlock: deleting block " << PP(blockpos)
+			<< "failed" << std::endl;
+		freeReplyObject(reply);
+		return false;
+	}
+
+	freeReplyObject(reply);
+	return true;
+}
+
 void Database_Redis::listAllLoadableBlocks(std::list<v3s16> &dst)
 {
 	redisReply *reply;

src/database-redis.h

@@ -38,6 +38,7 @@ public:
 	virtual void endSave();
 	virtual bool saveBlock(v3s16 blockpos, std::string &data);
 	virtual std::string loadBlock(v3s16 blockpos);
+	virtual bool deleteBlock(v3s16 blockpos);
 	virtual void listAllLoadableBlocks(std::list<v3s16> &dst);
 	virtual int Initialized(void);
 	~Database_Redis();

src/database-sqlite3.cpp

@@ -131,13 +131,11 @@ void Database_SQLite3::verifyDatabase() {
 		throw FileNotGoodException("Cannot prepare write statement");
 	}
 
-#ifdef __ANDROID__
 	d = sqlite3_prepare(m_database, "DELETE FROM `blocks` WHERE `pos`=?;", -1, &m_database_delete, NULL);
 	if(d != SQLITE_OK) {
 		infostream<<"WARNING: SQLite3 database delete statment failed to prepare: "<<sqlite3_errmsg(m_database)<<std::endl;
 		throw FileNotGoodException("Cannot prepare delete statement");
 	}
-#endif
 
 	d = sqlite3_prepare(m_database, "SELECT `pos` FROM `blocks`", -1, &m_database_list, NULL);
 	if(d != SQLITE_OK) {
@@ -148,22 +146,48 @@ void Database_SQLite3::verifyDatabase() {
 	infostream<<"ServerMap: SQLite3 database opened"<<std::endl;
 }
 
+bool Database_SQLite3::deleteBlock(v3s16 blockpos)
+{
+	verifyDatabase();
+
+	if (sqlite3_bind_int64(m_database_delete, 1,
+			getBlockAsInteger(blockpos)) != SQLITE_OK) {
+		errorstream << "WARNING: Could not bind block position for delete: "
+			<< sqlite3_errmsg(m_database) << std::endl;
+	}
+
+	if (sqlite3_step(m_database_delete) != SQLITE_DONE) {
+		errorstream << "WARNING: deleteBlock: Block failed to delete "
+			<< PP(blockpos) << ": " << sqlite3_errmsg(m_database) << std::endl;
+		sqlite3_reset(m_database_delete);
+		return false;
+	}
+
+	sqlite3_reset(m_database_delete);
+	return true;
+}
+
 bool Database_SQLite3::saveBlock(v3s16 blockpos, std::string &data)
 {
 	verifyDatabase();
 
+	s64 bkey = getBlockAsInteger(blockpos);
+
 #ifdef __ANDROID__
 	/**
 	 * Note: For some unknown reason sqlite3 fails to REPLACE blocks on android,
 	 * deleting them and inserting first works.
 	 */
-	if (sqlite3_bind_int64(m_database_read, 1, getBlockAsInteger(blockpos)) != SQLITE_OK) {
+	if (sqlite3_bind_int64(m_database_read, 1, bkey) != SQLITE_OK) {
 		infostream << "WARNING: Could not bind block position for load: "
 			<< sqlite3_errmsg(m_database)<<std::endl;
 	}
 
-	if (sqlite3_step(m_database_read) == SQLITE_ROW) {
+	int step_result = sqlite3_step(m_database_read);
-		if (sqlite3_bind_int64(m_database_delete, 1, getBlockAsInteger(blockpos)) != SQLITE_OK) {
+	sqlite3_reset(m_database_read);
+
+	if (step_result == SQLITE_ROW) {
+		if (sqlite3_bind_int64(m_database_delete, 1, bkey) != SQLITE_OK) {
 			infostream << "WARNING: Could not bind block position for delete: "
 				<< sqlite3_errmsg(m_database)<<std::endl;
 		}
@@ -175,17 +199,17 @@ bool Database_SQLite3::saveBlock(v3s16 blockpos, std::string &data)
 		}
 		sqlite3_reset(m_database_delete);
 	}
-	sqlite3_reset(m_database_read);
 #endif
 
-	if (sqlite3_bind_int64(m_database_write, 1, getBlockAsInteger(blockpos)) != SQLITE_OK) {
+	if (sqlite3_bind_int64(m_database_write, 1, bkey) != SQLITE_OK) {
 		errorstream << "WARNING: saveBlock: Block position failed to bind: "
 			<< PP(blockpos) << ": " << sqlite3_errmsg(m_database) << std::endl;
 		sqlite3_reset(m_database_write);
 		return false;
 	}
 
-	if (sqlite3_bind_blob(m_database_write, 2, (void *) data.c_str(), data.size(), NULL) != SQLITE_OK) {
+	if (sqlite3_bind_blob(m_database_write, 2, (void *)data.c_str(),
+			data.size(), NULL) != SQLITE_OK) {
 		errorstream << "WARNING: saveBlock: Block data failed to bind: "
 			<< PP(blockpos) << ": " << sqlite3_errmsg(m_database) << std::endl;
 		sqlite3_reset(m_database_write);
@@ -277,6 +301,7 @@ Database_SQLite3::~Database_SQLite3()
 	FINALIZE_STATEMENT(m_database_read)
 	FINALIZE_STATEMENT(m_database_write)
 	FINALIZE_STATEMENT(m_database_list)
+	FINALIZE_STATEMENT(m_database_delete)
 
 	if(m_database)
 		rc = sqlite3_close(m_database);

src/database-sqlite3.h

@@ -38,6 +38,7 @@ public:
 
 	virtual bool saveBlock(v3s16 blockpos, std::string &data);
 	virtual std::string loadBlock(v3s16 blockpos);
+	virtual bool deleteBlock(v3s16 blockpos);
 	virtual void listAllLoadableBlocks(std::list<v3s16> &dst);
 	virtual int Initialized(void);
 	~Database_SQLite3();
@@ -47,9 +48,7 @@ private:
 	sqlite3 *m_database;
 	sqlite3_stmt *m_database_read;
 	sqlite3_stmt *m_database_write;
-#ifdef __ANDROID__
 	sqlite3_stmt *m_database_delete;
-#endif
 	sqlite3_stmt *m_database_list;
 
 	// Create the database structure

src/database.h

@@ -37,6 +37,7 @@ public:
 
 	virtual bool saveBlock(v3s16 blockpos, std::string &data) = 0;
 	virtual std::string loadBlock(v3s16 blockpos) = 0;
+	virtual bool deleteBlock(v3s16 blockpos) = 0;
 	s64 getBlockAsInteger(const v3s16 pos) const;
 	v3s16 getIntegerAsBlock(s64 i) const;
 	virtual void listAllLoadableBlocks(std::list<v3s16> &dst) = 0;

src/map.cpp

@@ -3588,6 +3588,23 @@ MapBlock* ServerMap::loadBlock(v3s16 blockpos)
 	return getBlockNoCreateNoEx(blockpos);
 }
 
+bool ServerMap::deleteBlock(v3s16 blockpos)
+{
+	if (!dbase->deleteBlock(blockpos))
+		return false;
+
+	MapBlock *block = getBlockNoCreateNoEx(blockpos);
+	if (block) {
+		v2s16 p2d(blockpos.X, blockpos.Z);
+		MapSector *sector = getSectorNoGenerateNoEx(p2d);
+		if (!sector)
+			return false;
+		sector->deleteBlock(block);
+	}
+
+	return true;
+}
+
 void ServerMap::PrintInfo(std::ostream &out)
 {
 	out<<"ServerMap: ";

src/map.h

@@ -267,9 +267,10 @@ public:
 
 	virtual void save(ModifiedState save_level){assert(0);};
 
-	// Server implements this.
+	// Server implements these.
-	// Client leaves it as no-op.
+	// Client leaves them as no-op.
 	virtual bool saveBlock(MapBlock *block) { return false; };
+	virtual bool deleteBlock(v3s16 blockpos) { return false; };
 
 	/*
 		Updates usage timers and unloads unused blocks and sectors.
@@ -498,6 +499,8 @@ public:
 	// Database version
 	void loadBlock(std::string *blob, v3s16 p3d, MapSector *sector, bool save_after_load=false);
 
+	bool deleteBlock(v3s16 blockpos);
+
 	void updateVManip(v3s16 pos);
 
 	// For debug printing

src/script/lua_api/l_env.cpp

@@ -657,7 +657,8 @@ int ModApiEnvMod::l_clear_objects(lua_State *L)
 }
 
 // line_of_sight(pos1, pos2, stepsize) -> true/false, pos
-int ModApiEnvMod::l_line_of_sight(lua_State *L) {
+int ModApiEnvMod::l_line_of_sight(lua_State *L)
+{
 	float stepsize = 1.0;
 
 	GET_ENV_PTR;
@@ -681,6 +682,37 @@ int ModApiEnvMod::l_line_of_sight(lua_State *L) {
 	return 1;
 }
 
+// delete_area(p1, p2)
+// delete mapblocks in area p1..p2
+int ModApiEnvMod::l_delete_area(lua_State *L)
+{
+	GET_ENV_PTR;
+
+	v3s16 bpmin = getNodeBlockPos(read_v3s16(L, 1));
+	v3s16 bpmax = getNodeBlockPos(read_v3s16(L, 2));
+	sortBoxVerticies(bpmin, bpmax);
+
+	ServerMap &map = env->getServerMap();
+
+	MapEditEvent event;
+	event.type = MEET_OTHER;
+
+	bool success = true;
+	for (s16 z = bpmin.Z; z <= bpmax.Z; z++)
+	for (s16 y = bpmin.Y; y <= bpmax.Y; y++)
+	for (s16 x = bpmin.X; x <= bpmax.X; x++) {
+		v3s16 bp(x, y, z);
+		if (map.deleteBlock(bp))
+			event.modified_blocks.insert(bp);
+		else
+			success = false;
+	}
+
+	map.dispatchEvent(&event);
+	lua_pushboolean(L, success);
+	return 1;
+}
+
 // find_path(pos1, pos2, searchdistance,
 //     max_jump, max_drop, algorithm) -> table containing path
 int ModApiEnvMod::l_find_path(lua_State *L)
@@ -849,6 +881,7 @@ void ModApiEnvMod::Initialize(lua_State *L, int top)
 	API_FCT(get_gametime);
 	API_FCT(find_node_near);
 	API_FCT(find_nodes_in_area);
+	API_FCT(delete_area);
 	API_FCT(get_perlin);
 	API_FCT(get_perlin_map);
 	API_FCT(get_voxel_manip);

src/script/lua_api/l_env.h

@@ -119,6 +119,9 @@ private:
 	// nodenames: eg. {"ignore", "group:tree"} or "default:dirt"
 	static int l_find_nodes_in_area(lua_State *L);
 
+	// delete_area(p1, p2) -> true/false
+	static int l_delete_area(lua_State *L);
+
 	// get_perlin(seeddiff, octaves, persistence, scale)
 	// returns world-specific PerlinNoise
 	static int l_get_perlin(lua_State *L);