Add formspec prepends (or appends?)

• Implements https://github.com/minetest/minetest/pull/7099 in a backwards-compatible way.
 • Formspec prepends are appended (I don't think prepending them works) to formspecs before sending them to clients. This way older clients will still be able to display formspec prepends.

src/mapblock.cpp

@@ -553,7 +553,8 @@ static void correctBlockNodeIds(const NameIdMapping *nimap, MapNode *nodes,
 	}
 }
 
-void MapBlock::serialize(std::ostream &os, u8 version, bool disk)
+void MapBlock::serialize(std::ostream &os, u8 version, bool disk,
+	std::string formspec_prepend)
 {
 	if(!ser_ver_supported(version))
 		throw VersionMismatchException("ERROR: MapBlock format not supported");
@@ -611,7 +612,7 @@ void MapBlock::serialize(std::ostream &os, u8 version, bool disk)
 		Node metadata
 	*/
 	std::ostringstream oss(std::ios_base::binary);
-	m_node_metadata.serialize(oss, version, disk);
+	m_node_metadata.serialize(oss, version, disk, formspec_prepend);
 	compressZlib(oss.str(), os);
 
 	/*

src/mapblock.h

@@ -543,7 +543,8 @@ public:
 	// These don't write or read version by itself
 	// Set disk to true for on-disk format, false for over-the-network format
 	// Precondition: version >= SER_FMT_VER_LOWEST_WRITE
-	void serialize(std::ostream &os, u8 version, bool disk);
+	void serialize(std::ostream &os, u8 version, bool disk,
+		std::string formspec_prepend="");
 	// If disk == true: In addition to doing other things, will add
 	// unknown blocks from id-name mapping to wndef
 	void deSerialize(std::istream &is, u8 version, bool disk);

src/nodemetadata.cpp

@@ -40,7 +40,8 @@ NodeMetadata::~NodeMetadata()
 	delete m_inventory;
 }
 
-void NodeMetadata::serialize(std::ostream &os, u8 version, bool disk) const
+void NodeMetadata::serialize(std::ostream &os, u8 version, bool disk,
+	std::string formspec_prepend) const
 {
 	int num_vars = disk ? m_stringvars.size() : countNonPrivate();
 	writeU32(os, num_vars);
@@ -52,7 +53,14 @@ void NodeMetadata::serialize(std::ostream &os, u8 version, bool disk) const
 			continue;
 
 		os << serializeString(it->first);
-		os << serializeLongString(it->second);
+
+		if (formspec_prepend != "" && it->first == "formspec" &&
+				it->second.find("no_prepend[]") == std::string::npos) {
+			os << serializeLongString(it->second + formspec_prepend);
+		} else {
+			os << serializeLongString(it->second);
+		}
+
 		if (version >= 2)
 			writeU8(os, (priv) ? 1 : 0);
 	}
@@ -116,7 +124,8 @@ int NodeMetadata::countNonPrivate() const
 	NodeMetadataList
 */
 
-void NodeMetadataList::serialize(std::ostream &os, u8 blockver, bool disk) const
+void NodeMetadataList::serialize(std::ostream &os, u8 blockver, bool disk,
+	std::string formspec_prepend) const
 {
 	/*
 		Version 0 is a placeholder for "nothing to see here; go away."
@@ -144,7 +153,7 @@ void NodeMetadataList::serialize(std::ostream &os, u8 blockver, bool disk) const
 		u16 p16 = p.Z * MAP_BLOCKSIZE * MAP_BLOCKSIZE + p.Y * MAP_BLOCKSIZE + p.X;
 		writeU16(os, p16);
 
-		data->serialize(os, version, disk);
+		data->serialize(os, version, disk, formspec_prepend);
 	}
 }
 

src/nodemetadata.h

@@ -41,7 +41,8 @@ public:
 	NodeMetadata(IItemDefManager *item_def_mgr);
 	~NodeMetadata();
 
-	void serialize(std::ostream &os, u8 version, bool disk=true) const;
+	void serialize(std::ostream &os, u8 version, bool disk=true,
+		std::string formspec_prepend="") const;
 	void deSerialize(std::istream &is, u8 version);
 
 	void clear();
@@ -76,7 +77,8 @@ class NodeMetadataList
 public:
 	~NodeMetadataList();
 
-	void serialize(std::ostream &os, u8 blockver, bool disk=true) const;
+	void serialize(std::ostream &os, u8 blockver, bool disk=true,
+		std::string formspec_prepend="") const;
 	void deSerialize(std::istream &is, IItemDefManager *item_def_mgr);
 
 	// Add all keys in this list to the vector keys

src/player.h

@@ -164,6 +164,7 @@ public:
 	u16 peer_id;
 
 	std::string inventory_formspec;
+	std::string formspec_prepend;
 
 	PlayerControl control;
 	const PlayerControl& getPlayerControl() { return control; }

src/script/lua_api/l_object.cpp

@@ -1261,6 +1261,37 @@ int ObjectRef::l_get_inventory_formspec(lua_State *L)
 	return 1;
 }
 
+// set_formspec_prepend(self, formspec)
+int ObjectRef::l_set_formspec_prepend(lua_State *L)
+{
+	NO_MAP_LOCK_REQUIRED;
+	ObjectRef *ref = checkobject(L, 1);
+	RemotePlayer *player = getplayer(ref);
+	if (player == NULL)
+		return 0;
+
+	std::string formspec = luaL_checkstring(L, 2);
+
+	player->formspec_prepend = formspec;
+	getServer(L)->reportInventoryFormspecModified(player->getName());
+	lua_pushboolean(L, true);
+	return 1;
+}
+
+// get_formspec_prepend(self) -> formspec
+int ObjectRef::l_get_formspec_prepend(lua_State *L)
+{
+	NO_MAP_LOCK_REQUIRED;
+	ObjectRef *ref = checkobject(L, 1);
+	RemotePlayer *player = getplayer(ref);
+	if (player == NULL)
+		 return 0;
+
+	std::string formspec = player->formspec_prepend;
+	lua_pushlstring(L, formspec.c_str(), formspec.size());
+	return 1;
+}
+
 // get_player_control(self)
 int ObjectRef::l_get_player_control(lua_State *L)
 {
@@ -1979,6 +2010,8 @@ const luaL_Reg ObjectRef::methods[] = {
 	luamethod(ObjectRef, set_attribute),
 	luamethod(ObjectRef, set_inventory_formspec),
 	luamethod(ObjectRef, get_inventory_formspec),
+	luamethod(ObjectRef, set_formspec_prepend),
+	luamethod(ObjectRef, get_formspec_prepend),
 	luamethod(ObjectRef, get_player_control),
 	luamethod(ObjectRef, get_player_control_bits),
 	luamethod(ObjectRef, set_physics_override),

src/script/lua_api/l_object.h

@@ -238,6 +238,12 @@ private:
 	// get_inventory_formspec(self) -> formspec
 	static int l_get_inventory_formspec(lua_State *L);
 
+	// set_formspec_prepend(self, formspec)
+	static int l_set_formspec_prepend(lua_State *L);
+
+	// get_formspec_prepend(self) -> formspec
+	static int l_get_formspec_prepend(lua_State *L);
+
 	// get_player_control(self)
 	static int l_get_player_control(lua_State *L);
 

src/server.cpp

@@ -1673,11 +1673,20 @@ void Server::SendShowFormspecMessage(u16 peer_id, const std::string &formspec,
 	DSTACK(FUNCTION_NAME);
 
 	NetworkPacket pkt(TOCLIENT_SHOW_FORMSPEC, 0 , peer_id);
-	if (formspec == "" ){
-		//the client should close the formspec
+	if (formspec == "") {
+		// The client should close the formspec.
 		pkt.putLongString("");
 	} else {
-		pkt.putLongString(FORMSPEC_VERSION_STRING + formspec);
+		// Get the formspec prepend.
+		RemotePlayer *player = m_env->getPlayer(peer_id);
+		if (player->peer_id == PEER_ID_INEXISTENT) {
+			return;
+		} else if (formspec.find("no_prepend[]") == std::string::npos) {
+			pkt.putLongString(FORMSPEC_VERSION_STRING + formspec +
+				player->formspec_prepend);
+		} else {
+			pkt.putLongString(FORMSPEC_VERSION_STRING + formspec);
+		}
 	}
 	pkt << formname;
 
@@ -2019,7 +2028,14 @@ void Server::SendPlayerInventoryFormspec(u16 peer_id)
 		return;
 
 	NetworkPacket pkt(TOCLIENT_INVENTORY_FORMSPEC, 0, peer_id);
-	pkt.putLongString(FORMSPEC_VERSION_STRING + player->inventory_formspec);
+
+	if (player->inventory_formspec.find("no_prepend[]") == std::string::npos) {
+		pkt.putLongString(FORMSPEC_VERSION_STRING + player->inventory_formspec +
+			player->formspec_prepend);
+	} else {
+		pkt.putLongString(FORMSPEC_VERSION_STRING + player->inventory_formspec);
+	}
+
 	Send(&pkt);
 }
 
@@ -2282,7 +2298,14 @@ void Server::SendBlockNoLock(u16 peer_id, MapBlock *block, u8 ver, u16 net_proto
 	*/
 
 	std::ostringstream os(std::ios_base::binary);
-	block->serialize(os, ver, false);
+
+	RemotePlayer *player = m_env->getPlayer(peer_id);
+	if (player->peer_id == PEER_ID_INEXISTENT) {
+		block->serialize(os, ver, false);
+	} else {
+		block->serialize(os, ver, false, player->formspec_prepend);
+	}
+
 	block->serializeNetworkSpecific(os);
 	std::string s = os.str();