Guard new object from being added at shutdown (#16610)

Author: sfan5

src/serverenvironment.cpp

@@ -278,15 +278,20 @@ void ServerEnvironment::init()
 
 void ServerEnvironment::deactivateBlocksAndObjects()
 {
+	// Prevent any funny business from happening in case further callbacks
+	// try to add new objects.
+	m_shutting_down = true;
+
 	// Clear active block list.
-	// This makes the next one delete all active objects.
+	// This makes the next code delete all active objects.
 	m_active_blocks.clear();
 
 	deactivateFarObjects(true);
 }
 
 ServerEnvironment::~ServerEnvironment()
 {
+	m_script = nullptr;
 	assert(m_active_blocks.size() == 0); // deactivateBlocksAndObjects does this
 
 	// Drop/delete map
@@ -301,9 +306,12 @@ ServerEnvironment::~ServerEnvironment()
 	for (RemotePlayer *m_player : m_players) {
 		delete m_player;
 	}
+	m_players.clear();
 
 	delete m_player_database;
+	m_player_database = nullptr;
 	delete m_auth_database;
+	m_auth_database = nullptr;
 }
 
 Map & ServerEnvironment::getMap()
@@ -1208,6 +1216,11 @@ void ServerEnvironment::deleteParticleSpawner(u32 id, bool remove_from_object)
 u16 ServerEnvironment::addActiveObject(std::unique_ptr<ServerActiveObject> object)
 {
 	assert(object);	// Pre-condition
+	if (m_shutting_down) {
+		warningstream << "ServerEnvironment: refusing to add active object "
+			"during shutdown: " << object->getDescription() << std::endl;
+		return 0;
+	}
 	m_added_objects++;
 	u16 id = addActiveObjectRaw(std::move(object), nullptr, 0);
 	return id;
@@ -1569,7 +1582,7 @@ std::unique_ptr<ServerActiveObject> ServerEnvironment::createSAO(ActiveObjectTyp
 */
 void ServerEnvironment::activateObjects(MapBlock *block, u32 dtime_s)
 {
-	if (block == NULL)
+	if (!block || m_shutting_down)
 		return;
 
 	if (!block->onObjectsActivation())

src/serverenvironment.h

@@ -357,9 +357,9 @@ class ServerEnvironment final : public Environment
 	// The map
 	std::unique_ptr<ServerMap> m_map;
 	// Lua state
-	ServerScripting* m_script;
+	ServerScripting *m_script = nullptr;
 	// Server definition
-	Server *m_server;
+	Server *m_server = nullptr;
 	// Active Object Manager
 	server::ActiveObjectMgr m_ao_manager;
 	// on_mapblocks_changed map event receiver
@@ -378,6 +378,8 @@ class ServerEnvironment final : public Environment
 	IntervalLimiter m_active_blocks_nodemetadata_interval;
 	// Whether the variables below have been read from file yet
 	bool m_meta_loaded = false;
+	// Are we shutting down?
+	bool m_shutting_down = false;
 	// Time from the beginning of the game in seconds.
 	// Incremented in step().
 	u32 m_game_time = 0;