Safely handle block deletion (#13315)

Co-authored-by: Jude Melton-Houghton <jwmhjwmh@gmail.com>

1 files changed, 22 insertions, 1 deletions

diff --git a/src/map.cpp b/src/map.cpp
index 59d1a925d..239d5fb02 100644
--- a/src/map.cpp
+++ b/src/map.cpp
@@ -1309,6 +1309,8 @@ ServerMap::~ServerMap()
 	*/
 	delete dbase;
 	delete dbase_ro;
+
+	deleteDetachedBlocks();
 }
 
 MapgenParams *ServerMap::getMapgenParams()
@@ -1888,12 +1890,31 @@ bool ServerMap::deleteBlock(v3s16 blockpos)
 		MapSector *sector = getSectorNoGenerate(p2d);
 		if (!sector)
 			return false;
-		sector->deleteBlock(block);
+		// It may not be safe to delete the block from memory at the moment
+		// (pointers to it could still be in use)
+		sector->detachBlock(block);
+		m_detached_blocks.push_back(block);
 	}
 
 	return true;
 }
 
+void ServerMap::deleteDetachedBlocks()
+{
+	for (MapBlock *block : m_detached_blocks) {
+		assert(block->isOrphan());
+		delete block;
+	}
+	m_detached_blocks.clear();
+}
+
+void ServerMap::step()
+{
+	// Delete from memory blocks removed by deleteBlocks() only when pointers
+	// to them are (probably) no longer in use
+	deleteDetachedBlocks();
+}
+
 void ServerMap::PrintInfo(std::ostream &out)
 {
 	out<<"ServerMap: ";