From ba048e2101d42af53f2ac7a9a3ed04c194918136 Mon Sep 17 00:00:00 2001
From: Alexander Harkness <me@bearbin.net>
Date: Fri, 3 Apr 2020 20:24:49 +0000
Subject: New hotfix to prevent calling OnBroken (#4600)

* Fix stack overflow in breaking ice.

Stupid fix, but it does work and is used in other places too...

* Replace hotfix for pistons with better one

* Fix comments in BlockBed handler
---
 src/Blocks/BlockBed.cpp    | 16 ++++++++--------
 src/Blocks/BlockIce.h      |  2 ++
 src/Blocks/BlockPiston.cpp |  7 ++++---
 src/ChunkMap.cpp           |  7 +------
 4 files changed, 15 insertions(+), 17 deletions(-)

diff --git a/src/Blocks/BlockBed.cpp b/src/Blocks/BlockBed.cpp
index e6193682a..8b349ef5e 100644
--- a/src/Blocks/BlockBed.cpp
+++ b/src/Blocks/BlockBed.cpp
@@ -21,27 +21,27 @@ void cBlockBedHandler::OnBroken(cChunkInterface & a_ChunkInterface, cWorldInterf
 	if ((a_OldBlockMeta & 0x08) != 0)
 	{
 		// Was pillow
-		if (a_ChunkInterface.GetBlock(a_BlockPos - Direction) == E_BLOCK_BED)
+		Vector3i FootPos(a_BlockPos - Direction);
+		if (a_ChunkInterface.GetBlock(FootPos) == E_BLOCK_BED)
 		{
 			// First replace the bed with air
-			a_ChunkInterface.FastSetBlock(a_BlockPos - Direction, E_BLOCK_AIR, 0);
+			a_ChunkInterface.FastSetBlock(FootPos, E_BLOCK_AIR, 0);
 
 			// Then destroy the bed entity
-			Vector3i PillowPos(a_BlockPos - Direction);
-			a_ChunkInterface.SetBlock(PillowPos, E_BLOCK_AIR, 0);
+			a_ChunkInterface.SetBlock(FootPos, E_BLOCK_AIR, 0);
 		}
 	}
 	else
 	{
 		// Was foot end
-		if (a_ChunkInterface.GetBlock(a_BlockPos + Direction) == E_BLOCK_BED)
+		Vector3i PillowPos(a_BlockPos + Direction);
+		if (a_ChunkInterface.GetBlock(PillowPos) == E_BLOCK_BED)
 		{
 			// First replace the bed with air
-			a_ChunkInterface.FastSetBlock(a_BlockPos + Direction, E_BLOCK_AIR, 0);
+			a_ChunkInterface.FastSetBlock(PillowPos, E_BLOCK_AIR, 0);
 
 			// Then destroy the bed entity
-			Vector3i FootPos(a_BlockPos + Direction);
-			a_ChunkInterface.SetBlock(FootPos, E_BLOCK_AIR, 0);
+			a_ChunkInterface.SetBlock(PillowPos, E_BLOCK_AIR, 0);
 		}
 	}
 }
diff --git a/src/Blocks/BlockIce.h b/src/Blocks/BlockIce.h
index 672288ca3..a39162d79 100644
--- a/src/Blocks/BlockIce.h
+++ b/src/Blocks/BlockIce.h
@@ -54,6 +54,8 @@ public:
 		auto blockTypeBelow = a_ChunkInterface.GetBlock(a_BlockPos.addedY(-1));
 		if (cBlockInfo::FullyOccupiesVoxel(blockTypeBelow) || IsBlockLiquid(blockTypeBelow))
 		{
+			// Setting air with FastSetBlock prevents SetBlock recursively calling OnBroken.
+			a_ChunkInterface.FastSetBlock(a_BlockPos, E_BLOCK_AIR, 0);
 			a_ChunkInterface.SetBlock(a_BlockPos, E_BLOCK_WATER, 0);
 		}
 	}
diff --git a/src/Blocks/BlockPiston.cpp b/src/Blocks/BlockPiston.cpp
index 5a18cffac..8c6940454 100644
--- a/src/Blocks/BlockPiston.cpp
+++ b/src/Blocks/BlockPiston.cpp
@@ -297,9 +297,10 @@ void cBlockPistonHandler::RetractPiston(Vector3i a_BlockPos, cWorld & a_World)
 				return;
 			}
 
-			// Remove extension, update base state
-			World.SetBlock(extensionPos.x, extensionPos.y, extensionPos.z, E_BLOCK_AIR, 0);
-			World.SetBlock(a_BlockPos.x, a_BlockPos.y, a_BlockPos.z, pistonBlock, pistonMeta & ~(8));
+			// Remove extension, update base state. Calling FastSetBlock inhibits OnBroken being called by SetBlock.
+			World.FastSetBlock(extensionPos, E_BLOCK_AIR, 0);
+			World.SetBlock(extensionPos, E_BLOCK_AIR, 0);
+			World.SetBlock(a_BlockPos, pistonBlock, pistonMeta & ~(8));
 
 			// (Retraction is always successful, but play in the task for consistency)
 			World.BroadcastSoundEffect("block.piston.contract", a_BlockPos, 0.5f, 0.7f);
diff --git a/src/ChunkMap.cpp b/src/ChunkMap.cpp
index cb6ba07ca..fd4987bb4 100644
--- a/src/ChunkMap.cpp
+++ b/src/ChunkMap.cpp
@@ -641,12 +641,7 @@ void cChunkMap::SetBlock(Vector3i a_BlockPos, BLOCKTYPE a_BlockType, NIBBLETYPE
 		GetBlockTypeMeta(a_BlockPos, blockType, blockMeta);
 		cChunkInterface ChunkInterface(this);
 
-		// Hotfix for https://github.com/cuberite/cuberite/issues/4468
-		// Should be removed when a proper fix is found.
-		if ((blockType != E_BLOCK_PISTON) && (blockType != E_BLOCK_STICKY_PISTON) && (blockType != E_BLOCK_PISTON_EXTENSION))
-		{
-			BlockHandler(blockType)->OnBroken(ChunkInterface, *m_World, a_BlockPos, blockType, blockMeta);
-		}
+		BlockHandler(blockType)->OnBroken(ChunkInterface, *m_World, a_BlockPos, blockType, blockMeta);
 
 		chunk->SetBlock(relPos, a_BlockType, a_BlockMeta);
 		m_World->GetSimulatorManager()->WakeUp(a_BlockPos, chunk);
-- 
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