14 files changed, 129 insertions, 49 deletions

diff --git a/src/Blocks/BlockPiston.cpp b/src/Blocks/BlockPiston.cpp
index 124757b44..568e2eaa5 100644
--- a/src/Blocks/BlockPiston.cpp
+++ b/src/Blocks/BlockPiston.cpp
@@ -48,8 +48,12 @@ void cBlockPistonHandler::ExtendPiston(Vector3i a_BlockPos, cWorld & a_World)
 
 		BLOCKTYPE pistonBlock;
 		NIBBLETYPE pistonMeta;
-		a_World.GetBlockTypeMeta(a_BlockPos, pistonBlock, pistonMeta);
-		a_World.BroadcastBlockAction(a_BlockPos, PistonExtendAction, pistonMeta, pistonBlock);
+		if (a_World.GetBlockTypeMeta(a_BlockPos, pistonBlock, pistonMeta))
+		{
+			a_World.BroadcastBlockAction(
+				a_BlockPos, PistonExtendAction, pistonMeta, pistonBlock
+			);
+		}
 	}
 
 	// Client expects the server to "play" the animation before setting the final blocks
@@ -60,9 +64,12 @@ void cBlockPistonHandler::ExtendPiston(Vector3i a_BlockPos, cWorld & a_World)
 		{
 			BLOCKTYPE pistonBlock;
 			NIBBLETYPE pistonMeta;
-			World.GetBlockTypeMeta(a_BlockPos, pistonBlock, pistonMeta);
 
-			if ((pistonBlock != E_BLOCK_PISTON) && !IsSticky(pistonBlock))
+
+			if (
+				!World.GetBlockTypeMeta(a_BlockPos, pistonBlock, pistonMeta) ||
+				((pistonBlock != E_BLOCK_PISTON) && !IsSticky(pistonBlock))
+			)
 			{
 				// Ensure we operate on a piston to avoid spurious behaviour
 				// Note that the scheduled task may result in the block type of a_BlockPos changing
@@ -104,17 +111,23 @@ void cBlockPistonHandler::RetractPiston(Vector3i a_BlockPos, cWorld & a_World)
 	{
 		BLOCKTYPE pistonBlock;
 		NIBBLETYPE pistonMeta;
-		a_World.GetBlockTypeMeta(a_BlockPos, pistonBlock, pistonMeta);
-		a_World.BroadcastBlockAction(a_BlockPos, PistonRetractAction, pistonMeta, pistonBlock);
+		if (a_World.GetBlockTypeMeta(a_BlockPos, pistonBlock, pistonMeta))
+		{
+			a_World.BroadcastBlockAction(
+				a_BlockPos, PistonRetractAction, pistonMeta, pistonBlock
+			);
+		}
 	}
 
 	a_World.ScheduleTask(1_tick, [a_BlockPos](cWorld & World)
 		{
 			BLOCKTYPE pistonBlock;
 			NIBBLETYPE pistonMeta;
-			World.GetBlockTypeMeta(a_BlockPos, pistonBlock, pistonMeta);
 
-			if ((pistonBlock != E_BLOCK_PISTON) && !IsSticky(pistonBlock))
+			if (
+				!World.GetBlockTypeMeta(a_BlockPos, pistonBlock, pistonMeta) ||
+				((pistonBlock != E_BLOCK_PISTON) && !IsSticky(pistonBlock))
+			)
 			{
 				// Ensure we operate on a piston to avoid spurious behaviour
 				// Note that the scheduled task may result in the block type of a_BlockPos changing
@@ -189,19 +202,20 @@ void cBlockPistonHandler::PushBlocks(
 	NIBBLETYPE moveMeta;
 	for (auto & moveBlockPos : sortedBlocks)
 	{
-		a_World.GetBlockTypeMeta(moveBlockPos, moveBlock, moveMeta);
-
-		if (cBlockInfo::IsPistonBreakable(moveBlock))
-		{
-			// Block is breakable, drop it:
-			a_World.DropBlockAsPickups(moveBlockPos, nullptr, nullptr);
-		}
-		else
+		if (a_World.GetBlockTypeMeta(moveBlockPos, moveBlock, moveMeta))
 		{
-			// Not breakable, just move it
-			a_World.SetBlock(moveBlockPos, E_BLOCK_AIR, 0);
-			moveBlockPos += a_PushDir;
-			a_World.SetBlock(moveBlockPos, moveBlock, moveMeta);
+			if (cBlockInfo::IsPistonBreakable(moveBlock))
+			{
+				// Block is breakable, drop it:
+				a_World.DropBlockAsPickups(moveBlockPos, nullptr, nullptr);
+			}
+			else
+			{
+				// Not breakable, just move it
+				a_World.SetBlock(moveBlockPos, E_BLOCK_AIR, 0);
+				moveBlockPos += a_PushDir;
+				a_World.SetBlock(moveBlockPos, moveBlock, moveMeta);
+			}
 		}
 	}
 }
@@ -232,7 +246,10 @@ bool cBlockPistonHandler::CanPushBlock(
 
 	BLOCKTYPE currBlock;
 	NIBBLETYPE currMeta;
-	a_World.GetBlockTypeMeta(a_BlockPos, currBlock, currMeta);
+	if (!a_World.GetBlockTypeMeta(a_BlockPos, currBlock, currMeta))
+	{
+		return !a_RequirePushable;
+	}
 
 	if (currBlock == E_BLOCK_AIR)
 	{
diff --git a/src/ChunkMap.cpp b/src/ChunkMap.cpp
index a2bc50fe9..d982d0cf3 100644
--- a/src/ChunkMap.cpp
+++ b/src/ChunkMap.cpp
@@ -474,6 +474,11 @@ void cChunkMap::CollectPickupsByEntity(cEntity & a_Entity)
 
 BLOCKTYPE cChunkMap::GetBlock(Vector3i a_BlockPos) const
 {
+	if (!cChunkDef::IsValidHeight(a_BlockPos))
+	{
+		return 0;
+	}
+
 	auto chunkPos = cChunkDef::BlockToChunk(a_BlockPos);
 	auto relPos = cChunkDef::AbsoluteToRelative(a_BlockPos, chunkPos);
 
@@ -493,6 +498,11 @@ BLOCKTYPE cChunkMap::GetBlock(Vector3i a_BlockPos) const
 
 NIBBLETYPE cChunkMap::GetBlockMeta(Vector3i a_BlockPos) const
 {
+	if (!cChunkDef::IsValidHeight(a_BlockPos))
+	{
+		return 0;
+	}
+
 	auto chunkPos = cChunkDef::BlockToChunk(a_BlockPos);
 	auto relPos = cChunkDef::AbsoluteToRelative(a_BlockPos, chunkPos);
 
@@ -585,6 +595,14 @@ void cChunkMap::SetBlock(Vector3i a_BlockPos, BLOCKTYPE a_BlockType, NIBBLETYPE
 
 bool cChunkMap::GetBlockTypeMeta(Vector3i a_BlockPos, BLOCKTYPE & a_BlockType, NIBBLETYPE & a_BlockMeta) const
 {
+	if (!cChunkDef::IsValidHeight(a_BlockPos))
+	{
+		// Initialise the params to fulfil our contract.
+		a_BlockType = 0;
+		a_BlockMeta = 0;
+		return false;
+	}
+
 	auto chunkCoord = cChunkDef::BlockToChunk(a_BlockPos);
 	auto relPos = cChunkDef::AbsoluteToRelative(a_BlockPos, chunkCoord);
 
@@ -595,6 +613,10 @@ bool cChunkMap::GetBlockTypeMeta(Vector3i a_BlockPos, BLOCKTYPE & a_BlockType, N
 		Chunk->GetBlockTypeMeta(relPos, a_BlockType, a_BlockMeta);
 		return true;
 	}
+
+	// Initialise the params to fulfil our contract.
+	a_BlockType = 0;
+	a_BlockMeta = 0;
 	return false;
 }
 
diff --git a/src/ChunkMap.h b/src/ChunkMap.h
index 578c49b8a..8538b7624 100644
--- a/src/ChunkMap.h
+++ b/src/ChunkMap.h
@@ -115,6 +115,10 @@ public:
 	void SetBlockMeta(Vector3i a_BlockPos, NIBBLETYPE a_BlockMeta);
 
 	void SetBlock          (Vector3i a_BlockPos, BLOCKTYPE a_BlockType, NIBBLETYPE a_BlockMeta);
+	/** Get the block type and meta at the specified coords
+	Will always initialise a_BlockType and a_BlockMeta if called.
+	Returns false if the data could not be retrieved, either because the chunk is invalid or the height is invalid.
+	Otherwise, returns true. */
 	bool GetBlockTypeMeta  (Vector3i a_BlockPos, BLOCKTYPE & a_BlockType, NIBBLETYPE & a_BlockMeta) const;
 	bool GetBlockInfo      (Vector3i, BLOCKTYPE & a_BlockType, NIBBLETYPE & a_Meta, NIBBLETYPE & a_SkyLight, NIBBLETYPE & a_BlockLight) const;
 
diff --git a/src/ClientHandle.cpp b/src/ClientHandle.cpp
index 01c95095a..2b32c5c07 100644
--- a/src/ClientHandle.cpp
+++ b/src/ClientHandle.cpp
@@ -1254,7 +1254,10 @@ void cClientHandle::HandleBlockDigStarted(Vector3i a_BlockPos, eBlockFace a_Bloc
 
 	BLOCKTYPE DiggingBlock;
 	NIBBLETYPE DiggingMeta;
-	m_Player->GetWorld()->GetBlockTypeMeta(a_BlockPos, DiggingBlock, DiggingMeta);
+	if (!m_Player->GetWorld()->GetBlockTypeMeta(a_BlockPos, DiggingBlock, DiggingMeta))
+	{
+		return;
+	}
 
 	if (
 		m_Player->IsGameModeCreative() &&
@@ -1322,7 +1325,10 @@ void cClientHandle::HandleBlockDigFinished(Vector3i a_BlockPos, eBlockFace a_Blo
 
 	BLOCKTYPE DugBlock;
 	NIBBLETYPE DugMeta;
-	m_Player->GetWorld()->GetBlockTypeMeta(a_BlockPos, DugBlock, DugMeta);
+	if (!m_Player->GetWorld()->GetBlockTypeMeta(a_BlockPos, DugBlock, DugMeta))
+	{
+		return;
+	}
 
 	if (!m_Player->IsGameModeCreative())
 	{
diff --git a/src/Entities/Player.cpp b/src/Entities/Player.cpp
index de99a299d..50fd034a5 100644
--- a/src/Entities/Player.cpp
+++ b/src/Entities/Player.cpp
@@ -2594,9 +2594,10 @@ bool cPlayer::IsInsideWater()
 
 	BLOCKTYPE Block;
 	NIBBLETYPE Meta;
-	m_World->GetBlockTypeMeta(EyePos, Block, Meta);
-
-	if ((Block != E_BLOCK_WATER) && (Block != E_BLOCK_STATIONARY_WATER))
+	if (
+		!m_World->GetBlockTypeMeta(GetEyePosition().Floor(), Block, Meta) ||
+		((Block != E_BLOCK_WATER) && (Block != E_BLOCK_STATIONARY_WATER))
+	)
 	{
 		return false;
 	}
diff --git a/src/Items/ItemBed.h b/src/Items/ItemBed.h
index a2e254171..77818e7c7 100644
--- a/src/Items/ItemBed.h
+++ b/src/Items/ItemBed.h
@@ -27,7 +27,10 @@ public:
 		auto & World = *a_Player.GetWorld();
 		BLOCKTYPE HeadType;
 		NIBBLETYPE HeadMeta;
-		World.GetBlockTypeMeta(HeadPosition, HeadType, HeadMeta);
+		if (!World.GetBlockTypeMeta(HeadPosition, HeadType, HeadMeta))
+		{
+			return false;
+		}
 
 		// Vanilla only allows beds to be placed into air.
 		// Check if there is empty space for the "head" block:
diff --git a/src/Items/ItemBigFlower.h b/src/Items/ItemBigFlower.h
index cbdecbed7..a135a220d 100644
--- a/src/Items/ItemBigFlower.h
+++ b/src/Items/ItemBigFlower.h
@@ -29,7 +29,10 @@ public:
 		const auto TopPos = a_PlacePosition.addedY(1);
 		BLOCKTYPE TopType;
 		NIBBLETYPE TopMeta;
-		World.GetBlockTypeMeta(TopPos, TopType, TopMeta);
+		if (!World.GetBlockTypeMeta(TopPos, TopType, TopMeta))
+		{
+			return false;
+		}
 
 		if (!cBlockHandler::For(TopType).DoesIgnoreBuildCollision(World, a_HeldItem, TopPos, TopMeta, a_ClickedBlockFace, false))
 		{
diff --git a/src/Items/ItemDoor.h b/src/Items/ItemDoor.h
index 6538a5bef..f28d3ad36 100644
--- a/src/Items/ItemDoor.h
+++ b/src/Items/ItemDoor.h
@@ -54,7 +54,10 @@ public:
 		{
 			BLOCKTYPE TopType;
 			NIBBLETYPE TopMeta;
-			World.GetBlockTypeMeta(UpperBlockPosition, TopType, TopMeta);
+			if (!World.GetBlockTypeMeta(UpperBlockPosition, TopType, TopMeta))
+			{
+				return false;
+			}
 
 			if (!cBlockHandler::For(TopType).DoesIgnoreBuildCollision(World, a_HeldItem, UpperBlockPosition, TopMeta, a_ClickedBlockFace, false))
 			{
diff --git a/src/Items/ItemDye.h b/src/Items/ItemDye.h
index 636a1b477..b0f00b9ba 100644
--- a/src/Items/ItemDye.h
+++ b/src/Items/ItemDye.h
@@ -54,10 +54,12 @@ public:
 			// Cocoa (brown dye) can be planted on jungle logs:
 			BLOCKTYPE BlockType;
 			NIBBLETYPE BlockMeta;
-			a_World->GetBlockTypeMeta(a_ClickedBlockPos, BlockType, BlockMeta);
 
 			// Check if the block that the player clicked is a jungle log.
-			if ((BlockType != E_BLOCK_LOG) || ((BlockMeta & 0x03) != E_META_LOG_JUNGLE))
+			if (
+				!a_World->GetBlockTypeMeta(a_ClickedBlockPos, BlockType, BlockMeta) ||
+				((BlockType != E_BLOCK_LOG) || ((BlockMeta & 0x03) != E_META_LOG_JUNGLE))
+			)
 			{
 				return false;
 			}
diff --git a/src/Items/ItemEyeOfEnder.h b/src/Items/ItemEyeOfEnder.h
index fc6fac336..414d81c39 100644
--- a/src/Items/ItemEyeOfEnder.h
+++ b/src/Items/ItemEyeOfEnder.h
@@ -35,8 +35,8 @@ public:
 		{
 			BLOCKTYPE FacingBlock;
 			NIBBLETYPE FacingMeta;
-			a_World->GetBlockTypeMeta(a_ClickedBlockPos, FacingBlock, FacingMeta);
-			if (FacingBlock == E_BLOCK_END_PORTAL_FRAME)
+
+			if (a_World->GetBlockTypeMeta(a_ClickedBlockPos, FacingBlock, FacingMeta) && (FacingBlock == E_BLOCK_END_PORTAL_FRAME))
 			{
 				// Fill the portal frame. E_META_END_PORTAL_EYE is the bit for holding the eye of ender.
 				if ((FacingMeta & E_META_END_PORTAL_FRAME_EYE) != E_META_END_PORTAL_FRAME_EYE)
diff --git a/src/Items/ItemHoe.h b/src/Items/ItemHoe.h
index 2bca5f5ca..503047328 100644
--- a/src/Items/ItemHoe.h
+++ b/src/Items/ItemHoe.h
@@ -46,7 +46,10 @@ public:
 		// Can only transform dirt or grass blocks:
 		BLOCKTYPE BlockType;
 		NIBBLETYPE BlockMeta;
-		a_World->GetBlockTypeMeta(a_ClickedBlockPos, BlockType, BlockMeta);
+		if (!a_World->GetBlockTypeMeta(a_ClickedBlockPos, BlockType, BlockMeta))
+		{
+			return false;
+		}
 		if ((BlockType != E_BLOCK_DIRT) && (BlockType != E_BLOCK_GRASS))
 		{
 			return false;
diff --git a/src/Items/ItemShears.h b/src/Items/ItemShears.h
index 5f8e9e2f1..00504884c 100644
--- a/src/Items/ItemShears.h
+++ b/src/Items/ItemShears.h
@@ -32,7 +32,10 @@ public:
 	{
 		BLOCKTYPE Block;
 		NIBBLETYPE BlockMeta;
-		a_World->GetBlockTypeMeta(a_ClickedBlockPos, Block, BlockMeta);
+		if (!a_World->GetBlockTypeMeta(a_ClickedBlockPos, Block, BlockMeta))
+		{
+			return false;
+		}
 
 		if ((Block == E_BLOCK_LEAVES) || (Block == E_BLOCK_NEW_LEAVES))
 		{
diff --git a/src/UI/SlotArea.cpp b/src/UI/SlotArea.cpp
index 4085dc816..ef5f7382e 100644
--- a/src/UI/SlotArea.cpp
+++ b/src/UI/SlotArea.cpp
@@ -1065,9 +1065,12 @@ void cSlotAreaAnvil::OnTakeResult(cPlayer & a_Player)
 
 	BLOCKTYPE Block;
 	NIBBLETYPE BlockMeta;
-	a_Player.GetWorld()->GetBlockTypeMeta(BlockPos, Block, BlockMeta);
 
-	if (!a_Player.IsGameModeCreative() && (Block == E_BLOCK_ANVIL) && GetRandomProvider().RandBool(0.12))
+	if (
+		a_Player.GetWorld()->GetBlockTypeMeta(BlockPos, Block, BlockMeta) &&
+		!a_Player.IsGameModeCreative() && (Block == E_BLOCK_ANVIL) &&
+		GetRandomProvider().RandBool(0.12)
+	)
 	{
 		NIBBLETYPE Orientation = BlockMeta & 0x3;
 		NIBBLETYPE AnvilDamage = BlockMeta >> 2;
diff --git a/src/World.cpp b/src/World.cpp
index 2f92020bf..781d44c3a 100644
--- a/src/World.cpp
+++ b/src/World.cpp
@@ -1539,8 +1539,7 @@ bool cWorld::GetLargeTreeAdjustment(Vector3i & a_BlockPos, NIBBLETYPE a_Meta)
 		{
 			NIBBLETYPE meta;
 			BLOCKTYPE type;
-			GetBlockTypeMeta(a_BlockPos.addedXZ(x, z), type, meta);
-			IsLarge = IsLarge && (type == E_BLOCK_SAPLING) && ((meta & 0x07) == a_Meta);
+			IsLarge = IsLarge && GetBlockTypeMeta(a_BlockPos.addedXZ(x, z), type, meta) && (type == E_BLOCK_SAPLING) && ((meta & 0x07) == a_Meta);
 		}
 	}
 
@@ -1557,8 +1556,7 @@ bool cWorld::GetLargeTreeAdjustment(Vector3i & a_BlockPos, NIBBLETYPE a_Meta)
 		{
 			NIBBLETYPE meta;
 			BLOCKTYPE type;
-			GetBlockTypeMeta(a_BlockPos.addedXZ(x, z), type, meta);
-			IsLarge = IsLarge && (type == E_BLOCK_SAPLING) && ((meta & 0x07) == a_Meta);
+			IsLarge = IsLarge && GetBlockTypeMeta(a_BlockPos.addedXZ(x, z), type, meta) && (type == E_BLOCK_SAPLING) && ((meta & 0x07) == a_Meta);
 		}
 	}
 
@@ -1576,8 +1574,7 @@ bool cWorld::GetLargeTreeAdjustment(Vector3i & a_BlockPos, NIBBLETYPE a_Meta)
 		{
 			NIBBLETYPE meta;
 			BLOCKTYPE type;
-			GetBlockTypeMeta(a_BlockPos.addedXZ(x, z), type, meta);
-			IsLarge = IsLarge && (type == E_BLOCK_SAPLING) && ((meta & 0x07) == a_Meta);
+			IsLarge = IsLarge && GetBlockTypeMeta(a_BlockPos.addedXZ(x, z), type, meta) && (type == E_BLOCK_SAPLING) && ((meta & 0x07) == a_Meta);
 		}
 	}
 
@@ -1596,8 +1593,7 @@ bool cWorld::GetLargeTreeAdjustment(Vector3i & a_BlockPos, NIBBLETYPE a_Meta)
 		{
 			NIBBLETYPE meta;
 			BLOCKTYPE type;
-			GetBlockTypeMeta(a_BlockPos.addedXZ(x, z), type, meta);
-			IsLarge = IsLarge && (type == E_BLOCK_SAPLING) && ((meta & 0x07) == a_Meta);
+			IsLarge = IsLarge && GetBlockTypeMeta(a_BlockPos.addedXZ(x, z), type, meta) && (type == E_BLOCK_SAPLING) && ((meta & 0x07) == a_Meta);
 		}
 	}
 
@@ -2044,7 +2040,10 @@ void cWorld::PlaceBlock(const Vector3i a_Position, const BLOCKTYPE a_BlockType,
 {
 	BLOCKTYPE BlockType;
 	NIBBLETYPE BlockMeta;
-	GetBlockTypeMeta(a_Position, BlockType, BlockMeta);
+	if (!GetBlockTypeMeta(a_Position, BlockType, BlockMeta))
+	{
+		return;
+	}
 
 	SetBlock(a_Position, a_BlockType, a_BlockMeta);
 
@@ -2070,7 +2069,10 @@ bool cWorld::DigBlock(Vector3i a_BlockPos, const cEntity * a_Digger)
 {
 	BLOCKTYPE BlockType;
 	NIBBLETYPE BlockMeta;
-	GetBlockTypeMeta(a_BlockPos, BlockType, BlockMeta);
+	if (!GetBlockTypeMeta(a_BlockPos, BlockType, BlockMeta))
+	{
+		return false;
+	}
 
 	if (!m_ChunkMap.DigBlock(a_BlockPos))
 	{
@@ -2617,7 +2619,11 @@ bool cWorld::IsTrapdoorOpen(int a_BlockX, int a_BlockY, int a_BlockZ)
 {
 	BLOCKTYPE Block;
 	NIBBLETYPE Meta;
-	GetBlockTypeMeta({ a_BlockX, a_BlockY, a_BlockZ }, Block, Meta);
+	if (!GetBlockTypeMeta({ a_BlockX, a_BlockY, a_BlockZ }, Block, Meta))
+	{
+		return false;
+	}
+
 	if ((Block != E_BLOCK_TRAPDOOR) && (Block != E_BLOCK_IRON_TRAPDOOR))
 	{
 		return false;
@@ -2634,7 +2640,11 @@ bool cWorld::SetTrapdoorOpen(int a_BlockX, int a_BlockY, int a_BlockZ, bool a_Op
 {
 	BLOCKTYPE Block;
 	NIBBLETYPE Meta;
-	GetBlockTypeMeta({ a_BlockX, a_BlockY, a_BlockZ }, Block, Meta);
+	if (!GetBlockTypeMeta({ a_BlockX, a_BlockY, a_BlockZ }, Block, Meta))
+	{
+		return false;
+	}
+
 	if ((Block != E_BLOCK_TRAPDOOR) && (Block != E_BLOCK_IRON_TRAPDOOR))
 	{
 		return false;