Protect BlockSnapshot and Chunk.getTileEntity from mutible BlockPos instances. Closes #2438

patches/minecraft/net/minecraft/util/BlockPos.java.patch

@@ -0,0 +1,32 @@
+--- ../src-base/minecraft/net/minecraft/util/BlockPos.java
++++ ../src-work/minecraft/net/minecraft/util/BlockPos.java
+@@ -257,6 +257,21 @@
+         };
+     }
+ 
++    /**
++     * Returns a version of this BlockPos that is guaranteed to be Immutable.
++     * In most cases this will return 'this', but if 'this' is an instance of
++     * MutableBlockPos it will return a new instance of BlockPos with the same values.
++     *
++     * When storing a parameter given to you for an extended period of time, make sure you
++     * use this in case the value is changed internally.
++     *
++     * @return An immutable BlockPos.
++     */
++    public BlockPos getImmutable()
++    {
++        return this;
++    }
++
+     public static final class MutableBlockPos extends BlockPos
+         {
+             private int field_177997_b;
+@@ -298,5 +313,7 @@
+                 this.field_177996_d = p_181079_3_;
+                 return this;
+             }
++
++            @Override public BlockPos getImmutable() { return new BlockPos(this); }
+         }
+ }

patches/minecraft/net/minecraft/world/chunk/Chunk.java.patch

@@ -118,8 +118,12 @@
          if (tileentity == null)
          {
              if (p_177424_2_ == Chunk.EnumCreateEntityType.IMMEDIATE)
-@@ -849,11 +852,6 @@
+@@ -846,14 +849,9 @@
-                 this.field_177447_w.add(p_177424_1_);
+             }
+             else if (p_177424_2_ == Chunk.EnumCreateEntityType.QUEUED)
+             {
+-                this.field_177447_w.add(p_177424_1_);
++                this.field_177447_w.add(p_177424_1_.getImmutable());
              }
          }
 -        else if (tileentity.func_145837_r())

src/main/java/net/minecraftforge/common/util/BlockSnapshot.java

@@ -58,7 +58,7 @@ public class BlockSnapshot implements Serializable
     {
         this.world = world;
         this.dimId = world.provider.getDimensionId();
-        this.pos = pos;
+        this.pos = pos.getImmutable();
         this.replacedBlock = state;
         this.blockIdentifier = GameRegistry.findUniqueIdentifierFor(state.getBlock());
         this.meta = state.getBlock().getMetaFromState(state);
@@ -82,7 +82,7 @@ public class BlockSnapshot implements Serializable
     public BlockSnapshot(int dimension, BlockPos pos, String modid, String blockName, int meta, int flag, NBTTagCompound nbt)
     {
         this.dimId = dimension;
-        this.pos = pos;
+        this.pos = pos.getImmutable();
         this.flag = flag;
         this.blockIdentifier = new UniqueIdentifier(modid + ":" + blockName);
         this.meta = meta;