From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Spottedleaf Date: Thu, 11 Jun 2020 17:29:42 -0700 Subject: [PATCH] Fix piston physics inconsistency - MC-188840 Pistons invoke physics when they move blocks. The physics can cause tnt blocks to ignite. However, pistons (when storing the blocks they "moved") don't actually go back to the world state sometimes to check if something like that happened. As a result they end up moving the tnt like it was never ignited. This resulted in the ability to create machines that can duplicate tnt, called "world eaters". This patch makes the piston logic retrieve the block state from the world prevent this from occuring. This patch also sets the moved pos to air immediately after creating the moving piston TE. This prevents the block from being updated from other physics calls by the piston. Tested against the following tnt duper design: https://www.youtube.com/watch?v=mS7xxNGhjxs This patch also affects every type of machine that utilises this mechanic. For example, dead coral is removed by a physics update when being moved while it is attached to slimeblocks. Standard piston machines that don't destroy or modify the blocks they move by physics updates should be entirely unaffected. This patch fixes https://bugs.mojang.com/browse/MC-188840 This patch also fixes rail duping and carpet duping. diff --git a/src/main/java/com/destroystokyo/paper/PaperConfig.java b/src/main/java/com/destroystokyo/paper/PaperConfig.java index f2f0b9f011bf5b5aa7d80c605cc885104bb934f8..56e4359ba32339e1bef58061585ff3e12e4215f3 100644 --- a/src/main/java/com/destroystokyo/paper/PaperConfig.java +++ b/src/main/java/com/destroystokyo/paper/PaperConfig.java @@ -429,4 +429,10 @@ public class PaperConfig { consoleHasAllPermissions = getBoolean("settings.console-has-all-permissions", consoleHasAllPermissions); } + public static boolean allowPistonDuplication; + private static void allowPistonDuplication() { + config.set("settings.unsupported-settings.allow-piston-duplication-readme", "This setting controls if player should be able to use TNT duplication, but this also allows duplicating carpet, rails and potentially other items"); + allowPistonDuplication = getBoolean("settings.unsupported-settings.allow-piston-duplication", config.getBoolean("settings.unsupported-settings.allow-tnt-duplication", false)); + set("settings.unsupported-settings.allow-tnt-duplication", null); + } } diff --git a/src/main/java/net/minecraft/server/BlockPiston.java b/src/main/java/net/minecraft/server/BlockPiston.java index 6b1253fe7e8d4bb71d4d19c063d3e84c167c4d7b..c3133814f1349b2f70b12967b1b5abc88f71f98c 100644 --- a/src/main/java/net/minecraft/server/BlockPiston.java +++ b/src/main/java/net/minecraft/server/BlockPiston.java @@ -368,12 +368,24 @@ public class BlockPiston extends BlockDirectional { } for (k = list.size() - 1; k >= 0; --k) { - blockposition3 = (BlockPosition) list.get(k); - iblockdata1 = world.getType(blockposition3); + // Paper start - fix a variety of piston desync dupes + boolean allowDesync = com.destroystokyo.paper.PaperConfig.allowPistonDuplication; + BlockPosition oldPos = blockposition3 = (BlockPosition) list.get(k); + iblockdata1 = allowDesync ? world.getType(oldPos) : null; + // Paper end - fix a variety of piston desync dupes blockposition3 = blockposition3.shift(enumdirection1); map.remove(blockposition3); world.setTypeAndData(blockposition3, (IBlockData) Blocks.MOVING_PISTON.getBlockData().set(BlockPiston.FACING, enumdirection), 68); - world.setTileEntity(blockposition3, BlockPistonMoving.a((IBlockData) list1.get(k), enumdirection, flag, false)); + // Paper start - fix a variety of piston desync dupes + if (!allowDesync) { + iblockdata1 = world.getType(oldPos); + map.replace(oldPos, iblockdata1); + } + world.setTileEntity(blockposition3, BlockPistonMoving.a(allowDesync ? list1.get(k) : iblockdata1, enumdirection, flag, false)); + if (!allowDesync) { + world.setTypeAndData(oldPos, Blocks.AIR.getBlockData(), 2 | 4 | 16 | 1024); // set air to prevent later physics updates from seeing this block + } + // Paper end - fix a variety of piston desync dupes aiblockdata[j++] = iblockdata1; } diff --git a/src/main/java/net/minecraft/server/TileEntityPiston.java b/src/main/java/net/minecraft/server/TileEntityPiston.java index 5b941321a7fdc561e6b794a1dce5d600083c505d..e7b7e468fc874b0fbcd43f87d816a42420f9b05e 100644 --- a/src/main/java/net/minecraft/server/TileEntityPiston.java +++ b/src/main/java/net/minecraft/server/TileEntityPiston.java @@ -256,7 +256,7 @@ public class TileEntityPiston extends TileEntity implements ITickable { IBlockData iblockdata = Block.b(this.a, (GeneratorAccess) this.world, this.position); if (iblockdata.isAir()) { - this.world.setTypeAndData(this.position, this.a, 84); + this.world.setTypeAndData(this.position, this.a, com.destroystokyo.paper.PaperConfig.allowPistonDuplication ? 84 : (84 | 2)); // Paper - force notify (flag 2), it's possible the set type by the piston block (which doesn't notify) set this block to air Block.a(this.a, iblockdata, this.world, this.position, 3); } else { if (iblockdata.b(BlockProperties.C) && (Boolean) iblockdata.get(BlockProperties.C)) {