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 62a0f6772bacfb8ad90c15493e0d48e29b70fac1..c639557108ad9c59ccdd0b543b5507fbab1e0fa4 100644 --- a/src/main/java/com/destroystokyo/paper/PaperConfig.java +++ b/src/main/java/com/destroystokyo/paper/PaperConfig.java @@ -451,4 +451,12 @@ public class PaperConfig { private static void consoleHasAllPermissions() { 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/world/level/block/piston/PistonBaseBlock.java b/src/main/java/net/minecraft/world/level/block/piston/PistonBaseBlock.java index 272279244f558c8ea298b35605c0421c037aad48..053bb85355c1b0fd93477187f4cedc582c6a480b 100644 --- a/src/main/java/net/minecraft/world/level/block/piston/PistonBaseBlock.java +++ b/src/main/java/net/minecraft/world/level/block/piston/PistonBaseBlock.java @@ -411,14 +411,26 @@ public class PistonBaseBlock extends DirectionalBlock { } for (k = list.size() - 1; k >= 0; --k) { - blockposition3 = (BlockPos) list.get(k); - iblockdata1 = world.getBlockState(blockposition3); + // Paper start - fix a variety of piston desync dupes + boolean allowDesync = com.destroystokyo.paper.PaperConfig.allowPistonDuplication; + BlockPos oldPos = blockposition3 = (BlockPos) list.get(k); + iblockdata1 = allowDesync ? world.getBlockState(oldPos) : null; + // Paper end - fix a variety of piston desync dupes blockposition3 = blockposition3.relative(enumdirection1); map.remove(blockposition3); BlockState iblockdata2 = (BlockState) Blocks.MOVING_PISTON.defaultBlockState().setValue(PistonBaseBlock.FACING, dir); world.setBlock(blockposition3, iblockdata2, 68); - world.setBlockEntity(MovingPistonBlock.newMovingBlockEntity(blockposition3, iblockdata2, (BlockState) list1.get(k), dir, retract, false)); + // Paper start - fix a variety of piston desync dupes + if (!allowDesync) { + iblockdata1 = world.getBlockState(oldPos); + map.replace(oldPos, iblockdata1); + } + world.setBlockEntity(MovingPistonBlock.newMovingBlockEntity(blockposition3, iblockdata2, allowDesync ? list1.get(k) : iblockdata1, dir, retract, false)); + if (!allowDesync) { + world.setBlock(oldPos, Blocks.AIR.defaultBlockState(), 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/world/level/block/piston/PistonMovingBlockEntity.java b/src/main/java/net/minecraft/world/level/block/piston/PistonMovingBlockEntity.java index dda0b32a4989bbead35a2219a969a30ba0e975b0..94bd47212b05f66ebc81966eec3bc0abda76252c 100644 --- a/src/main/java/net/minecraft/world/level/block/piston/PistonMovingBlockEntity.java +++ b/src/main/java/net/minecraft/world/level/block/piston/PistonMovingBlockEntity.java @@ -285,7 +285,7 @@ public class PistonMovingBlockEntity extends BlockEntity { if (world.getBlockState(pos).is(Blocks.MOVING_PISTON)) { BlockState blockState = Block.updateFromNeighbourShapes(blockEntity.movedState, world, pos); if (blockState.isAir()) { - world.setBlock(pos, blockEntity.movedState, 84); + world.setBlock(pos, blockEntity.movedState, 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.updateOrDestroy(blockEntity.movedState, blockState, world, pos, 3); } else { if (blockState.hasProperty(BlockStateProperties.WATERLOGGED) && blockState.getValue(BlockStateProperties.WATERLOGGED)) {