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 edfa4a27a18b5c9df75f3952c51acdde1faa6dde..a545a882335094daa787ec5c7005939080195263 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 ebd8a234acf42f8d6ae0790bb6a60a214d22429f..2e95de4250f3b53591749ebbe7a5f2b607f6b7fa 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 @@ -410,14 +410,26 @@ 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 78d252b829e5c1f19532656a728620852403760c..613db573cef142e0ab1b24dc994677105a253042 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)) {