PaperMC/patches/server/1038-Only-write-chunk-data-to-disk-if-it-serializes-witho.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Spottedleaf <Spottedleaf@users.noreply.github.com>
Date: Sun, 19 Dec 2021 09:13:41 -0800
Subject: [PATCH] Only write chunk data to disk if it serializes without
 throwing

This ensures at least a valid version of the chunk exists
on disk, even if outdated

diff --git a/src/main/java/net/minecraft/world/level/chunk/storage/RegionFile.java b/src/main/java/net/minecraft/world/level/chunk/storage/RegionFile.java
index 057875cbbdc92ba49b429f9a129514760edb32a2..ff092c6d0cd436f14a9a4ff5c8ddbb5538d1a8c5 100644
--- a/src/main/java/net/minecraft/world/level/chunk/storage/RegionFile.java
+++ b/src/main/java/net/minecraft/world/level/chunk/storage/RegionFile.java
@@ -539,6 +539,7 @@ public class RegionFile implements AutoCloseable, ca.spottedleaf.moonrise.patche
 
     }
     // Paper end
+    public static final int MAX_CHUNK_SIZE = 500 * 1024 * 1024; // Paper - don't write garbage data to disk if writing serialization fails
     private class ChunkBuffer extends ByteArrayOutputStream implements ca.spottedleaf.moonrise.patches.chunk_system.storage.ChunkSystemChunkBuffer { // Paper - rewrite chunk system
 
         private final ChunkPos pos;
@@ -571,6 +572,23 @@ public class RegionFile implements AutoCloseable, ca.spottedleaf.moonrise.patche
             super.write(RegionFile.this.version.getId());
             this.pos = chunkcoordintpair;
         }
+        // Paper start - don't write garbage data to disk if writing serialization fails
+        @Override
+        public void write(final int b) {
+            if (this.count > MAX_CHUNK_SIZE) {
+                throw new RegionFileStorage.RegionFileSizeException("Region file too large: " + this.count);
+            }
+            super.write(b);
+        }
+
+        @Override
+        public void write(final byte[] b, final int off, final int len) {
+            if (this.count + len > MAX_CHUNK_SIZE) {
+                throw new RegionFileStorage.RegionFileSizeException("Region file too large: " + (this.count + len));
+            }
+            super.write(b, off, len);
+        }
+        // Paper end - don't write garbage data to disk if writing serialization fails
 
         public void close() throws IOException {
             ByteBuffer bytebuffer = ByteBuffer.wrap(this.buf, 0, this.count);
diff --git a/src/main/java/net/minecraft/world/level/chunk/storage/RegionFileStorage.java b/src/main/java/net/minecraft/world/level/chunk/storage/RegionFileStorage.java
index fdf8e18d24442178b52397acb482ffa3306a32e3..8d66d6b7aeb9feb54ebd83f5c73b45d42b9a7034 100644
--- a/src/main/java/net/minecraft/world/level/chunk/storage/RegionFileStorage.java
+++ b/src/main/java/net/minecraft/world/level/chunk/storage/RegionFileStorage.java
@@ -19,6 +19,8 @@ import net.minecraft.world.level.ChunkPos;
 
 public class RegionFileStorage implements AutoCloseable, ca.spottedleaf.moonrise.patches.chunk_system.io.ChunkSystemRegionFileStorage { // Paper - rewrite chunk system
 
+    private static final org.slf4j.Logger LOGGER = com.mojang.logging.LogUtils.getLogger(); // Paper
+
     public static final String ANVIL_EXTENSION = ".mca";
     private static final int MAX_CACHE_SIZE = 256;
     public final Long2ObjectLinkedOpenHashMap<RegionFile> regionCache = new Long2ObjectLinkedOpenHashMap();
@@ -123,11 +125,24 @@ public class RegionFileStorage implements AutoCloseable, ca.spottedleaf.moonrise
         // (and, the regionfile parameter is unused for writing until the write call)
         final ca.spottedleaf.moonrise.patches.chunk_system.io.MoonriseRegionFileIO.RegionDataController.WriteData writeData = ((ca.spottedleaf.moonrise.patches.chunk_system.storage.ChunkSystemRegionFile)regionFile).moonrise$startWrite(compound, pos);
 
+        try { // Paper - implement RegionFileSizeException
         try {
             NbtIo.write(compound, writeData.output());
         } finally {
             writeData.output().close();
         }
+        // Paper start - implement RegionFileSizeException
+        } catch (final RegionFileSizeException ex) {
+            // note: it's OK if close() is called, as close() here will not issue a write to the RegionFile
+            // see startWrite
+            final int maxSize = RegionFile.MAX_CHUNK_SIZE / (1024 * 1024);
+            LOGGER.error("Chunk at (" + chunkX + "," + chunkZ + ") in regionfile '" + regionFile.getPath().toString() + "' exceeds max size of " + maxSize + "MiB, it has been deleted from disk.");
+            return new ca.spottedleaf.moonrise.patches.chunk_system.io.MoonriseRegionFileIO.RegionDataController.WriteData(
+                compound, ca.spottedleaf.moonrise.patches.chunk_system.io.MoonriseRegionFileIO.RegionDataController.WriteData.WriteResult.DELETE,
+                null, null
+            );
+        }
+        // Paper end - implement RegionFileSizeException
 
         return writeData;
     }
@@ -378,10 +393,18 @@ public class RegionFileStorage implements AutoCloseable, ca.spottedleaf.moonrise
             try {
                 NbtIo.write(nbt, (DataOutput) dataoutputstream);
                 regionfile.setOversized(pos.x, pos.z, false); // Paper - We don't do this anymore, mojang stores differently, but clear old meta flag if it exists to get rid of our own meta file once last oversized is gone
+                // Paper start - don't write garbage data to disk if writing serialization fails
+                dataoutputstream.close(); // Only write if successful
+            } catch (final RegionFileSizeException ex) {
+                regionfile.clear(pos);
+                final int maxSize = RegionFile.MAX_CHUNK_SIZE / (1024 * 1024);
+                LOGGER.error("Chunk at (" + pos.x + "," + pos.z + ") in regionfile '" + regionfile.getPath().toString() + "' exceeds max size of " + maxSize + "MiB, it has been deleted from disk.");
+                return;
+                // Paper end - don't write garbage data to disk if writing serialization fails
             } catch (Throwable throwable) {
                 if (dataoutputstream != null) {
                     try {
-                        dataoutputstream.close();
+                        //dataoutputstream.close(); // Paper - don't write garbage data to disk if writing serialization fails
                     } catch (Throwable throwable1) {
                         throwable.addSuppressed(throwable1);
                     }
@@ -389,10 +412,7 @@ public class RegionFileStorage implements AutoCloseable, ca.spottedleaf.moonrise
 
                 throw throwable;
             }
-
-            if (dataoutputstream != null) {
-                dataoutputstream.close();
-            }
+            // Paper - don't write garbage data to disk if writing serialization fails; move into try block to only write if successfully serialized
         }
 
     }
@@ -435,4 +455,13 @@ public class RegionFileStorage implements AutoCloseable, ca.spottedleaf.moonrise
     public RegionStorageInfo info() {
         return this.info;
     }
+
+    // Paper start - don't write garbage data to disk if writing serialization fails
+    public static final class RegionFileSizeException extends RuntimeException {
+
+        public RegionFileSizeException(String message) {
+            super(message);
+        }
+    }
+    // Paper end - don't write garbage data to disk if writing serialization fails
 }