Paper/patches/server/0677-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on disk, even if outdated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 140d6e455c1729f6e31e95facba5520b75ad838c..169e375c814ff814d15101d09dccc67783f50465 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
@@ -420,6 +420,7 @@ public class RegionFile implements AutoCloseable {
 
     }
 
+    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 {
 
         private final ChunkPos pos;
@@ -433,6 +434,23 @@ public class RegionFile implements AutoCloseable {
             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 b5b7b73048eaadfe58961631427da7574d42f5e8..fa086a19f038b929f356292b2f657929765f7b6f 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
@@ -145,10 +145,17 @@ public class RegionFileStorage implements AutoCloseable {
 
             try {
                 NbtIo.write(nbt, (DataOutput) dataoutputstream);
+                // Paper start - don't write garbage data to disk if writing serialization fails
+                dataoutputstream.close(); // Only write if successful
+            } catch (final RegionFileSizeException e) {
+                attempts = 5; // Don't retry
+                regionfile.clear(pos);
+                throw e;
+                // 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);
                     }
@@ -156,10 +163,7 @@ public class RegionFileStorage implements AutoCloseable {
 
                 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
         }
         // Paper start - Chunk save reattempt
                 return;
@@ -202,4 +206,13 @@ public class RegionFileStorage implements AutoCloseable {
         }
 
     }
+
+    // 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
 }