From beb5d72299b93088f62a36e9d9cc01fb48465e14 Mon Sep 17 00:00:00 2001
From: "Dylan K. Taylor" <odigiman@gmail.com>
Date: Sat, 29 Dec 2018 00:02:54 +0000
Subject: [PATCH] RegionLoader: fix off-by-one bug with large chunks, closes
 #2615

---
 .../level/format/io/region/RegionLoader.php   |  2 +-
 .../format/io/region/RegionLoaderTest.php     | 52 +++++++++++++++++++
 2 files changed, 53 insertions(+), 1 deletion(-)
 create mode 100644 tests/phpunit/level/format/io/region/RegionLoaderTest.php

diff --git a/src/pocketmine/level/format/io/region/RegionLoader.php b/src/pocketmine/level/format/io/region/RegionLoader.php
index a8400f527..15b868bf1 100644
--- a/src/pocketmine/level/format/io/region/RegionLoader.php
+++ b/src/pocketmine/level/format/io/region/RegionLoader.php
@@ -33,7 +33,7 @@ class RegionLoader{
 	public const COMPRESSION_GZIP = 1;
 	public const COMPRESSION_ZLIB = 2;
 
-	public const MAX_SECTOR_LENGTH = 256 << 12; //256 sectors, (1 MiB)
+	public const MAX_SECTOR_LENGTH = 255 << 12; //255 sectors (~0.996 MiB)
 	public const REGION_HEADER_LENGTH = 8192; //4096 location table + 4096 timestamps
 
 	public static $COMPRESSION_LEVEL = 7;
diff --git a/tests/phpunit/level/format/io/region/RegionLoaderTest.php b/tests/phpunit/level/format/io/region/RegionLoaderTest.php
new file mode 100644
index 000000000..279439c0b
--- /dev/null
+++ b/tests/phpunit/level/format/io/region/RegionLoaderTest.php
@@ -0,0 +1,52 @@
+<?php
+
+/*
+ *
+ *  ____            _        _   __  __ _                  __  __ ____
+ * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \
+ * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
+ * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/
+ * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_|
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * @author PocketMine Team
+ * @link http://www.pocketmine.net/
+ *
+ *
+*/
+
+declare(strict_types=1);
+
+namespace pocketmine\level\format\io\region;
+
+use PHPUnit\Framework\TestCase;
+use pocketmine\level\format\ChunkException;
+
+class RegionLoaderTest extends TestCase{
+
+	public function testChunkTooBig() : void{
+		$r = new RegionLoader(sys_get_temp_dir() . '/chunk_too_big.testregion_' . bin2hex(random_bytes(4)), 0, 0);
+		$r->open();
+
+		$this->expectException(ChunkException::class);
+		$r->writeChunk(0, 0, str_repeat("a", 1044476));
+	}
+
+	public function testChunkMaxSize() : void{
+		$data = str_repeat("a", 1044475);
+		$path = sys_get_temp_dir() . '/chunk_just_fits.testregion_' . bin2hex(random_bytes(4));
+		$r = new RegionLoader($path, 0, 0);
+		$r->open();
+
+		$r->writeChunk(0, 0, $data);
+		$r->close();
+
+		$r = new RegionLoader($path, 0, 0);
+		$r->open();
+		self::assertSame($data, $r->readChunk(0, 0));
+	}
+}