From e3b3f60c669ea413fca775e4487615ddbb229bf4 Mon Sep 17 00:00:00 2001
From: "Dylan K. Taylor" <odigiman@gmail.com>
Date: Sat, 17 Jun 2017 12:22:38 +0100
Subject: [PATCH] Fixed item stack count and effect amplifier overflows, close
 #1072

---
 src/pocketmine/entity/Entity.php |  5 +++--
 src/pocketmine/item/Item.php     | 12 +++++++----
 src/pocketmine/utils/Binary.php  | 34 +++++++++++++++++++++++++++-----
 3 files changed, 40 insertions(+), 11 deletions(-)

diff --git a/src/pocketmine/entity/Entity.php b/src/pocketmine/entity/Entity.php
index cc137bb51..5a9dbe9c6 100644
--- a/src/pocketmine/entity/Entity.php
+++ b/src/pocketmine/entity/Entity.php
@@ -60,6 +60,7 @@ use pocketmine\network\mcpe\protocol\SetEntityDataPacket;
 use pocketmine\Player;
 use pocketmine\plugin\Plugin;
 use pocketmine\Server;
+use pocketmine\utils\Binary;
 
 abstract class Entity extends Location implements Metadatable{
 
@@ -773,7 +774,7 @@ abstract class Entity extends Location implements Metadatable{
 			foreach($this->effects as $effect){
 				$effects[] = new CompoundTag("", [
 					"Id" => new ByteTag("Id", $effect->getId()),
-					"Amplifier" => new ByteTag("Amplifier", $effect->getAmplifier()),
+					"Amplifier" => new ByteTag("Amplifier", Binary::signByte($effect->getAmplifier())),
 					"Duration" => new IntTag("Duration", $effect->getDuration()),
 					"Ambient" => new ByteTag("Ambient", 0),
 					"ShowParticles" => new ByteTag("ShowParticles", $effect->isVisible() ? 1 : 0)
@@ -800,7 +801,7 @@ abstract class Entity extends Location implements Metadatable{
 
 		if(isset($this->namedtag->ActiveEffects)){
 			foreach($this->namedtag->ActiveEffects->getValue() as $e){
-				$amplifier = $e["Amplifier"] & 0xff; //0-255 only
+				$amplifier = Binary::unsignByte($e->Amplifier->getValue()); //0-255 only
 
 				$effect = Effect::getEffect($e["Id"]);
 				if($effect === null){
diff --git a/src/pocketmine/item/Item.php b/src/pocketmine/item/Item.php
index b49ea708a..bebb5f3ad 100644
--- a/src/pocketmine/item/Item.php
+++ b/src/pocketmine/item/Item.php
@@ -40,6 +40,7 @@ use pocketmine\nbt\tag\StringTag;
 use pocketmine\nbt\tag\Tag;
 use pocketmine\Player;
 use pocketmine\Server;
+use pocketmine\utils\Binary;
 use pocketmine\utils\Config;
 
 class Item implements ItemIds, \JsonSerializable{
@@ -1009,7 +1010,7 @@ class Item implements ItemIds, \JsonSerializable{
 	public function nbtSerialize(int $slot = -1, string $tagName = "") : CompoundTag{
 		$tag = new CompoundTag($tagName, [
 			"id" => new ShortTag("id", $this->id),
-			"Count" => new ByteTag("Count", $this->count),
+			"Count" => new ByteTag("Count", Binary::signByte($this->count)),
 			"Damage" => new ShortTag("Damage", $this->meta),
 		]);
 
@@ -1037,12 +1038,15 @@ class Item implements ItemIds, \JsonSerializable{
 			return Item::get(0);
 		}
 
+		$count = Binary::unsignByte($tag->Count->getValue());
+		$meta = isset($tag->Damage) ? $tag->Damage->getValue() : 0;
+
 		if($tag->id instanceof ShortTag){
-			$item = Item::get($tag->id->getValue(), !isset($tag->Damage) ? 0 : $tag->Damage->getValue(), $tag->Count->getValue());
+			$item = Item::get($tag->id->getValue(), $meta, $count);
 		}elseif($tag->id instanceof StringTag){ //PC item save format
 			$item = Item::fromString($tag->id->getValue());
-			$item->setDamage(!isset($tag->Damage) ? 0 : $tag->Damage->getValue());
-			$item->setCount($tag->Count->getValue());
+			$item->setDamage($meta);
+			$item->setCount($count);
 		}else{
 			throw new \InvalidArgumentException("Item CompoundTag ID must be an instance of StringTag or ShortTag, " . get_class($tag->id) . " given");
 		}
diff --git a/src/pocketmine/utils/Binary.php b/src/pocketmine/utils/Binary.php
index df7c3c9bc..386aaa3d5 100644
--- a/src/pocketmine/utils/Binary.php
+++ b/src/pocketmine/utils/Binary.php
@@ -31,6 +31,30 @@ class Binary{
 	const BIG_ENDIAN = 0x00;
 	const LITTLE_ENDIAN = 0x01;
 
+	public static function signByte(int $value) : int{
+		return $value << 56 >> 56;
+	}
+
+	public static function unsignByte(int $value) : int{
+		return $value & 0xff;
+	}
+
+	public static function signShort(int $value) : int{
+		return $value << 48 >> 48;
+	}
+
+	public function unsignShort(int $value) : int{
+		return $value & 0xffff;
+	}
+
+	public static function signInt(int $value) : int{
+		return $value << 32 >> 32;
+	}
+
+	public static function unsignInt(int $value) : int{
+		return $value & 0xffffffff;
+	}
+
 	private static function checkLength($str, $expect){
 		assert(($len = strlen($str)) === $expect, "Expected $expect bytes, got $len");
 	}
@@ -73,7 +97,7 @@ class Binary{
 	 * @return int
 	 */
 	public static function readSignedByte(string $c) : int{
-		return ord($c{0}) << 56 >> 56;
+		return self::signByte(ord($c{0}));
 	}
 
 	/**
@@ -106,7 +130,7 @@ class Binary{
 	 */
 	public static function readSignedShort(string $str) : int{
 		self::checkLength($str, 2);
-		return unpack("n", $str)[1] << 48 >> 48;
+		return self::signShort(unpack("n", $str)[1]);
 	}
 
 	/**
@@ -141,7 +165,7 @@ class Binary{
 	 */
 	public static function readSignedLShort(string $str) : int{
 		self::checkLength($str, 2);
-		return unpack("v", $str)[1] << 48 >> 48;
+		return self::signShort(unpack("v", $str)[1]);
 	}
 
 	/**
@@ -205,7 +229,7 @@ class Binary{
 	 */
 	public static function readInt(string $str) : int{
 		self::checkLength($str, 4);
-		return unpack("N", $str)[1] << 32 >> 32;
+		return self::signInt(unpack("N", $str)[1]);
 	}
 
 	/**
@@ -226,7 +250,7 @@ class Binary{
 	 */
 	public static function readLInt(string $str) : int{
 		self::checkLength($str, 4);
-		return unpack("V", $str)[1] << 32 >> 32;
+		return self::signInt(unpack("V", $str)[1]);
 	}
 
 	/**