--- old/jdk/src/share/classes/com/sun/java/util/jar/pack/UnpackerImpl.java	2013-02-07 17:06:47.000000000 +0100
+++ new/jdk/src/share/classes/com/sun/java/util/jar/pack/UnpackerImpl.java	2013-02-07 17:06:46.000000000 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2012, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -107,7 +107,7 @@
      * @param out a JarOutputStream.
      * @exception IOException if an error is encountered.
      */
-    public void unpack(InputStream in, JarOutputStream out) throws IOException {
+    public synchronized void unpack(InputStream in, JarOutputStream out) throws IOException {
         if (in == null) {
             throw new NullPointerException("null input");
         }
@@ -152,7 +152,7 @@
      * @param out a JarOutputStream.
      * @exception IOException if an error is encountered.
      */
-    public void unpack(File in, JarOutputStream out) throws IOException {
+    public synchronized void unpack(File in, JarOutputStream out) throws IOException {
         if (in == null) {
             throw new NullPointerException("null input");
         }