JDK-6712743 : pack200: should default to 150.7 pack format for classfiles without any classes.
  • Type: Enhancement
  • Component: core-libs
  • Sub-Component: java.util.jar
  • Affected Version: 6u10,6u23,7
  • Priority: P4
  • Status: Closed
  • Resolution: Fixed
  • OS: generic,windows_xp,windows_7
  • CPU: generic,x86
  • Submitted: 2008-06-10
  • Updated: 2017-05-16
  • Resolved: 2011-03-08
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JDK 7
7 b100Fixed
Related Reports
Duplicate :  
JDK-7009863 - Pack200 generates java6 pack files even if all class files are java5 or smaller
Duplicate :  
JDK-6959206 - pack200 needs to recognise new classfile version
Relates :  
JDK-6960415 - pack200 documentation changes
Description
FULL PRODUCT VERSION :
java version "1.6.0_10-beta"
Java(TM) SE Runtime Environment (build 1.6.0_10-beta-b24)
Java HotSpot(TM) Client VM (build 11.0-b12, mixed mode, sharing)

Reproducible with other Java 6 verisons, e.g. Update 6 as well.

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows XP [Version 5.1.2600]

A DESCRIPTION OF THE PROBLEM :
Java 5 cannot unpack .jar.pack.gz files created with Java 6.  In my case I tested with Java 6 Update 10 [build 24] and Java 5 Update 15 with the command line utilities, but others have reproduced this with Java 6 Update 6 and Java 5 Update 11.  Moreover the issue has been seen with Java 5 Web Start clients of a Java 6 server.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Use Java 6's pack200 utility to create a .jar.pack.gz file from a jar.  Use Java 5's unpack200 to try to unpack it.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Pack200 files created in Java 6 should be readable in Java 5 -- at the very least with a "-target 1.5" option or some such.
ACTUAL -
It is apparently impossible to create pack200 files with Java 6 that can be used with Java 5!

ERROR MESSAGES/STACK TRACES THAT OCCUR :
Corrupted pack file: magic/ver = CAFED00D/160.1 should be CAFED00D/150.7

REPRODUCIBILITY :
This bug can be reproduced always.

CUSTOMER SUBMITTED WORKAROUND :
Create all pack200 files with Java 5 -- which means installing an additional JDK on one's server, having one's server app know this location, etc.

Overall this is a real issue specifically for Java 6 Update 10 as it really hurts the ease of Java client deployment!
Comments
WORK AROUND add a null class as shown below compiled with -target 5. The test script: % cat doit #!/bin/sh -x echo "create a failure case" echo "Junk" > junk jar cvf foo.jar junk /usr/jdk/instances/jdk1.6.0/bin/pack200 foo.jar.pack.gz foo.jar /usr/jdk/instances/jdk1.5.0/bin/unpack200 foo.jar.pack.gz bar.jar echo "demonstrate how to fix this" printf "public class Foo{}" > Foo.java /usr/jdk/instances/jdk1.6.0/bin/javac -target 5 Foo.java jar uvf foo.jar Foo.class rm -f bar.jar /usr/jdk/instances/jdk1.6.0/bin/pack200 foo.jar.pack.gz foo.jar /usr/jdk/instances/jdk1.5.0/bin/unpack200 foo.jar.pack.gz bar.jar if [ -f bar.jar ]; then printf "It worked\n" fi % ./doit + echo create a failure case create a failure case + echo Junk + jar cvf foo.jar junk added manifest adding: junk(in = 5) (out= 7)(deflated -40%) + /usr/jdk/instances/jdk1.6.0/bin/pack200 foo.jar.pack.gz foo.jar + /usr/jdk/instances/jdk1.5.0/bin/unpack200 foo.jar.pack.gz bar.jar Corrupted pack file: magic/ver = CAFED00D/160.1 should be CAFED00D/150.7 + echo demonstrate how to fix this demonstrate how to fix this + printf public class Foo{} + /usr/jdk/instances/jdk1.6.0/bin/javac -target 5 Foo.java + jar uvf foo.jar Foo.class adding: Foo.class(in = 180) (out= 152)(deflated 15%) + rm -f bar.jar + /usr/jdk/instances/jdk1.6.0/bin/pack200 foo.jar.pack.gz foo.jar + /usr/jdk/instances/jdk1.5.0/bin/unpack200 foo.jar.pack.gz bar.jar + [ -f bar.jar ] + printf It worked\n It worked
10-06-2008
EVALUATION The trouble here is that Jar-file does not contain any classes so the 1.6 pack200 generates a java6 compatible class, one can add a dummy class compiled with -target 5. Simple annotating JARs which are devoid of any classes should not use pack200 and instead rely on http-compression using gzip. The above behavior and deployment strategies are described here: http://java.sun.com/javase/6/docs/technotes/guides/deployment/deployment-guide/pack200.html See the workaround section for more info.
10-06-2008