Hi All,
I'm having trouble using Archive::Zip to write a file that is then readable by the jar program (Sun JDK 1.5.0_10).

I want to take a JAR created elsewhere and modify a file inside it with perl an write it back out. However, after modification and writing out with Archive::Zip, the jar program gives an error when reading the contents. Here are the stripped down steps:

1. Create foo.jar: 'jar cf foo.jar hello.txt'
2. Run the following code:

use Archive::Zip qw( :ERROR_CODES :CONSTANTS );

my $az_foo = Archive::Zip->new('foo.jar');

unless ($az_foo->writeToFileNamed('bar.jar') == AZ_OK ) {
 die 'write error';
}

my $az_bar = Archive::Zip->new();

unless ( $az_bar->read('bar.jar') == AZ_OK ) {
 die 'bad bar bad!'
}
[download]

** This gives no errors or warnings.**
3. Now run 'jar tf bar.jar'. This gives the error:

   java.util.zip.ZipException: only DEFLATED entries can have EXT descrip
   +tor
       at java.util.zip.ZipInputStream.readLOC(ZipInputStream.java:250)
       at java.util.zip.ZipInputStream.getNextEntry(ZipInputStream.java:7
   +3)
       at sun.tools.jar.Main.list(Main.java:735)
       at sun.tools.jar.Main.run(Main.java:191)
       at sun.tools.jar.Main.main(Main.java:903)
   [download]

I've done a lot of research and investigation without many fruits. Using 'zipinfo.pl' from the Archive::Zip examples/ did get me some clues:

1. bar.jar is 2 bytes smaller than foo.jar
2. The directory member for META-INF/ has a few different parameters between the two JAR's:
   • compressionMethod: foo.jar=8, bar.jar=0
   • desiredCompressionMethod: foo.jar=8, bar.jar=0
   • desiredCompressionLevel: foo.jar=-1, bar.jar=0
3. I've tried manually setting these parameters on the member before writing out, but the values remain the same.

It seems to me the 'META-INF/' directory member is actually expected to be deflated by the jar program - doesn't make sense. I thought I'd ask those wiser than myself before contacting the owner on this one...maybe there is something simple I can do. Cheers and beers.

20070813 Janitored by Corion: Changed PRE tags to P tags, as per Writeup Formatting Tips