tlhackque has asked for the wisdom of the Perl Monks concerning the following question:

I don't think it's me, but thought I'd see what other eyes see...

Using Archive::Tar, if I create a tar file of a symlink with FOLLOW_SYMLINK = 1, the write fails. Here's the 1-line reproducer. Perl 5.12.4, fedora 15

# touch foo
# ln -s foo bar

# perl -MArchive::Tar -e'$Archive::Tar::FOLLOW_SYMLINK = 1; my $t = Ar
+chive::Tar->new; $t->add_files("bar"); $t->write( "baz.tgz", COMPRESS
+_GZIP );print $t->error(1); print $Archive::Tar::VERSION'
Could not write data for: bar at -e line 1
Could not write data for: bar at /usr/share/perl5/Archive/Tar.pm line 
+1293
        Archive::Tar::write('Archive::Tar=HASH(0x9dcf90)', 'baz.tgz', 
+9) 
called at -e line 1
1.78

[download]
The same command adding "foo" instead of bar works. Hard to imagine something so simple being broken - but I can't see what I'm doing wrong!

Thanks for any help.

This communication may not represent my employer's views, if any, on the matters discussed.

Replies are listed 'Best First'.
Re: Archive::Tar fails to dereference and save symlinks?
by Khen1950fx (Canon) on Sep 16, 2011 at 02:54 UTC
    It's not broken:). You're trying to print the error method, but it doesn't like that. This worked for me: 
    #!/usr/bin/perl -slw

use strict;
use Archive::Tar;
use Data::Dumper::Concise;

$Archive::Tar::FOLLOW_SYMLINK = 1; 
print $Archive::Tar::VERSION;

my $t = Archive::Tar->new; 
$t->add_files('/root/Desktop/bar'); 
$t->write( 'baz.tgz', COMPRESS_GZIP );
$t->error(1); 
print "Done";

    [download]
[reply]
[d/l]
      Thanks, but there's something different about our environments.

      I downloaded your code. Commented out the "Data::Dumper::Concise" since you don't use it and it isn't installed on my system. Changed output file name (don't have a Desktop on this system).

      Still get error. Yes, the .tgz gets created (didn't notice this before).

      More interesting, if instead of a 0 byte file (Did you duplicate that?), I do echo "abcd">foo - the error goes away.

      BUT: the .tgz is corrupt. Sometimes. 

      #!/usr/bin/perl -slw

use strict;
use Archive::Tar;
#use Data::Dumper::Concise;

$Archive::Tar::FOLLOW_SYMLINK = 1;
print $Archive::Tar::VERSION;

my $t = Archive::Tar->new;
$t->add_files('bar');
$t->write( 'baz.tgz', COMPRESS_GZIP );
$t->error(1);
print "Done";

ls -l foo bar baz.tgz
ls: cannot access baz.tgz: No such file or directory
lrwxrwxrwx. 1 root root 3 Sep 15 19:35 bar -> foo
-rw-r--r--. 1 root root 0 Sep 15 23:19 foo

# perl z.tmp
1.78
Could not write data for: bar at z.tmp line 12
Done

# echo "abcd" >foo

# ls -l foo bar baz.tgz
lrwxrwxrwx. 1 root root  3 Sep 15 19:35 bar -> foo
-rw-r--r--. 1 root root 97 Sep 15 23:21 baz.tgz
-rw-r--r--. 1 root root  5 Sep 15 23:20 foo

# rm baz.tgz

# perl z.tmp
1.78
Done

]# ls -l foo bar baz.tgz
lrwxrwxrwx. 1 root root  3 Sep 15 19:35 bar -> foo
-rw-r--r--. 1 root root 97 Sep 15 23:25 baz.tgz
-rw-r--r--. 1 root root  5 Sep 15 23:20 foo

And sometimes, I get

# tar -tzvf baz.tgz
-rw-r--r-- root/root         0 2011-09-15 19:35 bar
tar: Skipping to next header
tar: Exiting with failure status due to previous errors

      [download]
      I'm not hallucinating. (This is a reduced test case from larger program; it normally does more work.)
[reply]
[d/l]

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