if($tar_engine == undef)

Not related to your problem, but that code does not do what you expect it to do. Numeric equal (==) forces numeric context on both sides, so essentially you are comparing $tar_engine with 0. Perl warns you about this problem if you use warnings. You want to use defined($tar_engine) instead of $tar_engine == undef.

Another problem:

if(!$tar_engine->extract(@filelist))
    {
        my $ret = 1;
        print "\nError in extraction.\n";
    }
[download]

The scope of my $ret is limited to the block following if. Outside that block, $ret is either not defined at all or its value stays unchanged.

I suspect that your script runs without strict and warnings, so there may be more hidden errors. Try adding use strict; and use warnings; to the top of your code and fix problems until perl stops whining.

Alexander