#!/usr/bin/perl

$bob = 10; # Number of files to extract at a time.

$USAGE = "
   USAGE:     etar -options args
   SYNOPSIS:  extended tar
   OPTIONS:   -x            eXtract files.
              -l            list files.
              -p:pattern    Pattern to match filenames.
              -i:infile     File can be .tar, .tgz, .tar.gz
              -o:outfile    File can be .tar, .tgz, .tar.gz
              -v            Verbose
   EXAMPLES:
   o  etar -l -i:pdtl.tgz -p:*.tex   List all tex files in pdtl.tgz
   o  etar -x -i:pdtl.tgz -p:*.tex   Extract the same.

   NOTES:     Extracts $bob files at a time to avoid huge input to system.
   AUTHOR:    GPL(C) Mohsin Ahmed http://www.cs.albany.edu/~mosh
";

$filepat = '.';

while( $_ = $ARGV[0], /^-/ ){
    shift; m/^--$/ && last;
    m/^-v/ && $verbose++;
    if( m/^-i:(.+)/ ){
        $infile = $1;
    }
    if( m/^-\?/   ){
        print $USAGE;
        exit;
    }
    m/^-o:(.+)/ && ($outfile = $1);
    m/^-p:(.+)/ && ($filepat = $1);
    m/^-l$/     && $listing++;
    m/^-x$/     && $extracting++;
}

die $USAGE unless $infile;
die "Cannot read '$infile'.\n" unless -r $infile && -f $infile;

#   zl          gunzip -c $1.tgz | tar -tvf -
#   zlg         gunzip -c $1.tgz | tar -tvf - | grep $2
#   zx          gunzip -c $1.tgz | tar -kxvf - $2
#   zxv         gunzip -c $1.tgz | tar -Oxvf - $2 | more
#   zs          tar -cvf - $2 $3 $4 $5 $6 | gzip > $1.tgz
#   zss         tar -cvf - $1    | gzip > $1.tgz


if( $infile =~ m/z$/ ){
    $lscmd = "gunzip -c $infile | tar -tvf  - |";
    $excmd = "gunzip -c $infile | tar -kxvf -  ";
}else{
    $lscmd = "cat  $infile      | tar -tvf  - |";
    $excmd = "cat  $infile      | tar -kxvf -  ";
}

print STDERR "lscmd = $lscmd \n";

open( LS, $lscmd ) || die "Failed: $lscmd\n";

while( $lsline  = <LS> ){
    chop $lsline; # should it be chomp?
    print STDERR "$lsline\n" if $verbose;
    # -rw-r--r-- 801/801        3871 Mar 29 02:50 1993 tab2.pic
    ( $perm,     $id,           $size,$month,$day,$time,$year,$name)
        = split( ' ', $lsline );

    next unless $name =~ m/${filepat}/;
    print STDOUT "$lsline\n" if $listing;
    push( @files, $name );
}

if( $extracting ){
    # Only $bob files at a time to avoid system( huge line ).
    while( @somefiles = splice( @files, 0, $bob ) ){
        print STDERR "Extracting: $excmd @somefiles\n" if $verbose;
        system("$excmd @somefiles");
    }
}

# EOF