use Data::Dumper;

my %child_status;
sub reaper {
    my $child;
    while (($child=waitpid(-1,WNOHANG))>0) {
        $child_status{$child} = $? >> 8;
    }
}


sub copy {
    my $file = shift;
    my $dir  = shift;

    local $SIG{CHLD} = \&reaper;

    my $reader_pid = open( my $reader, '-|' );

    if ($reader_pid) {

    }
    else {
        exec '/bin/cat', $file;
        exit;
    }

    my $writer_pid;
    if ($writer_pid = fork()) {
        
    }
    else {
        chdir($dir);
        open( STDIN, "<&=" . fileno($reader) );
        exec '/bin/tar', '-x', '-p', '-f', '-';
        exit;
    }

    while (1) {
        sleep 1;
        next if !%child_status;

        foreach my $pid ($reader_pid, $writer_pid) {
            if ($child_status{$pid} != 0) {

                print Dumper \%child_status;

                %child_status = ();
                die  "failed tar\n";
            }
        }

        if (exists $child_status{$writer_pid} && exists $child_status{$reader_pid}) {
            last;
        }
    }

}