#!/usr/bin/perl

use strict;
use warnings;
use diagnostics;
use POSIX ":sys_wait_h";
use Data::Dumper;

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

        # See waitpid(2) and POSIX(3perl)
        my $status      = $?;
        my $wifexited   = WIFEXITED($status);
        my $wexitstatus = $wifexited ? WEXITSTATUS($status) : undef;
        my $wifsignaled = WIFSIGNALED($status);
        my $wtermsig    = $wifsignaled ? WTERMSIG($status) : undef;
        my $wifstopped  = WIFSTOPPED($status);
        my $wstopsig    = $wifstopped ? WSTOPSIG($status) : undef;

        $child_status{$child} = {
            status      => $status,
            wifexited   => $wifexited,
            wexitstatus => $wexitstatus,
            wifsignaled => $wifsignaled,
            wtermsig    => $wtermsig,
            wifstopped  => $wifstopped,
            wstopsig    => $wstopsig,
        };

        print STDERR "reaper: reaped child=$child"
            ." status=$status"
            ." wifexited=$wifexited"
            ." wexitstatus=".(defined($wexitstatus) ? $wexitstatus : "undef")
            ." wifsignaled=$wifsignaled"
            ." wtermsig=".(defined($wtermsig) ? $wtermsig : "undef")
            ." wifstopped=$wifstopped"
            ." wstopsig=".(defined($wstopsig) ? $wstopsig : "undef")
            ."\n";
    }
}


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

    local $SIG{CHLD} = \&reaper;

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

    if ($reader_pid) {
        print STDERR "copy: spawned reader child=\"$reader_pid\"\n";

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

    my $writer_pid;
    if ($writer_pid = fork()) {
        print STDERR "copy: spawned writer child=\"$writer_pid\"\n";

    }
    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 (exists $child_status{$pid}) {
                my $st = $child_status{$pid};

                # check for non-zero exit status
                # check for death by signal
                if (($st->{wifexited} && $st->{wexitstatus} != 0)
                 || $st->{wifsignaled}) {
                    print Dumper \%child_status;
                    die  "failed ".($pid == $writer_pid ? "tar" : "reader");
                }
            }
        }

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

}


copy("/home/tmp/quotes.tar",".");
exit 0;