Monks,

There are three processes.

  1. The parent
  2. A child that cats a tarball to stdout. A reader
  3. A child that redirects STDIN to the other child and untars the stream from that child. A writer

What I am having trouble with is getting the parent to detect if the writer has exited early. So if I start it running get the pid of writer and kill -9 that pid SIGCHLD doesn't seem to be executed. If the reader is killed SIGCHLD is executed.

I don't understand what is going on. Why isn't SIGCHLD signaling when I kill the writer.

    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;
        }
    }

}

[download]

Thanks for any help you can give...

rlb3

In reply to Detecting when a child process is killed unexpectedly by rlb3

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