#!/usr/bin/perl
use strict;
use warnings;
use IO::Pty;
use File::Copy;

# Run @$argv in the background with stdout redirected to $out.
sub start_child {
        my ($argv, $out) = @_;
        my $pid = fork;
        if (not defined $pid) {
                die "fork failed: $!"
        } elsif ($pid == 0) {
                open STDOUT, ">&", $out;
                close $out;
                exec(@$argv) or die "cannot exec '$argv->[0]': $!"
        }
        return $pid;
}

# Wait for $pid to finish.
sub finish_child {
        # Simplified from wait_or_whine() in run-command.c.
        my ($pid) = @_;

        my $waiting = waitpid($pid, 0);
        if ($waiting < 0) {
                die "waitpid failed: $!";
        } elsif ($? & 127) {
                my $code = $? & 127;
                warn "died of signal $code";
                return $code - 128;
        } else {
                return $? >> 8;
        }
}

sub xsendfile {
        my ($out, $in) = @_;

        # Note: the real sendfile() cannot read from a terminal.

        # It is unspecified by POSIX whether reads
        # from a disconnected terminal will return
        # EIO (as in AIX 4.x, IRIX, and Linux) or
        # end-of-file.  Either is fine.
        copy($in, $out, 4096) or $!{EIO} or die "cannot copy from child: $!";
}

if ($#ARGV < 1) {
        die "usage: test-terminal program args";
}
my $master = new IO::Pty;
my $slave = $master->slave;
my $pid = start_child(\@ARGV, $slave);
close $slave;
xsendfile(\*STDOUT, $master);
exit(finish_child($pid));