#!/usr/bin/perl -w
use strict;

sub cat
{
	my ($dir, $F1, $F2) = @_;

	for (;;) {
		if (!sysread $F1, $_, 4096) {
			return if $! == 11; #EAGAIN;
			print STDERR 'conn closed:', $! || 'EOF', "\n";
			exit;
		}

		length == syswrite $F2, $_ or die;

		s/^\+//; s/^\$//; s/#..\Z//s;
		substr($_, 62) = '...' if length $_ > 64;

		print "$dir $_\n";
	}
}

sub main_loop
{
	my ($F1, $F2) = @_;

	# FIONBIO
	ioctl $F1, 0x5421, pack 'i!', 1 or die $!;
	ioctl $F2, 0x5421, pack 'i!', 1 or die $!;

	for (my $rfd = '';;) {
		vec($rfd, fileno $F1, 1) = 1;
		vec($rfd, fileno $F2, 1) = 1;

		0 < select $rfd, undef, undef, undef
			or die;

		cat '=>', $F1, $F2 if vec $rfd, fileno $F1, 1;
		cat '<=', $F2, $F1 if vec $rfd, fileno $F2, 1;
	}
}

sub wait_for_connect
{
	my $port = 0+shift;

	socket my $sk, 2,1,0
		or return die "sock create: $!";
	defined setsockopt $sk, 1,2,1
		or return die "sock reuseaddr: $!";
	bind $sk, pack 'Sna12', 2, $port, ''
		or return die "sock bind $port port: $!";
	listen $sk, 2
		or return die "sock listen: $!";

	print "wait for connection on $port port ...\n";
	accept my $conn, $sk
		or return die "sock accept: $!";

	return $conn;
}

sub main
{
	my $port = 2000;

	if (@_) {
		$port = shift;

		die "Usage: $0 [port]\n"
			if @_ || $port =~ /\D/;
	}

	my $conn = wait_for_connect $port or exit;

	sysopen my $ugdb, '/proc/ugdb', 2 or die 0;

	main_loop $conn, $ugdb;
}

main @ARGV;