sub fdopen {
	@_ == 3 or croak 'usage: $io->fdopen(FD, MODE)';
	my ($io, $fd, $mode) = @_;
	local(*GLOB);

	if (ref($fd) && "".$fd =~ /GLOB\(/o) {
	# It's a glob reference; Alias it as we cannot get name of anon GLOBs
	my $n = qualify(*GLOB);
	*GLOB = *{*$fd};
	$fd =  $n;
	} elsif ($fd =~ m#^\d+$#) {
	# It's an FD number; prefix with "=".
	$fd = "=$fd";
	}

	open($io, _open_mode_string($mode) . '&' . $fd)
	? $io : undef;
}