[perl5.git] / lib / chat2.pl

# chat.pl: chat with a server
# Based on: V2.01.alpha.7 91/06/16
# Randal L. Schwartz (was <merlyn@stonehenge.com>)
# multihome additions by A.Macpherson@bnr.co.uk
# allow for /dev/pts based systems by Joe Doupnik <JRD@CC.USU.EDU>

package chat;

require 'sys/socket.ph';

if( defined( &main'PF_INET ) ){
	$pf_inet = &main'PF_INET;
	$sock_stream = &main'SOCK_STREAM;
	local($name, $aliases, $proto) = getprotobyname( 'tcp' );
	$tcp_proto = $proto;
}
else {
	# XXX hardwired $PF_INET, $SOCK_STREAM, 'tcp'
	# but who the heck would change these anyway? (:-)
	$pf_inet = 2;
	$sock_stream = 1;
	$tcp_proto = 6;
}


$sockaddr = 'S n a4 x8';
chop($thishost = `hostname`);

# *S = symbol for current I/O, gets assigned *chatsymbol....
$next = "chatsymbol000000"; # next one
$nextpat = "^chatsymbol"; # patterns that match next++, ++, ++, ++


## $handle = &chat'open_port("server.address",$port_number);
## opens a named or numbered TCP server

sub open_port { ## public
	local($server, $port) = @_;

	local($serveraddr,$serverproc);

	# We may be multi-homed, start with 0, fixup once connexion is made
	$thisaddr = "\0\0\0\0" ;
	$thisproc = pack($sockaddr, 2, 0, $thisaddr);

	*S = ++$next;
	if ($server =~ /^(\d+)+\.(\d+)\.(\d+)\.(\d+)$/) {
		$serveraddr = pack('C4', $1, $2, $3, $4);
	} else {
		local(@x) = gethostbyname($server);
		return undef unless @x;
		$serveraddr = $x[4];
	}
	$serverproc = pack($sockaddr, 2, $port, $serveraddr);
	unless (socket(S, $pf_inet, $sock_stream, $tcp_proto)) {
		($!) = ($!, close(S)); # close S while saving $!
		return undef;
	}
	unless (bind(S, $thisproc)) {
		($!) = ($!, close(S)); # close S while saving $!
		return undef;
	}
	unless (connect(S, $serverproc)) {
		($!) = ($!, close(S)); # close S while saving $!
		return undef;
	}
# We opened with the local address set to ANY, at this stage we know
# which interface we are using.  This is critical if our machine is
# multi-homed, with IP forwarding off, so fix-up.
	local($fam,$lport);
	($fam,$lport,$thisaddr) = unpack($sockaddr, getsockname(S));
	$thisproc = pack($sockaddr, 2, 0, $thisaddr);
# end of post-connect fixup
	select((select(S), $| = 1)[0]);
	$next; # return symbol for switcharound
}

## ($host, $port, $handle) = &chat'open_listen([$port_number]);
## opens a TCP port on the current machine, ready to be listened to
## if $port_number is absent or zero, pick a default port number
## process must be uid 0 to listen to a low port number

sub open_listen { ## public

	*S = ++$next;
	local($thisport) = shift || 0;
	local($thisproc_local) = pack($sockaddr, 2, $thisport, $thisaddr);
	local(*NS) = "__" . time;
	unless (socket(NS, $pf_inet, $sock_stream, $tcp_proto)) {
		($!) = ($!, close(NS));
		return undef;
	}
	unless (bind(NS, $thisproc_local)) {
		($!) = ($!, close(NS));
		return undef;
	}
	unless (listen(NS, 1)) {
		($!) = ($!, close(NS));
		return undef;
	}
	select((select(NS), $| = 1)[0]);
	local($family, $port, @myaddr) =
		unpack("S n C C C C x8", getsockname(NS));
	$S{"needs_accept"} = *NS; # so expect will open it
	(@myaddr, $port, $next); # returning this
}

## $handle = &chat'open_proc("command","arg1","arg2",...);
## opens a /bin/sh on a pseudo-tty

sub open_proc { ## public
	local(@cmd) = @_;

	*S = ++$next;
	local(*TTY) = "__TTY" . time;
	local($pty,$tty) = &_getpty(S,TTY);
	die "Cannot find a new pty" unless defined $pty;
	$pid = fork;
	die "Cannot fork: $!" unless defined $pid;
	unless ($pid) {
		close STDIN; close STDOUT; close STDERR;
		setpgrp(0,$$);
		if (open(DEVTTY, "/dev/tty")) {
		    ioctl(DEVTTY,0x20007471,0);		# XXX s/b &TIOCNOTTY
		    close DEVTTY;
		}
		open(STDIN,"<&TTY");
		open(STDOUT,">&TTY");
		open(STDERR,">&STDOUT");
		die "Oops" unless fileno(STDERR) == 2;	# sanity
		close(S);
		exec @cmd;
		die "Cannot exec @cmd: $!";
	}
	close(TTY);
	$next; # return symbol for switcharound
}

# $S is the read-ahead buffer

## $return = &chat'expect([$handle,] $timeout_time,
## 	$pat1, $body1, $pat2, $body2, ... )
## $handle is from previous &chat'open_*().
## $timeout_time is the time (either relative to the current time, or
## absolute, ala time(2)) at which a timeout event occurs.
## $pat1, $pat2, and so on are regexs which are matched against the input
## stream.  If a match is found, the entire matched string is consumed,
## and the corresponding body eval string is evaled.
##
## Each pat is a regular-expression (probably enclosed in single-quotes
## in the invocation).  ^ and $ will work, respecting the current value of $*.
## If pat is 'TIMEOUT', the body is executed if the timeout is exceeded.
## If pat is 'EOF', the body is executed if the process exits before
## the other patterns are seen.
##
## Pats are scanned in the order given, so later pats can contain
## general defaults that won't be examined unless the earlier pats
## have failed.
##
## The result of eval'ing body is returned as the result of
## the invocation.  Recursive invocations are not thought
## through, and may work only accidentally. :-)
##
## undef is returned if either a timeout or an eof occurs and no
## corresponding body has been defined.
## I/O errors of any sort are treated as eof.

$nextsubname = "expectloop000000"; # used for subroutines

sub expect { ## public
	if ($_[0] =~ /$nextpat/) {
		*S = shift;
	}
	local($endtime) = shift;

	local($timeout,$eof) = (1,1);
	local($caller) = caller;
	local($rmask, $nfound, $timeleft, $thisbuf);
	local($cases, $pattern, $action, $subname);
	$endtime += time if $endtime < 600_000_000;

	if (defined $S{"needs_accept"}) { # is it a listen socket?
		local(*NS) = $S{"needs_accept"};
		delete $S{"needs_accept"};
		$S{"needs_close"} = *NS;
		unless(accept(S,NS)) {
			($!) = ($!, close(S), close(NS));
			return undef;
		}
		select((select(S), $| = 1)[0]);
	}

	# now see whether we need to create a new sub:

	unless ($subname = $expect_subname{$caller,@_}) {
		# nope.  make a new one:
		$expect_subname{$caller,@_} = $subname = $nextsubname++;

		$cases .= <<"EDQ"; # header is funny to make everything elsif's
sub $subname {
	LOOP: {
		if (0) { ; }
EDQ
		while (@_) {
			($pattern,$action) = splice(@_,0,2);
			if ($pattern =~ /^eof$/i) {
				$cases .= <<"EDQ";
		elsif (\$eof) {
	 		package $caller;
			$action;
		}
EDQ
				$eof = 0;
			} elsif ($pattern =~ /^timeout$/i) {
			$cases .= <<"EDQ";
		elsif (\$timeout) {
		 	package $caller;
			$action;
		}
EDQ
				$timeout = 0;
			} else {
				$pattern =~ s#/#\\/#g;
			$cases .= <<"EDQ";
		elsif (\$S =~ /$pattern/) {
			\$S = \$';
		 	package $caller;
			$action;
		}
EDQ
			}
		}
		$cases .= <<"EDQ" if $eof;
		elsif (\$eof) {
			undef;
		}
EDQ
		$cases .= <<"EDQ" if $timeout;
		elsif (\$timeout) {
			undef;
		}
EDQ
		$cases .= <<'ESQ';
		else {
			$rmask = "";
			vec($rmask,fileno(S),1) = 1;
			($nfound, $rmask) =
		 		select($rmask, undef, undef, $endtime - time);
			if ($nfound) {
				$nread = sysread(S, $thisbuf, 1024);
				if ($nread > 0) {
					$S .= $thisbuf;
				} else {
					$eof++, redo LOOP; # any error is also eof
				}
			} else {
				$timeout++, redo LOOP; # timeout
			}
			redo LOOP;
		}
	}
}
ESQ
		eval $cases; die "$cases:\n$@" if $@;
	}
	$eof = $timeout = 0;
	do $subname();
}

## &chat'print([$handle,] @data)
## $handle is from previous &chat'open().
## like print $handle @data

sub print { ## public
	if ($_[0] =~ /$nextpat/) {
		*S = shift;
	}

	local $out = join $, , @_;
	syswrite(S, $out, length $out);
	if( $chat'debug ){
		print STDERR "printed:";
		print STDERR @_;
	}
}

## &chat'close([$handle,])
## $handle is from previous &chat'open().
## like close $handle

sub close { ## public
	if ($_[0] =~ /$nextpat/) {
	 	*S = shift;
	}
	close(S);
	if (defined $S{"needs_close"}) { # is it a listen socket?
		local(*NS) = $S{"needs_close"};
		delete $S{"needs_close"};
		close(NS);
	}
}

## @ready_handles = &chat'select($timeout, @handles)
## select()'s the handles with a timeout value of $timeout seconds.
## Returns an array of handles that are ready for I/O.
## Both user handles and chat handles are supported (but beware of
## stdio's buffering for user handles).

sub select { ## public
	local($timeout) = shift;
	local(@handles) = @_;
	local(%handlename) = ();
	local(%ready) = ();
	local($caller) = caller;
	local($rmask) = "";
	for (@handles) {
		if (/$nextpat/o) { # one of ours... see if ready
			local(*SYM) = $_;
			if (length($SYM)) {
				$timeout = 0; # we have a winner
				$ready{$_}++;
			}
			$handlename{fileno($_)} = $_;
		} else {
			$handlename{fileno(/'/ ? $_ : "$caller\'$_")} = $_;
		}
	}
	for (sort keys %handlename) {
		vec($rmask, $_, 1) = 1;
	}
	select($rmask, undef, undef, $timeout);
	for (sort keys %handlename) {
		$ready{$handlename{$_}}++ if vec($rmask,$_,1);
	}
	sort keys %ready;
}

# ($pty,$tty) = $chat'_getpty(PTY,TTY):
# internal procedure to get the next available pty.
# opens pty on handle PTY, and matching tty on handle TTY.
# returns undef if can't find a pty.
# Modify "/dev/pty" to "/dev/pts" for Dell Unix v2.2 (aka SVR4.04). Joe Doupnik.

sub _getpty { ## private
	local($_PTY,$_TTY) = @_;
	$_PTY =~ s/^([^']+)$/(caller)[$[]."'".$1/e;
	$_TTY =~ s/^([^']+)$/(caller)[$[]."'".$1/e;
	local($pty, $tty, $kind);
	if( -e "/dev/pts000" ){		## mods by Joe Doupnik Dec 1992
		$kind = "pts";		## SVR4 Streams
	} else {
		$kind = "pty";		## BSD Clist stuff
	}
	for $bank (112..127) {
		next unless -e sprintf("/dev/$kind%c0", $bank);
		for $unit (48..57) {
			$pty = sprintf("/dev/$kind%c%c", $bank, $unit);
			open($_PTY,"+>$pty") || next;
			select((select($_PTY), $| = 1)[0]);
			($tty = $pty) =~ s/pty/tty/;
			open($_TTY,"+>$tty") || next;
			select((select($_TTY), $| = 1)[0]);
			system "stty nl>$tty";
			return ($pty,$tty);
		}
	}
	undef;
}

1;
Commit	Line	Data
3e3baf6d TB	1	# chat.pl: chat with a server
	2	# Based on: V2.01.alpha.7 91/06/16
	3	# Randal L. Schwartz (was <merlyn@stonehenge.com>)
	4	# multihome additions by A.Macpherson@bnr.co.uk
	5	# allow for /dev/pts based systems by Joe Doupnik <JRD@CC.USU.EDU>
	6
	7	package chat;
	8
	9	require 'sys/socket.ph';
	10
	11	if( defined( &main'PF_INET ) ){
	12	$pf_inet = &main'PF_INET;
	13	$sock_stream = &main'SOCK_STREAM;
	14	local($name, $aliases, $proto) = getprotobyname( 'tcp' );
	15	$tcp_proto = $proto;
	16	}
	17	else {
	18	# XXX hardwired $PF_INET, $SOCK_STREAM, 'tcp'
	19	# but who the heck would change these anyway? (:-)
	20	$pf_inet = 2;
	21	$sock_stream = 1;
	22	$tcp_proto = 6;
	23	}
	24
	25
	26	$sockaddr = 'S n a4 x8';
	27	chop($thishost = `hostname`);
	28
	29	# S = symbol for current I/O, gets assigned chatsymbol....
	30	$next = "chatsymbol000000"; # next one
	31	$nextpat = "^chatsymbol"; # patterns that match next++, ++, ++, ++
	32
	33
	34	## $handle = &chat'open_port("server.address",$port_number);
	35	## opens a named or numbered TCP server
	36
	37	sub open_port { ## public
	38	local($server, $port) = @_;
	39
	40	local($serveraddr,$serverproc);
	41
	42	# We may be multi-homed, start with 0, fixup once connexion is made
	43	$thisaddr = "\0\0\0\0" ;
	44	$thisproc = pack($sockaddr, 2, 0, $thisaddr);
	45
	46	*S = ++$next;
	47	if ($server =~ /^(\d+)+\.(\d+)\.(\d+)\.(\d+)$/) {
	48	$serveraddr = pack('C4', $1, $2, $3, $4);
	49	} else {
	50	local(@x) = gethostbyname($server);
	51	return undef unless @x;
	52	$serveraddr = $x[4];
	53	}
	54	$serverproc = pack($sockaddr, 2, $port, $serveraddr);
	55	unless (socket(S, $pf_inet, $sock_stream, $tcp_proto)) {
	56	($!) = ($!, close(S)); # close S while saving $!
	57	return undef;
	58	}
	59	unless (bind(S, $thisproc)) {
	60	($!) = ($!, close(S)); # close S while saving $!
	61	return undef;
	62	}
	63	unless (connect(S, $serverproc)) {
	64	($!) = ($!, close(S)); # close S while saving $!
65	return undef;
66	}
67	# We opened with the local address set to ANY, at this stage we know
68	# which interface we are using. This is critical if our machine is
69	# multi-homed, with IP forwarding off, so fix-up.
70	local($fam,$lport);
71	($fam,$lport,$thisaddr) = unpack($sockaddr, getsockname(S));
72	$thisproc = pack($sockaddr, 2, 0, $thisaddr);
73	# end of post-connect fixup
74	select((select(S), $\| = 1)[0]);
75	$next; # return symbol for switcharound
76	}
77
78	## ($host, $port, $handle) = &chat'open_listen([$port_number]);
79	## opens a TCP port on the current machine, ready to be listened to
80	## if $port_number is absent or zero, pick a default port number
81	## process must be uid 0 to listen to a low port number
82
83	sub open_listen { ## public
84
85	*S = ++$next;
86	local($thisport) = shift \|\| 0;
87	local($thisproc_local) = pack($sockaddr, 2, $thisport, $thisaddr);
88	local(*NS) = "__" . time;
89	unless (socket(NS, $pf_inet, $sock_stream, $tcp_proto)) {
90	($!) = ($!, close(NS));
91	return undef;
92	}
93	unless (bind(NS, $thisproc_local)) {
94	($!) = ($!, close(NS));
95	return undef;
96	}
97	unless (listen(NS, 1)) {
98	($!) = ($!, close(NS));
99	return undef;
100	}
101	select((select(NS), $\| = 1)[0]);
102	local($family, $port, @myaddr) =
103	unpack("S n C C C C x8", getsockname(NS));
104	$S{"needs_accept"} = *NS; # so expect will open it
105	(@myaddr, $port, $next); # returning this
106	}
107
108	## $handle = &chat'open_proc("command","arg1","arg2",...);
109	## opens a /bin/sh on a pseudo-tty
110
111	sub open_proc { ## public
112	local(@cmd) = @_;
113
114	*S = ++$next;
115	local(*TTY) = "__TTY" . time;
116	local($pty,$tty) = &_getpty(S,TTY);
117	die "Cannot find a new pty" unless defined $pty;
118	$pid = fork;
119	die "Cannot fork: $!" unless defined $pid;
120	unless ($pid) {
121	close STDIN; close STDOUT; close STDERR;
122	setpgrp(0,$$);
123	if (open(DEVTTY, "/dev/tty")) {
124	ioctl(DEVTTY,0x20007471,0); # XXX s/b &TIOCNOTTY
125	close DEVTTY;
126	}
127	open(STDIN,"<&TTY");
128	open(STDOUT,">&TTY");
129	open(STDERR,">&STDOUT");
130	die "Oops" unless fileno(STDERR) == 2; # sanity
131	close(S);
132	exec @cmd;
133	die "Cannot exec @cmd: $!";
134	}
135	close(TTY);
136	$next; # return symbol for switcharound
137	}
138
139	# $S is the read-ahead buffer
140
141	## $return = &chat'expect([$handle,] $timeout_time,
142	## $pat1, $body1, $pat2, $body2, ... )
143	## $handle is from previous &chat'open_*().
144	## $timeout_time is the time (either relative to the current time, or
145	## absolute, ala time(2)) at which a timeout event occurs.
146	## $pat1, $pat2, and so on are regexs which are matched against the input
147	## stream. If a match is found, the entire matched string is consumed,
148	## and the corresponding body eval string is evaled.
149	##
150	## Each pat is a regular-expression (probably enclosed in single-quotes
151	## in the invocation). ^ and $ will work, respecting the current value of $*.
152	## If pat is 'TIMEOUT', the body is executed if the timeout is exceeded.
153	## If pat is 'EOF', the body is executed if the process exits before
154	## the other patterns are seen.
155	##
156	## Pats are scanned in the order given, so later pats can contain
157	## general defaults that won't be examined unless the earlier pats
158	## have failed.
159	##
160	## The result of eval'ing body is returned as the result of
161	## the invocation. Recursive invocations are not thought
162	## through, and may work only accidentally. :-)
163	##
164	## undef is returned if either a timeout or an eof occurs and no
165	## corresponding body has been defined.
166	## I/O errors of any sort are treated as eof.
167
168	$nextsubname = "expectloop000000"; # used for subroutines
169
170	sub expect { ## public
171	if ($_[0] =~ /$nextpat/) {
172	*S = shift;
173	}
174	local($endtime) = shift;
175
176	local($timeout,$eof) = (1,1);
177	local($caller) = caller;
178	local($rmask, $nfound, $timeleft, $thisbuf);
179	local($cases, $pattern, $action, $subname);
180	$endtime += time if $endtime < 600_000_000;
181
182	if (defined $S{"needs_accept"}) { # is it a listen socket?
183	local(*NS) = $S{"needs_accept"};
184	delete $S{"needs_accept"};
185	$S{"needs_close"} = *NS;
186	unless(accept(S,NS)) {
187	($!) = ($!, close(S), close(NS));
188	return undef;
189	}
190	select((select(S), $\| = 1)[0]);
191	}
192
193	# now see whether we need to create a new sub:
194
195	unless ($subname = $expect_subname{$caller,@_}) {
196	# nope. make a new one:
197	$expect_subname{$caller,@_} = $subname = $nextsubname++;
198
199	$cases .= <<"EDQ"; # header is funny to make everything elsif's
200	sub $subname {
201	LOOP: {
202	if (0) { ; }
203	EDQ
204	while (@_) {
205	($pattern,$action) = splice(@_,0,2);
206	if ($pattern =~ /^eof$/i) {
207	$cases .= <<"EDQ";
208	elsif (\$eof) {
209	package $caller;
210	$action;
211	}
212	EDQ
213	$eof = 0;
214	} elsif ($pattern =~ /^timeout$/i) {
215	$cases .= <<"EDQ";
216	elsif (\$timeout) {
217	package $caller;
218	$action;
219	}
220	EDQ
221	$timeout = 0;
222	} else {
223	$pattern =~ s#/#\\/#g;
224	$cases .= <<"EDQ";
225	elsif (\$S =~ /$pattern/) {
226	\$S = \$';
227	package $caller;
228	$action;
229	}
230	EDQ
231	}
232	}
233	$cases .= <<"EDQ" if $eof;
234	elsif (\$eof) {
235	undef;
236	}
237	EDQ
238	$cases .= <<"EDQ" if $timeout;
239	elsif (\$timeout) {
240	undef;
241	}
242	EDQ
243	$cases .= <<'ESQ';
244	else {
245	$rmask = "";
246	vec($rmask,fileno(S),1) = 1;
247	($nfound, $rmask) =
248	select($rmask, undef, undef, $endtime - time);
249	if ($nfound) {
250	$nread = sysread(S, $thisbuf, 1024);
251	if ($nread > 0) {
252	$S .= $thisbuf;
253	} else {
254	$eof++, redo LOOP; # any error is also eof
255	}
256	} else {
257	$timeout++, redo LOOP; # timeout
258	}
259	redo LOOP;
260	}
261	}
262	}
263	ESQ
264	eval $cases; die "$cases:\n$@" if $@;
265	}
266	$eof = $timeout = 0;
267	do $subname();
268	}
269
270	## &chat'print([$handle,] @data)
271	## $handle is from previous &chat'open().
272	## like print $handle @data
273
274	sub print { ## public
275	if ($_[0] =~ /$nextpat/) {
276	*S = shift;
277	}
b7b1864f CB	278
	279	local $out = join $, , @_;
	280	syswrite(S, $out, length $out);
3e3baf6d TB	281	if( $chat'debug ){
	282	print STDERR "printed:";
	283	print STDERR @_;
	284	}
	285	}
	286
	287	## &chat'close([$handle,])
	288	## $handle is from previous &chat'open().
	289	## like close $handle
	290
	291	sub close { ## public
	292	if ($_[0] =~ /$nextpat/) {
	293	*S = shift;
	294	}
	295	close(S);
	296	if (defined $S{"needs_close"}) { # is it a listen socket?
	297	local(*NS) = $S{"needs_close"};
	298	delete $S{"needs_close"};
	299	close(NS);
	300	}
	301	}
	302
	303	## @ready_handles = &chat'select($timeout, @handles)
	304	## select()'s the handles with a timeout value of $timeout seconds.
	305	## Returns an array of handles that are ready for I/O.
	306	## Both user handles and chat handles are supported (but beware of
	307	## stdio's buffering for user handles).
	308
	309	sub select { ## public
	310	local($timeout) = shift;
	311	local(@handles) = @_;
	312	local(%handlename) = ();
	313	local(%ready) = ();
	314	local($caller) = caller;
	315	local($rmask) = "";
	316	for (@handles) {
	317	if (/$nextpat/o) { # one of ours... see if ready
	318	local(*SYM) = $_;
	319	if (length($SYM)) {
	320	$timeout = 0; # we have a winner
	321	$ready{$_}++;
	322	}
	323	$handlename{fileno($_)} = $_;
	324	} else {
	325	$handlename{fileno(/'/ ? $_ : "$caller\'$_")} = $_;
	326	}
	327	}
	328	for (sort keys %handlename) {
	329	vec($rmask, $_, 1) = 1;
	330	}
	331	select($rmask, undef, undef, $timeout);
	332	for (sort keys %handlename) {
	333	$ready{$handlename{$_}}++ if vec($rmask,$_,1);
	334	}
	335	sort keys %ready;
	336	}
	337
	338	# ($pty,$tty) = $chat'_getpty(PTY,TTY):
	339	# internal procedure to get the next available pty.
	340	# opens pty on handle PTY, and matching tty on handle TTY.
	341	# returns undef if can't find a pty.
	342	# Modify "/dev/pty" to "/dev/pts" for Dell Unix v2.2 (aka SVR4.04). Joe Doupnik.
	343
	344	sub _getpty { ## private
345	local($_PTY,$_TTY) = @_;
346	$_PTY =~ s/^([^']+)$/(caller)[$[]."'".$1/e;
347	$_TTY =~ s/^([^']+)$/(caller)[$[]."'".$1/e;
348	local($pty, $tty, $kind);
349	if( -e "/dev/pts000" ){ ## mods by Joe Doupnik Dec 1992
350	$kind = "pts"; ## SVR4 Streams
351	} else {
352	$kind = "pty"; ## BSD Clist stuff
353	}
354	for $bank (112..127) {
355	next unless -e sprintf("/dev/$kind%c0", $bank);
356	for $unit (48..57) {
357	$pty = sprintf("/dev/$kind%c%c", $bank, $unit);
358	open($_PTY,"+>$pty") \|\| next;
359	select((select($_PTY), $\| = 1)[0]);
360	($tty = $pty) =~ s/pty/tty/;
361	open($_TTY,"+>$tty") \|\| next;
362	select((select($_TTY), $\| = 1)[0]);
363	system "stty nl>$tty";
364	return ($pty,$tty);
365	}
366	}
367	undef;
368	}
369
370	1;