Implement POSIX function tcgetsid() which returns session id.

PR: stand/107561

lib/libc/gen/Makefile.inc

@@ -63,7 +63,7 @@ MAN+=	alarm.3 arc4random.3 \
 	setjmp.3 setmode.3 setproctitle.3 \
 	siginterrupt.3 signal.3 sigsetops.3 sleep.3 \
 	statvfs.3 stringlist.3 \
-	strtofflags.3 sysconf.3 sysctl.3 syslog.3 tcgetpgrp.3 \
+	strtofflags.3 sysconf.3 sysctl.3 syslog.3 tcgetpgrp.3 tcgetsid.3 \
 	tcsendbreak.3 tcsetattr.3 tcsetpgrp.3 time.3 times.3 timezone.3 \
 	ttyname.3 tzset.3 ualarm.3 ucontext.3 ulimit.3 uname.3 \
 	unvis.3 usleep.3 utime.3 valloc.3 vis.3 wordexp.3

lib/libc/gen/Symbol.map

@@ -337,6 +337,7 @@ FBSD_1.1 {
 	fts_get_clientptr;
 	fts_get_stream;
 	fts_set_clientptr;
+	tcgetsid;
 };
 
 FBSDprivate_1.0 {

lib/libc/gen/tcgetsid.3

@@ -0,0 +1,71 @@
+.\" Copyright (c) 2008 David Xu <davidxu@freebsd.org>
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd April 15, 2008
+.Dt TCGETSID 3
+.Os
+.Sh NAME
+.Nm tcgetsid
+.Nd get session ID associated with a controlling terminal
+.Sh LIBRARY
+.Lb libc
+.Sh SYNOPSIS
+.In sys/types.h
+.In termios.h
+.Ft pid_t
+.Fn tcgetsid "int fd"
+.Sh DESCRIPTION
+The
+.Fn tcgetsid
+function returns the process group ID of the session leader for a
+controlling terminal specified by
+.Fa fd .
+.Sh ERRORS
+If an error occurs,
+.Fn tcgetsid
+returns -1 and the global variable
+.Va errno
+is set to indicate the error, as follows:
+.Bl -tag -width Er
+.It Bq Er EBADF
+The
+.Fa fd
+argument is not a valid file descriptor.
+.It Bq Er ENOTTY
+The calling process does not have a controlling terminal or the
+underlying terminal device represented by
+.Fa fd
+is not the controlling terminal.
+.El
+.Sh SEE ALSO
+.Xr getsid 2 ,
+.Xr setsid 2 ,
+.Xr tcgetpgrp 3
+.Sh STANDARDS
+The
+.Fn tcgetsid
+function conforms to
+.St -xpg4.2 .

lib/libc/gen/termios.c

@@ -99,6 +99,17 @@ tcgetpgrp(fd)
 	return ((pid_t)s);
 }
 
+pid_t
+tcgetsid(int fd)
+{
+	int s;
+
+	if (_ioctl(fd, TIOCGSID, &s) < 0)
+		return ((pid_t)-1);
+
+	return ((pid_t)s);
+}
+
 speed_t
 cfgetospeed(t)
 	const struct termios *t;

sys/kern/tty.c

@@ -1010,6 +1010,11 @@ ttioctl(struct tty *tp, u_long cmd, void *data, int flag)
 			return (ENOTTY);
 		*(int *)data = tp->t_pgrp ? tp->t_pgrp->pg_id : NO_PID;
 		break;
+	case TIOCGSID:                  /* get sid of tty */
+		if (!isctty(p, tp))
+			return (ENOTTY);
+		*(int *)data = tp->t_session->s_sid;
+		break;
 #ifdef TIOCHPCL
 	case TIOCHPCL:			/* hang up on last close */
 		s = spltty();

sys/sys/ttycom.h

@@ -118,7 +118,7 @@ struct winsize {
 #define	TIOCSTAT	 _IO('t', 101)		/* simulate ^T status message */
 #define		UIOCCMD(n)	_IO('u', n)	/* usr cntl op "n" */
 						/* 100 see consio.h */
-						/* 99 obsolete or unused */
+#define	TIOCGSID	_IOR('t', 99, int)	/* get session id */
 #define	TIOCCONS	_IOW('t', 98, int)	/* become virtual console */
 #define	TIOCSCTTY	 _IO('t', 97)		/* become controlling tty */
 						/* 97-90 tun; some conflicts */