xref: /src/lib/libc/termios/tcgetpgrp.c

/*	$NetBSD: tcgetpgrp.c,v 1.10 2012/06/25 22:32:46 abs Exp $	*/

/*-
 * Copyright (c) 1989, 1993
 *	The Regents of the University of California.  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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * 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.
 */

#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)termios.c	8.2 (Berkeley) 2/21/94";
#else
__RCSID("$NetBSD: tcgetpgrp.c,v 1.10 2012/06/25 22:32:46 abs Exp $");
#endif
#endif /* LIBC_SCCS and not lint */

#include "namespace.h"
#include <sys/types.h>
#include <sys/ioctl.h>

#include <assert.h>
#include <errno.h>
#include <termios.h>
#include <unistd.h>

#ifdef __weak_alias
__weak_alias(tcgetpgrp,_tcgetpgrp)
#endif

pid_t
tcgetpgrp(int fd)
{
	int s;

	_DIAGASSERT(fd != -1);

	if (ioctl(fd, TIOCGPGRP, &s) < 0)
		return ((pid_t)-1);

	if (s == (pid_t)-1)
		/* SVID requires a number > 1 that isn't a valid PGID... */
		s = (uint)(pid_t)~0u >> 1;
	return ((pid_t)s);
}