/***********************************************************************

*                                                                      *

*               This software is part of the ast package               *

*          Copyright (c) 1985-2012 AT&T Intellectual Property          *

*                      and is licensed under the                       *

*                 Eclipse Public License, Version 1.0                  *

*                    by AT&T Intellectual Property                     *

*                                                                      *

*                A copy of the License is available at                 *

*          http://www.eclipse.org/org/documents/epl-v10.html           *

*         (with md5 checksum b35adb5213ca9657e911e9befb180842)         *

*                                                                      *

*              Information and Software Systems Research               *

*                            AT&T Research                             *

*                           Florham Park NJ                            *

*                                                                      *

*                 Glenn Fowler <gsf@research.att.com>                  *

*                  David Korn <dgk@research.att.com>                   *

*                   Phong Vo <kpv@research.att.com>                    *

*                                                                      *

***********************************************************************/

#pragma prototyped

#include <ast.h>

#if _lib_setsid

NoN(setsid)

#else

#include <ast_tty.h>

#include <error.h>

/*

 * become new process group leader and drop control tty

 */

pid_t

setsid(void)

{

	int	pg;

#ifdef TIOCNOTTY

	int	fd;

#endif

	/*

	 * become a new process group leader

	 */

	if ((pg = getpid()) == getpgrp())

	{

		errno = EPERM;

		return(-1);

	}

	setpgid(pg, pg);

#ifdef TIOCNOTTY

	/*

	 * drop the control tty

	 */

	if ((fd = open("/dev/tty", O_RDONLY|O_cloexec)) >= 0)

	{

		ioctl(fd, TIOCNOTTY, 0);

		close(fd);

	}

#else

	/*

	 * second child in s5 to avoid reacquiring the control tty

	 */

#if _lib_fork && HUH920711 /* some s5's botch this */

	switch (fork())

	{

	case -1:

		exit(1);

	case 0:

		break;

	default:

		exit(0);

	}

#endif

#endif

	return(pg);

}

#endif