daemon.c

/* -*- mode: c; c-file-style: "bsd"; indent-tabs-mode: t -*- */
/*
 * Copyright (c) 1990 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. 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 "k5-int.h"
#include <fcntl.h>
#include <sys/types.h>
#include <sys/file.h>
#include <unistd.h>
#ifdef HAVE_PATHS_H
#include <paths.h>
#endif

#ifndef _PATH_DEVNULL
#define _PATH_DEVNULL "/dev/null"
#endif

int
daemon(nochdir, noclose)
	int nochdir, noclose;
{
	int cpid;

	if ((cpid = fork()) == -1)
		return (-1);
	if (cpid)
		exit(0);
#ifdef HAVE_SETSID
	(void) setsid();
#else
#ifndef TIOCNOTTY
	setpgrp();
#else
	{
		int n;

		/*
		 * The open below may hang on pseudo ttys if the person
		 * who starts named logs out before this point.  Thus,
		 * the need for the timer.
		 */
		alarm(120);
		n = open("/dev/tty", O_RDWR);
		alarm(0);
		if (n > 0) {
			(void) ioctl(n, TIOCNOTTY, (char *)NULL);
			(void) close(n);
		}
	}
#endif
#endif
	if (!nochdir)
		(void) chdir("/");
	if (!noclose) {
		int devnull = open(_PATH_DEVNULL, O_RDWR, 0);

		if (devnull != -1) {
			(void) dup2(devnull, 0);
			(void) dup2(devnull, 1);
			(void) dup2(devnull, 2);
			if (devnull > 2)
				(void) close(devnull);
		}
	}
	return (0);
}