daemon.c revision 7934:6aeeafc994de 
1/*-
2 * Copyright (c) 1990 The Regents of the University of California.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#include "k5-int.h"
35#include <fcntl.h>
36#include <sys/types.h>
37#include <sys/file.h>
38#include <unistd.h>
39#ifdef HAVE_PATHS_H
40#include <paths.h>
41#endif
42
43#ifndef _PATH_DEVNULL
44#define _PATH_DEVNULL "/dev/null"
45#endif
46
47int
48daemon(nochdir, noclose)
49	int nochdir, noclose;
50{
51	int cpid;
52
53	if ((cpid = fork()) == -1)
54		return (-1);
55	if (cpid)
56		exit(0);
57#ifdef HAVE_SETSID
58	(void) setsid();
59#else
60#ifndef TIOCNOTTY
61	setpgrp();
62#else
63	{
64		int n;
65
66		/*
67		 * The open below may hang on pseudo ttys if the person
68		 * who starts named logs out before this point.  Thus,
69		 * the need for the timer.
70		 */
71		alarm(120);
72		n = open("/dev/tty", O_RDWR);
73		alarm(0);
74		if (n > 0) {
75			(void) ioctl(n, TIOCNOTTY, (char *)NULL);
76			(void) close(n);
77		}
78	}
79#endif
80#endif
81	if (!nochdir)
82		(void) chdir("/");
83	if (!noclose) {
84		int devnull = open(_PATH_DEVNULL, O_RDWR, 0);
85
86		if (devnull != -1) {
87			(void) dup2(devnull, 0);
88			(void) dup2(devnull, 1);
89			(void) dup2(devnull, 2);
90			if (devnull > 2)
91				(void) close(devnull);
92		}
93	}
94	return (0);
95}
96