xref: /freebsd/lib/libc/gen/daemon.c (revision 8a4217aacf57330755501a349d0ea662d4880386)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1990, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. Neither the name of the University nor the names of its contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  */
31 
32 #if defined(LIBC_SCCS) && !defined(lint)
33 static char sccsid[] = "@(#)daemon.c	8.1 (Berkeley) 6/4/93";
34 #endif /* LIBC_SCCS and not lint */
35 #include <sys/cdefs.h>
36 __FBSDID("$FreeBSD$");
37 
38 #include "namespace.h"
39 #include <errno.h>
40 #include <fcntl.h>
41 #include <paths.h>
42 #include <stdlib.h>
43 #include <signal.h>
44 #include <unistd.h>
45 #include "un-namespace.h"
46 #include "libc_private.h"
47 
48 int
49 daemon(int nochdir, int noclose)
50 {
51 	struct sigaction osa, sa;
52 	int fd;
53 	pid_t newgrp;
54 	int oerrno;
55 	int osa_ok;
56 
57 	/* A SIGHUP may be thrown when the parent exits below. */
58 	sigemptyset(&sa.sa_mask);
59 	sa.sa_handler = SIG_IGN;
60 	sa.sa_flags = 0;
61 	osa_ok = __libc_sigaction(SIGHUP, &sa, &osa);
62 
63 	switch (fork()) {
64 	case -1:
65 		return (-1);
66 	case 0:
67 		break;
68 	default:
69 		/*
70 		 * A fine point:  _exit(0), not exit(0), to avoid triggering
71 		 * atexit(3) processing
72 		 */
73 		_exit(0);
74 	}
75 
76 	newgrp = setsid();
77 	oerrno = errno;
78 	if (osa_ok != -1)
79 		__libc_sigaction(SIGHUP, &osa, NULL);
80 
81 	if (newgrp == -1) {
82 		errno = oerrno;
83 		return (-1);
84 	}
85 
86 	if (!nochdir)
87 		(void)chdir("/");
88 
89 	if (!noclose && (fd = _open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
90 		(void)_dup2(fd, STDIN_FILENO);
91 		(void)_dup2(fd, STDOUT_FILENO);
92 		(void)_dup2(fd, STDERR_FILENO);
93 		if (fd > 2)
94 			(void)_close(fd);
95 	}
96 	return (0);
97 }
98