daemon.c revision 167700 
1/*-
2 * Copyright (c) 1999 Berkeley Software Design, Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 * 3. Berkeley Software Design Inc's name may not be used to endorse or
13 *    promote products derived from this software without specific prior
14 *    written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 *
28 *	From BSDI: daemon.c,v 1.2 1996/08/15 01:11:09 jch Exp
29 */
30
31#include <sys/cdefs.h>
32__FBSDID("$FreeBSD: head/usr.sbin/daemon/daemon.c 167700 2007-03-19 12:12:53Z trhodes $");
33
34#include <sys/param.h>
35
36#include <err.h>
37#include <errno.h>
38#include <pwd.h>
39#include <libutil.h>
40#include <login_cap.h>
41#include <stdio.h>
42#include <stdlib.h>
43#include <unistd.h>
44
45static void restrict_process(const char *);
46static void usage(void);
47
48int
49main(int argc, char *argv[])
50{
51	struct pidfh *pfh = NULL;
52	int ch, nochdir, noclose, errcode;
53	const char *pidfile, *user;
54	pid_t otherpid;
55
56	nochdir = noclose = 1;
57	pidfile = user = NULL;
58	while ((ch = getopt(argc, argv, "-cf:p:u:")) != -1) {
59		switch (ch) {
60		case 'c':
61			nochdir = 0;
62			break;
63		case 'f':
64			noclose = 0;
65			break;
66		case 'p':
67			pidfile = optarg;
68			break;
69		case 'u':
70			user = optarg;
71			break;
72		default:
73			usage();
74		}
75	}
76	argc -= optind;
77	argv += optind;
78
79	if (argc == 0)
80		usage();
81
82	if (user != NULL)
83		restrict_process(user);
84
85	/*
86	 * Try to open the pidfile before calling daemon(3),
87	 * to be able to report the error intelligently
88	 */
89	if (pidfile) {
90		pfh = pidfile_open(pidfile, 0600, &otherpid);
91		if (pfh == NULL) {
92			if (errno == EEXIST) {
93				errx(3, "process already running, pid: %d",
94				    otherpid);
95			}
96			err(2, "pidfile ``%s''", pidfile);
97		}
98	}
99
100	if (daemon(nochdir, noclose) == -1)
101		err(1, NULL);
102
103	/* Now that we are the child, write out the pid */
104	if (pidfile)
105		pidfile_write(pfh);
106
107	execvp(argv[0], argv);
108
109	/*
110	 * execvp() failed -- unlink pidfile if any, and
111	 * report the error
112	 */
113	errcode = errno; /* Preserve errcode -- unlink may reset it */
114	if (pidfile)
115		pidfile_remove(pfh);
116
117	/* The child is now running, so the exit status doesn't matter. */
118	errc(1, errcode, "%s", argv[0]);
119}
120
121static void
122restrict_process(const char *user)
123{
124	struct passwd *pw = NULL;
125
126	pw = getpwnam(user);
127	if (pw == NULL)
128		errx(1, "unknown user: %s", user);
129
130	if (setusercontext(NULL, pw, pw->pw_uid, LOGIN_SETALL) != 0)
131		errx(1, "failed to set user environment");
132}
133
134static void
135usage(void)
136{
137	(void)fprintf(stderr,
138	    "usage: daemon [-cf] [-p pidfile] [-u user] command "
139		"arguments ...\n");
140	exit(1);
141}
142