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("$FreeBSD$");
33
34#include <sys/param.h>
35#include <sys/mman.h>
36#include <sys/wait.h>
37
38#include <err.h>
39#include <errno.h>
40#include <libutil.h>
41#include <login_cap.h>
42#include <pwd.h>
43#include <signal.h>
44#include <stdio.h>
45#include <stdlib.h>
46#include <unistd.h>
47
48static void dummy_sighandler(int);
49static void restrict_process(const char *);
50static int  wait_child(pid_t pid, sigset_t *mask);
51static void usage(void);
52
53int
54main(int argc, char *argv[])
55{
56	struct pidfh  *ppfh, *pfh;
57	sigset_t mask, oldmask;
58	int ch, nochdir, noclose, restart, serrno;
59	const char *pidfile, *ppidfile,  *user;
60	pid_t otherpid, pid;
61
62	nochdir = noclose = 1;
63	restart = 0;
64	ppidfile = pidfile = user = NULL;
65	while ((ch = getopt(argc, argv, "cfp:P:ru:")) != -1) {
66		switch (ch) {
67		case 'c':
68			nochdir = 0;
69			break;
70		case 'f':
71			noclose = 0;
72			break;
73		case 'p':
74			pidfile = optarg;
75			break;
76		case 'P':
77			ppidfile = optarg;
78			break;
79		case 'r':
80			restart = 1;
81			break;
82		case 'u':
83			user = optarg;
84			break;
85		default:
86			usage();
87		}
88	}
89	argc -= optind;
90	argv += optind;
91
92	if (argc == 0)
93		usage();
94
95	ppfh = pfh = NULL;
96	/*
97	 * Try to open the pidfile before calling daemon(3),
98	 * to be able to report the error intelligently
99	 */
100	if (pidfile != NULL) {
101		pfh = pidfile_open(pidfile, 0600, &otherpid);
102		if (pfh == NULL) {
103			if (errno == EEXIST) {
104				errx(3, "process already running, pid: %d",
105				    otherpid);
106			}
107			err(2, "pidfile ``%s''", pidfile);
108		}
109	}
110	/* Do the same for actual daemon process. */
111	if (ppidfile != NULL) {
112		ppfh = pidfile_open(ppidfile, 0600, &otherpid);
113		if (ppfh == NULL) {
114			serrno = errno;
115			pidfile_remove(pfh);
116			errno = serrno;
117			if (errno == EEXIST) {
118				errx(3, "process already running, pid: %d",
119				     otherpid);
120			}
121			err(2, "ppidfile ``%s''", ppidfile);
122		}
123	}
124
125	if (daemon(nochdir, noclose) == -1) {
126		warn("daemon");
127		goto exit;
128	}
129	/* Write out parent pidfile if needed. */
130	pidfile_write(ppfh);
131
132	/*
133	 * If the pidfile or restart option is specified the daemon
134	 * executes the command in a forked process and wait on child
135	 * exit to remove the pidfile or restart the command. Normally
136	 * we don't want the monitoring daemon to be terminated
137	 * leaving the running process and the stale pidfile, so we
138	 * catch SIGTERM and forward it to the children expecting to
139	 * get SIGCHLD eventually.
140	 */
141	pid = -1;
142	if (pidfile != NULL || restart) {
143		/*
144		 * Restore default action for SIGTERM in case the
145		 * parent process decided to ignore it.
146		 */
147		if (signal(SIGTERM, SIG_DFL) == SIG_ERR) {
148			warn("signal");
149			goto exit;
150		}
151		/*
152		 * Because SIGCHLD is ignored by default, setup dummy handler
153		 * for it, so we can mask it.
154		 */
155		if (signal(SIGCHLD, dummy_sighandler) == SIG_ERR) {
156			warn("signal");
157			goto exit;
158		}
159		/*
160		 * Block interesting signals.
161		 */
162		sigemptyset(&mask);
163		sigaddset(&mask, SIGTERM);
164		sigaddset(&mask, SIGCHLD);
165		if (sigprocmask(SIG_SETMASK, &mask, &oldmask) == -1) {
166			warn("sigprocmask");
167			goto exit;
168		}
169		/*
170		 * Try to protect against pageout kill. Ignore the
171		 * error, madvise(2) will fail only if a process does
172		 * not have superuser privileges.
173		 */
174		(void)madvise(NULL, 0, MADV_PROTECT);
175restart:
176		/*
177		 * Spawn a child to exec the command, so in the parent
178		 * we could wait for it to exit and remove pidfile.
179		 */
180		pid = fork();
181		if (pid == -1) {
182			warn("fork");
183			goto exit;
184		}
185	}
186	if (pid <= 0) {
187		if (pid == 0) {
188			/* Restore old sigmask in the child. */
189			if (sigprocmask(SIG_SETMASK, &oldmask, NULL) == -1)
190				err(1, "sigprocmask");
191		}
192		/* Now that we are the child, write out the pid. */
193		pidfile_write(pfh);
194
195		if (user != NULL)
196			restrict_process(user);
197
198		execvp(argv[0], argv);
199
200		/*
201		 * execvp() failed -- report the error. The child is
202		 * now running, so the exit status doesn't matter.
203		 */
204		err(1, "%s", argv[0]);
205	}
206
207	setproctitle("%s[%d]", argv[0], pid);
208	if (wait_child(pid, &mask) == 0 && restart) {
209		sleep(1);
210		goto restart;
211	}
212exit:
213	pidfile_remove(pfh);
214	pidfile_remove(ppfh);
215	exit(1); /* If daemon(3) succeeded exit status does not matter. */
216}
217
218static void
219dummy_sighandler(int sig __unused)
220{
221	/* Nothing to do. */
222}
223
224static void
225restrict_process(const char *user)
226{
227	struct passwd *pw = NULL;
228
229	pw = getpwnam(user);
230	if (pw == NULL)
231		errx(1, "unknown user: %s", user);
232
233	if (setusercontext(NULL, pw, pw->pw_uid, LOGIN_SETALL) != 0)
234		errx(1, "failed to set user environment");
235}
236
237static int
238wait_child(pid_t pid, sigset_t *mask)
239{
240	int terminate, signo;
241
242	terminate = 0;
243	for (;;) {
244		if (sigwait(mask, &signo) == -1) {
245			warn("sigwaitinfo");
246			return (-1);
247		}
248		switch (signo) {
249		case SIGCHLD:
250			if (waitpid(pid, NULL, WNOHANG) == -1) {
251				warn("waitpid");
252				return (-1);
253			}
254			return (terminate);
255		case SIGTERM:
256			terminate = 1;
257			if (kill(pid, signo) == -1) {
258				warn("kill");
259				return (-1);
260			}
261			continue;
262		default:
263			warnx("sigwaitinfo: invalid signal: %d", signo);
264			return (-1);
265		}
266	}
267}
268
269static void
270usage(void)
271{
272	(void)fprintf(stderr,
273	    "usage: daemon [-cfr] [-p child_pidfile] [-P supervisor_pidfile] "
274	    "[-u user]\n              command arguments ...\n");
275	exit(1);
276}
277