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 244986 2013-01-03 00:49:11Z marius $");
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 *pfh = NULL;
57 sigset_t mask, oldmask;
58 int ch, nochdir, noclose, restart;
59 const char *pidfile, *user;
60 pid_t otherpid, pid;
61
62 nochdir = noclose = 1;
63 restart = 0;
64 pidfile = user = NULL;
65 while ((ch = getopt(argc, argv, "cfp: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 'r':
77 restart = 1;
78 break;
79 case 'u':
80 user = optarg;
81 break;
82 default:
83 usage();
84 }
85 }
86 argc -= optind;
87 argv += optind;
88
89 if (argc == 0)
90 usage();
91
92 pfh = NULL;
93 /*
94 * Try to open the pidfile before calling daemon(3),
95 * to be able to report the error intelligently
96 */
97 if (pidfile != NULL) {
98 pfh = pidfile_open(pidfile, 0600, &otherpid);
99 if (pfh == NULL) {
100 if (errno == EEXIST) {
101 errx(3, "process already running, pid: %d",
102 otherpid);
103 }
104 err(2, "pidfile ``%s''", pidfile);
105 }
106 }
107
108 if (daemon(nochdir, noclose) == -1)
109 err(1, NULL);
110
111 /*
112 * If the pidfile or restart option is specified the daemon
113 * executes the command in a forked process and wait on child
114 * exit to remove the pidfile or restart the command. Normally
115 * we don't want the monitoring daemon to be terminated
116 * leaving the running process and the stale pidfile, so we
117 * catch SIGTERM and forward it to the children expecting to
118 * get SIGCHLD eventually.
119 */
120 pid = -1;
121 if (pidfile != NULL || restart) {
122 /*
123 * Restore default action for SIGTERM in case the
124 * parent process decided to ignore it.
125 */
126 if (signal(SIGTERM, SIG_DFL) == SIG_ERR)
127 err(1, "signal");
128 /*
129 * Because SIGCHLD is ignored by default, setup dummy handler
130 * for it, so we can mask it.
131 */
132 if (signal(SIGCHLD, dummy_sighandler) == SIG_ERR)
133 err(1, "signal");
134 /*
135 * Block interesting signals.
136 */
137 sigemptyset(&mask);
138 sigaddset(&mask, SIGTERM);
139 sigaddset(&mask, SIGCHLD);
140 if (sigprocmask(SIG_SETMASK, &mask, &oldmask) == -1)
141 err(1, "sigprocmask");
142 /*
143 * Try to protect against pageout kill. Ignore the
144 * error, madvise(2) will fail only if a process does
145 * not have superuser privileges.
146 */
147 (void)madvise(NULL, 0, MADV_PROTECT);
148restart:
149 /*
150 * Spawn a child to exec the command, so in the parent
151 * we could wait for it to exit and remove pidfile.
152 */
153 pid = fork();
154 if (pid == -1) {
155 pidfile_remove(pfh);
156 err(1, "fork");
157 }
158 }
159 if (pid <= 0) {
160 if (pid == 0) {
161 /* Restore old sigmask in the child. */
162 if (sigprocmask(SIG_SETMASK, &oldmask, NULL) == -1)
163 err(1, "sigprocmask");
164 }
165 /* Now that we are the child, write out the pid. */
166 pidfile_write(pfh);
167
168 if (user != NULL)
169 restrict_process(user);
170
171 execvp(argv[0], argv);
172
173 /*
174 * execvp() failed -- report the error. The child is
175 * now running, so the exit status doesn't matter.
176 */
177 err(1, "%s", argv[0]);
178 }
179 setproctitle("%s[%d]", argv[0], pid);
180 if (wait_child(pid, &mask) == 0 && restart) {
181 sleep(1);
182 goto restart;
183 }
184 pidfile_remove(pfh);
185 exit(0); /* Exit status does not matter. */
186}
187
188static void
189dummy_sighandler(int sig __unused)
190{
191 /* Nothing to do. */
192}
193
194static void
195restrict_process(const char *user)
196{
197 struct passwd *pw = NULL;
198
199 pw = getpwnam(user);
200 if (pw == NULL)
201 errx(1, "unknown user: %s", user);
202
203 if (setusercontext(NULL, pw, pw->pw_uid, LOGIN_SETALL) != 0)
204 errx(1, "failed to set user environment");
205}
206
207static int
208wait_child(pid_t pid, sigset_t *mask)
209{
210 int terminate, signo;
211
212 terminate = 0;
213 for (;;) {
214 if (sigwait(mask, &signo) == -1) {
215 warn("sigwaitinfo");
216 return (-1);
217 }
218 switch (signo) {
219 case SIGCHLD:
220 if (waitpid(pid, NULL, WNOHANG) == -1) {
221 warn("waitpid");
222 return (-1);
223 }
224 return (terminate);
225 case SIGTERM:
226 terminate = 1;
227 if (kill(pid, signo) == -1) {
228 warn("kill");
229 return (-1);
230 }
231 continue;
232 default:
233 warnx("sigwaitinfo: invalid signal: %d", signo);
234 return (-1);
235 }
236 }
237}
238
239static void
240usage(void)
241{
242 (void)fprintf(stderr,
243 "usage: daemon [-cfr] [-p pidfile] [-u user] command "
244 "arguments ...\n");
245 exit(1);
246}