2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1999 Berkeley Software Design, Inc. All rights reserved.
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. Berkeley Software Design Inc's name may not be used to endorse or
15 * promote products derived from this software without specific prior
18 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * From BSDI: daemon.c,v 1.2 1996/08/15 01:11:09 jch Exp
33 #include <sys/cdefs.h>
34 __FBSDID("$FreeBSD$");
36 #include <sys/param.h>
44 #include <login_cap.h>
57 #define LBUF_SIZE 4096
67 static void restrict_process(const char *);
68 static void handle_term(int);
69 static void handle_chld(int);
70 static void handle_hup(int);
71 static int open_log(const char *);
72 static void reopen_log(struct log_params *);
73 static int listen_child(int, struct log_params *);
74 static int get_log_mapping(const char *, const CODE *);
75 static void open_pid_files(const char *, const char *, struct pidfh **,
77 static void do_output(const unsigned char *, size_t, struct log_params *);
78 static void daemon_sleep(time_t, long);
79 static void usage(void);
81 static volatile sig_atomic_t terminate = 0, child_gone = 0, pid = 0,
85 main(int argc, char *argv[])
87 const char *pidfile, *ppidfile, *title, *user, *outfn, *logtag;
88 int ch, nochdir, noclose, restart, dosyslog, child_eof;
89 sigset_t mask_susp, mask_orig, mask_read, mask_term;
90 struct log_params logpar;
91 int pfd[2] = { -1, -1 }, outfd = -1;
92 int stdmask, logpri, logfac, log_reopen;
93 struct pidfh *ppfh, *pfh;
96 memset(&logpar, 0, sizeof(logpar));
97 stdmask = STDOUT_FILENO | STDERR_FILENO;
98 ppidfile = pidfile = user = NULL;
99 nochdir = noclose = 1;
108 while ((ch = getopt(argc, argv, "cfHSp:P:ru:o:s:l:t:l:m:R:T:")) != -1) {
120 logfac = get_log_mapping(optarg, facilitynames);
122 errx(5, "unrecognized syslog facility");
126 stdmask = strtol(optarg, &p, 10);
127 if (p == optarg || stdmask < 0 || stdmask > 3)
128 errx(6, "unrecognized listening mask");
143 restart = strtol(optarg, &p, 0);
144 if (p == optarg || restart < 1)
145 errx(6, "invalid restart delay");
148 logpri = get_log_mapping(optarg, prioritynames);
150 errx(4, "unrecognized syslog priority");
180 outfd = open_log(outfn);
186 openlog(logtag, LOG_PID | LOG_NDELAY, logfac);
190 * Try to open the pidfile before calling daemon(3),
191 * to be able to report the error intelligently
193 open_pid_files(pidfile, ppidfile, &pfh, &ppfh);
194 if (daemon(nochdir, noclose) == -1) {
198 /* Write out parent pidfile if needed. */
201 * If the pidfile or restart option is specified the daemon
202 * executes the command in a forked process and wait on child
203 * exit to remove the pidfile or restart the command. Normally
204 * we don't want the monitoring daemon to be terminated
205 * leaving the running process and the stale pidfile, so we
206 * catch SIGTERM and forward it to the children expecting to
207 * get SIGCHLD eventually. We also must fork() to obtain a
208 * readable pipe with the child for writing to a log file
212 if (pidfile || ppidfile || restart || outfd != -1 || dosyslog) {
213 struct sigaction act_term, act_chld, act_hup;
215 /* Avoid PID racing with SIGCHLD and SIGTERM. */
216 memset(&act_term, 0, sizeof(act_term));
217 act_term.sa_handler = handle_term;
218 sigemptyset(&act_term.sa_mask);
219 sigaddset(&act_term.sa_mask, SIGCHLD);
221 memset(&act_chld, 0, sizeof(act_chld));
222 act_chld.sa_handler = handle_chld;
223 sigemptyset(&act_chld.sa_mask);
224 sigaddset(&act_chld.sa_mask, SIGTERM);
226 memset(&act_hup, 0, sizeof(act_hup));
227 act_hup.sa_handler = handle_hup;
228 sigemptyset(&act_hup.sa_mask);
230 /* Block these when avoiding racing before sigsuspend(). */
231 sigemptyset(&mask_susp);
232 sigaddset(&mask_susp, SIGTERM);
233 sigaddset(&mask_susp, SIGCHLD);
234 /* Block SIGTERM when we lack a valid child PID. */
235 sigemptyset(&mask_term);
236 sigaddset(&mask_term, SIGTERM);
238 * When reading, we wish to avoid SIGCHLD. SIGTERM
239 * has to be caught, otherwise we'll be stuck until
240 * the read() returns - if it returns.
242 sigemptyset(&mask_read);
243 sigaddset(&mask_read, SIGCHLD);
244 /* Block SIGTERM to avoid racing until we have forked. */
245 if (sigprocmask(SIG_BLOCK, &mask_term, &mask_orig)) {
249 if (sigaction(SIGTERM, &act_term, NULL) == -1) {
253 if (sigaction(SIGCHLD, &act_chld, NULL) == -1) {
258 * Try to protect against pageout kill. Ignore the
259 * error, madvise(2) will fail only if a process does
260 * not have superuser privileges.
262 (void)madvise(NULL, 0, MADV_PROTECT);
263 logpar.outfd = outfd;
264 logpar.dosyslog = dosyslog;
265 logpar.logpri = logpri;
266 logpar.noclose = noclose;
267 logpar.outfn = outfn;
268 if (log_reopen && outfd >= 0 &&
269 sigaction(SIGHUP, &act_hup, NULL) == -1) {
277 * Spawn a child to exec the command.
284 } else if (pid > 0) {
286 * Unblock SIGTERM after we know we have a valid
287 * child PID to signal.
289 if (sigprocmask(SIG_UNBLOCK, &mask_term, NULL)) {
298 /* Now that we are the child, write out the pid. */
302 restrict_process(user);
304 * When forking, the child gets the original sigmask,
309 if (sigprocmask(SIG_SETMASK, &mask_orig, NULL))
310 err(1, "sigprogmask");
311 if (stdmask & STDERR_FILENO) {
312 if (dup2(pfd[1], STDERR_FILENO) == -1)
315 if (stdmask & STDOUT_FILENO) {
316 if (dup2(pfd[1], STDOUT_FILENO) == -1)
319 if (pfd[1] != STDERR_FILENO &&
320 pfd[1] != STDOUT_FILENO)
323 execvp(argv[0], argv);
325 * execvp() failed -- report the error. The child is
326 * now running, so the exit status doesn't matter.
328 err(1, "%s", argv[0]);
330 setproctitle("%s[%d]", title, (int)pid);
332 * As we have closed the write end of pipe for parent process,
333 * we might detect the child's exit by reading EOF. The child
334 * might have closed its stdout and stderr, so we must wait for
335 * the SIGCHLD to ensure that the process is actually gone.
340 * We block SIGCHLD when listening, but SIGTERM we accept
341 * so the read() won't block if we wish to depart.
343 * Upon receiving SIGTERM, we have several options after
344 * sending the SIGTERM to our child:
346 * - read until EOF but only for a while
349 * We go for the third, as otherwise we have no guarantee
350 * that we won't block indefinitely if the child refuses
351 * to depart. To handle the second option, a different
352 * approach would be needed (procctl()?)
354 if (child_gone && child_eof) {
356 } else if (terminate) {
358 } else if (!child_eof) {
359 if (sigprocmask(SIG_BLOCK, &mask_read, NULL)) {
363 child_eof = !listen_child(pfd[0], &logpar);
364 if (sigprocmask(SIG_UNBLOCK, &mask_read, NULL)) {
369 if (sigprocmask(SIG_BLOCK, &mask_susp, NULL)) {
373 while (!terminate && !child_gone)
374 sigsuspend(&mask_orig);
375 if (sigprocmask(SIG_UNBLOCK, &mask_susp, NULL)) {
381 if (restart && !terminate)
382 daemon_sleep(restart, 0);
383 if (sigprocmask(SIG_BLOCK, &mask_term, NULL)) {
387 if (restart && !terminate) {
399 pidfile_remove(ppfh);
400 exit(1); /* If daemon(3) succeeded exit status does not matter. */
404 daemon_sleep(time_t secs, long nsecs)
406 struct timespec ts = { secs, nsecs };
408 while (!terminate && nanosleep(&ts, &ts) == -1) {
415 open_pid_files(const char *pidfile, const char *ppidfile,
416 struct pidfh **pfh, struct pidfh **ppfh)
422 *pfh = pidfile_open(pidfile, 0600, &fpid);
424 if (errno == EEXIST) {
425 errx(3, "process already running, pid: %d",
428 err(2, "pidfile ``%s''", pidfile);
431 /* Do the same for the actual daemon process. */
433 *ppfh = pidfile_open(ppidfile, 0600, &fpid);
436 pidfile_remove(*pfh);
438 if (errno == EEXIST) {
439 errx(3, "process already running, pid: %d",
442 err(2, "ppidfile ``%s''", ppidfile);
448 get_log_mapping(const char *str, const CODE *c)
451 for (cp = c; cp->c_name; cp++)
452 if (strcmp(cp->c_name, str) == 0)
458 restrict_process(const char *user)
460 struct passwd *pw = NULL;
464 errx(1, "unknown user: %s", user);
466 if (setusercontext(NULL, pw, pw->pw_uid, LOGIN_SETALL) != 0)
467 errx(1, "failed to set user environment");
471 * We try to collect whole lines terminated by '\n'. Otherwise we collect a
472 * full buffer, and then output it.
474 * Return value of 0 is assumed to mean EOF or error, and 1 indicates to
478 listen_child(int fd, struct log_params *logpar)
480 static unsigned char buf[LBUF_SIZE];
481 static size_t bytes_read = 0;
485 assert(bytes_read < LBUF_SIZE - 1);
489 rv = read(fd, buf + bytes_read, LBUF_SIZE - bytes_read - 1);
494 assert(bytes_read <= LBUF_SIZE - 1);
495 /* Always NUL-terminate just in case. */
496 buf[LBUF_SIZE - 1] = '\0';
498 * Chomp line by line until we run out of buffer.
499 * This does not take NUL characters into account.
501 while ((cp = memchr(buf, '\n', bytes_read)) != NULL) {
502 size_t bytes_line = cp - buf + 1;
503 assert(bytes_line <= bytes_read);
504 do_output(buf, bytes_line, logpar);
505 bytes_read -= bytes_line;
506 memmove(buf, cp + 1, bytes_read);
508 /* Wait until the buffer is full. */
509 if (bytes_read < LBUF_SIZE - 1)
511 do_output(buf, bytes_read, logpar);
514 } else if (rv == -1) {
515 /* EINTR should trigger another read. */
516 if (errno == EINTR) {
523 /* Upon EOF, we have to flush what's left of the buffer. */
524 if (bytes_read > 0) {
525 do_output(buf, bytes_read, logpar);
532 * The default behavior is to stay silent if the user wants to redirect
533 * output to a file and/or syslog. If neither are provided, then we bounce
534 * everything back to parent's stdout.
537 do_output(const unsigned char *buf, size_t len, struct log_params *logpar)
539 assert(len <= LBUF_SIZE);
544 if (logpar->dosyslog)
545 syslog(logpar->logpri, "%.*s", (int)len, buf);
546 if (logpar->outfd != -1) {
547 if (write(logpar->outfd, buf, len) == -1)
550 if (logpar->noclose && !logpar->dosyslog && logpar->outfd == -1)
551 printf("%.*s", (int)len, buf);
555 * We use the global PID acquired directly from fork. If there is no valid
556 * child pid, the handler should be blocked and/or child_gone == 1.
559 handle_term(int signo)
561 if (pid > 0 && !child_gone)
567 handle_chld(int signo __unused)
571 int rv = waitpid(-1, NULL, WNOHANG);
575 } else if (rv == -1 && errno != EINTR) {
583 handle_hup(int signo __unused)
590 open_log(const char *outfn)
593 return open(outfn, O_CREAT | O_WRONLY | O_APPEND | O_CLOEXEC, 0600);
597 reopen_log(struct log_params *lpp)
602 outfd = open_log(lpp->outfn);
611 (void)fprintf(stderr,
612 "usage: daemon [-cfHrS] [-p child_pidfile] [-P supervisor_pidfile]\n"
613 " [-u user] [-o output_file] [-t title]\n"
614 " [-l syslog_facility] [-s syslog_priority]\n"
615 " [-T syslog_tag] [-m output_mask] [-R restart_delay_secs]\n"
616 "command arguments ...\n");