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>
45 #include <login_cap.h>
59 #define LBUF_SIZE 4096
69 static void restrict_process(const char *);
70 static void handle_term(int);
71 static void handle_chld(int);
72 static void handle_hup(int);
73 static int open_log(const char *);
74 static void reopen_log(struct log_params *);
75 static int listen_child(int, struct log_params *);
76 static int get_log_mapping(const char *, const CODE *);
77 static void open_pid_files(const char *, const char *, struct pidfh **,
79 static void do_output(const unsigned char *, size_t, struct log_params *);
80 static void daemon_sleep(time_t, long);
82 static volatile sig_atomic_t terminate = 0, child_gone = 0, pid = 0,
85 static const char shortopts[] = "+cfHSp:P:ru:o:s:l:t:m:R:T:h";
87 static const struct option longopts[] = {
88 { "change-dir", no_argument, NULL, 'c' },
89 { "close-fds", no_argument, NULL, 'f' },
90 { "sighup", no_argument, NULL, 'H' },
91 { "syslog", no_argument, NULL, 'S' },
92 { "output-file", required_argument, NULL, 'o' },
93 { "output-mask", required_argument, NULL, 'm' },
94 { "child-pidfile", required_argument, NULL, 'p' },
95 { "supervisor-pidfile", required_argument, NULL, 'P' },
96 { "restart", no_argument, NULL, 'r' },
97 { "restart-delay", required_argument, NULL, 'R' },
98 { "title", required_argument, NULL, 't' },
99 { "user", required_argument, NULL, 'u' },
100 { "syslog-priority", required_argument, NULL, 's' },
101 { "syslog-facility", required_argument, NULL, 'l' },
102 { "syslog-tag", required_argument, NULL, 'T' },
103 { "help", no_argument, NULL, 'h' },
107 static _Noreturn void
110 (void)fprintf(stderr,
111 "usage: daemon [-cfHrS] [-p child_pidfile] [-P supervisor_pidfile]\n"
112 " [-u user] [-o output_file] [-t title]\n"
113 " [-l syslog_facility] [-s syslog_priority]\n"
114 " [-T syslog_tag] [-m output_mask] [-R restart_delay_secs]\n"
115 "command arguments ...\n");
117 (void)fprintf(stderr,
118 " --change-dir -c Change the current working directory to root\n"
119 " --close-fds -f Set stdin, stdout, stderr to /dev/null\n"
120 " --sighup -H Close and re-open output file on SIGHUP\n"
121 " --syslog -S Send output to syslog\n"
122 " --output-file -o <file> Append output of the child process to file\n"
123 " --output-mask -m <mask> What to send to syslog/file\n"
124 " 1=stdout, 2=stderr, 3=both\n"
125 " --child-pidfile -p <file> Write PID of the child process to file\n"
126 " --supervisor-pidfile -P <file> Write PID of the supervisor process to file\n"
127 " --restart -r Restart child if it terminates (1 sec delay)\n"
128 " --restart-delay -R <N> Restart child if it terminates after N sec\n"
129 " --title -t <title> Set the title of the supervisor process\n"
130 " --user -u <user> Drop privileges, run as given user\n"
131 " --syslog-priority -s <prio> Set syslog priority\n"
132 " --syslog-facility -l <flty> Set syslog facility\n"
133 " --syslog-tag -T <tag> Set syslog tag\n"
134 " --help -h Show this help\n");
140 main(int argc, char *argv[])
142 const char *pidfile, *ppidfile, *title, *user, *outfn, *logtag;
143 int ch, nochdir, noclose, restart, dosyslog, child_eof;
144 sigset_t mask_susp, mask_orig, mask_read, mask_term;
145 struct log_params logpar;
146 int pfd[2] = { -1, -1 }, outfd = -1;
147 int stdmask, logpri, logfac, log_reopen;
148 struct pidfh *ppfh, *pfh;
151 memset(&logpar, 0, sizeof(logpar));
152 stdmask = STDOUT_FILENO | STDERR_FILENO;
153 ppidfile = pidfile = user = NULL;
154 nochdir = noclose = 1;
163 while ((ch = getopt_long(argc, argv, shortopts, longopts, NULL)) != -1) {
175 logfac = get_log_mapping(optarg, facilitynames);
177 errx(5, "unrecognized syslog facility");
182 stdmask = strtol(optarg, &p, 10);
183 if (p == optarg || stdmask < 0 || stdmask > 3) {
184 errx(6, "unrecognized listening mask");
200 restart = strtol(optarg, &p, 0);
201 if (p == optarg || restart < 1) {
202 errx(6, "invalid restart delay");
206 logpri = get_log_mapping(optarg, prioritynames);
208 errx(4, "unrecognized syslog priority");
227 __builtin_unreachable();
244 outfd = open_log(outfn);
251 openlog(logtag, LOG_PID | LOG_NDELAY, logfac);
256 * Try to open the pidfile before calling daemon(3),
257 * to be able to report the error intelligently
259 open_pid_files(pidfile, ppidfile, &pfh, &ppfh);
260 if (daemon(nochdir, noclose) == -1) {
264 /* Write out parent pidfile if needed. */
267 * If the pidfile or restart option is specified the daemon
268 * executes the command in a forked process and wait on child
269 * exit to remove the pidfile or restart the command. Normally
270 * we don't want the monitoring daemon to be terminated
271 * leaving the running process and the stale pidfile, so we
272 * catch SIGTERM and forward it to the children expecting to
273 * get SIGCHLD eventually. We also must fork() to obtain a
274 * readable pipe with the child for writing to a log file
278 if (pidfile || ppidfile || restart || outfd != -1 || dosyslog) {
279 struct sigaction act_term, act_chld, act_hup;
281 /* Avoid PID racing with SIGCHLD and SIGTERM. */
282 memset(&act_term, 0, sizeof(act_term));
283 act_term.sa_handler = handle_term;
284 sigemptyset(&act_term.sa_mask);
285 sigaddset(&act_term.sa_mask, SIGCHLD);
287 memset(&act_chld, 0, sizeof(act_chld));
288 act_chld.sa_handler = handle_chld;
289 sigemptyset(&act_chld.sa_mask);
290 sigaddset(&act_chld.sa_mask, SIGTERM);
292 memset(&act_hup, 0, sizeof(act_hup));
293 act_hup.sa_handler = handle_hup;
294 sigemptyset(&act_hup.sa_mask);
296 /* Block these when avoiding racing before sigsuspend(). */
297 sigemptyset(&mask_susp);
298 sigaddset(&mask_susp, SIGTERM);
299 sigaddset(&mask_susp, SIGCHLD);
300 /* Block SIGTERM when we lack a valid child PID. */
301 sigemptyset(&mask_term);
302 sigaddset(&mask_term, SIGTERM);
304 * When reading, we wish to avoid SIGCHLD. SIGTERM
305 * has to be caught, otherwise we'll be stuck until
306 * the read() returns - if it returns.
308 sigemptyset(&mask_read);
309 sigaddset(&mask_read, SIGCHLD);
310 /* Block SIGTERM to avoid racing until we have forked. */
311 if (sigprocmask(SIG_BLOCK, &mask_term, &mask_orig)) {
315 if (sigaction(SIGTERM, &act_term, NULL) == -1) {
319 if (sigaction(SIGCHLD, &act_chld, NULL) == -1) {
324 * Try to protect against pageout kill. Ignore the
325 * error, madvise(2) will fail only if a process does
326 * not have superuser privileges.
328 (void)madvise(NULL, 0, MADV_PROTECT);
329 logpar.outfd = outfd;
330 logpar.dosyslog = dosyslog;
331 logpar.logpri = logpri;
332 logpar.noclose = noclose;
333 logpar.outfn = outfn;
334 if (log_reopen && outfd >= 0 &&
335 sigaction(SIGHUP, &act_hup, NULL) == -1) {
344 * Spawn a child to exec the command.
351 } else if (pid > 0) {
353 * Unblock SIGTERM after we know we have a valid
354 * child PID to signal.
356 if (sigprocmask(SIG_UNBLOCK, &mask_term, NULL)) {
365 /* Now that we are the child, write out the pid. */
369 restrict_process(user);
372 * When forking, the child gets the original sigmask,
377 if (sigprocmask(SIG_SETMASK, &mask_orig, NULL)) {
378 err(1, "sigprogmask");
380 if (stdmask & STDERR_FILENO) {
381 if (dup2(pfd[1], STDERR_FILENO) == -1) {
385 if (stdmask & STDOUT_FILENO) {
386 if (dup2(pfd[1], STDOUT_FILENO) == -1) {
390 if (pfd[1] != STDERR_FILENO &&
391 pfd[1] != STDOUT_FILENO) {
395 execvp(argv[0], argv);
397 * execvp() failed -- report the error. The child is
398 * now running, so the exit status doesn't matter.
400 err(1, "%s", argv[0]);
402 setproctitle("%s[%d]", title, (int)pid);
404 * As we have closed the write end of pipe for parent process,
405 * we might detect the child's exit by reading EOF. The child
406 * might have closed its stdout and stderr, so we must wait for
407 * the SIGCHLD to ensure that the process is actually gone.
412 * We block SIGCHLD when listening, but SIGTERM we accept
413 * so the read() won't block if we wish to depart.
415 * Upon receiving SIGTERM, we have several options after
416 * sending the SIGTERM to our child:
418 * - read until EOF but only for a while
421 * We go for the third, as otherwise we have no guarantee
422 * that we won't block indefinitely if the child refuses
423 * to depart. To handle the second option, a different
424 * approach would be needed (procctl()?)
426 if (child_gone && child_eof) {
428 } else if (terminate) {
430 } else if (!child_eof) {
431 if (sigprocmask(SIG_BLOCK, &mask_read, NULL)) {
435 child_eof = !listen_child(pfd[0], &logpar);
436 if (sigprocmask(SIG_UNBLOCK, &mask_read, NULL)) {
441 if (sigprocmask(SIG_BLOCK, &mask_susp, NULL)) {
445 while (!terminate && !child_gone)
446 sigsuspend(&mask_orig);
447 if (sigprocmask(SIG_UNBLOCK, &mask_susp, NULL)) {
453 if (restart && !terminate) {
454 daemon_sleep(restart, 0);
456 if (sigprocmask(SIG_BLOCK, &mask_term, NULL)) {
460 if (restart && !terminate) {
473 pidfile_remove(ppfh);
474 exit(1); /* If daemon(3) succeeded exit status does not matter. */
478 daemon_sleep(time_t secs, long nsecs)
480 struct timespec ts = { secs, nsecs };
482 while (!terminate && nanosleep(&ts, &ts) == -1) {
483 if (errno != EINTR) {
490 open_pid_files(const char *pidfile, const char *ppidfile,
491 struct pidfh **pfh, struct pidfh **ppfh)
497 *pfh = pidfile_open(pidfile, 0600, &fpid);
499 if (errno == EEXIST) {
500 errx(3, "process already running, pid: %d",
503 err(2, "pidfile ``%s''", pidfile);
506 /* Do the same for the actual daemon process. */
508 *ppfh = pidfile_open(ppidfile, 0600, &fpid);
511 pidfile_remove(*pfh);
513 if (errno == EEXIST) {
514 errx(3, "process already running, pid: %d",
517 err(2, "ppidfile ``%s''", ppidfile);
523 get_log_mapping(const char *str, const CODE *c)
526 for (cp = c; cp->c_name; cp++)
527 if (strcmp(cp->c_name, str) == 0) {
534 restrict_process(const char *user)
536 struct passwd *pw = NULL;
540 errx(1, "unknown user: %s", user);
543 if (setusercontext(NULL, pw, pw->pw_uid, LOGIN_SETALL) != 0) {
544 errx(1, "failed to set user environment");
547 setenv("USER", pw->pw_name, 1);
548 setenv("HOME", pw->pw_dir, 1);
549 setenv("SHELL", *pw->pw_shell ? pw->pw_shell : _PATH_BSHELL, 1);
553 * We try to collect whole lines terminated by '\n'. Otherwise we collect a
554 * full buffer, and then output it.
556 * Return value of 0 is assumed to mean EOF or error, and 1 indicates to
560 listen_child(int fd, struct log_params *logpar)
562 static unsigned char buf[LBUF_SIZE];
563 static size_t bytes_read = 0;
567 assert(bytes_read < LBUF_SIZE - 1);
572 rv = read(fd, buf + bytes_read, LBUF_SIZE - bytes_read - 1);
577 assert(bytes_read <= LBUF_SIZE - 1);
578 /* Always NUL-terminate just in case. */
579 buf[LBUF_SIZE - 1] = '\0';
581 * Chomp line by line until we run out of buffer.
582 * This does not take NUL characters into account.
584 while ((cp = memchr(buf, '\n', bytes_read)) != NULL) {
585 size_t bytes_line = cp - buf + 1;
586 assert(bytes_line <= bytes_read);
587 do_output(buf, bytes_line, logpar);
588 bytes_read -= bytes_line;
589 memmove(buf, cp + 1, bytes_read);
591 /* Wait until the buffer is full. */
592 if (bytes_read < LBUF_SIZE - 1) {
595 do_output(buf, bytes_read, logpar);
598 } else if (rv == -1) {
599 /* EINTR should trigger another read. */
600 if (errno == EINTR) {
607 /* Upon EOF, we have to flush what's left of the buffer. */
608 if (bytes_read > 0) {
609 do_output(buf, bytes_read, logpar);
616 * The default behavior is to stay silent if the user wants to redirect
617 * output to a file and/or syslog. If neither are provided, then we bounce
618 * everything back to parent's stdout.
621 do_output(const unsigned char *buf, size_t len, struct log_params *logpar)
623 assert(len <= LBUF_SIZE);
629 if (logpar->dosyslog) {
630 syslog(logpar->logpri, "%.*s", (int)len, buf);
632 if (logpar->outfd != -1) {
633 if (write(logpar->outfd, buf, len) == -1)
636 if (logpar->noclose && !logpar->dosyslog && logpar->outfd == -1) {
637 printf("%.*s", (int)len, buf);
642 * We use the global PID acquired directly from fork. If there is no valid
643 * child pid, the handler should be blocked and/or child_gone == 1.
646 handle_term(int signo)
648 if (pid > 0 && !child_gone) {
655 handle_chld(int signo __unused)
659 int rv = waitpid(-1, NULL, WNOHANG);
663 } else if (rv == -1 && errno != EINTR) {
671 handle_hup(int signo __unused)
678 open_log(const char *outfn)
681 return open(outfn, O_CREAT | O_WRONLY | O_APPEND | O_CLOEXEC, 0600);
685 reopen_log(struct log_params *lpp)
690 outfd = open_log(lpp->outfn);
691 if (lpp->outfd >= 0) {