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>
60 #define LBUF_SIZE 4096
63 const char *output_filename;
64 const char *syslog_tag;
72 static void restrict_process(const char *);
73 static void handle_term(int);
74 static void handle_chld(int);
75 static void handle_hup(int);
76 static int open_log(const char *);
77 static void reopen_log(struct log_params *);
78 static int listen_child(int, struct log_params *);
79 static int get_log_mapping(const char *, const CODE *);
80 static void open_pid_files(const char *, const char *, struct pidfh **,
82 static void do_output(const unsigned char *, size_t, struct log_params *);
83 static void daemon_sleep(time_t, long);
85 static volatile sig_atomic_t terminate = 0;
86 static volatile sig_atomic_t child_gone = 0;
87 static volatile sig_atomic_t pid = -1;
88 static volatile sig_atomic_t do_log_reopen = 0;
90 static const char shortopts[] = "+cfHSp:P:ru:o:s:l:t:m:R:T:h";
92 static const struct option longopts[] = {
93 { "change-dir", no_argument, NULL, 'c' },
94 { "close-fds", no_argument, NULL, 'f' },
95 { "sighup", no_argument, NULL, 'H' },
96 { "syslog", no_argument, NULL, 'S' },
97 { "output-file", required_argument, NULL, 'o' },
98 { "output-mask", required_argument, NULL, 'm' },
99 { "child-pidfile", required_argument, NULL, 'p' },
100 { "supervisor-pidfile", required_argument, NULL, 'P' },
101 { "restart", no_argument, NULL, 'r' },
102 { "restart-delay", required_argument, NULL, 'R' },
103 { "title", required_argument, NULL, 't' },
104 { "user", required_argument, NULL, 'u' },
105 { "syslog-priority", required_argument, NULL, 's' },
106 { "syslog-facility", required_argument, NULL, 'l' },
107 { "syslog-tag", required_argument, NULL, 'T' },
108 { "help", no_argument, NULL, 'h' },
112 static _Noreturn void
115 (void)fprintf(stderr,
116 "usage: daemon [-cfHrS] [-p child_pidfile] [-P supervisor_pidfile]\n"
117 " [-u user] [-o output_file] [-t title]\n"
118 " [-l syslog_facility] [-s syslog_priority]\n"
119 " [-T syslog_tag] [-m output_mask] [-R restart_delay_secs]\n"
120 "command arguments ...\n");
122 (void)fprintf(stderr,
123 " --change-dir -c Change the current working directory to root\n"
124 " --close-fds -f Set stdin, stdout, stderr to /dev/null\n"
125 " --sighup -H Close and re-open output file on SIGHUP\n"
126 " --syslog -S Send output to syslog\n"
127 " --output-file -o <file> Append output of the child process to file\n"
128 " --output-mask -m <mask> What to send to syslog/file\n"
129 " 1=stdout, 2=stderr, 3=both\n"
130 " --child-pidfile -p <file> Write PID of the child process to file\n"
131 " --supervisor-pidfile -P <file> Write PID of the supervisor process to file\n"
132 " --restart -r Restart child if it terminates (1 sec delay)\n"
133 " --restart-delay -R <N> Restart child if it terminates after N sec\n"
134 " --title -t <title> Set the title of the supervisor process\n"
135 " --user -u <user> Drop privileges, run as given user\n"
136 " --syslog-priority -s <prio> Set syslog priority\n"
137 " --syslog-facility -l <flty> Set syslog facility\n"
138 " --syslog-tag -T <tag> Set syslog tag\n"
139 " --help -h Show this help\n");
145 main(int argc, char *argv[])
147 bool supervision_enabled = false;
148 bool log_reopen = false;
150 const char *pidfile = NULL;
151 const char *ppidfile = NULL;
152 const char *title = NULL;
153 const char *user = NULL;
157 int pfd[2] = { -1, -1 };
159 int stdmask = STDOUT_FILENO | STDERR_FILENO;
160 struct log_params logpar = {
161 .syslog_enabled = false,
162 .syslog_priority = LOG_NOTICE,
163 .syslog_tag = "daemon",
164 .syslog_facility = LOG_DAEMON,
167 .output_filename = NULL
169 struct pidfh *ppfh = NULL;
170 struct pidfh *pfh = NULL;
176 sigemptyset(&mask_susp);
177 sigemptyset(&mask_read);
178 sigemptyset(&mask_term);
179 sigemptyset(&mask_orig);
181 while ((ch = getopt_long(argc, argv, shortopts, longopts, NULL)) != -1) {
193 logpar.syslog_facility = get_log_mapping(optarg, facilitynames);
194 if (logpar.syslog_facility == -1) {
195 errx(5, "unrecognized syslog facility");
197 logpar.syslog_enabled = true;
200 stdmask = strtol(optarg, &p, 10);
201 if (p == optarg || stdmask < 0 || stdmask > 3) {
202 errx(6, "unrecognized listening mask");
206 logpar.output_filename = optarg;
218 restart = strtol(optarg, &p, 0);
219 if (p == optarg || restart < 1) {
220 errx(6, "invalid restart delay");
224 logpar.syslog_priority = get_log_mapping(optarg, prioritynames);
225 if (logpar.syslog_priority == -1) {
226 errx(4, "unrecognized syslog priority");
228 logpar.syslog_enabled = true;
231 logpar.syslog_enabled = true;
237 logpar.syslog_tag = optarg;
238 logpar.syslog_enabled = true;
245 __builtin_unreachable();
261 if (logpar.output_filename) {
262 logpar.output_fd = open_log(logpar.output_filename);
263 if (logpar.output_fd == -1) {
268 if (logpar.syslog_enabled) {
269 openlog(logpar.syslog_tag, LOG_PID | LOG_NDELAY, logpar.syslog_facility);
273 * Try to open the pidfile before calling daemon(3),
274 * to be able to report the error intelligently
276 open_pid_files(pidfile, ppidfile, &pfh, &ppfh);
277 if (daemon(nochdir, logpar.noclose) == -1) {
281 /* Write out parent pidfile if needed. */
285 * Supervision mode is enabled if one of the following options are used:
287 * --supervisor-pidfile -P
288 * --restart -r / --restart-delay -R
290 * --syslog-facility -l
291 * --syslog-priority -s
294 * In supervision mode daemon executes the command in a forked process
295 * and observes the child by waiting for SIGCHILD. In supervision mode
296 * daemon must never exit before the child, this is necessary to prevent
297 * orphaning the child and leaving a stale pid file.
298 * To achieve this daemon catches SIGTERM and
299 * forwards it to the child, expecting to get SIGCHLD eventually.
301 supervision_enabled = pidfile != NULL ||
304 logpar.output_fd != -1 ||
305 logpar.syslog_enabled == true;
307 if (supervision_enabled) {
308 struct sigaction act_term = { 0 };
309 struct sigaction act_chld = { 0 };
310 struct sigaction act_hup = { 0 };
312 /* Avoid PID racing with SIGCHLD and SIGTERM. */
313 act_term.sa_handler = handle_term;
314 sigemptyset(&act_term.sa_mask);
315 sigaddset(&act_term.sa_mask, SIGCHLD);
317 act_chld.sa_handler = handle_chld;
318 sigemptyset(&act_chld.sa_mask);
319 sigaddset(&act_chld.sa_mask, SIGTERM);
321 act_hup.sa_handler = handle_hup;
322 sigemptyset(&act_hup.sa_mask);
324 /* Block these when avoiding racing before sigsuspend(). */
325 sigaddset(&mask_susp, SIGTERM);
326 sigaddset(&mask_susp, SIGCHLD);
327 /* Block SIGTERM when we lack a valid child PID. */
328 sigaddset(&mask_term, SIGTERM);
330 * When reading, we wish to avoid SIGCHLD. SIGTERM
331 * has to be caught, otherwise we'll be stuck until
332 * the read() returns - if it returns.
334 sigaddset(&mask_read, SIGCHLD);
335 /* Block SIGTERM to avoid racing until we have forked. */
336 if (sigprocmask(SIG_BLOCK, &mask_term, &mask_orig)) {
340 if (sigaction(SIGTERM, &act_term, NULL) == -1) {
344 if (sigaction(SIGCHLD, &act_chld, NULL) == -1) {
349 * Try to protect against pageout kill. Ignore the
350 * error, madvise(2) will fail only if a process does
351 * not have superuser privileges.
353 (void)madvise(NULL, 0, MADV_PROTECT);
354 if (log_reopen && logpar.output_fd >= 0 &&
355 sigaction(SIGHUP, &act_hup, NULL) == -1) {
364 * Spawn a child to exec the command.
371 } else if (pid > 0) {
373 * Unblock SIGTERM after we know we have a valid
374 * child PID to signal.
376 if (sigprocmask(SIG_UNBLOCK, &mask_term, NULL)) {
385 /* Now that we are the child, write out the pid. */
389 restrict_process(user);
392 * When forking, the child gets the original sigmask,
397 if (sigprocmask(SIG_SETMASK, &mask_orig, NULL)) {
398 err(1, "sigprogmask");
400 if (stdmask & STDERR_FILENO) {
401 if (dup2(pfd[1], STDERR_FILENO) == -1) {
405 if (stdmask & STDOUT_FILENO) {
406 if (dup2(pfd[1], STDOUT_FILENO) == -1) {
410 if (pfd[1] != STDERR_FILENO &&
411 pfd[1] != STDOUT_FILENO) {
415 execvp(argv[0], argv);
417 * execvp() failed -- report the error. The child is
418 * now running, so the exit status doesn't matter.
420 err(1, "%s", argv[0]);
422 setproctitle("%s[%d]", title, (int)pid);
424 * As we have closed the write end of pipe for parent process,
425 * we might detect the child's exit by reading EOF. The child
426 * might have closed its stdout and stderr, so we must wait for
427 * the SIGCHLD to ensure that the process is actually gone.
431 * We block SIGCHLD when listening, but SIGTERM we accept
432 * so the read() won't block if we wish to depart.
434 * Upon receiving SIGTERM, we have several options after
435 * sending the SIGTERM to our child:
437 * - read until EOF but only for a while
440 * We go for the third, as otherwise we have no guarantee
441 * that we won't block indefinitely if the child refuses
442 * to depart. To handle the second option, a different
443 * approach would be needed (procctl()?)
445 if (child_gone && child_eof) {
447 } else if (terminate) {
449 } else if (!child_eof) {
450 if (sigprocmask(SIG_BLOCK, &mask_read, NULL)) {
454 child_eof = !listen_child(pfd[0], &logpar);
455 if (sigprocmask(SIG_UNBLOCK, &mask_read, NULL)) {
460 if (sigprocmask(SIG_BLOCK, &mask_susp, NULL)) {
464 while (!terminate && !child_gone)
465 sigsuspend(&mask_orig);
466 if (sigprocmask(SIG_UNBLOCK, &mask_susp, NULL)) {
472 if (restart && !terminate) {
473 daemon_sleep(restart, 0);
475 if (sigprocmask(SIG_BLOCK, &mask_term, NULL)) {
479 if (restart && !terminate) {
485 close(logpar.output_fd);
488 if (logpar.syslog_enabled) {
492 pidfile_remove(ppfh);
493 exit(1); /* If daemon(3) succeeded exit status does not matter. */
497 daemon_sleep(time_t secs, long nsecs)
499 struct timespec ts = { secs, nsecs };
501 while (!terminate && nanosleep(&ts, &ts) == -1) {
502 if (errno != EINTR) {
509 open_pid_files(const char *pidfile, const char *ppidfile,
510 struct pidfh **pfh, struct pidfh **ppfh)
516 *pfh = pidfile_open(pidfile, 0600, &fpid);
518 if (errno == EEXIST) {
519 errx(3, "process already running, pid: %d",
522 err(2, "pidfile ``%s''", pidfile);
525 /* Do the same for the actual daemon process. */
527 *ppfh = pidfile_open(ppidfile, 0600, &fpid);
530 pidfile_remove(*pfh);
532 if (errno == EEXIST) {
533 errx(3, "process already running, pid: %d",
536 err(2, "ppidfile ``%s''", ppidfile);
542 get_log_mapping(const char *str, const CODE *c)
545 for (cp = c; cp->c_name; cp++)
546 if (strcmp(cp->c_name, str) == 0) {
553 restrict_process(const char *user)
555 struct passwd *pw = NULL;
559 errx(1, "unknown user: %s", user);
562 if (setusercontext(NULL, pw, pw->pw_uid, LOGIN_SETALL) != 0) {
563 errx(1, "failed to set user environment");
566 setenv("USER", pw->pw_name, 1);
567 setenv("HOME", pw->pw_dir, 1);
568 setenv("SHELL", *pw->pw_shell ? pw->pw_shell : _PATH_BSHELL, 1);
572 * We try to collect whole lines terminated by '\n'. Otherwise we collect a
573 * full buffer, and then output it.
575 * Return value of 0 is assumed to mean EOF or error, and 1 indicates to
579 listen_child(int fd, struct log_params *logpar)
581 static unsigned char buf[LBUF_SIZE];
582 static size_t bytes_read = 0;
586 assert(bytes_read < LBUF_SIZE - 1);
591 rv = read(fd, buf + bytes_read, LBUF_SIZE - bytes_read - 1);
596 assert(bytes_read <= LBUF_SIZE - 1);
597 /* Always NUL-terminate just in case. */
598 buf[LBUF_SIZE - 1] = '\0';
600 * Chomp line by line until we run out of buffer.
601 * This does not take NUL characters into account.
603 while ((cp = memchr(buf, '\n', bytes_read)) != NULL) {
604 size_t bytes_line = cp - buf + 1;
605 assert(bytes_line <= bytes_read);
606 do_output(buf, bytes_line, logpar);
607 bytes_read -= bytes_line;
608 memmove(buf, cp + 1, bytes_read);
610 /* Wait until the buffer is full. */
611 if (bytes_read < LBUF_SIZE - 1) {
614 do_output(buf, bytes_read, logpar);
617 } else if (rv == -1) {
618 /* EINTR should trigger another read. */
619 if (errno == EINTR) {
626 /* Upon EOF, we have to flush what's left of the buffer. */
627 if (bytes_read > 0) {
628 do_output(buf, bytes_read, logpar);
635 * The default behavior is to stay silent if the user wants to redirect
636 * output to a file and/or syslog. If neither are provided, then we bounce
637 * everything back to parent's stdout.
640 do_output(const unsigned char *buf, size_t len, struct log_params *logpar)
642 assert(len <= LBUF_SIZE);
648 if (logpar->syslog_enabled) {
649 syslog(logpar->syslog_priority, "%.*s", (int)len, buf);
651 if (logpar->output_fd != -1) {
652 if (write(logpar->output_fd, buf, len) == -1)
655 if (logpar->noclose && !logpar->syslog_enabled && logpar->output_fd == -1) {
656 printf("%.*s", (int)len, buf);
661 * We use the global PID acquired directly from fork. If there is no valid
662 * child pid, the handler should be blocked and/or child_gone == 1.
665 handle_term(int signo)
667 if (pid > 0 && !child_gone) {
674 handle_chld(int signo __unused)
678 int rv = waitpid(-1, NULL, WNOHANG);
682 } else if (rv == -1 && errno != EINTR) {
690 handle_hup(int signo __unused)
697 open_log(const char *outfn)
700 return open(outfn, O_CREAT | O_WRONLY | O_APPEND | O_CLOEXEC, 0600);
704 reopen_log(struct log_params *lpp)
709 outfd = open_log(lpp->output_filename);
710 if (lpp->output_fd >= 0) {
711 close(lpp->output_fd);
713 lpp->output_fd = outfd;