2 * Copyright (c) 2008, 2009, 2010 Nicira Networks.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at:
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
24 #include <sys/resource.h>
28 #include "command-line.h"
29 #include "fatal-signal.h"
33 #include "socket-util.h"
38 VLOG_DEFINE_THIS_MODULE(daemon)
40 /* --detach: Should we run in the background? */
43 /* --pidfile: Name of pidfile (null if none). */
46 /* Device and inode of pidfile, so we can avoid reopening it. */
47 static dev_t pidfile_dev;
48 static ino_t pidfile_ino;
50 /* --overwrite-pidfile: Create pidfile even if one already exists and is
52 static bool overwrite_pidfile;
54 /* --no-chdir: Should we chdir to "/"? */
55 static bool chdir_ = true;
57 /* File descriptor used by daemonize_start() and daemonize_complete(). */
58 static int daemonize_fd = -1;
60 /* --monitor: Should a supervisory process monitor the daemon and restart it if
61 * it dies due to an error signal? */
64 /* Returns the file name that would be used for a pidfile if 'name' were
65 * provided to set_pidfile(). The caller must free the returned string. */
67 make_pidfile_name(const char *name)
70 ? xasprintf("%s/%s.pid", ovs_rundir, program_name)
71 : abs_file_name(ovs_rundir, name));
74 /* Sets up a following call to daemonize() to create a pidfile named 'name'.
75 * If 'name' begins with '/', then it is treated as an absolute path.
76 * Otherwise, it is taken relative to RUNDIR, which is $(prefix)/var/run by
79 * If 'name' is null, then program_name followed by ".pid" is used. */
81 set_pidfile(const char *name)
84 pidfile = make_pidfile_name(name);
87 /* Returns an absolute path to the configured pidfile, or a null pointer if no
88 * pidfile is configured. The caller must not modify or free the returned
96 /* Sets that we do not chdir to "/". */
103 /* Will we chdir to "/" as part of daemonizing? */
105 is_chdir_enabled(void)
110 /* Normally, die_if_already_running() will terminate the program with a message
111 * if a locked pidfile already exists. If this function is called,
112 * die_if_already_running() will merely log a warning. */
114 ignore_existing_pidfile(void)
116 overwrite_pidfile = true;
119 /* Sets up a following call to daemonize() to detach from the foreground
120 * session, running this process in the background. */
127 /* Will daemonize() really detach? */
134 /* Sets up a following call to daemonize() to fork a supervisory process to
135 * monitor the daemon and restart it if it dies due to an error signal. */
137 daemon_set_monitor(void)
142 /* If a pidfile has been configured and that pidfile already exists and is
143 * locked by a running process, returns the pid of the running process.
144 * Otherwise, returns 0. */
146 already_running(void)
150 int fd = open(pidfile, O_RDWR);
153 lck.l_type = F_WRLCK;
154 lck.l_whence = SEEK_SET;
157 if (fcntl(fd, F_GETLK, &lck) != -1 && lck.l_type != F_UNLCK) {
166 /* If a locked pidfile exists, issue a warning message and, unless
167 * ignore_existing_pidfile() has been called, terminate the program. */
169 die_if_already_running(void)
171 pid_t pid = already_running();
173 if (!overwrite_pidfile) {
174 ovs_fatal(0, "%s: already running as pid %ld",
175 get_pidfile(), (long int) pid);
177 VLOG_WARN("%s: %s already running as pid %ld",
178 get_pidfile(), program_name, (long int) pid);
183 /* If a pidfile has been configured, creates it and stores the running
184 * process's pid in it. Ensures that the pidfile will be deleted when the
190 /* Create pidfile via temporary file, so that observers never see an
191 * empty pidfile or an unlocked pidfile. */
192 long int pid = getpid();
196 tmpfile = xasprintf("%s.tmp%ld", pidfile, pid);
197 fatal_signal_add_file_to_unlink(tmpfile);
198 fd = open(tmpfile, O_CREAT | O_WRONLY | O_TRUNC, 0666);
201 lck.l_type = F_WRLCK;
202 lck.l_whence = SEEK_SET;
205 if (fcntl(fd, F_SETLK, &lck) != -1) {
206 char *text = xasprintf("%ld\n", pid);
207 if (write(fd, text, strlen(text)) == strlen(text)) {
208 fatal_signal_add_file_to_unlink(pidfile);
209 if (rename(tmpfile, pidfile) < 0) {
210 VLOG_ERR("failed to rename \"%s\" to \"%s\": %s",
211 tmpfile, pidfile, strerror(errno));
212 fatal_signal_remove_file_to_unlink(pidfile);
215 /* Keep 'fd' open to retain the lock. */
218 if (!fstat(fd, &s)) {
219 pidfile_dev = s.st_dev;
220 pidfile_ino = s.st_ino;
222 VLOG_ERR("%s: fstat failed: %s",
223 pidfile, strerror(errno));
228 VLOG_ERR("%s: write failed: %s", tmpfile, strerror(errno));
232 VLOG_ERR("%s: fcntl failed: %s", tmpfile, strerror(errno));
236 VLOG_ERR("%s: create failed: %s", tmpfile, strerror(errno));
238 fatal_signal_remove_file_to_unlink(tmpfile);
245 /* If configured with set_pidfile() or set_detach(), creates the pid file and
246 * detaches from the foreground session. */
251 daemonize_complete();
255 fork_and_wait_for_startup(int *fdp)
261 ovs_fatal(errno, "pipe failed");
266 /* Running in parent process. */
271 if (read(fds[0], &c, 1) != 1) {
276 retval = waitpid(pid, &status, 0);
277 } while (retval == -1 && errno == EINTR);
281 && WEXITSTATUS(status)) {
282 /* Child exited with an error. Convey the same error to
283 * our parent process as a courtesy. */
284 exit(WEXITSTATUS(status));
287 ovs_fatal(errno, "fork child failed to signal startup");
292 /* Running in child process. */
298 ovs_fatal(errno, "could not fork");
305 fork_notify_startup(int fd)
308 size_t bytes_written;
311 error = write_fully(fd, "", 1, &bytes_written);
313 ovs_fatal(error, "could not write to pipe");
321 should_restart(int status)
323 if (WIFSIGNALED(status)) {
324 static const int error_signals[] = {
325 SIGABRT, SIGALRM, SIGBUS, SIGFPE, SIGILL, SIGPIPE, SIGSEGV,
331 for (i = 0; i < ARRAY_SIZE(error_signals); i++) {
332 if (error_signals[i] == WTERMSIG(status)) {
341 monitor_daemon(pid_t daemon_pid)
343 /* XXX Should log daemon's stderr output at startup time. */
344 const char *saved_program_name;
349 saved_program_name = program_name;
350 program_name = xasprintf("monitor(%s)", program_name);
351 status_msg = xstrdup("healthy");
352 last_restart = TIME_MIN;
358 proctitle_set("%s: monitoring pid %lu (%s)",
359 saved_program_name, (unsigned long int) daemon_pid,
363 retval = waitpid(daemon_pid, &status, 0);
364 } while (retval == -1 && errno == EINTR);
367 ovs_fatal(errno, "waitpid failed");
368 } else if (retval == daemon_pid) {
369 char *s = process_status_msg(status);
371 status_msg = xasprintf("%d crashes: pid %lu died, %s",
373 (unsigned long int) daemon_pid, s);
376 if (should_restart(status)) {
377 if (WCOREDUMP(status)) {
378 /* Disable further core dumps to save disk space. */
383 if (setrlimit(RLIMIT_CORE, &r) == -1) {
384 VLOG_WARN("failed to disable core dumps: %s",
389 /* Throttle restarts to no more than once every 10 seconds. */
390 if (time(NULL) < last_restart + 10) {
391 VLOG_WARN("%s, waiting until 10 seconds since last "
392 "restart", status_msg);
394 time_t now = time(NULL);
395 time_t wakeup = last_restart + 10;
402 last_restart = time(NULL);
404 VLOG_ERR("%s, restarting", status_msg);
405 daemon_pid = fork_and_wait_for_startup(&daemonize_fd);
410 VLOG_INFO("%s, exiting", status_msg);
417 /* Running in new daemon process. */
419 free((char *) program_name);
420 program_name = saved_program_name;
423 /* Close stdin, stdout, stderr. If we're started from e.g. an SSH session,
424 * then this keeps us from holding that session open artificially. */
426 close_standard_fds(void)
428 int null_fd = get_null_fd();
430 dup2(null_fd, STDIN_FILENO);
431 dup2(null_fd, STDOUT_FILENO);
432 dup2(null_fd, STDERR_FILENO);
436 /* If daemonization is configured, then starts daemonization, by forking and
437 * returning in the child process. The parent process hangs around until the
438 * child lets it know either that it completed startup successfully (by calling
439 * daemon_complete()) or that it failed to start up (by exiting with a nonzero
442 daemonize_start(void)
447 if (fork_and_wait_for_startup(&daemonize_fd) > 0) {
448 /* Running in parent process. */
451 /* Running in daemon or monitor process. */
455 int saved_daemonize_fd = daemonize_fd;
458 daemon_pid = fork_and_wait_for_startup(&daemonize_fd);
459 if (daemon_pid > 0) {
460 /* Running in monitor process. */
461 fork_notify_startup(saved_daemonize_fd);
462 close_standard_fds();
463 monitor_daemon(daemon_pid);
465 /* Running in daemon process. */
470 /* Make sure that the unixctl commands for vlog get registered in a
471 * daemon, even before the first log message. */
475 /* If daemonization is configured, then this function notifies the parent
476 * process that the child process has completed startup successfully. */
478 daemonize_complete(void)
480 fork_notify_startup(daemonize_fd);
487 close_standard_fds();
495 "\nDaemon options:\n"
496 " --detach run in background as daemon\n"
497 " --no-chdir do not chdir to '/'\n"
498 " --pidfile[=FILE] create pidfile (default: %s/%s.pid)\n"
499 " --overwrite-pidfile with --pidfile, start even if already "
501 ovs_rundir, program_name);
504 /* Opens and reads a PID from 'pidfile'. Returns the nonnegative PID if
505 * successful, otherwise a negative errno value. */
507 read_pidfile(const char *pidfile)
515 if ((pidfile_ino || pidfile_dev)
516 && !stat(pidfile, &s)
517 && s.st_ino == pidfile_ino && s.st_dev == pidfile_dev) {
518 /* It's our own pidfile. We can't afford to open it, because closing
519 * *any* fd for a file that a process has locked also releases all the
520 * locks on that file.
522 * Fortunately, we know the associated pid anyhow: */
526 file = fopen(pidfile, "r");
529 VLOG_WARN("%s: open: %s", pidfile, strerror(error));
533 lck.l_type = F_WRLCK;
534 lck.l_whence = SEEK_SET;
537 if (fcntl(fileno(file), F_GETLK, &lck)) {
539 VLOG_WARN("%s: fcntl: %s", pidfile, strerror(error));
542 if (lck.l_type == F_UNLCK) {
544 VLOG_WARN("%s: pid file is not locked", pidfile);
548 if (!fgets(line, sizeof line, file)) {
551 VLOG_WARN("%s: read: %s", pidfile, strerror(error));
554 VLOG_WARN("%s: read: unexpected end of file", pidfile);
559 if (lck.l_pid != strtoul(line, NULL, 10)) {
561 VLOG_WARN("l_pid (%ld) != %s pid (%s)",
562 (long int) lck.l_pid, pidfile, line);