2 * Copyright (c) 2008, 2009, 2010, 2011 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 VLOG_ERR("%s: %s already running as pid %ld, aborting",
175 get_pidfile(), program_name, (long int) pid);
176 ovs_fatal(0, "%s: already running as pid %ld",
177 get_pidfile(), (long int) pid);
179 VLOG_WARN("%s: %s already running as pid %ld",
180 get_pidfile(), program_name, (long int) pid);
185 /* If a pidfile has been configured, creates it and stores the running
186 * process's pid in it. Ensures that the pidfile will be deleted when the
192 /* Create pidfile via temporary file, so that observers never see an
193 * empty pidfile or an unlocked pidfile. */
194 long int pid = getpid();
198 tmpfile = xasprintf("%s.tmp%ld", pidfile, pid);
199 fatal_signal_add_file_to_unlink(tmpfile);
200 fd = open(tmpfile, O_CREAT | O_WRONLY | O_TRUNC, 0666);
203 lck.l_type = F_WRLCK;
204 lck.l_whence = SEEK_SET;
207 if (fcntl(fd, F_SETLK, &lck) != -1) {
208 char *text = xasprintf("%ld\n", pid);
209 if (write(fd, text, strlen(text)) == strlen(text)) {
210 fatal_signal_add_file_to_unlink(pidfile);
211 if (rename(tmpfile, pidfile) < 0) {
212 VLOG_ERR("failed to rename \"%s\" to \"%s\": %s",
213 tmpfile, pidfile, strerror(errno));
214 fatal_signal_remove_file_to_unlink(pidfile);
217 /* Keep 'fd' open to retain the lock. */
220 if (!fstat(fd, &s)) {
221 pidfile_dev = s.st_dev;
222 pidfile_ino = s.st_ino;
224 VLOG_ERR("%s: fstat failed: %s",
225 pidfile, strerror(errno));
229 VLOG_ERR("%s: write failed: %s", tmpfile, strerror(errno));
234 VLOG_ERR("%s: fcntl failed: %s", tmpfile, strerror(errno));
238 VLOG_ERR("%s: create failed: %s", tmpfile, strerror(errno));
240 fatal_signal_remove_file_to_unlink(tmpfile);
247 /* If configured with set_pidfile() or set_detach(), creates the pid file and
248 * detaches from the foreground session. */
253 daemonize_complete();
257 fork_and_wait_for_startup(int *fdp)
263 ovs_fatal(errno, "pipe failed");
268 /* Running in parent process. */
273 if (read(fds[0], &c, 1) != 1) {
278 retval = waitpid(pid, &status, 0);
279 } while (retval == -1 && errno == EINTR);
283 && WEXITSTATUS(status)) {
284 /* Child exited with an error. Convey the same error to
285 * our parent process as a courtesy. */
286 exit(WEXITSTATUS(status));
289 ovs_fatal(errno, "fork child failed to signal startup");
294 /* Running in child process. */
300 ovs_fatal(errno, "could not fork");
307 fork_notify_startup(int fd)
310 size_t bytes_written;
313 error = write_fully(fd, "", 1, &bytes_written);
315 ovs_fatal(error, "could not write to pipe");
323 should_restart(int status)
325 if (WIFSIGNALED(status)) {
326 static const int error_signals[] = {
327 SIGABRT, SIGALRM, SIGBUS, SIGFPE, SIGILL, SIGPIPE, SIGSEGV,
333 for (i = 0; i < ARRAY_SIZE(error_signals); i++) {
334 if (error_signals[i] == WTERMSIG(status)) {
343 monitor_daemon(pid_t daemon_pid)
345 /* XXX Should log daemon's stderr output at startup time. */
346 const char *saved_program_name;
351 saved_program_name = program_name;
352 program_name = xasprintf("monitor(%s)", program_name);
353 status_msg = xstrdup("healthy");
354 last_restart = TIME_MIN;
360 proctitle_set("%s: monitoring pid %lu (%s)",
361 saved_program_name, (unsigned long int) daemon_pid,
365 retval = waitpid(daemon_pid, &status, 0);
366 } while (retval == -1 && errno == EINTR);
369 ovs_fatal(errno, "waitpid failed");
370 } else if (retval == daemon_pid) {
371 char *s = process_status_msg(status);
372 if (should_restart(status)) {
374 status_msg = xasprintf("%d crashes: pid %lu died, %s",
376 (unsigned long int) daemon_pid, s);
379 if (WCOREDUMP(status)) {
380 /* Disable further core dumps to save disk space. */
385 if (setrlimit(RLIMIT_CORE, &r) == -1) {
386 VLOG_WARN("failed to disable core dumps: %s",
391 /* Throttle restarts to no more than once every 10 seconds. */
392 if (time(NULL) < last_restart + 10) {
393 VLOG_WARN("%s, waiting until 10 seconds since last "
394 "restart", status_msg);
396 time_t now = time(NULL);
397 time_t wakeup = last_restart + 10;
404 last_restart = time(NULL);
406 VLOG_ERR("%s, restarting", status_msg);
407 daemon_pid = fork_and_wait_for_startup(&daemonize_fd);
412 VLOG_INFO("pid %lu died, %s, exiting",
413 (unsigned long int) daemon_pid, s);
421 /* Running in new daemon process. */
423 free((char *) program_name);
424 program_name = saved_program_name;
427 /* Close stdin, stdout, stderr. If we're started from e.g. an SSH session,
428 * then this keeps us from holding that session open artificially. */
430 close_standard_fds(void)
432 int null_fd = get_null_fd();
434 dup2(null_fd, STDIN_FILENO);
435 dup2(null_fd, STDOUT_FILENO);
436 dup2(null_fd, STDERR_FILENO);
440 /* If daemonization is configured, then starts daemonization, by forking and
441 * returning in the child process. The parent process hangs around until the
442 * child lets it know either that it completed startup successfully (by calling
443 * daemon_complete()) or that it failed to start up (by exiting with a nonzero
446 daemonize_start(void)
451 if (fork_and_wait_for_startup(&daemonize_fd) > 0) {
452 /* Running in parent process. */
455 /* Running in daemon or monitor process. */
459 int saved_daemonize_fd = daemonize_fd;
462 daemon_pid = fork_and_wait_for_startup(&daemonize_fd);
463 if (daemon_pid > 0) {
464 /* Running in monitor process. */
465 fork_notify_startup(saved_daemonize_fd);
466 close_standard_fds();
467 monitor_daemon(daemon_pid);
469 /* Running in daemon process. */
474 /* Make sure that the unixctl commands for vlog get registered in a
475 * daemon, even before the first log message. */
479 /* If daemonization is configured, then this function notifies the parent
480 * process that the child process has completed startup successfully.
482 * Calling this function more than once has no additional effect. */
484 daemonize_complete(void)
486 fork_notify_startup(daemonize_fd);
494 close_standard_fds();
503 "\nDaemon options:\n"
504 " --detach run in background as daemon\n"
505 " --no-chdir do not chdir to '/'\n"
506 " --pidfile[=FILE] create pidfile (default: %s/%s.pid)\n"
507 " --overwrite-pidfile with --pidfile, start even if already "
509 ovs_rundir(), program_name);
512 /* Opens and reads a PID from 'pidfile'. Returns the nonnegative PID if
513 * successful, otherwise a negative errno value. */
515 read_pidfile(const char *pidfile)
523 if ((pidfile_ino || pidfile_dev)
524 && !stat(pidfile, &s)
525 && s.st_ino == pidfile_ino && s.st_dev == pidfile_dev) {
526 /* It's our own pidfile. We can't afford to open it, because closing
527 * *any* fd for a file that a process has locked also releases all the
528 * locks on that file.
530 * Fortunately, we know the associated pid anyhow: */
534 file = fopen(pidfile, "r");
537 VLOG_WARN("%s: open: %s", pidfile, strerror(error));
541 lck.l_type = F_WRLCK;
542 lck.l_whence = SEEK_SET;
546 if (fcntl(fileno(file), F_GETLK, &lck)) {
548 VLOG_WARN("%s: fcntl: %s", pidfile, strerror(error));
551 if (lck.l_type == F_UNLCK) {
553 VLOG_WARN("%s: pid file is not locked", pidfile);
557 if (!fgets(line, sizeof line, file)) {
560 VLOG_WARN("%s: read: %s", pidfile, strerror(error));
563 VLOG_WARN("%s: read: unexpected end of file", pidfile);
568 if (lck.l_pid != strtoul(line, NULL, 10)) {
570 VLOG_WARN("l_pid (%ld) != %s pid (%s)",
571 (long int) lck.l_pid, pidfile, line);