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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.
25 #include "command-line.h"
26 #include "fatal-signal.h"
30 #include "socket-util.h"
34 #define THIS_MODULE VLM_daemon
37 /* Should we run in the background? */
40 /* Name of pidfile (null if none). */
43 /* Create pidfile even if one already exists and is locked? */
44 static bool overwrite_pidfile
;
46 /* Should we chdir to "/"? */
47 static bool chdir_
= true;
49 /* File descriptor used by daemonize_start() and daemonize_complete(). */
50 static int daemonize_fd
= -1;
52 /* --monitor: Should a supervisory process monitor the daemon and restart it if
53 * it dies due to an error signal? */
56 /* Returns the file name that would be used for a pidfile if 'name' were
57 * provided to set_pidfile(). The caller must free the returned string. */
59 make_pidfile_name(const char *name
)
61 return (!name
? xasprintf("%s/%s.pid", ovs_rundir
, program_name
)
62 : *name
== '/' ? xstrdup(name
)
63 : xasprintf("%s/%s", ovs_rundir
, name
));
66 /* Sets up a following call to daemonize() to create a pidfile named 'name'.
67 * If 'name' begins with '/', then it is treated as an absolute path.
68 * Otherwise, it is taken relative to RUNDIR, which is $(prefix)/var/run by
71 * If 'name' is null, then program_name followed by ".pid" is used. */
73 set_pidfile(const char *name
)
76 pidfile
= make_pidfile_name(name
);
79 /* Returns an absolute path to the configured pidfile, or a null pointer if no
80 * pidfile is configured. The caller must not modify or free the returned
88 /* Sets that we do not chdir to "/". */
95 /* Will we chdir to "/" as part of daemonizing? */
97 is_chdir_enabled(void)
102 /* Normally, die_if_already_running() will terminate the program with a message
103 * if a locked pidfile already exists. If this function is called,
104 * die_if_already_running() will merely log a warning. */
106 ignore_existing_pidfile(void)
108 overwrite_pidfile
= true;
111 /* Sets up a following call to daemonize() to detach from the foreground
112 * session, running this process in the background. */
119 /* Will daemonize() really detach? */
126 /* Sets up a following call to daemonize() to fork a supervisory process to
127 * monitor the daemon and restart it if it dies due to an error signal. */
129 daemon_set_monitor(void)
134 /* If a pidfile has been configured and that pidfile already exists and is
135 * locked by a running process, returns the pid of the running process.
136 * Otherwise, returns 0. */
138 already_running(void)
142 int fd
= open(pidfile
, O_RDWR
);
145 lck
.l_type
= F_WRLCK
;
146 lck
.l_whence
= SEEK_SET
;
149 if (fcntl(fd
, F_GETLK
, &lck
) != -1 && lck
.l_type
!= F_UNLCK
) {
158 /* If a locked pidfile exists, issue a warning message and, unless
159 * ignore_existing_pidfile() has been called, terminate the program. */
161 die_if_already_running(void)
163 pid_t pid
= already_running();
165 if (!overwrite_pidfile
) {
166 ovs_fatal(0, "%s: already running as pid %ld",
167 get_pidfile(), (long int) pid
);
169 VLOG_WARN("%s: %s already running as pid %ld",
170 get_pidfile(), program_name
, (long int) pid
);
175 /* If a pidfile has been configured, creates it and stores the running process'
176 * pid init. Ensures that the pidfile will be deleted when the process
182 /* Create pidfile via temporary file, so that observers never see an
183 * empty pidfile or an unlocked pidfile. */
184 long int pid
= getpid();
188 tmpfile
= xasprintf("%s.tmp%ld", pidfile
, pid
);
189 fatal_signal_add_file_to_unlink(tmpfile
);
190 fd
= open(tmpfile
, O_CREAT
| O_WRONLY
| O_TRUNC
, 0666);
193 lck
.l_type
= F_WRLCK
;
194 lck
.l_whence
= SEEK_SET
;
197 if (fcntl(fd
, F_SETLK
, &lck
) != -1) {
198 char *text
= xasprintf("%ld\n", pid
);
199 if (write(fd
, text
, strlen(text
)) == strlen(text
)) {
200 fatal_signal_add_file_to_unlink(pidfile
);
201 if (rename(tmpfile
, pidfile
) < 0) {
202 VLOG_ERR("failed to rename \"%s\" to \"%s\": %s",
203 tmpfile
, pidfile
, strerror(errno
));
204 fatal_signal_remove_file_to_unlink(pidfile
);
207 /* Keep 'fd' open to retain the lock. */
211 VLOG_ERR("%s: write failed: %s", tmpfile
, strerror(errno
));
215 VLOG_ERR("%s: fcntl failed: %s", tmpfile
, strerror(errno
));
219 VLOG_ERR("%s: create failed: %s", tmpfile
, strerror(errno
));
221 fatal_signal_remove_file_to_unlink(tmpfile
);
228 /* If configured with set_pidfile() or set_detach(), creates the pid file and
229 * detaches from the foreground session. */
234 daemonize_complete();
238 fork_and_wait_for_startup(int *fdp
)
244 ovs_fatal(errno
, "pipe failed");
249 /* Running in parent process. */
254 if (read(fds
[0], &c
, 1) != 1) {
259 retval
= waitpid(pid
, &status
, 0);
260 } while (retval
== -1 && errno
== EINTR
);
264 && WEXITSTATUS(status
)) {
265 /* Child exited with an error. Convey the same error to
266 * our parent process as a courtesy. */
267 exit(WEXITSTATUS(status
));
270 ovs_fatal(errno
, "fork child failed to signal startup");
275 /* Running in child process. */
281 ovs_fatal(errno
, "could not fork");
288 fork_notify_startup(int fd
)
291 size_t bytes_written
;
294 error
= write_fully(fd
, "", 1, &bytes_written
);
296 ovs_fatal(error
, "could not write to pipe");
304 should_restart(int status
)
306 if (WIFSIGNALED(status
)) {
307 static const int error_signals
[] = {
308 SIGABRT
, SIGALRM
, SIGBUS
, SIGFPE
, SIGILL
, SIGPIPE
, SIGSEGV
,
314 for (i
= 0; i
< ARRAY_SIZE(error_signals
); i
++) {
315 if (error_signals
[i
] == WTERMSIG(status
)) {
324 monitor_daemon(pid_t daemon_pid
)
326 /* XXX Should limit the rate at which we restart the daemon. */
327 /* XXX Should log daemon's stderr output at startup time. */
328 const char *saved_program_name
;
331 saved_program_name
= program_name
;
332 program_name
= xasprintf("monitor(%s)", program_name
);
333 status_msg
= xstrdup("healthy");
338 proctitle_set("%s: monitoring pid %lu (%s)",
339 saved_program_name
, (unsigned long int) daemon_pid
,
343 retval
= waitpid(daemon_pid
, &status
, 0);
344 } while (retval
== -1 && errno
== EINTR
);
347 ovs_fatal(errno
, "waitpid failed");
348 } else if (retval
== daemon_pid
) {
349 char *s
= process_status_msg(status
);
351 status_msg
= xasprintf("pid %lu died, %s",
352 (unsigned long int) daemon_pid
, s
);
355 if (should_restart(status
)) {
356 VLOG_ERR("%s, restarting", status_msg
);
357 daemon_pid
= fork_and_wait_for_startup(&daemonize_fd
);
362 VLOG_INFO("%s, exiting", status_msg
);
369 /* Running in new daemon process. */
371 free((char *) program_name
);
372 program_name
= saved_program_name
;
375 /* Close stdin, stdout, stderr. If we're started from e.g. an SSH session,
376 * then this keeps us from holding that session open artificially. */
378 close_standard_fds(void)
380 int null_fd
= get_null_fd();
382 dup2(null_fd
, STDIN_FILENO
);
383 dup2(null_fd
, STDOUT_FILENO
);
384 dup2(null_fd
, STDERR_FILENO
);
388 /* If daemonization is configured, then starts daemonization, by forking and
389 * returning in the child process. The parent process hangs around until the
390 * child lets it know either that it completed startup successfully (by calling
391 * daemon_complete()) or that it failed to start up (by exiting with a nonzero
394 daemonize_start(void)
399 if (fork_and_wait_for_startup(&daemonize_fd
) > 0) {
400 /* Running in parent process. */
403 /* Running in daemon or monitor process. */
407 int saved_daemonize_fd
= daemonize_fd
;
410 daemon_pid
= fork_and_wait_for_startup(&daemonize_fd
);
411 if (daemon_pid
> 0) {
412 /* Running in monitor process. */
413 fork_notify_startup(saved_daemonize_fd
);
414 close_standard_fds();
415 monitor_daemon(daemon_pid
);
417 /* Running in daemon process. */
423 /* If daemonization is configured, then this function notifies the parent
424 * process that the child process has completed startup successfully. */
426 daemonize_complete(void)
428 fork_notify_startup(daemonize_fd
);
435 close_standard_fds();
443 "\nDaemon options:\n"
444 " --detach run in background as daemon\n"
445 " --no-chdir do not chdir to '/'\n"
446 " --pidfile[=FILE] create pidfile (default: %s/%s.pid)\n"
447 " --overwrite-pidfile with --pidfile, start even if already "
449 ovs_rundir
, program_name
);
452 /* Opens and reads a PID from 'pidfile'. Returns the nonnegative PID if
453 * successful, otherwise a negative errno value. */
455 read_pidfile(const char *pidfile
)
462 file
= fopen(pidfile
, "r");
465 VLOG_WARN("%s: open: %s", pidfile
, strerror(error
));
469 lck
.l_type
= F_WRLCK
;
470 lck
.l_whence
= SEEK_SET
;
473 if (fcntl(fileno(file
), F_GETLK
, &lck
)) {
475 VLOG_WARN("%s: fcntl: %s", pidfile
, strerror(error
));
478 if (lck
.l_type
== F_UNLCK
) {
480 VLOG_WARN("%s: pid file is not locked", pidfile
);
484 if (!fgets(line
, sizeof line
, file
)) {
487 VLOG_WARN("%s: read: %s", pidfile
, strerror(error
));
490 VLOG_WARN("%s: read: unexpected end of file", pidfile
);
495 if (lck
.l_pid
!= strtoul(line
, NULL
, 10)) {
497 VLOG_WARN("l_pid (%ld) != %s pid (%s)",
498 (long int) lck
.l_pid
, pidfile
, line
);