1 /* Copyright (c) 2008 The Board of Trustees of The Leland Stanford
4 * We are making the OpenFlow specification and associated documentation
5 * (Software) available for public use and benefit with the expectation
6 * that others will use, modify and enhance the Software and contribute
7 * those enhancements back to the community. However, since we would
8 * like to make the Software available for broadest use, with as few
9 * restrictions as possible permission is hereby granted, free of
10 * charge, to any person obtaining a copy of this Software to deal in
11 * the Software under the copyrights without restriction, including
12 * without limitation the rights to use, copy, modify, merge, publish,
13 * distribute, sublicense, and/or sell copies of the Software, and to
14 * permit persons to whom the Software is furnished to do so, subject to
15 * the following conditions:
17 * The above copyright notice and this permission notice shall be
18 * included in all copies or substantial portions of the Software.
20 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
21 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
22 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
23 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
24 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
25 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
26 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
29 * The name and trademarks of copyright holder(s) may NOT be used in
30 * advertising or publicity pertaining to the Software or any
31 * derivatives without specific, written prior permission.
41 #include "fatal-signal.h"
45 #define THIS_MODULE VLM_daemon
48 /* Should we run in the background? */
51 /* Name of pidfile (null if none). */
54 /* Create pidfile even if one already exists and is locked? */
57 /* Returns the file name that would be used for a pidfile if 'name' were
58 * provided to set_pidfile(). The caller must free the returned string. */
60 make_pidfile_name(const char *name)
62 return (!name ? xasprintf("%s/%s.pid", ofp_rundir, program_name)
63 : *name == '/' ? xstrdup(name)
64 : xasprintf("%s/%s", ofp_rundir, name));
67 /* Sets up a following call to daemonize() to create a pidfile named 'name'.
68 * If 'name' begins with '/', then it is treated as an absolute path.
69 * Otherwise, it is taken relative to RUNDIR, which is $(prefix)/var/run by
72 * If 'name' is null, then program_name followed by ".pid" is used. */
74 set_pidfile(const char *name)
77 pidfile = make_pidfile_name(name);
80 /* Returns an absolute path to the configured pidfile, or a null pointer if no
81 * pidfile is configured. The caller must not modify or free the returned
89 /* Normally, die_if_already_running() will terminate the program with a message
90 * if a locked pidfile already exists. If this function is called,
91 * die_if_already_running() will merely log a warning. */
93 ignore_existing_pidfile(void)
98 /* Sets up a following call to daemonize() to detach from the foreground
99 * session, running this process in the background. */
106 /* If a pidfile has been configured and that pidfile already exists and is
107 * locked by a running process, returns the pid of the running process.
108 * Otherwise, returns 0. */
110 already_running(void)
114 int fd = open(pidfile, O_RDWR);
117 lck.l_type = F_WRLCK;
118 lck.l_whence = SEEK_SET;
121 if (fcntl(fd, F_GETLK, &lck) != -1 && lck.l_type != F_UNLCK) {
130 /* If a locked pidfile exists, issue a warning message and, unless
131 * ignore_existing_pidfile() has been called, terminate the program. */
133 die_if_already_running(void)
135 pid_t pid = already_running();
138 ofp_fatal(0, "%s: already running as pid %ld",
139 get_pidfile(), (long int) pid);
141 VLOG_WARN("%s: %s already running as pid %ld",
142 get_pidfile(), program_name, (long int) pid);
147 /* If a pidfile has been configured, creates it and stores the running process'
148 * pid init. Ensures that the pidfile will be deleted when the process
154 /* Create pidfile via temporary file, so that observers never see an
155 * empty pidfile or an unlocked pidfile. */
156 long int pid = getpid();
160 tmpfile = xasprintf("%s.tmp%ld", pidfile, pid);
161 fatal_signal_add_file_to_unlink(tmpfile);
162 fd = open(tmpfile, O_CREAT | O_WRONLY | O_TRUNC, 0666);
165 lck.l_type = F_WRLCK;
166 lck.l_whence = SEEK_SET;
169 if (fcntl(fd, F_SETLK, &lck) != -1) {
170 char *text = xasprintf("%ld\n", pid);
171 if (write(fd, text, strlen(text)) == strlen(text)) {
172 fatal_signal_add_file_to_unlink(pidfile);
173 if (rename(tmpfile, pidfile) < 0) {
174 VLOG_ERR("failed to rename \"%s\" to \"%s\": %s",
175 tmpfile, pidfile, strerror(errno));
176 fatal_signal_remove_file_to_unlink(pidfile);
179 /* Keep 'fd' open to retain the lock. */
182 VLOG_ERR("%s: write failed: %s", tmpfile, strerror(errno));
186 VLOG_ERR("%s: fcntl failed: %s", tmpfile, strerror(errno));
190 VLOG_ERR("%s: create failed: %s", tmpfile, strerror(errno));
192 fatal_signal_remove_file_to_unlink(tmpfile);
199 /* If configured with set_pidfile() or set_detach(), creates the pid file and
200 * detaches from the foreground session. */
208 ofp_fatal(errno, "pipe failed");
213 /* Parent process: wait for child to create pidfile, then exit. */
223 write(fds[1], &c, 1);
231 ofp_fatal(errno, "could not fork");
243 "\nDaemon options:\n"
244 " -D, --detach run in background as daemon\n"
245 " -P, --pidfile[=FILE] create pidfile (default: %s/%s.pid)\n"
246 " -f, --force with -P, start even if already running\n",
247 ofp_rundir, program_name);
250 /* Opens and reads a PID from 'pidfile'. Returns the nonnegative PID if
251 * successful, otherwise a negative errno value. */
253 read_pidfile(const char *pidfile)
260 file = fopen(pidfile, "r");
263 VLOG_WARN("%s: open: %s", pidfile, strerror(error));
267 lck.l_type = F_WRLCK;
268 lck.l_whence = SEEK_SET;
271 if (fcntl(fileno(file), F_GETLK, &lck)) {
273 VLOG_WARN("%s: fcntl: %s", pidfile, strerror(error));
277 if (!fgets(line, sizeof line, file)) {
279 VLOG_WARN("%s: read: %s", pidfile, strerror(error));
283 if (lck.l_pid != strtoul(line, NULL, 10)) {
285 VLOG_WARN("l_pid (%ld) != %s pid (%s)",
286 (long int) lck.l_pid, pidfile, line);