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"
44 #define THIS_MODULE VLM_daemon
47 /* Should we run in the background? */
50 /* Name of pidfile (null if none). */
53 /* Create pidfile even if one already exists and is locked? */
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", RUNDIR, program_name)
62 : *name == '/' ? xstrdup(name)
63 : xasprintf("%s/%s", 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 /* Normally, die_if_already_running() will terminate the program with a message
89 * if a locked pidfile already exists. If this function is called,
90 * die_if_already_running() will merely log a warning. */
92 ignore_existing_pidfile(void)
97 /* Sets up a following call to daemonize() to detach from the foreground
98 * session, running this process in the background. */
105 /* If a pidfile has been configured and that pidfile already exists and is
106 * locked by a running process, returns the pid of the running process.
107 * Otherwise, returns 0. */
109 already_running(void)
113 int fd = open(pidfile, O_RDWR);
116 lck.l_type = F_WRLCK;
117 lck.l_whence = SEEK_SET;
120 if (fcntl(fd, F_GETLK, &lck) != -1 && lck.l_type != F_UNLCK) {
129 /* If a locked pidfile exists, issue a warning message and, unless
130 * ignore_existing_pidfile() has been called, terminate the program. */
132 die_if_already_running(void)
134 pid_t pid = already_running();
137 fatal(0, "%s: already running as pid %ld",
138 get_pidfile(), (long int) pid);
140 VLOG_WARN("%s: %s already running as pid %ld",
141 get_pidfile(), program_name, (long int) pid);
146 /* If a pidfile has been configured, creates it and stores the running process'
147 * pid init. Ensures that the pidfile will be deleted when the process
153 /* Create pidfile via temporary file, so that observers never see an
154 * empty pidfile or an unlocked pidfile. */
155 long int pid = getpid();
159 tmpfile = xasprintf("%s.tmp%ld", pidfile, pid);
160 fatal_signal_add_file_to_unlink(tmpfile);
161 fd = open(tmpfile, O_CREAT | O_WRONLY | O_TRUNC, 0666);
164 lck.l_type = F_WRLCK;
165 lck.l_whence = SEEK_SET;
168 if (fcntl(fd, F_SETLK, &lck) != -1) {
169 char *text = xasprintf("%ld\n", pid);
170 if (write(fd, text, strlen(text)) == strlen(text)) {
171 fatal_signal_add_file_to_unlink(pidfile);
172 if (rename(tmpfile, pidfile) < 0) {
173 VLOG_ERR("failed to rename \"%s\" to \"%s\": %s",
174 tmpfile, pidfile, strerror(errno));
175 fatal_signal_remove_file_to_unlink(pidfile);
178 /* Keep 'fd' open to retain the lock. */
181 VLOG_ERR("%s: write failed: %s", tmpfile, strerror(errno));
185 VLOG_ERR("%s: fcntl failed: %s", tmpfile, strerror(errno));
189 VLOG_ERR("%s: create failed: %s", tmpfile, strerror(errno));
191 fatal_signal_remove_file_to_unlink(tmpfile);
198 /* If configured with set_pidfile() or set_detach(), creates the pid file and
199 * detaches from the foreground session. */
207 fatal(errno, "pipe failed");
212 /* Parent process: wait for child to create pidfile, then exit. */
222 write(fds[1], &c, 1);
230 fatal(errno, "could not fork");