* it dies due to an error signal? */
static bool monitor;
+static void check_already_running(void);
+static int lock_pidfile(FILE *, int command);
+
/* Returns the file name that would be used for a pidfile if 'name' were
* provided to set_pidfile(). The caller must free the returned string. */
char *
return chdir_;
}
-/* Normally, die_if_already_running() will terminate the program with a message
- * if a locked pidfile already exists. If this function is called,
- * die_if_already_running() will merely log a warning. */
+/* Normally, daemonize() or damonize_start() will terminate the program with a
+ * message if a locked pidfile already exists. If this function is called, an
+ * existing pidfile will be replaced, with a warning. */
void
ignore_existing_pidfile(void)
{
monitor = true;
}
-/* If a pidfile has been configured and that pidfile already exists and is
- * locked by a running process, returns the pid of the running process.
- * Otherwise, returns 0. */
-static pid_t
-already_running(void)
-{
- pid_t pid = 0;
- if (pidfile) {
- int fd = open(pidfile, O_RDWR);
- if (fd >= 0) {
- struct flock lck;
- lck.l_type = F_WRLCK;
- lck.l_whence = SEEK_SET;
- lck.l_start = 0;
- lck.l_len = 0;
- if (fcntl(fd, F_GETLK, &lck) != -1 && lck.l_type != F_UNLCK) {
- pid = lck.l_pid;
- }
- close(fd);
- }
- }
- return pid;
-}
-
-/* If a locked pidfile exists, issue a warning message and, unless
- * ignore_existing_pidfile() has been called, terminate the program. */
-void
-die_if_already_running(void)
-{
- pid_t pid = already_running();
- if (pid) {
- if (!overwrite_pidfile) {
- ovs_fatal(0, "%s: already running as pid %ld",
- get_pidfile(), (long int) pid);
- } else {
- VLOG_WARN("%s: %s already running as pid %ld",
- get_pidfile(), program_name, (long int) pid);
- }
- }
-}
-
/* If a pidfile has been configured, creates it and stores the running
* process's pid in it. Ensures that the pidfile will be deleted when the
* process exits. */
static void
make_pidfile(void)
{
- if (pidfile) {
- /* Create pidfile via temporary file, so that observers never see an
- * empty pidfile or an unlocked pidfile. */
- long int pid = getpid();
- char *tmpfile;
- int fd;
-
- tmpfile = xasprintf("%s.tmp%ld", pidfile, pid);
- fatal_signal_add_file_to_unlink(tmpfile);
- fd = open(tmpfile, O_CREAT | O_WRONLY | O_TRUNC, 0666);
- if (fd >= 0) {
- struct flock lck;
- lck.l_type = F_WRLCK;
- lck.l_whence = SEEK_SET;
- lck.l_start = 0;
- lck.l_len = 0;
- if (fcntl(fd, F_SETLK, &lck) != -1) {
- char *text = xasprintf("%ld\n", pid);
- if (write(fd, text, strlen(text)) == strlen(text)) {
- fatal_signal_add_file_to_unlink(pidfile);
- if (rename(tmpfile, pidfile) < 0) {
- VLOG_ERR("failed to rename \"%s\" to \"%s\": %s",
- tmpfile, pidfile, strerror(errno));
- fatal_signal_remove_file_to_unlink(pidfile);
- close(fd);
- } else {
- /* Keep 'fd' open to retain the lock. */
- struct stat s;
-
- if (!fstat(fd, &s)) {
- pidfile_dev = s.st_dev;
- pidfile_ino = s.st_ino;
- } else {
- VLOG_ERR("%s: fstat failed: %s",
- pidfile, strerror(errno));
- }
- }
- free(text);
- } else {
- VLOG_ERR("%s: write failed: %s", tmpfile, strerror(errno));
- close(fd);
- }
- } else {
- VLOG_ERR("%s: fcntl failed: %s", tmpfile, strerror(errno));
- close(fd);
+ long int pid = getpid();
+ struct stat s;
+ char *tmpfile;
+ FILE *file;
+ int error;
+
+ /* Create a temporary pidfile. */
+ tmpfile = xasprintf("%s.tmp%ld", pidfile, pid);
+ fatal_signal_add_file_to_unlink(tmpfile);
+ file = fopen(tmpfile, "w+");
+ if (!file) {
+ VLOG_FATAL("%s: create failed (%s)", tmpfile, strerror(errno));
+ }
+
+ if (fstat(fileno(file), &s) == -1) {
+ VLOG_FATAL("%s: fstat failed (%s)", tmpfile, strerror(errno));
+ }
+
+ fprintf(file, "%ld\n", pid);
+ if (fflush(file) == EOF) {
+ VLOG_FATAL("%s: write failed (%s)", tmpfile, strerror(errno));
+ }
+
+ error = lock_pidfile(file, F_SETLK);
+ if (error) {
+ VLOG_FATAL("%s: fcntl(F_SETLK) failed (%s)", tmpfile, strerror(error));
+ }
+
+ /* Rename or link it to the correct name. */
+ if (overwrite_pidfile) {
+ if (rename(tmpfile, pidfile) < 0) {
+ VLOG_FATAL("failed to rename \"%s\" to \"%s\" (%s)",
+ tmpfile, pidfile, strerror(errno));
+ }
+ } else {
+ do {
+ error = link(tmpfile, pidfile) == -1 ? errno : 0;
+ if (error == EEXIST) {
+ check_already_running();
}
- } else {
- VLOG_ERR("%s: create failed: %s", tmpfile, strerror(errno));
+ } while (error == EINTR || error == EEXIST);
+ if (error) {
+ VLOG_FATAL("failed to link \"%s\" as \"%s\" (%s)",
+ tmpfile, pidfile, strerror(error));
+ }
+ }
+
+ /* Ensure that the pidfile will get deleted on exit. */
+ fatal_signal_add_file_to_unlink(pidfile);
+
+ /* Delete the temporary pidfile if it still exists. */
+ if (!overwrite_pidfile) {
+ error = fatal_signal_unlink_file_now(tmpfile);
+ if (error) {
+ VLOG_FATAL("%s: unlink failed (%s)", tmpfile, strerror(error));
}
- fatal_signal_remove_file_to_unlink(tmpfile);
- free(tmpfile);
}
+
+ /* Clean up.
+ *
+ * We don't close 'file' because its file descriptor must remain open to
+ * hold the lock. */
+ pidfile_dev = s.st_dev;
+ pidfile_ino = s.st_ino;
+ free(tmpfile);
free(pidfile);
pidfile = NULL;
}
int fds[2];
pid_t pid;
- if (pipe(fds) < 0) {
- ovs_fatal(errno, "pipe failed");
- }
+ xpipe(fds);
pid = fork();
if (pid > 0) {
/* Running in parent process. */
+ size_t bytes_read;
char c;
close(fds[1]);
fatal_signal_fork();
- if (read(fds[0], &c, 1) != 1) {
+ if (read_fully(fds[0], &c, 1, &bytes_read) != 0) {
int retval;
int status;
exit(WEXITSTATUS(status));
}
- ovs_fatal(errno, "fork child failed to signal startup");
+ VLOG_FATAL("fork child failed to signal startup (%s)",
+ strerror(errno));
}
close(fds[0]);
*fdp = -1;
lockfile_postfork();
*fdp = fds[1];
} else {
- ovs_fatal(errno, "could not fork");
+ VLOG_FATAL("fork failed (%s)", strerror(errno));
}
return pid;
error = write_fully(fd, "", 1, &bytes_written);
if (error) {
- ovs_fatal(error, "could not write to pipe");
+ VLOG_FATAL("pipe write failed (%s)", strerror(error));
}
close(fd);
} while (retval == -1 && errno == EINTR);
if (retval == -1) {
- ovs_fatal(errno, "waitpid failed");
+ VLOG_FATAL("waitpid failed (%s)", strerror(errno));
} else if (retval == daemon_pid) {
char *s = process_status_msg(status);
if (should_restart(status)) {
dup2(null_fd, STDOUT_FILENO);
dup2(null_fd, STDERR_FILENO);
}
+
+ /* Disable logging to stderr to avoid wasting CPU time. */
+ vlog_set_levels(NULL, VLF_CONSOLE, VLL_OFF);
}
/* If daemonization is configured, then starts daemonization, by forking and
/* Running in daemon process. */
}
- make_pidfile();
+ if (pidfile) {
+ make_pidfile();
+ }
/* Make sure that the unixctl commands for vlog get registered in a
* daemon, even before the first log message. */
}
/* If daemonization is configured, then this function notifies the parent
- * process that the child process has completed startup successfully. */
+ * process that the child process has completed startup successfully.
+ *
+ * Calling this function more than once has no additional effect. */
void
daemonize_complete(void)
{
fork_notify_startup(daemonize_fd);
+ daemonize_fd = -1;
if (detach) {
setsid();
ignore(chdir("/"));
}
close_standard_fds();
+ detach = false;
}
}
ovs_rundir(), program_name);
}
-/* Opens and reads a PID from 'pidfile'. Returns the nonnegative PID if
- * successful, otherwise a negative errno value. */
-pid_t
-read_pidfile(const char *pidfile)
+static int
+lock_pidfile__(FILE *file, int command, struct flock *lck)
+{
+ int error;
+
+ lck->l_type = F_WRLCK;
+ lck->l_whence = SEEK_SET;
+ lck->l_start = 0;
+ lck->l_len = 0;
+ lck->l_pid = 0;
+
+ do {
+ error = fcntl(fileno(file), command, lck) == -1 ? errno : 0;
+ } while (error == EINTR);
+ return error;
+}
+
+static int
+lock_pidfile(FILE *file, int command)
{
- char line[128];
struct flock lck;
- struct stat s;
+
+ return lock_pidfile__(file, command, &lck);
+}
+
+static pid_t
+read_pidfile__(const char *pidfile, bool delete_if_stale)
+{
+ struct stat s, s2;
+ struct flock lck;
+ char line[128];
FILE *file;
int error;
return getpid();
}
- file = fopen(pidfile, "r");
+ file = fopen(pidfile, "r+");
if (!file) {
+ if (errno == ENOENT && delete_if_stale) {
+ return 0;
+ }
error = errno;
VLOG_WARN("%s: open: %s", pidfile, strerror(error));
goto error;
}
- lck.l_type = F_WRLCK;
- lck.l_whence = SEEK_SET;
- lck.l_start = 0;
- lck.l_len = 0;
- lck.l_pid = 0;
- if (fcntl(fileno(file), F_GETLK, &lck)) {
- error = errno;
+ error = lock_pidfile__(file, F_GETLK, &lck);
+ if (error) {
VLOG_WARN("%s: fcntl: %s", pidfile, strerror(error));
goto error;
}
if (lck.l_type == F_UNLCK) {
- error = ESRCH;
- VLOG_WARN("%s: pid file is not locked", pidfile);
- goto error;
+ /* pidfile exists but it isn't locked by anyone. We need to delete it
+ * so that a new pidfile can go in its place. But just calling
+ * unlink(pidfile) makes a nasty race: what if someone else unlinks it
+ * before we do and then replaces it by a valid pidfile? We'd unlink
+ * their valid pidfile. We do a little dance to avoid the race, by
+ * locking the invalid pidfile. Only one process can have the invalid
+ * pidfile locked, and only that process has the right to unlink it. */
+ if (!delete_if_stale) {
+ error = ESRCH;
+ VLOG_DBG("%s: pid file is stale", pidfile);
+ goto error;
+ }
+
+ /* Get the lock. */
+ error = lock_pidfile(file, F_SETLK);
+ if (error) {
+ /* We lost a race with someone else doing the same thing. */
+ VLOG_WARN("%s: lost race to lock pidfile", pidfile);
+ goto error;
+ }
+
+ /* Is the file we have locked still named 'pidfile'? */
+ if (stat(pidfile, &s) || fstat(fileno(file), &s2)
+ || s.st_ino != s2.st_ino || s.st_dev != s2.st_dev) {
+ /* No. We lost a race with someone else who got the lock before
+ * us, deleted the pidfile, and closed it (releasing the lock). */
+ error = EALREADY;
+ VLOG_WARN("%s: lost race to delete pidfile", pidfile);
+ goto error;
+ }
+
+ /* We won the right to delete the stale pidfile. */
+ if (unlink(pidfile)) {
+ error = errno;
+ VLOG_WARN("%s: failed to delete stale pidfile (%s)",
+ pidfile, strerror(error));
+ goto error;
+ }
+ VLOG_DBG("%s: deleted stale pidfile", pidfile);
+ fclose(file);
+ return 0;
}
if (!fgets(line, sizeof line, file)) {
}
if (lck.l_pid != strtoul(line, NULL, 10)) {
+ /* The process that has the pidfile locked is not the process that
+ * created it. It must be stale, with the process that has it locked
+ * preparing to delete it. */
error = ESRCH;
- VLOG_WARN("l_pid (%ld) != %s pid (%s)",
- (long int) lck.l_pid, pidfile, line);
+ VLOG_WARN("%s: stale pidfile for pid %s being deleted by pid %ld",
+ pidfile, line, (long int) lck.l_pid);
goto error;
}
}
return -error;
}
+
+/* Opens and reads a PID from 'pidfile'. Returns the positive PID if
+ * successful, otherwise a negative errno value. */
+pid_t
+read_pidfile(const char *pidfile)
+{
+ return read_pidfile__(pidfile, false);
+}
+
+/* Checks whether a process with the given 'pidfile' is already running and,
+ * if so, aborts. If 'pidfile' is stale, deletes it. */
+static void
+check_already_running(void)
+{
+ long int pid = read_pidfile__(pidfile, true);
+ if (pid > 0) {
+ VLOG_FATAL("%s: already running as pid %ld, aborting", pidfile, pid);
+ } else if (pid < 0) {
+ VLOG_FATAL("%s: pidfile check failed (%s), aborting",
+ pidfile, strerror(-pid));
+ }
+}
git://git.onelab.eu / sliver-openvswitch.git / blobdiff