--- /dev/null
+/*
+ * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <config.h>
+#include "daemon.h"
+#include "daemon-private.h"
+#include <errno.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/resource.h>
+#include <sys/wait.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include "command-line.h"
+#include "fatal-signal.h"
+#include "dirs.h"
+#include "lockfile.h"
+#include "ovs-thread.h"
+#include "process.h"
+#include "socket-util.h"
+#include "timeval.h"
+#include "util.h"
+#include "vlog.h"
+
+VLOG_DEFINE_THIS_MODULE(daemon_unix);
+
+/* --detach: Should we run in the background? */
+bool detach; /* Was --detach specified? */
+static bool detached; /* Have we already detached? */
+
+/* --pidfile: Name of pidfile (null if none). */
+char *pidfile;
+
+/* Device and inode of pidfile, so we can avoid reopening it. */
+static dev_t pidfile_dev;
+static ino_t pidfile_ino;
+
+/* --overwrite-pidfile: Create pidfile even if one already exists and is
+ locked? */
+static bool overwrite_pidfile;
+
+/* --no-chdir: Should we chdir to "/"? */
+static bool chdir_ = true;
+
+/* File descriptor used by daemonize_start() and daemonize_complete(). */
+static int daemonize_fd = -1;
+
+/* --monitor: Should a supervisory process monitor the daemon and restart it if
+ * it dies due to an error signal? */
+static bool monitor;
+
+static void check_already_running(void);
+static int lock_pidfile(FILE *, int command);
+static pid_t fork_and_clean_up(void);
+static void daemonize_post_detach(void);
+
+/* 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 *
+make_pidfile_name(const char *name)
+{
+ return (!name
+ ? xasprintf("%s/%s.pid", ovs_rundir(), program_name)
+ : abs_file_name(ovs_rundir(), name));
+}
+
+/* Sets that we do not chdir to "/". */
+void
+set_no_chdir(void)
+{
+ chdir_ = false;
+}
+
+/* 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)
+{
+ overwrite_pidfile = true;
+}
+
+/* Sets up a following call to daemonize() to detach from the foreground
+ * session, running this process in the background. */
+void
+set_detach(void)
+{
+ detach = true;
+}
+
+/* Sets up a following call to daemonize() to fork a supervisory process to
+ * monitor the daemon and restart it if it dies due to an error signal. */
+void
+daemon_set_monitor(void)
+{
+ monitor = true;
+}
+
+/* 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)
+{
+ long int pid = getpid();
+ struct stat s;
+ char *tmpfile;
+ FILE *file;
+ int error;
+
+ /* Create a temporary pidfile. */
+ if (overwrite_pidfile) {
+ tmpfile = xasprintf("%s.tmp%ld", pidfile, pid);
+ fatal_signal_add_file_to_unlink(tmpfile);
+ } else {
+ /* Everyone shares the same file which will be treated as a lock. To
+ * avoid some uncomfortable race conditions, we can't set up the fatal
+ * signal unlink until we've acquired it. */
+ tmpfile = xasprintf("%s.tmp", pidfile);
+ }
+
+ file = fopen(tmpfile, "a+");
+ if (!file) {
+ VLOG_FATAL("%s: create failed (%s)", tmpfile, ovs_strerror(errno));
+ }
+
+ error = lock_pidfile(file, F_SETLK);
+ if (error) {
+ /* Looks like we failed to acquire the lock. Note that, if we failed
+ * for some other reason (and '!overwrite_pidfile'), we will have
+ * left 'tmpfile' as garbage in the file system. */
+ VLOG_FATAL("%s: fcntl(F_SETLK) failed (%s)", tmpfile,
+ ovs_strerror(error));
+ }
+
+ if (!overwrite_pidfile) {
+ /* We acquired the lock. Make sure to clean up on exit, and verify
+ * that we're allowed to create the actual pidfile. */
+ fatal_signal_add_file_to_unlink(tmpfile);
+ check_already_running();
+ }
+
+ if (fstat(fileno(file), &s) == -1) {
+ VLOG_FATAL("%s: fstat failed (%s)", tmpfile, ovs_strerror(errno));
+ }
+
+ if (ftruncate(fileno(file), 0) == -1) {
+ VLOG_FATAL("%s: truncate failed (%s)", tmpfile, ovs_strerror(errno));
+ }
+
+ fprintf(file, "%ld\n", pid);
+ if (fflush(file) == EOF) {
+ VLOG_FATAL("%s: write failed (%s)", tmpfile, ovs_strerror(errno));
+ }
+
+ error = rename(tmpfile, pidfile);
+
+ /* Due to a race, 'tmpfile' may be owned by a different process, so we
+ * shouldn't delete it on exit. */
+ fatal_signal_remove_file_to_unlink(tmpfile);
+
+ if (error < 0) {
+ VLOG_FATAL("failed to rename \"%s\" to \"%s\" (%s)",
+ tmpfile, pidfile, ovs_strerror(errno));
+ }
+
+ /* Ensure that the pidfile will get deleted on exit. */
+ fatal_signal_add_file_to_unlink(pidfile);
+
+ /* 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);
+}
+
+/* Calls fork() and on success returns its return value. On failure, logs an
+ * error and exits unsuccessfully.
+ *
+ * Post-fork, but before returning, this function calls a few other functions
+ * that are generally useful if the child isn't planning to exec a new
+ * process. */
+static pid_t
+fork_and_clean_up(void)
+{
+ pid_t pid = xfork();
+ if (pid > 0) {
+ /* Running in parent process. */
+ fatal_signal_fork();
+ } else if (!pid) {
+ /* Running in child process. */
+ lockfile_postfork();
+ }
+ return pid;
+}
+
+/* Forks, then:
+ *
+ * - In the parent, waits for the child to signal that it has completed its
+ * startup sequence. Then stores -1 in '*fdp' and returns the child's pid.
+ *
+ * - In the child, stores a fd in '*fdp' and returns 0. The caller should
+ * pass the fd to fork_notify_startup() after it finishes its startup
+ * sequence.
+ *
+ * If something goes wrong with the fork, logs a critical error and aborts the
+ * process. */
+static pid_t
+fork_and_wait_for_startup(int *fdp)
+{
+ int fds[2];
+ pid_t pid;
+
+ xpipe(fds);
+
+ pid = fork_and_clean_up();
+ if (pid > 0) {
+ /* Running in parent process. */
+ size_t bytes_read;
+ char c;
+
+ close(fds[1]);
+ if (read_fully(fds[0], &c, 1, &bytes_read) != 0) {
+ int retval;
+ int status;
+
+ do {
+ retval = waitpid(pid, &status, 0);
+ } while (retval == -1 && errno == EINTR);
+
+ if (retval == pid) {
+ if (WIFEXITED(status) && WEXITSTATUS(status)) {
+ /* Child exited with an error. Convey the same error
+ * to our parent process as a courtesy. */
+ exit(WEXITSTATUS(status));
+ } else {
+ char *status_msg = process_status_msg(status);
+ VLOG_FATAL("fork child died before signaling startup (%s)",
+ status_msg);
+ }
+ } else if (retval < 0) {
+ VLOG_FATAL("waitpid failed (%s)", ovs_strerror(errno));
+ } else {
+ OVS_NOT_REACHED();
+ }
+ }
+ close(fds[0]);
+ *fdp = -1;
+ } else if (!pid) {
+ /* Running in child process. */
+ close(fds[0]);
+ *fdp = fds[1];
+ }
+
+ return pid;
+}
+
+static void
+fork_notify_startup(int fd)
+{
+ if (fd != -1) {
+ size_t bytes_written;
+ int error;
+
+ error = write_fully(fd, "", 1, &bytes_written);
+ if (error) {
+ VLOG_FATAL("pipe write failed (%s)", ovs_strerror(error));
+ }
+
+ close(fd);
+ }
+}
+
+static bool
+should_restart(int status)
+{
+ if (WIFSIGNALED(status)) {
+ static const int error_signals[] = {
+ /* This list of signals is documented in daemon.man. If you
+ * change the list, update the documentation too. */
+ SIGABRT, SIGALRM, SIGBUS, SIGFPE, SIGILL, SIGPIPE, SIGSEGV,
+ SIGXCPU, SIGXFSZ
+ };
+
+ size_t i;
+
+ for (i = 0; i < ARRAY_SIZE(error_signals); i++) {
+ if (error_signals[i] == WTERMSIG(status)) {
+ return true;
+ }
+ }
+ }
+ return false;
+}
+
+static void
+monitor_daemon(pid_t daemon_pid)
+{
+ /* XXX Should log daemon's stderr output at startup time. */
+ time_t last_restart;
+ char *status_msg;
+ int crashes;
+
+ set_subprogram_name("monitor");
+ status_msg = xstrdup("healthy");
+ last_restart = TIME_MIN;
+ crashes = 0;
+ for (;;) {
+ int retval;
+ int status;
+
+ proctitle_set("monitoring pid %lu (%s)",
+ (unsigned long int) daemon_pid, status_msg);
+
+ do {
+ retval = waitpid(daemon_pid, &status, 0);
+ } while (retval == -1 && errno == EINTR);
+
+ if (retval == -1) {
+ VLOG_FATAL("waitpid failed (%s)", ovs_strerror(errno));
+ } else if (retval == daemon_pid) {
+ char *s = process_status_msg(status);
+ if (should_restart(status)) {
+ free(status_msg);
+ status_msg = xasprintf("%d crashes: pid %lu died, %s",
+ ++crashes,
+ (unsigned long int) daemon_pid, s);
+ free(s);
+
+ if (WCOREDUMP(status)) {
+ /* Disable further core dumps to save disk space. */
+ struct rlimit r;
+
+ r.rlim_cur = 0;
+ r.rlim_max = 0;
+ if (setrlimit(RLIMIT_CORE, &r) == -1) {
+ VLOG_WARN("failed to disable core dumps: %s",
+ ovs_strerror(errno));
+ }
+ }
+
+ /* Throttle restarts to no more than once every 10 seconds. */
+ if (time(NULL) < last_restart + 10) {
+ VLOG_WARN("%s, waiting until 10 seconds since last "
+ "restart", status_msg);
+ for (;;) {
+ time_t now = time(NULL);
+ time_t wakeup = last_restart + 10;
+ if (now >= wakeup) {
+ break;
+ }
+ xsleep(wakeup - now);
+ }
+ }
+ last_restart = time(NULL);
+
+ VLOG_ERR("%s, restarting", status_msg);
+ daemon_pid = fork_and_wait_for_startup(&daemonize_fd);
+ if (!daemon_pid) {
+ break;
+ }
+ } else {
+ VLOG_INFO("pid %lu died, %s, exiting",
+ (unsigned long int) daemon_pid, s);
+ free(s);
+ exit(0);
+ }
+ }
+ }
+ free(status_msg);
+
+ /* Running in new daemon process. */
+ proctitle_restore();
+ set_subprogram_name("");
+}
+
+/* If daemonization is configured, then starts daemonization, by forking and
+ * returning in the child process. The parent process hangs around until the
+ * child lets it know either that it completed startup successfully (by calling
+ * daemon_complete()) or that it failed to start up (by exiting with a nonzero
+ * exit code). */
+void
+daemonize_start(void)
+{
+ assert_single_threaded();
+ daemonize_fd = -1;
+
+ if (detach) {
+ if (fork_and_wait_for_startup(&daemonize_fd) > 0) {
+ /* Running in parent process. */
+ exit(0);
+ }
+
+ /* Running in daemon or monitor process. */
+ setsid();
+ }
+
+ if (monitor) {
+ int saved_daemonize_fd = daemonize_fd;
+ pid_t daemon_pid;
+
+ daemon_pid = fork_and_wait_for_startup(&daemonize_fd);
+ if (daemon_pid > 0) {
+ /* Running in monitor process. */
+ fork_notify_startup(saved_daemonize_fd);
+ close_standard_fds();
+ monitor_daemon(daemon_pid);
+ }
+ /* Running in daemon process. */
+ }
+
+ forbid_forking("running in daemon process");
+
+ if (pidfile) {
+ make_pidfile();
+ }
+
+ /* Make sure that the unixctl commands for vlog get registered in a
+ * daemon, even before the first log message. */
+ vlog_init();
+}
+
+/* If daemonization is configured, then this function notifies the parent
+ * process that the child process has completed startup successfully. It also
+ * call daemonize_post_detach().
+ *
+ * Calling this function more than once has no additional effect. */
+void
+daemonize_complete(void)
+{
+ if (pidfile) {
+ free(pidfile);
+ pidfile = NULL;
+ }
+
+ if (!detached) {
+ detached = true;
+
+ fork_notify_startup(daemonize_fd);
+ daemonize_fd = -1;
+ daemonize_post_detach();
+ }
+}
+
+/* If daemonization is configured, then this function does traditional Unix
+ * daemonization behavior: join a new session, chdir to the root (if not
+ * disabled), and close the standard file descriptors.
+ *
+ * It only makes sense to call this function as part of an implementation of a
+ * special daemon subprocess. A normal daemon should just call
+ * daemonize_complete(). */
+static void
+daemonize_post_detach(void)
+{
+ if (detach) {
+ if (chdir_) {
+ ignore(chdir("/"));
+ }
+ close_standard_fds();
+ }
+}
+
+void
+daemon_usage(void)
+{
+ printf(
+ "\nDaemon options:\n"
+ " --detach run in background as daemon\n"
+ " --no-chdir do not chdir to '/'\n"
+ " --pidfile[=FILE] create pidfile (default: %s/%s.pid)\n"
+ " --overwrite-pidfile with --pidfile, start even if already "
+ "running\n",
+ ovs_rundir(), program_name);
+}
+
+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)
+{
+ struct flock lck;
+
+ 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;
+
+ if ((pidfile_ino || pidfile_dev)
+ && !stat(pidfile, &s)
+ && s.st_ino == pidfile_ino && s.st_dev == pidfile_dev) {
+ /* It's our own pidfile. We can't afford to open it, because closing
+ * *any* fd for a file that a process has locked also releases all the
+ * locks on that file.
+ *
+ * Fortunately, we know the associated pid anyhow: */
+ return getpid();
+ }
+
+ file = fopen(pidfile, "r+");
+ if (!file) {
+ if (errno == ENOENT && delete_if_stale) {
+ return 0;
+ }
+ error = errno;
+ VLOG_WARN("%s: open: %s", pidfile, ovs_strerror(error));
+ goto error;
+ }
+
+ error = lock_pidfile__(file, F_GETLK, &lck);
+ if (error) {
+ VLOG_WARN("%s: fcntl: %s", pidfile, ovs_strerror(error));
+ goto error;
+ }
+ if (lck.l_type == F_UNLCK) {
+ /* 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, ovs_strerror(error));
+ goto error;
+ }
+ VLOG_DBG("%s: deleted stale pidfile", pidfile);
+ fclose(file);
+ return 0;
+ }
+
+ if (!fgets(line, sizeof line, file)) {
+ if (ferror(file)) {
+ error = errno;
+ VLOG_WARN("%s: read: %s", pidfile, ovs_strerror(error));
+ } else {
+ error = ESRCH;
+ VLOG_WARN("%s: read: unexpected end of file", pidfile);
+ }
+ goto error;
+ }
+
+ 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("%s: stale pidfile for pid %s being deleted by pid %ld",
+ pidfile, line, (long int) lck.l_pid);
+ goto error;
+ }
+
+ fclose(file);
+ return lck.l_pid;
+
+error:
+ if (file) {
+ fclose(file);
+ }
+ 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, ovs_strerror(-pid));
+ }
+}
+
+\f
+/* stub functions for non-windows platform. */
+
+void
+service_start(int *argc OVS_UNUSED, char **argv[] OVS_UNUSED)
+{
+}
+
+void
+service_stop(void)
+{
+}
+
+bool
+should_service_stop(void)
+{
+ return false;
+}
git://git.onelab.eu / sliver-openvswitch.git / blobdiff