/*
- * Copyright (c) 2008, 2009, 2010 Nicira Networks.
+ * Copyright (c) 2008, 2009, 2010, 2011 Nicira Networks.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
#include "daemon.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 "process.h"
#include "socket-util.h"
#include "timeval.h"
#include "util.h"
-
-#define THIS_MODULE VLM_daemon
#include "vlog.h"
-/* Should we run in the background? */
+VLOG_DEFINE_THIS_MODULE(daemon);
+
+/* --detach: Should we run in the background? */
static bool detach;
-/* Name of pidfile (null if none). */
+/* --pidfile: Name of pidfile (null if none). */
static char *pidfile;
-/* Create pidfile even if one already exists and is locked? */
+/* 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;
-/* Should we chdir to "/"? */
+/* --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);
+
/* 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)
+make_pidfile_name(const char *name)
{
- return (!name ? xasprintf("%s/%s.pid", ovs_rundir, program_name)
- : *name == '/' ? xstrdup(name)
- : xasprintf("%s/%s", ovs_rundir, name));
+ return (!name
+ ? xasprintf("%s/%s.pid", ovs_rundir(), program_name)
+ : abs_file_name(ovs_rundir(), name));
}
/* Sets up a following call to daemonize() to create a pidfile named 'name'.
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)
{
return detach;
}
-/* 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. */
+/* 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
-die_if_already_running(void)
+daemon_set_monitor(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);
- }
- }
+ monitor = true;
}
-/* If a pidfile has been configured, creates it and stores the running process'
- * pid init. Ensures that the pidfile will be deleted when the process
- * exits. */
+/* 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. */
- }
- 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);
}
}
+static bool
+should_restart(int status)
+{
+ if (WIFSIGNALED(status)) {
+ static const int error_signals[] = {
+ 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. */
+ const char *saved_program_name;
+ time_t last_restart;
+ char *status_msg;
+ int crashes;
+
+ saved_program_name = program_name;
+ program_name = xasprintf("monitor(%s)", program_name);
+ status_msg = xstrdup("healthy");
+ last_restart = TIME_MIN;
+ crashes = 0;
+ for (;;) {
+ int retval;
+ int status;
+
+ proctitle_set("%s: monitoring pid %lu (%s)",
+ saved_program_name, (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)", 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",
+ 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;
+ }
+ sleep(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();
+ free((char *) program_name);
+ program_name = saved_program_name;
+}
+
/* Close stdin, stdout, stderr. If we're started from e.g. an SSH session,
* then this keeps us from holding that session open artificially. */
static void
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 parent process. */
exit(0);
}
+ /* Running in daemon or monitor process. */
+ }
+
+ 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. */
}
- 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. */
+ vlog_init();
}
/* 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;
}
}
" --pidfile[=FILE] create pidfile (default: %s/%s.pid)\n"
" --overwrite-pidfile with --pidfile, start even if already "
"running\n",
- ovs_rundir, program_name);
+ 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)
{
- char line[128];
+ 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;
- file = fopen(pidfile, "r");
+ 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, strerror(error));
goto error;
}
- lck.l_type = F_WRLCK;
- lck.l_whence = SEEK_SET;
- lck.l_start = 0;
- lck.l_len = 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