/*
- * Copyright (c) 2008, 2009, 2010 Nicira Networks.
+ * 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.
#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 "ovs-thread.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? */
-static bool detach;
+VLOG_DEFINE_THIS_MODULE(daemon);
+
+/* --detach: Should we run in the background? */
+static bool detach; /* Was --detach specified? */
+static bool detached; /* Have we already detached? */
-/* 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(). */
* it dies due to an error signal? */
static bool monitor;
+/* For each of the standard file descriptors, whether to replace it by
+ * /dev/null (if false) or keep it for the daemon to use (if true). */
+static bool save_fds[3];
+
+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'.
void
set_pidfile(const char *name)
{
+ assert_single_threaded();
free(pidfile);
pidfile = make_pidfile_name(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)
{
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)
+/* A daemon doesn't normally have any use for the file descriptors for stdin,
+ * stdout, and stderr after it detaches. To keep these file descriptors from
+ * e.g. holding an SSH session open, by default detaching replaces each of
+ * these file descriptors by /dev/null. But a few daemons expect the user to
+ * redirect stdout or stderr to a file, in which case it is desirable to keep
+ * these file descriptors. This function, therefore, disables replacing 'fd'
+ * by /dev/null when the daemon detaches. */
+void
+daemon_save_fd(int fd)
+{
+ ovs_assert(fd == STDIN_FILENO ||
+ fd == STDOUT_FILENO ||
+ fd == STDERR_FILENO);
+ save_fds[fd] = true;
+}
+
+/* Unregisters pidfile from being unlinked when the program terminates via
+* exit() or a fatal signal. */
+void
+remove_pidfile_from_unlink(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);
- }
+ fatal_signal_remove_file_to_unlink(pidfile);
}
- return pid;
}
-/* If a locked pidfile exists, issue a warning message and, unless
- * ignore_existing_pidfile() has been called, terminate the program. */
+/* Registers pidfile to be unlinked when the program terminates via exit() or a
+ * fatal signal. */
void
-die_if_already_running(void)
+add_pidfile_to_unlink(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 (pidfile) {
+ fatal_signal_add_file_to_unlink(pidfile);
}
}
-/* 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;
+ 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);
- 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);
- }
- } else {
- VLOG_ERR("%s: create failed: %s", tmpfile, strerror(errno));
- }
- fatal_signal_remove_file_to_unlink(tmpfile);
- free(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);
}
- free(pidfile);
- pidfile = NULL;
+
+ 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);
}
/* If configured with set_pidfile() or set_detach(), creates the pid file and
daemonize_complete();
}
+/* 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. */
+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. */
+ time_postfork();
+ 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;
- if (pipe(fds) < 0) {
- ovs_fatal(errno, "pipe failed");
- }
+ xpipe(fds);
- pid = fork();
+ pid = fork_and_clean_up();
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;
retval = waitpid(pid, &status, 0);
} while (retval == -1 && errno == EINTR);
- if (retval == pid
- && WIFEXITED(status)
- && WEXITSTATUS(status)) {
- /* Child exited with an error. Convey the same error to
- * our parent process as a courtesy. */
- exit(WEXITSTATUS(status));
+ 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 {
+ NOT_REACHED();
}
-
- ovs_fatal(errno, "fork child failed to signal startup");
}
close(fds[0]);
*fdp = -1;
} else if (!pid) {
/* Running in child process. */
close(fds[0]);
- time_postfork();
- lockfile_postfork();
*fdp = fds[1];
- } else {
- ovs_fatal(errno, "could not fork");
}
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)", ovs_strerror(error));
}
close(fd);
static void
monitor_daemon(pid_t daemon_pid)
{
- /* XXX Should limit the rate at which we restart the daemon. */
/* 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);
+ subprogram_name = "monitor";
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);
+ 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) {
- ovs_fatal(errno, "waitpid failed");
+ VLOG_FATAL("waitpid failed (%s)", ovs_strerror(errno));
} else if (retval == daemon_pid) {
char *s = process_status_msg(status);
- free(status_msg);
- status_msg = xasprintf("pid %lu died, %s",
- (unsigned long int) daemon_pid, s);
- free(s);
-
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;
+ }
+ 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("%s, exiting", status_msg);
+ VLOG_INFO("pid %lu died, %s, exiting",
+ (unsigned long int) daemon_pid, s);
+ free(s);
exit(0);
}
}
/* Running in new daemon process. */
proctitle_restore();
- free((char *) program_name);
- program_name = saved_program_name;
+ subprogram_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. */
+/* Close standard file descriptors (except any that the client has requested we
+ * leave open by calling daemon_save_fd()). If we're started from e.g. an SSH
+ * session, then this keeps us from holding that session open artificially. */
static void
close_standard_fds(void)
{
int null_fd = get_null_fd();
if (null_fd >= 0) {
- dup2(null_fd, STDIN_FILENO);
- dup2(null_fd, STDOUT_FILENO);
- dup2(null_fd, STDERR_FILENO);
+ int fd;
+
+ for (fd = 0; fd < 3; fd++) {
+ if (!save_fds[fd]) {
+ dup2(null_fd, fd);
+ }
+ }
}
+
+ /* 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
void
daemonize_start(void)
{
+ assert_single_threaded();
daemonize_fd = -1;
if (detach) {
/* Running in parent process. */
exit(0);
}
+
/* Running in daemon or monitor process. */
+ setsid();
}
if (monitor) {
/* 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. It also
+ * call daemonize_post_detach().
+ *
+ * Calling this function more than once has no additional effect. */
void
daemonize_complete(void)
{
- fork_notify_startup(daemonize_fd);
+ 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(). */
+void
+daemonize_post_detach(void)
+{
if (detach) {
- setsid();
if (chdir_) {
ignore(chdir("/"));
}
" --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));
+ VLOG_WARN("%s: open: %s", pidfile, ovs_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;
- VLOG_WARN("%s: fcntl: %s", pidfile, strerror(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) {
- 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, 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, strerror(error));
+ VLOG_WARN("%s: read: %s", pidfile, ovs_strerror(error));
} else {
error = ESRCH;
VLOG_WARN("%s: read: unexpected end of file", pidfile);
}
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, ovs_strerror(-pid));
+ }
+}
git://git.onelab.eu / sliver-openvswitch.git / blobdiff