/*
- * Copyright (c) 2008, 2009 Nicira Networks.
+ * Copyright (c) 2008, 2009, 2010 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 <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? */
-static bool force;
+/* --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;
/* 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 pidfile;
}
+/* Sets that we do not chdir to "/". */
+void
+set_no_chdir(void)
+{
+ chdir_ = false;
+}
+
+/* Will we chdir to "/" as part of daemonizing? */
+bool
+is_chdir_enabled(void)
+{
+ 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. */
void
ignore_existing_pidfile(void)
{
- force = true;
+ overwrite_pidfile = true;
}
/* Sets up a following call to daemonize() to detach from the foreground
detach = true;
}
+/* Will daemonize() really detach? */
+bool
+get_detach(void)
+{
+ return detach;
+}
+
+/* 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 and that pidfile already exists and is
* locked by a running process, returns the pid of the running process.
* Otherwise, returns 0. */
{
pid_t pid = already_running();
if (pid) {
- if (!force) {
+ if (!overwrite_pidfile) {
ovs_fatal(0, "%s: already running as pid %ld",
get_pidfile(), (long int) pid);
} else {
}
}
-/* 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)
{
void
daemonize(void)
{
- if (detach) {
- char c = 0;
- int fds[2];
- if (pipe(fds) < 0) {
- ovs_fatal(errno, "pipe failed");
+ daemonize_start();
+ daemonize_complete();
+}
+
+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");
+ }
+
+ pid = fork();
+ if (pid > 0) {
+ /* Running in parent process. */
+ char c;
+
+ close(fds[1]);
+ fatal_signal_fork();
+ if (read(fds[0], &c, 1) != 1) {
+ int retval;
+ int status;
+
+ do {
+ 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));
+ }
+
+ 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;
+}
+
+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) {
+ ovs_fatal(error, "could not write to pipe");
}
- switch (fork()) {
- default:
- /* Parent process: wait for child to create pidfile, then exit. */
- close(fds[1]);
- fatal_signal_fork();
- if (read(fds[0], &c, 1) != 1) {
- ovs_fatal(errno, "daemon child failed to signal startup");
+ 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;
+
+ saved_program_name = program_name;
+ program_name = xasprintf("monitor(%s)", program_name);
+ status_msg = xstrdup("healthy");
+ last_restart = TIME_MIN;
+ 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) {
+ ovs_fatal(errno, "waitpid failed");
+ } 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)) {
+ 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("%s, exiting", status_msg);
+ 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
+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);
+ }
+}
+
+/* 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)
+{
+ 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. */
+ }
- case 0:
- /* Child process. */
- close(fds[0]);
- make_pidfile();
- write(fds[1], &c, 1);
- close(fds[1]);
- setsid();
- chdir("/");
- break;
-
- case -1:
- /* Error. */
- ovs_fatal(errno, "could not fork");
- break;
+ 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);
}
- } else {
- make_pidfile();
+ /* Running in daemon process. */
+ }
+
+ 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. */
+void
+daemonize_complete(void)
+{
+ fork_notify_startup(daemonize_fd);
+
+ if (detach) {
+ setsid();
+ if (chdir_) {
+ ignore(chdir("/"));
+ }
+ close_standard_fds();
}
}
{
printf(
"\nDaemon options:\n"
- " -D, --detach run in background as daemon\n"
- " -P, --pidfile[=FILE] create pidfile (default: %s/%s.pid)\n"
- " -f, --force with -P, start even if already running\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);
}
git://git.onelab.eu / sliver-openvswitch.git / blobdiff