mirror of
https://github.com/openvswitch/ovs
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b43c6fe279
This makes it possible to run tests that need access to installation directories, such as the rundir, without having access to the actual installation directories (/var/run is generally not world-writable), by setting environment variables. This is not a good way to do things in general--usually it would be better to choose the correct directories at configure time--so for now this is undocumented.
577 lines
16 KiB
C
577 lines
16 KiB
C
/*
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* Copyright (c) 2008, 2009, 2010 Nicira Networks.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <config.h>
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#include "daemon.h"
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#include <errno.h>
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#include <fcntl.h>
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#include <signal.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/resource.h>
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#include <sys/wait.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include "command-line.h"
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#include "fatal-signal.h"
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#include "dirs.h"
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#include "lockfile.h"
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#include "process.h"
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#include "socket-util.h"
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#include "timeval.h"
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#include "util.h"
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#include "vlog.h"
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VLOG_DEFINE_THIS_MODULE(daemon);
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/* --detach: Should we run in the background? */
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static bool detach;
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/* --pidfile: Name of pidfile (null if none). */
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static char *pidfile;
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/* Device and inode of pidfile, so we can avoid reopening it. */
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static dev_t pidfile_dev;
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static ino_t pidfile_ino;
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/* --overwrite-pidfile: Create pidfile even if one already exists and is
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locked? */
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static bool overwrite_pidfile;
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/* --no-chdir: Should we chdir to "/"? */
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static bool chdir_ = true;
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/* File descriptor used by daemonize_start() and daemonize_complete(). */
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static int daemonize_fd = -1;
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/* --monitor: Should a supervisory process monitor the daemon and restart it if
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* it dies due to an error signal? */
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static bool monitor;
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/* Returns the file name that would be used for a pidfile if 'name' were
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* provided to set_pidfile(). The caller must free the returned string. */
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char *
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make_pidfile_name(const char *name)
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{
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return (!name
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? xasprintf("%s/%s.pid", ovs_rundir(), program_name)
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: abs_file_name(ovs_rundir(), name));
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}
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/* Sets up a following call to daemonize() to create a pidfile named 'name'.
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* If 'name' begins with '/', then it is treated as an absolute path.
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* Otherwise, it is taken relative to RUNDIR, which is $(prefix)/var/run by
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* default.
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*
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* If 'name' is null, then program_name followed by ".pid" is used. */
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void
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set_pidfile(const char *name)
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{
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free(pidfile);
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pidfile = make_pidfile_name(name);
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}
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/* Returns an absolute path to the configured pidfile, or a null pointer if no
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* pidfile is configured. The caller must not modify or free the returned
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* string. */
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const char *
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get_pidfile(void)
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{
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return pidfile;
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}
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/* Sets that we do not chdir to "/". */
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void
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set_no_chdir(void)
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{
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chdir_ = false;
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}
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/* Will we chdir to "/" as part of daemonizing? */
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bool
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is_chdir_enabled(void)
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{
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return chdir_;
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}
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/* Normally, die_if_already_running() will terminate the program with a message
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* if a locked pidfile already exists. If this function is called,
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* die_if_already_running() will merely log a warning. */
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void
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ignore_existing_pidfile(void)
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{
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overwrite_pidfile = true;
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}
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/* Sets up a following call to daemonize() to detach from the foreground
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* session, running this process in the background. */
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void
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set_detach(void)
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{
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detach = true;
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}
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/* Will daemonize() really detach? */
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bool
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get_detach(void)
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{
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return detach;
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}
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/* Sets up a following call to daemonize() to fork a supervisory process to
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* monitor the daemon and restart it if it dies due to an error signal. */
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void
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daemon_set_monitor(void)
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{
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monitor = true;
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}
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/* If a pidfile has been configured and that pidfile already exists and is
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* locked by a running process, returns the pid of the running process.
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* Otherwise, returns 0. */
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static pid_t
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already_running(void)
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{
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pid_t pid = 0;
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if (pidfile) {
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int fd = open(pidfile, O_RDWR);
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if (fd >= 0) {
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struct flock lck;
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lck.l_type = F_WRLCK;
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lck.l_whence = SEEK_SET;
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lck.l_start = 0;
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lck.l_len = 0;
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if (fcntl(fd, F_GETLK, &lck) != -1 && lck.l_type != F_UNLCK) {
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pid = lck.l_pid;
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}
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close(fd);
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}
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}
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return pid;
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}
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/* If a locked pidfile exists, issue a warning message and, unless
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* ignore_existing_pidfile() has been called, terminate the program. */
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void
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die_if_already_running(void)
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{
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pid_t pid = already_running();
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if (pid) {
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if (!overwrite_pidfile) {
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ovs_fatal(0, "%s: already running as pid %ld",
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get_pidfile(), (long int) pid);
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} else {
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VLOG_WARN("%s: %s already running as pid %ld",
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get_pidfile(), program_name, (long int) pid);
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}
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}
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}
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/* If a pidfile has been configured, creates it and stores the running
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* process's pid in it. Ensures that the pidfile will be deleted when the
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* process exits. */
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static void
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make_pidfile(void)
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{
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if (pidfile) {
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/* Create pidfile via temporary file, so that observers never see an
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* empty pidfile or an unlocked pidfile. */
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long int pid = getpid();
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char *tmpfile;
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int fd;
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tmpfile = xasprintf("%s.tmp%ld", pidfile, pid);
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fatal_signal_add_file_to_unlink(tmpfile);
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fd = open(tmpfile, O_CREAT | O_WRONLY | O_TRUNC, 0666);
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if (fd >= 0) {
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struct flock lck;
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lck.l_type = F_WRLCK;
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lck.l_whence = SEEK_SET;
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lck.l_start = 0;
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lck.l_len = 0;
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if (fcntl(fd, F_SETLK, &lck) != -1) {
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char *text = xasprintf("%ld\n", pid);
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if (write(fd, text, strlen(text)) == strlen(text)) {
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fatal_signal_add_file_to_unlink(pidfile);
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if (rename(tmpfile, pidfile) < 0) {
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VLOG_ERR("failed to rename \"%s\" to \"%s\": %s",
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tmpfile, pidfile, strerror(errno));
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fatal_signal_remove_file_to_unlink(pidfile);
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close(fd);
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} else {
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/* Keep 'fd' open to retain the lock. */
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struct stat s;
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if (!fstat(fd, &s)) {
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pidfile_dev = s.st_dev;
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pidfile_ino = s.st_ino;
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} else {
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VLOG_ERR("%s: fstat failed: %s",
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pidfile, strerror(errno));
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}
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}
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free(text);
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} else {
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VLOG_ERR("%s: write failed: %s", tmpfile, strerror(errno));
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close(fd);
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}
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} else {
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VLOG_ERR("%s: fcntl failed: %s", tmpfile, strerror(errno));
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close(fd);
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}
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} else {
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VLOG_ERR("%s: create failed: %s", tmpfile, strerror(errno));
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}
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fatal_signal_remove_file_to_unlink(tmpfile);
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free(tmpfile);
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}
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free(pidfile);
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pidfile = NULL;
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}
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/* If configured with set_pidfile() or set_detach(), creates the pid file and
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* detaches from the foreground session. */
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void
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daemonize(void)
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{
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daemonize_start();
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daemonize_complete();
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}
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static pid_t
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fork_and_wait_for_startup(int *fdp)
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{
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int fds[2];
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pid_t pid;
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if (pipe(fds) < 0) {
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ovs_fatal(errno, "pipe failed");
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}
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pid = fork();
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if (pid > 0) {
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/* Running in parent process. */
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char c;
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close(fds[1]);
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fatal_signal_fork();
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if (read(fds[0], &c, 1) != 1) {
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int retval;
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int status;
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do {
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retval = waitpid(pid, &status, 0);
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} while (retval == -1 && errno == EINTR);
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if (retval == pid
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&& WIFEXITED(status)
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&& WEXITSTATUS(status)) {
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/* Child exited with an error. Convey the same error to
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* our parent process as a courtesy. */
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exit(WEXITSTATUS(status));
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}
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ovs_fatal(errno, "fork child failed to signal startup");
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}
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close(fds[0]);
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*fdp = -1;
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} else if (!pid) {
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/* Running in child process. */
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close(fds[0]);
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time_postfork();
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lockfile_postfork();
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*fdp = fds[1];
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} else {
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ovs_fatal(errno, "could not fork");
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}
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return pid;
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}
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static void
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fork_notify_startup(int fd)
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{
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if (fd != -1) {
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size_t bytes_written;
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int error;
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error = write_fully(fd, "", 1, &bytes_written);
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if (error) {
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ovs_fatal(error, "could not write to pipe");
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}
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close(fd);
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}
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}
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static bool
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should_restart(int status)
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{
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if (WIFSIGNALED(status)) {
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static const int error_signals[] = {
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SIGABRT, SIGALRM, SIGBUS, SIGFPE, SIGILL, SIGPIPE, SIGSEGV,
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SIGXCPU, SIGXFSZ
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};
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size_t i;
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for (i = 0; i < ARRAY_SIZE(error_signals); i++) {
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if (error_signals[i] == WTERMSIG(status)) {
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return true;
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}
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}
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}
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return false;
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}
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static void
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monitor_daemon(pid_t daemon_pid)
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{
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/* XXX Should log daemon's stderr output at startup time. */
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const char *saved_program_name;
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time_t last_restart;
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char *status_msg;
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int crashes;
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saved_program_name = program_name;
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program_name = xasprintf("monitor(%s)", program_name);
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status_msg = xstrdup("healthy");
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last_restart = TIME_MIN;
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crashes = 0;
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for (;;) {
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int retval;
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int status;
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proctitle_set("%s: monitoring pid %lu (%s)",
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saved_program_name, (unsigned long int) daemon_pid,
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status_msg);
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do {
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retval = waitpid(daemon_pid, &status, 0);
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} while (retval == -1 && errno == EINTR);
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if (retval == -1) {
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ovs_fatal(errno, "waitpid failed");
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} else if (retval == daemon_pid) {
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char *s = process_status_msg(status);
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if (should_restart(status)) {
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free(status_msg);
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status_msg = xasprintf("%d crashes: pid %lu died, %s",
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++crashes,
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(unsigned long int) daemon_pid, s);
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free(s);
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if (WCOREDUMP(status)) {
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/* Disable further core dumps to save disk space. */
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struct rlimit r;
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r.rlim_cur = 0;
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r.rlim_max = 0;
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if (setrlimit(RLIMIT_CORE, &r) == -1) {
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VLOG_WARN("failed to disable core dumps: %s",
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strerror(errno));
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}
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}
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/* Throttle restarts to no more than once every 10 seconds. */
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if (time(NULL) < last_restart + 10) {
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VLOG_WARN("%s, waiting until 10 seconds since last "
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"restart", status_msg);
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for (;;) {
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time_t now = time(NULL);
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time_t wakeup = last_restart + 10;
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if (now >= wakeup) {
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break;
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}
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sleep(wakeup - now);
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}
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}
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last_restart = time(NULL);
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VLOG_ERR("%s, restarting", status_msg);
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daemon_pid = fork_and_wait_for_startup(&daemonize_fd);
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if (!daemon_pid) {
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break;
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}
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} else {
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VLOG_INFO("pid %lu died, %s, exiting",
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(unsigned long int) daemon_pid, s);
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free(s);
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exit(0);
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}
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}
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}
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free(status_msg);
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/* Running in new daemon process. */
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proctitle_restore();
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free((char *) program_name);
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program_name = saved_program_name;
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}
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/* Close stdin, stdout, stderr. If we're started from e.g. an SSH session,
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* then this keeps us from holding that session open artificially. */
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static void
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close_standard_fds(void)
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{
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int null_fd = get_null_fd();
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if (null_fd >= 0) {
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dup2(null_fd, STDIN_FILENO);
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dup2(null_fd, STDOUT_FILENO);
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dup2(null_fd, STDERR_FILENO);
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}
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}
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/* If daemonization is configured, then starts daemonization, by forking and
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* returning in the child process. The parent process hangs around until the
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* child lets it know either that it completed startup successfully (by calling
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* daemon_complete()) or that it failed to start up (by exiting with a nonzero
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* exit code). */
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void
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daemonize_start(void)
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{
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daemonize_fd = -1;
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if (detach) {
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if (fork_and_wait_for_startup(&daemonize_fd) > 0) {
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/* Running in parent process. */
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exit(0);
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}
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/* Running in daemon or monitor process. */
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}
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if (monitor) {
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int saved_daemonize_fd = daemonize_fd;
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pid_t daemon_pid;
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daemon_pid = fork_and_wait_for_startup(&daemonize_fd);
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if (daemon_pid > 0) {
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/* Running in monitor process. */
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fork_notify_startup(saved_daemonize_fd);
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close_standard_fds();
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monitor_daemon(daemon_pid);
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}
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/* Running in daemon process. */
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}
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make_pidfile();
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/* Make sure that the unixctl commands for vlog get registered in a
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* daemon, even before the first log message. */
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vlog_init();
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}
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/* If daemonization is configured, then this function notifies the parent
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* process that the child process has completed startup successfully. */
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void
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daemonize_complete(void)
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{
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fork_notify_startup(daemonize_fd);
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if (detach) {
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setsid();
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if (chdir_) {
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ignore(chdir("/"));
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}
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close_standard_fds();
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}
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}
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void
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daemon_usage(void)
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{
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printf(
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"\nDaemon options:\n"
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" --detach run in background as daemon\n"
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" --no-chdir do not chdir to '/'\n"
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" --pidfile[=FILE] create pidfile (default: %s/%s.pid)\n"
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" --overwrite-pidfile with --pidfile, start even if already "
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"running\n",
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ovs_rundir(), program_name);
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}
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/* Opens and reads a PID from 'pidfile'. Returns the nonnegative PID if
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* successful, otherwise a negative errno value. */
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pid_t
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read_pidfile(const char *pidfile)
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{
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char line[128];
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struct flock lck;
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struct stat s;
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FILE *file;
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int error;
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if ((pidfile_ino || pidfile_dev)
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&& !stat(pidfile, &s)
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&& s.st_ino == pidfile_ino && s.st_dev == pidfile_dev) {
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/* It's our own pidfile. We can't afford to open it, because closing
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* *any* fd for a file that a process has locked also releases all the
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* locks on that file.
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*
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* Fortunately, we know the associated pid anyhow: */
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return getpid();
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}
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file = fopen(pidfile, "r");
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if (!file) {
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error = errno;
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VLOG_WARN("%s: open: %s", pidfile, strerror(error));
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goto error;
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}
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lck.l_type = F_WRLCK;
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lck.l_whence = SEEK_SET;
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lck.l_start = 0;
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lck.l_len = 0;
|
|
if (fcntl(fileno(file), F_GETLK, &lck)) {
|
|
error = errno;
|
|
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;
|
|
}
|
|
|
|
if (!fgets(line, sizeof line, file)) {
|
|
if (ferror(file)) {
|
|
error = errno;
|
|
VLOG_WARN("%s: read: %s", pidfile, strerror(error));
|
|
} else {
|
|
error = ESRCH;
|
|
VLOG_WARN("%s: read: unexpected end of file", pidfile);
|
|
}
|
|
goto error;
|
|
}
|
|
|
|
if (lck.l_pid != strtoul(line, NULL, 10)) {
|
|
error = ESRCH;
|
|
VLOG_WARN("l_pid (%ld) != %s pid (%s)",
|
|
(long int) lck.l_pid, pidfile, line);
|
|
goto error;
|
|
}
|
|
|
|
fclose(file);
|
|
return lck.l_pid;
|
|
|
|
error:
|
|
if (file) {
|
|
fclose(file);
|
|
}
|
|
return -error;
|
|
}
|