/*
- * Copyright (c) 2008, 2009, 2010, 2011, 2012 Nicira, Inc.
+ * 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 <config.h>
#include "daemon.h"
-#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.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"
VLOG_DEFINE_THIS_MODULE(daemon);
/* --detach: Should we run in the background? */
-static bool detach;
+static bool detach; /* Was --detach specified? */
+static bool detached; /* Have we already detached? */
/* --pidfile: Name of pidfile (null if none). */
static char *pidfile;
void
set_pidfile(const char *name)
{
+ assert_single_threaded();
free(pidfile);
pidfile = make_pidfile_name(name);
}
void
daemon_save_fd(int fd)
{
- assert(fd == STDIN_FILENO || fd == STDOUT_FILENO || fd == STDERR_FILENO);
+ 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)
+{
+ if (pidfile) {
+ fatal_signal_remove_file_to_unlink(pidfile);
+ }
+}
+
+/* Registers pidfile to be unlinked when the program terminates via exit() or a
+ * fatal signal. */
+void
+add_pidfile_to_unlink(void)
+{
+ if (pidfile) {
+ fatal_signal_add_file_to_unlink(pidfile);
+ }
+}
+
/* 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. */
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 (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, strerror(errno));
+ 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, strerror(errno));
+ 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, strerror(errno));
+ VLOG_FATAL("%s: write failed (%s)", tmpfile, ovs_strerror(errno));
}
- error = lock_pidfile(file, F_SETLK);
- if (error) {
- VLOG_FATAL("%s: fcntl(F_SETLK) failed (%s)", tmpfile, strerror(error));
- }
+ error = rename(tmpfile, pidfile);
- /* 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();
- }
- } while (error == EINTR || error == EEXIST);
- if (error) {
- VLOG_FATAL("failed to link \"%s\" as \"%s\" (%s)",
- tmpfile, pidfile, strerror(error));
- }
+ /* 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);
- /* 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));
- }
- }
-
/* Clean up.
*
* We don't close 'file' because its file descriptor must remain open to
pidfile_dev = s.st_dev;
pidfile_ino = s.st_ino;
free(tmpfile);
- free(pidfile);
- pidfile = NULL;
}
/* 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
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_fully(fds[0], &c, 1, &bytes_read) != 0) {
int retval;
int status;
status_msg);
}
} else if (retval < 0) {
- VLOG_FATAL("waitpid failed (%s)", strerror(errno));
+ VLOG_FATAL("waitpid failed (%s)", ovs_strerror(errno));
} else {
NOT_REACHED();
}
} else if (!pid) {
/* Running in child process. */
close(fds[0]);
- time_postfork();
- lockfile_postfork();
*fdp = fds[1];
- } else {
- VLOG_FATAL("fork failed (%s)", strerror(errno));
}
return pid;
error = write_fully(fd, "", 1, &bytes_written);
if (error) {
- VLOG_FATAL("pipe write failed (%s)", strerror(error));
+ VLOG_FATAL("pipe write failed (%s)", ovs_strerror(error));
}
close(fd);
int retval;
int status;
- proctitle_set("%s: monitoring pid %lu (%s)",
- 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) {
- VLOG_FATAL("waitpid failed (%s)", strerror(errno));
+ VLOG_FATAL("waitpid failed (%s)", ovs_strerror(errno));
} else if (retval == daemon_pid) {
char *s = process_status_msg(status);
if (should_restart(status)) {
r.rlim_max = 0;
if (setrlimit(RLIMIT_CORE, &r) == -1) {
VLOG_WARN("failed to disable core dumps: %s",
- strerror(errno));
+ ovs_strerror(errno));
}
}
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) {
}
/* 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);
- daemonize_fd = -1;
+ 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("/"));
}
close_standard_fds();
- detach = false;
}
}
return 0;
}
error = errno;
- VLOG_WARN("%s: open: %s", pidfile, strerror(error));
+ 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, strerror(error));
+ VLOG_WARN("%s: fcntl: %s", pidfile, ovs_strerror(error));
goto error;
}
if (lck.l_type == F_UNLCK) {
if (unlink(pidfile)) {
error = errno;
VLOG_WARN("%s: failed to delete stale pidfile (%s)",
- pidfile, strerror(error));
+ pidfile, ovs_strerror(error));
goto error;
}
VLOG_DBG("%s: deleted stale pidfile", pidfile);
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);
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));
+ pidfile, ovs_strerror(-pid));
}
}
git://git.onelab.eu / sliver-openvswitch.git / blobdiff