/*
- * Copyright (c) 2008, 2009, 2010, 2011, 2012 Nicira Networks.
+ * Copyright (c) 2008, 2009, 2010, 2011, 2012 Nicira, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
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;
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;
+
+ pid = fork();
+ if (pid > 0) {
+ /* Running in parent process. */
+ fatal_signal_fork();
+ } else if (!pid) {
+ /* Running in child process. */
+ time_postfork();
+ lockfile_postfork();
+ } else {
+ VLOG_FATAL("fork failed (%s)", strerror(errno));
+ }
+
+ 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)
{
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;
} 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;
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);
+ subprogram_name = "monitor";
status_msg = xstrdup("healthy");
last_restart = TIME_MIN;
crashes = 0;
int status;
proctitle_set("%s: monitoring pid %lu (%s)",
- saved_program_name, (unsigned long int) daemon_pid,
+ program_name, (unsigned long int) daemon_pid,
status_msg);
do {
/* Running in new daemon process. */
proctitle_restore();
- free((char *) program_name);
- program_name = saved_program_name;
+ subprogram_name = "";
}
/* Close standard file descriptors (except any that the client has requested we
}
/* 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 (!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;
}
}