+/*
+ * Write JUL TCP port using the rundir.
+ */
+static void write_julport(void)
+{
+ int ret;
+ char path[PATH_MAX];
+
+ assert(rundir);
+
+ ret = snprintf(path, sizeof(path), "%s/"
+ DEFAULT_LTTNG_SESSIOND_JULPORT_FILE, rundir);
+ if (ret < 0) {
+ PERROR("snprintf julport path");
+ goto error;
+ }
+
+ /*
+ * Create TCP JUL port file in rundir. Return value is of no importance.
+ * The execution will continue even though we are not able to write the
+ * file.
+ */
+ (void) utils_create_pid_file(jul_tcp_port, path);
+
+error:
+ return;
+}
+
+/*
+ * Daemonize this process by forking and making the parent wait for the child
+ * to signal it indicating readiness. Once received, the parent successfully
+ * quits.
+ *
+ * The child process undergoes the same action that daemon(3) does meaning
+ * setsid, chdir, and dup /dev/null into 0, 1 and 2.
+ *
+ * Return 0 on success else -1 on error.
+ */
+static int daemonize(void)
+{
+ int ret;
+ pid_t pid;
+
+ /* Get parent pid of this process. */
+ child_ppid = getppid();
+
+ pid = fork();
+ if (pid < 0) {
+ PERROR("fork");
+ goto error;
+ } else if (pid == 0) {
+ int fd;
+ pid_t sid;
+
+ /* Child */
+
+ /*
+ * Get the newly created parent pid so we can signal that process when
+ * we are ready to operate.
+ */
+ child_ppid = getppid();
+
+ sid = setsid();
+ if (sid < 0) {
+ PERROR("setsid");
+ goto error;
+ }
+
+ /* Try to change directory to /. If we can't well at least notify. */
+ ret = chdir("/");
+ if (ret < 0) {
+ PERROR("chdir");
+ }
+
+ fd = open(_PATH_DEVNULL, O_RDWR, 0);
+ if (fd < 0) {
+ PERROR("open %s", _PATH_DEVNULL);
+ /* Let 0, 1 and 2 open since we can't bind them to /dev/null. */
+ } else {
+ (void) dup2(fd, STDIN_FILENO);
+ (void) dup2(fd, STDOUT_FILENO);
+ (void) dup2(fd, STDERR_FILENO);
+ if (fd > 2) {
+ ret = close(fd);
+ if (ret < 0) {
+ PERROR("close");
+ }
+ }
+ }
+ goto end;
+ } else {
+ /* Parent */
+
+ /*
+ * Waiting for child to notify this parent that it can exit. Note that
+ * sleep() is interrupted before the 1 second delay as soon as the
+ * signal is received, so it will not cause visible delay for the
+ * user.
+ */
+ while (!CMM_LOAD_SHARED(recv_child_signal)) {
+ int status;
+ pid_t ret;
+
+ /*
+ * Check if child exists without blocking. If so, we have to stop
+ * this parent process and return an error.
+ */
+ ret = waitpid(pid, &status, WNOHANG);
+ if (ret < 0 || (ret != 0 && WIFEXITED(status))) {
+ /* The child exited somehow or was not valid. */
+ goto error;
+ }
+ sleep(1);
+ }
+
+ /*
+ * From this point on, the parent can exit and the child is now an
+ * operationnal session daemon ready to serve clients and applications.
+ */
+ exit(EXIT_SUCCESS);
+ }
+
+end:
+ return 0;
+
+error:
+ return -1;
+}
+