- ret = -1;
-
-end:
- return ret;
-}
-
-/*
- * spawn_sessiond
- *
- * Spawn a session daemon by forking and execv.
- */
-static int spawn_sessiond(char *pathname)
-{
- int ret = 0;
- pid_t pid;
-
- MSG("Spawning a session daemon");
- recv_child_signal = 0;
- pid = fork();
- if (pid == 0) {
- /*
- * Spawn session daemon and tell
- * it to signal us when ready.
- */
- execlp(pathname, "lttng-sessiond", "--sig-parent", "--quiet", NULL);
- /* execlp only returns if error happened */
- if (errno == ENOENT) {
- ERR("No session daemon found. Use --sessiond-path.");
- } else {
- perror("execlp");
- }
- kill(getppid(), SIGTERM); /* wake parent */
- exit(EXIT_FAILURE);
- } else if (pid > 0) {
- sessiond_pid = pid;
- /*
- * Wait for lttng-sessiond to start. We need to use a flag to check if
- * the signal has been sent to us, because the child can be scheduled
- * before the parent, and thus send the signal before this check. In
- * the signal handler, we set the recv_child_signal flag, so anytime we
- * check it after the fork is fine. 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 (!recv_child_signal) {
- sleep(1);
- }
- /*
- * The signal handler will nullify sessiond_pid on SIGCHLD
- */
- if (!sessiond_pid) {
- exit(EXIT_FAILURE);
- }
- goto end;
- } else {
- perror("fork");
- ret = -1;
- goto end;
- }
-
-end:
- return ret;
-}
-
-/*
- * check_sessiond
- *
- * Check if the session daemon is available using
- * the liblttngctl API for the check. If not, try to
- * spawn a daemon.
- */
-static int check_sessiond(void)
-{
- int ret;
- char *pathname = NULL, *alloc_pathname = NULL;
-
- ret = lttng_session_daemon_alive();
- if (ret == 0) { /* not alive */
- /* Try command line option path */
- if (opt_sessiond_path != NULL) {
- ret = access(opt_sessiond_path, F_OK | X_OK);
- if (ret < 0) {
- ERR("No such file or access denied: %s", opt_sessiond_path);
- goto end;
- }
- pathname = opt_sessiond_path;
- } else {
- /* Try LTTNG_SESSIOND_PATH env variable */
- pathname = getenv(DEFAULT_SESSIOND_PATH_ENV);
- }
-
- /* Let's rock and roll */
- if (pathname == NULL) {
- ret = asprintf(&alloc_pathname, INSTALL_BIN_PATH "/lttng-sessiond");
- if (ret < 0) {
- perror("asprintf spawn sessiond");
- goto end;
- }
- pathname = alloc_pathname;
- }
-
- ret = spawn_sessiond(pathname);
- free(alloc_pathname);
- if (ret < 0) {
- ERR("Problem occurred when starting %s", pathname);
- goto end;
- }
- }