Fix: checking for existing session daemon is done after daemonizing

[lttng-tools.git] / src / bin / lttng-sessiond / main.c

diff --git a/src/bin/lttng-sessiond/main.c b/src/bin/lttng-sessiond/main.c
index 8e8b83b0f54a48d7d063f6cc668645ba804de7be..a4f9763ebf6c33b90bbe2cc0059490f0715eb418 100644 (file)
--- a/src/bin/lttng-sessiond/main.c
+++ b/src/bin/lttng-sessiond/main.c
@@ -631,21 +631,6 @@ static void sessiond_cleanup(void)
                free(load_info);
        }
 
-       /*
-        * Cleanup lock file by deleting it and finaly closing it which will
-        * release the file system lock.
-        */
-       if (lockfile_fd >= 0) {
-               ret = remove(config.lock_file_path.value);
-               if (ret < 0) {
-                       PERROR("remove lock file");
-               }
-               ret = close(lockfile_fd);
-               if (ret < 0) {
-                       PERROR("close lock file");
-               }
-       }
-
        /*
         * We do NOT rmdir rundir because there are other processes
         * using it, for instance lttng-relayd, which can start in
@@ -5332,18 +5317,57 @@ end:
        return ret;
 }
 
+/*
+ * Create lockfile using the rundir and return its fd.
+ */
+static int create_lockfile(void)
+{
+        return utils_create_lock_file(config.lock_file_path.value);
+}
+
 /*
  * Check if the global socket is available, and if a daemon is answering at the
  * other side. If yes, error is returned.
+ *
+ * Also attempts to create and hold the lock file.
  */
 static int check_existing_daemon(void)
 {
+       int ret = 0;
+
        /* Is there anybody out there ? */
        if (lttng_session_daemon_alive()) {
-               return -EEXIST;
+               ret = -EEXIST;
+               goto end;
        }
 
-       return 0;
+       lockfile_fd = create_lockfile();
+       if (lockfile_fd < 0) {
+               ret = -EEXIST;
+               goto end;
+       }
+end:
+       return ret;
+}
+
+static void sessiond_cleanup_lock_file(void)
+{
+       int ret;
+
+       /*
+        * Cleanup lock file by deleting it and finaly closing it which will
+        * release the file system lock.
+        */
+       if (lockfile_fd >= 0) {
+               ret = remove(config.lock_file_path.value);
+               if (ret < 0) {
+                       PERROR("remove lock file");
+               }
+               ret = close(lockfile_fd);
+               if (ret < 0) {
+                       PERROR("close lock file");
+               }
+       }
 }
 
 /*
@@ -5602,14 +5626,6 @@ static int write_pidfile(void)
         return utils_create_pid_file(getpid(), config.pid_file_path.value);
 }
 
-/*
- * Create lockfile using the rundir and return its fd.
- */
-static int create_lockfile(void)
-{
-        return utils_create_lock_file(config.lock_file_path.value);
-}
-
 /*
  * Write agent TCP port using the rundir.
  */
@@ -5786,6 +5802,18 @@ int main(int argc, char **argv)
 
        sessiond_config_log(&config);
 
+       if (create_lttng_rundir()) {
+               retval = -1;
+               goto exit_options;
+       }
+
+       /* Abort launch if a session daemon is already running. */
+       if (check_existing_daemon()) {
+               ERR("A session daemon is already running.");
+               retval = -1;
+               goto exit_options;
+       }
+
        /* Daemonize */
        if (config.daemonize || config.background) {
                int i;
@@ -5800,9 +5828,12 @@ int main(int argc, char **argv)
                /*
                 * We are in the child. Make sure all other file descriptors are
                 * closed, in case we are called with more opened file
-                * descriptors than the standard ones.
+                * descriptors than the standard ones and the lock file.
                 */
                for (i = 3; i < sysconf(_SC_OPEN_MAX); i++) {
+                       if (i == lockfile_fd) {
+                               continue;
+                       }
                        (void) close(i);
                }
        }
@@ -5841,12 +5872,6 @@ int main(int argc, char **argv)
 
        /* Check if daemon is UID = 0 */
        is_root = !getuid();
-
-       if (create_lttng_rundir()) {
-               retval = -1;
-               goto exit_init_data;
-       }
-
        if (is_root) {
                /* Create global run dir with root access */
 
@@ -5878,12 +5903,6 @@ int main(int argc, char **argv)
                }
        }
 
-       lockfile_fd = create_lockfile();
-       if (lockfile_fd < 0) {
-               retval = -1;
-               goto exit_init_data;
-       }
-
        /* Set consumer initial state */
        kernel_consumerd_state = CONSUMER_STOPPED;
        ust_consumerd_state = CONSUMER_STOPPED;
@@ -5950,19 +5969,6 @@ int main(int argc, char **argv)
                goto exit_init_data;
        }
 
-       /*
-        * See if daemon already exist.
-        */
-       if (check_existing_daemon()) {
-               ERR("Already running daemon.\n");
-               /*
-                * We do not goto exit because we must not cleanup()
-                * because a daemon is already running.
-                */
-               retval = -1;
-               goto exit_init_data;
-       }
-
        /*
         * Init UST app hash table. Alloc hash table before this point since
         * cleanup() can get called after that point.
@@ -6455,6 +6461,7 @@ exit_health_sessiond_cleanup:
 exit_create_run_as_worker_cleanup:
 
 exit_options:
+       sessiond_cleanup_lock_file();
        sessiond_cleanup_options();
 
 exit_set_signal_handler: