+/*
+ * Add enum to the UST session registry. Once done, this replies to the
+ * application with the appropriate error code.
+ *
+ * The session UST registry lock is acquired within this function.
+ *
+ * On success 0 is returned else a negative value.
+ */
+static int add_enum_ust_registry(int sock, int sobjd, char *name,
+ struct ustctl_enum_entry *entries, size_t nr_entries)
+{
+ int ret = 0, ret_code;
+ struct ust_app *app;
+ struct ust_app_session *ua_sess;
+ struct ust_registry_session *registry;
+ uint64_t enum_id = -1ULL;
+
+ rcu_read_lock();
+
+ /* Lookup application. If not found, there is a code flow error. */
+ app = find_app_by_notify_sock(sock);
+ if (!app) {
+ /* Return an error since this is not an error */
+ DBG("Application socket %d is being torn down. Aborting enum registration",
+ sock);
+ free(entries);
+ goto error_rcu_unlock;
+ }
+
+ /* Lookup session by UST object descriptor. */
+ ua_sess = find_session_by_objd(app, sobjd);
+ if (!ua_sess) {
+ /* Return an error since this is not an error */
+ DBG("Application session is being torn down. Aborting enum registration.");
+ free(entries);
+ goto error_rcu_unlock;
+ }
+
+ registry = get_session_registry(ua_sess);
+ assert(registry);
+
+ pthread_mutex_lock(®istry->lock);
+
+ /*
+ * From this point on, the callee acquires the ownership of
+ * entries. The variable entries MUST NOT be read/written after
+ * call.
+ */
+ ret_code = ust_registry_create_or_find_enum(registry, sobjd, name,
+ entries, nr_entries, &enum_id);
+ entries = NULL;
+
+ /*
+ * The return value is returned to ustctl so in case of an error, the
+ * application can be notified. In case of an error, it's important not to
+ * return a negative error or else the application will get closed.
+ */
+ ret = ustctl_reply_register_enum(sock, enum_id, ret_code);
+ if (ret < 0) {
+ if (ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
+ ERR("UST app reply enum failed with ret %d", ret);
+ } else {
+ DBG3("UST app reply enum failed. Application died");
+ }
+ /*
+ * No need to wipe the create enum since the application socket will
+ * get close on error hence cleaning up everything by itself.
+ */
+ goto error;
+ }
+
+ DBG3("UST registry enum %s added successfully or already found", name);
+
+error:
+ pthread_mutex_unlock(®istry->lock);
+error_rcu_unlock:
+ rcu_read_unlock();
+ return ret;
+}
+