+ element->fd = tracer_event_source_fd;
+ element->domain = domain_type;
+
+ cds_list_add(&element->node, &state->tracer_event_sources_list);
+
+ DBG3("[notification-thread] Adding tracer event source fd to poll set: tracer_event_source_fd = %d, domain = '%s'",
+ tracer_event_source_fd,
+ lttng_domain_type_str(domain_type));
+
+ /* Adding the read side pipe to the event poll. */
+ ret = lttng_poll_add(&state->events, tracer_event_source_fd, LPOLLIN | LPOLLERR);
+ if (ret < 0) {
+ ERR("[notification-thread] Failed to add tracer event source to poll set: tracer_event_source_fd = %d, domain = '%s'",
+ tracer_event_source_fd,
+ lttng_domain_type_str(element->domain));
+ cds_list_del(&element->node);
+ free(element);
+ goto end;
+ }
+
+ element->is_fd_in_poll_set = true;
+
+end:
+ *_cmd_result = cmd_result;
+ return ret;
+}
+
+static
+int drain_event_notifier_notification_pipe(
+ struct notification_thread_state *state,
+ int pipe, enum lttng_domain_type domain)
+{
+ struct lttng_poll_event events = {0};
+ int ret;
+
+ ret = lttng_poll_create(&events, 1, LTTNG_CLOEXEC);
+ if (ret < 0) {
+ ERR("[notification-thread] Error creating lttng_poll_event");
+ goto end;
+ }
+
+ ret = lttng_poll_add(&events, pipe, LPOLLIN);
+ if (ret < 0) {
+ ERR("[notification-thread] Error adding fd event notifier notification pipe to lttng_poll_event: fd = %d",
+ pipe);
+ goto end;
+ }
+
+ while (true) {
+ /*
+ * Continue to consume notifications as long as there are new
+ * ones coming in. The tracer has been asked to stop producing
+ * them.
+ *
+ * LPOLLIN is explicitly checked since LPOLLHUP is implicitly
+ * monitored (on Linux, at least) and will be returned when
+ * the pipe is closed but empty.
+ */
+ ret = lttng_poll_wait_interruptible(&events, 0);
+ if (ret == 0 || (LTTNG_POLL_GETEV(&events, 0) & LPOLLIN) == 0) {
+ /* No more notification to be read on this pipe. */
+ ret = 0;
+ goto end;
+ } else if (ret < 0) {
+ PERROR("Failed on lttng_poll_wait_interruptible() call");
+ ret = -1;
+ goto end;
+ }
+
+ ret = handle_one_event_notifier_notification(state, pipe, domain);
+ if (ret) {
+ ERR("[notification-thread] Error consuming an event notifier notification from pipe: fd = %d",
+ pipe);
+ }
+ }
+end:
+ lttng_poll_clean(&events);
+ return ret;
+}
+
+static
+int handle_notification_thread_command_remove_tracer_event_source(
+ struct notification_thread_state *state,
+ int tracer_event_source_fd,
+ enum lttng_error_code *_cmd_result)
+{
+ int ret = 0;
+ bool found = false;
+ enum lttng_error_code cmd_result = LTTNG_OK;
+ struct notification_event_tracer_event_source_element *source_element = NULL, *tmp;
+
+ cds_list_for_each_entry_safe(source_element, tmp,
+ &state->tracer_event_sources_list, node) {
+ if (source_element->fd != tracer_event_source_fd) {
+ continue;
+ }
+
+ DBG("[notification-thread] Removed tracer event source from poll set: tracer_event_source_fd = %d, domain = '%s'",
+ tracer_event_source_fd,
+ lttng_domain_type_str(source_element->domain));
+ cds_list_del(&source_element->node);
+ found = true;
+ break;
+ }
+
+ if (!found) {
+ /*
+ * This is temporarily allowed since the poll activity set is
+ * not properly cleaned-up for the moment. This is adressed in
+ * an upcoming fix.
+ */
+ source_element = NULL;
+ goto end;
+ }
+
+ if (!source_element->is_fd_in_poll_set) {
+ /* Skip the poll set removal. */
+ goto end;
+ }
+
+ DBG3("[notification-thread] Removing tracer event source from poll set: tracer_event_source_fd = %d, domain = '%s'",
+ tracer_event_source_fd,
+ lttng_domain_type_str(source_element->domain));
+
+ /* Removing the fd from the event poll set. */
+ ret = lttng_poll_del(&state->events, tracer_event_source_fd);
+ if (ret < 0) {
+ ERR("[notification-thread] Failed to remove tracer event source from poll set: tracer_event_source_fd = %d, domain = '%s'",
+ tracer_event_source_fd,
+ lttng_domain_type_str(source_element->domain));
+ cmd_result = LTTNG_ERR_FATAL;
+ goto end;
+ }
+
+ source_element->is_fd_in_poll_set = false;
+
+ ret = drain_event_notifier_notification_pipe(state, tracer_event_source_fd,
+ source_element->domain);
+ if (ret) {
+ ERR("[notification-thread] Error draining event notifier notification: tracer_event_source_fd = %d, domain = %s",
+ tracer_event_source_fd,
+ lttng_domain_type_str(source_element->domain));
+ cmd_result = LTTNG_ERR_FATAL;
+ goto end;
+ }
+
+ /*
+ * The drain_event_notifier_notification_pipe() call might have read
+ * data from an fd that we received in event in the latest _poll_wait()
+ * call. Make sure the thread call poll_wait() again to ensure we have
+ * a clean state.
+ */
+ state->restart_poll = true;
+
+end:
+ free(source_element);
+ *_cmd_result = cmd_result;
+ return ret;
+}
+
+int handle_notification_thread_remove_tracer_event_source_no_result(
+ struct notification_thread_state *state,
+ int tracer_event_source_fd)
+{
+ int ret;
+ enum lttng_error_code cmd_result;
+
+ ret = handle_notification_thread_command_remove_tracer_event_source(
+ state, tracer_event_source_fd, &cmd_result);
+ (void) cmd_result;
+ return ret;
+}
+
+static int handle_notification_thread_command_list_triggers(
+ struct notification_thread_handle *handle,
+ struct notification_thread_state *state,
+ uid_t client_uid,
+ struct lttng_triggers **triggers,
+ enum lttng_error_code *_cmd_result)
+{
+ int ret = 0;
+ enum lttng_error_code cmd_result = LTTNG_OK;
+ struct cds_lfht_iter iter;
+ struct lttng_trigger_ht_element *trigger_ht_element;
+ struct lttng_triggers *local_triggers = NULL;
+ const struct lttng_credentials *creds;
+
+ rcu_read_lock();
+
+ local_triggers = lttng_triggers_create();
+ if (!local_triggers) {
+ /* Not a fatal error. */
+ cmd_result = LTTNG_ERR_NOMEM;
+ goto end;
+ }
+
+ cds_lfht_for_each_entry(state->triggers_ht, &iter,
+ trigger_ht_element, node) {
+ /*
+ * Only return the triggers to which the client has access.
+ * The root user has visibility over all triggers.
+ */
+ creds = lttng_trigger_get_credentials(trigger_ht_element->trigger);
+ if (client_uid != lttng_credentials_get_uid(creds) && client_uid != 0) {
+ continue;
+ }
+
+ ret = lttng_triggers_add(local_triggers,
+ trigger_ht_element->trigger);
+ if (ret < 0) {
+ /* Not a fatal error. */
+ ret = 0;
+ cmd_result = LTTNG_ERR_NOMEM;
+ goto end;
+ }
+ }
+
+ /* Transferring ownership to the caller. */
+ *triggers = local_triggers;
+ local_triggers = NULL;
+
+end:
+ rcu_read_unlock();
+ lttng_triggers_destroy(local_triggers);
+ *_cmd_result = cmd_result;
+ return ret;
+}
+
+static inline void get_trigger_info_for_log(const struct lttng_trigger *trigger,
+ const char **trigger_name,
+ uid_t *trigger_owner_uid)
+{
+ enum lttng_trigger_status trigger_status;
+
+ trigger_status = lttng_trigger_get_name(trigger, trigger_name);
+ switch (trigger_status) {
+ case LTTNG_TRIGGER_STATUS_OK:
+ break;
+ case LTTNG_TRIGGER_STATUS_UNSET:
+ *trigger_name = "(unset)";
+ break;
+ default:
+ abort();
+ }
+
+ trigger_status = lttng_trigger_get_owner_uid(trigger,
+ trigger_owner_uid);
+ assert(trigger_status == LTTNG_TRIGGER_STATUS_OK);
+}
+
+static int handle_notification_thread_command_get_trigger(
+ struct notification_thread_state *state,
+ const struct lttng_trigger *trigger,
+ struct lttng_trigger **registered_trigger,
+ enum lttng_error_code *_cmd_result)
+{
+ int ret = -1;
+ struct cds_lfht_iter iter;
+ struct lttng_trigger_ht_element *trigger_ht_element;
+ enum lttng_error_code cmd_result = LTTNG_ERR_TRIGGER_NOT_FOUND;
+ const char *trigger_name;
+ uid_t trigger_owner_uid;
+
+ rcu_read_lock();
+
+ cds_lfht_for_each_entry(
+ state->triggers_ht, &iter, trigger_ht_element, node) {
+ if (lttng_trigger_is_equal(
+ trigger, trigger_ht_element->trigger)) {
+ /* Take one reference on the return trigger. */
+ *registered_trigger = trigger_ht_element->trigger;
+ lttng_trigger_get(*registered_trigger);
+ ret = 0;
+ cmd_result = LTTNG_OK;
+ goto end;