+static
+int handle_notification_thread_command_add_tracer_event_source(
+ struct notification_thread_state *state,
+ int tracer_event_source_fd,
+ enum lttng_domain_type domain_type,
+ enum lttng_error_code *_cmd_result)
+{
+ int ret = 0;
+ enum lttng_error_code cmd_result = LTTNG_OK;
+ struct notification_event_tracer_event_source_element *element = NULL;
+
+ element = zmalloc(sizeof(*element));
+ if (!element) {
+ cmd_result = LTTNG_ERR_NOMEM;
+ ret = -1;
+ goto end;
+ }
+
+ element->fd = tracer_event_source_fd;
+ element->domain = domain_type;
+
+ cds_list_add(&element->node, &state->tracer_event_sources_list);
+
+ DBG3("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("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("Error creating lttng_poll_event");
+ goto end;
+ }
+
+ ret = lttng_poll_add(&events, pipe, LPOLLIN);
+ if (ret < 0) {
+ ERR("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("Error consuming an event notifier notification from pipe: fd = %d",
+ pipe);
+ }
+ }
+end:
+ lttng_poll_clean(&events);
+ return ret;
+}
+
+static
+struct notification_event_tracer_event_source_element *
+find_tracer_event_source_element(struct notification_thread_state *state,
+ int tracer_event_source_fd)
+{
+ struct notification_event_tracer_event_source_element *source_element;
+
+ cds_list_for_each_entry(source_element,
+ &state->tracer_event_sources_list, node) {
+ if (source_element->fd == tracer_event_source_fd) {
+ goto end;
+ }
+ }
+
+ source_element = NULL;
+end:
+ return source_element;
+}
+
+static
+int remove_tracer_event_source_from_pollset(
+ struct notification_thread_state *state,
+ struct notification_event_tracer_event_source_element *source_element)
+{
+ int ret = 0;
+
+ assert(source_element->is_fd_in_poll_set);
+
+ DBG3("Removing tracer event source from poll set: tracer_event_source_fd = %d, domain = '%s'",
+ source_element->fd,
+ lttng_domain_type_str(source_element->domain));
+
+ /* Removing the fd from the event poll set. */
+ ret = lttng_poll_del(&state->events, source_element->fd);
+ if (ret < 0) {
+ ERR("Failed to remove tracer event source from poll set: tracer_event_source_fd = %d, domain = '%s'",
+ source_element->fd,
+ lttng_domain_type_str(source_element->domain));
+ ret = -1;
+ goto end;
+ }
+
+ source_element->is_fd_in_poll_set = false;
+
+ ret = drain_event_notifier_notification_pipe(state, source_element->fd,
+ source_element->domain);
+ if (ret) {
+ ERR("Error draining event notifier notification: tracer_event_source_fd = %d, domain = %s",
+ source_element->fd,
+ lttng_domain_type_str(source_element->domain));
+ ret = -1;
+ goto end;
+ }
+
+end:
+ return ret;
+}
+
+int handle_notification_thread_tracer_event_source_died(
+ struct notification_thread_state *state,
+ int tracer_event_source_fd)
+{
+ int ret = 0;
+ struct notification_event_tracer_event_source_element *source_element;
+
+ source_element = find_tracer_event_source_element(state,
+ tracer_event_source_fd);
+
+ assert(source_element);
+
+ ret = remove_tracer_event_source_from_pollset(state, source_element);
+ if (ret) {
+ ERR("Failed to remove dead tracer event source from poll set");
+ }
+
+ 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;
+ enum lttng_error_code cmd_result = LTTNG_OK;
+ struct notification_event_tracer_event_source_element *source_element = NULL;
+
+ source_element = find_tracer_event_source_element(state,
+ tracer_event_source_fd);
+
+ assert(source_element);
+
+ /* Remove the tracer source from the list. */
+ cds_list_del(&source_element->node);
+
+ if (!source_element->is_fd_in_poll_set) {
+ /* Skip the poll set removal. */
+ goto end;
+ }
+
+ ret = remove_tracer_event_source_from_pollset(state, source_element);
+ if (ret) {
+ ERR("Failed to remove tracer event source from poll set");
+ cmd_result = LTTNG_ERR_FATAL;
+ }
+
+end:
+ free(source_element);
+ *_cmd_result = 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 = "(anonymous)";
+ 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;
+ }
+ }
+
+ /* Not a fatal error if the trigger is not found. */
+ get_trigger_info_for_log(trigger, &trigger_name, &trigger_owner_uid);
+ DBG("Failed to retrieve registered version of trigger: trigger name = '%s', trigger owner uid = %d",
+ trigger_name, (int) trigger_owner_uid);
+
+ ret = 0;
+
+end:
+ rcu_read_unlock();
+ *_cmd_result = cmd_result;
+ return ret;
+}
+
+static
+bool condition_is_supported(struct lttng_condition *condition)
+{
+ bool is_supported;
+
+ switch (lttng_condition_get_type(condition)) {
+ case LTTNG_CONDITION_TYPE_BUFFER_USAGE_LOW:
+ case LTTNG_CONDITION_TYPE_BUFFER_USAGE_HIGH:
+ {
+ int ret;
+ enum lttng_domain_type domain;
+
+ ret = lttng_condition_buffer_usage_get_domain_type(condition,
+ &domain);
+ assert(ret == 0);
+
+ if (domain != LTTNG_DOMAIN_KERNEL) {
+ is_supported = true;
+ goto end;
+ }
+
+ /*
+ * Older kernel tracers don't expose the API to monitor their
+ * buffers. Therefore, we reject triggers that require that
+ * mechanism to be available to be evaluated.
+ *
+ * Assume unsupported on error.
+ */
+ is_supported = kernel_supports_ring_buffer_snapshot_sample_positions() == 1;
+ break;
+ }
+ case LTTNG_CONDITION_TYPE_EVENT_RULE_MATCHES:
+ {
+ const struct lttng_event_rule *event_rule;
+ enum lttng_domain_type domain;
+ const enum lttng_condition_status status =
+ lttng_condition_event_rule_matches_get_rule(
+ condition, &event_rule);
+
+ assert(status == LTTNG_CONDITION_STATUS_OK);
+
+ domain = lttng_event_rule_get_domain_type(event_rule);
+ if (domain != LTTNG_DOMAIN_KERNEL) {
+ is_supported = true;
+ goto end;
+ }
+
+ /*
+ * Older kernel tracers can't emit notification. Therefore, we
+ * reject triggers that require that mechanism to be available
+ * to be evaluated.
+ *
+ * Assume unsupported on error.
+ */
+ is_supported = kernel_supports_event_notifiers() == 1;
+ break;
+ }
+ default:
+ is_supported = true;
+ }
+end:
+ return is_supported;
+}
+
+/* Must be called with RCU read lock held. */
+static
+int bind_trigger_to_matching_session(struct lttng_trigger *trigger,
+ struct notification_thread_state *state)
+{
+ int ret = 0;
+ const struct lttng_condition *condition;
+ const char *session_name;
+ struct lttng_session_trigger_list *trigger_list;
+
+ condition = lttng_trigger_get_const_condition(trigger);
+ switch (lttng_condition_get_type(condition)) {
+ case LTTNG_CONDITION_TYPE_SESSION_ROTATION_ONGOING:
+ case LTTNG_CONDITION_TYPE_SESSION_ROTATION_COMPLETED:
+ {
+ enum lttng_condition_status status;
+
+ status = lttng_condition_session_rotation_get_session_name(
+ condition, &session_name);
+ if (status != LTTNG_CONDITION_STATUS_OK) {
+ ERR("Failed to bind trigger to session: unable to get 'session_rotation' condition's session name");
+ ret = -1;
+ goto end;
+ }
+ break;
+ }
+ default:
+ ret = -1;
+ goto end;
+ }
+
+ trigger_list = get_session_trigger_list(state, session_name);
+ if (!trigger_list) {
+ DBG("Unable to bind trigger applying to session \"%s\" as it is not yet known to the notification system",
+ session_name);
+ goto end;
+
+ }
+
+ DBG("Newly registered trigger bound to session \"%s\"",
+ session_name);
+ ret = lttng_session_trigger_list_add(trigger_list, trigger);
+end:
+ return ret;
+}
+
+/* Must be called with RCU read lock held. */
+static
+int bind_trigger_to_matching_channels(struct lttng_trigger *trigger,
+ struct notification_thread_state *state)
+{
+ int ret = 0;
+ struct cds_lfht_node *node;
+ struct cds_lfht_iter iter;
+ struct channel_info *channel;
+
+ cds_lfht_for_each_entry(state->channels_ht, &iter, channel,
+ channels_ht_node) {
+ struct lttng_trigger_list_element *trigger_list_element;
+ struct lttng_channel_trigger_list *trigger_list;
+ struct cds_lfht_iter lookup_iter;
+
+ if (!trigger_applies_to_channel(trigger, channel)) {
+ continue;
+ }
+
+ cds_lfht_lookup(state->channel_triggers_ht,
+ hash_channel_key(&channel->key),
+ match_channel_trigger_list,
+ &channel->key,
+ &lookup_iter);
+ node = cds_lfht_iter_get_node(&lookup_iter);
+ assert(node);
+ trigger_list = caa_container_of(node,
+ struct lttng_channel_trigger_list,
+ channel_triggers_ht_node);
+
+ trigger_list_element = zmalloc(sizeof(*trigger_list_element));
+ if (!trigger_list_element) {
+ ret = -1;
+ goto end;
+ }
+ CDS_INIT_LIST_HEAD(&trigger_list_element->node);
+ trigger_list_element->trigger = trigger;
+ cds_list_add(&trigger_list_element->node, &trigger_list->list);
+ DBG("Newly registered trigger bound to channel \"%s\"",
+ channel->name);
+ }
+end:
+ return ret;
+}
+
+static
+bool is_trigger_action_notify(const struct lttng_trigger *trigger)
+{
+ bool is_notify = false;
+ unsigned int i, count;
+ enum lttng_action_status action_status;
+ const struct lttng_action *action =
+ lttng_trigger_get_const_action(trigger);
+ enum lttng_action_type action_type;
+
+ assert(action);
+ action_type = lttng_action_get_type(action);
+ if (action_type == LTTNG_ACTION_TYPE_NOTIFY) {
+ is_notify = true;
+ goto end;
+ } else if (action_type != LTTNG_ACTION_TYPE_LIST) {
+ goto end;
+ }
+
+ action_status = lttng_action_list_get_count(action, &count);
+ assert(action_status == LTTNG_ACTION_STATUS_OK);
+
+ for (i = 0; i < count; i++) {
+ const struct lttng_action *inner_action =
+ lttng_action_list_get_at_index(
+ action, i);
+
+ action_type = lttng_action_get_type(inner_action);
+ if (action_type == LTTNG_ACTION_TYPE_NOTIFY) {
+ is_notify = true;
+ goto end;
+ }
+ }
+
+end:
+ return is_notify;
+}
+
+static bool trigger_name_taken(struct notification_thread_state *state,
+ const struct lttng_trigger *trigger)
+{
+ struct cds_lfht_iter iter;
+
+ /*
+ * No duplicata is allowed in the triggers_by_name_uid_ht.
+ * The match is done against the trigger name and uid.
+ */
+ cds_lfht_lookup(state->triggers_by_name_uid_ht,
+ hash_trigger_by_name_uid(trigger),
+ match_trigger_by_name_uid,
+ trigger,
+ &iter);
+ return !!cds_lfht_iter_get_node(&iter);
+}
+
+static
+enum lttng_error_code generate_trigger_name(
+ struct notification_thread_state *state,
+ struct lttng_trigger *trigger, const char **name)
+{
+ enum lttng_error_code ret_code = LTTNG_OK;
+ bool taken = false;
+ enum lttng_trigger_status status;
+
+ do {
+ const int ret = lttng_trigger_generate_name(trigger,
+ state->trigger_id.name_offset++);
+ if (ret) {
+ /* The only reason this can fail right now. */
+ ret_code = LTTNG_ERR_NOMEM;
+ break;
+ }
+
+ status = lttng_trigger_get_name(trigger, name);
+ assert(status == LTTNG_TRIGGER_STATUS_OK);
+
+ taken = trigger_name_taken(state, trigger);
+ } while (taken || state->trigger_id.name_offset == UINT64_MAX);
+
+ return ret_code;
+}
+
+static inline
+void notif_thread_state_remove_trigger_ht_elem(
+ struct notification_thread_state *state,
+ struct lttng_trigger_ht_element *trigger_ht_element)
+{
+ assert(state);
+ assert(trigger_ht_element);
+
+ cds_lfht_del(state->triggers_ht, &trigger_ht_element->node);
+ cds_lfht_del(state->triggers_by_name_uid_ht, &trigger_ht_element->node_by_name_uid);
+}
+
+static
+enum lttng_error_code setup_tracer_notifier(
+ struct notification_thread_state *state,
+ struct lttng_trigger *trigger)
+{
+ enum lttng_error_code ret;
+ enum event_notifier_error_accounting_status error_accounting_status;
+ struct cds_lfht_node *node;
+ uint64_t error_counter_index = 0;
+ struct lttng_condition *condition = lttng_trigger_get_condition(trigger);
+ struct notification_trigger_tokens_ht_element *trigger_tokens_ht_element = NULL;
+
+ trigger_tokens_ht_element = zmalloc(sizeof(*trigger_tokens_ht_element));
+ if (!trigger_tokens_ht_element) {
+ ret = LTTNG_ERR_NOMEM;
+ goto end;
+ }
+
+ /* Add trigger token to the trigger_tokens_ht. */
+ cds_lfht_node_init(&trigger_tokens_ht_element->node);
+ trigger_tokens_ht_element->token = LTTNG_OPTIONAL_GET(trigger->tracer_token);
+ trigger_tokens_ht_element->trigger = trigger;
+
+ node = cds_lfht_add_unique(state->trigger_tokens_ht,
+ hash_key_u64(&trigger_tokens_ht_element->token, lttng_ht_seed),
+ match_trigger_token,
+ &trigger_tokens_ht_element->token,
+ &trigger_tokens_ht_element->node);
+ if (node != &trigger_tokens_ht_element->node) {
+ ret = LTTNG_ERR_TRIGGER_EXISTS;
+ goto error_free_ht_element;
+ }
+
+ error_accounting_status = event_notifier_error_accounting_register_event_notifier(
+ trigger, &error_counter_index);
+ if (error_accounting_status != EVENT_NOTIFIER_ERROR_ACCOUNTING_STATUS_OK) {
+ if (error_accounting_status == EVENT_NOTIFIER_ERROR_ACCOUNTING_STATUS_NO_INDEX_AVAILABLE) {
+ DBG("Trigger list error accounting counter full.");
+ ret = LTTNG_ERR_EVENT_NOTIFIER_ERROR_ACCOUNTING_FULL;
+ } else {
+ ERR("Error registering trigger for error accounting");
+ ret = LTTNG_ERR_EVENT_NOTIFIER_REGISTRATION;
+ }
+
+ goto error_remove_ht_element;
+ }
+
+ lttng_condition_event_rule_matches_set_error_counter_index(
+ condition, error_counter_index);
+
+ ret = LTTNG_OK;
+ goto end;
+
+error_remove_ht_element:
+ cds_lfht_del(state->trigger_tokens_ht, &trigger_tokens_ht_element->node);
+error_free_ht_element:
+ free(trigger_tokens_ht_element);
+end:
+ return ret;
+}
+
+/*
+ * FIXME A client's credentials are not checked when registering a trigger.
+ *
+ * The effects of this are benign since:
+ * - The client will succeed in registering the trigger, as it is valid,
+ * - The trigger will, internally, be bound to the channel/session,