+
+ ret = LTTNG_OK;
+
+error:
+ return ret;
+}
+
+/*
+ * Check if this event's filter requires the activation of application contexts
+ * and enable them in the agent.
+ * TODO: bytecode iterator does not support non-legacy application
+ * contexts yet. Not an issue for now, since they are not generated by
+ * the lttng-ctl library.
+ */
+static int add_filter_app_ctx(struct lttng_filter_bytecode *bytecode,
+ const char *filter_expression, struct agent *agt)
+{
+ int ret = LTTNG_OK;
+ char *provider_name = NULL, *ctx_name = NULL;
+ struct bytecode_symbol_iterator *it =
+ bytecode_symbol_iterator_create(bytecode);
+
+ if (!it) {
+ ret = LTTNG_ERR_NOMEM;
+ goto end;
+ }
+
+ do {
+ struct lttng_event_context ctx;
+ const char *symbol_name =
+ bytecode_symbol_iterator_get_name(it);
+
+ if (parse_application_context(symbol_name, &provider_name,
+ &ctx_name)) {
+ /* Not an application context. */
+ continue;
+ }
+
+ ctx.ctx = LTTNG_EVENT_CONTEXT_APP_CONTEXT;
+ ctx.u.app_ctx.provider_name = provider_name;
+ ctx.u.app_ctx.ctx_name = ctx_name;
+
+ /* Recognized an application context. */
+ DBG("Enabling event with filter expression \"%s\" requires enabling the %s:%s application context.",
+ filter_expression, provider_name, ctx_name);
+
+ ret = agent_add_context(&ctx, agt);
+ if (ret != LTTNG_OK) {
+ ERR("Failed to add application context %s:%s.",
+ provider_name, ctx_name);
+ goto end;
+ }
+
+ ret = agent_enable_context(&ctx, agt->domain);
+ if (ret != LTTNG_OK) {
+ ERR("Failed to enable application context %s:%s.",
+ provider_name, ctx_name);
+ goto end;
+ }
+
+ free(provider_name);
+ free(ctx_name);
+ provider_name = ctx_name = NULL;
+ } while (bytecode_symbol_iterator_next(it) == 0);
+end:
+ free(provider_name);
+ free(ctx_name);
+ bytecode_symbol_iterator_destroy(it);
+ return ret;
+}
+
+/*
+ * Enable a single agent event for a given UST session.
+ *
+ * Return LTTNG_OK on success or else a LTTNG_ERR* code.
+ */
+int event_agent_enable(struct ltt_ust_session *usess,
+ struct agent *agt, struct lttng_event *event,
+ struct lttng_filter_bytecode *filter,
+ char *filter_expression)
+{
+ int ret, created = 0;
+ struct agent_event *aevent;
+
+ assert(usess);
+ assert(event);
+ assert(agt);
+
+ DBG("Event agent enabling %s for session %" PRIu64 " with loglevel type %d "
+ ", loglevel %d and filter \"%s\"", event->name,
+ usess->id, event->loglevel_type, event->loglevel,
+ filter_expression ? filter_expression : "NULL");
+
+ aevent = agent_find_event(event->name, event->loglevel_type,
+ event->loglevel, filter_expression, agt);
+ if (!aevent) {
+ aevent = agent_create_event(event->name, event->loglevel_type,
+ event->loglevel, filter,
+ filter_expression);
+ if (!aevent) {
+ ret = LTTNG_ERR_NOMEM;
+ goto error;
+ }
+ filter = NULL;
+ filter_expression = NULL;
+ created = 1;
+ assert(!aevent->enabled);
+ }
+
+ if (created && aevent->filter) {
+ ret = add_filter_app_ctx(
+ aevent->filter, aevent->filter_expression, agt);
+ if (ret != LTTNG_OK) {
+ goto error;
+ }
+ }
+
+ /* Already enabled? */
+ if (aevent->enabled) {
+ ret = LTTNG_OK;
+ goto end;
+ }
+
+ ret = agent_enable_event(aevent, agt->domain);
+ if (ret != LTTNG_OK) {
+ goto error;
+ }
+
+ /* If the event was created prior to the enable, add it to the domain. */
+ if (created) {
+ agent_add_event(aevent, agt);
+ }
+
+ ret = LTTNG_OK;
+ goto end;
+
+error:
+ if (created) {
+ agent_destroy_event(aevent);
+ }
+end:
+ free(filter);
+ free(filter_expression);
+ return ret;
+}
+
+/*
+ * Return the default event name associated with the provided UST domain. Return
+ * NULL on error.
+ */
+const char *event_get_default_agent_ust_name(enum lttng_domain_type domain)
+{
+ const char *default_event_name = NULL;
+
+ switch (domain) {
+ case LTTNG_DOMAIN_LOG4J:
+ default_event_name = DEFAULT_LOG4J_EVENT_NAME;
+ break;
+ case LTTNG_DOMAIN_JUL:
+ default_event_name = DEFAULT_JUL_EVENT_NAME;
+ break;
+ case LTTNG_DOMAIN_PYTHON:
+ default_event_name = DEFAULT_PYTHON_EVENT_NAME;
+ break;
+ default:
+ assert(0);
+ }
+
+ return default_event_name;
+}
+
+/*
+ * Disable a given agent event for a given UST session.
+ *
+ * Must be called with the RCU read lock held.
+ * Return LTTNG_OK on success or else a LTTNG_ERR* code.
+ */
+static int event_agent_disable_one(struct ltt_ust_session *usess,
+ struct agent *agt, struct agent_event *aevent)
+{
+ int ret;
+ struct ltt_ust_event *uevent = NULL;
+ struct ltt_ust_channel *uchan = NULL;
+ const char *ust_event_name, *ust_channel_name;
+
+ assert(agt);
+ assert(usess);
+ assert(aevent);
+
+ DBG("Event agent disabling %s (loglevel type %d, loglevel value %d) for session %" PRIu64,
+ aevent->name, aevent->loglevel_type, aevent->loglevel_value,
+ usess->id);
+
+ /* Already disabled? */
+ if (!aevent->enabled) {
+ goto end;
+ }
+
+ if (agt->domain == LTTNG_DOMAIN_JUL) {
+ ust_channel_name = DEFAULT_JUL_CHANNEL_NAME;
+ } else if (agt->domain == LTTNG_DOMAIN_LOG4J) {
+ ust_channel_name = DEFAULT_LOG4J_CHANNEL_NAME;
+ } else if (agt->domain == LTTNG_DOMAIN_PYTHON) {
+ ust_channel_name = DEFAULT_PYTHON_CHANNEL_NAME;
+ } else {
+ ret = LTTNG_ERR_INVALID;
+ goto error;
+ }
+
+ /*
+ * Disable it on the UST side. First get the channel reference then find
+ * the event and finally disable it.
+ */
+ uchan = trace_ust_find_channel_by_name(usess->domain_global.channels,
+ (char *) ust_channel_name);
+ if (!uchan) {
+ ret = LTTNG_ERR_UST_CHAN_NOT_FOUND;
+ goto error;
+ }
+
+ ust_event_name = event_get_default_agent_ust_name(agt->domain);
+ if (!ust_event_name) {
+ ret = LTTNG_ERR_FATAL;
+ goto error;
+ }
+
+ /*
+ * Agent UST event has its loglevel type forced to
+ * LTTNG_UST_LOGLEVEL_ALL. The actual loglevel type/value filtering
+ * happens thanks to an UST filter. The following -1 is actually
+ * ignored since the type is LTTNG_UST_LOGLEVEL_ALL.
+ */
+ uevent = trace_ust_find_event(uchan->events, (char *) ust_event_name,
+ aevent->filter, LTTNG_UST_LOGLEVEL_ALL, -1, NULL);
+ /* If the agent event exists, it must be available on the UST side. */
+ assert(uevent);
+
+ if (usess->active) {
+ ret = ust_app_disable_event_glb(usess, uchan, uevent);
+ if (ret < 0 && ret != -LTTNG_UST_ERR_EXIST) {
+ ret = LTTNG_ERR_UST_DISABLE_FAIL;
+ goto error;
+ }
+ }
+
+ /*
+ * Flag event that it's disabled so the shadow copy on the ust app side
+ * will disable it if an application shows up.
+ */
+ uevent->enabled = 0;
+
+ ret = agent_disable_event(aevent, agt->domain);
+ if (ret != LTTNG_OK) {
+ goto error;
+ }
+
+end: