X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=src%2Fbin%2Flttng-sessiond%2Fcmd.c;h=ceafa00e2c8f7a13eddc968e53ac9839d8027c14;hb=42f626e843c5b67edeef6499adc146def3239aeb;hp=6709926572c00203dbe34242d6ff3367c9b6d077;hpb=8782cc7477fae212607b9fd6395a4b2e2d3357ed;p=lttng-tools.git

diff --git a/src/bin/lttng-sessiond/cmd.c b/src/bin/lttng-sessiond/cmd.c
index 670992657..ceafa00e2 100644
--- a/src/bin/lttng-sessiond/cmd.c
+++ b/src/bin/lttng-sessiond/cmd.c
@@ -17,6 +17,7 @@
 
 #define _GNU_SOURCE
 #include <assert.h>
+#include <string.h>
 #include <inttypes.h>
 #include <urcu/list.h>
 #include <urcu/uatomic.h>
@@ -166,6 +167,8 @@ static void list_lttng_channels(int domain, struct ltt_session *session,
 			channels[i].attr.read_timer_interval =
 				uchan->attr.read_timer_interval;
 			channels[i].enabled = uchan->enabled;
+			channels[i].attr.tracefile_size = uchan->tracefile_size;
+			channels[i].attr.tracefile_count = uchan->tracefile_count;
 			switch (uchan->attr.output) {
 			case LTTNG_UST_MMAP:
 			default:
@@ -182,6 +185,57 @@ static void list_lttng_channels(int domain, struct ltt_session *session,
 	}
 }
 
+/*
+ * Create a list of JUL domain events.
+ *
+ * Return number of events in list on success or else a negative value.
+ */
+static int list_lttng_jul_events(struct jul_domain *dom,
+		struct lttng_event **events)
+{
+	int i = 0, ret = 0;
+	unsigned int nb_event = 0;
+	struct jul_event *event;
+	struct lttng_event *tmp_events;
+	struct lttng_ht_iter iter;
+
+	assert(dom);
+	assert(events);
+
+	DBG3("Listing JUL events");
+
+	nb_event = lttng_ht_get_count(dom->events);
+	if (nb_event == 0) {
+		ret = nb_event;
+		goto error;
+	}
+
+	tmp_events = zmalloc(nb_event * sizeof(*tmp_events));
+	if (!tmp_events) {
+		PERROR("zmalloc JUL events session");
+		ret = -LTTNG_ERR_FATAL;
+		goto error;
+	}
+
+	rcu_read_lock();
+	cds_lfht_for_each_entry(dom->events->ht, &iter.iter, event, node.node) {
+		strncpy(tmp_events[i].name, event->name, sizeof(tmp_events[i].name));
+		tmp_events[i].name[sizeof(tmp_events[i].name) - 1] = '\0';
+		tmp_events[i].enabled = event->enabled;
+		tmp_events[i].loglevel = event->loglevel;
+		tmp_events[i].loglevel_type = event->loglevel_type;
+		i++;
+	}
+	rcu_read_unlock();
+
+	*events = tmp_events;
+	ret = nb_event;
+
+error:
+	assert(nb_event == i);
+	return ret;
+}
+
 /*
  * Create a list of ust global domain events.
  */
@@ -256,6 +310,9 @@ static int list_lttng_ust_global_events(char *channel_name,
 		if (uevent->filter) {
 			tmp[i].filter = 1;
 		}
+		if (uevent->exclusion) {
+			tmp[i].exclusion = 1;
+		}
 		i++;
 	}
 
@@ -406,6 +463,7 @@ static int add_uri_to_consumer(struct consumer_output *consumer,
 			 * URI was the same in the consumer so we do not append the subdir
 			 * again so to not duplicate output dir.
 			 */
+			ret = LTTNG_OK;
 			goto error;
 		}
 
@@ -770,7 +828,7 @@ static int start_kernel_session(struct ltt_kernel_session *ksess, int wpipe)
 	/* Quiescent wait after starting trace */
 	kernel_wait_quiescent(kernel_tracer_fd);
 
-	ksess->started = 1;
+	ksess->active = 1;
 
 	ret = LTTNG_OK;
 
@@ -850,11 +908,21 @@ int cmd_enable_channel(struct ltt_session *session,
 	int ret;
 	struct ltt_ust_session *usess = session->ust_session;
 	struct lttng_ht *chan_ht;
+	size_t len;
 
 	assert(session);
 	assert(attr);
 	assert(domain);
 
+	len = strnlen(attr->name, sizeof(attr->name));
+
+	/* Validate channel name */
+	if (attr->name[0] == '.' ||
+		memchr(attr->name, '/', len) != NULL) {
+		ret = LTTNG_ERR_INVALID_CHANNEL_NAME;
+		goto end;
+	}
+
 	DBG("Enabling channel %s for session %s", attr->name, session->name);
 
 	rcu_read_lock();
@@ -863,7 +931,7 @@ int cmd_enable_channel(struct ltt_session *session,
 	 * Don't try to enable a channel if the session has been started at
 	 * some point in time before. The tracer does not allow it.
 	 */
-	if (session->started) {
+	if (session->has_been_started) {
 		ret = LTTNG_ERR_TRACE_ALREADY_STARTED;
 		goto error;
 	}
@@ -878,6 +946,16 @@ int cmd_enable_channel(struct ltt_session *session,
 		attr->attr.switch_timer_interval = 0;
 	}
 
+	/*
+	 * The ringbuffer (both in user space and kernel) behave badly in overwrite
+	 * mode and with less than 2 subbuf so block it right away and send back an
+	 * invalid attribute error.
+	 */
+	if (attr->attr.overwrite && attr->attr.num_subbuf < 2) {
+		ret = LTTNG_ERR_INVALID;
+		goto error;
+	}
+
 	switch (domain->type) {
 	case LTTNG_DOMAIN_KERNEL:
 	{
@@ -886,15 +964,6 @@ int cmd_enable_channel(struct ltt_session *session,
 		kchan = trace_kernel_get_channel_by_name(attr->name,
 				session->kernel_session);
 		if (kchan == NULL) {
-			/*
-			 * Don't try to create a channel if the session
-			 * has been started at some point in time
-			 * before. The tracer does not allow it.
-			 */
-			if (session->started) {
-				ret = LTTNG_ERR_TRACE_ALREADY_STARTED;
-				goto error;
-			}
 			ret = channel_kernel_create(session->kernel_session, attr, wpipe);
 			if (attr->name[0] != '\0') {
 				session->kernel_session->has_non_default_channel = 1;
@@ -918,15 +987,6 @@ int cmd_enable_channel(struct ltt_session *session,
 
 		uchan = trace_ust_find_channel_by_name(chan_ht, attr->name);
 		if (uchan == NULL) {
-			/*
-			 * Don't try to create a channel if the session
-			 * has been started at some point in time
-			 * before. The tracer does not allow it.
-			 */
-			if (session->started) {
-				ret = LTTNG_ERR_TRACE_ALREADY_STARTED;
-				goto error;
-			}
 			ret = channel_ust_create(usess, attr, domain->buf_type);
 			if (attr->name[0] != '\0') {
 				usess->has_non_default_channel = 1;
@@ -943,6 +1003,7 @@ int cmd_enable_channel(struct ltt_session *session,
 
 error:
 	rcu_read_unlock();
+end:
 	return ret;
 }
 
@@ -1022,6 +1083,19 @@ int cmd_disable_event(struct ltt_session *session, int domain,
 				channel_name);
 		break;
 	}
+	case LTTNG_DOMAIN_JUL:
+	{
+		struct ltt_ust_session *usess = session->ust_session;
+
+		assert(usess);
+
+		ret = event_jul_disable(usess, event_name);
+		if (ret != LTTNG_OK) {
+			goto error;
+		}
+
+		break;
+	}
 #if 0
 	case LTTNG_DOMAIN_UST_EXEC_NAME:
 	case LTTNG_DOMAIN_UST_PID:
@@ -1112,6 +1186,19 @@ int cmd_disable_event_all(struct ltt_session *session, int domain,
 
 		DBG3("Disable all UST events in channel %s completed", channel_name);
 
+		break;
+	}
+	case LTTNG_DOMAIN_JUL:
+	{
+		struct ltt_ust_session *usess = session->ust_session;
+
+		assert(usess);
+
+		ret = event_jul_disable_all(usess);
+		if (ret != LTTNG_OK) {
+			goto error;
+		}
+
 		break;
 	}
 #if 0
@@ -1228,10 +1315,14 @@ error:
 
 /*
  * Command LTTNG_ENABLE_EVENT processed by the client thread.
+ * We own filter, exclusion, and filter_expression.
  */
 int cmd_enable_event(struct ltt_session *session, struct lttng_domain *domain,
 		char *channel_name, struct lttng_event *event,
-		struct lttng_filter_bytecode *filter, int wpipe)
+		char *filter_expression,
+		struct lttng_filter_bytecode *filter,
+		struct lttng_event_exclusion *exclusion,
+		int wpipe)
 {
 	int ret, channel_created = 0;
 	struct lttng_channel *attr;
@@ -1344,10 +1435,66 @@ int cmd_enable_event(struct ltt_session *session, struct lttng_domain *domain,
 		}
 
 		/* At this point, the session and channel exist on the tracer */
-		ret = event_ust_enable_tracepoint(usess, uchan, event, filter);
+		ret = event_ust_enable_tracepoint(usess, uchan, event,
+				filter_expression, filter, exclusion);
+		/* We have passed ownership */
+		filter_expression = NULL;
+		filter = NULL;
+		exclusion = NULL;
+		if (ret != LTTNG_OK) {
+			goto error;
+		}
+		break;
+	}
+	case LTTNG_DOMAIN_JUL:
+	{
+		struct lttng_event uevent;
+		struct lttng_domain tmp_dom;
+		struct ltt_ust_session *usess = session->ust_session;
+
+		assert(usess);
+
+		/* Create the default JUL tracepoint. */
+		memset(&uevent, 0, sizeof(uevent));
+		uevent.type = LTTNG_EVENT_TRACEPOINT;
+		uevent.loglevel_type = LTTNG_EVENT_LOGLEVEL_ALL;
+		if (is_root) {
+			strncpy(uevent.name, DEFAULT_SYS_JUL_EVENT_NAME,
+					sizeof(uevent.name));
+		} else {
+			strncpy(uevent.name, DEFAULT_USER_JUL_EVENT_NAME,
+					sizeof(uevent.name));
+		}
+		uevent.name[sizeof(uevent.name) - 1] = '\0';
+
+		/*
+		 * The domain type is changed because we are about to enable the
+		 * default channel and event for the JUL domain that are hardcoded.
+		 * This happens in the UST domain.
+		 */
+		memcpy(&tmp_dom, domain, sizeof(tmp_dom));
+		tmp_dom.type = LTTNG_DOMAIN_UST;
+
+		ret = cmd_enable_event(session, &tmp_dom, DEFAULT_JUL_CHANNEL_NAME,
+			&uevent, filter_expression, filter, NULL, wpipe);
+		/* We have passed ownership */
+		filter_expression = NULL;
+		if (ret != LTTNG_OK && ret != LTTNG_ERR_UST_EVENT_ENABLED) {
+			goto error;
+		}
+
+		/* The wild card * means that everything should be enabled. */
+		if (strncmp(event->name, "*", 1) == 0 && strlen(event->name) == 1) {
+			ret = event_jul_enable_all(usess, event, filter);
+			filter = NULL;
+		} else {
+			ret = event_jul_enable(usess, event, filter);
+			filter = NULL;
+		}
 		if (ret != LTTNG_OK) {
 			goto error;
 		}
+
 		break;
 	}
 #if 0
@@ -1363,6 +1510,9 @@ int cmd_enable_event(struct ltt_session *session, struct lttng_domain *domain,
 	ret = LTTNG_OK;
 
 error:
+	free(filter_expression);
+	free(filter);
+	free(exclusion);
 	rcu_read_unlock();
 	return ret;
 }
@@ -1372,6 +1522,7 @@ error:
  */
 int cmd_enable_event_all(struct ltt_session *session,
 		struct lttng_domain *domain, char *channel_name, int event_type,
+		char *filter_expression,
 		struct lttng_filter_bytecode *filter, int wpipe)
 {
 	int ret;
@@ -1505,7 +1656,8 @@ int cmd_enable_event_all(struct ltt_session *session,
 		switch (event_type) {
 		case LTTNG_EVENT_ALL:
 		case LTTNG_EVENT_TRACEPOINT:
-			ret = event_ust_enable_all_tracepoints(usess, uchan, filter);
+			ret = event_ust_enable_all_tracepoints(usess, uchan,
+				filter_expression, filter);
 			if (ret != LTTNG_OK) {
 				goto error;
 			}
@@ -1520,6 +1672,52 @@ int cmd_enable_event_all(struct ltt_session *session,
 			goto error;
 		}
 
+		break;
+	}
+	case LTTNG_DOMAIN_JUL:
+	{
+		struct lttng_event uevent, event;
+		struct lttng_domain tmp_dom;
+		struct ltt_ust_session *usess = session->ust_session;
+
+		assert(usess);
+
+		/* Create the default JUL tracepoint. */
+		uevent.type = LTTNG_EVENT_TRACEPOINT;
+		uevent.loglevel_type = LTTNG_EVENT_LOGLEVEL_ALL;
+		if (is_root) {
+			strncpy(uevent.name, DEFAULT_SYS_JUL_EVENT_NAME,
+					sizeof(uevent.name));
+		} else {
+			strncpy(uevent.name, DEFAULT_USER_JUL_EVENT_NAME,
+					sizeof(uevent.name));
+		}
+		uevent.name[sizeof(uevent.name) - 1] = '\0';
+
+		/*
+		 * The domain type is changed because we are about to enable the
+		 * default channel and event for the JUL domain that are hardcoded.
+		 * This happens in the UST domain.
+		 */
+		memcpy(&tmp_dom, domain, sizeof(tmp_dom));
+		tmp_dom.type = LTTNG_DOMAIN_UST;
+
+		ret = cmd_enable_event(session, &tmp_dom, DEFAULT_JUL_CHANNEL_NAME,
+			&uevent, NULL, NULL, NULL, wpipe);
+		if (ret != LTTNG_OK && ret != LTTNG_ERR_UST_EVENT_ENABLED) {
+			goto error;
+		}
+
+		event.loglevel = LTTNG_LOGLEVEL_JUL_ALL;
+		event.loglevel_type = LTTNG_EVENT_LOGLEVEL_ALL;
+		strncpy(event.name, "*", sizeof(event.name));
+		event.name[sizeof(event.name) - 1] = '\0';
+
+		ret = event_jul_enable_all(usess, &event, filter);
+		if (ret != LTTNG_OK) {
+			goto error;
+		}
+
 		break;
 	}
 #if 0
@@ -1563,6 +1761,13 @@ ssize_t cmd_list_tracepoints(int domain, struct lttng_event **events)
 			goto error;
 		}
 		break;
+	case LTTNG_DOMAIN_JUL:
+		nb_events = jul_list_events(events);
+		if (nb_events < 0) {
+			ret = LTTNG_ERR_UST_LIST_FAIL;
+			goto error;
+		}
+		break;
 	default:
 		ret = LTTNG_ERR_UND;
 		goto error;
@@ -1611,6 +1816,7 @@ error:
 int cmd_start_trace(struct ltt_session *session)
 {
 	int ret;
+	unsigned long nb_chan = 0;
 	struct ltt_kernel_session *ksession;
 	struct ltt_ust_session *usess;
 
@@ -1620,13 +1826,28 @@ int cmd_start_trace(struct ltt_session *session)
 	ksession = session->kernel_session;
 	usess = session->ust_session;
 
-	if (session->enabled) {
-		/* Already started. */
+	/* Is the session already started? */
+	if (session->active) {
 		ret = LTTNG_ERR_TRACE_ALREADY_STARTED;
 		goto error;
 	}
 
-	session->enabled = 1;
+	/*
+	 * Starting a session without channel is useless since after that it's not
+	 * possible to enable channel thus inform the client.
+	 */
+	if (usess && usess->domain_global.channels) {
+		rcu_read_lock();
+		nb_chan += lttng_ht_get_count(usess->domain_global.channels);
+		rcu_read_unlock();
+	}
+	if (ksession) {
+		nb_chan += ksession->channel_count;
+	}
+	if (!nb_chan) {
+		ret = LTTNG_ERR_NO_CHANNEL;
+		goto error;
+	}
 
 	/* Kernel tracing */
 	if (ksession != NULL) {
@@ -1638,7 +1859,11 @@ int cmd_start_trace(struct ltt_session *session)
 
 	/* Flag session that trace should start automatically */
 	if (usess) {
-		usess->start_trace = 1;
+		/*
+		 * Even though the start trace might fail, flag this session active so
+		 * other application coming in are started by default.
+		 */
+		usess->active = 1;
 
 		ret = ust_app_start_trace_all(usess);
 		if (ret < 0) {
@@ -1647,7 +1872,9 @@ int cmd_start_trace(struct ltt_session *session)
 		}
 	}
 
-	session->started = 1;
+	/* Flag this after a successful start. */
+	session->has_been_started = 1;
+	session->active = 1;
 
 	ret = LTTNG_OK;
 
@@ -1671,15 +1898,14 @@ int cmd_stop_trace(struct ltt_session *session)
 	ksession = session->kernel_session;
 	usess = session->ust_session;
 
-	if (!session->enabled) {
+	/* Session is not active. Skip everythong and inform the client. */
+	if (!session->active) {
 		ret = LTTNG_ERR_TRACE_ALREADY_STOPPED;
 		goto error;
 	}
 
-	session->enabled = 0;
-
 	/* Kernel tracer */
-	if (ksession && ksession->started) {
+	if (ksession && ksession->active) {
 		DBG("Stop kernel tracing");
 
 		/* Flush metadata if exist */
@@ -1706,11 +1932,15 @@ int cmd_stop_trace(struct ltt_session *session)
 
 		kernel_wait_quiescent(kernel_tracer_fd);
 
-		ksession->started = 0;
+		ksession->active = 0;
 	}
 
-	if (usess && usess->start_trace) {
-		usess->start_trace = 0;
+	if (usess && usess->active) {
+		/*
+		 * Even though the stop trace might fail, flag this session inactive so
+		 * other application coming in are not started by default.
+		 */
+		usess->active = 0;
 
 		ret = ust_app_stop_trace_all(usess);
 		if (ret < 0) {
@@ -1719,6 +1949,8 @@ int cmd_stop_trace(struct ltt_session *session)
 		}
 	}
 
+	/* Flag inactive after a successful stop. */
+	session->active = 0;
 	ret = LTTNG_OK;
 
 error:
@@ -1728,59 +1960,71 @@ error:
 /*
  * Command LTTNG_SET_CONSUMER_URI processed by the client thread.
  */
-int cmd_set_consumer_uri(int domain, struct ltt_session *session,
-		size_t nb_uri, struct lttng_uri *uris)
+int cmd_set_consumer_uri(struct ltt_session *session, size_t nb_uri,
+		struct lttng_uri *uris)
 {
 	int ret, i;
 	struct ltt_kernel_session *ksess = session->kernel_session;
 	struct ltt_ust_session *usess = session->ust_session;
-	struct consumer_output *consumer = NULL;
 
 	assert(session);
 	assert(uris);
 	assert(nb_uri > 0);
 
-	/* Can't enable consumer after session started. */
-	if (session->enabled) {
+	/* Can't set consumer URI if the session is active. */
+	if (session->active) {
 		ret = LTTNG_ERR_TRACE_ALREADY_STARTED;
 		goto error;
 	}
 
-	/*
-	 * This case switch makes sure the domain session has a temporary consumer
-	 * so the URL can be set.
-	 */
-	switch (domain) {
-	case 0:
-		/* Code flow error. A session MUST always have a consumer object */
-		assert(session->consumer);
-		/*
-		 * The URL will be added to the tracing session consumer instead of a
-		 * specific domain consumer.
-		 */
-		consumer = session->consumer;
-		break;
-	case LTTNG_DOMAIN_KERNEL:
-		/* Code flow error if we don't have a kernel session here. */
-		assert(ksess);
-		assert(ksess->consumer);
-		consumer = ksess->consumer;
-		break;
-	case LTTNG_DOMAIN_UST:
-		/* Code flow error if we don't have a kernel session here. */
-		assert(usess);
-		assert(usess->consumer);
-		consumer = usess->consumer;
-		break;
-	}
-
+	/* Set the "global" consumer URIs */
 	for (i = 0; i < nb_uri; i++) {
-		ret = add_uri_to_consumer(consumer, &uris[i], domain, session->name);
+		ret = add_uri_to_consumer(session->consumer,
+				&uris[i], 0, session->name);
 		if (ret != LTTNG_OK) {
 			goto error;
 		}
 	}
 
+	/* Set UST session URIs */
+	if (session->ust_session) {
+		for (i = 0; i < nb_uri; i++) {
+			ret = add_uri_to_consumer(
+					session->ust_session->consumer,
+					&uris[i], LTTNG_DOMAIN_UST,
+					session->name);
+			if (ret != LTTNG_OK) {
+				goto error;
+			}
+		}
+	}
+
+	/* Set kernel session URIs */
+	if (session->kernel_session) {
+		for (i = 0; i < nb_uri; i++) {
+			ret = add_uri_to_consumer(
+					session->kernel_session->consumer,
+					&uris[i], LTTNG_DOMAIN_KERNEL,
+					session->name);
+			if (ret != LTTNG_OK) {
+				goto error;
+			}
+		}
+	}
+
+	/*
+	 * Make sure to set the session in output mode after we set URI since a
+	 * session can be created without URL (thus flagged in no output mode).
+	 */
+	session->output_traces = 1;
+	if (ksess) {
+		ksess->output_traces = 1;
+	}
+
+	if (usess) {
+		usess->output_traces = 1;
+	}
+
 	/* All good! */
 	ret = LTTNG_OK;
 
@@ -1839,7 +2083,7 @@ int cmd_create_session_uri(char *name, struct lttng_uri *uris,
 	}
 
 	if (uris) {
-		ret = cmd_set_consumer_uri(0, session, nb_uri, uris);
+		ret = cmd_set_consumer_uri(session, nb_uri, uris);
 		if (ret != LTTNG_OK) {
 			goto consumer_error;
 		}
@@ -1985,7 +2229,14 @@ int cmd_calibrate(int domain, struct lttng_calibrate *calibrate)
 	{
 		struct lttng_kernel_calibrate kcalibrate;
 
-		kcalibrate.type = calibrate->type;
+		switch (calibrate->type) {
+		case LTTNG_CALIBRATE_FUNCTION:
+		default:
+			/* Default and only possible calibrate option. */
+			kcalibrate.type = LTTNG_KERNEL_CALIBRATE_KRETPROBE;
+			break;
+		}
+
 		ret = kernel_calibrate(kernel_tracer_fd, &kcalibrate);
 		if (ret < 0) {
 			ret = LTTNG_ERR_KERN_ENABLE_FAIL;
@@ -1997,7 +2248,14 @@ int cmd_calibrate(int domain, struct lttng_calibrate *calibrate)
 	{
 		struct lttng_ust_calibrate ucalibrate;
 
-		ucalibrate.type = calibrate->type;
+		switch (calibrate->type) {
+		case LTTNG_CALIBRATE_FUNCTION:
+		default:
+			/* Default and only possible calibrate option. */
+			ucalibrate.type = LTTNG_UST_CALIBRATE_TRACEPOINT;
+			break;
+		}
+
 		ret = ust_app_calibrate_glb(&ucalibrate);
 		if (ret < 0) {
 			ret = LTTNG_ERR_UST_CALIBRATE_FAIL;
@@ -2111,6 +2369,10 @@ ssize_t cmd_list_domains(struct ltt_session *session,
 	if (session->ust_session != NULL) {
 		DBG3("Listing domains found UST global domain");
 		nb_dom++;
+
+		if (session->ust_session->domain_jul.being_used) {
+			nb_dom++;
+		}
 	}
 
 	*domains = zmalloc(nb_dom * sizeof(struct lttng_domain));
@@ -2128,6 +2390,12 @@ ssize_t cmd_list_domains(struct ltt_session *session,
 		(*domains)[index].type = LTTNG_DOMAIN_UST;
 		(*domains)[index].buf_type = session->ust_session->buffer_type;
 		index++;
+
+		if (session->ust_session->domain_jul.being_used) {
+			(*domains)[index].type = LTTNG_DOMAIN_JUL;
+			(*domains)[index].buf_type = session->ust_session->buffer_type;
+			index++;
+		}
 	}
 
 	return nb_dom;
@@ -2159,16 +2427,18 @@ ssize_t cmd_list_channels(int domain, struct ltt_session *session,
 		break;
 	case LTTNG_DOMAIN_UST:
 		if (session->ust_session != NULL) {
+			rcu_read_lock();
 			nb_chan = lttng_ht_get_count(
-					session->ust_session->domain_global.channels);
+				session->ust_session->domain_global.channels);
+			rcu_read_unlock();
 		}
 		DBG3("Number of UST global channels %zd", nb_chan);
-		if (nb_chan <= 0) {
+		if (nb_chan < 0) {
 			ret = LTTNG_ERR_UST_CHAN_NOT_FOUND;
+			goto error;
 		}
 		break;
 	default:
-		*channels = NULL;
 		ret = LTTNG_ERR_UND;
 		goto error;
 	}
@@ -2181,10 +2451,6 @@ ssize_t cmd_list_channels(int domain, struct ltt_session *session,
 		}
 
 		list_lttng_channels(domain, session, *channels);
-	} else {
-		*channels = NULL;
-		/* Ret value was set in the domain switch case */
-		goto error;
 	}
 
 	return nb_chan;
@@ -2218,6 +2484,12 @@ ssize_t cmd_list_events(int domain, struct ltt_session *session,
 		}
 		break;
 	}
+	case LTTNG_DOMAIN_JUL:
+		if (session->ust_session) {
+			nb_event = list_lttng_jul_events(
+					&session->ust_session->domain_jul, events);
+		}
+		break;
 	default:
 		ret = LTTNG_ERR_UND;
 		goto error;
@@ -2278,8 +2550,9 @@ void cmd_list_lttng_sessions(struct lttng_session *sessions, uid_t uid,
 
 		strncpy(sessions[i].name, session->name, NAME_MAX);
 		sessions[i].name[NAME_MAX - 1] = '\0';
-		sessions[i].enabled = session->enabled;
+		sessions[i].enabled = session->active;
 		sessions[i].snapshot_mode = session->snapshot_mode;
+		sessions[i].live_timer_interval = session->live_timer;
 		i++;
 	}
 }
@@ -2297,9 +2570,24 @@ int cmd_data_pending(struct ltt_session *session)
 	assert(session);
 
 	/* Session MUST be stopped to ask for data availability. */
-	if (session->enabled) {
+	if (session->active) {
 		ret = LTTNG_ERR_SESSION_STARTED;
 		goto error;
+	} else {
+		/*
+		 * If stopped, just make sure we've started before else the above call
+		 * will always send that there is data pending.
+		 *
+		 * The consumer assumes that when the data pending command is received,
+		 * the trace has been started before or else no output data is written
+		 * by the streams which is a condition for data pending. So, this is
+		 * *VERY* important that we don't ask the consumer before a start
+		 * trace.
+		 */
+		if (!session->has_been_started) {
+			ret = 0;
+			goto error;
+		}
 	}
 
 	if (ksess && ksess->consumer) {
@@ -2448,7 +2736,7 @@ ssize_t cmd_snapshot_list_outputs(struct ltt_session *session,
 		struct lttng_snapshot_output **outputs)
 {
 	int ret, idx = 0;
-	struct lttng_snapshot_output *list;
+	struct lttng_snapshot_output *list = NULL;
 	struct lttng_ht_iter iter;
 	struct snapshot_output *output;
 
@@ -2462,7 +2750,7 @@ ssize_t cmd_snapshot_list_outputs(struct ltt_session *session,
 	 * set in no output mode.
 	 */
 	if (session->output_traces) {
-		ret = LTTNG_ERR_EPERM;
+		ret = -LTTNG_ERR_EPERM;
 		goto error;
 	}
 
@@ -2473,11 +2761,12 @@ ssize_t cmd_snapshot_list_outputs(struct ltt_session *session,
 
 	list = zmalloc(session->snapshot.nb_output * sizeof(*list));
 	if (!list) {
-		ret = LTTNG_ERR_NOMEM;
+		ret = -LTTNG_ERR_NOMEM;
 		goto error;
 	}
 
 	/* Copy list from session to the new list object. */
+	rcu_read_lock();
 	cds_lfht_for_each_entry(session->snapshot.output_ht->ht, &iter.iter,
 			output, node.node) {
 		assert(output->consumer);
@@ -2492,28 +2781,28 @@ ssize_t cmd_snapshot_list_outputs(struct ltt_session *session,
 			ret = uri_to_str_url(&output->consumer->dst.net.control,
 					list[idx].ctrl_url, sizeof(list[idx].ctrl_url));
 			if (ret < 0) {
-				ret = LTTNG_ERR_NOMEM;
-				goto free_error;
+				ret = -LTTNG_ERR_NOMEM;
+				goto error;
 			}
 
 			/* Data URI. */
 			ret = uri_to_str_url(&output->consumer->dst.net.data,
 					list[idx].data_url, sizeof(list[idx].data_url));
 			if (ret < 0) {
-				ret = LTTNG_ERR_NOMEM;
-				goto free_error;
+				ret = -LTTNG_ERR_NOMEM;
+				goto error;
 			}
 		}
 		idx++;
 	}
 
 	*outputs = list;
-	return session->snapshot.nb_output;
-
-free_error:
-	free(list);
+	list = NULL;
+	ret = session->snapshot.nb_output;
 error:
-	return -ret;
+	free(list);
+	rcu_read_unlock();
+	return ret;
 }
 
 /*
@@ -2565,11 +2854,11 @@ error:
 /*
  * Record a kernel snapshot.
  *
- * Return 0 on success or a LTTNG_ERR code.
+ * Return LTTNG_OK on success or a LTTNG_ERR code.
  */
 static int record_kernel_snapshot(struct ltt_kernel_session *ksess,
 		struct snapshot_output *output, struct ltt_session *session,
-		int wait, int nb_streams)
+		int wait, uint64_t nb_packets_per_stream)
 {
 	int ret;
 
@@ -2600,17 +2889,19 @@ static int record_kernel_snapshot(struct ltt_kernel_session *ksess,
 		goto error_snapshot;
 	}
 
-	ret = kernel_snapshot_record(ksess, output, wait, nb_streams);
+	ret = kernel_snapshot_record(ksess, output, wait, nb_packets_per_stream);
 	if (ret != LTTNG_OK) {
 		goto error_snapshot;
 	}
 
 	ret = LTTNG_OK;
+	goto end;
 
 error_snapshot:
 	/* Clean up copied sockets so this output can use some other later on. */
 	consumer_destroy_output_sockets(output->consumer);
 error:
+end:
 	return ret;
 }
 
@@ -2621,7 +2912,7 @@ error:
  */
 static int record_ust_snapshot(struct ltt_ust_session *usess,
 		struct snapshot_output *output, struct ltt_session *session,
-		int wait, int nb_streams)
+		int wait, uint64_t nb_packets_per_stream)
 {
 	int ret;
 
@@ -2652,14 +2943,19 @@ static int record_ust_snapshot(struct ltt_ust_session *usess,
 		goto error_snapshot;
 	}
 
-	ret = ust_app_snapshot_record(usess, output, wait, nb_streams);
+	ret = ust_app_snapshot_record(usess, output, wait, nb_packets_per_stream);
 	if (ret < 0) {
-		if (ret == -EINVAL) {
+		switch (-ret) {
+		case EINVAL:
 			ret = LTTNG_ERR_INVALID;
-			goto error_snapshot;
+			break;
+		case ENODATA:
+			ret = LTTNG_ERR_SNAPSHOT_NODATA;
+			break;
+		default:
+			ret = LTTNG_ERR_SNAPSHOT_FAIL;
+			break;
 		}
-
-		ret = LTTNG_ERR_SNAPSHOT_FAIL;
 		goto error_snapshot;
 	}
 
@@ -2672,27 +2968,90 @@ error:
 	return ret;
 }
 
-/*
- * Returns the total number of streams for a session or a negative value
- * on error.
- */
-static unsigned int get_total_nb_stream(struct ltt_session *session)
+static
+uint64_t get_session_size_one_more_packet_per_stream(struct ltt_session *session,
+	uint64_t cur_nr_packets)
 {
-	unsigned int total_streams = 0;
+	uint64_t tot_size = 0;
 
 	if (session->kernel_session) {
+		struct ltt_kernel_channel *chan;
 		struct ltt_kernel_session *ksess = session->kernel_session;
 
-		total_streams += ksess->stream_count_global;
+		cds_list_for_each_entry(chan, &ksess->channel_list.head, list) {
+			if (cur_nr_packets >= chan->channel->attr.num_subbuf) {
+				/*
+				 * Don't take channel into account if we
+				 * already grab all its packets.
+				 */
+				continue;
+			}
+			tot_size += chan->channel->attr.subbuf_size
+				* chan->stream_count;
+		}
 	}
 
 	if (session->ust_session) {
 		struct ltt_ust_session *usess = session->ust_session;
 
-		total_streams += ust_app_get_nb_stream(usess);
+		tot_size += ust_app_get_size_one_more_packet_per_stream(usess,
+				cur_nr_packets);
+	}
+
+	return tot_size;
+}
+
+/*
+ * Calculate the number of packets we can grab from each stream that
+ * fits within the overall snapshot max size.
+ *
+ * Returns -1 on error, 0 means infinite number of packets, else > 0 is
+ * the number of packets per stream.
+ *
+ * TODO: this approach is not perfect: we consider the worse case
+ * (packet filling the sub-buffers) as an upper bound, but we could do
+ * better if we do this calculation while we actually grab the packet
+ * content: we would know how much padding we don't actually store into
+ * the file.
+ *
+ * This algorithm is currently bounded by the number of packets per
+ * stream.
+ *
+ * Since we call this algorithm before actually grabbing the data, it's
+ * an approximation: for instance, applications could appear/disappear
+ * in between this call and actually grabbing data.
+ */
+static
+int64_t get_session_nb_packets_per_stream(struct ltt_session *session, uint64_t max_size)
+{
+	int64_t size_left;
+	uint64_t cur_nb_packets = 0;
+
+	if (!max_size) {
+		return 0;	/* Infinite */
 	}
 
-	return total_streams;
+	size_left = max_size;
+	for (;;) {
+		uint64_t one_more_packet_tot_size;
+
+		one_more_packet_tot_size = get_session_size_one_more_packet_per_stream(session,
+					cur_nb_packets);
+		if (!one_more_packet_tot_size) {
+			/* We are already grabbing all packets. */
+			break;
+		}
+		size_left -= one_more_packet_tot_size;
+		if (size_left < 0) {
+			break;
+		}
+		cur_nb_packets++;
+	}
+	if (!cur_nb_packets) {
+		/* Not enough room to grab one packet of each stream, error. */
+		return -1;
+	}
+	return cur_nb_packets;
 }
 
 /*
@@ -2709,7 +3068,7 @@ int cmd_snapshot_record(struct ltt_session *session,
 	int ret = LTTNG_OK;
 	unsigned int use_tmp_output = 0;
 	struct snapshot_output tmp_output;
-	unsigned int nb_streams, snapshot_success = 0;
+	unsigned int snapshot_success = 0;
 
 	assert(session);
 
@@ -2725,7 +3084,7 @@ int cmd_snapshot_record(struct ltt_session *session,
 	}
 
 	/* The session needs to be started at least once. */
-	if (!session->started) {
+	if (!session->has_been_started) {
 		ret = LTTNG_ERR_START_SESSION_ONCE;
 		goto error;
 	}
@@ -2748,18 +3107,20 @@ int cmd_snapshot_record(struct ltt_session *session,
 		use_tmp_output = 1;
 	}
 
-	/*
-	 * Get the total number of stream of that session which is used by the
-	 * maximum size of the snapshot feature.
-	 */
-	nb_streams = get_total_nb_stream(session);
-
 	if (session->kernel_session) {
 		struct ltt_kernel_session *ksess = session->kernel_session;
 
 		if (use_tmp_output) {
+			int64_t nb_packets_per_stream;
+
+			nb_packets_per_stream = get_session_nb_packets_per_stream(session,
+					tmp_output.max_size);
+			if (nb_packets_per_stream < 0) {
+				ret = LTTNG_ERR_MAX_SIZE_INVALID;
+				goto error;
+			}
 			ret = record_kernel_snapshot(ksess, &tmp_output, session,
-					wait, nb_streams);
+					wait, nb_packets_per_stream);
 			if (ret != LTTNG_OK) {
 				goto error;
 			}
@@ -2771,6 +3132,8 @@ int cmd_snapshot_record(struct ltt_session *session,
 			rcu_read_lock();
 			cds_lfht_for_each_entry(session->snapshot.output_ht->ht,
 					&iter.iter, sout, node.node) {
+				int64_t nb_packets_per_stream;
+
 				/*
 				 * Make a local copy of the output and assign the possible
 				 * temporary value given by the caller.
@@ -2778,11 +3141,17 @@ int cmd_snapshot_record(struct ltt_session *session,
 				memset(&tmp_output, 0, sizeof(tmp_output));
 				memcpy(&tmp_output, sout, sizeof(tmp_output));
 
-				/* Use temporary max size. */
 				if (output->max_size != (uint64_t) -1ULL) {
 					tmp_output.max_size = output->max_size;
 				}
 
+				nb_packets_per_stream = get_session_nb_packets_per_stream(session,
+						tmp_output.max_size);
+				if (nb_packets_per_stream < 0) {
+					ret = LTTNG_ERR_MAX_SIZE_INVALID;
+					goto error;
+				}
+
 				/* Use temporary name. */
 				if (*output->name != '\0') {
 					strncpy(tmp_output.name, output->name,
@@ -2792,7 +3161,7 @@ int cmd_snapshot_record(struct ltt_session *session,
 				tmp_output.nb_snapshot = session->snapshot.nb_snapshot;
 
 				ret = record_kernel_snapshot(ksess, &tmp_output,
-						session, wait, nb_streams);
+						session, wait, nb_packets_per_stream);
 				if (ret != LTTNG_OK) {
 					rcu_read_unlock();
 					goto error;
@@ -2807,8 +3176,16 @@ int cmd_snapshot_record(struct ltt_session *session,
 		struct ltt_ust_session *usess = session->ust_session;
 
 		if (use_tmp_output) {
+			int64_t nb_packets_per_stream;
+
+			nb_packets_per_stream = get_session_nb_packets_per_stream(session,
+					tmp_output.max_size);
+			if (nb_packets_per_stream < 0) {
+				ret = LTTNG_ERR_MAX_SIZE_INVALID;
+				goto error;
+			}
 			ret = record_ust_snapshot(usess, &tmp_output, session,
-					wait, nb_streams);
+					wait, nb_packets_per_stream);
 			if (ret != LTTNG_OK) {
 				goto error;
 			}
@@ -2820,6 +3197,8 @@ int cmd_snapshot_record(struct ltt_session *session,
 			rcu_read_lock();
 			cds_lfht_for_each_entry(session->snapshot.output_ht->ht,
 					&iter.iter, sout, node.node) {
+				int64_t nb_packets_per_stream;
+
 				/*
 				 * Make a local copy of the output and assign the possible
 				 * temporary value given by the caller.
@@ -2827,11 +3206,18 @@ int cmd_snapshot_record(struct ltt_session *session,
 				memset(&tmp_output, 0, sizeof(tmp_output));
 				memcpy(&tmp_output, sout, sizeof(tmp_output));
 
-				/* Use temporary max size. */
 				if (output->max_size != (uint64_t) -1ULL) {
 					tmp_output.max_size = output->max_size;
 				}
 
+				nb_packets_per_stream = get_session_nb_packets_per_stream(session,
+						tmp_output.max_size);
+				if (nb_packets_per_stream < 0) {
+					ret = LTTNG_ERR_MAX_SIZE_INVALID;
+					rcu_read_unlock();
+					goto error;
+				}
+
 				/* Use temporary name. */
 				if (*output->name != '\0') {
 					strncpy(tmp_output.name, output->name,
@@ -2841,7 +3227,7 @@ int cmd_snapshot_record(struct ltt_session *session,
 				tmp_output.nb_snapshot = session->snapshot.nb_snapshot;
 
 				ret = record_ust_snapshot(usess, &tmp_output, session,
-						wait, nb_streams);
+						wait, nb_packets_per_stream);
 				if (ret != LTTNG_OK) {
 					rcu_read_unlock();
 					goto error;