X-Git-Url: http://git.efficios.com/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fbin%2Flttng-sessiond%2Fcmd.c;h=d882b074d54cd4f0348365ab4adb218ce263c48b;hp=bba77023a6415ff0b52e9f0dcfde6729c5a0856f;hb=0e1155633b00241b8b1e5a9bb683cf91b28f5eeb;hpb=d2f11c4a439e76804369810907e2a22dfcd0956f

diff --git a/src/bin/lttng-sessiond/cmd.c b/src/bin/lttng-sessiond/cmd.c
index bba77023a..d882b074d 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 <inttypes.h>
 #include <urcu/list.h>
 #include <urcu/uatomic.h>
 
@@ -24,15 +25,17 @@
 #include <common/common.h>
 #include <common/sessiond-comm/sessiond-comm.h>
 #include <common/relayd/relayd.h>
+#include <common/utils.h>
 
 #include "channel.h"
 #include "consumer.h"
 #include "event.h"
-#include "health.h"
+#include "health-sessiond.h"
 #include "kernel.h"
 #include "kernel-consumer.h"
 #include "lttng-sessiond.h"
 #include "utils.h"
+#include "syscall.h"
 
 #include "cmd.h"
 
@@ -45,6 +48,21 @@
 static pthread_mutex_t relayd_net_seq_idx_lock = PTHREAD_MUTEX_INITIALIZER;
 static uint64_t relayd_net_seq_idx;
 
+/*
+ * Both functions below are special case for the Kernel domain when
+ * enabling/disabling all events.
+ */
+static
+int enable_kevent_all(struct ltt_session *session,
+		struct lttng_domain *domain, char *channel_name,
+		struct lttng_event *event,
+		char *filter_expression,
+		struct lttng_filter_bytecode *filter, int wpipe);
+static
+int disable_kevent_all(struct ltt_session *session, int domain,
+		char *channel_name,
+		struct lttng_event *event);
+
 /*
  * Create a session path used by list_lttng_sessions for the case that the
  * session consumer is on the network.
@@ -164,6 +182,8 @@ 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:
@@ -180,6 +200,57 @@ static void list_lttng_channels(int domain, struct ltt_session *session,
 	}
 }
 
+/*
+ * Create a list of agent domain events.
+ *
+ * Return number of events in list on success or else a negative value.
+ */
+static int list_lttng_agent_events(struct agent *agt,
+		struct lttng_event **events)
+{
+	int i = 0, ret = 0;
+	unsigned int nb_event = 0;
+	struct agent_event *event;
+	struct lttng_event *tmp_events;
+	struct lttng_ht_iter iter;
+
+	assert(agt);
+	assert(events);
+
+	DBG3("Listing agent events");
+
+	nb_event = lttng_ht_get_count(agt->events);
+	if (nb_event == 0) {
+		ret = nb_event;
+		goto error;
+	}
+
+	tmp_events = zmalloc(nb_event * sizeof(*tmp_events));
+	if (!tmp_events) {
+		PERROR("zmalloc agent events session");
+		ret = -LTTNG_ERR_FATAL;
+		goto error;
+	}
+
+	rcu_read_lock();
+	cds_lfht_for_each_entry(agt->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.
  */
@@ -254,6 +325,9 @@ 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++;
 	}
 
@@ -287,7 +361,8 @@ static int list_lttng_kernel_events(char *channel_name,
 	DBG("Listing events for channel %s", kchan->channel->name);
 
 	if (nb_event == 0) {
-		goto end;
+		*events = NULL;
+		goto syscall;
 	}
 
 	*events = zmalloc(nb_event * sizeof(struct lttng_event));
@@ -334,7 +409,19 @@ static int list_lttng_kernel_events(char *channel_name,
 		i++;
 	}
 
-end:
+syscall:
+	if (syscall_table) {
+		ssize_t new_size;
+
+		new_size = syscall_list_channel(kchan, events, nb_event);
+		if (new_size < 0) {
+			free(events);
+			ret = -new_size;
+			goto error;
+		}
+		nb_event = new_size;
+	}
+
 	return nb_event;
 
 error:
@@ -404,6 +491,7 @@ 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;
 		}
 
@@ -460,9 +548,6 @@ static int init_kernel_tracing(struct ltt_kernel_session *session)
 	if (session->consumer_fds_sent == 0 && session->consumer != NULL) {
 		cds_lfht_for_each_entry(session->consumer->socks->ht, &iter.iter,
 				socket, node.node) {
-			/* Code flow error */
-			assert(socket->fd >= 0);
-
 			pthread_mutex_lock(socket->lock);
 			ret = kernel_consumer_send_session(socket, session);
 			pthread_mutex_unlock(socket->lock);
@@ -546,9 +631,10 @@ error:
 /*
  * Connect to the relayd using URI and send the socket to the right consumer.
  */
-static int send_consumer_relayd_socket(int domain, struct ltt_session *session,
+static int send_consumer_relayd_socket(int domain, unsigned int session_id,
 		struct lttng_uri *relayd_uri, struct consumer_output *consumer,
-		struct consumer_socket *consumer_sock)
+		struct consumer_socket *consumer_sock,
+		char *session_name, char *hostname, int session_live_timer)
 {
 	int ret;
 	struct lttcomm_relayd_sock *rsock = NULL;
@@ -560,11 +646,6 @@ static int send_consumer_relayd_socket(int domain, struct ltt_session *session,
 	}
 	assert(rsock);
 
-	/* If the control socket is connected, network session is ready */
-	if (relayd_uri->stype == LTTNG_STREAM_CONTROL) {
-		session->net_handle = 1;
-	}
-
 	/* Set the network sequence index if not set. */
 	if (consumer->net_seq_index == (uint64_t) -1ULL) {
 		pthread_mutex_lock(&relayd_net_seq_idx_lock);
@@ -579,7 +660,8 @@ static int send_consumer_relayd_socket(int domain, struct ltt_session *session,
 
 	/* Send relayd socket to consumer. */
 	ret = consumer_send_relayd_socket(consumer_sock, rsock, consumer,
-			relayd_uri->stype, session->id);
+			relayd_uri->stype, session_id,
+			session_name, hostname, session_live_timer);
 	if (ret < 0) {
 		ret = LTTNG_ERR_ENABLE_CONSUMER_FAIL;
 		goto close_sock;
@@ -606,10 +688,11 @@ close_sock:
 error:
 	if (ret != LTTNG_OK) {
 		/*
-		 * On error, nullify the consumer sequence index so streams are not
-		 * associated with it once sent to the consumer.
+		 * The consumer output for this session should not be used anymore
+		 * since the relayd connection failed thus making any tracing or/and
+		 * streaming not usable.
 		 */
-		uatomic_set(&consumer->net_seq_index, -1);
+		consumer->enabled = 0;
 	}
 	return ret;
 }
@@ -619,19 +702,20 @@ error:
  * helper function to facilitate sending the information to the consumer for a
  * session.
  */
-static int send_consumer_relayd_sockets(int domain,
-		struct ltt_session *session, struct consumer_output *consumer,
-		struct consumer_socket *sock)
+static int send_consumer_relayd_sockets(int domain, unsigned int session_id,
+		struct consumer_output *consumer, struct consumer_socket *sock,
+		char *session_name, char *hostname, int session_live_timer)
 {
 	int ret = LTTNG_OK;
 
-	assert(session);
 	assert(consumer);
+	assert(sock);
 
 	/* Sending control relayd socket. */
 	if (!sock->control_sock_sent) {
-		ret = send_consumer_relayd_socket(domain, session,
-				&consumer->dst.net.control, consumer, sock);
+		ret = send_consumer_relayd_socket(domain, session_id,
+				&consumer->dst.net.control, consumer, sock,
+				session_name, hostname, session_live_timer);
 		if (ret != LTTNG_OK) {
 			goto error;
 		}
@@ -639,8 +723,9 @@ static int send_consumer_relayd_sockets(int domain,
 
 	/* Sending data relayd socket. */
 	if (!sock->data_sock_sent) {
-		ret = send_consumer_relayd_socket(domain, session,
-				&consumer->dst.net.data, consumer, sock);
+		ret = send_consumer_relayd_socket(domain, session_id,
+				&consumer->dst.net.data, consumer, sock,
+				session_name, hostname, session_live_timer);
 		if (ret != LTTNG_OK) {
 			goto error;
 		}
@@ -677,16 +762,17 @@ int cmd_setup_relayd(struct ltt_session *session)
 		/* For each consumer socket, send relayd sockets */
 		cds_lfht_for_each_entry(usess->consumer->socks->ht, &iter.iter,
 				socket, node.node) {
-			/* Code flow error */
-			assert(socket->fd >= 0);
-
 			pthread_mutex_lock(socket->lock);
-			ret = send_consumer_relayd_sockets(LTTNG_DOMAIN_UST, session,
-					usess->consumer, socket);
+			ret = send_consumer_relayd_sockets(LTTNG_DOMAIN_UST, session->id,
+					usess->consumer, socket,
+					session->name, session->hostname,
+					session->live_timer);
 			pthread_mutex_unlock(socket->lock);
 			if (ret != LTTNG_OK) {
 				goto error;
 			}
+			/* Session is now ready for network streaming. */
+			session->net_handle = 1;
 		}
 	}
 
@@ -694,16 +780,17 @@ int cmd_setup_relayd(struct ltt_session *session)
 			&& ksess->consumer->enabled) {
 		cds_lfht_for_each_entry(ksess->consumer->socks->ht, &iter.iter,
 				socket, node.node) {
-			/* Code flow error */
-			assert(socket->fd >= 0);
-
 			pthread_mutex_lock(socket->lock);
-			ret = send_consumer_relayd_sockets(LTTNG_DOMAIN_KERNEL, session,
-					ksess->consumer, socket);
+			ret = send_consumer_relayd_sockets(LTTNG_DOMAIN_KERNEL, session->id,
+					ksess->consumer, socket,
+					session->name, session->hostname,
+					session->live_timer);
 			pthread_mutex_unlock(socket->lock);
 			if (ret != LTTNG_OK) {
 				goto error;
 			}
+			/* Session is now ready for network streaming. */
+			session->net_handle = 1;
 		}
 	}
 
@@ -721,7 +808,7 @@ static int start_kernel_session(struct ltt_kernel_session *ksess, int wpipe)
 	struct ltt_kernel_channel *kchan;
 
 	/* Open kernel metadata */
-	if (ksess->metadata == NULL) {
+	if (ksess->metadata == NULL && ksess->output_traces) {
 		ret = kernel_open_metadata(ksess);
 		if (ret < 0) {
 			ret = LTTNG_ERR_KERN_META_FAIL;
@@ -730,7 +817,7 @@ static int start_kernel_session(struct ltt_kernel_session *ksess, int wpipe)
 	}
 
 	/* Open kernel metadata stream */
-	if (ksess->metadata_stream_fd < 0) {
+	if (ksess->metadata && ksess->metadata_stream_fd < 0) {
 		ret = kernel_open_metadata_stream(ksess);
 		if (ret < 0) {
 			ERR("Kernel create metadata stream failed");
@@ -769,7 +856,7 @@ 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;
 
@@ -856,16 +943,36 @@ int cmd_enable_channel(struct ltt_session *session,
 
 	DBG("Enabling channel %s for session %s", attr->name, session->name);
 
+	rcu_read_lock();
+
 	/*
 	 * 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;
 	}
 
-	rcu_read_lock();
+	/*
+	 * If the session is a live session, remove the switch timer, the
+	 * live timer does the same thing but sends also synchronisation
+	 * beacons for inactive streams.
+	 */
+	if (session->live_timer > 0) {
+		attr->attr.live_timer_interval = session->live_timer;
+		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:
@@ -876,6 +983,9 @@ int cmd_enable_channel(struct ltt_session *session,
 				session->kernel_session);
 		if (kchan == NULL) {
 			ret = channel_kernel_create(session->kernel_session, attr, wpipe);
+			if (attr->name[0] != '\0') {
+				session->kernel_session->has_non_default_channel = 1;
+			}
 		} else {
 			ret = channel_kernel_enable(session->kernel_session, kchan);
 		}
@@ -896,6 +1006,9 @@ int cmd_enable_channel(struct ltt_session *session,
 		uchan = trace_ust_find_channel_by_name(chan_ht, attr->name);
 		if (uchan == NULL) {
 			ret = channel_ust_create(usess, attr, domain->buf_type);
+			if (attr->name[0] != '\0') {
+				usess->has_non_default_channel = 1;
+			}
 		} else {
 			ret = channel_ust_enable(usess, uchan);
 		}
@@ -916,9 +1029,24 @@ error:
  * Command LTTNG_DISABLE_EVENT processed by the client thread.
  */
 int cmd_disable_event(struct ltt_session *session, int domain,
-		char *channel_name, char *event_name)
+		char *channel_name,
+		struct lttng_event *event)
 {
 	int ret;
+	char *event_name;
+
+	DBG("Disable event command for event \'%s\'", event->name);
+
+	event_name = event->name;
+
+	if (event->loglevel_type || event->loglevel || event->enabled
+			|| event->pid || event->filter || event->exclusion) {
+		return LTTNG_ERR_UNK;
+	}
+	/* Special handling for kernel domain all events. */
+	if (domain == LTTNG_DOMAIN_KERNEL && !strcmp(event_name, "*")) {
+		return disable_kevent_all(session, domain, channel_name, event);
+	}
 
 	rcu_read_lock();
 
@@ -930,14 +1058,38 @@ int cmd_disable_event(struct ltt_session *session, int domain,
 
 		ksess = session->kernel_session;
 
+		/*
+		 * If a non-default channel has been created in the
+		 * session, explicitely require that -c chan_name needs
+		 * to be provided.
+		 */
+		if (ksess->has_non_default_channel && channel_name[0] == '\0') {
+			ret = LTTNG_ERR_NEED_CHANNEL_NAME;
+			goto error;
+		}
+
 		kchan = trace_kernel_get_channel_by_name(channel_name, ksess);
 		if (kchan == NULL) {
 			ret = LTTNG_ERR_KERN_CHAN_NOT_FOUND;
 			goto error;
 		}
 
-		ret = event_kernel_disable_tracepoint(kchan, event_name);
-		if (ret != LTTNG_OK) {
+		switch (event->type) {
+		case LTTNG_EVENT_ALL:
+		case LTTNG_EVENT_TRACEPOINT:
+			ret = event_kernel_disable_tracepoint(kchan, event_name);
+			if (ret != LTTNG_OK) {
+				goto error;
+			}
+			break;
+		case LTTNG_EVENT_SYSCALL:
+			ret = event_kernel_disable_syscall(kchan, event_name);
+			if (ret != LTTNG_OK) {
+				goto error;
+			}
+			break;
+		default:
+			ret = LTTNG_ERR_UNK;
 			goto error;
 		}
 
@@ -951,6 +1103,16 @@ int cmd_disable_event(struct ltt_session *session, int domain,
 
 		usess = session->ust_session;
 
+		/*
+		 * If a non-default channel has been created in the
+		 * session, explicitely require that -c chan_name needs
+		 * to be provided.
+		 */
+		if (usess->has_non_default_channel && channel_name[0] == '\0') {
+			ret = LTTNG_ERR_NEED_CHANNEL_NAME;
+			goto error;
+		}
+
 		uchan = trace_ust_find_channel_by_name(usess->domain_global.channels,
 				channel_name);
 		if (uchan == NULL) {
@@ -958,8 +1120,15 @@ int cmd_disable_event(struct ltt_session *session, int domain,
 			goto error;
 		}
 
-		ret = event_ust_disable_tracepoint(usess, uchan, event_name);
-		if (ret != LTTNG_OK) {
+		switch (event->type) {
+		case LTTNG_EVENT_ALL:
+			ret = event_ust_disable_tracepoint(usess, uchan, event_name);
+			if (ret != LTTNG_OK) {
+				goto error;
+			}
+			break;
+		default:
+			ret = LTTNG_ERR_UNK;
 			goto error;
 		}
 
@@ -967,6 +1136,40 @@ int cmd_disable_event(struct ltt_session *session, int domain,
 				channel_name);
 		break;
 	}
+	case LTTNG_DOMAIN_LOG4J:
+	case LTTNG_DOMAIN_JUL:
+	case LTTNG_DOMAIN_PYTHON:
+	{
+		struct agent *agt;
+		struct ltt_ust_session *usess = session->ust_session;
+
+		assert(usess);
+
+		switch (event->type) {
+		case LTTNG_EVENT_ALL:
+			break;
+		default:
+			ret = LTTNG_ERR_UNK;
+			goto error;
+		}
+
+		agt = trace_ust_find_agent(usess, domain);
+		if (!agt) {
+			ret = -LTTNG_ERR_UST_EVENT_NOT_FOUND;
+			goto error;
+		}
+		/* The wild card * means that everything should be disabled. */
+		if (strncmp(event->name, "*", 1) == 0 && strlen(event->name) == 1) {
+			ret = event_agent_disable_all(usess, agt);
+		} else {
+			ret = event_agent_disable(usess, agt, event_name);
+		}
+		if (ret != LTTNG_OK) {
+			goto error;
+		}
+
+		break;
+	}
 #if 0
 	case LTTNG_DOMAIN_UST_EXEC_NAME:
 	case LTTNG_DOMAIN_UST_PID:
@@ -985,10 +1188,12 @@ error:
 }
 
 /*
- * Command LTTNG_DISABLE_ALL_EVENT processed by the client thread.
+ * Command LTTNG_DISABLE_EVENT for event "*" processed by the client thread.
  */
-int cmd_disable_event_all(struct ltt_session *session, int domain,
-		char *channel_name)
+static
+int disable_kevent_all(struct ltt_session *session, int domain,
+		char *channel_name,
+		struct lttng_event *event)
 {
 	int ret;
 
@@ -1002,48 +1207,43 @@ int cmd_disable_event_all(struct ltt_session *session, int domain,
 
 		ksess = session->kernel_session;
 
+		/*
+		 * If a non-default channel has been created in the
+		 * session, explicitely require that -c chan_name needs
+		 * to be provided.
+		 */
+		if (ksess->has_non_default_channel && channel_name[0] == '\0') {
+			ret = LTTNG_ERR_NEED_CHANNEL_NAME;
+			goto error;
+		}
+
 		kchan = trace_kernel_get_channel_by_name(channel_name, ksess);
 		if (kchan == NULL) {
 			ret = LTTNG_ERR_KERN_CHAN_NOT_FOUND;
 			goto error;
 		}
 
-		ret = event_kernel_disable_all(kchan);
-		if (ret != LTTNG_OK) {
+		switch (event->type) {
+		case LTTNG_EVENT_ALL:
+			ret = event_kernel_disable_all(kchan);
+			if (ret != LTTNG_OK) {
+				goto error;
+			}
+			break;
+		case LTTNG_EVENT_SYSCALL:
+			ret = event_kernel_disable_syscall(kchan, "");
+			if (ret != LTTNG_OK) {
+				goto error;
+			}
+			break;
+		default:
+			ret = LTTNG_ERR_UNK;
 			goto error;
 		}
 
 		kernel_wait_quiescent(kernel_tracer_fd);
 		break;
 	}
-	case LTTNG_DOMAIN_UST:
-	{
-		struct ltt_ust_session *usess;
-		struct ltt_ust_channel *uchan;
-
-		usess = session->ust_session;
-
-		uchan = trace_ust_find_channel_by_name(usess->domain_global.channels,
-				channel_name);
-		if (uchan == NULL) {
-			ret = LTTNG_ERR_UST_CHAN_NOT_FOUND;
-			goto error;
-		}
-
-		ret = event_ust_disable_all_tracepoints(usess, uchan);
-		if (ret != 0) {
-			goto error;
-		}
-
-		DBG3("Disable all UST events in channel %s completed", channel_name);
-
-		break;
-	}
-#if 0
-	case LTTNG_DOMAIN_UST_EXEC_NAME:
-	case LTTNG_DOMAIN_UST_PID:
-	case LTTNG_DOMAIN_UST_PID_FOLLOW_CHILDREN:
-#endif
 	default:
 		ret = LTTNG_ERR_UND;
 		goto error;
@@ -1076,7 +1276,6 @@ int cmd_add_context(struct ltt_session *session, int domain,
 			}
 			chan_kern_created = 1;
 		}
-
 		/* Add kernel context to kernel tracer */
 		ret = context_kernel_add(session->kernel_session, ctx, channel_name);
 		if (ret != LTTNG_OK) {
@@ -1086,10 +1285,11 @@ int cmd_add_context(struct ltt_session *session, int domain,
 	case LTTNG_DOMAIN_UST:
 	{
 		struct ltt_ust_session *usess = session->ust_session;
+		unsigned int chan_count;
+
 		assert(usess);
 
-		unsigned int chan_count =
-			lttng_ht_get_count(usess->domain_global.channels);
+		chan_count = lttng_ht_get_count(usess->domain_global.channels);
 		if (chan_count == 0) {
 			struct lttng_channel *attr;
 			/* Create default channel */
@@ -1151,12 +1351,47 @@ error:
 	return ret;
 }
 
+static int validate_event_name(const char *name)
+{
+	int ret = 0;
+	const char *c = name;
+	const char *event_name_end = c + LTTNG_SYMBOL_NAME_LEN;
+
+	/*
+	 * Make sure that unescaped wildcards are only used as the last
+	 * character of the event name.
+	 */
+	while (c < event_name_end) {
+		switch (*c) {
+		case '\0':
+			goto end;
+		case '\\':
+			c++;
+			break;
+		case '*':
+			if ((c + 1) < event_name_end && *(c + 1)) {
+				/* Wildcard is not the last character */
+				ret = LTTNG_ERR_INVALID_EVENT_NAME;
+				goto end;
+			}
+		default:
+			break;
+		}
+		c++;
+	}
+end:
+	return ret;
+}
+
 /*
  * Command LTTNG_ENABLE_EVENT processed by the client thread.
  */
 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;
@@ -1165,6 +1400,19 @@ int cmd_enable_event(struct ltt_session *session, struct lttng_domain *domain,
 	assert(event);
 	assert(channel_name);
 
+	DBG("Enable event command for event \'%s\'", event->name);
+
+	/* Special handling for kernel domain all events. */
+	if (domain->type == LTTNG_DOMAIN_KERNEL && !strcmp(event->name, "*")) {
+		return enable_kevent_all(session, domain, channel_name, event,
+				filter_expression, filter, wpipe);
+	}
+
+	ret = validate_event_name(event->name);
+	if (ret) {
+		goto error;
+	}
+
 	rcu_read_lock();
 
 	switch (domain->type) {
@@ -1172,6 +1420,17 @@ int cmd_enable_event(struct ltt_session *session, struct lttng_domain *domain,
 	{
 		struct ltt_kernel_channel *kchan;
 
+		/*
+		 * If a non-default channel has been created in the
+		 * session, explicitely require that -c chan_name needs
+		 * to be provided.
+		 */
+		if (session->kernel_session->has_non_default_channel
+				&& channel_name[0] == '\0') {
+			ret = LTTNG_ERR_NEED_CHANNEL_NAME;
+			goto error;
+		}
+
 		kchan = trace_kernel_get_channel_by_name(channel_name,
 				session->kernel_session);
 		if (kchan == NULL) {
@@ -1202,12 +1461,29 @@ int cmd_enable_event(struct ltt_session *session, struct lttng_domain *domain,
 			goto error;
 		}
 
-		ret = event_kernel_enable_tracepoint(kchan, event);
-		if (ret != LTTNG_OK) {
-			if (channel_created) {
-				/* Let's not leak a useless channel. */
-				kernel_destroy_channel(kchan);
+		switch (event->type) {
+		case LTTNG_EVENT_ALL:
+		case LTTNG_EVENT_PROBE:
+		case LTTNG_EVENT_FUNCTION:
+		case LTTNG_EVENT_FUNCTION_ENTRY:
+		case LTTNG_EVENT_TRACEPOINT:
+			ret = event_kernel_enable_tracepoint(kchan, event);
+			if (ret != LTTNG_OK) {
+				if (channel_created) {
+					/* Let's not leak a useless channel. */
+					kernel_destroy_channel(kchan);
+				}
+				goto error;
+			}
+			break;
+		case LTTNG_EVENT_SYSCALL:
+			ret = event_kernel_enable_syscall(kchan, event->name);
+			if (ret != LTTNG_OK) {
+				goto error;
 			}
+			break;
+		default:
+			ret = LTTNG_ERR_UNK;
 			goto error;
 		}
 
@@ -1221,6 +1497,16 @@ int cmd_enable_event(struct ltt_session *session, struct lttng_domain *domain,
 
 		assert(usess);
 
+		/*
+		 * If a non-default channel has been created in the
+		 * session, explicitely require that -c chan_name needs
+		 * to be provided.
+		 */
+		if (usess->has_non_default_channel && channel_name[0] == '\0') {
+			ret = LTTNG_ERR_NEED_CHANNEL_NAME;
+			goto error;
+		}
+
 		/* Get channel from global UST domain */
 		uchan = trace_ust_find_channel_by_name(usess->domain_global.channels,
 				channel_name);
@@ -1248,10 +1534,86 @@ 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);
+		if (ret != LTTNG_OK) {
+			goto error;
+		}
+		break;
+	}
+	case LTTNG_DOMAIN_LOG4J:
+	case LTTNG_DOMAIN_JUL:
+	case LTTNG_DOMAIN_PYTHON:
+	{
+		const char *default_event_name, *default_chan_name;
+		struct agent *agt;
+		struct lttng_event uevent;
+		struct lttng_domain tmp_dom;
+		struct ltt_ust_session *usess = session->ust_session;
+
+		assert(usess);
+
+		agt = trace_ust_find_agent(usess, domain->type);
+		if (!agt) {
+			agt = agent_create(domain->type);
+			if (!agt) {
+				ret = -LTTNG_ERR_NOMEM;
+				goto error;
+			}
+			agent_add(agt, usess->agents);
+		}
+
+		/* Create the default tracepoint. */
+		memset(&uevent, 0, sizeof(uevent));
+		uevent.type = LTTNG_EVENT_TRACEPOINT;
+		uevent.loglevel_type = LTTNG_EVENT_LOGLEVEL_ALL;
+		default_event_name = event_get_default_agent_ust_name(domain->type);
+		if (!default_event_name) {
+			ret = -LTTNG_ERR_FATAL;
+			goto error;
+		}
+		strncpy(uevent.name, default_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;
+
+		switch (domain->type) {
+		case LTTNG_DOMAIN_LOG4J:
+			default_chan_name = DEFAULT_LOG4J_CHANNEL_NAME;
+			break;
+		case LTTNG_DOMAIN_JUL:
+			default_chan_name = DEFAULT_JUL_CHANNEL_NAME;
+			break;
+		case LTTNG_DOMAIN_PYTHON:
+			default_chan_name = DEFAULT_PYTHON_CHANNEL_NAME;
+			break;
+		default:
+			/* The switch/case we are in should avoid this else big problem */
+			assert(0);
+		}
+
+		ret = cmd_enable_event(session, &tmp_dom, (char *) default_chan_name,
+			&uevent, filter_expression, filter, NULL, wpipe);
+		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_agent_enable_all(usess, agt, event, filter);
+		} else {
+			ret = event_agent_enable(usess, agt, event, filter);
+		}
 		if (ret != LTTNG_OK) {
 			goto error;
 		}
+
 		break;
 	}
 #if 0
@@ -1272,10 +1634,13 @@ error:
 }
 
 /*
- * Command LTTNG_ENABLE_ALL_EVENT processed by the client thread.
+ * Command LTTNG_ENABLE_EVENT for event "*" processed by the client thread.
  */
-int cmd_enable_event_all(struct ltt_session *session,
-		struct lttng_domain *domain, char *channel_name, int event_type,
+static
+int enable_kevent_all(struct ltt_session *session,
+		struct lttng_domain *domain, char *channel_name,
+		struct lttng_event *event,
+		char *filter_expression,
 		struct lttng_filter_bytecode *filter, int wpipe)
 {
 	int ret;
@@ -1293,6 +1658,17 @@ int cmd_enable_event_all(struct ltt_session *session,
 
 		assert(session->kernel_session);
 
+		/*
+		 * If a non-default channel has been created in the
+		 * session, explicitely require that -c chan_name needs
+		 * to be provided.
+		 */
+		if (session->kernel_session->has_non_default_channel
+				&& channel_name[0] == '\0') {
+			ret = LTTNG_ERR_NEED_CHANNEL_NAME;
+			goto error;
+		}
+
 		kchan = trace_kernel_get_channel_by_name(channel_name,
 				session->kernel_session);
 		if (kchan == NULL) {
@@ -1318,9 +1694,12 @@ int cmd_enable_event_all(struct ltt_session *session,
 			assert(kchan);
 		}
 
-		switch (event_type) {
+		switch (event->type) {
 		case LTTNG_EVENT_SYSCALL:
-			ret = event_kernel_enable_all_syscalls(kchan, kernel_tracer_fd);
+			ret = event_kernel_enable_syscall(kchan, "");
+			if (ret != LTTNG_OK) {
+				goto error;
+			}
 			break;
 		case LTTNG_EVENT_TRACEPOINT:
 			/*
@@ -1350,70 +1729,10 @@ int cmd_enable_event_all(struct ltt_session *session,
 		kernel_wait_quiescent(kernel_tracer_fd);
 		break;
 	}
-	case LTTNG_DOMAIN_UST:
-	{
-		struct ltt_ust_channel *uchan;
-		struct ltt_ust_session *usess = session->ust_session;
-
-		assert(usess);
-
-		/* Get channel from global UST domain */
-		uchan = trace_ust_find_channel_by_name(usess->domain_global.channels,
-				channel_name);
-		if (uchan == NULL) {
-			/* Create default channel */
-			attr = channel_new_default_attr(LTTNG_DOMAIN_UST,
-					usess->buffer_type);
-			if (attr == NULL) {
-				ret = LTTNG_ERR_FATAL;
-				goto error;
-			}
-			strncpy(attr->name, channel_name, sizeof(attr->name));
-
-			ret = cmd_enable_channel(session, domain, attr, wpipe);
-			if (ret != LTTNG_OK) {
-				free(attr);
-				goto error;
-			}
-			free(attr);
-
-			/* Get the newly created channel reference back */
-			uchan = trace_ust_find_channel_by_name(
-					usess->domain_global.channels, channel_name);
-			assert(uchan);
-		}
-
-		/* At this point, the session and channel exist on the tracer */
-
-		switch (event_type) {
-		case LTTNG_EVENT_ALL:
-		case LTTNG_EVENT_TRACEPOINT:
-			ret = event_ust_enable_all_tracepoints(usess, uchan, filter);
-			if (ret != LTTNG_OK) {
-				goto error;
-			}
-			break;
-		default:
-			ret = LTTNG_ERR_UST_ENABLE_FAIL;
-			goto error;
-		}
-
-		/* Manage return value */
-		if (ret != LTTNG_OK) {
-			goto error;
-		}
-
-		break;
-	}
-#if 0
-	case LTTNG_DOMAIN_UST_EXEC_NAME:
-	case LTTNG_DOMAIN_UST_PID:
-	case LTTNG_DOMAIN_UST_PID_FOLLOW_CHILDREN:
-#endif
-	default:
-		ret = LTTNG_ERR_UND;
-		goto error;
-	}
+	default:
+		ret = LTTNG_ERR_UND;
+		goto error;
+	}
 
 	ret = LTTNG_OK;
 
@@ -1446,6 +1765,15 @@ ssize_t cmd_list_tracepoints(int domain, struct lttng_event **events)
 			goto error;
 		}
 		break;
+	case LTTNG_DOMAIN_LOG4J:
+	case LTTNG_DOMAIN_JUL:
+	case LTTNG_DOMAIN_PYTHON:
+		nb_events = agent_list_events(events, domain);
+		if (nb_events < 0) {
+			ret = LTTNG_ERR_UST_LIST_FAIL;
+			goto error;
+		}
+		break;
 	default:
 		ret = LTTNG_ERR_UND;
 		goto error;
@@ -1488,12 +1816,18 @@ error:
 	return -ret;
 }
 
+ssize_t cmd_list_syscalls(struct lttng_event **events)
+{
+	return syscall_table_list(events);
+}
+
 /*
  * Command LTTNG_START_TRACE processed by the client thread.
  */
 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;
 
@@ -1503,13 +1837,26 @@ 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) {
+		nb_chan += lttng_ht_get_count(usess->domain_global.channels);
+	}
+	if (ksession) {
+		nb_chan += ksession->channel_count;
+	}
+	if (!nb_chan) {
+		ret = LTTNG_ERR_NO_CHANNEL;
+		goto error;
+	}
 
 	/* Kernel tracing */
 	if (ksession != NULL) {
@@ -1521,7 +1868,11 @@ 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) {
@@ -1530,7 +1881,9 @@ 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;
 
@@ -1554,15 +1907,14 @@ 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 */
@@ -1589,11 +1941,15 @@ 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) {
@@ -1602,6 +1958,8 @@ int cmd_stop_trace(struct ltt_session *session)
 		}
 	}
 
+	/* Flag inactive after a successful stop. */
+	session->active = 0;
 	ret = LTTNG_OK;
 
 error:
@@ -1623,8 +1981,8 @@ int cmd_set_consumer_uri(int domain, struct ltt_session *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;
 	}
@@ -1664,6 +2022,17 @@ int cmd_set_consumer_uri(int domain, struct ltt_session *session,
 		}
 	}
 
+	/*
+	 * 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;
+	} else if (usess) {
+		usess->output_traces = 1;
+	}
+
 	/* All good! */
 	ret = LTTNG_OK;
 
@@ -1675,18 +2044,13 @@ error:
  * Command LTTNG_CREATE_SESSION processed by the client thread.
  */
 int cmd_create_session_uri(char *name, struct lttng_uri *uris,
-		size_t nb_uri, lttng_sock_cred *creds)
+		size_t nb_uri, lttng_sock_cred *creds, unsigned int live_timer)
 {
 	int ret;
 	struct ltt_session *session;
 
 	assert(name);
-
-	/* No URIs is not possible. */
-	if (uris == NULL) {
-		ret = LTTNG_ERR_SESSION_FAIL;
-		goto session_error;
-	}
+	assert(creds);
 
 	/*
 	 * Verify if the session already exist
@@ -1718,6 +2082,7 @@ int cmd_create_session_uri(char *name, struct lttng_uri *uris,
 	session = session_find_by_name(name);
 	assert(session);
 
+	session->live_timer = live_timer;
 	/* Create default consumer output for the session not yet created. */
 	session->consumer = consumer_create_output(CONSUMER_DST_LOCAL);
 	if (session->consumer == NULL) {
@@ -1725,9 +2090,15 @@ int cmd_create_session_uri(char *name, struct lttng_uri *uris,
 		goto consumer_error;
 	}
 
-	ret = cmd_set_consumer_uri(0, session, nb_uri, uris);
-	if (ret != LTTNG_OK) {
-		goto consumer_error;
+	if (uris) {
+		ret = cmd_set_consumer_uri(0, session, nb_uri, uris);
+		if (ret != LTTNG_OK) {
+			goto consumer_error;
+		}
+		session->output_traces = 1;
+	} else {
+		session->output_traces = 0;
+		DBG2("Session %s created with no output", session->name);
 	}
 
 	session->consumer->enabled = 1;
@@ -1741,6 +2112,72 @@ find_error:
 	return ret;
 }
 
+/*
+ * Command LTTNG_CREATE_SESSION_SNAPSHOT processed by the client thread.
+ */
+int cmd_create_session_snapshot(char *name, struct lttng_uri *uris,
+		size_t nb_uri, lttng_sock_cred *creds)
+{
+	int ret;
+	struct ltt_session *session;
+	struct snapshot_output *new_output = NULL;
+
+	assert(name);
+	assert(creds);
+
+	/*
+	 * Create session in no output mode with URIs set to NULL. The uris we've
+	 * received are for a default snapshot output if one.
+	 */
+	ret = cmd_create_session_uri(name, NULL, 0, creds, -1);
+	if (ret != LTTNG_OK) {
+		goto error;
+	}
+
+	/* Get the newly created session pointer back. This should NEVER fail. */
+	session = session_find_by_name(name);
+	assert(session);
+
+	/* Flag session for snapshot mode. */
+	session->snapshot_mode = 1;
+
+	/* Skip snapshot output creation if no URI is given. */
+	if (nb_uri == 0) {
+		goto end;
+	}
+
+	new_output = snapshot_output_alloc();
+	if (!new_output) {
+		ret = LTTNG_ERR_NOMEM;
+		goto error_snapshot_alloc;
+	}
+
+	ret = snapshot_output_init_with_uri(DEFAULT_SNAPSHOT_MAX_SIZE, NULL,
+			uris, nb_uri, session->consumer, new_output, &session->snapshot);
+	if (ret < 0) {
+		if (ret == -ENOMEM) {
+			ret = LTTNG_ERR_NOMEM;
+		} else {
+			ret = LTTNG_ERR_INVALID;
+		}
+		goto error_snapshot;
+	}
+
+	rcu_read_lock();
+	snapshot_add_output(&session->snapshot, new_output);
+	rcu_read_unlock();
+
+end:
+	return LTTNG_OK;
+
+error_snapshot:
+	snapshot_output_destroy(new_output);
+error_snapshot_alloc:
+	session_destroy(session);
+error:
+	return ret;
+}
+
 /*
  * Command LTTNG_DESTROY_SESSION processed by the client thread.
  */
@@ -1800,7 +2237,14 @@ 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;
@@ -1812,7 +2256,14 @@ 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;
@@ -1862,13 +2313,15 @@ int cmd_register_consumer(struct ltt_session *session, int domain,
 			ret = LTTNG_ERR_CONNECT_FAIL;
 			goto error;
 		}
+		cdata->cmd_sock = sock;
 
-		socket = consumer_allocate_socket(sock);
+		socket = consumer_allocate_socket(&cdata->cmd_sock);
 		if (socket == NULL) {
 			ret = close(sock);
 			if (ret < 0) {
 				PERROR("close register consumer");
 			}
+			cdata->cmd_sock = -1;
 			ret = LTTNG_ERR_FATAL;
 			goto error;
 		}
@@ -1915,6 +2368,8 @@ ssize_t cmd_list_domains(struct ltt_session *session,
 {
 	int ret, index = 0;
 	ssize_t nb_dom = 0;
+	struct agent *agt;
+	struct lttng_ht_iter iter;
 
 	if (session->kernel_session != NULL) {
 		DBG3("Listing domains found kernel domain");
@@ -1924,6 +2379,13 @@ ssize_t cmd_list_domains(struct ltt_session *session,
 	if (session->ust_session != NULL) {
 		DBG3("Listing domains found UST global domain");
 		nb_dom++;
+
+		cds_lfht_for_each_entry(session->ust_session->agents->ht, &iter.iter,
+				agt, node.node) {
+			if (agt->being_used) {
+				nb_dom++;
+			}
+		}
 	}
 
 	*domains = zmalloc(nb_dom * sizeof(struct lttng_domain));
@@ -1941,6 +2403,15 @@ 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++;
+
+		cds_lfht_for_each_entry(session->ust_session->agents->ht, &iter.iter,
+				agt, node.node) {
+			if (agt->being_used) {
+				(*domains)[index].type = agt->domain;
+				(*domains)[index].buf_type = session->ust_session->buffer_type;
+				index++;
+			}
+		}
 	}
 
 	return nb_dom;
@@ -2031,6 +2502,19 @@ ssize_t cmd_list_events(int domain, struct ltt_session *session,
 		}
 		break;
 	}
+	case LTTNG_DOMAIN_LOG4J:
+	case LTTNG_DOMAIN_JUL:
+	case LTTNG_DOMAIN_PYTHON:
+		if (session->ust_session) {
+			struct lttng_ht_iter iter;
+			struct agent *agt;
+
+			cds_lfht_for_each_entry(session->ust_session->agents->ht,
+					&iter.iter, agt, node.node) {
+				nb_event = list_lttng_agent_events(agt, events);
+			}
+		}
+		break;
 	default:
 		ret = LTTNG_ERR_UND;
 		goto error;
@@ -2091,14 +2575,16 @@ 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++;
 	}
 }
 
 /*
  * Command LTTNG_DATA_PENDING returning 0 if the data is NOT pending meaning
- * ready for trace analysis (or anykind of reader) or else 1 for pending data.
+ * ready for trace analysis (or any kind of reader) or else 1 for pending data.
  */
 int cmd_data_pending(struct ltt_session *session)
 {
@@ -2109,9 +2595,24 @@ 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) {
@@ -2137,6 +2638,630 @@ error:
 	return ret;
 }
 
+/*
+ * Command LTTNG_SNAPSHOT_ADD_OUTPUT from the lttng ctl library.
+ *
+ * Return LTTNG_OK on success or else a LTTNG_ERR code.
+ */
+int cmd_snapshot_add_output(struct ltt_session *session,
+		struct lttng_snapshot_output *output, uint32_t *id)
+{
+	int ret;
+	struct snapshot_output *new_output;
+
+	assert(session);
+	assert(output);
+
+	DBG("Cmd snapshot add output for session %s", session->name);
+
+	/*
+	 * Permission denied to create an output if the session is not
+	 * set in no output mode.
+	 */
+	if (session->output_traces) {
+		ret = LTTNG_ERR_EPERM;
+		goto error;
+	}
+
+	/* Only one output is allowed until we have the "tee" feature. */
+	if (session->snapshot.nb_output == 1) {
+		ret = LTTNG_ERR_SNAPSHOT_OUTPUT_EXIST;
+		goto error;
+	}
+
+	new_output = snapshot_output_alloc();
+	if (!new_output) {
+		ret = LTTNG_ERR_NOMEM;
+		goto error;
+	}
+
+	ret = snapshot_output_init(output->max_size, output->name,
+			output->ctrl_url, output->data_url, session->consumer, new_output,
+			&session->snapshot);
+	if (ret < 0) {
+		if (ret == -ENOMEM) {
+			ret = LTTNG_ERR_NOMEM;
+		} else {
+			ret = LTTNG_ERR_INVALID;
+		}
+		goto free_error;
+	}
+
+	rcu_read_lock();
+	snapshot_add_output(&session->snapshot, new_output);
+	if (id) {
+		*id = new_output->id;
+	}
+	rcu_read_unlock();
+
+	return LTTNG_OK;
+
+free_error:
+	snapshot_output_destroy(new_output);
+error:
+	return ret;
+}
+
+/*
+ * Command LTTNG_SNAPSHOT_DEL_OUTPUT from lib lttng ctl.
+ *
+ * Return LTTNG_OK on success or else a LTTNG_ERR code.
+ */
+int cmd_snapshot_del_output(struct ltt_session *session,
+		struct lttng_snapshot_output *output)
+{
+	int ret;
+	struct snapshot_output *sout = NULL;
+
+	assert(session);
+	assert(output);
+
+	rcu_read_lock();
+
+	/*
+	 * Permission denied to create an output if the session is not
+	 * set in no output mode.
+	 */
+	if (session->output_traces) {
+		ret = LTTNG_ERR_EPERM;
+		goto error;
+	}
+
+	if (output->id) {
+		DBG("Cmd snapshot del output id %" PRIu32 " for session %s", output->id,
+				session->name);
+		sout = snapshot_find_output_by_id(output->id, &session->snapshot);
+	} else if (*output->name != '\0') {
+		DBG("Cmd snapshot del output name %s for session %s", output->name,
+				session->name);
+		sout = snapshot_find_output_by_name(output->name, &session->snapshot);
+	}
+	if (!sout) {
+		ret = LTTNG_ERR_INVALID;
+		goto error;
+	}
+
+	snapshot_delete_output(&session->snapshot, sout);
+	snapshot_output_destroy(sout);
+	ret = LTTNG_OK;
+
+error:
+	rcu_read_unlock();
+	return ret;
+}
+
+/*
+ * Command LTTNG_SNAPSHOT_LIST_OUTPUT from lib lttng ctl.
+ *
+ * If no output is available, outputs is untouched and 0 is returned.
+ *
+ * Return the size of the newly allocated outputs or a negative LTTNG_ERR code.
+ */
+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_ht_iter iter;
+	struct snapshot_output *output;
+
+	assert(session);
+	assert(outputs);
+
+	DBG("Cmd snapshot list outputs for session %s", session->name);
+
+	/*
+	 * Permission denied to create an output if the session is not
+	 * set in no output mode.
+	 */
+	if (session->output_traces) {
+		ret = LTTNG_ERR_EPERM;
+		goto error;
+	}
+
+	if (session->snapshot.nb_output == 0) {
+		ret = 0;
+		goto error;
+	}
+
+	list = zmalloc(session->snapshot.nb_output * sizeof(*list));
+	if (!list) {
+		ret = LTTNG_ERR_NOMEM;
+		goto error;
+	}
+
+	/* Copy list from session to the new list object. */
+	cds_lfht_for_each_entry(session->snapshot.output_ht->ht, &iter.iter,
+			output, node.node) {
+		assert(output->consumer);
+		list[idx].id = output->id;
+		list[idx].max_size = output->max_size;
+		strncpy(list[idx].name, output->name, sizeof(list[idx].name));
+		if (output->consumer->type == CONSUMER_DST_LOCAL) {
+			strncpy(list[idx].ctrl_url, output->consumer->dst.trace_path,
+					sizeof(list[idx].ctrl_url));
+		} else {
+			/* Control URI. */
+			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;
+			}
+
+			/* 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;
+			}
+		}
+		idx++;
+	}
+
+	*outputs = list;
+	return session->snapshot.nb_output;
+
+free_error:
+	free(list);
+error:
+	return -ret;
+}
+
+/*
+ * Send relayd sockets from snapshot output to consumer. Ignore request if the
+ * snapshot output is *not* set with a remote destination.
+ *
+ * Return 0 on success or a LTTNG_ERR code.
+ */
+static int set_relayd_for_snapshot(struct consumer_output *consumer,
+		struct snapshot_output *snap_output, struct ltt_session *session)
+{
+	int ret = LTTNG_OK;
+	struct lttng_ht_iter iter;
+	struct consumer_socket *socket;
+
+	assert(consumer);
+	assert(snap_output);
+	assert(session);
+
+	DBG2("Set relayd object from snapshot output");
+
+	/* Ignore if snapshot consumer output is not network. */
+	if (snap_output->consumer->type != CONSUMER_DST_NET) {
+		goto error;
+	}
+
+	/*
+	 * For each consumer socket, create and send the relayd object of the
+	 * snapshot output.
+	 */
+	rcu_read_lock();
+	cds_lfht_for_each_entry(snap_output->consumer->socks->ht, &iter.iter,
+			socket, node.node) {
+		ret = send_consumer_relayd_sockets(0, session->id,
+				snap_output->consumer, socket,
+				session->name, session->hostname,
+				session->live_timer);
+		if (ret != LTTNG_OK) {
+			rcu_read_unlock();
+			goto error;
+		}
+	}
+	rcu_read_unlock();
+
+error:
+	return ret;
+}
+
+/*
+ * Record a kernel snapshot.
+ *
+ * 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, uint64_t max_stream_size)
+{
+	int ret;
+
+	assert(ksess);
+	assert(output);
+	assert(session);
+
+	/* Get the datetime for the snapshot output directory. */
+	ret = utils_get_current_time_str("%Y%m%d-%H%M%S", output->datetime,
+			sizeof(output->datetime));
+	if (!ret) {
+		ret = LTTNG_ERR_INVALID;
+		goto error;
+	}
+
+	/*
+	 * Copy kernel session sockets so we can communicate with the right
+	 * consumer for the snapshot record command.
+	 */
+	ret = consumer_copy_sockets(output->consumer, ksess->consumer);
+	if (ret < 0) {
+		ret = LTTNG_ERR_NOMEM;
+		goto error;
+	}
+
+	ret = set_relayd_for_snapshot(ksess->consumer, output, session);
+	if (ret != LTTNG_OK) {
+		goto error_snapshot;
+	}
+
+	ret = kernel_snapshot_record(ksess, output, wait, max_stream_size);
+	if (ret != LTTNG_OK) {
+		goto error_snapshot;
+	}
+
+	ret = LTTNG_OK;
+
+error_snapshot:
+	/* Clean up copied sockets so this output can use some other later on. */
+	consumer_destroy_output_sockets(output->consumer);
+error:
+	return ret;
+}
+
+/*
+ * Record a UST snapshot.
+ *
+ * Return 0 on success or a LTTNG_ERR error code.
+ */
+static int record_ust_snapshot(struct ltt_ust_session *usess,
+		struct snapshot_output *output, struct ltt_session *session,
+		int wait, uint64_t max_stream_size)
+{
+	int ret;
+
+	assert(usess);
+	assert(output);
+	assert(session);
+
+	/* Get the datetime for the snapshot output directory. */
+	ret = utils_get_current_time_str("%Y%m%d-%H%M%S", output->datetime,
+			sizeof(output->datetime));
+	if (!ret) {
+		ret = LTTNG_ERR_INVALID;
+		goto error;
+	}
+
+	/*
+	 * Copy UST session sockets so we can communicate with the right
+	 * consumer for the snapshot record command.
+	 */
+	ret = consumer_copy_sockets(output->consumer, usess->consumer);
+	if (ret < 0) {
+		ret = LTTNG_ERR_NOMEM;
+		goto error;
+	}
+
+	ret = set_relayd_for_snapshot(usess->consumer, output, session);
+	if (ret != LTTNG_OK) {
+		goto error_snapshot;
+	}
+
+	ret = ust_app_snapshot_record(usess, output, wait, max_stream_size);
+	if (ret < 0) {
+		switch (-ret) {
+		case EINVAL:
+			ret = LTTNG_ERR_INVALID;
+			break;
+		case ENODATA:
+			ret = LTTNG_ERR_SNAPSHOT_NODATA;
+			break;
+		default:
+			ret = LTTNG_ERR_SNAPSHOT_FAIL;
+			break;
+		}
+		goto error_snapshot;
+	}
+
+	ret = LTTNG_OK;
+
+error_snapshot:
+	/* Clean up copied sockets so this output can use some other later on. */
+	consumer_destroy_output_sockets(output->consumer);
+error:
+	return ret;
+}
+
+/*
+ * Return the biggest subbuffer size of all channels in the given session.
+ */
+static uint64_t get_session_max_subbuf_size(struct ltt_session *session)
+{
+	uint64_t max_size = 0;
+
+	assert(session);
+
+	if (session->kernel_session) {
+		struct ltt_kernel_channel *chan;
+		struct ltt_kernel_session *ksess = session->kernel_session;
+
+		/*
+		 * For each channel, add to the max size the size of each subbuffer
+		 * multiplied by their sized.
+		 */
+		cds_list_for_each_entry(chan, &ksess->channel_list.head, list) {
+			if (chan->channel->attr.subbuf_size > max_size) {
+				max_size = chan->channel->attr.subbuf_size;
+			}
+		}
+	}
+
+	if (session->ust_session) {
+		struct lttng_ht_iter iter;
+		struct ltt_ust_channel *uchan;
+		struct ltt_ust_session *usess = session->ust_session;
+
+		cds_lfht_for_each_entry(usess->domain_global.channels->ht, &iter.iter,
+				uchan, node.node) {
+			if (uchan->attr.subbuf_size > max_size) {
+				max_size = uchan->attr.subbuf_size;
+			}
+		}
+	}
+
+	return max_size;
+}
+
+/*
+ * Returns the total number of streams for a session or a negative value
+ * on error.
+ */
+static unsigned int get_session_nb_streams(struct ltt_session *session)
+{
+	unsigned int total_streams = 0;
+
+	if (session->kernel_session) {
+		struct ltt_kernel_session *ksess = session->kernel_session;
+
+		total_streams += ksess->stream_count_global;
+	}
+
+	if (session->ust_session) {
+		struct ltt_ust_session *usess = session->ust_session;
+
+		total_streams += ust_app_get_nb_stream(usess);
+	}
+
+	return total_streams;
+}
+
+/*
+ * Command LTTNG_SNAPSHOT_RECORD from lib lttng ctl.
+ *
+ * The wait parameter is ignored so this call always wait for the snapshot to
+ * complete before returning.
+ *
+ * Return LTTNG_OK on success or else a LTTNG_ERR code.
+ */
+int cmd_snapshot_record(struct ltt_session *session,
+		struct lttng_snapshot_output *output, int wait)
+{
+	int ret = LTTNG_OK;
+	unsigned int use_tmp_output = 0;
+	struct snapshot_output tmp_output;
+	unsigned int nb_streams, snapshot_success = 0;
+	uint64_t session_max_size = 0, max_stream_size = 0;
+
+	assert(session);
+	assert(output);
+
+	DBG("Cmd snapshot record for session %s", session->name);
+
+	/*
+	 * Permission denied to create an output if the session is not
+	 * set in no output mode.
+	 */
+	if (session->output_traces) {
+		ret = LTTNG_ERR_EPERM;
+		goto error;
+	}
+
+	/* The session needs to be started at least once. */
+	if (!session->has_been_started) {
+		ret = LTTNG_ERR_START_SESSION_ONCE;
+		goto error;
+	}
+
+	/* Use temporary output for the session. */
+	if (*output->ctrl_url != '\0') {
+		ret = snapshot_output_init(output->max_size, output->name,
+				output->ctrl_url, output->data_url, session->consumer,
+				&tmp_output, NULL);
+		if (ret < 0) {
+			if (ret == -ENOMEM) {
+				ret = LTTNG_ERR_NOMEM;
+			} else {
+				ret = LTTNG_ERR_INVALID;
+			}
+			goto error;
+		}
+		/* Use the global session count for the temporary snapshot. */
+		tmp_output.nb_snapshot = session->snapshot.nb_snapshot;
+		use_tmp_output = 1;
+	}
+
+	/*
+	 * Get the session maximum size for a snapshot meaning it will compute the
+	 * size of all streams from all domain.
+	 */
+	max_stream_size = get_session_max_subbuf_size(session);
+
+	nb_streams = get_session_nb_streams(session);
+	if (nb_streams) {
+		/*
+		 * The maximum size of the snapshot is the number of streams multiplied
+		 * by the biggest subbuf size of all channels in a session which is the
+		 * maximum stream size available for each stream. The session max size
+		 * is now checked against the snapshot max size value given by the user
+		 * and if lower, an error is returned.
+		 */
+		session_max_size = max_stream_size * nb_streams;
+	}
+
+	DBG3("Snapshot max size is %" PRIu64 " for max stream size of %" PRIu64,
+			session_max_size, max_stream_size);
+
+	/*
+	 * If we use a temporary output, check right away if the max size fits else
+	 * for each output the max size will be checked.
+	 */
+	if (use_tmp_output &&
+			(tmp_output.max_size != 0 &&
+			tmp_output.max_size < session_max_size)) {
+		ret = LTTNG_ERR_MAX_SIZE_INVALID;
+		goto error;
+	}
+
+	if (session->kernel_session) {
+		struct ltt_kernel_session *ksess = session->kernel_session;
+
+		if (use_tmp_output) {
+			ret = record_kernel_snapshot(ksess, &tmp_output, session,
+					wait, max_stream_size);
+			if (ret != LTTNG_OK) {
+				goto error;
+			}
+			snapshot_success = 1;
+		} else {
+			struct snapshot_output *sout;
+			struct lttng_ht_iter iter;
+
+			rcu_read_lock();
+			cds_lfht_for_each_entry(session->snapshot.output_ht->ht,
+					&iter.iter, sout, node.node) {
+				/*
+				 * Make a local copy of the output and assign the possible
+				 * temporary value given by the caller.
+				 */
+				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;
+				}
+
+				if (tmp_output.max_size != 0 &&
+						tmp_output.max_size < session_max_size) {
+					rcu_read_unlock();
+					ret = LTTNG_ERR_MAX_SIZE_INVALID;
+					goto error;
+				}
+
+				/* Use temporary name. */
+				if (*output->name != '\0') {
+					strncpy(tmp_output.name, output->name,
+							sizeof(tmp_output.name));
+				}
+
+				tmp_output.nb_snapshot = session->snapshot.nb_snapshot;
+
+				ret = record_kernel_snapshot(ksess, &tmp_output,
+						session, wait, max_stream_size);
+				if (ret != LTTNG_OK) {
+					rcu_read_unlock();
+					goto error;
+				}
+				snapshot_success = 1;
+			}
+			rcu_read_unlock();
+		}
+	}
+
+	if (session->ust_session) {
+		struct ltt_ust_session *usess = session->ust_session;
+
+		if (use_tmp_output) {
+			ret = record_ust_snapshot(usess, &tmp_output, session,
+					wait, max_stream_size);
+			if (ret != LTTNG_OK) {
+				goto error;
+			}
+			snapshot_success = 1;
+		} else {
+			struct snapshot_output *sout;
+			struct lttng_ht_iter iter;
+
+			rcu_read_lock();
+			cds_lfht_for_each_entry(session->snapshot.output_ht->ht,
+					&iter.iter, sout, node.node) {
+				/*
+				 * Make a local copy of the output and assign the possible
+				 * temporary value given by the caller.
+				 */
+				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;
+				}
+
+				if (tmp_output.max_size != 0 &&
+						tmp_output.max_size < session_max_size) {
+					rcu_read_unlock();
+					ret = LTTNG_ERR_MAX_SIZE_INVALID;
+					goto error;
+				}
+
+				/* Use temporary name. */
+				if (*output->name != '\0') {
+					strncpy(tmp_output.name, output->name,
+							sizeof(tmp_output.name));
+				}
+
+				tmp_output.nb_snapshot = session->snapshot.nb_snapshot;
+
+				ret = record_ust_snapshot(usess, &tmp_output, session,
+						wait, max_stream_size);
+				if (ret != LTTNG_OK) {
+					rcu_read_unlock();
+					goto error;
+				}
+				snapshot_success = 1;
+			}
+			rcu_read_unlock();
+		}
+	}
+
+	if (snapshot_success) {
+		session->snapshot.nb_snapshot++;
+	} else {
+		ret = LTTNG_ERR_SNAPSHOT_FAIL;
+	}
+
+error:
+	return ret;
+}
+
 /*
  * Init command subsystem.
  */