X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Flib%2Flttng-ctl%2Flttng-ctl.c;h=f50ca306145f9b30e28b24f3bfea500f9181f1f4;hp=4332881c6eb7a41f538189a3dd3dcc41aed0ae30;hb=6a0838b7bdcc04613f703dc6580f81beb849fa64;hpb=d7ba13889c8692b14f99238ddf2721ed78df89d2

diff --git a/src/lib/lttng-ctl/lttng-ctl.c b/src/lib/lttng-ctl/lttng-ctl.c
index 4332881c6..f50ca3061 100644
--- a/src/lib/lttng-ctl/lttng-ctl.c
+++ b/src/lib/lttng-ctl/lttng-ctl.c
@@ -1,9 +1,10 @@
 /*
- * liblttngctl.c
+ * lttng-ctl.c
  *
  * Linux Trace Toolkit Control Library
  *
  * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
+ * Copyright (C) 2016 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
  *
  * This library is free software; you can redistribute it and/or modify it
  * under the terms of the GNU Lesser General Public License, version 2.1 only,
@@ -19,7 +20,6 @@
  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
-#define _GNU_SOURCE
 #define _LGPL_SOURCE
 #include <assert.h>
 #include <grp.h>
@@ -30,12 +30,21 @@
 #include <unistd.h>
 
 #include <common/common.h>
+#include <common/compat/string.h>
 #include <common/defaults.h>
 #include <common/sessiond-comm/sessiond-comm.h>
 #include <common/uri.h>
 #include <common/utils.h>
+#include <common/dynamic-buffer.h>
 #include <lttng/lttng.h>
 #include <lttng/health-internal.h>
+#include <lttng/trigger/trigger-internal.h>
+#include <lttng/endpoint.h>
+#include <lttng/channel-internal.h>
+#include <lttng/event-internal.h>
+#include <lttng/userspace-probe-internal.h>
+#include <lttng/session-internal.h>
+#include <lttng/session-descriptor-internal.h>
 
 #include "filter/filter-ast.h"
 #include "filter/filter-parser.h"
@@ -150,7 +159,7 @@ end:
  * On success, returns the number of bytes sent (>=0)
  * On error, returns -1
  */
-static int send_session_varlen(void *data, size_t len)
+static int send_session_varlen(const void *data, size_t len)
 {
 	int ret;
 
@@ -173,6 +182,35 @@ end:
 	return ret;
 }
 
+/*
+ * Send file descriptors to the session daemon.
+ *
+ * On success, returns the number of bytes sent (>=0)
+ * On error, returns -1
+ */
+static int send_session_fds(const int *fds, size_t nb_fd)
+{
+	int ret;
+
+	if (!connected) {
+		ret = -LTTNG_ERR_NO_SESSIOND;
+		goto end;
+	}
+
+	if (!fds || !nb_fd) {
+		ret = 0;
+		goto end;
+	}
+
+	ret = lttcomm_send_fds_unix_sock(sessiond_socket, fds, nb_fd);
+	if (ret < 0) {
+		ret = -LTTNG_ERR_FATAL;
+	}
+
+end:
+	return ret;
+}
+
 /*
  * Receive data from the sessiond socket.
  *
@@ -198,22 +236,20 @@ end:
 }
 
 /*
- *  Check if we are in the specified group.
+ * Check if we are in the specified group.
  *
- *  If yes return 1, else return -1.
+ * If yes return 1, else return -1.
  */
 LTTNG_HIDDEN
 int lttng_check_tracing_group(void)
 {
-	struct group *grp_tracing;	/* no free(). See getgrnam(3) */
-	gid_t *grp_list;
+	gid_t *grp_list, tracing_gid;
 	int grp_list_size, grp_id, i;
 	int ret = -1;
 	const char *grp_name = tracing_group;
 
 	/* Get GID of group 'tracing' */
-	grp_tracing = getgrnam(grp_name);
-	if (!grp_tracing) {
+	if (utils_get_group_id(grp_name, false, &tracing_gid)) {
 		/* If grp_tracing is NULL, the group does not exist. */
 		goto end;
 	}
@@ -238,7 +274,7 @@ int lttng_check_tracing_group(void)
 	}
 
 	for (i = 0; i < grp_list_size; i++) {
-		if (grp_list[i] == grp_tracing->gr_gid) {
+		if (grp_list[i] == tracing_gid) {
 			ret = 1;
 			break;
 		}
@@ -251,6 +287,50 @@ end:
 	return ret;
 }
 
+static int check_enough_available_memory(size_t num_bytes_requested_per_cpu)
+{
+	int ret;
+	long num_cpu;
+	size_t best_mem_info;
+	size_t num_bytes_requested_total;
+
+	/*
+	 * Get the number of CPU currently online to compute the amount of
+	 * memory needed to create a buffer for every CPU.
+	 */
+	num_cpu = sysconf(_SC_NPROCESSORS_ONLN);
+	if (num_cpu == -1) {
+		goto error;
+	}
+
+	num_bytes_requested_total = num_bytes_requested_per_cpu * num_cpu;
+
+	/*
+	 * Try to get the `MemAvail` field of `/proc/meminfo`. This is the most
+	 * reliable estimate we can get but it is only exposed by the kernel
+	 * since 3.14. (See Linux kernel commit:
+	 * 34e431b0ae398fc54ea69ff85ec700722c9da773)
+	 */
+	ret = utils_get_memory_available(&best_mem_info);
+	if (ret >= 0) {
+		goto success;
+	}
+
+	/*
+	 * As a backup plan, use `MemTotal` field of `/proc/meminfo`. This
+	 * is a sanity check for obvious user error.
+	 */
+	ret = utils_get_memory_total(&best_mem_info);
+	if (ret >= 0) {
+		goto success;
+	}
+
+error:
+	return -1;
+success:
+	return best_mem_info >= num_bytes_requested_total;
+}
+
 /*
  * Try connect to session daemon with sock_path.
  *
@@ -269,7 +349,7 @@ static int try_connect_sessiond(const char *sock_path)
 
 	ret = lttcomm_connect_unix_sock(sock_path);
 	if (ret < 0) {
-		/* Not alive */
+		/* Not alive. */
 		goto error;
 	}
 
@@ -293,7 +373,7 @@ error:
  */
 static int set_session_daemon_path(void)
 {
-	int in_tgroup = 0;	/* In tracing group */
+	int in_tgroup = 0;	/* In tracing group. */
 	uid_t uid;
 
 	uid = getuid();
@@ -312,7 +392,7 @@ static int set_session_daemon_path(void)
 		int ret;
 
 		if (in_tgroup) {
-			/* Tracing group */
+			/* Tracing group. */
 			ret = try_connect_sessiond(sessiond_sock_path);
 			if (ret >= 0) {
 				goto end;
@@ -322,8 +402,10 @@ static int set_session_daemon_path(void)
 		/* ...or not in tracing group (and not root), default */
 
 		/*
-		 * With GNU C <  2.1, snprintf returns -1 if the target buffer is too small;
-		 * With GNU C >= 2.1, snprintf returns the required size (excluding closing null)
+		 * With GNU C <  2.1, snprintf returns -1 if the target buffer
+		 * is too small;
+		 * With GNU C >= 2.1, snprintf returns the required size
+		 * (excluding closing null)
 		 */
 		ret = snprintf(sessiond_sock_path, sizeof(sessiond_sock_path),
 				DEFAULT_HOME_CLIENT_UNIX_SOCK, utils_get_home_dir());
@@ -339,9 +421,9 @@ error:
 }
 
 /*
- *  Connect to the LTTng session daemon.
+ * Connect to the LTTng session daemon.
  *
- *  On success, return 0. On error, return -1.
+ * On success, return 0. On error, return -1.
  */
 static int connect_sessiond(void)
 {
@@ -357,7 +439,7 @@ static int connect_sessiond(void)
 		goto error;
 	}
 
-	/* Connect to the sesssion daemon */
+	/* Connect to the sesssion daemon. */
 	ret = lttcomm_connect_unix_sock(sessiond_sock_path);
 	if (ret < 0) {
 		goto error;
@@ -374,6 +456,7 @@ error:
 
 /*
  *  Clean disconnect from the session daemon.
+ *
  *  On success, return 0. On error, return -1.
  */
 static int disconnect_sessiond(void)
@@ -389,19 +472,69 @@ static int disconnect_sessiond(void)
 	return ret;
 }
 
+static int recv_sessiond_optional_data(size_t len, void **user_buf,
+	size_t *user_len)
+{
+	int ret = 0;
+	void *buf = NULL;
+
+	if (len) {
+		if (!user_len) {
+			ret = -LTTNG_ERR_INVALID;
+			goto end;
+		}
+
+		buf = zmalloc(len);
+		if (!buf) {
+			ret = -ENOMEM;
+			goto end;
+		}
+
+		ret = recv_data_sessiond(buf, len);
+		if (ret < 0) {
+			goto end;
+		}
+
+		if (!user_buf) {
+			ret = -LTTNG_ERR_INVALID;
+			goto end;
+		}
+
+		/* Move ownership of command header buffer to user. */
+		*user_buf = buf;
+		buf = NULL;
+		*user_len = len;
+	} else {
+		/* No command header. */
+		if (user_len) {
+			*user_len = 0;
+		}
+
+		if (user_buf) {
+			*user_buf = NULL;
+		}
+	}
+
+end:
+	free(buf);
+	return ret;
+}
+
 /*
  * Ask the session daemon a specific command and put the data into buf.
- * Takes extra var. len. data as input to send to the session daemon.
+ * Takes extra var. len. data and file descriptors as input to send to the
+ * session daemon.
  *
  * Return size of data (only payload, not header) or a negative error code.
  */
 LTTNG_HIDDEN
-int lttng_ctl_ask_sessiond_varlen(struct lttcomm_session_msg *lsm,
-		void *vardata, size_t varlen, void **buf)
+int lttng_ctl_ask_sessiond_fds_varlen(struct lttcomm_session_msg *lsm,
+		const int *fds, size_t nb_fd, const void *vardata,
+		size_t vardata_len, void **user_payload_buf,
+		void **user_cmd_header_buf, size_t *user_cmd_header_len)
 {
 	int ret;
-	size_t size;
-	void *data = NULL;
+	size_t payload_len;
 	struct lttcomm_lttng_msg llm;
 
 	ret = connect_sessiond();
@@ -417,7 +550,14 @@ int lttng_ctl_ask_sessiond_varlen(struct lttcomm_session_msg *lsm,
 		goto end;
 	}
 	/* Send var len data */
-	ret = send_session_varlen(vardata, varlen);
+	ret = send_session_varlen(vardata, vardata_len);
+	if (ret < 0) {
+		/* Ret value is a valid lttng error code. */
+		goto end;
+	}
+
+	/* Send fds */
+	ret = send_session_fds(fds, nb_fd);
 	if (ret < 0) {
 		/* Ret value is a valid lttng error code. */
 		goto end;
@@ -436,41 +576,21 @@ int lttng_ctl_ask_sessiond_varlen(struct lttcomm_session_msg *lsm,
 		goto end;
 	}
 
-	size = llm.data_size;
-	if (size == 0) {
-		/* If client free with size 0 */
-		if (buf != NULL) {
-			*buf = NULL;
-		}
-		ret = 0;
-		goto end;
-	}
-
-	data = zmalloc(size);
-	if (!data) {
-		ret = -ENOMEM;
-		goto end;
-	}
-
-	/* Get payload data */
-	ret = recv_data_sessiond(data, size);
+	/* Get command header from data transmission */
+	ret = recv_sessiond_optional_data(llm.cmd_header_size,
+		user_cmd_header_buf, user_cmd_header_len);
 	if (ret < 0) {
-		free(data);
 		goto end;
 	}
 
-	/*
-	 * Extra protection not to dereference a NULL pointer. If buf is NULL at
-	 * this point, an error is returned and data is freed.
-	 */
-	if (buf == NULL) {
-		ret = -LTTNG_ERR_INVALID;
-		free(data);
+	/* Get payload from data transmission */
+	ret = recv_sessiond_optional_data(llm.data_size, user_payload_buf,
+		&payload_len);
+	if (ret < 0) {
 		goto end;
 	}
 
-	*buf = data;
-	ret = size;
+	ret = llm.data_size;
 
 end:
 	disconnect_sessiond();
@@ -479,6 +599,7 @@ end:
 
 /*
  * Create lttng handle and return pointer.
+ *
  * The returned pointer will be NULL in case of malloc() error.
  */
 struct lttng_handle *lttng_create_handle(const char *session_name,
@@ -486,10 +607,6 @@ struct lttng_handle *lttng_create_handle(const char *session_name,
 {
 	struct lttng_handle *handle = NULL;
 
-	if (domain == NULL) {
-		goto end;
-	}
-
 	handle = zmalloc(sizeof(struct lttng_handle));
 	if (handle == NULL) {
 		PERROR("malloc handle");
@@ -500,8 +617,10 @@ struct lttng_handle *lttng_create_handle(const char *session_name,
 	lttng_ctl_copy_string(handle->session_name, session_name,
 			sizeof(handle->session_name));
 
-	/* Copy lttng domain */
-	lttng_ctl_copy_lttng_domain(&handle->domain, domain);
+	/* Copy lttng domain or leave initialized to 0. */
+	if (domain) {
+		lttng_ctl_copy_lttng_domain(&handle->domain, domain);
+	}
 
 end:
 	return handle;
@@ -517,6 +636,7 @@ void lttng_destroy_handle(struct lttng_handle *handle)
 
 /*
  * Register an outside consumer.
+ *
  * Returns size of returned session payload data or a negative error code.
  */
 int lttng_register_consumer(struct lttng_handle *handle,
@@ -534,14 +654,16 @@ int lttng_register_consumer(struct lttng_handle *handle,
 			sizeof(lsm.session.name));
 	lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
 
-	lttng_ctl_copy_string(lsm.u.reg.path, socket_path, sizeof(lsm.u.reg.path));
+	lttng_ctl_copy_string(lsm.u.reg.path, socket_path,
+			sizeof(lsm.u.reg.path));
 
 	return lttng_ctl_ask_sessiond(&lsm, NULL);
 }
 
 /*
- *  Start tracing for all traces of the session.
- *  Returns size of returned session payload data or a negative error code.
+ * Start tracing for all traces of the session.
+ *
+ * Returns size of returned session payload data or a negative error code.
  */
 int lttng_start_tracing(const char *session_name)
 {
@@ -597,8 +719,8 @@ static int _lttng_stop_tracing(const char *session_name, int wait)
 		}
 
 		/*
-		 * Data sleep time before retrying (in usec). Don't sleep if the call
-		 * returned value indicates availability.
+		 * Data sleep time before retrying (in usec). Don't sleep if the
+		 * call returned value indicates availability.
 		 */
 		if (data_ret) {
 			usleep(DEFAULT_DATA_AVAILABILITY_WAIT_TIME);
@@ -638,15 +760,18 @@ int lttng_add_context(struct lttng_handle *handle,
 		struct lttng_event_context *ctx, const char *event_name,
 		const char *channel_name)
 {
+	int ret;
+	size_t len = 0;
+	char *buf = NULL;
 	struct lttcomm_session_msg lsm;
 
-	/* Safety check. Both are mandatory */
+	/* Safety check. Both are mandatory. */
 	if (handle == NULL || ctx == NULL) {
-		return -LTTNG_ERR_INVALID;
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
 	}
 
 	memset(&lsm, 0, sizeof(lsm));
-
 	lsm.cmd_type = LTTNG_ADD_CONTEXT;
 
 	/* If no channel name, send empty string. */
@@ -659,20 +784,68 @@ int lttng_add_context(struct lttng_handle *handle,
 	}
 
 	lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
+	lttng_ctl_copy_string(lsm.session.name, handle->session_name,
+			sizeof(lsm.session.name));
+
+	if (ctx->ctx == LTTNG_EVENT_CONTEXT_APP_CONTEXT) {
+		size_t provider_len, ctx_len;
+		const char *provider_name = ctx->u.app_ctx.provider_name;
+		const char *ctx_name = ctx->u.app_ctx.ctx_name;
+
+		if (!provider_name || !ctx_name) {
+			ret = -LTTNG_ERR_INVALID;
+			goto end;
+		}
+
+		provider_len = strlen(provider_name);
+		if (provider_len == 0) {
+			ret = -LTTNG_ERR_INVALID;
+			goto end;
+		}
+		lsm.u.context.provider_name_len = provider_len;
+
+		ctx_len = strlen(ctx_name);
+		if (ctx_len == 0) {
+			ret = -LTTNG_ERR_INVALID;
+			goto end;
+		}
+		lsm.u.context.context_name_len = ctx_len;
+
+		len = provider_len + ctx_len;
+		buf = zmalloc(len);
+		if (!buf) {
+			ret = -LTTNG_ERR_NOMEM;
+			goto end;
+		}
 
+		memcpy(buf, provider_name, provider_len);
+		memcpy(buf + provider_len, ctx_name, ctx_len);
+	}
 	memcpy(&lsm.u.context.ctx, ctx, sizeof(struct lttng_event_context));
 
-	lttng_ctl_copy_string(lsm.session.name, handle->session_name,
-			sizeof(lsm.session.name));
+	if (ctx->ctx == LTTNG_EVENT_CONTEXT_APP_CONTEXT) {
+		/*
+		 * Don't leak application addresses to the sessiond.
+		 * This is only necessary when ctx is for an app ctx otherwise
+		 * the values inside the union (type & config) are overwritten.
+		 */
+		lsm.u.context.ctx.u.app_ctx.provider_name = NULL;
+		lsm.u.context.ctx.u.app_ctx.ctx_name = NULL;
+	}
 
-	return lttng_ctl_ask_sessiond(&lsm, NULL);
+	ret = lttng_ctl_ask_sessiond_varlen_no_cmd_header(&lsm, buf, len, NULL);
+end:
+	free(buf);
+	return ret;
 }
 
 /*
- *  Enable event(s) for a channel.
- *  If no event name is specified, all events are enabled.
- *  If no channel name is specified, the default 'channel0' is used.
- *  Returns size of returned session payload data or a negative error code.
+ * Enable event(s) for a channel.
+ *
+ * If no event name is specified, all events are enabled.
+ * If no channel name is specified, the default 'channel0' is used.
+ *
+ * Returns size of returned session payload data or a negative error code.
  */
 int lttng_enable_event(struct lttng_handle *handle,
 		struct lttng_event *ev, const char *channel_name)
@@ -709,7 +882,7 @@ static char *set_agent_filter(const char *filter, struct lttng_event *ev)
 	assert(ev);
 
 	/* Don't add filter for the '*' event. */
-	if (ev->name[0] != '*') {
+	if (strcmp(ev->name, "*") != 0) {
 		if (filter) {
 			err = asprintf(&agent_filter, "(%s) && (logger_name == \"%s\")", filter,
 					ev->name);
@@ -759,7 +932,7 @@ error:
 }
 
 /*
- * Generate the filter bytecode from a give filter expression string. Put the
+ * Generate the filter bytecode from a given filter expression string. Put the
  * newly allocated parser context in ctxp and populate the lsm object with the
  * expression len.
  *
@@ -799,12 +972,6 @@ static int generate_filter(char *filter_expression,
 		ret = -LTTNG_ERR_FILTER_INVAL;
 		goto parse_error;
 	}
-	ret = filter_visitor_set_parent(ctx);
-	if (ret) {
-		fprintf(stderr, "Set parent error\n");
-		ret = -LTTNG_ERR_FILTER_INVAL;
-		goto parse_error;
-	}
 	if (print_xml) {
 		ret = filter_visitor_print_xml(ctx, stdout, 0);
 		if (ret) {
@@ -832,12 +999,28 @@ static int generate_filter(char *filter_expression,
 		ret = -LTTNG_ERR_FILTER_INVAL;
 		goto parse_error;
 	}
-	/* Validate strings used as literals in the expression */
+
+	/* Normalize globbing patterns in the expression. */
+	ret = filter_visitor_ir_normalize_glob_patterns(ctx);
+	if (ret) {
+		ret = -LTTNG_ERR_FILTER_INVAL;
+		goto parse_error;
+	}
+
+	/* Validate strings used as literals in the expression. */
 	ret = filter_visitor_ir_validate_string(ctx);
 	if (ret) {
 		ret = -LTTNG_ERR_FILTER_INVAL;
 		goto parse_error;
 	}
+
+	/* Validate globbing patterns in the expression. */
+	ret = filter_visitor_ir_validate_globbing(ctx);
+	if (ret) {
+		ret = -LTTNG_ERR_FILTER_INVAL;
+		goto parse_error;
+	}
+
 	dbg_printf("done\n");
 
 	dbg_printf("Generating bytecode... ");
@@ -889,10 +1072,18 @@ int lttng_enable_event_with_exclusions(struct lttng_handle *handle,
 		int exclusion_count, char **exclusion_list)
 {
 	struct lttcomm_session_msg lsm;
-	char *varlen_data;
-	int ret = 0;
+	struct lttng_dynamic_buffer send_buffer;
+	int ret = 0, i, fd_to_send = -1;
+	bool send_fd = false;
 	unsigned int free_filter_expression = 0;
 	struct filter_parser_ctx *ctx = NULL;
+
+	/*
+	 * We have either a filter or some exclusions, so we need to set up
+	 * a variable-length memory block from where to send the data.
+	 */
+	lttng_dynamic_buffer_init(&send_buffer);
+
 	/*
 	 * Cast as non-const since we may replace the filter expression
 	 * by a dynamically allocated string. Otherwise, the original
@@ -905,7 +1096,8 @@ int lttng_enable_event_with_exclusions(struct lttng_handle *handle,
 		goto error;
 	}
 
-	/* Empty filter string will always be rejected by the parser
+	/*
+	 * Empty filter string will always be rejected by the parser
 	 * anyway, so treat this corner-case early to eliminate
 	 * lttng_fmemopen error for 0-byte allocation.
 	 */
@@ -940,24 +1132,7 @@ int lttng_enable_event_with_exclusions(struct lttng_handle *handle,
 	lsm.u.enable.exclusion_count = exclusion_count;
 	lsm.u.enable.bytecode_len = 0;
 
-	/*
-	 * For the JUL domain, a filter is enforced except for the enable all
-	 * event. This is done to avoid having the event in all sessions thus
-	 * filtering by logger name.
-	 */
-	if (exclusion_count == 0 && filter_expression == NULL &&
-			(handle->domain.type != LTTNG_DOMAIN_JUL &&
-				handle->domain.type != LTTNG_DOMAIN_LOG4J &&
-				handle->domain.type != LTTNG_DOMAIN_PYTHON)) {
-		goto ask_sessiond;
-	}
-
-	/*
-	 * We have either a filter or some exclusions, so we need to set up
-	 * a variable-length memory block from where to send the data
-	 */
-
-	/* Parse filter expression */
+	/* Parse filter expression. */
 	if (filter_expression != NULL || handle->domain.type == LTTNG_DOMAIN_JUL
 			|| handle->domain.type == LTTNG_DOMAIN_LOG4J
 			|| handle->domain.type == LTTNG_DOMAIN_PYTHON) {
@@ -970,13 +1145,17 @@ int lttng_enable_event_with_exclusions(struct lttng_handle *handle,
 			agent_filter = set_agent_filter(filter_expression, ev);
 			if (!agent_filter) {
 				if (!filter_expression) {
-					/* No JUL and no filter, just skip everything below. */
+					/*
+					 * No JUL and no filter, just skip
+					 * everything below.
+					 */
 					goto ask_sessiond;
 				}
 			} else {
 				/*
-				 * With an agent filter, the original filter has been added to
-				 * it thus replace the filter expression.
+				 * With an agent filter, the original filter has
+				 * been added to it thus replace the filter
+				 * expression.
 				 */
 				filter_expression = agent_filter;
 				free_filter_expression = 1;
@@ -989,39 +1168,82 @@ int lttng_enable_event_with_exclusions(struct lttng_handle *handle,
 		}
 	}
 
-	varlen_data = zmalloc(lsm.u.enable.bytecode_len
+	ret = lttng_dynamic_buffer_set_capacity(&send_buffer,
+			lsm.u.enable.bytecode_len
 			+ lsm.u.enable.expression_len
 			+ LTTNG_SYMBOL_NAME_LEN * exclusion_count);
-	if (!varlen_data) {
+	if (ret) {
 		ret = -LTTNG_ERR_EXCLUSION_NOMEM;
 		goto mem_error;
 	}
 
-	/* Put exclusion names first in the data */
-	while (exclusion_count--) {
-		strncpy(varlen_data + LTTNG_SYMBOL_NAME_LEN * exclusion_count,
-			*(exclusion_list + exclusion_count), LTTNG_SYMBOL_NAME_LEN);
+	/* Put exclusion names first in the data. */
+	for (i = 0; i < exclusion_count; i++) {
+		size_t exclusion_len;
+
+		exclusion_len = lttng_strnlen(*(exclusion_list + i),
+				LTTNG_SYMBOL_NAME_LEN);
+		if (exclusion_len == LTTNG_SYMBOL_NAME_LEN) {
+			/* Exclusion is not NULL-terminated. */
+			ret = -LTTNG_ERR_INVALID;
+			goto mem_error;
+		}
+
+		ret = lttng_dynamic_buffer_append(&send_buffer,
+				*(exclusion_list + i),
+				LTTNG_SYMBOL_NAME_LEN);
+		if (ret) {
+			goto mem_error;
+		}
 	}
-	/* Add filter expression next */
-	if (lsm.u.enable.expression_len != 0) {
-		memcpy(varlen_data
-			+ LTTNG_SYMBOL_NAME_LEN * lsm.u.enable.exclusion_count,
-			filter_expression,
-			lsm.u.enable.expression_len);
+
+	/* Add filter expression next. */
+	if (filter_expression) {
+		ret = lttng_dynamic_buffer_append(&send_buffer,
+				filter_expression, lsm.u.enable.expression_len);
+		if (ret) {
+			goto mem_error;
+		}
 	}
-	/* Add filter bytecode next */
+	/* Add filter bytecode next. */
 	if (ctx && lsm.u.enable.bytecode_len != 0) {
-		memcpy(varlen_data
-			+ LTTNG_SYMBOL_NAME_LEN * lsm.u.enable.exclusion_count
-			+ lsm.u.enable.expression_len,
-			&ctx->bytecode->b,
-			lsm.u.enable.bytecode_len);
+		ret = lttng_dynamic_buffer_append(&send_buffer,
+				&ctx->bytecode->b, lsm.u.enable.bytecode_len);
+		if (ret) {
+			goto mem_error;
+		}
 	}
+	if (ev->extended.ptr) {
+		struct lttng_event_extended *ev_ext =
+			(struct lttng_event_extended *) ev->extended.ptr;
+
+		if (ev_ext->probe_location) {
+			/*
+			 * lttng_userspace_probe_location_serialize returns the
+			 * number of bytes that was appended to the buffer.
+			 */
+			ret = lttng_userspace_probe_location_serialize(
+				ev_ext->probe_location, &send_buffer,
+				&fd_to_send);
+			if (ret < 0) {
+				goto mem_error;
+			}
 
-	ret = lttng_ctl_ask_sessiond_varlen(&lsm, varlen_data,
-			(LTTNG_SYMBOL_NAME_LEN * lsm.u.enable.exclusion_count) +
-			lsm.u.enable.bytecode_len + lsm.u.enable.expression_len, NULL);
-	free(varlen_data);
+			send_fd = fd_to_send >= 0;
+			/*
+			 * Set the size of the userspace probe location element
+			 * of the buffer so that the receiving side knows where
+			 * to split it.
+			 */
+			lsm.u.enable.userspace_probe_location_len = ret;
+		}
+	}
+
+	ret = lttng_ctl_ask_sessiond_fds_varlen(&lsm,
+			send_fd ? &fd_to_send : NULL,
+			send_fd ? 1 : 0,
+			send_buffer.size ? send_buffer.data : NULL,
+			send_buffer.size, NULL, NULL, 0);
 
 mem_error:
 	if (filter_expression && ctx) {
@@ -1032,16 +1254,18 @@ mem_error:
 filter_error:
 	if (free_filter_expression) {
 		/*
-		 * The filter expression has been replaced and must be freed as it is
-		 * not the original filter expression received as a parameter.
+		 * The filter expression has been replaced and must be freed as
+		 * it is not the original filter expression received as a
+		 * parameter.
 		 */
 		free(filter_expression);
 	}
 error:
 	/*
-	 * Return directly to the caller and don't ask the sessiond since something
-	 * went wrong in the parsing of data above.
+	 * Return directly to the caller and don't ask the sessiond since
+	 * something went wrong in the parsing of data above.
 	 */
+	lttng_dynamic_buffer_reset(&send_buffer);
 	return ret;
 
 ask_sessiond:
@@ -1070,7 +1294,8 @@ int lttng_disable_event_ext(struct lttng_handle *handle,
 		goto error;
 	}
 
-	/* Empty filter string will always be rejected by the parser
+	/*
+	 * Empty filter string will always be rejected by the parser
 	 * anyway, so treat this corner-case early to eliminate
 	 * lttng_fmemopen error for 0-byte allocation.
 	 */
@@ -1091,10 +1316,6 @@ int lttng_disable_event_ext(struct lttng_handle *handle,
 	}
 
 	lsm.cmd_type = LTTNG_DISABLE_EVENT;
-	if (ev->name[0] == '\0') {
-		/* Disable all events */
-		lttng_ctl_copy_string(ev->name, "*", sizeof(ev->name));
-	}
 
 	lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
 	/* FIXME: copying non-packed struct to packed struct. */
@@ -1134,13 +1355,17 @@ int lttng_disable_event_ext(struct lttng_handle *handle,
 			agent_filter = set_agent_filter(filter_expression, ev);
 			if (!agent_filter) {
 				if (!filter_expression) {
-					/* No JUL and no filter, just skip everything below. */
+					/*
+					 * No JUL and no filter, just skip
+					 * everything below.
+					 */
 					goto ask_sessiond;
 				}
 			} else {
 				/*
-				 * With a JUL filter, the original filter has been added to it
-				 * thus replace the filter expression.
+				 * With a JUL filter, the original filter has
+				 * been added to it thus replace the filter
+				 * expression.
 				 */
 				filter_expression = agent_filter;
 				free_filter_expression = 1;
@@ -1160,13 +1385,13 @@ int lttng_disable_event_ext(struct lttng_handle *handle,
 		goto mem_error;
 	}
 
-	/* Add filter expression */
+	/* Add filter expression. */
 	if (lsm.u.disable.expression_len != 0) {
 		memcpy(varlen_data,
 			filter_expression,
 			lsm.u.disable.expression_len);
 	}
-	/* Add filter bytecode next */
+	/* Add filter bytecode next. */
 	if (ctx && lsm.u.disable.bytecode_len != 0) {
 		memcpy(varlen_data
 			+ lsm.u.disable.expression_len,
@@ -1174,7 +1399,7 @@ int lttng_disable_event_ext(struct lttng_handle *handle,
 			lsm.u.disable.bytecode_len);
 	}
 
-	ret = lttng_ctl_ask_sessiond_varlen(&lsm, varlen_data,
+	ret = lttng_ctl_ask_sessiond_varlen_no_cmd_header(&lsm, varlen_data,
 			lsm.u.disable.bytecode_len + lsm.u.disable.expression_len, NULL);
 	free(varlen_data);
 
@@ -1187,15 +1412,16 @@ mem_error:
 filter_error:
 	if (free_filter_expression) {
 		/*
-		 * The filter expression has been replaced and must be freed as it is
-		 * not the original filter expression received as a parameter.
+		 * The filter expression has been replaced and must be freed as
+		 * it is not the original filter expression received as a
+		 * parameter.
 		 */
 		free(filter_expression);
 	}
 error:
 	/*
-	 * Return directly to the caller and don't ask the sessiond since something
-	 * went wrong in the parsing of data above.
+	 * Return directly to the caller and don't ask the sessiond since
+	 * something went wrong in the parsing of data above.
 	 */
 	return ret;
 
@@ -1205,10 +1431,10 @@ ask_sessiond:
 }
 
 /*
- *  Disable event(s) of a channel and domain.
- *  If no event name is specified, all events are disabled.
- *  If no channel name is specified, the default 'channel0' is used.
- *  Returns size of returned session payload data or a negative error code.
+ * Disable event(s) of a channel and domain.
+ * If no event name is specified, all events are disabled.
+ * If no channel name is specified, the default 'channel0' is used.
+ * Returns size of returned session payload data or a negative error code.
  */
 int lttng_disable_event(struct lttng_handle *handle, const char *name,
 		const char *channel_name)
@@ -1222,69 +1448,215 @@ int lttng_disable_event(struct lttng_handle *handle, const char *name,
 	return lttng_disable_event_ext(handle, &ev, channel_name, NULL);
 }
 
-/*
- *  Enable channel per domain
- *  Returns size of returned session payload data or a negative error code.
- */
-int lttng_enable_channel(struct lttng_handle *handle,
-		struct lttng_channel *chan)
+struct lttng_channel *lttng_channel_create(struct lttng_domain *domain)
 {
-	struct lttcomm_session_msg lsm;
+	struct lttng_channel *channel = NULL;
+	struct lttng_channel_extended *extended = NULL;
 
-	/*
-	 * NULL arguments are forbidden. No default values.
-	 */
-	if (handle == NULL || chan == NULL) {
-		return -LTTNG_ERR_INVALID;
+	if (!domain) {
+		goto error;
 	}
 
-	memset(&lsm, 0, sizeof(lsm));
+	/* Validate domain. */
+	switch (domain->type) {
+	case LTTNG_DOMAIN_UST:
+		switch (domain->buf_type) {
+		case LTTNG_BUFFER_PER_UID:
+		case LTTNG_BUFFER_PER_PID:
+			break;
+		default:
+			goto error;
+		}
+		break;
+	case LTTNG_DOMAIN_KERNEL:
+		if (domain->buf_type != LTTNG_BUFFER_GLOBAL) {
+			goto error;
+		}
+		break;
+	default:
+		goto error;
+	}
 
-	memcpy(&lsm.u.channel.chan, chan, sizeof(lsm.u.channel.chan));
+	channel = zmalloc(sizeof(*channel));
+	if (!channel) {
+		goto error;
+	}
 
-	lsm.cmd_type = LTTNG_ENABLE_CHANNEL;
+	extended = zmalloc(sizeof(*extended));
+	if (!extended) {
+		goto error;
+	}
 
-	lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
+	channel->attr.extended.ptr = extended;
 
-	lttng_ctl_copy_string(lsm.session.name, handle->session_name,
-			sizeof(lsm.session.name));
+	lttng_channel_set_default_attr(domain, &channel->attr);
+	return channel;
+error:
+	free(channel);
+	free(extended);
+	return NULL;
+}
 
-	return lttng_ctl_ask_sessiond(&lsm, NULL);
+void lttng_channel_destroy(struct lttng_channel *channel)
+{
+	if (!channel) {
+		return;
+	}
+
+	if (channel->attr.extended.ptr) {
+		free(channel->attr.extended.ptr);
+	}
+	free(channel);
 }
 
 /*
- *  All tracing will be stopped for registered events of the channel.
- *  Returns size of returned session payload data or a negative error code.
+ * Enable channel per domain
+ * Returns size of returned session payload data or a negative error code.
  */
-int lttng_disable_channel(struct lttng_handle *handle, const char *name)
+int lttng_enable_channel(struct lttng_handle *handle,
+		struct lttng_channel *in_chan)
 {
 	struct lttcomm_session_msg lsm;
+	size_t total_buffer_size_needed_per_cpu = 0;
 
-	/* Safety check. Both are mandatory */
-	if (handle == NULL || name == NULL) {
+	/* NULL arguments are forbidden. No default values. */
+	if (handle == NULL || in_chan == NULL) {
 		return -LTTNG_ERR_INVALID;
 	}
 
 	memset(&lsm, 0, sizeof(lsm));
+	memcpy(&lsm.u.channel.chan, in_chan, sizeof(lsm.u.channel.chan));
+	lsm.u.channel.chan.attr.extended.ptr = NULL;
 
-	lsm.cmd_type = LTTNG_DISABLE_CHANNEL;
-
-	lttng_ctl_copy_string(lsm.u.disable.channel_name, name,
-			sizeof(lsm.u.disable.channel_name));
+	if (!in_chan->attr.extended.ptr) {
+		struct lttng_channel *channel;
+		struct lttng_channel_extended *extended;
 
-	lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
+		channel = lttng_channel_create(&handle->domain);
+		if (!channel) {
+			return -LTTNG_ERR_NOMEM;
+		}
 
-	lttng_ctl_copy_string(lsm.session.name, handle->session_name,
+		/*
+		 * Create a new channel in order to use default extended
+		 * attribute values.
+		 */
+		extended = (struct lttng_channel_extended *)
+				channel->attr.extended.ptr;
+		memcpy(&lsm.u.channel.extended, extended, sizeof(*extended));
+		lttng_channel_destroy(channel);
+	} else {
+		struct lttng_channel_extended *extended;
+
+		extended = (struct lttng_channel_extended *)
+				in_chan->attr.extended.ptr;
+		memcpy(&lsm.u.channel.extended, extended, sizeof(*extended));
+	}
+
+	/*
+	 * Verify that the amount of memory required to create the requested
+	 * buffer is available on the system at the moment.
+	 */
+	total_buffer_size_needed_per_cpu = lsm.u.channel.chan.attr.num_subbuf *
+		lsm.u.channel.chan.attr.subbuf_size;
+	if (!check_enough_available_memory(total_buffer_size_needed_per_cpu)) {
+		return -LTTNG_ERR_NOMEM;
+	}
+
+	lsm.cmd_type = LTTNG_ENABLE_CHANNEL;
+	lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
+
+	lttng_ctl_copy_string(lsm.session.name, handle->session_name,
+			sizeof(lsm.session.name));
+
+	return lttng_ctl_ask_sessiond(&lsm, NULL);
+}
+
+/*
+ * All tracing will be stopped for registered events of the channel.
+ * Returns size of returned session payload data or a negative error code.
+ */
+int lttng_disable_channel(struct lttng_handle *handle, const char *name)
+{
+	struct lttcomm_session_msg lsm;
+
+	/* Safety check. Both are mandatory. */
+	if (handle == NULL || name == NULL) {
+		return -LTTNG_ERR_INVALID;
+	}
+
+	memset(&lsm, 0, sizeof(lsm));
+
+	lsm.cmd_type = LTTNG_DISABLE_CHANNEL;
+
+	lttng_ctl_copy_string(lsm.u.disable.channel_name, name,
+			sizeof(lsm.u.disable.channel_name));
+
+	lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
+
+	lttng_ctl_copy_string(lsm.session.name, handle->session_name,
+			sizeof(lsm.session.name));
+
+	return lttng_ctl_ask_sessiond(&lsm, NULL);
+}
+
+/*
+ * Add PID to session tracker.
+ * Return 0 on success else a negative LTTng error code.
+ */
+int lttng_track_pid(struct lttng_handle *handle, int pid)
+{
+	struct lttcomm_session_msg lsm;
+
+	/* NULL arguments are forbidden. No default values. */
+	if (handle == NULL) {
+		return -LTTNG_ERR_INVALID;
+	}
+
+	memset(&lsm, 0, sizeof(lsm));
+
+	lsm.cmd_type = LTTNG_TRACK_PID;
+	lsm.u.pid_tracker.pid = pid;
+
+	lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
+
+	lttng_ctl_copy_string(lsm.session.name, handle->session_name,
 			sizeof(lsm.session.name));
 
 	return lttng_ctl_ask_sessiond(&lsm, NULL);
 }
 
 /*
- *  Lists all available tracepoints of domain.
- *  Sets the contents of the events array.
- *  Returns the number of lttng_event entries in events;
- *  on error, returns a negative value.
+ * Remove PID from session tracker.
+ * Return 0 on success else a negative LTTng error code.
+ */
+int lttng_untrack_pid(struct lttng_handle *handle, int pid)
+{
+	struct lttcomm_session_msg lsm;
+
+	/* NULL arguments are forbidden. No default values. */
+	if (handle == NULL) {
+		return -LTTNG_ERR_INVALID;
+	}
+
+	memset(&lsm, 0, sizeof(lsm));
+
+	lsm.cmd_type = LTTNG_UNTRACK_PID;
+	lsm.u.pid_tracker.pid = pid;
+
+	lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
+
+	lttng_ctl_copy_string(lsm.session.name, handle->session_name,
+			sizeof(lsm.session.name));
+
+	return lttng_ctl_ask_sessiond(&lsm, NULL);
+}
+
+/*
+ * Lists all available tracepoints of domain.
+ * Sets the contents of the events array.
+ * Returns the number of lttng_event entries in events;
+ * on error, returns a negative value.
  */
 int lttng_list_tracepoints(struct lttng_handle *handle,
 		struct lttng_event **events)
@@ -1309,10 +1681,10 @@ int lttng_list_tracepoints(struct lttng_handle *handle,
 }
 
 /*
- *  Lists all available tracepoint fields of domain.
- *  Sets the contents of the event field array.
- *  Returns the number of lttng_event_field entries in events;
- *  on error, returns a negative value.
+ * Lists all available tracepoint fields of domain.
+ * Sets the contents of the event field array.
+ * Returns the number of lttng_event_field entries in events;
+ * on error, returns a negative value.
  */
 int lttng_list_tracepoint_fields(struct lttng_handle *handle,
 		struct lttng_event_field **fields)
@@ -1337,11 +1709,11 @@ int lttng_list_tracepoint_fields(struct lttng_handle *handle,
 }
 
 /*
- *  Lists all available kernel system calls. Allocates and sets the contents of
- *  the events array.
+ * Lists all available kernel system calls. Allocates and sets the contents of
+ * the events array.
  *
- *  Returns the number of lttng_event entries in events; on error, returns a
- *  negative value.
+ * Returns the number of lttng_event entries in events; on error, returns a
+ * negative value.
  */
 int lttng_list_syscalls(struct lttng_event **events)
 {
@@ -1366,16 +1738,97 @@ int lttng_list_syscalls(struct lttng_event **events)
 }
 
 /*
- *  Returns a human readable string describing
- *  the error code (a negative value).
+ * Returns a human readable string describing
+ * the error code (a negative value).
  */
 const char *lttng_strerror(int code)
 {
 	return error_get_str(code);
 }
 
+enum lttng_error_code lttng_create_session_ext(
+		struct lttng_session_descriptor *session_descriptor)
+{
+	enum lttng_error_code ret_code;
+	struct lttcomm_session_msg lsm = {
+		.cmd_type = LTTNG_CREATE_SESSION_EXT,
+	};
+	void *reply = NULL;
+	struct lttng_buffer_view reply_view;
+	int reply_ret;
+	bool sessiond_must_generate_ouput;
+	struct lttng_dynamic_buffer payload;
+	int ret;
+	size_t descriptor_size;
+	struct lttng_session_descriptor *descriptor_reply = NULL;
+
+	lttng_dynamic_buffer_init(&payload);
+	if (!session_descriptor) {
+		ret_code = LTTNG_ERR_INVALID;
+		goto end;
+	}
+
+	sessiond_must_generate_ouput =
+			!lttng_session_descriptor_is_output_destination_initialized(
+				session_descriptor);
+	if (sessiond_must_generate_ouput) {
+		const char *home_dir = utils_get_home_dir();
+		size_t home_dir_len = home_dir ? strlen(home_dir) + 1 : 0;
+
+		if (!home_dir || home_dir_len > LTTNG_PATH_MAX) {
+			ret_code = LTTNG_ERR_FATAL;
+			goto end;
+		}
+
+		lsm.u.create_session.home_dir_size = (uint16_t) home_dir_len;
+		ret = lttng_dynamic_buffer_append(&payload, home_dir,
+				home_dir_len);
+		if (ret) {
+			ret_code = LTTNG_ERR_NOMEM;
+			goto end;
+		}
+	}
+
+	descriptor_size = payload.size;
+	ret = lttng_session_descriptor_serialize(session_descriptor,
+			&payload);
+	if (ret) {
+		ret_code = LTTNG_ERR_INVALID;
+		goto end;
+	}
+	descriptor_size = payload.size - descriptor_size;
+	lsm.u.create_session.session_descriptor_size = descriptor_size;
+
+	/* Command returns a session descriptor on success. */
+	reply_ret = lttng_ctl_ask_sessiond_varlen_no_cmd_header(&lsm, payload.data,
+			payload.size, &reply);
+	if (reply_ret < 0) {
+		ret_code = -reply_ret;
+		goto end;
+	} else if (reply_ret == 0) {
+		/* Socket unexpectedly closed by the session daemon. */
+		ret_code = LTTNG_ERR_FATAL;
+		goto end;
+	}
+
+	reply_view = lttng_buffer_view_init(reply, 0, reply_ret);
+	ret = lttng_session_descriptor_create_from_buffer(&reply_view,
+			&descriptor_reply);
+	if (ret < 0) {
+		ret_code = LTTNG_ERR_FATAL;
+		goto end;
+	}
+	ret_code = LTTNG_OK;
+	lttng_session_descriptor_assign(session_descriptor, descriptor_reply);
+end:
+	free(reply);
+	lttng_dynamic_buffer_reset(&payload);
+	lttng_session_descriptor_destroy(descriptor_reply);
+	return ret_code;
+}
+
 /*
- * Create a brand new session using name and url for destination.
+ * Create a new session using name and url for destination.
  *
  * Returns LTTNG_OK on success or a negative error code.
  */
@@ -1383,38 +1836,169 @@ int lttng_create_session(const char *name, const char *url)
 {
 	int ret;
 	ssize_t size;
-	struct lttcomm_session_msg lsm;
 	struct lttng_uri *uris = NULL;
+	struct lttng_session_descriptor *descriptor = NULL;
+	enum lttng_error_code ret_code;
 
-	if (name == NULL) {
-		return -LTTNG_ERR_INVALID;
+	if (!name) {
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
 	}
 
-	memset(&lsm, 0, sizeof(lsm));
-
-	lsm.cmd_type = LTTNG_CREATE_SESSION;
-	lttng_ctl_copy_string(lsm.session.name, name, sizeof(lsm.session.name));
-
-	/* There should never be a data URL */
 	size = uri_parse_str_urls(url, NULL, &uris);
 	if (size < 0) {
-		return -LTTNG_ERR_INVALID;
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
 	}
+	switch (size) {
+	case 0:
+		descriptor = lttng_session_descriptor_create(name);
+		break;
+	case 1:
+		if (uris[0].dtype != LTTNG_DST_PATH) {
+			ret = -LTTNG_ERR_INVALID;
+			goto end;
+		}
+		descriptor = lttng_session_descriptor_local_create(name,
+				uris[0].dst.path);
+		break;
+	case 2:
+		descriptor = lttng_session_descriptor_network_create(name, url,
+				NULL);
+		break;
+	default:
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
+	}
+	if (!descriptor) {
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
+	}
+	ret_code = lttng_create_session_ext(descriptor);
+	ret = ret_code == LTTNG_OK ? 0 : -ret_code;
+end:
+	lttng_session_descriptor_destroy(descriptor);
+	free(uris);
+	return ret;
+}
 
-	lsm.u.uri.size = size;
+/*
+ * Create a session exclusively used for snapshot.
+ *
+ * Returns LTTNG_OK on success or a negative error code.
+ */
+int lttng_create_session_snapshot(const char *name, const char *snapshot_url)
+{
+	int ret;
+	enum lttng_error_code ret_code;
+	ssize_t size;
+	struct lttng_uri *uris = NULL;
+	struct lttng_session_descriptor *descriptor = NULL;
 
-	ret = lttng_ctl_ask_sessiond_varlen(&lsm, uris,
-			sizeof(struct lttng_uri) * size, NULL);
+	if (!name) {
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
+	}
 
+	size = uri_parse_str_urls(snapshot_url, NULL, &uris);
+	if (size < 0) {
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
+	}
+	/*
+	 * If the user does not specify a custom subdir, use the session name.
+	 */
+	if (size > 0 && uris[0].dtype != LTTNG_DST_PATH &&
+			strlen(uris[0].subdir) == 0) {
+		ret = snprintf(uris[0].subdir, sizeof(uris[0].subdir), "%s",
+				name);
+		if (ret < 0) {
+			PERROR("Failed to set session name as network destination sub-directory");
+			ret = -LTTNG_ERR_FATAL;
+			goto end;
+		} else if (ret >= sizeof(uris[0].subdir)) {
+			/* Truncated output. */
+			ret = -LTTNG_ERR_INVALID;
+			goto end;
+		}
+	}
+
+	switch (size) {
+	case 0:
+		descriptor = lttng_session_descriptor_snapshot_create(name);
+		break;
+	case 1:
+		if (uris[0].dtype != LTTNG_DST_PATH) {
+			ret = -LTTNG_ERR_INVALID;
+			goto end;
+		}
+		descriptor = lttng_session_descriptor_snapshot_local_create(
+				name,
+				uris[0].dst.path);
+		break;
+	case 2:
+		descriptor = lttng_session_descriptor_snapshot_network_create(
+				name,
+				snapshot_url,
+				NULL);
+		break;
+	default:
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
+	}
+	if (!descriptor) {
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
+	}
+	ret_code = lttng_create_session_ext(descriptor);
+	ret = ret_code == LTTNG_OK ? 0 : -ret_code;
+end:
+	lttng_session_descriptor_destroy(descriptor);
 	free(uris);
 	return ret;
 }
 
 /*
- *  Destroy session using name.
- *  Returns size of returned session payload data or a negative error code.
+ * Create a session exclusively used for live.
+ *
+ * Returns LTTNG_OK on success or a negative error code.
  */
-int lttng_destroy_session(const char *session_name)
+int lttng_create_session_live(const char *name, const char *url,
+		unsigned int timer_interval)
+{
+	int ret;
+	enum lttng_error_code ret_code;
+	struct lttng_session_descriptor *descriptor = NULL;
+
+	if (!name) {
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
+	}
+
+	if (url) {
+		descriptor = lttng_session_descriptor_live_network_create(
+				name, url, NULL, timer_interval);
+	} else {
+		descriptor = lttng_session_descriptor_live_create(
+				name, timer_interval);
+	}
+	if (!descriptor) {
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
+	}
+	ret_code = lttng_create_session_ext(descriptor);
+	ret = ret_code == LTTNG_OK ? 0 : -ret_code;
+end:
+	lttng_session_descriptor_destroy(descriptor);
+	return ret;
+}
+
+/*
+ * Destroy session using name.
+ * Returns size of returned session payload data or a negative error code.
+ */
+static
+int _lttng_destroy_session(const char *session_name)
 {
 	struct lttcomm_session_msg lsm;
 
@@ -1432,24 +2016,120 @@ int lttng_destroy_session(const char *session_name)
 }
 
 /*
- *  Ask the session daemon for all available sessions.
- *  Sets the contents of the sessions array.
- *  Returns the number of lttng_session entries in sessions;
- *  on error, returns a negative value.
+ * Stop the session and wait for the data before destroying it
  */
-int lttng_list_sessions(struct lttng_session **sessions)
+int lttng_destroy_session(const char *session_name)
+{
+	int ret;
+
+	/*
+	 * Stop the tracing and wait for the data.
+	 */
+	ret = _lttng_stop_tracing(session_name, 1);
+	if (ret && ret != -LTTNG_ERR_TRACE_ALREADY_STOPPED) {
+		goto end;
+	}
+
+	ret = _lttng_destroy_session(session_name);
+end:
+	return ret;
+}
+
+/*
+ * Destroy the session without waiting for the data.
+ */
+int lttng_destroy_session_no_wait(const char *session_name)
+{
+	int ret;
+
+	/*
+	 * Stop the tracing without waiting for the data.
+	 * The session might already have been stopped, so just
+	 * skip this error.
+	 */
+	ret = _lttng_stop_tracing(session_name, 0);
+	if (ret && ret != -LTTNG_ERR_TRACE_ALREADY_STOPPED) {
+		goto end;
+	}
+
+	ret = _lttng_destroy_session(session_name);
+end:
+	return ret;
+}
+
+/*
+ * Ask the session daemon for all available sessions.
+ * Sets the contents of the sessions array.
+ * Returns the number of lttng_session entries in sessions;
+ * on error, returns a negative value.
+ */
+int lttng_list_sessions(struct lttng_session **out_sessions)
 {
 	int ret;
 	struct lttcomm_session_msg lsm;
+	const size_t session_size = sizeof(struct lttng_session) +
+			sizeof(struct lttng_session_extended);
+	size_t session_count, i;
+	struct lttng_session_extended *sessions_extended_begin;
+	struct lttng_session *sessions = NULL;
 
 	memset(&lsm, 0, sizeof(lsm));
 	lsm.cmd_type = LTTNG_LIST_SESSIONS;
-	ret = lttng_ctl_ask_sessiond(&lsm, (void**) sessions);
-	if (ret < 0) {
-		return ret;
+	ret = lttng_ctl_ask_sessiond(&lsm, (void**) &sessions);
+	if (ret <= 0) {
+		ret = ret == 0 ? -LTTNG_ERR_FATAL : ret;
+		goto end;
+	}
+	if (!sessions) {
+		ret = -LTTNG_ERR_FATAL;
+		goto end;
+	}
+
+	if (ret % session_size) {
+		ret = -LTTNG_ERR_UNK;
+		free(sessions);
+		*out_sessions = NULL;
+		goto end;
+	}
+	session_count = (size_t) ret / session_size;
+	sessions_extended_begin = (struct lttng_session_extended *)
+			(&sessions[session_count]);
+
+	/* Set extended session info pointers. */
+	for (i = 0; i < session_count; i++) {
+		struct lttng_session *session = &sessions[i];
+		struct lttng_session_extended *extended =
+				&(sessions_extended_begin[i]);
+
+		session->extended.ptr = extended;
+	}
+
+	ret = (int) session_count;
+	*out_sessions = sessions;
+end:
+	return ret;
+}
+
+enum lttng_error_code lttng_session_get_creation_time(
+		const struct lttng_session *session, uint64_t *creation_time)
+{
+	enum lttng_error_code ret = LTTNG_OK;
+	struct lttng_session_extended *extended;
+
+	if (!session || !creation_time || !session->extended.ptr) {
+		ret = LTTNG_ERR_INVALID;
+		goto end;
 	}
 
-	return ret / sizeof(struct lttng_session);
+	extended = session->extended.ptr;
+	if (!extended->creation_time.is_set) {
+		/* Not created on the session daemon yet. */
+		ret = LTTNG_ERR_SESSION_NOT_EXIST;
+		goto end;
+	}
+	*creation_time = extended->creation_time.value;
+end:
+	return ret;
 }
 
 int lttng_set_session_shm_path(const char *session_name,
@@ -1473,10 +2153,10 @@ int lttng_set_session_shm_path(const char *session_name,
 }
 
 /*
- *  Ask the session daemon for all available domains of a session.
- *  Sets the contents of the domains array.
- *  Returns the number of lttng_domain entries in domains;
- *  on error, returns a negative value.
+ * Ask the session daemon for all available domains of a session.
+ * Sets the contents of the domains array.
+ * Returns the number of lttng_domain entries in domains;
+ * on error, returns a negative value.
  */
 int lttng_list_domains(const char *session_name,
 		struct lttng_domain **domains)
@@ -1503,19 +2183,24 @@ int lttng_list_domains(const char *session_name,
 }
 
 /*
- *  Ask the session daemon for all available channels of a session.
- *  Sets the contents of the channels array.
- *  Returns the number of lttng_channel entries in channels;
- *  on error, returns a negative value.
+ * Ask the session daemon for all available channels of a session.
+ * Sets the contents of the channels array.
+ * Returns the number of lttng_channel entries in channels;
+ * on error, returns a negative value.
  */
 int lttng_list_channels(struct lttng_handle *handle,
 		struct lttng_channel **channels)
 {
 	int ret;
+	size_t channel_count, i;
+	const size_t channel_size = sizeof(struct lttng_channel) +
+			sizeof(struct lttng_channel_extended);
 	struct lttcomm_session_msg lsm;
+	void *extended_at;
 
 	if (handle == NULL) {
-		return -LTTNG_ERR_INVALID;
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
 	}
 
 	memset(&lsm, 0, sizeof(lsm));
@@ -1527,23 +2212,50 @@ int lttng_list_channels(struct lttng_handle *handle,
 
 	ret = lttng_ctl_ask_sessiond(&lsm, (void**) channels);
 	if (ret < 0) {
-		return ret;
+		goto end;
+	}
+
+	if (ret % channel_size) {
+		ret = -LTTNG_ERR_UNK;
+		free(*channels);
+		*channels = NULL;
+		goto end;
+	}
+	channel_count = (size_t) ret / channel_size;
+
+	/* Set extended info pointers */
+	extended_at = ((void *) *channels) +
+			channel_count * sizeof(struct lttng_channel);
+	for (i = 0; i < channel_count; i++) {
+		struct lttng_channel *chan = &(*channels)[i];
+
+		chan->attr.extended.ptr = extended_at;
+		extended_at += sizeof(struct lttng_channel_extended);
 	}
 
-	return ret / sizeof(struct lttng_channel);
+	ret = (int) channel_count;
+end:
+	return ret;
 }
 
 /*
- *  Ask the session daemon for all available events of a session channel.
- *  Sets the contents of the events array.
- *  Returns the number of lttng_event entries in events;
- *  on error, returns a negative value.
+ * Ask the session daemon for all available events of a session channel.
+ * Sets the contents of the events array.
+ * Returns the number of lttng_event entries in events;
+ * on error, returns a negative value.
  */
 int lttng_list_events(struct lttng_handle *handle,
 		const char *channel_name, struct lttng_event **events)
 {
 	int ret;
 	struct lttcomm_session_msg lsm;
+	struct lttcomm_event_command_header *cmd_header = NULL;
+	size_t cmd_header_len;
+	uint32_t nb_events, i;
+	void *comm_ext_at;
+	char *reception_buffer = NULL;
+	struct lttng_dynamic_buffer listing;
+	size_t storage_req;
 
 	/* Safety check. An handle and channel name are mandatory */
 	if (handle == NULL || channel_name == NULL) {
@@ -1556,15 +2268,223 @@ int lttng_list_events(struct lttng_handle *handle,
 			sizeof(lsm.session.name));
 	lttng_ctl_copy_string(lsm.u.list.channel_name, channel_name,
 			sizeof(lsm.u.list.channel_name));
-
 	lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
 
-	ret = lttng_ctl_ask_sessiond(&lsm, (void**) events);
+	ret = lttng_ctl_ask_sessiond_fds_varlen(&lsm, NULL, 0, NULL, 0,
+		(void **) &reception_buffer, (void **) &cmd_header,
+		&cmd_header_len);
 	if (ret < 0) {
-		return ret;
+		goto end;
 	}
 
-	return ret / sizeof(struct lttng_event);
+	if (!cmd_header) {
+		ret = -LTTNG_ERR_UNK;
+		goto end;
+	}
+
+	/* Set number of events and free command header */
+	nb_events = cmd_header->nb_events;
+	if (nb_events > INT_MAX) {
+		ret = -EOVERFLOW;
+		goto end;
+	}
+	free(cmd_header);
+	cmd_header = NULL;
+
+	/*
+	 * The buffer that is returned must contain a "flat" version of
+	 * the events that are returned. In other words, all pointers
+	 * within an lttng_event must point to a location within the returned
+	 * buffer so that the user may free everything by simply calling free()
+	 * on the returned buffer. This is needed in order to maintain API
+	 * compatibility.
+	 *
+	 * A first pass is performed to compute the size of the buffer that
+	 * must be allocated. A second pass is then performed to setup
+	 * the returned events so that their members always point within the
+	 * buffer.
+	 *
+	 * The layout of the returned buffer is as follows:
+	 *   - struct lttng_event[nb_events],
+	 *   - nb_events times the following:
+	 *     - struct lttng_event_extended,
+	 *     - flattened version of userspace_probe_location
+	 *     - filter_expression
+	 *     - exclusions
+	 *     - padding to align to 64-bits
+	 */
+	comm_ext_at = reception_buffer +
+		(nb_events * sizeof(struct lttng_event));
+	storage_req = nb_events * sizeof(struct lttng_event);
+
+	for (i = 0; i < nb_events; i++) {
+		struct lttcomm_event_extended_header *ext_comm =
+			(struct lttcomm_event_extended_header *) comm_ext_at;
+		int probe_storage_req = 0;
+
+		comm_ext_at += sizeof(*ext_comm);
+		comm_ext_at += ext_comm->filter_len;
+		comm_ext_at +=
+			ext_comm->nb_exclusions * LTTNG_SYMBOL_NAME_LEN;
+
+		if (ext_comm->userspace_probe_location_len) {
+			struct lttng_userspace_probe_location *probe_location = NULL;
+			struct lttng_buffer_view probe_location_view;
+
+			probe_location_view = lttng_buffer_view_init(
+					comm_ext_at, 0,
+					ext_comm->userspace_probe_location_len);
+
+			/*
+			 * Create a temporary userspace probe location to
+			 * determine the size needed by a "flattened" version
+			 * of that same probe location.
+			 */
+			ret = lttng_userspace_probe_location_create_from_buffer(
+					&probe_location_view, &probe_location);
+			if (ret < 0) {
+				ret = -LTTNG_ERR_PROBE_LOCATION_INVAL;
+				goto end;
+			}
+
+			ret = lttng_userspace_probe_location_flatten(
+					probe_location, NULL);
+			lttng_userspace_probe_location_destroy(probe_location);
+			if (ret < 0) {
+				ret = -LTTNG_ERR_PROBE_LOCATION_INVAL;
+				goto end;
+			}
+
+			probe_storage_req = ret;
+			comm_ext_at += ext_comm->userspace_probe_location_len;
+		}
+
+		storage_req += sizeof(struct lttng_event_extended);
+		storage_req += ext_comm->filter_len;
+		storage_req += ext_comm->nb_exclusions * LTTNG_SYMBOL_NAME_LEN;
+		/* Padding to ensure the flat probe is aligned. */
+		storage_req = ALIGN_TO(storage_req, sizeof(uint64_t));
+		storage_req += probe_storage_req;
+	}
+
+	lttng_dynamic_buffer_init(&listing);
+	/*
+	 * We must ensure that "listing" is never resized so as to preserve
+	 * the validity of the flattened objects.
+	 */
+	ret = lttng_dynamic_buffer_set_capacity(&listing, storage_req);
+	if (ret) {
+		ret = -LTTNG_ERR_NOMEM;
+		goto end;
+	}
+
+	ret = lttng_dynamic_buffer_append(&listing, reception_buffer,
+			nb_events * sizeof(struct lttng_event));
+	if (ret) {
+		ret = -LTTNG_ERR_NOMEM;
+		goto free_dynamic_buffer;
+	}
+
+	comm_ext_at = reception_buffer +
+			(nb_events * sizeof(struct lttng_event));
+	for (i = 0; i < nb_events; i++) {
+		struct lttng_event *event = (struct lttng_event *)
+			(listing.data + (sizeof(struct lttng_event) * i));
+		struct lttcomm_event_extended_header *ext_comm =
+			(struct lttcomm_event_extended_header *) comm_ext_at;
+		struct lttng_event_extended *event_extended =
+			(struct lttng_event_extended *)
+				(listing.data + listing.size);
+
+		/* Insert struct lttng_event_extended. */
+		ret = lttng_dynamic_buffer_set_size(&listing,
+				listing.size + sizeof(*event_extended));
+		if (ret) {
+			ret = -LTTNG_ERR_NOMEM;
+			goto free_dynamic_buffer;
+		}
+		event->extended.ptr = event_extended;
+
+		comm_ext_at += sizeof(*ext_comm);
+
+		/* Insert filter expression. */
+		if (ext_comm->filter_len) {
+			event_extended->filter_expression = listing.data +
+					listing.size;
+			ret = lttng_dynamic_buffer_append(&listing, comm_ext_at,
+					ext_comm->filter_len);
+			if (ret) {
+				ret = -LTTNG_ERR_NOMEM;
+				goto free_dynamic_buffer;
+			}
+			comm_ext_at += ext_comm->filter_len;
+		}
+
+		/* Insert exclusions. */
+		if (ext_comm->nb_exclusions) {
+			event_extended->exclusions.count =
+					ext_comm->nb_exclusions;
+			event_extended->exclusions.strings =
+					listing.data + listing.size;
+
+			ret = lttng_dynamic_buffer_append(&listing,
+					comm_ext_at,
+					ext_comm->nb_exclusions * LTTNG_SYMBOL_NAME_LEN);
+			if (ret) {
+				ret = -LTTNG_ERR_NOMEM;
+				goto free_dynamic_buffer;
+			}
+			comm_ext_at += ext_comm->nb_exclusions * LTTNG_SYMBOL_NAME_LEN;
+		}
+
+		/* Insert padding to align to 64-bits. */
+		ret = lttng_dynamic_buffer_set_size(&listing,
+				ALIGN_TO(listing.size, sizeof(uint64_t)));
+		if (ret) {
+			ret = -LTTNG_ERR_NOMEM;
+			goto free_dynamic_buffer;
+		}
+
+		/* Insert flattened userspace probe location. */
+		if (ext_comm->userspace_probe_location_len) {
+			struct lttng_userspace_probe_location *probe_location = NULL;
+			struct lttng_buffer_view probe_location_view;
+
+			probe_location_view = lttng_buffer_view_init(
+					comm_ext_at, 0,
+					ext_comm->userspace_probe_location_len);
+
+			ret = lttng_userspace_probe_location_create_from_buffer(
+					&probe_location_view, &probe_location);
+			if (ret < 0) {
+				ret = -LTTNG_ERR_PROBE_LOCATION_INVAL;
+				goto free_dynamic_buffer;
+			}
+
+			event_extended->probe_location = (struct lttng_userspace_probe_location *)
+					(listing.data + listing.size);
+			ret = lttng_userspace_probe_location_flatten(
+					probe_location, &listing);
+			lttng_userspace_probe_location_destroy(probe_location);
+			if (ret < 0) {
+				ret = -LTTNG_ERR_PROBE_LOCATION_INVAL;
+				goto free_dynamic_buffer;
+			}
+
+			comm_ext_at += ext_comm->userspace_probe_location_len;
+		}
+	}
+
+	/* Don't reset listing buffer as we return its content. */
+	*events = (struct lttng_event *) listing.data;
+	lttng_dynamic_buffer_init(&listing);
+	ret = (int) nb_events;
+free_dynamic_buffer:
+	lttng_dynamic_buffer_reset(&listing);
+end:
+	free(cmd_header);
+	free(reception_buffer);
+	return ret;
 }
 
 /*
@@ -1583,28 +2503,15 @@ int lttng_set_tracing_group(const char *name)
 	}
 
 	return 0;
-}
-
-/*
- * Returns size of returned session payload data or a negative error code.
- */
-int lttng_calibrate(struct lttng_handle *handle,
-		struct lttng_calibrate *calibrate)
-{
-	struct lttcomm_session_msg lsm;
-
-	/* Safety check. NULL pointer are forbidden */
-	if (handle == NULL || calibrate == NULL) {
-		return -LTTNG_ERR_INVALID;
-	}
-
-	memset(&lsm, 0, sizeof(lsm));
-	lsm.cmd_type = LTTNG_CALIBRATE;
-	lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
-
-	memcpy(&lsm.u.calibrate, calibrate, sizeof(lsm.u.calibrate));
+}
 
-	return lttng_ctl_ask_sessiond(&lsm, NULL);
+int lttng_calibrate(struct lttng_handle *handle,
+		struct lttng_calibrate *calibrate)
+{
+	/*
+	 * This command was removed in LTTng 2.9.
+	 */
+	return -LTTNG_ERR_UND;
 }
 
 /*
@@ -1614,11 +2521,14 @@ int lttng_calibrate(struct lttng_handle *handle,
 void lttng_channel_set_default_attr(struct lttng_domain *domain,
 		struct lttng_channel_attr *attr)
 {
+	struct lttng_channel_extended *extended;
+
 	/* Safety check */
 	if (attr == NULL || domain == NULL) {
 		return;
 	}
 
+	extended = (struct lttng_channel_extended *) attr->extended.ptr;
 	memset(attr, 0, sizeof(struct lttng_channel_attr));
 
 	/* Same for all domains. */
@@ -1628,11 +2538,18 @@ void lttng_channel_set_default_attr(struct lttng_domain *domain,
 
 	switch (domain->type) {
 	case LTTNG_DOMAIN_KERNEL:
-		attr->switch_timer_interval = DEFAULT_KERNEL_CHANNEL_SWITCH_TIMER;
+		attr->switch_timer_interval =
+				DEFAULT_KERNEL_CHANNEL_SWITCH_TIMER;
 		attr->read_timer_interval = DEFAULT_KERNEL_CHANNEL_READ_TIMER;
 		attr->subbuf_size = default_get_kernel_channel_subbuf_size();
 		attr->num_subbuf = DEFAULT_KERNEL_CHANNEL_SUBBUF_NUM;
 		attr->output = DEFAULT_KERNEL_CHANNEL_OUTPUT;
+		if (extended) {
+			extended->monitor_timer_interval =
+					DEFAULT_KERNEL_CHANNEL_MONITOR_TIMER;
+			extended->blocking_timeout =
+					DEFAULT_KERNEL_CHANNEL_BLOCKING_TIMEOUT;
+		}
 		break;
 	case LTTNG_DOMAIN_UST:
 		switch (domain->buf_type) {
@@ -1640,22 +2557,185 @@ void lttng_channel_set_default_attr(struct lttng_domain *domain,
 			attr->subbuf_size = default_get_ust_uid_channel_subbuf_size();
 			attr->num_subbuf = DEFAULT_UST_UID_CHANNEL_SUBBUF_NUM;
 			attr->output = DEFAULT_UST_UID_CHANNEL_OUTPUT;
-			attr->switch_timer_interval = DEFAULT_UST_UID_CHANNEL_SWITCH_TIMER;
-			attr->read_timer_interval = DEFAULT_UST_UID_CHANNEL_READ_TIMER;
+			attr->switch_timer_interval =
+					DEFAULT_UST_UID_CHANNEL_SWITCH_TIMER;
+			attr->read_timer_interval =
+					DEFAULT_UST_UID_CHANNEL_READ_TIMER;
+			if (extended) {
+				extended->monitor_timer_interval =
+						DEFAULT_UST_UID_CHANNEL_MONITOR_TIMER;
+				extended->blocking_timeout =
+						DEFAULT_UST_UID_CHANNEL_BLOCKING_TIMEOUT;
+			}
 			break;
 		case LTTNG_BUFFER_PER_PID:
 		default:
 			attr->subbuf_size = default_get_ust_pid_channel_subbuf_size();
 			attr->num_subbuf = DEFAULT_UST_PID_CHANNEL_SUBBUF_NUM;
 			attr->output = DEFAULT_UST_PID_CHANNEL_OUTPUT;
-			attr->switch_timer_interval = DEFAULT_UST_PID_CHANNEL_SWITCH_TIMER;
-			attr->read_timer_interval = DEFAULT_UST_PID_CHANNEL_READ_TIMER;
+			attr->switch_timer_interval =
+					DEFAULT_UST_PID_CHANNEL_SWITCH_TIMER;
+			attr->read_timer_interval =
+					DEFAULT_UST_PID_CHANNEL_READ_TIMER;
+			if (extended) {
+				extended->monitor_timer_interval =
+						DEFAULT_UST_PID_CHANNEL_MONITOR_TIMER;
+				extended->blocking_timeout =
+						DEFAULT_UST_PID_CHANNEL_BLOCKING_TIMEOUT;
+			}
 			break;
 		}
 	default:
 		/* Default behavior: leave set to 0. */
 		break;
 	}
+
+	attr->extended.ptr = extended;
+}
+
+int lttng_channel_get_discarded_event_count(struct lttng_channel *channel,
+		uint64_t *discarded_events)
+{
+	int ret = 0;
+	struct lttng_channel_extended *chan_ext;
+
+	if (!channel || !discarded_events) {
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
+	}
+
+	chan_ext = channel->attr.extended.ptr;
+	if (!chan_ext) {
+		/*
+		 * This can happen since the lttng_channel structure is
+		 * used for other tasks where this pointer is never set.
+		 */
+		*discarded_events = 0;
+		goto end;
+	}
+
+	*discarded_events = chan_ext->discarded_events;
+end:
+	return ret;
+}
+
+int lttng_channel_get_lost_packet_count(struct lttng_channel *channel,
+		uint64_t *lost_packets)
+{
+	int ret = 0;
+	struct lttng_channel_extended *chan_ext;
+
+	if (!channel || !lost_packets) {
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
+	}
+
+	chan_ext = channel->attr.extended.ptr;
+	if (!chan_ext) {
+		/*
+		 * This can happen since the lttng_channel structure is
+		 * used for other tasks where this pointer is never set.
+		 */
+		*lost_packets = 0;
+		goto end;
+	}
+
+	*lost_packets = chan_ext->lost_packets;
+end:
+	return ret;
+}
+
+int lttng_channel_get_monitor_timer_interval(struct lttng_channel *chan,
+		uint64_t *monitor_timer_interval)
+{
+	int ret = 0;
+
+	if (!chan || !monitor_timer_interval) {
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
+	}
+
+	if (!chan->attr.extended.ptr) {
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
+	}
+
+	*monitor_timer_interval = ((struct lttng_channel_extended *)
+			chan->attr.extended.ptr)->monitor_timer_interval;
+end:
+	return ret;
+}
+
+int lttng_channel_set_monitor_timer_interval(struct lttng_channel *chan,
+		uint64_t monitor_timer_interval)
+{
+	int ret = 0;
+
+	if (!chan || !chan->attr.extended.ptr) {
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
+	}
+
+	((struct lttng_channel_extended *)
+			chan->attr.extended.ptr)->monitor_timer_interval =
+			monitor_timer_interval;
+end:
+	return ret;
+}
+
+int lttng_channel_get_blocking_timeout(struct lttng_channel *chan,
+		int64_t *blocking_timeout)
+{
+	int ret = 0;
+
+	if (!chan || !blocking_timeout) {
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
+	}
+
+	if (!chan->attr.extended.ptr) {
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
+	}
+
+	*blocking_timeout = ((struct lttng_channel_extended *)
+			chan->attr.extended.ptr)->blocking_timeout;
+end:
+	return ret;
+}
+
+int lttng_channel_set_blocking_timeout(struct lttng_channel *chan,
+		int64_t blocking_timeout)
+{
+	int ret = 0;
+	int64_t msec_timeout;
+
+	if (!chan || !chan->attr.extended.ptr) {
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
+	}
+
+	if (blocking_timeout < 0 && blocking_timeout != -1) {
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
+	}
+
+	/*
+	 * LTTng-ust's use of poll() to implement this timeout mechanism forces
+	 * us to accept a narrower range of values (msecs expressed as a signed
+	 * 32-bit integer).
+	 */
+	msec_timeout = blocking_timeout / 1000;
+	if (msec_timeout != (int32_t) msec_timeout) {
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
+	}
+
+	((struct lttng_channel_extended *)
+			chan->attr.extended.ptr)->blocking_timeout =
+			blocking_timeout;
+end:
+	return ret;
 }
 
 /*
@@ -1670,25 +2750,25 @@ int lttng_session_daemon_alive(void)
 
 	ret = set_session_daemon_path();
 	if (ret < 0) {
-		/* Error */
+		/* Error. */
 		return ret;
 	}
 
 	if (*sessiond_sock_path == '\0') {
 		/*
-		 * No socket path set. Weird error which means the constructor was not
-		 * called.
+		 * No socket path set. Weird error which means the constructor
+		 * was not called.
 		 */
 		assert(0);
 	}
 
 	ret = try_connect_sessiond(sessiond_sock_path);
 	if (ret < 0) {
-		/* Not alive */
+		/* Not alive. */
 		return 0;
 	}
 
-	/* Is alive */
+	/* Is alive. */
 	return 1;
 }
 
@@ -1724,7 +2804,7 @@ int lttng_set_consumer_url(struct lttng_handle *handle,
 
 	lsm.u.uri.size = size;
 
-	ret = lttng_ctl_ask_sessiond_varlen(&lsm, uris,
+	ret = lttng_ctl_ask_sessiond_varlen_no_cmd_header(&lsm, uris,
 			sizeof(struct lttng_uri) * size, NULL);
 
 	free(uris);
@@ -1748,205 +2828,246 @@ int lttng_disable_consumer(struct lttng_handle *handle)
 }
 
 /*
- * This is an extension of create session that is ONLY and SHOULD only be used
- * by the lttng command line program. It exists to avoid using URI parsing in
- * the lttng client.
- *
- * We need the date and time for the trace path subdirectory for the case where
- * the user does NOT define one using either -o or -U. Using the normal
- * lttng_create_session API call, we have no clue on the session daemon side if
- * the URL was generated automatically by the client or define by the user.
- *
- * So this function "wrapper" is hidden from the public API, takes the datetime
- * string and appends it if necessary to the URI subdirectory before sending it
- * to the session daemon.
- *
- * With this extra function, the lttng_create_session call behavior is not
- * changed and the timestamp is appended to the URI on the session daemon side
- * if necessary.
+ * [OBSOLETE]
  */
 int _lttng_create_session_ext(const char *name, const char *url,
 		const char *datetime)
+{
+	return -ENOSYS;
+}
+
+/*
+ * For a given session name, this call checks if the data is ready to be read
+ * or is still being extracted by the consumer(s) hence not ready to be used by
+ * any readers.
+ */
+int lttng_data_pending(const char *session_name)
 {
 	int ret;
-	ssize_t size;
 	struct lttcomm_session_msg lsm;
-	struct lttng_uri *uris = NULL;
+	uint8_t *pending = NULL;
 
-	if (name == NULL || datetime == NULL) {
+	if (session_name == NULL) {
 		return -LTTNG_ERR_INVALID;
 	}
 
 	memset(&lsm, 0, sizeof(lsm));
+	lsm.cmd_type = LTTNG_DATA_PENDING;
 
-	lsm.cmd_type = LTTNG_CREATE_SESSION;
-	lttng_ctl_copy_string(lsm.session.name, name, sizeof(lsm.session.name));
+	lttng_ctl_copy_string(lsm.session.name, session_name,
+			sizeof(lsm.session.name));
 
-	/* There should never be a data URL */
-	size = uri_parse_str_urls(url, NULL, &uris);
-	if (size < 0) {
+	ret = lttng_ctl_ask_sessiond(&lsm, (void **) &pending);
+	if (ret < 0) {
+		goto end;
+	} else if (ret != 1) {
+		/* Unexpected payload size */
 		ret = -LTTNG_ERR_INVALID;
-		goto error;
+		goto end;
 	}
 
-	lsm.u.uri.size = size;
+	ret = (int) *pending;
+end:
+	free(pending);
+	return ret;
+}
 
-	if (size > 0 && uris[0].dtype != LTTNG_DST_PATH && strlen(uris[0].subdir) == 0) {
-		/* Don't append datetime if the name was automatically created. */
-		if (strncmp(name, DEFAULT_SESSION_NAME "-",
-					strlen(DEFAULT_SESSION_NAME) + 1)) {
-			ret = snprintf(uris[0].subdir, sizeof(uris[0].subdir), "%s-%s",
-					name, datetime);
-		} else {
-			ret = snprintf(uris[0].subdir, sizeof(uris[0].subdir), "%s", name);
-		}
-		if (ret < 0) {
-			PERROR("snprintf uri subdir");
-			ret = -LTTNG_ERR_FATAL;
-			goto error;
-		}
+/*
+ * List PIDs in the tracker.
+ *
+ * enabled is set to whether the PID tracker is enabled.
+ * pids is set to an allocated array of PIDs currently tracked. On
+ * success, pids must be freed by the caller.
+ * nr_pids is set to the number of entries contained by the pids array.
+ *
+ * Returns 0 on success, else a negative LTTng error code.
+ */
+int lttng_list_tracker_pids(struct lttng_handle *handle,
+		int *_enabled, int32_t **_pids, size_t *_nr_pids)
+{
+	int ret;
+	int enabled = 1;
+	struct lttcomm_session_msg lsm;
+	size_t nr_pids;
+	int32_t *pids = NULL;
+
+	if (handle == NULL) {
+		return -LTTNG_ERR_INVALID;
 	}
 
-	ret = lttng_ctl_ask_sessiond_varlen(&lsm, uris,
-			sizeof(struct lttng_uri) * size, NULL);
+	memset(&lsm, 0, sizeof(lsm));
+	lsm.cmd_type = LTTNG_LIST_TRACKER_PIDS;
+	lttng_ctl_copy_string(lsm.session.name, handle->session_name,
+			sizeof(lsm.session.name));
+	lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
 
-error:
-	free(uris);
-	return ret;
+	ret = lttng_ctl_ask_sessiond(&lsm, (void **) &pids);
+	if (ret < 0) {
+		return ret;
+	}
+	nr_pids = ret / sizeof(int32_t);
+	if (nr_pids > 0 && !pids) {
+		return -LTTNG_ERR_UNK;
+	}
+	if (nr_pids == 1 && pids[0] == -1) {
+		free(pids);
+		pids = NULL;
+		enabled = 0;
+		nr_pids = 0;
+	}
+	*_enabled = enabled;
+	*_pids = pids;
+	*_nr_pids = nr_pids;
+	return 0;
 }
 
 /*
- * For a given session name, this call checks if the data is ready to be read
- * or is still being extracted by the consumer(s) hence not ready to be used by
- * any readers.
+ * Regenerate the metadata for a session.
+ * Return 0 on success, a negative error code on error.
  */
-int lttng_data_pending(const char *session_name)
+int lttng_regenerate_metadata(const char *session_name)
 {
 	int ret;
 	struct lttcomm_session_msg lsm;
 
-	if (session_name == NULL) {
-		return -LTTNG_ERR_INVALID;
+	if (!session_name) {
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
 	}
 
 	memset(&lsm, 0, sizeof(lsm));
-	lsm.cmd_type = LTTNG_DATA_PENDING;
+	lsm.cmd_type = LTTNG_REGENERATE_METADATA;
 
 	lttng_ctl_copy_string(lsm.session.name, session_name,
 			sizeof(lsm.session.name));
 
 	ret = lttng_ctl_ask_sessiond(&lsm, NULL);
-
-	/*
-	 * The lttng_ctl_ask_sessiond function negate the return code if it's not
-	 * LTTNG_OK so getting -1 means that the reply ret_code was 1 thus meaning
-	 * that the data is available. Yes it is hackish but for now this is the
-	 * only way.
-	 */
-	if (ret == -1) {
-		ret = 1;
+	if (ret < 0) {
+		goto end;
 	}
 
+	ret = 0;
+end:
 	return ret;
 }
 
 /*
- * Create a session exclusively used for snapshot.
- *
- * Returns LTTNG_OK on success or a negative error code.
+ * Deprecated, replaced by lttng_regenerate_metadata.
  */
-int lttng_create_session_snapshot(const char *name, const char *snapshot_url)
+int lttng_metadata_regenerate(const char *session_name)
+{
+	return lttng_regenerate_metadata(session_name);
+}
+
+/*
+ * Regenerate the statedump of a session.
+ * Return 0 on success, a negative error code on error.
+ */
+int lttng_regenerate_statedump(const char *session_name)
 {
 	int ret;
-	ssize_t size;
 	struct lttcomm_session_msg lsm;
-	struct lttng_uri *uris = NULL;
 
-	if (name == NULL) {
-		return -LTTNG_ERR_INVALID;
+	if (!session_name) {
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
 	}
 
 	memset(&lsm, 0, sizeof(lsm));
+	lsm.cmd_type = LTTNG_REGENERATE_STATEDUMP;
 
-	lsm.cmd_type = LTTNG_CREATE_SESSION_SNAPSHOT;
-	lttng_ctl_copy_string(lsm.session.name, name, sizeof(lsm.session.name));
+	lttng_ctl_copy_string(lsm.session.name, session_name,
+			sizeof(lsm.session.name));
 
-	size = uri_parse_str_urls(snapshot_url, NULL, &uris);
-	if (size < 0) {
-		return -LTTNG_ERR_INVALID;
+	ret = lttng_ctl_ask_sessiond(&lsm, NULL);
+	if (ret < 0) {
+		goto end;
 	}
 
-	lsm.u.uri.size = size;
-
-	ret = lttng_ctl_ask_sessiond_varlen(&lsm, uris,
-			sizeof(struct lttng_uri) * size, NULL);
-
-	free(uris);
+	ret = 0;
+end:
 	return ret;
 }
 
-/*
- * Create a session exclusively used for live.
- *
- * Returns LTTNG_OK on success or a negative error code.
- */
-int lttng_create_session_live(const char *name, const char *url,
-		unsigned int timer_interval)
+int lttng_register_trigger(struct lttng_trigger *trigger)
 {
 	int ret;
-	ssize_t size;
 	struct lttcomm_session_msg lsm;
-	struct lttng_uri *uris = NULL;
+	struct lttng_dynamic_buffer buffer;
 
-	if (name == NULL) {
-		return -LTTNG_ERR_INVALID;
+	lttng_dynamic_buffer_init(&buffer);
+	if (!trigger) {
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
 	}
 
-	memset(&lsm, 0, sizeof(lsm));
+	if (!lttng_trigger_validate(trigger)) {
+		ret = -LTTNG_ERR_INVALID_TRIGGER;
+		goto end;
+	}
 
-	lsm.cmd_type = LTTNG_CREATE_SESSION_LIVE;
-	lttng_ctl_copy_string(lsm.session.name, name, sizeof(lsm.session.name));
+	ret = lttng_trigger_serialize(trigger, &buffer);
+	if (ret < 0) {
+		ret = -LTTNG_ERR_UNK;
+		goto end;
+	}
 
-	if (url) {
-		size = uri_parse_str_urls(url, NULL, &uris);
-		if (size <= 0) {
-			ret = -LTTNG_ERR_INVALID;
-			goto end;
-		}
+	memset(&lsm, 0, sizeof(lsm));
+	lsm.cmd_type = LTTNG_REGISTER_TRIGGER;
+	lsm.u.trigger.length = (uint32_t) buffer.size;
+	ret = lttng_ctl_ask_sessiond_varlen_no_cmd_header(&lsm, buffer.data,
+			buffer.size, NULL);
+end:
+	lttng_dynamic_buffer_reset(&buffer);
+	return ret;
+}
 
-		/* file:// is not accepted for live session. */
-		if (uris[0].dtype == LTTNG_DST_PATH) {
-			ret = -LTTNG_ERR_INVALID;
-			goto end;
-		}
-	} else {
-		size = 0;
+int lttng_unregister_trigger(struct lttng_trigger *trigger)
+{
+	int ret;
+	struct lttcomm_session_msg lsm;
+	struct lttng_dynamic_buffer buffer;
+
+	lttng_dynamic_buffer_init(&buffer);
+	if (!trigger) {
+		ret = -LTTNG_ERR_INVALID;
+		goto end;
 	}
 
-	lsm.u.session_live.nb_uri = size;
-	lsm.u.session_live.timer_interval = timer_interval;
+	if (!lttng_trigger_validate(trigger)) {
+		ret = -LTTNG_ERR_INVALID_TRIGGER;
+		goto end;
+	}
 
-	ret = lttng_ctl_ask_sessiond_varlen(&lsm, uris,
-			sizeof(struct lttng_uri) * size, NULL);
+	ret = lttng_trigger_serialize(trigger, &buffer);
+	if (ret < 0) {
+		ret = -LTTNG_ERR_UNK;
+		goto end;
+	}
 
+	memset(&lsm, 0, sizeof(lsm));
+	lsm.cmd_type = LTTNG_UNREGISTER_TRIGGER;
+	lsm.u.trigger.length = (uint32_t) buffer.size;
+	ret = lttng_ctl_ask_sessiond_varlen_no_cmd_header(&lsm, buffer.data,
+			buffer.size, NULL);
 end:
-	free(uris);
+	lttng_dynamic_buffer_reset(&buffer);
 	return ret;
 }
 
 /*
- * lib constructor
+ * lib constructor.
  */
-static void __attribute__((constructor)) init()
+static void __attribute__((constructor)) init(void)
 {
 	/* Set default session group */
 	lttng_set_tracing_group(DEFAULT_TRACING_GROUP);
 }
 
 /*
- * lib destructor
+ * lib destructor.
  */
-static void __attribute__((destructor)) lttng_ctl_exit()
+static void __attribute__((destructor)) lttng_ctl_exit(void)
 {
 	free(tracing_group);
 }