From 9a0fa4458e73d7a9d7245d6b4c1432f1e612f74e Mon Sep 17 00:00:00 2001
From: =?utf8?q?J=C3=A9r=C3=A9mie=20Galarneau?=
 <jeremie.galarneau@efficios.com>
Date: Fri, 22 Jan 2016 16:23:43 -0500
Subject: [PATCH 01/16] Cleanup comments in lttng-ctl.c
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---
 src/lib/lttng-ctl/lttng-ctl.c | 245 ++++++++++++++++++----------------
 1 file changed, 133 insertions(+), 112 deletions(-)

diff --git a/src/lib/lttng-ctl/lttng-ctl.c b/src/lib/lttng-ctl/lttng-ctl.c
index 665aba57d..0dcd673eb 100644
--- a/src/lib/lttng-ctl/lttng-ctl.c
+++ b/src/lib/lttng-ctl/lttng-ctl.c
@@ -197,9 +197,9 @@ 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)
@@ -268,7 +268,7 @@ 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;
 	}
 
@@ -292,7 +292,7 @@ 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();
@@ -311,7 +311,7 @@ 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;
@@ -321,8 +321,10 @@ 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());
@@ -338,9 +340,9 @@ 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)
 {
@@ -356,7 +358,7 @@ 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;
@@ -373,6 +375,7 @@ error:
 
 /*
  *  Clean disconnect from the session daemon.
+ *
  *  On success, return 0. On error, return -1.
  */
 static int disconnect_sessiond(void)
@@ -478,6 +481,7 @@ 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,
@@ -516,6 +520,7 @@ 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,
@@ -533,14 +538,16 @@ 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)
 {
@@ -596,8 +603,8 @@ 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);
@@ -639,7 +646,7 @@ int lttng_add_context(struct lttng_handle *handle,
 {
 	struct lttcomm_session_msg lsm;
 
-	/* Safety check. Both are mandatory */
+	/* Safety check. Both are mandatory. */
 	if (handle == NULL || ctx == NULL) {
 		return -LTTNG_ERR_INVALID;
 	}
@@ -668,10 +675,12 @@ int lttng_add_context(struct lttng_handle *handle,
 }
 
 /*
- *  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)
@@ -831,7 +840,7 @@ static int generate_filter(char *filter_expression,
 		ret = -LTTNG_ERR_FILTER_INVAL;
 		goto parse_error;
 	}
-	/* Validate strings used as literals in the expression */
+	/* Validate strings used as literals in the expression. */
 	ret = filter_visitor_ir_validate_string(ctx);
 	if (ret) {
 		ret = -LTTNG_ERR_FILTER_INVAL;
@@ -904,7 +913,8 @@ 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.
 	 */
@@ -953,10 +963,10 @@ int lttng_enable_event_with_exclusions(struct lttng_handle *handle,
 
 	/*
 	 * 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
+	 * 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) {
@@ -969,13 +979,17 @@ 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;
@@ -996,20 +1010,20 @@ int lttng_enable_event_with_exclusions(struct lttng_handle *handle,
 		goto mem_error;
 	}
 
-	/* Put exclusion names first in the data */
+	/* 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 - 1);
 	}
-	/* Add filter expression next */
+	/* 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 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
@@ -1020,7 +1034,8 @@ int lttng_enable_event_with_exclusions(struct lttng_handle *handle,
 
 	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);
+			lsm.u.enable.bytecode_len + lsm.u.enable.expression_len,
+			NULL);
 	free(varlen_data);
 
 mem_error:
@@ -1032,15 +1047,16 @@ 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;
 
@@ -1070,7 +1086,8 @@ 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.
 	 */
@@ -1130,13 +1147,17 @@ 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;
@@ -1156,13 +1177,13 @@ 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,
@@ -1183,15 +1204,16 @@ 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;
 
@@ -1201,10 +1223,10 @@ 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)
@@ -1219,17 +1241,15 @@ int lttng_disable_event(struct lttng_handle *handle, const char *name,
 }
 
 /*
- *  Enable channel per domain
- *  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_enable_channel(struct lttng_handle *handle,
 		struct lttng_channel *chan)
 {
 	struct lttcomm_session_msg lsm;
 
-	/*
-	 * NULL arguments are forbidden. No default values.
-	 */
+	/* NULL arguments are forbidden. No default values. */
 	if (handle == NULL || chan == NULL) {
 		return -LTTNG_ERR_INVALID;
 	}
@@ -1249,14 +1269,14 @@ int lttng_enable_channel(struct lttng_handle *handle,
 }
 
 /*
- *  All tracing will be stopped for registered events of the channel.
- *  Returns size of returned session payload data or a negative error code.
+ * 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 */
+	/* Safety check. Both are mandatory. */
 	if (handle == NULL || name == NULL) {
 		return -LTTNG_ERR_INVALID;
 	}
@@ -1277,16 +1297,14 @@ int lttng_disable_channel(struct lttng_handle *handle, const char *name)
 }
 
 /*
- *  Add PID to session tracker.
- *  Return 0 on success else a negative LTTng error code.
+ * 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.
-	 */
+	/* NULL arguments are forbidden. No default values. */
 	if (handle == NULL) {
 		return -LTTNG_ERR_INVALID;
 	}
@@ -1305,16 +1323,14 @@ int lttng_track_pid(struct lttng_handle *handle, int pid)
 }
 
 /*
- *  Remove PID from session tracker.
- *  Return 0 on success else a negative LTTng error code.
+ * 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.
-	 */
+	/* NULL arguments are forbidden. No default values. */
 	if (handle == NULL) {
 		return -LTTNG_ERR_INVALID;
 	}
@@ -1333,10 +1349,10 @@ int lttng_untrack_pid(struct lttng_handle *handle, int pid)
 }
 
 /*
- *  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.
+ * 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)
@@ -1361,10 +1377,10 @@ 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)
@@ -1389,11 +1405,11 @@ 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)
 {
@@ -1418,8 +1434,8 @@ 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)
 {
@@ -1463,8 +1479,8 @@ int lttng_create_session(const char *name, const char *url)
 }
 
 /*
- *  Destroy session using name.
- *  Returns size of returned session payload data or a negative error code.
+ * Destroy session using name.
+ * Returns size of returned session payload data or a negative error code.
  */
 int lttng_destroy_session(const char *session_name)
 {
@@ -1484,10 +1500,10 @@ 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.
+ * 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 **sessions)
 {
@@ -1525,10 +1541,10 @@ 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)
@@ -1555,10 +1571,10 @@ 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)
@@ -1586,10 +1602,10 @@ int lttng_list_channels(struct lttng_handle *handle,
 }
 
 /*
- *  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)
@@ -1680,7 +1696,8 @@ 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;
@@ -1692,16 +1709,20 @@ 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;
 			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;
 			break;
 		}
 	default:
@@ -1722,25 +1743,25 @@ 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;
 }
 
@@ -1834,7 +1855,7 @@ int _lttng_create_session_ext(const char *name, const char *url,
 	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 */
+	/* There should never be a data URL. */
 	size = uri_parse_str_urls(url, NULL, &uris);
 	if (size < 0) {
 		ret = -LTTNG_ERR_INVALID;
@@ -2034,7 +2055,7 @@ int lttng_list_tracker_pids(struct lttng_handle *handle,
 }
 
 /*
- * lib constructor
+ * lib constructor.
  */
 static void __attribute__((constructor)) init()
 {
@@ -2043,7 +2064,7 @@ static void __attribute__((constructor)) init()
 }
 
 /*
- * lib destructor
+ * lib destructor.
  */
 static void __attribute__((destructor)) lttng_ctl_exit()
 {
-- 
2.34.1


From 72316fcf465b4aad870d422dca8cae5214d917ec Mon Sep 17 00:00:00 2001
From: =?utf8?q?J=C3=A9r=C3=A9mie=20Galarneau?=
 <jeremie.galarneau@efficios.com>
Date: Tue, 26 Jan 2016 11:42:45 -0500
Subject: [PATCH 02/16] Add application context support to lttng-ctl
 lttng_add_context
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

Forward the provider and context names of app contexts to the
session daemon.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---
 include/lttng/event.h                    | 34 +++++++-----
 src/bin/lttng-sessiond/main.c            | 69 +++++++++++++++++++++++-
 src/common/sessiond-comm/sessiond-comm.h |  2 +
 src/lib/lttng-ctl/lttng-ctl.c            | 55 ++++++++++++++++---
 4 files changed, 138 insertions(+), 22 deletions(-)

diff --git a/include/lttng/event.h b/include/lttng/event.h
index 3e8fbe3e8..e5b2b4bb0 100644
--- a/include/lttng/event.h
+++ b/include/lttng/event.h
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2014 - David Goulet <dgoulet@efficios.com>
+ * 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,
@@ -121,21 +122,22 @@ enum lttng_event_output {
 
 /* Event context possible type */
 enum lttng_event_context_type {
-	LTTNG_EVENT_CONTEXT_PID               = 0,
-	LTTNG_EVENT_CONTEXT_PERF_COUNTER      = 1,	/* Backward compat. */
-	LTTNG_EVENT_CONTEXT_PROCNAME          = 2,
-	LTTNG_EVENT_CONTEXT_PRIO              = 3,
-	LTTNG_EVENT_CONTEXT_NICE              = 4,
-	LTTNG_EVENT_CONTEXT_VPID              = 5,
-	LTTNG_EVENT_CONTEXT_TID               = 6,
-	LTTNG_EVENT_CONTEXT_VTID              = 7,
-	LTTNG_EVENT_CONTEXT_PPID              = 8,
-	LTTNG_EVENT_CONTEXT_VPPID             = 9,
-	LTTNG_EVENT_CONTEXT_PTHREAD_ID        = 10,
-	LTTNG_EVENT_CONTEXT_HOSTNAME          = 11,
-	LTTNG_EVENT_CONTEXT_IP                = 12,
-	LTTNG_EVENT_CONTEXT_PERF_CPU_COUNTER  = 13,
+	LTTNG_EVENT_CONTEXT_PID			= 0,
+	LTTNG_EVENT_CONTEXT_PERF_COUNTER	= 1,	/* Backward compat. */
+	LTTNG_EVENT_CONTEXT_PROCNAME		= 2,
+	LTTNG_EVENT_CONTEXT_PRIO		= 3,
+	LTTNG_EVENT_CONTEXT_NICE		= 4,
+	LTTNG_EVENT_CONTEXT_VPID		= 5,
+	LTTNG_EVENT_CONTEXT_TID			= 6,
+	LTTNG_EVENT_CONTEXT_VTID		= 7,
+	LTTNG_EVENT_CONTEXT_PPID		= 8,
+	LTTNG_EVENT_CONTEXT_VPPID		= 9,
+	LTTNG_EVENT_CONTEXT_PTHREAD_ID		= 10,
+	LTTNG_EVENT_CONTEXT_HOSTNAME		= 11,
+	LTTNG_EVENT_CONTEXT_IP			= 12,
+	LTTNG_EVENT_CONTEXT_PERF_CPU_COUNTER	= 13,
 	LTTNG_EVENT_CONTEXT_PERF_THREAD_COUNTER = 14,
+	LTTNG_EVENT_CONTEXT_APP_CONTEXT		= 15,
 };
 
 enum lttng_event_field_type {
@@ -178,6 +180,10 @@ struct lttng_event_context {
 
 	union {
 		struct lttng_event_perf_counter_ctx perf_counter;
+		struct {
+			char *provider_name;
+			char *ctx_name;
+		} app_ctx;
 		char padding[LTTNG_EVENT_CONTEXT_PADDING2];
 	} u;
 };
diff --git a/src/bin/lttng-sessiond/main.c b/src/bin/lttng-sessiond/main.c
index c1f466ed7..7a8b5ae42 100644
--- a/src/bin/lttng-sessiond/main.c
+++ b/src/bin/lttng-sessiond/main.c
@@ -3343,9 +3343,74 @@ skip_domain:
 	switch (cmd_ctx->lsm->cmd_type) {
 	case LTTNG_ADD_CONTEXT:
 	{
-		ret = cmd_add_context(cmd_ctx->session, cmd_ctx->lsm->domain.type,
+		/*
+		 * An LTTNG_ADD_CONTEXT command might have a supplementary
+		 * payload if the context being added is an application context.
+		 */
+		if (cmd_ctx->lsm->u.context.ctx.ctx ==
+				LTTNG_EVENT_CONTEXT_APP_CONTEXT) {
+			char *provider_name = NULL, *context_name = NULL;
+			size_t provider_name_len =
+					cmd_ctx->lsm->u.context.provider_name_len;
+			size_t context_name_len =
+					cmd_ctx->lsm->u.context.context_name_len;
+
+			if (provider_name_len == 0 || context_name_len == 0) {
+				/*
+				 * Application provider and context names MUST
+				 * be provided.
+				 */
+				ret = -LTTNG_ERR_INVALID;
+				goto error;
+			}
+
+			provider_name = zmalloc(provider_name_len + 1);
+			if (!provider_name) {
+				ret = -LTTNG_ERR_NOMEM;
+				goto error;
+			}
+
+			context_name = zmalloc(context_name_len + 1);
+			if (!context_name) {
+				ret = -LTTNG_ERR_NOMEM;
+				goto error_add_context;
+			}
+
+			ret = lttcomm_recv_unix_sock(sock, provider_name,
+					provider_name_len);
+			if (ret < 0) {
+				goto error_add_context;
+			}
+
+			ret = lttcomm_recv_unix_sock(sock, context_name,
+					context_name_len);
+			if (ret < 0) {
+				goto error_add_context;
+			}
+			cmd_ctx->lsm->u.context.ctx.u.app_ctx.provider_name =
+					provider_name;
+			cmd_ctx->lsm->u.context.ctx.u.app_ctx.ctx_name =
+					context_name;
+		}
+
+		/*
+		 * cmd_add_context assumes ownership of the provider and context
+		 * names.
+		 */
+		ret = cmd_add_context(cmd_ctx->session,
+				cmd_ctx->lsm->domain.type,
 				cmd_ctx->lsm->u.context.channel_name,
-				&cmd_ctx->lsm->u.context.ctx, kernel_poll_pipe[1]);
+				&cmd_ctx->lsm->u.context.ctx,
+				kernel_poll_pipe[1]);
+
+		cmd_ctx->lsm->u.context.ctx.u.app_ctx.provider_name = NULL;
+		cmd_ctx->lsm->u.context.ctx.u.app_ctx.ctx_name = NULL;
+error_add_context:
+		free(cmd_ctx->lsm->u.context.ctx.u.app_ctx.provider_name);
+		free(cmd_ctx->lsm->u.context.ctx.u.app_ctx.ctx_name);
+		if (ret < 0) {
+			goto error;
+		}
 		break;
 	}
 	case LTTNG_DISABLE_CHANNEL:
diff --git a/src/common/sessiond-comm/sessiond-comm.h b/src/common/sessiond-comm/sessiond-comm.h
index 778618876..4a204c02e 100644
--- a/src/common/sessiond-comm/sessiond-comm.h
+++ b/src/common/sessiond-comm/sessiond-comm.h
@@ -270,6 +270,8 @@ struct lttcomm_session_msg {
 		struct {
 			char channel_name[LTTNG_SYMBOL_NAME_LEN];
 			struct lttng_event_context ctx LTTNG_PACKED;
+			uint32_t provider_name_len;
+			uint32_t context_name_len;
 		} LTTNG_PACKED context;
 		/* Use by register_consumer */
 		struct {
diff --git a/src/lib/lttng-ctl/lttng-ctl.c b/src/lib/lttng-ctl/lttng-ctl.c
index 0dcd673eb..03b74c0b7 100644
--- a/src/lib/lttng-ctl/lttng-ctl.c
+++ b/src/lib/lttng-ctl/lttng-ctl.c
@@ -4,6 +4,7 @@
  * 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,
@@ -644,15 +645,18 @@ 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. */
 	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. */
@@ -665,13 +669,52 @@ int lttng_add_context(struct lttng_handle *handle,
 	}
 
 	lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
-
-	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));
 
-	return lttng_ctl_ask_sessiond(&lsm, NULL);
+	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));
+	/* Don't leak application addresses to the sessiond. */
+	lsm.u.context.ctx.u.app_ctx.provider_name = NULL;
+	lsm.u.context.ctx.u.app_ctx.ctx_name = NULL;
+
+	ret = lttng_ctl_ask_sessiond_varlen(&lsm, buf, len, NULL);
+end:
+	free(buf);
+	return ret;
 }
 
 /*
-- 
2.34.1


From 8ef030a7bff927ba186a69156cce57490fc5ccde Mon Sep 17 00:00:00 2001
From: =?utf8?q?J=C3=A9r=C3=A9mie=20Galarneau?=
 <jeremie.galarneau@efficios.com>
Date: Tue, 26 Jan 2016 11:44:12 -0500
Subject: [PATCH 03/16] Use lttng_domain_type enum instead of bare integer
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---
 src/bin/lttng-sessiond/context.c | 8 +++++---
 src/bin/lttng-sessiond/context.h | 5 +++--
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/src/bin/lttng-sessiond/context.c b/src/bin/lttng-sessiond/context.c
index 866a039e7..be15cebd2 100644
--- a/src/bin/lttng-sessiond/context.c
+++ b/src/bin/lttng-sessiond/context.c
@@ -87,7 +87,8 @@ error:
 /*
  * Add UST context to channel.
  */
-static int add_uctx_to_channel(struct ltt_ust_session *usess, int domain,
+static int add_uctx_to_channel(struct ltt_ust_session *usess,
+		enum lttng_domain_type domain,
 		struct ltt_ust_channel *uchan, struct lttng_event_context *ctx)
 {
 	int ret;
@@ -239,8 +240,9 @@ error:
 /*
  * Add UST context to tracer.
  */
-int context_ust_add(struct ltt_ust_session *usess, int domain,
-		struct lttng_event_context *ctx, char *channel_name)
+int context_ust_add(struct ltt_ust_session *usess,
+		enum lttng_domain_type domain, struct lttng_event_context *ctx,
+		char *channel_name)
 {
 	int ret = LTTNG_OK;
 	struct lttng_ht_iter iter;
diff --git a/src/bin/lttng-sessiond/context.h b/src/bin/lttng-sessiond/context.h
index e3047761b..01b35167e 100644
--- a/src/bin/lttng-sessiond/context.h
+++ b/src/bin/lttng-sessiond/context.h
@@ -26,7 +26,8 @@
 
 int context_kernel_add(struct ltt_kernel_session *ksession,
 		struct lttng_event_context *ctx, char *channel_name);
-int context_ust_add(struct ltt_ust_session *usess, int domain,
-		struct lttng_event_context *ctx, char *channel_name);
+int context_ust_add(struct ltt_ust_session *usess,
+		enum lttng_domain_type domain, struct lttng_event_context *ctx,
+		char *channel_name);
 
 #endif /* _LTT_CONTEXT_H */
-- 
2.34.1


From 8df907cb3e58910e3588c6cdc384dafc81963a22 Mon Sep 17 00:00:00 2001
From: =?utf8?q?J=C3=A9r=C3=A9mie=20Galarneau?=
 <jeremie.galarneau@efficios.com>
Date: Tue, 26 Jan 2016 11:45:42 -0500
Subject: [PATCH 04/16] Remove superflous domain check in add_uctx_to_channel
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---
 src/bin/lttng-sessiond/context.c | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/src/bin/lttng-sessiond/context.c b/src/bin/lttng-sessiond/context.c
index be15cebd2..941ab2535 100644
--- a/src/bin/lttng-sessiond/context.c
+++ b/src/bin/lttng-sessiond/context.c
@@ -97,6 +97,7 @@ static int add_uctx_to_channel(struct ltt_ust_session *usess,
 	assert(usess);
 	assert(uchan);
 	assert(ctx);
+	assert(domain == LTTNG_DOMAIN_UST);
 
 	/* Check if context is duplicate */
 	cds_list_for_each_entry(uctx, &uchan->ctx_list, list) {
@@ -113,15 +114,8 @@ static int add_uctx_to_channel(struct ltt_ust_session *usess,
 		goto error;
 	}
 
-	switch (domain) {
-	case LTTNG_DOMAIN_UST:
-		ret = ust_app_add_ctx_channel_glb(usess, uchan, uctx);
-		if (ret < 0) {
-			goto error;
-		}
-		break;
-	default:
-		ret = -ENOSYS;
+	ret = ust_app_add_ctx_channel_glb(usess, uchan, uctx);
+	if (ret < 0) {
 		goto error;
 	}
 
-- 
2.34.1


From 5235bf17705eb1e731486605cfd040801745b032 Mon Sep 17 00:00:00 2001
From: =?utf8?q?J=C3=A9r=C3=A9mie=20Galarneau?=
 <jeremie.galarneau@efficios.com>
Date: Tue, 26 Jan 2016 11:46:17 -0500
Subject: [PATCH 05/16] Remove superflous domain check in context_ust_add
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---
 src/bin/lttng-sessiond/context.c | 14 ++------------
 1 file changed, 2 insertions(+), 12 deletions(-)

diff --git a/src/bin/lttng-sessiond/context.c b/src/bin/lttng-sessiond/context.c
index 941ab2535..ffd6e3ad5 100644
--- a/src/bin/lttng-sessiond/context.c
+++ b/src/bin/lttng-sessiond/context.c
@@ -246,21 +246,11 @@ int context_ust_add(struct ltt_ust_session *usess,
 	assert(usess);
 	assert(ctx);
 	assert(channel_name);
+	assert(domain == LTTNG_DOMAIN_UST);
 
 	rcu_read_lock();
 
-	/*
-	 * Define which channel's hashtable to use from the domain or quit if
-	 * unknown domain.
-	 */
-	switch (domain) {
-	case LTTNG_DOMAIN_UST:
-		chan_ht = usess->domain_global.channels;
-		break;
-	default:
-		ret = LTTNG_ERR_UND;
-		goto error;
-	}
+	chan_ht = usess->domain_global.channels;
 
 	/* Get UST channel if defined */
 	if (channel_name[0] != '\0') {
-- 
2.34.1


From 885b6cbc5396dd88637c0cb53ab60eda0a513274 Mon Sep 17 00:00:00 2001
From: =?utf8?q?J=C3=A9r=C3=A9mie=20Galarneau?=
 <jeremie.galarneau@efficios.com>
Date: Tue, 26 Jan 2016 11:46:48 -0500
Subject: [PATCH 06/16] Enforce const-correctness in UNIX socket wrappers
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---
 src/common/sessiond-comm/inet.c          | 4 ++--
 src/common/sessiond-comm/inet.h          | 4 ++--
 src/common/sessiond-comm/inet6.c         | 4 ++--
 src/common/sessiond-comm/inet6.h         | 4 ++--
 src/common/sessiond-comm/sessiond-comm.h | 4 ++--
 src/common/sessiond-comm/unix.c          | 4 ++--
 src/common/sessiond-comm/unix.h          | 2 +-
 src/lib/lttng-ctl/lttng-ctl-helper.h     | 4 ++--
 src/lib/lttng-ctl/lttng-ctl.c            | 4 ++--
 9 files changed, 17 insertions(+), 17 deletions(-)

diff --git a/src/common/sessiond-comm/inet.c b/src/common/sessiond-comm/inet.c
index 35ce3b6b5..b870deef4 100644
--- a/src/common/sessiond-comm/inet.c
+++ b/src/common/sessiond-comm/inet.c
@@ -407,7 +407,7 @@ ssize_t lttcomm_recvmsg_inet_sock(struct lttcomm_sock *sock, void *buf,
  * Return the size of sent data.
  */
 LTTNG_HIDDEN
-ssize_t lttcomm_sendmsg_inet_sock(struct lttcomm_sock *sock, void *buf,
+ssize_t lttcomm_sendmsg_inet_sock(struct lttcomm_sock *sock, const void *buf,
 		size_t len, int flags)
 {
 	struct msghdr msg;
@@ -416,7 +416,7 @@ ssize_t lttcomm_sendmsg_inet_sock(struct lttcomm_sock *sock, void *buf,
 
 	memset(&msg, 0, sizeof(msg));
 
-	iov[0].iov_base = buf;
+	iov[0].iov_base = (void *) buf;
 	iov[0].iov_len = len;
 	msg.msg_iov = iov;
 	msg.msg_iovlen = 1;
diff --git a/src/common/sessiond-comm/inet.h b/src/common/sessiond-comm/inet.h
index 6a79c9106..03549fabd 100644
--- a/src/common/sessiond-comm/inet.h
+++ b/src/common/sessiond-comm/inet.h
@@ -57,8 +57,8 @@ extern int lttcomm_listen_inet_sock(struct lttcomm_sock *sock, int backlog);
 
 extern ssize_t lttcomm_recvmsg_inet_sock(struct lttcomm_sock *sock, void *buf,
 		size_t len, int flags);
-extern ssize_t lttcomm_sendmsg_inet_sock(struct lttcomm_sock *sock, void *buf,
-		size_t len, int flags);
+extern ssize_t lttcomm_sendmsg_inet_sock(struct lttcomm_sock *sock,
+		const void *buf, size_t len, int flags);
 
 /* Initialize inet communication layer. */
 extern void lttcomm_inet_init(void);
diff --git a/src/common/sessiond-comm/inet6.c b/src/common/sessiond-comm/inet6.c
index a29adad42..51d02ebb9 100644
--- a/src/common/sessiond-comm/inet6.c
+++ b/src/common/sessiond-comm/inet6.c
@@ -386,7 +386,7 @@ ssize_t lttcomm_recvmsg_inet6_sock(struct lttcomm_sock *sock, void *buf,
  * Return the size of sent data.
  */
 LTTNG_HIDDEN
-ssize_t lttcomm_sendmsg_inet6_sock(struct lttcomm_sock *sock, void *buf,
+ssize_t lttcomm_sendmsg_inet6_sock(struct lttcomm_sock *sock, const void *buf,
 		size_t len, int flags)
 {
 	struct msghdr msg;
@@ -395,7 +395,7 @@ ssize_t lttcomm_sendmsg_inet6_sock(struct lttcomm_sock *sock, void *buf,
 
 	memset(&msg, 0, sizeof(msg));
 
-	iov[0].iov_base = buf;
+	iov[0].iov_base = (void *) buf;
 	iov[0].iov_len = len;
 	msg.msg_iov = iov;
 	msg.msg_iovlen = 1;
diff --git a/src/common/sessiond-comm/inet6.h b/src/common/sessiond-comm/inet6.h
index 3af3be5be..5c2ed5371 100644
--- a/src/common/sessiond-comm/inet6.h
+++ b/src/common/sessiond-comm/inet6.h
@@ -38,7 +38,7 @@ extern int lttcomm_listen_inet6_sock(struct lttcomm_sock *sock, int backlog);
 
 extern ssize_t lttcomm_recvmsg_inet6_sock(struct lttcomm_sock *sock, void *buf,
 		size_t len, int flags);
-extern ssize_t lttcomm_sendmsg_inet6_sock(struct lttcomm_sock *sock, void *buf,
-		size_t len, int flags);
+extern ssize_t lttcomm_sendmsg_inet6_sock(struct lttcomm_sock *sock,
+		const void *buf, size_t len, int flags);
 
 #endif	/* _LTTCOMM_INET6_H */
diff --git a/src/common/sessiond-comm/sessiond-comm.h b/src/common/sessiond-comm/sessiond-comm.h
index 4a204c02e..ec7d36ae5 100644
--- a/src/common/sessiond-comm/sessiond-comm.h
+++ b/src/common/sessiond-comm/sessiond-comm.h
@@ -218,8 +218,8 @@ struct lttcomm_proto_ops {
 	int (*listen) (struct lttcomm_sock *sock, int backlog);
 	ssize_t (*recvmsg) (struct lttcomm_sock *sock, void *buf, size_t len,
 			int flags);
-	ssize_t (*sendmsg) (struct lttcomm_sock *sock, void *buf, size_t len,
-			int flags);
+	ssize_t (*sendmsg) (struct lttcomm_sock *sock, const void *buf,
+			size_t len, int flags);
 };
 
 /*
diff --git a/src/common/sessiond-comm/unix.c b/src/common/sessiond-comm/unix.c
index 5e0ba6281..8d2e03a5b 100644
--- a/src/common/sessiond-comm/unix.c
+++ b/src/common/sessiond-comm/unix.c
@@ -205,7 +205,7 @@ ssize_t lttcomm_recv_unix_sock(int sock, void *buf, size_t len)
  * Return the size of sent data.
  */
 LTTNG_HIDDEN
-ssize_t lttcomm_send_unix_sock(int sock, void *buf, size_t len)
+ssize_t lttcomm_send_unix_sock(int sock, const void *buf, size_t len)
 {
 	struct msghdr msg;
 	struct iovec iov[1];
@@ -213,7 +213,7 @@ ssize_t lttcomm_send_unix_sock(int sock, void *buf, size_t len)
 
 	memset(&msg, 0, sizeof(msg));
 
-	iov[0].iov_base = buf;
+	iov[0].iov_base = (void *) buf;
 	iov[0].iov_len = len;
 	msg.msg_iov = iov;
 	msg.msg_iovlen = 1;
diff --git a/src/common/sessiond-comm/unix.h b/src/common/sessiond-comm/unix.h
index 7ea05032f..24786b8fe 100644
--- a/src/common/sessiond-comm/unix.h
+++ b/src/common/sessiond-comm/unix.h
@@ -49,7 +49,7 @@ ssize_t lttcomm_recv_fds_unix_sock(int sock, int *fds, size_t nb_fd);
 LTTNG_HIDDEN
 ssize_t lttcomm_recv_unix_sock(int sock, void *buf, size_t len);
 LTTNG_HIDDEN
-ssize_t lttcomm_send_unix_sock(int sock, void *buf, size_t len);
+ssize_t lttcomm_send_unix_sock(int sock, const void *buf, size_t len);
 
 LTTNG_HIDDEN
 ssize_t lttcomm_send_creds_unix_sock(int sock, void *buf, size_t len);
diff --git a/src/lib/lttng-ctl/lttng-ctl-helper.h b/src/lib/lttng-ctl/lttng-ctl-helper.h
index 5f6d5c209..b7a28268c 100644
--- a/src/lib/lttng-ctl/lttng-ctl-helper.h
+++ b/src/lib/lttng-ctl/lttng-ctl-helper.h
@@ -35,14 +35,14 @@ void lttng_ctl_copy_lttng_domain(struct lttng_domain *dst,
 		struct lttng_domain *src);
 
 /*
- * Sends the lttcomm message to the session daemon and fills buf of the
+ * Sends the lttcomm message to the session daemon and fills buf if the
  * returned data is not NULL.
  *
  * Return the size of the received data on success or else a negative lttng
  * error code. If buf is NULL, 0 is returned on success.
  */
 int lttng_ctl_ask_sessiond_varlen(struct lttcomm_session_msg *lsm,
-		void *vardata, size_t varlen, void **buf);
+		const void *vardata, size_t varlen, void **buf);
 
 /*
  * Use this if no variable length data needs to be sent.
diff --git a/src/lib/lttng-ctl/lttng-ctl.c b/src/lib/lttng-ctl/lttng-ctl.c
index 03b74c0b7..14bb7b32d 100644
--- a/src/lib/lttng-ctl/lttng-ctl.c
+++ b/src/lib/lttng-ctl/lttng-ctl.c
@@ -150,7 +150,7 @@ 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;
 
@@ -400,7 +400,7 @@ static int disconnect_sessiond(void)
  */
 LTTNG_HIDDEN
 int lttng_ctl_ask_sessiond_varlen(struct lttcomm_session_msg *lsm,
-		void *vardata, size_t varlen, void **buf)
+		const void *vardata, size_t varlen, void **buf)
 {
 	int ret;
 	size_t size;
-- 
2.34.1


From 5b2f9c4dd9ef66cbf9253955653324281eac263b Mon Sep 17 00:00:00 2001
From: =?utf8?q?J=C3=A9r=C3=A9mie=20Galarneau?=
 <jeremie.galarneau@efficios.com>
Date: Wed, 27 Jan 2016 19:01:50 -0500
Subject: [PATCH 07/16] Add app context support to lttng client
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---
 src/bin/lttng/commands/add_context.c | 214 ++++++++++++++++++++++-----
 1 file changed, 177 insertions(+), 37 deletions(-)

diff --git a/src/bin/lttng/commands/add_context.c b/src/bin/lttng/commands/add_context.c
index fb37c0aa7..d58ee908b 100644
--- a/src/bin/lttng/commands/add_context.c
+++ b/src/bin/lttng/commands/add_context.c
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
+ * Copyright (C) 2016 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License, version 2 only,
@@ -38,12 +39,16 @@ static char *opt_channel_name;
 static char *opt_session_name;
 static int opt_kernel;
 static int opt_userspace;
+static int opt_jul;
+static int opt_log4j;
 static char *opt_type;
 
 enum {
 	OPT_HELP = 1,
 	OPT_TYPE,
 	OPT_USERSPACE,
+	OPT_JUL,
+	OPT_LOG4J,
 	OPT_LIST_OPTIONS,
 };
 
@@ -69,6 +74,7 @@ enum context_type {
 	CONTEXT_IP           = 12,
 	CONTEXT_PERF_CPU_COUNTER = 13,
 	CONTEXT_PERF_THREAD_COUNTER = 14,
+	CONTEXT_APP_CONTEXT  = 15,
 };
 
 /*
@@ -144,6 +150,8 @@ static struct poptOption long_options[] = {
 	{"channel",        'c', POPT_ARG_STRING, &opt_channel_name, 0, 0, 0},
 	{"kernel",         'k', POPT_ARG_VAL, &opt_kernel, 1, 0, 0},
 	{"userspace",      'u', POPT_ARG_NONE, 0, OPT_USERSPACE, 0, 0},
+	{"jul",            'j', POPT_ARG_NONE, 0, OPT_JUL, 0, 0},
+	{"log4j",          'l', POPT_ARG_NONE, 0, OPT_LOG4J, 0, 0},
 	{"type",           't', POPT_ARG_STRING, &opt_type, OPT_TYPE, 0, 0},
 	{"list-options",   0, POPT_ARG_NONE, NULL, OPT_LIST_OPTIONS, NULL, NULL},
 	{0, 0, 0, 0, 0, 0, 0}
@@ -199,6 +207,10 @@ const struct ctx_opts {
 			uint32_t type;
 			uint64_t config;
 		} perf;
+		struct {
+			char *provider_name;
+			char *ctx_name;
+		} app_ctx;
 	} u;
 } ctx_opts[] = {
 	{ "pid", CONTEXT_PID },
@@ -441,7 +453,7 @@ const struct ctx_opts {
  * Context type for command line option parsing.
  */
 struct ctx_type {
-	const struct ctx_opts *opt;
+	struct ctx_opts *opt;
 	struct cds_list_head list;
 };
 
@@ -505,6 +517,8 @@ static void usage(FILE *ofp)
 	fprintf(ofp, "  -c, --channel NAME       Apply to channel\n");
 	fprintf(ofp, "  -k, --kernel             Apply to the kernel tracer\n");
 	fprintf(ofp, "  -u, --userspace          Apply to the user-space tracer\n");
+	fprintf(ofp, "  -j, --jul                Apply to Java application using JUL\n");
+	fprintf(ofp, "  -l, --log4j              Apply for Java application using LOG4j\n");
 	fprintf(ofp, "\n");
 	fprintf(ofp, "Context:\n");
 	fprintf(ofp, "  -t, --type TYPE          Context type. You can repeat that option on\n");
@@ -526,10 +540,12 @@ static void usage(FILE *ofp)
 
 /*
  * Find context numerical value from string.
+ *
+ * Return -1 if not found.
  */
 static int find_ctx_type_idx(const char *opt)
 {
-	int ret = -1, i = 0;
+	int ret, i = 0;
 
 	while (ctx_opts[i].symbol != NULL) {
 		if (strcmp(opt, ctx_opts[i].symbol) == 0) {
@@ -539,10 +555,27 @@ static int find_ctx_type_idx(const char *opt)
 		i++;
 	}
 
+	ret = -1;
 end:
 	return ret;
 }
 
+static
+enum lttng_domain_type get_domain(void)
+{
+	if (opt_kernel) {
+		return LTTNG_DOMAIN_KERNEL;
+	} else if (opt_userspace) {
+		return LTTNG_DOMAIN_UST;
+	} else if (opt_jul) {
+		return LTTNG_DOMAIN_JUL;
+	} else if (opt_log4j) {
+		return LTTNG_DOMAIN_LOG4J;
+	} else {
+		assert(0);
+	}
+}
+
 /*
  * Add context to channel or event.
  */
@@ -557,14 +590,7 @@ static int add_context(char *session_name)
 	memset(&context, 0, sizeof(context));
 	memset(&dom, 0, sizeof(dom));
 
-	if (opt_kernel) {
-		dom.type = LTTNG_DOMAIN_KERNEL;
-	} else if (opt_userspace) {
-		dom.type = LTTNG_DOMAIN_UST;
-	} else {
-		assert(0);
-	}
-
+	dom.type = get_domain();
 	handle = lttng_create_handle(session_name, &dom);
 	if (handle == NULL) {
 		ret = CMD_ERROR;
@@ -599,6 +625,12 @@ static int add_context(char *session_name)
 				*ptr = '_';
 			}
 			break;
+		case LTTNG_EVENT_CONTEXT_APP_CONTEXT:
+			context.u.app_ctx.provider_name =
+					type->opt->u.app_ctx.provider_name;
+			context.u.app_ctx.ctx_name =
+					type->opt->u.app_ctx.ctx_name;
+			break;
 		default:
 			break;
 		}
@@ -671,12 +703,132 @@ error:
 	return ret;
 }
 
+static
+void destroy_ctx_type(struct ctx_type *type)
+{
+	if (!type) {
+		return;
+	}
+	free(type->opt->symbol);
+	free(type->opt);
+	free(type);
+}
+
+static
+struct ctx_type *create_ctx_type(void)
+{
+	struct ctx_type *type = zmalloc(sizeof(*type));
+
+	if (!type) {
+		PERROR("malloc ctx_type");
+		goto end;
+	}
+
+	type->opt = zmalloc(sizeof(*type->opt));
+	if (!type->opt) {
+		PERROR("malloc ctx_type options");
+		destroy_ctx_type(type);
+		goto end;
+	}
+end:
+	return type;
+}
+
+static
+struct ctx_type *get_context_type(const char *ctx)
+{
+	int opt_index;
+	struct ctx_type *type = NULL;
+	const char app_ctx_prefix[] = "$app.";
+	char *provider_name = NULL, *ctx_name = NULL;
+	size_t i, len, colon_pos = 0, provider_name_len, ctx_name_len;
+
+	if (!ctx) {
+		goto not_found;
+	}
+
+	type = create_ctx_type();
+	if (!type) {
+		goto not_found;
+	}
+
+	/* Check if ctx matches a known static context. */
+	opt_index = find_ctx_type_idx(ctx);
+	if (opt_index >= 0) {
+		*type->opt = ctx_opts[opt_index];
+		type->opt->symbol = strdup(ctx_opts[opt_index].symbol);
+		goto found;
+	}
+
+	/*
+	 * No match found against static contexts; check if it is an app
+	 * context.
+	 */
+	len = strlen(ctx);
+	if (len <= sizeof(app_ctx_prefix) - 1) {
+		goto not_found;
+	}
+
+	/* String starts with $app. */
+	if (strncmp(ctx, app_ctx_prefix, sizeof(app_ctx_prefix) - 1)) {
+		goto not_found;
+	}
+
+	/* Validate that the ':' separator is present. */
+	for (i = sizeof(app_ctx_prefix); i < len; i++) {
+		const char c = ctx[i];
+
+		if (c == ':') {
+			colon_pos = i;
+			break;
+		}
+	}
+
+	/*
+	 * No colon found or no ctx name ("$app.provider:") or no provider name
+	 * given ("$app.:..."), which is invalid.
+	 */
+	if (!colon_pos || colon_pos == len ||
+			colon_pos == sizeof(app_ctx_prefix)) {
+		ERR("Invalid application context provided: no provider or context name provided.");
+		goto not_found;
+	}
+
+	provider_name_len = colon_pos - sizeof(app_ctx_prefix) + 2;
+	provider_name = zmalloc(provider_name_len);
+	if (!provider_name) {
+		PERROR("malloc provider_name");
+		goto not_found;
+	}
+	strncpy(provider_name, ctx + sizeof(app_ctx_prefix) - 1,
+			provider_name_len - 1);
+	type->opt->u.app_ctx.provider_name = provider_name;
+
+	ctx_name_len = len - colon_pos;
+	ctx_name = zmalloc(ctx_name_len);
+	if (!ctx_name) {
+		PERROR("malloc ctx_name");
+		goto not_found;
+	}
+	strncpy(ctx_name, ctx + colon_pos + 1, ctx_name_len - 1);
+	type->opt->u.app_ctx.ctx_name = ctx_name;
+	type->opt->ctx_type = CONTEXT_APP_CONTEXT;
+	type->opt->symbol = strdup(ctx);
+found:
+	return type;
+not_found:
+	free(provider_name);
+	free(ctx_name);
+	destroy_ctx_type(type);
+	return NULL;
+}
+
 /*
  * Add context to channel or event.
  */
 int cmd_add_context(int argc, const char **argv)
 {
-	int index, opt, ret = CMD_SUCCESS, command_ret = CMD_SUCCESS;
+	int opt, ret = CMD_SUCCESS, command_ret = CMD_SUCCESS;
 	int success = 1;
 	static poptContext pc;
 	struct ctx_type *type, *tmptype;
@@ -697,37 +849,25 @@ int cmd_add_context(int argc, const char **argv)
 			usage(stdout);
 			goto end;
 		case OPT_TYPE:
-			/*
-			 * Look up the index of opt_type in ctx_opts[] first, so we don't
-			 * have to free(type) on failure.
-			 */
-			index = find_ctx_type_idx(opt_type);
-			if (index < 0) {
+		{
+			type = get_context_type(opt_type);
+			if (!type) {
 				ERR("Unknown context type %s", opt_type);
-				ret = CMD_ERROR;
-				goto end;
-			}
-
-			type = zmalloc(sizeof(struct ctx_type));
-			if (type == NULL) {
-				PERROR("malloc ctx_type");
 				ret = CMD_FATAL;
 				goto end;
 			}
-
-			type->opt = &ctx_opts[index];
-			if (type->opt->symbol == NULL) {
-				ERR("Unknown context type %s", opt_type);
-				free(type);
-				ret = CMD_ERROR;
-				goto end;
-			} else {
-				cds_list_add_tail(&type->list, &ctx_type_list.head);
-			}
+			cds_list_add_tail(&type->list, &ctx_type_list.head);
 			break;
+		}
 		case OPT_USERSPACE:
 			opt_userspace = 1;
 			break;
+		case OPT_JUL:
+			opt_jul = 1;
+			break;
+		case OPT_LOG4J:
+			opt_log4j = 1;
+			break;
 		case OPT_LIST_OPTIONS:
 			list_cmd_options(stdout, long_options);
 			goto end;
@@ -738,8 +878,8 @@ int cmd_add_context(int argc, const char **argv)
 		}
 	}
 
-	ret = print_missing_or_multiple_domains(opt_kernel + opt_userspace);
-
+	ret = print_missing_or_multiple_domains(opt_kernel + opt_userspace +
+			opt_jul + opt_log4j);
 	if (ret) {
 		ret = CMD_ERROR;
 		goto end;
@@ -830,7 +970,7 @@ end:
 
 	/* Cleanup allocated memory */
 	cds_list_for_each_entry_safe(type, tmptype, &ctx_type_list.head, list) {
-		free(type);
+		destroy_ctx_type(type);
 	}
 
 	/* Overwrite ret if an error occurred during add_context() */
-- 
2.34.1


From 8b6f8f8b05fdfbcd707a98ea0935051be5219a5b Mon Sep 17 00:00:00 2001
From: =?utf8?q?J=C3=A9r=C3=A9mie=20Galarneau?=
 <jeremie.galarneau@efficios.com>
Date: Thu, 28 Jan 2016 16:39:33 -0500
Subject: [PATCH 08/16] Notify java agent of enabled application contexts
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---
 src/bin/lttng-sessiond/agent.c         | 322 +++++++++++++++++++++++--
 src/bin/lttng-sessiond/agent.h         |   9 +
 src/bin/lttng-sessiond/channel.c       |  23 +-
 src/bin/lttng-sessiond/cmd.c           |  39 ++-
 src/bin/lttng-sessiond/context.c       |  40 ++-
 src/bin/lttng-sessiond/lttng-ust-abi.h |   6 +
 src/bin/lttng-sessiond/lttng-ust-ctl.h |  13 +-
 src/bin/lttng-sessiond/trace-ust.c     |  52 +++-
 src/bin/lttng-sessiond/trace-ust.h     |   4 +-
 src/bin/lttng-sessiond/ust-app.c       |  52 +++-
 src/bin/lttng-sessiond/ust-app.h       |   3 +-
 src/common/sessiond-comm/agent.h       |  21 +-
 12 files changed, 526 insertions(+), 58 deletions(-)

diff --git a/src/bin/lttng-sessiond/agent.c b/src/bin/lttng-sessiond/agent.c
index f6f2f772e..b2608a186 100644
--- a/src/bin/lttng-sessiond/agent.c
+++ b/src/bin/lttng-sessiond/agent.c
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2013 - David Goulet <dgoulet@efficios.com>
+ * Copyright (C) 2016 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License, version 2 only, as
@@ -18,6 +19,7 @@
 #define _LGPL_SOURCE
 #include <assert.h>
 #include <urcu/uatomic.h>
+#include <urcu/rculist.h>
 
 #include <common/common.h>
 #include <common/sessiond-comm/agent.h>
@@ -31,6 +33,20 @@
 
 #define AGENT_RET_CODE_INDEX(code) (code - AGENT_RET_CODE_SUCCESS)
 
+/*
+ * Agent application context representation.
+ */
+struct agent_app_ctx {
+	char *provider_name;
+	char *ctx_name;
+
+	/* agent_app_ctx are part of the agent app_ctx_list. */
+	struct cds_list_head list_node;
+
+	/* For call_rcu teardown. */
+	struct rcu_head rcu_node;
+};
+
 /*
  * Human readable agent return code.
  */
@@ -225,7 +241,7 @@ error:
  *
  * Return 0 on success or else a negative errno value of sendmsg() op.
  */
-static int send_payload(struct lttcomm_sock *sock, void *data,
+static int send_payload(struct lttcomm_sock *sock, const void *data,
 		size_t size)
 {
 	int ret;
@@ -371,7 +387,7 @@ static int enable_event(struct agent_app *app, struct agent_event *event)
 	uint64_t data_size;
 	size_t filter_expression_length;
 	uint32_t reply_ret_code;
-	struct lttcomm_agent_enable msg;
+	struct lttcomm_agent_enable_event msg;
 	struct lttcomm_agent_generic_reply reply;
 
 	assert(app);
@@ -447,6 +463,112 @@ error:
 	return ret;
 }
 
+/*
+ * Send Pascal-style string. Size is sent as a 32-bit big endian integer.
+ */
+static
+int send_pstring(struct lttcomm_sock *sock, const char *str, uint32_t len)
+{
+	int ret;
+	uint32_t len_be;
+
+	len_be = htobe32(len);
+	ret = send_payload(sock, &len_be, sizeof(len_be));
+	if (ret) {
+		goto end;
+	}
+
+	ret = send_payload(sock, str, len);
+	if (ret) {
+		goto end;
+	}
+end:
+	return ret;
+}
+
+/*
+ * Internal enable application context on an agent application. This function
+ * communicates with the agent to enable a given application context.
+ *
+ * Return LTTNG_OK on success or else a LTTNG_ERR* code.
+ */
+static int app_context_op(struct agent_app *app,
+		struct agent_app_ctx *ctx, enum lttcomm_agent_command cmd)
+{
+	int ret;
+	uint32_t reply_ret_code;
+	struct lttcomm_agent_generic_reply reply;
+	size_t app_ctx_provider_name_len, app_ctx_name_len, data_size;
+
+	assert(app);
+	assert(app->sock);
+	assert(ctx);
+	assert(cmd == AGENT_CMD_APP_CTX_ENABLE ||
+			cmd == AGENT_CMD_APP_CTX_DISABLE);
+
+	DBG2("Agent %s application %s:%s for app pid: %d and socket %d",
+			cmd == AGENT_CMD_APP_CTX_ENABLE ? "enabling" : "disabling",
+			ctx->provider_name, ctx->ctx_name,
+			app->pid, app->sock->fd);
+
+	/*
+	 * Calculate the payload's size, which consists of the size (u32, BE)
+	 * of the provider name, the NULL-terminated provider name string, the
+	 * size (u32, BE) of the context name, followed by the NULL-terminated
+	 * context name string.
+	 */
+	app_ctx_provider_name_len = strlen(ctx->provider_name) + 1;
+	app_ctx_name_len = strlen(ctx->ctx_name) + 1;
+	data_size = sizeof(uint32_t) + app_ctx_provider_name_len +
+			sizeof(uint32_t) + app_ctx_name_len;
+
+	ret = send_header(app->sock, data_size, cmd, 0);
+	if (ret < 0) {
+		goto error_io;
+	}
+
+	if (app_ctx_provider_name_len > UINT32_MAX ||
+			app_ctx_name_len > UINT32_MAX) {
+		ERR("Application context name > MAX_UINT32");
+		ret = LTTNG_ERR_INVALID;
+		goto error;
+	}
+
+	ret = send_pstring(app->sock, ctx->provider_name,
+			(uint32_t) app_ctx_provider_name_len);
+	if (ret < 0) {
+		goto error_io;
+	}
+
+	ret = send_pstring(app->sock, ctx->ctx_name,
+			(uint32_t) app_ctx_name_len);
+	if (ret < 0) {
+		goto error_io;
+	}
+
+	ret = recv_reply(app->sock, &reply, sizeof(reply));
+	if (ret < 0) {
+		goto error_io;
+	}
+
+	reply_ret_code = be32toh(reply.ret_code);
+	log_reply_code(reply_ret_code);
+	switch (reply_ret_code) {
+	case AGENT_RET_CODE_SUCCESS:
+		break;
+	default:
+		ret = LTTNG_ERR_UNK;
+		goto error;
+	}
+
+	return LTTNG_OK;
+
+error_io:
+	ret = LTTNG_ERR_UST_ENABLE_FAIL;
+error:
+	return ret;
+}
+
 /*
  * Internal disable agent event call on a agent application. This function
  * communicates with the agent to disable a given event.
@@ -458,7 +580,7 @@ static int disable_event(struct agent_app *app, struct agent_event *event)
 	int ret;
 	uint64_t data_size;
 	uint32_t reply_ret_code;
-	struct lttcomm_agent_disable msg;
+	struct lttcomm_agent_disable_event msg;
 	struct lttcomm_agent_generic_reply reply;
 
 	assert(app);
@@ -561,8 +683,91 @@ error:
 	return ret;
 }
 
+static
+void destroy_app_ctx(struct agent_app_ctx *ctx)
+{
+	free(ctx->provider_name);
+	free(ctx->ctx_name);
+	free(ctx);
+}
+
+static
+struct agent_app_ctx *create_app_ctx(struct lttng_event_context *ctx)
+{
+	struct agent_app_ctx *agent_ctx = NULL;
+
+	if (!ctx) {
+		goto end;
+	}
+
+	assert(ctx->ctx == LTTNG_EVENT_CONTEXT_APP_CONTEXT);
+	agent_ctx = zmalloc(sizeof(*ctx));
+	if (!agent_ctx) {
+		goto end;
+	}
+
+	agent_ctx->provider_name = strdup(ctx->u.app_ctx.provider_name);
+	agent_ctx->ctx_name = strdup(ctx->u.app_ctx.ctx_name);
+	if (!agent_ctx->provider_name || !agent_ctx->ctx_name) {
+		destroy_app_ctx(agent_ctx);
+		agent_ctx = NULL;
+	}
+end:
+	return agent_ctx;
+}
+
+/*
+ * Enable agent context on every agent applications registered with the session
+ * daemon.
+ *
+ * Return LTTNG_OK on success or else a LTTNG_ERR* code.
+ */
+int agent_enable_context(struct lttng_event_context *ctx,
+		enum lttng_domain_type domain)
+{
+	int ret;
+	struct agent_app *app;
+	struct lttng_ht_iter iter;
+
+	assert(ctx);
+	if (ctx->ctx != LTTNG_EVENT_CONTEXT_APP_CONTEXT) {
+		ret = LTTNG_ERR_INVALID;
+		goto error;
+	}
+
+	rcu_read_lock();
+
+	cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
+			node.node) {
+		struct agent_app_ctx *agent_ctx;
+
+		if (app->domain != domain) {
+			continue;
+		}
+
+		agent_ctx = create_app_ctx(ctx);
+		if (!agent_ctx) {
+			goto error_unlock;
+		}
+
+		/* Enable event on agent application through TCP socket. */
+		ret = app_context_op(app, agent_ctx, AGENT_CMD_APP_CTX_ENABLE);
+		if (ret != LTTNG_OK) {
+			destroy_app_ctx(agent_ctx);
+			goto error_unlock;
+		}
+	}
+
+	ret = LTTNG_OK;
+
+error_unlock:
+	rcu_read_unlock();
+error:
+	return ret;
+}
+
 /*
- * Disable agent event on every agent applications registered with the session
+ * Disable agent event on every agent application registered with the session
  * daemon.
  *
  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
@@ -602,6 +807,39 @@ end:
 	return ret;
 }
 
+/*
+ * Disable agent context on every agent application registered with the session
+ * daemon.
+ *
+ * Return LTTNG_OK on success or else a LTTNG_ERR* code.
+ */
+int disable_context(struct agent_app_ctx *ctx, enum lttng_domain_type domain)
+{
+	int ret = LTTNG_OK;
+	struct agent_app *app;
+	struct lttng_ht_iter iter;
+
+	assert(ctx);
+
+	rcu_read_lock();
+	DBG2("Disabling agent application context %s:%s",
+			ctx->provider_name, ctx->ctx_name);
+	cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
+			node.node) {
+		if (app->domain != domain) {
+			continue;
+		}
+
+		ret = app_context_op(app, ctx, AGENT_CMD_APP_CTX_DISABLE);
+		if (ret != LTTNG_OK) {
+			goto end;
+		}
+	}
+end:
+	rcu_read_unlock();
+	return ret;
+}
+
 /*
  * Ask every agent for the list of possible event. Events is allocated with the
  * events of every agent application.
@@ -808,6 +1046,7 @@ int agent_init(struct agent *agt)
 	}
 	lttng_ht_node_init_u64(&agt->node, agt->domain);
 
+	CDS_INIT_LIST_HEAD(&agt->app_ctx_list);
 	return 0;
 
 error:
@@ -907,6 +1146,32 @@ void agent_add_event(struct agent_event *event, struct agent *agt)
 	agt->being_used = 1;
 }
 
+/*
+ * Unique add of a agent context to an agent object.
+ */
+int agent_add_context(struct lttng_event_context *ctx, struct agent *agt)
+{
+	int ret = LTTNG_OK;
+	struct agent_app_ctx *agent_ctx = NULL;
+
+	assert(ctx);
+	assert(agt);
+	assert(agt->events);
+	assert(ctx->ctx == LTTNG_EVENT_CONTEXT_APP_CONTEXT);
+
+	agent_ctx = create_app_ctx(ctx);
+	if (!agent_ctx) {
+		ret = LTTNG_ERR_NOMEM;
+		goto end;
+	}
+
+	DBG3("Agent adding context %s:%s", ctx->u.app_ctx.provider_name,
+			ctx->u.app_ctx.ctx_name);
+	cds_list_add_tail_rcu(&agent_ctx->list_node, &agt->app_ctx_list);
+end:
+	return ret;
+}
+
 /*
  * Find multiple agent events sharing the given name.
  *
@@ -1008,6 +1273,15 @@ void agent_destroy_event(struct agent_event *event)
 	free(event);
 }
 
+static
+void destroy_app_ctx_rcu(struct rcu_head *head)
+{
+	struct agent_app_ctx *ctx =
+			caa_container_of(head, struct agent_app_ctx, rcu_node);
+
+	destroy_app_ctx(ctx);
+}
+
 /*
  * Destroy an agent completely.
  */
@@ -1015,6 +1289,7 @@ void agent_destroy(struct agent *agt)
 {
 	struct lttng_ht_node_str *node;
 	struct lttng_ht_iter iter;
+	struct agent_app_ctx *ctx;
 
 	assert(agt);
 
@@ -1026,9 +1301,10 @@ void agent_destroy(struct agent *agt)
 		struct agent_event *event;
 
 		/*
-		 * When destroying an event, we have to try to disable it on the agent
-		 * side so the event stops generating data. The return value is not
-		 * important since we have to continue anyway destroying the object.
+		 * When destroying an event, we have to try to disable it on the
+		 * agent side so the event stops generating data. The return
+		 * value is not important since we have to continue anyway
+		 * destroying the object.
 		 */
 		event = caa_container_of(node, struct agent_event, node);
 		(void) agent_disable_event(event, agt->domain);
@@ -1037,8 +1313,13 @@ void agent_destroy(struct agent *agt)
 		assert(!ret);
 		call_rcu(&node->head, destroy_event_agent_rcu);
 	}
-	rcu_read_unlock();
 
+	cds_list_for_each_entry_rcu(ctx, &agt->app_ctx_list, list_node) {
+		(void) disable_context(ctx, agt->domain);
+		cds_list_del(&ctx->list_node);
+		call_rcu(&ctx->rcu_node, destroy_app_ctx_rcu);
+	}
+	rcu_read_unlock();
 	ht_cleanup_push(agt->events);
 	free(agt);
 }
@@ -1119,6 +1400,7 @@ void agent_update(struct agent *agt, int sock)
 	struct agent_app *app;
 	struct agent_event *event;
 	struct lttng_ht_iter iter;
+	struct agent_app_ctx *ctx;
 
 	assert(agt);
 	assert(sock >= 0);
@@ -1126,19 +1408,18 @@ void agent_update(struct agent *agt, int sock)
 	DBG("Agent updating app socket %d", sock);
 
 	rcu_read_lock();
+	app = agent_find_app_by_sock(sock);
+	/*
+	 * We are in the registration path thus if the application is gone,
+	 * there is a serious code flow error.
+	 */
+	assert(app);
 	cds_lfht_for_each_entry(agt->events->ht, &iter.iter, event, node.node) {
 		/* Skip event if disabled. */
 		if (!event->enabled) {
 			continue;
 		}
 
-		app = agent_find_app_by_sock(sock);
-		/*
-		 * We are in the registration path thus if the application is gone,
-		 * there is a serious code flow error.
-		 */
-		assert(app);
-
 		ret = enable_event(app, event);
 		if (ret != LTTNG_OK) {
 			DBG2("Agent update unable to enable event %s on app pid: %d sock %d",
@@ -1147,5 +1428,16 @@ void agent_update(struct agent *agt, int sock)
 			continue;
 		}
 	}
+
+	cds_list_for_each_entry_rcu(ctx, &agt->app_ctx_list, list_node) {
+		ret = app_context_op(app, ctx, AGENT_CMD_APP_CTX_ENABLE);
+		if (ret != LTTNG_OK) {
+			DBG2("Agent update unable to add application context %s:%s on app pid: %d sock %d",
+					ctx->provider_name, ctx->ctx_name,
+					app->pid, app->sock->fd);
+			continue;
+		}
+	}
+
 	rcu_read_unlock();
 }
diff --git a/src/bin/lttng-sessiond/agent.h b/src/bin/lttng-sessiond/agent.h
index 2b3d864a6..c0808c48f 100644
--- a/src/bin/lttng-sessiond/agent.h
+++ b/src/bin/lttng-sessiond/agent.h
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2013 - David Goulet <dgoulet@efficios.com>
+ * Copyright (C) 2016 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License, version 2 only, as
@@ -116,6 +117,9 @@ struct agent {
 	/* Contains event indexed by name. */
 	struct lttng_ht *events;
 
+	/* Application context list (struct agent_app_ctx). */
+	struct cds_list_head app_ctx_list;
+
 	/* Node used for the hash table indexed by domain type. */
 	struct lttng_ht_node_u64 node;
 };
@@ -148,6 +152,11 @@ void agent_event_next_duplicate(const char *name,
 void agent_delete_event(struct agent_event *event, struct agent *agt);
 void agent_destroy_event(struct agent_event *event);
 
+/* Agent context API.*/
+int agent_enable_context(struct lttng_event_context *ctx,
+		enum lttng_domain_type domain);
+int agent_add_context(struct lttng_event_context *ctx, struct agent *agt);
+
 /* Agent app API. */
 struct agent_app *agent_create_app(pid_t pid, enum lttng_domain_type domain,
 		struct lttcomm_sock *sock);
diff --git a/src/bin/lttng-sessiond/channel.c b/src/bin/lttng-sessiond/channel.c
index 06a6d616a..7c95a0d21 100644
--- a/src/bin/lttng-sessiond/channel.c
+++ b/src/bin/lttng-sessiond/channel.c
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
+ * Copyright (C) 2016 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License, version 2 only,
@@ -38,6 +39,7 @@ struct lttng_channel *channel_new_default_attr(int dom,
 		enum lttng_buffer_type type)
 {
 	struct lttng_channel *chan;
+	const char *channel_name = DEFAULT_CHANNEL_NAME;
 
 	chan = zmalloc(sizeof(struct lttng_channel));
 	if (chan == NULL) {
@@ -45,12 +47,6 @@ struct lttng_channel *channel_new_default_attr(int dom,
 		goto error_alloc;
 	}
 
-	if (snprintf(chan->name, sizeof(chan->name), "%s",
-				DEFAULT_CHANNEL_NAME) < 0) {
-		PERROR("snprintf default channel name");
-		goto error;
-	}
-
 	/* Same for all domains. */
 	chan->attr.overwrite = DEFAULT_CHANNEL_OVERWRITE;
 	chan->attr.tracefile_size = DEFAULT_CHANNEL_TRACEFILE_SIZE;
@@ -67,7 +63,17 @@ struct lttng_channel *channel_new_default_attr(int dom,
 		chan->attr.read_timer_interval = DEFAULT_KERNEL_CHANNEL_READ_TIMER;
 		chan->attr.live_timer_interval = DEFAULT_KERNEL_CHANNEL_LIVE_TIMER;
 		break;
+	case LTTNG_DOMAIN_JUL:
+		channel_name = DEFAULT_JUL_CHANNEL_NAME;
+		goto common_ust;
+	case LTTNG_DOMAIN_LOG4J:
+		channel_name = DEFAULT_LOG4J_CHANNEL_NAME;
+		goto common_ust;
+	case LTTNG_DOMAIN_PYTHON:
+		channel_name = DEFAULT_PYTHON_CHANNEL_NAME;
+		goto common_ust;
 	case LTTNG_DOMAIN_UST:
+common_ust:
 		switch (type) {
 		case LTTNG_BUFFER_PER_UID:
 			chan->attr.subbuf_size = default_get_ust_uid_channel_subbuf_size();
@@ -98,6 +104,11 @@ struct lttng_channel *channel_new_default_attr(int dom,
 		goto error;	/* Not implemented */
 	}
 
+	if (snprintf(chan->name, sizeof(chan->name), "%s",
+			channel_name) < 0) {
+		PERROR("snprintf default channel name");
+		goto error;
+	}
 	return chan;
 
 error:
diff --git a/src/bin/lttng-sessiond/cmd.c b/src/bin/lttng-sessiond/cmd.c
index 33e301c87..eca3cf439 100644
--- a/src/bin/lttng-sessiond/cmd.c
+++ b/src/bin/lttng-sessiond/cmd.c
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2012 - David Goulet <dgoulet@efficios.com>
+ * Copyright (C) 2016 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License, version 2 only, as
@@ -1359,6 +1360,12 @@ int cmd_add_context(struct ltt_session *session, enum lttng_domain_type domain,
 		char *channel_name, struct lttng_event_context *ctx, int kwpipe)
 {
 	int ret, chan_kern_created = 0, chan_ust_created = 0;
+	char *app_ctx_provider_name = NULL, *app_ctx_name = NULL;
+
+	if (ctx->ctx == LTTNG_EVENT_CONTEXT_APP_CONTEXT) {
+		app_ctx_provider_name = ctx->u.app_ctx.provider_name;
+		app_ctx_name = ctx->u.app_ctx.ctx_name;
+	}
 
 	switch (domain) {
 	case LTTNG_DOMAIN_KERNEL:
@@ -1378,6 +1385,28 @@ int cmd_add_context(struct ltt_session *session, enum lttng_domain_type domain,
 			goto error;
 		}
 		break;
+	case LTTNG_DOMAIN_JUL:
+	case LTTNG_DOMAIN_LOG4J:
+	{
+		/*
+		 * Validate channel name.
+		 * If no channel name is given and the domain is JUL or LOG4J,
+		 * set it to the appropriate domain-specific channel name. If
+		 * a name is provided but does not match the expexted channel
+		 * name, return an error.
+		 */
+		if (domain == LTTNG_DOMAIN_JUL && *channel_name &&
+				strcmp(channel_name,
+				DEFAULT_JUL_CHANNEL_NAME)) {
+			ret = LTTNG_ERR_UST_CHAN_NOT_FOUND;
+			goto error;
+		} else if (domain == LTTNG_DOMAIN_LOG4J && *channel_name &&
+				strcmp(channel_name,
+				DEFAULT_LOG4J_CHANNEL_NAME)) {
+			ret = LTTNG_ERR_UST_CHAN_NOT_FOUND;
+			goto error;
+		}
+	}
 	case LTTNG_DOMAIN_UST:
 	{
 		struct ltt_ust_session *usess = session->ust_session;
@@ -1405,6 +1434,10 @@ int cmd_add_context(struct ltt_session *session, enum lttng_domain_type domain,
 		}
 
 		ret = context_ust_add(usess, domain, ctx, channel_name);
+		free(app_ctx_provider_name);
+		free(app_ctx_name);
+		app_ctx_name = NULL;
+		app_ctx_provider_name = NULL;
 		if (ret != LTTNG_OK) {
 			goto error;
 		}
@@ -1415,7 +1448,8 @@ int cmd_add_context(struct ltt_session *session, enum lttng_domain_type domain,
 		goto error;
 	}
 
-	return LTTNG_OK;
+	ret = LTTNG_OK;
+	goto end;
 
 error:
 	if (chan_kern_created) {
@@ -1439,6 +1473,9 @@ error:
 				uchan);
 		trace_ust_destroy_channel(uchan);
 	}
+end:
+	free(app_ctx_provider_name);
+	free(app_ctx_name);
 	return ret;
 }
 
diff --git a/src/bin/lttng-sessiond/context.c b/src/bin/lttng-sessiond/context.c
index ffd6e3ad5..1725c6a10 100644
--- a/src/bin/lttng-sessiond/context.c
+++ b/src/bin/lttng-sessiond/context.c
@@ -1,5 +1,6 @@
 /*
- * Copyright (C)  2011 - David Goulet <david.goulet@polymtl.ca>
+ * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
+ * Copyright (C) 2016 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License, version 2 only,
@@ -29,6 +30,7 @@
 #include "kernel.h"
 #include "ust-app.h"
 #include "trace-ust.h"
+#include "agent.h"
 
 /*
  * Add kernel context to all channel.
@@ -92,12 +94,11 @@ static int add_uctx_to_channel(struct ltt_ust_session *usess,
 		struct ltt_ust_channel *uchan, struct lttng_event_context *ctx)
 {
 	int ret;
-	struct ltt_ust_context *uctx;
+	struct ltt_ust_context *uctx = NULL;
 
 	assert(usess);
 	assert(uchan);
 	assert(ctx);
-	assert(domain == LTTNG_DOMAIN_UST);
 
 	/* Check if context is duplicate */
 	cds_list_for_each_entry(uctx, &uchan->ctx_list, list) {
@@ -106,6 +107,38 @@ static int add_uctx_to_channel(struct ltt_ust_session *usess,
 			goto duplicate;
 		}
 	}
+	uctx = NULL;
+
+	switch (domain) {
+	case LTTNG_DOMAIN_JUL:
+	case LTTNG_DOMAIN_LOG4J:
+	{
+		struct agent *agt = trace_ust_find_agent(usess, domain);
+
+		if (!agt) {
+			agt = agent_create(domain);
+			if (!agt) {
+				ret = LTTNG_ERR_NOMEM;
+				goto error;
+			}
+			agent_add(agt, usess->agents);
+		}
+		ret = agent_add_context(ctx, agt);
+		if (ret != LTTNG_OK) {
+			goto error;
+		}
+
+		ret = agent_enable_context(ctx, domain);
+		if (ret != LTTNG_OK) {
+			goto error;
+		}
+		break;
+	}
+	case LTTNG_DOMAIN_UST:
+		break;
+	default:
+		assert(0);
+	}
 
 	/* Create ltt UST context */
 	uctx = trace_ust_create_context(ctx);
@@ -246,7 +279,6 @@ int context_ust_add(struct ltt_ust_session *usess,
 	assert(usess);
 	assert(ctx);
 	assert(channel_name);
-	assert(domain == LTTNG_DOMAIN_UST);
 
 	rcu_read_lock();
 
diff --git a/src/bin/lttng-sessiond/lttng-ust-abi.h b/src/bin/lttng-sessiond/lttng-ust-abi.h
index d4c3b60aa..7bec0c961 100644
--- a/src/bin/lttng-sessiond/lttng-ust-abi.h
+++ b/src/bin/lttng-sessiond/lttng-ust-abi.h
@@ -142,6 +142,7 @@ enum lttng_ust_context_type {
 	LTTNG_UST_CONTEXT_IP			= 4,
 	LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER	= 5,
 	LTTNG_UST_CONTEXT_CPU_ID		= 6,
+	LTTNG_UST_CONTEXT_APP_CONTEXT		= 7,
 };
 
 struct lttng_ust_perf_counter_ctx {
@@ -158,6 +159,11 @@ struct lttng_ust_context {
 
 	union {
 		struct lttng_ust_perf_counter_ctx perf_counter;
+		struct {
+			/* Includes trailing '\0'. */
+			uint32_t provider_name_len;
+			uint32_t ctx_name_len;
+		} app_ctx;
 		char padding[LTTNG_UST_CONTEXT_PADDING2];
 	} u;
 } LTTNG_PACKED;
diff --git a/src/bin/lttng-sessiond/lttng-ust-ctl.h b/src/bin/lttng-sessiond/lttng-ust-ctl.h
index 73a924418..1ea7b938a 100644
--- a/src/bin/lttng-sessiond/lttng-ust-ctl.h
+++ b/src/bin/lttng-sessiond/lttng-ust-ctl.h
@@ -59,6 +59,17 @@ struct ustctl_consumer_channel_attr {
  * API used by sessiond.
  */
 
+struct lttng_ust_context_attr {
+	enum lttng_ust_context_type ctx;
+	union {
+		struct lttng_ust_perf_counter_ctx perf_counter;
+		struct {
+		        char *provider_name;
+			char *ctx_name;
+		} app_ctx;
+	} u;
+};
+
 /*
  * Error values: all the following functions return:
  * >= 0: Success (LTTNG_UST_OK)
@@ -69,7 +80,7 @@ int ustctl_create_session(int sock);
 int ustctl_create_event(int sock, struct lttng_ust_event *ev,
 		struct lttng_ust_object_data *channel_data,
 		struct lttng_ust_object_data **event_data);
-int ustctl_add_context(int sock, struct lttng_ust_context *ctx,
+int ustctl_add_context(int sock, struct lttng_ust_context_attr *ctx,
 		struct lttng_ust_object_data *obj_data,
 		struct lttng_ust_object_data **context_data);
 int ustctl_set_filter(int sock, struct lttng_ust_filter_bytecode *bytecode,
diff --git a/src/bin/lttng-sessiond/trace-ust.c b/src/bin/lttng-sessiond/trace-ust.c
index 4d39e2133..4ed8fb1a5 100644
--- a/src/bin/lttng-sessiond/trace-ust.c
+++ b/src/bin/lttng-sessiond/trace-ust.c
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
+ * Copyright (C) 2016 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License, version 2 only,
@@ -518,7 +519,8 @@ error:
 }
 
 static
-int trace_ust_context_type_event_to_ust(enum lttng_event_context_type type)
+int trace_ust_context_type_event_to_ust(
+		enum lttng_event_context_type type)
 {
 	int utype;
 
@@ -546,6 +548,9 @@ int trace_ust_context_type_event_to_ust(enum lttng_event_context_type type)
 			utype = LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER;
 		}
 		break;
+	case LTTNG_EVENT_CONTEXT_APP_CONTEXT:
+		utype = LTTNG_UST_CONTEXT_APP_CONTEXT;
+		break;
 	default:
 		utype = -1;
 		break;
@@ -599,7 +604,7 @@ int trace_ust_match_context(struct ltt_ust_context *uctx,
 struct ltt_ust_context *trace_ust_create_context(
 		struct lttng_event_context *ctx)
 {
-	struct ltt_ust_context *uctx;
+	struct ltt_ust_context *uctx = NULL;
 	int utype;
 
 	assert(ctx);
@@ -607,13 +612,13 @@ struct ltt_ust_context *trace_ust_create_context(
 	utype = trace_ust_context_type_event_to_ust(ctx->ctx);
 	if (utype < 0) {
 		ERR("Invalid UST context");
-		return NULL;
+		goto end;
 	}
 
 	uctx = zmalloc(sizeof(struct ltt_ust_context));
-	if (uctx == NULL) {
+	if (!uctx) {
 		PERROR("zmalloc ltt_ust_context");
-		goto error;
+		goto end;
 	}
 
 	uctx->ctx.ctx = (enum lttng_ust_context_type) utype;
@@ -625,14 +630,31 @@ struct ltt_ust_context *trace_ust_create_context(
 				LTTNG_UST_SYM_NAME_LEN);
 		uctx->ctx.u.perf_counter.name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 		break;
+	case LTTNG_UST_CONTEXT_APP_CONTEXT:
+	{
+		char *provider_name = NULL, *ctx_name = NULL;
+
+		provider_name = strdup(ctx->u.app_ctx.provider_name);
+		if (!provider_name) {
+			goto error;
+		}
+		uctx->ctx.u.app_ctx.provider_name = provider_name;
+
+		ctx_name = strdup(ctx->u.app_ctx.ctx_name);
+		if (!ctx_name) {
+			goto error;
+		}
+		uctx->ctx.u.app_ctx.ctx_name = ctx_name;
+		break;
+	}
 	default:
 		break;
 	}
 	lttng_ht_node_init_ulong(&uctx->node, (unsigned long) uctx->ctx.ctx);
-
+end:
 	return uctx;
-
 error:
+	trace_ust_destroy_context(uctx);
 	return NULL;
 }
 
@@ -931,7 +953,7 @@ static void destroy_context_rcu(struct rcu_head *head)
 	struct ltt_ust_context *ctx =
 		caa_container_of(node, struct ltt_ust_context, node);
 
-	free(ctx);
+	trace_ust_destroy_context(ctx);
 }
 
 /*
@@ -976,6 +998,20 @@ void trace_ust_destroy_event(struct ltt_ust_event *event)
 	free(event);
 }
 
+/*
+ * Cleanup ust context structure.
+ */
+void trace_ust_destroy_context(struct ltt_ust_context *ctx)
+{
+	assert(ctx);
+
+	if (ctx->ctx.ctx == LTTNG_UST_CONTEXT_APP_CONTEXT) {
+		free(ctx->ctx.u.app_ctx.provider_name);
+		free(ctx->ctx.u.app_ctx.ctx_name);
+	}
+	free(ctx);
+}
+
 /*
  * URCU intermediate call to complete destroy event.
  */
diff --git a/src/bin/lttng-sessiond/trace-ust.h b/src/bin/lttng-sessiond/trace-ust.h
index 04b3e027c..5a48885d8 100644
--- a/src/bin/lttng-sessiond/trace-ust.h
+++ b/src/bin/lttng-sessiond/trace-ust.h
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
+ * Copyright (C) 2016 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License, version 2 only,
@@ -40,7 +41,7 @@ struct ltt_ust_ht_key {
 
 /* Context hash table nodes */
 struct ltt_ust_context {
-	struct lttng_ust_context ctx;
+	struct lttng_ust_context_attr ctx;
 	struct lttng_ht_node_ulong node;
 	struct cds_list_head list;
 };
@@ -209,6 +210,7 @@ void trace_ust_delete_channel(struct lttng_ht *ht,
 void trace_ust_destroy_session(struct ltt_ust_session *session);
 void trace_ust_destroy_channel(struct ltt_ust_channel *channel);
 void trace_ust_destroy_event(struct ltt_ust_event *event);
+void trace_ust_destroy_context(struct ltt_ust_context *ctx);
 
 int trace_ust_track_pid(struct ltt_ust_session *session, int pid);
 int trace_ust_untrack_pid(struct ltt_ust_session *session, int pid);
diff --git a/src/bin/lttng-sessiond/ust-app.c b/src/bin/lttng-sessiond/ust-app.c
index 2bd48c7f3..8c45a89a5 100644
--- a/src/bin/lttng-sessiond/ust-app.c
+++ b/src/bin/lttng-sessiond/ust-app.c
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
+ * Copyright (C) 2016 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License, version 2 only,
@@ -1037,7 +1038,7 @@ error:
  * Alloc new UST app context.
  */
 static
-struct ust_app_ctx *alloc_ust_app_ctx(struct lttng_ust_context *uctx)
+struct ust_app_ctx *alloc_ust_app_ctx(struct lttng_ust_context_attr *uctx)
 {
 	struct ust_app_ctx *ua_ctx;
 
@@ -1050,12 +1051,27 @@ struct ust_app_ctx *alloc_ust_app_ctx(struct lttng_ust_context *uctx)
 
 	if (uctx) {
 		memcpy(&ua_ctx->ctx, uctx, sizeof(ua_ctx->ctx));
+		if (uctx->ctx == LTTNG_UST_CONTEXT_APP_CONTEXT) {
+		        char *provider_name = NULL, *ctx_name = NULL;
+
+			provider_name = strdup(uctx->u.app_ctx.provider_name);
+			ctx_name = strdup(uctx->u.app_ctx.ctx_name);
+			if (!provider_name || !ctx_name) {
+				free(provider_name);
+				free(ctx_name);
+				goto error;
+			}
+
+			ua_ctx->ctx.u.app_ctx.provider_name = provider_name;
+			ua_ctx->ctx.u.app_ctx.ctx_name = ctx_name;
+		}
 	}
 
 	DBG3("UST app context %d allocated", ua_ctx->ctx.ctx);
-
-error:
 	return ua_ctx;
+error:
+	free(ua_ctx);
+	return NULL;
 }
 
 /*
@@ -1696,7 +1712,6 @@ static void shadow_copy_channel(struct ust_app_channel *ua_chan,
 	struct ltt_ust_event *uevent;
 	struct ltt_ust_context *uctx;
 	struct ust_app_event *ua_event;
-	struct ust_app_ctx *ua_ctx;
 
 	DBG2("UST app shadow copy of channel %s started", ua_chan->name);
 
@@ -1722,7 +1737,8 @@ static void shadow_copy_channel(struct ust_app_channel *ua_chan,
 	ua_chan->tracing_channel_id = uchan->id;
 
 	cds_list_for_each_entry(uctx, &uchan->ctx_list, list) {
-		ua_ctx = alloc_ust_app_ctx(&uctx->ctx);
+		struct ust_app_ctx *ua_ctx = alloc_ust_app_ctx(&uctx->ctx);
+
 		if (ua_ctx == NULL) {
 			continue;
 		}
@@ -2173,7 +2189,7 @@ error:
 static int ht_match_ust_app_ctx(struct cds_lfht_node *node, const void *_key)
 {
 	struct ust_app_ctx *ctx;
-	const struct lttng_ust_context *key;
+	const struct lttng_ust_context_attr *key;
 
 	assert(node);
 	assert(_key);
@@ -2186,13 +2202,24 @@ static int ht_match_ust_app_ctx(struct cds_lfht_node *node, const void *_key)
 		goto no_match;
 	}
 
-	/* Check the name in the case of perf thread counters. */
-	if (key->ctx == LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER) {
+	switch(key->ctx) {
+	case LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER:
 		if (strncmp(key->u.perf_counter.name,
-			ctx->ctx.u.perf_counter.name,
-			sizeof(key->u.perf_counter.name))) {
+				ctx->ctx.u.perf_counter.name,
+				sizeof(key->u.perf_counter.name))) {
+			goto no_match;
+		}
+		break;
+	case LTTNG_UST_CONTEXT_APP_CONTEXT:
+		if (strcmp(key->u.app_ctx.provider_name,
+				ctx->ctx.u.app_ctx.provider_name) ||
+				strcmp(key->u.app_ctx.ctx_name,
+				ctx->ctx.u.app_ctx.ctx_name)) {
 			goto no_match;
 		}
+		break;
+	default:
+		break;
 	}
 
 	/* Match. */
@@ -2210,7 +2237,7 @@ no_match:
  */
 static
 struct ust_app_ctx *find_ust_app_context(struct lttng_ht *ht,
-		struct lttng_ust_context *uctx)
+		struct lttng_ust_context_attr *uctx)
 {
 	struct lttng_ht_iter iter;
 	struct lttng_ht_node_ulong *node;
@@ -2240,7 +2267,8 @@ end:
  */
 static
 int create_ust_app_channel_context(struct ust_app_session *ua_sess,
-		struct ust_app_channel *ua_chan, struct lttng_ust_context *uctx,
+		struct ust_app_channel *ua_chan,
+	        struct lttng_ust_context_attr *uctx,
 		struct ust_app *app)
 {
 	int ret = 0;
diff --git a/src/bin/lttng-sessiond/ust-app.h b/src/bin/lttng-sessiond/ust-app.h
index 3daccba86..4398fe241 100644
--- a/src/bin/lttng-sessiond/ust-app.h
+++ b/src/bin/lttng-sessiond/ust-app.h
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
+ * Copyright (C) 2016 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License, version 2 only,
@@ -101,7 +102,7 @@ struct ust_app_stream_list {
 
 struct ust_app_ctx {
 	int handle;
-	struct lttng_ust_context ctx;
+	struct lttng_ust_context_attr ctx;
 	struct lttng_ust_object_data *obj;
 	struct lttng_ht_node_ulong node;
 	struct cds_list_head list;
diff --git a/src/common/sessiond-comm/agent.h b/src/common/sessiond-comm/agent.h
index e8d182515..11acc52f9 100644
--- a/src/common/sessiond-comm/agent.h
+++ b/src/common/sessiond-comm/agent.h
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2013 - David Goulet <dgoulet@efficios.com>
+ * Copyright (C) 2016 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License, version 2 only, as
@@ -26,10 +27,12 @@
  * Command value passed in the header.
  */
 enum lttcomm_agent_command {
-	AGENT_CMD_LIST       = 1,
-	AGENT_CMD_ENABLE     = 2,
-	AGENT_CMD_DISABLE    = 3,
-	AGENT_CMD_REG_DONE   = 4,	/* End registration process. */
+	AGENT_CMD_LIST			= 1,
+	AGENT_CMD_ENABLE		= 2,
+	AGENT_CMD_DISABLE		= 3,
+	AGENT_CMD_REG_DONE		= 4,	/* End registration process. */
+	AGENT_CMD_APP_CTX_ENABLE	= 5,
+	AGENT_CMD_APP_CTX_DISABLE	= 6,
 };
 
 /*
@@ -37,11 +40,11 @@ enum lttcomm_agent_command {
  */
 enum lttcomm_agent_ret_code {
 	/* Success, assumed to be the first entry */
-	AGENT_RET_CODE_SUCCESS      = 1,
+	AGENT_RET_CODE_SUCCESS		= 1,
 	/* Invalid command */
-	AGENT_RET_CODE_INVALID      = 2,
+	AGENT_RET_CODE_INVALID		= 2,
 	/* Unknown logger name */
-	AGENT_RET_CODE_UNKNOWN_NAME = 3,
+	AGENT_RET_CODE_UNKNOWN_NAME	= 3,
 	AGENT_RET_CODE_NR,
 };
 
@@ -58,7 +61,7 @@ struct lttcomm_agent_hdr {
  * Enable event command payload. Will be immediately followed by the
  * variable-length string representing the filter expression.
  */
-struct lttcomm_agent_enable {
+struct lttcomm_agent_enable_event {
 	uint32_t loglevel_value;
 	uint32_t loglevel_type;
 	char name[LTTNG_SYMBOL_NAME_LEN];
@@ -68,7 +71,7 @@ struct lttcomm_agent_enable {
 /*
  * Disable event command payload.
  */
-struct lttcomm_agent_disable {
+struct lttcomm_agent_disable_event {
 	char name[LTTNG_SYMBOL_NAME_LEN];
 } LTTNG_PACKED;
 
-- 
2.34.1


From d5734456436e1d49a7806d0fc7b948a76d738f20 Mon Sep 17 00:00:00 2001
From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Mon, 18 Jan 2016 17:22:25 -0500
Subject: [PATCH 09/16] Add variant type support to ust registry and metadata
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---
 src/bin/lttng-sessiond/ust-metadata.c | 188 ++++++++++++++++++++++----
 src/bin/lttng-sessiond/ust-registry.c |  19 ++-
 2 files changed, 175 insertions(+), 32 deletions(-)

diff --git a/src/bin/lttng-sessiond/ust-metadata.c b/src/bin/lttng-sessiond/ust-metadata.c
index 984d5f813..585e23501 100644
--- a/src/bin/lttng-sessiond/ust-metadata.c
+++ b/src/bin/lttng-sessiond/ust-metadata.c
@@ -45,6 +45,11 @@ struct offset_sample {
 	uint64_t measure_delta;		/* lower is better */
 };
 
+static
+int _lttng_field_statedump(struct ust_registry_session *session,
+		const struct ustctl_field *fields, size_t nr_fields,
+		size_t *iter_field, size_t nesting);
+
 static inline
 int fls(unsigned int x)
 {
@@ -179,13 +184,29 @@ end:
 	return ret;
 }
 
+static
+int print_tabs(struct ust_registry_session *session, size_t nesting)
+{
+	size_t i;
+
+	for (i = 0; i < nesting; i++) {
+		int ret;
+
+		ret = lttng_metadata_printf(session, "	");
+		if (ret) {
+			return ret;
+		}
+	}
+	return 0;
+}
+
 /* Called with session registry mutex held. */
 static
 int ust_metadata_enum_statedump(struct ust_registry_session *session,
 		const char *enum_name,
 		uint64_t enum_id,
 		const struct ustctl_integer_type *container_type,
-		const char *field_name)
+		const char *field_name, size_t *iter_field, size_t nesting)
 {
 	struct ust_registry_enum *reg_enum;
 	const struct ustctl_enum_entry *entries;
@@ -204,8 +225,12 @@ int ust_metadata_enum_statedump(struct ust_registry_session *session,
 	entries = reg_enum->entries;
 	nr_entries = reg_enum->nr_entries;
 
+	ret = print_tabs(session, nesting);
+	if (ret) {
+		goto end;
+	}
 	ret = lttng_metadata_printf(session,
-		"		enum : integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u; } {\n",
+		"enum : integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u; } {\n",
 		container_type->size,
 		container_type->alignment,
 		container_type->signedness,
@@ -271,29 +296,85 @@ int ust_metadata_enum_statedump(struct ust_registry_session *session,
 	}
 	ret = lttng_metadata_printf(session, "		} _%s;\n",
 			field_name);
+end:
+	(*iter_field)++;
+	return ret;
+}
+
+
+static
+int _lttng_variant_statedump(struct ust_registry_session *session,
+		const struct ustctl_field *fields, size_t nr_fields,
+		size_t *iter_field, size_t nesting)
+{
+	const struct ustctl_field *variant = &fields[*iter_field];
+	uint32_t nr_choices, i;
+	int ret;
+
+	if (variant->type.atype != ustctl_atype_variant) {
+		ret = -EINVAL;
+		goto end;
+	}
+	nr_choices = variant->type.u.variant.nr_choices;
+	(*iter_field)++;
+	ret = lttng_metadata_printf(session,
+			"		variant <_%s> {\n",
+			variant->type.u.variant.tag_name);
+	if (ret) {
+		goto end;
+	}
+
+	for (i = 0; i < nr_choices; i++) {
+		if (*iter_field >= nr_fields) {
+			ret = -EOVERFLOW;
+			goto end;
+		}
+		ret = _lttng_field_statedump(session,
+				fields, nr_fields,
+				iter_field, nesting + 1);
+	}
+	ret = lttng_metadata_printf(session,
+			"		} _%s;\n",
+			variant->name);
+	if (ret) {
+		goto end;
+	}
 end:
 	return ret;
 }
 
 static
 int _lttng_field_statedump(struct ust_registry_session *session,
-		const struct ustctl_field *field)
+		const struct ustctl_field *fields, size_t nr_fields,
+		size_t *iter_field, size_t nesting)
 {
 	int ret = 0;
 	const char *bo_be = " byte_order = be;";
 	const char *bo_le = " byte_order = le;";
 	const char *bo_native = "";
 	const char *bo_reverse;
+	const struct ustctl_field *field;
+
+	if (*iter_field >= nr_fields) {
+		ret = -EOVERFLOW;
+		goto end;
+	}
+	field = &fields[*iter_field];
 
-	if (session->byte_order == BIG_ENDIAN)
+	if (session->byte_order == BIG_ENDIAN) {
 		bo_reverse = bo_le;
-	else
+	} else {
 		bo_reverse = bo_be;
+	}
 
 	switch (field->type.atype) {
 	case ustctl_atype_integer:
+		ret = print_tabs(session, nesting);
+		if (ret) {
+			goto end;
+		}
 		ret = lttng_metadata_printf(session,
-			"		integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s;\n",
+			"integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s;\n",
 			field->type.u.basic.integer.size,
 			field->type.u.basic.integer.alignment,
 			field->type.u.basic.integer.signedness,
@@ -305,30 +386,40 @@ int _lttng_field_statedump(struct ust_registry_session *session,
 			field->type.u.basic.integer.base,
 			field->type.u.basic.integer.reverse_byte_order ? bo_reverse : bo_native,
 			field->name);
+		(*iter_field)++;
 		break;
 	case ustctl_atype_enum:
 		ret = ust_metadata_enum_statedump(session,
 			field->type.u.basic.enumeration.name,
 			field->type.u.basic.enumeration.id,
 			&field->type.u.basic.enumeration.container_type,
-			field->name);
+			field->name, iter_field, nesting);
 		break;
 	case ustctl_atype_float:
+		ret = print_tabs(session, nesting);
+		if (ret) {
+			goto end;
+		}
 		ret = lttng_metadata_printf(session,
-			"		floating_point { exp_dig = %u; mant_dig = %u; align = %u;%s } _%s;\n",
+			"floating_point { exp_dig = %u; mant_dig = %u; align = %u;%s } _%s;\n",
 			field->type.u.basic._float.exp_dig,
 			field->type.u.basic._float.mant_dig,
 			field->type.u.basic._float.alignment,
 			field->type.u.basic.integer.reverse_byte_order ? bo_reverse : bo_native,
 			field->name);
+		(*iter_field)++;
 		break;
 	case ustctl_atype_array:
 	{
 		const struct ustctl_basic_type *elem_type;
 
+		ret = print_tabs(session, nesting);
+		if (ret) {
+			goto end;
+		}
 		elem_type = &field->type.u.array.elem_type;
 		ret = lttng_metadata_printf(session,
-			"		integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s[%u];\n",
+			"integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s[%u];\n",
 			elem_type->u.basic.integer.size,
 			elem_type->u.basic.integer.alignment,
 			elem_type->u.basic.integer.signedness,
@@ -340,6 +431,7 @@ int _lttng_field_statedump(struct ust_registry_session *session,
 			elem_type->u.basic.integer.base,
 			elem_type->u.basic.integer.reverse_byte_order ? bo_reverse : bo_native,
 			field->name, field->type.u.array.length);
+		(*iter_field)++;
 		break;
 	}
 	case ustctl_atype_sequence:
@@ -349,8 +441,12 @@ int _lttng_field_statedump(struct ust_registry_session *session,
 
 		elem_type = &field->type.u.sequence.elem_type;
 		length_type = &field->type.u.sequence.length_type;
+		ret = print_tabs(session, nesting);
+		if (ret) {
+			goto end;
+		}
 		ret = lttng_metadata_printf(session,
-			"		integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } __%s_length;\n",
+			"integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } __%s_length;\n",
 			length_type->u.basic.integer.size,
 			(unsigned int) length_type->u.basic.integer.alignment,
 			length_type->u.basic.integer.signedness,
@@ -362,11 +458,16 @@ int _lttng_field_statedump(struct ust_registry_session *session,
 			length_type->u.basic.integer.base,
 			length_type->u.basic.integer.reverse_byte_order ? bo_reverse : bo_native,
 			field->name);
-		if (ret)
-			return ret;
+		if (ret) {
+			goto end;
+		}
 
+		ret = print_tabs(session, nesting);
+		if (ret) {
+			goto end;
+		}
 		ret = lttng_metadata_printf(session,
-			"		integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s[ __%s_length ];\n",
+			"integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s[ __%s_length ];\n",
 			elem_type->u.basic.integer.size,
 			(unsigned int) elem_type->u.basic.integer.alignment,
 			elem_type->u.basic.integer.signedness,
@@ -379,20 +480,43 @@ int _lttng_field_statedump(struct ust_registry_session *session,
 			elem_type->u.basic.integer.reverse_byte_order ? bo_reverse : bo_native,
 			field->name,
 			field->name);
+		(*iter_field)++;
 		break;
 	}
 
 	case ustctl_atype_string:
 		/* Default encoding is UTF8 */
+		ret = print_tabs(session, nesting);
+		if (ret) {
+			goto end;
+		}
 		ret = lttng_metadata_printf(session,
-			"		string%s _%s;\n",
+			"string%s _%s;\n",
 			field->type.u.basic.string.encoding == ustctl_encode_ASCII ?
 				" { encoding = ASCII; }" : "",
 			field->name);
+		(*iter_field)++;
+		break;
+	case ustctl_atype_variant:
+		ret = _lttng_variant_statedump(session, fields, nr_fields, iter_field, nesting);
+		if (ret) {
+			goto end;
+		}
+		break;
+	case ustctl_atype_struct:
+		ret = print_tabs(session, nesting);
+		if (ret) {
+			goto end;
+		}
+		ret = lttng_metadata_printf(session,
+			"struct {} _%s;\n",
+			field->name);
+		(*iter_field)++;
 		break;
 	default:
-		return -EINVAL;
+		ret = -EINVAL;
 	}
+end:
 	return ret;
 }
 
@@ -402,16 +526,19 @@ int _lttng_context_metadata_statedump(struct ust_registry_session *session,
 		struct ustctl_field *ctx)
 {
 	int ret = 0;
-	int i;
+	size_t i = 0;
 
 	if (!ctx)
 		return 0;
-	for (i = 0; i < nr_ctx_fields; i++) {
-		const struct ustctl_field *field = &ctx[i];
-
-		ret = _lttng_field_statedump(session, field);
-		if (ret)
-			return ret;
+	for (;;) {
+		if (i >= nr_ctx_fields) {
+			break;
+		}
+		ret = _lttng_field_statedump(session, ctx,
+				nr_ctx_fields, &i, 2);
+		if (ret) {
+			break;
+		}
 	}
 	return ret;
 }
@@ -421,14 +548,17 @@ int _lttng_fields_metadata_statedump(struct ust_registry_session *session,
 		struct ust_registry_event *event)
 {
 	int ret = 0;
-	int i;
+	size_t i = 0;
 
-	for (i = 0; i < event->nr_fields; i++) {
-		const struct ustctl_field *field = &event->fields[i];
-
-		ret = _lttng_field_statedump(session, field);
-		if (ret)
-			return ret;
+	for (;;) {
+		if (i >= event->nr_fields) {
+			break;
+		}
+		ret = _lttng_field_statedump(session, event->fields,
+				event->nr_fields, &i, 2);
+		if (ret) {
+			break;
+		}
 	}
 	return ret;
 }
diff --git a/src/bin/lttng-sessiond/ust-registry.c b/src/bin/lttng-sessiond/ust-registry.c
index 80ea2e570..1990655ef 100644
--- a/src/bin/lttng-sessiond/ust-registry.c
+++ b/src/bin/lttng-sessiond/ust-registry.c
@@ -188,12 +188,22 @@ int validate_event_field(struct ustctl_field *field,
 		const char *event_name,
 		struct ust_app *app)
 {
+	int ret = 0;
+
 	switch(field->type.atype) {
 	case ustctl_atype_integer:
 	case ustctl_atype_enum:
 	case ustctl_atype_array:
 	case ustctl_atype_sequence:
 	case ustctl_atype_string:
+	case ustctl_atype_variant:
+		break;
+	case ustctl_atype_struct:
+		if (field->type.u._struct.nr_fields != 0) {
+			WARN("Unsupported non-empty struct field.");
+			ret = -EINVAL;
+			goto end;
+		}
 		break;
 
 	case ustctl_atype_float:
@@ -205,16 +215,19 @@ int validate_event_field(struct ustctl_field *field,
 				field->type.u.basic._float.mant_dig,
 				field->name,
 				event_name);
-			return -EINVAL;
+			ret = -EINVAL;
+			goto end;
 		default:
 			break;
 		}
 		break;
 
 	default:
-		return -ENOENT;
+		ret = -ENOENT;
+		goto end;
 	}
-	return 0;
+end:
+	return ret;
 }
 
 static
-- 
2.34.1


From b11392a1271d6a8e552f6f509f69a2e32f0c1a2b Mon Sep 17 00:00:00 2001
From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Tue, 26 Jan 2016 10:14:17 -0500
Subject: [PATCH 10/16] Allow $app.provider:ctxname in filter, enum, variant
 identifiers
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---
 src/bin/lttng-sessiond/ust-metadata.c         | 51 ++++++++++++++++---
 src/lib/lttng-ctl/filter/filter-lexer.l       |  3 +-
 .../filter/filter-visitor-generate-ir.c       | 38 ++++++--------
 3 files changed, 61 insertions(+), 31 deletions(-)

diff --git a/src/bin/lttng-sessiond/ust-metadata.c b/src/bin/lttng-sessiond/ust-metadata.c
index 585e23501..4fcdf2b1e 100644
--- a/src/bin/lttng-sessiond/ust-metadata.c
+++ b/src/bin/lttng-sessiond/ust-metadata.c
@@ -200,6 +200,24 @@ int print_tabs(struct ust_registry_session *session, size_t nesting)
 	return 0;
 }
 
+static
+void sanitize_ctf_identifier(char *out, const char *in)
+{
+	size_t i;
+
+	for (i = 0; i < LTTNG_UST_SYM_NAME_LEN; i++) {
+		switch (in[i]) {
+		case '.':
+		case '$':
+		case ':':
+			out[i] = '_';
+			break;
+		default:
+			out[i] = in[i];
+		}
+	}
+}
+
 /* Called with session registry mutex held. */
 static
 int ust_metadata_enum_statedump(struct ust_registry_session *session,
@@ -213,6 +231,7 @@ int ust_metadata_enum_statedump(struct ust_registry_session *session,
 	size_t nr_entries;
 	int ret = 0;
 	size_t i;
+	char identifier[LTTNG_UST_SYM_NAME_LEN];
 
 	rcu_read_lock();
 	reg_enum = ust_registry_lookup_enum_by_id(session, enum_name, enum_id);
@@ -248,8 +267,12 @@ int ust_metadata_enum_statedump(struct ust_registry_session *session,
 		const struct ustctl_enum_entry *entry = &entries[i];
 		int j, len;
 
+		ret = print_tabs(session, nesting);
+		if (ret) {
+			goto end;
+		}
 		ret = lttng_metadata_printf(session,
-				"			\"");
+				"\"");
 		if (ret) {
 			goto end;
 		}
@@ -294,14 +317,18 @@ int ust_metadata_enum_statedump(struct ust_registry_session *session,
 			goto end;
 		}
 	}
-	ret = lttng_metadata_printf(session, "		} _%s;\n",
-			field_name);
+	sanitize_ctf_identifier(identifier, field_name);
+	ret = print_tabs(session, nesting);
+	if (ret) {
+		goto end;
+	}
+	ret = lttng_metadata_printf(session, "} _%s;\n",
+			identifier);
 end:
 	(*iter_field)++;
 	return ret;
 }
 
-
 static
 int _lttng_variant_statedump(struct ust_registry_session *session,
 		const struct ustctl_field *fields, size_t nr_fields,
@@ -310,6 +337,7 @@ int _lttng_variant_statedump(struct ust_registry_session *session,
 	const struct ustctl_field *variant = &fields[*iter_field];
 	uint32_t nr_choices, i;
 	int ret;
+	char identifier[LTTNG_UST_SYM_NAME_LEN];
 
 	if (variant->type.atype != ustctl_atype_variant) {
 		ret = -EINVAL;
@@ -317,9 +345,14 @@ int _lttng_variant_statedump(struct ust_registry_session *session,
 	}
 	nr_choices = variant->type.u.variant.nr_choices;
 	(*iter_field)++;
+	sanitize_ctf_identifier(identifier, variant->type.u.variant.tag_name);
+	ret = print_tabs(session, nesting);
+	if (ret) {
+		goto end;
+	}
 	ret = lttng_metadata_printf(session,
-			"		variant <_%s> {\n",
-			variant->type.u.variant.tag_name);
+			"variant <_%s> {\n",
+			identifier);
 	if (ret) {
 		goto end;
 	}
@@ -333,9 +366,11 @@ int _lttng_variant_statedump(struct ust_registry_session *session,
 				fields, nr_fields,
 				iter_field, nesting + 1);
 	}
+	sanitize_ctf_identifier(identifier, variant->name);
+	ret = print_tabs(session, nesting);
 	ret = lttng_metadata_printf(session,
-			"		} _%s;\n",
-			variant->name);
+			"} _%s;\n",
+			identifier);
 	if (ret) {
 		goto end;
 	}
diff --git a/src/lib/lttng-ctl/filter/filter-lexer.l b/src/lib/lttng-ctl/filter/filter-lexer.l
index ab887f74c..a45b6e838 100644
--- a/src/lib/lttng-ctl/filter/filter-lexer.l
+++ b/src/lib/lttng-ctl/filter/filter-lexer.l
@@ -49,7 +49,8 @@ HEXDIGIT			[0-9A-Fa-f]
 OCTALDIGIT			[0-7]
 UCHARLOWERCASE			\\u{HEXDIGIT}{4}
 UCHARUPPERCASE			\\U{HEXDIGIT}{8}
-ID_NONDIGIT			{NONDIGIT}|{UCHARLOWERCASE}|{UCHARUPPERCASE}
+ID_EXTRA_CHAR			(":"|".")
+ID_NONDIGIT			{NONDIGIT}|{UCHARLOWERCASE}|{UCHARUPPERCASE}|{ID_EXTRA_CHAR}
 IDENTIFIER			{ID_NONDIGIT}({ID_NONDIGIT}|{DIGIT})*
 ESCSEQ				\\(\'|\"|\?|\\|a|b|f|n|r|t|v|{OCTALDIGIT}{1,3}|u{HEXDIGIT}{4}|U{HEXDIGIT}{8}|x{HEXDIGIT}+)
 %%
diff --git a/src/lib/lttng-ctl/filter/filter-visitor-generate-ir.c b/src/lib/lttng-ctl/filter/filter-visitor-generate-ir.c
index d694dcc16..f734b56e3 100644
--- a/src/lib/lttng-ctl/filter/filter-visitor-generate-ir.c
+++ b/src/lib/lttng-ctl/filter/filter-visitor-generate-ir.c
@@ -418,36 +418,30 @@ struct ir_op *make_expression(struct filter_parser_ctx *ctx,
 					side);
 	case AST_EXP_GLOBAL_IDENTIFIER:
 	{
-		struct filter_node *next;
+		const char *name;
 
-		if (node->u.expression.pre_op == AST_LINK_UNKNOWN) {
-			fprintf(stderr, "[error] %s: global identifiers need chained identifier \n", __func__);
-			return NULL;
-		}
-		/* We currently only support $ctx (context) identifiers */
+		/*
+		 * We currently only support $ctx (context) and $app
+		 * identifiers.
+		 */
 		if (strncmp(node->u.expression.u.identifier,
-				"$ctx", strlen("$ctx")) != 0) {
-			fprintf(stderr, "[error] %s: \"%s\" global identifier is unknown. Only \"$ctx\" currently implemented.\n", __func__, node->u.expression.u.identifier);
-			return NULL;
-		}
-		next = node->u.expression.next;
-		if (!next) {
-			fprintf(stderr, "[error] %s: Expecting a context name, e.g. \'$ctx.name\'.\n", __func__);
+				"$ctx.", strlen("$ctx.")) != 0
+			&& strncmp(node->u.expression.u.identifier,
+				"$app.", strlen("$app.")) != 0) {
+			fprintf(stderr, "[error] %s: \"%s\" global identifier is unknown. Only \"$ctx\" and \"$app\" are currently implemented.\n", __func__, node->u.expression.u.identifier);
 			return NULL;
 		}
-		if (next->type != NODE_EXPRESSION) {
-			fprintf(stderr, "[error] %s: Expecting expression.\n", __func__);
+		name = strchr(node->u.expression.u.identifier, '.');
+		if (!name) {
+			fprintf(stderr, "[error] %s: Expecting '.'\n", __func__);
 			return NULL;
 		}
-		if (next->u.expression.type != AST_EXP_IDENTIFIER) {
-			fprintf(stderr, "[error] %s: Expecting identifier.\n", __func__);
-			return NULL;
-		}
-		if (next->u.expression.pre_op != AST_LINK_UNKNOWN) {
-			fprintf(stderr, "[error] %s: dotted and dereferenced identifiers not supported after identifier\n", __func__);
+		name++;	/* Skip . */
+		if (!strlen(name)) {
+			fprintf(stderr, "[error] %s: Expecting a context name, e.g. \'$ctx.name\'.\n", __func__);
 			return NULL;
 		}
-		return make_op_load_get_context_ref(next->u.expression.u.identifier,
+		return make_op_load_get_context_ref(node->u.expression.u.identifier,
 					side);
 	}
 	case AST_EXP_NESTED:
-- 
2.34.1


From 8fb1291c63c56ea15363a2628e7a8bac9b9c035c Mon Sep 17 00:00:00 2001
From: =?utf8?q?J=C3=A9r=C3=A9mie=20Galarneau?=
 <jeremie.galarneau@efficios.com>
Date: Wed, 3 Feb 2016 18:51:29 -0500
Subject: [PATCH 11/16] Compare provider and context names in
 trace_ust_match_context
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---
 src/bin/lttng-sessiond/trace-ust.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/bin/lttng-sessiond/trace-ust.c b/src/bin/lttng-sessiond/trace-ust.c
index 4ed8fb1a5..1c325fb25 100644
--- a/src/bin/lttng-sessiond/trace-ust.c
+++ b/src/bin/lttng-sessiond/trace-ust.c
@@ -589,6 +589,15 @@ int trace_ust_match_context(struct ltt_ust_context *uctx,
 			return 0;
 		}
 		break;
+	case LTTNG_UST_CONTEXT_APP_CONTEXT:
+		assert(uctx->ctx.u.app_ctx.provider_name);
+		assert(uctx->ctx.u.app_ctx.ctx_name);
+		if (strcmp(uctx->ctx.u.app_ctx.provider_name,
+				ctx->u.app_ctx.provider_name) ||
+				strcmp(uctx->ctx.u.app_ctx.ctx_name,
+				ctx->u.app_ctx.ctx_name)) {
+			return 0;
+		}
 	default:
 		break;
 
-- 
2.34.1


From aa217ae263e7509be2907c1c28aebbade15da6db Mon Sep 17 00:00:00 2001
From: =?utf8?q?J=C3=A9r=C3=A9mie=20Galarneau?=
 <jeremie.galarneau@efficios.com>
Date: Fri, 5 Feb 2016 17:10:41 -0500
Subject: [PATCH 12/16] Enable agent application contexts if filter has such
 dependencies
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---
 src/bin/lttng-sessiond/cmd.c   |   2 +-
 src/bin/lttng-sessiond/event.c |  74 +++++++++++++++++++++++-
 src/common/Makefile.am         |   3 +-
 src/common/context.c           |  93 ++++++++++++++++++++++++++++++
 src/common/context.h           |  35 ++++++++++++
 src/common/filter.c            | 100 +++++++++++++++++++++++++++++++++
 src/common/filter.h            |  46 +++++++++++++++
 7 files changed, 350 insertions(+), 3 deletions(-)
 create mode 100644 src/common/context.c
 create mode 100644 src/common/context.h
 create mode 100644 src/common/filter.c
 create mode 100644 src/common/filter.h

diff --git a/src/bin/lttng-sessiond/cmd.c b/src/bin/lttng-sessiond/cmd.c
index eca3cf439..83286a002 100644
--- a/src/bin/lttng-sessiond/cmd.c
+++ b/src/bin/lttng-sessiond/cmd.c
@@ -1790,7 +1790,7 @@ static int _cmd_enable_event(struct ltt_session *session,
 		filter_expression = NULL;
 		filter = NULL;
 		exclusion = NULL;
-		if (ret != LTTNG_OK) {
+		if (ret != LTTNG_OK && ret != LTTNG_ERR_UST_EVENT_ENABLED) {
 			goto error;
 		}
 		break;
diff --git a/src/bin/lttng-sessiond/event.c b/src/bin/lttng-sessiond/event.c
index e4c79df74..b7b80d366 100644
--- a/src/bin/lttng-sessiond/event.c
+++ b/src/bin/lttng-sessiond/event.c
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
+ * Copyright (C) 2016 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License, version 2 only,
@@ -23,6 +24,8 @@
 #include <lttng/lttng.h>
 #include <common/error.h>
 #include <common/sessiond-comm/sessiond-comm.h>
+#include <common/filter.h>
+#include <common/context.h>
 
 #include "channel.h"
 #include "event.h"
@@ -416,6 +419,67 @@ error:
 	return ret;
 }
 
+/*
+ * Check if this event's filter requires the activation of application contexts
+ * and enable them in the agent.
+ */
+static int add_filter_app_ctx(struct lttng_filter_bytecode *bytecode,
+		const char *filter_expression, struct agent *agt)
+{
+	int ret = LTTNG_OK;
+	char *provider_name = NULL, *ctx_name = NULL;
+	struct bytecode_symbol_iterator *it =
+			bytecode_symbol_iterator_create(bytecode);
+
+	if (!it) {
+		ret = LTTNG_ERR_NOMEM;
+		goto end;
+	}
+
+	do {
+		struct lttng_event_context ctx;
+		const char *symbol_name =
+				bytecode_symbol_iterator_get_name(it);
+
+		if (parse_application_context(symbol_name, &provider_name,
+				&ctx_name)) {
+			/* Not an application context. */
+			continue;
+		}
+
+		ctx.ctx = LTTNG_EVENT_CONTEXT_APP_CONTEXT;
+		ctx.u.app_ctx.provider_name = provider_name;
+		ctx.u.app_ctx.ctx_name = ctx_name;
+
+		/* Recognized an application context. */
+		DBG("Enabling event with filter expression \"%s\" requires enabling the %s:%s application context.",
+				filter_expression, provider_name, ctx_name);
+
+		ret = agent_add_context(&ctx, agt);
+		if (ret != LTTNG_OK) {
+			ERR("Failed to add application context %s:%s.",
+					provider_name, ctx_name);
+			goto end;
+		}
+
+		ret = agent_enable_context(&ctx, agt->domain);
+		if (ret != LTTNG_OK) {
+			ERR("Failed to enable application context %s:%s.",
+					provider_name, ctx_name);
+			goto end;
+		}
+
+		free(provider_name);
+		free(ctx_name);
+		provider_name = ctx_name = NULL;
+	} while (bytecode_symbol_iterator_next(it) == 0);
+end:
+	free(provider_name);
+	free(ctx_name);
+	bytecode_symbol_iterator_destroy(it);
+	return ret;
+}
+
 /*
  * Enable a single agent event for a given UST session.
  *
@@ -439,7 +503,7 @@ int event_agent_enable(struct ltt_ust_session *usess,
 			filter_expression ? filter_expression : "NULL");
 
 	aevent = agent_find_event(event->name, event->loglevel_type,
-		event->loglevel, filter_expression, agt);
+			event->loglevel, filter_expression, agt);
 	if (!aevent) {
 		aevent = agent_create_event(event->name, event->loglevel_type,
 				event->loglevel, filter,
@@ -448,6 +512,7 @@ int event_agent_enable(struct ltt_ust_session *usess,
 			ret = LTTNG_ERR_NOMEM;
 			goto error;
 		}
+
 		created = 1;
 	}
 
@@ -456,6 +521,13 @@ int event_agent_enable(struct ltt_ust_session *usess,
 		goto end;
 	}
 
+	if (created && filter) {
+		ret = add_filter_app_ctx(filter, filter_expression, agt);
+		if (ret != LTTNG_OK) {
+			goto error;
+		}
+	}
+
 	ret = agent_enable_event(aevent, agt->domain);
 	if (ret != LTTNG_OK) {
 		goto error;
diff --git a/src/common/Makefile.am b/src/common/Makefile.am
index 148130177..66146bb73 100644
--- a/src/common/Makefile.am
+++ b/src/common/Makefile.am
@@ -72,7 +72,8 @@ libcommon_la_SOURCES = error.h error.c utils.c utils.h runas.c runas.h \
                        pipe.c pipe.h readwrite.c readwrite.h \
                        mi-lttng.h mi-lttng.c \
                        daemonize.c daemonize.h \
-                       sessiond-comm/unix.c sessiond-comm/unix.h
+                       sessiond-comm/unix.c sessiond-comm/unix.h \
+                       filter.c filter.h context.c context.h
 
 libcommon_la_LIBADD = \
 		-luuid \
diff --git a/src/common/context.c b/src/common/context.c
new file mode 100644
index 000000000..ead6bb3f5
--- /dev/null
+++ b/src/common/context.c
@@ -0,0 +1,93 @@
+/*
+ * context.c
+ *
+ * LTTng context utilities.
+ *
+ * Copyright 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,
+ * as published by the Free Software Foundation.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "context.h"
+#include <stddef.h>
+#include <string.h>
+#include <common/error.h>
+#include <common/macros.h>
+
+int parse_application_context(const char *str, char **out_provider_name,
+		char **out_ctx_name)
+{
+	const char app_ctx_prefix[] = "$app.";
+	char *provider_name = NULL, *ctx_name = NULL;
+	size_t i, len, colon_pos = 0, provider_name_len, ctx_name_len;
+
+	if (!str || !out_provider_name || !out_ctx_name) {
+		goto not_found;
+	}
+
+	len = strlen(str);
+	if (len <= sizeof(app_ctx_prefix) - 1) {
+		goto not_found;
+	}
+
+	/* String starts with $app. */
+	if (strncmp(str, app_ctx_prefix, sizeof(app_ctx_prefix) - 1)) {
+		goto not_found;
+	}
+
+	/* Validate that the ':' separator is present. */
+	for (i = sizeof(app_ctx_prefix); i < len; i++) {
+		const char c = str[i];
+
+		if (c == ':') {
+			colon_pos = i;
+			break;
+		}
+	}
+
+	/*
+	 * No colon found or no ctx name ("$app.provider:") or no provider name
+	 * given ("$app.:..."), which is invalid.
+	 */
+	if (!colon_pos || colon_pos == len ||
+			colon_pos == sizeof(app_ctx_prefix)) {
+		goto not_found;
+	}
+
+	provider_name_len = colon_pos - sizeof(app_ctx_prefix) + 2;
+	provider_name = zmalloc(provider_name_len);
+	if (!provider_name) {
+		PERROR("malloc provider_name");
+		goto not_found;
+	}
+	strncpy(provider_name, str + sizeof(app_ctx_prefix) - 1,
+			provider_name_len - 1);
+
+	ctx_name_len = len - colon_pos;
+	ctx_name = zmalloc(ctx_name_len);
+	if (!ctx_name) {
+		PERROR("malloc ctx_name");
+		goto not_found;
+	}
+	strncpy(ctx_name, str + colon_pos + 1, ctx_name_len - 1);
+
+	*out_provider_name = provider_name;
+	*out_ctx_name = ctx_name;
+	return 0;
+not_found:
+	free(provider_name);
+	free(ctx_name);
+	return -1;
+}
+
diff --git a/src/common/context.h b/src/common/context.h
new file mode 100644
index 000000000..5552f4da5
--- /dev/null
+++ b/src/common/context.h
@@ -0,0 +1,35 @@
+/*
+ * Copyright 2016 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License, version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 51
+ * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef LTTNG_COMMON_CONTEXT_H
+#define LTTNG_COMMON_CONTEXT_H
+
+/*
+ * Parse string as an application context of the form
+ * "$app.provider_name:context_name" and return the provider name and context
+ * name separately.
+ *
+ * provider_name and ctx_name are returned only if an application context name
+ * was successfully parsed and must be freed by the caller.
+ *
+ * Returns 0 if the string is a valid application context, else a negative
+ * value on error.
+ */
+int parse_application_context(const char *str, char **provider_name,
+		char **ctx_name);
+
+#endif /* LTTNG_COMMON_CONTEXT_H */
diff --git a/src/common/filter.c b/src/common/filter.c
new file mode 100644
index 000000000..f103d240f
--- /dev/null
+++ b/src/common/filter.c
@@ -0,0 +1,100 @@
+/*
+ * filter.c
+ *
+ * LTTng filter bytecode utilities.
+ *
+ * Copyright 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,
+ * as published by the Free Software Foundation.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "filter.h"
+#include <stddef.h>
+
+struct bytecode_symbol_iterator {
+	/* No ownership of bytecode is taken. */
+	char *bytecode;
+	size_t offset, len;
+};
+
+struct bytecode_symbol_iterator *bytecode_symbol_iterator_create(
+		struct lttng_filter_bytecode *bytecode)
+{
+	struct bytecode_symbol_iterator *it = NULL;
+
+	if (!bytecode) {
+		goto end;
+	}
+
+	it = zmalloc(sizeof(*it));
+	if (!it) {
+		goto end;
+	}
+
+	it->bytecode = bytecode->data;
+	it->offset = bytecode->reloc_table_offset;
+	it->len = bytecode->len;
+end:
+	return it;
+}
+
+int bytecode_symbol_iterator_next(struct bytecode_symbol_iterator *it)
+{
+	int ret;
+	size_t len;
+
+	if (!it || it->offset >= it->len) {
+		ret = -1;
+		goto end;
+	}
+
+	len = strlen(it->bytecode + it->offset + sizeof(uint16_t)) + 1;
+	it->offset += len + sizeof(uint16_t);
+	ret = it->offset >= it->len ? -1 : 0;
+end:
+	return ret;
+}
+
+int bytecode_symbol_iterator_get_type(struct bytecode_symbol_iterator *it)
+{
+	int ret;
+
+	if (!it) {
+		ret = -1;
+		goto end;
+	}
+
+	ret = *((uint16_t *) (it->bytecode + it->offset));
+end:
+	return ret;
+ }
+
+const char *bytecode_symbol_iterator_get_name(
+		struct bytecode_symbol_iterator *it)
+{
+	const char *ret = NULL;
+
+	if (!it) {
+		goto end;
+	}
+
+	ret = it->bytecode + it->offset + sizeof(uint16_t);
+end:
+	return ret;
+}
+
+void bytecode_symbol_iterator_destroy(struct bytecode_symbol_iterator *it)
+{
+	free(it);
+}
diff --git a/src/common/filter.h b/src/common/filter.h
new file mode 100644
index 000000000..051177a0e
--- /dev/null
+++ b/src/common/filter.h
@@ -0,0 +1,46 @@
+/*
+ * Copyright 2016 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License, version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 51
+ * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef LTTNG_COMMON_FILTER_H
+#define LTTNG_COMMON_FILTER_H
+
+#include <common/sessiond-comm/sessiond-comm.h>
+
+struct bytecode_symbol_iterator;
+
+/*
+ * Create an iterator on a bytecode's symbols. The iterator points to the
+ * first element after creation.
+ */
+struct bytecode_symbol_iterator *bytecode_symbol_iterator_create(
+		struct lttng_filter_bytecode *bytecode);
+
+/*
+ * Advance iterator of one element.
+ *
+ * Returns 0 if a next element exists or a negative value at the end.
+ */
+int bytecode_symbol_iterator_next(struct bytecode_symbol_iterator *it);
+
+int bytecode_symbol_iterator_get_type(struct bytecode_symbol_iterator *it);
+
+const char *bytecode_symbol_iterator_get_name(
+		struct bytecode_symbol_iterator *it);
+
+void bytecode_symbol_iterator_destroy(struct bytecode_symbol_iterator *it);
+
+#endif /* LTTNG_COMMON_FILTER_H */
-- 
2.34.1


From a98e27bfab122c75634b9d43164061963be60bc2 Mon Sep 17 00:00:00 2001
From: =?utf8?q?J=C3=A9r=C3=A9mie=20Galarneau?=
 <jeremie.galarneau@efficios.com>
Date: Tue, 9 Feb 2016 15:11:32 -0500
Subject: [PATCH 13/16] Fix typos in error descriptions
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---
 include/lttng/lttng-error.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/lttng/lttng-error.h b/include/lttng/lttng-error.h
index 1340dc29b..65ec20572 100644
--- a/include/lttng/lttng-error.h
+++ b/include/lttng/lttng-error.h
@@ -32,7 +32,7 @@ extern "C" {
 enum lttng_error_code {
 	LTTNG_OK                         = 10,  /* Ok */
 	LTTNG_ERR_UNK                    = 11,  /* Unknown Error */
-	LTTNG_ERR_UND                    = 12,  /* Undefine command */
+	LTTNG_ERR_UND                    = 12,  /* Undefined command */
 	LTTNG_ERR_SESSION_STARTED        = 13,  /* Session is running */
 	LTTNG_ERR_UNKNOWN_DOMAIN         = 14,  /* Tracing domain not known */
 	LTTNG_ERR_NOT_SUPPORTED          = 15,  /* Operation not supported */
@@ -106,7 +106,7 @@ enum lttng_error_code {
 	LTTNG_ERR_NEED_CHANNEL_NAME      = 83,	/* Non-default channel exists within session: channel name needs to be specified with '-c name' */
 	LTTNG_ERR_NO_UST                 = 84,  /* LTTng-UST tracer is not supported. Please rebuild lttng-tools with lttng-ust support enabled. */
 	LTTNG_ERR_SAVE_FILE_EXIST        = 85,  /* Session file already exists. */
-	LTTNG_ERR_SAVE_IO_FAIL           = 86,  /* IO error while writting session configuration */
+	LTTNG_ERR_SAVE_IO_FAIL           = 86,  /* IO error while writing session configuration */
 	LTTNG_ERR_LOAD_INVALID_CONFIG    = 87,  /* Invalid session configuration */
 	LTTNG_ERR_LOAD_IO_FAIL           = 88,  /* IO error while reading a session configuration */
 	LTTNG_ERR_LOAD_SESSION_NOENT     = 89,  /* Session file not found */
-- 
2.34.1


From a44b83a535d147f8c04441a3e465996bb6b83903 Mon Sep 17 00:00:00 2001
From: =?utf8?q?J=C3=A9r=C3=A9mie=20Galarneau?=
 <jeremie.galarneau@efficios.com>
Date: Tue, 9 Feb 2016 15:12:33 -0500
Subject: [PATCH 14/16] Introduce application contexts to session configuration
 schema
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

Session configuration schema version is bumped to 2.8.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---
 src/bin/lttng-sessiond/save.c          | 195 +++++++++++++++++--------
 src/common/config/config-session-abi.h |   6 +-
 src/common/config/session-config.c     |  45 +++++-
 src/common/config/session.xsd          |  11 +-
 4 files changed, 193 insertions(+), 64 deletions(-)

diff --git a/src/bin/lttng-sessiond/save.c b/src/bin/lttng-sessiond/save.c
index a6fea46ce..b33287855 100644
--- a/src/bin/lttng-sessiond/save.c
+++ b/src/bin/lttng-sessiond/save.c
@@ -261,6 +261,9 @@ const char *get_ust_context_type_string(
 	case LTTNG_UST_CONTEXT_PTHREAD_ID:
 		context_type_string = config_event_context_pthread_id;
 		break;
+	case LTTNG_UST_CONTEXT_APP_CONTEXT:
+		context_type_string = config_event_context_app;
+		break;
 	case LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER:
 		/*
 		 * Error, should not be stored in the XML, perf contexts
@@ -845,7 +848,8 @@ int save_kernel_context(struct config_writer *writer,
 	}
 
 	if (ctx->ctx == LTTNG_KERNEL_CONTEXT_PERF_CPU_COUNTER) {
-		ret = config_writer_open_element(writer, config_element_perf);
+		ret = config_writer_open_element(writer,
+				config_element_context_perf);
 		if (ret) {
 			ret = LTTNG_ERR_SAVE_IO_FAIL;
 			goto end;
@@ -942,6 +946,124 @@ end:
 	return ret;
 }
 
+static
+int save_ust_context_perf_thread_counter(struct config_writer *writer,
+		struct ltt_ust_context *ctx)
+{
+	int ret;
+
+	assert(writer);
+	assert(ctx);
+
+	/* Perf contexts are saved as event_perf_context_type */
+	ret = config_writer_open_element(writer, config_element_context_perf);
+	if (ret) {
+		ret = LTTNG_ERR_SAVE_IO_FAIL;
+		goto end;
+	}
+
+	ret = config_writer_write_element_unsigned_int(writer,
+			config_element_type, ctx->ctx.u.perf_counter.type);
+	if (ret) {
+		ret = LTTNG_ERR_SAVE_IO_FAIL;
+		goto end;
+	}
+
+	ret = config_writer_write_element_unsigned_int(writer,
+			config_element_config, ctx->ctx.u.perf_counter.config);
+	if (ret) {
+		ret = LTTNG_ERR_SAVE_IO_FAIL;
+		goto end;
+	}
+
+	ret = config_writer_write_element_string(writer, config_element_name,
+			ctx->ctx.u.perf_counter.name);
+	if (ret) {
+		ret = LTTNG_ERR_SAVE_IO_FAIL;
+		goto end;
+	}
+
+	/* /perf */
+	ret = config_writer_close_element(writer);
+	if (ret) {
+		ret = LTTNG_ERR_SAVE_IO_FAIL;
+		goto end;
+	}
+end:
+	return ret;
+}
+
+static
+int save_ust_context_app_ctx(struct config_writer *writer,
+		struct ltt_ust_context *ctx)
+{
+	int ret;
+
+	assert(writer);
+	assert(ctx);
+
+	/* Application contexts are saved as application_context_type */
+	ret = config_writer_open_element(writer, config_element_context_app);
+	if (ret) {
+		ret = LTTNG_ERR_SAVE_IO_FAIL;
+		goto end;
+	}
+
+	ret = config_writer_write_element_string(writer,
+			config_element_context_app_provider_name,
+			ctx->ctx.u.app_ctx.provider_name);
+	if (ret) {
+		ret = LTTNG_ERR_SAVE_IO_FAIL;
+		goto end;
+	}
+
+	ret = config_writer_write_element_string(writer,
+			config_element_context_app_ctx_name,
+			ctx->ctx.u.app_ctx.ctx_name);
+	if (ret) {
+		ret = LTTNG_ERR_SAVE_IO_FAIL;
+		goto end;
+	}
+
+	/* /app */
+	ret = config_writer_close_element(writer);
+	if (ret) {
+		ret = LTTNG_ERR_SAVE_IO_FAIL;
+		goto end;
+	}
+end:
+	return ret;
+}
+
+static
+int save_ust_context_generic(struct config_writer *writer,
+		struct ltt_ust_context *ctx)
+{
+	int ret;
+	const char *context_type_string;
+
+	assert(writer);
+	assert(ctx);
+
+	/* Save context as event_context_type_type */
+	context_type_string = get_ust_context_type_string(
+			ctx->ctx.ctx);
+	if (!context_type_string) {
+		ERR("Unsupported UST context type.");
+		ret = LTTNG_ERR_SAVE_IO_FAIL;
+		goto end;
+	}
+
+	ret = config_writer_write_element_string(writer,
+			config_element_type, context_type_string);
+	if (ret) {
+		ret = LTTNG_ERR_SAVE_IO_FAIL;
+		goto end;
+	}
+end:
+	return ret;
+}
+
 static
 int save_ust_context(struct config_writer *writer,
 	struct cds_list_head *ctx_list)
@@ -959,9 +1081,6 @@ int save_ust_context(struct config_writer *writer,
 	}
 
 	cds_list_for_each_entry(ctx, ctx_list, list) {
-		const char *context_type_string;
-
-
 		ret = config_writer_open_element(writer,
 			config_element_context);
 		if (ret) {
@@ -969,61 +1088,19 @@ int save_ust_context(struct config_writer *writer,
 			goto end;
 		}
 
-		if (ctx->ctx.ctx == LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER) {
-			/* Perf contexts are saved as event_perf_context_type */
-			ret = config_writer_open_element(writer,
-				config_element_perf);
-			if (ret) {
-				ret = LTTNG_ERR_SAVE_IO_FAIL;
-				goto end;
-			}
-
-			ret = config_writer_write_element_unsigned_int(writer,
-				config_element_type,
-				ctx->ctx.u.perf_counter.type);
-			if (ret) {
-				ret = LTTNG_ERR_SAVE_IO_FAIL;
-				goto end;
-			}
-
-			ret = config_writer_write_element_unsigned_int(writer,
-				config_element_config,
-				ctx->ctx.u.perf_counter.config);
-			if (ret) {
-				ret = LTTNG_ERR_SAVE_IO_FAIL;
-				goto end;
-			}
-
-			ret = config_writer_write_element_string(writer,
-				config_element_name,
-				ctx->ctx.u.perf_counter.name);
-			if (ret) {
-				ret = LTTNG_ERR_SAVE_IO_FAIL;
-				goto end;
-			}
-
-			/* /perf */
-			ret = config_writer_close_element(writer);
-			if (ret) {
-				ret = LTTNG_ERR_SAVE_IO_FAIL;
-				goto end;
-			}
-		} else {
-			/* Save context as event_context_type_type */
-			context_type_string = get_ust_context_type_string(
-				ctx->ctx.ctx);
-			if (!context_type_string) {
-				ERR("Unsupported UST context type.")
-					ret = LTTNG_ERR_INVALID;
-				goto end;
-			}
-
-			ret = config_writer_write_element_string(writer,
-				config_element_type, context_type_string);
-			if (ret) {
-				ret = LTTNG_ERR_SAVE_IO_FAIL;
-				goto end;
-			}
+		switch (ctx->ctx.ctx) {
+		case LTTNG_UST_CONTEXT_PERF_THREAD_COUNTER:
+			ret = save_ust_context_perf_thread_counter(writer, ctx);
+			break;
+		case LTTNG_UST_CONTEXT_APP_CONTEXT:
+			ret = save_ust_context_app_ctx(writer, ctx);
+			break;
+		default:
+			/* Save generic context. */
+			ret = save_ust_context_generic(writer, ctx);
+		}
+		if (ret) {
+			goto end;
 		}
 
 		/* /context */
diff --git a/src/common/config/config-session-abi.h b/src/common/config/config-session-abi.h
index 9251b22fc..23f8c8416 100644
--- a/src/common/config/config-session-abi.h
+++ b/src/common/config/config-session-abi.h
@@ -50,7 +50,10 @@ extern const char * const config_element_type;
 extern const char * const config_element_buffer_type;
 extern const char * const config_element_session;
 extern const char * const config_element_sessions;
-extern const char * const config_element_perf;
+extern const char * const config_element_context_perf;
+extern const char * const config_element_context_app;
+extern const char * const config_element_context_app_provider_name;
+extern const char * const config_element_context_app_ctx_name;
 extern const char * const config_element_config;
 extern const char * const config_element_started;
 extern const char * const config_element_snapshot_mode;
@@ -116,5 +119,6 @@ extern const char * const config_event_context_pthread_id;
 extern const char * const config_event_context_hostname;
 extern const char * const config_event_context_ip;
 extern const char * const config_event_context_perf_thread_counter;
+extern const char * const config_event_context_app;
 
 #endif /* CONFIG_SESSION_INTERNAL_H */
diff --git a/src/common/config/session-config.c b/src/common/config/session-config.c
index 87e9c03c8..ba938d9f1 100644
--- a/src/common/config/session-config.c
+++ b/src/common/config/session-config.c
@@ -99,7 +99,10 @@ const char * const config_element_type = "type";
 const char * const config_element_buffer_type = "buffer_type";
 const char * const config_element_session = "session";
 const char * const config_element_sessions = "sessions";
-const char * const config_element_perf = "perf";
+const char * const config_element_context_perf = "perf";
+const char * const config_element_context_app = "app";
+const char * const config_element_context_app_provider_name = "provider_name";
+const char * const config_element_context_app_ctx_name = "ctx_name";
 const char * const config_element_config = "config";
 const char * const config_element_started = "started";
 const char * const config_element_snapshot_mode = "snapshot_mode";
@@ -165,6 +168,8 @@ const char * const config_event_context_pthread_id = "PTHREAD_ID";
 const char * const config_event_context_hostname = "HOSTNAME";
 const char * const config_event_context_ip = "IP";
 const char * const config_event_context_perf_thread_counter = "PERF_THREAD_COUNTER";
+const char * const config_event_context_app = "APP";
+
 
 struct consumer_output {
 	int enabled;
@@ -1991,6 +1996,7 @@ int process_context_node(xmlNodePtr context_node,
 		config_element_type)) {
 		/* type */
 		xmlChar *content = xmlNodeGetContent(context_child_node);
+
 		if (!content) {
 			ret = -LTTNG_ERR_NOMEM;
 			goto end;
@@ -2004,10 +2010,11 @@ int process_context_node(xmlNodePtr context_node,
 		}
 
 		context.ctx = ret;
-	} else {
+	} else if (!strcmp((const char *) context_child_node->name,
+		config_element_context_perf)) {
+		/* perf */
 		xmlNodePtr perf_attr_node;
 
-		/* perf */
 		context.ctx = handle->domain.type == LTTNG_DOMAIN_KERNEL ?
 			LTTNG_EVENT_CONTEXT_PERF_CPU_COUNTER :
 			LTTNG_EVENT_CONTEXT_PERF_THREAD_COUNTER;
@@ -2085,9 +2092,41 @@ int process_context_node(xmlNodePtr context_node,
 				free(content);
 			}
 		}
+	} else if (!strcmp((const char *) context_child_node->name,
+		config_element_context_app)) {
+		/* application context */
+		xmlNodePtr app_ctx_node;
+
+		context.ctx = LTTNG_EVENT_CONTEXT_APP_CONTEXT;
+		for (app_ctx_node = xmlFirstElementChild(context_child_node);
+				app_ctx_node; app_ctx_node =
+				xmlNextElementSibling(app_ctx_node)) {
+			xmlChar *content;
+			char **target = strcmp(
+				(const char *) app_ctx_node->name,
+				config_element_context_app_provider_name) == 0 ?
+					&context.u.app_ctx.provider_name :
+					&context.u.app_ctx.ctx_name;
+
+			content = xmlNodeGetContent(app_ctx_node);
+			if (!content) {
+				ret = -LTTNG_ERR_NOMEM;
+				goto end;
+			}
+
+			*target = (char *) content;
+		}
+	} else {
+		/* Unrecognized context type */
+		ret = -LTTNG_ERR_LOAD_INVALID_CONFIG;
+		goto end;
 	}
 
 	ret = lttng_add_context(handle, &context, NULL, channel_name);
+	if (context.ctx == LTTNG_EVENT_CONTEXT_APP_CONTEXT) {
+		free(context.u.app_ctx.provider_name);
+		free(context.u.app_ctx.ctx_name);
+	}
 end:
 	return ret;
 }
diff --git a/src/common/config/session.xsd b/src/common/config/session.xsd
index 49b7cd112..550fea0ee 100644
--- a/src/common/config/session.xsd
+++ b/src/common/config/session.xsd
@@ -21,7 +21,7 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 THE SOFTWARE.
 -->
 <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
-elementFormDefault="qualified" version="2.7">
+elementFormDefault="qualified" version="2.8">
 
 <xs:simpleType name="name_type">
 	<xs:restriction base="xs:string">
@@ -136,6 +136,13 @@ elementFormDefault="qualified" version="2.7">
 	</xs:all>
 </xs:complexType>
 
+<xs:complexType name="event_app_context_type">
+	<xs:all>
+	  <xs:element name="provider_name" type="xs:string"/>
+	  <xs:element name="ctx_name" type="xs:string"/>
+	</xs:all>
+</xs:complexType>
+
 <!-- Maps to the lttng_event_context_type enum -->
 <xs:simpleType name="event_context_type_type">
 	<xs:restriction base="xs:string">
@@ -151,6 +158,7 @@ elementFormDefault="qualified" version="2.7">
 		<xs:enumeration value="PTHREAD_ID"/>
 		<xs:enumeration value="HOSTNAME"/>
 		<xs:enumeration value="IP"/>
+		<xs:enumeration value="APP"/>
 	</xs:restriction>
 </xs:simpleType>
 
@@ -158,6 +166,7 @@ elementFormDefault="qualified" version="2.7">
 	<xs:choice>
 		<xs:element name="type" type="event_context_type_type"/>
 		<xs:element name="perf" type="event_perf_context_type"/>
+		<xs:element name="app" type="event_app_context_type"/>
 	</xs:choice>
 </xs:complexType>
 
-- 
2.34.1


From cac5ee8ff005c9e6871cadd0068bf9ea88a34b31 Mon Sep 17 00:00:00 2001
From: =?utf8?q?J=C3=A9r=C3=A9mie=20Galarneau?=
 <jeremie.galarneau@efficios.com>
Date: Tue, 9 Feb 2016 15:16:38 -0500
Subject: [PATCH 15/16] Create agent on channel creation
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---
 src/bin/lttng-sessiond/channel.c | 40 +++++++++++++++++++++-----------
 1 file changed, 27 insertions(+), 13 deletions(-)

diff --git a/src/bin/lttng-sessiond/channel.c b/src/bin/lttng-sessiond/channel.c
index 7c95a0d21..8ceb4e893 100644
--- a/src/bin/lttng-sessiond/channel.c
+++ b/src/bin/lttng-sessiond/channel.c
@@ -31,6 +31,7 @@
 #include "ust-ctl.h"
 #include "utils.h"
 #include "ust-app.h"
+#include "agent.h"
 
 /*
  * Return allocated channel attributes.
@@ -272,6 +273,7 @@ int channel_ust_create(struct ltt_ust_session *usess,
 	int ret = LTTNG_OK;
 	struct ltt_ust_channel *uchan = NULL;
 	struct lttng_channel *defattr = NULL;
+	enum lttng_domain_type domain = LTTNG_DOMAIN_UST;
 
 	assert(usess);
 
@@ -283,6 +285,18 @@ int channel_ust_create(struct ltt_ust_session *usess,
 			goto error;
 		}
 		attr = defattr;
+	} else {
+		/*
+		 * HACK: Set the channel's subdomain (JUL, Log4j, Python, etc.)
+		 * based on the default name.
+		 */
+		if (!strcmp(attr->name, DEFAULT_JUL_CHANNEL_NAME)) {
+			domain = LTTNG_DOMAIN_JUL;
+		} else if (!strcmp(attr->name, DEFAULT_LOG4J_CHANNEL_NAME)) {
+			domain = LTTNG_DOMAIN_LOG4J;
+		} else if (!strcmp(attr->name, DEFAULT_PYTHON_CHANNEL_NAME)) {
+			domain = LTTNG_DOMAIN_PYTHON;
+		}
 	}
 
 	if (usess->snapshot_mode) {
@@ -343,24 +357,12 @@ int channel_ust_create(struct ltt_ust_session *usess,
 	}
 
 	/* Create UST channel */
-	uchan = trace_ust_create_channel(attr, LTTNG_DOMAIN_UST);
+	uchan = trace_ust_create_channel(attr, domain);
 	if (uchan == NULL) {
 		ret = LTTNG_ERR_FATAL;
 		goto error;
 	}
 
-	/*
-	 * HACK: Set the channel's subdomain (JUL, Log4j, Python, etc.)
-	 * based on the default name.
-	 */
-	if (!strcmp(uchan->name, DEFAULT_JUL_CHANNEL_NAME)) {
-		uchan->domain = LTTNG_DOMAIN_JUL;
-	} else if (!strcmp(uchan->name, DEFAULT_LOG4J_CHANNEL_NAME)) {
-		uchan->domain = LTTNG_DOMAIN_LOG4J;
-	} else if (!strcmp(uchan->name, DEFAULT_PYTHON_CHANNEL_NAME)) {
-		uchan->domain = LTTNG_DOMAIN_PYTHON;
-	}
-
 	uchan->enabled = 1;
 	if (trace_ust_is_max_id(usess->used_channel_id)) {
 		ret = LTTNG_ERR_UST_CHAN_FAIL;
@@ -405,6 +407,18 @@ int channel_ust_create(struct ltt_ust_session *usess,
 	rcu_read_unlock();
 
 	DBG2("Channel %s created successfully", uchan->name);
+	if (domain != LTTNG_DOMAIN_UST) {
+		struct agent *agt = trace_ust_find_agent(usess, domain);
+
+		if (!agt) {
+			agt = agent_create(domain);
+			if (!agt) {
+				ret = LTTNG_ERR_NOMEM;
+				goto error_free_chan;
+			}
+			agent_add(agt, usess->agents);
+		}
+	}
 
 	free(defattr);
 	return LTTNG_OK;
-- 
2.34.1


From be35e7ae07cba3fb5ce34a0e2b9db5597632a50f Mon Sep 17 00:00:00 2001
From: =?utf8?q?J=C3=A9r=C3=A9mie=20Galarneau?=
 <jeremie.galarneau@efficios.com>
Date: Tue, 9 Feb 2016 15:16:49 -0500
Subject: [PATCH 16/16] Fix: Don't notify agent of non-app context addition
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---
 src/bin/lttng-sessiond/context.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/bin/lttng-sessiond/context.c b/src/bin/lttng-sessiond/context.c
index 1725c6a10..9a5738799 100644
--- a/src/bin/lttng-sessiond/context.c
+++ b/src/bin/lttng-sessiond/context.c
@@ -113,7 +113,13 @@ static int add_uctx_to_channel(struct ltt_ust_session *usess,
 	case LTTNG_DOMAIN_JUL:
 	case LTTNG_DOMAIN_LOG4J:
 	{
-		struct agent *agt = trace_ust_find_agent(usess, domain);
+		struct agent *agt;
+
+		if (ctx->ctx != LTTNG_EVENT_CONTEXT_APP_CONTEXT) {
+			/* Other contexts are not needed by the agent. */
+			break;
+		}
+		agt = trace_ust_find_agent(usess, domain);
 
 		if (!agt) {
 			agt = agent_create(domain);
-- 
2.34.1