Fix: sessiond: previously created channel cannot be enabled
[lttng-tools.git] / src / bin / lttng-sessiond / cmd.c
index 4447747de752608f08aa02719af5254ab3f2a26c..2c0fa462d38fe63a728679b0dc3072ae6e88502a 100644 (file)
@@ -1,71 +1,73 @@
 /*
- * Copyright (C) 2012 David Goulet <dgoulet@efficios.com>
- * Copyright (C) 2016 Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ * 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
- * published by the Free Software Foundation.
+ * SPDX-License-Identifier: GPL-2.0-only
  *
- * 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.
  */
 
+
 #define _LGPL_SOURCE
-#include <assert.h>
 #include <inttypes.h>
+#include <stdio.h>
+#include <sys/stat.h>
 #include <urcu/list.h>
 #include <urcu/uatomic.h>
-#include <sys/stat.h>
-#include <stdio.h>
 
-#include <common/defaults.h>
+#include <common/buffer-view.h>
 #include <common/common.h>
-#include <common/sessiond-comm/sessiond-comm.h>
-#include <common/relayd/relayd.h>
-#include <common/utils.h>
 #include <common/compat/string.h>
-#include <common/kernel-ctl/kernel-ctl.h>
+#include <common/defaults.h>
 #include <common/dynamic-buffer.h>
-#include <common/buffer-view.h>
+#include <common/kernel-ctl/kernel-ctl.h>
+#include <common/payload-view.h>
+#include <common/payload.h>
+#include <common/relayd/relayd.h>
+#include <common/sessiond-comm/sessiond-comm.h>
+#include <common/string-utils/string-utils.h>
 #include <common/trace-chunk.h>
-#include <lttng/location-internal.h>
-#include <lttng/trigger/trigger-internal.h>
-#include <lttng/condition/condition.h>
+#include <common/utils.h>
+#include <lttng/action/action-internal.h>
 #include <lttng/action/action.h>
-#include <lttng/channel.h>
 #include <lttng/channel-internal.h>
-#include <lttng/rotate-internal.h>
+#include <lttng/channel.h>
+#include <lttng/condition/condition-internal.h>
+#include <lttng/condition/condition.h>
+#include <lttng/condition/event-rule-matches-internal.h>
+#include <lttng/condition/event-rule-matches.h>
+#include <lttng/error-query-internal.h>
+#include <lttng/event-rule/event-rule-internal.h>
+#include <lttng/event-rule/event-rule.h>
 #include <lttng/location-internal.h>
+#include <lttng/lttng-error.h>
+#include <lttng/rotate-internal.h>
+#include <lttng/session-descriptor-internal.h>
 #include <lttng/session-internal.h>
+#include <lttng/tracker.h>
+#include <lttng/trigger/trigger-internal.h>
 #include <lttng/userspace-probe-internal.h>
-#include <lttng/session-descriptor-internal.h>
-#include <common/string-utils/string-utils.h>
 
+#include "agent-thread.h"
+#include "agent.h"
+#include "buffer-registry.h"
 #include "channel.h"
+#include "cmd.h"
 #include "consumer.h"
+#include "event-notifier-error-accounting.h"
 #include "event.h"
 #include "health-sessiond.h"
-#include "kernel.h"
 #include "kernel-consumer.h"
+#include "kernel.h"
 #include "lttng-sessiond.h"
-#include "utils.h"
 #include "lttng-syscall.h"
-#include "agent.h"
-#include "buffer-registry.h"
-#include "notification-thread.h"
 #include "notification-thread-commands.h"
+#include "notification-thread.h"
 #include "rotate.h"
 #include "rotation-thread.h"
+#include "session.h"
 #include "timer.h"
-#include "agent-thread.h"
-
-#include "cmd.h"
+#include "tracker.h"
+#include "utils.h"
 
 /* Sleep for 100ms between each check for the shm path's deletion. */
 #define SESSION_DESTROY_SHM_PATH_CHECK_DELAY_US 100000
 struct cmd_destroy_session_reply_context {
        int reply_sock_fd;
        bool implicit_rotation_on_destroy;
+       /*
+        * Indicates whether or not an error occurred while launching the
+        * destruction of a session.
+        */
+       enum lttng_error_code destruction_status;
 };
 
 static enum lttng_error_code wait_on_path(void *path);
@@ -107,10 +114,10 @@ static uint64_t relayd_net_seq_idx;
 
 static int validate_ust_event_name(const char *);
 static int cmd_enable_event_internal(struct ltt_session *session,
-               struct lttng_domain *domain,
+               const struct lttng_domain *domain,
                char *channel_name, struct lttng_event *event,
                char *filter_expression,
-               struct lttng_filter_bytecode *filter,
+               struct lttng_bytecode *filter,
                struct lttng_event_exclusion *exclusion,
                int wpipe);
 
@@ -125,8 +132,8 @@ static int build_network_session_path(char *dst, size_t size,
        struct lttng_uri *kuri = NULL, *uuri = NULL, *uri = NULL;
        char tmp_uurl[PATH_MAX], tmp_urls[PATH_MAX];
 
-       assert(session);
-       assert(dst);
+       LTTNG_ASSERT(session);
+       LTTNG_ASSERT(dst);
 
        memset(tmp_urls, 0, sizeof(tmp_urls));
        memset(tmp_uurl, 0, sizeof(tmp_uurl));
@@ -244,8 +251,8 @@ static int get_ust_runtime_stats(struct ltt_session *session,
        }
 
        usess = session->ust_session;
-       assert(discarded_events);
-       assert(lost_packets);
+       LTTNG_ASSERT(discarded_events);
+       LTTNG_ASSERT(lost_packets);
 
        if (!usess || !session->has_been_started) {
                *discarded_events = 0;
@@ -274,7 +281,7 @@ static int get_ust_runtime_stats(struct ltt_session *session,
                *lost_packets += uchan->per_pid_closed_app_lost;
        } else {
                ERR("Unsupported buffer type");
-               assert(0);
+               abort();
                ret = -1;
                goto end;
        }
@@ -354,7 +361,7 @@ static ssize_t list_lttng_channels(enum lttng_domain_type domain,
                         * Map enum lttng_ust_output to enum lttng_event_output.
                         */
                        switch (uchan->attr.output) {
-                       case LTTNG_UST_MMAP:
+                       case LTTNG_UST_ABI_MMAP:
                                channels[i].attr.output = LTTNG_EVENT_MMAP;
                                break;
                        default:
@@ -362,7 +369,7 @@ static ssize_t list_lttng_channels(enum lttng_domain_type domain,
                                 * LTTNG_UST_MMAP is the only supported UST
                                 * output mode.
                                 */
-                               assert(0);
+                               abort();
                                break;
                        }
 
@@ -395,95 +402,69 @@ end:
        }
 }
 
-static int increment_extended_len(const char *filter_expression,
-               struct lttng_event_exclusion *exclusion,
-               const struct lttng_userspace_probe_location *probe_location,
-               size_t *extended_len)
-{
-       int ret = 0;
-
-       *extended_len += sizeof(struct lttcomm_event_extended_header);
-
-       if (filter_expression) {
-               *extended_len += strlen(filter_expression) + 1;
-       }
-
-       if (exclusion) {
-               *extended_len += exclusion->count * LTTNG_SYMBOL_NAME_LEN;
-       }
-
-       if (probe_location) {
-               ret = lttng_userspace_probe_location_serialize(probe_location,
-                               NULL, NULL);
-               if (ret < 0) {
-                       goto end;
-               }
-               *extended_len += ret;
-       }
-       ret = 0;
-end:
-       return ret;
-}
-
 static int append_extended_info(const char *filter_expression,
                struct lttng_event_exclusion *exclusion,
                struct lttng_userspace_probe_location *probe_location,
-               void **extended_at)
+               struct lttng_payload *payload)
 {
        int ret = 0;
        size_t filter_len = 0;
        size_t nb_exclusions = 0;
        size_t userspace_probe_location_len = 0;
-       struct lttng_dynamic_buffer location_buffer;
-       struct lttcomm_event_extended_header extended_header;
+       struct lttcomm_event_extended_header extended_header = {};
+       struct lttcomm_event_extended_header *p_extended_header;
+       const size_t original_payload_size = payload->buffer.size;
+
+       ret = lttng_dynamic_buffer_append(&payload->buffer, &extended_header,
+                       sizeof(extended_header));
+       if (ret) {
+               goto end;
+       }
 
        if (filter_expression) {
                filter_len = strlen(filter_expression) + 1;
+               ret = lttng_dynamic_buffer_append(&payload->buffer,
+                               filter_expression, filter_len);
+               if (ret) {
+                       goto end;
+               }
        }
 
        if (exclusion) {
+               const size_t len = exclusion->count * LTTNG_SYMBOL_NAME_LEN;
+
                nb_exclusions = exclusion->count;
+
+               ret = lttng_dynamic_buffer_append(
+                               &payload->buffer, &exclusion->names, len);
+               if (ret) {
+                       goto end;
+               }
        }
 
        if (probe_location) {
-               lttng_dynamic_buffer_init(&location_buffer);
+               const size_t size_before_probe = payload->buffer.size;
+
                ret = lttng_userspace_probe_location_serialize(probe_location,
-                               &location_buffer, NULL);
+                               payload);
                if (ret < 0) {
                        ret = -1;
                        goto end;
                }
-               userspace_probe_location_len = location_buffer.size;
-       }
-
-       /* Set header fields */
-       extended_header.filter_len = filter_len;
-       extended_header.nb_exclusions = nb_exclusions;
-       extended_header.userspace_probe_location_len = userspace_probe_location_len;
 
-       /* Copy header */
-       memcpy(*extended_at, &extended_header, sizeof(extended_header));
-       *extended_at += sizeof(extended_header);
-
-       /* Copy filter string */
-       if (filter_expression) {
-               memcpy(*extended_at, filter_expression, filter_len);
-               *extended_at += filter_len;
+               userspace_probe_location_len =
+                               payload->buffer.size - size_before_probe;
        }
 
-       /* Copy exclusion names */
-       if (exclusion) {
-               size_t len = nb_exclusions * LTTNG_SYMBOL_NAME_LEN;
+       /* Set header fields */
+       p_extended_header = (struct lttcomm_event_extended_header *)
+                       (payload->buffer.data + original_payload_size);
 
-               memcpy(*extended_at, &exclusion->names, len);
-               *extended_at += len;
-       }
+       p_extended_header->filter_len = filter_len;
+       p_extended_header->nb_exclusions = nb_exclusions;
+       p_extended_header->userspace_probe_location_len =
+                       userspace_probe_location_len;
 
-       if (probe_location) {
-               memcpy(*extended_at, location_buffer.data, location_buffer.size);
-               *extended_at += location_buffer.size;
-               lttng_dynamic_buffer_reset(&location_buffer);
-       }
        ret = 0;
 end:
        return ret;
@@ -495,89 +476,61 @@ end:
  * Return number of events in list on success or else a negative value.
  */
 static int list_lttng_agent_events(struct agent *agt,
-               struct lttng_event **events, size_t *total_size)
+               struct lttng_payload *payload)
 {
-       int i = 0, ret = 0;
-       unsigned int nb_event = 0;
-       struct agent_event *event;
-       struct lttng_event *tmp_events = NULL;
+       int nb_events = 0, ret = 0;
+       const struct agent_event *agent_event;
        struct lttng_ht_iter iter;
-       size_t extended_len = 0;
-       void *extended_at;
 
-       assert(agt);
-       assert(events);
+       LTTNG_ASSERT(agt);
 
        DBG3("Listing agent events");
 
        rcu_read_lock();
-       nb_event = lttng_ht_get_count(agt->events);
-       rcu_read_unlock();
-       if (nb_event == 0) {
-               ret = nb_event;
-               *total_size = 0;
-               goto error;
-       }
-
-       /* Compute required extended infos size */
-       extended_len = nb_event * sizeof(struct lttcomm_event_extended_header);
+       cds_lfht_for_each_entry (
+                       agt->events->ht, &iter.iter, agent_event, node.node) {
+               struct lttng_event event = {
+                       .enabled = AGENT_EVENT_IS_ENABLED(agent_event),
+                       .loglevel = agent_event->loglevel_value,
+                       .loglevel_type = agent_event->loglevel_type,
+               };
+
+               ret = lttng_strncpy(event.name, agent_event->name, sizeof(event.name));
+               if (ret) {
+                       /* Internal error, invalid name. */
+                       ERR("Invalid event name while listing agent events: '%s' exceeds the maximal allowed length of %zu bytes",
+                                       agent_event->name, sizeof(event.name));
+                       ret = -LTTNG_ERR_UNK;
+                       goto end;
+               }
 
-       /*
-        * This is only valid because the commands which add events are
-        * processed in the same thread as the listing.
-        */
-       rcu_read_lock();
-       cds_lfht_for_each_entry(agt->events->ht, &iter.iter, event, node.node) {
-               ret = increment_extended_len(event->filter_expression, NULL, NULL,
-                               &extended_len);
+               ret = lttng_dynamic_buffer_append(
+                               &payload->buffer, &event, sizeof(event));
                if (ret) {
-                       DBG("Error computing the length of extended info message");
-                       ret = -LTTNG_ERR_FATAL;
-                       goto error;
+                       ERR("Failed to append event to payload");
+                       ret = -LTTNG_ERR_NOMEM;
+                       goto end;
                }
-       }
-       rcu_read_unlock();
 
-       *total_size = nb_event * sizeof(*tmp_events) + extended_len;
-       tmp_events = zmalloc(*total_size);
-       if (!tmp_events) {
-               PERROR("zmalloc agent events session");
-               ret = -LTTNG_ERR_FATAL;
-               goto error;
+               nb_events++;
        }
 
-       extended_at = ((uint8_t *) tmp_events) +
-               nb_event * sizeof(struct lttng_event);
-
-       rcu_read_lock();
-       cds_lfht_for_each_entry(agt->events->ht, &iter.iter, event, node.node) {
-               strncpy(tmp_events[i].name, event->name, sizeof(tmp_events[i].name));
-               tmp_events[i].name[sizeof(tmp_events[i].name) - 1] = '\0';
-               tmp_events[i].enabled = event->enabled;
-               tmp_events[i].loglevel = event->loglevel_value;
-               tmp_events[i].loglevel_type = event->loglevel_type;
-               i++;
-
-               /* Append extended info */
-               ret = append_extended_info(event->filter_expression, NULL, NULL,
-                               &extended_at);
+       cds_lfht_for_each_entry (
+               agt->events->ht, &iter.iter, agent_event, node.node) {
+               /* Append extended info. */
+               ret = append_extended_info(agent_event->filter_expression, NULL,
+                               NULL, payload);
                if (ret) {
-                       DBG("Error appending extended info message");
-                       ret = -LTTNG_ERR_FATAL;
-                       goto error;
+                       ERR("Failed to append extended event info to payload");
+                       ret = -LTTNG_ERR_NOMEM;
+                       goto end;
                }
        }
 
-       *events = tmp_events;
-       ret = nb_event;
-       assert(nb_event == i);
-
+       ret = nb_events;
 end:
        rcu_read_unlock();
        return ret;
-error:
-       free(tmp_events);
-       goto end;
 }
 
 /*
@@ -585,23 +538,20 @@ error:
  */
 static int list_lttng_ust_global_events(char *channel_name,
                struct ltt_ust_domain_global *ust_global,
-               struct lttng_event **events, size_t *total_size)
+               struct lttng_payload *payload)
 {
-       int i = 0, ret = 0;
-       unsigned int nb_event = 0;
+       int ret = 0;
+       unsigned int nb_events = 0;
        struct lttng_ht_iter iter;
-       struct lttng_ht_node_str *node;
-       struct ltt_ust_channel *uchan;
-       struct ltt_ust_event *uevent;
-       struct lttng_event *tmp;
-       size_t extended_len = 0;
-       void *extended_at;
+       const struct lttng_ht_node_str *node;
+       const struct ltt_ust_channel *uchan;
+       const struct ltt_ust_event *uevent;
 
        DBG("Listing UST global events for channel %s", channel_name);
 
        rcu_read_lock();
 
-       lttng_ht_lookup(ust_global->channels, (void *)channel_name, &iter);
+       lttng_ht_lookup(ust_global->channels, (void *) channel_name, &iter);
        node = lttng_ht_iter_get_node_str(&iter);
        if (node == NULL) {
                ret = LTTNG_ERR_UST_CHAN_NOT_FOUND;
@@ -610,99 +560,81 @@ static int list_lttng_ust_global_events(char *channel_name,
 
        uchan = caa_container_of(&node->node, struct ltt_ust_channel, node.node);
 
-       nb_event = lttng_ht_get_count(uchan->events);
-       if (nb_event == 0) {
-               ret = nb_event;
-               *total_size = 0;
-               goto end;
-       }
-
-       DBG3("Listing UST global %d events", nb_event);
+       DBG3("Listing UST global events");
 
-       /* Compute required extended infos size */
        cds_lfht_for_each_entry(uchan->events->ht, &iter.iter, uevent, node.node) {
+               struct lttng_event event = {};
+
                if (uevent->internal) {
-                       nb_event--;
                        continue;
                }
 
-               ret = increment_extended_len(uevent->filter_expression,
-                       uevent->exclusion, NULL, &extended_len);
+               ret = lttng_strncpy(event.name, uevent->attr.name, sizeof(event.name));
                if (ret) {
-                       DBG("Error computing the length of extended info message");
-                       ret = -LTTNG_ERR_FATAL;
+                       /* Internal error, invalid name. */
+                       ERR("Invalid event name while listing user space tracer events: '%s' exceeds the maximal allowed length of %zu bytes",
+                                       uevent->attr.name, sizeof(event.name));
+                       ret = -LTTNG_ERR_UNK;
                        goto end;
                }
-       }
-       if (nb_event == 0) {
-               /* All events are internal, skip. */
-               ret = 0;
-               *total_size = 0;
-               goto end;
-       }
-
-       *total_size = nb_event * sizeof(struct lttng_event) + extended_len;
-       tmp = zmalloc(*total_size);
-       if (tmp == NULL) {
-               ret = -LTTNG_ERR_FATAL;
-               goto end;
-       }
-
-       extended_at = ((uint8_t *) tmp) + nb_event * sizeof(struct lttng_event);
 
-       cds_lfht_for_each_entry(uchan->events->ht, &iter.iter, uevent, node.node) {
-               if (uevent->internal) {
-                       /* This event should remain hidden from clients */
-                       continue;
-               }
-               strncpy(tmp[i].name, uevent->attr.name, LTTNG_SYMBOL_NAME_LEN);
-               tmp[i].name[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
-               tmp[i].enabled = uevent->enabled;
+               event.enabled = uevent->enabled;
 
                switch (uevent->attr.instrumentation) {
-               case LTTNG_UST_TRACEPOINT:
-                       tmp[i].type = LTTNG_EVENT_TRACEPOINT;
+               case LTTNG_UST_ABI_TRACEPOINT:
+                       event.type = LTTNG_EVENT_TRACEPOINT;
                        break;
-               case LTTNG_UST_PROBE:
-                       tmp[i].type = LTTNG_EVENT_PROBE;
+               case LTTNG_UST_ABI_PROBE:
+                       event.type = LTTNG_EVENT_PROBE;
                        break;
-               case LTTNG_UST_FUNCTION:
-                       tmp[i].type = LTTNG_EVENT_FUNCTION;
+               case LTTNG_UST_ABI_FUNCTION:
+                       event.type = LTTNG_EVENT_FUNCTION;
                        break;
                }
 
-               tmp[i].loglevel = uevent->attr.loglevel;
+               event.loglevel = uevent->attr.loglevel;
                switch (uevent->attr.loglevel_type) {
-               case LTTNG_UST_LOGLEVEL_ALL:
-                       tmp[i].loglevel_type = LTTNG_EVENT_LOGLEVEL_ALL;
+               case LTTNG_UST_ABI_LOGLEVEL_ALL:
+                       event.loglevel_type = LTTNG_EVENT_LOGLEVEL_ALL;
                        break;
-               case LTTNG_UST_LOGLEVEL_RANGE:
-                       tmp[i].loglevel_type = LTTNG_EVENT_LOGLEVEL_RANGE;
+               case LTTNG_UST_ABI_LOGLEVEL_RANGE:
+                       event.loglevel_type = LTTNG_EVENT_LOGLEVEL_RANGE;
                        break;
-               case LTTNG_UST_LOGLEVEL_SINGLE:
-                       tmp[i].loglevel_type = LTTNG_EVENT_LOGLEVEL_SINGLE;
+               case LTTNG_UST_ABI_LOGLEVEL_SINGLE:
+                       event.loglevel_type = LTTNG_EVENT_LOGLEVEL_SINGLE;
                        break;
                }
+
                if (uevent->filter) {
-                       tmp[i].filter = 1;
+                       event.filter = 1;
                }
+
                if (uevent->exclusion) {
-                       tmp[i].exclusion = 1;
+                       event.exclusion = 1;
                }
-               i++;
 
-               /* Append extended info */
+               ret = lttng_dynamic_buffer_append(&payload->buffer, &event, sizeof(event));
+               if (ret) {
+                       ERR("Failed to append event to payload");
+                       ret = -LTTNG_ERR_NOMEM;
+                       goto end;
+               }
+
+               nb_events++;
+       }
+
+       cds_lfht_for_each_entry(uchan->events->ht, &iter.iter, uevent, node.node) {
+               /* Append extended info. */
                ret = append_extended_info(uevent->filter_expression,
-                       uevent->exclusion, NULL, &extended_at);
+                               uevent->exclusion, NULL, payload);
                if (ret) {
-                       DBG("Error appending extended info message");
+                       ERR("Failed to append extended event info to payload");
                        ret = -LTTNG_ERR_FATAL;
                        goto end;
                }
        }
 
-       ret = nb_event;
-       *events = tmp;
+       ret = nb_events;
 end:
        rcu_read_unlock();
        return ret;
@@ -713,14 +645,12 @@ end:
  */
 static int list_lttng_kernel_events(char *channel_name,
                struct ltt_kernel_session *kernel_session,
-               struct lttng_event **events, size_t *total_size)
+               struct lttng_payload *payload)
 {
-       int i = 0, ret;
+       int ret;
        unsigned int nb_event;
-       struct ltt_kernel_event *event;
-       struct ltt_kernel_channel *kchan;
-       size_t extended_len = 0;
-       void *extended_at;
+       const struct ltt_kernel_event *kevent;
+       const struct ltt_kernel_channel *kchan;
 
        kchan = trace_kernel_get_channel_by_name(channel_name, kernel_session);
        if (kchan == NULL) {
@@ -732,81 +662,71 @@ static int list_lttng_kernel_events(char *channel_name,
 
        DBG("Listing events for channel %s", kchan->channel->name);
 
-       if (nb_event == 0) {
-               *total_size = 0;
-               *events = NULL;
-               goto end;
-       }
+       /* Kernel channels */
+       cds_list_for_each_entry(kevent, &kchan->events_list.head , list) {
+               struct lttng_event event = {};
 
-       /* Compute required extended infos size */
-       cds_list_for_each_entry(event, &kchan->events_list.head, list) {
-               ret = increment_extended_len(event->filter_expression, NULL,
-                       event->userspace_probe_location,
-                       &extended_len);
+               ret = lttng_strncpy(event.name, kevent->event->name, sizeof(event.name));
                if (ret) {
-                       DBG("Error computing the length of extended info message");
-                       ret = -LTTNG_ERR_FATAL;
-                       goto error;
+                       /* Internal error, invalid name. */
+                       ERR("Invalid event name while listing kernel events: '%s' exceeds the maximal allowed length of %zu bytes",
+                                       kevent->event->name,
+                                       sizeof(event.name));
+                       ret = -LTTNG_ERR_UNK;
+                       goto end;
                }
-       }
-
-       *total_size = nb_event * sizeof(struct lttng_event) + extended_len;
-       *events = zmalloc(*total_size);
-       if (*events == NULL) {
-               ret = -LTTNG_ERR_FATAL;
-               goto error;
-       }
 
-       extended_at = ((void *) *events) +
-               nb_event * sizeof(struct lttng_event);
+               event.enabled = kevent->enabled;
+               event.filter = (unsigned char) !!kevent->filter_expression;
 
-       /* Kernel channels */
-       cds_list_for_each_entry(event, &kchan->events_list.head , list) {
-               strncpy((*events)[i].name, event->event->name, LTTNG_SYMBOL_NAME_LEN);
-               (*events)[i].name[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
-               (*events)[i].enabled = event->enabled;
-               (*events)[i].filter =
-                               (unsigned char) !!event->filter_expression;
-
-               switch (event->event->instrumentation) {
-               case LTTNG_KERNEL_TRACEPOINT:
-                       (*events)[i].type = LTTNG_EVENT_TRACEPOINT;
+               switch (kevent->event->instrumentation) {
+               case LTTNG_KERNEL_ABI_TRACEPOINT:
+                       event.type = LTTNG_EVENT_TRACEPOINT;
                        break;
-               case LTTNG_KERNEL_KRETPROBE:
-                       (*events)[i].type = LTTNG_EVENT_FUNCTION;
-                       memcpy(&(*events)[i].attr.probe, &event->event->u.kprobe,
-                                       sizeof(struct lttng_kernel_kprobe));
+               case LTTNG_KERNEL_ABI_KRETPROBE:
+                       event.type = LTTNG_EVENT_FUNCTION;
+                       memcpy(&event.attr.probe, &kevent->event->u.kprobe,
+                                       sizeof(struct lttng_kernel_abi_kprobe));
                        break;
-               case LTTNG_KERNEL_KPROBE:
-                       (*events)[i].type = LTTNG_EVENT_PROBE;
-                       memcpy(&(*events)[i].attr.probe, &event->event->u.kprobe,
-                                       sizeof(struct lttng_kernel_kprobe));
+               case LTTNG_KERNEL_ABI_KPROBE:
+                       event.type = LTTNG_EVENT_PROBE;
+                       memcpy(&event.attr.probe, &kevent->event->u.kprobe,
+                                       sizeof(struct lttng_kernel_abi_kprobe));
                        break;
-               case LTTNG_KERNEL_UPROBE:
-                       (*events)[i].type = LTTNG_EVENT_USERSPACE_PROBE;
+               case LTTNG_KERNEL_ABI_UPROBE:
+                       event.type = LTTNG_EVENT_USERSPACE_PROBE;
                        break;
-               case LTTNG_KERNEL_FUNCTION:
-                       (*events)[i].type = LTTNG_EVENT_FUNCTION;
-                       memcpy(&((*events)[i].attr.ftrace), &event->event->u.ftrace,
-                                       sizeof(struct lttng_kernel_function));
+               case LTTNG_KERNEL_ABI_FUNCTION:
+                       event.type = LTTNG_EVENT_FUNCTION;
+                       memcpy(&event.attr.ftrace, &kevent->event->u.ftrace,
+                                       sizeof(struct lttng_kernel_abi_function));
                        break;
-               case LTTNG_KERNEL_NOOP:
-                       (*events)[i].type = LTTNG_EVENT_NOOP;
+               case LTTNG_KERNEL_ABI_NOOP:
+                       event.type = LTTNG_EVENT_NOOP;
                        break;
-               case LTTNG_KERNEL_SYSCALL:
-                       (*events)[i].type = LTTNG_EVENT_SYSCALL;
+               case LTTNG_KERNEL_ABI_SYSCALL:
+                       event.type = LTTNG_EVENT_SYSCALL;
                        break;
-               case LTTNG_KERNEL_ALL:
+               case LTTNG_KERNEL_ABI_ALL:
                        /* fall-through. */
                default:
-                       assert(0);
+                       abort();
                        break;
                }
-               i++;
 
-               /* Append extended info */
-               ret = append_extended_info(event->filter_expression, NULL,
-                       event->userspace_probe_location, &extended_at);
+               ret = lttng_dynamic_buffer_append(
+                               &payload->buffer, &event, sizeof(event));
+               if (ret) {
+                       ERR("Failed to append event to payload");
+                       ret = -LTTNG_ERR_NOMEM;
+                       goto end;
+               }
+       }
+
+       cds_list_for_each_entry(kevent, &kchan->events_list.head , list) {
+               /* Append extended info. */
+               ret = append_extended_info(kevent->filter_expression, NULL,
+                               kevent->userspace_probe_location, payload);
                if (ret) {
                        DBG("Error appending extended info message");
                        ret = -LTTNG_ERR_FATAL;
@@ -816,10 +736,8 @@ static int list_lttng_kernel_events(char *channel_name,
 
 end:
        return nb_event;
-
 error:
-       /* Negate the error code to differentiate the size from an error */
-       return -ret;
+       return ret;
 }
 
 /*
@@ -834,7 +752,7 @@ static enum lttng_error_code add_uri_to_consumer(
        int ret;
        enum lttng_error_code ret_code = LTTNG_OK;
 
-       assert(uri);
+       LTTNG_ASSERT(uri);
 
        if (consumer == NULL) {
                DBG("No consumer detected. Don't add URI. Stopping.");
@@ -912,6 +830,10 @@ static enum lttng_error_code add_uri_to_consumer(
                ret = lttng_strncpy(consumer->dst.session_root_path,
                                uri->dst.path,
                                sizeof(consumer->dst.session_root_path));
+               if (ret) {
+                       ret_code = LTTNG_ERR_FATAL;
+                       goto error;
+               }
                consumer->type = CONSUMER_DST_LOCAL;
                break;
        }
@@ -930,7 +852,7 @@ static int init_kernel_tracing(struct ltt_kernel_session *session)
        struct lttng_ht_iter iter;
        struct consumer_socket *socket;
 
-       assert(session);
+       LTTNG_ASSERT(session);
 
        rcu_read_lock();
 
@@ -989,6 +911,8 @@ static enum lttng_error_code create_connect_relayd(struct lttng_uri *uri,
 
        /* Create socket for control stream. */
        if (uri->stype == LTTNG_STREAM_CONTROL) {
+               uint64_t result_flags;
+
                DBG3("Creating relayd stream socket from URI");
 
                /* Check relayd version */
@@ -1003,6 +927,16 @@ static enum lttng_error_code create_connect_relayd(struct lttng_uri *uri,
                }
                consumer->relay_major_version = rsock->major;
                consumer->relay_minor_version = rsock->minor;
+               ret = relayd_get_configuration(rsock, 0,
+                               &result_flags);
+               if (ret < 0) {
+                       ERR("Unable to get relayd configuration");
+                       status = LTTNG_ERR_RELAYD_CONNECT_FAIL;
+                       goto close_sock;
+               }
+               if (result_flags & LTTCOMM_RELAYD_CONFIGURATION_FLAG_CLEAR_ALLOWED) {
+                       consumer->relay_allows_clear = true;
+               }
        } else if (uri->stype == LTTNG_STREAM_DATA) {
                DBG3("Creating relayd data socket from URI");
        } else {
@@ -1039,7 +973,7 @@ static enum lttng_error_code send_consumer_relayd_socket(
                struct consumer_socket *consumer_sock,
                const char *session_name, const char *hostname,
                const char *base_path, int session_live_timer,
-               const uint64_t *current_chunk_id,
+               const uint64_t *current_chunk_id,
                time_t session_creation_time,
                bool session_name_contains_creation_time)
 {
@@ -1052,7 +986,7 @@ static enum lttng_error_code send_consumer_relayd_socket(
        if (status != LTTNG_OK) {
                goto relayd_comm_error;
        }
-       assert(rsock);
+       LTTNG_ASSERT(rsock);
 
        /* Set the network sequence index if not set. */
        if (consumer->net_seq_index == (uint64_t) -1ULL) {
@@ -1124,8 +1058,8 @@ static enum lttng_error_code send_consumer_relayd_sockets(
 {
        enum lttng_error_code status = LTTNG_OK;
 
-       assert(consumer);
-       assert(sock);
+       LTTNG_ASSERT(consumer);
+       LTTNG_ASSERT(sock);
 
        /* Sending control relayd socket. */
        if (!sock->control_sock_sent) {
@@ -1167,15 +1101,16 @@ int cmd_setup_relayd(struct ltt_session *session)
        struct ltt_kernel_session *ksess;
        struct consumer_socket *socket;
        struct lttng_ht_iter iter;
-        LTTNG_OPTIONAL(uint64_t) current_chunk_id = {};
+       LTTNG_OPTIONAL(uint64_t) current_chunk_id = {};
 
-        assert(session);
+       LTTNG_ASSERT(session);
 
        usess = session->ust_session;
        ksess = session->kernel_session;
 
        DBG("Setting relayd for session %s", session->name);
 
+       rcu_read_lock();
        if (session->current_trace_chunk) {
                enum lttng_trace_chunk_status status = lttng_trace_chunk_get_id(
                                session->current_trace_chunk, &current_chunk_id.value);
@@ -1189,8 +1124,6 @@ int cmd_setup_relayd(struct ltt_session *session)
                }
        }
 
-       rcu_read_lock();
-
        if (usess && usess->consumer && usess->consumer->type == CONSUMER_DST_NET
                        && usess->consumer->enabled) {
                /* For each consumer socket, send relayd sockets */
@@ -1216,6 +1149,8 @@ int cmd_setup_relayd(struct ltt_session *session)
                        usess->consumer->relay_major_version;
                session->consumer->relay_minor_version =
                        usess->consumer->relay_minor_version;
+               session->consumer->relay_allows_clear =
+                       usess->consumer->relay_allows_clear;
        }
 
        if (ksess && ksess->consumer && ksess->consumer->type == CONSUMER_DST_NET
@@ -1242,6 +1177,8 @@ int cmd_setup_relayd(struct ltt_session *session)
                        ksess->consumer->relay_major_version;
                session->consumer->relay_minor_version =
                        ksess->consumer->relay_minor_version;
+               session->consumer->relay_allows_clear =
+                       ksess->consumer->relay_allows_clear;
        }
 
 error:
@@ -1252,7 +1189,7 @@ error:
 /*
  * Start a kernel session by opening all necessary streams.
  */
-static int start_kernel_session(struct ltt_kernel_session *ksess, int wpipe)
+int start_kernel_session(struct ltt_kernel_session *ksess)
 {
        int ret;
        struct ltt_kernel_channel *kchan;
@@ -1304,7 +1241,7 @@ static int start_kernel_session(struct ltt_kernel_session *ksess, int wpipe)
        }
 
        /* Quiescent wait after starting trace */
-       kernel_wait_quiescent(wpipe);
+       kernel_wait_quiescent();
 
        ksess->active = 1;
 
@@ -1314,6 +1251,53 @@ error:
        return ret;
 }
 
+int stop_kernel_session(struct ltt_kernel_session *ksess)
+{
+       struct ltt_kernel_channel *kchan;
+       bool error_occurred = false;
+       int ret;
+
+       if (!ksess || !ksess->active) {
+               return LTTNG_OK;
+       }
+       DBG("Stopping kernel tracing");
+
+       ret = kernel_stop_session(ksess);
+       if (ret < 0) {
+               ret = LTTNG_ERR_KERN_STOP_FAIL;
+               goto error;
+       }
+
+       kernel_wait_quiescent();
+
+       /* Flush metadata after stopping (if exists) */
+       if (ksess->metadata_stream_fd >= 0) {
+               ret = kernel_metadata_flush_buffer(ksess->metadata_stream_fd);
+               if (ret < 0) {
+                       ERR("Kernel metadata flush failed");
+                       error_occurred = true;
+               }
+       }
+
+       /* Flush all buffers after stopping */
+       cds_list_for_each_entry(kchan, &ksess->channel_list.head, list) {
+               ret = kernel_flush_buffer(kchan);
+               if (ret < 0) {
+                       ERR("Kernel flush buffer error");
+                       error_occurred = true;
+               }
+       }
+
+       ksess->active = 0;
+       if (error_occurred) {
+               ret = LTTNG_ERR_UNK;
+       } else {
+               ret = LTTNG_OK;
+       }
+error:
+       return ret;
+}
+
 /*
  * Command LTTNG_DISABLE_CHANNEL processed by the client thread.
  */
@@ -1336,7 +1320,7 @@ int cmd_disable_channel(struct ltt_session *session,
                        goto error;
                }
 
-               kernel_wait_quiescent(kernel_tracer_fd);
+               kernel_wait_quiescent();
                break;
        }
        case LTTNG_DOMAIN_UST:
@@ -1371,167 +1355,58 @@ error:
 }
 
 /*
- * Command LTTNG_TRACK_PID processed by the client thread.
+ * Command LTTNG_ENABLE_CHANNEL processed by the client thread.
  *
- * Called with session lock held.
+ * The wpipe arguments is used as a notifier for the kernel thread.
  */
-int cmd_track_pid(struct ltt_session *session, enum lttng_domain_type domain,
-               int pid)
+int cmd_enable_channel(struct ltt_session *session,
+               const struct lttng_domain *domain, const struct lttng_channel *_attr, int wpipe)
 {
        int ret;
+       struct ltt_ust_session *usess = session->ust_session;
+       struct lttng_ht *chan_ht;
+       size_t len;
+       struct lttng_channel attr;
+
+       LTTNG_ASSERT(session);
+       LTTNG_ASSERT(_attr);
+       LTTNG_ASSERT(domain);
+
+       attr = *_attr;
+       len = lttng_strnlen(attr.name, sizeof(attr.name));
+
+       /* Validate channel name */
+       if (attr.name[0] == '.' ||
+               memchr(attr.name, '/', len) != NULL) {
+               ret = LTTNG_ERR_INVALID_CHANNEL_NAME;
+               goto end;
+       }
+
+       DBG("Enabling channel %s for session %s", attr.name, session->name);
 
        rcu_read_lock();
 
-       switch (domain) {
+       /*
+        * If the session is a live session, remove the switch timer, the
+        * live timer does the same thing but sends also synchronisation
+        * beacons for inactive streams.
+        */
+       if (session->live_timer > 0) {
+               attr.attr.live_timer_interval = session->live_timer;
+               attr.attr.switch_timer_interval = 0;
+       }
+
+       /* Check for feature support */
+       switch (domain->type) {
        case LTTNG_DOMAIN_KERNEL:
        {
-               struct ltt_kernel_session *ksess;
-
-               ksess = session->kernel_session;
-
-               ret = kernel_track_pid(ksess, pid);
-               if (ret != LTTNG_OK) {
-                       goto error;
-               }
-
-               kernel_wait_quiescent(kernel_tracer_fd);
-               break;
-       }
-       case LTTNG_DOMAIN_UST:
-       {
-               struct ltt_ust_session *usess;
-
-               usess = session->ust_session;
-
-               ret = trace_ust_track_pid(usess, pid);
-               if (ret != LTTNG_OK) {
-                       goto error;
-               }
-               break;
-       }
-       default:
-               ret = LTTNG_ERR_UNKNOWN_DOMAIN;
-               goto error;
-       }
-
-       ret = LTTNG_OK;
-
-error:
-       rcu_read_unlock();
-       return ret;
-}
-
-/*
- * Command LTTNG_UNTRACK_PID processed by the client thread.
- *
- * Called with session lock held.
- */
-int cmd_untrack_pid(struct ltt_session *session, enum lttng_domain_type domain,
-               int pid)
-{
-       int ret;
-
-       rcu_read_lock();
-
-       switch (domain) {
-       case LTTNG_DOMAIN_KERNEL:
-       {
-               struct ltt_kernel_session *ksess;
-
-               ksess = session->kernel_session;
-
-               ret = kernel_untrack_pid(ksess, pid);
-               if (ret != LTTNG_OK) {
-                       goto error;
-               }
-
-               kernel_wait_quiescent(kernel_tracer_fd);
-               break;
-       }
-       case LTTNG_DOMAIN_UST:
-       {
-               struct ltt_ust_session *usess;
-
-               usess = session->ust_session;
-
-               ret = trace_ust_untrack_pid(usess, pid);
-               if (ret != LTTNG_OK) {
-                       goto error;
-               }
-               break;
-       }
-       default:
-               ret = LTTNG_ERR_UNKNOWN_DOMAIN;
-               goto error;
-       }
-
-       ret = LTTNG_OK;
-
-error:
-       rcu_read_unlock();
-       return ret;
-}
-
-/*
- * Command LTTNG_ENABLE_CHANNEL processed by the client thread.
- *
- * The wpipe arguments is used as a notifier for the kernel thread.
- */
-int cmd_enable_channel(struct ltt_session *session,
-               struct lttng_domain *domain, struct lttng_channel *attr, int wpipe)
-{
-       int ret;
-       struct ltt_ust_session *usess = session->ust_session;
-       struct lttng_ht *chan_ht;
-       size_t len;
-
-       assert(session);
-       assert(attr);
-       assert(domain);
-
-       len = lttng_strnlen(attr->name, sizeof(attr->name));
-
-       /* Validate channel name */
-       if (attr->name[0] == '.' ||
-               memchr(attr->name, '/', len) != NULL) {
-               ret = LTTNG_ERR_INVALID_CHANNEL_NAME;
-               goto end;
-       }
-
-       DBG("Enabling channel %s for session %s", attr->name, session->name);
-
-       rcu_read_lock();
-
-       /*
-        * Don't try to enable a channel if the session has been started at
-        * some point in time before. The tracer does not allow it.
-        */
-       if (session->has_been_started) {
-               ret = LTTNG_ERR_TRACE_ALREADY_STARTED;
-               goto error;
-       }
-
-       /*
-        * If the session is a live session, remove the switch timer, the
-        * live timer does the same thing but sends also synchronisation
-        * beacons for inactive streams.
-        */
-       if (session->live_timer > 0) {
-               attr->attr.live_timer_interval = session->live_timer;
-               attr->attr.switch_timer_interval = 0;
-       }
-
-       /* Check for feature support */
-       switch (domain->type) {
-       case LTTNG_DOMAIN_KERNEL:
-       {
-               if (kernel_supports_ring_buffer_snapshot_sample_positions(kernel_tracer_fd) != 1) {
-                       /* Sampling position of buffer is not supported */
-                       WARN("Kernel tracer does not support buffer monitoring. "
-                                       "Setting the monitor interval timer to 0 "
-                                       "(disabled) for channel '%s' of session '%s'",
-                                       attr-> name, session->name);
-                       lttng_channel_set_monitor_timer_interval(attr, 0);
+               if (kernel_supports_ring_buffer_snapshot_sample_positions() != 1) {
+                       /* Sampling position of buffer is not supported */
+                       WARN("Kernel tracer does not support buffer monitoring. "
+                                       "Setting the monitor interval timer to 0 "
+                                       "(disabled) for channel '%s' of session '%s'",
+                                       attr.name, session->name);
+                       lttng_channel_set_monitor_timer_interval(&attr, 0);
                }
                break;
        }
@@ -1556,16 +1431,25 @@ int cmd_enable_channel(struct ltt_session *session,
        {
                struct ltt_kernel_channel *kchan;
 
-               kchan = trace_kernel_get_channel_by_name(attr->name,
+               kchan = trace_kernel_get_channel_by_name(attr.name,
                                session->kernel_session);
                if (kchan == NULL) {
+                       /*
+                        * Don't try to create a channel if the session has been started at
+                        * some point in time before. The tracer does not allow it.
+                        */
+                       if (session->has_been_started) {
+                               ret = LTTNG_ERR_TRACE_ALREADY_STARTED;
+                               goto error;
+                       }
+
                        if (session->snapshot.nb_output > 0 ||
                                        session->snapshot_mode) {
                                /* Enforce mmap output for snapshot sessions. */
-                               attr->attr.output = LTTNG_EVENT_MMAP;
+                               attr.attr.output = LTTNG_EVENT_MMAP;
                        }
-                       ret = channel_kernel_create(session->kernel_session, attr, wpipe);
-                       if (attr->name[0] != '\0') {
+                       ret = channel_kernel_create(session->kernel_session, &attr, wpipe);
+                       if (attr.name[0] != '\0') {
                                session->kernel_session->has_non_default_channel = 1;
                        }
                } else {
@@ -1576,7 +1460,7 @@ int cmd_enable_channel(struct ltt_session *session,
                        goto error;
                }
 
-               kernel_wait_quiescent(kernel_tracer_fd);
+               kernel_wait_quiescent();
                break;
        }
        case LTTNG_DOMAIN_UST:
@@ -1595,19 +1479,19 @@ int cmd_enable_channel(struct ltt_session *session,
                 * adhered to.
                 */
                if (domain->type == LTTNG_DOMAIN_JUL) {
-                       if (strncmp(attr->name, DEFAULT_JUL_CHANNEL_NAME,
+                       if (strncmp(attr.name, DEFAULT_JUL_CHANNEL_NAME,
                                        LTTNG_SYMBOL_NAME_LEN)) {
                                ret = LTTNG_ERR_INVALID_CHANNEL_NAME;
                                goto error;
                        }
                } else if (domain->type == LTTNG_DOMAIN_LOG4J) {
-                       if (strncmp(attr->name, DEFAULT_LOG4J_CHANNEL_NAME,
+                       if (strncmp(attr.name, DEFAULT_LOG4J_CHANNEL_NAME,
                                        LTTNG_SYMBOL_NAME_LEN)) {
                                ret = LTTNG_ERR_INVALID_CHANNEL_NAME;
                                goto error;
                        }
                } else if (domain->type == LTTNG_DOMAIN_PYTHON) {
-                       if (strncmp(attr->name, DEFAULT_PYTHON_CHANNEL_NAME,
+                       if (strncmp(attr.name, DEFAULT_PYTHON_CHANNEL_NAME,
                                        LTTNG_SYMBOL_NAME_LEN)) {
                                ret = LTTNG_ERR_INVALID_CHANNEL_NAME;
                                goto error;
@@ -1616,10 +1500,19 @@ int cmd_enable_channel(struct ltt_session *session,
 
                chan_ht = usess->domain_global.channels;
 
-               uchan = trace_ust_find_channel_by_name(chan_ht, attr->name);
+               uchan = trace_ust_find_channel_by_name(chan_ht, attr.name);
                if (uchan == NULL) {
-                       ret = channel_ust_create(usess, attr, domain->buf_type);
-                       if (attr->name[0] != '\0') {
+                       /*
+                        * Don't try to create a channel if the session has been started at
+                        * some point in time before. The tracer does not allow it.
+                        */
+                       if (session->has_been_started) {
+                               ret = LTTNG_ERR_TRACE_ALREADY_STARTED;
+                               goto error;
+                       }
+
+                       ret = channel_ust_create(usess, &attr, domain->buf_type);
+                       if (attr.name[0] != '\0') {
                                usess->has_non_default_channel = 1;
                        }
                } else {
@@ -1632,7 +1525,7 @@ int cmd_enable_channel(struct ltt_session *session,
                goto error;
        }
 
-       if (ret == LTTNG_OK && attr->attr.output != LTTNG_EVENT_MMAP) {
+       if (ret == LTTNG_OK && attr.attr.output != LTTNG_EVENT_MMAP) {
                session->has_non_mmap_channel = true;
        }
 error:
@@ -1641,15 +1534,220 @@ end:
        return ret;
 }
 
+enum lttng_error_code cmd_process_attr_tracker_get_tracking_policy(
+               struct ltt_session *session,
+               enum lttng_domain_type domain,
+               enum lttng_process_attr process_attr,
+               enum lttng_tracking_policy *policy)
+{
+       enum lttng_error_code ret_code = LTTNG_OK;
+       const struct process_attr_tracker *tracker;
+
+       switch (domain) {
+       case LTTNG_DOMAIN_KERNEL:
+               if (!session->kernel_session) {
+                       ret_code = LTTNG_ERR_INVALID;
+                       goto end;
+               }
+               tracker = kernel_get_process_attr_tracker(
+                               session->kernel_session, process_attr);
+               break;
+       case LTTNG_DOMAIN_UST:
+               if (!session->ust_session) {
+                       ret_code = LTTNG_ERR_INVALID;
+                       goto end;
+               }
+               tracker = trace_ust_get_process_attr_tracker(
+                               session->ust_session, process_attr);
+               break;
+       default:
+               ret_code = LTTNG_ERR_UNSUPPORTED_DOMAIN;
+               goto end;
+       }
+       if (tracker) {
+               *policy = process_attr_tracker_get_tracking_policy(tracker);
+       } else {
+               ret_code = LTTNG_ERR_INVALID;
+       }
+end:
+       return ret_code;
+}
+
+enum lttng_error_code cmd_process_attr_tracker_set_tracking_policy(
+               struct ltt_session *session,
+               enum lttng_domain_type domain,
+               enum lttng_process_attr process_attr,
+               enum lttng_tracking_policy policy)
+{
+       enum lttng_error_code ret_code = LTTNG_OK;
+
+       switch (policy) {
+       case LTTNG_TRACKING_POLICY_INCLUDE_SET:
+       case LTTNG_TRACKING_POLICY_EXCLUDE_ALL:
+       case LTTNG_TRACKING_POLICY_INCLUDE_ALL:
+               break;
+       default:
+               ret_code = LTTNG_ERR_INVALID;
+               goto end;
+       }
+
+       switch (domain) {
+       case LTTNG_DOMAIN_KERNEL:
+               if (!session->kernel_session) {
+                       ret_code = LTTNG_ERR_INVALID;
+                       goto end;
+               }
+               ret_code = kernel_process_attr_tracker_set_tracking_policy(
+                               session->kernel_session, process_attr, policy);
+               break;
+       case LTTNG_DOMAIN_UST:
+               if (!session->ust_session) {
+                       ret_code = LTTNG_ERR_INVALID;
+                       goto end;
+               }
+               ret_code = trace_ust_process_attr_tracker_set_tracking_policy(
+                               session->ust_session, process_attr, policy);
+               break;
+       default:
+               ret_code = LTTNG_ERR_UNSUPPORTED_DOMAIN;
+               break;
+       }
+end:
+       return ret_code;
+}
+
+enum lttng_error_code cmd_process_attr_tracker_inclusion_set_add_value(
+               struct ltt_session *session,
+               enum lttng_domain_type domain,
+               enum lttng_process_attr process_attr,
+               const struct process_attr_value *value)
+{
+       enum lttng_error_code ret_code = LTTNG_OK;
+
+       switch (domain) {
+       case LTTNG_DOMAIN_KERNEL:
+               if (!session->kernel_session) {
+                       ret_code = LTTNG_ERR_INVALID;
+                       goto end;
+               }
+               ret_code = kernel_process_attr_tracker_inclusion_set_add_value(
+                               session->kernel_session, process_attr, value);
+               break;
+       case LTTNG_DOMAIN_UST:
+               if (!session->ust_session) {
+                       ret_code = LTTNG_ERR_INVALID;
+                       goto end;
+               }
+               ret_code = trace_ust_process_attr_tracker_inclusion_set_add_value(
+                               session->ust_session, process_attr, value);
+               break;
+       default:
+               ret_code = LTTNG_ERR_UNSUPPORTED_DOMAIN;
+               break;
+       }
+end:
+       return ret_code;
+}
+
+enum lttng_error_code cmd_process_attr_tracker_inclusion_set_remove_value(
+               struct ltt_session *session,
+               enum lttng_domain_type domain,
+               enum lttng_process_attr process_attr,
+               const struct process_attr_value *value)
+{
+       enum lttng_error_code ret_code = LTTNG_OK;
+
+       switch (domain) {
+       case LTTNG_DOMAIN_KERNEL:
+               if (!session->kernel_session) {
+                       ret_code = LTTNG_ERR_INVALID;
+                       goto end;
+               }
+               ret_code = kernel_process_attr_tracker_inclusion_set_remove_value(
+                               session->kernel_session, process_attr, value);
+               break;
+       case LTTNG_DOMAIN_UST:
+               if (!session->ust_session) {
+                       ret_code = LTTNG_ERR_INVALID;
+                       goto end;
+               }
+               ret_code = trace_ust_process_attr_tracker_inclusion_set_remove_value(
+                               session->ust_session, process_attr, value);
+               break;
+       default:
+               ret_code = LTTNG_ERR_UNSUPPORTED_DOMAIN;
+               break;
+       }
+end:
+       return ret_code;
+}
+
+enum lttng_error_code cmd_process_attr_tracker_get_inclusion_set(
+               struct ltt_session *session,
+               enum lttng_domain_type domain,
+               enum lttng_process_attr process_attr,
+               struct lttng_process_attr_values **values)
+{
+       enum lttng_error_code ret_code = LTTNG_OK;
+       const struct process_attr_tracker *tracker;
+       enum process_attr_tracker_status status;
+
+       switch (domain) {
+       case LTTNG_DOMAIN_KERNEL:
+               if (!session->kernel_session) {
+                       ret_code = LTTNG_ERR_INVALID;
+                       goto end;
+               }
+               tracker = kernel_get_process_attr_tracker(
+                               session->kernel_session, process_attr);
+               break;
+       case LTTNG_DOMAIN_UST:
+               if (!session->ust_session) {
+                       ret_code = LTTNG_ERR_INVALID;
+                       goto end;
+               }
+               tracker = trace_ust_get_process_attr_tracker(
+                               session->ust_session, process_attr);
+               break;
+       default:
+               ret_code = LTTNG_ERR_UNSUPPORTED_DOMAIN;
+               goto end;
+       }
+
+       if (!tracker) {
+               ret_code = LTTNG_ERR_INVALID;
+               goto end;
+       }
+
+       status = process_attr_tracker_get_inclusion_set(tracker, values);
+       switch (status) {
+       case PROCESS_ATTR_TRACKER_STATUS_OK:
+               ret_code = LTTNG_OK;
+               break;
+       case PROCESS_ATTR_TRACKER_STATUS_INVALID_TRACKING_POLICY:
+               ret_code = LTTNG_ERR_PROCESS_ATTR_TRACKER_INVALID_TRACKING_POLICY;
+               break;
+       case PROCESS_ATTR_TRACKER_STATUS_ERROR:
+               ret_code = LTTNG_ERR_NOMEM;
+               break;
+       default:
+               ret_code = LTTNG_ERR_UNK;
+               break;
+       }
+
+end:
+       return ret_code;
+}
+
 /*
  * Command LTTNG_DISABLE_EVENT processed by the client thread.
  */
 int cmd_disable_event(struct ltt_session *session,
-               enum lttng_domain_type domain, char *channel_name,
-               struct lttng_event *event)
+               enum lttng_domain_type domain, const char *channel_name,
+               const struct lttng_event *event)
 {
        int ret;
-       char *event_name;
+       const char *event_name;
 
        DBG("Disable event command for event \'%s\'", event->name);
 
@@ -1711,7 +1809,7 @@ int cmd_disable_event(struct ltt_session *session,
                        goto error_unlock;
                }
 
-               kernel_wait_quiescent(kernel_tracer_fd);
+               kernel_wait_quiescent();
                break;
        }
        case LTTNG_DOMAIN_UST:
@@ -1775,7 +1873,7 @@ int cmd_disable_event(struct ltt_session *session,
                struct agent *agt;
                struct ltt_ust_session *usess = session->ust_session;
 
-               assert(usess);
+               LTTNG_ASSERT(usess);
 
                switch (event->type) {
                case LTTNG_EVENT_ALL:
@@ -1822,7 +1920,7 @@ error:
  * Command LTTNG_ADD_CONTEXT processed by the client thread.
  */
 int cmd_add_context(struct ltt_session *session, enum lttng_domain_type domain,
-               char *channel_name, struct lttng_event_context *ctx, int kwpipe)
+               char *channel_name, const 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;
@@ -1844,7 +1942,7 @@ int cmd_add_context(struct ltt_session *session, enum lttng_domain_type domain,
 
        switch (domain) {
        case LTTNG_DOMAIN_KERNEL:
-               assert(session->kernel_session);
+               LTTNG_ASSERT(session->kernel_session);
 
                if (session->kernel_session->channel_count == 0) {
                        /* Create default channel */
@@ -1888,7 +1986,7 @@ int cmd_add_context(struct ltt_session *session, enum lttng_domain_type domain,
                struct ltt_ust_session *usess = session->ust_session;
                unsigned int chan_count;
 
-               assert(usess);
+               LTTNG_ASSERT(usess);
 
                chan_count = lttng_ht_get_count(usess->domain_global.channels);
                if (chan_count == 0) {
@@ -1933,7 +2031,7 @@ error:
                        trace_kernel_get_channel_by_name(DEFAULT_CHANNEL_NAME,
                                        session->kernel_session);
                /* Created previously, this should NOT fail. */
-               assert(kchan);
+               LTTNG_ASSERT(kchan);
                kernel_destroy_channel(kchan);
        }
 
@@ -1943,7 +2041,7 @@ error:
                                        session->ust_session->domain_global.channels,
                                        DEFAULT_CHANNEL_NAME);
                /* Created previously, this should NOT fail. */
-               assert(uchan);
+               LTTNG_ASSERT(uchan);
                /* Remove from the channel list of the session. */
                trace_ust_delete_channel(session->ust_session->domain_global.channels,
                                uchan);
@@ -1993,22 +2091,22 @@ end:
  * enable the events through which all "agent" events are funeled.
  */
 static int _cmd_enable_event(struct ltt_session *session,
-               struct lttng_domain *domain,
+               const struct lttng_domain *domain,
                char *channel_name, struct lttng_event *event,
                char *filter_expression,
-               struct lttng_filter_bytecode *filter,
+               struct lttng_bytecode *filter,
                struct lttng_event_exclusion *exclusion,
                int wpipe, bool internal_event)
 {
        int ret = 0, channel_created = 0;
        struct lttng_channel *attr = NULL;
 
-       assert(session);
-       assert(event);
-       assert(channel_name);
+       LTTNG_ASSERT(session);
+       LTTNG_ASSERT(event);
+       LTTNG_ASSERT(channel_name);
 
        /* If we have a filter, we must have its filter expression */
-       assert(!(!!filter_expression ^ !!filter));
+       LTTNG_ASSERT(!(!!filter_expression ^ !!filter));
 
        /* Normalize event name as a globbing pattern */
        strutils_normalize_star_glob_pattern(event->name);
@@ -2079,7 +2177,7 @@ static int _cmd_enable_event(struct ltt_session *session,
                case LTTNG_EVENT_ALL:
                {
                        char *filter_expression_a = NULL;
-                       struct lttng_filter_bytecode *filter_a = NULL;
+                       struct lttng_bytecode *filter_a = NULL;
 
                        /*
                         * We need to duplicate filter_expression and filter,
@@ -2161,7 +2259,7 @@ static int _cmd_enable_event(struct ltt_session *session,
                        goto error;
                }
 
-               kernel_wait_quiescent(kernel_tracer_fd);
+               kernel_wait_quiescent();
                break;
        }
        case LTTNG_DOMAIN_UST:
@@ -2169,7 +2267,7 @@ static int _cmd_enable_event(struct ltt_session *session,
                struct ltt_ust_channel *uchan;
                struct ltt_ust_session *usess = session->ust_session;
 
-               assert(usess);
+               LTTNG_ASSERT(usess);
 
                /*
                 * If a non-default channel has been created in the
@@ -2206,7 +2304,7 @@ static int _cmd_enable_event(struct ltt_session *session,
                        /* Get the newly created channel reference back */
                        uchan = trace_ust_find_channel_by_name(
                                        usess->domain_global.channels, channel_name);
-                       assert(uchan);
+                       LTTNG_ASSERT(uchan);
                }
 
                if (uchan->domain != LTTNG_DOMAIN_UST && !internal_event) {
@@ -2226,7 +2324,7 @@ static int _cmd_enable_event(struct ltt_session *session,
                         */
                        ret = validate_ust_event_name(event->name);
                        if (ret) {
-                               WARN("Userspace event name %s failed validation.",
+                               WARN("Userspace event name %s failed validation.",
                                                event->name);
                                ret = LTTNG_ERR_INVALID_EVENT_NAME;
                                goto error;
@@ -2258,7 +2356,7 @@ static int _cmd_enable_event(struct ltt_session *session,
                struct lttng_domain tmp_dom;
                struct ltt_ust_session *usess = session->ust_session;
 
-               assert(usess);
+               LTTNG_ASSERT(usess);
 
                if (!agent_tracing_is_enabled()) {
                        DBG("Attempted to enable an event in an agent domain but the agent thread is not running");
@@ -2309,16 +2407,16 @@ static int _cmd_enable_event(struct ltt_session *session,
                        break;
                default:
                        /* The switch/case we are in makes this impossible */
-                       assert(0);
+                       abort();
                }
 
                {
                        char *filter_expression_copy = NULL;
-                       struct lttng_filter_bytecode *filter_copy = NULL;
+                       struct lttng_bytecode *filter_copy = NULL;
 
                        if (filter) {
                                const size_t filter_size = sizeof(
-                                               struct lttng_filter_bytecode)
+                                               struct lttng_bytecode)
                                                + filter->len;
 
                                filter_copy = zmalloc(filter_size);
@@ -2390,10 +2488,11 @@ error:
  * Command LTTNG_ENABLE_EVENT processed by the client thread.
  * We own filter, exclusion, and filter_expression.
  */
-int cmd_enable_event(struct ltt_session *session, struct lttng_domain *domain,
+int cmd_enable_event(struct ltt_session *session,
+               const struct lttng_domain *domain,
                char *channel_name, struct lttng_event *event,
                char *filter_expression,
-               struct lttng_filter_bytecode *filter,
+               struct lttng_bytecode *filter,
                struct lttng_event_exclusion *exclusion,
                int wpipe)
 {
@@ -2407,10 +2506,10 @@ int cmd_enable_event(struct ltt_session *session, struct lttng_domain *domain,
  * reserved names.
  */
 static int cmd_enable_event_internal(struct ltt_session *session,
-               struct lttng_domain *domain,
+               const struct lttng_domain *domain,
                char *channel_name, struct lttng_event *event,
                char *filter_expression,
-               struct lttng_filter_bytecode *filter,
+               struct lttng_bytecode *filter,
                struct lttng_event_exclusion *exclusion,
                int wpipe)
 {
@@ -2429,7 +2528,7 @@ ssize_t cmd_list_tracepoints(enum lttng_domain_type domain,
 
        switch (domain) {
        case LTTNG_DOMAIN_KERNEL:
-               nb_events = kernel_list_events(kernel_tracer_fd, events);
+               nb_events = kernel_list_events(events);
                if (nb_events < 0) {
                        ret = LTTNG_ERR_KERN_LIST_FAIL;
                        goto error;
@@ -2476,79 +2575,28 @@ ssize_t cmd_list_tracepoint_fields(enum lttng_domain_type domain,
        case LTTNG_DOMAIN_UST:
                nb_fields = ust_app_list_event_fields(fields);
                if (nb_fields < 0) {
-                       ret = LTTNG_ERR_UST_LIST_FAIL;
-                       goto error;
-               }
-               break;
-       case LTTNG_DOMAIN_KERNEL:
-       default:        /* fall-through */
-               ret = LTTNG_ERR_UND;
-               goto error;
-       }
-
-       return nb_fields;
-
-error:
-       /* Return negative value to differentiate return code */
-       return -ret;
-}
-
-ssize_t cmd_list_syscalls(struct lttng_event **events)
-{
-       return syscall_table_list(events);
-}
-
-/*
- * Command LTTNG_LIST_TRACKER_PIDS processed by the client thread.
- *
- * Called with session lock held.
- */
-ssize_t cmd_list_tracker_pids(struct ltt_session *session,
-               enum lttng_domain_type domain, int32_t **pids)
-{
-       int ret;
-       ssize_t nr_pids = 0;
-
-       switch (domain) {
-       case LTTNG_DOMAIN_KERNEL:
-       {
-               struct ltt_kernel_session *ksess;
-
-               ksess = session->kernel_session;
-               nr_pids = kernel_list_tracker_pids(ksess, pids);
-               if (nr_pids < 0) {
-                       ret = LTTNG_ERR_KERN_LIST_FAIL;
-                       goto error;
-               }
-               break;
-       }
-       case LTTNG_DOMAIN_UST:
-       {
-               struct ltt_ust_session *usess;
-
-               usess = session->ust_session;
-               nr_pids = trace_ust_list_tracker_pids(usess, pids);
-               if (nr_pids < 0) {
-                       ret = LTTNG_ERR_UST_LIST_FAIL;
-                       goto error;
-               }
-               break;
-       }
-       case LTTNG_DOMAIN_LOG4J:
-       case LTTNG_DOMAIN_JUL:
-       case LTTNG_DOMAIN_PYTHON:
-       default:
+                       ret = LTTNG_ERR_UST_LIST_FAIL;
+                       goto error;
+               }
+               break;
+       case LTTNG_DOMAIN_KERNEL:
+       default:        /* fall-through */
                ret = LTTNG_ERR_UND;
                goto error;
        }
 
-       return nr_pids;
+       return nb_fields;
 
 error:
        /* Return negative value to differentiate return code */
        return -ret;
 }
 
+ssize_t cmd_list_syscalls(struct lttng_event **events)
+{
+       return syscall_table_list(events);
+}
+
 /*
  * Command LTTNG_START_TRACE processed by the client thread.
  *
@@ -2560,8 +2608,12 @@ int cmd_start_trace(struct ltt_session *session)
        unsigned long nb_chan = 0;
        struct ltt_kernel_session *ksession;
        struct ltt_ust_session *usess;
+       const bool session_rotated_after_last_stop =
+                       session->rotated_after_last_stop;
+       const bool session_cleared_after_last_stop =
+                       session->cleared_after_last_stop;
 
-       assert(session);
+       LTTNG_ASSERT(session);
 
        /* Ease our life a bit ;) */
        ksession = session->kernel_session;
@@ -2570,6 +2622,23 @@ int cmd_start_trace(struct ltt_session *session)
        /* Is the session already started? */
        if (session->active) {
                ret = LTTNG_ERR_TRACE_ALREADY_STARTED;
+               /* Perform nothing */
+               goto end;
+       }
+
+       if (session->rotation_state == LTTNG_ROTATION_STATE_ONGOING &&
+                       !session->current_trace_chunk) {
+               /*
+                * A rotation was launched while the session was stopped and
+                * it has not been completed yet. It is not possible to start
+                * the session since starting the session here would require a
+                * rotation from "NULL" to a new trace chunk. That rotation
+                * would overlap with the ongoing rotation, which is not
+                * supported.
+                */
+               WARN("Refusing to start session \"%s\" as a rotation launched after the last \"stop\" is still ongoing",
+                               session->name);
+               ret = LTTNG_ERR_ROTATION_PENDING;
                goto error;
        }
 
@@ -2588,28 +2657,54 @@ int cmd_start_trace(struct ltt_session *session)
                goto error;
        }
 
+       session->active = 1;
+       session->rotated_after_last_stop = false;
+       session->cleared_after_last_stop = false;
        if (session->output_traces && !session->current_trace_chunk) {
-               struct lttng_trace_chunk *trace_chunk;
+               if (!session->has_been_started) {
+                       struct lttng_trace_chunk *trace_chunk;
 
-               trace_chunk = session_create_new_trace_chunk(
-                               session, NULL, NULL, NULL);
-               if (!trace_chunk) {
-                       ret = LTTNG_ERR_CREATE_DIR_FAIL;
-                       goto error;
-               }
-               assert(!session->current_trace_chunk);
-               ret = session_set_trace_chunk(session, trace_chunk, NULL);
-               lttng_trace_chunk_put(trace_chunk);
-               if (ret) {
-                       ret = LTTNG_ERR_CREATE_TRACE_CHUNK_FAIL_CONSUMER;
-                       goto error;
+                       DBG("Creating initial trace chunk of session \"%s\"",
+                                       session->name);
+                       trace_chunk = session_create_new_trace_chunk(
+                                       session, NULL, NULL, NULL);
+                       if (!trace_chunk) {
+                               ret = LTTNG_ERR_CREATE_DIR_FAIL;
+                               goto error;
+                       }
+                       LTTNG_ASSERT(!session->current_trace_chunk);
+                       ret = session_set_trace_chunk(session, trace_chunk,
+                                       NULL);
+                       lttng_trace_chunk_put(trace_chunk);
+                       if (ret) {
+                               ret = LTTNG_ERR_CREATE_TRACE_CHUNK_FAIL_CONSUMER;
+                               goto error;
+                       }
+               } else {
+                       DBG("Rotating session \"%s\" from its current \"NULL\" trace chunk to a new chunk",
+                                       session->name);
+                       /*
+                        * Rotate existing streams into the new chunk.
+                        * This is a "quiet" rotation has no client has
+                        * explicitly requested this operation.
+                        *
+                        * There is also no need to wait for the rotation
+                        * to complete as it will happen immediately. No data
+                        * was produced as the session was stopped, so the
+                        * rotation should happen on reception of the command.
+                        */
+                       ret = cmd_rotate_session(session, NULL, true,
+                                       LTTNG_TRACE_CHUNK_COMMAND_TYPE_NO_OPERATION);
+                       if (ret != LTTNG_OK) {
+                               goto error;
+                       }
                }
        }
 
        /* Kernel tracing */
        if (ksession != NULL) {
                DBG("Start kernel tracing session %s", session->name);
-               ret = start_kernel_session(ksession, kernel_tracer_fd);
+               ret = start_kernel_session(ksession);
                if (ret != LTTNG_OK) {
                        goto error;
                }
@@ -2625,9 +2720,15 @@ int cmd_start_trace(struct ltt_session *session)
                }
        }
 
-       /* Flag this after a successful start. */
-       session->has_been_started = 1;
-       session->active = 1;
+       /*
+        * Open a packet in every stream of the session to ensure that viewers
+        * can correctly identify the boundaries of the periods during which
+        * tracing was active for this session.
+        */
+       ret = session_open_packets(session);
+       if (ret != LTTNG_OK) {
+               goto error;
+       }
 
        /*
         * Clear the flag that indicates that a rotation was done while the
@@ -2649,6 +2750,18 @@ int cmd_start_trace(struct ltt_session *session)
        ret = LTTNG_OK;
 
 error:
+       if (ret == LTTNG_OK) {
+               /* Flag this after a successful start. */
+               session->has_been_started |= 1;
+       } else {
+               session->active = 0;
+               /* Restore initial state on error. */
+               session->rotated_after_last_stop =
+                               session_rotated_after_last_stop;
+               session->cleared_after_last_stop =
+                               session_cleared_after_last_stop;
+       }
+end:
        return ret;
 }
 
@@ -2658,14 +2771,12 @@ error:
 int cmd_stop_trace(struct ltt_session *session)
 {
        int ret;
-       struct ltt_kernel_channel *kchan;
        struct ltt_kernel_session *ksession;
        struct ltt_ust_session *usess;
-       bool error_occurred = false;
 
-       assert(session);
+       LTTNG_ASSERT(session);
 
-       DBG("Begin stop session %s (id %" PRIu64 ")", session->name, session->id);
+       DBG("Begin stop session \"%s\" (id %" PRIu64 ")", session->name, session->id);
        /* Short cut */
        ksession = session->kernel_session;
        usess = session->ust_session;
@@ -2676,37 +2787,9 @@ int cmd_stop_trace(struct ltt_session *session)
                goto error;
        }
 
-       /* Kernel tracer */
-       if (ksession && ksession->active) {
-               DBG("Stop kernel tracing");
-
-               ret = kernel_stop_session(ksession);
-               if (ret < 0) {
-                       ret = LTTNG_ERR_KERN_STOP_FAIL;
-                       goto error;
-               }
-
-               kernel_wait_quiescent(kernel_tracer_fd);
-
-               /* Flush metadata after stopping (if exists) */
-               if (ksession->metadata_stream_fd >= 0) {
-                       ret = kernel_metadata_flush_buffer(ksession->metadata_stream_fd);
-                       if (ret < 0) {
-                               ERR("Kernel metadata flush failed");
-                       }
-               }
-
-               /* Flush all buffers after stopping */
-               cds_list_for_each_entry(kchan, &ksession->channel_list.head, list) {
-                       ret = kernel_flush_buffer(kchan);
-                       if (ret < 0) {
-                               ERR("Kernel flush buffer error");
-                       }
-               }
-
-               ksession->active = 0;
-               DBG("Kernel session stopped %s (id %" PRIu64 ")", session->name,
-                               session->id);
+       ret = stop_kernel_session(ksession);
+       if (ret != LTTNG_OK) {
+               goto error;
        }
 
        if (usess && usess->active) {
@@ -2717,10 +2800,51 @@ int cmd_stop_trace(struct ltt_session *session)
                }
        }
 
+       DBG("Completed stop session \"%s\" (id %" PRIu64 ")", session->name,
+                       session->id);
        /* Flag inactive after a successful stop. */
        session->active = 0;
-       ret = !error_occurred ? LTTNG_OK : LTTNG_ERR_UNK;
+       ret = LTTNG_OK;
+
+error:
+       return ret;
+}
+
+/*
+ * Set the base_path of the session only if subdir of a control uris is set.
+ * Return LTTNG_OK on success, otherwise LTTNG_ERR_*.
+ */
+static int set_session_base_path_from_uris(struct ltt_session *session,
+               size_t nb_uri,
+               struct lttng_uri *uris)
+{
+       int ret;
+       size_t i;
+
+       for (i = 0; i < nb_uri; i++) {
+               if (uris[i].stype != LTTNG_STREAM_CONTROL ||
+                               uris[i].subdir[0] == '\0') {
+                       /* Not interested in these URIs */
+                       continue;
+               }
+
+               if (session->base_path != NULL) {
+                       free(session->base_path);
+                       session->base_path = NULL;
+               }
 
+               /* Set session base_path */
+               session->base_path = strdup(uris[i].subdir);
+               if (!session->base_path) {
+                       PERROR("Failed to copy base path \"%s\" to session \"%s\"",
+                                       uris[i].subdir, session->name);
+                       ret = LTTNG_ERR_NOMEM;
+                       goto error;
+               }
+               DBG2("Setting base path \"%s\" for session \"%s\"",
+                               session->base_path, session->name);
+       }
+       ret = LTTNG_OK;
 error:
        return ret;
 }
@@ -2735,9 +2859,9 @@ int cmd_set_consumer_uri(struct ltt_session *session, size_t nb_uri,
        struct ltt_kernel_session *ksess = session->kernel_session;
        struct ltt_ust_session *usess = session->ust_session;
 
-       assert(session);
-       assert(uris);
-       assert(nb_uri > 0);
+       LTTNG_ASSERT(session);
+       LTTNG_ASSERT(uris);
+       LTTNG_ASSERT(nb_uri > 0);
 
        /* Can't set consumer URI if the session is active. */
        if (session->active) {
@@ -2745,11 +2869,20 @@ int cmd_set_consumer_uri(struct ltt_session *session, size_t nb_uri,
                goto error;
        }
 
+       /*
+        * Set the session base path if any. This is done inside
+        * cmd_set_consumer_uri to preserve backward compatibility of the
+        * previous session creation api vs the session descriptor api.
+        */
+       ret = set_session_base_path_from_uris(session, nb_uri, uris);
+       if (ret != LTTNG_OK) {
+               goto error;
+       }
+
        /* Set the "global" consumer URIs */
        for (i = 0; i < nb_uri; i++) {
-               ret = add_uri_to_consumer(session,
-                               session->consumer,
-                               &uris[i], LTTNG_DOMAIN_NONE);
+               ret = add_uri_to_consumer(session, session->consumer, &uris[i],
+                               LTTNG_DOMAIN_NONE);
                if (ret != LTTNG_OK) {
                        goto error;
                }
@@ -2880,7 +3013,6 @@ enum lttng_error_code cmd_create_session_from_descriptor(
        const char *session_name;
        struct ltt_session *new_session = NULL;
        enum lttng_session_descriptor_status descriptor_status;
-       const char *base_path;
 
        session_lock_list();
        if (home_path) {
@@ -2903,13 +3035,9 @@ enum lttng_error_code cmd_create_session_from_descriptor(
                ret_code = LTTNG_ERR_INVALID;
                goto end;
        }
-       ret = lttng_session_descriptor_get_base_path(descriptor, &base_path);
-       if (ret) {
-               ret_code = LTTNG_ERR_INVALID;
-               goto end;
-       }
+
        ret_code = session_create(session_name, creds->uid, creds->gid,
-                       base_path, &new_session);
+                       &new_session);
        if (ret_code != LTTNG_OK) {
                goto end;
        }
@@ -2985,19 +3113,19 @@ enum lttng_error_code cmd_create_session(struct command_ctx *cmd_ctx, int sock,
        enum lttng_error_code ret_code;
 
        lttng_dynamic_buffer_init(&payload);
-       if (cmd_ctx->lsm->u.create_session.home_dir_size >=
+       if (cmd_ctx->lsm.u.create_session.home_dir_size >=
                        LTTNG_PATH_MAX) {
                ret_code = LTTNG_ERR_INVALID;
                goto error;
        }
-       if (cmd_ctx->lsm->u.create_session.session_descriptor_size >
+       if (cmd_ctx->lsm.u.create_session.session_descriptor_size >
                        LTTNG_SESSION_DESCRIPTOR_MAX_LEN) {
                ret_code = LTTNG_ERR_INVALID;
                goto error;
        }
 
-       payload_size = cmd_ctx->lsm->u.create_session.home_dir_size +
-                       cmd_ctx->lsm->u.create_session.session_descriptor_size;
+       payload_size = cmd_ctx->lsm.u.create_session.home_dir_size +
+                       cmd_ctx->lsm.u.create_session.session_descriptor_size;
        ret = lttng_dynamic_buffer_set_size(&payload, payload_size);
        if (ret) {
                ret_code = LTTNG_ERR_NOMEM;
@@ -3014,11 +3142,23 @@ enum lttng_error_code cmd_create_session(struct command_ctx *cmd_ctx, int sock,
        home_dir_view = lttng_buffer_view_from_dynamic_buffer(
                        &payload,
                        0,
-                       cmd_ctx->lsm->u.create_session.home_dir_size);
+                       cmd_ctx->lsm.u.create_session.home_dir_size);
+       if (cmd_ctx->lsm.u.create_session.home_dir_size > 0 &&
+                       !lttng_buffer_view_is_valid(&home_dir_view)) {
+               ERR("Invalid payload in \"create session\" command: buffer too short to contain home directory");
+               ret_code = LTTNG_ERR_INVALID_PROTOCOL;
+               goto error;
+       }
+
        session_descriptor_view = lttng_buffer_view_from_dynamic_buffer(
                        &payload,
-                       cmd_ctx->lsm->u.create_session.home_dir_size,
-                       cmd_ctx->lsm->u.create_session.session_descriptor_size);
+                       cmd_ctx->lsm.u.create_session.home_dir_size,
+                       cmd_ctx->lsm.u.create_session.session_descriptor_size);
+       if (!lttng_buffer_view_is_valid(&session_descriptor_view)) {
+               ERR("Invalid payload in \"create session\" command: buffer too short to contain session descriptor");
+               ret_code = LTTNG_ERR_INVALID_PROTOCOL;
+               goto error;
+       }
 
        ret = lttng_session_descriptor_create_from_buffer(
                        &session_descriptor_view, &session_descriptor);
@@ -3061,7 +3201,7 @@ void cmd_destroy_session_reply(const struct ltt_session *session,
        struct lttng_trace_archive_location *location = NULL;
        struct lttcomm_lttng_msg llm = {
                .cmd_type = LTTNG_DESTROY_SESSION,
-               .ret_code = LTTNG_OK,
+               .ret_code = reply_context->destruction_status,
                .pid = UINT32_MAX,
                .cmd_header_size =
                        sizeof(struct lttcomm_session_destroy_command_header),
@@ -3072,10 +3212,10 @@ void cmd_destroy_session_reply(const struct ltt_session *session,
        lttng_dynamic_buffer_init(&payload);
 
        ret = lttng_dynamic_buffer_append(&payload, &llm, sizeof(llm));
-        if (ret) {
+       if (ret) {
                ERR("Failed to append session destruction message");
                goto error;
-        }
+       }
 
        cmd_header.rotation_state =
                        (int32_t) (reply_context->implicit_rotation_on_destroy ?
@@ -3109,6 +3249,7 @@ void cmd_destroy_session_reply(const struct ltt_session *session,
        payload_size_before_location = payload.size;
        comm_ret = lttng_trace_archive_location_serialize(location,
                        &payload);
+       lttng_trace_archive_location_put(location);
        if (comm_ret < 0) {
                ERR("Failed to serialize the location of the trace archive produced during the destruction of session \"%s\"",
                                session->name);
@@ -3143,6 +3284,7 @@ int cmd_destroy_session(struct ltt_session *session,
                int *sock_fd)
 {
        int ret;
+       enum lttng_error_code destruction_last_error = LTTNG_OK;
        struct cmd_destroy_session_reply_context *reply_context = NULL;
 
        if (sock_fd) {
@@ -3155,7 +3297,7 @@ int cmd_destroy_session(struct ltt_session *session,
        }
 
        /* Safety net */
-       assert(session);
+       LTTNG_ASSERT(session);
 
        DBG("Begin destroy session %s (id %" PRIu64 ")", session->name,
                        session->id);
@@ -3167,6 +3309,7 @@ int cmd_destroy_session(struct ltt_session *session,
                        /* Carry on with the destruction of the session. */
                        ERR("Failed to stop session \"%s\" as part of its destruction: %s",
                                        session->name, lttng_strerror(-ret));
+                       destruction_last_error = ret;
                }
        }
 
@@ -3175,6 +3318,7 @@ int cmd_destroy_session(struct ltt_session *session,
                                session)) {
                        ERR("Failed to stop the \"rotation schedule\" timer of session %s",
                                        session->name);
+                       destruction_last_error = LTTNG_ERR_TIMER_STOP_ERROR;
                }
        }
 
@@ -3183,22 +3327,22 @@ int cmd_destroy_session(struct ltt_session *session,
                session->rotate_size = 0;
        }
 
-       if (session->most_recent_chunk_id.is_set &&
-                       session->most_recent_chunk_id.value != 0 &&
-                       session->current_trace_chunk && session->output_traces) {
+       if (session->rotated && session->current_trace_chunk && session->output_traces) {
                /*
                 * Perform a last rotation on destruction if rotations have
                 * occurred during the session's lifetime.
                 */
-               ret = cmd_rotate_session(session, NULL, false);
+               ret = cmd_rotate_session(session, NULL, false,
+                       LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED);
                if (ret != LTTNG_OK) {
                        ERR("Failed to perform an implicit rotation as part of the destruction of session \"%s\": %s",
                                        session->name, lttng_strerror(-ret));
+                       destruction_last_error = -ret;
                }
-                if (reply_context) {
+               if (reply_context) {
                        reply_context->implicit_rotation_on_destroy = true;
-                }
-        } else if (session->has_been_started && session->current_trace_chunk) {
+               }
+       } else if (session->has_been_started && session->current_trace_chunk) {
                /*
                 * The user has not triggered a session rotation. However, to
                 * ensure all data has been consumed, the session is rotated
@@ -3208,10 +3352,20 @@ int cmd_destroy_session(struct ltt_session *session,
                 * emitted and no renaming of the current trace chunk takes
                 * place.
                 */
-               ret = cmd_rotate_session(session, NULL, true);
-               if (ret != LTTNG_OK) {
+               ret = cmd_rotate_session(session, NULL, true,
+                       LTTNG_TRACE_CHUNK_COMMAND_TYPE_NO_OPERATION);
+               /*
+                * Rotation operations may not be supported by the kernel
+                * tracer. Hence, do not consider this implicit rotation as
+                * a session destruction error. The library has already stopped
+                * the session and waited for pending data; there is nothing
+                * left to do but complete the destruction of the session.
+                */
+               if (ret != LTTNG_OK &&
+                               ret != -LTTNG_ERR_ROTATION_NOT_AVAILABLE_KERNEL) {
                        ERR("Failed to perform a quiet rotation as part of the destruction of session \"%s\": %s",
-                                       session->name, lttng_strerror(-ret));
+                           session->name, lttng_strerror(ret));
+                       destruction_last_error = -ret;
                }
        }
 
@@ -3266,7 +3420,7 @@ int cmd_destroy_session(struct ltt_session *session,
                ret = lttng_strncpy(destroy_completion_handler.shm_path,
                                session->shm_path,
                                sizeof(destroy_completion_handler.shm_path));
-               assert(!ret);
+               LTTNG_ASSERT(!ret);
        }
 
        /*
@@ -3276,6 +3430,7 @@ int cmd_destroy_session(struct ltt_session *session,
         */
        session_destroy(session);
        if (reply_context) {
+               reply_context->destruction_status = destruction_last_error;
                ret = session_add_destroy_notifier(session,
                                cmd_destroy_session_reply,
                                (void *) reply_context);
@@ -3285,8 +3440,8 @@ int cmd_destroy_session(struct ltt_session *session,
                } else {
                        *sock_fd = -1;
                }
-        }
-        ret = LTTNG_OK;
+       }
+       ret = LTTNG_OK;
 end:
        return ret;
 }
@@ -3301,16 +3456,16 @@ int cmd_register_consumer(struct ltt_session *session,
        int ret, sock;
        struct consumer_socket *socket = NULL;
 
-       assert(session);
-       assert(cdata);
-       assert(sock_path);
+       LTTNG_ASSERT(session);
+       LTTNG_ASSERT(cdata);
+       LTTNG_ASSERT(sock_path);
 
        switch (domain) {
        case LTTNG_DOMAIN_KERNEL:
        {
                struct ltt_kernel_session *ksess = session->kernel_session;
 
-               assert(ksess);
+               LTTNG_ASSERT(ksess);
 
                /* Can't register a consumer if there is already one */
                if (ksess->consumer_fds_sent != 0) {
@@ -3515,25 +3670,33 @@ end:
  */
 ssize_t cmd_list_events(enum lttng_domain_type domain,
                struct ltt_session *session, char *channel_name,
-               struct lttng_event **events, size_t *total_size)
+               struct lttng_payload *payload)
 {
        int ret = 0;
-       ssize_t nb_event = 0;
+       ssize_t nb_events = 0;
+       struct lttcomm_event_command_header cmd_header = {};
+       const size_t cmd_header_offset = payload->buffer.size;
+
+       ret = lttng_dynamic_buffer_append(
+                       &payload->buffer, &cmd_header, sizeof(cmd_header));
+       if (ret) {
+               ret = LTTNG_ERR_NOMEM;
+               goto error;
+       }
 
        switch (domain) {
        case LTTNG_DOMAIN_KERNEL:
                if (session->kernel_session != NULL) {
-                       nb_event = list_lttng_kernel_events(channel_name,
-                                       session->kernel_session, events,
-                                       total_size);
+                       nb_events = list_lttng_kernel_events(channel_name,
+                                       session->kernel_session, payload);
                }
                break;
        case LTTNG_DOMAIN_UST:
        {
                if (session->ust_session != NULL) {
-                       nb_event = list_lttng_ust_global_events(channel_name,
-                                       &session->ust_session->domain_global, events,
-                                       total_size);
+                       nb_events = list_lttng_ust_global_events(channel_name,
+                                       &session->ust_session->domain_global,
+                                       payload);
                }
                break;
        }
@@ -3548,9 +3711,8 @@ ssize_t cmd_list_events(enum lttng_domain_type domain,
                        cds_lfht_for_each_entry(session->ust_session->agents->ht,
                                        &iter.iter, agt, node.node) {
                                if (agt->domain == domain) {
-                                       nb_event = list_lttng_agent_events(
-                                                       agt, events,
-                                                       total_size);
+                                       nb_events = list_lttng_agent_events(
+                                                       agt, payload);
                                        break;
                                }
                        }
@@ -3562,7 +3724,10 @@ ssize_t cmd_list_events(enum lttng_domain_type domain,
                goto error;
        }
 
-       return nb_event;
+       ((struct lttcomm_event_command_header *) (payload->buffer.data +
+                        cmd_header_offset))->nb_events = (uint32_t) nb_events;
+
+       return nb_events;
 
 error:
        /* Return negative value to differentiate return code */
@@ -3583,7 +3748,7 @@ void cmd_list_lttng_sessions(struct lttng_session *sessions,
        unsigned int i = 0;
        struct ltt_session *session;
        struct ltt_session_list *list = session_get_list();
-        struct lttng_session_extended *extended =
+       struct lttng_session_extended *extended =
                        (typeof(extended)) (&sessions[session_count]);
 
        DBG("Getting all available session for UID %d GID %d",
@@ -3599,7 +3764,7 @@ void cmd_list_lttng_sessions(struct lttng_session *sessions,
                /*
                 * Only list the sessions the user can control.
                 */
-               if (!session_access_ok(session, uid, gid) ||
+               if (!session_access_ok(session, uid) ||
                                session->destroyed) {
                        session_put(session);
                        continue;
@@ -3645,7 +3810,7 @@ int cmd_data_pending(struct ltt_session *session)
        struct ltt_kernel_session *ksess = session->kernel_session;
        struct ltt_ust_session *usess = session->ust_session;
 
-       assert(session);
+       LTTNG_ASSERT(session);
 
        DBG("Data pending for session %s", session->name);
 
@@ -3706,13 +3871,13 @@ error:
  * Return LTTNG_OK on success or else a LTTNG_ERR code.
  */
 int cmd_snapshot_add_output(struct ltt_session *session,
-               struct lttng_snapshot_output *output, uint32_t *id)
+               const struct lttng_snapshot_output *output, uint32_t *id)
 {
        int ret;
        struct snapshot_output *new_output;
 
-       assert(session);
-       assert(output);
+       LTTNG_ASSERT(session);
+       LTTNG_ASSERT(output);
 
        DBG("Cmd snapshot add output for session %s", session->name);
 
@@ -3774,13 +3939,13 @@ error:
  * Return LTTNG_OK on success or else a LTTNG_ERR code.
  */
 int cmd_snapshot_del_output(struct ltt_session *session,
-               struct lttng_snapshot_output *output)
+               const struct lttng_snapshot_output *output)
 {
        int ret;
        struct snapshot_output *sout = NULL;
 
-       assert(session);
-       assert(output);
+       LTTNG_ASSERT(session);
+       LTTNG_ASSERT(output);
 
        rcu_read_lock();
 
@@ -3831,8 +3996,8 @@ ssize_t cmd_snapshot_list_outputs(struct ltt_session *session,
        struct lttng_ht_iter iter;
        struct snapshot_output *output;
 
-       assert(session);
-       assert(outputs);
+       LTTNG_ASSERT(session);
+       LTTNG_ASSERT(outputs);
 
        DBG("Cmd snapshot list outputs for session %s", session->name);
 
@@ -3860,7 +4025,7 @@ ssize_t cmd_snapshot_list_outputs(struct ltt_session *session,
        rcu_read_lock();
        cds_lfht_for_each_entry(session->snapshot.output_ht->ht, &iter.iter,
                        output, node.node) {
-               assert(output->consumer);
+               LTTNG_ASSERT(output->consumer);
                list[idx].id = output->id;
                list[idx].max_size = output->max_size;
                if (lttng_strncpy(list[idx].name, output->name,
@@ -3916,7 +4081,7 @@ int check_regenerate_metadata_support(struct ltt_session *session)
 {
        int ret;
 
-       assert(session);
+       LTTNG_ASSERT(session);
 
        if (session->live_timer != 0) {
                ret = LTTNG_ERR_LIVE_SESSION;
@@ -3934,7 +4099,7 @@ int check_regenerate_metadata_support(struct ltt_session *session)
                        ret = LTTNG_ERR_PER_PID_SESSION;
                        goto end;
                default:
-                       assert(0);
+                       abort();
                        ret = LTTNG_ERR_UNK;
                        goto end;
                }
@@ -4050,182 +4215,600 @@ end:
  * then regenerate the metadata. Live and per-pid sessions are not
  * supported and return an error.
  *
- * Return 0 on success or else a LTTNG_ERR code.
+ * Return LTTNG_OK on success or else a LTTNG_ERR code.
  */
 int cmd_regenerate_metadata(struct ltt_session *session)
 {
        int ret;
 
-       assert(session);
+       LTTNG_ASSERT(session);
 
        ret = check_regenerate_metadata_support(session);
        if (ret) {
                goto end;
        }
 
-       if (session->kernel_session) {
-               ret = kernctl_session_regenerate_metadata(
-                               session->kernel_session->fd);
-               if (ret < 0) {
-                       ERR("Failed to regenerate the kernel metadata");
-                       goto end;
-               }
+       if (session->kernel_session) {
+               ret = kernctl_session_regenerate_metadata(
+                               session->kernel_session->fd);
+               if (ret < 0) {
+                       ERR("Failed to regenerate the kernel metadata");
+                       goto end;
+               }
+       }
+
+       if (session->ust_session) {
+               ret = ust_regenerate_metadata(session->ust_session);
+               if (ret < 0) {
+                       ERR("Failed to regenerate the UST metadata");
+                       goto end;
+               }
+       }
+       DBG("Cmd metadata regenerate for session %s", session->name);
+       ret = LTTNG_OK;
+
+end:
+       return ret;
+}
+
+/*
+ * Command LTTNG_REGENERATE_STATEDUMP from the lttng-ctl library.
+ *
+ * Ask the tracer to regenerate a new statedump.
+ *
+ * Return LTTNG_OK on success or else a LTTNG_ERR code.
+ */
+int cmd_regenerate_statedump(struct ltt_session *session)
+{
+       int ret;
+
+       LTTNG_ASSERT(session);
+
+       if (!session->active) {
+               ret = LTTNG_ERR_SESSION_NOT_STARTED;
+               goto end;
+       }
+
+       if (session->kernel_session) {
+               ret = kernctl_session_regenerate_statedump(
+                               session->kernel_session->fd);
+               /*
+                * Currently, the statedump in kernel can only fail if out
+                * of memory.
+                */
+               if (ret < 0) {
+                       if (ret == -ENOMEM) {
+                               ret = LTTNG_ERR_REGEN_STATEDUMP_NOMEM;
+                       } else {
+                               ret = LTTNG_ERR_REGEN_STATEDUMP_FAIL;
+                       }
+                       ERR("Failed to regenerate the kernel statedump");
+                       goto end;
+               }
+       }
+
+       if (session->ust_session) {
+               ret = ust_app_regenerate_statedump_all(session->ust_session);
+               /*
+                * Currently, the statedump in UST always returns 0.
+                */
+               if (ret < 0) {
+                       ret = LTTNG_ERR_REGEN_STATEDUMP_FAIL;
+                       ERR("Failed to regenerate the UST statedump");
+                       goto end;
+               }
+       }
+       DBG("Cmd regenerate statedump for session %s", session->name);
+       ret = LTTNG_OK;
+
+end:
+       return ret;
+}
+
+static
+enum lttng_error_code synchronize_tracer_notifier_register(
+               struct notification_thread_handle *notification_thread,
+               struct lttng_trigger *trigger, const struct lttng_credentials *cmd_creds)
+{
+       enum lttng_error_code ret_code;
+       const struct lttng_condition *condition =
+                       lttng_trigger_get_const_condition(trigger);
+       const char *trigger_name;
+       uid_t trigger_owner;
+       enum lttng_trigger_status trigger_status;
+       const enum lttng_domain_type trigger_domain =
+                       lttng_trigger_get_underlying_domain_type_restriction(
+                                       trigger);
+
+       trigger_status = lttng_trigger_get_owner_uid(trigger, &trigger_owner);
+       LTTNG_ASSERT(trigger_status == LTTNG_TRIGGER_STATUS_OK);
+
+       LTTNG_ASSERT(condition);
+       LTTNG_ASSERT(lttng_condition_get_type(condition) ==
+                       LTTNG_CONDITION_TYPE_EVENT_RULE_MATCHES);
+
+       trigger_status = lttng_trigger_get_name(trigger, &trigger_name);
+       trigger_name = trigger_status == LTTNG_TRIGGER_STATUS_OK ?
+                       trigger_name : "(anonymous)";
+
+       session_lock_list();
+       switch (trigger_domain) {
+       case LTTNG_DOMAIN_KERNEL:
+       {
+               ret_code = kernel_register_event_notifier(trigger, cmd_creds);
+               if (ret_code != LTTNG_OK) {
+                       enum lttng_error_code notif_thread_unregister_ret;
+
+                       notif_thread_unregister_ret =
+                                       notification_thread_command_unregister_trigger(
+                                               notification_thread, trigger);
+
+                       if (notif_thread_unregister_ret != LTTNG_OK) {
+                               /* Return the original error code. */
+                               ERR("Failed to unregister trigger from notification thread during error recovery: trigger name = '%s', trigger owner uid = %d, error code = %d",
+                                               trigger_name,
+                                               (int) trigger_owner,
+                                               ret_code);
+                       }
+               }
+               break;
+       }
+       case LTTNG_DOMAIN_UST:
+               ust_app_global_update_all_event_notifier_rules();
+               break;
+       case LTTNG_DOMAIN_JUL:
+       case LTTNG_DOMAIN_LOG4J:
+       case LTTNG_DOMAIN_PYTHON:
+       {
+               /* Agent domains. */
+               struct agent *agt = agent_find_by_event_notifier_domain(
+                               trigger_domain);
+
+               if (!agt) {
+                       agt = agent_create(trigger_domain);
+                       if (!agt) {
+                               ret_code = LTTNG_ERR_NOMEM;
+                               goto end_unlock_session_list;
+                       }
+
+                       agent_add(agt, the_trigger_agents_ht_by_domain);
+               }
+
+               ret_code = trigger_agent_enable(trigger, agt);
+               if (ret_code != LTTNG_OK) {
+                       goto end_unlock_session_list;
+               }
+
+               break;
+       }
+       case LTTNG_DOMAIN_NONE:
+       default:
+               abort();
+       }
+
+       ret_code = LTTNG_OK;
+end_unlock_session_list:
+       session_unlock_list();
+       return ret_code;
+}
+
+enum lttng_error_code cmd_register_trigger(const struct lttng_credentials *cmd_creds,
+               struct lttng_trigger *trigger,
+               bool is_trigger_anonymous,
+               struct notification_thread_handle *notification_thread,
+               struct lttng_trigger **return_trigger)
+{
+       enum lttng_error_code ret_code;
+       const char *trigger_name;
+       uid_t trigger_owner;
+       enum lttng_trigger_status trigger_status;
+
+       trigger_status = lttng_trigger_get_name(trigger, &trigger_name);
+       trigger_name = trigger_status == LTTNG_TRIGGER_STATUS_OK ?
+                       trigger_name : "(anonymous)";
+
+       trigger_status = lttng_trigger_get_owner_uid(
+               trigger, &trigger_owner);
+       LTTNG_ASSERT(trigger_status == LTTNG_TRIGGER_STATUS_OK);
+
+       DBG("Running register trigger command: trigger name = '%s', trigger owner uid = %d, command creds uid = %d",
+                       trigger_name, (int) trigger_owner,
+                       (int) lttng_credentials_get_uid(cmd_creds));
+
+       /*
+        * Validate the trigger credentials against the command credentials.
+        * Only the root user can register a trigger with non-matching
+        * credentials.
+        */
+       if (!lttng_credentials_is_equal_uid(
+                       lttng_trigger_get_credentials(trigger),
+                       cmd_creds)) {
+               if (lttng_credentials_get_uid(cmd_creds) != 0) {
+                       ERR("Trigger credentials do not match the command credentials: trigger name = '%s', trigger owner uid = %d, command creds uid = %d",
+                                       trigger_name, (int) trigger_owner,
+                                       (int) lttng_credentials_get_uid(cmd_creds));
+                       ret_code = LTTNG_ERR_INVALID_TRIGGER;
+                       goto end;
+               }
+       }
+
+       /*
+        * The bytecode generation also serves as a validation step for the
+        * bytecode expressions.
+        */
+       ret_code = lttng_trigger_generate_bytecode(trigger, cmd_creds);
+       if (ret_code != LTTNG_OK) {
+               ERR("Failed to generate bytecode of trigger: trigger name = '%s', trigger owner uid = %d, error code = %d",
+                               trigger_name, (int) trigger_owner, ret_code);
+               goto end;
+       }
+
+       /*
+        * A reference to the trigger is acquired by the notification thread.
+        * It is safe to return the same trigger to the caller since it the
+        * other user holds a reference.
+        *
+        * The trigger is modified during the execution of the
+        * "register trigger" command. However, by the time the command returns,
+        * it is safe to use without any locking as its properties are
+        * immutable.
+        */
+       ret_code = notification_thread_command_register_trigger(
+                       notification_thread, trigger, is_trigger_anonymous);
+       if (ret_code != LTTNG_OK) {
+               DBG("Failed to register trigger to notification thread: trigger name = '%s', trigger owner uid = %d, error code = %d",
+                               trigger_name, (int) trigger_owner, ret_code);
+               goto end;
        }
 
-       if (session->ust_session) {
-               ret = ust_regenerate_metadata(session->ust_session);
-               if (ret < 0) {
-                       ERR("Failed to regenerate the UST metadata");
+       trigger_status = lttng_trigger_get_name(trigger, &trigger_name);
+       trigger_name = trigger_status == LTTNG_TRIGGER_STATUS_OK ?
+                       trigger_name : "(anonymous)";
+
+       /*
+        * Synchronize tracers if the trigger adds an event notifier.
+        */
+       if (lttng_trigger_needs_tracer_notifier(trigger)) {
+               ret_code = synchronize_tracer_notifier_register(notification_thread,
+                               trigger, cmd_creds);
+               if (ret_code != LTTNG_OK) {
+                       ERR("Error registering tracer notifier: %s",
+                                       lttng_strerror(-ret_code));
                        goto end;
                }
        }
-       DBG("Cmd metadata regenerate for session %s", session->name);
-       ret = LTTNG_OK;
 
+       /*
+        * Return an updated trigger to the client.
+        *
+        * Since a modified version of the same trigger is returned, acquire a
+        * reference to the trigger so the caller doesn't have to care if those
+        * are distinct instances or not.
+        */
+       if (ret_code == LTTNG_OK) {
+               lttng_trigger_get(trigger);
+               *return_trigger = trigger;
+               /* Ownership of trigger was transferred to caller. */
+               trigger = NULL;
+       }
 end:
-       return ret;
+       return ret_code;
 }
 
-/*
- * Command LTTNG_REGENERATE_STATEDUMP from the lttng-ctl library.
- *
- * Ask the tracer to regenerate a new statedump.
- *
- * Return 0 on success or else a LTTNG_ERR code.
- */
-int cmd_regenerate_statedump(struct ltt_session *session)
+static
+enum lttng_error_code synchronize_tracer_notifier_unregister(
+               const struct lttng_trigger *trigger)
 {
-       int ret;
+       enum lttng_error_code ret_code;
+       const struct lttng_condition *condition =
+                       lttng_trigger_get_const_condition(trigger);
+       const enum lttng_domain_type trigger_domain =
+                       lttng_trigger_get_underlying_domain_type_restriction(
+                                       trigger);
 
-       assert(session);
+       LTTNG_ASSERT(condition);
+       LTTNG_ASSERT(lttng_condition_get_type(condition) ==
+                       LTTNG_CONDITION_TYPE_EVENT_RULE_MATCHES);
 
-       if (!session->active) {
-               ret = LTTNG_ERR_SESSION_NOT_STARTED;
-               goto end;
-       }
+       session_lock_list();
+       switch (trigger_domain) {
+       case LTTNG_DOMAIN_KERNEL:
+               ret_code = kernel_unregister_event_notifier(trigger);
+               if (ret_code != LTTNG_OK) {
+                       goto end_unlock_session_list;
+               }
+
+               break;
+       case LTTNG_DOMAIN_UST:
+               ust_app_global_update_all_event_notifier_rules();
+               break;
+       case LTTNG_DOMAIN_JUL:
+       case LTTNG_DOMAIN_LOG4J:
+       case LTTNG_DOMAIN_PYTHON:
+       {
+               /* Agent domains. */
+               struct agent *agt = agent_find_by_event_notifier_domain(
+                               trigger_domain);
 
-       if (session->kernel_session) {
-               ret = kernctl_session_regenerate_statedump(
-                               session->kernel_session->fd);
                /*
-                * Currently, the statedump in kernel can only fail if out
-                * of memory.
+                * This trigger was never registered in the first place. Calling
+                * this function under those circumstances is an internal error.
                 */
-               if (ret < 0) {
-                       if (ret == -ENOMEM) {
-                               ret = LTTNG_ERR_REGEN_STATEDUMP_NOMEM;
-                       } else {
-                               ret = LTTNG_ERR_REGEN_STATEDUMP_FAIL;
-                       }
-                       ERR("Failed to regenerate the kernel statedump");
+               LTTNG_ASSERT(agt);
+               ret_code = trigger_agent_disable(trigger, agt);
+               if (ret_code != LTTNG_OK) {
+                       goto end_unlock_session_list;
+               }
+
+               break;
+       }
+       case LTTNG_DOMAIN_NONE:
+       default:
+               abort();
+       }
+
+       ret_code = LTTNG_OK;
+
+end_unlock_session_list:
+       session_unlock_list();
+       return ret_code;
+}
+
+enum lttng_error_code cmd_unregister_trigger(const struct lttng_credentials *cmd_creds,
+               const struct lttng_trigger *trigger,
+               struct notification_thread_handle *notification_thread)
+{
+       enum lttng_error_code ret_code;
+       const char *trigger_name;
+       uid_t trigger_owner;
+       enum lttng_trigger_status trigger_status;
+       struct lttng_trigger *sessiond_trigger = NULL;
+
+       trigger_status = lttng_trigger_get_name(trigger, &trigger_name);
+       trigger_name = trigger_status == LTTNG_TRIGGER_STATUS_OK ? trigger_name : "(anonymous)";
+       trigger_status = lttng_trigger_get_owner_uid(trigger, &trigger_owner);
+       LTTNG_ASSERT(trigger_status == LTTNG_TRIGGER_STATUS_OK);
+
+       DBG("Running unregister trigger command: trigger name = '%s', trigger owner uid = %d, command creds uid = %d",
+                       trigger_name, (int) trigger_owner,
+                       (int) lttng_credentials_get_uid(cmd_creds));
+
+       /*
+        * Validate the trigger credentials against the command credentials.
+        * Only the root user can unregister a trigger with non-matching
+        * credentials.
+        */
+       if (!lttng_credentials_is_equal_uid(
+                       lttng_trigger_get_credentials(trigger),
+                       cmd_creds)) {
+               if (lttng_credentials_get_uid(cmd_creds) != 0) {
+                       ERR("Trigger credentials do not match the command credentials: trigger name = '%s', trigger owner uid = %d, command creds uid = %d",
+                                       trigger_name, (int) trigger_owner,
+                                       (int) lttng_credentials_get_uid(cmd_creds));
+                       ret_code = LTTNG_ERR_INVALID_TRIGGER;
                        goto end;
                }
        }
 
-       if (session->ust_session) {
-               ret = ust_app_regenerate_statedump_all(session->ust_session);
-               /*
-                * Currently, the statedump in UST always returns 0.
-                */
-               if (ret < 0) {
-                       ret = LTTNG_ERR_REGEN_STATEDUMP_FAIL;
-                       ERR("Failed to regenerate the UST statedump");
+       /* Fetch the sessiond side trigger object. */
+       ret_code = notification_thread_command_get_trigger(
+                       notification_thread, trigger, &sessiond_trigger);
+       if (ret_code != LTTNG_OK) {
+               DBG("Failed to get trigger from notification thread during unregister: trigger name = '%s', trigger owner uid = %d, error code = %d",
+                               trigger_name, (int) trigger_owner, ret_code);
+               goto end;
+       }
+
+       LTTNG_ASSERT(sessiond_trigger);
+
+       /*
+        * From this point on, no matter what, consider the trigger
+        * unregistered.
+        *
+        * We set the unregistered state of the sessiond side trigger object in
+        * the client thread since we want to minimize the possibility of the
+        * notification thread being stalled due to a long execution of an
+        * action that required the trigger lock.
+        */
+       lttng_trigger_set_as_unregistered(sessiond_trigger);
+
+       ret_code = notification_thread_command_unregister_trigger(notification_thread,
+                                                                 trigger);
+       if (ret_code != LTTNG_OK) {
+               DBG("Failed to unregister trigger from notification thread: trigger name = '%s', trigger owner uid = %d, error code = %d",
+                               trigger_name, (int) trigger_owner, ret_code);
+               goto end;
+       }
+
+       /*
+        * Synchronize tracers if the trigger removes an event notifier.
+        * Do this even if the trigger unregistration failed to at least stop
+        * the tracers from producing notifications associated with this
+        * event notifier.
+        */
+       if (lttng_trigger_needs_tracer_notifier(trigger)) {
+               ret_code = synchronize_tracer_notifier_unregister(trigger);
+               if (ret_code != LTTNG_OK) {
+                       ERR("Error unregistering trigger to tracer.");
                        goto end;
                }
+
        }
-       DBG("Cmd regenerate statedump for session %s", session->name);
-       ret = LTTNG_OK;
 
 end:
-       return ret;
+       lttng_trigger_put(sessiond_trigger);
+       return ret_code;
 }
 
-int cmd_register_trigger(struct command_ctx *cmd_ctx, int sock,
-               struct notification_thread_handle *notification_thread)
+enum lttng_error_code cmd_list_triggers(struct command_ctx *cmd_ctx,
+               struct notification_thread_handle *notification_thread,
+               struct lttng_triggers **return_triggers)
 {
        int ret;
-       size_t trigger_len;
-       ssize_t sock_recv_len;
-       struct lttng_trigger *trigger = NULL;
-       struct lttng_buffer_view view;
-       struct lttng_dynamic_buffer trigger_buffer;
-
-       lttng_dynamic_buffer_init(&trigger_buffer);
-       trigger_len = (size_t) cmd_ctx->lsm->u.trigger.length;
-       ret = lttng_dynamic_buffer_set_size(&trigger_buffer, trigger_len);
-       if (ret) {
-               ret = LTTNG_ERR_NOMEM;
-               goto end;
-       }
+       enum lttng_error_code ret_code;
+       struct lttng_triggers *triggers = NULL;
 
-       sock_recv_len = lttcomm_recv_unix_sock(sock, trigger_buffer.data,
-                       trigger_len);
-       if (sock_recv_len < 0 || sock_recv_len != trigger_len) {
-               ERR("Failed to receive \"register trigger\" command payload");
-               /* TODO: should this be a new error enum ? */
-               ret = LTTNG_ERR_INVALID_TRIGGER;
+       /* Get the set of triggers from the notification thread. */
+       ret_code = notification_thread_command_list_triggers(
+                       notification_thread, cmd_ctx->creds.uid, &triggers);
+       if (ret_code != LTTNG_OK) {
                goto end;
        }
 
-       view = lttng_buffer_view_from_dynamic_buffer(&trigger_buffer, 0, -1);
-       if (lttng_trigger_create_from_buffer(&view, &trigger) !=
-                       trigger_len) {
-               ERR("Invalid trigger payload received in \"register trigger\" command");
-               ret = LTTNG_ERR_INVALID_TRIGGER;
+       ret = lttng_triggers_remove_hidden_triggers(triggers);
+       if (ret) {
+               ret_code = LTTNG_ERR_UNK;
                goto end;
        }
 
-       ret = notification_thread_command_register_trigger(notification_thread,
-                       trigger);
-       /* Ownership of trigger was transferred. */
-       trigger = NULL;
+       *return_triggers = triggers;
+       triggers = NULL;
+       ret_code = LTTNG_OK;
 end:
-       lttng_trigger_destroy(trigger);
-       lttng_dynamic_buffer_reset(&trigger_buffer);
-       return ret;
+       lttng_triggers_destroy(triggers);
+       return ret_code;
 }
 
-int cmd_unregister_trigger(struct command_ctx *cmd_ctx, int sock,
+enum lttng_error_code cmd_execute_error_query(const struct lttng_credentials *cmd_creds,
+               const struct lttng_error_query *query,
+               struct lttng_error_query_results **_results,
                struct notification_thread_handle *notification_thread)
 {
-       int ret;
-       size_t trigger_len;
-       ssize_t sock_recv_len;
-       struct lttng_trigger *trigger = NULL;
-       struct lttng_buffer_view view;
-       struct lttng_dynamic_buffer trigger_buffer;
-
-       lttng_dynamic_buffer_init(&trigger_buffer);
-       trigger_len = (size_t) cmd_ctx->lsm->u.trigger.length;
-       ret = lttng_dynamic_buffer_set_size(&trigger_buffer, trigger_len);
-       if (ret) {
-               ret = LTTNG_ERR_NOMEM;
-               goto end;
+       enum lttng_error_code ret_code;
+       const struct lttng_trigger *query_target_trigger;
+       const struct lttng_action *query_target_action = NULL;
+       struct lttng_trigger *matching_trigger = NULL;
+       const char *trigger_name;
+       uid_t trigger_owner;
+       enum lttng_trigger_status trigger_status;
+       struct lttng_error_query_results *results = NULL;
+
+       switch (lttng_error_query_get_target_type(query)) {
+       case LTTNG_ERROR_QUERY_TARGET_TYPE_TRIGGER:
+               query_target_trigger = lttng_error_query_trigger_borrow_target(query);
+               break;
+       case LTTNG_ERROR_QUERY_TARGET_TYPE_CONDITION:
+               query_target_trigger =
+                               lttng_error_query_condition_borrow_target(query);
+               break;
+       case LTTNG_ERROR_QUERY_TARGET_TYPE_ACTION:
+               query_target_trigger = lttng_error_query_action_borrow_trigger_target(
+                               query);
+               break;
+       default:
+               abort();
        }
 
-       sock_recv_len = lttcomm_recv_unix_sock(sock, trigger_buffer.data,
-                       trigger_len);
-       if (sock_recv_len < 0 || sock_recv_len != trigger_len) {
-               ERR("Failed to receive \"unregister trigger\" command payload");
-               /* TODO: should this be a new error enum ? */
-               ret = LTTNG_ERR_INVALID_TRIGGER;
+       LTTNG_ASSERT(query_target_trigger);
+
+       ret_code = notification_thread_command_get_trigger(notification_thread,
+                       query_target_trigger, &matching_trigger);
+       if (ret_code != LTTNG_OK) {
                goto end;
        }
 
-       view = lttng_buffer_view_from_dynamic_buffer(&trigger_buffer, 0, -1);
-       if (lttng_trigger_create_from_buffer(&view, &trigger) !=
-                       trigger_len) {
-               ERR("Invalid trigger payload received in \"unregister trigger\" command");
-               ret = LTTNG_ERR_INVALID_TRIGGER;
+       /* No longer needed. */
+       query_target_trigger = NULL;
+
+       if (lttng_error_query_get_target_type(query) ==
+                       LTTNG_ERROR_QUERY_TARGET_TYPE_ACTION) {
+               /* Get the sessiond-side version of the target action. */
+               query_target_action =
+                               lttng_error_query_action_borrow_action_target(
+                                               query, matching_trigger);
+       }
+
+       trigger_status = lttng_trigger_get_name(matching_trigger, &trigger_name);
+       trigger_name = trigger_status == LTTNG_TRIGGER_STATUS_OK ?
+                       trigger_name : "(anonymous)";
+       trigger_status = lttng_trigger_get_owner_uid(matching_trigger,
+                       &trigger_owner);
+       LTTNG_ASSERT(trigger_status == LTTNG_TRIGGER_STATUS_OK);
+
+       results = lttng_error_query_results_create();
+       if (!results) {
+               ret_code = LTTNG_ERR_NOMEM;
                goto end;
        }
 
-       ret = notification_thread_command_unregister_trigger(notification_thread,
-                       trigger);
+       DBG("Running \"execute error query\" command: trigger name = '%s', trigger owner uid = %d, command creds uid = %d",
+                       trigger_name, (int) trigger_owner,
+                       (int) lttng_credentials_get_uid(cmd_creds));
+
+       /*
+        * Validate the trigger credentials against the command credentials.
+        * Only the root user can target a trigger with non-matching
+        * credentials.
+        */
+       if (!lttng_credentials_is_equal_uid(
+                       lttng_trigger_get_credentials(matching_trigger),
+                       cmd_creds)) {
+               if (lttng_credentials_get_uid(cmd_creds) != 0) {
+                       ERR("Trigger credentials do not match the command credentials: trigger name = '%s', trigger owner uid = %d, command creds uid = %d",
+                                       trigger_name, (int) trigger_owner,
+                                       (int) lttng_credentials_get_uid(cmd_creds));
+                       ret_code = LTTNG_ERR_INVALID_TRIGGER;
+                       goto end;
+               }
+       }
+
+       switch (lttng_error_query_get_target_type(query)) {
+       case LTTNG_ERROR_QUERY_TARGET_TYPE_TRIGGER:
+               trigger_status = lttng_trigger_add_error_results(
+                               matching_trigger, results);
+
+               switch (trigger_status) {
+               case LTTNG_TRIGGER_STATUS_OK:
+                       break;
+               default:
+                       ret_code = LTTNG_ERR_UNK;
+                       goto end;
+               }
+
+               break;
+       case LTTNG_ERROR_QUERY_TARGET_TYPE_CONDITION:
+       {
+               trigger_status = lttng_trigger_condition_add_error_results(
+                               matching_trigger, results);
+
+               switch (trigger_status) {
+               case LTTNG_TRIGGER_STATUS_OK:
+                       break;
+               default:
+                       ret_code = LTTNG_ERR_UNK;
+                       goto end;
+               }
+
+               break;
+       }
+       case LTTNG_ERROR_QUERY_TARGET_TYPE_ACTION:
+       {
+               const enum lttng_action_status action_status =
+                               lttng_action_add_error_query_results(
+                                               query_target_action, results);
+
+               switch (action_status) {
+               case LTTNG_ACTION_STATUS_OK:
+                       break;
+               default:
+                       ret_code = LTTNG_ERR_UNK;
+                       goto end;
+               }
+
+               break;
+       }
+       default:
+               abort();
+               break;
+       }
+
+       *_results = results;
+       results = NULL;
+       ret_code = LTTNG_OK;
 end:
-       lttng_trigger_destroy(trigger);
-       lttng_dynamic_buffer_reset(&trigger_buffer);
-       return ret;
+       lttng_trigger_put(matching_trigger);
+       lttng_error_query_results_destroy(results);
+       return ret_code;
 }
 
 /*
@@ -4244,8 +4827,8 @@ static enum lttng_error_code set_relayd_for_snapshot(
        LTTNG_OPTIONAL(uint64_t) current_chunk_id = {};
        const char *base_path;
 
-       assert(output);
-       assert(session);
+       LTTNG_ASSERT(output);
+       LTTNG_ASSERT(session);
 
        DBG2("Set relayd object from snapshot output");
 
@@ -4320,9 +4903,9 @@ static enum lttng_error_code record_kernel_snapshot(
 {
        enum lttng_error_code status;
 
-       assert(ksess);
-       assert(output);
-       assert(session);
+       LTTNG_ASSERT(ksess);
+       LTTNG_ASSERT(output);
+       LTTNG_ASSERT(session);
 
        status = kernel_snapshot_record(
                        ksess, output, wait, nb_packets_per_stream);
@@ -4341,9 +4924,9 @@ static enum lttng_error_code record_ust_snapshot(struct ltt_ust_session *usess,
 {
        enum lttng_error_code status;
 
-       assert(usess);
-       assert(output);
-       assert(session);
+       LTTNG_ASSERT(usess);
+       LTTNG_ASSERT(output);
+       LTTNG_ASSERT(session);
 
        status = ust_app_snapshot_record(
                        usess, output, wait, nb_packets_per_stream);
@@ -4431,7 +5014,7 @@ int64_t get_session_nb_packets_per_stream(const struct ltt_session *session,
                }
                cur_nb_packets++;
        }
-       if (!cur_nb_packets) {
+       if (!cur_nb_packets && size_left != max_size) {
                /* Not enough room to grab one packet of each stream, error. */
                return -1;
        }
@@ -4476,6 +5059,13 @@ enum lttng_error_code snapshot_record(struct ltt_session *session,
                                session->kernel_session->consumer;
                snapshot_kernel_consumer_output =
                                consumer_copy_output(snapshot_output->consumer);
+               strcpy(snapshot_kernel_consumer_output->chunk_path,
+                       snapshot_chunk_name);
+
+               /* Copy the original domain subdir. */
+               strcpy(snapshot_kernel_consumer_output->domain_subdir,
+                               original_kernel_consumer_output->domain_subdir);
+
                ret = consumer_copy_sockets(snapshot_kernel_consumer_output,
                                original_kernel_consumer_output);
                if (ret < 0) {
@@ -4496,6 +5086,13 @@ enum lttng_error_code snapshot_record(struct ltt_session *session,
                original_ust_consumer_output = session->ust_session->consumer;
                snapshot_ust_consumer_output =
                                consumer_copy_output(snapshot_output->consumer);
+               strcpy(snapshot_ust_consumer_output->chunk_path,
+                       snapshot_chunk_name);
+
+               /* Copy the original domain subdir. */
+               strcpy(snapshot_ust_consumer_output->domain_subdir,
+                               original_ust_consumer_output->domain_subdir);
+
                ret = consumer_copy_sockets(snapshot_ust_consumer_output,
                                original_ust_consumer_output);
                if (ret < 0) {
@@ -4525,7 +5122,7 @@ enum lttng_error_code snapshot_record(struct ltt_session *session,
                ret_code = LTTNG_ERR_CREATE_DIR_FAIL;
                goto error;
        }
-       assert(!session->current_trace_chunk);
+       LTTNG_ASSERT(!session->current_trace_chunk);
        ret = session_set_trace_chunk(session, snapshot_trace_chunk, NULL);
        lttng_trace_chunk_put(snapshot_trace_chunk);
        snapshot_trace_chunk = NULL;
@@ -4540,7 +5137,7 @@ enum lttng_error_code snapshot_record(struct ltt_session *session,
                        snapshot_output->max_size);
        if (nb_packets_per_stream < 0) {
                ret_code = LTTNG_ERR_MAX_SIZE_INVALID;
-               goto error;
+               goto error_close_trace_chunk;
        }
 
        if (session->kernel_session) {
@@ -4548,7 +5145,7 @@ enum lttng_error_code snapshot_record(struct ltt_session *session,
                                snapshot_kernel_consumer_output, session,
                                wait, nb_packets_per_stream);
                if (ret_code != LTTNG_OK) {
-                       goto error;
+                       goto error_close_trace_chunk;
                }
        }
 
@@ -4557,12 +5154,19 @@ enum lttng_error_code snapshot_record(struct ltt_session *session,
                                snapshot_ust_consumer_output, session,
                                wait, nb_packets_per_stream);
                if (ret_code != LTTNG_OK) {
-                       goto error;
+                       goto error_close_trace_chunk;
                }
        }
 
-       if (session_close_trace_chunk(
-                           session, session->current_trace_chunk, NULL)) {
+error_close_trace_chunk:
+       if (session_set_trace_chunk(session, NULL, &snapshot_trace_chunk)) {
+               ERR("Failed to release the current trace chunk of session \"%s\"",
+                               session->name);
+               ret_code = LTTNG_ERR_UNK;
+       }
+
+       if (session_close_trace_chunk(session, snapshot_trace_chunk,
+                       LTTNG_TRACE_CHUNK_COMMAND_TYPE_NO_OPERATION, NULL)) {
                /*
                 * Don't goto end; make sure the chunk is closed for the session
                 * to allow future snapshots.
@@ -4571,11 +5175,6 @@ enum lttng_error_code snapshot_record(struct ltt_session *session,
                                session->name);
                ret_code = LTTNG_ERR_CLOSE_TRACE_CHUNK_FAIL_CONSUMER;
        }
-       if (session_set_trace_chunk(session, NULL, NULL)) {
-               ERR("Failed to release the current trace chunk of session \"%s\"",
-                               session->name);
-               ret_code = LTTNG_ERR_UNK;
-       }
 error:
        if (original_ust_consumer_output) {
                session->ust_session->consumer = original_ust_consumer_output;
@@ -4598,7 +5197,7 @@ error:
  * Return LTTNG_OK on success or else a LTTNG_ERR code.
  */
 int cmd_snapshot_record(struct ltt_session *session,
-               struct lttng_snapshot_output *output, int wait)
+               const struct lttng_snapshot_output *output, int wait)
 {
        enum lttng_error_code cmd_ret = LTTNG_OK;
        int ret;
@@ -4606,8 +5205,8 @@ int cmd_snapshot_record(struct ltt_session *session,
        char datetime[16];
        struct snapshot_output *tmp_output = NULL;
 
-       assert(session);
-       assert(output);
+       LTTNG_ASSERT(session);
+       LTTNG_ASSERT(output);
 
        DBG("Cmd snapshot record for session %s", session->name);
 
@@ -4730,7 +5329,7 @@ int cmd_set_session_shm_path(struct ltt_session *session,
                const char *shm_path)
 {
        /* Safety net */
-       assert(session);
+       LTTNG_ASSERT(session);
 
        /*
         * Can only set shm path before session is started.
@@ -4743,7 +5342,7 @@ int cmd_set_session_shm_path(struct ltt_session *session,
                sizeof(session->shm_path));
        session->shm_path[sizeof(session->shm_path) - 1] = '\0';
 
-       return 0;
+       return LTTNG_OK;
 }
 
 /*
@@ -4756,7 +5355,8 @@ int cmd_set_session_shm_path(struct ltt_session *session,
  */
 int cmd_rotate_session(struct ltt_session *session,
                struct lttng_rotate_session_return *rotate_return,
-               bool quiet_rotation)
+               bool quiet_rotation,
+               enum lttng_trace_chunk_command_type command)
 {
        int ret;
        uint64_t ongoing_rotation_chunk_id;
@@ -4764,8 +5364,10 @@ int cmd_rotate_session(struct ltt_session *session,
        struct lttng_trace_chunk *chunk_being_archived = NULL;
        struct lttng_trace_chunk *new_trace_chunk = NULL;
        enum lttng_trace_chunk_status chunk_status;
+       bool failed_to_rotate = false;
+       enum lttng_error_code rotation_fail_code = LTTNG_OK;
 
-       assert(session);
+       LTTNG_ASSERT(session);
 
        if (!session->has_been_started) {
                cmd_ret = LTTNG_ERR_START_SESSION_ONCE;
@@ -4792,6 +5394,12 @@ int cmd_rotate_session(struct ltt_session *session,
                goto end;
        }
 
+       /* Unsupported feature in lttng-modules before 2.8 (lack of sequence number). */
+       if (session->kernel_session && !kernel_supports_ring_buffer_packet_sequence_number()) {
+               cmd_ret = LTTNG_ERR_ROTATION_NOT_AVAILABLE_KERNEL;
+               goto end;
+       }
+
        if (session->rotation_state == LTTNG_ROTATION_STATE_ONGOING) {
                DBG("Refusing to launch a rotation; a rotation is already in progress for session %s",
                                session->name);
@@ -4810,7 +5418,16 @@ int cmd_rotate_session(struct ltt_session *session,
                goto end;
        }
 
-       session->rotation_state = LTTNG_ROTATION_STATE_ONGOING;
+       /*
+        * After a stop followed by a clear, disallow following rotations a they would
+        * generate empty chunks.
+        */
+       if (session->cleared_after_last_stop) {
+               DBG("Session \"%s\" was already cleared after stop, refusing rotation",
+                               session->name);
+               cmd_ret = LTTNG_ERR_ROTATION_AFTER_STOP_CLEAR;
+               goto end;
+       }
 
        if (session->active) {
                new_trace_chunk = session_create_new_trace_chunk(session, NULL,
@@ -4819,9 +5436,15 @@ int cmd_rotate_session(struct ltt_session *session,
                        cmd_ret = LTTNG_ERR_CREATE_DIR_FAIL;
                        goto error;
                }
-        }
+       }
 
-        /* The current trace chunk becomes the chunk being archived. */
+       /*
+        * The current trace chunk becomes the chunk being archived.
+        *
+        * After this point, "chunk_being_archived" must absolutely
+        * be closed on the consumer(s), otherwise it will never be
+        * cleaned-up, which will result in a leak.
+        */
        ret = session_set_trace_chunk(session, new_trace_chunk,
                        &chunk_being_archived);
        if (ret) {
@@ -4829,34 +5452,53 @@ int cmd_rotate_session(struct ltt_session *session,
                goto error;
        }
 
-       assert(chunk_being_archived);
-       chunk_status = lttng_trace_chunk_get_id(chunk_being_archived,
-                       &ongoing_rotation_chunk_id);
-       assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
-
        if (session->kernel_session) {
                cmd_ret = kernel_rotate_session(session);
                if (cmd_ret != LTTNG_OK) {
-                       goto error;
+                       failed_to_rotate = true;
+                       rotation_fail_code = cmd_ret;
                }
        }
        if (session->ust_session) {
                cmd_ret = ust_app_rotate_session(session);
                if (cmd_ret != LTTNG_OK) {
+                       failed_to_rotate = true;
+                       rotation_fail_code = cmd_ret;
+               }
+       }
+
+       if (!session->active) {
+               session->rotated_after_last_stop = true;
+       }
+
+       if (!chunk_being_archived) {
+               DBG("Rotating session \"%s\" from a \"NULL\" trace chunk to a new trace chunk, skipping completion check",
+                               session->name);
+               if (failed_to_rotate) {
+                       cmd_ret = rotation_fail_code;
                        goto error;
                }
+               cmd_ret = LTTNG_OK;
+               goto end;
        }
 
+       session->rotation_state = LTTNG_ROTATION_STATE_ONGOING;
+       chunk_status = lttng_trace_chunk_get_id(chunk_being_archived,
+                       &ongoing_rotation_chunk_id);
+       LTTNG_ASSERT(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
+
        ret = session_close_trace_chunk(session, chunk_being_archived,
-                       quiet_rotation ?
-                                       NULL :
-                                       &((enum lttng_trace_chunk_command_type){
-                                                       LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED}));
+               command, session->last_chunk_path);
        if (ret) {
                cmd_ret = LTTNG_ERR_CLOSE_TRACE_CHUNK_FAIL_CONSUMER;
                goto error;
        }
 
+       if (failed_to_rotate) {
+               cmd_ret = rotation_fail_code;
+               goto error;
+       }
+
        session->quiet_rotation = quiet_rotation;
        ret = timer_session_rotation_pending_check_start(session,
                        DEFAULT_ROTATE_PENDING_TIMER);
@@ -4865,10 +5507,6 @@ int cmd_rotate_session(struct ltt_session *session,
                goto error;
        }
 
-       if (!session->active) {
-               session->rotated_after_last_stop = true;
-       }
-
        if (rotate_return) {
                rotate_return->rotation_id = ongoing_rotation_chunk_id;
        }
@@ -4877,8 +5515,8 @@ int cmd_rotate_session(struct ltt_session *session,
        chunk_being_archived = NULL;
        if (!quiet_rotation) {
                ret = notification_thread_command_session_rotation_ongoing(
-                               notification_thread_handle,
-                               session->name, session->uid, session->gid,
+                               the_notification_thread_handle, session->name,
+                               session->uid, session->gid,
                                ongoing_rotation_chunk_id);
                if (ret != LTTNG_OK) {
                        ERR("Failed to notify notification thread that a session rotation is ongoing for session %s",
@@ -4927,7 +5565,7 @@ int cmd_rotate_get_info(struct ltt_session *session,
                chunk_status = lttng_trace_chunk_get_id(
                                session->chunk_being_archived,
                                &chunk_id);
-               assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
+               LTTNG_ASSERT(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
 
                rotation_state = rotation_id == chunk_id ?
                                LTTNG_ROTATION_STATE_ONGOING :
@@ -4943,7 +5581,7 @@ int cmd_rotate_get_info(struct ltt_session *session,
 
        switch (rotation_state) {
        case LTTNG_ROTATION_STATE_NO_ROTATION:
-               DBG("Reporting that no rotation has occured within the lifetime of session \"%s\"",
+               DBG("Reporting that no rotation has occurred within the lifetime of session \"%s\"",
                                session->name);
                goto end;
        case LTTNG_ROTATION_STATE_EXPIRED:
@@ -4972,8 +5610,21 @@ int cmd_rotate_get_info(struct ltt_session *session,
                                        sizeof(info_return->location.local.absolute_path);
                        info_return->location_type =
                                        (int8_t) LTTNG_TRACE_ARCHIVE_LOCATION_TYPE_LOCAL;
+                       fmt_ret = asprintf(&chunk_path,
+                                       "%s/" DEFAULT_ARCHIVED_TRACE_CHUNKS_DIRECTORY "/%s",
+                                       session_get_base_path(session),
+                                       session->last_archived_chunk_name);
+                       if (fmt_ret == -1) {
+                               PERROR("Failed to format the path of the last archived trace chunk");
+                               info_return->status = LTTNG_ROTATION_STATUS_ERROR;
+                               cmd_ret = LTTNG_ERR_UNK;
+                               goto end;
+                       }
                        break;
                case CONSUMER_DST_NET:
+               {
+                       uint16_t ctrl_port, data_port;
+
                        current_tracing_path_reply =
                                        info_return->location.relay.relative_path;
                        current_tracing_path_reply_len =
@@ -4992,25 +5643,23 @@ int cmd_rotate_get_info(struct ltt_session *session,
                                goto end;
                        }
 
-                       session_get_net_consumer_ports(session,
-                                       &info_return->location.relay.ports.control,
-                                       &info_return->location.relay.ports.data);
+                       session_get_net_consumer_ports(session, &ctrl_port, &data_port);
+                       info_return->location.relay.ports.control = ctrl_port;
+                       info_return->location.relay.ports.data = data_port;
                        info_return->location_type =
                                        (int8_t) LTTNG_TRACE_ARCHIVE_LOCATION_TYPE_RELAY;
+                       chunk_path = strdup(session->last_chunk_path);
+                       if (!chunk_path) {
+                               ERR("Failed to allocate the path of the last archived trace chunk");
+                               info_return->status = LTTNG_ROTATION_STATUS_ERROR;
+                               cmd_ret = LTTNG_ERR_UNK;
+                               goto end;
+                       }
                        break;
+               }
                default:
                        abort();
                }
-               fmt_ret = asprintf(&chunk_path,
-                               "%s/" DEFAULT_ARCHIVED_TRACE_CHUNKS_DIRECTORY "/%s",
-                               session_get_base_path(session),
-                               session->last_archived_chunk_name);
-               if (fmt_ret == -1) {
-                       PERROR("Failed to format the path of the last archived trace chunk");
-                       info_return->status = LTTNG_ROTATION_STATUS_ERROR;
-                       cmd_ret = LTTNG_ERR_UNK;
-                       goto end;
-               }
 
                fmt_ret = lttng_strncpy(current_tracing_path_reply,
                                chunk_path, current_tracing_path_reply_len);
@@ -5046,7 +5695,7 @@ end:
  * 'activate' to false means deactivate the rotation schedule and validate that
  * 'new_value' has the same value as the currently active value.
  *
- * Return 0 on success or else a positive LTTNG_ERR code.
+ * Return LTTNG_OK on success or else a positive LTTNG_ERR code.
  */
 int cmd_rotation_set_schedule(struct ltt_session *session,
                bool activate, enum lttng_rotation_schedule_type schedule_type,
@@ -5056,7 +5705,7 @@ int cmd_rotation_set_schedule(struct ltt_session *session,
        int ret;
        uint64_t *parameter_value;
 
-       assert(session);
+       LTTNG_ASSERT(session);
 
        DBG("Cmd rotate set schedule session %s", session->name);
 
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