Fix: sessiond: no rotation performed from null chunk to new chunk
[lttng-tools.git] / src / bin / lttng-sessiond / cmd.c
index e0a8db9b2cc13a2b5c77407e0b14938fa565a587..5a122d8d3c8dcf7e7f361b34f69f46c4680c0d22 100644 (file)
@@ -21,6 +21,8 @@
 #include <inttypes.h>
 #include <urcu/list.h>
 #include <urcu/uatomic.h>
+#include <sys/stat.h>
+#include <stdio.h>
 
 #include <common/defaults.h>
 #include <common/common.h>
 #include <common/kernel-ctl/kernel-ctl.h>
 #include <common/dynamic-buffer.h>
 #include <common/buffer-view.h>
+#include <common/trace-chunk.h>
+#include <lttng/location-internal.h>
 #include <lttng/trigger/trigger-internal.h>
 #include <lttng/condition/condition.h>
 #include <lttng/action/action.h>
 #include <lttng/channel.h>
 #include <lttng/channel-internal.h>
 #include <lttng/rotate-internal.h>
+#include <lttng/location-internal.h>
+#include <lttng/session-internal.h>
+#include <lttng/userspace-probe-internal.h>
+#include <lttng/session-descriptor-internal.h>
 #include <common/string-utils/string-utils.h>
 
 #include "channel.h"
 #include "kernel-consumer.h"
 #include "lttng-sessiond.h"
 #include "utils.h"
-#include "syscall.h"
+#include "lttng-syscall.h"
 #include "agent.h"
 #include "buffer-registry.h"
 #include "notification-thread.h"
 #include "notification-thread-commands.h"
 #include "rotate.h"
 #include "rotation-thread.h"
-#include "sessiond-timer.h"
+#include "timer.h"
+#include "agent-thread.h"
 
 #include "cmd.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);
+
+/*
+ * Command completion handler that is used by the destroy command
+ * when a session that has a non-default shm_path is being destroyed.
+ *
+ * See comment in cmd_destroy_session() for the rationale.
+ */
+static struct destroy_completion_handler {
+       struct cmd_completion_handler handler;
+       char shm_path[member_sizeof(struct ltt_session, shm_path)];
+} destroy_completion_handler = {
+       .handler = {
+               .run = wait_on_path,
+               .data = destroy_completion_handler.shm_path
+       },
+       .shm_path = { 0 },
+};
+
+static struct cmd_completion_handler *current_completion_handler;
+
 /*
  * Used to keep a unique index for each relayd socket created where this value
  * is associated with streams on the consumer so it can match the right relayd
@@ -69,7 +112,7 @@ 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,
@@ -357,9 +400,13 @@ end:
        }
 }
 
-static void increment_extended_len(const char *filter_expression,
-               struct lttng_event_exclusion *exclusion, size_t *extended_len)
+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) {
@@ -369,14 +416,31 @@ static void increment_extended_len(const char *filter_expression,
        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 void append_extended_info(const char *filter_expression,
-               struct lttng_event_exclusion *exclusion, void **extended_at)
+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 lttcomm_event_extended_header extended_header;
+       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;
 
        if (filter_expression) {
                filter_len = strlen(filter_expression) + 1;
@@ -386,9 +450,21 @@ static void append_extended_info(const char *filter_expression,
                nb_exclusions = exclusion->count;
        }
 
+       if (probe_location) {
+               lttng_dynamic_buffer_init(&location_buffer);
+               ret = lttng_userspace_probe_location_serialize(probe_location,
+                               &location_buffer, NULL);
+               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));
@@ -407,6 +483,15 @@ static void append_extended_info(const char *filter_expression,
                memcpy(*extended_at, &exclusion->names, len);
                *extended_at += 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;
 }
 
 /*
@@ -420,7 +505,7 @@ static int list_lttng_agent_events(struct agent *agt,
        int i = 0, ret = 0;
        unsigned int nb_event = 0;
        struct agent_event *event;
-       struct lttng_event *tmp_events;
+       struct lttng_event *tmp_events = NULL;
        struct lttng_ht_iter iter;
        size_t extended_len = 0;
        void *extended_at;
@@ -448,8 +533,13 @@ static int list_lttng_agent_events(struct agent *agt,
         */
        rcu_read_lock();
        cds_lfht_for_each_entry(agt->events->ht, &iter.iter, event, node.node) {
-               increment_extended_len(event->filter_expression, NULL,
+               ret = increment_extended_len(event->filter_expression, NULL, NULL,
                                &extended_len);
+               if (ret) {
+                       DBG("Error computing the length of extended info message");
+                       ret = -LTTNG_ERR_FATAL;
+                       goto error;
+               }
        }
        rcu_read_unlock();
 
@@ -474,17 +564,25 @@ static int list_lttng_agent_events(struct agent *agt,
                i++;
 
                /* Append extended info */
-               append_extended_info(event->filter_expression, NULL,
+               ret = append_extended_info(event->filter_expression, NULL, NULL,
                                &extended_at);
+               if (ret) {
+                       DBG("Error appending extended info message");
+                       ret = -LTTNG_ERR_FATAL;
+                       goto error;
+               }
        }
-       rcu_read_unlock();
 
        *events = tmp_events;
        ret = nb_event;
-
-error:
        assert(nb_event == i);
+
+end:
+       rcu_read_unlock();
        return ret;
+error:
+       free(tmp_events);
+       goto end;
 }
 
 /*
@@ -533,8 +631,13 @@ static int list_lttng_ust_global_events(char *channel_name,
                        continue;
                }
 
-               increment_extended_len(uevent->filter_expression,
-                       uevent->exclusion, &extended_len);
+               ret = increment_extended_len(uevent->filter_expression,
+                       uevent->exclusion, NULL, &extended_len);
+               if (ret) {
+                       DBG("Error computing the length of extended info message");
+                       ret = -LTTNG_ERR_FATAL;
+                       goto end;
+               }
        }
        if (nb_event == 0) {
                /* All events are internal, skip. */
@@ -594,8 +697,13 @@ static int list_lttng_ust_global_events(char *channel_name,
                i++;
 
                /* Append extended info */
-               append_extended_info(uevent->filter_expression,
-                       uevent->exclusion, &extended_at);
+               ret = append_extended_info(uevent->filter_expression,
+                       uevent->exclusion, NULL, &extended_at);
+               if (ret) {
+                       DBG("Error appending extended info message");
+                       ret = -LTTNG_ERR_FATAL;
+                       goto end;
+               }
        }
 
        ret = nb_event;
@@ -637,14 +745,20 @@ static int list_lttng_kernel_events(char *channel_name,
 
        /* Compute required extended infos size */
        cds_list_for_each_entry(event, &kchan->events_list.head, list) {
-               increment_extended_len(event->filter_expression, NULL,
+               ret = increment_extended_len(event->filter_expression, NULL,
+                       event->userspace_probe_location,
                        &extended_len);
+               if (ret) {
+                       DBG("Error computing the length of extended info message");
+                       ret = -LTTNG_ERR_FATAL;
+                       goto error;
+               }
        }
 
        *total_size = nb_event * sizeof(struct lttng_event) + extended_len;
        *events = zmalloc(*total_size);
        if (*events == NULL) {
-               ret = LTTNG_ERR_FATAL;
+               ret = -LTTNG_ERR_FATAL;
                goto error;
        }
 
@@ -673,6 +787,9 @@ static int list_lttng_kernel_events(char *channel_name,
                        memcpy(&(*events)[i].attr.probe, &event->event->u.kprobe,
                                        sizeof(struct lttng_kernel_kprobe));
                        break;
+               case LTTNG_KERNEL_UPROBE:
+                       (*events)[i].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,
@@ -685,14 +802,21 @@ static int list_lttng_kernel_events(char *channel_name,
                        (*events)[i].type = LTTNG_EVENT_SYSCALL;
                        break;
                case LTTNG_KERNEL_ALL:
+                       /* fall-through. */
+               default:
                        assert(0);
                        break;
                }
                i++;
 
                /* Append extended info */
-               append_extended_info(event->filter_expression, NULL,
-                       &extended_at);
+               ret = append_extended_info(event->filter_expression, NULL,
+                       event->userspace_probe_location, &extended_at);
+               if (ret) {
+                       DBG("Error appending extended info message");
+                       ret = -LTTNG_ERR_FATAL;
+                       goto error;
+               }
        }
 
 end:
@@ -707,34 +831,47 @@ error:
  * Add URI so the consumer output object. Set the correct path depending on the
  * domain adding the default trace directory.
  */
-static int add_uri_to_consumer(struct consumer_output *consumer,
-               struct lttng_uri *uri, enum lttng_domain_type domain,
-               const char *session_name)
+static enum lttng_error_code add_uri_to_consumer(
+               const struct ltt_session *session,
+               struct consumer_output *consumer,
+               struct lttng_uri *uri, enum lttng_domain_type domain)
 {
-       int ret = LTTNG_OK;
-       const char *default_trace_dir;
+       int ret;
+       enum lttng_error_code ret_code = LTTNG_OK;
 
        assert(uri);
 
        if (consumer == NULL) {
                DBG("No consumer detected. Don't add URI. Stopping.");
-               ret = LTTNG_ERR_NO_CONSUMER;
+               ret_code = LTTNG_ERR_NO_CONSUMER;
                goto error;
        }
 
        switch (domain) {
        case LTTNG_DOMAIN_KERNEL:
-               default_trace_dir = DEFAULT_KERNEL_TRACE_DIR;
+               ret = lttng_strncpy(consumer->domain_subdir,
+                               DEFAULT_KERNEL_TRACE_DIR,
+                               sizeof(consumer->domain_subdir));
                break;
        case LTTNG_DOMAIN_UST:
-               default_trace_dir = DEFAULT_UST_TRACE_DIR;
+               ret = lttng_strncpy(consumer->domain_subdir,
+                               DEFAULT_UST_TRACE_DIR,
+                               sizeof(consumer->domain_subdir));
                break;
        default:
                /*
-                * This case is possible is we try to add the URI to the global tracing
-                * session consumer object which in this case there is no subdir.
+                * This case is possible is we try to add the URI to the global
+                * tracing session consumer object which in this case there is
+                * no subdir.
                 */
-               default_trace_dir = "";
+               memset(consumer->domain_subdir, 0,
+                               sizeof(consumer->domain_subdir));
+               ret = 0;
+       }
+       if (ret) {
+               ERR("Failed to initialize consumer output domain subdirectory");
+               ret_code = LTTNG_ERR_FATAL;
+               goto error;
        }
 
        switch (uri->dtype) {
@@ -747,67 +884,50 @@ static int add_uri_to_consumer(struct consumer_output *consumer,
                                consumer->dst.net.control_isset) ||
                                (uri->stype == LTTNG_STREAM_DATA &&
                                consumer->dst.net.data_isset)) {
-                               ret = LTTNG_ERR_URL_EXIST;
+                               ret_code = LTTNG_ERR_URL_EXIST;
                                goto error;
                        }
                } else {
-                       memset(&consumer->dst.net, 0, sizeof(consumer->dst.net));
+                       memset(&consumer->dst, 0, sizeof(consumer->dst));
                }
 
-               consumer->type = CONSUMER_DST_NET;
-
                /* Set URI into consumer output object */
-               ret = consumer_set_network_uri(consumer, uri);
+               ret = consumer_set_network_uri(session, consumer, uri);
                if (ret < 0) {
-                       ret = -ret;
+                       ret_code = -ret;
                        goto error;
                } else if (ret == 1) {
                        /*
                         * URI was the same in the consumer so we do not append the subdir
                         * again so to not duplicate output dir.
                         */
-                       ret = LTTNG_OK;
+                       ret_code = LTTNG_OK;
                        goto error;
                }
-
-               if (uri->stype == LTTNG_STREAM_CONTROL && strlen(uri->subdir) == 0) {
-                       ret = consumer_set_subdir(consumer, session_name);
-                       if (ret < 0) {
-                               ret = LTTNG_ERR_FATAL;
-                               goto error;
-                       }
-               }
-
-               if (uri->stype == LTTNG_STREAM_CONTROL) {
-                       /* On a new subdir, reappend the default trace dir. */
-                       strncat(consumer->subdir, default_trace_dir,
-                                       sizeof(consumer->subdir) - strlen(consumer->subdir) - 1);
-                       DBG3("Append domain trace name to subdir %s", consumer->subdir);
-               }
-
                break;
        case LTTNG_DST_PATH:
-               DBG2("Setting trace directory path from URI to %s", uri->dst.path);
-               memset(consumer->dst.session_root_path, 0,
+               if (*uri->dst.path != '/' || strstr(uri->dst.path, "../")) {
+                       ret_code = LTTNG_ERR_INVALID;
+                       goto error;
+               }
+               DBG2("Setting trace directory path from URI to %s",
+                               uri->dst.path);
+               memset(&consumer->dst, 0, sizeof(consumer->dst));
+
+               ret = lttng_strncpy(consumer->dst.session_root_path,
+                               uri->dst.path,
                                sizeof(consumer->dst.session_root_path));
-               /* Explicit length checks for strcpy and strcat. */
-               if (strlen(uri->dst.path) + strlen(default_trace_dir)
-                               >= sizeof(consumer->dst.session_root_path)) {
-                       ret = LTTNG_ERR_FATAL;
+               if (ret) {
+                       ret_code = LTTNG_ERR_FATAL;
                        goto error;
                }
-               strcpy(consumer->dst.session_root_path, uri->dst.path);
-               /* Append default trace dir */
-               strcat(consumer->dst.session_root_path, default_trace_dir);
-               /* Flag consumer as local. */
                consumer->type = CONSUMER_DST_LOCAL;
                break;
        }
 
-       ret = LTTNG_OK;
-
+       ret_code = LTTNG_OK;
 error:
-       return ret;
+       return ret_code;
 }
 
 /*
@@ -845,19 +965,20 @@ error:
  * Create a socket to the relayd using the URI.
  *
  * On success, the relayd_sock pointer is set to the created socket.
- * Else, it's stays untouched and a lttcomm error code is returned.
+ * Else, it remains untouched and an LTTng error code is returned.
  */
-static int create_connect_relayd(struct lttng_uri *uri,
+static enum lttng_error_code create_connect_relayd(struct lttng_uri *uri,
                struct lttcomm_relayd_sock **relayd_sock,
                struct consumer_output *consumer)
 {
        int ret;
+       enum lttng_error_code status = LTTNG_OK;
        struct lttcomm_relayd_sock *rsock;
 
        rsock = lttcomm_alloc_relayd_sock(uri, RELAYD_VERSION_COMM_MAJOR,
                        RELAYD_VERSION_COMM_MINOR);
        if (!rsock) {
-               ret = LTTNG_ERR_FATAL;
+               status = LTTNG_ERR_FATAL;
                goto error;
        }
 
@@ -871,7 +992,7 @@ static int create_connect_relayd(struct lttng_uri *uri,
        health_poll_exit();
        if (ret < 0) {
                ERR("Unable to reach lttng-relayd");
-               ret = LTTNG_ERR_RELAYD_CONNECT_FAIL;
+               status = LTTNG_ERR_RELAYD_CONNECT_FAIL;
                goto free_sock;
        }
 
@@ -882,10 +1003,11 @@ static int create_connect_relayd(struct lttng_uri *uri,
                /* Check relayd version */
                ret = relayd_version_check(rsock);
                if (ret == LTTNG_ERR_RELAYD_VERSION_FAIL) {
+                       status = LTTNG_ERR_RELAYD_VERSION_FAIL;
                        goto close_sock;
                } else if (ret < 0) {
                        ERR("Unable to reach lttng-relayd");
-                       ret = LTTNG_ERR_RELAYD_CONNECT_FAIL;
+                       status = LTTNG_ERR_RELAYD_CONNECT_FAIL;
                        goto close_sock;
                }
                consumer->relay_major_version = rsock->major;
@@ -895,13 +1017,13 @@ static int create_connect_relayd(struct lttng_uri *uri,
        } else {
                /* Command is not valid */
                ERR("Relayd invalid stream type: %d", uri->stype);
-               ret = LTTNG_ERR_INVALID;
+               status = LTTNG_ERR_INVALID;
                goto close_sock;
        }
 
        *relayd_sock = rsock;
 
-       return LTTNG_OK;
+       return status;
 
 close_sock:
        /* The returned value is not useful since we are on an error path. */
@@ -909,26 +1031,34 @@ close_sock:
 free_sock:
        free(rsock);
 error:
-       return ret;
+       return status;
 }
 
 /*
  * Connect to the relayd using URI and send the socket to the right consumer.
  *
  * The consumer socket lock must be held by the caller.
+ *
+ * Returns LTTNG_OK on success or an LTTng error code on failure.
  */
-static int send_consumer_relayd_socket(enum lttng_domain_type domain,
-               unsigned int session_id, struct lttng_uri *relayd_uri,
+static enum lttng_error_code send_consumer_relayd_socket(
+               unsigned int session_id,
+               struct lttng_uri *relayd_uri,
                struct consumer_output *consumer,
                struct consumer_socket *consumer_sock,
-               char *session_name, char *hostname, int session_live_timer)
+               const char *session_name, const char *hostname,
+               const char *base_path, int session_live_timer,
+               const uint64_t *current_chunk_id,
+               time_t session_creation_time,
+               bool session_name_contains_creation_time)
 {
        int ret;
        struct lttcomm_relayd_sock *rsock = NULL;
+       enum lttng_error_code status;
 
        /* Connect to relayd and make version check if uri is the control. */
-       ret = create_connect_relayd(relayd_uri, &rsock, consumer);
-       if (ret != LTTNG_OK) {
+       status = create_connect_relayd(relayd_uri, &rsock, consumer);
+       if (status != LTTNG_OK) {
                goto relayd_comm_error;
        }
        assert(rsock);
@@ -948,9 +1078,11 @@ static int send_consumer_relayd_socket(enum lttng_domain_type domain,
        /* Send relayd socket to consumer. */
        ret = consumer_send_relayd_socket(consumer_sock, rsock, consumer,
                        relayd_uri->stype, session_id,
-                       session_name, hostname, session_live_timer);
+                       session_name, hostname, base_path,
+                       session_live_timer, current_chunk_id,
+                       session_creation_time, session_name_contains_creation_time);
        if (ret < 0) {
-               ret = LTTNG_ERR_ENABLE_CONSUMER_FAIL;
+               status = LTTNG_ERR_ENABLE_CONSUMER_FAIL;
                goto close_sock;
        }
 
@@ -961,15 +1093,13 @@ static int send_consumer_relayd_socket(enum lttng_domain_type domain,
                consumer_sock->data_sock_sent = 1;
        }
 
-       ret = LTTNG_OK;
-
        /*
         * Close socket which was dup on the consumer side. The session daemon does
         * NOT keep track of the relayd socket(s) once transfer to the consumer.
         */
 
 close_sock:
-       if (ret != LTTNG_OK) {
+       if (status != LTTNG_OK) {
                /*
                 * The consumer output for this session should not be used anymore
                 * since the relayd connection failed thus making any tracing or/and
@@ -981,7 +1111,7 @@ close_sock:
        free(rsock);
 
 relayd_comm_error:
-       return ret;
+       return status;
 }
 
 /*
@@ -990,39 +1120,48 @@ relayd_comm_error:
  * session.
  *
  * The consumer socket lock must be held by the caller.
+ *
+ * Returns LTTNG_OK, or an LTTng error code on failure.
  */
-static int send_consumer_relayd_sockets(enum lttng_domain_type domain,
+static enum lttng_error_code send_consumer_relayd_sockets(
+               enum lttng_domain_type domain,
                unsigned int session_id, struct consumer_output *consumer,
-               struct consumer_socket *sock, char *session_name,
-               char *hostname, int session_live_timer)
+               struct consumer_socket *sock, const char *session_name,
+               const char *hostname, const char *base_path, int session_live_timer,
+               const uint64_t *current_chunk_id, time_t session_creation_time,
+               bool session_name_contains_creation_time)
 {
-       int ret = LTTNG_OK;
+       enum lttng_error_code status = LTTNG_OK;
 
        assert(consumer);
        assert(sock);
 
        /* Sending control relayd socket. */
        if (!sock->control_sock_sent) {
-               ret = send_consumer_relayd_socket(domain, session_id,
+               status = send_consumer_relayd_socket(session_id,
                                &consumer->dst.net.control, consumer, sock,
-                               session_name, hostname, session_live_timer);
-               if (ret != LTTNG_OK) {
+                               session_name, hostname, base_path, session_live_timer,
+                               current_chunk_id, session_creation_time,
+                               session_name_contains_creation_time);
+               if (status != LTTNG_OK) {
                        goto error;
                }
        }
 
        /* Sending data relayd socket. */
        if (!sock->data_sock_sent) {
-               ret = send_consumer_relayd_socket(domain, session_id,
+               status = send_consumer_relayd_socket(session_id,
                                &consumer->dst.net.data, consumer, sock,
-                               session_name, hostname, session_live_timer);
-               if (ret != LTTNG_OK) {
+                               session_name, hostname, base_path, session_live_timer,
+                               current_chunk_id, session_creation_time,
+                               session_name_contains_creation_time);
+               if (status != LTTNG_OK) {
                        goto error;
                }
        }
 
 error:
-       return ret;
+       return status;
 }
 
 /*
@@ -1037,14 +1176,28 @@ 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 = {};
 
-       assert(session);
+        assert(session);
 
        usess = session->ust_session;
        ksess = session->kernel_session;
 
        DBG("Setting relayd for session %s", session->name);
 
+       if (session->current_trace_chunk) {
+               enum lttng_trace_chunk_status status = lttng_trace_chunk_get_id(
+                               session->current_trace_chunk, &current_chunk_id.value);
+
+               if (status == LTTNG_TRACE_CHUNK_STATUS_OK) {
+                       current_chunk_id.is_set = true;
+               } else {
+                       ERR("Failed to get current trace chunk id");
+                       ret = LTTNG_ERR_UNK;
+                       goto error;
+               }
+       }
+
        rcu_read_lock();
 
        if (usess && usess->consumer && usess->consumer->type == CONSUMER_DST_NET
@@ -1056,7 +1209,11 @@ int cmd_setup_relayd(struct ltt_session *session)
                        ret = send_consumer_relayd_sockets(LTTNG_DOMAIN_UST, session->id,
                                        usess->consumer, socket,
                                        session->name, session->hostname,
-                                       session->live_timer);
+                                       session->base_path,
+                                       session->live_timer,
+                                       current_chunk_id.is_set ? &current_chunk_id.value : NULL,
+                                       session->creation_time,
+                                       session->name_contains_creation_time);
                        pthread_mutex_unlock(socket->lock);
                        if (ret != LTTNG_OK) {
                                goto error;
@@ -1078,7 +1235,11 @@ int cmd_setup_relayd(struct ltt_session *session)
                        ret = send_consumer_relayd_sockets(LTTNG_DOMAIN_KERNEL, session->id,
                                        ksess->consumer, socket,
                                        session->name, session->hostname,
-                                       session->live_timer);
+                                       session->base_path,
+                                       session->live_timer,
+                                       current_chunk_id.is_set ? &current_chunk_id.value : NULL,
+                                       session->creation_time,
+                                       session->name_contains_creation_time);
                        pthread_mutex_unlock(socket->lock);
                        if (ret != LTTNG_OK) {
                                goto error;
@@ -1100,7 +1261,7 @@ error:
 /*
  * Start a kernel session by opening all necessary streams.
  */
-static int start_kernel_session(struct ltt_kernel_session *ksess, int wpipe)
+static int start_kernel_session(struct ltt_kernel_session *ksess)
 {
        int ret;
        struct ltt_kernel_channel *kchan;
@@ -1152,7 +1313,7 @@ static int start_kernel_session(struct ltt_kernel_session *ksess, int wpipe)
        }
 
        /* Quiescent wait after starting trace */
-       kernel_wait_quiescent(kernel_tracer_fd);
+       kernel_wait_quiescent();
 
        ksess->active = 1;
 
@@ -1184,7 +1345,7 @@ int cmd_disable_channel(struct ltt_session *session,
                        goto error;
                }
 
-               kernel_wait_quiescent(kernel_tracer_fd);
+               kernel_wait_quiescent();
                break;
        }
        case LTTNG_DOMAIN_UST:
@@ -1242,7 +1403,7 @@ int cmd_track_pid(struct ltt_session *session, enum lttng_domain_type domain,
                        goto error;
                }
 
-               kernel_wait_quiescent(kernel_tracer_fd);
+               kernel_wait_quiescent();
                break;
        }
        case LTTNG_DOMAIN_UST:
@@ -1293,7 +1454,7 @@ int cmd_untrack_pid(struct ltt_session *session, enum lttng_domain_type domain,
                        goto error;
                }
 
-               kernel_wait_quiescent(kernel_tracer_fd);
+               kernel_wait_quiescent();
                break;
        }
        case LTTNG_DOMAIN_UST:
@@ -1326,27 +1487,29 @@ error:
  * 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)
+               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;
 
        assert(session);
-       assert(attr);
+       assert(_attr);
        assert(domain);
 
-       len = lttng_strnlen(attr->name, sizeof(attr->name));
+       attr = *_attr;
+       len = lttng_strnlen(attr.name, sizeof(attr.name));
 
        /* Validate channel name */
-       if (attr->name[0] == '.' ||
-               memchr(attr->name, '/', len) != NULL) {
+       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);
+       DBG("Enabling channel %s for session %s", attr.name, session->name);
 
        rcu_read_lock();
 
@@ -1365,28 +1528,34 @@ int cmd_enable_channel(struct ltt_session *session,
         * beacons for inactive streams.
         */
        if (session->live_timer > 0) {
-               attr->attr.live_timer_interval = session->live_timer;
-               attr->attr.switch_timer_interval = 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) {
+               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);
+                                       attr.name, session->name);
+                       lttng_channel_set_monitor_timer_interval(&attr, 0);
                }
                break;
        }
        case LTTNG_DOMAIN_UST:
+               break;
        case LTTNG_DOMAIN_JUL:
        case LTTNG_DOMAIN_LOG4J:
        case LTTNG_DOMAIN_PYTHON:
+               if (!agent_tracing_is_enabled()) {
+                       DBG("Attempted to enable a channel in an agent domain but the agent thread is not running");
+                       ret = LTTNG_ERR_AGENT_TRACING_DISABLED;
+                       goto error;
+               }
                break;
        default:
                ret = LTTNG_ERR_UNKNOWN_DOMAIN;
@@ -1398,11 +1567,16 @@ 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) {
-                       ret = channel_kernel_create(session->kernel_session, attr, wpipe);
-                       if (attr->name[0] != '\0') {
+                       if (session->snapshot.nb_output > 0 ||
+                                       session->snapshot_mode) {
+                               /* Enforce mmap output for snapshot sessions. */
+                               attr.attr.output = LTTNG_EVENT_MMAP;
+                       }
+                       ret = channel_kernel_create(session->kernel_session, &attr, wpipe);
+                       if (attr.name[0] != '\0') {
                                session->kernel_session->has_non_default_channel = 1;
                        }
                } else {
@@ -1413,7 +1587,7 @@ int cmd_enable_channel(struct ltt_session *session,
                        goto error;
                }
 
-               kernel_wait_quiescent(kernel_tracer_fd);
+               kernel_wait_quiescent();
                break;
        }
        case LTTNG_DOMAIN_UST:
@@ -1432,19 +1606,19 @@ 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;
@@ -1453,10 +1627,10 @@ 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') {
+                       ret = channel_ust_create(usess, &attr, domain->buf_type);
+                       if (attr.name[0] != '\0') {
                                usess->has_non_default_channel = 1;
                        }
                } else {
@@ -1469,6 +1643,9 @@ int cmd_enable_channel(struct ltt_session *session,
                goto error;
        }
 
+       if (ret == LTTNG_OK && attr.attr.output != LTTNG_EVENT_MMAP) {
+               session->has_non_mmap_channel = true;
+       }
 error:
        rcu_read_unlock();
 end:
@@ -1479,11 +1656,11 @@ end:
  * 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);
 
@@ -1545,7 +1722,7 @@ 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:
@@ -1656,7 +1833,7 @@ 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;
@@ -1827,7 +2004,7 @@ 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,
@@ -1963,6 +2140,7 @@ static int _cmd_enable_event(struct ltt_session *session,
                        break;
                }
                case LTTNG_EVENT_PROBE:
+               case LTTNG_EVENT_USERSPACE_PROBE:
                case LTTNG_EVENT_FUNCTION:
                case LTTNG_EVENT_FUNCTION_ENTRY:
                case LTTNG_EVENT_TRACEPOINT:
@@ -1994,7 +2172,7 @@ 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:
@@ -2060,8 +2238,7 @@ 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.",
-                                               event->name ?
-                                               event->name : "NULL");
+                                               event->name);
                                ret = LTTNG_ERR_INVALID_EVENT_NAME;
                                goto error;
                        }
@@ -2094,6 +2271,12 @@ static int _cmd_enable_event(struct ltt_session *session,
 
                assert(usess);
 
+               if (!agent_tracing_is_enabled()) {
+                       DBG("Attempted to enable an event in an agent domain but the agent thread is not running");
+                       ret = LTTNG_ERR_AGENT_TRACING_DISABLED;
+                       goto error;
+               }
+
                agt = trace_ust_find_agent(usess, domain->type);
                if (!agt) {
                        agt = agent_create(domain->type);
@@ -2218,7 +2401,8 @@ 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,
@@ -2235,7 +2419,7 @@ 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,
@@ -2257,7 +2441,7 @@ 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;
@@ -2377,113 +2561,6 @@ error:
        return -ret;
 }
 
-static
-int domain_mkdir(const struct consumer_output *output,
-               const struct ltt_session *session,
-               uid_t uid, gid_t gid)
-{
-       struct consumer_socket *socket;
-       struct lttng_ht_iter iter;
-       int ret;
-       char *path = NULL;
-
-       if (!output || !output->socks) {
-               ERR("No consumer output found");
-               ret = -1;
-               goto end;
-       }
-
-       path = zmalloc(LTTNG_PATH_MAX * sizeof(char));
-       if (!path) {
-               ERR("Cannot allocate mkdir path");
-               ret = -1;
-               goto end;
-       }
-
-       ret = snprintf(path, LTTNG_PATH_MAX, "%s%s%s",
-                       session_get_base_path(session),
-                       output->chunk_path, output->subdir);
-       if (ret < 0 || ret >= LTTNG_PATH_MAX) {
-               ERR("Format path");
-               ret = -1;
-               goto end;
-       }
-
-       DBG("Domain mkdir %s for session %" PRIu64, path, session->id);
-       rcu_read_lock();
-       /*
-        * We have to iterate to find a socket, but we only need to send the
-        * rename command to one consumer, so we break after the first one.
-        */
-       cds_lfht_for_each_entry(output->socks->ht, &iter.iter, socket, node.node) {
-               pthread_mutex_lock(socket->lock);
-               ret = consumer_mkdir(socket, session->id, output, path, uid, gid);
-               pthread_mutex_unlock(socket->lock);
-               if (ret) {
-                       ERR("Consumer mkdir");
-                       ret = -1;
-                       goto end_unlock;
-               }
-               break;
-       }
-
-       ret = 0;
-
-end_unlock:
-       rcu_read_unlock();
-end:
-       free(path);
-       return ret;
-}
-
-static
-int session_mkdir(const struct ltt_session *session)
-{
-       int ret;
-       struct consumer_output *output;
-       uid_t uid;
-       gid_t gid;
-
-       /*
-        * Unsupported feature in lttng-relayd before 2.11, not an error since it
-        * is only needed for session rotation and the user will get an error
-        * on rotate.
-        */
-       if (session->consumer->type == CONSUMER_DST_NET &&
-                       session->consumer->relay_major_version == 2 &&
-                       session->consumer->relay_minor_version < 11) {
-               ret = 0;
-               goto end;
-       }
-
-       if (session->kernel_session) {
-               output = session->kernel_session->consumer;
-               uid = session->kernel_session->uid;
-               gid = session->kernel_session->gid;
-               ret = domain_mkdir(output, session, uid, gid);
-               if (ret) {
-                       ERR("Mkdir kernel");
-                       goto end;
-               }
-       }
-
-       if (session->ust_session) {
-               output = session->ust_session->consumer;
-               uid = session->ust_session->uid;
-               gid = session->ust_session->gid;
-               ret = domain_mkdir(output, session, uid, gid);
-               if (ret) {
-                       ERR("Mkdir UST");
-                       goto end;
-               }
-       }
-
-       ret = 0;
-
-end:
-       return ret;
-}
-
 /*
  * Command LTTNG_START_TRACE processed by the client thread.
  *
@@ -2491,10 +2568,12 @@ end:
  */
 int cmd_start_trace(struct ltt_session *session)
 {
-       int ret;
+       enum lttng_error_code ret;
        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;
 
        assert(session);
 
@@ -2508,6 +2587,22 @@ int cmd_start_trace(struct ltt_session *session)
                goto error;
        }
 
+       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;
+       }
+
        /*
         * Starting a session without channel is useless since after that it's not
         * possible to enable channel thus inform the client.
@@ -2523,32 +2618,52 @@ int cmd_start_trace(struct ltt_session *session)
                goto error;
        }
 
-       /*
-        * Record the timestamp of the first time the session is started for
-        * an eventual session rotation call.
-        */
-       if (!session->has_been_started) {
-               session->current_chunk_start_ts = time(NULL);
-               if (session->current_chunk_start_ts == (time_t) -1) {
-                       PERROR("Failed to retrieve the \"%s\" session's start time",
+       session->active = 1;
+       session->rotated_after_last_stop = false;
+       if (session->output_traces && !session->current_trace_chunk) {
+               if (!session->has_been_started) {
+                       struct lttng_trace_chunk *trace_chunk;
+
+                       DBG("Creating initial trace chunk of session \"%s\"",
                                        session->name);
-                       ret = LTTNG_ERR_FATAL;
-                       goto error;
-               }
-               if (!session->snapshot_mode && session->output_traces) {
-                       ret = session_mkdir(session);
-                       if (ret) {
-                               ERR("Failed to create the session directories");
+                       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;
+                       }
+               } 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);
+                       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;
                }
@@ -2556,23 +2671,14 @@ int cmd_start_trace(struct ltt_session *session)
 
        /* Flag session that trace should start automatically */
        if (usess) {
-               /*
-                * Even though the start trace might fail, flag this session active so
-                * other application coming in are started by default.
-                */
-               usess->active = 1;
+               int int_ret = ust_app_start_trace_all(usess);
 
-               ret = ust_app_start_trace_all(usess);
-               if (ret < 0) {
+               if (int_ret < 0) {
                        ret = LTTNG_ERR_UST_START_FAIL;
                        goto error;
                }
        }
 
-       /* Flag this after a successful start. */
-       session->has_been_started = 1;
-       session->active = 1;
-
        /*
         * Clear the flag that indicates that a rotation was done while the
         * session was stopped.
@@ -2580,9 +2686,10 @@ int cmd_start_trace(struct ltt_session *session)
        session->rotated_after_last_stop = false;
 
        if (session->rotate_timer_period) {
-               ret = sessiond_rotate_timer_start(session,
-                               session->rotate_timer_period);
-               if (ret < 0) {
+               int int_ret = timer_session_rotation_schedule_timer_start(
+                               session, session->rotate_timer_period);
+
+               if (int_ret < 0) {
                        ERR("Failed to enable rotate timer");
                        ret = LTTNG_ERR_UNK;
                        goto error;
@@ -2592,48 +2699,15 @@ int cmd_start_trace(struct ltt_session *session)
        ret = LTTNG_OK;
 
 error:
-       return ret;
-}
-
-static
-int rename_active_chunk(struct ltt_session *session)
-{
-       int ret;
-
-       session->rotate_count++;
-
-       /*
-        * The currently active tracing path is now the folder we
-        * want to rename.
-        */
-       ret = lttng_strncpy(session->rotation_chunk.current_rotate_path,
-                       session->rotation_chunk.active_tracing_path,
-                       sizeof(session->rotation_chunk.current_rotate_path));
-       if (ret) {
-               ERR("Failed to copy active tracing path");
-               goto end;
-       }
-
-       ret = rename_complete_chunk(session, time(NULL));
-       if (ret < 0) {
-               ERR("Failed to rename current rotate path");
-               goto end;
-       }
-
-       /*
-        * We just renamed, the folder, we didn't do an actual rotation, so
-        * the active tracing path is now the renamed folder and we have to
-        * restore the rotate count.
-        */
-       ret = lttng_strncpy(session->rotation_chunk.active_tracing_path,
-                       session->rotation_chunk.current_rotate_path,
-                       sizeof(session->rotation_chunk.active_tracing_path));
-       if (ret) {
-               ERR("Failed to rename active session chunk tracing path");
-               goto end;
+       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;
        }
-end:
-       session->rotate_count--;
        return ret;
 }
 
@@ -2646,7 +2720,7 @@ int cmd_stop_trace(struct ltt_session *session)
        struct ltt_kernel_channel *kchan;
        struct ltt_kernel_session *ksession;
        struct ltt_ust_session *usess;
-       bool error_occured = false;
+       bool error_occurred = false;
 
        assert(session);
 
@@ -2661,25 +2735,6 @@ int cmd_stop_trace(struct ltt_session *session)
                goto error;
        }
 
-       if (session->rotate_relay_pending_timer_enabled) {
-               sessiond_timer_rotate_pending_stop(session);
-       }
-
-       if (session->rotate_timer_enabled) {
-               sessiond_rotate_timer_stop(session);
-       }
-
-       if (session->rotate_count > 0 && !session->rotate_pending) {
-               ret = rename_active_chunk(session);
-               if (ret) {
-                       /*
-                        * This error should not prevent the user from stopping
-                        * the session. However, it will be reported at the end.
-                        */
-                       error_occured = true;
-               }
-       }
-
        /* Kernel tracer */
        if (ksession && ksession->active) {
                DBG("Stop kernel tracing");
@@ -2690,13 +2745,14 @@ int cmd_stop_trace(struct ltt_session *session)
                        goto error;
                }
 
-               kernel_wait_quiescent(kernel_tracer_fd);
+               kernel_wait_quiescent();
 
                /* 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");
+                               error_occurred = true;
                        }
                }
 
@@ -2705,6 +2761,7 @@ int cmd_stop_trace(struct ltt_session *session)
                        ret = kernel_flush_buffer(kchan);
                        if (ret < 0) {
                                ERR("Kernel flush buffer error");
+                               error_occurred = true;
                        }
                }
 
@@ -2714,12 +2771,6 @@ int cmd_stop_trace(struct ltt_session *session)
        }
 
        if (usess && usess->active) {
-               /*
-                * Even though the stop trace might fail, flag this session inactive so
-                * other application coming in are not started by default.
-                */
-               usess->active = 0;
-
                ret = ust_app_stop_trace_all(usess);
                if (ret < 0) {
                        ret = LTTNG_ERR_UST_STOP_FAIL;
@@ -2729,8 +2780,47 @@ int cmd_stop_trace(struct ltt_session *session)
 
        /* Flag inactive after a successful stop. */
        session->active = 0;
-       ret = !error_occured ? LTTNG_OK : LTTNG_ERR_UNK;
+       ret = !error_occurred ? LTTNG_OK : LTTNG_ERR_UNK;
+
+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;
 }
@@ -2755,10 +2845,20 @@ 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->consumer,
-                               &uris[i], 0, session->name);
+               ret = add_uri_to_consumer(session, session->consumer, &uris[i],
+                               LTTNG_DOMAIN_NONE);
                if (ret != LTTNG_OK) {
                        goto error;
                }
@@ -2767,10 +2867,9 @@ int cmd_set_consumer_uri(struct ltt_session *session, size_t nb_uri,
        /* Set UST session URIs */
        if (session->ust_session) {
                for (i = 0; i < nb_uri; i++) {
-                       ret = add_uri_to_consumer(
+                       ret = add_uri_to_consumer(session,
                                        session->ust_session->consumer,
-                                       &uris[i], LTTNG_DOMAIN_UST,
-                                       session->name);
+                                       &uris[i], LTTNG_DOMAIN_UST);
                        if (ret != LTTNG_OK) {
                                goto error;
                        }
@@ -2780,10 +2879,9 @@ int cmd_set_consumer_uri(struct ltt_session *session, size_t nb_uri,
        /* Set kernel session URIs */
        if (session->kernel_session) {
                for (i = 0; i < nb_uri; i++) {
-                       ret = add_uri_to_consumer(
+                       ret = add_uri_to_consumer(session,
                                        session->kernel_session->consumer,
-                                       &uris[i], LTTNG_DOMAIN_KERNEL,
-                                       session->name);
+                                       &uris[i], LTTNG_DOMAIN_KERNEL);
                        if (ret != LTTNG_OK) {
                                goto error;
                        }
@@ -2810,142 +2908,333 @@ error:
        return ret;
 }
 
-/*
- * Command LTTNG_CREATE_SESSION processed by the client thread.
- */
-int cmd_create_session_uri(char *name, struct lttng_uri *uris,
-               size_t nb_uri, lttng_sock_cred *creds, unsigned int live_timer)
+static
+enum lttng_error_code set_session_output_from_descriptor(
+               struct ltt_session *session,
+               const struct lttng_session_descriptor *descriptor)
 {
        int ret;
-       struct ltt_session *session;
+       enum lttng_error_code ret_code = LTTNG_OK;
+       enum lttng_session_descriptor_type session_type =
+                       lttng_session_descriptor_get_type(descriptor);
+       enum lttng_session_descriptor_output_type output_type =
+                       lttng_session_descriptor_get_output_type(descriptor);
+       struct lttng_uri uris[2] = {};
+       size_t uri_count = 0;
+
+       switch (output_type) {
+       case LTTNG_SESSION_DESCRIPTOR_OUTPUT_TYPE_NONE:
+               goto end;
+       case LTTNG_SESSION_DESCRIPTOR_OUTPUT_TYPE_LOCAL:
+               lttng_session_descriptor_get_local_output_uri(descriptor,
+                               &uris[0]);
+               uri_count = 1;
+               break;
+       case LTTNG_SESSION_DESCRIPTOR_OUTPUT_TYPE_NETWORK:
+               lttng_session_descriptor_get_network_output_uris(descriptor,
+                               &uris[0], &uris[1]);
+               uri_count = 2;
+               break;
+       default:
+               ret_code = LTTNG_ERR_INVALID;
+               goto end;
+       }
 
-       assert(name);
-       assert(creds);
+       switch (session_type) {
+       case LTTNG_SESSION_DESCRIPTOR_TYPE_SNAPSHOT:
+       {
+               struct snapshot_output *new_output = NULL;
 
-       /*
-        * Verify if the session already exist
-        *
-        * XXX: There is no need for the session lock list here since the caller
-        * (process_client_msg) is holding it. We might want to change that so a
-        * single command does not lock the entire session list.
-        */
-       session = session_find_by_name(name);
-       if (session != NULL) {
-               ret = LTTNG_ERR_EXIST_SESS;
-               goto find_error;
+               new_output = snapshot_output_alloc();
+               if (!new_output) {
+                       ret_code = LTTNG_ERR_NOMEM;
+                       goto end;
+               }
+
+               ret = snapshot_output_init_with_uri(session,
+                               DEFAULT_SNAPSHOT_MAX_SIZE,
+                               NULL, uris, uri_count, session->consumer,
+                               new_output, &session->snapshot);
+               if (ret < 0) {
+                       ret_code = (ret == -ENOMEM) ?
+                                       LTTNG_ERR_NOMEM : LTTNG_ERR_INVALID;
+                       snapshot_output_destroy(new_output);
+                       goto end;
+               }
+               snapshot_add_output(&session->snapshot, new_output);
+               break;
+       }
+       case LTTNG_SESSION_DESCRIPTOR_TYPE_REGULAR:
+       case LTTNG_SESSION_DESCRIPTOR_TYPE_LIVE:
+       {
+               ret_code = cmd_set_consumer_uri(session, uri_count, uris);
+               break;
+       }
+       default:
+               ret_code = LTTNG_ERR_INVALID;
+               goto end;
        }
+end:
+       return ret_code;
+}
 
-       /* Create tracing session in the registry */
-       ret = session_create(name, LTTNG_SOCK_GET_UID_CRED(creds),
-                       LTTNG_SOCK_GET_GID_CRED(creds));
-       if (ret != LTTNG_OK) {
-               goto session_error;
+static
+enum lttng_error_code cmd_create_session_from_descriptor(
+               struct lttng_session_descriptor *descriptor,
+               const lttng_sock_cred *creds,
+               const char *home_path)
+{
+       int ret;
+       enum lttng_error_code ret_code;
+       const char *session_name;
+       struct ltt_session *new_session = NULL;
+       enum lttng_session_descriptor_status descriptor_status;
+
+       session_lock_list();
+       if (home_path) {
+               if (*home_path != '/') {
+                       ERR("Home path provided by client is not absolute");
+                       ret_code = LTTNG_ERR_INVALID;
+                       goto end;
+               }
        }
 
-       /*
-        * Get the newly created session pointer back
-        *
-        * XXX: There is no need for the session lock list here since the caller
-        * (process_client_msg) is holding it. We might want to change that so a
-        * single command does not lock the entire session list.
-        */
-       session = session_find_by_name(name);
-       assert(session);
+       descriptor_status = lttng_session_descriptor_get_session_name(
+                       descriptor, &session_name);
+       switch (descriptor_status) {
+       case LTTNG_SESSION_DESCRIPTOR_STATUS_OK:
+               break;
+       case LTTNG_SESSION_DESCRIPTOR_STATUS_UNSET:
+               session_name = NULL;
+               break;
+       default:
+               ret_code = LTTNG_ERR_INVALID;
+               goto end;
+       }
 
-       session->live_timer = live_timer;
-       /* Create default consumer output for the session not yet created. */
-       session->consumer = consumer_create_output(CONSUMER_DST_LOCAL);
-       if (session->consumer == NULL) {
-               ret = LTTNG_ERR_FATAL;
-               goto consumer_error;
+       ret_code = session_create(session_name, creds->uid, creds->gid,
+                       &new_session);
+       if (ret_code != LTTNG_OK) {
+               goto end;
        }
 
-       if (uris) {
-               ret = cmd_set_consumer_uri(session, nb_uri, uris);
-               if (ret != LTTNG_OK) {
-                       goto consumer_error;
+       if (!session_name) {
+               ret = lttng_session_descriptor_set_session_name(descriptor,
+                               new_session->name);
+               if (ret) {
+                       ret_code = LTTNG_ERR_SESSION_FAIL;
+                       goto end;
                }
-               session->output_traces = 1;
-       } else {
-               session->output_traces = 0;
-               DBG2("Session %s created with no output", session->name);
        }
 
-       session->consumer->enabled = 1;
+       if (!lttng_session_descriptor_is_output_destination_initialized(
+                       descriptor)) {
+               /*
+                * Only include the session's creation time in the output
+                * destination if the name of the session itself was
+                * not auto-generated.
+                */
+               ret_code = lttng_session_descriptor_set_default_output(
+                               descriptor,
+                               session_name ? &new_session->creation_time : NULL,
+                               home_path);
+               if (ret_code != LTTNG_OK) {
+                       goto end;
+               }
+       } else {
+               new_session->has_user_specified_directory =
+                               lttng_session_descriptor_has_output_directory(
+                                       descriptor);
+       }
 
-       return LTTNG_OK;
+       switch (lttng_session_descriptor_get_type(descriptor)) {
+       case LTTNG_SESSION_DESCRIPTOR_TYPE_SNAPSHOT:
+               new_session->snapshot_mode = 1;
+               break;
+       case LTTNG_SESSION_DESCRIPTOR_TYPE_LIVE:
+               new_session->live_timer =
+                               lttng_session_descriptor_live_get_timer_interval(
+                                       descriptor);
+               break;
+       default:
+               break;
+       }
 
-consumer_error:
-       session_destroy(session);
-session_error:
-find_error:
-       return ret;
+       ret_code = set_session_output_from_descriptor(new_session, descriptor);
+       if (ret_code != LTTNG_OK) {
+               goto end;
+       }
+       new_session->consumer->enabled = 1;
+       ret_code = LTTNG_OK;
+end:
+       /* Release reference provided by the session_create function. */
+       session_put(new_session);
+       if (ret_code != LTTNG_OK && new_session) {
+               /* Release the global reference on error. */
+               session_destroy(new_session);
+       }
+       session_unlock_list();
+       return ret_code;
 }
 
-/*
- * Command LTTNG_CREATE_SESSION_SNAPSHOT processed by the client thread.
- */
-int cmd_create_session_snapshot(char *name, struct lttng_uri *uris,
-               size_t nb_uri, lttng_sock_cred *creds)
+enum lttng_error_code cmd_create_session(struct command_ctx *cmd_ctx, int sock,
+               struct lttng_session_descriptor **return_descriptor)
 {
        int ret;
-       struct ltt_session *session;
-       struct snapshot_output *new_output = NULL;
-
-       assert(name);
-       assert(creds);
+       size_t payload_size;
+       struct lttng_dynamic_buffer payload;
+       struct lttng_buffer_view home_dir_view;
+       struct lttng_buffer_view session_descriptor_view;
+       struct lttng_session_descriptor *session_descriptor = NULL;
+       enum lttng_error_code ret_code;
+
+       lttng_dynamic_buffer_init(&payload);
+       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 >
+                       LTTNG_SESSION_DESCRIPTOR_MAX_LEN) {
+               ret_code = LTTNG_ERR_INVALID;
+               goto error;
+       }
 
-       /*
-        * Create session in no output mode with URIs set to NULL. The uris we've
-        * received are for a default snapshot output if one.
-        */
-       ret = cmd_create_session_uri(name, NULL, 0, creds, 0);
-       if (ret != LTTNG_OK) {
+       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;
                goto error;
        }
 
-       /* Get the newly created session pointer back. This should NEVER fail. */
-       session = session_find_by_name(name);
-       assert(session);
+       ret = lttcomm_recv_unix_sock(sock, payload.data, payload.size);
+       if (ret <= 0) {
+               ERR("Reception of session descriptor failed, aborting.");
+               ret_code = LTTNG_ERR_SESSION_FAIL;
+               goto error;
+       }
 
-       /* Flag session for snapshot mode. */
-       session->snapshot_mode = 1;
+       home_dir_view = lttng_buffer_view_from_dynamic_buffer(
+                       &payload,
+                       0,
+                       cmd_ctx->lsm->u.create_session.home_dir_size);
+       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);
 
-       /* Skip snapshot output creation if no URI is given. */
-       if (nb_uri == 0) {
-               goto end;
+       ret = lttng_session_descriptor_create_from_buffer(
+                       &session_descriptor_view, &session_descriptor);
+       if (ret < 0) {
+               ERR("Failed to create session descriptor from payload of \"create session\" command");
+               ret_code = LTTNG_ERR_INVALID;
+               goto error;
        }
 
-       new_output = snapshot_output_alloc();
-       if (!new_output) {
-               ret = LTTNG_ERR_NOMEM;
-               goto error_snapshot_alloc;
+       /*
+        * Sets the descriptor's auto-generated properties (name, output) if
+        * needed.
+        */
+       ret_code = cmd_create_session_from_descriptor(session_descriptor,
+                       &cmd_ctx->creds,
+                       home_dir_view.size ? home_dir_view.data : NULL);
+       if (ret_code != LTTNG_OK) {
+               goto error;
        }
 
-       ret = snapshot_output_init_with_uri(DEFAULT_SNAPSHOT_MAX_SIZE, NULL,
-                       uris, nb_uri, session->consumer, new_output, &session->snapshot);
-       if (ret < 0) {
-               if (ret == -ENOMEM) {
-                       ret = LTTNG_ERR_NOMEM;
-               } else {
-                       ret = LTTNG_ERR_INVALID;
-               }
-               goto error_snapshot;
+       ret_code = LTTNG_OK;
+       *return_descriptor = session_descriptor;
+       session_descriptor = NULL;
+error:
+       lttng_dynamic_buffer_reset(&payload);
+       lttng_session_descriptor_destroy(session_descriptor);
+       return ret_code;
+}
+
+static
+void cmd_destroy_session_reply(const struct ltt_session *session,
+               void *_reply_context)
+{
+       int ret;
+       ssize_t comm_ret;
+       const struct cmd_destroy_session_reply_context *reply_context =
+                       _reply_context;
+       struct lttng_dynamic_buffer payload;
+       struct lttcomm_session_destroy_command_header cmd_header;
+       struct lttng_trace_archive_location *location = NULL;
+       struct lttcomm_lttng_msg llm = {
+               .cmd_type = LTTNG_DESTROY_SESSION,
+               .ret_code = reply_context->destruction_status,
+               .pid = UINT32_MAX,
+               .cmd_header_size =
+                       sizeof(struct lttcomm_session_destroy_command_header),
+               .data_size = 0,
+       };
+       size_t payload_size_before_location;
+
+       lttng_dynamic_buffer_init(&payload);
+
+       ret = lttng_dynamic_buffer_append(&payload, &llm, sizeof(llm));
+        if (ret) {
+               ERR("Failed to append session destruction message");
+               goto error;
+        }
+
+       cmd_header.rotation_state =
+                       (int32_t) (reply_context->implicit_rotation_on_destroy ?
+                               session->rotation_state :
+                               LTTNG_ROTATION_STATE_NO_ROTATION);
+       ret = lttng_dynamic_buffer_append(&payload, &cmd_header,
+                       sizeof(cmd_header));
+       if (ret) {
+               ERR("Failed to append session destruction command header");
+               goto error;
        }
 
-       rcu_read_lock();
-       snapshot_add_output(&session->snapshot, new_output);
-       rcu_read_unlock();
+       if (!reply_context->implicit_rotation_on_destroy) {
+               DBG("No implicit rotation performed during the destruction of session \"%s\", sending reply",
+                               session->name);
+               goto send_reply;
+       }
+       if (session->rotation_state != LTTNG_ROTATION_STATE_COMPLETED) {
+               DBG("Rotation state of session \"%s\" is not \"completed\", sending session destruction reply",
+                               session->name);
+               goto send_reply;
+       }
 
-end:
-       return LTTNG_OK;
+       location = session_get_trace_archive_location(session);
+       if (!location) {
+               ERR("Failed to get the location of the trace archive produced during the destruction of session \"%s\"",
+                               session->name);
+               goto error;
+       }
 
-error_snapshot:
-       snapshot_output_destroy(new_output);
-error_snapshot_alloc:
-       session_destroy(session);
+       payload_size_before_location = payload.size;
+       comm_ret = lttng_trace_archive_location_serialize(location,
+                       &payload);
+       if (comm_ret < 0) {
+               ERR("Failed to serialize the location of the trace archive produced during the destruction of session \"%s\"",
+                               session->name);
+               goto error;
+       }
+       /* Update the message to indicate the location's length. */
+       ((struct lttcomm_lttng_msg *) payload.data)->data_size =
+                       payload.size - payload_size_before_location;
+send_reply:
+       comm_ret = lttcomm_send_unix_sock(reply_context->reply_sock_fd,
+                       payload.data, payload.size);
+       if (comm_ret != (ssize_t) payload.size) {
+               ERR("Failed to send result of the destruction of session \"%s\" to client",
+                               session->name);
+       }
 error:
-       return ret;
+       ret = close(reply_context->reply_sock_fd);
+       if (ret) {
+               PERROR("Failed to close client socket in deferred session destroy reply");
+       }
+       lttng_dynamic_buffer_reset(&payload);
+       free(_reply_context);
 }
 
 /*
@@ -2953,27 +3242,47 @@ error:
  *
  * Called with session lock held.
  */
-int cmd_destroy_session(struct ltt_session *session, int wpipe,
-               struct notification_thread_handle *notification_thread_handle)
+int cmd_destroy_session(struct ltt_session *session,
+               struct notification_thread_handle *notification_thread_handle,
+               int *sock_fd)
 {
        int ret;
-       struct ltt_ust_session *usess;
-       struct ltt_kernel_session *ksess;
+       enum lttng_error_code destruction_last_error = LTTNG_OK;
+       struct cmd_destroy_session_reply_context *reply_context = NULL;
+
+       if (sock_fd) {
+               reply_context = zmalloc(sizeof(*reply_context));
+               if (!reply_context) {
+                       ret = LTTNG_ERR_NOMEM;
+                       goto end;
+               }
+               reply_context->reply_sock_fd = *sock_fd;
+       }
 
        /* Safety net */
        assert(session);
 
-       usess = session->ust_session;
-       ksess = session->kernel_session;
-
-       DBG("Begin destroy session %s (id %" PRIu64 ")", session->name, session->id);
-
-       if (session->rotate_relay_pending_timer_enabled) {
-               sessiond_timer_rotate_pending_stop(session);
+       DBG("Begin destroy session %s (id %" PRIu64 ")", session->name,
+                       session->id);
+       if (session->active) {
+               DBG("Session \"%s\" is active, attempting to stop it before destroying it",
+                               session->name);
+               ret = cmd_stop_trace(session);
+               if (ret != LTTNG_OK && ret != LTTNG_ERR_TRACE_ALREADY_STOPPED) {
+                       /* 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;
+               }
        }
 
-       if (session->rotate_timer_enabled) {
-               sessiond_rotate_timer_stop(session);
+       if (session->rotation_schedule_timer_enabled) {
+               if (timer_session_rotation_schedule_timer_stop(
+                               session)) {
+                       ERR("Failed to stop the \"rotation schedule\" timer of session %s",
+                                       session->name);
+                       destruction_last_error = LTTNG_ERR_TIMER_STOP_ERROR;
+               }
        }
 
        if (session->rotate_size) {
@@ -2981,44 +3290,114 @@ int cmd_destroy_session(struct ltt_session *session, int wpipe,
                session->rotate_size = 0;
        }
 
-       /*
-        * The rename of the current chunk is performed at stop, but if we rotated
-        * the session after the previous stop command, we need to rename the
-        * new (and empty) chunk that was started in between.
-        */
-       if (session->rotated_after_last_stop) {
-               rename_active_chunk(session);
-       }
-
-       /* Clean kernel session teardown */
-       kernel_destroy_session(ksess);
-
-       /* UST session teardown */
-       if (usess) {
-               /* Close any relayd session */
-               consumer_output_send_destroy_relayd(usess->consumer);
-
-               /* Destroy every UST application related to this session. */
-               ret = ust_app_destroy_trace_all(usess);
-               if (ret) {
-                       ERR("Error in ust_app_destroy_trace_all");
+       if (session->most_recent_chunk_id.is_set &&
+                       session->most_recent_chunk_id.value != 0 &&
+                       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);
+               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) {
+                       reply_context->implicit_rotation_on_destroy = true;
+                }
+        } 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
+                * to a 'null' trace chunk before it is destroyed.
+                *
+                * This is a "quiet" rotation meaning that no notification is
+                * emitted and no renaming of the current trace chunk takes
+                * place.
+                */
+               ret = cmd_rotate_session(session, NULL, true);
+               if (ret != LTTNG_OK) {
+                       ERR("Failed to perform a quiet rotation as part of the destruction of session \"%s\": %s",
+                                       session->name, lttng_strerror(-ret));
+                       destruction_last_error = -ret;
                }
+       }
 
-               /* Clean up the rest. */
-               trace_ust_destroy_session(usess);
+       if (session->shm_path[0]) {
+               /*
+                * When a session is created with an explicit shm_path,
+                * the consumer daemon will create its shared memory files
+                * at that location and will *not* unlink them. This is normal
+                * as the intention of that feature is to make it possible
+                * to retrieve the content of those files should a crash occur.
+                *
+                * To ensure the content of those files can be used, the
+                * sessiond daemon will replicate the content of the metadata
+                * cache in a metadata file.
+                *
+                * On clean-up, it is expected that the consumer daemon will
+                * unlink the shared memory files and that the session daemon
+                * will unlink the metadata file. Then, the session's directory
+                * in the shm path can be removed.
+                *
+                * Unfortunately, a flaw in the design of the sessiond's and
+                * consumerd's tear down of channels makes it impossible to
+                * determine when the sessiond _and_ the consumerd have both
+                * destroyed their representation of a channel. For one, the
+                * unlinking, close, and rmdir happen in deferred 'call_rcu'
+                * callbacks in both daemons.
+                *
+                * However, it is also impossible for the sessiond to know when
+                * the consumer daemon is done destroying its channel(s) since
+                * it occurs as a reaction to the closing of the channel's file
+                * descriptor. There is no resulting communication initiated
+                * from the consumerd to the sessiond to confirm that the
+                * operation is completed (and was successful).
+                *
+                * Until this is all fixed, the session daemon checks for the
+                * removal of the session's shm path which makes it possible
+                * to safely advertise a session as having been destroyed.
+                *
+                * Prior to this fix, it was not possible to reliably save
+                * a session making use of the --shm-path option, destroy it,
+                * and load it again. This is because the creation of the
+                * session would fail upon seeing the session's shm path
+                * already in existence.
+                *
+                * Note that none of the error paths in the check for the
+                * directory's existence return an error. This is normal
+                * as there isn't much that can be done. The session will
+                * be destroyed properly, except that we can't offer the
+                * guarantee that the same session can be re-created.
+                */
+               current_completion_handler = &destroy_completion_handler.handler;
+               ret = lttng_strncpy(destroy_completion_handler.shm_path,
+                               session->shm_path,
+                               sizeof(destroy_completion_handler.shm_path));
+               assert(!ret);
        }
 
        /*
-        * Must notify the kernel thread here to update it's poll set in order to
-        * remove the channel(s)' fd just destroyed.
+        * The session is destroyed. However, note that the command context
+        * still holds a reference to the session, thus delaying its destruction
+        * _at least_ up to the point when that reference is released.
         */
-       ret = notify_thread_pipe(wpipe);
-       if (ret < 0) {
-               PERROR("write kernel poll pipe");
-       }
-
-       ret = session_destroy(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);
+               if (ret) {
+                       ret = LTTNG_ERR_FATAL;
+                       goto end;
+               } else {
+                       *sock_fd = -1;
+               }
+        }
+        ret = LTTNG_OK;
+end:
        return ret;
 }
 
@@ -3307,13 +3686,15 @@ error:
  * The session list lock MUST be acquired before calling this function. Use
  * session_lock_list() and session_unlock_list().
  */
-void cmd_list_lttng_sessions(struct lttng_session *sessions, uid_t uid,
-               gid_t gid)
+void cmd_list_lttng_sessions(struct lttng_session *sessions,
+               size_t session_count, uid_t uid, gid_t gid)
 {
        int ret;
        unsigned int i = 0;
        struct ltt_session *session;
        struct ltt_session_list *list = session_get_list();
+        struct lttng_session_extended *extended =
+                       (typeof(extended)) (&sessions[session_count]);
 
        DBG("Getting all available session for UID %d GID %d",
                        uid, gid);
@@ -3322,10 +3703,15 @@ void cmd_list_lttng_sessions(struct lttng_session *sessions, uid_t uid,
         * the buffer.
         */
        cds_list_for_each_entry(session, &list->head, list) {
+               if (!session_get(session)) {
+                       continue;
+               }
                /*
                 * Only list the sessions the user can control.
                 */
-               if (!session_access_ok(session, uid, gid)) {
+               if (!session_access_ok(session, uid, gid) ||
+                               session->destroyed) {
+                       session_put(session);
                        continue;
                }
 
@@ -3343,6 +3729,7 @@ void cmd_list_lttng_sessions(struct lttng_session *sessions, uid_t uid,
                }
                if (ret < 0) {
                        PERROR("snprintf session path");
+                       session_put(session);
                        continue;
                }
 
@@ -3351,7 +3738,10 @@ void cmd_list_lttng_sessions(struct lttng_session *sessions, uid_t uid,
                sessions[i].enabled = session->active;
                sessions[i].snapshot_mode = session->snapshot_mode;
                sessions[i].live_timer_interval = session->live_timer;
+               extended[i].creation_time.value = (uint64_t) session->creation_time;
+               extended[i].creation_time.is_set = 1;
                i++;
+               session_put(session);
        }
 }
 
@@ -3390,10 +3780,8 @@ int cmd_data_pending(struct ltt_session *session)
                }
        }
 
-       /*
-        * A rotation is still pending, we have to wait.
-        */
-       if (session->rotate_pending) {
+       /* A rotation is still pending, we have to wait. */
+       if (session->rotation_state == LTTNG_ROTATION_STATE_ONGOING) {
                DBG("Rotate still pending for session %s", session->name);
                ret = 1;
                goto error;
@@ -3428,7 +3816,7 @@ 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;
@@ -3446,6 +3834,11 @@ int cmd_snapshot_add_output(struct ltt_session *session,
                goto error;
        }
 
+       if (session->has_non_mmap_channel) {
+               ret = LTTNG_ERR_SNAPSHOT_UNSUPPORTED;
+               goto error;
+       }
+
        /* Only one output is allowed until we have the "tee" feature. */
        if (session->snapshot.nb_output == 1) {
                ret = LTTNG_ERR_SNAPSHOT_OUTPUT_EXIST;
@@ -3458,7 +3851,7 @@ int cmd_snapshot_add_output(struct ltt_session *session,
                goto error;
        }
 
-       ret = snapshot_output_init(output->max_size, output->name,
+       ret = snapshot_output_init(session, output->max_size, output->name,
                        output->ctrl_url, output->data_url, session->consumer, new_output,
                        &session->snapshot);
        if (ret < 0) {
@@ -3491,7 +3884,7 @@ 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;
@@ -3671,10 +4064,12 @@ static
 int clear_metadata_file(int fd)
 {
        int ret;
+       off_t lseek_ret;
 
-       ret = lseek(fd, 0, SEEK_SET);
-       if (ret < 0) {
+       lseek_ret = lseek(fd, 0, SEEK_SET);
+       if (lseek_ret < 0) {
                PERROR("lseek");
+               ret = -1;
                goto end;
        }
 
@@ -3947,40 +4342,71 @@ end:
  * Send relayd sockets from snapshot output to consumer. Ignore request if the
  * snapshot output is *not* set with a remote destination.
  *
- * Return 0 on success or a LTTNG_ERR code.
+ * Return LTTNG_OK on success or a LTTNG_ERR code.
  */
-static int set_relayd_for_snapshot(struct consumer_output *consumer,
-               struct snapshot_output *snap_output, struct ltt_session *session)
+static enum lttng_error_code set_relayd_for_snapshot(
+               struct consumer_output *output,
+               const struct ltt_session *session)
 {
-       int ret = LTTNG_OK;
+       enum lttng_error_code status = LTTNG_OK;
        struct lttng_ht_iter iter;
        struct consumer_socket *socket;
+       LTTNG_OPTIONAL(uint64_t) current_chunk_id = {};
+       const char *base_path;
 
-       assert(consumer);
-       assert(snap_output);
+       assert(output);
        assert(session);
 
        DBG2("Set relayd object from snapshot output");
 
+       if (session->current_trace_chunk) {
+               enum lttng_trace_chunk_status chunk_status =
+                               lttng_trace_chunk_get_id(
+                                               session->current_trace_chunk,
+                                               &current_chunk_id.value);
+
+               if (chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK) {
+                       current_chunk_id.is_set = true;
+               } else {
+                       ERR("Failed to get current trace chunk id");
+                       status = LTTNG_ERR_UNK;
+                       goto error;
+               }
+       }
+
        /* Ignore if snapshot consumer output is not network. */
-       if (snap_output->consumer->type != CONSUMER_DST_NET) {
+       if (output->type != CONSUMER_DST_NET) {
                goto error;
        }
 
+       /*
+        * The snapshot record URI base path overrides the session
+        * base path.
+        */
+       if (output->dst.net.control.subdir[0] != '\0') {
+               base_path = output->dst.net.control.subdir;
+       } else {
+               base_path = session->base_path;
+       }
+
        /*
         * For each consumer socket, create and send the relayd object of the
         * snapshot output.
         */
        rcu_read_lock();
-       cds_lfht_for_each_entry(snap_output->consumer->socks->ht, &iter.iter,
+       cds_lfht_for_each_entry(output->socks->ht, &iter.iter,
                        socket, node.node) {
                pthread_mutex_lock(socket->lock);
-               ret = send_consumer_relayd_sockets(0, session->id,
-                               snap_output->consumer, socket,
+               status = send_consumer_relayd_sockets(0, session->id,
+                               output, socket,
                                session->name, session->hostname,
-                               session->live_timer);
+                               base_path,
+                               session->live_timer,
+                               current_chunk_id.is_set ? &current_chunk_id.value : NULL,
+                               session->creation_time,
+                               session->name_contains_creation_time);
                pthread_mutex_unlock(socket->lock);
-               if (ret != LTTNG_OK) {
+               if (status != LTTNG_OK) {
                        rcu_read_unlock();
                        goto error;
                }
@@ -3988,7 +4414,7 @@ static int set_relayd_for_snapshot(struct consumer_output *consumer,
        rcu_read_unlock();
 
 error:
-       return ret;
+       return status;
 }
 
 /*
@@ -3996,109 +4422,54 @@ error:
  *
  * Return LTTNG_OK on success or a LTTNG_ERR code.
  */
-static int record_kernel_snapshot(struct ltt_kernel_session *ksess,
-               struct snapshot_output *output, struct ltt_session *session,
+static enum lttng_error_code record_kernel_snapshot(
+               struct ltt_kernel_session *ksess,
+               const struct consumer_output *output,
+               const struct ltt_session *session,
                int wait, uint64_t nb_packets_per_stream)
 {
-       int ret;
+       enum lttng_error_code status;
 
        assert(ksess);
        assert(output);
        assert(session);
 
-
-       /*
-        * Copy kernel session sockets so we can communicate with the right
-        * consumer for the snapshot record command.
-        */
-       ret = consumer_copy_sockets(output->consumer, ksess->consumer);
-       if (ret < 0) {
-               ret = LTTNG_ERR_NOMEM;
-               goto error;
-       }
-
-       ret = set_relayd_for_snapshot(ksess->consumer, output, session);
-       if (ret != LTTNG_OK) {
-               goto error_snapshot;
-       }
-
-       ret = kernel_snapshot_record(ksess, output, wait, nb_packets_per_stream);
-       if (ret != LTTNG_OK) {
-               goto error_snapshot;
-       }
-
-       ret = LTTNG_OK;
-       goto end;
-
-error_snapshot:
-       /* Clean up copied sockets so this output can use some other later on. */
-       consumer_destroy_output_sockets(output->consumer);
-error:
-end:
-       return ret;
-}
+       status = kernel_snapshot_record(
+                       ksess, output, wait, nb_packets_per_stream);
+       return status;
+}
 
 /*
  * Record a UST snapshot.
  *
- * Return 0 on success or a LTTNG_ERR error code.
+ * Returns LTTNG_OK on success or a LTTNG_ERR error code.
  */
-static int record_ust_snapshot(struct ltt_ust_session *usess,
-               struct snapshot_output *output, struct ltt_session *session,
+static enum lttng_error_code record_ust_snapshot(struct ltt_ust_session *usess,
+               const struct consumer_output *output,
+               const struct ltt_session *session,
                int wait, uint64_t nb_packets_per_stream)
 {
-       int ret;
+       enum lttng_error_code status;
 
        assert(usess);
        assert(output);
        assert(session);
 
-       /*
-        * Copy UST session sockets so we can communicate with the right
-        * consumer for the snapshot record command.
-        */
-       ret = consumer_copy_sockets(output->consumer, usess->consumer);
-       if (ret < 0) {
-               ret = LTTNG_ERR_NOMEM;
-               goto error;
-       }
-
-       ret = set_relayd_for_snapshot(usess->consumer, output, session);
-       if (ret != LTTNG_OK) {
-               goto error_snapshot;
-       }
-
-       ret = ust_app_snapshot_record(usess, output, wait, nb_packets_per_stream);
-       if (ret < 0) {
-               switch (-ret) {
-               case EINVAL:
-                       ret = LTTNG_ERR_INVALID;
-                       break;
-               default:
-                       ret = LTTNG_ERR_SNAPSHOT_FAIL;
-                       break;
-               }
-               goto error_snapshot;
-       }
-
-       ret = LTTNG_OK;
-
-error_snapshot:
-       /* Clean up copied sockets so this output can use some other later on. */
-       consumer_destroy_output_sockets(output->consumer);
-error:
-       return ret;
+       status = ust_app_snapshot_record(
+                       usess, output, wait, nb_packets_per_stream);
+       return status;
 }
 
 static
-uint64_t get_session_size_one_more_packet_per_stream(struct ltt_session *session,
-       uint64_t cur_nr_packets)
+uint64_t get_session_size_one_more_packet_per_stream(
+               const struct ltt_session *session, uint64_t cur_nr_packets)
 {
        uint64_t tot_size = 0;
 
        if (session->kernel_session) {
                struct ltt_kernel_channel *chan;
-               struct ltt_kernel_session *ksess = session->kernel_session;
+               const struct ltt_kernel_session *ksess =
+                               session->kernel_session;
 
                cds_list_for_each_entry(chan, &ksess->channel_list.head, list) {
                        if (cur_nr_packets >= chan->channel->attr.num_subbuf) {
@@ -4114,7 +4485,7 @@ uint64_t get_session_size_one_more_packet_per_stream(struct ltt_session *session
        }
 
        if (session->ust_session) {
-               struct ltt_ust_session *usess = session->ust_session;
+               const struct ltt_ust_session *usess = session->ust_session;
 
                tot_size += ust_app_get_size_one_more_packet_per_stream(usess,
                                cur_nr_packets);
@@ -4144,7 +4515,8 @@ uint64_t get_session_size_one_more_packet_per_stream(struct ltt_session *session
  * in between this call and actually grabbing data.
  */
 static
-int64_t get_session_nb_packets_per_stream(struct ltt_session *session, uint64_t max_size)
+int64_t get_session_nb_packets_per_stream(const struct ltt_session *session,
+               uint64_t max_size)
 {
        int64_t size_left;
        uint64_t cur_nb_packets = 0;
@@ -4157,8 +4529,8 @@ int64_t get_session_nb_packets_per_stream(struct ltt_session *session, uint64_t
        for (;;) {
                uint64_t one_more_packet_tot_size;
 
-               one_more_packet_tot_size = get_session_size_one_more_packet_per_stream(session,
-                                       cur_nb_packets);
+               one_more_packet_tot_size = get_session_size_one_more_packet_per_stream(
+                               session, cur_nb_packets);
                if (!one_more_packet_tot_size) {
                        /* We are already grabbing all packets. */
                        break;
@@ -4176,6 +4548,161 @@ int64_t get_session_nb_packets_per_stream(struct ltt_session *session, uint64_t
        return cur_nb_packets;
 }
 
+static
+enum lttng_error_code snapshot_record(struct ltt_session *session,
+               const struct snapshot_output *snapshot_output, int wait)
+{
+       int64_t nb_packets_per_stream;
+       char snapshot_chunk_name[LTTNG_NAME_MAX];
+       int ret;
+       enum lttng_error_code ret_code = LTTNG_OK;
+       struct lttng_trace_chunk *snapshot_trace_chunk;
+       struct consumer_output *original_ust_consumer_output = NULL;
+       struct consumer_output *original_kernel_consumer_output = NULL;
+       struct consumer_output *snapshot_ust_consumer_output = NULL;
+       struct consumer_output *snapshot_kernel_consumer_output = NULL;
+
+       ret = snprintf(snapshot_chunk_name, sizeof(snapshot_chunk_name),
+                       "%s-%s-%" PRIu64,
+                       snapshot_output->name,
+                       snapshot_output->datetime,
+                       snapshot_output->nb_snapshot);
+       if (ret < 0 || ret >= sizeof(snapshot_chunk_name)) {
+               ERR("Failed to format snapshot name");
+               ret_code = LTTNG_ERR_INVALID;
+               goto error;
+       }
+       DBG("Recording snapshot \"%s\" for session \"%s\" with chunk name \"%s\"",
+                       snapshot_output->name, session->name,
+                       snapshot_chunk_name);
+       if (!session->kernel_session && !session->ust_session) {
+               ERR("Failed to record snapshot as no channels exist");
+               ret_code = LTTNG_ERR_NO_CHANNEL;
+               goto error;
+       }
+
+       if (session->kernel_session) {
+               original_kernel_consumer_output =
+                               session->kernel_session->consumer;
+               snapshot_kernel_consumer_output =
+                               consumer_copy_output(snapshot_output->consumer);
+               strcpy(snapshot_kernel_consumer_output->chunk_path,
+                       snapshot_chunk_name);
+               ret = consumer_copy_sockets(snapshot_kernel_consumer_output,
+                               original_kernel_consumer_output);
+               if (ret < 0) {
+                       ERR("Failed to copy consumer sockets from snapshot output configuration");
+                       ret_code = LTTNG_ERR_NOMEM;
+                       goto error;
+               }
+               ret_code = set_relayd_for_snapshot(
+                               snapshot_kernel_consumer_output, session);
+               if (ret_code != LTTNG_OK) {
+                       ERR("Failed to setup relay daemon for kernel tracer snapshot");
+                       goto error;
+               }
+               session->kernel_session->consumer =
+                               snapshot_kernel_consumer_output;
+       }
+       if (session->ust_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);
+               ret = consumer_copy_sockets(snapshot_ust_consumer_output,
+                               original_ust_consumer_output);
+               if (ret < 0) {
+                       ERR("Failed to copy consumer sockets from snapshot output configuration");
+                       ret_code = LTTNG_ERR_NOMEM;
+                       goto error;
+               }
+               ret_code = set_relayd_for_snapshot(
+                               snapshot_ust_consumer_output, session);
+               if (ret_code != LTTNG_OK) {
+                       ERR("Failed to setup relay daemon for userspace tracer snapshot");
+                       goto error;
+               }
+               session->ust_session->consumer =
+                               snapshot_ust_consumer_output;
+       }
+
+       snapshot_trace_chunk = session_create_new_trace_chunk(session,
+                       snapshot_kernel_consumer_output ?:
+                                       snapshot_ust_consumer_output,
+                       consumer_output_get_base_path(
+                                       snapshot_output->consumer),
+                       snapshot_chunk_name);
+       if (!snapshot_trace_chunk) {
+               ERR("Failed to create temporary trace chunk to record a snapshot of session \"%s\"",
+                               session->name);
+               ret_code = LTTNG_ERR_CREATE_DIR_FAIL;
+               goto error;
+       }
+       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;
+       if (ret) {
+               ERR("Failed to set temporary trace chunk to record a snapshot of session \"%s\"",
+                               session->name);
+               ret_code = LTTNG_ERR_CREATE_TRACE_CHUNK_FAIL_CONSUMER;
+               goto error;
+       }
+
+       nb_packets_per_stream = get_session_nb_packets_per_stream(session,
+                       snapshot_output->max_size);
+       if (nb_packets_per_stream < 0) {
+               ret_code = LTTNG_ERR_MAX_SIZE_INVALID;
+               goto error;
+       }
+
+       if (session->kernel_session) {
+               ret_code = record_kernel_snapshot(session->kernel_session,
+                               snapshot_kernel_consumer_output, session,
+                               wait, nb_packets_per_stream);
+               if (ret_code != LTTNG_OK) {
+                       goto error;
+               }
+       }
+
+       if (session->ust_session) {
+               ret_code = record_ust_snapshot(session->ust_session,
+                               snapshot_ust_consumer_output, session,
+                               wait, nb_packets_per_stream);
+               if (ret_code != LTTNG_OK) {
+                       goto error;
+               }
+       }
+
+       if (session_close_trace_chunk(
+                           session, session->current_trace_chunk, NULL, NULL)) {
+               /*
+                * Don't goto end; make sure the chunk is closed for the session
+                * to allow future snapshots.
+                */
+               ERR("Failed to close snapshot trace chunk of session \"%s\"",
+                               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;
+       }
+       if (original_kernel_consumer_output) {
+               session->kernel_session->consumer =
+                               original_kernel_consumer_output;
+       }
+       consumer_output_put(snapshot_ust_consumer_output);
+       consumer_output_put(snapshot_kernel_consumer_output);
+       return ret_code;
+}
+
 /*
  * Command LTTNG_SNAPSHOT_RECORD from lib lttng ctl.
  *
@@ -4185,13 +4712,13 @@ int64_t get_session_nb_packets_per_stream(struct ltt_session *session, uint64_t
  * 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)
 {
-       int ret = LTTNG_OK;
-       unsigned int use_tmp_output = 0;
-       struct snapshot_output tmp_output;
+       enum lttng_error_code cmd_ret = LTTNG_OK;
+       int ret;
        unsigned int snapshot_success = 0;
        char datetime[16];
+       struct snapshot_output *tmp_output = NULL;
 
        assert(session);
        assert(output);
@@ -4202,7 +4729,7 @@ int cmd_snapshot_record(struct ltt_session *session,
        ret = utils_get_current_time_str("%Y%m%d-%H%M%S", datetime,
                        sizeof(datetime));
        if (!ret) {
-               ret = LTTNG_ERR_INVALID;
+               cmd_ret = LTTNG_ERR_INVALID;
                goto error;
        }
 
@@ -4211,65 +4738,46 @@ int cmd_snapshot_record(struct ltt_session *session,
         * set in no output mode.
         */
        if (session->output_traces) {
-               ret = LTTNG_ERR_NOT_SNAPSHOT_SESSION;
+               cmd_ret = LTTNG_ERR_NOT_SNAPSHOT_SESSION;
                goto error;
        }
 
        /* The session needs to be started at least once. */
        if (!session->has_been_started) {
-               ret = LTTNG_ERR_START_SESSION_ONCE;
+               cmd_ret = LTTNG_ERR_START_SESSION_ONCE;
                goto error;
        }
 
        /* Use temporary output for the session. */
        if (*output->ctrl_url != '\0') {
-               ret = snapshot_output_init(output->max_size, output->name,
-                               output->ctrl_url, output->data_url, session->consumer,
-                               &tmp_output, NULL);
+               tmp_output = snapshot_output_alloc();
+               if (!tmp_output) {
+                       cmd_ret = LTTNG_ERR_NOMEM;
+                       goto error;
+               }
+
+               ret = snapshot_output_init(session, output->max_size,
+                               output->name,
+                               output->ctrl_url, output->data_url,
+                               session->consumer,
+                               tmp_output, NULL);
                if (ret < 0) {
                        if (ret == -ENOMEM) {
-                               ret = LTTNG_ERR_NOMEM;
+                               cmd_ret = LTTNG_ERR_NOMEM;
                        } else {
-                               ret = LTTNG_ERR_INVALID;
+                               cmd_ret = LTTNG_ERR_INVALID;
                        }
                        goto error;
                }
                /* Use the global session count for the temporary snapshot. */
-               tmp_output.nb_snapshot = session->snapshot.nb_snapshot;
+               tmp_output->nb_snapshot = session->snapshot.nb_snapshot;
 
                /* Use the global datetime */
-               memcpy(tmp_output.datetime, datetime, sizeof(datetime));
-               use_tmp_output = 1;
-       }
-
-       if (use_tmp_output) {
-               int64_t nb_packets_per_stream;
-
-               nb_packets_per_stream = get_session_nb_packets_per_stream(session,
-                               tmp_output.max_size);
-               if (nb_packets_per_stream < 0) {
-                       ret = LTTNG_ERR_MAX_SIZE_INVALID;
+               memcpy(tmp_output->datetime, datetime, sizeof(datetime));
+               cmd_ret = snapshot_record(session, tmp_output, wait);
+               if (cmd_ret != LTTNG_OK) {
                        goto error;
                }
-
-               if (session->kernel_session) {
-                       ret = record_kernel_snapshot(session->kernel_session,
-                                       &tmp_output, session,
-                                       wait, nb_packets_per_stream);
-                       if (ret != LTTNG_OK) {
-                               goto error;
-                       }
-               }
-
-               if (session->ust_session) {
-                       ret = record_ust_snapshot(session->ust_session,
-                                       &tmp_output, session,
-                                       wait, nb_packets_per_stream);
-                       if (ret != LTTNG_OK) {
-                               goto error;
-                       }
-               }
-
                snapshot_success = 1;
        } else {
                struct snapshot_output *sout;
@@ -4278,58 +4786,38 @@ int cmd_snapshot_record(struct ltt_session *session,
                rcu_read_lock();
                cds_lfht_for_each_entry(session->snapshot.output_ht->ht,
                                &iter.iter, sout, node.node) {
-                       int64_t nb_packets_per_stream;
+                       struct snapshot_output output_copy;
 
                        /*
-                        * Make a local copy of the output and assign the possible
-                        * temporary value given by the caller.
+                        * Make a local copy of the output and override output
+                        * parameters with those provided as part of the
+                        * command.
                         */
-                       memset(&tmp_output, 0, sizeof(tmp_output));
-                       memcpy(&tmp_output, sout, sizeof(tmp_output));
+                       memcpy(&output_copy, sout, sizeof(output_copy));
 
                        if (output->max_size != (uint64_t) -1ULL) {
-                               tmp_output.max_size = output->max_size;
+                               output_copy.max_size = output->max_size;
                        }
 
-                       nb_packets_per_stream = get_session_nb_packets_per_stream(session,
-                                       tmp_output.max_size);
-                       if (nb_packets_per_stream < 0) {
-                               ret = LTTNG_ERR_MAX_SIZE_INVALID;
-                               rcu_read_unlock();
-                               goto error;
-                       }
+                       output_copy.nb_snapshot = session->snapshot.nb_snapshot;
+                       memcpy(output_copy.datetime, datetime,
+                                       sizeof(datetime));
 
                        /* Use temporary name. */
                        if (*output->name != '\0') {
-                               if (lttng_strncpy(tmp_output.name, output->name,
-                                               sizeof(tmp_output.name))) {
-                                       ret = LTTNG_ERR_INVALID;
-                                       rcu_read_unlock();
-                                       goto error;
-                               }
-                       }
-
-                       tmp_output.nb_snapshot = session->snapshot.nb_snapshot;
-                       memcpy(tmp_output.datetime, datetime, sizeof(datetime));
-
-                       if (session->kernel_session) {
-                               ret = record_kernel_snapshot(session->kernel_session,
-                                               &tmp_output, session,
-                                               wait, nb_packets_per_stream);
-                               if (ret != LTTNG_OK) {
+                               if (lttng_strncpy(output_copy.name,
+                                               output->name,
+                                               sizeof(output_copy.name))) {
+                                       cmd_ret = LTTNG_ERR_INVALID;
                                        rcu_read_unlock();
                                        goto error;
                                }
                        }
 
-                       if (session->ust_session) {
-                               ret = record_ust_snapshot(session->ust_session,
-                                               &tmp_output, session,
-                                               wait, nb_packets_per_stream);
-                               if (ret != LTTNG_OK) {
-                                       rcu_read_unlock();
-                                       goto error;
-                               }
+                       cmd_ret = snapshot_record(session, &output_copy, wait);
+                       if (cmd_ret != LTTNG_OK) {
+                               rcu_read_unlock();
+                               goto error;
                        }
                        snapshot_success = 1;
                }
@@ -4339,11 +4827,14 @@ int cmd_snapshot_record(struct ltt_session *session,
        if (snapshot_success) {
                session->snapshot.nb_snapshot++;
        } else {
-               ret = LTTNG_ERR_SNAPSHOT_FAIL;
+               cmd_ret = LTTNG_ERR_SNAPSHOT_FAIL;
        }
 
 error:
-       return ret;
+       if (tmp_output) {
+               snapshot_output_destroy(tmp_output);
+       }
+       return cmd_ret;
 }
 
 /*
@@ -4375,44 +4866,52 @@ int cmd_set_session_shm_path(struct ltt_session *session,
  * Ask the consumer to rotate the session output directory.
  * The session lock must be held.
  *
- * Return LTTNG_OK on success or else a LTTNG_ERR code.
+ * Returns LTTNG_OK on success or else a negative LTTng error code.
  */
 int cmd_rotate_session(struct ltt_session *session,
-               struct lttng_rotate_session_return *rotate_return)
+               struct lttng_rotate_session_return *rotate_return,
+               bool quiet_rotation)
 {
        int ret;
-       size_t strf_ret;
-       struct tm *timeinfo;
-       char datetime[21];
-       time_t now;
-       bool ust_active = false;
+       uint64_t ongoing_rotation_chunk_id;
+       enum lttng_error_code cmd_ret = LTTNG_OK;
+       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);
 
        if (!session->has_been_started) {
-               ret = -LTTNG_ERR_START_SESSION_ONCE;
+               cmd_ret = LTTNG_ERR_START_SESSION_ONCE;
                goto end;
        }
 
-       if (session->live_timer || session->snapshot_mode ||
+       /*
+        * Explicit rotation is not supported for live sessions.
+        * However, live sessions can perform a quiet rotation on
+        * destroy.
+        * Rotation is not supported for snapshot traces (no output).
+        */
+       if ((!quiet_rotation && session->live_timer) ||
                        !session->output_traces) {
-               ret = -LTTNG_ERR_ROTATION_NOT_AVAILABLE;
+               cmd_ret = LTTNG_ERR_ROTATION_NOT_AVAILABLE;
                goto end;
        }
 
-       /*
-        * Unsupported feature in lttng-relayd before 2.11.
-        */
-       if (session->consumer->type == CONSUMER_DST_NET &&
+       /* Unsupported feature in lttng-relayd before 2.11. */
+       if (!quiet_rotation && session->consumer->type == CONSUMER_DST_NET &&
                        (session->consumer->relay_major_version == 2 &&
                        session->consumer->relay_minor_version < 11)) {
-               ret = -LTTNG_ERR_ROTATION_NOT_AVAILABLE_RELAY;
+               cmd_ret = LTTNG_ERR_ROTATION_NOT_AVAILABLE_RELAY;
                goto end;
        }
 
-       if (session->rotate_pending || session->rotate_pending_relay) {
-               ret = -LTTNG_ERR_ROTATION_PENDING;
-               DBG("Rotate already in progress");
+       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);
+               cmd_ret = LTTNG_ERR_ROTATION_PENDING;
                goto end;
        }
 
@@ -4423,186 +4922,115 @@ int cmd_rotate_session(struct ltt_session *session,
        if (session->rotated_after_last_stop) {
                DBG("Session \"%s\" was already rotated after stop, refusing rotation",
                                session->name);
-               ret = -LTTNG_ERR_ROTATION_MULTIPLE_AFTER_STOP;
+               cmd_ret = LTTNG_ERR_ROTATION_MULTIPLE_AFTER_STOP;
                goto end;
        }
 
-       /* Special case for the first rotation. */
-       if (session->rotate_count == 0) {
-               const char *base_path = NULL;
+       session->rotation_state = LTTNG_ROTATION_STATE_ONGOING;
 
-               /* Either one of the two sessions is enough to get the root path. */
-               if (session->kernel_session) {
-                       base_path = session_get_base_path(session);
-               } else if (session->ust_session) {
-                       base_path = session_get_base_path(session);
-               } else {
-                       assert(0);
-               }
-               assert(base_path);
-               ret = lttng_strncpy(session->rotation_chunk.current_rotate_path,
-                               base_path,
-                               sizeof(session->rotation_chunk.current_rotate_path));
-               if (ret) {
-                       ERR("Failed to copy session base path to current rotation chunk path");
-                       ret = -LTTNG_ERR_UNK;
-                       goto end;
-               }
-       } else {
-               /*
-                * The currently active tracing path is now the folder we
-                * want to rotate.
-                */
-               ret = lttng_strncpy(session->rotation_chunk.current_rotate_path,
-                               session->rotation_chunk.active_tracing_path,
-                               sizeof(session->rotation_chunk.current_rotate_path));
-               if (ret) {
-                       ERR("Failed to copy the active tracing path to the current rotate path");
-                       ret = -LTTNG_ERR_UNK;
-                       goto end;
+       if (session->active) {
+               new_trace_chunk = session_create_new_trace_chunk(session, NULL,
+                               NULL, NULL);
+               if (!new_trace_chunk) {
+                       cmd_ret = LTTNG_ERR_CREATE_DIR_FAIL;
+                       goto error;
                }
-       }
-       DBG("Current rotate path %s", session->rotation_chunk.current_rotate_path);
-
-       session->rotate_count++;
-       session->rotate_pending = true;
-       session->rotation_state = LTTNG_ROTATION_STATE_ONGOING;
+        }
 
        /*
-        * Create the path name for the next chunk.
+        * 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.
         */
-       now = time(NULL);
-       if (now == (time_t) -1) {
-               ret = -LTTNG_ERR_ROTATION_NOT_AVAILABLE;
-               goto end;
+       ret = session_set_trace_chunk(session, new_trace_chunk,
+                       &chunk_being_archived);
+       if (ret) {
+               cmd_ret = LTTNG_ERR_CREATE_TRACE_CHUNK_FAIL_CONSUMER;
+               goto error;
        }
-       session->last_chunk_start_ts = session->current_chunk_start_ts;
-       session->current_chunk_start_ts = now;
 
-       timeinfo = localtime(&now);
-       if (!timeinfo) {
-               PERROR("Failed to sample local time in rotate session command");
-               ret = -LTTNG_ERR_UNK;
-               goto end;
-       }
-       strf_ret = strftime(datetime, sizeof(datetime), "%Y%m%dT%H%M%S%z",
-                       timeinfo);
-       if (!strf_ret) {
-               ERR("Failed to format local time timestamp in rotate session command");
-               ret = -LTTNG_ERR_UNK;
-               goto end;
-       }
+       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) {
-               /*
-                * The active path for the next rotation/destroy.
-                * Ex: ~/lttng-traces/auto-20170922-111748/20170922-111754-42
-                */
-               ret = snprintf(session->rotation_chunk.active_tracing_path,
-                               sizeof(session->rotation_chunk.active_tracing_path),
-                               "%s/%s-%" PRIu64,
-                               session_get_base_path(session),
-                               datetime, session->rotate_count + 1);
-               if (ret < 0 || ret == sizeof(session->rotation_chunk.active_tracing_path)) {
-                       ERR("Failed to format active kernel tracing path in rotate session command");
-                       ret = -LTTNG_ERR_UNK;
-                       goto end;
-               }
-               /*
-                * The sub-directory for the consumer
-                * Ex: /20170922-111754-42/kernel
-                */
-               ret = snprintf(session->kernel_session->consumer->chunk_path,
-                               sizeof(session->kernel_session->consumer->chunk_path),
-                               "/%s-%" PRIu64, datetime,
-                               session->rotate_count + 1);
-               if (ret < 0 || ret == sizeof(session->kernel_session->consumer->chunk_path)) {
-                       ERR("Failed to format the kernel consumer's sub-directory in rotate session command");
-                       ret = -LTTNG_ERR_UNK;
-                       goto end;
-               }
-               /*
-                * Create the new chunk folder, before the rotation begins so we don't
-                * race with the consumer/tracer activity.
-                */
-               ret = domain_mkdir(session->kernel_session->consumer, session,
-                               session->kernel_session->uid,
-                               session->kernel_session->gid);
-               if (ret) {
-                       ERR("Failed to create kernel session tracing path at %s",
-                                       session->kernel_session->consumer->chunk_path);
-                       ret = -LTTNG_ERR_CREATE_DIR_FAIL;
-                       goto end;
-               }
-               ret = kernel_rotate_session(session);
-               if (ret != LTTNG_OK) {
-                       ret = -ret;
-                       goto end;
+               cmd_ret = kernel_rotate_session(session);
+               if (cmd_ret != LTTNG_OK) {
+                       failed_to_rotate = true;
+                       rotation_fail_code = cmd_ret;
                }
        }
        if (session->ust_session) {
-               ret = snprintf(session->rotation_chunk.active_tracing_path,
-                               PATH_MAX, "%s/%s-%" PRIu64,
-                               session_get_base_path(session),
-                               datetime, session->rotate_count + 1);
-               if (ret < 0) {
-                       ERR("Failed to format active UST tracing path in rotate session command");
-                       ret = -LTTNG_ERR_UNK;
-                       goto end;
-               }
-               ret = snprintf(session->ust_session->consumer->chunk_path,
-                               PATH_MAX, "/%s-%" PRIu64, datetime,
-                               session->rotate_count + 1);
-               if (ret < 0) {
-                       ERR("Failed to format the UST consumer's sub-directory in rotate session command");
-                       ret = -LTTNG_ERR_UNK;
-                       goto end;
-               }
-               /*
-                * Create the new chunk folder, before the rotation begins so we don't
-                * race with the consumer/tracer activity.
-                */
-               ret = domain_mkdir(session->ust_session->consumer, session,
-                               session->ust_session->uid,
-                               session->ust_session->gid);
-               if (ret) {
-                       ret = -LTTNG_ERR_CREATE_DIR_FAIL;
-                       goto end;
-               }
-               ret = ust_app_rotate_session(session, &ust_active);
-               if (ret != LTTNG_OK) {
-                       goto end;
-               }
-               /*
-                * Handle the case where we did not start a rotation on any channel.
-                * The consumer will never wake up the rotation thread to perform the
-                * rename, so we have to do it here while we hold the session and
-                * session_list locks.
-                */
-               if (!session->kernel_session && !ust_active) {
-                       ret = rename_complete_chunk(session, now);
-                       if (ret < 0) {
-                               ERR("Failed to rename completed rotation chunk");
-                               goto end;
-                       }
-                       session->rotate_pending = false;
-                       session->rotation_state = LTTNG_ROTATION_STATE_COMPLETED;
+               cmd_ret = ust_app_rotate_session(session);
+               if (cmd_ret != LTTNG_OK) {
+                       failed_to_rotate = true;
+                       rotation_fail_code = cmd_ret;
                }
        }
 
+       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}),
+                       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);
+       if (ret) {
+               cmd_ret = LTTNG_ERR_UNK;
+               goto error;
+       }
+
        if (!session->active) {
                session->rotated_after_last_stop = true;
        }
 
        if (rotate_return) {
-               rotate_return->rotation_id = session->rotate_count;
+               rotate_return->rotation_id = ongoing_rotation_chunk_id;
        }
 
-       DBG("Cmd rotate session %s, rotate_id %" PRIu64 " sent", session->name,
-                       session->rotate_count);
-       ret = LTTNG_OK;
+       session->chunk_being_archived = chunk_being_archived;
+       chunk_being_archived = NULL;
+       if (!quiet_rotation) {
+               ret = notification_thread_command_session_rotation_ongoing(
+                               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",
+                                       session->name);
+                       cmd_ret = ret;
+               }
+       }
 
+       DBG("Cmd rotate session %s, archive_id %" PRIu64 " sent",
+                       session->name, ongoing_rotation_chunk_id);
 end:
+       lttng_trace_chunk_put(new_trace_chunk);
+       lttng_trace_chunk_put(chunk_being_archived);
+       ret = (cmd_ret == LTTNG_OK) ? cmd_ret : -((int) cmd_ret);
        return ret;
+error:
+       if (session_reset_rotation_state(session,
+                       LTTNG_ROTATION_STATE_ERROR)) {
+               ERR("Failed to reset rotation state of session \"%s\"",
+                               session->name);
+       }
+       goto end;
 }
 
 /*
@@ -4610,140 +5038,283 @@ end:
  *
  * Check if the session has finished its rotation.
  *
- * Return 0 on success or else a LTTNG_ERR code.
+ * Return LTTNG_OK on success or else an LTTNG_ERR code.
  */
 int cmd_rotate_get_info(struct ltt_session *session,
                struct lttng_rotation_get_info_return *info_return,
                uint64_t rotation_id)
 {
-       int ret;
-
-       assert(session);
+       enum lttng_error_code cmd_ret = LTTNG_OK;
+       enum lttng_rotation_state rotation_state;
 
        DBG("Cmd rotate_get_info session %s, rotation id %" PRIu64, session->name,
-                       session->rotate_count);
+                       session->most_recent_chunk_id.value);
 
-       if (session->rotate_count != rotation_id) {
-               info_return->status = (int32_t) LTTNG_ROTATION_STATE_EXPIRED;
-               ret = LTTNG_OK;
-               goto end;
+       if (session->chunk_being_archived) {
+               enum lttng_trace_chunk_status chunk_status;
+               uint64_t chunk_id;
+
+               chunk_status = lttng_trace_chunk_get_id(
+                               session->chunk_being_archived,
+                               &chunk_id);
+               assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
+
+               rotation_state = rotation_id == chunk_id ?
+                               LTTNG_ROTATION_STATE_ONGOING :
+                               LTTNG_ROTATION_STATE_EXPIRED;
+       } else {
+               if (session->last_archived_chunk_id.is_set &&
+                               rotation_id != session->last_archived_chunk_id.value) {
+                       rotation_state = LTTNG_ROTATION_STATE_EXPIRED;
+               } else {
+                       rotation_state = session->rotation_state;
+               }
        }
 
-       switch (session->rotation_state) {
+       switch (rotation_state) {
+       case LTTNG_ROTATION_STATE_NO_ROTATION:
+               DBG("Reporting that no rotation has occurred within the lifetime of session \"%s\"",
+                               session->name);
+               goto end;
+       case LTTNG_ROTATION_STATE_EXPIRED:
+               DBG("Reporting that the rotation state of rotation id %" PRIu64 " of session \"%s\" has expired",
+                               rotation_id, session->name);
+               break;
        case LTTNG_ROTATION_STATE_ONGOING:
-               DBG("Reporting that rotation id %" PRIu64 " of session %s is still pending",
+               DBG("Reporting that rotation id %" PRIu64 " of session \"%s\" is still pending",
                                rotation_id, session->name);
                break;
        case LTTNG_ROTATION_STATE_COMPLETED:
-               ret = lttng_strncpy(info_return->path,
-                               session->rotation_chunk.current_rotate_path,
-                               sizeof(info_return->path));
-               if (ret) {
-                       ERR("Failed to copy active tracing path to rotate_get_info reply");
+       {
+               int fmt_ret;
+               char *chunk_path;
+               char *current_tracing_path_reply;
+               size_t current_tracing_path_reply_len;
+
+               DBG("Reporting that rotation id %" PRIu64 " of session \"%s\" is completed",
+                               rotation_id, session->name);
+
+               switch (session_get_consumer_destination_type(session)) {
+               case CONSUMER_DST_LOCAL:
+                       current_tracing_path_reply =
+                                       info_return->location.local.absolute_path;
+                       current_tracing_path_reply_len =
+                                       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 =
+                                       sizeof(info_return->location.relay.relative_path);
+                       /* Currently the only supported relay protocol. */
+                       info_return->location.relay.protocol =
+                                       (int8_t) LTTNG_TRACE_ARCHIVE_LOCATION_RELAY_PROTOCOL_TYPE_TCP;
+
+                       fmt_ret = lttng_strncpy(info_return->location.relay.host,
+                                       session_get_net_consumer_hostname(session),
+                                       sizeof(info_return->location.relay.host));
+                       if (fmt_ret) {
+                               ERR("Failed to copy host name to rotate_get_info reply");
+                               info_return->status = LTTNG_ROTATION_STATUS_ERROR;
+                               cmd_ret = LTTNG_ERR_SET_URL;
+                               goto end;
+                       }
+
+                       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 = lttng_strncpy(current_tracing_path_reply,
+                               chunk_path, current_tracing_path_reply_len);
+               free(chunk_path);
+               if (fmt_ret) {
+                       ERR("Failed to copy path of the last archived trace chunk to rotate_get_info reply");
                        info_return->status = LTTNG_ROTATION_STATUS_ERROR;
-                       ret = -LTTNG_ERR_UNK;
+                       cmd_ret = LTTNG_ERR_UNK;
                        goto end;
                }
+
                break;
+       }
        case LTTNG_ROTATION_STATE_ERROR:
-               DBG("Reporting that an error occurred during rotation %" PRIu64 " of session %s",
+               DBG("Reporting that an error occurred during rotation %" PRIu64 " of session \"%s\"",
                                rotation_id, session->name);
                break;
        default:
                abort();
        }
 
-       info_return->status = (int32_t) session->rotation_state;
-       ret = LTTNG_OK;
+       cmd_ret = LTTNG_OK;
 end:
-       return ret;
+       info_return->status = (int32_t) rotation_state;
+       return cmd_ret;
 }
 
 /*
  * Command LTTNG_ROTATION_SET_SCHEDULE from the lttng-ctl library.
  *
  * Configure the automatic rotation parameters.
- * Set to -1ULL to disable them.
+ * 'activate' to true means activate the rotation schedule type with 'new_value'.
+ * '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 an LTTNG_ERR code.
+ * Return 0 on success or else a positive LTTNG_ERR code.
  */
 int cmd_rotation_set_schedule(struct ltt_session *session,
-               uint64_t timer_us, uint64_t size,
+               bool activate, enum lttng_rotation_schedule_type schedule_type,
+               uint64_t new_value,
                struct notification_thread_handle *notification_thread_handle)
 {
        int ret;
+       uint64_t *parameter_value;
 
        assert(session);
 
        DBG("Cmd rotate set schedule session %s", session->name);
 
-       if (session->live_timer || session->snapshot_mode ||
-                       !session->output_traces) {
+       if (session->live_timer || !session->output_traces) {
+               DBG("Failing ROTATION_SET_SCHEDULE command as the rotation feature is not available for this session");
                ret = LTTNG_ERR_ROTATION_NOT_AVAILABLE;
                goto end;
        }
 
-       /* Trying to override an already active timer. */
-       if (timer_us && timer_us != -1ULL && session->rotate_timer_period) {
-               ret = LTTNG_ERR_ROTATION_TIMER_SET;
+       switch (schedule_type) {
+       case LTTNG_ROTATION_SCHEDULE_TYPE_SIZE_THRESHOLD:
+               parameter_value = &session->rotate_size;
+               break;
+       case LTTNG_ROTATION_SCHEDULE_TYPE_PERIODIC:
+               parameter_value = &session->rotate_timer_period;
+               if (new_value >= UINT_MAX) {
+                       DBG("Failing ROTATION_SET_SCHEDULE command as the value requested for a periodic rotation schedule is invalid: %" PRIu64 " > %u (UINT_MAX)",
+                                       new_value, UINT_MAX);
+                       ret = LTTNG_ERR_INVALID;
+                       goto end;
+               }
+               break;
+       default:
+               WARN("Failing ROTATION_SET_SCHEDULE command on unknown schedule type");
+               ret = LTTNG_ERR_INVALID;
                goto end;
-       /* Trying to disable an inactive timer. */
-       } else if (timer_us == -1ULL && !session->rotate_timer_period) {
-               ret = LTTNG_ERR_ROTATION_NO_TIMER_SET;
+       }
+
+       /* Improper use of the API. */
+       if (new_value == -1ULL) {
+               WARN("Failing ROTATION_SET_SCHEDULE command as the value requested is -1");
+               ret = LTTNG_ERR_INVALID;
+               goto end;
+       }
+
+       /*
+        * As indicated in struct ltt_session's comments, a value of == 0 means
+        * this schedule rotation type is not in use.
+        *
+        * Reject the command if we were asked to activate a schedule that was
+        * already active.
+        */
+       if (activate && *parameter_value != 0) {
+               DBG("Failing ROTATION_SET_SCHEDULE (activate) command as the schedule is already active");
+               ret = LTTNG_ERR_ROTATION_SCHEDULE_SET;
                goto end;
        }
 
-       if (size && size != -1ULL && session->rotate_size) {
-               ret = LTTNG_ERR_ROTATION_SIZE_SET;
+       /*
+        * Reject the command if we were asked to deactivate a schedule that was
+        * not active.
+        */
+       if (!activate && *parameter_value == 0) {
+               DBG("Failing ROTATION_SET_SCHEDULE (deactivate) command as the schedule is already inactive");
+               ret = LTTNG_ERR_ROTATION_SCHEDULE_NOT_SET;
                goto end;
-       } else if (size == -1ULL && !session->rotate_size) {
-               ret = LTTNG_ERR_ROTATION_NO_SIZE_SET;
+       }
+
+       /*
+        * Reject the command if we were asked to deactivate a schedule that
+        * doesn't exist.
+        */
+       if (!activate && *parameter_value != new_value) {
+               DBG("Failing ROTATION_SET_SCHEDULE (deactivate) command as an inexistant schedule was provided");
+               ret = LTTNG_ERR_ROTATION_SCHEDULE_NOT_SET;
                goto end;
        }
 
-       if (timer_us && !session->rotate_timer_period) {
-               if (timer_us > UINT_MAX) {
-                       ret = LTTNG_ERR_INVALID;
-                       goto end;
-               }
+       *parameter_value = activate ? new_value : 0;
 
-               session->rotate_timer_period = timer_us;
-               /*
-                * Only start the timer if the session is active, otherwise
-                * it will be started when the session starts.
-                */
-               if (session->active) {
-                       ret = sessiond_rotate_timer_start(session, timer_us);
+       switch (schedule_type) {
+       case LTTNG_ROTATION_SCHEDULE_TYPE_PERIODIC:
+               if (activate && session->active) {
+                       /*
+                        * Only start the timer if the session is active,
+                        * otherwise it will be started when the session starts.
+                        */
+                       ret = timer_session_rotation_schedule_timer_start(
+                                       session, new_value);
+                       if (ret) {
+                               ERR("Failed to enable session rotation timer in ROTATION_SET_SCHEDULE command");
+                               ret = LTTNG_ERR_UNK;
+                               goto end;
+                       }
+               } else {
+                       ret = timer_session_rotation_schedule_timer_stop(
+                                       session);
                        if (ret) {
-                               ERR("Failed to enable rotate timer");
+                               ERR("Failed to disable session rotation timer in ROTATION_SET_SCHEDULE command");
                                ret = LTTNG_ERR_UNK;
                                goto end;
                        }
                }
-       } else if (timer_us == -1ULL && session->rotate_timer_period > 0) {
-               sessiond_rotate_timer_stop(session);
-               session->rotate_timer_period = 0;
-       }
-
-       if (size > 0) {
-               if (size == -1ULL) {
-                       ret = unsubscribe_session_consumed_size_rotation(session,
-                                       notification_thread_handle);
+               break;
+       case LTTNG_ROTATION_SCHEDULE_TYPE_SIZE_THRESHOLD:
+               if (activate) {
+                       ret = subscribe_session_consumed_size_rotation(session,
+                                       new_value, notification_thread_handle);
                        if (ret) {
+                               ERR("Failed to enable consumed-size notification in ROTATION_SET_SCHEDULE command");
                                ret = LTTNG_ERR_UNK;
                                goto end;
                        }
-                       session->rotate_size = 0;
                } else {
-                       ret = subscribe_session_consumed_size_rotation(session,
-                                       size, notification_thread_handle);
+                       ret = unsubscribe_session_consumed_size_rotation(session,
+                                       notification_thread_handle);
                        if (ret) {
-                               PERROR("Subscribe to session usage");
+                               ERR("Failed to disable consumed-size notification in ROTATION_SET_SCHEDULE command");
                                ret = LTTNG_ERR_UNK;
                                goto end;
                        }
-                       session->rotate_size = size;
+
                }
+               break;
+       default:
+               /* Would have been caught before. */
+               abort();
        }
 
        ret = LTTNG_OK;
@@ -4754,56 +5325,47 @@ end:
        return ret;
 }
 
-/*
- * Command ROTATE_GET_CURRENT_PATH from the lttng-ctl library.
- *
- * Configure the automatic rotation parameters.
- * Set to -1ULL to disable them.
- *
- * Return LTTNG_OK on success or else a LTTNG_ERR code.
- */
-int cmd_session_get_current_output(struct ltt_session *session,
-               struct lttng_session_get_current_output_return *output_return)
+/* Wait for a given path to be removed before continuing. */
+static enum lttng_error_code wait_on_path(void *path_data)
 {
-       int ret;
-       const char *path;
-
-       if (!session->snapshot_mode) {
-               if (session->rotate_count == 0) {
-                       if (session->kernel_session) {
-                               path = session_get_base_path(session);
-                       } else if (session->ust_session) {
-                               path = session_get_base_path(session);
+       const char *shm_path = path_data;
+
+       DBG("Waiting for the shm path at %s to be removed before completing session destruction",
+                       shm_path);
+       while (true) {
+               int ret;
+               struct stat st;
+
+               ret = stat(shm_path, &st);
+               if (ret) {
+                       if (errno != ENOENT) {
+                               PERROR("stat() returned an error while checking for the existence of the shm path");
                        } else {
-                               abort();
+                               DBG("shm path no longer exists, completing the destruction of session");
                        }
-                       assert(path);
+                       break;
                } else {
-                       path = session->rotation_chunk.active_tracing_path;
+                       if (!S_ISDIR(st.st_mode)) {
+                               ERR("The type of shm path %s returned by stat() is not a directory; aborting the wait for shm path removal",
+                                               shm_path);
+                               break;
+                       }
                }
-       } else {
-               /*
-                * A snapshot session does not have a "current" trace archive
-                * location.
-                */
-               path = "";
+               usleep(SESSION_DESTROY_SHM_PATH_CHECK_DELAY_US);
        }
+       return LTTNG_OK;
+}
 
-       DBG("Cmd get current output for session %s, returning %s",
-                       session->name, path);
-
-       ret = lttng_strncpy(output_return->path,
-                       path,
-                       sizeof(output_return->path));
-       if (ret) {
-               ERR("Failed to copy trace output path to session get current output command reply");
-               ret = -LTTNG_ERR_UNK;
-               goto end;
-       }
+/*
+ * Returns a pointer to a handler to run on completion of a command.
+ * Returns NULL if no handler has to be run for the last command executed.
+ */
+const struct cmd_completion_handler *cmd_pop_completion_handler(void)
+{
+       struct cmd_completion_handler *handler = current_completion_handler;
 
-       ret = LTTNG_OK;
-end:
-       return ret;
+       current_completion_handler = NULL;
+       return handler;
 }
 
 /*
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