Dedicated error message when relay does not support rotations
[lttng-tools.git] / src / bin / lttng-sessiond / cmd.c
index aa030d3b1253f45a716cfa2386c8282c2173611a..e0a8db9b2cc13a2b5c77407e0b14938fa565a587 100644 (file)
 #include <common/utils.h>
 #include <common/compat/string.h>
 #include <common/kernel-ctl/kernel-ctl.h>
+#include <common/dynamic-buffer.h>
+#include <common/buffer-view.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 <common/string-utils/string-utils.h>
 
 #include "channel.h"
 #include "consumer.h"
 #include "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 "cmd.h"
 
@@ -53,7 +67,6 @@
 static pthread_mutex_t relayd_net_seq_idx_lock = PTHREAD_MUTEX_INITIALIZER;
 static uint64_t relayd_net_seq_idx;
 
-static int validate_event_name(const char *);
 static int validate_ust_event_name(const char *);
 static int cmd_enable_event_internal(struct ltt_session *session,
                struct lttng_domain *domain,
@@ -158,14 +171,14 @@ static int get_kernel_runtime_stats(struct ltt_session *session,
                goto end;
        }
 
-       ret = consumer_get_discarded_events(session->id, kchan->fd,
+       ret = consumer_get_discarded_events(session->id, kchan->key,
                        session->kernel_session->consumer,
                        discarded_events);
        if (ret < 0) {
                goto end;
        }
 
-       ret = consumer_get_lost_packets(session->id, kchan->fd,
+       ret = consumer_get_lost_packets(session->id, kchan->key,
                        session->kernel_session->consumer,
                        lost_packets);
        if (ret < 0) {
@@ -187,7 +200,14 @@ static int get_ust_runtime_stats(struct ltt_session *session,
        int ret;
        struct ltt_ust_session *usess;
 
+       if (!discarded_events || !lost_packets) {
+               ret = -1;
+               goto end;
+       }
+
        usess = session->ust_session;
+       assert(discarded_events);
+       assert(lost_packets);
 
        if (!usess || !session->has_been_started) {
                *discarded_events = 0;
@@ -228,11 +248,11 @@ end:
 /*
  * Fill lttng_channel array of all channels.
  */
-static void list_lttng_channels(enum lttng_domain_type domain,
+static ssize_t list_lttng_channels(enum lttng_domain_type domain,
                struct ltt_session *session, struct lttng_channel *channels,
-               struct lttcomm_channel_extended *chan_exts)
+               struct lttng_channel_extended *chan_exts)
 {
-       int i = 0, ret;
+       int i = 0, ret = 0;
        struct ltt_kernel_channel *kchan;
 
        DBG("Listing channels for session %s", session->name);
@@ -244,6 +264,10 @@ static void list_lttng_channels(enum lttng_domain_type domain,
                        cds_list_for_each_entry(kchan,
                                        &session->kernel_session->channel_list.head, list) {
                                uint64_t discarded_events, lost_packets;
+                               struct lttng_channel_extended *extended;
+
+                               extended = (struct lttng_channel_extended *)
+                                               kchan->channel->attr.extended.ptr;
 
                                ret = get_kernel_runtime_stats(session, kchan,
                                                &discarded_events, &lost_packets);
@@ -256,6 +280,9 @@ static void list_lttng_channels(enum lttng_domain_type domain,
                                chan_exts[i].discarded_events =
                                                discarded_events;
                                chan_exts[i].lost_packets = lost_packets;
+                               chan_exts[i].monitor_timer_interval =
+                                               extended->monitor_timer_interval;
+                               chan_exts[i].blocking_timeout = 0;
                                i++;
                        }
                }
@@ -268,9 +295,12 @@ static void list_lttng_channels(enum lttng_domain_type domain,
                rcu_read_lock();
                cds_lfht_for_each_entry(session->ust_session->domain_global.channels->ht,
                                &iter.iter, uchan, node.node) {
-                       uint64_t discarded_events, lost_packets;
+                       uint64_t discarded_events = 0, lost_packets = 0;
 
-                       strncpy(channels[i].name, uchan->name, LTTNG_SYMBOL_NAME_LEN);
+                       if (lttng_strncpy(channels[i].name, uchan->name,
+                                       LTTNG_SYMBOL_NAME_LEN)) {
+                               break;
+                       }
                        channels[i].attr.overwrite = uchan->attr.overwrite;
                        channels[i].attr.subbuf_size = uchan->attr.subbuf_size;
                        channels[i].attr.num_subbuf = uchan->attr.num_subbuf;
@@ -298,6 +328,11 @@ static void list_lttng_channels(enum lttng_domain_type domain,
                                break;
                        }
 
+                       chan_exts[i].monitor_timer_interval =
+                                       uchan->monitor_timer_interval;
+                       chan_exts[i].blocking_timeout =
+                               uchan->attr.u.s.blocking_timeout;
+
                        ret = get_ust_runtime_stats(session, uchan,
                                        &discarded_events, &lost_packets);
                        if (ret < 0) {
@@ -315,7 +350,11 @@ static void list_lttng_channels(enum lttng_domain_type domain,
        }
 
 end:
-       return;
+       if (ret < 0) {
+               return -LTTNG_ERR_FATAL;
+       } else {
+               return LTTNG_OK;
+       }
 }
 
 static void increment_extended_len(const char *filter_expression,
@@ -749,14 +788,17 @@ static int add_uri_to_consumer(struct consumer_output *consumer,
                break;
        case LTTNG_DST_PATH:
                DBG2("Setting trace directory path from URI to %s", uri->dst.path);
-               memset(consumer->dst.trace_path, 0,
-                               sizeof(consumer->dst.trace_path));
-               strncpy(consumer->dst.trace_path, uri->dst.path,
-                               sizeof(consumer->dst.trace_path));
+               memset(consumer->dst.session_root_path, 0,
+                               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;
+                       goto error;
+               }
+               strcpy(consumer->dst.session_root_path, uri->dst.path);
                /* Append default trace dir */
-               strncat(consumer->dst.trace_path, default_trace_dir,
-                               sizeof(consumer->dst.trace_path) -
-                               strlen(consumer->dst.trace_path) - 1);
+               strcat(consumer->dst.session_root_path, default_trace_dir);
                /* Flag consumer as local. */
                consumer->type = CONSUMER_DST_LOCAL;
                break;
@@ -839,8 +881,11 @@ static int create_connect_relayd(struct lttng_uri *uri,
 
                /* Check relayd version */
                ret = relayd_version_check(rsock);
-               if (ret < 0) {
-                       ret = LTTNG_ERR_RELAYD_VERSION_FAIL;
+               if (ret == LTTNG_ERR_RELAYD_VERSION_FAIL) {
+                       goto close_sock;
+               } else if (ret < 0) {
+                       ERR("Unable to reach lttng-relayd");
+                       ret = LTTNG_ERR_RELAYD_CONNECT_FAIL;
                        goto close_sock;
                }
                consumer->relay_major_version = rsock->major;
@@ -869,6 +914,8 @@ error:
 
 /*
  * Connect to the relayd using URI and send the socket to the right consumer.
+ *
+ * The consumer socket lock must be held by the caller.
  */
 static int send_consumer_relayd_socket(enum lttng_domain_type domain,
                unsigned int session_id, struct lttng_uri *relayd_uri,
@@ -882,7 +929,7 @@ static int send_consumer_relayd_socket(enum lttng_domain_type domain,
        /* Connect to relayd and make version check if uri is the control. */
        ret = create_connect_relayd(relayd_uri, &rsock, consumer);
        if (ret != LTTNG_OK) {
-               goto error;
+               goto relayd_comm_error;
        }
        assert(rsock);
 
@@ -922,10 +969,6 @@ static int send_consumer_relayd_socket(enum lttng_domain_type domain,
         */
 
 close_sock:
-       (void) relayd_close(rsock);
-       free(rsock);
-
-error:
        if (ret != LTTNG_OK) {
                /*
                 * The consumer output for this session should not be used anymore
@@ -934,6 +977,10 @@ error:
                 */
                consumer->enabled = 0;
        }
+       (void) relayd_close(rsock);
+       free(rsock);
+
+relayd_comm_error:
        return ret;
 }
 
@@ -941,6 +988,8 @@ error:
  * Send both relayd sockets to a specific consumer and domain.  This is a
  * helper function to facilitate sending the information to the consumer for a
  * session.
+ *
+ * The consumer socket lock must be held by the caller.
  */
 static int send_consumer_relayd_sockets(enum lttng_domain_type domain,
                unsigned int session_id, struct consumer_output *consumer,
@@ -1320,13 +1369,27 @@ int cmd_enable_channel(struct ltt_session *session,
                attr->attr.switch_timer_interval = 0;
        }
 
-       /*
-        * The ringbuffer (both in user space and kernel) behave badly in overwrite
-        * mode and with less than 2 subbuf so block it right away and send back an
-        * invalid attribute error.
-        */
-       if (attr->attr.overwrite && attr->attr.num_subbuf < 2) {
-               ret = LTTNG_ERR_INVALID;
+       /* Check for feature support */
+       switch (domain->type) {
+       case LTTNG_DOMAIN_KERNEL:
+       {
+               if (kernel_supports_ring_buffer_snapshot_sample_positions(kernel_tracer_fd) != 1) {
+                       /* Sampling position of buffer is not supported */
+                       WARN("Kernel tracer does not support buffer monitoring. "
+                                       "Setting the monitor interval timer to 0 "
+                                       "(disabled) for channel '%s' of session '%s'",
+                                       attr-> name, session->name);
+                       lttng_channel_set_monitor_timer_interval(attr, 0);
+               }
+               break;
+       }
+       case LTTNG_DOMAIN_UST:
+       case LTTNG_DOMAIN_JUL:
+       case LTTNG_DOMAIN_LOG4J:
+       case LTTNG_DOMAIN_PYTHON:
+               break;
+       default:
+               ret = LTTNG_ERR_UNKNOWN_DOMAIN;
                goto error;
        }
 
@@ -1425,10 +1488,6 @@ int cmd_disable_event(struct ltt_session *session,
        DBG("Disable event command for event \'%s\'", event->name);
 
        event_name = event->name;
-       if (validate_event_name(event_name)) {
-               ret = LTTNG_ERR_INVALID_EVENT_NAME;
-               goto error;
-       }
 
        /* Error out on unhandled search criteria */
        if (event->loglevel_type || event->loglevel != -1 || event->enabled
@@ -1602,6 +1661,16 @@ int cmd_add_context(struct ltt_session *session, enum lttng_domain_type domain,
        int ret, chan_kern_created = 0, chan_ust_created = 0;
        char *app_ctx_provider_name = NULL, *app_ctx_name = NULL;
 
+       /*
+        * Don't try to add a context if the session has been started at
+        * some point in time before. The tracer does not allow it and would
+        * result in a corrupted trace.
+        */
+       if (session->has_been_started) {
+               ret = LTTNG_ERR_TRACE_ALREADY_STARTED;
+               goto end;
+       }
+
        if (ctx->ctx == LTTNG_EVENT_CONTEXT_APP_CONTEXT) {
                app_ctx_provider_name = ctx->u.app_ctx.provider_name;
                app_ctx_name = ctx->u.app_ctx.ctx_name;
@@ -1670,7 +1739,7 @@ int cmd_add_context(struct ltt_session *session, enum lttng_domain_type domain,
                                free(attr);
                                goto error;
                        }
-                       free(attr);
+                       channel_attr_destroy(attr);
                        chan_ust_created = 1;
                }
 
@@ -1720,43 +1789,6 @@ end:
        return ret;
 }
 
-static int validate_event_name(const char *name)
-{
-       int ret = 0;
-       const char *c = name;
-       const char *event_name_end = c + LTTNG_SYMBOL_NAME_LEN;
-       bool null_terminated = false;
-
-       /*
-        * Make sure that unescaped wildcards are only used as the last
-        * character of the event name.
-        */
-       while (c < event_name_end) {
-               switch (*c) {
-               case '\0':
-                       null_terminated = true;
-                       goto end;
-               case '\\':
-                       c++;
-                       break;
-               case '*':
-                       if ((c + 1) < event_name_end && *(c + 1)) {
-                               /* Wildcard is not the last character */
-                               ret = LTTNG_ERR_INVALID_EVENT_NAME;
-                               goto end;
-                       }
-               default:
-                       break;
-               }
-               c++;
-       }
-end:
-       if (!ret && !null_terminated) {
-               ret = LTTNG_ERR_INVALID_EVENT_NAME;
-       }
-       return ret;
-}
-
 static inline bool name_starts_with(const char *name, const char *prefix)
 {
        const size_t max_cmp_len = min(strlen(prefix), LTTNG_SYMBOL_NAME_LEN);
@@ -1802,8 +1834,8 @@ static int _cmd_enable_event(struct ltt_session *session,
                struct lttng_event_exclusion *exclusion,
                int wpipe, bool internal_event)
 {
-       int ret, channel_created = 0;
-       struct lttng_channel *attr;
+       int ret = 0, channel_created = 0;
+       struct lttng_channel *attr = NULL;
 
        assert(session);
        assert(event);
@@ -1812,15 +1844,24 @@ static int _cmd_enable_event(struct ltt_session *session,
        /* If we have a filter, we must have its filter expression */
        assert(!(!!filter_expression ^ !!filter));
 
-       DBG("Enable event command for event \'%s\'", event->name);
+       /* Normalize event name as a globbing pattern */
+       strutils_normalize_star_glob_pattern(event->name);
 
-       rcu_read_lock();
+       /* Normalize exclusion names as globbing patterns */
+       if (exclusion) {
+               size_t i;
 
-       ret = validate_event_name(event->name);
-       if (ret) {
-               goto error;
+               for (i = 0; i < exclusion->count; i++) {
+                       char *name = LTTNG_EVENT_EXCLUSION_NAME_AT(exclusion, i);
+
+                       strutils_normalize_star_glob_pattern(name);
+               }
        }
 
+       DBG("Enable event command for event \'%s\'", event->name);
+
+       rcu_read_lock();
+
        switch (domain->type) {
        case LTTNG_DOMAIN_KERNEL:
        {
@@ -1846,15 +1887,16 @@ static int _cmd_enable_event(struct ltt_session *session,
                                ret = LTTNG_ERR_FATAL;
                                goto error;
                        }
-                       strncpy(attr->name, channel_name, sizeof(attr->name));
+                       if (lttng_strncpy(attr->name, channel_name,
+                                       sizeof(attr->name))) {
+                               ret = LTTNG_ERR_INVALID;
+                               goto error;
+                       }
 
                        ret = cmd_enable_channel(session, domain, attr, wpipe);
                        if (ret != LTTNG_OK) {
-                               free(attr);
                                goto error;
                        }
-                       free(attr);
-
                        channel_created = 1;
                }
 
@@ -1983,14 +2025,16 @@ static int _cmd_enable_event(struct ltt_session *session,
                                ret = LTTNG_ERR_FATAL;
                                goto error;
                        }
-                       strncpy(attr->name, channel_name, sizeof(attr->name));
+                       if (lttng_strncpy(attr->name, channel_name,
+                                       sizeof(attr->name))) {
+                               ret = LTTNG_ERR_INVALID;
+                               goto error;
+                       }
 
                        ret = cmd_enable_channel(session, domain, attr, wpipe);
                        if (ret != LTTNG_OK) {
-                               free(attr);
                                goto error;
                        }
-                       free(attr);
 
                        /* Get the newly created channel reference back */
                        uchan = trace_ust_find_channel_by_name(
@@ -2165,6 +2209,7 @@ error:
        free(filter_expression);
        free(filter);
        free(exclusion);
+       channel_attr_destroy(attr);
        rcu_read_unlock();
        return ret;
 }
@@ -2332,6 +2377,113 @@ 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.
  *
@@ -2371,8 +2523,31 @@ 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->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");
+                               ret = LTTNG_ERR_CREATE_DIR_FAIL;
+                               goto error;
+                       }
+               }
+       }
+
        /* Kernel tracing */
        if (ksession != NULL) {
+               DBG("Start kernel tracing session %s", session->name);
                ret = start_kernel_session(ksession, kernel_tracer_fd);
                if (ret != LTTNG_OK) {
                        goto error;
@@ -2398,12 +2573,70 @@ int cmd_start_trace(struct ltt_session *session)
        session->has_been_started = 1;
        session->active = 1;
 
+       /*
+        * Clear the flag that indicates that a rotation was done while the
+        * session was stopped.
+        */
+       session->rotated_after_last_stop = false;
+
+       if (session->rotate_timer_period) {
+               ret = sessiond_rotate_timer_start(session,
+                               session->rotate_timer_period);
+               if (ret < 0) {
+                       ERR("Failed to enable rotate timer");
+                       ret = LTTNG_ERR_UNK;
+                       goto error;
+               }
+       }
+
        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;
+       }
+end:
+       session->rotate_count--;
+       return ret;
+}
+
 /*
  * Command LTTNG_STOP_TRACE processed by the client thread.
  */
@@ -2413,9 +2646,11 @@ 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;
 
        assert(session);
 
+       DBG("Begin stop session %s (id %" PRIu64 ")", session->name, session->id);
        /* Short cut */
        ksession = session->kernel_session;
        usess = session->ust_session;
@@ -2426,11 +2661,38 @@ 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");
 
-               /* Flush metadata if exist */
+               ret = kernel_stop_session(ksession);
+               if (ret < 0) {
+                       ret = LTTNG_ERR_KERN_STOP_FAIL;
+                       goto error;
+               }
+
+               kernel_wait_quiescent(kernel_tracer_fd);
+
+               /* Flush metadata after stopping (if exists) */
                if (ksession->metadata_stream_fd >= 0) {
                        ret = kernel_metadata_flush_buffer(ksession->metadata_stream_fd);
                        if (ret < 0) {
@@ -2438,7 +2700,7 @@ int cmd_stop_trace(struct ltt_session *session)
                        }
                }
 
-               /* Flush all buffers before stopping */
+               /* Flush all buffers after stopping */
                cds_list_for_each_entry(kchan, &ksession->channel_list.head, list) {
                        ret = kernel_flush_buffer(kchan);
                        if (ret < 0) {
@@ -2446,15 +2708,9 @@ int cmd_stop_trace(struct ltt_session *session)
                        }
                }
 
-               ret = kernel_stop_session(ksession);
-               if (ret < 0) {
-                       ret = LTTNG_ERR_KERN_STOP_FAIL;
-                       goto error;
-               }
-
-               kernel_wait_quiescent(kernel_tracer_fd);
-
                ksession->active = 0;
+               DBG("Kernel session stopped %s (id %" PRIu64 ")", session->name,
+                               session->id);
        }
 
        if (usess && usess->active) {
@@ -2473,7 +2729,7 @@ int cmd_stop_trace(struct ltt_session *session)
 
        /* Flag inactive after a successful stop. */
        session->active = 0;
-       ret = LTTNG_OK;
+       ret = !error_occured ? LTTNG_OK : LTTNG_ERR_UNK;
 
 error:
        return ret;
@@ -2697,7 +2953,8 @@ error:
  *
  * Called with session lock held.
  */
-int cmd_destroy_session(struct ltt_session *session, int wpipe)
+int cmd_destroy_session(struct ltt_session *session, int wpipe,
+               struct notification_thread_handle *notification_thread_handle)
 {
        int ret;
        struct ltt_ust_session *usess;
@@ -2709,6 +2966,30 @@ int cmd_destroy_session(struct ltt_session *session, int wpipe)
        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);
+       }
+
+       if (session->rotate_timer_enabled) {
+               sessiond_rotate_timer_stop(session);
+       }
+
+       if (session->rotate_size) {
+               unsubscribe_session_consumed_size_rotation(session, notification_thread_handle);
+               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);
 
@@ -2742,83 +3023,25 @@ int cmd_destroy_session(struct ltt_session *session, int wpipe)
 }
 
 /*
- * Command LTTNG_CALIBRATE processed by the client thread.
+ * Command LTTNG_REGISTER_CONSUMER processed by the client thread.
  */
-int cmd_calibrate(enum lttng_domain_type domain,
-               struct lttng_calibrate *calibrate)
+int cmd_register_consumer(struct ltt_session *session,
+               enum lttng_domain_type domain, const char *sock_path,
+               struct consumer_data *cdata)
 {
-       int ret;
+       int ret, sock;
+       struct consumer_socket *socket = NULL;
+
+       assert(session);
+       assert(cdata);
+       assert(sock_path);
 
        switch (domain) {
        case LTTNG_DOMAIN_KERNEL:
        {
-               struct lttng_kernel_calibrate kcalibrate;
+               struct ltt_kernel_session *ksess = session->kernel_session;
 
-               switch (calibrate->type) {
-               case LTTNG_CALIBRATE_FUNCTION:
-               default:
-                       /* Default and only possible calibrate option. */
-                       kcalibrate.type = LTTNG_KERNEL_CALIBRATE_KRETPROBE;
-                       break;
-               }
-
-               ret = kernel_calibrate(kernel_tracer_fd, &kcalibrate);
-               if (ret < 0) {
-                       ret = LTTNG_ERR_KERN_ENABLE_FAIL;
-                       goto error;
-               }
-               break;
-       }
-       case LTTNG_DOMAIN_UST:
-       {
-               struct lttng_ust_calibrate ucalibrate;
-
-               switch (calibrate->type) {
-               case LTTNG_CALIBRATE_FUNCTION:
-               default:
-                       /* Default and only possible calibrate option. */
-                       ucalibrate.type = LTTNG_UST_CALIBRATE_TRACEPOINT;
-                       break;
-               }
-
-               ret = ust_app_calibrate_glb(&ucalibrate);
-               if (ret < 0) {
-                       ret = LTTNG_ERR_UST_CALIBRATE_FAIL;
-                       goto error;
-               }
-               break;
-       }
-       default:
-               ret = LTTNG_ERR_UND;
-               goto error;
-       }
-
-       ret = LTTNG_OK;
-
-error:
-       return ret;
-}
-
-/*
- * Command LTTNG_REGISTER_CONSUMER processed by the client thread.
- */
-int cmd_register_consumer(struct ltt_session *session,
-               enum lttng_domain_type domain, const char *sock_path,
-               struct consumer_data *cdata)
-{
-       int ret, sock;
-       struct consumer_socket *socket = NULL;
-
-       assert(session);
-       assert(cdata);
-       assert(sock_path);
-
-       switch (domain) {
-       case LTTNG_DOMAIN_KERNEL:
-       {
-               struct ltt_kernel_session *ksess = session->kernel_session;
-
-               assert(ksess);
+               assert(ksess);
 
                /* Can't register a consumer if there is already one */
                if (ksess->consumer_fds_sent != 0) {
@@ -2991,8 +3214,8 @@ ssize_t cmd_list_channels(enum lttng_domain_type domain,
 
        if (nb_chan > 0) {
                const size_t channel_size = sizeof(struct lttng_channel) +
-                       sizeof(struct lttcomm_channel_extended);
-               struct lttcomm_channel_extended *channel_exts;
+                       sizeof(struct lttng_channel_extended);
+               struct lttng_channel_extended *channel_exts;
 
                payload_size = nb_chan * channel_size;
                *channels = zmalloc(payload_size);
@@ -3003,7 +3226,12 @@ ssize_t cmd_list_channels(enum lttng_domain_type domain,
 
                channel_exts = ((void *) *channels) +
                                (nb_chan * sizeof(struct lttng_channel));
-               list_lttng_channels(domain, session, *channels, channel_exts);
+               ret = list_lttng_channels(domain, session, *channels, channel_exts);
+               if (ret != LTTNG_OK) {
+                       free(*channels);
+                       *channels = NULL;
+                       goto end;
+               }
        } else {
                *channels = NULL;
        }
@@ -3111,7 +3339,7 @@ void cmd_list_lttng_sessions(struct lttng_session *sessions, uid_t uid,
                                        sizeof(sessions[i].path), session);
                } else {
                        ret = snprintf(sessions[i].path, sizeof(sessions[i].path), "%s",
-                                       session->consumer->dst.trace_path);
+                                       session->consumer->dst.session_root_path);
                }
                if (ret < 0) {
                        PERROR("snprintf session path");
@@ -3139,6 +3367,8 @@ int cmd_data_pending(struct ltt_session *session)
 
        assert(session);
 
+       DBG("Data pending for session %s", session->name);
+
        /* Session MUST be stopped to ask for data availability. */
        if (session->active) {
                ret = LTTNG_ERR_SESSION_STARTED;
@@ -3160,6 +3390,15 @@ int cmd_data_pending(struct ltt_session *session)
                }
        }
 
+       /*
+        * A rotation is still pending, we have to wait.
+        */
+       if (session->rotate_pending) {
+               DBG("Rotate still pending for session %s", session->name);
+               ret = 1;
+               goto error;
+       }
+
        if (ksess && ksess->consumer) {
                ret = consumer_is_data_pending(ksess->id, ksess->consumer);
                if (ret == 1) {
@@ -3200,11 +3439,10 @@ int cmd_snapshot_add_output(struct ltt_session *session,
        DBG("Cmd snapshot add output for session %s", session->name);
 
        /*
-        * Permission denied to create an output if the session is not
-        * set in no output mode.
+        * Can't create an output if the session is not set in no-output mode.
         */
        if (session->output_traces) {
-               ret = LTTNG_ERR_EPERM;
+               ret = LTTNG_ERR_NOT_SNAPSHOT_SESSION;
                goto error;
        }
 
@@ -3268,7 +3506,7 @@ int cmd_snapshot_del_output(struct ltt_session *session,
         * set in no output mode.
         */
        if (session->output_traces) {
-               ret = LTTNG_ERR_EPERM;
+               ret = LTTNG_ERR_NOT_SNAPSHOT_SESSION;
                goto error;
        }
 
@@ -3320,19 +3558,19 @@ ssize_t cmd_snapshot_list_outputs(struct ltt_session *session,
         * set in no output mode.
         */
        if (session->output_traces) {
-               ret = -LTTNG_ERR_EPERM;
-               goto error;
+               ret = -LTTNG_ERR_NOT_SNAPSHOT_SESSION;
+               goto end;
        }
 
        if (session->snapshot.nb_output == 0) {
                ret = 0;
-               goto error;
+               goto end;
        }
 
        list = zmalloc(session->snapshot.nb_output * sizeof(*list));
        if (!list) {
                ret = -LTTNG_ERR_NOMEM;
-               goto error;
+               goto end;
        }
 
        /* Copy list from session to the new list object. */
@@ -3342,10 +3580,18 @@ ssize_t cmd_snapshot_list_outputs(struct ltt_session *session,
                assert(output->consumer);
                list[idx].id = output->id;
                list[idx].max_size = output->max_size;
-               strncpy(list[idx].name, output->name, sizeof(list[idx].name));
+               if (lttng_strncpy(list[idx].name, output->name,
+                               sizeof(list[idx].name))) {
+                       ret = -LTTNG_ERR_INVALID;
+                       goto error;
+               }
                if (output->consumer->type == CONSUMER_DST_LOCAL) {
-                       strncpy(list[idx].ctrl_url, output->consumer->dst.trace_path,
-                                       sizeof(list[idx].ctrl_url));
+                       if (lttng_strncpy(list[idx].ctrl_url,
+                                       output->consumer->dst.session_root_path,
+                                       sizeof(list[idx].ctrl_url))) {
+                               ret = -LTTNG_ERR_INVALID;
+                               goto error;
+                       }
                } else {
                        /* Control URI. */
                        ret = uri_to_str_url(&output->consumer->dst.net.control,
@@ -3370,8 +3616,9 @@ ssize_t cmd_snapshot_list_outputs(struct ltt_session *session,
        list = NULL;
        ret = session->snapshot.nb_output;
 error:
-       free(list);
        rcu_read_unlock();
+       free(list);
+end:
        return ret;
 }
 
@@ -3382,7 +3629,7 @@ error:
  * Return 0 if the metadata can be generated, a LTTNG_ERR code otherwise.
  */
 static
-int check_metadata_regenerate_support(struct ltt_session *session)
+int check_regenerate_metadata_support(struct ltt_session *session)
 {
        int ret;
 
@@ -3421,7 +3668,28 @@ end:
 }
 
 static
-int ust_metadata_regenerate(struct ltt_ust_session *usess)
+int clear_metadata_file(int fd)
+{
+       int ret;
+
+       ret = lseek(fd, 0, SEEK_SET);
+       if (ret < 0) {
+               PERROR("lseek");
+               goto end;
+       }
+
+       ret = ftruncate(fd, 0);
+       if (ret < 0) {
+               PERROR("ftruncate");
+               goto end;
+       }
+
+end:
+       return ret;
+}
+
+static
+int ust_regenerate_metadata(struct ltt_ust_session *usess)
 {
        int ret = 0;
        struct buffer_reg_uid *uid_reg = NULL;
@@ -3441,6 +3709,15 @@ int ust_metadata_regenerate(struct ltt_ust_session *usess)
                memset(registry->metadata, 0, registry->metadata_alloc_len);
                registry->metadata_len = 0;
                registry->metadata_version++;
+               if (registry->metadata_fd > 0) {
+                       /* Clear the metadata file's content. */
+                       ret = clear_metadata_file(registry->metadata_fd);
+                       if (ret) {
+                               pthread_mutex_unlock(&registry->lock);
+                               goto end;
+                       }
+               }
+
                ret = ust_metadata_session_statedump(registry, NULL,
                                registry->major, registry->minor);
                if (ret) {
@@ -3482,7 +3759,7 @@ end:
 }
 
 /*
- * Command LTTNG_METADATA_REGENERATE from the lttng-ctl library.
+ * Command LTTNG_REGENERATE_METADATA from the lttng-ctl library.
  *
  * Ask the consumer to truncate the existing metadata file(s) and
  * then regenerate the metadata. Live and per-pid sessions are not
@@ -3490,19 +3767,19 @@ end:
  *
  * Return 0 on success or else a LTTNG_ERR code.
  */
-int cmd_metadata_regenerate(struct ltt_session *session)
+int cmd_regenerate_metadata(struct ltt_session *session)
 {
        int ret;
 
        assert(session);
 
-       ret = check_metadata_regenerate_support(session);
+       ret = check_regenerate_metadata_support(session);
        if (ret) {
                goto end;
        }
 
        if (session->kernel_session) {
-               ret = kernctl_session_metadata_regenerate(
+               ret = kernctl_session_regenerate_metadata(
                                session->kernel_session->fd);
                if (ret < 0) {
                        ERR("Failed to regenerate the kernel metadata");
@@ -3511,7 +3788,7 @@ int cmd_metadata_regenerate(struct ltt_session *session)
        }
 
        if (session->ust_session) {
-               ret = ust_metadata_regenerate(session->ust_session);
+               ret = ust_regenerate_metadata(session->ust_session);
                if (ret < 0) {
                        ERR("Failed to regenerate the UST metadata");
                        goto end;
@@ -3524,6 +3801,147 @@ end:
        return ret;
 }
 
+/*
+ * Command LTTNG_REGENERATE_STATEDUMP from the lttng-ctl library.
+ *
+ * Ask the tracer to regenerate a new statedump.
+ *
+ * Return 0 on success or else a LTTNG_ERR code.
+ */
+int cmd_regenerate_statedump(struct ltt_session *session)
+{
+       int ret;
+
+       assert(session);
+
+       if (!session->active) {
+               ret = LTTNG_ERR_SESSION_NOT_STARTED;
+               goto end;
+       }
+
+       if (session->kernel_session) {
+               ret = kernctl_session_regenerate_statedump(
+                               session->kernel_session->fd);
+               /*
+                * Currently, the statedump in kernel can only fail if out
+                * of memory.
+                */
+               if (ret < 0) {
+                       if (ret == -ENOMEM) {
+                               ret = LTTNG_ERR_REGEN_STATEDUMP_NOMEM;
+                       } else {
+                               ret = LTTNG_ERR_REGEN_STATEDUMP_FAIL;
+                       }
+                       ERR("Failed to regenerate the kernel statedump");
+                       goto end;
+               }
+       }
+
+       if (session->ust_session) {
+               ret = ust_app_regenerate_statedump_all(session->ust_session);
+               /*
+                * Currently, the statedump in UST always returns 0.
+                */
+               if (ret < 0) {
+                       ret = LTTNG_ERR_REGEN_STATEDUMP_FAIL;
+                       ERR("Failed to regenerate the UST statedump");
+                       goto end;
+               }
+       }
+       DBG("Cmd regenerate statedump for session %s", session->name);
+       ret = LTTNG_OK;
+
+end:
+       return ret;
+}
+
+int cmd_register_trigger(struct command_ctx *cmd_ctx, int sock,
+               struct notification_thread_handle *notification_thread)
+{
+       int ret;
+       size_t trigger_len;
+       ssize_t sock_recv_len;
+       struct lttng_trigger *trigger = NULL;
+       struct lttng_buffer_view view;
+       struct lttng_dynamic_buffer trigger_buffer;
+
+       lttng_dynamic_buffer_init(&trigger_buffer);
+       trigger_len = (size_t) cmd_ctx->lsm->u.trigger.length;
+       ret = lttng_dynamic_buffer_set_size(&trigger_buffer, trigger_len);
+       if (ret) {
+               ret = LTTNG_ERR_NOMEM;
+               goto end;
+       }
+
+       sock_recv_len = lttcomm_recv_unix_sock(sock, trigger_buffer.data,
+                       trigger_len);
+       if (sock_recv_len < 0 || sock_recv_len != trigger_len) {
+               ERR("Failed to receive \"register trigger\" command payload");
+               /* TODO: should this be a new error enum ? */
+               ret = LTTNG_ERR_INVALID_TRIGGER;
+               goto end;
+       }
+
+       view = lttng_buffer_view_from_dynamic_buffer(&trigger_buffer, 0, -1);
+       if (lttng_trigger_create_from_buffer(&view, &trigger) !=
+                       trigger_len) {
+               ERR("Invalid trigger payload received in \"register trigger\" command");
+               ret = LTTNG_ERR_INVALID_TRIGGER;
+               goto end;
+       }
+
+       ret = notification_thread_command_register_trigger(notification_thread,
+                       trigger);
+       /* Ownership of trigger was transferred. */
+       trigger = NULL;
+end:
+       lttng_trigger_destroy(trigger);
+       lttng_dynamic_buffer_reset(&trigger_buffer);
+       return ret;
+}
+
+int cmd_unregister_trigger(struct command_ctx *cmd_ctx, int sock,
+               struct notification_thread_handle *notification_thread)
+{
+       int ret;
+       size_t trigger_len;
+       ssize_t sock_recv_len;
+       struct lttng_trigger *trigger = NULL;
+       struct lttng_buffer_view view;
+       struct lttng_dynamic_buffer trigger_buffer;
+
+       lttng_dynamic_buffer_init(&trigger_buffer);
+       trigger_len = (size_t) cmd_ctx->lsm->u.trigger.length;
+       ret = lttng_dynamic_buffer_set_size(&trigger_buffer, trigger_len);
+       if (ret) {
+               ret = LTTNG_ERR_NOMEM;
+               goto end;
+       }
+
+       sock_recv_len = lttcomm_recv_unix_sock(sock, trigger_buffer.data,
+                       trigger_len);
+       if (sock_recv_len < 0 || sock_recv_len != trigger_len) {
+               ERR("Failed to receive \"unregister trigger\" command payload");
+               /* TODO: should this be a new error enum ? */
+               ret = LTTNG_ERR_INVALID_TRIGGER;
+               goto end;
+       }
+
+       view = lttng_buffer_view_from_dynamic_buffer(&trigger_buffer, 0, -1);
+       if (lttng_trigger_create_from_buffer(&view, &trigger) !=
+                       trigger_len) {
+               ERR("Invalid trigger payload received in \"unregister trigger\" command");
+               ret = LTTNG_ERR_INVALID_TRIGGER;
+               goto end;
+       }
+
+       ret = notification_thread_command_unregister_trigger(notification_thread,
+                       trigger);
+end:
+       lttng_trigger_destroy(trigger);
+       lttng_dynamic_buffer_reset(&trigger_buffer);
+       return ret;
+}
 
 /*
  * Send relayd sockets from snapshot output to consumer. Ignore request if the
@@ -3556,10 +3974,12 @@ static int set_relayd_for_snapshot(struct consumer_output *consumer,
        rcu_read_lock();
        cds_lfht_for_each_entry(snap_output->consumer->socks->ht, &iter.iter,
                        socket, node.node) {
+               pthread_mutex_lock(socket->lock);
                ret = send_consumer_relayd_sockets(0, session->id,
                                snap_output->consumer, socket,
                                session->name, session->hostname,
                                session->live_timer);
+               pthread_mutex_unlock(socket->lock);
                if (ret != LTTNG_OK) {
                        rcu_read_unlock();
                        goto error;
@@ -3586,13 +4006,6 @@ static int record_kernel_snapshot(struct ltt_kernel_session *ksess,
        assert(output);
        assert(session);
 
-       /* Get the datetime for the snapshot output directory. */
-       ret = utils_get_current_time_str("%Y%m%d-%H%M%S", output->datetime,
-                       sizeof(output->datetime));
-       if (!ret) {
-               ret = LTTNG_ERR_INVALID;
-               goto error;
-       }
 
        /*
         * Copy kernel session sockets so we can communicate with the right
@@ -3640,14 +4053,6 @@ static int record_ust_snapshot(struct ltt_ust_session *usess,
        assert(output);
        assert(session);
 
-       /* Get the datetime for the snapshot output directory. */
-       ret = utils_get_current_time_str("%Y%m%d-%H%M%S", output->datetime,
-                       sizeof(output->datetime));
-       if (!ret) {
-               ret = LTTNG_ERR_INVALID;
-               goto error;
-       }
-
        /*
         * Copy UST session sockets so we can communicate with the right
         * consumer for the snapshot record command.
@@ -3669,9 +4074,6 @@ static int record_ust_snapshot(struct ltt_ust_session *usess,
                case EINVAL:
                        ret = LTTNG_ERR_INVALID;
                        break;
-               case ENODATA:
-                       ret = LTTNG_ERR_SNAPSHOT_NODATA;
-                       break;
                default:
                        ret = LTTNG_ERR_SNAPSHOT_FAIL;
                        break;
@@ -3789,18 +4191,27 @@ int cmd_snapshot_record(struct ltt_session *session,
        unsigned int use_tmp_output = 0;
        struct snapshot_output tmp_output;
        unsigned int snapshot_success = 0;
+       char datetime[16];
 
        assert(session);
        assert(output);
 
        DBG("Cmd snapshot record for session %s", session->name);
 
+       /* Get the datetime for the snapshot output directory. */
+       ret = utils_get_current_time_str("%Y%m%d-%H%M%S", datetime,
+                       sizeof(datetime));
+       if (!ret) {
+               ret = LTTNG_ERR_INVALID;
+               goto error;
+       }
+
        /*
         * Permission denied to create an output if the session is not
         * set in no output mode.
         */
        if (session->output_traces) {
-               ret = LTTNG_ERR_EPERM;
+               ret = LTTNG_ERR_NOT_SNAPSHOT_SESSION;
                goto error;
        }
 
@@ -3825,138 +4236,104 @@ int cmd_snapshot_record(struct ltt_session *session,
                }
                /* Use the global session count for the temporary 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 (session->kernel_session) {
-               struct ltt_kernel_session *ksess = session->kernel_session;
+       if (use_tmp_output) {
+               int64_t nb_packets_per_stream;
 
-               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;
+                       goto error;
+               }
 
-                       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;
+               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;
                        }
-                       ret = record_kernel_snapshot(ksess, &tmp_output, session,
+               }
+
+               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;
-                       struct lttng_ht_iter iter;
-
-                       rcu_read_lock();
-                       cds_lfht_for_each_entry(session->snapshot.output_ht->ht,
-                                       &iter.iter, sout, node.node) {
-                               int64_t nb_packets_per_stream;
-
-                               /*
-                                * Make a local copy of the output and assign the possible
-                                * temporary value given by the caller.
-                                */
-                               memset(&tmp_output, 0, sizeof(tmp_output));
-                               memcpy(&tmp_output, sout, sizeof(tmp_output));
-
-                               if (output->max_size != (uint64_t) -1ULL) {
-                                       tmp_output.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;
-                                       goto error;
-                               }
+               snapshot_success = 1;
+       } else {
+               struct snapshot_output *sout;
+               struct lttng_ht_iter iter;
 
-                               /* Use temporary name. */
-                               if (*output->name != '\0') {
-                                       strncpy(tmp_output.name, output->name,
-                                                       sizeof(tmp_output.name));
-                               }
+               rcu_read_lock();
+               cds_lfht_for_each_entry(session->snapshot.output_ht->ht,
+                               &iter.iter, sout, node.node) {
+                       int64_t nb_packets_per_stream;
 
-                               tmp_output.nb_snapshot = session->snapshot.nb_snapshot;
+                       /*
+                        * Make a local copy of the output and assign the possible
+                        * temporary value given by the caller.
+                        */
+                       memset(&tmp_output, 0, sizeof(tmp_output));
+                       memcpy(&tmp_output, sout, sizeof(tmp_output));
 
-                               ret = record_kernel_snapshot(ksess, &tmp_output,
-                                               session, wait, nb_packets_per_stream);
-                               if (ret != LTTNG_OK) {
-                                       rcu_read_unlock();
-                                       goto error;
-                               }
-                               snapshot_success = 1;
+                       if (output->max_size != (uint64_t) -1ULL) {
+                               tmp_output.max_size = output->max_size;
                        }
-                       rcu_read_unlock();
-               }
-       }
-
-       if (session->ust_session) {
-               struct ltt_ust_session *usess = session->ust_session;
-
-               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;
+                               rcu_read_unlock();
                                goto error;
                        }
-                       ret = record_ust_snapshot(usess, &tmp_output, session,
-                                       wait, nb_packets_per_stream);
-                       if (ret != LTTNG_OK) {
-                               goto error;
-                       }
-                       snapshot_success = 1;
-               } else {
-                       struct snapshot_output *sout;
-                       struct lttng_ht_iter iter;
-
-                       rcu_read_lock();
-                       cds_lfht_for_each_entry(session->snapshot.output_ht->ht,
-                                       &iter.iter, sout, node.node) {
-                               int64_t nb_packets_per_stream;
-
-                               /*
-                                * Make a local copy of the output and assign the possible
-                                * temporary value given by the caller.
-                                */
-                               memset(&tmp_output, 0, sizeof(tmp_output));
-                               memcpy(&tmp_output, sout, sizeof(tmp_output));
 
-                               if (output->max_size != (uint64_t) -1ULL) {
-                                       tmp_output.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;
+                       /* 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;
                                }
+                       }
 
-                               /* Use temporary name. */
-                               if (*output->name != '\0') {
-                                       strncpy(tmp_output.name, output->name,
-                                                       sizeof(tmp_output.name));
-                               }
+                       tmp_output.nb_snapshot = session->snapshot.nb_snapshot;
+                       memcpy(tmp_output.datetime, datetime, sizeof(datetime));
 
-                               tmp_output.nb_snapshot = session->snapshot.nb_snapshot;
+                       if (session->kernel_session) {
+                               ret = record_kernel_snapshot(session->kernel_session,
+                                               &tmp_output, session,
+                                               wait, nb_packets_per_stream);
+                               if (ret != LTTNG_OK) {
+                                       rcu_read_unlock();
+                                       goto error;
+                               }
+                       }
 
-                               ret = record_ust_snapshot(usess, &tmp_output, session,
+                       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;
                                }
-                               snapshot_success = 1;
                        }
-                       rcu_read_unlock();
+                       snapshot_success = 1;
                }
+               rcu_read_unlock();
        }
 
        if (snapshot_success) {
@@ -3992,6 +4369,443 @@ int cmd_set_session_shm_path(struct ltt_session *session,
        return 0;
 }
 
+/*
+ * Command LTTNG_ROTATE_SESSION from the lttng-ctl library.
+ *
+ * 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.
+ */
+int cmd_rotate_session(struct ltt_session *session,
+               struct lttng_rotate_session_return *rotate_return)
+{
+       int ret;
+       size_t strf_ret;
+       struct tm *timeinfo;
+       char datetime[21];
+       time_t now;
+       bool ust_active = false;
+
+       assert(session);
+
+       if (!session->has_been_started) {
+               ret = -LTTNG_ERR_START_SESSION_ONCE;
+               goto end;
+       }
+
+       if (session->live_timer || session->snapshot_mode ||
+                       !session->output_traces) {
+               ret = -LTTNG_ERR_ROTATION_NOT_AVAILABLE;
+               goto end;
+       }
+
+       /*
+        * Unsupported feature in lttng-relayd before 2.11.
+        */
+       if (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;
+               goto end;
+       }
+
+       if (session->rotate_pending || session->rotate_pending_relay) {
+               ret = -LTTNG_ERR_ROTATION_PENDING;
+               DBG("Rotate already in progress");
+               goto end;
+       }
+
+       /*
+        * After a stop, we only allow one rotation to occur, the other ones are
+        * useless until a new start.
+        */
+       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;
+               goto end;
+       }
+
+       /* Special case for the first rotation. */
+       if (session->rotate_count == 0) {
+               const char *base_path = NULL;
+
+               /* 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;
+               }
+       }
+       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.
+        */
+       now = time(NULL);
+       if (now == (time_t) -1) {
+               ret = -LTTNG_ERR_ROTATION_NOT_AVAILABLE;
+               goto end;
+       }
+       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;
+       }
+       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;
+               }
+       }
+       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;
+               }
+       }
+
+       if (!session->active) {
+               session->rotated_after_last_stop = true;
+       }
+
+       if (rotate_return) {
+               rotate_return->rotation_id = session->rotate_count;
+       }
+
+       DBG("Cmd rotate session %s, rotate_id %" PRIu64 " sent", session->name,
+                       session->rotate_count);
+       ret = LTTNG_OK;
+
+end:
+       return ret;
+}
+
+/*
+ * Command LTTNG_ROTATION_GET_INFO from the lttng-ctl library.
+ *
+ * Check if the session has finished its rotation.
+ *
+ * Return 0 on success or else a 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);
+
+       DBG("Cmd rotate_get_info session %s, rotation id %" PRIu64, session->name,
+                       session->rotate_count);
+
+       if (session->rotate_count != rotation_id) {
+               info_return->status = (int32_t) LTTNG_ROTATION_STATE_EXPIRED;
+               ret = LTTNG_OK;
+               goto end;
+       }
+
+       switch (session->rotation_state) {
+       case LTTNG_ROTATION_STATE_ONGOING:
+               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");
+                       info_return->status = LTTNG_ROTATION_STATUS_ERROR;
+                       ret = -LTTNG_ERR_UNK;
+                       goto end;
+               }
+               break;
+       case LTTNG_ROTATION_STATE_ERROR:
+               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;
+end:
+       return ret;
+}
+
+/*
+ * Command LTTNG_ROTATION_SET_SCHEDULE from the lttng-ctl library.
+ *
+ * Configure the automatic rotation parameters.
+ * Set to -1ULL to disable them.
+ *
+ * Return 0 on success or else an LTTNG_ERR code.
+ */
+int cmd_rotation_set_schedule(struct ltt_session *session,
+               uint64_t timer_us, uint64_t size,
+               struct notification_thread_handle *notification_thread_handle)
+{
+       int ret;
+
+       assert(session);
+
+       DBG("Cmd rotate set schedule session %s", session->name);
+
+       if (session->live_timer || session->snapshot_mode ||
+                       !session->output_traces) {
+               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;
+               goto end;
+       /* Trying to disable an inactive timer. */
+       } else if (timer_us == -1ULL && !session->rotate_timer_period) {
+               ret = LTTNG_ERR_ROTATION_NO_TIMER_SET;
+               goto end;
+       }
+
+       if (size && size != -1ULL && session->rotate_size) {
+               ret = LTTNG_ERR_ROTATION_SIZE_SET;
+               goto end;
+       } else if (size == -1ULL && !session->rotate_size) {
+               ret = LTTNG_ERR_ROTATION_NO_SIZE_SET;
+               goto end;
+       }
+
+       if (timer_us && !session->rotate_timer_period) {
+               if (timer_us > UINT_MAX) {
+                       ret = LTTNG_ERR_INVALID;
+                       goto end;
+               }
+
+               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);
+                       if (ret) {
+                               ERR("Failed to enable rotate timer");
+                               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);
+                       if (ret) {
+                               ret = LTTNG_ERR_UNK;
+                               goto end;
+                       }
+                       session->rotate_size = 0;
+               } else {
+                       ret = subscribe_session_consumed_size_rotation(session,
+                                       size, notification_thread_handle);
+                       if (ret) {
+                               PERROR("Subscribe to session usage");
+                               ret = LTTNG_ERR_UNK;
+                               goto end;
+                       }
+                       session->rotate_size = size;
+               }
+       }
+
+       ret = LTTNG_OK;
+
+       goto end;
+
+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)
+{
+       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);
+                       } else {
+                               abort();
+                       }
+                       assert(path);
+               } else {
+                       path = session->rotation_chunk.active_tracing_path;
+               }
+       } else {
+               /*
+                * A snapshot session does not have a "current" trace archive
+                * location.
+                */
+               path = "";
+       }
+
+       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;
+       }
+
+       ret = LTTNG_OK;
+end:
+       return ret;
+}
+
 /*
  * Init command subsystem.
  */
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