trigger: consider domain on register and unregister
[lttng-tools.git] / src / lib / lttng-ctl / lttng-ctl.c
index 0041969657e18089c8a957c941924363a752daaf..a295667fea7855e594645e99b5c24520ea5976ec 100644 (file)
@@ -1,65 +1,64 @@
 /*
- * liblttngctl.c
+ * lttng-ctl.c
  *
  * Linux Trace Toolkit Control Library
  *
  * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
+ * Copyright (C) 2016 Jérémie Galarneau <jeremie.galarneau@efficios.com>
  *
- * This library is free software; you can redistribute it and/or modify it
- * under the terms of the GNU Lesser General Public License, version 2.1 only,
- * as published by the Free Software Foundation.
+ * SPDX-License-Identifier: LGPL-2.1-only
  *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public License
- * along with this library; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
-#define _GNU_SOURCE
 #define _LGPL_SOURCE
 #include <assert.h>
 #include <grp.h>
-#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 
 #include <common/common.h>
+#include <common/compat/errno.h>
+#include <common/compat/string.h>
 #include <common/defaults.h>
+#include <common/dynamic-buffer.h>
+#include <common/dynamic-array.h>
+#include <common/payload.h>
+#include <common/payload-view.h>
 #include <common/sessiond-comm/sessiond-comm.h>
+#include <common/tracker.h>
+#include <common/unix.h>
 #include <common/uri.h>
 #include <common/utils.h>
-#include <lttng/lttng.h>
+#include <lttng/channel-internal.h>
+#include <lttng/destruction-handle.h>
+#include <lttng/endpoint.h>
+#include <lttng/event-internal.h>
 #include <lttng/health-internal.h>
-
-#include "filter/filter-ast.h"
-#include "filter/filter-parser.h"
-#include "filter/filter-bytecode.h"
-#include "filter/memstream.h"
+#include <lttng/lttng.h>
+#include <lttng/session-descriptor-internal.h>
+#include <lttng/session-internal.h>
+#include <lttng/trigger/trigger-internal.h>
+#include <lttng/userspace-probe-internal.h>
+#include <lttng/lttng-error.h>
+
+#include <common/filter/filter-ast.h>
+#include <common/filter/filter-parser.h>
+#include <common/filter/filter-bytecode.h>
+#include <common/filter/memstream.h>
 #include "lttng-ctl-helper.h"
 
-#ifdef DEBUG
-static const int print_xml = 1;
-#define dbg_printf(fmt, args...)       \
-       printf("[debug liblttng-ctl] " fmt, ## args)
-#else
-static const int print_xml = 0;
-#define dbg_printf(fmt, args...)                               \
+#define COPY_DOMAIN_PACKED(dst, src)                           \
 do {                                                           \
-       /* do nothing but check printf format */                \
-       if (0)                                                  \
-               printf("[debug liblttnctl] " fmt, ## args);     \
+       struct lttng_domain _tmp_domain;                        \
+                                                               \
+       lttng_ctl_copy_lttng_domain(&_tmp_domain, &src);        \
+       dst = _tmp_domain;                                      \
 } while (0)
-#endif
-
 
 /* Socket to session daemon for communication */
-static int sessiond_socket;
+static int sessiond_socket = -1;
 static char sessiond_sock_path[PATH_MAX];
 
 /* Variables */
@@ -150,7 +149,7 @@ end:
  * On success, returns the number of bytes sent (>=0)
  * On error, returns -1
  */
-static int send_session_varlen(void *data, size_t len)
+static int send_session_varlen(const void *data, size_t len)
 {
        int ret;
 
@@ -173,16 +172,47 @@ end:
        return ret;
 }
 
+/*
+ * Send file descriptors to the session daemon.
+ *
+ * On success, returns the number of bytes sent (>=0)
+ * On error, returns -1
+ */
+static int send_session_fds(const int *fds, size_t nb_fd)
+{
+       int ret;
+
+       if (!connected) {
+               ret = -LTTNG_ERR_NO_SESSIOND;
+               goto end;
+       }
+
+       if (!fds || !nb_fd) {
+               ret = 0;
+               goto end;
+       }
+
+       ret = lttcomm_send_fds_unix_sock(sessiond_socket, fds, nb_fd);
+       if (ret < 0) {
+               ret = -LTTNG_ERR_FATAL;
+       }
+
+end:
+       return ret;
+}
+
 /*
  * Receive data from the sessiond socket.
  *
  * On success, returns the number of bytes received (>=0)
- * On error, returns -1 (recvmsg() error) or -ENOTCONN
+ * On error, returns a negative lttng_error_code.
  */
 static int recv_data_sessiond(void *buf, size_t len)
 {
        int ret;
 
+       assert(len > 0);
+
        if (!connected) {
                ret = -LTTNG_ERR_NO_SESSIOND;
                goto end;
@@ -191,6 +221,8 @@ static int recv_data_sessiond(void *buf, size_t len)
        ret = lttcomm_recv_unix_sock(sessiond_socket, buf, len);
        if (ret < 0) {
                ret = -LTTNG_ERR_FATAL;
+       } else if (ret == 0) {
+               ret = -LTTNG_ERR_NO_SESSIOND;
        }
 
 end:
@@ -198,22 +230,44 @@ end:
 }
 
 /*
- *  Check if we are in the specified group.
+ * Receive a payload from the session daemon by appending to an existing
+ * payload.
+ * On success, returns the number of bytes received (>=0)
+ * On error, returns a negative lttng_error_code.
+ */
+static int recv_payload_sessiond(struct lttng_payload *payload, size_t len)
+{
+       int ret;
+       const size_t original_payload_size = payload->buffer.size;
+
+       ret = lttng_dynamic_buffer_set_size(
+                       &payload->buffer, payload->buffer.size + len);
+       if (ret) {
+               ret = -LTTNG_ERR_NOMEM;
+               goto end;
+       }
+
+       ret = recv_data_sessiond(
+                       payload->buffer.data + original_payload_size, len);
+end:
+       return ret;
+}
+
+/*
+ * Check if we are in the specified group.
  *
- *  If yes return 1, else return -1.
+ * If yes return 1, else return -1.
  */
 LTTNG_HIDDEN
 int lttng_check_tracing_group(void)
 {
-       struct group *grp_tracing;      /* no free(). See getgrnam(3) */
-       gid_t *grp_list;
+       gid_t *grp_list, tracing_gid;
        int grp_list_size, grp_id, i;
        int ret = -1;
        const char *grp_name = tracing_group;
 
        /* Get GID of group 'tracing' */
-       grp_tracing = getgrnam(grp_name);
-       if (!grp_tracing) {
+       if (utils_get_group_id(grp_name, false, &tracing_gid)) {
                /* If grp_tracing is NULL, the group does not exist. */
                goto end;
        }
@@ -221,24 +275,24 @@ int lttng_check_tracing_group(void)
        /* Get number of supplementary group IDs */
        grp_list_size = getgroups(0, NULL);
        if (grp_list_size < 0) {
-               perror("getgroups");
+               PERROR("getgroups");
                goto end;
        }
 
        /* Alloc group list of the right size */
        grp_list = zmalloc(grp_list_size * sizeof(gid_t));
        if (!grp_list) {
-               perror("malloc");
+               PERROR("malloc");
                goto end;
        }
        grp_id = getgroups(grp_list_size, grp_list);
        if (grp_id < 0) {
-               perror("getgroups");
+               PERROR("getgroups");
                goto free_list;
        }
 
        for (i = 0; i < grp_list_size; i++) {
-               if (grp_list[i] == grp_tracing->gr_gid) {
+               if (grp_list[i] == tracing_gid) {
                        ret = 1;
                        break;
                }
@@ -251,6 +305,50 @@ end:
        return ret;
 }
 
+static int check_enough_available_memory(size_t num_bytes_requested_per_cpu)
+{
+       int ret;
+       long num_cpu;
+       size_t best_mem_info;
+       size_t num_bytes_requested_total;
+
+       /*
+        * Get the number of CPU currently online to compute the amount of
+        * memory needed to create a buffer for every CPU.
+        */
+       num_cpu = sysconf(_SC_NPROCESSORS_ONLN);
+       if (num_cpu == -1) {
+               goto error;
+       }
+
+       num_bytes_requested_total = num_bytes_requested_per_cpu * num_cpu;
+
+       /*
+        * Try to get the `MemAvail` field of `/proc/meminfo`. This is the most
+        * reliable estimate we can get but it is only exposed by the kernel
+        * since 3.14. (See Linux kernel commit:
+        * 34e431b0ae398fc54ea69ff85ec700722c9da773)
+        */
+       ret = utils_get_memory_available(&best_mem_info);
+       if (ret >= 0) {
+               goto success;
+       }
+
+       /*
+        * As a backup plan, use `MemTotal` field of `/proc/meminfo`. This
+        * is a sanity check for obvious user error.
+        */
+       ret = utils_get_memory_total(&best_mem_info);
+       if (ret >= 0) {
+               goto success;
+       }
+
+error:
+       return -1;
+success:
+       return best_mem_info >= num_bytes_requested_total;
+}
+
 /*
  * Try connect to session daemon with sock_path.
  *
@@ -269,13 +367,13 @@ static int try_connect_sessiond(const char *sock_path)
 
        ret = lttcomm_connect_unix_sock(sock_path);
        if (ret < 0) {
-               /* Not alive */
+               /* Not alive. */
                goto error;
        }
 
        ret = lttcomm_close_unix_sock(ret);
        if (ret < 0) {
-               perror("lttcomm_close_unix_sock");
+               PERROR("lttcomm_close_unix_sock");
        }
 
        return 0;
@@ -293,7 +391,7 @@ error:
  */
 static int set_session_daemon_path(void)
 {
-       int in_tgroup = 0;      /* In tracing group */
+       int in_tgroup = 0;      /* In tracing group. */
        uid_t uid;
 
        uid = getuid();
@@ -312,7 +410,7 @@ static int set_session_daemon_path(void)
                int ret;
 
                if (in_tgroup) {
-                       /* Tracing group */
+                       /* Tracing group. */
                        ret = try_connect_sessiond(sessiond_sock_path);
                        if (ret >= 0) {
                                goto end;
@@ -322,8 +420,10 @@ static int set_session_daemon_path(void)
                /* ...or not in tracing group (and not root), default */
 
                /*
-                * With GNU C <  2.1, snprintf returns -1 if the target buffer is too small;
-                * With GNU C >= 2.1, snprintf returns the required size (excluding closing null)
+                * With GNU C <  2.1, snprintf returns -1 if the target buffer
+                * is too small;
+                * With GNU C >= 2.1, snprintf returns the required size
+                * (excluding closing null)
                 */
                ret = snprintf(sessiond_sock_path, sizeof(sessiond_sock_path),
                                DEFAULT_HOME_CLIENT_UNIX_SOCK, utils_get_home_dir());
@@ -339,41 +439,40 @@ error:
 }
 
 /*
- *  Connect to the LTTng session daemon.
+ * Connect to the LTTng session daemon.
  *
- *  On success, return 0. On error, return -1.
+ * On success, return the socket's file descriptor. On error, return -1.
  */
-static int connect_sessiond(void)
+LTTNG_HIDDEN int connect_sessiond(void)
 {
        int ret;
 
-       /* Don't try to connect if already connected. */
-       if (connected) {
-               return 0;
-       }
-
        ret = set_session_daemon_path();
        if (ret < 0) {
                goto error;
        }
 
-       /* Connect to the sesssion daemon */
+       /* Connect to the sesssion daemon. */
        ret = lttcomm_connect_unix_sock(sessiond_sock_path);
        if (ret < 0) {
                goto error;
        }
 
-       sessiond_socket = ret;
-       connected = 1;
-
-       return 0;
+       return ret;
 
 error:
        return -1;
 }
 
+static void reset_global_sessiond_connection_state(void)
+{
+       sessiond_socket = -1;
+       connected = 0;
+}
+
 /*
  *  Clean disconnect from the session daemon.
+ *
  *  On success, return 0. On error, return -1.
  */
 static int disconnect_sessiond(void)
@@ -382,42 +481,100 @@ static int disconnect_sessiond(void)
 
        if (connected) {
                ret = lttcomm_close_unix_sock(sessiond_socket);
-               sessiond_socket = 0;
-               connected = 0;
+               reset_global_sessiond_connection_state();
+       }
+
+       return ret;
+}
+
+static int recv_sessiond_optional_data(size_t len, void **user_buf,
+       size_t *user_len)
+{
+       int ret = 0;
+       void *buf = NULL;
+
+       if (len) {
+               if (!user_len) {
+                       ret = -LTTNG_ERR_INVALID;
+                       goto end;
+               }
+
+               buf = zmalloc(len);
+               if (!buf) {
+                       ret = -ENOMEM;
+                       goto end;
+               }
+
+               ret = recv_data_sessiond(buf, len);
+               if (ret < 0) {
+                       goto end;
+               }
+
+               if (!user_buf) {
+                       ret = -LTTNG_ERR_INVALID;
+                       goto end;
+               }
+
+               /* Move ownership of command header buffer to user. */
+               *user_buf = buf;
+               buf = NULL;
+               *user_len = len;
+       } else {
+               /* No command header. */
+               if (user_len) {
+                       *user_len = 0;
+               }
+
+               if (user_buf) {
+                       *user_buf = NULL;
+               }
        }
 
+end:
+       free(buf);
        return ret;
 }
 
 /*
  * Ask the session daemon a specific command and put the data into buf.
- * Takes extra var. len. data as input to send to the session daemon.
+ * Takes extra var. len. data and file descriptors as input to send to the
+ * session daemon.
  *
  * Return size of data (only payload, not header) or a negative error code.
  */
 LTTNG_HIDDEN
-int lttng_ctl_ask_sessiond_varlen(struct lttcomm_session_msg *lsm,
-               void *vardata, size_t varlen, void **buf)
+int lttng_ctl_ask_sessiond_fds_varlen(struct lttcomm_session_msg *lsm,
+               const int *fds, size_t nb_fd, const void *vardata,
+               size_t vardata_len, void **user_payload_buf,
+               void **user_cmd_header_buf, size_t *user_cmd_header_len)
 {
        int ret;
-       size_t size;
-       void *data = NULL;
+       size_t payload_len;
        struct lttcomm_lttng_msg llm;
 
        ret = connect_sessiond();
        if (ret < 0) {
                ret = -LTTNG_ERR_NO_SESSIOND;
                goto end;
+       } else {
+               sessiond_socket = ret;
+               connected = 1;
        }
 
-       /* Send command to session daemon */
        ret = send_session_msg(lsm);
        if (ret < 0) {
                /* Ret value is a valid lttng error code. */
                goto end;
        }
        /* Send var len data */
-       ret = send_session_varlen(vardata, varlen);
+       ret = send_session_varlen(vardata, vardata_len);
+       if (ret < 0) {
+               /* Ret value is a valid lttng error code. */
+               goto end;
+       }
+
+       /* Send fds */
+       ret = send_session_fds(fds, nb_fd);
        if (ret < 0) {
                /* Ret value is a valid lttng error code. */
                goto end;
@@ -436,41 +593,113 @@ int lttng_ctl_ask_sessiond_varlen(struct lttcomm_session_msg *lsm,
                goto end;
        }
 
-       size = llm.data_size;
-       if (size == 0) {
-               /* If client free with size 0 */
-               if (buf != NULL) {
-                       *buf = NULL;
-               }
-               ret = 0;
+       /* Get command header from data transmission */
+       ret = recv_sessiond_optional_data(llm.cmd_header_size,
+               user_cmd_header_buf, user_cmd_header_len);
+       if (ret < 0) {
+               goto end;
+       }
+
+       /* Get payload from data transmission */
+       ret = recv_sessiond_optional_data(llm.data_size, user_payload_buf,
+               &payload_len);
+       if (ret < 0) {
+               goto end;
+       }
+
+       ret = llm.data_size;
+
+end:
+       disconnect_sessiond();
+       return ret;
+}
+
+LTTNG_HIDDEN
+int lttng_ctl_ask_sessiond_payload(struct lttng_payload_view *message,
+       struct lttng_payload *reply)
+{
+       int ret;
+       struct lttcomm_lttng_msg llm;
+       const int fd_count = lttng_payload_view_get_fd_handle_count(message);
+
+       assert(reply->buffer.size == 0);
+       assert(lttng_dynamic_pointer_array_get_count(&reply->_fd_handles) == 0);
+
+       ret = connect_sessiond();
+       if (ret < 0) {
+               ret = -LTTNG_ERR_NO_SESSIOND;
                goto end;
+       } else {
+               sessiond_socket = ret;
+               connected = 1;
        }
 
-       data = zmalloc(size);
-       if (!data) {
-               ret = -ENOMEM;
+       /* Send command to session daemon */
+       ret = lttcomm_send_creds_unix_sock(sessiond_socket, message->buffer.data,
+                       message->buffer.size);
+       if (ret < 0) {
+               ret = -LTTNG_ERR_FATAL;
                goto end;
        }
 
-       /* Get payload data */
-       ret = recv_data_sessiond(data, size);
+       if (fd_count > 0) {
+               ret = lttcomm_send_payload_view_fds_unix_sock(sessiond_socket,
+                               message);
+               if (ret < 0) {
+                       ret = -LTTNG_ERR_FATAL;
+                       goto end;
+               }
+       }
+
+       /* Get header from data transmission */
+       ret = recv_payload_sessiond(reply, sizeof(llm));
        if (ret < 0) {
-               free(data);
+               /* Ret value is a valid lttng error code. */
                goto end;
        }
 
-       /*
-        * Extra protection not to dereference a NULL pointer. If buf is NULL at
-        * this point, an error is returned and data is freed.
-        */
-       if (buf == NULL) {
-               ret = -LTTNG_ERR_INVALID;
-               free(data);
+       llm = *((typeof(llm) *) reply->buffer.data);
+
+       /* Check error code if OK */
+       if (llm.ret_code != LTTNG_OK) {
+               ret = -llm.ret_code;
                goto end;
        }
 
-       *buf = data;
-       ret = size;
+       if (llm.cmd_header_size > 0) {
+               ret = recv_payload_sessiond(reply, llm.cmd_header_size);
+               if (ret < 0) {
+                       goto end;
+               }
+       }
+
+       /* Get command header from data transmission */
+       if (llm.data_size > 0) {
+               ret = recv_payload_sessiond(reply, llm.data_size);
+               if (ret < 0) {
+                       goto end;
+               }
+       }
+
+       if (llm.fd_count > 0) {
+               ret = lttcomm_recv_payload_fds_unix_sock(
+                               sessiond_socket, llm.fd_count, reply);
+               if (ret < 0) {
+                       goto end;
+               }
+       }
+
+       /* Don't return the llm header to the caller. */
+       memmove(reply->buffer.data, reply->buffer.data + sizeof(llm),
+                       reply->buffer.size - sizeof(llm));
+       ret = lttng_dynamic_buffer_set_size(
+                       &reply->buffer, reply->buffer.size - sizeof(llm));
+       if (ret) {
+               /* Can't happen as size is reduced. */
+               abort();
+       }
+
+       ret = reply->buffer.size;
 
 end:
        disconnect_sessiond();
@@ -479,6 +708,7 @@ end:
 
 /*
  * Create lttng handle and return pointer.
+ *
  * The returned pointer will be NULL in case of malloc() error.
  */
 struct lttng_handle *lttng_create_handle(const char *session_name,
@@ -486,10 +716,6 @@ struct lttng_handle *lttng_create_handle(const char *session_name,
 {
        struct lttng_handle *handle = NULL;
 
-       if (domain == NULL) {
-               goto end;
-       }
-
        handle = zmalloc(sizeof(struct lttng_handle));
        if (handle == NULL) {
                PERROR("malloc handle");
@@ -500,8 +726,10 @@ struct lttng_handle *lttng_create_handle(const char *session_name,
        lttng_ctl_copy_string(handle->session_name, session_name,
                        sizeof(handle->session_name));
 
-       /* Copy lttng domain */
-       lttng_ctl_copy_lttng_domain(&handle->domain, domain);
+       /* Copy lttng domain or leave initialized to 0. */
+       if (domain) {
+               lttng_ctl_copy_lttng_domain(&handle->domain, domain);
+       }
 
 end:
        return handle;
@@ -517,6 +745,7 @@ void lttng_destroy_handle(struct lttng_handle *handle)
 
 /*
  * Register an outside consumer.
+ *
  * Returns size of returned session payload data or a negative error code.
  */
 int lttng_register_consumer(struct lttng_handle *handle,
@@ -532,16 +761,18 @@ int lttng_register_consumer(struct lttng_handle *handle,
        lsm.cmd_type = LTTNG_REGISTER_CONSUMER;
        lttng_ctl_copy_string(lsm.session.name, handle->session_name,
                        sizeof(lsm.session.name));
-       lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
+       COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
 
-       lttng_ctl_copy_string(lsm.u.reg.path, socket_path, sizeof(lsm.u.reg.path));
+       lttng_ctl_copy_string(lsm.u.reg.path, socket_path,
+                       sizeof(lsm.u.reg.path));
 
        return lttng_ctl_ask_sessiond(&lsm, NULL);
 }
 
 /*
- *  Start tracing for all traces of the session.
- *  Returns size of returned session payload data or a negative error code.
+ * Start tracing for all traces of the session.
+ *
+ * Returns size of returned session payload data or a negative error code.
  */
 int lttng_start_tracing(const char *session_name)
 {
@@ -597,11 +828,11 @@ static int _lttng_stop_tracing(const char *session_name, int wait)
                }
 
                /*
-                * Data sleep time before retrying (in usec). Don't sleep if the call
-                * returned value indicates availability.
+                * Data sleep time before retrying (in usec). Don't sleep if the
+                * call returned value indicates availability.
                 */
                if (data_ret) {
-                       usleep(DEFAULT_DATA_AVAILABILITY_WAIT_TIME);
+                       usleep(DEFAULT_DATA_AVAILABILITY_WAIT_TIME_US);
                }
        } while (data_ret != 0);
 
@@ -638,15 +869,18 @@ int lttng_add_context(struct lttng_handle *handle,
                struct lttng_event_context *ctx, const char *event_name,
                const char *channel_name)
 {
+       int ret;
+       size_t len = 0;
+       char *buf = NULL;
        struct lttcomm_session_msg lsm;
 
-       /* Safety check. Both are mandatory */
+       /* Safety check. Both are mandatory. */
        if (handle == NULL || ctx == NULL) {
-               return -LTTNG_ERR_INVALID;
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
        }
 
        memset(&lsm, 0, sizeof(lsm));
-
        lsm.cmd_type = LTTNG_ADD_CONTEXT;
 
        /* If no channel name, send empty string. */
@@ -658,21 +892,69 @@ int lttng_add_context(struct lttng_handle *handle,
                                sizeof(lsm.u.context.channel_name));
        }
 
-       lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
+       COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
+       lttng_ctl_copy_string(lsm.session.name, handle->session_name,
+                       sizeof(lsm.session.name));
+
+       if (ctx->ctx == LTTNG_EVENT_CONTEXT_APP_CONTEXT) {
+               size_t provider_len, ctx_len;
+               const char *provider_name = ctx->u.app_ctx.provider_name;
+               const char *ctx_name = ctx->u.app_ctx.ctx_name;
+
+               if (!provider_name || !ctx_name) {
+                       ret = -LTTNG_ERR_INVALID;
+                       goto end;
+               }
+
+               provider_len = strlen(provider_name);
+               if (provider_len == 0) {
+                       ret = -LTTNG_ERR_INVALID;
+                       goto end;
+               }
+               lsm.u.context.provider_name_len = provider_len;
+
+               ctx_len = strlen(ctx_name);
+               if (ctx_len == 0) {
+                       ret = -LTTNG_ERR_INVALID;
+                       goto end;
+               }
+               lsm.u.context.context_name_len = ctx_len;
+
+               len = provider_len + ctx_len;
+               buf = zmalloc(len);
+               if (!buf) {
+                       ret = -LTTNG_ERR_NOMEM;
+                       goto end;
+               }
 
+               memcpy(buf, provider_name, provider_len);
+               memcpy(buf + provider_len, ctx_name, ctx_len);
+       }
        memcpy(&lsm.u.context.ctx, ctx, sizeof(struct lttng_event_context));
 
-       lttng_ctl_copy_string(lsm.session.name, handle->session_name,
-                       sizeof(lsm.session.name));
+       if (ctx->ctx == LTTNG_EVENT_CONTEXT_APP_CONTEXT) {
+               /*
+                * Don't leak application addresses to the sessiond.
+                * This is only necessary when ctx is for an app ctx otherwise
+                * the values inside the union (type & config) are overwritten.
+                */
+               lsm.u.context.ctx.u.app_ctx.provider_name = NULL;
+               lsm.u.context.ctx.u.app_ctx.ctx_name = NULL;
+       }
 
-       return lttng_ctl_ask_sessiond(&lsm, NULL);
+       ret = lttng_ctl_ask_sessiond_varlen_no_cmd_header(&lsm, buf, len, NULL);
+end:
+       free(buf);
+       return ret;
 }
 
 /*
- *  Enable event(s) for a channel.
- *  If no event name is specified, all events are enabled.
- *  If no channel name is specified, the default 'channel0' is used.
- *  Returns size of returned session payload data or a negative error code.
+ * Enable event(s) for a channel.
+ *
+ * If no event name is specified, all events are enabled.
+ * If no channel name is specified, the default 'channel0' is used.
+ *
+ * Returns size of returned session payload data or a negative error code.
  */
 int lttng_enable_event(struct lttng_handle *handle,
                struct lttng_event *ev, const char *channel_name)
@@ -709,7 +991,7 @@ static char *set_agent_filter(const char *filter, struct lttng_event *ev)
        assert(ev);
 
        /* Don't add filter for the '*' event. */
-       if (ev->name[0] != '*') {
+       if (strcmp(ev->name, "*") != 0) {
                if (filter) {
                        err = asprintf(&agent_filter, "(%s) && (logger_name == \"%s\")", filter,
                                        ev->name);
@@ -724,7 +1006,7 @@ static char *set_agent_filter(const char *filter, struct lttng_event *ev)
 
        /* Add loglevel filtering if any for the JUL domain. */
        if (ev->loglevel_type != LTTNG_EVENT_LOGLEVEL_ALL) {
-               char *op;
+               const char *op;
 
                if (ev->loglevel_type == LTTNG_EVENT_LOGLEVEL_RANGE) {
                        op = ">=";
@@ -759,153 +1041,44 @@ error:
 }
 
 /*
- * Generate the filter bytecode from a give filter expression string. Put the
- * newly allocated parser context in ctxp and populate the lsm object with the
- * expression len.
- *
- * Return 0 on success else a LTTNG_ERR_* code and ctxp is untouched.
+ * Enable event(s) for a channel, possibly with exclusions and a filter.
+ * If no event name is specified, all events are enabled.
+ * If no channel name is specified, the default name is used.
+ * If filter expression is not NULL, the filter is set for the event.
+ * If exclusion count is not zero, the exclusions are set for the event.
+ * Returns size of returned session payload data or a negative error code.
  */
-static int generate_filter(char *filter_expression,
-               struct lttcomm_session_msg *lsm, struct filter_parser_ctx **ctxp)
+int lttng_enable_event_with_exclusions(struct lttng_handle *handle,
+               struct lttng_event *ev, const char *channel_name,
+               const char *original_filter_expression,
+               int exclusion_count, char **exclusion_list)
 {
-       int ret;
+       struct lttcomm_session_msg lsm;
+       struct lttng_payload payload;
+       int ret = 0, i;
+       unsigned int free_filter_expression = 0;
        struct filter_parser_ctx *ctx = NULL;
-       FILE *fmem = NULL;
 
-       assert(filter_expression);
-       assert(lsm);
-       assert(ctxp);
+       /*
+        * We have either a filter or some exclusions, so we need to set up
+        * a variable-length payload from where to send the data.
+        */
+       lttng_payload_init(&payload);
 
        /*
-        * Casting const to non-const, as the underlying function will use it in
-        * read-only mode.
+        * Cast as non-const since we may replace the filter expression
+        * by a dynamically allocated string. Otherwise, the original
+        * string is not modified.
         */
-       fmem = lttng_fmemopen((void *) filter_expression,
-                       strlen(filter_expression), "r");
-       if (!fmem) {
-               fprintf(stderr, "Error opening memory as stream\n");
-               ret = -LTTNG_ERR_FILTER_NOMEM;
-               goto error;
-       }
-       ctx = filter_parser_ctx_alloc(fmem);
-       if (!ctx) {
-               fprintf(stderr, "Error allocating parser\n");
-               ret = -LTTNG_ERR_FILTER_NOMEM;
-               goto filter_alloc_error;
-       }
-       ret = filter_parser_ctx_append_ast(ctx);
-       if (ret) {
-               fprintf(stderr, "Parse error\n");
-               ret = -LTTNG_ERR_FILTER_INVAL;
-               goto parse_error;
-       }
-       ret = filter_visitor_set_parent(ctx);
-       if (ret) {
-               fprintf(stderr, "Set parent error\n");
-               ret = -LTTNG_ERR_FILTER_INVAL;
-               goto parse_error;
-       }
-       if (print_xml) {
-               ret = filter_visitor_print_xml(ctx, stdout, 0);
-               if (ret) {
-                       fflush(stdout);
-                       fprintf(stderr, "XML print error\n");
-                       ret = -LTTNG_ERR_FILTER_INVAL;
-                       goto parse_error;
-               }
-       }
+       char *filter_expression = (char *) original_filter_expression;
 
-       dbg_printf("Generating IR... ");
-       fflush(stdout);
-       ret = filter_visitor_ir_generate(ctx);
-       if (ret) {
-               fprintf(stderr, "Generate IR error\n");
-               ret = -LTTNG_ERR_FILTER_INVAL;
-               goto parse_error;
+       if (handle == NULL || ev == NULL) {
+               ret = -LTTNG_ERR_INVALID;
+               goto error;
        }
-       dbg_printf("done\n");
 
-       dbg_printf("Validating IR... ");
-       fflush(stdout);
-       ret = filter_visitor_ir_check_binary_op_nesting(ctx);
-       if (ret) {
-               ret = -LTTNG_ERR_FILTER_INVAL;
-               goto parse_error;
-       }
-       /* Validate strings used as literals in the expression */
-       ret = filter_visitor_ir_validate_string(ctx);
-       if (ret) {
-               ret = -LTTNG_ERR_FILTER_INVAL;
-               goto parse_error;
-       }
-       dbg_printf("done\n");
-
-       dbg_printf("Generating bytecode... ");
-       fflush(stdout);
-       ret = filter_visitor_bytecode_generate(ctx);
-       if (ret) {
-               fprintf(stderr, "Generate bytecode error\n");
-               ret = -LTTNG_ERR_FILTER_INVAL;
-               goto parse_error;
-       }
-       dbg_printf("done\n");
-       dbg_printf("Size of bytecode generated: %u bytes.\n",
-                       bytecode_get_len(&ctx->bytecode->b));
-
-       lsm->u.enable.bytecode_len = sizeof(ctx->bytecode->b)
-               + bytecode_get_len(&ctx->bytecode->b);
-       lsm->u.enable.expression_len = strlen(filter_expression) + 1;
-
-       /* No need to keep the memory stream. */
-       if (fclose(fmem) != 0) {
-               perror("fclose");
-       }
-
-       *ctxp = ctx;
-       return 0;
-
-parse_error:
-       filter_ir_free(ctx);
-       filter_parser_ctx_free(ctx);
-filter_alloc_error:
-       if (fclose(fmem) != 0) {
-               perror("fclose");
-       }
-error:
-       return ret;
-}
-
-/*
- * Enable event(s) for a channel, possibly with exclusions and a filter.
- * If no event name is specified, all events are enabled.
- * If no channel name is specified, the default name is used.
- * If filter expression is not NULL, the filter is set for the event.
- * If exclusion count is not zero, the exclusions are set for the event.
- * Returns size of returned session payload data or a negative error code.
- */
-int lttng_enable_event_with_exclusions(struct lttng_handle *handle,
-               struct lttng_event *ev, const char *channel_name,
-               const char *original_filter_expression,
-               int exclusion_count, char **exclusion_list)
-{
-       struct lttcomm_session_msg lsm;
-       char *varlen_data;
-       int ret = 0;
-       unsigned int free_filter_expression = 0;
-       struct filter_parser_ctx *ctx = NULL;
        /*
-        * Cast as non-const since we may replace the filter expression
-        * by a dynamically allocated string. Otherwise, the original
-        * string is not modified.
-        */
-       char *filter_expression = (char *) original_filter_expression;
-
-       if (handle == NULL || ev == NULL) {
-               ret = -LTTNG_ERR_INVALID;
-               goto error;
-       }
-
-       /* Empty filter string will always be rejected by the parser
+        * Empty filter string will always be rejected by the parser
         * anyway, so treat this corner-case early to eliminate
         * lttng_fmemopen error for 0-byte allocation.
         */
@@ -931,8 +1104,7 @@ int lttng_enable_event_with_exclusions(struct lttng_handle *handle,
                lttng_ctl_copy_string(ev->name, "*", sizeof(ev->name));
        }
 
-       lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
-       /* FIXME: copying non-packed struct to packed struct. */
+       COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
        memcpy(&lsm.u.enable.event, ev, sizeof(lsm.u.enable.event));
 
        lttng_ctl_copy_string(lsm.session.name, handle->session_name,
@@ -940,24 +1112,7 @@ int lttng_enable_event_with_exclusions(struct lttng_handle *handle,
        lsm.u.enable.exclusion_count = exclusion_count;
        lsm.u.enable.bytecode_len = 0;
 
-       /*
-        * For the JUL domain, a filter is enforced except for the enable all
-        * event. This is done to avoid having the event in all sessions thus
-        * filtering by logger name.
-        */
-       if (exclusion_count == 0 && filter_expression == NULL &&
-                       (handle->domain.type != LTTNG_DOMAIN_JUL &&
-                               handle->domain.type != LTTNG_DOMAIN_LOG4J &&
-                               handle->domain.type != LTTNG_DOMAIN_PYTHON)) {
-               goto ask_sessiond;
-       }
-
-       /*
-        * We have either a filter or some exclusions, so we need to set up
-        * a variable-length memory block from where to send the data
-        */
-
-       /* Parse filter expression */
+       /* Parse filter expression. */
        if (filter_expression != NULL || handle->domain.type == LTTNG_DOMAIN_JUL
                        || handle->domain.type == LTTNG_DOMAIN_LOG4J
                        || handle->domain.type == LTTNG_DOMAIN_PYTHON) {
@@ -970,58 +1125,130 @@ int lttng_enable_event_with_exclusions(struct lttng_handle *handle,
                        agent_filter = set_agent_filter(filter_expression, ev);
                        if (!agent_filter) {
                                if (!filter_expression) {
-                                       /* No JUL and no filter, just skip everything below. */
+                                       /*
+                                        * No JUL and no filter, just skip
+                                        * everything below.
+                                        */
                                        goto ask_sessiond;
                                }
                        } else {
                                /*
-                                * With an agent filter, the original filter has been added to
-                                * it thus replace the filter expression.
+                                * With an agent filter, the original filter has
+                                * been added to it thus replace the filter
+                                * expression.
                                 */
                                filter_expression = agent_filter;
                                free_filter_expression = 1;
                        }
                }
 
-               ret = generate_filter(filter_expression, &lsm, &ctx);
+               ret = filter_parser_ctx_create_from_filter_expression(filter_expression, &ctx);
                if (ret) {
                        goto filter_error;
                }
+
+               lsm.u.enable.bytecode_len = sizeof(ctx->bytecode->b)
+                       + bytecode_get_len(&ctx->bytecode->b);
+               lsm.u.enable.expression_len = strlen(filter_expression) + 1;
        }
 
-       varlen_data = zmalloc(lsm.u.enable.bytecode_len
-                       + lsm.u.enable.expression_len
-                       + LTTNG_SYMBOL_NAME_LEN * exclusion_count);
-       if (!varlen_data) {
+       ret = lttng_dynamic_buffer_set_capacity(&payload.buffer,
+                       lsm.u.enable.bytecode_len +
+                                       lsm.u.enable.expression_len +
+                                       LTTNG_SYMBOL_NAME_LEN *
+                                                       exclusion_count);
+       if (ret) {
                ret = -LTTNG_ERR_EXCLUSION_NOMEM;
                goto mem_error;
        }
 
-       /* Put exclusion names first in the data */
-       while (exclusion_count--) {
-               strncpy(varlen_data + LTTNG_SYMBOL_NAME_LEN * exclusion_count,
-                       *(exclusion_list + exclusion_count), LTTNG_SYMBOL_NAME_LEN);
+       /* Put exclusion names first in the data. */
+       for (i = 0; i < exclusion_count; i++) {
+               size_t exclusion_len;
+
+               exclusion_len = lttng_strnlen(*(exclusion_list + i),
+                               LTTNG_SYMBOL_NAME_LEN);
+               if (exclusion_len == LTTNG_SYMBOL_NAME_LEN) {
+                       /* Exclusion is not NULL-terminated. */
+                       ret = -LTTNG_ERR_INVALID;
+                       goto mem_error;
+               }
+
+               ret = lttng_dynamic_buffer_append(&payload.buffer,
+                               *(exclusion_list + i), LTTNG_SYMBOL_NAME_LEN);
+               if (ret) {
+                       goto mem_error;
+               }
        }
-       /* Add filter expression next */
-       if (lsm.u.enable.expression_len != 0) {
-               memcpy(varlen_data
-                       + LTTNG_SYMBOL_NAME_LEN * lsm.u.enable.exclusion_count,
-                       filter_expression,
-                       lsm.u.enable.expression_len);
+
+       /* Add filter expression next. */
+       if (filter_expression) {
+               ret = lttng_dynamic_buffer_append(&payload.buffer,
+                               filter_expression, lsm.u.enable.expression_len);
+               if (ret) {
+                       goto mem_error;
+               }
        }
-       /* Add filter bytecode next */
+       /* Add filter bytecode next. */
        if (ctx && lsm.u.enable.bytecode_len != 0) {
-               memcpy(varlen_data
-                       + LTTNG_SYMBOL_NAME_LEN * lsm.u.enable.exclusion_count
-                       + lsm.u.enable.expression_len,
-                       &ctx->bytecode->b,
-                       lsm.u.enable.bytecode_len);
+               ret = lttng_dynamic_buffer_append(&payload.buffer,
+                               &ctx->bytecode->b, lsm.u.enable.bytecode_len);
+               if (ret) {
+                       goto mem_error;
+               }
        }
+       if (ev->extended.ptr) {
+               struct lttng_event_extended *ev_ext =
+                       (struct lttng_event_extended *) ev->extended.ptr;
+
+               if (ev_ext->probe_location) {
+                       /*
+                        * lttng_userspace_probe_location_serialize returns the
+                        * number of bytes that was appended to the buffer.
+                        */
+                       ret = lttng_userspace_probe_location_serialize(
+                                       ev_ext->probe_location, &payload);
+                       if (ret < 0) {
+                               goto mem_error;
+                       }
 
-       ret = lttng_ctl_ask_sessiond_varlen(&lsm, varlen_data,
-                       (LTTNG_SYMBOL_NAME_LEN * lsm.u.enable.exclusion_count) +
-                       lsm.u.enable.bytecode_len + lsm.u.enable.expression_len, NULL);
-       free(varlen_data);
+                       /*
+                        * Set the size of the userspace probe location element
+                        * of the buffer so that the receiving side knows where
+                        * to split it.
+                        */
+                       lsm.u.enable.userspace_probe_location_len = ret;
+               }
+       }
+
+       {
+               struct lttng_payload_view view = lttng_payload_view_from_payload(
+                       &payload, 0, -1);
+               int fd_count = lttng_payload_view_get_fd_handle_count(&view);
+               int fd_to_send;
+
+               if (fd_count < 0) {
+                       goto mem_error;
+               }
+
+               assert(fd_count == 0 || fd_count == 1);
+               if (fd_count == 1) {
+                       struct fd_handle *handle =
+                                       lttng_payload_view_pop_fd_handle(&view);
+
+                       if (!handle) {
+                               goto mem_error;
+                       }
+
+                       fd_to_send = fd_handle_get_fd(handle);
+                       fd_handle_put(handle);
+               }
+
+               ret = lttng_ctl_ask_sessiond_fds_varlen(&lsm,
+                               fd_count ? &fd_to_send : NULL, fd_count,
+                               view.buffer.size ? view.buffer.data : NULL,
+                               view.buffer.size, NULL, NULL, 0);
+       }
 
 mem_error:
        if (filter_expression && ctx) {
@@ -1032,16 +1259,18 @@ mem_error:
 filter_error:
        if (free_filter_expression) {
                /*
-                * The filter expression has been replaced and must be freed as it is
-                * not the original filter expression received as a parameter.
+                * The filter expression has been replaced and must be freed as
+                * it is not the original filter expression received as a
+                * parameter.
                 */
                free(filter_expression);
        }
 error:
        /*
-        * Return directly to the caller and don't ask the sessiond since something
-        * went wrong in the parsing of data above.
+        * Return directly to the caller and don't ask the sessiond since
+        * something went wrong in the parsing of data above.
         */
+       lttng_payload_reset(&payload);
        return ret;
 
 ask_sessiond:
@@ -1070,7 +1299,8 @@ int lttng_disable_event_ext(struct lttng_handle *handle,
                goto error;
        }
 
-       /* Empty filter string will always be rejected by the parser
+       /*
+        * Empty filter string will always be rejected by the parser
         * anyway, so treat this corner-case early to eliminate
         * lttng_fmemopen error for 0-byte allocation.
         */
@@ -1091,13 +1321,8 @@ int lttng_disable_event_ext(struct lttng_handle *handle,
        }
 
        lsm.cmd_type = LTTNG_DISABLE_EVENT;
-       if (ev->name[0] == '\0') {
-               /* Disable all events */
-               lttng_ctl_copy_string(ev->name, "*", sizeof(ev->name));
-       }
 
-       lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
-       /* FIXME: copying non-packed struct to packed struct. */
+       COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
        memcpy(&lsm.u.disable.event, ev, sizeof(lsm.u.disable.event));
 
        lttng_ctl_copy_string(lsm.session.name, handle->session_name,
@@ -1134,23 +1359,31 @@ int lttng_disable_event_ext(struct lttng_handle *handle,
                        agent_filter = set_agent_filter(filter_expression, ev);
                        if (!agent_filter) {
                                if (!filter_expression) {
-                                       /* No JUL and no filter, just skip everything below. */
+                                       /*
+                                        * No JUL and no filter, just skip
+                                        * everything below.
+                                        */
                                        goto ask_sessiond;
                                }
                        } else {
                                /*
-                                * With a JUL filter, the original filter has been added to it
-                                * thus replace the filter expression.
+                                * With a JUL filter, the original filter has
+                                * been added to it thus replace the filter
+                                * expression.
                                 */
                                filter_expression = agent_filter;
                                free_filter_expression = 1;
                        }
                }
 
-               ret = generate_filter(filter_expression, &lsm, &ctx);
+               ret = filter_parser_ctx_create_from_filter_expression(filter_expression, &ctx);
                if (ret) {
                        goto filter_error;
                }
+
+               lsm.u.enable.bytecode_len = sizeof(ctx->bytecode->b)
+                       + bytecode_get_len(&ctx->bytecode->b);
+               lsm.u.enable.expression_len = strlen(filter_expression) + 1;
        }
 
        varlen_data = zmalloc(lsm.u.disable.bytecode_len
@@ -1160,13 +1393,13 @@ int lttng_disable_event_ext(struct lttng_handle *handle,
                goto mem_error;
        }
 
-       /* Add filter expression */
+       /* Add filter expression. */
        if (lsm.u.disable.expression_len != 0) {
                memcpy(varlen_data,
                        filter_expression,
                        lsm.u.disable.expression_len);
        }
-       /* Add filter bytecode next */
+       /* Add filter bytecode next. */
        if (ctx && lsm.u.disable.bytecode_len != 0) {
                memcpy(varlen_data
                        + lsm.u.disable.expression_len,
@@ -1174,7 +1407,7 @@ int lttng_disable_event_ext(struct lttng_handle *handle,
                        lsm.u.disable.bytecode_len);
        }
 
-       ret = lttng_ctl_ask_sessiond_varlen(&lsm, varlen_data,
+       ret = lttng_ctl_ask_sessiond_varlen_no_cmd_header(&lsm, varlen_data,
                        lsm.u.disable.bytecode_len + lsm.u.disable.expression_len, NULL);
        free(varlen_data);
 
@@ -1187,15 +1420,16 @@ mem_error:
 filter_error:
        if (free_filter_expression) {
                /*
-                * The filter expression has been replaced and must be freed as it is
-                * not the original filter expression received as a parameter.
+                * The filter expression has been replaced and must be freed as
+                * it is not the original filter expression received as a
+                * parameter.
                 */
                free(filter_expression);
        }
 error:
        /*
-        * Return directly to the caller and don't ask the sessiond since something
-        * went wrong in the parsing of data above.
+        * Return directly to the caller and don't ask the sessiond since
+        * something went wrong in the parsing of data above.
         */
        return ret;
 
@@ -1205,10 +1439,10 @@ ask_sessiond:
 }
 
 /*
- *  Disable event(s) of a channel and domain.
- *  If no event name is specified, all events are disabled.
- *  If no channel name is specified, the default 'channel0' is used.
- *  Returns size of returned session payload data or a negative error code.
+ * Disable event(s) of a channel and domain.
+ * If no event name is specified, all events are disabled.
+ * If no channel name is specified, the default 'channel0' is used.
+ * Returns size of returned session payload data or a negative error code.
  */
 int lttng_disable_event(struct lttng_handle *handle, const char *name,
                const char *channel_name)
@@ -1216,34 +1450,129 @@ int lttng_disable_event(struct lttng_handle *handle, const char *name,
        struct lttng_event ev;
 
        memset(&ev, 0, sizeof(ev));
+       ev.loglevel = -1;
        ev.type = LTTNG_EVENT_ALL;
        lttng_ctl_copy_string(ev.name, name, sizeof(ev.name));
        return lttng_disable_event_ext(handle, &ev, channel_name, NULL);
 }
 
+struct lttng_channel *lttng_channel_create(struct lttng_domain *domain)
+{
+       struct lttng_channel *channel = NULL;
+       struct lttng_channel_extended *extended = NULL;
+
+       if (!domain) {
+               goto error;
+       }
+
+       /* Validate domain. */
+       switch (domain->type) {
+       case LTTNG_DOMAIN_UST:
+               switch (domain->buf_type) {
+               case LTTNG_BUFFER_PER_UID:
+               case LTTNG_BUFFER_PER_PID:
+                       break;
+               default:
+                       goto error;
+               }
+               break;
+       case LTTNG_DOMAIN_KERNEL:
+               if (domain->buf_type != LTTNG_BUFFER_GLOBAL) {
+                       goto error;
+               }
+               break;
+       default:
+               goto error;
+       }
+
+       channel = zmalloc(sizeof(*channel));
+       if (!channel) {
+               goto error;
+       }
+
+       extended = zmalloc(sizeof(*extended));
+       if (!extended) {
+               goto error;
+       }
+
+       channel->attr.extended.ptr = extended;
+
+       lttng_channel_set_default_attr(domain, &channel->attr);
+       return channel;
+error:
+       free(channel);
+       free(extended);
+       return NULL;
+}
+
+void lttng_channel_destroy(struct lttng_channel *channel)
+{
+       if (!channel) {
+               return;
+       }
+
+       if (channel->attr.extended.ptr) {
+               free(channel->attr.extended.ptr);
+       }
+       free(channel);
+}
+
 /*
- *  Enable channel per domain
- *  Returns size of returned session payload data or a negative error code.
+ * Enable channel per domain
+ * Returns size of returned session payload data or a negative error code.
  */
 int lttng_enable_channel(struct lttng_handle *handle,
-               struct lttng_channel *chan)
+               struct lttng_channel *in_chan)
 {
        struct lttcomm_session_msg lsm;
+       size_t total_buffer_size_needed_per_cpu = 0;
 
-       /*
-        * NULL arguments are forbidden. No default values.
-        */
-       if (handle == NULL || chan == NULL) {
+       /* NULL arguments are forbidden. No default values. */
+       if (handle == NULL || in_chan == NULL) {
                return -LTTNG_ERR_INVALID;
        }
 
        memset(&lsm, 0, sizeof(lsm));
+       memcpy(&lsm.u.channel.chan, in_chan, sizeof(lsm.u.channel.chan));
+       lsm.u.channel.chan.attr.extended.ptr = NULL;
 
-       memcpy(&lsm.u.channel.chan, chan, sizeof(lsm.u.channel.chan));
+       if (!in_chan->attr.extended.ptr) {
+               struct lttng_channel *channel;
+               struct lttng_channel_extended *extended;
 
-       lsm.cmd_type = LTTNG_ENABLE_CHANNEL;
+               channel = lttng_channel_create(&handle->domain);
+               if (!channel) {
+                       return -LTTNG_ERR_NOMEM;
+               }
 
-       lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
+               /*
+                * Create a new channel in order to use default extended
+                * attribute values.
+                */
+               extended = (struct lttng_channel_extended *)
+                               channel->attr.extended.ptr;
+               memcpy(&lsm.u.channel.extended, extended, sizeof(*extended));
+               lttng_channel_destroy(channel);
+       } else {
+               struct lttng_channel_extended *extended;
+
+               extended = (struct lttng_channel_extended *)
+                               in_chan->attr.extended.ptr;
+               memcpy(&lsm.u.channel.extended, extended, sizeof(*extended));
+       }
+
+       /*
+        * Verify that the amount of memory required to create the requested
+        * buffer is available on the system at the moment.
+        */
+       total_buffer_size_needed_per_cpu = lsm.u.channel.chan.attr.num_subbuf *
+               lsm.u.channel.chan.attr.subbuf_size;
+       if (!check_enough_available_memory(total_buffer_size_needed_per_cpu)) {
+               return -LTTNG_ERR_NOMEM;
+       }
+
+       lsm.cmd_type = LTTNG_ENABLE_CHANNEL;
+       COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
 
        lttng_ctl_copy_string(lsm.session.name, handle->session_name,
                        sizeof(lsm.session.name));
@@ -1252,14 +1581,14 @@ int lttng_enable_channel(struct lttng_handle *handle,
 }
 
 /*
- *  All tracing will be stopped for registered events of the channel.
- *  Returns size of returned session payload data or a negative error code.
+ * All tracing will be stopped for registered events of the channel.
+ * Returns size of returned session payload data or a negative error code.
  */
 int lttng_disable_channel(struct lttng_handle *handle, const char *name)
 {
        struct lttcomm_session_msg lsm;
 
-       /* Safety check. Both are mandatory */
+       /* Safety check. Both are mandatory. */
        if (handle == NULL || name == NULL) {
                return -LTTNG_ERR_INVALID;
        }
@@ -1271,7 +1600,7 @@ int lttng_disable_channel(struct lttng_handle *handle, const char *name)
        lttng_ctl_copy_string(lsm.u.disable.channel_name, name,
                        sizeof(lsm.u.disable.channel_name));
 
-       lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
+       COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
 
        lttng_ctl_copy_string(lsm.session.name, handle->session_name,
                        sizeof(lsm.session.name));
@@ -1280,10 +1609,10 @@ int lttng_disable_channel(struct lttng_handle *handle, const char *name)
 }
 
 /*
- *  Lists all available tracepoints of domain.
- *  Sets the contents of the events array.
- *  Returns the number of lttng_event entries in events;
- *  on error, returns a negative value.
+ * Lists all available tracepoints of domain.
+ * Sets the contents of the events array.
+ * Returns the number of lttng_event entries in events;
+ * on error, returns a negative value.
  */
 int lttng_list_tracepoints(struct lttng_handle *handle,
                struct lttng_event **events)
@@ -1297,7 +1626,7 @@ int lttng_list_tracepoints(struct lttng_handle *handle,
 
        memset(&lsm, 0, sizeof(lsm));
        lsm.cmd_type = LTTNG_LIST_TRACEPOINTS;
-       lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
+       COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
 
        ret = lttng_ctl_ask_sessiond(&lsm, (void **) events);
        if (ret < 0) {
@@ -1308,10 +1637,10 @@ int lttng_list_tracepoints(struct lttng_handle *handle,
 }
 
 /*
- *  Lists all available tracepoint fields of domain.
- *  Sets the contents of the event field array.
- *  Returns the number of lttng_event_field entries in events;
- *  on error, returns a negative value.
+ * Lists all available tracepoint fields of domain.
+ * Sets the contents of the event field array.
+ * Returns the number of lttng_event_field entries in events;
+ * on error, returns a negative value.
  */
 int lttng_list_tracepoint_fields(struct lttng_handle *handle,
                struct lttng_event_field **fields)
@@ -1325,7 +1654,7 @@ int lttng_list_tracepoint_fields(struct lttng_handle *handle,
 
        memset(&lsm, 0, sizeof(lsm));
        lsm.cmd_type = LTTNG_LIST_TRACEPOINT_FIELDS;
-       lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
+       COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
 
        ret = lttng_ctl_ask_sessiond(&lsm, (void **) fields);
        if (ret < 0) {
@@ -1336,11 +1665,11 @@ int lttng_list_tracepoint_fields(struct lttng_handle *handle,
 }
 
 /*
- *  Lists all available kernel system calls. Allocates and sets the contents of
- *  the events array.
+ * Lists all available kernel system calls. Allocates and sets the contents of
+ * the events array.
  *
- *  Returns the number of lttng_event entries in events; on error, returns a
- *  negative value.
+ * Returns the number of lttng_event entries in events; on error, returns a
+ * negative value.
  */
 int lttng_list_syscalls(struct lttng_event **events)
 {
@@ -1365,115 +1694,435 @@ int lttng_list_syscalls(struct lttng_event **events)
 }
 
 /*
- *  Returns a human readable string describing
- *  the error code (a negative value).
+ * Returns a human readable string describing
+ * the error code (a negative value).
  */
 const char *lttng_strerror(int code)
 {
        return error_get_str(code);
 }
 
-/*
- * Create a brand new session using name and url for destination.
- *
- * Returns LTTNG_OK on success or a negative error code.
- */
-int lttng_create_session(const char *name, const char *url)
+enum lttng_error_code lttng_create_session_ext(
+               struct lttng_session_descriptor *session_descriptor)
 {
+       enum lttng_error_code ret_code;
+       struct lttcomm_session_msg lsm = {
+               .cmd_type = LTTNG_CREATE_SESSION_EXT,
+       };
+       void *reply = NULL;
+       struct lttng_buffer_view reply_view;
+       int reply_ret;
+       bool sessiond_must_generate_ouput;
+       struct lttng_dynamic_buffer payload;
        int ret;
-       ssize_t size;
-       struct lttcomm_session_msg lsm;
-       struct lttng_uri *uris = NULL;
+       size_t descriptor_size;
+       struct lttng_session_descriptor *descriptor_reply = NULL;
 
-       if (name == NULL) {
-               return -LTTNG_ERR_INVALID;
+       lttng_dynamic_buffer_init(&payload);
+       if (!session_descriptor) {
+               ret_code = LTTNG_ERR_INVALID;
+               goto end;
        }
 
-       memset(&lsm, 0, sizeof(lsm));
+       sessiond_must_generate_ouput =
+                       !lttng_session_descriptor_is_output_destination_initialized(
+                               session_descriptor);
+       if (sessiond_must_generate_ouput) {
+               const char *home_dir = utils_get_home_dir();
+               size_t home_dir_len = home_dir ? strlen(home_dir) + 1 : 0;
 
-       lsm.cmd_type = LTTNG_CREATE_SESSION;
-       lttng_ctl_copy_string(lsm.session.name, name, sizeof(lsm.session.name));
+               if (!home_dir || home_dir_len > LTTNG_PATH_MAX) {
+                       ret_code = LTTNG_ERR_FATAL;
+                       goto end;
+               }
 
-       /* There should never be a data URL */
-       size = uri_parse_str_urls(url, NULL, &uris);
-       if (size < 0) {
-               return -LTTNG_ERR_INVALID;
+               lsm.u.create_session.home_dir_size = (uint16_t) home_dir_len;
+               ret = lttng_dynamic_buffer_append(&payload, home_dir,
+                               home_dir_len);
+               if (ret) {
+                       ret_code = LTTNG_ERR_NOMEM;
+                       goto end;
+               }
        }
 
-       lsm.u.uri.size = size;
-
-       ret = lttng_ctl_ask_sessiond_varlen(&lsm, uris,
-                       sizeof(struct lttng_uri) * size, NULL);
-
-       free(uris);
-       return ret;
-}
-
-/*
- *  Destroy session using name.
- *  Returns size of returned session payload data or a negative error code.
- */
-int lttng_destroy_session(const char *session_name)
-{
-       struct lttcomm_session_msg lsm;
-
-       if (session_name == NULL) {
-               return -LTTNG_ERR_INVALID;
+       descriptor_size = payload.size;
+       ret = lttng_session_descriptor_serialize(session_descriptor,
+                       &payload);
+       if (ret) {
+               ret_code = LTTNG_ERR_INVALID;
+               goto end;
        }
+       descriptor_size = payload.size - descriptor_size;
+       lsm.u.create_session.session_descriptor_size = descriptor_size;
 
-       memset(&lsm, 0, sizeof(lsm));
-       lsm.cmd_type = LTTNG_DESTROY_SESSION;
-
-       lttng_ctl_copy_string(lsm.session.name, session_name,
-                       sizeof(lsm.session.name));
+       /* Command returns a session descriptor on success. */
+       reply_ret = lttng_ctl_ask_sessiond_varlen_no_cmd_header(&lsm, payload.data,
+                       payload.size, &reply);
+       if (reply_ret < 0) {
+               ret_code = -reply_ret;
+               goto end;
+       } else if (reply_ret == 0) {
+               /* Socket unexpectedly closed by the session daemon. */
+               ret_code = LTTNG_ERR_FATAL;
+               goto end;
+       }
 
-       return lttng_ctl_ask_sessiond(&lsm, NULL);
+       reply_view = lttng_buffer_view_init(reply, 0, reply_ret);
+       ret = lttng_session_descriptor_create_from_buffer(&reply_view,
+                       &descriptor_reply);
+       if (ret < 0) {
+               ret_code = LTTNG_ERR_FATAL;
+               goto end;
+       }
+       ret_code = LTTNG_OK;
+       lttng_session_descriptor_assign(session_descriptor, descriptor_reply);
+end:
+       free(reply);
+       lttng_dynamic_buffer_reset(&payload);
+       lttng_session_descriptor_destroy(descriptor_reply);
+       return ret_code;
 }
 
 /*
- *  Ask the session daemon for all available sessions.
- *  Sets the contents of the sessions array.
- *  Returns the number of lttng_session entries in sessions;
- *  on error, returns a negative value.
+ * Create a new session using name and url for destination.
+ *
+ * Return 0 on success else a negative LTTng error code.
  */
-int lttng_list_sessions(struct lttng_session **sessions)
+int lttng_create_session(const char *name, const char *url)
 {
        int ret;
-       struct lttcomm_session_msg lsm;
+       ssize_t size;
+       struct lttng_uri *uris = NULL;
+       struct lttng_session_descriptor *descriptor = NULL;
+       enum lttng_error_code ret_code;
 
-       memset(&lsm, 0, sizeof(lsm));
-       lsm.cmd_type = LTTNG_LIST_SESSIONS;
-       ret = lttng_ctl_ask_sessiond(&lsm, (void**) sessions);
-       if (ret < 0) {
-               return ret;
+       if (!name) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
        }
 
-       return ret / sizeof(struct lttng_session);
+       size = uri_parse_str_urls(url, NULL, &uris);
+       if (size < 0) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
+       switch (size) {
+       case 0:
+               descriptor = lttng_session_descriptor_create(name);
+               break;
+       case 1:
+               if (uris[0].dtype != LTTNG_DST_PATH) {
+                       ret = -LTTNG_ERR_INVALID;
+                       goto end;
+               }
+               descriptor = lttng_session_descriptor_local_create(name,
+                               uris[0].dst.path);
+               break;
+       case 2:
+               descriptor = lttng_session_descriptor_network_create(name, url,
+                               NULL);
+               break;
+       default:
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
+       if (!descriptor) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
+       ret_code = lttng_create_session_ext(descriptor);
+       ret = ret_code == LTTNG_OK ? 0 : -ret_code;
+end:
+       lttng_session_descriptor_destroy(descriptor);
+       free(uris);
+       return ret;
 }
 
 /*
- *  Ask the session daemon for all available domains of a session.
- *  Sets the contents of the domains array.
- *  Returns the number of lttng_domain entries in domains;
- *  on error, returns a negative value.
+ * Create a session exclusively used for snapshot.
+ *
+ * Return 0 on success else a negative LTTng error code.
  */
-int lttng_list_domains(const char *session_name,
-               struct lttng_domain **domains)
+int lttng_create_session_snapshot(const char *name, const char *snapshot_url)
 {
        int ret;
-       struct lttcomm_session_msg lsm;
+       enum lttng_error_code ret_code;
+       ssize_t size;
+       struct lttng_uri *uris = NULL;
+       struct lttng_session_descriptor *descriptor = NULL;
 
-       if (session_name == NULL) {
-               return -LTTNG_ERR_INVALID;
+       if (!name) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
        }
 
-       memset(&lsm, 0, sizeof(lsm));
-       lsm.cmd_type = LTTNG_LIST_DOMAINS;
-
-       lttng_ctl_copy_string(lsm.session.name, session_name,
-                       sizeof(lsm.session.name));
-
-       ret = lttng_ctl_ask_sessiond(&lsm, (void**) domains);
+       size = uri_parse_str_urls(snapshot_url, NULL, &uris);
+       if (size < 0) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
+       /*
+        * If the user does not specify a custom subdir, use the session name.
+        */
+       if (size > 0 && uris[0].dtype != LTTNG_DST_PATH &&
+                       strlen(uris[0].subdir) == 0) {
+               ret = snprintf(uris[0].subdir, sizeof(uris[0].subdir), "%s",
+                               name);
+               if (ret < 0) {
+                       PERROR("Failed to set session name as network destination sub-directory");
+                       ret = -LTTNG_ERR_FATAL;
+                       goto end;
+               } else if (ret >= sizeof(uris[0].subdir)) {
+                       /* Truncated output. */
+                       ret = -LTTNG_ERR_INVALID;
+                       goto end;
+               }
+       }
+
+       switch (size) {
+       case 0:
+               descriptor = lttng_session_descriptor_snapshot_create(name);
+               break;
+       case 1:
+               if (uris[0].dtype != LTTNG_DST_PATH) {
+                       ret = -LTTNG_ERR_INVALID;
+                       goto end;
+               }
+               descriptor = lttng_session_descriptor_snapshot_local_create(
+                               name,
+                               uris[0].dst.path);
+               break;
+       case 2:
+               descriptor = lttng_session_descriptor_snapshot_network_create(
+                               name,
+                               snapshot_url,
+                               NULL);
+               break;
+       default:
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
+       if (!descriptor) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
+       ret_code = lttng_create_session_ext(descriptor);
+       ret = ret_code == LTTNG_OK ? 0 : -ret_code;
+end:
+       lttng_session_descriptor_destroy(descriptor);
+       free(uris);
+       return ret;
+}
+
+/*
+ * Create a session exclusively used for live.
+ *
+ * Return 0 on success else a negative LTTng error code.
+ */
+int lttng_create_session_live(const char *name, const char *url,
+               unsigned int timer_interval)
+{
+       int ret;
+       enum lttng_error_code ret_code;
+       struct lttng_session_descriptor *descriptor = NULL;
+
+       if (!name) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
+
+       if (url) {
+               descriptor = lttng_session_descriptor_live_network_create(
+                               name, url, NULL, timer_interval);
+       } else {
+               descriptor = lttng_session_descriptor_live_create(
+                               name, timer_interval);
+       }
+       if (!descriptor) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
+       ret_code = lttng_create_session_ext(descriptor);
+       ret = ret_code == LTTNG_OK ? 0 : -ret_code;
+end:
+       lttng_session_descriptor_destroy(descriptor);
+       return ret;
+}
+
+/*
+ * Stop the session and wait for the data before destroying it
+ *
+ * Return 0 on success else a negative LTTng error code.
+ */
+int lttng_destroy_session(const char *session_name)
+{
+       int ret;
+       enum lttng_error_code ret_code;
+       enum lttng_destruction_handle_status status;
+       struct lttng_destruction_handle *handle = NULL;
+
+       /*
+        * Stop the tracing and wait for the data to be
+        * consumed.
+        */
+       ret = _lttng_stop_tracing(session_name, 1);
+       if (ret && ret != -LTTNG_ERR_TRACE_ALREADY_STOPPED) {
+               goto end;
+       }
+
+       ret_code = lttng_destroy_session_ext(session_name, &handle);
+       if (ret_code != LTTNG_OK) {
+               ret = (int) -ret_code;
+               goto end;
+       }
+       assert(handle);
+
+       /* Block until the completion of the destruction of the session. */
+       status = lttng_destruction_handle_wait_for_completion(handle, -1);
+       if (status != LTTNG_DESTRUCTION_HANDLE_STATUS_COMPLETED) {
+               ret = -LTTNG_ERR_UNK;
+               goto end;
+       }
+
+       status = lttng_destruction_handle_get_result(handle, &ret_code);
+       if (status != LTTNG_DESTRUCTION_HANDLE_STATUS_OK) {
+               ret = -LTTNG_ERR_UNK;
+               goto end;
+       }
+       ret = ret_code == LTTNG_OK ? 0 : -ret_code;
+end:
+       lttng_destruction_handle_destroy(handle);
+       return ret;
+}
+
+/*
+ * Destroy the session without waiting for the data.
+ */
+int lttng_destroy_session_no_wait(const char *session_name)
+{
+       enum lttng_error_code ret_code;
+
+       ret_code = lttng_destroy_session_ext(session_name, NULL);
+       return ret_code == LTTNG_OK ? ret_code : -ret_code;
+}
+
+/*
+ * Ask the session daemon for all available sessions.
+ * Sets the contents of the sessions array.
+ * Returns the number of lttng_session entries in sessions;
+ * on error, returns a negative value.
+ */
+int lttng_list_sessions(struct lttng_session **out_sessions)
+{
+       int ret;
+       struct lttcomm_session_msg lsm;
+       const size_t session_size = sizeof(struct lttng_session) +
+                       sizeof(struct lttng_session_extended);
+       size_t session_count, i;
+       struct lttng_session_extended *sessions_extended_begin;
+       struct lttng_session *sessions = NULL;
+
+       memset(&lsm, 0, sizeof(lsm));
+       lsm.cmd_type = LTTNG_LIST_SESSIONS;
+       ret = lttng_ctl_ask_sessiond(&lsm, (void**) &sessions);
+       if (ret <= 0) {
+               goto end;
+       }
+       if (!sessions) {
+               ret = -LTTNG_ERR_FATAL;
+               goto end;
+       }
+
+       if (ret % session_size) {
+               ret = -LTTNG_ERR_UNK;
+               free(sessions);
+               *out_sessions = NULL;
+               goto end;
+       }
+       session_count = (size_t) ret / session_size;
+       sessions_extended_begin = (struct lttng_session_extended *)
+                       (&sessions[session_count]);
+
+       /* Set extended session info pointers. */
+       for (i = 0; i < session_count; i++) {
+               struct lttng_session *session = &sessions[i];
+               struct lttng_session_extended *extended =
+                               &(sessions_extended_begin[i]);
+
+               session->extended.ptr = extended;
+       }
+
+       ret = (int) session_count;
+       *out_sessions = sessions;
+end:
+       return ret;
+}
+
+enum lttng_error_code lttng_session_get_creation_time(
+               const struct lttng_session *session, uint64_t *creation_time)
+{
+       enum lttng_error_code ret = LTTNG_OK;
+       struct lttng_session_extended *extended;
+
+       if (!session || !creation_time || !session->extended.ptr) {
+               ret = LTTNG_ERR_INVALID;
+               goto end;
+       }
+
+       extended = session->extended.ptr;
+       if (!extended->creation_time.is_set) {
+               /* Not created on the session daemon yet. */
+               ret = LTTNG_ERR_SESSION_NOT_EXIST;
+               goto end;
+       }
+       *creation_time = extended->creation_time.value;
+end:
+       return ret;
+}
+
+int lttng_set_session_shm_path(const char *session_name,
+               const char *shm_path)
+{
+       struct lttcomm_session_msg lsm;
+
+       if (session_name == NULL) {
+               return -LTTNG_ERR_INVALID;
+       }
+
+       memset(&lsm, 0, sizeof(lsm));
+       lsm.cmd_type = LTTNG_SET_SESSION_SHM_PATH;
+
+       lttng_ctl_copy_string(lsm.session.name, session_name,
+                       sizeof(lsm.session.name));
+       lttng_ctl_copy_string(lsm.u.set_shm_path.shm_path, shm_path,
+                       sizeof(lsm.u.set_shm_path.shm_path));
+
+       return lttng_ctl_ask_sessiond(&lsm, NULL);
+}
+
+/*
+ * Ask the session daemon for all available domains of a session.
+ * Sets the contents of the domains array.
+ * Returns the number of lttng_domain entries in domains;
+ * on error, returns a negative value.
+ */
+int lttng_list_domains(const char *session_name,
+               struct lttng_domain **domains)
+{
+       int ret;
+       struct lttcomm_session_msg lsm;
+
+       if (session_name == NULL) {
+               return -LTTNG_ERR_INVALID;
+       }
+
+       memset(&lsm, 0, sizeof(lsm));
+       lsm.cmd_type = LTTNG_LIST_DOMAINS;
+
+       lttng_ctl_copy_string(lsm.session.name, session_name,
+                       sizeof(lsm.session.name));
+
+       ret = lttng_ctl_ask_sessiond(&lsm, (void**) domains);
        if (ret < 0) {
                return ret;
        }
@@ -1482,19 +2131,24 @@ int lttng_list_domains(const char *session_name,
 }
 
 /*
- *  Ask the session daemon for all available channels of a session.
- *  Sets the contents of the channels array.
- *  Returns the number of lttng_channel entries in channels;
- *  on error, returns a negative value.
+ * Ask the session daemon for all available channels of a session.
+ * Sets the contents of the channels array.
+ * Returns the number of lttng_channel entries in channels;
+ * on error, returns a negative value.
  */
 int lttng_list_channels(struct lttng_handle *handle,
                struct lttng_channel **channels)
 {
        int ret;
+       size_t channel_count, i;
+       const size_t channel_size = sizeof(struct lttng_channel) +
+                       sizeof(struct lttng_channel_extended);
        struct lttcomm_session_msg lsm;
+       void *extended_at;
 
        if (handle == NULL) {
-               return -LTTNG_ERR_INVALID;
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
        }
 
        memset(&lsm, 0, sizeof(lsm));
@@ -1502,48 +2156,348 @@ int lttng_list_channels(struct lttng_handle *handle,
        lttng_ctl_copy_string(lsm.session.name, handle->session_name,
                        sizeof(lsm.session.name));
 
-       lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
+       COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
 
        ret = lttng_ctl_ask_sessiond(&lsm, (void**) channels);
        if (ret < 0) {
-               return ret;
+               goto end;
+       }
+
+       if (ret % channel_size) {
+               ret = -LTTNG_ERR_UNK;
+               free(*channels);
+               *channels = NULL;
+               goto end;
        }
+       channel_count = (size_t) ret / channel_size;
+
+       /* Set extended info pointers */
+       extended_at = ((void *) *channels) +
+                       channel_count * sizeof(struct lttng_channel);
+       for (i = 0; i < channel_count; i++) {
+               struct lttng_channel *chan = &(*channels)[i];
 
-       return ret / sizeof(struct lttng_channel);
+               chan->attr.extended.ptr = extended_at;
+               extended_at += sizeof(struct lttng_channel_extended);
+       }
+
+       ret = (int) channel_count;
+end:
+       return ret;
 }
 
 /*
- *  Ask the session daemon for all available events of a session channel.
- *  Sets the contents of the events array.
- *  Returns the number of lttng_event entries in events;
- *  on error, returns a negative value.
+ * Ask the session daemon for all available events of a session channel.
+ * Sets the contents of the events array.
+ * Returns the number of lttng_event entries in events;
+ * on error, returns a negative value.
  */
 int lttng_list_events(struct lttng_handle *handle,
                const char *channel_name, struct lttng_event **events)
 {
        int ret;
-       struct lttcomm_session_msg lsm;
+       struct lttcomm_session_msg lsm = {};
+       const struct lttcomm_event_command_header *cmd_header = NULL;
+       uint32_t nb_events, i;
+       const void *comm_ext_at;
+       struct lttng_dynamic_buffer listing;
+       size_t storage_req;
+       struct lttng_payload payload;
+       struct lttng_payload payload_copy;
+       struct lttng_payload_view lsm_view =
+                       lttng_payload_view_init_from_buffer(
+                               (const char *) &lsm, 0, sizeof(lsm));
+       struct lttng_buffer_view cmd_header_view;
+       struct lttng_buffer_view cmd_payload_view;
+       struct lttng_buffer_view flat_events_view;
+       struct lttng_buffer_view ext_view;
 
        /* Safety check. An handle and channel name are mandatory */
        if (handle == NULL || channel_name == NULL) {
-               return -LTTNG_ERR_INVALID;
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
        }
 
-       memset(&lsm, 0, sizeof(lsm));
+       lttng_payload_init(&payload);
+       lttng_payload_init(&payload_copy);
+
        lsm.cmd_type = LTTNG_LIST_EVENTS;
        lttng_ctl_copy_string(lsm.session.name, handle->session_name,
                        sizeof(lsm.session.name));
        lttng_ctl_copy_string(lsm.u.list.channel_name, channel_name,
                        sizeof(lsm.u.list.channel_name));
+       COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
 
-       lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
-
-       ret = lttng_ctl_ask_sessiond(&lsm, (void**) events);
+       ret = lttng_ctl_ask_sessiond_payload(&lsm_view, &payload);
        if (ret < 0) {
-               return ret;
+               goto end;
        }
 
-       return ret / sizeof(struct lttng_event);
+       /*
+        * A copy of the payload is performed since it will be
+        * consumed twice. Consuming the same payload twice is invalid since
+        * it will cause any received file descriptor to become "shared"
+        * between different instances of the resulting objects.
+        */
+       ret = lttng_payload_copy(&payload, &payload_copy);
+       if (ret) {
+               ret = -LTTNG_ERR_NOMEM;
+               goto end;
+       }
+
+       cmd_header_view = lttng_buffer_view_from_dynamic_buffer(
+               &payload.buffer, 0, sizeof(*cmd_header));
+       if (!lttng_buffer_view_is_valid(&cmd_header_view)) {
+               ret = -LTTNG_ERR_INVALID_PROTOCOL;
+               goto end;
+       }
+
+       cmd_header = (typeof(cmd_header)) cmd_header_view.data;
+
+       /* Set number of events and free command header */
+       nb_events = cmd_header->nb_events;
+       if (nb_events > INT_MAX) {
+               ret = -LTTNG_ERR_OVERFLOW;
+               goto end;
+       }
+
+       cmd_payload_view = lttng_buffer_view_from_dynamic_buffer(
+                       &payload.buffer, sizeof(*cmd_header), -1);
+
+       /*
+        * The buffer that is returned must contain a "flat" version of
+        * the events that are returned. In other words, all pointers
+        * within an lttng_event must point to a location within the returned
+        * buffer so that the user may free everything by simply calling free()
+        * on the returned buffer. This is needed in order to maintain API
+        * compatibility.
+        *
+        * A first pass is performed to compute the size of the buffer that
+        * must be allocated. A second pass is then performed to setup
+        * the returned events so that their members always point within the
+        * buffer.
+        *
+        * The layout of the returned buffer is as follows:
+        *   - struct lttng_event[nb_events],
+        *   - nb_events times the following:
+        *     - struct lttng_event_extended,
+        *     - flattened version of userspace_probe_location
+        *     - filter_expression
+        *     - exclusions
+        *     - padding to align to 64-bits
+        */
+       ext_view = lttng_buffer_view_from_view(&cmd_payload_view,
+                       nb_events * sizeof(struct lttng_event), -1);
+       comm_ext_at = ext_view.data;
+       storage_req = nb_events * sizeof(struct lttng_event);
+       {
+               struct lttng_payload_view payload_view =
+                               lttng_payload_view_from_payload(&payload, 0, -1);
+
+               for (i = 0; i < nb_events; i++) {
+                       const struct lttcomm_event_extended_header *ext_comm =
+                                       (struct lttcomm_event_extended_header *)
+                                                       comm_ext_at;
+                       int probe_storage_req = 0;
+
+                       comm_ext_at += sizeof(*ext_comm);
+                       comm_ext_at += ext_comm->filter_len;
+                       comm_ext_at += ext_comm->nb_exclusions *
+                                       LTTNG_SYMBOL_NAME_LEN;
+
+                       if (ext_comm->userspace_probe_location_len) {
+                               struct lttng_userspace_probe_location
+                                               *probe_location = NULL;
+                               struct lttng_payload_view probe_location_view = lttng_payload_view_from_view(
+                                               &payload_view,
+                                               (const char *) comm_ext_at -
+                                                               payload_view.buffer.data,
+                                               ext_comm->userspace_probe_location_len);
+
+                               if (!lttng_payload_view_is_valid(&probe_location_view)) {
+                                       ret = -LTTNG_ERR_PROBE_LOCATION_INVAL;
+                                       goto end;
+                               }
+
+                               /*
+                                * Create a temporary userspace probe location
+                                * to determine the size needed by a "flattened"
+                                * version of that same probe location.
+                                */
+                               ret = lttng_userspace_probe_location_create_from_payload(
+                                               &probe_location_view,
+                                               &probe_location);
+                               if (ret < 0) {
+                                       ret = -LTTNG_ERR_PROBE_LOCATION_INVAL;
+                                       goto end;
+                               }
+
+                               ret = lttng_userspace_probe_location_flatten(
+                                               probe_location, NULL);
+                               lttng_userspace_probe_location_destroy(
+                                               probe_location);
+                               if (ret < 0) {
+                                       ret = -LTTNG_ERR_PROBE_LOCATION_INVAL;
+                                       goto end;
+                               }
+
+                               probe_storage_req = ret;
+                               comm_ext_at += ext_comm->userspace_probe_location_len;
+                       }
+
+                       storage_req += sizeof(struct lttng_event_extended);
+                       storage_req += ext_comm->filter_len;
+                       storage_req += ext_comm->nb_exclusions *
+                                       LTTNG_SYMBOL_NAME_LEN;
+                       /* Padding to ensure the flat probe is aligned. */
+                       storage_req = ALIGN_TO(storage_req, sizeof(uint64_t));
+                       storage_req += probe_storage_req;
+               }
+       }
+
+       lttng_dynamic_buffer_init(&listing);
+       /*
+        * We must ensure that "listing" is never resized so as to preserve
+        * the validity of the flattened objects.
+        */
+       ret = lttng_dynamic_buffer_set_capacity(&listing, storage_req);
+       if (ret) {
+               ret = -LTTNG_ERR_NOMEM;
+               goto end;
+       }
+
+       cmd_payload_view = lttng_buffer_view_from_dynamic_buffer(
+               &payload_copy.buffer, sizeof(*cmd_header), -1);
+       flat_events_view = lttng_buffer_view_from_view(&cmd_payload_view, 0,
+                       nb_events * sizeof(struct lttng_event));
+       ret = lttng_dynamic_buffer_append_view(&listing, &flat_events_view);
+       if (ret) {
+               ret = -LTTNG_ERR_NOMEM;
+               goto free_dynamic_buffer;
+       }
+
+       ext_view = lttng_buffer_view_from_view(&cmd_payload_view,
+                       nb_events * sizeof(struct lttng_event), -1);
+       comm_ext_at = ext_view.data;
+
+       {
+               struct lttng_payload_view payload_copy_view =
+                               lttng_payload_view_from_payload(
+                                               &payload_copy, 0, -1);
+
+               for (i = 0; i < nb_events; i++) {
+                       struct lttng_event *event = (typeof(event))(
+                                       listing.data +
+                                       (sizeof(struct lttng_event) * i));
+                       const struct lttcomm_event_extended_header *ext_comm =
+                                       (typeof(ext_comm)) comm_ext_at;
+                       struct lttng_event_extended *event_extended =
+                                       (typeof(event_extended))(listing.data +
+                                                       listing.size);
+
+                       /* Insert struct lttng_event_extended. */
+                       ret = lttng_dynamic_buffer_set_size(&listing,
+                                       listing.size + sizeof(*event_extended));
+                       if (ret) {
+                               ret = -LTTNG_ERR_NOMEM;
+                               goto free_dynamic_buffer;
+                       }
+                       event->extended.ptr = event_extended;
+
+                       comm_ext_at += sizeof(*ext_comm);
+
+                       /* Insert filter expression. */
+                       if (ext_comm->filter_len) {
+                               event_extended->filter_expression =
+                                               listing.data + listing.size;
+                               ret = lttng_dynamic_buffer_append(&listing,
+                                               comm_ext_at,
+                                               ext_comm->filter_len);
+                               if (ret) {
+                                       ret = -LTTNG_ERR_NOMEM;
+                                       goto free_dynamic_buffer;
+                               }
+                               comm_ext_at += ext_comm->filter_len;
+                       }
+
+                       /* Insert exclusions. */
+                       if (ext_comm->nb_exclusions) {
+                               event_extended->exclusions.count =
+                                               ext_comm->nb_exclusions;
+                               event_extended->exclusions.strings =
+                                               listing.data + listing.size;
+
+                               ret = lttng_dynamic_buffer_append(&listing,
+                                               comm_ext_at,
+                                               ext_comm->nb_exclusions *
+                                                               LTTNG_SYMBOL_NAME_LEN);
+                               if (ret) {
+                                       ret = -LTTNG_ERR_NOMEM;
+                                       goto free_dynamic_buffer;
+                               }
+                               comm_ext_at += ext_comm->nb_exclusions *
+                                               LTTNG_SYMBOL_NAME_LEN;
+                       }
+
+                       /* Insert padding to align to 64-bits. */
+                       ret = lttng_dynamic_buffer_set_size(&listing,
+                                       ALIGN_TO(listing.size,
+                                                       sizeof(uint64_t)));
+                       if (ret) {
+                               ret = -LTTNG_ERR_NOMEM;
+                               goto free_dynamic_buffer;
+                       }
+
+                       /* Insert flattened userspace probe location. */
+                       if (ext_comm->userspace_probe_location_len) {
+                               struct lttng_userspace_probe_location
+                                               *probe_location = NULL;
+                               struct lttng_payload_view probe_location_view = lttng_payload_view_from_view(
+                                               &payload_copy_view,
+                                               (const char *) comm_ext_at -
+                                                               payload_copy_view.buffer.data,
+                                               ext_comm->userspace_probe_location_len);
+
+                               if (!lttng_payload_view_is_valid(&probe_location_view)) {
+                                       ret = -LTTNG_ERR_PROBE_LOCATION_INVAL;
+                                       goto free_dynamic_buffer;
+                               }
+
+                               ret = lttng_userspace_probe_location_create_from_payload(
+                                               &probe_location_view,
+                                               &probe_location);
+                               if (ret < 0) {
+                                       ret = -LTTNG_ERR_PROBE_LOCATION_INVAL;
+                                       goto free_dynamic_buffer;
+                               }
+
+                               event_extended->probe_location = (struct lttng_userspace_probe_location
+                                                               *) (listing.data +
+                                               listing.size);
+                               ret = lttng_userspace_probe_location_flatten(
+                                               probe_location, &listing);
+                               lttng_userspace_probe_location_destroy(
+                                               probe_location);
+                               if (ret < 0) {
+                                       ret = -LTTNG_ERR_PROBE_LOCATION_INVAL;
+                                       goto free_dynamic_buffer;
+                               }
+
+                               comm_ext_at += ext_comm->userspace_probe_location_len;
+                       }
+               }
+       }
+
+       /* Don't reset listing buffer as we return its content. */
+       *events = (struct lttng_event *) listing.data;
+       lttng_dynamic_buffer_init(&listing);
+       ret = (int) nb_events;
+free_dynamic_buffer:
+       lttng_dynamic_buffer_reset(&listing);
+end:
+       lttng_payload_reset(&payload);
+       lttng_payload_reset(&payload_copy);
+       return ret;
 }
 
 /*
@@ -1564,77 +2518,237 @@ int lttng_set_tracing_group(const char *name)
        return 0;
 }
 
-/*
- * Returns size of returned session payload data or a negative error code.
- */
 int lttng_calibrate(struct lttng_handle *handle,
                struct lttng_calibrate *calibrate)
 {
-       struct lttcomm_session_msg lsm;
+       /*
+        * This command was removed in LTTng 2.9.
+        */
+       return -LTTNG_ERR_UND;
+}
 
-       /* Safety check. NULL pointer are forbidden */
-       if (handle == NULL || calibrate == NULL) {
-               return -LTTNG_ERR_INVALID;
+/*
+ * Set default channel attributes.
+ * If either or both of the arguments are null, attr content is zeroe'd.
+ */
+void lttng_channel_set_default_attr(struct lttng_domain *domain,
+               struct lttng_channel_attr *attr)
+{
+       struct lttng_channel_extended *extended;
+
+       /* Safety check */
+       if (attr == NULL || domain == NULL) {
+               return;
        }
 
-       memset(&lsm, 0, sizeof(lsm));
-       lsm.cmd_type = LTTNG_CALIBRATE;
-       lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
+       extended = (struct lttng_channel_extended *) attr->extended.ptr;
+       memset(attr, 0, sizeof(struct lttng_channel_attr));
+
+       /* Same for all domains. */
+       attr->overwrite = DEFAULT_CHANNEL_OVERWRITE;
+       attr->tracefile_size = DEFAULT_CHANNEL_TRACEFILE_SIZE;
+       attr->tracefile_count = DEFAULT_CHANNEL_TRACEFILE_COUNT;
 
-       memcpy(&lsm.u.calibrate, calibrate, sizeof(lsm.u.calibrate));
+       switch (domain->type) {
+       case LTTNG_DOMAIN_KERNEL:
+               attr->switch_timer_interval =
+                               DEFAULT_KERNEL_CHANNEL_SWITCH_TIMER;
+               attr->read_timer_interval = DEFAULT_KERNEL_CHANNEL_READ_TIMER;
+               attr->subbuf_size = default_get_kernel_channel_subbuf_size();
+               attr->num_subbuf = DEFAULT_KERNEL_CHANNEL_SUBBUF_NUM;
+               attr->output = DEFAULT_KERNEL_CHANNEL_OUTPUT;
+               if (extended) {
+                       extended->monitor_timer_interval =
+                                       DEFAULT_KERNEL_CHANNEL_MONITOR_TIMER;
+                       extended->blocking_timeout =
+                                       DEFAULT_KERNEL_CHANNEL_BLOCKING_TIMEOUT;
+               }
+               break;
+       case LTTNG_DOMAIN_UST:
+               switch (domain->buf_type) {
+               case LTTNG_BUFFER_PER_UID:
+                       attr->subbuf_size = default_get_ust_uid_channel_subbuf_size();
+                       attr->num_subbuf = DEFAULT_UST_UID_CHANNEL_SUBBUF_NUM;
+                       attr->output = DEFAULT_UST_UID_CHANNEL_OUTPUT;
+                       attr->switch_timer_interval =
+                                       DEFAULT_UST_UID_CHANNEL_SWITCH_TIMER;
+                       attr->read_timer_interval =
+                                       DEFAULT_UST_UID_CHANNEL_READ_TIMER;
+                       if (extended) {
+                               extended->monitor_timer_interval =
+                                               DEFAULT_UST_UID_CHANNEL_MONITOR_TIMER;
+                               extended->blocking_timeout =
+                                               DEFAULT_UST_UID_CHANNEL_BLOCKING_TIMEOUT;
+                       }
+                       break;
+               case LTTNG_BUFFER_PER_PID:
+               default:
+                       attr->subbuf_size = default_get_ust_pid_channel_subbuf_size();
+                       attr->num_subbuf = DEFAULT_UST_PID_CHANNEL_SUBBUF_NUM;
+                       attr->output = DEFAULT_UST_PID_CHANNEL_OUTPUT;
+                       attr->switch_timer_interval =
+                                       DEFAULT_UST_PID_CHANNEL_SWITCH_TIMER;
+                       attr->read_timer_interval =
+                                       DEFAULT_UST_PID_CHANNEL_READ_TIMER;
+                       if (extended) {
+                               extended->monitor_timer_interval =
+                                               DEFAULT_UST_PID_CHANNEL_MONITOR_TIMER;
+                               extended->blocking_timeout =
+                                               DEFAULT_UST_PID_CHANNEL_BLOCKING_TIMEOUT;
+                       }
+                       break;
+               }
+       default:
+               /* Default behavior: leave set to 0. */
+               break;
+       }
+
+       attr->extended.ptr = extended;
+}
+
+int lttng_channel_get_discarded_event_count(struct lttng_channel *channel,
+               uint64_t *discarded_events)
+{
+       int ret = 0;
+       struct lttng_channel_extended *chan_ext;
+
+       if (!channel || !discarded_events) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
+
+       chan_ext = channel->attr.extended.ptr;
+       if (!chan_ext) {
+               /*
+                * This can happen since the lttng_channel structure is
+                * used for other tasks where this pointer is never set.
+                */
+               *discarded_events = 0;
+               goto end;
+       }
+
+       *discarded_events = chan_ext->discarded_events;
+end:
+       return ret;
+}
+
+int lttng_channel_get_lost_packet_count(struct lttng_channel *channel,
+               uint64_t *lost_packets)
+{
+       int ret = 0;
+       struct lttng_channel_extended *chan_ext;
+
+       if (!channel || !lost_packets) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
+
+       chan_ext = channel->attr.extended.ptr;
+       if (!chan_ext) {
+               /*
+                * This can happen since the lttng_channel structure is
+                * used for other tasks where this pointer is never set.
+                */
+               *lost_packets = 0;
+               goto end;
+       }
+
+       *lost_packets = chan_ext->lost_packets;
+end:
+       return ret;
+}
+
+int lttng_channel_get_monitor_timer_interval(struct lttng_channel *chan,
+               uint64_t *monitor_timer_interval)
+{
+       int ret = 0;
+
+       if (!chan || !monitor_timer_interval) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
+
+       if (!chan->attr.extended.ptr) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
+
+       *monitor_timer_interval = ((struct lttng_channel_extended *)
+                       chan->attr.extended.ptr)->monitor_timer_interval;
+end:
+       return ret;
+}
+
+int lttng_channel_set_monitor_timer_interval(struct lttng_channel *chan,
+               uint64_t monitor_timer_interval)
+{
+       int ret = 0;
+
+       if (!chan || !chan->attr.extended.ptr) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
+
+       ((struct lttng_channel_extended *)
+                       chan->attr.extended.ptr)->monitor_timer_interval =
+                       monitor_timer_interval;
+end:
+       return ret;
+}
+
+int lttng_channel_get_blocking_timeout(struct lttng_channel *chan,
+               int64_t *blocking_timeout)
+{
+       int ret = 0;
+
+       if (!chan || !blocking_timeout) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
+
+       if (!chan->attr.extended.ptr) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
 
-       return lttng_ctl_ask_sessiond(&lsm, NULL);
+       *blocking_timeout = ((struct lttng_channel_extended *)
+                       chan->attr.extended.ptr)->blocking_timeout;
+end:
+       return ret;
 }
 
-/*
- * Set default channel attributes.
- * If either or both of the arguments are null, attr content is zeroe'd.
- */
-void lttng_channel_set_default_attr(struct lttng_domain *domain,
-               struct lttng_channel_attr *attr)
+int lttng_channel_set_blocking_timeout(struct lttng_channel *chan,
+               int64_t blocking_timeout)
 {
-       /* Safety check */
-       if (attr == NULL || domain == NULL) {
-               return;
-       }
+       int ret = 0;
+       int64_t msec_timeout;
 
-       memset(attr, 0, sizeof(struct lttng_channel_attr));
+       if (!chan || !chan->attr.extended.ptr) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
 
-       /* Same for all domains. */
-       attr->overwrite = DEFAULT_CHANNEL_OVERWRITE;
-       attr->tracefile_size = DEFAULT_CHANNEL_TRACEFILE_SIZE;
-       attr->tracefile_count = DEFAULT_CHANNEL_TRACEFILE_COUNT;
+       if (blocking_timeout < 0 && blocking_timeout != -1) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
 
-       switch (domain->type) {
-       case LTTNG_DOMAIN_KERNEL:
-               attr->switch_timer_interval = DEFAULT_KERNEL_CHANNEL_SWITCH_TIMER;
-               attr->read_timer_interval = DEFAULT_KERNEL_CHANNEL_READ_TIMER;
-               attr->subbuf_size = default_get_kernel_channel_subbuf_size();
-               attr->num_subbuf = DEFAULT_KERNEL_CHANNEL_SUBBUF_NUM;
-               attr->output = DEFAULT_KERNEL_CHANNEL_OUTPUT;
-               break;
-       case LTTNG_DOMAIN_UST:
-               switch (domain->buf_type) {
-               case LTTNG_BUFFER_PER_UID:
-                       attr->subbuf_size = default_get_ust_uid_channel_subbuf_size();
-                       attr->num_subbuf = DEFAULT_UST_UID_CHANNEL_SUBBUF_NUM;
-                       attr->output = DEFAULT_UST_UID_CHANNEL_OUTPUT;
-                       attr->switch_timer_interval = DEFAULT_UST_UID_CHANNEL_SWITCH_TIMER;
-                       attr->read_timer_interval = DEFAULT_UST_UID_CHANNEL_READ_TIMER;
-                       break;
-               case LTTNG_BUFFER_PER_PID:
-               default:
-                       attr->subbuf_size = default_get_ust_pid_channel_subbuf_size();
-                       attr->num_subbuf = DEFAULT_UST_PID_CHANNEL_SUBBUF_NUM;
-                       attr->output = DEFAULT_UST_PID_CHANNEL_OUTPUT;
-                       attr->switch_timer_interval = DEFAULT_UST_PID_CHANNEL_SWITCH_TIMER;
-                       attr->read_timer_interval = DEFAULT_UST_PID_CHANNEL_READ_TIMER;
-                       break;
-               }
-       default:
-               /* Default behavior: leave set to 0. */
-               break;
+       /*
+        * LTTng-ust's use of poll() to implement this timeout mechanism forces
+        * us to accept a narrower range of values (msecs expressed as a signed
+        * 32-bit integer).
+        */
+       msec_timeout = blocking_timeout / 1000;
+       if (msec_timeout != (int32_t) msec_timeout) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
        }
+
+       ((struct lttng_channel_extended *)
+                       chan->attr.extended.ptr)->blocking_timeout =
+                       blocking_timeout;
+end:
+       return ret;
 }
 
 /*
@@ -1649,25 +2763,25 @@ int lttng_session_daemon_alive(void)
 
        ret = set_session_daemon_path();
        if (ret < 0) {
-               /* Error */
+               /* Error. */
                return ret;
        }
 
        if (*sessiond_sock_path == '\0') {
                /*
-                * No socket path set. Weird error which means the constructor was not
-                * called.
+                * No socket path set. Weird error which means the constructor
+                * was not called.
                 */
                assert(0);
        }
 
        ret = try_connect_sessiond(sessiond_sock_path);
        if (ret < 0) {
-               /* Not alive */
+               /* Not alive. */
                return 0;
        }
 
-       /* Is alive */
+       /* Is alive. */
        return 1;
 }
 
@@ -1694,7 +2808,7 @@ int lttng_set_consumer_url(struct lttng_handle *handle,
 
        lttng_ctl_copy_string(lsm.session.name, handle->session_name,
                        sizeof(lsm.session.name));
-       lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
+       COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
 
        size = uri_parse_str_urls(control_url, data_url, &uris);
        if (size < 0) {
@@ -1703,7 +2817,7 @@ int lttng_set_consumer_url(struct lttng_handle *handle,
 
        lsm.u.uri.size = size;
 
-       ret = lttng_ctl_ask_sessiond_varlen(&lsm, uris,
+       ret = lttng_ctl_ask_sessiond_varlen_no_cmd_header(&lsm, uris,
                        sizeof(struct lttng_uri) * size, NULL);
 
        free(uris);
@@ -1713,6 +2827,7 @@ int lttng_set_consumer_url(struct lttng_handle *handle,
 /*
  * [OBSOLETE]
  */
+int lttng_enable_consumer(struct lttng_handle *handle);
 int lttng_enable_consumer(struct lttng_handle *handle)
 {
        return -ENOSYS;
@@ -1721,211 +2836,408 @@ int lttng_enable_consumer(struct lttng_handle *handle)
 /*
  * [OBSOLETE]
  */
+int lttng_disable_consumer(struct lttng_handle *handle);
 int lttng_disable_consumer(struct lttng_handle *handle)
 {
        return -ENOSYS;
 }
 
 /*
- * This is an extension of create session that is ONLY and SHOULD only be used
- * by the lttng command line program. It exists to avoid using URI parsing in
- * the lttng client.
- *
- * We need the date and time for the trace path subdirectory for the case where
- * the user does NOT define one using either -o or -U. Using the normal
- * lttng_create_session API call, we have no clue on the session daemon side if
- * the URL was generated automatically by the client or define by the user.
- *
- * So this function "wrapper" is hidden from the public API, takes the datetime
- * string and appends it if necessary to the URI subdirectory before sending it
- * to the session daemon.
- *
- * With this extra function, the lttng_create_session call behavior is not
- * changed and the timestamp is appended to the URI on the session daemon side
- * if necessary.
+ * [OBSOLETE]
  */
+int _lttng_create_session_ext(const char *name, const char *url,
+               const char *datetime);
 int _lttng_create_session_ext(const char *name, const char *url,
                const char *datetime)
+{
+       return -ENOSYS;
+}
+
+/*
+ * For a given session name, this call checks if the data is ready to be read
+ * or is still being extracted by the consumer(s) hence not ready to be used by
+ * any readers.
+ */
+int lttng_data_pending(const char *session_name)
 {
        int ret;
-       ssize_t size;
        struct lttcomm_session_msg lsm;
-       struct lttng_uri *uris = NULL;
+       uint8_t *pending = NULL;
 
-       if (name == NULL || datetime == NULL) {
+       if (session_name == NULL) {
                return -LTTNG_ERR_INVALID;
        }
 
        memset(&lsm, 0, sizeof(lsm));
+       lsm.cmd_type = LTTNG_DATA_PENDING;
 
-       lsm.cmd_type = LTTNG_CREATE_SESSION;
-       lttng_ctl_copy_string(lsm.session.name, name, sizeof(lsm.session.name));
+       lttng_ctl_copy_string(lsm.session.name, session_name,
+                       sizeof(lsm.session.name));
 
-       /* There should never be a data URL */
-       size = uri_parse_str_urls(url, NULL, &uris);
-       if (size < 0) {
+       ret = lttng_ctl_ask_sessiond(&lsm, (void **) &pending);
+       if (ret < 0) {
+               goto end;
+       } else if (ret != 1) {
+               /* Unexpected payload size */
                ret = -LTTNG_ERR_INVALID;
-               goto error;
+               goto end;
+       } else if (!pending) {
+               /* Internal error. */
+               ret = -LTTNG_ERR_UNK;
+               goto end;
        }
 
-       lsm.u.uri.size = size;
+       ret = (int) *pending;
+end:
+       free(pending);
+       return ret;
+}
 
-       if (size > 0 && uris[0].dtype != LTTNG_DST_PATH && strlen(uris[0].subdir) == 0) {
-               /* Don't append datetime if the name was automatically created. */
-               if (strncmp(name, DEFAULT_SESSION_NAME "-",
-                                       strlen(DEFAULT_SESSION_NAME) + 1)) {
-                       ret = snprintf(uris[0].subdir, sizeof(uris[0].subdir), "%s-%s",
-                                       name, datetime);
-               } else {
-                       ret = snprintf(uris[0].subdir, sizeof(uris[0].subdir), "%s", name);
-               }
-               if (ret < 0) {
-                       PERROR("snprintf uri subdir");
-                       ret = -LTTNG_ERR_FATAL;
-                       goto error;
-               }
+/*
+ * Regenerate the metadata for a session.
+ * Return 0 on success, a negative error code on error.
+ */
+int lttng_regenerate_metadata(const char *session_name)
+{
+       int ret;
+       struct lttcomm_session_msg lsm;
+
+       if (!session_name) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
        }
 
-       ret = lttng_ctl_ask_sessiond_varlen(&lsm, uris,
-                       sizeof(struct lttng_uri) * size, NULL);
+       memset(&lsm, 0, sizeof(lsm));
+       lsm.cmd_type = LTTNG_REGENERATE_METADATA;
 
-error:
-       free(uris);
+       lttng_ctl_copy_string(lsm.session.name, session_name,
+                       sizeof(lsm.session.name));
+
+       ret = lttng_ctl_ask_sessiond(&lsm, NULL);
+       if (ret < 0) {
+               goto end;
+       }
+
+       ret = 0;
+end:
        return ret;
 }
 
 /*
- * For a given session name, this call checks if the data is ready to be read
- * or is still being extracted by the consumer(s) hence not ready to be used by
- * any readers.
+ * Deprecated, replaced by lttng_regenerate_metadata.
  */
-int lttng_data_pending(const char *session_name)
+int lttng_metadata_regenerate(const char *session_name)
+{
+       return lttng_regenerate_metadata(session_name);
+}
+
+/*
+ * Regenerate the statedump of a session.
+ * Return 0 on success, a negative error code on error.
+ */
+int lttng_regenerate_statedump(const char *session_name)
 {
        int ret;
        struct lttcomm_session_msg lsm;
 
-       if (session_name == NULL) {
-               return -LTTNG_ERR_INVALID;
+       if (!session_name) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
        }
 
        memset(&lsm, 0, sizeof(lsm));
-       lsm.cmd_type = LTTNG_DATA_PENDING;
+       lsm.cmd_type = LTTNG_REGENERATE_STATEDUMP;
 
        lttng_ctl_copy_string(lsm.session.name, session_name,
                        sizeof(lsm.session.name));
 
        ret = lttng_ctl_ask_sessiond(&lsm, NULL);
+       if (ret < 0) {
+               goto end;
+       }
+
+       ret = 0;
+end:
+       return ret;
+}
+
+int lttng_register_trigger(struct lttng_trigger *trigger)
+{
+       int ret;
+       struct lttcomm_session_msg lsm = {
+               .cmd_type = LTTNG_REGISTER_TRIGGER,
+       };
+       struct lttcomm_session_msg *message_lsm;
+       struct lttng_payload message;
+       struct lttng_payload reply;
+       struct lttng_trigger *reply_trigger = NULL;
+       enum lttng_domain_type domain_type;
+       const struct lttng_credentials user_creds = {
+               .uid = LTTNG_OPTIONAL_INIT_VALUE(geteuid()),
+               .gid = LTTNG_OPTIONAL_INIT_UNSET,
+       };
+
+
+       lttng_payload_init(&message);
+       lttng_payload_init(&reply);
+
+       if (!trigger) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
+
+       if (!trigger->creds.uid.is_set) {
+               /* Use the client's credentials as the trigger credentials. */
+               lttng_trigger_set_credentials(trigger, &user_creds);
+       } else {
+               /*
+                * Validate that either the current trigger credentials and the
+                * client credentials are identical or that the current user is
+                * root. The root user can register, unregister triggers for
+                * himself and other users.
+                *
+                * This check is also present on the sessiond side, using the
+                * credentials passed on the socket. These check are all
+                * "safety" checks.
+                */
+               const struct lttng_credentials *trigger_creds =
+                               lttng_trigger_get_credentials(trigger);
+
+               if (!lttng_credentials_is_equal_uid(trigger_creds, &user_creds)) {
+                       if (lttng_credentials_get_uid(&user_creds) != 0) {
+                               ret = -LTTNG_ERR_EPERM;
+                               goto end;
+                       }
+               }
+       }
+
+       if (!lttng_trigger_validate(trigger)) {
+               ret = -LTTNG_ERR_INVALID_TRIGGER;
+               goto end;
+       }
+
+       domain_type = lttng_trigger_get_underlying_domain_type_restriction(
+                       trigger);
+
+       lsm.domain.type = domain_type;
+
+       ret = lttng_dynamic_buffer_append(&message.buffer, &lsm, sizeof(lsm));
+       if (ret) {
+               ret = -LTTNG_ERR_NOMEM;
+               goto end;
+       }
 
        /*
-        * The lttng_ctl_ask_sessiond function negate the return code if it's not
-        * LTTNG_OK so getting -1 means that the reply ret_code was 1 thus meaning
-        * that the data is available. Yes it is hackish but for now this is the
-        * only way.
-        */
-       if (ret == -1) {
-               ret = 1;
+        * This is needed to populate the trigger object size for the command
+        * header.
+       */
+       message_lsm = (struct lttcomm_session_msg *) message.buffer.data;
+
+       ret = lttng_trigger_serialize(trigger, &message);
+       if (ret < 0) {
+               ret = -LTTNG_ERR_UNK;
+               goto end;
+       }
+
+       message_lsm->u.trigger.length = (uint32_t) message.buffer.size - sizeof(lsm);
+
+       {
+               struct lttng_payload_view message_view =
+                               lttng_payload_view_from_payload(
+                                               &message, 0, -1);
+
+               message_lsm->fd_count = lttng_payload_view_get_fd_handle_count(
+                               &message_view);
+               ret = lttng_ctl_ask_sessiond_payload(&message_view, &reply);
+               if (ret < 0) {
+                       goto end;
+               }
+       }
+
+       {
+               struct lttng_payload_view reply_view =
+                               lttng_payload_view_from_payload(
+                                               &reply, 0, reply.buffer.size);
+
+               ret = lttng_trigger_create_from_payload(
+                               &reply_view, &reply_trigger);
+               if (ret < 0) {
+                       ret = -LTTNG_ERR_FATAL;
+                       goto end;
+               }
+       }
+
+       ret = lttng_trigger_assign_name(trigger, reply_trigger);
+       if (ret < 0) {
+               ret = -LTTNG_ERR_FATAL;
+               goto end;
        }
 
+       ret = 0;
+end:
+       lttng_payload_reset(&message);
+       lttng_payload_reset(&reply);
+       lttng_trigger_destroy(reply_trigger);
        return ret;
 }
 
-/*
- * Create a session exclusively used for snapshot.
- *
- * Returns LTTNG_OK on success or a negative error code.
- */
-int lttng_create_session_snapshot(const char *name, const char *snapshot_url)
+int lttng_unregister_trigger(struct lttng_trigger *trigger)
 {
        int ret;
-       ssize_t size;
        struct lttcomm_session_msg lsm;
-       struct lttng_uri *uris = NULL;
+       struct lttcomm_session_msg *message_lsm;
+       struct lttng_payload message;
+       struct lttng_payload reply;
+       const struct lttng_credentials user_creds = {
+               .uid = LTTNG_OPTIONAL_INIT_VALUE(geteuid()),
+               .gid = LTTNG_OPTIONAL_INIT_UNSET,
+       };
+
+       lttng_payload_init(&message);
+       lttng_payload_init(&reply);
+
+       if (!trigger) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
 
-       if (name == NULL) {
-               return -LTTNG_ERR_INVALID;
+       if (!trigger->creds.uid.is_set) {
+               /* Use the client's credentials as the trigger credentials. */
+               lttng_trigger_set_credentials(trigger, &user_creds);
+       } else {
+               /*
+                * Validate that either the current trigger credentials and the
+                * client credentials are identical or that the current user is
+                * root. The root user can register, unregister triggers for
+                * himself and other users.
+                *
+                * This check is also present on the sessiond side, using the
+                * credentials passed on the socket. These check are all
+                * "safety" checks.
+                */
+               const struct lttng_credentials *trigger_creds =
+                               lttng_trigger_get_credentials(trigger);
+
+               if (!lttng_credentials_is_equal_uid(trigger_creds, &user_creds)) {
+                       if (lttng_credentials_get_uid(&user_creds) != 0) {
+                               ret = -LTTNG_ERR_EPERM;
+                               goto end;
+                       }
+               }
+       }
+
+       if (!lttng_trigger_validate(trigger)) {
+               ret = -LTTNG_ERR_INVALID_TRIGGER;
+               goto end;
        }
 
        memset(&lsm, 0, sizeof(lsm));
+       lsm.cmd_type = LTTNG_UNREGISTER_TRIGGER;
 
-       lsm.cmd_type = LTTNG_CREATE_SESSION_SNAPSHOT;
-       lttng_ctl_copy_string(lsm.session.name, name, sizeof(lsm.session.name));
+       ret = lttng_dynamic_buffer_append(&message.buffer, &lsm, sizeof(lsm));
+       if (ret) {
+               ret = -LTTNG_ERR_NOMEM;
+               goto end;
+       }
 
-       size = uri_parse_str_urls(snapshot_url, NULL, &uris);
-       if (size < 0) {
-               return -LTTNG_ERR_INVALID;
+       /*
+        * This is needed to populate the trigger object size for the command
+        * header and number of fds sent.
+       */
+       message_lsm = (struct lttcomm_session_msg *) message.buffer.data;
+
+       ret = lttng_trigger_serialize(trigger, &message);
+       if (ret < 0) {
+               ret = -LTTNG_ERR_UNK;
+               goto end;
        }
 
-       lsm.u.uri.size = size;
+       message_lsm->u.trigger.length = (uint32_t) message.buffer.size - sizeof(lsm);
 
-       ret = lttng_ctl_ask_sessiond_varlen(&lsm, uris,
-                       sizeof(struct lttng_uri) * size, NULL);
+       {
+               struct lttng_payload_view message_view =
+                               lttng_payload_view_from_payload(
+                                               &message, 0, -1);
 
-       free(uris);
+               /*
+                * Update the message header with the number of fd that will be
+                * sent.
+                */
+               message_lsm->fd_count = lttng_payload_view_get_fd_handle_count(
+                               &message_view);
+
+               ret = lttng_ctl_ask_sessiond_payload(&message_view, &reply);
+               if (ret < 0) {
+                       goto end;
+               }
+       }
+
+       ret = 0;
+end:
+       lttng_payload_reset(&message);
+       lttng_payload_reset(&reply);
        return ret;
 }
 
 /*
- * Create a session exclusively used for live.
+ * Ask the session daemon for all registered triggers for the current user.
  *
- * Returns LTTNG_OK on success or a negative error code.
+ * Allocates and return an lttng_triggers set.
+ * On error, returns a suitable lttng_error_code.
  */
-int lttng_create_session_live(const char *name, const char *url,
-               unsigned int timer_interval)
+enum lttng_error_code lttng_list_triggers(struct lttng_triggers **triggers)
 {
        int ret;
-       ssize_t size;
-       struct lttcomm_session_msg lsm;
-       struct lttng_uri *uris = NULL;
-
-       if (name == NULL) {
-               return -LTTNG_ERR_INVALID;
-       }
+       enum lttng_error_code ret_code = LTTNG_OK;
+       struct lttcomm_session_msg lsm = { .cmd_type = LTTNG_LIST_TRIGGERS };
+       struct lttng_triggers *local_triggers = NULL;
+       struct lttng_payload reply;
+       struct lttng_payload_view lsm_view =
+                       lttng_payload_view_init_from_buffer(
+                               (const char *) &lsm, 0, sizeof(lsm));
 
-       memset(&lsm, 0, sizeof(lsm));
+       lttng_payload_init(&reply);
 
-       lsm.cmd_type = LTTNG_CREATE_SESSION_LIVE;
-       lttng_ctl_copy_string(lsm.session.name, name, sizeof(lsm.session.name));
+       ret = lttng_ctl_ask_sessiond_payload(&lsm_view, &reply);
+       if (ret < 0) {
+               ret_code = (enum lttng_error_code) -ret;
+               goto end;
+       }
 
-       if (url) {
-               size = uri_parse_str_urls(url, NULL, &uris);
-               if (size <= 0) {
-                       ret = -LTTNG_ERR_INVALID;
-                       goto end;
-               }
+       {
+               struct lttng_payload_view reply_view =
+                               lttng_payload_view_from_payload(
+                                               &reply, 0, reply.buffer.size);
 
-               /* file:// is not accepted for live session. */
-               if (uris[0].dtype == LTTNG_DST_PATH) {
-                       ret = -LTTNG_ERR_INVALID;
+               ret = lttng_triggers_create_from_payload(
+                               &reply_view, &local_triggers);
+               if (ret < 0) {
+                       ret_code = LTTNG_ERR_FATAL;
                        goto end;
                }
-       } else {
-               size = 0;
        }
 
-       lsm.u.session_live.nb_uri = size;
-       lsm.u.session_live.timer_interval = timer_interval;
-
-       ret = lttng_ctl_ask_sessiond_varlen(&lsm, uris,
-                       sizeof(struct lttng_uri) * size, NULL);
-
+       *triggers = local_triggers;
+       local_triggers = NULL;
 end:
-       free(uris);
-       return ret;
+       lttng_payload_reset(&reply);
+       lttng_triggers_destroy(local_triggers);
+       return ret_code;
 }
 
 /*
- * lib constructor
+ * lib constructor.
  */
-static void __attribute__((constructor)) init()
+static void __attribute__((constructor)) init(void)
 {
        /* Set default session group */
        lttng_set_tracing_group(DEFAULT_TRACING_GROUP);
 }
 
 /*
- * lib destructor
+ * lib destructor.
  */
-static void __attribute__((destructor)) lttng_ctl_exit()
+static void __attribute__((destructor)) lttng_ctl_exit(void)
 {
        free(tracing_group);
 }
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