Fix: liblttng-ctl: leak of payload on field listing
[lttng-tools.git] / src / lib / lttng-ctl / lttng-ctl.c
index 02b3fed4cd3a76a7ff5d828fbabed8723ca38750..be397918f477512325c276fbbe8eca3749898cb1 100644 (file)
@@ -1,65 +1,66 @@
 /*
- * 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>
+ * Copyright (C) 2011 EfficiOS Inc.
+ * 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 _LGPL_SOURCE
 #include <assert.h>
 #include <grp.h>
-#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <stdint.h>
 #include <string.h>
 #include <unistd.h>
 
+#include <common/bytecode/bytecode.h>
 #include <common/common.h>
+#include <common/compat/errno.h>
+#include <common/compat/string.h>
 #include <common/defaults.h>
+#include <common/dynamic-array.h>
+#include <common/dynamic-buffer.h>
+#include <common/payload-view.h>
+#include <common/payload.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/error-query-internal.h>
+#include <lttng/event-internal.h>
 #include <lttng/health-internal.h>
+#include <lttng/lttng-error.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 "filter/filter-ast.h"
-#include "filter/filter-parser.h"
-#include "filter/filter-bytecode.h"
-#include "filter/memstream.h"
 #include "lttng-ctl-helper.h"
+#include <common/filter/filter-ast.h>
+#include <common/filter/filter-parser.h>
+#include <common/filter/memstream.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 */
@@ -77,21 +78,6 @@ int lttng_opt_quiet;
 int lttng_opt_verbose;
 int lttng_opt_mi;
 
-/*
- * Copy string from src to dst and enforce null terminated byte.
- */
-LTTNG_HIDDEN
-void lttng_ctl_copy_string(char *dst, const char *src, size_t len)
-{
-       if (src && dst) {
-               strncpy(dst, src, len);
-               /* Enforce the NULL terminated byte */
-               dst[len - 1] = '\0';
-       } else if (dst) {
-               dst[0] = '\0';
-       }
-}
-
 /*
  * Copy domain to lttcomm_session_msg domain.
  *
@@ -132,7 +118,8 @@ static int send_session_msg(struct lttcomm_session_msg *lsm)
                goto end;
        }
 
-       DBG("LSM cmd type : %d", lsm->cmd_type);
+       DBG("LSM cmd type: '%s' (%d)", lttcomm_sessiond_command_str(lsm->cmd_type),
+                       lsm->cmd_type);
 
        ret = lttcomm_send_creds_unix_sock(sessiond_socket, lsm,
                        sizeof(struct lttcomm_session_msg));
@@ -173,16 +160,47 @@ 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;
@@ -191,8 +209,34 @@ 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:
+       return ret;
+}
+
+/*
+ * 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;
 }
@@ -205,15 +249,13 @@ end:
 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;
        }
@@ -238,7 +280,7 @@ int lttng_check_tracing_group(void)
        }
 
        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 +293,68 @@ end:
        return ret;
 }
 
+static enum lttng_error_code check_enough_available_memory(
+               uint64_t num_bytes_requested_per_cpu)
+{
+       int ret;
+       enum lttng_error_code ret_code;
+       long num_cpu;
+       uint64_t best_mem_info;
+       uint64_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) {
+               ret_code = LTTNG_ERR_FATAL;
+               goto end;
+       }
+
+       if (num_bytes_requested_per_cpu > UINT64_MAX / (uint64_t) num_cpu) {
+               /* Overflow */
+               ret_code = LTTNG_ERR_OVERFLOW;
+               goto end;
+       }
+
+       num_bytes_requested_total =
+                       num_bytes_requested_per_cpu * (uint64_t) 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;
+       }
+
+       /* No valid source of information. */
+       ret_code = LTTNG_ERR_NOMEM;
+       goto end;
+
+success:
+       if (best_mem_info >= num_bytes_requested_total) {
+               ret_code = LTTNG_OK;
+       } else {
+               ret_code = LTTNG_ERR_NOMEM;
+       }
+end:
+       return ret_code;
+}
+
 /*
  * Try connect to session daemon with sock_path.
  *
@@ -303,9 +407,14 @@ static int set_session_daemon_path(void)
                in_tgroup = lttng_check_tracing_group();
        }
 
-       if ((uid == 0) || in_tgroup) {
-               lttng_ctl_copy_string(sessiond_sock_path,
-                               DEFAULT_GLOBAL_CLIENT_UNIX_SOCK, sizeof(sessiond_sock_path));
+       if ((uid == 0) || in_tgroup == 1) {
+               const int ret = lttng_strncpy(sessiond_sock_path,
+                               DEFAULT_GLOBAL_CLIENT_UNIX_SOCK,
+                               sizeof(sessiond_sock_path));
+
+               if (ret) {
+                       goto error;
+               }
        }
 
        if (uid != 0) {
@@ -343,17 +452,12 @@ error:
 /*
  * 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;
@@ -365,15 +469,18 @@ static int connect_sessiond(void)
                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.
  *
@@ -385,8 +492,7 @@ 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;
@@ -442,15 +548,16 @@ end:
 
 /*
  * 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,
-               const void *vardata, size_t vardata_len,
-               void **user_payload_buf, void **user_cmd_header_buf,
-               size_t *user_cmd_header_len)
+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 payload_len;
@@ -460,9 +567,11 @@ int lttng_ctl_ask_sessiond_varlen(struct lttcomm_session_msg *lsm,
        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. */
@@ -475,6 +584,13 @@ int lttng_ctl_ask_sessiond_varlen(struct lttcomm_session_msg *lsm,
                goto end;
        }
 
+       /* Send fds */
+       ret = send_session_fds(fds, nb_fd);
+       if (ret < 0) {
+               /* Ret value is a valid lttng error code. */
+               goto end;
+       }
+
        /* Get header from data transmission */
        ret = recv_data_sessiond(&llm, sizeof(llm));
        if (ret < 0) {
@@ -509,6 +625,103 @@ end:
        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;
+       }
+
+       /* 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;
+       }
+
+       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) {
+               /* Ret value is a valid lttng error code. */
+               goto end;
+       }
+
+       llm = *((typeof(llm) *) reply->buffer.data);
+
+       /* Check error code if OK */
+       if (llm.ret_code != LTTNG_OK) {
+               if (llm.ret_code < LTTNG_OK || llm.ret_code >= LTTNG_ERR_NR) {
+                       /* Invalid error code received. */
+                       ret = -LTTNG_ERR_UNK;
+               } else {
+                       ret = -llm.ret_code;
+               }
+               goto end;
+       }
+
+       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();
+       return ret;
+}
+
 /*
  * Create lttng handle and return pointer.
  *
@@ -517,12 +730,9 @@ end:
 struct lttng_handle *lttng_create_handle(const char *session_name,
                struct lttng_domain *domain)
 {
+       int ret;
        struct lttng_handle *handle = NULL;
 
-       if (domain == NULL) {
-               goto end;
-       }
-
        handle = zmalloc(sizeof(struct lttng_handle));
        if (handle == NULL) {
                PERROR("malloc handle");
@@ -530,14 +740,22 @@ struct lttng_handle *lttng_create_handle(const char *session_name,
        }
 
        /* Copy session name */
-       lttng_ctl_copy_string(handle->session_name, session_name,
-                       sizeof(handle->session_name));
+       ret = lttng_strncpy(handle->session_name, session_name ? : "",
+                           sizeof(handle->session_name));
+       if (ret) {
+               goto error;
+       }
 
-       /* 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;
+error:
+       free(handle);
+       return NULL;
 }
 
 /*
@@ -556,22 +774,35 @@ void lttng_destroy_handle(struct lttng_handle *handle)
 int lttng_register_consumer(struct lttng_handle *handle,
                const char *socket_path)
 {
+       int ret;
        struct lttcomm_session_msg lsm;
 
        if (handle == NULL || socket_path == NULL) {
-               return -LTTNG_ERR_INVALID;
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
        }
 
        memset(&lsm, 0, sizeof(lsm));
        lsm.cmd_type = LTTNG_REGISTER_CONSUMER;
-       lttng_ctl_copy_string(lsm.session.name, handle->session_name,
+       ret = lttng_strncpy(lsm.session.name, handle->session_name,
                        sizeof(lsm.session.name));
-       lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
+       if (ret) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
+
+       COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
 
-       lttng_ctl_copy_string(lsm.u.reg.path, socket_path,
-                       sizeof(lsm.u.reg.path));
+       ret = lttng_strncpy(lsm.u.reg.path, socket_path,
+                           sizeof(lsm.u.reg.path));
+       if (ret) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
 
-       return lttng_ctl_ask_sessiond(&lsm, NULL);
+       ret = lttng_ctl_ask_sessiond(&lsm, NULL);
+end:
+       return ret;
 }
 
 /*
@@ -581,19 +812,27 @@ int lttng_register_consumer(struct lttng_handle *handle,
  */
 int lttng_start_tracing(const char *session_name)
 {
+       int ret;
        struct lttcomm_session_msg lsm;
 
        if (session_name == NULL) {
-               return -LTTNG_ERR_INVALID;
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
        }
 
        memset(&lsm, 0, sizeof(lsm));
        lsm.cmd_type = LTTNG_START_TRACE;
 
-       lttng_ctl_copy_string(lsm.session.name, session_name,
-                       sizeof(lsm.session.name));
+       ret = lttng_strncpy(lsm.session.name, session_name,
+                           sizeof(lsm.session.name));
+       if (ret) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
 
-       return lttng_ctl_ask_sessiond(&lsm, NULL);
+       ret = lttng_ctl_ask_sessiond(&lsm, NULL);
+end:
+       return ret;
 }
 
 /*
@@ -605,14 +844,19 @@ static int _lttng_stop_tracing(const char *session_name, int wait)
        struct lttcomm_session_msg lsm;
 
        if (session_name == NULL) {
-               return -LTTNG_ERR_INVALID;
+               ret = -LTTNG_ERR_INVALID;
+               goto error;
        }
 
        memset(&lsm, 0, sizeof(lsm));
        lsm.cmd_type = LTTNG_STOP_TRACE;
 
-       lttng_ctl_copy_string(lsm.session.name, session_name,
-                       sizeof(lsm.session.name));
+       ret = lttng_strncpy(lsm.session.name, session_name,
+                           sizeof(lsm.session.name));
+       if (ret) {
+               ret = -LTTNG_ERR_INVALID;
+               goto error;
+       }
 
        ret = lttng_ctl_ask_sessiond(&lsm, NULL);
        if (ret < 0 && ret != -LTTNG_ERR_TRACE_ALREADY_STOPPED) {
@@ -637,7 +881,7 @@ static int _lttng_stop_tracing(const char *session_name, int wait)
                 * 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);
 
@@ -675,9 +919,10 @@ int lttng_add_context(struct lttng_handle *handle,
                const char *channel_name)
 {
        int ret;
-       size_t len = 0;
-       char *buf = NULL;
-       struct lttcomm_session_msg lsm;
+       struct lttcomm_session_msg lsm = { .cmd_type = LTTNG_ADD_CONTEXT };
+       struct lttng_payload payload;
+
+       lttng_payload_init(&payload);
 
        /* Safety check. Both are mandatory. */
        if (handle == NULL || ctx == NULL) {
@@ -685,64 +930,55 @@ int lttng_add_context(struct lttng_handle *handle,
                goto end;
        }
 
-       memset(&lsm, 0, sizeof(lsm));
-       lsm.cmd_type = LTTNG_ADD_CONTEXT;
+       ret = lttng_dynamic_buffer_set_size(&payload.buffer, sizeof(lsm));
+       if (ret) {
+               ret = -LTTNG_ERR_NOMEM;
+               goto end;
+       }
 
        /* If no channel name, send empty string. */
-       if (channel_name == NULL) {
-               lttng_ctl_copy_string(lsm.u.context.channel_name, "",
-                               sizeof(lsm.u.context.channel_name));
-       } else {
-               lttng_ctl_copy_string(lsm.u.context.channel_name, channel_name,
-                               sizeof(lsm.u.context.channel_name));
+       ret = lttng_strncpy(lsm.u.context.channel_name, channel_name ?: "",
+                       sizeof(lsm.u.context.channel_name));
+       if (ret) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
        }
 
-       lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
-       lttng_ctl_copy_string(lsm.session.name, handle->session_name,
+       COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
+       ret = lttng_strncpy(lsm.session.name, handle->session_name,
                        sizeof(lsm.session.name));
+       if (ret) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
 
-       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;
+       ret = lttng_event_context_serialize(ctx, &payload);
+       if (ret) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
 
-               if (!provider_name || !ctx_name) {
-                       ret = -LTTNG_ERR_INVALID;
-                       goto end;
-               }
+       lsm.u.context.length = payload.buffer.size - sizeof(lsm);
 
-               provider_len = strlen(provider_name);
-               if (provider_len == 0) {
-                       ret = -LTTNG_ERR_INVALID;
-                       goto end;
-               }
-               lsm.u.context.provider_name_len = provider_len;
+       /* Update message header. */
+       memcpy(payload.buffer.data, &lsm, sizeof(lsm));
 
-               ctx_len = strlen(ctx_name);
-               if (ctx_len == 0) {
-                       ret = -LTTNG_ERR_INVALID;
-                       goto end;
-               }
-               lsm.u.context.context_name_len = ctx_len;
+       {
+               struct lttng_payload reply;
+               struct lttng_payload_view payload_view =
+                               lttng_payload_view_from_payload(&payload, 0,
+                               -1);
 
-               len = provider_len + ctx_len;
-               buf = zmalloc(len);
-               if (!buf) {
-                       ret = -LTTNG_ERR_NOMEM;
+               lttng_payload_init(&reply);
+               ret = lttng_ctl_ask_sessiond_payload(&payload_view, &reply);
+               lttng_payload_reset(&reply);
+               if (ret) {
                        goto end;
                }
-
-               memcpy(buf, provider_name, provider_len);
-               memcpy(buf + provider_len, ctx_name, ctx_len);
        }
-       memcpy(&lsm.u.context.ctx, ctx, sizeof(struct lttng_event_context));
-       /* Don't leak application addresses to the sessiond. */
-       lsm.u.context.ctx.u.app_ctx.provider_name = NULL;
-       lsm.u.context.ctx.u.app_ctx.ctx_name = NULL;
 
-       ret = lttng_ctl_ask_sessiond_varlen_no_cmd_header(&lsm, buf, len, NULL);
 end:
-       free(buf);
+       lttng_payload_reset(&payload);
        return ret;
 }
 
@@ -789,7 +1025,7 @@ 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);
@@ -804,7 +1040,7 @@ 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 = ">=";
@@ -839,140 +1075,31 @@ error:
 }
 
 /*
- * Generate the filter bytecode from a given 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 = { .cmd_type = LTTNG_ENABLE_EVENT };
+       struct lttng_payload payload;
+       int ret = 0;
+       unsigned int free_filter_expression = 0;
        struct filter_parser_ctx *ctx = NULL;
-       FILE *fmem = NULL;
-
-       assert(filter_expression);
-       assert(lsm);
-       assert(ctxp);
+       size_t bytecode_len = 0;
 
        /*
-        * Casting const to non-const, as the underlying function will use it in
-        * read-only mode.
+        * We have either a filter or some exclusions, so we need to set up
+        * a variable-length payload from where to send the data.
         */
-       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;
-               }
-       }
-
-       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;
-       }
-       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;
-}
+       lttng_payload_init(&payload);
 
-/*
- * 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
@@ -995,49 +1122,12 @@ int lttng_enable_event_with_exclusions(struct lttng_handle *handle,
                goto error;
        }
 
-       memset(&lsm, 0, sizeof(lsm));
-
-       /* If no channel name, send empty string. */
-       if (channel_name == NULL) {
-               lttng_ctl_copy_string(lsm.u.enable.channel_name, "",
-                               sizeof(lsm.u.enable.channel_name));
-       } else {
-               lttng_ctl_copy_string(lsm.u.enable.channel_name, channel_name,
-                               sizeof(lsm.u.enable.channel_name));
-       }
-
-       lsm.cmd_type = LTTNG_ENABLE_EVENT;
        if (ev->name[0] == '\0') {
-               /* Enable 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. */
-       memcpy(&lsm.u.enable.event, ev, sizeof(lsm.u.enable.event));
-
-       lttng_ctl_copy_string(lsm.session.name, handle->session_name,
-                       sizeof(lsm.session.name));
-       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;
+               /* Enable all events. */
+               ret = lttng_strncpy(ev->name, "*", sizeof(ev->name));
+               assert(ret == 0);
        }
 
-       /*
-        * 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. */
        if (filter_expression != NULL || handle->domain.type == LTTNG_DOMAIN_JUL
                        || handle->domain.type == LTTNG_DOMAIN_LOG4J
@@ -1047,7 +1137,7 @@ int lttng_enable_event_with_exclusions(struct lttng_handle *handle,
                                handle->domain.type == LTTNG_DOMAIN_PYTHON) {
                        char *agent_filter;
 
-                       /* Setup JUL filter if needed. */
+                       /* Setup agent filter if needed. */
                        agent_filter = set_agent_filter(filter_expression, ev);
                        if (!agent_filter) {
                                if (!filter_expression) {
@@ -1055,7 +1145,7 @@ int lttng_enable_event_with_exclusions(struct lttng_handle *handle,
                                         * No JUL and no filter, just skip
                                         * everything below.
                                         */
-                                       goto ask_sessiond;
+                                       goto serialize;
                                }
                        } else {
                                /*
@@ -1068,55 +1158,94 @@ int lttng_enable_event_with_exclusions(struct lttng_handle *handle,
                        }
                }
 
-               ret = generate_filter(filter_expression, &lsm, &ctx);
+               if (strnlen(filter_expression, LTTNG_FILTER_MAX_LEN) ==
+                               LTTNG_FILTER_MAX_LEN) {
+                       ret = -LTTNG_ERR_FILTER_INVAL;
+                       goto error;
+               }
+
+               ret = filter_parser_ctx_create_from_filter_expression(filter_expression, &ctx);
                if (ret) {
-                       goto filter_error;
+                       goto error;
                }
-       }
 
-       varlen_data = zmalloc(lsm.u.enable.bytecode_len
-                       + lsm.u.enable.expression_len
-                       + LTTNG_SYMBOL_NAME_LEN * exclusion_count);
-       if (!varlen_data) {
-               ret = -LTTNG_ERR_EXCLUSION_NOMEM;
-               goto mem_error;
+               bytecode_len = bytecode_get_len(&ctx->bytecode->b) +
+                               sizeof(ctx->bytecode->b);
+               if (bytecode_len > LTTNG_FILTER_MAX_LEN) {
+                       ret = -LTTNG_ERR_FILTER_INVAL;
+                       goto 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 - 1);
+serialize:
+       ret = lttng_event_serialize(ev, exclusion_count, exclusion_list,
+                       filter_expression, bytecode_len,
+                       (ctx && bytecode_len) ? &ctx->bytecode->b : NULL,
+                       &payload);
+       if (ret) {
+               ret = -LTTNG_ERR_INVALID;
+               goto 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);
+
+       /* If no channel name, send empty string. */
+       ret = lttng_strncpy(lsm.u.enable.channel_name, channel_name ?: "",
+                       sizeof(lsm.u.enable.channel_name));
+       if (ret) {
+               ret = -LTTNG_ERR_INVALID;
+               goto error;
        }
-       /* 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);
+
+       /* Domain */
+       COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
+
+       /* Session name */
+       ret = lttng_strncpy(lsm.session.name, handle->session_name,
+                       sizeof(lsm.session.name));
+       if (ret) {
+               ret = -LTTNG_ERR_INVALID;
+               goto error;
        }
 
-       ret = lttng_ctl_ask_sessiond_varlen_no_cmd_header(&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);
+       /* Length of the serialized event. */
+       lsm.u.enable.length = (uint32_t) payload.buffer.size;
+
+       {
+               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 error;
+               }
+
+               assert(fd_count == 0 || fd_count == 1);
+               if (fd_count == 1) {
+                       struct fd_handle *h =
+                                       lttng_payload_view_pop_fd_handle(&view);
+
+                       if (!h) {
+                               goto error;
+                       }
+
+                       fd_to_send = fd_handle_get_fd(h);
+                       fd_handle_put(h);
+               }
+
+               lsm.fd_count = fd_count;
+
+               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:
+error:
        if (filter_expression && ctx) {
                filter_bytecode_free(ctx);
                filter_ir_free(ctx);
                filter_parser_ctx_free(ctx);
        }
-filter_error:
        if (free_filter_expression) {
                /*
                 * The filter expression has been replaced and must be freed as
@@ -1125,15 +1254,11 @@ filter_error:
                 */
                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 ret;
-
-ask_sessiond:
-       ret = lttng_ctl_ask_sessiond(&lsm, NULL);
+       lttng_payload_reset(&payload);
        return ret;
 }
 
@@ -1141,11 +1266,19 @@ int lttng_disable_event_ext(struct lttng_handle *handle,
                struct lttng_event *ev, const char *channel_name,
                const char *original_filter_expression)
 {
-       struct lttcomm_session_msg lsm;
-       char *varlen_data;
+       struct lttcomm_session_msg lsm = { .cmd_type = LTTNG_DISABLE_EVENT };
+       struct lttng_payload payload;
        int ret = 0;
        unsigned int free_filter_expression = 0;
        struct filter_parser_ctx *ctx = NULL;
+       size_t bytecode_len = 0;
+
+       /*
+        * 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);
+
        /*
         * Cast as non-const since we may replace the filter expression
         * by a dynamically allocated string. Otherwise, the original
@@ -1168,45 +1301,7 @@ int lttng_disable_event_ext(struct lttng_handle *handle,
                goto error;
        }
 
-       memset(&lsm, 0, sizeof(lsm));
-
-       /* If no channel name, send empty string. */
-       if (channel_name == NULL) {
-               lttng_ctl_copy_string(lsm.u.disable.channel_name, "",
-                               sizeof(lsm.u.disable.channel_name));
-       } else {
-               lttng_ctl_copy_string(lsm.u.disable.channel_name, channel_name,
-                               sizeof(lsm.u.disable.channel_name));
-       }
-
-       lsm.cmd_type = LTTNG_DISABLE_EVENT;
-
-       lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
-       /* FIXME: copying non-packed struct to packed struct. */
-       memcpy(&lsm.u.disable.event, ev, sizeof(lsm.u.disable.event));
-
-       lttng_ctl_copy_string(lsm.session.name, handle->session_name,
-                       sizeof(lsm.session.name));
-       lsm.u.disable.bytecode_len = 0;
-
-       /*
-        * For the JUL domain, a filter is enforced except for the
-        * disable all event. This is done to avoid having the event in
-        * all sessions thus filtering by logger name.
-        */
-       if (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 a filter, 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) {
@@ -1215,7 +1310,7 @@ int lttng_disable_event_ext(struct lttng_handle *handle,
                                handle->domain.type == LTTNG_DOMAIN_PYTHON) {
                        char *agent_filter;
 
-                       /* Setup JUL filter if needed. */
+                       /* Setup agent filter if needed. */
                        agent_filter = set_agent_filter(filter_expression, ev);
                        if (!agent_filter) {
                                if (!filter_expression) {
@@ -1223,11 +1318,11 @@ int lttng_disable_event_ext(struct lttng_handle *handle,
                                         * No JUL and no filter, just skip
                                         * everything below.
                                         */
-                                       goto ask_sessiond;
+                                       goto serialize;
                                }
                        } else {
                                /*
-                                * With a JUL filter, the original filter has
+                                * With an agent filter, the original filter has
                                 * been added to it thus replace the filter
                                 * expression.
                                 */
@@ -1236,44 +1331,92 @@ int lttng_disable_event_ext(struct lttng_handle *handle,
                        }
                }
 
-               ret = generate_filter(filter_expression, &lsm, &ctx);
+               if (strnlen(filter_expression, LTTNG_FILTER_MAX_LEN) ==
+                               LTTNG_FILTER_MAX_LEN) {
+                       ret = -LTTNG_ERR_FILTER_INVAL;
+                       goto error;
+               }
+
+               ret = filter_parser_ctx_create_from_filter_expression(filter_expression, &ctx);
                if (ret) {
-                       goto filter_error;
+                       goto error;
+               }
+
+               bytecode_len = bytecode_get_len(&ctx->bytecode->b) +
+                               sizeof(ctx->bytecode->b);
+               if (bytecode_len > LTTNG_FILTER_MAX_LEN) {
+                       ret = -LTTNG_ERR_FILTER_INVAL;
+                       goto error;
                }
        }
 
-       varlen_data = zmalloc(lsm.u.disable.bytecode_len
-                       + lsm.u.disable.expression_len);
-       if (!varlen_data) {
-               ret = -LTTNG_ERR_EXCLUSION_NOMEM;
-               goto mem_error;
+serialize:
+       ret = lttng_event_serialize(ev, 0, NULL,
+                       filter_expression, bytecode_len,
+                       (ctx && bytecode_len) ? &ctx->bytecode->b : NULL,
+                       &payload);
+       if (ret) {
+               ret = -LTTNG_ERR_INVALID;
+               goto error;
        }
 
-       /* Add filter expression. */
-       if (lsm.u.disable.expression_len != 0) {
-               memcpy(varlen_data,
-                       filter_expression,
-                       lsm.u.disable.expression_len);
+       /* If no channel name, send empty string. */
+       ret = lttng_strncpy(lsm.u.disable.channel_name, channel_name ?: "",
+                       sizeof(lsm.u.disable.channel_name));
+       if (ret) {
+               ret = -LTTNG_ERR_INVALID;
+               goto error;
        }
-       /* Add filter bytecode next. */
-       if (ctx && lsm.u.disable.bytecode_len != 0) {
-               memcpy(varlen_data
-                       + lsm.u.disable.expression_len,
-                       &ctx->bytecode->b,
-                       lsm.u.disable.bytecode_len);
+
+       /* Domain */
+       COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
+
+       /* Session name */
+       ret = lttng_strncpy(lsm.session.name, handle->session_name,
+                       sizeof(lsm.session.name));
+       if (ret) {
+               ret = -LTTNG_ERR_INVALID;
+               goto error;
        }
 
-       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);
+       /* Length of the serialized event. */
+       lsm.u.disable.length = (uint32_t) payload.buffer.size;
+
+       {
+               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 error;
+               }
+
+               assert(fd_count == 0 || fd_count == 1);
+               if (fd_count == 1) {
+                       struct fd_handle *h =
+                                       lttng_payload_view_pop_fd_handle(&view);
+
+                       if (!h) {
+                               goto error;
+                       }
+
+                       fd_to_send = fd_handle_get_fd(h);
+                       fd_handle_put(h);
+               }
+
+               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:
+error:
        if (filter_expression && ctx) {
                filter_bytecode_free(ctx);
                filter_ir_free(ctx);
                filter_parser_ctx_free(ctx);
        }
-filter_error:
        if (free_filter_expression) {
                /*
                 * The filter expression has been replaced and must be freed as
@@ -1282,15 +1425,11 @@ filter_error:
                 */
                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 ret;
-
-ask_sessiond:
-       ret = lttng_ctl_ask_sessiond(&lsm, NULL);
+       lttng_payload_reset(&payload);
        return ret;
 }
 
@@ -1303,13 +1442,71 @@ ask_sessiond:
 int lttng_disable_event(struct lttng_handle *handle, const char *name,
                const char *channel_name)
 {
+       int ret;
        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);
+       ret = lttng_strncpy(ev.name, name ?: "", sizeof(ev.name));
+       if (ret) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
+
+       ret = lttng_disable_event_ext(handle, &ev, channel_name, NULL);
+end:
+       return ret;
+}
+
+struct lttng_channel *lttng_channel_create(struct lttng_domain *domain)
+{
+       struct lttng_channel *channel = NULL;
+
+       if (!domain) {
+               goto end;
+       }
+
+       /* 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 end;
+               }
+               break;
+       case LTTNG_DOMAIN_KERNEL:
+               if (domain->buf_type != LTTNG_BUFFER_GLOBAL) {
+                       goto end;
+               }
+               break;
+       default:
+               goto end;
+       }
+
+       channel = lttng_channel_create_internal();
+       if (!channel) {
+               goto end;
+       }
+
+       lttng_channel_set_default_attr(domain, &channel->attr);
+end:
+       return channel;
+}
+
+void lttng_channel_destroy(struct lttng_channel *channel)
+{
+       if (!channel) {
+               return;
+       }
+
+       if (channel->attr.extended.ptr) {
+               free(channel->attr.extended.ptr);
+       }
+       free(channel);
 }
 
 /*
@@ -1317,27 +1514,92 @@ int lttng_disable_event(struct lttng_handle *handle, const char *name,
  * 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)
 {
+       enum lttng_error_code ret_code;
+       int ret;
+       struct lttng_dynamic_buffer buffer;
        struct lttcomm_session_msg lsm;
+       uint64_t total_buffer_size_needed_per_cpu = 0;
+       struct lttng_channel *channel = NULL;
+
+       lttng_dynamic_buffer_init(&buffer);
 
        /* NULL arguments are forbidden. No default values. */
-       if (handle == NULL || chan == NULL) {
-               return -LTTNG_ERR_INVALID;
+       if (handle == NULL || in_chan == NULL) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
        }
 
-       memset(&lsm, 0, sizeof(lsm));
+       /*
+        * Verify that the amount of memory required to create the requested
+        * buffer is available on the system at the moment.
+        */
+       if (in_chan->attr.num_subbuf >
+                       UINT64_MAX / in_chan->attr.subbuf_size) {
+               /* Overflow */
+               ret = -LTTNG_ERR_OVERFLOW;
+               goto end;
+       }
+
+       total_buffer_size_needed_per_cpu =
+                       in_chan->attr.num_subbuf * in_chan->attr.subbuf_size;
+       ret_code = check_enough_available_memory(
+                       total_buffer_size_needed_per_cpu);
+       if (ret_code != LTTNG_OK) {
+               ret = -ret_code;
+               goto end;
+       }
+
+       /* Copy the channel for easier manipulation. */
+       channel = lttng_channel_copy(in_chan);
+       if (!channel) {
+               ret = -LTTNG_ERR_NOMEM;
+               goto end;
+       }
+
+       /* Populate the channel extended attribute if necessary. */
+       if (!channel->attr.extended.ptr) {
+               struct lttng_channel_extended *extended =
+                               (struct lttng_channel_extended *) zmalloc(
+                                               sizeof(*extended));
+
+               if (!extended) {
+                       ret = -LTTNG_ERR_NOMEM;
+                       goto end;
+               }
+               lttng_channel_set_default_extended_attr(
+                               &handle->domain, extended);
+               channel->attr.extended.ptr = extended;
+       }
 
-       memcpy(&lsm.u.channel.chan, chan, sizeof(lsm.u.channel.chan));
+       /* Prepare the payload */
+       memset(&lsm, 0, sizeof(lsm));
 
        lsm.cmd_type = LTTNG_ENABLE_CHANNEL;
+       COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
 
-       lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
+       ret = lttng_strncpy(lsm.session.name, handle->session_name,
+                                   sizeof(lsm.session.name));
+       if (ret) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
 
-       lttng_ctl_copy_string(lsm.session.name, handle->session_name,
-                       sizeof(lsm.session.name));
+       ret = lttng_channel_serialize(channel, &buffer);
+       if (ret) {
+               ret = -LTTNG_ERR_FATAL;
+               goto end;
+       }
 
-       return lttng_ctl_ask_sessiond(&lsm, NULL);
+       lsm.u.channel.length = buffer.size;
+
+       ret = lttng_ctl_ask_sessiond_varlen_no_cmd_header(
+                       &lsm, buffer.data, buffer.size, NULL);
+end:
+       lttng_channel_destroy(channel);
+       lttng_dynamic_buffer_reset(&buffer);
+       return ret;
 }
 
 /*
@@ -1346,6 +1608,7 @@ int lttng_enable_channel(struct lttng_handle *handle,
  */
 int lttng_disable_channel(struct lttng_handle *handle, const char *name)
 {
+       int ret;
        struct lttcomm_session_msg lsm;
 
        /* Safety check. Both are mandatory. */
@@ -1357,67 +1620,25 @@ int lttng_disable_channel(struct lttng_handle *handle, const char *name)
 
        lsm.cmd_type = LTTNG_DISABLE_CHANNEL;
 
-       lttng_ctl_copy_string(lsm.u.disable.channel_name, name,
+       ret = lttng_strncpy(lsm.u.disable.channel_name, name,
                        sizeof(lsm.u.disable.channel_name));
-
-       lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
-
-       lttng_ctl_copy_string(lsm.session.name, handle->session_name,
-                       sizeof(lsm.session.name));
-
-       return lttng_ctl_ask_sessiond(&lsm, NULL);
-}
-
-/*
- * Add PID to session tracker.
- * Return 0 on success else a negative LTTng error code.
- */
-int lttng_track_pid(struct lttng_handle *handle, int pid)
-{
-       struct lttcomm_session_msg lsm;
-
-       /* NULL arguments are forbidden. No default values. */
-       if (handle == NULL) {
-               return -LTTNG_ERR_INVALID;
+       if (ret) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
        }
 
-       memset(&lsm, 0, sizeof(lsm));
-
-       lsm.cmd_type = LTTNG_TRACK_PID;
-       lsm.u.pid_tracker.pid = pid;
-
-       lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
-
-       lttng_ctl_copy_string(lsm.session.name, handle->session_name,
-                       sizeof(lsm.session.name));
-
-       return lttng_ctl_ask_sessiond(&lsm, NULL);
-}
-
-/*
- * Remove PID from session tracker.
- * Return 0 on success else a negative LTTng error code.
- */
-int lttng_untrack_pid(struct lttng_handle *handle, int pid)
-{
-       struct lttcomm_session_msg lsm;
+       COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
 
-       /* NULL arguments are forbidden. No default values. */
-       if (handle == NULL) {
-               return -LTTNG_ERR_INVALID;
+       ret = lttng_strncpy(lsm.session.name, handle->session_name,
+                           sizeof(lsm.session.name));
+       if (ret) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
        }
 
-       memset(&lsm, 0, sizeof(lsm));
-
-       lsm.cmd_type = LTTNG_UNTRACK_PID;
-       lsm.u.pid_tracker.pid = pid;
-
-       lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
-
-       lttng_ctl_copy_string(lsm.session.name, handle->session_name,
-                       sizeof(lsm.session.name));
-
-       return lttng_ctl_ask_sessiond(&lsm, NULL);
+       ret = lttng_ctl_ask_sessiond(&lsm, NULL);
+end:
+       return ret;
 }
 
 /*
@@ -1429,23 +1650,64 @@ int lttng_untrack_pid(struct lttng_handle *handle, int pid)
 int lttng_list_tracepoints(struct lttng_handle *handle,
                struct lttng_event **events)
 {
-       int ret;
-       struct lttcomm_session_msg lsm;
-
-       if (handle == NULL) {
-               return -LTTNG_ERR_INVALID;
+        enum lttng_error_code ret_code;
+        int ret, total_payload_received;
+        char *reception_buffer = NULL;
+        struct lttcomm_session_msg lsm = { .cmd_type = LTTNG_LIST_TRACEPOINTS };
+        struct lttcomm_list_command_header *cmd_header = NULL;
+        size_t cmd_header_len;
+        unsigned int nb_events = 0;
+
+        if (handle == NULL) {
+                ret = -LTTNG_ERR_INVALID;
+                goto end;
+        }
+
+        COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
+
+        ret = lttng_ctl_ask_sessiond_fds_varlen(&lsm, NULL, 0, NULL, 0,
+                        (void **) &reception_buffer, (void **) &cmd_header,
+                        &cmd_header_len);
+        if (ret < 0) {
+                goto end;
+        }
+
+        total_payload_received = ret;
+
+        if (!cmd_header) {
+                ret = -LTTNG_ERR_UNK;
+                goto end;
+        }
+
+        if (cmd_header->count > INT_MAX) {
+                ret = -LTTNG_ERR_OVERFLOW;
+                goto end;
+        }
+
+        nb_events = (unsigned int) cmd_header->count;
+
+       {
+               struct lttng_buffer_view events_view =
+                               lttng_buffer_view_init(reception_buffer, 0,
+                                               total_payload_received);
+               struct lttng_payload_view events_payload_view =
+                               lttng_payload_view_from_buffer_view(
+                                               &events_view, 0, -1);
+
+               ret_code = lttng_events_create_and_flatten_from_payload(
+                               &events_payload_view, nb_events, events);
+               if (ret_code != LTTNG_OK) {
+                       ret = -ret_code;
+                       goto end;
+               }
        }
 
-       memset(&lsm, 0, sizeof(lsm));
-       lsm.cmd_type = LTTNG_LIST_TRACEPOINTS;
-       lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
-
-       ret = lttng_ctl_ask_sessiond(&lsm, (void **) events);
-       if (ret < 0) {
-               return ret;
-       }
+       ret = (int) nb_events;
 
-       return ret / sizeof(struct lttng_event);
+end:
+        free(cmd_header);
+        free(reception_buffer);
+        return ret;
 }
 
 /*
@@ -1457,23 +1719,75 @@ int lttng_list_tracepoints(struct lttng_handle *handle,
 int lttng_list_tracepoint_fields(struct lttng_handle *handle,
                struct lttng_event_field **fields)
 {
+       enum lttng_error_code ret_code;
        int ret;
        struct lttcomm_session_msg lsm;
+       const struct lttcomm_list_command_header *cmd_header = NULL;
+       unsigned int nb_event_fields = 0;
+       struct lttng_payload reply;
+
+       lttng_payload_init(&reply);
 
        if (handle == NULL) {
-               return -LTTNG_ERR_INVALID;
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
        }
 
        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) {
-               return ret;
+       {
+               struct lttng_payload_view message_view =
+                               lttng_payload_view_init_from_buffer(
+                                       (const char *) &lsm, 0,
+                                       sizeof(lsm));
+
+               ret = lttng_ctl_ask_sessiond_payload(&message_view, &reply);
+               if (ret < 0) {
+                       goto end;
+               }
+       }
+
+       {
+               const struct lttng_buffer_view cmd_header_view =
+                               lttng_buffer_view_from_dynamic_buffer(
+                                       &reply.buffer, 0, sizeof(*cmd_header));
+
+               if (!lttng_buffer_view_is_valid(&cmd_header_view)) {
+                       ret = -LTTNG_ERR_INVALID_PROTOCOL;
+                       goto end;
+               }
+
+               cmd_header = (struct lttcomm_list_command_header *)
+                               cmd_header_view.data;
+       }
+
+       if (cmd_header->count > INT_MAX) {
+               ret = -LTTNG_ERR_OVERFLOW;
+               goto end;
+       }
+
+       nb_event_fields = cmd_header->count;
+
+       {
+               struct lttng_payload_view reply_view =
+                               lttng_payload_view_from_payload(&reply,
+                               sizeof(*cmd_header), -1);
+
+               ret_code = lttng_event_fields_create_and_flatten_from_payload(
+                               &reply_view, nb_event_fields, fields);
+               if (ret_code != LTTNG_OK) {
+                       ret = -ret_code;
+                       goto end;
+               }
        }
 
-       return ret / sizeof(struct lttng_event_field);
+       ret = nb_event_fields;
+
+end:
+       lttng_payload_reset(&reply);
+       return ret;
 }
 
 /*
@@ -1485,24 +1799,65 @@ int lttng_list_tracepoint_fields(struct lttng_handle *handle,
  */
 int lttng_list_syscalls(struct lttng_event **events)
 {
-       int ret;
-       struct lttcomm_session_msg lsm;
-
-       if (!events) {
-               return -LTTNG_ERR_INVALID;
-       }
-
-       memset(&lsm, 0, sizeof(lsm));
-       lsm.cmd_type = LTTNG_LIST_SYSCALLS;
-       /* Force kernel domain for system calls. */
-       lsm.domain.type = LTTNG_DOMAIN_KERNEL;
-
-       ret = lttng_ctl_ask_sessiond(&lsm, (void **) events);
-       if (ret < 0) {
-               return ret;
-       }
+        enum lttng_error_code ret_code;
+        int ret, total_payload_received;
+        char *reception_buffer = NULL;
+        struct lttcomm_session_msg lsm = {};
+        struct lttcomm_list_command_header *cmd_header = NULL;
+        size_t cmd_header_len;
+        uint32_t nb_events = 0;
+
+        if (!events) {
+                ret = -LTTNG_ERR_INVALID;
+                goto end;
+        }
+
+        lsm.cmd_type = LTTNG_LIST_SYSCALLS;
+        /* Force kernel domain for system calls. */
+        lsm.domain.type = LTTNG_DOMAIN_KERNEL;
+
+        ret = lttng_ctl_ask_sessiond_fds_varlen(&lsm, NULL, 0, NULL, 0,
+                        (void **) &reception_buffer, (void **) &cmd_header,
+                        &cmd_header_len);
+        if (ret < 0) {
+                goto end;
+        }
+        total_payload_received = ret;
+
+        if (!cmd_header) {
+                ret = -LTTNG_ERR_UNK;
+                goto end;
+        }
+
+        if (cmd_header->count > INT_MAX) {
+                ret = -LTTNG_ERR_OVERFLOW;
+                goto end;
+        }
+
+        nb_events = (unsigned int) cmd_header->count;
+
+        {
+                const struct lttng_buffer_view events_view =
+                                lttng_buffer_view_init(reception_buffer, 0,
+                                                total_payload_received);
+               struct lttng_payload_view events_payload_view =
+                               lttng_payload_view_from_buffer_view(
+                                               &events_view, 0, -1);
+
+                ret_code = lttng_events_create_and_flatten_from_payload(
+                                &events_payload_view, nb_events, events);
+                if (ret_code != LTTNG_OK) {
+                        ret = -ret_code;
+                        goto end;
+                }
+        }
+
+        ret = (int) nb_events;
 
-       return ret / sizeof(struct lttng_event);
+end:
+        free(reception_buffer);
+        free(cmd_header);
+        return ret;
 }
 
 /*
@@ -1514,80 +1869,296 @@ const char *lttng_strerror(int code)
        return error_get_str(code);
 }
 
+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;
+       size_t descriptor_size;
+       struct lttng_session_descriptor *descriptor_reply = NULL;
+
+       lttng_dynamic_buffer_init(&payload);
+       if (!session_descriptor) {
+               ret_code = LTTNG_ERR_INVALID;
+               goto end;
+       }
+
+       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;
+
+               if (!home_dir || home_dir_len > LTTNG_PATH_MAX) {
+                       ret_code = LTTNG_ERR_FATAL;
+                       goto end;
+               }
+
+               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;
+               }
+       }
+
+       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;
+
+       /* 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;
+       }
+
+       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;
+}
+
 /*
- * Create a brand new session using name and url for destination.
+ * Create a new session using name and url for destination.
  *
- * Returns LTTNG_OK on success or a negative error code.
+ * Return 0 on success else a negative LTTng error code.
  */
 int lttng_create_session(const char *name, const char *url)
 {
        int ret;
        ssize_t size;
-       struct lttcomm_session_msg lsm;
        struct lttng_uri *uris = NULL;
+       struct lttng_session_descriptor *descriptor = NULL;
+       enum lttng_error_code ret_code;
 
-       if (name == NULL) {
-               return -LTTNG_ERR_INVALID;
+       if (!name) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
        }
 
-       memset(&lsm, 0, sizeof(lsm));
-
-       lsm.cmd_type = LTTNG_CREATE_SESSION;
-       lttng_ctl_copy_string(lsm.session.name, name, sizeof(lsm.session.name));
-
-       /* There should never be a data URL */
        size = uri_parse_str_urls(url, NULL, &uris);
        if (size < 0) {
-               return -LTTNG_ERR_INVALID;
+               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;
+}
 
-       lsm.u.uri.size = size;
+/*
+ * Create a session exclusively used for snapshot.
+ *
+ * Return 0 on success else a negative LTTng error code.
+ */
+int lttng_create_session_snapshot(const char *name, const char *snapshot_url)
+{
+       int ret;
+       enum lttng_error_code ret_code;
+       ssize_t size;
+       struct lttng_uri *uris = NULL;
+       struct lttng_session_descriptor *descriptor = NULL;
 
-       ret = lttng_ctl_ask_sessiond_varlen_no_cmd_header(&lsm, uris,
-                       sizeof(struct lttng_uri) * size, NULL);
+       if (!name) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
+
+       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;
 }
 
 /*
- * Destroy session using name.
- * Returns size of returned session payload data or a negative error code.
+ * Create a session exclusively used for live.
+ *
+ * Return 0 on success else a negative LTTng error code.
  */
-int _lttng_destroy_session(const char *session_name)
+int lttng_create_session_live(const char *name, const char *url,
+               unsigned int timer_interval)
 {
-       struct lttcomm_session_msg lsm;
+       int ret;
+       enum lttng_error_code ret_code;
+       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_DESTROY_SESSION;
-
-       lttng_ctl_copy_string(lsm.session.name, session_name,
-                       sizeof(lsm.session.name));
-
-       return lttng_ctl_ask_sessiond(&lsm, NULL);
+       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.
+        * 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 = _lttng_destroy_session(session_name);
+       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;
 }
 
@@ -1596,21 +2167,10 @@ end:
  */
 int lttng_destroy_session_no_wait(const char *session_name)
 {
-       int ret;
-
-       /*
-        * Stop the tracing without waiting for the data.
-        * The session might already have been stopped, so just
-        * skip this error.
-        */
-       ret = _lttng_stop_tracing(session_name, 0);
-       if (ret && ret != -LTTNG_ERR_TRACE_ALREADY_STOPPED) {
-               goto end;
-       }
+       enum lttng_error_code ret_code;
 
-       ret = _lttng_destroy_session(session_name);
-end:
-       return ret;
+       ret_code = lttng_destroy_session_ext(session_name, NULL);
+       return ret_code == LTTNG_OK ? 0 : -ret_code;
 }
 
 /*
@@ -1619,24 +2179,83 @@ end:
  * Returns the number of lttng_session entries in sessions;
  * on error, returns a negative value.
  */
-int lttng_list_sessions(struct lttng_session **sessions)
+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) {
-               return ret;
+       /*
+        * Initialize out_sessions to NULL so it is initialized when
+        * lttng_list_sessions returns 0, thus allowing *out_sessions to
+        * be subsequently freed.
+        */
+       *out_sessions = NULL;
+       ret = lttng_ctl_ask_sessiond(&lsm, (void**) &sessions);
+       if (ret <= 0) {
+               goto end;
+       }
+       if (!sessions) {
+               ret = -LTTNG_ERR_FATAL;
+               goto end;
        }
 
-       return ret / sizeof(struct lttng_session);
-}
+       if (ret % session_size) {
+               ret = -LTTNG_ERR_UNK;
+               free(sessions);
+               goto end;
+       }
+       session_count = (size_t) ret / session_size;
+       sessions_extended_begin = (struct lttng_session_extended *)
+                       (&sessions[session_count]);
 
-int lttng_set_session_shm_path(const char *session_name,
+       /* 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)
 {
+       int ret;
        struct lttcomm_session_msg lsm;
 
        if (session_name == NULL) {
@@ -1646,12 +2265,23 @@ int lttng_set_session_shm_path(const char *session_name,
        memset(&lsm, 0, sizeof(lsm));
        lsm.cmd_type = LTTNG_SET_SESSION_SHM_PATH;
 
-       lttng_ctl_copy_string(lsm.session.name, session_name,
+       ret = lttng_strncpy(lsm.session.name, session_name,
                        sizeof(lsm.session.name));
-       lttng_ctl_copy_string(lsm.u.set_shm_path.shm_path, shm_path,
+       if (ret) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
+
+       ret = lttng_strncpy(lsm.u.set_shm_path.shm_path, shm_path ?: "",
                        sizeof(lsm.u.set_shm_path.shm_path));
+       if (ret) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
 
-       return lttng_ctl_ask_sessiond(&lsm, NULL);
+       ret = lttng_ctl_ask_sessiond(&lsm, NULL);
+end:
+       return ret;
 }
 
 /*
@@ -1667,21 +2297,28 @@ int lttng_list_domains(const char *session_name,
        struct lttcomm_session_msg lsm;
 
        if (session_name == NULL) {
-               return -LTTNG_ERR_INVALID;
+               ret = -LTTNG_ERR_INVALID;
+               goto error;
        }
 
        memset(&lsm, 0, sizeof(lsm));
        lsm.cmd_type = LTTNG_LIST_DOMAINS;
 
-       lttng_ctl_copy_string(lsm.session.name, session_name,
+       ret = lttng_strncpy(lsm.session.name, session_name,
                        sizeof(lsm.session.name));
+       if (ret) {
+               ret = -LTTNG_ERR_INVALID;
+               goto error;
+       }
 
        ret = lttng_ctl_ask_sessiond(&lsm, (void**) domains);
        if (ret < 0) {
-               return ret;
+               goto error;
        }
 
        return ret / sizeof(struct lttng_domain);
+error:
+       return ret;
 }
 
 /*
@@ -1693,26 +2330,74 @@ int lttng_list_domains(const char *session_name,
 int lttng_list_channels(struct lttng_handle *handle,
                struct lttng_channel **channels)
 {
-       int ret;
+       int ret, total_payload_received;
        struct lttcomm_session_msg lsm;
+       char *reception_buffer = NULL;
+       size_t cmd_header_len = 0;
+       struct lttcomm_list_command_header *cmd_header = NULL;
+       struct lttng_dynamic_buffer tmp_buffer;
+
+       lttng_dynamic_buffer_init(&tmp_buffer);
 
        if (handle == NULL) {
-               return -LTTNG_ERR_INVALID;
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
        }
 
        memset(&lsm, 0, sizeof(lsm));
        lsm.cmd_type = LTTNG_LIST_CHANNELS;
-       lttng_ctl_copy_string(lsm.session.name, handle->session_name,
+       ret = lttng_strncpy(lsm.session.name, handle->session_name,
                        sizeof(lsm.session.name));
+       if (ret) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
 
-       lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
+       COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
 
-       ret = lttng_ctl_ask_sessiond(&lsm, (void**) channels);
+       ret = lttng_ctl_ask_sessiond_fds_varlen(&lsm, NULL, 0, NULL, 0,
+                       (void **) &reception_buffer, (void **) &cmd_header,
+                       &cmd_header_len);
        if (ret < 0) {
-               return ret;
+               goto end;
+       }
+
+       total_payload_received = ret;
+
+       if (cmd_header_len != sizeof(*cmd_header)) {
+               ret = -LTTNG_ERR_FATAL;
+               goto end;
+       }
+
+       if (!cmd_header) {
+               ret = LTTNG_ERR_UNK;
+               goto end;
+       }
+
+       if (cmd_header->count > INT_MAX) {
+               ret = -LTTNG_ERR_OVERFLOW;
+               goto end;
+       }
+
+       {
+               enum lttng_error_code ret_code;
+               const struct lttng_buffer_view events_view =
+                               lttng_buffer_view_init(reception_buffer, 0,
+                                               total_payload_received);
+
+               ret_code = lttng_channels_create_and_flatten_from_buffer(
+                               &events_view, cmd_header->count, channels);
+               if (ret_code != LTTNG_OK) {
+                       ret = -ret_code;
+                       goto end;
+               }
        }
 
-       return ret / sizeof(struct lttng_channel);
+       ret = (int) cmd_header->count;
+end:
+       free(cmd_header);
+       free(reception_buffer);
+       return ret;
 }
 
 /*
@@ -1725,95 +2410,85 @@ 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_event_command_header *cmd_header = NULL;
-       size_t cmd_header_len;
-       uint32_t nb_events, i;
-       void *extended_at;
+       struct lttcomm_session_msg lsm = {};
+       struct lttng_payload reply;
+       struct lttng_payload_view lsm_view =
+                       lttng_payload_view_init_from_buffer(
+                               (const char *) &lsm, 0, sizeof(lsm));
+       unsigned int nb_events = 0;
+
+       lttng_payload_init(&reply);
 
-       /* Safety check. An handle and channel name are mandatory */
+       /* 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));
+       /* Initialize command parameters. */
        lsm.cmd_type = LTTNG_LIST_EVENTS;
-       lttng_ctl_copy_string(lsm.session.name, handle->session_name,
+       ret = lttng_strncpy(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));
-       lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
-
-       ret = lttng_ctl_ask_sessiond_varlen(&lsm, NULL, 0, (void **) events,
-               (void **) &cmd_header, &cmd_header_len);
-       if (ret < 0) {
-               goto error;
+       if (ret) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
        }
 
-       /* Set number of events and free command header */
-       nb_events = cmd_header->nb_events;
-       if (nb_events > INT_MAX) {
-               ret = -EOVERFLOW;
-               goto error;
+       ret = lttng_strncpy(lsm.u.list.channel_name, channel_name,
+                       sizeof(lsm.u.list.channel_name));
+       if (ret) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
        }
-       ret = (int) nb_events;
-       free(cmd_header);
-       cmd_header = NULL;
 
-       /* Set extended info pointers */
-       extended_at = ((void*) (*events)) +
-                       nb_events * sizeof(struct lttng_event);
+       COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
 
-       for (i = 0; i < nb_events; i++) {
-               struct lttcomm_event_extended_header *ext_header;
-               struct lttng_event *event = &(*events)[i];
-
-               event->extended.ptr = extended_at;
-               ext_header =
-                       (struct lttcomm_event_extended_header *) extended_at;
-               extended_at += sizeof(*ext_header);
-               extended_at += ext_header->filter_len;
-               extended_at +=
-                       ext_header->nb_exclusions * LTTNG_SYMBOL_NAME_LEN;
+       /* Execute command against the session daemon. */
+       ret = lttng_ctl_ask_sessiond_payload(&lsm_view, &reply);
+       if (ret < 0) {
+               goto end;
        }
 
-       return ret;
-error:
-       free(cmd_header);
-       free(*events);
-       return ret;
-}
-
-int lttng_event_get_filter_string(struct lttng_event *event,
-       const char **filter_string)
-{
-       int ret = 0;
-       struct lttcomm_event_extended_header *ext_header;
+       {
+               const struct lttcomm_list_command_header *cmd_reply_header =
+                               NULL;
+               const struct lttng_payload_view cmd_reply_header_view =
+                               lttng_payload_view_from_payload(&reply, 0,
+                                               sizeof(*cmd_reply_header));
 
-       if (!event || !filter_string) {
-               ret = -LTTNG_ERR_INVALID;
-               goto end;
-       }
+               if (!lttng_payload_view_is_valid(&cmd_reply_header_view)) {
+                       ret = -LTTNG_ERR_INVALID_PROTOCOL;
+                       goto end;
+               }
 
-       ext_header = event->extended.ptr;
+               cmd_reply_header = (const struct lttcomm_list_command_header *)
+                                                  cmd_reply_header_view.buffer
+                                                                  .data;
+               if (cmd_reply_header->count > INT_MAX) {
+                       ret = -LTTNG_ERR_OVERFLOW;
+                       goto end;
+               }
 
-       if (!ext_header) {
-               /*
-                * This can happen since the lttng_event structure is
-                * used for other tasks where this pointer is never set.
-                */
-               *filter_string = NULL;
-               goto end;
+               nb_events = (unsigned int) cmd_reply_header->count;
        }
 
-       if (ext_header->filter_len) {
-               *filter_string = ((const char *) (ext_header)) +
-                       sizeof(*ext_header);
-       } else {
-               *filter_string = NULL;
+       {
+               enum lttng_error_code ret_code;
+               struct lttng_payload_view cmd_reply_payload = lttng_payload_view_from_payload(
+                               &reply,
+                               sizeof(struct lttcomm_list_command_header), -1);
+
+               ret_code = lttng_events_create_and_flatten_from_payload(
+                               &cmd_reply_payload, nb_events, events);
+               if (ret_code != LTTNG_OK) {
+                       ret = -((int) ret_code);
+                       goto end;
+               }
        }
 
+       ret = (int) nb_events;
 end:
+       lttng_payload_reset(&reply);
        return ret;
 }
 
@@ -1824,37 +2499,29 @@ end:
  */
 int lttng_set_tracing_group(const char *name)
 {
+       char *new_group;
        if (name == NULL) {
                return -LTTNG_ERR_INVALID;
        }
 
-       if (asprintf(&tracing_group, "%s", name) < 0) {
+       if (asprintf(&new_group, "%s", name) < 0) {
                return -LTTNG_ERR_FATAL;
        }
 
+       free(tracing_group);
+       tracing_group = new_group;
+       new_group = NULL;
+
        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;
-
-       /* Safety check. NULL pointer are forbidden */
-       if (handle == NULL || calibrate == NULL) {
-               return -LTTNG_ERR_INVALID;
-       }
-
-       memset(&lsm, 0, sizeof(lsm));
-       lsm.cmd_type = LTTNG_CALIBRATE;
-       lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
-
-       memcpy(&lsm.u.calibrate, calibrate, sizeof(lsm.u.calibrate));
-
-       return lttng_ctl_ask_sessiond(&lsm, NULL);
+       /*
+        * This command was removed in LTTng 2.9.
+        */
+       return -LTTNG_ERR_UND;
 }
 
 /*
@@ -1864,11 +2531,15 @@ int lttng_calibrate(struct lttng_handle *handle,
 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;
        }
 
+       /* Save the pointer for later use */
+       extended = (struct lttng_channel_extended *) attr->extended.ptr;
        memset(attr, 0, sizeof(struct lttng_channel_attr));
 
        /* Same for all domains. */
@@ -1911,6 +2582,158 @@ void lttng_channel_set_default_attr(struct lttng_domain *domain,
                /* Default behavior: leave set to 0. */
                break;
        }
+
+       if (extended) {
+               lttng_channel_set_default_extended_attr(domain, extended);
+       }
+
+       /* Reassign the extended pointer. */
+       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;
+       }
+
+       *blocking_timeout = ((struct lttng_channel_extended *)
+                       chan->attr.extended.ptr)->blocking_timeout;
+end:
+       return ret;
+}
+
+int lttng_channel_set_blocking_timeout(struct lttng_channel *chan,
+               int64_t blocking_timeout)
+{
+       int ret = 0;
+       int64_t msec_timeout;
+
+       if (!chan || !chan->attr.extended.ptr) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
+
+       if (blocking_timeout < 0 && blocking_timeout != -1) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
+
+       /*
+        * 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;
 }
 
 /*
@@ -1961,20 +2784,27 @@ int lttng_set_consumer_url(struct lttng_handle *handle,
        struct lttng_uri *uris = NULL;
 
        if (handle == NULL || (control_url == NULL && data_url == NULL)) {
-               return -LTTNG_ERR_INVALID;
+               ret = -LTTNG_ERR_INVALID;
+               goto error;
        }
 
        memset(&lsm, 0, sizeof(lsm));
 
        lsm.cmd_type = LTTNG_SET_CONSUMER_URI;
 
-       lttng_ctl_copy_string(lsm.session.name, handle->session_name,
+       ret = lttng_strncpy(lsm.session.name, handle->session_name,
                        sizeof(lsm.session.name));
-       lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
+       if (ret) {
+               ret = -LTTNG_ERR_INVALID;
+               goto error;
+       }
+
+       COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
 
        size = uri_parse_str_urls(control_url, data_url, &uris);
        if (size < 0) {
-               return -LTTNG_ERR_INVALID;
+               ret = -LTTNG_ERR_INVALID;
+               goto error;
        }
 
        lsm.u.uri.size = size;
@@ -1983,12 +2813,14 @@ int lttng_set_consumer_url(struct lttng_handle *handle,
                        sizeof(struct lttng_uri) * size, NULL);
 
        free(uris);
+error:
        return ret;
 }
 
 /*
  * [OBSOLETE]
  */
+int lttng_enable_consumer(struct lttng_handle *handle);
 int lttng_enable_consumer(struct lttng_handle *handle)
 {
        return -ENOSYS;
@@ -1997,77 +2829,21 @@ 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)
 {
-       int ret;
-       ssize_t size;
-       struct lttcomm_session_msg lsm;
-       struct lttng_uri *uris = NULL;
-
-       if (name == NULL || datetime == NULL) {
-               return -LTTNG_ERR_INVALID;
-       }
-
-       memset(&lsm, 0, sizeof(lsm));
-
-       lsm.cmd_type = LTTNG_CREATE_SESSION;
-       lttng_ctl_copy_string(lsm.session.name, name, sizeof(lsm.session.name));
-
-       /* There should never be a data URL. */
-       size = uri_parse_str_urls(url, NULL, &uris);
-       if (size < 0) {
-               ret = -LTTNG_ERR_INVALID;
-               goto error;
-       }
-
-       lsm.u.uri.size = size;
-
-       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;
-               }
-       }
-
-       ret = lttng_ctl_ask_sessiond_varlen_no_cmd_header(&lsm, uris,
-                       sizeof(struct lttng_uri) * size, NULL);
-
-error:
-       free(uris);
-       return ret;
+       return -ENOSYS;
 }
 
 /*
@@ -2088,8 +2864,12 @@ int lttng_data_pending(const char *session_name)
        memset(&lsm, 0, sizeof(lsm));
        lsm.cmd_type = LTTNG_DATA_PENDING;
 
-       lttng_ctl_copy_string(lsm.session.name, session_name,
+       ret = lttng_strncpy(lsm.session.name, session_name,
                        sizeof(lsm.session.name));
+       if (ret) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
 
        ret = lttng_ctl_ask_sessiond(&lsm, (void **) &pending);
        if (ret < 0) {
@@ -2098,6 +2878,10 @@ int lttng_data_pending(const char *session_name)
                /* Unexpected payload size */
                ret = -LTTNG_ERR_INVALID;
                goto end;
+       } else if (!pending) {
+               /* Internal error. */
+               ret = -LTTNG_ERR_UNK;
+               goto end;
        }
 
        ret = (int) *pending;
@@ -2107,139 +2891,484 @@ end:
 }
 
 /*
- * Create a session exclusively used for snapshot.
- *
- * Returns LTTNG_OK on success or a negative error code.
+ * Regenerate the metadata for a session.
+ * Return 0 on success, a negative error code on error.
  */
-int lttng_create_session_snapshot(const char *name, const char *snapshot_url)
+int lttng_regenerate_metadata(const char *session_name)
 {
        int ret;
-       ssize_t size;
        struct lttcomm_session_msg lsm;
-       struct lttng_uri *uris = NULL;
 
-       if (name == NULL) {
-               return -LTTNG_ERR_INVALID;
+       if (!session_name) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
        }
 
        memset(&lsm, 0, sizeof(lsm));
+       lsm.cmd_type = LTTNG_REGENERATE_METADATA;
 
-       lsm.cmd_type = LTTNG_CREATE_SESSION_SNAPSHOT;
-       lttng_ctl_copy_string(lsm.session.name, name, sizeof(lsm.session.name));
-
-       size = uri_parse_str_urls(snapshot_url, NULL, &uris);
-       if (size < 0) {
-               return -LTTNG_ERR_INVALID;
+       ret = lttng_strncpy(lsm.session.name, session_name,
+                       sizeof(lsm.session.name));
+       if (ret) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
        }
 
-       lsm.u.uri.size = size;
-
-       ret = lttng_ctl_ask_sessiond_varlen_no_cmd_header(&lsm, uris,
-                       sizeof(struct lttng_uri) * size, NULL);
+       ret = lttng_ctl_ask_sessiond(&lsm, NULL);
+       if (ret < 0) {
+               goto end;
+       }
 
-       free(uris);
+       ret = 0;
+end:
        return ret;
 }
 
 /*
- * Create a session exclusively used for live.
- *
- * Returns LTTNG_OK on success or a negative error code.
+ * Deprecated, replaced by lttng_regenerate_metadata.
  */
-int lttng_create_session_live(const char *name, const char *url,
-               unsigned int timer_interval)
+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;
-       ssize_t size;
        struct lttcomm_session_msg lsm;
-       struct lttng_uri *uris = NULL;
 
-       if (name == NULL || timer_interval == 0) {
-               return -LTTNG_ERR_INVALID;
+       if (!session_name) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
        }
 
        memset(&lsm, 0, sizeof(lsm));
+       lsm.cmd_type = LTTNG_REGENERATE_STATEDUMP;
 
-       lsm.cmd_type = LTTNG_CREATE_SESSION_LIVE;
-       lttng_ctl_copy_string(lsm.session.name, name, sizeof(lsm.session.name));
+       ret = lttng_strncpy(lsm.session.name, session_name,
+                       sizeof(lsm.session.name));
+       if (ret) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
 
-       if (url) {
-               size = uri_parse_str_urls(url, NULL, &uris);
-               if (size <= 0) {
-                       ret = -LTTNG_ERR_INVALID;
+       ret = lttng_ctl_ask_sessiond(&lsm, NULL);
+       if (ret < 0) {
+               goto end;
+       }
+
+       ret = 0;
+end:
+       return ret;
+}
+
+static
+int _lttng_register_trigger(struct lttng_trigger *trigger, const char *name,
+               bool generate_name)
+{
+       int ret;
+       struct lttcomm_session_msg lsm = {
+               .cmd_type = LTTNG_REGISTER_TRIGGER,
+               .u.trigger.is_trigger_anonymous = !name && !generate_name,
+       };
+       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,
+       };
+       const char *unused_trigger_name = NULL;
+       enum lttng_trigger_status trigger_status;
+
+       lttng_payload_init(&message);
+       lttng_payload_init(&reply);
+
+       if (!trigger) {
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
+
+       trigger_status = lttng_trigger_get_name(trigger, &unused_trigger_name);
+       if (trigger_status != LTTNG_TRIGGER_STATUS_UNSET) {
+               /* Re-using already registered trigger. */
+               ret = -LTTNG_ERR_INVALID;
+               goto end;
+       }
+
+       if (name) {
+               trigger_status = lttng_trigger_set_name(trigger, name);
+               if (trigger_status != LTTNG_TRIGGER_STATUS_OK) {
+                       ret = -LTTNG_ERR_NOMEM;
                        goto end;
                }
+       }
 
-               /* file:// is not accepted for live session. */
-               if (uris[0].dtype == LTTNG_DST_PATH) {
-                       ret = -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_unset_name;
+                       }
+               }
+       }
+
+       if (!lttng_trigger_validate(trigger)) {
+               ret = -LTTNG_ERR_INVALID_TRIGGER;
+               goto end_unset_name;
+       }
+
+       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_unset_name;
+       }
+
+       ret = lttng_trigger_serialize(trigger, &message);
+       if (ret < 0) {
+               ret = -LTTNG_ERR_UNK;
+               goto end_unset_name;
+       }
+
+       /*
+        * This is needed to populate the trigger object size for the command
+        * header.
+        */
+       message_lsm = (struct lttcomm_session_msg *) message.buffer.data;
+
+       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_unset_name;
+               }
+       }
+
+       {
+               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_INVALID_PROTOCOL;
+                       goto end_unset_name;
+               }
+       }
+
+       if (name || generate_name) {
+               ret = lttng_trigger_assign_name(trigger, reply_trigger);
+               if (ret < 0) {
+                       ret = -LTTNG_ERR_NOMEM;
                        goto end;
                }
+       }
+
+       ret = 0;
+       goto end;
+
+end_unset_name:
+       trigger_status = lttng_trigger_set_name(trigger, NULL);
+       if (trigger_status != LTTNG_TRIGGER_STATUS_OK) {
+               ret = -LTTNG_ERR_UNK;
+       }
+end:
+       lttng_payload_reset(&message);
+       lttng_payload_reset(&reply);
+       lttng_trigger_destroy(reply_trigger);
+       return ret;
+}
+
+int lttng_register_trigger(struct lttng_trigger *trigger)
+{
+       /* Register an anonymous trigger. */
+       return _lttng_register_trigger(trigger, NULL, false);
+}
+
+enum lttng_error_code lttng_register_trigger_with_name(
+               struct lttng_trigger *trigger, const char *name)
+{
+       const int ret = _lttng_register_trigger(trigger, name, false);
+
+       return ret == 0 ? LTTNG_OK : (enum lttng_error_code) -ret;
+}
+
+enum lttng_error_code lttng_register_trigger_with_automatic_name(
+               struct lttng_trigger *trigger)
+{
+       const int ret =  _lttng_register_trigger(trigger, false, true);
+
+       return ret == 0 ? LTTNG_OK : (enum lttng_error_code) -ret;
+}
+
+enum lttng_error_code lttng_error_query_execute(
+               const struct lttng_error_query *query,
+               const struct lttng_endpoint *endpoint,
+               struct lttng_error_query_results **results)
+{
+       int ret;
+       enum lttng_error_code ret_code;
+       struct lttcomm_session_msg lsm = {
+               .cmd_type = LTTNG_EXECUTE_ERROR_QUERY,
+       };
+       struct lttng_payload message;
+       struct lttng_payload reply;
+       struct lttcomm_session_msg *message_lsm;
+
+       lttng_payload_init(&message);
+       lttng_payload_init(&reply);
+
+       if (!query || !results) {
+               ret_code = LTTNG_ERR_INVALID;
+               goto end;
+       }
+
+       if (endpoint != lttng_session_daemon_command_endpoint) {
+               ret_code = LTTNG_ERR_INVALID_ERROR_QUERY_TARGET;
+               goto end;
+       }
+
+       ret = lttng_dynamic_buffer_append(&message.buffer, &lsm, sizeof(lsm));
+       if (ret) {
+               ret_code = LTTNG_ERR_NOMEM;
+               goto end;
+       }
+
+       ret = lttng_error_query_serialize(query, &message);
+       if (ret) {
+               ret_code = LTTNG_ERR_UNK;
+               goto end;
+       }
+
+       message_lsm = (struct lttcomm_session_msg *) message.buffer.data;
+       message_lsm->u.error_query.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) {
+                       ret_code = -ret;
+                       goto end;
+               }
+       }
+
+       {
+               ssize_t reply_create_ret;
+               struct lttng_payload_view reply_view =
+                               lttng_payload_view_from_payload(
+                                               &reply, 0, reply.buffer.size);
+
+               reply_create_ret = lttng_error_query_results_create_from_payload(
+                               &reply_view, results);
+               if (reply_create_ret < 0) {
+                       ret_code = LTTNG_ERR_INVALID_PROTOCOL;
+                       goto end;
+               }
+       }
+
+       ret_code = LTTNG_OK;
+end:
+       lttng_payload_reset(&message);
+       lttng_payload_reset(&reply);
+       return ret_code;
+}
+
+int lttng_unregister_trigger(const struct lttng_trigger *trigger)
+{
+       int ret;
+       struct lttcomm_session_msg lsm;
+       struct lttcomm_session_msg *message_lsm;
+       struct lttng_payload message;
+       struct lttng_payload reply;
+       struct lttng_trigger *copy = NULL;
+       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;
+       }
+
+       copy = lttng_trigger_copy(trigger);
+       if (!copy) {
+               ret = -LTTNG_ERR_UNK;
+               goto end;
+       }
+
+       if (!copy->creds.uid.is_set) {
+               /* Use the client credentials as the trigger credentials */
+               lttng_trigger_set_credentials(copy, &user_creds);
        } else {
-               size = 0;
+               /*
+                * 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(copy);
+               if (!lttng_credentials_is_equal_uid(trigger_creds, &user_creds)) {
+                       if (lttng_credentials_get_uid(&user_creds) != 0) {
+                               ret = -LTTNG_ERR_EPERM;
+                               goto end;
+                       }
+               }
        }
 
-       lsm.u.session_live.nb_uri = size;
-       lsm.u.session_live.timer_interval = timer_interval;
+       if (!lttng_trigger_validate(copy)) {
+               ret = -LTTNG_ERR_INVALID_TRIGGER;
+               goto end;
+       }
 
-       ret = lttng_ctl_ask_sessiond_varlen_no_cmd_header(&lsm, uris,
-                       sizeof(struct lttng_uri) * size, NULL);
+       memset(&lsm, 0, sizeof(lsm));
+       lsm.cmd_type = LTTNG_UNREGISTER_TRIGGER;
+
+       ret = lttng_dynamic_buffer_append(&message.buffer, &lsm, sizeof(lsm));
+       if (ret) {
+               ret = -LTTNG_ERR_NOMEM;
+               goto end;
+       }
+
+       ret = lttng_trigger_serialize(copy, &message);
+       if (ret < 0) {
+               ret = -LTTNG_ERR_UNK;
+               goto end;
+       }
 
+       /*
+        * 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;
+
+       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);
+
+               /*
+                * 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:
-       free(uris);
+       lttng_trigger_destroy(copy);
+       lttng_payload_reset(&message);
+       lttng_payload_reset(&reply);
        return ret;
 }
 
 /*
- * List PIDs in the tracker.
- *
- * enabled is set to whether the PID tracker is enabled.
- * pids is set to an allocated array of PIDs currently tracked. On
- * success, pids must be freed by the caller.
- * nr_pids is set to the number of entries contained by the pids array.
+ * Ask the session daemon for all registered triggers for the current user.
  *
- * Returns 0 on success, else a negative LTTng error code.
+ * Allocates and return an lttng_triggers set.
+ * On error, returns a suitable lttng_error_code.
  */
-int lttng_list_tracker_pids(struct lttng_handle *handle,
-               int *_enabled, int32_t **_pids, size_t *_nr_pids)
+enum lttng_error_code lttng_list_triggers(struct lttng_triggers **triggers)
 {
        int ret;
-       int enabled = 1;
-       struct lttcomm_session_msg lsm;
-       size_t nr_pids;
-       int32_t *pids;
+       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));
 
-       if (handle == NULL) {
-               return -LTTNG_ERR_INVALID;
-       }
-
-       memset(&lsm, 0, sizeof(lsm));
-       lsm.cmd_type = LTTNG_LIST_TRACKER_PIDS;
-       lttng_ctl_copy_string(lsm.session.name, handle->session_name,
-                       sizeof(lsm.session.name));
-       lttng_ctl_copy_lttng_domain(&lsm.domain, &handle->domain);
+       lttng_payload_init(&reply);
 
-       ret = lttng_ctl_ask_sessiond(&lsm, (void **) &pids);
+       ret = lttng_ctl_ask_sessiond_payload(&lsm_view, &reply);
        if (ret < 0) {
-               return ret;
+               ret_code = (enum lttng_error_code) -ret;
+               goto end;
        }
-       nr_pids = ret / sizeof(int32_t);
-       if (nr_pids == 1 && pids[0] == -1) {
-               free(pids);
-               pids = NULL;
-               enabled = 0;
-               nr_pids = 0;
+
+       {
+               struct lttng_payload_view reply_view =
+                               lttng_payload_view_from_payload(
+                                               &reply, 0, reply.buffer.size);
+
+               ret = lttng_triggers_create_from_payload(
+                               &reply_view, &local_triggers);
+               if (ret < 0) {
+                       ret_code = LTTNG_ERR_FATAL;
+                       goto end;
+               }
        }
-       *_enabled = enabled;
-       *_pids = pids;
-       *_nr_pids = nr_pids;
-       return 0;
+
+       *triggers = local_triggers;
+       local_triggers = NULL;
+end:
+       lttng_payload_reset(&reply);
+       lttng_triggers_destroy(local_triggers);
+       return ret_code;
 }
 
 /*
  * lib constructor.
  */
-static void __attribute__((constructor)) init()
+static void __attribute__((constructor)) init(void)
 {
        /* Set default session group */
        lttng_set_tracing_group(DEFAULT_TRACING_GROUP);
@@ -2248,7 +3377,7 @@ static void __attribute__((constructor)) init()
 /*
  * lib destructor.
  */
-static void __attribute__((destructor)) lttng_ctl_exit()
+static void __attribute__((destructor)) lttng_ctl_exit(void)
 {
        free(tracing_group);
 }
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