src/lib/lttng-ctl/lttng-ctl.c

   1 /*
   2  * lttng-ctl.c
   3  *
   4  * Linux Trace Toolkit Control Library
   5  *
   6  * Copyright (C) 2011 EfficiOS Inc.
   7  * Copyright (C) 2016 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   8  *
   9  * SPDX-License-Identifier: LGPL-2.1-only
  10  *
  11  */
  12
  13 #define _LGPL_SOURCE
  14 #include <assert.h>
  15 #include <grp.h>
  16 #include <errno.h>
  17 #include <stdio.h>
  18 #include <stdlib.h>
  19 #include <stdint.h>
  20 #include <string.h>
  21 #include <unistd.h>
  22
  23 #include <common/buffer-view.h>
  24 #include <common/common.h>
  25 #include <common/compat/string.h>
  26 #include <common/defaults.h>
  27 #include <common/dynamic-array.h>
  28 #include <common/dynamic-buffer.h>
  29 #include <common/macros.h>
  30 #include <common/sessiond-comm/sessiond-comm.h>
  31 #include <common/tracker.h>
  32 #include <common/uri.h>
  33 #include <common/utils.h>
  34 #include <lttng/channel-internal.h>
  35 #include <lttng/destruction-handle.h>
  36 #include <lttng/endpoint.h>
  37 #include <lttng/event-internal.h>
  38 #include <lttng/health-internal.h>
  39 #include <lttng/lttng.h>
  40 #include <lttng/session-descriptor-internal.h>
  41 #include <lttng/session-internal.h>
  42 #include <lttng/trigger/trigger-internal.h>
  43 #include <lttng/userspace-probe-internal.h>
  44
  45 #include "filter/filter-ast.h"
  46 #include "filter/filter-parser.h"
  47 #include "filter/filter-bytecode.h"
  48 #include "filter/memstream.h"
  49 #include "lttng-ctl-helper.h"
  50
  51 #ifdef DEBUG
  52 static const int print_xml = 1;
  53 #define dbg_printf(fmt, args...)        \
  54         printf("[debug liblttng-ctl] " fmt, ## args)
  55 #else
  56 static const int print_xml = 0;
  57 #define dbg_printf(fmt, args...)                                \
  58 do {                                                            \
  59         /* do nothing but check printf format */                \
  60         if (0)                                                  \
  61                 printf("[debug liblttnctl] " fmt, ## args);     \
  62 } while (0)
  63 #endif
  64
  65 #define COPY_DOMAIN_PACKED(dst, src)                            \
  66 do {                                                            \
  67         struct lttng_domain _tmp_domain;                        \
  68                                                                 \
  69         lttng_ctl_copy_lttng_domain(&_tmp_domain, &src);        \
  70         dst = _tmp_domain;                                      \
  71 } while (0)
  72
  73 /* Socket to session daemon for communication */
  74 static int sessiond_socket = -1;
  75 static char sessiond_sock_path[PATH_MAX];
  76
  77 /* Variables */
  78 static char *tracing_group;
  79 static int connected;
  80
  81 /* Global */
  82
  83 /*
  84  * Those two variables are used by error.h to silent or control the verbosity of
  85  * error message. They are global to the library so application linking with it
  86  * are able to compile correctly and also control verbosity of the library.
  87  */
  88 int lttng_opt_quiet;
  89 int lttng_opt_verbose;
  90 int lttng_opt_mi;
  91
  92 /*
  93  * Copy domain to lttcomm_session_msg domain.
  94  *
  95  * If domain is unknown, default domain will be the kernel.
  96  */
  97 LTTNG_HIDDEN
  98 void lttng_ctl_copy_lttng_domain(struct lttng_domain *dst,
  99                 struct lttng_domain *src)
 100 {
 101         if (src && dst) {
 102                 switch (src->type) {
 103                 case LTTNG_DOMAIN_KERNEL:
 104                 case LTTNG_DOMAIN_UST:
 105                 case LTTNG_DOMAIN_JUL:
 106                 case LTTNG_DOMAIN_LOG4J:
 107                 case LTTNG_DOMAIN_PYTHON:
 108                         memcpy(dst, src, sizeof(struct lttng_domain));
 109                         break;
 110                 default:
 111                         memset(dst, 0, sizeof(struct lttng_domain));
 112                         break;
 113                 }
 114         }
 115 }
 116
 117 /*
 118  * Send lttcomm_session_msg to the session daemon.
 119  *
 120  * On success, returns the number of bytes sent (>=0)
 121  * On error, returns -1
 122  */
 123 static int send_session_msg(struct lttcomm_session_msg *lsm)
 124 {
 125         int ret;
 126
 127         if (!connected) {
 128                 ret = -LTTNG_ERR_NO_SESSIOND;
 129                 goto end;
 130         }
 131
 132         DBG("LSM cmd type : %d", lsm->cmd_type);
 133
 134         ret = lttcomm_send_creds_unix_sock(sessiond_socket, lsm,
 135                         sizeof(struct lttcomm_session_msg));
 136         if (ret < 0) {
 137                 ret = -LTTNG_ERR_FATAL;
 138         }
 139
 140 end:
 141         return ret;
 142 }
 143
 144 /*
 145  * Send var len data to the session daemon.
 146  *
 147  * On success, returns the number of bytes sent (>=0)
 148  * On error, returns -1
 149  */
 150 static int send_session_varlen(const void *data, size_t len)
 151 {
 152         int ret;
 153
 154         if (!connected) {
 155                 ret = -LTTNG_ERR_NO_SESSIOND;
 156                 goto end;
 157         }
 158
 159         if (!data || !len) {
 160                 ret = 0;
 161                 goto end;
 162         }
 163
 164         ret = lttcomm_send_unix_sock(sessiond_socket, data, len);
 165         if (ret < 0) {
 166                 ret = -LTTNG_ERR_FATAL;
 167         }
 168
 169 end:
 170         return ret;
 171 }
 172
 173 /*
 174  * Send file descriptors to the session daemon.
 175  *
 176  * On success, returns the number of bytes sent (>=0)
 177  * On error, returns -1
 178  */
 179 static int send_session_fds(const int *fds, size_t nb_fd)
 180 {
 181         int ret;
 182
 183         if (!connected) {
 184                 ret = -LTTNG_ERR_NO_SESSIOND;
 185                 goto end;
 186         }
 187
 188         if (!fds || !nb_fd) {
 189                 ret = 0;
 190                 goto end;
 191         }
 192
 193         ret = lttcomm_send_fds_unix_sock(sessiond_socket, fds, nb_fd);
 194         if (ret < 0) {
 195                 ret = -LTTNG_ERR_FATAL;
 196         }
 197
 198 end:
 199         return ret;
 200 }
 201
 202 /*
 203  * Receive data from the sessiond socket.
 204  *
 205  * On success, returns the number of bytes received (>=0)
 206  * On error, returns -1 (recvmsg() error) or -ENOTCONN
 207  */
 208 static int recv_data_sessiond(void *buf, size_t len)
 209 {
 210         int ret;
 211
 212         if (!connected) {
 213                 ret = -LTTNG_ERR_NO_SESSIOND;
 214                 goto end;
 215         }
 216
 217         ret = lttcomm_recv_unix_sock(sessiond_socket, buf, len);
 218         if (ret < 0) {
 219                 ret = -LTTNG_ERR_FATAL;
 220         }
 221
 222 end:
 223         return ret;
 224 }
 225
 226 /*
 227  * Check if we are in the specified group.
 228  *
 229  * If yes return 1, else return -1.
 230  */
 231 LTTNG_HIDDEN
 232 int lttng_check_tracing_group(void)
 233 {
 234         gid_t *grp_list, tracing_gid;
 235         int grp_list_size, grp_id, i;
 236         int ret = -1;
 237         const char *grp_name = tracing_group;
 238
 239         /* Get GID of group 'tracing' */
 240         if (utils_get_group_id(grp_name, false, &tracing_gid)) {
 241                 /* If grp_tracing is NULL, the group does not exist. */
 242                 goto end;
 243         }
 244
 245         /* Get number of supplementary group IDs */
 246         grp_list_size = getgroups(0, NULL);
 247         if (grp_list_size < 0) {
 248                 PERROR("getgroups");
 249                 goto end;
 250         }
 251
 252         /* Alloc group list of the right size */
 253         grp_list = zmalloc(grp_list_size * sizeof(gid_t));
 254         if (!grp_list) {
 255                 PERROR("malloc");
 256                 goto end;
 257         }
 258         grp_id = getgroups(grp_list_size, grp_list);
 259         if (grp_id < 0) {
 260                 PERROR("getgroups");
 261                 goto free_list;
 262         }
 263
 264         for (i = 0; i < grp_list_size; i++) {
 265                 if (grp_list[i] == tracing_gid) {
 266                         ret = 1;
 267                         break;
 268                 }
 269         }
 270
 271 free_list:
 272         free(grp_list);
 273
 274 end:
 275         return ret;
 276 }
 277
 278 static enum lttng_error_code check_enough_available_memory(
 279                 uint64_t num_bytes_requested_per_cpu)
 280 {
 281         int ret;
 282         long num_cpu;
 283         uint64_t best_mem_info;
 284         uint64_t num_bytes_requested_total;
 285
 286         /*
 287          * Get the number of CPU currently online to compute the amount of
 288          * memory needed to create a buffer for every CPU.
 289          */
 290         num_cpu = sysconf(_SC_NPROCESSORS_ONLN);
 291         if (num_cpu == -1) {
 292                 ret = LTTNG_ERR_FATAL;
 293                 goto end;
 294         }
 295
 296         if (num_bytes_requested_per_cpu > UINT64_MAX / (uint64_t) num_cpu) {
 297                 /* Overflow */
 298                 ret = LTTNG_ERR_OVERFLOW;
 299                 goto end;
 300         }
 301
 302         num_bytes_requested_total =
 303                         num_bytes_requested_per_cpu * (uint64_t) num_cpu;
 304
 305         /*
 306          * Try to get the `MemAvail` field of `/proc/meminfo`. This is the most
 307          * reliable estimate we can get but it is only exposed by the kernel
 308          * since 3.14. (See Linux kernel commit:
 309          * 34e431b0ae398fc54ea69ff85ec700722c9da773)
 310          */
 311         ret = utils_get_memory_available(&best_mem_info);
 312         if (ret >= 0) {
 313                 goto success;
 314         }
 315
 316         /*
 317          * As a backup plan, use `MemTotal` field of `/proc/meminfo`. This
 318          * is a sanity check for obvious user error.
 319          */
 320         ret = utils_get_memory_total(&best_mem_info);
 321         if (ret >= 0) {
 322                 goto success;
 323         }
 324
 325         /* No valid source of information. */
 326         ret = LTTNG_ERR_NOMEM;
 327         goto end;
 328
 329 success:
 330         if (best_mem_info >= num_bytes_requested_total) {
 331                 ret = LTTNG_OK;
 332         } else {
 333                 ret = LTTNG_ERR_NOMEM;
 334         }
 335 end:
 336         return ret;
 337 }
 338
 339 /*
 340  * Try connect to session daemon with sock_path.
 341  *
 342  * Return 0 on success, else -1
 343  */
 344 static int try_connect_sessiond(const char *sock_path)
 345 {
 346         int ret;
 347
 348         /* If socket exist, we check if the daemon listens for connect. */
 349         ret = access(sock_path, F_OK);
 350         if (ret < 0) {
 351                 /* Not alive */
 352                 goto error;
 353         }
 354
 355         ret = lttcomm_connect_unix_sock(sock_path);
 356         if (ret < 0) {
 357                 /* Not alive. */
 358                 goto error;
 359         }
 360
 361         ret = lttcomm_close_unix_sock(ret);
 362         if (ret < 0) {
 363                 PERROR("lttcomm_close_unix_sock");
 364         }
 365
 366         return 0;
 367
 368 error:
 369         return -1;
 370 }
 371
 372 /*
 373  * Set sessiond socket path by putting it in the global sessiond_sock_path
 374  * variable.
 375  *
 376  * Returns 0 on success, negative value on failure (the sessiond socket path
 377  * is somehow too long or ENOMEM).
 378  */
 379 static int set_session_daemon_path(void)
 380 {
 381         int in_tgroup = 0;      /* In tracing group. */
 382         uid_t uid;
 383
 384         uid = getuid();
 385
 386         if (uid != 0) {
 387                 /* Are we in the tracing group ? */
 388                 in_tgroup = lttng_check_tracing_group();
 389         }
 390
 391         if ((uid == 0) || in_tgroup == 1) {
 392                 const int ret = lttng_strncpy(sessiond_sock_path,
 393                                 DEFAULT_GLOBAL_CLIENT_UNIX_SOCK,
 394                                 sizeof(sessiond_sock_path));
 395
 396                 if (ret) {
 397                         goto error;
 398                 }
 399         }
 400
 401         if (uid != 0) {
 402                 int ret;
 403
 404                 if (in_tgroup) {
 405                         /* Tracing group. */
 406                         ret = try_connect_sessiond(sessiond_sock_path);
 407                         if (ret >= 0) {
 408                                 goto end;
 409                         }
 410                         /* Global session daemon not available... */
 411                 }
 412                 /* ...or not in tracing group (and not root), default */
 413
 414                 /*
 415                  * With GNU C <  2.1, snprintf returns -1 if the target buffer
 416                  * is too small;
 417                  * With GNU C >= 2.1, snprintf returns the required size
 418                  * (excluding closing null)
 419                  */
 420                 ret = snprintf(sessiond_sock_path, sizeof(sessiond_sock_path),
 421                                 DEFAULT_HOME_CLIENT_UNIX_SOCK, utils_get_home_dir());
 422                 if ((ret < 0) || (ret >= sizeof(sessiond_sock_path))) {
 423                         goto error;
 424                 }
 425         }
 426 end:
 427         return 0;
 428
 429 error:
 430         return -1;
 431 }
 432
 433 /*
 434  * Connect to the LTTng session daemon.
 435  *
 436  * On success, return the socket's file descriptor. On error, return -1.
 437  */
 438 LTTNG_HIDDEN int connect_sessiond(void)
 439 {
 440         int ret;
 441
 442         ret = set_session_daemon_path();
 443         if (ret < 0) {
 444                 goto error;
 445         }
 446
 447         /* Connect to the sesssion daemon. */
 448         ret = lttcomm_connect_unix_sock(sessiond_sock_path);
 449         if (ret < 0) {
 450                 goto error;
 451         }
 452
 453         return ret;
 454
 455 error:
 456         return -1;
 457 }
 458
 459 static void reset_global_sessiond_connection_state(void)
 460 {
 461         sessiond_socket = -1;
 462         connected = 0;
 463 }
 464
 465 /*
 466  *  Clean disconnect from the session daemon.
 467  *
 468  *  On success, return 0. On error, return -1.
 469  */
 470 static int disconnect_sessiond(void)
 471 {
 472         int ret = 0;
 473
 474         if (connected) {
 475                 ret = lttcomm_close_unix_sock(sessiond_socket);
 476                 reset_global_sessiond_connection_state();
 477         }
 478
 479         return ret;
 480 }
 481
 482 static int recv_sessiond_optional_data(size_t len, void **user_buf,
 483         size_t *user_len)
 484 {
 485         int ret = 0;
 486         void *buf = NULL;
 487
 488         if (len) {
 489                 if (!user_len) {
 490                         ret = -LTTNG_ERR_INVALID;
 491                         goto end;
 492                 }
 493
 494                 buf = zmalloc(len);
 495                 if (!buf) {
 496                         ret = -ENOMEM;
 497                         goto end;
 498                 }
 499
 500                 ret = recv_data_sessiond(buf, len);
 501                 if (ret < 0) {
 502                         goto end;
 503                 }
 504
 505                 if (!user_buf) {
 506                         ret = -LTTNG_ERR_INVALID;
 507                         goto end;
 508                 }
 509
 510                 /* Move ownership of command header buffer to user. */
 511                 *user_buf = buf;
 512                 buf = NULL;
 513                 *user_len = len;
 514         } else {
 515                 /* No command header. */
 516                 if (user_len) {
 517                         *user_len = 0;
 518                 }
 519
 520                 if (user_buf) {
 521                         *user_buf = NULL;
 522                 }
 523         }
 524
 525 end:
 526         free(buf);
 527         return ret;
 528 }
 529
 530 /*
 531  * Ask the session daemon a specific command and put the data into buf.
 532  * Takes extra var. len. data and file descriptors as input to send to the
 533  * session daemon.
 534  *
 535  * Return size of data (only payload, not header) or a negative error code.
 536  */
 537 LTTNG_HIDDEN
 538 int lttng_ctl_ask_sessiond_fds_varlen(struct lttcomm_session_msg *lsm,
 539                 const int *fds, size_t nb_fd, const void *vardata,
 540                 size_t vardata_len, void **user_payload_buf,
 541                 void **user_cmd_header_buf, size_t *user_cmd_header_len)
 542 {
 543         int ret;
 544         size_t payload_len;
 545         struct lttcomm_lttng_msg llm;
 546
 547         ret = connect_sessiond();
 548         if (ret < 0) {
 549                 ret = -LTTNG_ERR_NO_SESSIOND;
 550                 goto end;
 551         } else {
 552                 sessiond_socket = ret;
 553                 connected = 1;
 554         }
 555
 556         /* Send command to session daemon */
 557         ret = send_session_msg(lsm);
 558         if (ret < 0) {
 559                 /* Ret value is a valid lttng error code. */
 560                 goto end;
 561         }
 562         /* Send var len data */
 563         ret = send_session_varlen(vardata, vardata_len);
 564         if (ret < 0) {
 565                 /* Ret value is a valid lttng error code. */
 566                 goto end;
 567         }
 568
 569         /* Send fds */
 570         ret = send_session_fds(fds, nb_fd);
 571         if (ret < 0) {
 572                 /* Ret value is a valid lttng error code. */
 573                 goto end;
 574         }
 575
 576         /* Get header from data transmission */
 577         ret = recv_data_sessiond(&llm, sizeof(llm));
 578         if (ret < 0) {
 579                 /* Ret value is a valid lttng error code. */
 580                 goto end;
 581         }
 582
 583         /* Check error code if OK */
 584         if (llm.ret_code != LTTNG_OK) {
 585                 ret = -llm.ret_code;
 586                 goto end;
 587         }
 588
 589         /* Get command header from data transmission */
 590         ret = recv_sessiond_optional_data(llm.cmd_header_size,
 591                 user_cmd_header_buf, user_cmd_header_len);
 592         if (ret < 0) {
 593                 goto end;
 594         }
 595
 596         /* Get payload from data transmission */
 597         ret = recv_sessiond_optional_data(llm.data_size, user_payload_buf,
 598                 &payload_len);
 599         if (ret < 0) {
 600                 goto end;
 601         }
 602
 603         ret = llm.data_size;
 604
 605 end:
 606         disconnect_sessiond();
 607         return ret;
 608 }
 609
 610 /*
 611  * Create lttng handle and return pointer.
 612  *
 613  * The returned pointer will be NULL in case of malloc() error.
 614  */
 615 struct lttng_handle *lttng_create_handle(const char *session_name,
 616                 struct lttng_domain *domain)
 617 {
 618         int ret;
 619         struct lttng_handle *handle = NULL;
 620
 621         handle = zmalloc(sizeof(struct lttng_handle));
 622         if (handle == NULL) {
 623                 PERROR("malloc handle");
 624                 goto end;
 625         }
 626
 627         /* Copy session name */
 628         ret = lttng_strncpy(handle->session_name, session_name ? : "",
 629                             sizeof(handle->session_name));
 630         if (ret) {
 631                 goto error;
 632         }
 633
 634         /* Copy lttng domain or leave initialized to 0. */
 635         if (domain) {
 636                 lttng_ctl_copy_lttng_domain(&handle->domain, domain);
 637         }
 638
 639 end:
 640         return handle;
 641 error:
 642         free(handle);
 643         return NULL;
 644 }
 645
 646 /*
 647  * Destroy handle by free(3) the pointer.
 648  */
 649 void lttng_destroy_handle(struct lttng_handle *handle)
 650 {
 651         free(handle);
 652 }
 653
 654 /*
 655  * Register an outside consumer.
 656  *
 657  * Returns size of returned session payload data or a negative error code.
 658  */
 659 int lttng_register_consumer(struct lttng_handle *handle,
 660                 const char *socket_path)
 661 {
 662         int ret;
 663         struct lttcomm_session_msg lsm;
 664
 665         if (handle == NULL || socket_path == NULL) {
 666                 ret = -LTTNG_ERR_INVALID;
 667                 goto end;
 668         }
 669
 670         memset(&lsm, 0, sizeof(lsm));
 671         lsm.cmd_type = LTTNG_REGISTER_CONSUMER;
 672         ret = lttng_strncpy(lsm.session.name, handle->session_name,
 673                         sizeof(lsm.session.name));
 674         if (ret) {
 675                 ret = -LTTNG_ERR_INVALID;
 676                 goto end;
 677         }
 678
 679         COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
 680
 681         ret = lttng_strncpy(lsm.u.reg.path, socket_path,
 682                             sizeof(lsm.u.reg.path));
 683         if (ret) {
 684                 ret = -LTTNG_ERR_INVALID;
 685                 goto end;
 686         }
 687
 688         ret = lttng_ctl_ask_sessiond(&lsm, NULL);
 689 end:
 690         return ret;
 691 }
 692
 693 /*
 694  * Start tracing for all traces of the session.
 695  *
 696  * Returns size of returned session payload data or a negative error code.
 697  */
 698 int lttng_start_tracing(const char *session_name)
 699 {
 700         int ret;
 701         struct lttcomm_session_msg lsm;
 702
 703         if (session_name == NULL) {
 704                 ret = -LTTNG_ERR_INVALID;
 705                 goto end;
 706         }
 707
 708         memset(&lsm, 0, sizeof(lsm));
 709         lsm.cmd_type = LTTNG_START_TRACE;
 710
 711         ret = lttng_strncpy(lsm.session.name, session_name,
 712                             sizeof(lsm.session.name));
 713         if (ret) {
 714                 ret = -LTTNG_ERR_INVALID;
 715                 goto end;
 716         }
 717
 718         ret = lttng_ctl_ask_sessiond(&lsm, NULL);
 719 end:
 720         return ret;
 721 }
 722
 723 /*
 724  * Stop tracing for all traces of the session.
 725  */
 726 static int _lttng_stop_tracing(const char *session_name, int wait)
 727 {
 728         int ret, data_ret;
 729         struct lttcomm_session_msg lsm;
 730
 731         if (session_name == NULL) {
 732                 ret = -LTTNG_ERR_INVALID;
 733                 goto error;
 734         }
 735
 736         memset(&lsm, 0, sizeof(lsm));
 737         lsm.cmd_type = LTTNG_STOP_TRACE;
 738
 739         ret = lttng_strncpy(lsm.session.name, session_name,
 740                             sizeof(lsm.session.name));
 741         if (ret) {
 742                 ret = -LTTNG_ERR_INVALID;
 743                 goto error;
 744         }
 745
 746         ret = lttng_ctl_ask_sessiond(&lsm, NULL);
 747         if (ret < 0 && ret != -LTTNG_ERR_TRACE_ALREADY_STOPPED) {
 748                 goto error;
 749         }
 750
 751         if (!wait) {
 752                 goto end;
 753         }
 754
 755         /* Check for data availability */
 756         do {
 757                 data_ret = lttng_data_pending(session_name);
 758                 if (data_ret < 0) {
 759                         /* Return the data available call error. */
 760                         ret = data_ret;
 761                         goto error;
 762                 }
 763
 764                 /*
 765                  * Data sleep time before retrying (in usec). Don't sleep if the
 766                  * call returned value indicates availability.
 767                  */
 768                 if (data_ret) {
 769                         usleep(DEFAULT_DATA_AVAILABILITY_WAIT_TIME_US);
 770                 }
 771         } while (data_ret != 0);
 772
 773 end:
 774 error:
 775         return ret;
 776 }
 777
 778 /*
 779  * Stop tracing and wait for data availability.
 780  */
 781 int lttng_stop_tracing(const char *session_name)
 782 {
 783         return _lttng_stop_tracing(session_name, 1);
 784 }
 785
 786 /*
 787  * Stop tracing but _don't_ wait for data availability.
 788  */
 789 int lttng_stop_tracing_no_wait(const char *session_name)
 790 {
 791         return _lttng_stop_tracing(session_name, 0);
 792 }
 793
 794 /*
 795  * Add context to a channel.
 796  *
 797  * If the given channel is NULL, add the contexts to all channels.
 798  * The event_name param is ignored.
 799  *
 800  * Returns the size of the returned payload data or a negative error code.
 801  */
 802 int lttng_add_context(struct lttng_handle *handle,
 803                 struct lttng_event_context *ctx, const char *event_name,
 804                 const char *channel_name)
 805 {
 806         int ret;
 807         struct lttcomm_session_msg lsm;
 808         struct lttng_dynamic_buffer buffer;
 809
 810         lttng_dynamic_buffer_init(&buffer);
 811
 812         /* Safety check. Both are mandatory. */
 813         if (handle == NULL || ctx == NULL) {
 814                 ret = -LTTNG_ERR_INVALID;
 815                 goto end;
 816         }
 817
 818         memset(&lsm, 0, sizeof(lsm));
 819         lsm.cmd_type = LTTNG_ADD_CONTEXT;
 820
 821         /* If no channel name, send empty string. */
 822         ret = lttng_strncpy(lsm.u.context.channel_name, channel_name ?: "",
 823                         sizeof(lsm.u.context.channel_name));
 824         if (ret) {
 825                 ret = -LTTNG_ERR_INVALID;
 826                 goto end;
 827         }
 828
 829         COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
 830         ret = lttng_strncpy(lsm.session.name, handle->session_name,
 831                         sizeof(lsm.session.name));
 832         if (ret) {
 833                 ret = -LTTNG_ERR_INVALID;
 834                 goto end;
 835         }
 836
 837         ret = lttng_event_context_serialize(ctx, &buffer);
 838         if (ret) {
 839                 ret = -LTTNG_ERR_INVALID;
 840                 goto end;
 841         }
 842
 843         lsm.u.context.length = buffer.size;
 844
 845         ret = lttng_ctl_ask_sessiond_varlen_no_cmd_header(
 846                         &lsm, buffer.data, buffer.size, NULL);
 847 end:
 848         lttng_dynamic_buffer_reset(&buffer);
 849         return ret;
 850 }
 851
 852 /*
 853  * Enable event(s) for a channel.
 854  *
 855  * If no event name is specified, all events are enabled.
 856  * If no channel name is specified, the default 'channel0' is used.
 857  *
 858  * Returns size of returned session payload data or a negative error code.
 859  */
 860 int lttng_enable_event(struct lttng_handle *handle,
 861                 struct lttng_event *ev, const char *channel_name)
 862 {
 863         return lttng_enable_event_with_exclusions(handle, ev, channel_name,
 864                         NULL, 0, NULL);
 865 }
 866
 867 /*
 868  * Create or enable an event with a filter expression.
 869  *
 870  * Return negative error value on error.
 871  * Return size of returned session payload data if OK.
 872  */
 873 int lttng_enable_event_with_filter(struct lttng_handle *handle,
 874                 struct lttng_event *event, const char *channel_name,
 875                 const char *filter_expression)
 876 {
 877         return lttng_enable_event_with_exclusions(handle, event, channel_name,
 878                         filter_expression, 0, NULL);
 879 }
 880
 881 /*
 882  * Depending on the event, return a newly allocated agent filter expression or
 883  * NULL if not applicable.
 884  *
 885  * An event with NO loglevel and the name is * will return NULL.
 886  */
 887 static char *set_agent_filter(const char *filter, struct lttng_event *ev)
 888 {
 889         int err;
 890         char *agent_filter = NULL;
 891
 892         assert(ev);
 893
 894         /* Don't add filter for the '*' event. */
 895         if (strcmp(ev->name, "*") != 0) {
 896                 if (filter) {
 897                         err = asprintf(&agent_filter, "(%s) && (logger_name == \"%s\")", filter,
 898                                         ev->name);
 899                 } else {
 900                         err = asprintf(&agent_filter, "logger_name == \"%s\"", ev->name);
 901                 }
 902                 if (err < 0) {
 903                         PERROR("asprintf");
 904                         goto error;
 905                 }
 906         }
 907
 908         /* Add loglevel filtering if any for the JUL domain. */
 909         if (ev->loglevel_type != LTTNG_EVENT_LOGLEVEL_ALL) {
 910                 const char *op;
 911
 912                 if (ev->loglevel_type == LTTNG_EVENT_LOGLEVEL_RANGE) {
 913                         op = ">=";
 914                 } else {
 915                         op = "==";
 916                 }
 917
 918                 if (filter || agent_filter) {
 919                         char *new_filter;
 920
 921                         err = asprintf(&new_filter, "(%s) && (int_loglevel %s %d)",
 922                                         agent_filter ? agent_filter : filter, op,
 923                                         ev->loglevel);
 924                         if (agent_filter) {
 925                                 free(agent_filter);
 926                         }
 927                         agent_filter = new_filter;
 928                 } else {
 929                         err = asprintf(&agent_filter, "int_loglevel %s %d", op,
 930                                         ev->loglevel);
 931                 }
 932                 if (err < 0) {
 933                         PERROR("asprintf");
 934                         goto error;
 935                 }
 936         }
 937
 938         return agent_filter;
 939 error:
 940         free(agent_filter);
 941         return NULL;
 942 }
 943
 944 /*
 945  * Generate the filter bytecode from a given filter expression string. Put the
 946  * newly allocated parser context in ctxp and populate the lsm object with the
 947  * expression len.
 948  *
 949  * Return 0 on success else a LTTNG_ERR_* code and ctxp is untouched.
 950  */
 951 static int generate_filter(char *filter_expression,
 952                 size_t *bytecode_len,
 953                 struct filter_parser_ctx **ctxp)
 954 {
 955         int ret;
 956         struct filter_parser_ctx *ctx = NULL;
 957         FILE *fmem = NULL;
 958
 959         assert(filter_expression);
 960         assert(ctxp);
 961
 962         /*
 963          * Casting const to non-const, as the underlying function will use it in
 964          * read-only mode.
 965          */
 966         fmem = lttng_fmemopen((void *) filter_expression,
 967                         strlen(filter_expression), "r");
 968         if (!fmem) {
 969                 fprintf(stderr, "Error opening memory as stream\n");
 970                 ret = -LTTNG_ERR_FILTER_NOMEM;
 971                 goto error;
 972         }
 973         ctx = filter_parser_ctx_alloc(fmem);
 974         if (!ctx) {
 975                 fprintf(stderr, "Error allocating parser\n");
 976                 ret = -LTTNG_ERR_FILTER_NOMEM;
 977                 goto filter_alloc_error;
 978         }
 979         ret = filter_parser_ctx_append_ast(ctx);
 980         if (ret) {
 981                 fprintf(stderr, "Parse error\n");
 982                 ret = -LTTNG_ERR_FILTER_INVAL;
 983                 goto parse_error;
 984         }
 985         if (print_xml) {
 986                 ret = filter_visitor_print_xml(ctx, stdout, 0);
 987                 if (ret) {
 988                         fflush(stdout);
 989                         fprintf(stderr, "XML print error\n");
 990                         ret = -LTTNG_ERR_FILTER_INVAL;
 991                         goto parse_error;
 992                 }
 993         }
 994
 995         dbg_printf("Generating IR... ");
 996         fflush(stdout);
 997         ret = filter_visitor_ir_generate(ctx);
 998         if (ret) {
 999                 fprintf(stderr, "Generate IR error\n");
1000                 ret = -LTTNG_ERR_FILTER_INVAL;
1001                 goto parse_error;
1002         }
1003         dbg_printf("done\n");
1004
1005         dbg_printf("Validating IR... ");
1006         fflush(stdout);
1007         ret = filter_visitor_ir_check_binary_op_nesting(ctx);
1008         if (ret) {
1009                 ret = -LTTNG_ERR_FILTER_INVAL;
1010                 goto parse_error;
1011         }
1012
1013         /* Normalize globbing patterns in the expression. */
1014         ret = filter_visitor_ir_normalize_glob_patterns(ctx);
1015         if (ret) {
1016                 ret = -LTTNG_ERR_FILTER_INVAL;
1017                 goto parse_error;
1018         }
1019
1020         /* Validate strings used as literals in the expression. */
1021         ret = filter_visitor_ir_validate_string(ctx);
1022         if (ret) {
1023                 ret = -LTTNG_ERR_FILTER_INVAL;
1024                 goto parse_error;
1025         }
1026
1027         /* Validate globbing patterns in the expression. */
1028         ret = filter_visitor_ir_validate_globbing(ctx);
1029         if (ret) {
1030                 ret = -LTTNG_ERR_FILTER_INVAL;
1031                 goto parse_error;
1032         }
1033
1034         dbg_printf("done\n");
1035
1036         dbg_printf("Generating bytecode... ");
1037         fflush(stdout);
1038         ret = filter_visitor_bytecode_generate(ctx);
1039         if (ret) {
1040                 fprintf(stderr, "Generate bytecode error\n");
1041                 ret = -LTTNG_ERR_FILTER_INVAL;
1042                 goto parse_error;
1043         }
1044         dbg_printf("done\n");
1045         dbg_printf("Size of bytecode generated: %u bytes.\n",
1046                         bytecode_get_len(&ctx->bytecode->b));
1047
1048         *bytecode_len = sizeof(ctx->bytecode->b) +
1049                         bytecode_get_len(&ctx->bytecode->b);
1050
1051         /* No need to keep the memory stream. */
1052         if (fclose(fmem) != 0) {
1053                 PERROR("fclose");
1054         }
1055
1056         *ctxp = ctx;
1057         return 0;
1058
1059 parse_error:
1060         filter_ir_free(ctx);
1061         filter_parser_ctx_free(ctx);
1062 filter_alloc_error:
1063         if (fclose(fmem) != 0) {
1064                 PERROR("fclose");
1065         }
1066 error:
1067         return ret;
1068 }
1069
1070 /*
1071  * Enable event(s) for a channel, possibly with exclusions and a filter.
1072  * If no event name is specified, all events are enabled.
1073  * If no channel name is specified, the default name is used.
1074  * If filter expression is not NULL, the filter is set for the event.
1075  * If exclusion count is not zero, the exclusions are set for the event.
1076  * Returns size of returned session payload data or a negative error code.
1077  */
1078 int lttng_enable_event_with_exclusions(struct lttng_handle *handle,
1079                 struct lttng_event *ev, const char *channel_name,
1080                 const char *original_filter_expression,
1081                 int exclusion_count, char **exclusion_list)
1082 {
1083         struct lttcomm_session_msg lsm;
1084         struct lttng_dynamic_buffer send_buffer;
1085         int ret = 0, fd_to_send = -1;
1086         bool send_fd = false;
1087         unsigned int free_filter_expression = 0;
1088         struct filter_parser_ctx *ctx = NULL;
1089         size_t bytecode_len = 0;
1090
1091         /*
1092          * We have either a filter or some exclusions, so we need to set up
1093          * a variable-length memory block from where to send the data.
1094          */
1095         lttng_dynamic_buffer_init(&send_buffer);
1096
1097         /*
1098          * Cast as non-const since we may replace the filter expression
1099          * by a dynamically allocated string. Otherwise, the original
1100          * string is not modified.
1101          */
1102         char *filter_expression = (char *) original_filter_expression;
1103
1104         if (handle == NULL || ev == NULL) {
1105                 ret = -LTTNG_ERR_INVALID;
1106                 goto error;
1107         }
1108
1109         /*
1110          * Empty filter string will always be rejected by the parser
1111          * anyway, so treat this corner-case early to eliminate
1112          * lttng_fmemopen error for 0-byte allocation.
1113          */
1114         if (filter_expression && filter_expression[0] == '\0') {
1115                 ret = -LTTNG_ERR_INVALID;
1116                 goto error;
1117         }
1118
1119         if (ev->name[0] == '\0') {
1120                 /* Enable all events. */
1121                 ret = lttng_strncpy(ev->name, "*", sizeof(ev->name));
1122                 assert(ret == 0);
1123         }
1124
1125         /* Parse filter expression. */
1126         if (filter_expression != NULL || handle->domain.type == LTTNG_DOMAIN_JUL
1127                         || handle->domain.type == LTTNG_DOMAIN_LOG4J
1128                         || handle->domain.type == LTTNG_DOMAIN_PYTHON) {
1129                 if (handle->domain.type == LTTNG_DOMAIN_JUL ||
1130                                 handle->domain.type == LTTNG_DOMAIN_LOG4J ||
1131                                 handle->domain.type == LTTNG_DOMAIN_PYTHON) {
1132                         char *agent_filter;
1133
1134                         /* Setup agent filter if needed. */
1135                         agent_filter = set_agent_filter(filter_expression, ev);
1136                         if (!agent_filter) {
1137                                 if (!filter_expression) {
1138                                         /*
1139                                          * No JUL and no filter, just skip
1140                                          * everything below.
1141                                          */
1142                                         goto serialize;
1143                                 }
1144                         } else {
1145                                 /*
1146                                  * With an agent filter, the original filter has
1147                                  * been added to it thus replace the filter
1148                                  * expression.
1149                                  */
1150                                 filter_expression = agent_filter;
1151                                 free_filter_expression = 1;
1152                         }
1153                 }
1154
1155                 if (strnlen(filter_expression, LTTNG_FILTER_MAX_LEN) ==
1156                                 LTTNG_FILTER_MAX_LEN) {
1157                         ret = -LTTNG_ERR_FILTER_INVAL;
1158                         goto error;
1159                 }
1160
1161                 ret = generate_filter(filter_expression, &bytecode_len, &ctx);
1162                 if (ret) {
1163                         goto error;
1164                 }
1165
1166                 if (bytecode_len > LTTNG_FILTER_MAX_LEN) {
1167                         ret = -LTTNG_ERR_FILTER_INVAL;
1168                         goto error;
1169                 }
1170         }
1171
1172 serialize:
1173         ret = lttng_event_serialize(ev, exclusion_count, exclusion_list,
1174                         filter_expression, bytecode_len,
1175                         ctx && (bytecode_len != 0) ? &ctx->bytecode->b : NULL,
1176                         &send_buffer, &fd_to_send);
1177         if (ret) {
1178                 goto error;
1179         }
1180
1181         if (fd_to_send >= 0) {
1182                 send_fd = true;
1183         }
1184
1185         /* Prepare the command header */
1186         memset(&lsm, 0, sizeof(lsm));
1187         lsm.cmd_type = LTTNG_ENABLE_EVENT;
1188
1189         /* If no channel name, send empty string. */
1190         ret = lttng_strncpy(lsm.u.enable.channel_name, channel_name ?: "",
1191                         sizeof(lsm.u.enable.channel_name));
1192         if (ret) {
1193                 ret = -LTTNG_ERR_INVALID;
1194                 goto error;
1195         }
1196
1197         /* Domain */
1198         COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
1199
1200         /* Session name */
1201         ret = lttng_strncpy(lsm.session.name, handle->session_name,
1202                         sizeof(lsm.session.name));
1203         if (ret) {
1204                 ret = -LTTNG_ERR_INVALID;
1205                 goto error;
1206         }
1207
1208         /* Length of the serialized event */
1209         lsm.u.enable.length = (uint32_t) send_buffer.size;
1210
1211         ret = lttng_ctl_ask_sessiond_fds_varlen(&lsm,
1212                         send_fd ? &fd_to_send : NULL,
1213                         send_fd ? 1 : 0,
1214                         send_buffer.size ? send_buffer.data : NULL,
1215                         send_buffer.size, NULL, NULL, 0);
1216 error:
1217         if (filter_expression && ctx) {
1218                 filter_bytecode_free(ctx);
1219                 filter_ir_free(ctx);
1220                 filter_parser_ctx_free(ctx);
1221         }
1222
1223         if (free_filter_expression) {
1224                 /*
1225                  * The filter expression has been replaced and must be freed as
1226                  * it is not the original filter expression received as a
1227                  * parameter.
1228                  */
1229                 free(filter_expression);
1230         }
1231
1232         lttng_dynamic_buffer_reset(&send_buffer);
1233         return ret;
1234 }
1235
1236 int lttng_disable_event_ext(struct lttng_handle *handle,
1237                 struct lttng_event *ev, const char *channel_name,
1238                 const char *original_filter_expression)
1239 {
1240         struct lttcomm_session_msg lsm;
1241         struct lttng_dynamic_buffer buf;
1242         int ret = 0;
1243         unsigned int free_filter_expression = 0;
1244         struct filter_parser_ctx *ctx = NULL;
1245         size_t bytecode_len = 0;
1246         int fd_to_send = -1;
1247         bool send_fd = false;
1248         /*
1249          * Cast as non-const since we may replace the filter expression
1250          * by a dynamically allocated string. Otherwise, the original
1251          * string is not modified.
1252          */
1253         char *filter_expression = (char *) original_filter_expression;
1254
1255         lttng_dynamic_buffer_init(&buf);
1256
1257         if (handle == NULL || ev == NULL) {
1258                 ret = -LTTNG_ERR_INVALID;
1259                 goto error;
1260         }
1261
1262         /*
1263          * Empty filter string will always be rejected by the parser
1264          * anyway, so treat this corner-case early to eliminate
1265          * lttng_fmemopen error for 0-byte allocation.
1266          */
1267         if (filter_expression && filter_expression[0] == '\0') {
1268                 ret = -LTTNG_ERR_INVALID;
1269                 goto error;
1270         }
1271
1272         /* Parse filter expression */
1273         if (filter_expression != NULL || handle->domain.type == LTTNG_DOMAIN_JUL
1274                         || handle->domain.type == LTTNG_DOMAIN_LOG4J
1275                         || handle->domain.type == LTTNG_DOMAIN_PYTHON) {
1276                 if (handle->domain.type == LTTNG_DOMAIN_JUL ||
1277                                 handle->domain.type == LTTNG_DOMAIN_LOG4J ||
1278                                 handle->domain.type == LTTNG_DOMAIN_PYTHON) {
1279                         char *agent_filter;
1280
1281                         /* Setup agent filter if needed. */
1282                         agent_filter = set_agent_filter(filter_expression, ev);
1283                         if (!agent_filter) {
1284                                 if (!filter_expression) {
1285                                         /*
1286                                          * No JUL and no filter, just skip
1287                                          * everything below.
1288                                          */
1289                                         goto serialize;
1290                                 }
1291                         } else {
1292                                 /*
1293                                  * With a JUL filter, the original filter has
1294                                  * been added to it thus replace the filter
1295                                  * expression.
1296                                  */
1297                                 filter_expression = agent_filter;
1298                                 free_filter_expression = 1;
1299                         }
1300                 }
1301
1302                 ret = generate_filter(filter_expression, &bytecode_len, &ctx);
1303                 if (ret) {
1304                         ret = -1;
1305                         goto error;
1306                 }
1307         }
1308
1309 serialize:
1310         ret = lttng_event_serialize(ev, 0, NULL, filter_expression,
1311                         bytecode_len,
1312                         ctx && (bytecode_len != 0) ? &ctx->bytecode->b : NULL,
1313                         &buf, &fd_to_send);
1314         if (ret) {
1315                 ret = -1;
1316                 goto error;
1317         }
1318
1319         if (fd_to_send >= 0) {
1320                 send_fd = true;
1321         }
1322
1323         /* Prepare command header */
1324         memset(&lsm, 0, sizeof(lsm));
1325         lsm.cmd_type = LTTNG_DISABLE_EVENT;
1326
1327         /* If no channel name, send empty string. */
1328         ret = lttng_strncpy(lsm.u.disable.channel_name, channel_name ?: "",
1329                         sizeof(lsm.u.disable.channel_name));
1330         if (ret) {
1331                 ret = -LTTNG_ERR_INVALID;
1332                 goto error;
1333         }
1334         /* Domain */
1335         COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
1336
1337         /* Session name */
1338         ret = lttng_strncpy(lsm.session.name, handle->session_name,
1339                         sizeof(lsm.session.name));
1340         if (ret) {
1341                 ret = -LTTNG_ERR_INVALID;
1342                 goto error;
1343         }
1344
1345         /* Length of the serialized event */
1346         lsm.u.disable.length = (uint32_t) buf.size;
1347
1348         ret = lttng_ctl_ask_sessiond_fds_varlen(&lsm,
1349                         send_fd ? &fd_to_send : NULL, send_fd ? 1 : 0,
1350                         buf.size ? buf.data : NULL, buf.size, NULL, NULL, 0);
1351
1352 error:
1353         if (filter_expression && ctx) {
1354                 filter_bytecode_free(ctx);
1355                 filter_ir_free(ctx);
1356                 filter_parser_ctx_free(ctx);
1357         }
1358
1359         if (free_filter_expression) {
1360                 /*
1361                  * The filter expression has been replaced and must be freed as
1362                  * it is not the original filter expression received as a
1363                  * parameter.
1364                  */
1365                 free(filter_expression);
1366         }
1367
1368         lttng_dynamic_buffer_reset(&buf);
1369         return ret;
1370 }
1371
1372 /*
1373  * Disable event(s) of a channel and domain.
1374  * If no event name is specified, all events are disabled.
1375  * If no channel name is specified, the default 'channel0' is used.
1376  * Returns size of returned session payload data or a negative error code.
1377  */
1378 int lttng_disable_event(struct lttng_handle *handle, const char *name,
1379                 const char *channel_name)
1380 {
1381         int ret;
1382         struct lttng_event ev;
1383
1384         memset(&ev, 0, sizeof(ev));
1385         ev.loglevel = -1;
1386         ev.type = LTTNG_EVENT_ALL;
1387         ret = lttng_strncpy(ev.name, name ?: "", sizeof(ev.name));
1388         if (ret) {
1389                 ret = -LTTNG_ERR_INVALID;
1390                 goto end;
1391         }
1392
1393         ret = lttng_disable_event_ext(handle, &ev, channel_name, NULL);
1394 end:
1395         return ret;
1396 }
1397
1398 struct lttng_channel *lttng_channel_create(struct lttng_domain *domain)
1399 {
1400         struct lttng_channel *channel = NULL;
1401
1402         if (!domain) {
1403                 goto end;
1404         }
1405
1406         /* Validate domain. */
1407         switch (domain->type) {
1408         case LTTNG_DOMAIN_UST:
1409                 switch (domain->buf_type) {
1410                 case LTTNG_BUFFER_PER_UID:
1411                 case LTTNG_BUFFER_PER_PID:
1412                         break;
1413                 default:
1414                         goto end;
1415                 }
1416                 break;
1417         case LTTNG_DOMAIN_KERNEL:
1418                 if (domain->buf_type != LTTNG_BUFFER_GLOBAL) {
1419                         goto end;
1420                 }
1421                 break;
1422         default:
1423                 goto end;
1424         }
1425
1426         channel = lttng_channel_create_internal();
1427         if (!channel) {
1428                 goto end;
1429         }
1430
1431         lttng_channel_set_default_attr(domain, &channel->attr);
1432 end:
1433         return channel;
1434 }
1435
1436 void lttng_channel_destroy(struct lttng_channel *channel)
1437 {
1438         if (!channel) {
1439                 return;
1440         }
1441
1442         if (channel->attr.extended.ptr) {
1443                 free(channel->attr.extended.ptr);
1444         }
1445         free(channel);
1446 }
1447
1448 /*
1449  * Enable channel per domain
1450  * Returns size of returned session payload data or a negative error code.
1451  */
1452 int lttng_enable_channel(struct lttng_handle *handle,
1453                 struct lttng_channel *in_chan)
1454 {
1455         enum lttng_error_code ret_code;
1456         int ret;
1457         struct lttng_dynamic_buffer buffer;
1458         struct lttcomm_session_msg lsm;
1459         uint64_t total_buffer_size_needed_per_cpu = 0;
1460         struct lttng_channel *channel = NULL;
1461
1462         lttng_dynamic_buffer_init(&buffer);
1463
1464         /* NULL arguments are forbidden. No default values. */
1465         if (handle == NULL || in_chan == NULL) {
1466                 ret = -LTTNG_ERR_INVALID;
1467                 goto end;
1468         }
1469
1470         /*
1471          * Verify that the amount of memory required to create the requested
1472          * buffer is available on the system at the moment.
1473          */
1474         if (in_chan->attr.num_subbuf >
1475                         UINT64_MAX / in_chan->attr.subbuf_size) {
1476                 /* Overflow */
1477                 ret = -LTTNG_ERR_OVERFLOW;
1478                 goto end;
1479         }
1480
1481         total_buffer_size_needed_per_cpu =
1482                         in_chan->attr.num_subbuf * in_chan->attr.subbuf_size;
1483         ret_code = check_enough_available_memory(
1484                         total_buffer_size_needed_per_cpu);
1485         if (ret_code != LTTNG_OK) {
1486                 ret = -ret_code;
1487                 goto end;
1488         }
1489
1490         /* Copy the channel for easier manipulation. */
1491         channel = lttng_channel_copy(in_chan);
1492         if (!channel) {
1493                 ret = -LTTNG_ERR_NOMEM;
1494                 goto end;
1495         }
1496
1497         /* Populate the channel extended attribute if necessary. */
1498         if (!channel->attr.extended.ptr) {
1499                 struct lttng_channel_extended *extended =
1500                                 zmalloc(sizeof(*extended));
1501
1502                 if (!extended) {
1503                         ret = -LTTNG_ERR_NOMEM;
1504                         goto end;
1505                 }
1506                 lttng_channel_set_default_extended_attr(
1507                                 &handle->domain, extended);
1508                 channel->attr.extended.ptr = extended;
1509         }
1510
1511         /* Prepare the payload */
1512         memset(&lsm, 0, sizeof(lsm));
1513
1514         lsm.cmd_type = LTTNG_ENABLE_CHANNEL;
1515         COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
1516
1517         ret = lttng_strncpy(lsm.session.name, handle->session_name,
1518                                     sizeof(lsm.session.name));
1519         if (ret) {
1520                 ret = -LTTNG_ERR_INVALID;
1521                 goto end;
1522         }
1523
1524         ret = lttng_channel_serialize(channel, &buffer);
1525         if (ret) {
1526                 ret = -LTTNG_ERR_FATAL;
1527                 goto end;
1528         }
1529
1530         lsm.u.channel.length = buffer.size;
1531
1532         ret = lttng_ctl_ask_sessiond_varlen_no_cmd_header(
1533                         &lsm, buffer.data, buffer.size, NULL);
1534 end:
1535         lttng_channel_destroy(channel);
1536         lttng_dynamic_buffer_reset(&buffer);
1537         return ret;
1538 }
1539
1540 /*
1541  * All tracing will be stopped for registered events of the channel.
1542  * Returns size of returned session payload data or a negative error code.
1543  */
1544 int lttng_disable_channel(struct lttng_handle *handle, const char *name)
1545 {
1546         int ret;
1547         struct lttcomm_session_msg lsm;
1548
1549         /* Safety check. Both are mandatory. */
1550         if (handle == NULL || name == NULL) {
1551                 return -LTTNG_ERR_INVALID;
1552         }
1553
1554         memset(&lsm, 0, sizeof(lsm));
1555
1556         lsm.cmd_type = LTTNG_DISABLE_CHANNEL;
1557
1558         ret = lttng_strncpy(lsm.u.disable.channel_name, name,
1559                         sizeof(lsm.u.disable.channel_name));
1560         if (ret) {
1561                 ret = -LTTNG_ERR_INVALID;
1562                 goto end;
1563         }
1564
1565         COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
1566
1567         ret = lttng_strncpy(lsm.session.name, handle->session_name,
1568                             sizeof(lsm.session.name));
1569         if (ret) {
1570                 ret = -LTTNG_ERR_INVALID;
1571                 goto end;
1572         }
1573
1574         ret = lttng_ctl_ask_sessiond(&lsm, NULL);
1575 end:
1576         return ret;
1577 }
1578
1579 /*
1580  * Lists all available tracepoints of domain.
1581  * Sets the contents of the events array.
1582  * Returns the number of lttng_event entries in events;
1583  * on error, returns a negative value.
1584  */
1585 int lttng_list_tracepoints(struct lttng_handle *handle,
1586                 struct lttng_event **events)
1587 {
1588         enum lttng_error_code ret_code;
1589         int ret, total_payload_received;
1590         char *reception_buffer = NULL;
1591         struct lttcomm_session_msg lsm;
1592         struct lttcomm_list_command_header *cmd_header = NULL;
1593         size_t cmd_header_len;
1594         unsigned int nb_events = 0;
1595
1596         if (handle == NULL) {
1597                 ret = -LTTNG_ERR_INVALID;
1598                 goto end;
1599         }
1600
1601         memset(&lsm, 0, sizeof(lsm));
1602         lsm.cmd_type = LTTNG_LIST_TRACEPOINTS;
1603         COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
1604
1605         ret = lttng_ctl_ask_sessiond_fds_varlen(&lsm, NULL, 0, NULL, 0,
1606                         (void **) &reception_buffer, (void **) &cmd_header,
1607                         &cmd_header_len);
1608         if (ret < 0) {
1609                 goto end;
1610         }
1611         total_payload_received = ret;
1612
1613         if (!cmd_header) {
1614                 ret = -LTTNG_ERR_UNK;
1615                 goto end;
1616         }
1617
1618         if (cmd_header->count > INT_MAX) {
1619                 ret = -LTTNG_ERR_OVERFLOW;
1620                 goto end;
1621         }
1622
1623         nb_events = (unsigned int) cmd_header->count;
1624
1625         {
1626                 const struct lttng_buffer_view events_view =
1627                                 lttng_buffer_view_init(reception_buffer, 0,
1628                                                 total_payload_received);
1629
1630                 ret_code = lttng_events_create_and_flatten_from_buffer(
1631                                 &events_view, nb_events, events);
1632                 if (ret_code != LTTNG_OK) {
1633                         ret = -ret_code;
1634                         goto end;
1635                 }
1636         }
1637
1638         ret = (int) nb_events;
1639
1640 end:
1641         free(cmd_header);
1642         free(reception_buffer);
1643         return ret;
1644 }
1645
1646 /*
1647  * Lists all available tracepoint fields of domain.
1648  * Sets the contents of the event field array.
1649  * Returns the number of lttng_event_field entries in events;
1650  * on error, returns a negative value.
1651  */
1652 int lttng_list_tracepoint_fields(struct lttng_handle *handle,
1653                 struct lttng_event_field **fields)
1654 {
1655         enum lttng_error_code ret_code;
1656         int ret, total_payload_received;
1657         struct lttcomm_session_msg lsm;
1658         char *reception_buffer = NULL;
1659         struct lttcomm_list_command_header *cmd_header = NULL;
1660         size_t cmd_header_len;
1661         unsigned int nb_event_fields = 0;
1662
1663         if (handle == NULL) {
1664                 return -LTTNG_ERR_INVALID;
1665         }
1666
1667         memset(&lsm, 0, sizeof(lsm));
1668         lsm.cmd_type = LTTNG_LIST_TRACEPOINT_FIELDS;
1669         COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
1670
1671         ret = lttng_ctl_ask_sessiond_fds_varlen(&lsm, NULL, 0, NULL, 0,
1672                         (void **) &reception_buffer, (void **) &cmd_header,
1673                         &cmd_header_len);
1674         if (ret < 0) {
1675                 goto end;
1676         }
1677
1678         total_payload_received = ret;
1679
1680         if (!cmd_header) {
1681                 ret = -LTTNG_ERR_UNK;
1682                 goto end;
1683         }
1684
1685         if (cmd_header->count > INT_MAX) {
1686                 ret = -LTTNG_ERR_OVERFLOW;
1687                 goto end;
1688         }
1689
1690         nb_event_fields = cmd_header->count;
1691
1692         {
1693                 const struct lttng_buffer_view view =
1694                         lttng_buffer_view_init(reception_buffer, 0, total_payload_received);
1695
1696                 ret_code = lttng_event_fields_create_and_flatten_from_buffer(
1697                                 &view, nb_event_fields, fields);
1698                 if (ret_code != LTTNG_OK) {
1699                         ret = -ret_code;
1700                         goto end;
1701                 }
1702         }
1703
1704         ret = nb_event_fields;
1705
1706 end:
1707         free(cmd_header);
1708         free(reception_buffer);
1709         return ret;
1710 }
1711
1712 /*
1713  * Lists all available kernel system calls. Allocates and sets the contents of
1714  * the events array.
1715  *
1716  * Returns the number of lttng_event entries in events; on error, returns a
1717  * negative value.
1718  */
1719 int lttng_list_syscalls(struct lttng_event **events)
1720 {
1721         enum lttng_error_code ret_code;
1722         int ret, total_payload_received;
1723         char *reception_buffer = NULL;
1724         struct lttcomm_session_msg lsm;
1725         struct lttcomm_list_command_header *cmd_header = NULL;
1726         size_t cmd_header_len;
1727         uint32_t nb_events = 0;
1728
1729         if (!events) {
1730                 ret = -LTTNG_ERR_INVALID;
1731                 goto end;
1732         }
1733
1734         memset(&lsm, 0, sizeof(lsm));
1735         lsm.cmd_type = LTTNG_LIST_SYSCALLS;
1736         /* Force kernel domain for system calls. */
1737         lsm.domain.type = LTTNG_DOMAIN_KERNEL;
1738
1739         ret = lttng_ctl_ask_sessiond_fds_varlen(&lsm, NULL, 0, NULL, 0,
1740                         (void **) &reception_buffer, (void **) &cmd_header,
1741                         &cmd_header_len);
1742         if (ret < 0) {
1743                 goto end;
1744         }
1745         total_payload_received = ret;
1746
1747         if (!cmd_header) {
1748                 ret = -LTTNG_ERR_UNK;
1749                 goto end;
1750         }
1751
1752         if (cmd_header->count > INT_MAX) {
1753                 ret = -LTTNG_ERR_OVERFLOW;
1754                 goto end;
1755         }
1756
1757         nb_events = (unsigned int) cmd_header->count;
1758
1759         {
1760                 const struct lttng_buffer_view events_view =
1761                                 lttng_buffer_view_init(reception_buffer, 0,
1762                                                 total_payload_received);
1763
1764                 ret_code = lttng_events_create_and_flatten_from_buffer(
1765                                 &events_view, nb_events, events);
1766                 if (ret_code != LTTNG_OK) {
1767                         ret = -ret_code;
1768                         goto end;
1769                 }
1770         }
1771
1772         ret = (int) nb_events;
1773
1774 end:
1775         free(reception_buffer);
1776         free(cmd_header);
1777         return ret;
1778 }
1779
1780 /*
1781  * Returns a human readable string describing
1782  * the error code (a negative value).
1783  */
1784 const char *lttng_strerror(int code)
1785 {
1786         return error_get_str(code);
1787 }
1788
1789 enum lttng_error_code lttng_create_session_ext(
1790                 struct lttng_session_descriptor *session_descriptor)
1791 {
1792         enum lttng_error_code ret_code;
1793         struct lttcomm_session_msg lsm = {
1794                 .cmd_type = LTTNG_CREATE_SESSION_EXT,
1795         };
1796         void *reply = NULL;
1797         struct lttng_buffer_view reply_view;
1798         int reply_ret;
1799         bool sessiond_must_generate_ouput;
1800         struct lttng_dynamic_buffer payload;
1801         int ret;
1802         size_t descriptor_size;
1803         struct lttng_session_descriptor *descriptor_reply = NULL;
1804
1805         lttng_dynamic_buffer_init(&payload);
1806         if (!session_descriptor) {
1807                 ret_code = LTTNG_ERR_INVALID;
1808                 goto end;
1809         }
1810
1811         sessiond_must_generate_ouput =
1812                         !lttng_session_descriptor_is_output_destination_initialized(
1813                                 session_descriptor);
1814         if (sessiond_must_generate_ouput) {
1815                 const char *home_dir = utils_get_home_dir();
1816                 size_t home_dir_len = home_dir ? strlen(home_dir) + 1 : 0;
1817
1818                 if (!home_dir || home_dir_len > LTTNG_PATH_MAX) {
1819                         ret_code = LTTNG_ERR_FATAL;
1820                         goto end;
1821                 }
1822
1823                 lsm.u.create_session.home_dir_size = (uint16_t) home_dir_len;
1824                 ret = lttng_dynamic_buffer_append(&payload, home_dir,
1825                                 home_dir_len);
1826                 if (ret) {
1827                         ret_code = LTTNG_ERR_NOMEM;
1828                         goto end;
1829                 }
1830         }
1831
1832         descriptor_size = payload.size;
1833         ret = lttng_session_descriptor_serialize(session_descriptor,
1834                         &payload);
1835         if (ret) {
1836                 ret_code = LTTNG_ERR_INVALID;
1837                 goto end;
1838         }
1839         descriptor_size = payload.size - descriptor_size;
1840         lsm.u.create_session.session_descriptor_size = descriptor_size;
1841
1842         /* Command returns a session descriptor on success. */
1843         reply_ret = lttng_ctl_ask_sessiond_varlen_no_cmd_header(&lsm, payload.data,
1844                         payload.size, &reply);
1845         if (reply_ret < 0) {
1846                 ret_code = -reply_ret;
1847                 goto end;
1848         } else if (reply_ret == 0) {
1849                 /* Socket unexpectedly closed by the session daemon. */
1850                 ret_code = LTTNG_ERR_FATAL;
1851                 goto end;
1852         }
1853
1854         reply_view = lttng_buffer_view_init(reply, 0, reply_ret);
1855         ret = lttng_session_descriptor_create_from_buffer(&reply_view,
1856                         &descriptor_reply);
1857         if (ret < 0) {
1858                 ret_code = LTTNG_ERR_FATAL;
1859                 goto end;
1860         }
1861         ret_code = LTTNG_OK;
1862         lttng_session_descriptor_assign(session_descriptor, descriptor_reply);
1863 end:
1864         free(reply);
1865         lttng_dynamic_buffer_reset(&payload);
1866         lttng_session_descriptor_destroy(descriptor_reply);
1867         return ret_code;
1868 }
1869
1870 /*
1871  * Create a new session using name and url for destination.
1872  *
1873  * Return 0 on success else a negative LTTng error code.
1874  */
1875 int lttng_create_session(const char *name, const char *url)
1876 {
1877         int ret;
1878         ssize_t size;
1879         struct lttng_uri *uris = NULL;
1880         struct lttng_session_descriptor *descriptor = NULL;
1881         enum lttng_error_code ret_code;
1882
1883         if (!name) {
1884                 ret = -LTTNG_ERR_INVALID;
1885                 goto end;
1886         }
1887
1888         size = uri_parse_str_urls(url, NULL, &uris);
1889         if (size < 0) {
1890                 ret = -LTTNG_ERR_INVALID;
1891                 goto end;
1892         }
1893         switch (size) {
1894         case 0:
1895                 descriptor = lttng_session_descriptor_create(name);
1896                 break;
1897         case 1:
1898                 if (uris[0].dtype != LTTNG_DST_PATH) {
1899                         ret = -LTTNG_ERR_INVALID;
1900                         goto end;
1901                 }
1902                 descriptor = lttng_session_descriptor_local_create(name,
1903                                 uris[0].dst.path);
1904                 break;
1905         case 2:
1906                 descriptor = lttng_session_descriptor_network_create(name, url,
1907                                 NULL);
1908                 break;
1909         default:
1910                 ret = -LTTNG_ERR_INVALID;
1911                 goto end;
1912         }
1913         if (!descriptor) {
1914                 ret = -LTTNG_ERR_INVALID;
1915                 goto end;
1916         }
1917         ret_code = lttng_create_session_ext(descriptor);
1918         ret = ret_code == LTTNG_OK ? 0 : -ret_code;
1919 end:
1920         lttng_session_descriptor_destroy(descriptor);
1921         free(uris);
1922         return ret;
1923 }
1924
1925 /*
1926  * Create a session exclusively used for snapshot.
1927  *
1928  * Return 0 on success else a negative LTTng error code.
1929  */
1930 int lttng_create_session_snapshot(const char *name, const char *snapshot_url)
1931 {
1932         int ret;
1933         enum lttng_error_code ret_code;
1934         ssize_t size;
1935         struct lttng_uri *uris = NULL;
1936         struct lttng_session_descriptor *descriptor = NULL;
1937
1938         if (!name) {
1939                 ret = -LTTNG_ERR_INVALID;
1940                 goto end;
1941         }
1942
1943         size = uri_parse_str_urls(snapshot_url, NULL, &uris);
1944         if (size < 0) {
1945                 ret = -LTTNG_ERR_INVALID;
1946                 goto end;
1947         }
1948         /*
1949          * If the user does not specify a custom subdir, use the session name.
1950          */
1951         if (size > 0 && uris[0].dtype != LTTNG_DST_PATH &&
1952                         strlen(uris[0].subdir) == 0) {
1953                 ret = snprintf(uris[0].subdir, sizeof(uris[0].subdir), "%s",
1954                                 name);
1955                 if (ret < 0) {
1956                         PERROR("Failed to set session name as network destination sub-directory");
1957                         ret = -LTTNG_ERR_FATAL;
1958                         goto end;
1959                 } else if (ret >= sizeof(uris[0].subdir)) {
1960                         /* Truncated output. */
1961                         ret = -LTTNG_ERR_INVALID;
1962                         goto end;
1963                 }
1964         }
1965
1966         switch (size) {
1967         case 0:
1968                 descriptor = lttng_session_descriptor_snapshot_create(name);
1969                 break;
1970         case 1:
1971                 if (uris[0].dtype != LTTNG_DST_PATH) {
1972                         ret = -LTTNG_ERR_INVALID;
1973                         goto end;
1974                 }
1975                 descriptor = lttng_session_descriptor_snapshot_local_create(
1976                                 name,
1977                                 uris[0].dst.path);
1978                 break;
1979         case 2:
1980                 descriptor = lttng_session_descriptor_snapshot_network_create(
1981                                 name,
1982                                 snapshot_url,
1983                                 NULL);
1984                 break;
1985         default:
1986                 ret = -LTTNG_ERR_INVALID;
1987                 goto end;
1988         }
1989         if (!descriptor) {
1990                 ret = -LTTNG_ERR_INVALID;
1991                 goto end;
1992         }
1993         ret_code = lttng_create_session_ext(descriptor);
1994         ret = ret_code == LTTNG_OK ? 0 : -ret_code;
1995 end:
1996         lttng_session_descriptor_destroy(descriptor);
1997         free(uris);
1998         return ret;
1999 }
2000
2001 /*
2002  * Create a session exclusively used for live.
2003  *
2004  * Return 0 on success else a negative LTTng error code.
2005  */
2006 int lttng_create_session_live(const char *name, const char *url,
2007                 unsigned int timer_interval)
2008 {
2009         int ret;
2010         enum lttng_error_code ret_code;
2011         struct lttng_session_descriptor *descriptor = NULL;
2012
2013         if (!name) {
2014                 ret = -LTTNG_ERR_INVALID;
2015                 goto end;
2016         }
2017
2018         if (url) {
2019                 descriptor = lttng_session_descriptor_live_network_create(
2020                                 name, url, NULL, timer_interval);
2021         } else {
2022                 descriptor = lttng_session_descriptor_live_create(
2023                                 name, timer_interval);
2024         }
2025         if (!descriptor) {
2026                 ret = -LTTNG_ERR_INVALID;
2027                 goto end;
2028         }
2029         ret_code = lttng_create_session_ext(descriptor);
2030         ret = ret_code == LTTNG_OK ? 0 : -ret_code;
2031 end:
2032         lttng_session_descriptor_destroy(descriptor);
2033         return ret;
2034 }
2035
2036 /*
2037  * Stop the session and wait for the data before destroying it
2038  *
2039  * Return 0 on success else a negative LTTng error code.
2040  */
2041 int lttng_destroy_session(const char *session_name)
2042 {
2043         int ret;
2044         enum lttng_error_code ret_code;
2045         enum lttng_destruction_handle_status status;
2046         struct lttng_destruction_handle *handle = NULL;
2047
2048         /*
2049          * Stop the tracing and wait for the data to be
2050          * consumed.
2051          */
2052         ret = _lttng_stop_tracing(session_name, 1);
2053         if (ret && ret != -LTTNG_ERR_TRACE_ALREADY_STOPPED) {
2054                 goto end;
2055         }
2056
2057         ret_code = lttng_destroy_session_ext(session_name, &handle);
2058         if (ret_code != LTTNG_OK) {
2059                 ret = (int) -ret_code;
2060                 goto end;
2061         }
2062         assert(handle);
2063
2064         /* Block until the completion of the destruction of the session. */
2065         status = lttng_destruction_handle_wait_for_completion(handle, -1);
2066         if (status != LTTNG_DESTRUCTION_HANDLE_STATUS_COMPLETED) {
2067                 ret = -LTTNG_ERR_UNK;
2068                 goto end;
2069         }
2070
2071         status = lttng_destruction_handle_get_result(handle, &ret_code);
2072         if (status != LTTNG_DESTRUCTION_HANDLE_STATUS_OK) {
2073                 ret = -LTTNG_ERR_UNK;
2074                 goto end;
2075         }
2076         ret = ret_code == LTTNG_OK ? 0 : -ret_code;
2077 end:
2078         lttng_destruction_handle_destroy(handle);
2079         return ret;
2080 }
2081
2082 /*
2083  * Destroy the session without waiting for the data.
2084  */
2085 int lttng_destroy_session_no_wait(const char *session_name)
2086 {
2087         enum lttng_error_code ret_code;
2088
2089         ret_code = lttng_destroy_session_ext(session_name, NULL);
2090         return ret_code == LTTNG_OK ? 0 : -ret_code;
2091 }
2092
2093 /*
2094  * Ask the session daemon for all available sessions.
2095  * Sets the contents of the sessions array.
2096  * Returns the number of lttng_session entries in sessions;
2097  * on error, returns a negative value.
2098  */
2099 int lttng_list_sessions(struct lttng_session **out_sessions)
2100 {
2101         int ret;
2102         struct lttcomm_session_msg lsm;
2103         const size_t session_size = sizeof(struct lttng_session) +
2104                         sizeof(struct lttng_session_extended);
2105         size_t session_count, i;
2106         struct lttng_session_extended *sessions_extended_begin;
2107         struct lttng_session *sessions = NULL;
2108
2109         memset(&lsm, 0, sizeof(lsm));
2110         lsm.cmd_type = LTTNG_LIST_SESSIONS;
2111         /*
2112          * Initialize out_sessions to NULL so it is initialized when
2113          * lttng_list_sessions returns 0, thus allowing *out_sessions to
2114          * be subsequently freed.
2115          */
2116         *out_sessions = NULL;
2117         ret = lttng_ctl_ask_sessiond(&lsm, (void**) &sessions);
2118         if (ret <= 0) {
2119                 goto end;
2120         }
2121         if (!sessions) {
2122                 ret = -LTTNG_ERR_FATAL;
2123                 goto end;
2124         }
2125
2126         if (ret % session_size) {
2127                 ret = -LTTNG_ERR_UNK;
2128                 free(sessions);
2129                 goto end;
2130         }
2131         session_count = (size_t) ret / session_size;
2132         sessions_extended_begin = (struct lttng_session_extended *)
2133                         (&sessions[session_count]);
2134
2135         /* Set extended session info pointers. */
2136         for (i = 0; i < session_count; i++) {
2137                 struct lttng_session *session = &sessions[i];
2138                 struct lttng_session_extended *extended =
2139                                 &(sessions_extended_begin[i]);
2140
2141                 session->extended.ptr = extended;
2142         }
2143
2144         ret = (int) session_count;
2145         *out_sessions = sessions;
2146 end:
2147         return ret;
2148 }
2149
2150 enum lttng_error_code lttng_session_get_creation_time(
2151                 const struct lttng_session *session, uint64_t *creation_time)
2152 {
2153         enum lttng_error_code ret = LTTNG_OK;
2154         struct lttng_session_extended *extended;
2155
2156         if (!session || !creation_time || !session->extended.ptr) {
2157                 ret = LTTNG_ERR_INVALID;
2158                 goto end;
2159         }
2160
2161         extended = session->extended.ptr;
2162         if (!extended->creation_time.is_set) {
2163                 /* Not created on the session daemon yet. */
2164                 ret = LTTNG_ERR_SESSION_NOT_EXIST;
2165                 goto end;
2166         }
2167         *creation_time = extended->creation_time.value;
2168 end:
2169         return ret;
2170 }
2171
2172 int lttng_set_session_shm_path(const char *session_name,
2173                 const char *shm_path)
2174 {
2175         int ret;
2176         struct lttcomm_session_msg lsm;
2177
2178         if (session_name == NULL) {
2179                 return -LTTNG_ERR_INVALID;
2180         }
2181
2182         memset(&lsm, 0, sizeof(lsm));
2183         lsm.cmd_type = LTTNG_SET_SESSION_SHM_PATH;
2184
2185         ret = lttng_strncpy(lsm.session.name, session_name,
2186                         sizeof(lsm.session.name));
2187         if (ret) {
2188                 ret = -LTTNG_ERR_INVALID;
2189                 goto end;
2190         }
2191
2192         ret = lttng_strncpy(lsm.u.set_shm_path.shm_path, shm_path ?: "",
2193                         sizeof(lsm.u.set_shm_path.shm_path));
2194         if (ret) {
2195                 ret = -LTTNG_ERR_INVALID;
2196                 goto end;
2197         }
2198
2199         ret = lttng_ctl_ask_sessiond(&lsm, NULL);
2200 end:
2201         return ret;
2202 }
2203
2204 /*
2205  * Ask the session daemon for all available domains of a session.
2206  * Sets the contents of the domains array.
2207  * Returns the number of lttng_domain entries in domains;
2208  * on error, returns a negative value.
2209  */
2210 int lttng_list_domains(const char *session_name,
2211                 struct lttng_domain **domains)
2212 {
2213         int ret;
2214         struct lttcomm_session_msg lsm;
2215
2216         if (session_name == NULL) {
2217                 ret = -LTTNG_ERR_INVALID;
2218                 goto error;
2219         }
2220
2221         memset(&lsm, 0, sizeof(lsm));
2222         lsm.cmd_type = LTTNG_LIST_DOMAINS;
2223
2224         ret = lttng_strncpy(lsm.session.name, session_name,
2225                         sizeof(lsm.session.name));
2226         if (ret) {
2227                 ret = -LTTNG_ERR_INVALID;
2228                 goto error;
2229         }
2230
2231         ret = lttng_ctl_ask_sessiond(&lsm, (void**) domains);
2232         if (ret < 0) {
2233                 goto error;
2234         }
2235
2236         return ret / sizeof(struct lttng_domain);
2237 error:
2238         return ret;
2239 }
2240
2241 /*
2242  * Ask the session daemon for all available channels of a session.
2243  * Sets the contents of the channels array.
2244  * Returns the number of lttng_channel entries in channels;
2245  * on error, returns a negative value.
2246  */
2247 int lttng_list_channels(struct lttng_handle *handle,
2248                 struct lttng_channel **channels)
2249 {
2250         int ret, total_payload_received;
2251         struct lttcomm_session_msg lsm;
2252         char *reception_buffer = NULL;
2253         size_t cmd_header_len = 0;
2254         struct lttcomm_list_command_header *cmd_header = NULL;
2255         struct lttng_dynamic_buffer tmp_buffer;
2256
2257         lttng_dynamic_buffer_init(&tmp_buffer);
2258
2259         if (handle == NULL) {
2260                 ret = -LTTNG_ERR_INVALID;
2261                 goto end;
2262         }
2263
2264         memset(&lsm, 0, sizeof(lsm));
2265         lsm.cmd_type = LTTNG_LIST_CHANNELS;
2266         ret = lttng_strncpy(lsm.session.name, handle->session_name,
2267                         sizeof(lsm.session.name));
2268         if (ret) {
2269                 ret = -LTTNG_ERR_INVALID;
2270                 goto end;
2271         }
2272
2273         COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
2274
2275         ret = lttng_ctl_ask_sessiond_fds_varlen(&lsm, NULL, 0, NULL, 0,
2276                         (void **) &reception_buffer, (void **) &cmd_header,
2277                         &cmd_header_len);
2278         if (ret < 0) {
2279                 goto end;
2280         }
2281
2282         total_payload_received = ret;
2283
2284         if (cmd_header_len != sizeof(*cmd_header)) {
2285                 ret = -LTTNG_ERR_FATAL;
2286                 goto end;
2287         }
2288
2289         if (!cmd_header) {
2290                 ret = LTTNG_ERR_UNK;
2291                 goto end;
2292         }
2293
2294         if (cmd_header->count > INT_MAX) {
2295                 ret = -LTTNG_ERR_OVERFLOW;
2296                 goto end;
2297         }
2298
2299         {
2300                 enum lttng_error_code ret_code;
2301                 const struct lttng_buffer_view events_view =
2302                                 lttng_buffer_view_init(reception_buffer, 0,
2303                                                 total_payload_received);
2304
2305                 ret_code = lttng_channels_create_and_flatten_from_buffer(
2306                                 &events_view, cmd_header->count, channels);
2307                 if (ret_code != LTTNG_OK) {
2308                         ret = -ret_code;
2309                         goto end;
2310                 }
2311         }
2312
2313         ret = (int) cmd_header->count;
2314 end:
2315         free(cmd_header);
2316         free(reception_buffer);
2317         return ret;
2318 }
2319
2320 /*
2321  * Ask the session daemon for all available events of a session channel.
2322  * Sets the contents of the events array.
2323  * Returns the number of lttng_event entries in events;
2324  * on error, returns a negative value.
2325  */
2326 int lttng_list_events(struct lttng_handle *handle,
2327                 const char *channel_name, struct lttng_event **events)
2328 {
2329         enum lttng_error_code ret_code;
2330         int ret;
2331         struct lttcomm_session_msg lsm;
2332         struct lttcomm_list_command_header *cmd_header = NULL;
2333         size_t cmd_header_len;
2334         unsigned int nb_events;
2335         char *reception_buffer = NULL;
2336         struct lttng_dynamic_buffer tmp_buffer;
2337         ssize_t total_payload_received;
2338
2339         lttng_dynamic_buffer_init(&tmp_buffer);
2340
2341         /* Safety check. An handle and channel name are mandatory */
2342         if (handle == NULL || channel_name == NULL) {
2343                 return -LTTNG_ERR_INVALID;
2344         }
2345
2346         memset(&lsm, 0, sizeof(lsm));
2347         lsm.cmd_type = LTTNG_LIST_EVENTS;
2348         ret = lttng_strncpy(lsm.session.name, handle->session_name,
2349                         sizeof(lsm.session.name));
2350         if (ret) {
2351                 ret = -LTTNG_ERR_INVALID;
2352                 goto end;
2353         }
2354
2355         ret = lttng_strncpy(lsm.u.list.channel_name, channel_name,
2356                         sizeof(lsm.u.list.channel_name));
2357         if (ret) {
2358                 ret = -LTTNG_ERR_INVALID;
2359                 goto end;
2360         }
2361
2362         COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
2363
2364         ret = lttng_ctl_ask_sessiond_fds_varlen(&lsm, NULL, 0, NULL, 0,
2365                 (void **) &reception_buffer, (void **) &cmd_header,
2366                 &cmd_header_len);
2367         if (ret < 0) {
2368                 goto end;
2369         }
2370
2371         total_payload_received = ret;
2372
2373         if (!cmd_header) {
2374                 ret = -LTTNG_ERR_UNK;
2375                 goto end;
2376         }
2377
2378         if (cmd_header->count > INT_MAX) {
2379                 ret = -LTTNG_ERR_OVERFLOW;
2380                 goto end;
2381         }
2382
2383         nb_events = (unsigned int) cmd_header->count;
2384
2385         {
2386                 const struct lttng_buffer_view events_view =
2387                                 lttng_buffer_view_init(reception_buffer, 0,
2388                                                 total_payload_received);
2389                 ret_code = lttng_events_create_and_flatten_from_buffer(
2390                                 &events_view, nb_events, events);
2391                 if (ret_code != LTTNG_OK) {
2392                         ret = -ret_code;
2393                         goto end;
2394                 }
2395         }
2396
2397         ret = (int) nb_events;
2398 end:
2399         free(cmd_header);
2400         free(reception_buffer);
2401         return ret;
2402 }
2403
2404 /*
2405  * Sets the tracing_group variable with name.
2406  * This function allocates memory pointed to by tracing_group.
2407  * On success, returns 0, on error, returns -1 (null name) or -ENOMEM.
2408  */
2409 int lttng_set_tracing_group(const char *name)
2410 {
2411         char *new_group;
2412         if (name == NULL) {
2413                 return -LTTNG_ERR_INVALID;
2414         }
2415
2416         if (asprintf(&new_group, "%s", name) < 0) {
2417                 return -LTTNG_ERR_FATAL;
2418         }
2419
2420         free(tracing_group);
2421         tracing_group = new_group;
2422         new_group = NULL;
2423
2424         return 0;
2425 }
2426
2427 int lttng_calibrate(struct lttng_handle *handle,
2428                 struct lttng_calibrate *calibrate)
2429 {
2430         /*
2431          * This command was removed in LTTng 2.9.
2432          */
2433         return -LTTNG_ERR_UND;
2434 }
2435
2436 /*
2437  * Set default channel attributes.
2438  * If either or both of the arguments are null, attr content is zeroe'd.
2439  */
2440 void lttng_channel_set_default_attr(struct lttng_domain *domain,
2441                 struct lttng_channel_attr *attr)
2442 {
2443         struct lttng_channel_extended *extended;
2444
2445         /* Safety check */
2446         if (attr == NULL || domain == NULL) {
2447                 return;
2448         }
2449
2450         /* Save the pointer for later use */
2451         extended = (struct lttng_channel_extended *) attr->extended.ptr;
2452         memset(attr, 0, sizeof(struct lttng_channel_attr));
2453
2454         /* Same for all domains. */
2455         attr->overwrite = DEFAULT_CHANNEL_OVERWRITE;
2456         attr->tracefile_size = DEFAULT_CHANNEL_TRACEFILE_SIZE;
2457         attr->tracefile_count = DEFAULT_CHANNEL_TRACEFILE_COUNT;
2458
2459         switch (domain->type) {
2460         case LTTNG_DOMAIN_KERNEL:
2461                 attr->switch_timer_interval =
2462                                 DEFAULT_KERNEL_CHANNEL_SWITCH_TIMER;
2463                 attr->read_timer_interval = DEFAULT_KERNEL_CHANNEL_READ_TIMER;
2464                 attr->subbuf_size = default_get_kernel_channel_subbuf_size();
2465                 attr->num_subbuf = DEFAULT_KERNEL_CHANNEL_SUBBUF_NUM;
2466                 attr->output = DEFAULT_KERNEL_CHANNEL_OUTPUT;
2467                 break;
2468         case LTTNG_DOMAIN_UST:
2469                 switch (domain->buf_type) {
2470                 case LTTNG_BUFFER_PER_UID:
2471                         attr->subbuf_size = default_get_ust_uid_channel_subbuf_size();
2472                         attr->num_subbuf = DEFAULT_UST_UID_CHANNEL_SUBBUF_NUM;
2473                         attr->output = DEFAULT_UST_UID_CHANNEL_OUTPUT;
2474                         attr->switch_timer_interval =
2475                                         DEFAULT_UST_UID_CHANNEL_SWITCH_TIMER;
2476                         attr->read_timer_interval =
2477                                         DEFAULT_UST_UID_CHANNEL_READ_TIMER;
2478                         break;
2479                 case LTTNG_BUFFER_PER_PID:
2480                 default:
2481                         attr->subbuf_size = default_get_ust_pid_channel_subbuf_size();
2482                         attr->num_subbuf = DEFAULT_UST_PID_CHANNEL_SUBBUF_NUM;
2483                         attr->output = DEFAULT_UST_PID_CHANNEL_OUTPUT;
2484                         attr->switch_timer_interval =
2485                                         DEFAULT_UST_PID_CHANNEL_SWITCH_TIMER;
2486                         attr->read_timer_interval =
2487                                         DEFAULT_UST_PID_CHANNEL_READ_TIMER;
2488                         break;
2489                 }
2490         default:
2491                 /* Default behavior: leave set to 0. */
2492                 break;
2493         }
2494
2495         if (extended) {
2496                 lttng_channel_set_default_extended_attr(domain, extended);
2497         }
2498
2499         /* Reassign the extended pointer. */
2500         attr->extended.ptr = extended;
2501 }
2502
2503 int lttng_channel_get_discarded_event_count(struct lttng_channel *channel,
2504                 uint64_t *discarded_events)
2505 {
2506         int ret = 0;
2507         struct lttng_channel_extended *chan_ext;
2508
2509         if (!channel || !discarded_events) {
2510                 ret = -LTTNG_ERR_INVALID;
2511                 goto end;
2512         }
2513
2514         chan_ext = channel->attr.extended.ptr;
2515         if (!chan_ext) {
2516                 /*
2517                  * This can happen since the lttng_channel structure is
2518                  * used for other tasks where this pointer is never set.
2519                  */
2520                 *discarded_events = 0;
2521                 goto end;
2522         }
2523
2524         *discarded_events = chan_ext->discarded_events;
2525 end:
2526         return ret;
2527 }
2528
2529 int lttng_channel_get_lost_packet_count(struct lttng_channel *channel,
2530                 uint64_t *lost_packets)
2531 {
2532         int ret = 0;
2533         struct lttng_channel_extended *chan_ext;
2534
2535         if (!channel || !lost_packets) {
2536                 ret = -LTTNG_ERR_INVALID;
2537                 goto end;
2538         }
2539
2540         chan_ext = channel->attr.extended.ptr;
2541         if (!chan_ext) {
2542                 /*
2543                  * This can happen since the lttng_channel structure is
2544                  * used for other tasks where this pointer is never set.
2545                  */
2546                 *lost_packets = 0;
2547                 goto end;
2548         }
2549
2550         *lost_packets = chan_ext->lost_packets;
2551 end:
2552         return ret;
2553 }
2554
2555 int lttng_channel_get_monitor_timer_interval(struct lttng_channel *chan,
2556                 uint64_t *monitor_timer_interval)
2557 {
2558         int ret = 0;
2559
2560         if (!chan || !monitor_timer_interval) {
2561                 ret = -LTTNG_ERR_INVALID;
2562                 goto end;
2563         }
2564
2565         if (!chan->attr.extended.ptr) {
2566                 ret = -LTTNG_ERR_INVALID;
2567                 goto end;
2568         }
2569
2570         *monitor_timer_interval = ((struct lttng_channel_extended *)
2571                         chan->attr.extended.ptr)->monitor_timer_interval;
2572 end:
2573         return ret;
2574 }
2575
2576 int lttng_channel_set_monitor_timer_interval(struct lttng_channel *chan,
2577                 uint64_t monitor_timer_interval)
2578 {
2579         int ret = 0;
2580
2581         if (!chan || !chan->attr.extended.ptr) {
2582                 ret = -LTTNG_ERR_INVALID;
2583                 goto end;
2584         }
2585
2586         ((struct lttng_channel_extended *)
2587                         chan->attr.extended.ptr)->monitor_timer_interval =
2588                         monitor_timer_interval;
2589 end:
2590         return ret;
2591 }
2592
2593 int lttng_channel_get_blocking_timeout(struct lttng_channel *chan,
2594                 int64_t *blocking_timeout)
2595 {
2596         int ret = 0;
2597
2598         if (!chan || !blocking_timeout) {
2599                 ret = -LTTNG_ERR_INVALID;
2600                 goto end;
2601         }
2602
2603         if (!chan->attr.extended.ptr) {
2604                 ret = -LTTNG_ERR_INVALID;
2605                 goto end;
2606         }
2607
2608         *blocking_timeout = ((struct lttng_channel_extended *)
2609                         chan->attr.extended.ptr)->blocking_timeout;
2610 end:
2611         return ret;
2612 }
2613
2614 int lttng_channel_set_blocking_timeout(struct lttng_channel *chan,
2615                 int64_t blocking_timeout)
2616 {
2617         int ret = 0;
2618         int64_t msec_timeout;
2619
2620         if (!chan || !chan->attr.extended.ptr) {
2621                 ret = -LTTNG_ERR_INVALID;
2622                 goto end;
2623         }
2624
2625         if (blocking_timeout < 0 && blocking_timeout != -1) {
2626                 ret = -LTTNG_ERR_INVALID;
2627                 goto end;
2628         }
2629
2630         /*
2631          * LTTng-ust's use of poll() to implement this timeout mechanism forces
2632          * us to accept a narrower range of values (msecs expressed as a signed
2633          * 32-bit integer).
2634          */
2635         msec_timeout = blocking_timeout / 1000;
2636         if (msec_timeout != (int32_t) msec_timeout) {
2637                 ret = -LTTNG_ERR_INVALID;
2638                 goto end;
2639         }
2640
2641         ((struct lttng_channel_extended *)
2642                         chan->attr.extended.ptr)->blocking_timeout =
2643                         blocking_timeout;
2644 end:
2645         return ret;
2646 }
2647
2648 /*
2649  * Check if session daemon is alive.
2650  *
2651  * Return 1 if alive or 0 if not.
2652  * On error returns a negative value.
2653  */
2654 int lttng_session_daemon_alive(void)
2655 {
2656         int ret;
2657
2658         ret = set_session_daemon_path();
2659         if (ret < 0) {
2660                 /* Error. */
2661                 return ret;
2662         }
2663
2664         if (*sessiond_sock_path == '\0') {
2665                 /*
2666                  * No socket path set. Weird error which means the constructor
2667                  * was not called.
2668                  */
2669                 assert(0);
2670         }
2671
2672         ret = try_connect_sessiond(sessiond_sock_path);
2673         if (ret < 0) {
2674                 /* Not alive. */
2675                 return 0;
2676         }
2677
2678         /* Is alive. */
2679         return 1;
2680 }
2681
2682 /*
2683  * Set URL for a consumer for a session and domain.
2684  *
2685  * Return 0 on success, else a negative value.
2686  */
2687 int lttng_set_consumer_url(struct lttng_handle *handle,
2688                 const char *control_url, const char *data_url)
2689 {
2690         int ret;
2691         ssize_t size;
2692         struct lttcomm_session_msg lsm;
2693         struct lttng_uri *uris = NULL;
2694
2695         if (handle == NULL || (control_url == NULL && data_url == NULL)) {
2696                 ret = -LTTNG_ERR_INVALID;
2697                 goto error;
2698         }
2699
2700         memset(&lsm, 0, sizeof(lsm));
2701
2702         lsm.cmd_type = LTTNG_SET_CONSUMER_URI;
2703
2704         ret = lttng_strncpy(lsm.session.name, handle->session_name,
2705                         sizeof(lsm.session.name));
2706         if (ret) {
2707                 ret = -LTTNG_ERR_INVALID;
2708                 goto error;
2709         }
2710
2711         COPY_DOMAIN_PACKED(lsm.domain, handle->domain);
2712
2713         size = uri_parse_str_urls(control_url, data_url, &uris);
2714         if (size < 0) {
2715                 ret = -LTTNG_ERR_INVALID;
2716                 goto error;
2717         }
2718
2719         lsm.u.uri.size = size;
2720
2721         ret = lttng_ctl_ask_sessiond_varlen_no_cmd_header(&lsm, uris,
2722                         sizeof(struct lttng_uri) * size, NULL);
2723
2724         free(uris);
2725 error:
2726         return ret;
2727 }
2728
2729 /*
2730  * [OBSOLETE]
2731  */
2732 int lttng_enable_consumer(struct lttng_handle *handle);
2733 int lttng_enable_consumer(struct lttng_handle *handle)
2734 {
2735         return -ENOSYS;
2736 }
2737
2738 /*
2739  * [OBSOLETE]
2740  */
2741 int lttng_disable_consumer(struct lttng_handle *handle);
2742 int lttng_disable_consumer(struct lttng_handle *handle)
2743 {
2744         return -ENOSYS;
2745 }
2746
2747 /*
2748  * [OBSOLETE]
2749  */
2750 int _lttng_create_session_ext(const char *name, const char *url,
2751                 const char *datetime);
2752 int _lttng_create_session_ext(const char *name, const char *url,
2753                 const char *datetime)
2754 {
2755         return -ENOSYS;
2756 }
2757
2758 /*
2759  * For a given session name, this call checks if the data is ready to be read
2760  * or is still being extracted by the consumer(s) hence not ready to be used by
2761  * any readers.
2762  */
2763 int lttng_data_pending(const char *session_name)
2764 {
2765         int ret;
2766         struct lttcomm_session_msg lsm;
2767         uint8_t *pending = NULL;
2768
2769         if (session_name == NULL) {
2770                 return -LTTNG_ERR_INVALID;
2771         }
2772
2773         memset(&lsm, 0, sizeof(lsm));
2774         lsm.cmd_type = LTTNG_DATA_PENDING;
2775
2776         ret = lttng_strncpy(lsm.session.name, session_name,
2777                         sizeof(lsm.session.name));
2778         if (ret) {
2779                 ret = -LTTNG_ERR_INVALID;
2780                 goto end;
2781         }
2782
2783         ret = lttng_ctl_ask_sessiond(&lsm, (void **) &pending);
2784         if (ret < 0) {
2785                 goto end;
2786         } else if (ret != 1) {
2787                 /* Unexpected payload size */
2788                 ret = -LTTNG_ERR_INVALID;
2789                 goto end;
2790         } else if (!pending) {
2791                 /* Internal error. */
2792                 ret = -LTTNG_ERR_UNK;
2793                 goto end;
2794         }
2795
2796         ret = (int) *pending;
2797 end:
2798         free(pending);
2799         return ret;
2800 }
2801
2802 /*
2803  * Regenerate the metadata for a session.
2804  * Return 0 on success, a negative error code on error.
2805  */
2806 int lttng_regenerate_metadata(const char *session_name)
2807 {
2808         int ret;
2809         struct lttcomm_session_msg lsm;
2810
2811         if (!session_name) {
2812                 ret = -LTTNG_ERR_INVALID;
2813                 goto end;
2814         }
2815
2816         memset(&lsm, 0, sizeof(lsm));
2817         lsm.cmd_type = LTTNG_REGENERATE_METADATA;
2818
2819         ret = lttng_strncpy(lsm.session.name, session_name,
2820                         sizeof(lsm.session.name));
2821         if (ret) {
2822                 ret = -LTTNG_ERR_INVALID;
2823                 goto end;
2824         }
2825
2826         ret = lttng_ctl_ask_sessiond(&lsm, NULL);
2827         if (ret < 0) {
2828                 goto end;
2829         }
2830
2831         ret = 0;
2832 end:
2833         return ret;
2834 }
2835
2836 /*
2837  * Deprecated, replaced by lttng_regenerate_metadata.
2838  */
2839 int lttng_metadata_regenerate(const char *session_name)
2840 {
2841         return lttng_regenerate_metadata(session_name);
2842 }
2843
2844 /*
2845  * Regenerate the statedump of a session.
2846  * Return 0 on success, a negative error code on error.
2847  */
2848 int lttng_regenerate_statedump(const char *session_name)
2849 {
2850         int ret;
2851         struct lttcomm_session_msg lsm;
2852
2853         if (!session_name) {
2854                 ret = -LTTNG_ERR_INVALID;
2855                 goto end;
2856         }
2857
2858         memset(&lsm, 0, sizeof(lsm));
2859         lsm.cmd_type = LTTNG_REGENERATE_STATEDUMP;
2860
2861         ret = lttng_strncpy(lsm.session.name, session_name,
2862                         sizeof(lsm.session.name));
2863         if (ret) {
2864                 ret = -LTTNG_ERR_INVALID;
2865                 goto end;
2866         }
2867
2868         ret = lttng_ctl_ask_sessiond(&lsm, NULL);
2869         if (ret < 0) {
2870                 goto end;
2871         }
2872
2873         ret = 0;
2874 end:
2875         return ret;
2876 }
2877
2878 int lttng_register_trigger(struct lttng_trigger *trigger)
2879 {
2880         int ret;
2881         struct lttcomm_session_msg lsm;
2882         struct lttng_dynamic_buffer buffer;
2883
2884         lttng_dynamic_buffer_init(&buffer);
2885         if (!trigger) {
2886                 ret = -LTTNG_ERR_INVALID;
2887                 goto end;
2888         }
2889
2890         if (!lttng_trigger_validate(trigger)) {
2891                 ret = -LTTNG_ERR_INVALID_TRIGGER;
2892                 goto end;
2893         }
2894
2895         ret = lttng_trigger_serialize(trigger, &buffer);
2896         if (ret < 0) {
2897                 ret = -LTTNG_ERR_UNK;
2898                 goto end;
2899         }
2900
2901         memset(&lsm, 0, sizeof(lsm));
2902         lsm.cmd_type = LTTNG_REGISTER_TRIGGER;
2903         lsm.u.trigger.length = (uint32_t) buffer.size;
2904         ret = lttng_ctl_ask_sessiond_varlen_no_cmd_header(&lsm, buffer.data,
2905                         buffer.size, NULL);
2906 end:
2907         lttng_dynamic_buffer_reset(&buffer);
2908         return ret;
2909 }
2910
2911 int lttng_unregister_trigger(struct lttng_trigger *trigger)
2912 {
2913         int ret;
2914         struct lttcomm_session_msg lsm;
2915         struct lttng_dynamic_buffer buffer;
2916
2917         lttng_dynamic_buffer_init(&buffer);
2918         if (!trigger) {
2919                 ret = -LTTNG_ERR_INVALID;
2920                 goto end;
2921         }
2922
2923         if (!lttng_trigger_validate(trigger)) {
2924                 ret = -LTTNG_ERR_INVALID_TRIGGER;
2925                 goto end;
2926         }
2927
2928         ret = lttng_trigger_serialize(trigger, &buffer);
2929         if (ret < 0) {
2930                 ret = -LTTNG_ERR_UNK;
2931                 goto end;
2932         }
2933
2934         memset(&lsm, 0, sizeof(lsm));
2935         lsm.cmd_type = LTTNG_UNREGISTER_TRIGGER;
2936         lsm.u.trigger.length = (uint32_t) buffer.size;
2937         ret = lttng_ctl_ask_sessiond_varlen_no_cmd_header(&lsm, buffer.data,
2938                         buffer.size, NULL);
2939 end:
2940         lttng_dynamic_buffer_reset(&buffer);
2941         return ret;
2942 }
2943
2944 /*
2945  * lib constructor.
2946  */
2947 static void __attribute__((constructor)) init(void)
2948 {
2949         /* Set default session group */
2950         lttng_set_tracing_group(DEFAULT_TRACING_GROUP);
2951 }
2952
2953 /*
2954  * lib destructor.
2955  */
2956 static void __attribute__((destructor)) lttng_ctl_exit(void)
2957 {
2958         free(tracing_group);
2959 }