src/bin/lttng/commands/create.c

   1 /*
   2  * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
   3  * Copyright (C) 2019 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   4  *
   5  * SPDX-License-Identifier: GPL-2.0-only
   6  *
   7  */
   8
   9 #define _LGPL_SOURCE
  10 #include <assert.h>
  11 #include <ctype.h>
  12 #include <popt.h>
  13 #include <stdio.h>
  14 #include <stdlib.h>
  15 #include <string.h>
  16 #include <sys/stat.h>
  17 #include <sys/types.h>
  18 #include <common/compat/time.h>
  19 #include <unistd.h>
  20 #include <signal.h>
  21 #include <sys/wait.h>
  22
  23 #include <common/mi-lttng.h>
  24
  25 #include "../command.h"
  26 #include "../utils.h"
  27
  28 #include <common/defaults.h>
  29 #include <common/sessiond-comm/sessiond-comm.h>
  30 #include <common/uri.h>
  31 #include <common/utils.h>
  32 #include <lttng/snapshot.h>
  33 #include <lttng/session-descriptor.h>
  34
  35 static char *opt_output_path;
  36 static char *opt_session_name;
  37 static char *opt_url;
  38 static char *opt_ctrl_url;
  39 static char *opt_data_url;
  40 static char *opt_shm_path;
  41 static int opt_no_consumer;
  42 static int opt_no_output;
  43 static int opt_snapshot;
  44 static uint32_t opt_live_timer;
  45
  46 #ifdef LTTNG_EMBED_HELP
  47 static const char help_msg[] =
  48 #include <lttng-create.1.h>
  49 ;
  50 #endif
  51
  52 enum {
  53         OPT_HELP = 1,
  54         OPT_LIST_OPTIONS,
  55         OPT_LIVE_TIMER,
  56 };
  57
  58 enum output_type {
  59         OUTPUT_NONE,
  60         OUTPUT_LOCAL,
  61         OUTPUT_NETWORK,
  62         OUTPUT_UNSPECIFIED,
  63 };
  64
  65 static struct mi_writer *writer;
  66 static struct poptOption long_options[] = {
  67         /* longName, shortName, argInfo, argPtr, value, descrip, argDesc */
  68         {"help", 'h', POPT_ARG_NONE, NULL, OPT_HELP, NULL, NULL},
  69         {"output", 'o', POPT_ARG_STRING, &opt_output_path, 0, NULL, NULL},
  70         {"list-options", 0, POPT_ARG_NONE, NULL, OPT_LIST_OPTIONS, NULL, NULL},
  71         {"set-url",        'U', POPT_ARG_STRING, &opt_url, 0, 0, 0},
  72         {"ctrl-url",       'C', POPT_ARG_STRING, &opt_ctrl_url, 0, 0, 0},
  73         {"data-url",       'D', POPT_ARG_STRING, &opt_data_url, 0, 0, 0},
  74         {"no-output",       0, POPT_ARG_VAL, &opt_no_output, 1, 0, 0},
  75         {"no-consumer",     0, POPT_ARG_VAL, &opt_no_consumer, 1, 0, 0},
  76         {"snapshot",        0, POPT_ARG_VAL, &opt_snapshot, 1, 0, 0},
  77         {"live",            0, POPT_ARG_INT | POPT_ARGFLAG_OPTIONAL, 0, OPT_LIVE_TIMER, 0, 0},
  78         {"shm-path",        0, POPT_ARG_STRING, &opt_shm_path, 0, 0, 0},
  79         {0, 0, 0, 0, 0, 0, 0}
  80 };
  81
  82 /*
  83  * Retrieve the created session and mi output it based on provided argument
  84  * This is currently a summary of what was pretty printed and is subject to
  85  * enhancements.
  86  */
  87 static int mi_created_session(const char *session_name)
  88 {
  89         int ret, i, count, found;
  90         struct lttng_session *sessions;
  91
  92         /* session_name should not be null */
  93         assert(session_name);
  94         assert(writer);
  95
  96         count = lttng_list_sessions(&sessions);
  97         if (count < 0) {
  98                 ret = count;
  99                 ERR("%s", lttng_strerror(ret));
 100                 goto error;
 101         }
 102
 103         if (count == 0) {
 104                 ERR("Error session creation failed: session %s not found", session_name);
 105                 ret = -LTTNG_ERR_SESS_NOT_FOUND;
 106                 goto end;
 107         }
 108
 109         found = 0;
 110         for (i = 0; i < count; i++) {
 111                 if (strncmp(sessions[i].name, session_name, NAME_MAX) == 0) {
 112                         found = 1;
 113                         ret = mi_lttng_session(writer, &sessions[i], 0);
 114                         if (ret) {
 115                                 goto error;
 116                         }
 117                         break;
 118                 }
 119         }
 120
 121         if (!found) {
 122                 ret = -LTTNG_ERR_SESS_NOT_FOUND;
 123         } else {
 124                 ret = CMD_SUCCESS;
 125         }
 126
 127 error:
 128         free(sessions);
 129 end:
 130         return ret;
 131 }
 132
 133 static
 134 struct lttng_session_descriptor *create_session_descriptor(void)
 135 {
 136         int ret;
 137         ssize_t uri_count;
 138         enum output_type output_type;
 139         struct lttng_uri *uris = NULL;
 140         struct lttng_session_descriptor *descriptor = NULL;
 141         const char *uri_str1 = NULL, *uri_str2 = NULL;
 142         char local_output_path[LTTNG_PATH_MAX] = {};
 143
 144         if (opt_no_output) {
 145                 output_type = OUTPUT_NONE;
 146         } else if (opt_output_path) {
 147                 char *expanded_output_path;
 148
 149                 output_type = OUTPUT_LOCAL;
 150                 expanded_output_path = utils_expand_path(opt_output_path);
 151                 if (!expanded_output_path) {
 152                         ERR("Failed to expand output path.");
 153                         goto end;
 154                 }
 155                 ret = lttng_strncpy(local_output_path, expanded_output_path,
 156                                 sizeof(local_output_path));
 157                 free(expanded_output_path);
 158                 if (ret) {
 159                         ERR("Output path exceeds the maximal supported length (%zu bytes)",
 160                                         sizeof(local_output_path));
 161                         goto end;
 162                 }
 163         } else if (opt_url || opt_ctrl_url) {
 164                 uri_str1 = opt_ctrl_url ? opt_ctrl_url : opt_url;
 165                 uri_str2 = opt_data_url;
 166
 167                 uri_count = uri_parse_str_urls(uri_str1, uri_str2, &uris);
 168                 if (uri_count != 1 && uri_count != 2) {
 169                         ERR("Unrecognized URL format.");
 170                         goto end;
 171                 }
 172
 173                 switch (uri_count) {
 174                 case 1:
 175                         output_type = OUTPUT_LOCAL;
 176                         if (uris[0].dtype != LTTNG_DST_PATH) {
 177                                 ERR("Unrecognized URL format.");
 178                                 goto end;
 179                         }
 180                         ret = lttng_strncpy(local_output_path, uris[0].dst.path,
 181                                         sizeof(local_output_path));
 182                         if (ret) {
 183                                 ERR("Output path exceeds the maximal supported length (%zu bytes)",
 184                                                 sizeof(local_output_path));
 185                         }
 186                         break;
 187                 case 2:
 188                         output_type = OUTPUT_NETWORK;
 189                         break;
 190                 default:
 191                         /* Already checked. */
 192                         abort();
 193                 }
 194         } else {
 195                 output_type = OUTPUT_UNSPECIFIED;
 196         }
 197
 198         if (opt_snapshot) {
 199                 /* Snapshot session. */
 200                 switch (output_type) {
 201                 case OUTPUT_UNSPECIFIED:
 202                 case OUTPUT_LOCAL:
 203                         descriptor = lttng_session_descriptor_snapshot_local_create(
 204                                         opt_session_name,
 205                                         output_type == OUTPUT_LOCAL ?
 206                                                 local_output_path : NULL);
 207                         break;
 208                 case OUTPUT_NONE:
 209                         descriptor = lttng_session_descriptor_snapshot_create(
 210                                         opt_session_name);
 211                         break;
 212                 case OUTPUT_NETWORK:
 213                         descriptor = lttng_session_descriptor_snapshot_network_create(
 214                                         opt_session_name, uri_str1, uri_str2);
 215                         break;
 216                 default:
 217                         abort();
 218                 }
 219         } else if (opt_live_timer) {
 220                 /* Live session. */
 221                 if (output_type != OUTPUT_UNSPECIFIED &&
 222                                 output_type != OUTPUT_NETWORK) {
 223                         ERR("Unsupported output type specified for live session.");
 224                         goto end;
 225                 }
 226                 descriptor = lttng_session_descriptor_live_network_create(
 227                                 opt_session_name, uri_str1, uri_str2,
 228                                 opt_live_timer);
 229         } else {
 230                 /* Regular session. */
 231                 switch (output_type) {
 232                 case OUTPUT_UNSPECIFIED:
 233                 case OUTPUT_LOCAL:
 234                         descriptor = lttng_session_descriptor_local_create(
 235                                         opt_session_name,
 236                                         output_type == OUTPUT_LOCAL ?
 237                                                 local_output_path : NULL);
 238                         break;
 239                 case OUTPUT_NONE:
 240                         descriptor = lttng_session_descriptor_create(
 241                                         opt_session_name);
 242                         break;
 243                 case OUTPUT_NETWORK:
 244                         descriptor = lttng_session_descriptor_network_create(
 245                                         opt_session_name, uri_str1, uri_str2);
 246                         break;
 247                 default:
 248                         abort();
 249                 }
 250         }
 251         if (!descriptor) {
 252                 ERR("Failed to initialize session creation command.");
 253         } else {
 254                 /*
 255                  * Auto-launch the relay daemon when a live session
 256                  * is created using default URLs.
 257                  */
 258                 if (!opt_url && !opt_ctrl_url && !opt_data_url &&
 259                                 opt_live_timer && !check_relayd()) {
 260                         int ret;
 261                         const char *pathname = opt_relayd_path ? :
 262                                         INSTALL_BIN_PATH "/lttng-relayd";
 263
 264                         ret = spawn_relayd(pathname, 0);
 265                         if (ret < 0) {
 266                                 lttng_session_descriptor_destroy(descriptor);
 267                                 descriptor = NULL;
 268                         }
 269                 }
 270         }
 271 end:
 272         free(uris);
 273         return descriptor;
 274 }
 275
 276 /*
 277  *  Create a tracing session.
 278  *  If no name is specified, a default name is generated.
 279  *
 280  *  Returns one of the CMD_* result constants.
 281  */
 282 static int create_session(void)
 283 {
 284         int ret, i;
 285         char shm_path[LTTNG_PATH_MAX] = {};
 286         struct lttng_session_descriptor *session_descriptor = NULL;
 287         enum lttng_session_descriptor_status descriptor_status;
 288         enum lttng_error_code ret_code;
 289         struct lttng_session *sessions = NULL;
 290         const struct lttng_session *created_session = NULL;
 291         const char *created_session_name;
 292
 293         /* Validate options. */
 294         if (opt_session_name) {
 295                 if (strlen(opt_session_name) > NAME_MAX) {
 296                         ERR("Session name too long. Length must be lower or equal to %d",
 297                                         NAME_MAX);
 298                         ret = CMD_ERROR;
 299                         goto error;
 300                 }
 301                 /*
 302                  * Check if the session name begins with "auto-" or is exactly "auto".
 303                  * Both are reserved for the default session name. See bug #449 to
 304                  * understand why we need to check both here.
 305                  */
 306                 if ((strncmp(opt_session_name, DEFAULT_SESSION_NAME "-",
 307                                         strlen(DEFAULT_SESSION_NAME) + 1) == 0) ||
 308                                 (strncmp(opt_session_name, DEFAULT_SESSION_NAME,
 309                                         strlen(DEFAULT_SESSION_NAME)) == 0 &&
 310                                 strlen(opt_session_name) == strlen(DEFAULT_SESSION_NAME))) {
 311                         ERR("%s is a reserved keyword for default session(s)",
 312                                         DEFAULT_SESSION_NAME);
 313                         ret = CMD_ERROR;
 314                         goto error;
 315                 }
 316         }
 317
 318         if (opt_snapshot && opt_live_timer) {
 319                 ERR("Snapshot and live modes are mutually exclusive.");
 320                 ret = CMD_ERROR;
 321                 goto error;
 322         }
 323
 324         if ((!opt_ctrl_url && opt_data_url) || (opt_ctrl_url && !opt_data_url)) {
 325                 ERR("Both control and data URLs must be specified.");
 326                 ret = CMD_ERROR;
 327                 goto error;
 328         }
 329
 330         session_descriptor = create_session_descriptor();
 331         if (!session_descriptor) {
 332                 ret = CMD_ERROR;
 333                 goto error;
 334         }
 335         ret_code = lttng_create_session_ext(session_descriptor);
 336         if (ret_code != LTTNG_OK) {
 337                 ERR("%s", lttng_strerror(-ret_code));
 338                 ret = CMD_ERROR;
 339                 goto error;
 340         }
 341
 342         descriptor_status = lttng_session_descriptor_get_session_name(
 343                 session_descriptor, &created_session_name);
 344         if (descriptor_status != LTTNG_SESSION_DESCRIPTOR_STATUS_OK) {
 345                 ERR("Failed to obtain created session name");
 346                 ret = CMD_ERROR;
 347                 goto error;
 348         }
 349
 350         ret = lttng_list_sessions(&sessions);
 351         if (ret < 0) {
 352                 ERR("Failed to fetch properties of created session: %s",
 353                                 lttng_strerror(ret));
 354                 ret = CMD_ERROR;
 355                 goto error;
 356         }
 357         for (i = 0; i < ret; i++) {
 358                 if (!strcmp(created_session_name, sessions[i].name)) {
 359                         created_session = &sessions[i];
 360                         break;
 361                 }
 362         }
 363         if (!created_session) {
 364                 ERR("Failed to fetch properties of created session");
 365                 ret = CMD_ERROR;
 366                 goto error;
 367         }
 368
 369         if (opt_shm_path) {
 370                 char datetime_suffix[17] = {};
 371
 372                 /*
 373                  * An auto-generated session name already includes the creation
 374                  * timestamp.
 375                  */
 376                 if (opt_session_name) {
 377                         uint64_t creation_time;
 378                         struct tm *timeinfo;
 379                         time_t creation_time_t;
 380                         size_t strftime_ret;
 381
 382                         ret_code = lttng_session_get_creation_time(
 383                                         created_session,
 384                                         &creation_time);
 385                         if (ret_code != LTTNG_OK) {
 386                                 ERR("%s", lttng_strerror(-ret_code));
 387                                 ret = CMD_ERROR;
 388                                 goto error;
 389                         }
 390                         creation_time_t = (time_t) creation_time;
 391                         timeinfo = localtime(&creation_time_t);
 392                         if (!timeinfo) {
 393                                 PERROR("Failed to interpret session creation time");
 394                                 ret = CMD_ERROR;
 395                                 goto error;
 396                         }
 397                         strftime_ret = strftime(datetime_suffix,
 398                                         sizeof(datetime_suffix),
 399                                         "-%Y%m%d-%H%M%S", timeinfo);
 400                         if (strftime_ret == 0) {
 401                                 ERR("Failed to format session creation time.");
 402                                 ret = CMD_ERROR;
 403                                 goto error;
 404                         }
 405                 }
 406
 407                 ret = snprintf(shm_path, sizeof(shm_path),
 408                                 "%s/%s%s", opt_shm_path, created_session_name,
 409                                 datetime_suffix);
 410                 if (ret < 0 || ret >= sizeof(shm_path)) {
 411                         ERR("Failed to format the shared memory path.");
 412                         ret = CMD_ERROR;
 413                         goto error;
 414                 }
 415                 ret = lttng_set_session_shm_path(created_session_name,
 416                                 shm_path);
 417                 if (ret < 0) {
 418                         lttng_destroy_session(created_session_name);
 419                         ret = CMD_ERROR;
 420                         goto error;
 421                 }
 422         }
 423
 424         if (opt_snapshot) {
 425                 MSG("Snapshot session %s created.", created_session_name);
 426         } else if (opt_live_timer) {
 427                 MSG("Live session %s created.", created_session_name);
 428         } else {
 429                 MSG("Session %s created.", created_session_name);
 430         }
 431
 432         if (*created_session->path && !opt_snapshot) {
 433                 MSG("Traces will be output to %s", created_session->path);
 434
 435                 if (opt_live_timer) {
 436                         MSG("Live timer interval set to %u %s", opt_live_timer,
 437                                         USEC_UNIT);
 438                 }
 439         } else if (opt_snapshot) {
 440                 struct lttng_snapshot_output_list *list;
 441                 struct lttng_snapshot_output *iter;
 442                 char snapshot_url[LTTNG_PATH_MAX] = {};
 443
 444                 ret = lttng_snapshot_list_output(created_session_name, &list);
 445                 if (ret < 0) {
 446                         ERR("Failed to list snapshot outputs.");
 447                         ret = CMD_ERROR;
 448                         goto error;
 449                 }
 450
 451                 while ((iter = lttng_snapshot_output_list_get_next(list))) {
 452                         const char *url = NULL;
 453
 454                         url = lttng_snapshot_output_get_ctrl_url(
 455                                         iter);
 456                         ret = lttng_strncpy(snapshot_url, url,
 457                                         sizeof(snapshot_url));
 458                         if (ret) {
 459                                 snapshot_url[0] = '\0';
 460                                 ERR("Failed to retrieve snapshot output destination");
 461                         }
 462                         break;
 463                 }
 464                 lttng_snapshot_output_list_destroy(list);
 465
 466                 if (*snapshot_url) {
 467                         MSG("Default snapshot output set to %s",
 468                                         snapshot_url);
 469                 }
 470                 MSG("Every channel enabled for this session will be set to mmap output and default to overwrite mode.");
 471         }
 472         if (opt_shm_path) {
 473                 MSG("Shared memory path set to %s", shm_path);
 474         }
 475
 476         /* Mi output */
 477         if (lttng_opt_mi) {
 478                 ret = mi_created_session(created_session_name);
 479                 if (ret) {
 480                         ret = CMD_ERROR;
 481                         goto error;
 482                 }
 483         }
 484
 485         /* Init lttng session config */
 486         ret = config_init(created_session_name);
 487         if (ret < 0) {
 488                 ret = CMD_ERROR;
 489                 goto error;
 490         }
 491
 492         ret = CMD_SUCCESS;
 493 error:
 494         lttng_session_descriptor_destroy(session_descriptor);
 495         free(sessions);
 496         return ret;
 497 }
 498
 499 /*
 500  *  spawn_sessiond
 501  *
 502  *  Spawn a session daemon by forking and execv.
 503  */
 504 static int spawn_sessiond(const char *pathname)
 505 {
 506         int ret = 0;
 507         pid_t pid;
 508
 509         MSG("Spawning a session daemon");
 510         pid = fork();
 511         if (pid == 0) {
 512                 /*
 513                  * Spawn session daemon in daemon mode.
 514                  */
 515                 execlp(pathname, "lttng-sessiond",
 516                                 "--daemonize", NULL);
 517                 /* execlp only returns if error happened */
 518                 if (errno == ENOENT) {
 519                         ERR("No session daemon found. Use --sessiond-path.");
 520                 } else {
 521                         PERROR("execlp");
 522                 }
 523                 kill(getppid(), SIGTERM);       /* wake parent */
 524                 exit(EXIT_FAILURE);
 525         } else if (pid > 0) {
 526                 /*
 527                  * In daemon mode (--daemonize), sessiond only exits when
 528                  * it's ready to accept commands.
 529                  */
 530                 for (;;) {
 531                         int status;
 532                         pid_t wait_pid_ret = waitpid(pid, &status, 0);
 533
 534                         if (wait_pid_ret < 0) {
 535                                 if (errno == EINTR) {
 536                                         continue;
 537                                 }
 538                                 PERROR("waitpid");
 539                                 ret = -errno;
 540                                 goto end;
 541                         }
 542
 543                         if (WIFSIGNALED(status)) {
 544                                 ERR("Session daemon was killed by signal %d",
 545                                                 WTERMSIG(status));
 546                                 ret = -1;
 547                                 goto end;
 548                         } else if (WIFEXITED(status)) {
 549                                 DBG("Session daemon terminated normally (exit status: %d)",
 550                                                 WEXITSTATUS(status));
 551
 552                                 if (WEXITSTATUS(status) != 0) {
 553                                         ERR("Session daemon terminated with an error (exit status: %d)",
 554                                                         WEXITSTATUS(status));
 555                                         ret = -1;
 556                                         goto end;
 557                                 }
 558                                 break;
 559                         }
 560                 }
 561
 562                 goto end;
 563         } else {
 564                 PERROR("fork");
 565                 ret = -1;
 566                 goto end;
 567         }
 568
 569 end:
 570         return ret;
 571 }
 572
 573 /*
 574  *  launch_sessiond
 575  *
 576  *  Check if the session daemon is available using
 577  *  the liblttngctl API for the check. If not, try to
 578  *  spawn a daemon.
 579  */
 580 static int launch_sessiond(void)
 581 {
 582         int ret;
 583         const char *pathname = NULL;
 584
 585         ret = lttng_session_daemon_alive();
 586         if (ret) {
 587                 /* Sessiond is alive, not an error */
 588                 ret = 0;
 589                 goto end;
 590         }
 591
 592         /* Try command line option path */
 593         pathname = opt_sessiond_path;
 594
 595         /* Try LTTNG_SESSIOND_PATH env variable */
 596         if (pathname == NULL) {
 597                 pathname = getenv(DEFAULT_SESSIOND_PATH_ENV);
 598         }
 599
 600         /* Try with configured path */
 601         if (pathname == NULL) {
 602                 if (CONFIG_SESSIOND_BIN[0] != '\0') {
 603                         pathname = CONFIG_SESSIOND_BIN;
 604                 }
 605         }
 606
 607         /* Try the default path */
 608         if (pathname == NULL) {
 609                 pathname = INSTALL_BIN_PATH "/lttng-sessiond";
 610         }
 611
 612         DBG("Session daemon binary path: %s", pathname);
 613
 614         /* Check existence and permissions */
 615         ret = access(pathname, F_OK | X_OK);
 616         if (ret < 0) {
 617                 ERR("No such file or access denied: %s", pathname);
 618                 goto end;
 619         }
 620
 621         ret = spawn_sessiond(pathname);
 622 end:
 623         if (ret) {
 624                 ERR("Problem occurred while launching session daemon (%s)",
 625                                 pathname);
 626         }
 627         return ret;
 628 }
 629
 630 static
 631 int validate_url_option_combination(void)
 632 {
 633         int ret = 0;
 634         int used_count = 0;
 635
 636         used_count += !!opt_url;
 637         used_count += !!opt_output_path;
 638         used_count += (opt_data_url || opt_ctrl_url);
 639         if (used_count > 1) {
 640                 ERR("Only one of the --set-url, --ctrl-url/data-url, or --output options may be used at once.");
 641                 ret = -1;
 642         }
 643
 644         return ret;
 645 }
 646
 647 /*
 648  *  The 'create <options>' first level command
 649  *
 650  *  Returns one of the CMD_* result constants.
 651  */
 652 int cmd_create(int argc, const char **argv)
 653 {
 654         int opt, ret = CMD_SUCCESS, command_ret = CMD_SUCCESS, success = 1;
 655         char *opt_arg = NULL;
 656         const char *leftover = NULL;
 657         static poptContext pc;
 658
 659         pc = poptGetContext(NULL, argc, argv, long_options, 0);
 660         poptReadDefaultConfig(pc, 0);
 661
 662         while ((opt = poptGetNextOpt(pc)) != -1) {
 663                 switch (opt) {
 664                 case OPT_HELP:
 665                         SHOW_HELP();
 666                         goto end;
 667                 case OPT_LIST_OPTIONS:
 668                         list_cmd_options(stdout, long_options);
 669                         goto end;
 670                 case OPT_LIVE_TIMER:
 671                 {
 672                         uint64_t v;
 673
 674                         errno = 0;
 675                         opt_arg = poptGetOptArg(pc);
 676                         if (!opt_arg) {
 677                                 /* Set up default values. */
 678                                 opt_live_timer = (uint32_t) DEFAULT_LTTNG_LIVE_TIMER;
 679                                 DBG("Session live timer interval set to default value %d",
 680                                                 opt_live_timer);
 681                                 break;
 682                         }
 683
 684                         if (utils_parse_time_suffix(opt_arg, &v) < 0) {
 685                                 ERR("Wrong value for --live parameter: %s", opt_arg);
 686                                 ret = CMD_ERROR;
 687                                 goto end;
 688                         }
 689
 690                         if (v != (uint32_t) v) {
 691                                 ERR("32-bit overflow in --live parameter: %s", opt_arg);
 692                                 ret = CMD_ERROR;
 693                                 goto end;
 694                         }
 695
 696                         if (v == 0) {
 697                                 ERR("Live timer interval must be greater than zero");
 698                                 ret = CMD_ERROR;
 699                                 goto end;
 700                         }
 701
 702                         opt_live_timer = (uint32_t) v;
 703                         DBG("Session live timer interval set to %d", opt_live_timer);
 704                         break;
 705                 }
 706                 default:
 707                         ret = CMD_UNDEFINED;
 708                         goto end;
 709                 }
 710         }
 711
 712         if (opt_no_consumer) {
 713                 MSG("The option --no-consumer is obsolete. Use --no-output now.");
 714                 ret = CMD_WARNING;
 715                 goto end;
 716         }
 717
 718         ret = validate_url_option_combination();
 719         if (ret) {
 720                 ret = CMD_ERROR;
 721                 goto end;
 722         }
 723
 724         /* Spawn a session daemon if needed */
 725         if (!opt_no_sessiond) {
 726                 ret = launch_sessiond();
 727                 if (ret) {
 728                         ret = CMD_ERROR;
 729                         goto end;
 730                 }
 731         }
 732
 733         /* MI initialization */
 734         if (lttng_opt_mi) {
 735                 writer = mi_lttng_writer_create(fileno(stdout), lttng_opt_mi);
 736                 if (!writer) {
 737                         ret = -LTTNG_ERR_NOMEM;
 738                         goto end;
 739                 }
 740
 741                 /* Open command element */
 742                 ret = mi_lttng_writer_command_open(writer,
 743                                 mi_lttng_element_command_create);
 744                 if (ret) {
 745                         ret = CMD_ERROR;
 746                         goto end;
 747                 }
 748
 749                 /* Open output element */
 750                 ret = mi_lttng_writer_open_element(writer,
 751                                 mi_lttng_element_command_output);
 752                 if (ret) {
 753                         ret = CMD_ERROR;
 754                         goto end;
 755                 }
 756         }
 757         opt_session_name = (char*) poptGetArg(pc);
 758
 759         leftover = poptGetArg(pc);
 760         if (leftover) {
 761                 ERR("Unknown argument: %s", leftover);
 762                 ret = CMD_ERROR;
 763                 goto end;
 764         }
 765
 766         command_ret = create_session();
 767         if (command_ret) {
 768                 success = 0;
 769         }
 770
 771         if (lttng_opt_mi) {
 772                 /* Close  output element */
 773                 ret = mi_lttng_writer_close_element(writer);
 774                 if (ret) {
 775                         ret = CMD_ERROR;
 776                         goto end;
 777                 }
 778
 779                 /* Success ? */
 780                 ret = mi_lttng_writer_write_element_bool(writer,
 781                                 mi_lttng_element_command_success, success);
 782                 if (ret) {
 783                         ret = CMD_ERROR;
 784                         goto end;
 785                 }
 786
 787                 /* Command element close */
 788                 ret = mi_lttng_writer_command_close(writer);
 789                 if (ret) {
 790                         ret = CMD_ERROR;
 791                         goto end;
 792                 }
 793         }
 794
 795 end:
 796         /* Mi clean-up */
 797         if (writer && mi_lttng_writer_destroy(writer)) {
 798                 /* Preserve original error code */
 799                 ret = ret ? ret : -LTTNG_ERR_MI_IO_FAIL;
 800         }
 801
 802         /* Overwrite ret if an error occurred in create_session() */
 803         ret = command_ret ? command_ret : ret;
 804
 805         poptFreeContext(pc);
 806         return ret;
 807 }