src/bin/lttng/commands/create.c

   1 /*
   2  * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License, version 2 only,
   6  * as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  16  */
  17
  18 #define _LGPL_SOURCE
  19 #include <assert.h>
  20 #include <ctype.h>
  21 #include <popt.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <sys/stat.h>
  26 #include <sys/types.h>
  27 #include <time.h>
  28 #include <unistd.h>
  29 #include <signal.h>
  30 #include <sys/wait.h>
  31
  32 #include <common/mi-lttng.h>
  33
  34 #include "../command.h"
  35 #include "../utils.h"
  36
  37 #include <common/defaults.h>
  38 #include <common/sessiond-comm/sessiond-comm.h>
  39 #include <common/uri.h>
  40 #include <common/utils.h>
  41 #include <lttng/snapshot.h>
  42
  43 static char *opt_output_path;
  44 static char *opt_session_name;
  45 static char *opt_url;
  46 static char *opt_ctrl_url;
  47 static char *opt_data_url;
  48 static char *opt_shm_path;
  49 static int opt_no_consumer;
  50 static int opt_no_output;
  51 static int opt_snapshot;
  52 static unsigned int opt_live_timer;
  53
  54 enum {
  55         OPT_HELP = 1,
  56         OPT_LIST_OPTIONS,
  57         OPT_LIVE_TIMER,
  58 };
  59
  60 static struct mi_writer *writer;
  61
  62 static struct poptOption long_options[] = {
  63         /* longName, shortName, argInfo, argPtr, value, descrip, argDesc */
  64         {"help", 'h', POPT_ARG_NONE, NULL, OPT_HELP, NULL, NULL},
  65         {"output", 'o', POPT_ARG_STRING, &opt_output_path, 0, NULL, NULL},
  66         {"list-options", 0, POPT_ARG_NONE, NULL, OPT_LIST_OPTIONS, NULL, NULL},
  67         {"set-url",        'U', POPT_ARG_STRING, &opt_url, 0, 0, 0},
  68         {"ctrl-url",       'C', POPT_ARG_STRING, &opt_ctrl_url, 0, 0, 0},
  69         {"data-url",       'D', POPT_ARG_STRING, &opt_data_url, 0, 0, 0},
  70         {"no-output",       0, POPT_ARG_VAL, &opt_no_output, 1, 0, 0},
  71         {"no-consumer",     0, POPT_ARG_VAL, &opt_no_consumer, 1, 0, 0},
  72         {"snapshot",        0, POPT_ARG_VAL, &opt_snapshot, 1, 0, 0},
  73         {"live",            0, POPT_ARG_INT | POPT_ARGFLAG_OPTIONAL, 0, OPT_LIVE_TIMER, 0, 0},
  74         {"shm-path",        0, POPT_ARG_STRING, &opt_shm_path, 0, 0, 0},
  75         {0, 0, 0, 0, 0, 0, 0}
  76 };
  77
  78 /*
  79  * Please have a look at src/lib/lttng-ctl/lttng-ctl.c for more information on
  80  * why this declaration exists and used ONLY in for this command.
  81  */
  82 extern int _lttng_create_session_ext(const char *name, const char *url,
  83                 const char *datetime);
  84
  85 /*
  86  * Retrieve the created session and mi output it based on provided argument
  87  * This is currently a summary of what was pretty printed and is subject to
  88  * enhancements.
  89  */
  90 static int mi_created_session(const char *session_name)
  91 {
  92         int ret, i, count, found;
  93         struct lttng_session *sessions;
  94
  95         /* session_name should not be null */
  96         assert(session_name);
  97         assert(writer);
  98
  99         count = lttng_list_sessions(&sessions);
 100         if (count < 0) {
 101                 ret = count;
 102                 ERR("%s", lttng_strerror(ret));
 103                 goto error;
 104         }
 105
 106         if (count == 0) {
 107                 ERR("Error session creation failed: session %s not found", session_name);
 108                 ret = -LTTNG_ERR_SESS_NOT_FOUND;
 109                 goto end;
 110         }
 111
 112         found = 0;
 113         for (i = 0; i < count; i++) {
 114                 if (strncmp(sessions[i].name, session_name, NAME_MAX) == 0) {
 115                         found = 1;
 116                         ret = mi_lttng_session(writer, &sessions[i], 0);
 117                         if (ret) {
 118                                 goto error;
 119                         }
 120                         break;
 121                 }
 122         }
 123
 124         if (!found) {
 125                 ret = -LTTNG_ERR_SESS_NOT_FOUND;
 126         } else {
 127                 ret = CMD_SUCCESS;
 128         }
 129
 130 error:
 131         free(sessions);
 132 end:
 133         return ret;
 134 }
 135
 136 /*
 137  * For a session name, set the consumer URLs.
 138  */
 139 static int set_consumer_url(const char *session_name, const char *ctrl_url,
 140                 const char *data_url)
 141 {
 142         int ret;
 143         struct lttng_handle *handle;
 144         struct lttng_domain dom;
 145
 146         assert(session_name);
 147
 148         /*
 149          * Set handle with the session name and the domain set to 0. This means to
 150          * the session daemon that the next action applies on the tracing session
 151          * rather then the domain specific session.
 152          */
 153         memset(&dom, 0, sizeof(dom));
 154
 155         handle = lttng_create_handle(session_name, &dom);
 156         if (handle == NULL) {
 157                 ret = CMD_FATAL;
 158                 goto error;
 159         }
 160
 161         ret = lttng_set_consumer_url(handle, ctrl_url, data_url);
 162         if (ret < 0) {
 163                 goto error;
 164         }
 165
 166         if (ctrl_url) {
 167                 MSG("Control URL %s set for session %s", ctrl_url, session_name);
 168         }
 169
 170         if (data_url) {
 171                 MSG("Data URL %s set for session %s", data_url, session_name);
 172         }
 173
 174 error:
 175         lttng_destroy_handle(handle);
 176         return ret;
 177 }
 178
 179 static int add_snapshot_output(const char *session_name, const char *ctrl_url,
 180                 const char *data_url)
 181 {
 182         int ret;
 183         struct lttng_snapshot_output *output = NULL;
 184
 185         assert(session_name);
 186
 187         output = lttng_snapshot_output_create();
 188         if (!output) {
 189                 ret = CMD_FATAL;
 190                 goto error_create;
 191         }
 192
 193         if (ctrl_url) {
 194                 ret = lttng_snapshot_output_set_ctrl_url(ctrl_url, output);
 195                 if (ret < 0) {
 196                         goto error;
 197                 }
 198         }
 199
 200         if (data_url) {
 201                 ret = lttng_snapshot_output_set_data_url(data_url, output);
 202                 if (ret < 0) {
 203                         goto error;
 204                 }
 205         }
 206
 207         /* This call, if successful, populates the id of the output object. */
 208         ret = lttng_snapshot_add_output(session_name, output);
 209         if (ret < 0) {
 210                 goto error;
 211         }
 212
 213 error:
 214         lttng_snapshot_output_destroy(output);
 215 error_create:
 216         return ret;
 217 }
 218
 219 /*
 220  *  Create a tracing session.
 221  *  If no name is specified, a default name is generated.
 222  *
 223  *  Returns one of the CMD_* result constants.
 224  */
 225 static int create_session(void)
 226 {
 227         int ret;
 228         char *session_name = NULL, *traces_path = NULL, *alloc_path = NULL;
 229         char *alloc_url = NULL, *url = NULL, datetime[16];
 230         char session_name_date[NAME_MAX + 17], *print_str_url = NULL;
 231         time_t rawtime;
 232         struct tm *timeinfo;
 233         char shm_path[PATH_MAX] = "";
 234
 235         /* Get date and time for automatic session name/path */
 236         time(&rawtime);
 237         timeinfo = localtime(&rawtime);
 238         strftime(datetime, sizeof(datetime), "%Y%m%d-%H%M%S", timeinfo);
 239
 240         /* Auto session name creation */
 241         if (opt_session_name == NULL) {
 242                 ret = snprintf(session_name_date, sizeof(session_name_date),
 243                                 DEFAULT_SESSION_NAME "-%s", datetime);
 244                 if (ret < 0) {
 245                         PERROR("snprintf session name");
 246                         goto error;
 247                 }
 248                 session_name = session_name_date;
 249                 DBG("Auto session name set to %s", session_name_date);
 250         } else {
 251                 if (strlen(opt_session_name) > NAME_MAX) {
 252                         ERR("Session name too long. Length must be lower or equal to %d",
 253                                         NAME_MAX);
 254                         ret = LTTNG_ERR_SESSION_FAIL;
 255                         goto error;
 256                 }
 257                 /*
 258                  * Check if the session name begins with "auto-" or is exactly "auto".
 259                  * Both are reserved for the default session name. See bug #449 to
 260                  * understand why we need to check both here.
 261                  */
 262                 if ((strncmp(opt_session_name, DEFAULT_SESSION_NAME "-",
 263                                         strlen(DEFAULT_SESSION_NAME) + 1) == 0) ||
 264                                 (strncmp(opt_session_name, DEFAULT_SESSION_NAME,
 265                                         strlen(DEFAULT_SESSION_NAME)) == 0 &&
 266                                 strlen(opt_session_name) == strlen(DEFAULT_SESSION_NAME))) {
 267                         ERR("%s is a reserved keyword for default session(s)",
 268                                         DEFAULT_SESSION_NAME);
 269                         ret = CMD_ERROR;
 270                         goto error;
 271                 }
 272                 session_name = opt_session_name;
 273                 ret = snprintf(session_name_date, sizeof(session_name_date),
 274                                 "%s-%s", session_name, datetime);
 275                 if (ret < 0) {
 276                         PERROR("snprintf session name");
 277                         goto error;
 278                 }
 279         }
 280
 281         if ((!opt_ctrl_url && opt_data_url) || (opt_ctrl_url && !opt_data_url)) {
 282                 ERR("You need both control and data URL.");
 283                 ret = CMD_ERROR;
 284                 goto error;
 285         }
 286
 287         if (opt_output_path != NULL) {
 288                 traces_path = utils_expand_path(opt_output_path);
 289                 if (traces_path == NULL) {
 290                         ret = CMD_ERROR;
 291                         goto error;
 292                 }
 293
 294                 /* Create URL string from the local file system path */
 295                 ret = asprintf(&alloc_url, "file://%s", traces_path);
 296                 if (ret < 0) {
 297                         PERROR("asprintf url path");
 298                         ret = CMD_FATAL;
 299                         goto error;
 300                 }
 301                 /* URL to use in the lttng_create_session() call */
 302                 url = alloc_url;
 303                 print_str_url = traces_path;
 304         } else if (opt_url) { /* Handling URL (-U opt) */
 305                 url = opt_url;
 306                 print_str_url = url;
 307         } else if (opt_data_url && opt_ctrl_url) {
 308                 /*
 309                  * With both control and data, we'll be setting the consumer URL after
 310                  * session creation thus use no URL.
 311                  */
 312                 url = NULL;
 313         } else if (!opt_no_output) {
 314                 char *tmp_path;
 315
 316                 /* Auto output path */
 317                 tmp_path = utils_get_home_dir();
 318                 if (tmp_path == NULL) {
 319                         ERR("HOME path not found.\n \
 320                                         Please specify an output path using -o, --output PATH");
 321                         ret = CMD_FATAL;
 322                         goto error;
 323                 }
 324                 alloc_path = strdup(tmp_path);
 325                 if (!alloc_path) {
 326                         PERROR("allocating alloc_path");
 327                         ret = CMD_FATAL;
 328                         goto error;
 329                 }
 330                 ret = asprintf(&alloc_url,
 331                                 "file://%s/" DEFAULT_TRACE_DIR_NAME "/%s",
 332                                 alloc_path, session_name_date);
 333                 if (ret < 0) {
 334                         PERROR("asprintf trace dir name");
 335                         ret = CMD_FATAL;
 336                         goto error;
 337                 }
 338
 339                 url = alloc_url;
 340                 print_str_url = alloc_url + strlen("file://");
 341         } else {
 342                 /* No output means --no-output or --snapshot mode. */
 343                 url = NULL;
 344         }
 345
 346         /* Use default live URL if NO url is/are found. */
 347         if ((opt_live_timer && !opt_url) && (opt_live_timer && !opt_data_url)) {
 348                 ret = asprintf(&alloc_url, "net://127.0.0.1");
 349                 if (ret < 0) {
 350                         PERROR("asprintf default live URL");
 351                         ret = CMD_FATAL;
 352                         goto error;
 353                 }
 354                 url = alloc_url;
 355                 print_str_url = url;
 356         }
 357
 358         if (opt_snapshot && opt_live_timer) {
 359                 ERR("Snapshot and live modes are mutually exclusive.");
 360                 ret = CMD_ERROR;
 361                 goto error;
 362         }
 363
 364         if (opt_snapshot) {
 365                 /* No output by default. */
 366                 const char *snapshot_url = NULL;
 367
 368                 if (opt_url) {
 369                         snapshot_url = url;
 370                 } else if (!opt_data_url && !opt_ctrl_url) {
 371                         /* This is the session path that we need to use as output. */
 372                         snapshot_url = url;
 373                 }
 374                 ret = lttng_create_session_snapshot(session_name, snapshot_url);
 375         } else if (opt_live_timer) {
 376                 const char *pathname;
 377
 378                 if (opt_relayd_path) {
 379                         pathname = opt_relayd_path;
 380                 } else {
 381                         pathname = INSTALL_BIN_PATH "/lttng-relayd";
 382                 }
 383                 if (!opt_url && !opt_data_url && !check_relayd() &&
 384                                 spawn_relayd(pathname, 0) < 0) {
 385                         goto error;
 386                 }
 387                 ret = lttng_create_session_live(session_name, url, opt_live_timer);
 388         } else {
 389                 ret = _lttng_create_session_ext(session_name, url, datetime);
 390         }
 391         if (ret < 0) {
 392                 /* Don't set ret so lttng can interpret the sessiond error. */
 393                 switch (-ret) {
 394                 case LTTNG_ERR_EXIST_SESS:
 395                         WARN("Session %s already exists", session_name);
 396                         break;
 397                 default:
 398                         break;
 399                 }
 400                 goto error;
 401         }
 402
 403         if (opt_ctrl_url && opt_data_url) {
 404                 if (opt_snapshot) {
 405                         ret = add_snapshot_output(session_name, opt_ctrl_url,
 406                                         opt_data_url);
 407                 } else {
 408                         /* Setting up control URI (-C or/and -D opt) */
 409                         ret = set_consumer_url(session_name, opt_ctrl_url, opt_data_url);
 410                 }
 411                 if (ret < 0) {
 412                         /* Destroy created session because the URL are not valid. */
 413                         lttng_destroy_session(session_name);
 414                         goto error;
 415                 }
 416         }
 417
 418         if (opt_shm_path) {
 419                 ret = snprintf(shm_path, sizeof(shm_path),
 420                                 "%s/%s", opt_shm_path, session_name_date);
 421                 if (ret < 0) {
 422                         PERROR("snprintf shm_path");
 423                         goto error;
 424                 }
 425
 426                 ret = lttng_set_session_shm_path(session_name, shm_path);
 427                 if (ret < 0) {
 428                         lttng_destroy_session(session_name);
 429                         goto error;
 430                 }
 431         }
 432
 433         MSG("Session %s created.", session_name);
 434         if (print_str_url && !opt_snapshot) {
 435                 MSG("Traces will be written in %s", print_str_url);
 436
 437                 if (opt_live_timer) {
 438                         MSG("Live timer set to %u usec", opt_live_timer);
 439                 }
 440         } else if (opt_snapshot) {
 441                 if (print_str_url) {
 442                         MSG("Default snapshot output set to: %s", print_str_url);
 443                 }
 444                 MSG("Snapshot mode set. Every channel enabled for that session will "
 445                                 "be set in overwrite mode and mmap output.");
 446         }
 447         if (opt_shm_path) {
 448                 MSG("Session %s set to shm_path: %s.", session_name,
 449                         shm_path);
 450         }
 451
 452         /* Mi output */
 453         if (lttng_opt_mi) {
 454                 ret = mi_created_session(session_name);
 455                 if (ret) {
 456                         ret = CMD_ERROR;
 457                         goto error;
 458                 }
 459         }
 460
 461         /* Init lttng session config */
 462         ret = config_init(session_name);
 463         if (ret < 0) {
 464                 ret = CMD_ERROR;
 465                 goto error;
 466         }
 467
 468         ret = CMD_SUCCESS;
 469
 470 error:
 471         free(alloc_url);
 472         free(traces_path);
 473         free(alloc_path);
 474
 475         if (ret < 0) {
 476                 ERR("%s", lttng_strerror(ret));
 477         }
 478         return ret;
 479 }
 480
 481 /*
 482  *  spawn_sessiond
 483  *
 484  *  Spawn a session daemon by forking and execv.
 485  */
 486 static int spawn_sessiond(char *pathname)
 487 {
 488         int ret = 0;
 489         pid_t pid;
 490
 491         MSG("Spawning a session daemon");
 492         pid = fork();
 493         if (pid == 0) {
 494                 /*
 495                  * Spawn session daemon in daemon mode.
 496                  */
 497                 execlp(pathname, "lttng-sessiond",
 498                                 "--daemonize", NULL);
 499                 /* execlp only returns if error happened */
 500                 if (errno == ENOENT) {
 501                         ERR("No session daemon found. Use --sessiond-path.");
 502                 } else {
 503                         PERROR("execlp");
 504                 }
 505                 kill(getppid(), SIGTERM);       /* wake parent */
 506                 exit(EXIT_FAILURE);
 507         } else if (pid > 0) {
 508                 /*
 509                  * In daemon mode (--daemonize), sessiond only exits when
 510                  * it's ready to accept commands.
 511                  */
 512                 for (;;) {
 513                         int status;
 514                         pid_t wait_pid_ret = waitpid(pid, &status, 0);
 515
 516                         if (wait_pid_ret < 0) {
 517                                 if (errno == EINTR) {
 518                                         continue;
 519                                 }
 520                                 PERROR("waitpid");
 521                                 ret = -errno;
 522                                 goto end;
 523                         }
 524
 525                         if (WIFSIGNALED(status)) {
 526                                 ERR("Session daemon was killed by signal %d",
 527                                                 WTERMSIG(status));
 528                                 ret = -1;
 529                                 goto end;
 530                         } else if (WIFEXITED(status)) {
 531                                 DBG("Session daemon terminated normally (exit status: %d)",
 532                                                 WEXITSTATUS(status));
 533
 534                                 if (WEXITSTATUS(status) != 0) {
 535                                         ERR("Session daemon terminated with an error (exit status: %d)",
 536                                                         WEXITSTATUS(status));
 537                                         ret = -1;
 538                                         goto end;
 539                                 }
 540                                 break;
 541                         }
 542                 }
 543
 544                 goto end;
 545         } else {
 546                 PERROR("fork");
 547                 ret = -1;
 548                 goto end;
 549         }
 550
 551 end:
 552         return ret;
 553 }
 554
 555 /*
 556  *  launch_sessiond
 557  *
 558  *  Check if the session daemon is available using
 559  *  the liblttngctl API for the check. If not, try to
 560  *  spawn a daemon.
 561  */
 562 static int launch_sessiond(void)
 563 {
 564         int ret;
 565         char *pathname = NULL;
 566
 567         ret = lttng_session_daemon_alive();
 568         if (ret) {
 569                 /* Sessiond is alive, not an error */
 570                 ret = 0;
 571                 goto end;
 572         }
 573
 574         /* Try command line option path */
 575         pathname = opt_sessiond_path;
 576
 577         /* Try LTTNG_SESSIOND_PATH env variable */
 578         if (pathname == NULL) {
 579                 pathname = getenv(DEFAULT_SESSIOND_PATH_ENV);
 580         }
 581
 582         /* Try with configured path */
 583         if (pathname == NULL) {
 584                 if (CONFIG_SESSIOND_BIN[0] != '\0') {
 585                         pathname = CONFIG_SESSIOND_BIN;
 586                 }
 587         }
 588
 589         /* Try the default path */
 590         if (pathname == NULL) {
 591                 pathname = INSTALL_BIN_PATH "/lttng-sessiond";
 592         }
 593
 594         DBG("Session daemon binary path: %s", pathname);
 595
 596         /* Check existence and permissions */
 597         ret = access(pathname, F_OK | X_OK);
 598         if (ret < 0) {
 599                 ERR("No such file or access denied: %s", pathname);
 600                 goto end;
 601         }
 602
 603         ret = spawn_sessiond(pathname);
 604 end:
 605         if (ret) {
 606                 ERR("Problem occurred while launching session daemon (%s)",
 607                                 pathname);
 608         }
 609         return ret;
 610 }
 611
 612 /*
 613  *  The 'create <options>' first level command
 614  *
 615  *  Returns one of the CMD_* result constants.
 616  */
 617 int cmd_create(int argc, const char **argv)
 618 {
 619         int opt, ret = CMD_SUCCESS, command_ret = CMD_SUCCESS, success = 1;
 620         char *opt_arg = NULL;
 621         static poptContext pc;
 622
 623         pc = poptGetContext(NULL, argc, argv, long_options, 0);
 624         poptReadDefaultConfig(pc, 0);
 625
 626         while ((opt = poptGetNextOpt(pc)) != -1) {
 627                 switch (opt) {
 628                 case OPT_HELP:
 629                         SHOW_HELP();
 630                         goto end;
 631                 case OPT_LIST_OPTIONS:
 632                         list_cmd_options(stdout, long_options);
 633                         goto end;
 634                 case OPT_LIVE_TIMER:
 635                 {
 636                         unsigned long v;
 637
 638                         errno = 0;
 639                         opt_arg = poptGetOptArg(pc);
 640                         if (!opt_arg) {
 641                                 /* Set up default values. */
 642                                 opt_live_timer = (uint32_t) DEFAULT_LTTNG_LIVE_TIMER;
 643                                 DBG("Session live timer interval set to default value %d",
 644                                                 opt_live_timer);
 645                                 break;
 646                         }
 647
 648                         v = strtoul(opt_arg, NULL, 0);
 649                         if (errno != 0 || !isdigit(opt_arg[0])) {
 650                                 ERR("Wrong value in --live parameter: %s", opt_arg);
 651                                 ret = CMD_ERROR;
 652                                 goto end;
 653                         }
 654                         if (v != (uint32_t) v) {
 655                                 ERR("32-bit overflow in --live parameter: %s", opt_arg);
 656                                 ret = CMD_ERROR;
 657                                 goto end;
 658                         }
 659                         if (v == 0) {
 660                                 ERR("Live timer interval must be greater than zero");
 661                                 ret = CMD_ERROR;
 662                                 goto end;
 663                         }
 664                         opt_live_timer = (uint32_t) v;
 665                         DBG("Session live timer interval set to %d", opt_live_timer);
 666                         break;
 667                 }
 668                 default:
 669                         ret = CMD_UNDEFINED;
 670                         goto end;
 671                 }
 672         }
 673
 674         if (opt_no_consumer) {
 675                 MSG("The option --no-consumer is obsolete. Use --no-output now.");
 676                 ret = CMD_WARNING;
 677                 goto end;
 678         }
 679
 680         /* Spawn a session daemon if needed */
 681         if (!opt_no_sessiond) {
 682                 ret = launch_sessiond();
 683                 if (ret) {
 684                         ret = CMD_ERROR;
 685                         goto end;
 686                 }
 687         }
 688
 689         /* MI initialization */
 690         if (lttng_opt_mi) {
 691                 writer = mi_lttng_writer_create(fileno(stdout), lttng_opt_mi);
 692                 if (!writer) {
 693                         ret = -LTTNG_ERR_NOMEM;
 694                         goto end;
 695                 }
 696
 697                 /* Open command element */
 698                 ret = mi_lttng_writer_command_open(writer,
 699                                 mi_lttng_element_command_create);
 700                 if (ret) {
 701                         ret = CMD_ERROR;
 702                         goto end;
 703                 }
 704
 705                 /* Open output element */
 706                 ret = mi_lttng_writer_open_element(writer,
 707                                 mi_lttng_element_command_output);
 708                 if (ret) {
 709                         ret = CMD_ERROR;
 710                         goto end;
 711                 }
 712         }
 713         opt_session_name = (char*) poptGetArg(pc);
 714
 715         command_ret = create_session();
 716         if (command_ret) {
 717                 success = 0;
 718         }
 719
 720         if (lttng_opt_mi) {
 721                 /* Close  output element */
 722                 ret = mi_lttng_writer_close_element(writer);
 723                 if (ret) {
 724                         ret = CMD_ERROR;
 725                         goto end;
 726                 }
 727
 728                 /* Success ? */
 729                 ret = mi_lttng_writer_write_element_bool(writer,
 730                                 mi_lttng_element_command_success, success);
 731                 if (ret) {
 732                         ret = CMD_ERROR;
 733                         goto end;
 734                 }
 735
 736                 /* Command element close */
 737                 ret = mi_lttng_writer_command_close(writer);
 738                 if (ret) {
 739                         ret = CMD_ERROR;
 740                         goto end;
 741                 }
 742         }
 743
 744 end:
 745         /* Mi clean-up */
 746         if (writer && mi_lttng_writer_destroy(writer)) {
 747                 /* Preserve original error code */
 748                 ret = ret ? ret : -LTTNG_ERR_MI_IO_FAIL;
 749         }
 750
 751         /* Overwrite ret if an error occurred in create_session() */
 752         ret = command_ret ? command_ret : ret;
 753
 754         poptFreeContext(pc);
 755         return ret;
 756 }