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 _GNU_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
  30 #include <common/mi-lttng.h>
  31
  32 #include "../command.h"
  33 #include "../utils.h"
  34
  35 #include <common/defaults.h>
  36 #include <common/sessiond-comm/sessiond-comm.h>
  37 #include <common/uri.h>
  38 #include <common/utils.h>
  39 #include <lttng/snapshot.h>
  40
  41 static char *opt_output_path;
  42 static char *opt_session_name;
  43 static char *opt_url;
  44 static char *opt_ctrl_url;
  45 static char *opt_data_url;
  46 static int opt_no_consumer;
  47 static int opt_no_output;
  48 static int opt_snapshot;
  49 static unsigned int opt_live_timer;
  50 static int opt_disable_consumer;
  51
  52 enum {
  53         OPT_HELP = 1,
  54         OPT_LIST_OPTIONS,
  55         OPT_LIVE_TIMER,
  56 };
  57
  58 static struct mi_writer *writer;
  59
  60 static struct poptOption long_options[] = {
  61         /* longName, shortName, argInfo, argPtr, value, descrip, argDesc */
  62         {"help", 'h', POPT_ARG_NONE, NULL, OPT_HELP, NULL, NULL},
  63         {"output", 'o', POPT_ARG_STRING, &opt_output_path, 0, NULL, NULL},
  64         {"list-options", 0, POPT_ARG_NONE, NULL, OPT_LIST_OPTIONS, NULL, NULL},
  65         {"set-url",        'U', POPT_ARG_STRING, &opt_url, 0, 0, 0},
  66         {"ctrl-url",       'C', POPT_ARG_STRING, &opt_ctrl_url, 0, 0, 0},
  67         {"data-url",       'D', POPT_ARG_STRING, &opt_data_url, 0, 0, 0},
  68         {"no-output",       0, POPT_ARG_VAL, &opt_no_output, 1, 0, 0},
  69         {"no-consumer",     0, POPT_ARG_VAL, &opt_no_consumer, 1, 0, 0},
  70         {"disable-consumer", 0, POPT_ARG_VAL, &opt_disable_consumer, 1, 0, 0},
  71         {"snapshot",        0, POPT_ARG_VAL, &opt_snapshot, 1, 0, 0},
  72         {"live",            0, POPT_ARG_INT | POPT_ARGFLAG_OPTIONAL, 0, OPT_LIVE_TIMER, 0, 0},
  73         {0, 0, 0, 0, 0, 0, 0}
  74 };
  75
  76 /*
  77  * Please have a look at src/lib/lttng-ctl/lttng-ctl.c for more information on
  78  * why this declaration exists and used ONLY in for this command.
  79  */
  80 extern int _lttng_create_session_ext(const char *name, const char *url,
  81                 const char *datetime, int live_timer);
  82
  83 /*
  84  * usage
  85  */
  86 static void usage(FILE *ofp)
  87 {
  88         fprintf(ofp, "usage: lttng create [NAME] [OPTIONS] \n");
  89         fprintf(ofp, "\n");
  90         fprintf(ofp, "Without a given NAME, the default is 'auto-<yyyymmdd>-<hhmmss>'\n");
  91         fprintf(ofp, "\n");
  92         fprintf(ofp, "Options:\n");
  93         fprintf(ofp, "  -h, --help           Show this help\n");
  94         fprintf(ofp, "      --list-options   Simple listing of options\n");
  95         fprintf(ofp, "  -o, --output PATH    Specify output path for traces\n");
  96         fprintf(ofp, "      --no-output      Traces will not be outputted\n");
  97         fprintf(ofp, "      --snapshot       Set the session in snapshot mode.\n");
  98         fprintf(ofp, "                       Created in no-output mode and uses the URL,\n");
  99         fprintf(ofp, "                       if one, as the default snapshot output.\n");
 100         fprintf(ofp, "                       Every channel will be set in overwrite mode\n");
 101         fprintf(ofp, "                       and with mmap output (splice not supported).\n");
 102         fprintf(ofp, "      --live [USEC]    Set the session in live-reading mode.\n");
 103         fprintf(ofp, "                       The delay parameter in micro-seconds is the\n");
 104         fprintf(ofp, "                       maximum time the user can wait for the data\n");
 105         fprintf(ofp, "                       to be flushed. Can be set with a network\n");
 106         fprintf(ofp, "                       URL (-U or -C/-D) and must have a relayd listening.\n");
 107         fprintf(ofp, "                       By default, %u is used for the timer and the\n",
 108                                                                                         DEFAULT_LTTNG_LIVE_TIMER);
 109         fprintf(ofp, "                       network URL is set to net://127.0.0.1.\n");
 110         fprintf(ofp, "\n");
 111         fprintf(ofp, "Extended Options:\n");
 112         fprintf(ofp, "\n");
 113         fprintf(ofp, "Using these options, each API call can be controlled individually.\n");
 114         fprintf(ofp, "\n");
 115         fprintf(ofp, "  -U, --set-url=URL    Set URL destination of the trace data.\n");
 116         fprintf(ofp, "                       It is persistent for the session lifetime.\n");
 117         fprintf(ofp, "                       This will set both data and control URL.\n");
 118         fprintf(ofp, "                       You can change it with the enable-consumer cmd\n");
 119         fprintf(ofp, "  -C, --ctrl-url=URL   Set control path URL. (Must use -D also)\n");
 120         fprintf(ofp, "  -D, --data-url=URL   Set data path URL. (Must use -C also)\n");
 121         fprintf(ofp, "\n");
 122         fprintf(ofp, "Please refer to the man page (lttng(1)) for more information on network\n");
 123         fprintf(ofp, "streaming mechanisms and explanation of the control and data port\n");
 124         fprintf(ofp, "You must have a running remote lttng-relayd for network streaming\n");
 125         fprintf(ofp, "\n");
 126         fprintf(ofp, "URL format is has followed:\n");
 127         fprintf(ofp, "\n");
 128         fprintf(ofp, "  proto://[HOST|IP][:PORT1[:PORT2]][/TRACE_PATH]\n");
 129         fprintf(ofp, "\n");
 130         fprintf(ofp, "  Supported protocols are (proto):\n");
 131         fprintf(ofp, "  > file://...\n");
 132         fprintf(ofp, "    Local filesystem full path.\n");
 133         fprintf(ofp, "\n");
 134         fprintf(ofp, "  > net[6]://...\n");
 135         fprintf(ofp, "    This will use the default network transport layer which is\n");
 136         fprintf(ofp, "    TCP for both control (PORT1) and data port (PORT2).\n");
 137         fprintf(ofp, "    The default ports are respectively 5342 and 5343.\n");
 138         fprintf(ofp, "\n");
 139         fprintf(ofp, "  > tcp[6]://...\n");
 140         fprintf(ofp, "    Can only be used with -C and -D together\n");
 141         fprintf(ofp, "\n");
 142         fprintf(ofp, "NOTE: IPv6 address MUST be enclosed in brackets '[]' (rfc2732)\n");
 143         fprintf(ofp, "\n");
 144         fprintf(ofp, "Examples:\n");
 145         fprintf(ofp, "    # lttng create -U net://192.168.1.42\n");
 146         fprintf(ofp, "    Uses TCP and default ports for the given destination.\n");
 147         fprintf(ofp, "    # lttng create -U net6://[fe80::f66d:4ff:fe53:d220]\n");
 148         fprintf(ofp, "    Uses TCP, default ports and IPv6.\n");
 149         fprintf(ofp, "    # lttng create s1 -U net://myhost.com:3229\n");
 150         fprintf(ofp, "    Set the consumer to the remote HOST on port 3229 for control.\n");
 151         fprintf(ofp, "\n");
 152 }
 153
 154 /*
 155  * Retrieve the created session and
 156  * mi output it of the created session based on provided argument
 157  * This is currently a summary of what was pretty printed and is subject to
 158  * enhancements.
 159  * str_url is a placement string for output  url (snapshot or regular trace)
 160  */
 161 static int mi_created_session(const char *session_name)
 162 {
 163         int ret, i, count, found;
 164         struct lttng_session *sessions;
 165
 166         /* session_name should not be null */
 167         assert(session_name);
 168         assert(writer);
 169
 170         count = lttng_list_sessions(&sessions);
 171         if (count < 0) {
 172                 ret = count;
 173                 ERR("%s", lttng_strerror(ret));
 174                 goto error;
 175         }
 176
 177         if (count == 0) {
 178                 ERR("Error session creation failed: session %s not found", session_name);
 179                 ret = -LTTNG_ERR_SESS_NOT_FOUND;
 180                 goto end;
 181         }
 182
 183         found = 0;
 184         for (i = 0; i < count; i++) {
 185                 if (strncmp(sessions[i].name, session_name, NAME_MAX) == 0) {
 186                         found = 1;
 187                         ret = mi_lttng_session(writer, &sessions[i], 0);
 188                         if (ret) {
 189                                 goto error;
 190                         }
 191                         break;
 192                 }
 193         }
 194
 195         if (!found) {
 196                 ret = -LTTNG_ERR_SESS_NOT_FOUND;
 197         } else {
 198                 ret = CMD_SUCCESS;
 199         }
 200
 201 error:
 202         free(sessions);
 203 end:
 204         return ret;
 205 }
 206
 207 /*
 208  * For a session name, set the consumer URLs.
 209  */
 210 static int set_consumer_url(const char *session_name, const char *ctrl_url,
 211                 const char *data_url)
 212 {
 213         int ret;
 214         struct lttng_handle *handle;
 215         struct lttng_domain dom;
 216
 217         assert(session_name);
 218
 219         /*
 220          * Set handle with the session name and the domain set to 0. This means to
 221          * the session daemon that the next action applies on the tracing session
 222          * rather then the domain specific session.
 223          */
 224         memset(&dom, 0, sizeof(dom));
 225
 226         handle = lttng_create_handle(session_name, &dom);
 227         if (handle == NULL) {
 228                 ret = CMD_FATAL;
 229                 goto error;
 230         }
 231
 232         ret = lttng_set_consumer_url(handle, ctrl_url, data_url);
 233         if (ret < 0) {
 234                 goto error;
 235         }
 236
 237         if (ctrl_url) {
 238                 MSG("Control URL %s set for session %s", ctrl_url, session_name);
 239         }
 240
 241         if (data_url) {
 242                 MSG("Data URL %s set for session %s", data_url, session_name);
 243         }
 244
 245 error:
 246         lttng_destroy_handle(handle);
 247         return ret;
 248 }
 249
 250 static int add_snapshot_output(const char *session_name, const char *ctrl_url,
 251                 const char *data_url)
 252 {
 253         int ret;
 254         struct lttng_snapshot_output *output = NULL;
 255
 256         assert(session_name);
 257
 258         output = lttng_snapshot_output_create();
 259         if (!output) {
 260                 ret = CMD_FATAL;
 261                 goto error_create;
 262         }
 263
 264         if (ctrl_url) {
 265                 ret = lttng_snapshot_output_set_ctrl_url(ctrl_url, output);
 266                 if (ret < 0) {
 267                         goto error;
 268                 }
 269         }
 270
 271         if (data_url) {
 272                 ret = lttng_snapshot_output_set_data_url(data_url, output);
 273                 if (ret < 0) {
 274                         goto error;
 275                 }
 276         }
 277
 278         /* This call, if successful, populates the id of the output object. */
 279         ret = lttng_snapshot_add_output(session_name, output);
 280         if (ret < 0) {
 281                 goto error;
 282         }
 283
 284 error:
 285         lttng_snapshot_output_destroy(output);
 286 error_create:
 287         return ret;
 288 }
 289
 290 /*
 291  *  Create a tracing session.
 292  *  If no name is specified, a default name is generated.
 293  *
 294  *  Returns one of the CMD_* result constants.
 295  */
 296 static int create_session(void)
 297 {
 298         int ret;
 299         char *session_name = NULL, *traces_path = NULL, *alloc_path = NULL;
 300         char *alloc_url = NULL, *url = NULL, datetime[16];
 301         char session_name_date[NAME_MAX + 17], *print_str_url = NULL;
 302         time_t rawtime;
 303         struct tm *timeinfo;
 304
 305         /* Get date and time for automatic session name/path */
 306         time(&rawtime);
 307         timeinfo = localtime(&rawtime);
 308         strftime(datetime, sizeof(datetime), "%Y%m%d-%H%M%S", timeinfo);
 309
 310         /* Auto session name creation */
 311         if (opt_session_name == NULL) {
 312                 ret = snprintf(session_name_date, sizeof(session_name_date),
 313                                 DEFAULT_SESSION_NAME "-%s", datetime);
 314                 if (ret < 0) {
 315                         PERROR("snprintf session name");
 316                         goto error;
 317                 }
 318                 session_name = session_name_date;
 319                 DBG("Auto session name set to %s", session_name_date);
 320         } else {
 321                 if (strlen(opt_session_name) > NAME_MAX) {
 322                         ERR("Session name too long. Length must be lower or equal to %d",
 323                                         NAME_MAX);
 324                         ret = LTTNG_ERR_SESSION_FAIL;
 325                         goto error;
 326                 }
 327                 /*
 328                  * Check if the session name begins with "auto-" or is exactly "auto".
 329                  * Both are reserved for the default session name. See bug #449 to
 330                  * understand why we need to check both here.
 331                  */
 332                 if ((strncmp(opt_session_name, DEFAULT_SESSION_NAME "-",
 333                                         strlen(DEFAULT_SESSION_NAME) + 1) == 0) ||
 334                                 (strncmp(opt_session_name, DEFAULT_SESSION_NAME,
 335                                         strlen(DEFAULT_SESSION_NAME)) == 0 &&
 336                                 strlen(opt_session_name) == strlen(DEFAULT_SESSION_NAME))) {
 337                         ERR("%s is a reserved keyword for default session(s)",
 338                                         DEFAULT_SESSION_NAME);
 339                         ret = CMD_ERROR;
 340                         goto error;
 341                 }
 342                 session_name = opt_session_name;
 343                 ret = snprintf(session_name_date, sizeof(session_name_date),
 344                                 "%s-%s", session_name, datetime);
 345                 if (ret < 0) {
 346                         PERROR("snprintf session name");
 347                         goto error;
 348                 }
 349         }
 350
 351         if ((!opt_ctrl_url && opt_data_url) || (opt_ctrl_url && !opt_data_url)) {
 352                 ERR("You need both control and data URL.");
 353                 ret = CMD_ERROR;
 354                 goto error;
 355         }
 356
 357         if (opt_output_path != NULL) {
 358                 traces_path = utils_expand_path(opt_output_path);
 359                 if (traces_path == NULL) {
 360                         ret = CMD_ERROR;
 361                         goto error;
 362                 }
 363
 364                 /* Create URL string from the local file system path */
 365                 ret = asprintf(&alloc_url, "file://%s", traces_path);
 366                 if (ret < 0) {
 367                         PERROR("asprintf url path");
 368                         ret = CMD_FATAL;
 369                         goto error;
 370                 }
 371                 /* URL to use in the lttng_create_session() call */
 372                 url = alloc_url;
 373                 print_str_url = traces_path;
 374         } else if (opt_url) { /* Handling URL (-U opt) */
 375                 url = opt_url;
 376                 print_str_url = url;
 377         } else if (opt_data_url && opt_ctrl_url) {
 378                 /*
 379                  * With both control and data, we'll be setting the consumer URL after
 380                  * session creation thus use no URL.
 381                  */
 382                 url = NULL;
 383         } else if (!opt_no_output) {
 384                 /* Auto output path */
 385                 alloc_path = utils_get_home_dir();
 386                 if (alloc_path == NULL) {
 387                         ERR("HOME path not found.\n \
 388                                         Please specify an output path using -o, --output PATH");
 389                         ret = CMD_FATAL;
 390                         goto error;
 391                 }
 392                 alloc_path = strdup(alloc_path);
 393
 394                 ret = asprintf(&alloc_url,
 395                                 "file://%s/" DEFAULT_TRACE_DIR_NAME "/%s",
 396                                 alloc_path, session_name_date);
 397                 if (ret < 0) {
 398                         PERROR("asprintf trace dir name");
 399                         ret = CMD_FATAL;
 400                         goto error;
 401                 }
 402
 403                 url = alloc_url;
 404                 print_str_url = alloc_url + strlen("file://");
 405         } else {
 406                 /* No output means --no-output or --snapshot mode. */
 407                 url = NULL;
 408         }
 409
 410         /* Use default live URL if NO url is/are found. */
 411         if ((opt_live_timer && !opt_url) && (opt_live_timer && !opt_data_url)) {
 412                 ret = asprintf(&alloc_url, "net://127.0.0.1");
 413                 if (ret < 0) {
 414                         PERROR("asprintf default live URL");
 415                         ret = CMD_FATAL;
 416                         goto error;
 417                 }
 418                 url = alloc_url;
 419                 print_str_url = url;
 420         }
 421
 422         if (opt_snapshot && opt_live_timer) {
 423                 ERR("Snapshot and live modes are mutually exclusive.");
 424                 ret = CMD_ERROR;
 425                 goto error;
 426         }
 427
 428         if (opt_snapshot) {
 429                 /* No output by default. */
 430                 const char *snapshot_url = NULL;
 431
 432                 if (opt_url) {
 433                         snapshot_url = url;
 434                 } else if (!opt_data_url && !opt_ctrl_url) {
 435                         /* This is the session path that we need to use as output. */
 436                         snapshot_url = url;
 437                 }
 438                 ret = lttng_create_session_snapshot(session_name, snapshot_url);
 439         } else if (opt_live_timer) {
 440                 const char *pathname;
 441
 442                 if (opt_relayd_path) {
 443                         pathname = opt_relayd_path;
 444                 } else {
 445                         pathname = INSTALL_BIN_PATH "/lttng-relayd";
 446                 }
 447                 if (!opt_url && !opt_data_url && !check_relayd() &&
 448                                 spawn_relayd(pathname, 0) < 0) {
 449                         goto error;
 450                 }
 451                 ret = lttng_create_session_live(session_name, url, opt_live_timer);
 452         } else {
 453                 ret = _lttng_create_session_ext(session_name, url, datetime, -1);
 454         }
 455         if (ret < 0) {
 456                 /* Don't set ret so lttng can interpret the sessiond error. */
 457                 switch (-ret) {
 458                 case LTTNG_ERR_EXIST_SESS:
 459                         WARN("Session %s already exists", session_name);
 460                         break;
 461                 default:
 462                         break;
 463                 }
 464                 goto error;
 465         }
 466
 467         if (opt_ctrl_url && opt_data_url) {
 468                 if (opt_snapshot) {
 469                         ret = add_snapshot_output(session_name, opt_ctrl_url,
 470                                         opt_data_url);
 471                 } else {
 472                         /* Setting up control URI (-C or/and -D opt) */
 473                         ret = set_consumer_url(session_name, opt_ctrl_url, opt_data_url);
 474                 }
 475                 if (ret < 0) {
 476                         /* Destroy created session because the URL are not valid. */
 477                         lttng_destroy_session(session_name);
 478                         goto error;
 479                 }
 480         }
 481
 482         MSG("Session %s created.", session_name);
 483         if (print_str_url && !opt_snapshot) {
 484                 MSG("Traces will be written in %s", print_str_url);
 485
 486                 if (opt_live_timer) {
 487                         MSG("Live timer set to %u usec", opt_live_timer);
 488                 }
 489         } else if (opt_snapshot) {
 490                 if (print_str_url) {
 491                         MSG("Default snapshot output set to: %s", print_str_url);
 492                 }
 493                 MSG("Snapshot mode set. Every channel enabled for that session will "
 494                                 "be set in overwrite mode and mmap output.");
 495         }
 496
 497         /* Mi output */
 498         if (lttng_opt_mi) {
 499                 ret = mi_created_session(session_name);
 500                 if (ret) {
 501                         ret = CMD_ERROR;
 502                         goto error;
 503                 }
 504         }
 505
 506         /* Init lttng session config */
 507         ret = config_init(session_name);
 508         if (ret < 0) {
 509                 ret = CMD_ERROR;
 510                 goto error;
 511         }
 512
 513         ret = CMD_SUCCESS;
 514
 515 error:
 516         free(alloc_url);
 517         free(traces_path);
 518         free(alloc_path);
 519
 520         if (ret < 0) {
 521                 ERR("%s", lttng_strerror(ret));
 522         }
 523         return ret;
 524 }
 525
 526 /*
 527  *  The 'create <options>' first level command
 528  *
 529  *  Returns one of the CMD_* result constants.
 530  */
 531 int cmd_create(int argc, const char **argv)
 532 {
 533         int opt, ret = CMD_SUCCESS, command_ret = CMD_SUCCESS, success = 1;
 534         char *opt_arg = NULL;
 535         static poptContext pc;
 536
 537         pc = poptGetContext(NULL, argc, argv, long_options, 0);
 538         poptReadDefaultConfig(pc, 0);
 539
 540         while ((opt = poptGetNextOpt(pc)) != -1) {
 541                 switch (opt) {
 542                 case OPT_HELP:
 543                         usage(stdout);
 544                         goto end;
 545                 case OPT_LIST_OPTIONS:
 546                         list_cmd_options(stdout, long_options);
 547                         goto end;
 548                 case OPT_LIVE_TIMER:
 549                 {
 550                         unsigned long v;
 551
 552                         errno = 0;
 553                         opt_arg = poptGetOptArg(pc);
 554                         if (!opt_arg) {
 555                                 /* Set up default values. */
 556                                 opt_live_timer = (uint32_t) DEFAULT_LTTNG_LIVE_TIMER;
 557                                 DBG("Session live timer interval set to default value %d",
 558                                                 opt_live_timer);
 559                                 break;
 560                         }
 561
 562                         v = strtoul(opt_arg, NULL, 0);
 563                         if (errno != 0 || !isdigit(opt_arg[0])) {
 564                                 ERR("Wrong value in --live parameter: %s", opt_arg);
 565                                 ret = CMD_ERROR;
 566                                 goto end;
 567                         }
 568                         if (v != (uint32_t) v) {
 569                                 ERR("32-bit overflow in --live parameter: %s", opt_arg);
 570                                 ret = CMD_ERROR;
 571                                 goto end;
 572                         }
 573                         opt_live_timer = (uint32_t) v;
 574                         DBG("Session live timer interval set to %d", opt_live_timer);
 575                         break;
 576                 }
 577                 default:
 578                         usage(stderr);
 579                         ret = CMD_UNDEFINED;
 580                         goto end;
 581                 }
 582         }
 583
 584         if (opt_no_consumer) {
 585                 MSG("The option --no-consumer is obsolete. Use --no-output now.");
 586                 ret = CMD_WARNING;
 587                 goto end;
 588         }
 589
 590         if (opt_disable_consumer) {
 591                 MSG("The option --disable-consumer is obsolete.");
 592                 ret = CMD_WARNING;
 593                 goto end;
 594         }
 595
 596
 597         /* MI initialization */
 598         if (lttng_opt_mi) {
 599                 writer = mi_lttng_writer_create(fileno(stdout), lttng_opt_mi);
 600                 if (!writer) {
 601                         ret = -LTTNG_ERR_NOMEM;
 602                         goto end;
 603                 }
 604
 605                 /* Open command element */
 606                 ret = mi_lttng_writer_command_open(writer,
 607                                 mi_lttng_element_command_create);
 608                 if (ret) {
 609                         ret = CMD_ERROR;
 610                         goto end;
 611                 }
 612
 613                 /* Open output element */
 614                 ret = mi_lttng_writer_open_element(writer,
 615                                 mi_lttng_element_command_output);
 616                 if (ret) {
 617                         ret = CMD_ERROR;
 618                         goto end;
 619                 }
 620         }
 621         opt_session_name = (char*) poptGetArg(pc);
 622
 623         command_ret = create_session();
 624         if (command_ret) {
 625                 success = 0;
 626         }
 627
 628         if (lttng_opt_mi) {
 629                 /* Close  output element */
 630                 ret = mi_lttng_writer_close_element(writer);
 631                 if (ret) {
 632                         ret = CMD_ERROR;
 633                         goto end;
 634                 }
 635
 636                 /* Success ? */
 637                 ret = mi_lttng_writer_write_element_bool(writer,
 638                                 mi_lttng_element_command_success, success);
 639                 if (ret) {
 640                         ret = CMD_ERROR;
 641                         goto end;
 642                 }
 643
 644                 /* Command element close */
 645                 ret = mi_lttng_writer_command_close(writer);
 646                 if (ret) {
 647                         ret = CMD_ERROR;
 648                         goto end;
 649                 }
 650         }
 651
 652 end:
 653         /* Mi clean-up */
 654         if (writer && mi_lttng_writer_destroy(writer)) {
 655                 /* Preserve original error code */
 656                 ret = ret ? ret : -LTTNG_ERR_MI_IO_FAIL;
 657         }
 658
 659         /* Overwrite ret if an error occurred in create_session() */
 660         ret = command_ret ? command_ret : ret;
 661
 662         poptFreeContext(pc);
 663         return ret;
 664 }