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