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 char *opt_shm_path;
  48 static int opt_no_consumer;
  49 static int opt_no_output;
  50 static int opt_snapshot;
  51 static unsigned int opt_live_timer;
  52
  53 enum {
  54         OPT_HELP = 1,
  55         OPT_LIST_OPTIONS,
  56         OPT_LIVE_TIMER,
  57 };
  58
  59 static struct mi_writer *writer;
  60
  61 static struct poptOption long_options[] = {
  62         /* longName, shortName, argInfo, argPtr, value, descrip, argDesc */
  63         {"help", 'h', POPT_ARG_NONE, NULL, OPT_HELP, NULL, NULL},
  64         {"output", 'o', POPT_ARG_STRING, &opt_output_path, 0, NULL, NULL},
  65         {"list-options", 0, POPT_ARG_NONE, NULL, OPT_LIST_OPTIONS, NULL, NULL},
  66         {"set-url",        'U', POPT_ARG_STRING, &opt_url, 0, 0, 0},
  67         {"ctrl-url",       'C', POPT_ARG_STRING, &opt_ctrl_url, 0, 0, 0},
  68         {"data-url",       'D', POPT_ARG_STRING, &opt_data_url, 0, 0, 0},
  69         {"no-output",       0, POPT_ARG_VAL, &opt_no_output, 1, 0, 0},
  70         {"no-consumer",     0, POPT_ARG_VAL, &opt_no_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         {"shm-path",        0, POPT_ARG_STRING, &opt_shm_path, 0, 0, 0},
  74         {0, 0, 0, 0, 0, 0, 0}
  75 };
  76
  77 /*
  78  * Please have a look at src/lib/lttng-ctl/lttng-ctl.c for more information on
  79  * why this declaration exists and used ONLY in for this command.
  80  */
  81 extern int _lttng_create_session_ext(const char *name, const char *url,
  82                 const char *datetime, int live_timer);
  83
  84 /*
  85  * usage
  86  */
  87 static void usage(FILE *ofp)
  88 {
  89         fprintf(ofp, "usage: lttng create [NAME] [OPTIONS] \n");
  90         fprintf(ofp, "\n");
  91         fprintf(ofp, "Without a given NAME, the default is 'auto-<yyyymmdd>-<hhmmss>'\n");
  92         fprintf(ofp, "\n");
  93         fprintf(ofp, "Options:\n");
  94         fprintf(ofp, "  -h, --help           Show this help\n");
  95         fprintf(ofp, "      --list-options   Simple listing of options\n");
  96         fprintf(ofp, "  -o, --output PATH    Specify output path for traces\n");
  97         fprintf(ofp, "      --no-output      Traces will not be outputted\n");
  98         fprintf(ofp, "      --snapshot       Set the session in snapshot mode.\n");
  99         fprintf(ofp, "                       Created in no-output mode and uses the URL,\n");
 100         fprintf(ofp, "                       if one, as the default snapshot output.\n");
 101         fprintf(ofp, "                       Every channel will be set in overwrite mode\n");
 102         fprintf(ofp, "                       and with mmap output (splice not supported).\n");
 103         fprintf(ofp, "      --live [USEC]    Set the session in live-reading mode.\n");
 104         fprintf(ofp, "                       The delay parameter in micro-seconds is the\n");
 105         fprintf(ofp, "                       maximum time the user can wait for the data\n");
 106         fprintf(ofp, "                       to be flushed. Can be set with a network\n");
 107         fprintf(ofp, "                       URL (-U or -C/-D) and must have a relayd listening.\n");
 108         fprintf(ofp, "                       By default, %u is used for the timer and the\n",
 109                                                                                         DEFAULT_LTTNG_LIVE_TIMER);
 110         fprintf(ofp, "                       network URL is set to net://127.0.0.1.\n");
 111         fprintf(ofp, "      --shm-path PATH  Path where shared memory holding buffers\n");
 112         fprintf(ofp, "                       should be created. Useful when used with pramfs\n");
 113         fprintf(ofp, "                       to extract trace data after crash.\n");
 114         fprintf(ofp, "\n");
 115         fprintf(ofp, "Extended Options:\n");
 116         fprintf(ofp, "\n");
 117         fprintf(ofp, "Using these options, each API call can be controlled individually.\n");
 118         fprintf(ofp, "\n");
 119         fprintf(ofp, "  -U, --set-url=URL    Set URL destination of the trace data.\n");
 120         fprintf(ofp, "                       It is persistent for the session lifetime.\n");
 121         fprintf(ofp, "                       This will set both data and control URL.\n");
 122         fprintf(ofp, "  -C, --ctrl-url=URL   Set control path URL. (Must use -D also)\n");
 123         fprintf(ofp, "  -D, --data-url=URL   Set data path URL. (Must use -C also)\n");
 124         fprintf(ofp, "\n");
 125         fprintf(ofp, "Please refer to the man page (lttng(1)) for more information on network\n");
 126         fprintf(ofp, "streaming mechanisms and explanation of the control and data port\n");
 127         fprintf(ofp, "You must have a running remote lttng-relayd for network streaming\n");
 128         fprintf(ofp, "\n");
 129         fprintf(ofp, "URL format is has followed:\n");
 130         fprintf(ofp, "\n");
 131         fprintf(ofp, "  proto://[HOST|IP][:PORT1[:PORT2]][/TRACE_PATH]\n");
 132         fprintf(ofp, "\n");
 133         fprintf(ofp, "  Supported protocols are (proto):\n");
 134         fprintf(ofp, "  > file://...\n");
 135         fprintf(ofp, "    Local filesystem full path.\n");
 136         fprintf(ofp, "\n");
 137         fprintf(ofp, "  > net[6]://...\n");
 138         fprintf(ofp, "    This will use the default network transport layer which is\n");
 139         fprintf(ofp, "    TCP for both control (PORT1) and data port (PORT2).\n");
 140         fprintf(ofp, "    The default ports are respectively 5342 and 5343.\n");
 141         fprintf(ofp, "\n");
 142         fprintf(ofp, "  > tcp[6]://...\n");
 143         fprintf(ofp, "    Can only be used with -C and -D together\n");
 144         fprintf(ofp, "\n");
 145         fprintf(ofp, "NOTE: IPv6 address MUST be enclosed in brackets '[]' (rfc2732)\n");
 146         fprintf(ofp, "\n");
 147         fprintf(ofp, "Examples:\n");
 148         fprintf(ofp, "    # lttng create -U net://192.168.1.42\n");
 149         fprintf(ofp, "    Uses TCP and default ports for the given destination.\n");
 150         fprintf(ofp, "    # lttng create -U net6://[fe80::f66d:4ff:fe53:d220]\n");
 151         fprintf(ofp, "    Uses TCP, default ports and IPv6.\n");
 152         fprintf(ofp, "    # lttng create s1 -U net://myhost.com:3229\n");
 153         fprintf(ofp, "    Set the consumer to the remote HOST on port 3229 for control.\n");
 154         fprintf(ofp, "\n");
 155 }
 156
 157 /*
 158  * Retrieve the created session and mi output it based on provided argument
 159  * This is currently a summary of what was pretty printed and is subject to
 160  * enhancements.
 161  */
 162 static int mi_created_session(const char *session_name)
 163 {
 164         int ret, i, count, found;
 165         struct lttng_session *sessions;
 166
 167         /* session_name should not be null */
 168         assert(session_name);
 169         assert(writer);
 170
 171         count = lttng_list_sessions(&sessions);
 172         if (count < 0) {
 173                 ret = count;
 174                 ERR("%s", lttng_strerror(ret));
 175                 goto error;
 176         }
 177
 178         if (count == 0) {
 179                 ERR("Error session creation failed: session %s not found", session_name);
 180                 ret = -LTTNG_ERR_SESS_NOT_FOUND;
 181                 goto end;
 182         }
 183
 184         found = 0;
 185         for (i = 0; i < count; i++) {
 186                 if (strncmp(sessions[i].name, session_name, NAME_MAX) == 0) {
 187                         found = 1;
 188                         ret = mi_lttng_session(writer, &sessions[i], 0);
 189                         if (ret) {
 190                                 goto error;
 191                         }
 192                         break;
 193                 }
 194         }
 195
 196         if (!found) {
 197                 ret = -LTTNG_ERR_SESS_NOT_FOUND;
 198         } else {
 199                 ret = CMD_SUCCESS;
 200         }
 201
 202 error:
 203         free(sessions);
 204 end:
 205         return ret;
 206 }
 207
 208 /*
 209  * For a session name, set the consumer URLs.
 210  */
 211 static int set_consumer_url(const char *session_name, const char *ctrl_url,
 212                 const char *data_url)
 213 {
 214         int ret;
 215         struct lttng_handle *handle;
 216         struct lttng_domain dom;
 217
 218         assert(session_name);
 219
 220         /*
 221          * Set handle with the session name and the domain set to 0. This means to
 222          * the session daemon that the next action applies on the tracing session
 223          * rather then the domain specific session.
 224          */
 225         memset(&dom, 0, sizeof(dom));
 226
 227         handle = lttng_create_handle(session_name, &dom);
 228         if (handle == NULL) {
 229                 ret = CMD_FATAL;
 230                 goto error;
 231         }
 232
 233         ret = lttng_set_consumer_url(handle, ctrl_url, data_url);
 234         if (ret < 0) {
 235                 goto error;
 236         }
 237
 238         if (ctrl_url) {
 239                 MSG("Control URL %s set for session %s", ctrl_url, session_name);
 240         }
 241
 242         if (data_url) {
 243                 MSG("Data URL %s set for session %s", data_url, session_name);
 244         }
 245
 246 error:
 247         lttng_destroy_handle(handle);
 248         return ret;
 249 }
 250
 251 static int add_snapshot_output(const char *session_name, const char *ctrl_url,
 252                 const char *data_url)
 253 {
 254         int ret;
 255         struct lttng_snapshot_output *output = NULL;
 256
 257         assert(session_name);
 258
 259         output = lttng_snapshot_output_create();
 260         if (!output) {
 261                 ret = CMD_FATAL;
 262                 goto error_create;
 263         }
 264
 265         if (ctrl_url) {
 266                 ret = lttng_snapshot_output_set_ctrl_url(ctrl_url, output);
 267                 if (ret < 0) {
 268                         goto error;
 269                 }
 270         }
 271
 272         if (data_url) {
 273                 ret = lttng_snapshot_output_set_data_url(data_url, output);
 274                 if (ret < 0) {
 275                         goto error;
 276                 }
 277         }
 278
 279         /* This call, if successful, populates the id of the output object. */
 280         ret = lttng_snapshot_add_output(session_name, output);
 281         if (ret < 0) {
 282                 goto error;
 283         }
 284
 285 error:
 286         lttng_snapshot_output_destroy(output);
 287 error_create:
 288         return ret;
 289 }
 290
 291 /*
 292  *  Create a tracing session.
 293  *  If no name is specified, a default name is generated.
 294  *
 295  *  Returns one of the CMD_* result constants.
 296  */
 297 static int create_session(void)
 298 {
 299         int ret;
 300         char *session_name = NULL, *traces_path = NULL, *alloc_path = NULL;
 301         char *alloc_url = NULL, *url = NULL, datetime[16];
 302         char session_name_date[NAME_MAX + 17], *print_str_url = NULL;
 303         time_t rawtime;
 304         struct tm *timeinfo;
 305         char shm_path[PATH_MAX] = "";
 306
 307         /* Get date and time for automatic session name/path */
 308         time(&rawtime);
 309         timeinfo = localtime(&rawtime);
 310         strftime(datetime, sizeof(datetime), "%Y%m%d-%H%M%S", timeinfo);
 311
 312         /* Auto session name creation */
 313         if (opt_session_name == NULL) {
 314                 ret = snprintf(session_name_date, sizeof(session_name_date),
 315                                 DEFAULT_SESSION_NAME "-%s", datetime);
 316                 if (ret < 0) {
 317                         PERROR("snprintf session name");
 318                         goto error;
 319                 }
 320                 session_name = session_name_date;
 321                 DBG("Auto session name set to %s", session_name_date);
 322         } else {
 323                 if (strlen(opt_session_name) > NAME_MAX) {
 324                         ERR("Session name too long. Length must be lower or equal to %d",
 325                                         NAME_MAX);
 326                         ret = LTTNG_ERR_SESSION_FAIL;
 327                         goto error;
 328                 }
 329                 /*
 330                  * Check if the session name begins with "auto-" or is exactly "auto".
 331                  * Both are reserved for the default session name. See bug #449 to
 332                  * understand why we need to check both here.
 333                  */
 334                 if ((strncmp(opt_session_name, DEFAULT_SESSION_NAME "-",
 335                                         strlen(DEFAULT_SESSION_NAME) + 1) == 0) ||
 336                                 (strncmp(opt_session_name, DEFAULT_SESSION_NAME,
 337                                         strlen(DEFAULT_SESSION_NAME)) == 0 &&
 338                                 strlen(opt_session_name) == strlen(DEFAULT_SESSION_NAME))) {
 339                         ERR("%s is a reserved keyword for default session(s)",
 340                                         DEFAULT_SESSION_NAME);
 341                         ret = CMD_ERROR;
 342                         goto error;
 343                 }
 344                 session_name = opt_session_name;
 345                 ret = snprintf(session_name_date, sizeof(session_name_date),
 346                                 "%s-%s", session_name, datetime);
 347                 if (ret < 0) {
 348                         PERROR("snprintf session name");
 349                         goto error;
 350                 }
 351         }
 352
 353         if ((!opt_ctrl_url && opt_data_url) || (opt_ctrl_url && !opt_data_url)) {
 354                 ERR("You need both control and data URL.");
 355                 ret = CMD_ERROR;
 356                 goto error;
 357         }
 358
 359         if (opt_output_path != NULL) {
 360                 traces_path = utils_expand_path(opt_output_path);
 361                 if (traces_path == NULL) {
 362                         ret = CMD_ERROR;
 363                         goto error;
 364                 }
 365
 366                 /* Create URL string from the local file system path */
 367                 ret = asprintf(&alloc_url, "file://%s", traces_path);
 368                 if (ret < 0) {
 369                         PERROR("asprintf url path");
 370                         ret = CMD_FATAL;
 371                         goto error;
 372                 }
 373                 /* URL to use in the lttng_create_session() call */
 374                 url = alloc_url;
 375                 print_str_url = traces_path;
 376         } else if (opt_url) { /* Handling URL (-U opt) */
 377                 url = opt_url;
 378                 print_str_url = url;
 379         } else if (opt_data_url && opt_ctrl_url) {
 380                 /*
 381                  * With both control and data, we'll be setting the consumer URL after
 382                  * session creation thus use no URL.
 383                  */
 384                 url = NULL;
 385         } else if (!opt_no_output) {
 386                 char *tmp_path;
 387
 388                 /* Auto output path */
 389                 tmp_path = utils_get_home_dir();
 390                 if (tmp_path == NULL) {
 391                         ERR("HOME path not found.\n \
 392                                         Please specify an output path using -o, --output PATH");
 393                         ret = CMD_FATAL;
 394                         goto error;
 395                 }
 396                 alloc_path = strdup(tmp_path);
 397                 if (!alloc_path) {
 398                         PERROR("allocating alloc_path");
 399                         ret = CMD_FATAL;
 400                         goto error;
 401                 }
 402                 ret = asprintf(&alloc_url,
 403                                 "file://%s/" DEFAULT_TRACE_DIR_NAME "/%s",
 404                                 alloc_path, session_name_date);
 405                 if (ret < 0) {
 406                         PERROR("asprintf trace dir name");
 407                         ret = CMD_FATAL;
 408                         goto error;
 409                 }
 410
 411                 url = alloc_url;
 412                 print_str_url = alloc_url + strlen("file://");
 413         } else {
 414                 /* No output means --no-output or --snapshot mode. */
 415                 url = NULL;
 416         }
 417
 418         /* Use default live URL if NO url is/are found. */
 419         if ((opt_live_timer && !opt_url) && (opt_live_timer && !opt_data_url)) {
 420                 ret = asprintf(&alloc_url, "net://127.0.0.1");
 421                 if (ret < 0) {
 422                         PERROR("asprintf default live URL");
 423                         ret = CMD_FATAL;
 424                         goto error;
 425                 }
 426                 url = alloc_url;
 427                 print_str_url = url;
 428         }
 429
 430         if (opt_snapshot && opt_live_timer) {
 431                 ERR("Snapshot and live modes are mutually exclusive.");
 432                 ret = CMD_ERROR;
 433                 goto error;
 434         }
 435
 436         if (opt_snapshot) {
 437                 /* No output by default. */
 438                 const char *snapshot_url = NULL;
 439
 440                 if (opt_url) {
 441                         snapshot_url = url;
 442                 } else if (!opt_data_url && !opt_ctrl_url) {
 443                         /* This is the session path that we need to use as output. */
 444                         snapshot_url = url;
 445                 }
 446                 ret = lttng_create_session_snapshot(session_name, snapshot_url);
 447         } else if (opt_live_timer) {
 448                 const char *pathname;
 449
 450                 if (opt_relayd_path) {
 451                         pathname = opt_relayd_path;
 452                 } else {
 453                         pathname = INSTALL_BIN_PATH "/lttng-relayd";
 454                 }
 455                 if (!opt_url && !opt_data_url && !check_relayd() &&
 456                                 spawn_relayd(pathname, 0) < 0) {
 457                         goto error;
 458                 }
 459                 ret = lttng_create_session_live(session_name, url, opt_live_timer);
 460         } else {
 461                 ret = _lttng_create_session_ext(session_name, url, datetime, -1);
 462         }
 463         if (ret < 0) {
 464                 /* Don't set ret so lttng can interpret the sessiond error. */
 465                 switch (-ret) {
 466                 case LTTNG_ERR_EXIST_SESS:
 467                         WARN("Session %s already exists", session_name);
 468                         break;
 469                 default:
 470                         break;
 471                 }
 472                 goto error;
 473         }
 474
 475         if (opt_ctrl_url && opt_data_url) {
 476                 if (opt_snapshot) {
 477                         ret = add_snapshot_output(session_name, opt_ctrl_url,
 478                                         opt_data_url);
 479                 } else {
 480                         /* Setting up control URI (-C or/and -D opt) */
 481                         ret = set_consumer_url(session_name, opt_ctrl_url, opt_data_url);
 482                 }
 483                 if (ret < 0) {
 484                         /* Destroy created session because the URL are not valid. */
 485                         lttng_destroy_session(session_name);
 486                         goto error;
 487                 }
 488         }
 489
 490         if (opt_shm_path) {
 491                 ret = snprintf(shm_path, sizeof(shm_path),
 492                                 "%s/%s", opt_shm_path, session_name_date);
 493                 if (ret < 0) {
 494                         PERROR("snprintf shm_path");
 495                         goto error;
 496                 }
 497
 498                 ret = lttng_set_session_shm_path(session_name, shm_path);
 499                 if (ret < 0) {
 500                         lttng_destroy_session(session_name);
 501                         goto error;
 502                 }
 503         }
 504
 505         MSG("Session %s created.", session_name);
 506         if (print_str_url && !opt_snapshot) {
 507                 MSG("Traces will be written in %s", print_str_url);
 508
 509                 if (opt_live_timer) {
 510                         MSG("Live timer set to %u usec", opt_live_timer);
 511                 }
 512         } else if (opt_snapshot) {
 513                 if (print_str_url) {
 514                         MSG("Default snapshot output set to: %s", print_str_url);
 515                 }
 516                 MSG("Snapshot mode set. Every channel enabled for that session will "
 517                                 "be set in overwrite mode and mmap output.");
 518         }
 519         if (opt_shm_path) {
 520                 MSG("Session %s set to shm_path: %s.", session_name,
 521                         shm_path);
 522         }
 523
 524         /* Mi output */
 525         if (lttng_opt_mi) {
 526                 ret = mi_created_session(session_name);
 527                 if (ret) {
 528                         ret = CMD_ERROR;
 529                         goto error;
 530                 }
 531         }
 532
 533         /* Init lttng session config */
 534         ret = config_init(session_name);
 535         if (ret < 0) {
 536                 ret = CMD_ERROR;
 537                 goto error;
 538         }
 539
 540         ret = CMD_SUCCESS;
 541
 542 error:
 543         free(alloc_url);
 544         free(traces_path);
 545         free(alloc_path);
 546
 547         if (ret < 0) {
 548                 ERR("%s", lttng_strerror(ret));
 549         }
 550         return ret;
 551 }
 552
 553 /*
 554  *  The 'create <options>' first level command
 555  *
 556  *  Returns one of the CMD_* result constants.
 557  */
 558 int cmd_create(int argc, const char **argv)
 559 {
 560         int opt, ret = CMD_SUCCESS, command_ret = CMD_SUCCESS, success = 1;
 561         char *opt_arg = NULL;
 562         static poptContext pc;
 563
 564         pc = poptGetContext(NULL, argc, argv, long_options, 0);
 565         poptReadDefaultConfig(pc, 0);
 566
 567         while ((opt = poptGetNextOpt(pc)) != -1) {
 568                 switch (opt) {
 569                 case OPT_HELP:
 570                         usage(stdout);
 571                         goto end;
 572                 case OPT_LIST_OPTIONS:
 573                         list_cmd_options(stdout, long_options);
 574                         goto end;
 575                 case OPT_LIVE_TIMER:
 576                 {
 577                         unsigned long v;
 578
 579                         errno = 0;
 580                         opt_arg = poptGetOptArg(pc);
 581                         if (!opt_arg) {
 582                                 /* Set up default values. */
 583                                 opt_live_timer = (uint32_t) DEFAULT_LTTNG_LIVE_TIMER;
 584                                 DBG("Session live timer interval set to default value %d",
 585                                                 opt_live_timer);
 586                                 break;
 587                         }
 588
 589                         v = strtoul(opt_arg, NULL, 0);
 590                         if (errno != 0 || !isdigit(opt_arg[0])) {
 591                                 ERR("Wrong value in --live parameter: %s", opt_arg);
 592                                 ret = CMD_ERROR;
 593                                 goto end;
 594                         }
 595                         if (v != (uint32_t) v) {
 596                                 ERR("32-bit overflow in --live parameter: %s", opt_arg);
 597                                 ret = CMD_ERROR;
 598                                 goto end;
 599                         }
 600                         if (v == 0) {
 601                                 ERR("Live timer interval must be greater than zero");
 602                                 ret = CMD_ERROR;
 603                                 goto end;
 604                         }
 605                         opt_live_timer = (uint32_t) v;
 606                         DBG("Session live timer interval set to %d", opt_live_timer);
 607                         break;
 608                 }
 609                 default:
 610                         usage(stderr);
 611                         ret = CMD_UNDEFINED;
 612                         goto end;
 613                 }
 614         }
 615
 616         if (opt_no_consumer) {
 617                 MSG("The option --no-consumer is obsolete. Use --no-output now.");
 618                 ret = CMD_WARNING;
 619                 goto end;
 620         }
 621
 622         /* MI initialization */
 623         if (lttng_opt_mi) {
 624                 writer = mi_lttng_writer_create(fileno(stdout), lttng_opt_mi);
 625                 if (!writer) {
 626                         ret = -LTTNG_ERR_NOMEM;
 627                         goto end;
 628                 }
 629
 630                 /* Open command element */
 631                 ret = mi_lttng_writer_command_open(writer,
 632                                 mi_lttng_element_command_create);
 633                 if (ret) {
 634                         ret = CMD_ERROR;
 635                         goto end;
 636                 }
 637
 638                 /* Open output element */
 639                 ret = mi_lttng_writer_open_element(writer,
 640                                 mi_lttng_element_command_output);
 641                 if (ret) {
 642                         ret = CMD_ERROR;
 643                         goto end;
 644                 }
 645         }
 646         opt_session_name = (char*) poptGetArg(pc);
 647
 648         command_ret = create_session();
 649         if (command_ret) {
 650                 success = 0;
 651         }
 652
 653         if (lttng_opt_mi) {
 654                 /* Close  output element */
 655                 ret = mi_lttng_writer_close_element(writer);
 656                 if (ret) {
 657                         ret = CMD_ERROR;
 658                         goto end;
 659                 }
 660
 661                 /* Success ? */
 662                 ret = mi_lttng_writer_write_element_bool(writer,
 663                                 mi_lttng_element_command_success, success);
 664                 if (ret) {
 665                         ret = CMD_ERROR;
 666                         goto end;
 667                 }
 668
 669                 /* Command element close */
 670                 ret = mi_lttng_writer_command_close(writer);
 671                 if (ret) {
 672                         ret = CMD_ERROR;
 673                         goto end;
 674                 }
 675         }
 676
 677 end:
 678         /* Mi clean-up */
 679         if (writer && mi_lttng_writer_destroy(writer)) {
 680                 /* Preserve original error code */
 681                 ret = ret ? ret : -LTTNG_ERR_MI_IO_FAIL;
 682         }
 683
 684         /* Overwrite ret if an error occurred in create_session() */
 685         ret = command_ret ? command_ret : ret;
 686
 687         poptFreeContext(pc);
 688         return ret;
 689 }