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 mi output it based on provided argument
 156  * This is currently a summary of what was pretty printed and is subject to
 157  * enhancements.
 158  */
 159 static int mi_created_session(const char *session_name)
 160 {
 161         int ret, i, count, found;
 162         struct lttng_session *sessions;
 163
 164         /* session_name should not be null */
 165         assert(session_name);
 166         assert(writer);
 167
 168         count = lttng_list_sessions(&sessions);
 169         if (count < 0) {
 170                 ret = count;
 171                 ERR("%s", lttng_strerror(ret));
 172                 goto error;
 173         }
 174
 175         if (count == 0) {
 176                 ERR("Error session creation failed: session %s not found", session_name);
 177                 ret = -LTTNG_ERR_SESS_NOT_FOUND;
 178                 goto end;
 179         }
 180
 181         found = 0;
 182         for (i = 0; i < count; i++) {
 183                 if (strncmp(sessions[i].name, session_name, NAME_MAX) == 0) {
 184                         found = 1;
 185                         ret = mi_lttng_session(writer, &sessions[i], 0);
 186                         if (ret) {
 187                                 goto error;
 188                         }
 189                         break;
 190                 }
 191         }
 192
 193         if (!found) {
 194                 ret = -LTTNG_ERR_SESS_NOT_FOUND;
 195         } else {
 196                 ret = CMD_SUCCESS;
 197         }
 198
 199 error:
 200         free(sessions);
 201 end:
 202         return ret;
 203 }
 204
 205 /*
 206  * For a session name, set the consumer URLs.
 207  */
 208 static int set_consumer_url(const char *session_name, const char *ctrl_url,
 209                 const char *data_url)
 210 {
 211         int ret;
 212         struct lttng_handle *handle;
 213         struct lttng_domain dom;
 214
 215         assert(session_name);
 216
 217         /*
 218          * Set handle with the session name and the domain set to 0. This means to
 219          * the session daemon that the next action applies on the tracing session
 220          * rather then the domain specific session.
 221          */
 222         memset(&dom, 0, sizeof(dom));
 223
 224         handle = lttng_create_handle(session_name, &dom);
 225         if (handle == NULL) {
 226                 ret = CMD_FATAL;
 227                 goto error;
 228         }
 229
 230         ret = lttng_set_consumer_url(handle, ctrl_url, data_url);
 231         if (ret < 0) {
 232                 goto error;
 233         }
 234
 235         if (ctrl_url) {
 236                 MSG("Control URL %s set for session %s", ctrl_url, session_name);
 237         }
 238
 239         if (data_url) {
 240                 MSG("Data URL %s set for session %s", data_url, session_name);
 241         }
 242
 243 error:
 244         lttng_destroy_handle(handle);
 245         return ret;
 246 }
 247
 248 static int add_snapshot_output(const char *session_name, const char *ctrl_url,
 249                 const char *data_url)
 250 {
 251         int ret;
 252         struct lttng_snapshot_output *output = NULL;
 253
 254         assert(session_name);
 255
 256         output = lttng_snapshot_output_create();
 257         if (!output) {
 258                 ret = CMD_FATAL;
 259                 goto error_create;
 260         }
 261
 262         if (ctrl_url) {
 263                 ret = lttng_snapshot_output_set_ctrl_url(ctrl_url, output);
 264                 if (ret < 0) {
 265                         goto error;
 266                 }
 267         }
 268
 269         if (data_url) {
 270                 ret = lttng_snapshot_output_set_data_url(data_url, output);
 271                 if (ret < 0) {
 272                         goto error;
 273                 }
 274         }
 275
 276         /* This call, if successful, populates the id of the output object. */
 277         ret = lttng_snapshot_add_output(session_name, output);
 278         if (ret < 0) {
 279                 goto error;
 280         }
 281
 282 error:
 283         lttng_snapshot_output_destroy(output);
 284 error_create:
 285         return ret;
 286 }
 287
 288 /*
 289  *  Create a tracing session.
 290  *  If no name is specified, a default name is generated.
 291  *
 292  *  Returns one of the CMD_* result constants.
 293  */
 294 static int create_session(void)
 295 {
 296         int ret;
 297         char *session_name = NULL, *traces_path = NULL, *alloc_path = NULL;
 298         char *alloc_url = NULL, *url = NULL, datetime[16];
 299         char session_name_date[NAME_MAX + 17], *print_str_url = NULL;
 300         time_t rawtime;
 301         struct tm *timeinfo;
 302
 303         /* Get date and time for automatic session name/path */
 304         time(&rawtime);
 305         timeinfo = localtime(&rawtime);
 306         strftime(datetime, sizeof(datetime), "%Y%m%d-%H%M%S", timeinfo);
 307
 308         /* Auto session name creation */
 309         if (opt_session_name == NULL) {
 310                 ret = snprintf(session_name_date, sizeof(session_name_date),
 311                                 DEFAULT_SESSION_NAME "-%s", datetime);
 312                 if (ret < 0) {
 313                         PERROR("snprintf session name");
 314                         goto error;
 315                 }
 316                 session_name = session_name_date;
 317                 DBG("Auto session name set to %s", session_name_date);
 318         } else {
 319                 if (strlen(opt_session_name) > NAME_MAX) {
 320                         ERR("Session name too long. Length must be lower or equal to %d",
 321                                         NAME_MAX);
 322                         ret = LTTNG_ERR_SESSION_FAIL;
 323                         goto error;
 324                 }
 325                 /*
 326                  * Check if the session name begins with "auto-" or is exactly "auto".
 327                  * Both are reserved for the default session name. See bug #449 to
 328                  * understand why we need to check both here.
 329                  */
 330                 if ((strncmp(opt_session_name, DEFAULT_SESSION_NAME "-",
 331                                         strlen(DEFAULT_SESSION_NAME) + 1) == 0) ||
 332                                 (strncmp(opt_session_name, DEFAULT_SESSION_NAME,
 333                                         strlen(DEFAULT_SESSION_NAME)) == 0 &&
 334                                 strlen(opt_session_name) == strlen(DEFAULT_SESSION_NAME))) {
 335                         ERR("%s is a reserved keyword for default session(s)",
 336                                         DEFAULT_SESSION_NAME);
 337                         ret = CMD_ERROR;
 338                         goto error;
 339                 }
 340                 session_name = opt_session_name;
 341                 ret = snprintf(session_name_date, sizeof(session_name_date),
 342                                 "%s-%s", session_name, datetime);
 343                 if (ret < 0) {
 344                         PERROR("snprintf session name");
 345                         goto error;
 346                 }
 347         }
 348
 349         if ((!opt_ctrl_url && opt_data_url) || (opt_ctrl_url && !opt_data_url)) {
 350                 ERR("You need both control and data URL.");
 351                 ret = CMD_ERROR;
 352                 goto error;
 353         }
 354
 355         if (opt_output_path != NULL) {
 356                 traces_path = utils_expand_path(opt_output_path);
 357                 if (traces_path == NULL) {
 358                         ret = CMD_ERROR;
 359                         goto error;
 360                 }
 361
 362                 /* Create URL string from the local file system path */
 363                 ret = asprintf(&alloc_url, "file://%s", traces_path);
 364                 if (ret < 0) {
 365                         PERROR("asprintf url path");
 366                         ret = CMD_FATAL;
 367                         goto error;
 368                 }
 369                 /* URL to use in the lttng_create_session() call */
 370                 url = alloc_url;
 371                 print_str_url = traces_path;
 372         } else if (opt_url) { /* Handling URL (-U opt) */
 373                 url = opt_url;
 374                 print_str_url = url;
 375         } else if (opt_data_url && opt_ctrl_url) {
 376                 /*
 377                  * With both control and data, we'll be setting the consumer URL after
 378                  * session creation thus use no URL.
 379                  */
 380                 url = NULL;
 381         } else if (!opt_no_output) {
 382                 /* Auto output path */
 383                 alloc_path = utils_get_home_dir();
 384                 if (alloc_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(alloc_path);
 391
 392                 ret = asprintf(&alloc_url,
 393                                 "file://%s/" DEFAULT_TRACE_DIR_NAME "/%s",
 394                                 alloc_path, session_name_date);
 395                 if (ret < 0) {
 396                         PERROR("asprintf trace dir name");
 397                         ret = CMD_FATAL;
 398                         goto error;
 399                 }
 400
 401                 url = alloc_url;
 402                 print_str_url = alloc_url + strlen("file://");
 403         } else {
 404                 /* No output means --no-output or --snapshot mode. */
 405                 url = NULL;
 406         }
 407
 408         /* Use default live URL if NO url is/are found. */
 409         if ((opt_live_timer && !opt_url) && (opt_live_timer && !opt_data_url)) {
 410                 ret = asprintf(&alloc_url, "net://127.0.0.1");
 411                 if (ret < 0) {
 412                         PERROR("asprintf default live URL");
 413                         ret = CMD_FATAL;
 414                         goto error;
 415                 }
 416                 url = alloc_url;
 417                 print_str_url = url;
 418         }
 419
 420         if (opt_snapshot && opt_live_timer) {
 421                 ERR("Snapshot and live modes are mutually exclusive.");
 422                 ret = CMD_ERROR;
 423                 goto error;
 424         }
 425
 426         if (opt_snapshot) {
 427                 /* No output by default. */
 428                 const char *snapshot_url = NULL;
 429
 430                 if (opt_url) {
 431                         snapshot_url = url;
 432                 } else if (!opt_data_url && !opt_ctrl_url) {
 433                         /* This is the session path that we need to use as output. */
 434                         snapshot_url = url;
 435                 }
 436                 ret = lttng_create_session_snapshot(session_name, snapshot_url);
 437         } else if (opt_live_timer) {
 438                 const char *pathname;
 439
 440                 if (opt_relayd_path) {
 441                         pathname = opt_relayd_path;
 442                 } else {
 443                         pathname = INSTALL_BIN_PATH "/lttng-relayd";
 444                 }
 445                 if (!opt_url && !opt_data_url && !check_relayd() &&
 446                                 spawn_relayd(pathname, 0) < 0) {
 447                         goto error;
 448                 }
 449                 ret = lttng_create_session_live(session_name, url, opt_live_timer);
 450         } else {
 451                 ret = _lttng_create_session_ext(session_name, url, datetime, -1);
 452         }
 453         if (ret < 0) {
 454                 /* Don't set ret so lttng can interpret the sessiond error. */
 455                 switch (-ret) {
 456                 case LTTNG_ERR_EXIST_SESS:
 457                         WARN("Session %s already exists", session_name);
 458                         break;
 459                 default:
 460                         break;
 461                 }
 462                 goto error;
 463         }
 464
 465         if (opt_ctrl_url && opt_data_url) {
 466                 if (opt_snapshot) {
 467                         ret = add_snapshot_output(session_name, opt_ctrl_url,
 468                                         opt_data_url);
 469                 } else {
 470                         /* Setting up control URI (-C or/and -D opt) */
 471                         ret = set_consumer_url(session_name, opt_ctrl_url, opt_data_url);
 472                 }
 473                 if (ret < 0) {
 474                         /* Destroy created session because the URL are not valid. */
 475                         lttng_destroy_session(session_name);
 476                         goto error;
 477                 }
 478         }
 479
 480         MSG("Session %s created.", session_name);
 481         if (print_str_url && !opt_snapshot) {
 482                 MSG("Traces will be written in %s", print_str_url);
 483
 484                 if (opt_live_timer) {
 485                         MSG("Live timer set to %u usec", opt_live_timer);
 486                 }
 487         } else if (opt_snapshot) {
 488                 if (print_str_url) {
 489                         MSG("Default snapshot output set to: %s", print_str_url);
 490                 }
 491                 MSG("Snapshot mode set. Every channel enabled for that session will "
 492                                 "be set in overwrite mode and mmap output.");
 493         }
 494
 495         /* Mi output */
 496         if (lttng_opt_mi) {
 497                 ret = mi_created_session(session_name);
 498                 if (ret) {
 499                         ret = CMD_ERROR;
 500                         goto error;
 501                 }
 502         }
 503
 504         /* Init lttng session config */
 505         ret = config_init(session_name);
 506         if (ret < 0) {
 507                 ret = CMD_ERROR;
 508                 goto error;
 509         }
 510
 511         ret = CMD_SUCCESS;
 512
 513 error:
 514         free(alloc_url);
 515         free(traces_path);
 516         free(alloc_path);
 517
 518         if (ret < 0) {
 519                 ERR("%s", lttng_strerror(ret));
 520         }
 521         return ret;
 522 }
 523
 524 /*
 525  *  The 'create <options>' first level command
 526  *
 527  *  Returns one of the CMD_* result constants.
 528  */
 529 int cmd_create(int argc, const char **argv)
 530 {
 531         int opt, ret = CMD_SUCCESS, command_ret = CMD_SUCCESS, success = 1;
 532         char *opt_arg = NULL;
 533         static poptContext pc;
 534
 535         pc = poptGetContext(NULL, argc, argv, long_options, 0);
 536         poptReadDefaultConfig(pc, 0);
 537
 538         while ((opt = poptGetNextOpt(pc)) != -1) {
 539                 switch (opt) {
 540                 case OPT_HELP:
 541                         usage(stdout);
 542                         goto end;
 543                 case OPT_LIST_OPTIONS:
 544                         list_cmd_options(stdout, long_options);
 545                         goto end;
 546                 case OPT_LIVE_TIMER:
 547                 {
 548                         unsigned long v;
 549
 550                         errno = 0;
 551                         opt_arg = poptGetOptArg(pc);
 552                         if (!opt_arg) {
 553                                 /* Set up default values. */
 554                                 opt_live_timer = (uint32_t) DEFAULT_LTTNG_LIVE_TIMER;
 555                                 DBG("Session live timer interval set to default value %d",
 556                                                 opt_live_timer);
 557                                 break;
 558                         }
 559
 560                         v = strtoul(opt_arg, NULL, 0);
 561                         if (errno != 0 || !isdigit(opt_arg[0])) {
 562                                 ERR("Wrong value in --live parameter: %s", opt_arg);
 563                                 ret = CMD_ERROR;
 564                                 goto end;
 565                         }
 566                         if (v != (uint32_t) v) {
 567                                 ERR("32-bit overflow in --live parameter: %s", opt_arg);
 568                                 ret = CMD_ERROR;
 569                                 goto end;
 570                         }
 571                         opt_live_timer = (uint32_t) v;
 572                         DBG("Session live timer interval set to %d", opt_live_timer);
 573                         break;
 574                 }
 575                 default:
 576                         usage(stderr);
 577                         ret = CMD_UNDEFINED;
 578                         goto end;
 579                 }
 580         }
 581
 582         if (opt_no_consumer) {
 583                 MSG("The option --no-consumer is obsolete. Use --no-output now.");
 584                 ret = CMD_WARNING;
 585                 goto end;
 586         }
 587
 588         if (opt_disable_consumer) {
 589                 MSG("The option --disable-consumer is obsolete.");
 590                 ret = CMD_WARNING;
 591                 goto end;
 592         }
 593
 594
 595         /* MI initialization */
 596         if (lttng_opt_mi) {
 597                 writer = mi_lttng_writer_create(fileno(stdout), lttng_opt_mi);
 598                 if (!writer) {
 599                         ret = -LTTNG_ERR_NOMEM;
 600                         goto end;
 601                 }
 602
 603                 /* Open command element */
 604                 ret = mi_lttng_writer_command_open(writer,
 605                                 mi_lttng_element_command_create);
 606                 if (ret) {
 607                         ret = CMD_ERROR;
 608                         goto end;
 609                 }
 610
 611                 /* Open output element */
 612                 ret = mi_lttng_writer_open_element(writer,
 613                                 mi_lttng_element_command_output);
 614                 if (ret) {
 615                         ret = CMD_ERROR;
 616                         goto end;
 617                 }
 618         }
 619         opt_session_name = (char*) poptGetArg(pc);
 620
 621         command_ret = create_session();
 622         if (command_ret) {
 623                 success = 0;
 624         }
 625
 626         if (lttng_opt_mi) {
 627                 /* Close  output element */
 628                 ret = mi_lttng_writer_close_element(writer);
 629                 if (ret) {
 630                         ret = CMD_ERROR;
 631                         goto end;
 632                 }
 633
 634                 /* Success ? */
 635                 ret = mi_lttng_writer_write_element_bool(writer,
 636                                 mi_lttng_element_command_success, success);
 637                 if (ret) {
 638                         ret = CMD_ERROR;
 639                         goto end;
 640                 }
 641
 642                 /* Command element close */
 643                 ret = mi_lttng_writer_command_close(writer);
 644                 if (ret) {
 645                         ret = CMD_ERROR;
 646                         goto end;
 647                 }
 648         }
 649
 650 end:
 651         /* Mi clean-up */
 652         if (writer && mi_lttng_writer_destroy(writer)) {
 653                 /* Preserve original error code */
 654                 ret = ret ? ret : -LTTNG_ERR_MI_IO_FAIL;
 655         }
 656
 657         /* Overwrite ret if an error occurred in create_session() */
 658         ret = command_ret ? command_ret : ret;
 659
 660         poptFreeContext(pc);
 661         return ret;
 662 }