src/bin/lttng/commands/snapshot.c

   1 /*
   2  * Copyright (C) 2013 - David Goulet <dgoulet@efficios.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License, version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along with
  14  * this program; if not, write to the Free Software Foundation, Inc., 51
  15  * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  16  */
  17
  18 #define _GNU_SOURCE
  19 #include <assert.h>
  20 #include <inttypes.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 <unistd.h>
  28 #include <assert.h>
  29
  30 #include <common/utils.h>
  31 #include <common/mi-lttng.h>
  32 #include <lttng/snapshot.h>
  33
  34 #include "../command.h"
  35
  36 static const char *opt_session_name;
  37 static const char *opt_output_name;
  38 static const char *opt_data_url;
  39 static const char *opt_ctrl_url;
  40 static const char *current_session_name;
  41 static uint64_t opt_max_size;
  42
  43 /* Stub for the cmd struct actions. */
  44 static int cmd_add_output(int argc, const char **argv);
  45 static int cmd_del_output(int argc, const char **argv);
  46 static int cmd_list_output(int argc, const char **argv);
  47 static int cmd_record(int argc, const char **argv);
  48
  49 static const char *indent4 = "    ";
  50
  51 enum {
  52         OPT_HELP = 1,
  53         OPT_LIST_OPTIONS,
  54         OPT_MAX_SIZE,
  55         OPT_LIST_COMMANDS,
  56 };
  57
  58 static struct mi_writer *writer;
  59
  60 static struct poptOption snapshot_opts[] = {
  61         /* longName, shortName, argInfo, argPtr, value, descrip, argDesc */
  62         {"help",      'h', POPT_ARG_NONE, 0, OPT_HELP, 0, 0},
  63         {"session",      's', POPT_ARG_STRING, &opt_session_name, 0, 0, 0},
  64         {"ctrl-url",     'C', POPT_ARG_STRING, &opt_ctrl_url, 0, 0, 0},
  65         {"data-url",     'D', POPT_ARG_STRING, &opt_data_url, 0, 0, 0},
  66         {"name",         'n', POPT_ARG_STRING, &opt_output_name, 0, 0, 0},
  67         {"max-size",     'm', POPT_ARG_STRING, 0, OPT_MAX_SIZE, 0, 0},
  68         {"list-options",   0, POPT_ARG_NONE, NULL, OPT_LIST_OPTIONS, NULL, NULL},
  69         {"list-commands",  0, POPT_ARG_NONE, NULL, OPT_LIST_COMMANDS},
  70         {0, 0, 0, 0, 0, 0, 0}
  71 };
  72
  73 static struct cmd_struct actions[] = {
  74         { "add-output", cmd_add_output },
  75         { "del-output", cmd_del_output },
  76         { "list-output", cmd_list_output },
  77         { "record", cmd_record },
  78         { NULL, NULL }  /* Array closure */
  79 };
  80
  81 /*
  82  * usage
  83  */
  84 static void usage(FILE *ofp)
  85 {
  86         fprintf(ofp, "usage: lttng snapshot [OPTION] ACTION\n");
  87         fprintf(ofp, "\n");
  88         fprintf(ofp, "Actions:\n");
  89         fprintf(ofp, "   add-output [-m <SIZE>] [-s <NAME>] [-n <NAME>] <URL> | -C <URL> -D <URL>\n");
  90         fprintf(ofp, "      Setup and add an snapshot output for a session.\n");
  91         fprintf(ofp, "\n");
  92         fprintf(ofp, "   del-output ID | NAME [-s <NAME>]\n");
  93         fprintf(ofp, "      Delete an output for a session using the ID.\n");
  94         fprintf(ofp, "\n");
  95         fprintf(ofp, "   list-output [-s <NAME>]\n");
  96         fprintf(ofp, "      List the output of a session.\n");
  97         fprintf(ofp, "\n");
  98         fprintf(ofp, "   record [-m <SIZE>] [-s <NAME>] [-n <NAME>] [<URL> | -C <URL> -D <URL>]\n");
  99         fprintf(ofp, "      Snapshot a session's buffer(s) for all domains. If an URL is\n");
 100         fprintf(ofp, "      specified, it is used instead of a previously added output.\n");
 101         fprintf(ofp, "      Specifying only a name or/a size will override the current output value.\n");
 102         fprintf(ofp, "      For instance, you can record a snapshot with a custom maximum size\n");
 103         fprintf(ofp, "      or with a different name.\n");
 104         fprintf(ofp, "\n");
 105         fprintf(ofp, "Options:\n");
 106         fprintf(ofp, "  -h, --help           Show this help\n");
 107         fprintf(ofp, "      --list-options   Simple listing of options\n");
 108         fprintf(ofp, "  -s, --session NAME   Apply to session name\n");
 109         fprintf(ofp, "  -n, --name NAME      Name of the output or snapshot\n");
 110         fprintf(ofp, "  -m, --max-size SIZE  Maximum bytes size of the snapshot {+k,+M,+G}\n");
 111         fprintf(ofp, "  -C, --ctrl-url URL   Set control path URL. (Must use -D also)\n");
 112         fprintf(ofp, "  -D, --data-url URL   Set data path URL. (Must use -C also)\n");
 113         fprintf(ofp, "\n");
 114 }
 115
 116 /*
 117  * Count and return the number of arguments in argv.
 118  */
 119 static int count_arguments(const char **argv)
 120 {
 121         int i = 0;
 122
 123         assert(argv);
 124
 125         while (argv[i] != NULL) {
 126                 i++;
 127         }
 128
 129         return i;
 130 }
 131
 132 /*
 133  * Create a snapshot output object from arguments using the given URL.
 134  *
 135  * Return a newly allocated object or NULL on error.
 136  */
 137 static struct lttng_snapshot_output *create_output_from_args(const char *url)
 138 {
 139         int ret = 0;
 140         struct lttng_snapshot_output *output = NULL;
 141
 142         output = lttng_snapshot_output_create();
 143         if (!output) {
 144                 goto error_create;
 145         }
 146
 147         if (url) {
 148                 ret = lttng_snapshot_output_set_ctrl_url(url, output);
 149                 if (ret < 0) {
 150                         goto error;
 151                 }
 152         } else if (opt_ctrl_url) {
 153                 ret = lttng_snapshot_output_set_ctrl_url(opt_ctrl_url, output);
 154                 if (ret < 0) {
 155                         goto error;
 156                 }
 157         }
 158
 159         if (opt_data_url) {
 160                 ret = lttng_snapshot_output_set_data_url(opt_data_url, output);
 161                 if (ret < 0) {
 162                         goto error;
 163                 }
 164         }
 165
 166         if (opt_max_size) {
 167                 ret = lttng_snapshot_output_set_size(opt_max_size, output);
 168                 if (ret < 0) {
 169                         goto error;
 170                 }
 171         }
 172
 173         if (opt_output_name) {
 174                 ret = lttng_snapshot_output_set_name(opt_output_name, output);
 175                 if (ret < 0) {
 176                         goto error;
 177                 }
 178         }
 179
 180         return output;
 181
 182 error:
 183         lttng_snapshot_output_destroy(output);
 184 error_create:
 185         return NULL;
 186 }
 187
 188 static int mi_list_output(void)
 189 {
 190         int ret;
 191         struct lttng_snapshot_output *s_iter;
 192         struct lttng_snapshot_output_list *list;
 193
 194         assert(writer);
 195
 196         ret = lttng_snapshot_list_output(current_session_name, &list);
 197         if (ret < 0) {
 198                 goto error;
 199         }
 200
 201         ret = mi_lttng_snapshot_output_session_name(writer, current_session_name);
 202         if (ret) {
 203                 ret = CMD_ERROR;
 204                 goto end;
 205         }
 206
 207         while ((s_iter = lttng_snapshot_output_list_get_next(list)) != NULL) {
 208                 ret = mi_lttng_snapshot_list_output(writer, s_iter);
 209                 if (ret) {
 210                         ret = CMD_ERROR;
 211                         goto end;
 212                 }
 213         }
 214
 215
 216         /* Close snapshot snapshots element */
 217         ret = mi_lttng_writer_close_element(writer);
 218         if (ret) {
 219                 ret = CMD_ERROR;
 220                 goto end;
 221         }
 222
 223         /* Close snapshot session element */
 224         ret = mi_lttng_writer_close_element(writer);
 225         if (ret) {
 226                 ret = CMD_ERROR;
 227         }
 228 end:
 229         lttng_snapshot_output_list_destroy(list);
 230 error:
 231         return ret;
 232 }
 233
 234 static int list_output(void)
 235 {
 236         int ret, output_seen = 0;
 237         struct lttng_snapshot_output *s_iter;
 238         struct lttng_snapshot_output_list *list;
 239
 240         ret = lttng_snapshot_list_output(current_session_name, &list);
 241         if (ret < 0) {
 242                 goto error;
 243         }
 244
 245         MSG("Snapshot output list for session %s", current_session_name);
 246
 247         while ((s_iter = lttng_snapshot_output_list_get_next(list)) != NULL) {
 248                 MSG("%s[%" PRIu32 "] %s: %s (max-size: %" PRId64 ")", indent4,
 249                                 lttng_snapshot_output_get_id(s_iter),
 250                                 lttng_snapshot_output_get_name(s_iter),
 251                                 lttng_snapshot_output_get_ctrl_url(s_iter),
 252                                 lttng_snapshot_output_get_maxsize(s_iter));
 253                 output_seen = 1;
 254         }
 255
 256         lttng_snapshot_output_list_destroy(list);
 257
 258         if (!output_seen) {
 259                 MSG("%sNone", indent4);
 260         }
 261
 262 error:
 263         return ret;
 264 }
 265
 266 /*
 267  * Delete output by ID (machine interface version).
 268  */
 269 static int mi_del_output(uint32_t id, const char *name)
 270 {
 271         int ret;
 272         struct lttng_snapshot_output *output = NULL;
 273
 274         assert(writer);
 275
 276         output = lttng_snapshot_output_create();
 277         if (!output) {
 278                 ret = CMD_FATAL;
 279                 goto error;
 280         }
 281
 282         if (name) {
 283                 ret = lttng_snapshot_output_set_name(name, output);
 284         } else if (id != UINT32_MAX) {
 285                 ret = lttng_snapshot_output_set_id(id, output);
 286         } else {
 287                 ret = CMD_ERROR;
 288                 goto error;
 289         }
 290         if (ret < 0) {
 291                 ret = CMD_FATAL;
 292                 goto error;
 293         }
 294
 295         ret = lttng_snapshot_del_output(current_session_name, output);
 296         if (ret < 0) {
 297                 ret = CMD_FATAL;
 298                 goto error;
 299         }
 300
 301         ret = mi_lttng_snapshot_del_output(writer, id, name, current_session_name);
 302         if (ret) {
 303                 ret = CMD_ERROR;
 304         }
 305
 306 error:
 307         lttng_snapshot_output_destroy(output);
 308         return ret;
 309 }
 310
 311 /*
 312  * Delete output by ID.
 313  */
 314 static int del_output(uint32_t id, const char *name)
 315 {
 316         int ret;
 317         struct lttng_snapshot_output *output = NULL;
 318
 319         output = lttng_snapshot_output_create();
 320         if (!output) {
 321                 ret = CMD_FATAL;
 322                 goto error;
 323         }
 324
 325         if (name) {
 326                 ret = lttng_snapshot_output_set_name(name, output);
 327         } else if (id != UINT32_MAX) {
 328                 ret = lttng_snapshot_output_set_id(id, output);
 329         } else {
 330                 ret = CMD_ERROR;
 331                 goto error;
 332         }
 333         if (ret < 0) {
 334                 ret = CMD_FATAL;
 335                 goto error;
 336         }
 337
 338         ret = lttng_snapshot_del_output(current_session_name, output);
 339         if (ret < 0) {
 340                 goto error;
 341         }
 342
 343         if (id != UINT32_MAX) {
 344                 MSG("Snapshot output id %" PRIu32 " successfully deleted for session %s",
 345                                 id, current_session_name);
 346         } else {
 347                 MSG("Snapshot output %s successfully deleted for session %s",
 348                                 name, current_session_name);
 349         }
 350
 351 error:
 352         lttng_snapshot_output_destroy(output);
 353         return ret;
 354 }
 355
 356 /*
 357  * Add output from the user URL (machine interface).
 358  */
 359 static int mi_add_output(const char *url)
 360 {
 361         int ret;
 362         struct lttng_snapshot_output *output = NULL;
 363         char name[NAME_MAX];
 364         const char *n_ptr;
 365
 366         if (!url && (!opt_data_url || !opt_ctrl_url)) {
 367                 ret = CMD_ERROR;
 368                 goto error;
 369         }
 370
 371         output = create_output_from_args(url);
 372         if (!output) {
 373                 ret = CMD_FATAL;
 374                 goto error;
 375         }
 376
 377         /* This call, if successful, populates the id of the output object. */
 378         ret = lttng_snapshot_add_output(current_session_name, output);
 379         if (ret < 0) {
 380                 ret = CMD_ERROR;
 381                 goto error;
 382         }
 383
 384         n_ptr = lttng_snapshot_output_get_name(output);
 385         if (*n_ptr == '\0') {
 386                 int pret;
 387                 pret = snprintf(name, sizeof(name), DEFAULT_SNAPSHOT_NAME "-%" PRIu32,
 388                                 lttng_snapshot_output_get_id(output));
 389                 if (pret < 0) {
 390                         PERROR("snprintf add output name");
 391                 }
 392                 n_ptr = name;
 393         }
 394
 395         ret = mi_lttng_snapshot_add_output(writer, current_session_name, n_ptr,
 396                         output);
 397         if (ret) {
 398                 ret = CMD_ERROR;
 399         }
 400
 401 error:
 402         lttng_snapshot_output_destroy(output);
 403         return ret;
 404 }
 405
 406 /*
 407  * Add output from the user URL.
 408  */
 409 static int add_output(const char *url)
 410 {
 411         int ret;
 412         struct lttng_snapshot_output *output = NULL;
 413         char name[NAME_MAX];
 414         const char *n_ptr;
 415
 416         if (!url && (!opt_data_url || !opt_ctrl_url)) {
 417                 ret = CMD_ERROR;
 418                 goto error;
 419         }
 420
 421         output = create_output_from_args(url);
 422         if (!output) {
 423                 ret = CMD_FATAL;
 424                 goto error;
 425         }
 426
 427         /* This call, if successful, populates the id of the output object. */
 428         ret = lttng_snapshot_add_output(current_session_name, output);
 429         if (ret < 0) {
 430                 goto error;
 431         }
 432
 433         n_ptr = lttng_snapshot_output_get_name(output);
 434         if (*n_ptr == '\0') {
 435                 int pret;
 436                 pret = snprintf(name, sizeof(name), DEFAULT_SNAPSHOT_NAME "-%" PRIu32,
 437                                 lttng_snapshot_output_get_id(output));
 438                 if (pret < 0) {
 439                         PERROR("snprintf add output name");
 440                 }
 441                 n_ptr = name;
 442         }
 443
 444         MSG("Snapshot output successfully added for session %s",
 445                         current_session_name);
 446         MSG("  [%" PRIu32 "] %s: %s (max-size: %" PRId64 ")",
 447                         lttng_snapshot_output_get_id(output), n_ptr,
 448                         lttng_snapshot_output_get_ctrl_url(output),
 449                         lttng_snapshot_output_get_maxsize(output));
 450 error:
 451         lttng_snapshot_output_destroy(output);
 452         return ret;
 453 }
 454
 455 static int cmd_add_output(int argc, const char **argv)
 456 {
 457         int ret;
 458
 459         if (argc < 2 && (!opt_data_url || !opt_ctrl_url)) {
 460                 usage(stderr);
 461                 ret = CMD_ERROR;
 462                 goto end;
 463         }
 464
 465         if (lttng_opt_mi) {
 466                 ret = mi_add_output(argv[1]);
 467         } else {
 468                 ret = add_output(argv[1]);
 469         }
 470
 471 end:
 472         return ret;
 473 }
 474
 475 static int cmd_del_output(int argc, const char **argv)
 476 {
 477         int ret;
 478         char *name;
 479         long id;
 480
 481         if (argc < 2) {
 482                 usage(stderr);
 483                 ret = CMD_ERROR;
 484                 goto end;
 485         }
 486
 487         errno = 0;
 488         id = strtol(argv[1], &name, 10);
 489         if (id == 0 && errno == 0) {
 490                 if (lttng_opt_mi) {
 491                         ret = mi_del_output(UINT32_MAX, name);
 492                 } else {
 493                         ret = del_output(UINT32_MAX, name);
 494                 }
 495         } else if (errno == 0 && *name == '\0') {
 496                 if (lttng_opt_mi) {
 497                         ret = mi_del_output(id, NULL);
 498                 } else {
 499                         ret = del_output(id, NULL);
 500                 }
 501         } else {
 502                 ERR("Argument %s not recognized", argv[1]);
 503                 ret = -1;
 504                 goto end;
 505         }
 506
 507 end:
 508         return ret;
 509 }
 510
 511 static int cmd_list_output(int argc, const char **argv)
 512 {
 513         int ret;
 514
 515         if (lttng_opt_mi) {
 516                 ret = mi_list_output();
 517         } else {
 518                 ret = list_output();
 519         }
 520
 521         return ret;
 522 }
 523
 524 /*
 525  * Do a snapshot record with the URL if one is given (machine interface).
 526  */
 527 static int mi_record(const char *url)
 528 {
 529         int ret;
 530         struct lttng_snapshot_output *output = NULL;
 531
 532         output = create_output_from_args(url);
 533         if (!output) {
 534                 ret = CMD_FATAL;
 535                 goto error;
 536         }
 537
 538         ret = lttng_snapshot_record(current_session_name, output, 0);
 539         if (ret < 0) {
 540                 ret = CMD_ERROR;
 541                 goto error;
 542         }
 543
 544         ret = mi_lttng_snapshot_record(writer, current_session_name, url,
 545                         opt_ctrl_url, opt_data_url);
 546         if (ret) {
 547                 ret = CMD_ERROR;
 548         }
 549
 550 error:
 551         lttng_snapshot_output_destroy(output);
 552         return ret;
 553 }
 554
 555 /*
 556  * Do a snapshot record with the URL if one is given.
 557  */
 558 static int record(const char *url)
 559 {
 560         int ret;
 561         struct lttng_snapshot_output *output = NULL;
 562
 563         output = create_output_from_args(url);
 564         if (!output) {
 565                 ret = CMD_FATAL;
 566                 goto error;
 567         }
 568
 569         ret = lttng_snapshot_record(current_session_name, output, 0);
 570         if (ret < 0) {
 571                 if (ret == -LTTNG_ERR_MAX_SIZE_INVALID) {
 572                         ERR("The minimum size of a snapshot is computed by multiplying "
 573                                         "the total amount of streams with the largest subbuffer "
 574                                         "in the session.");
 575                 }
 576                 goto error;
 577         }
 578
 579         MSG("Snapshot recorded successfully for session %s", current_session_name);
 580
 581         if (url) {
 582                 MSG("Snapshot written at: %s", url);
 583         } else if (opt_ctrl_url) {
 584                 MSG("Snapshot written to ctrl: %s, data: %s", opt_ctrl_url,
 585                                 opt_data_url);
 586         }
 587
 588 error:
 589         lttng_snapshot_output_destroy(output);
 590         return ret;
 591 }
 592
 593 static int cmd_record(int argc, const char **argv)
 594 {
 595         int ret;
 596
 597         if (argc == 2) {
 598                 /* With a given URL */
 599                 if (lttng_opt_mi) {
 600                         ret = mi_record(argv[1]);
 601                 } else {
 602                         ret = record(argv[1]);
 603                 }
 604         } else {
 605                 if (lttng_opt_mi) {
 606                         ret = mi_record(NULL);
 607                 } else {
 608                         ret = record(NULL);
 609                 }
 610         }
 611
 612         return ret;
 613 }
 614
 615 static int handle_command(const char **argv)
 616 {
 617         int ret = CMD_SUCCESS, i = 0, argc, command_ret =  CMD_SUCCESS;
 618         struct cmd_struct *cmd;
 619
 620         if (argv == NULL || (!opt_ctrl_url && opt_data_url) ||
 621                         (opt_ctrl_url && !opt_data_url)) {
 622                 usage(stderr);
 623                 command_ret = CMD_ERROR;
 624                 goto end;
 625         }
 626
 627         argc = count_arguments(argv);
 628
 629         cmd = &actions[i];
 630         while (cmd->func != NULL) {
 631                 /* Find command */
 632                 if (strcmp(argv[0], cmd->name) == 0) {
 633                         if (lttng_opt_mi) {
 634                                 /* Action element */
 635                                 ret = mi_lttng_writer_open_element(writer,
 636                                                 mi_lttng_element_command_action);
 637                                 if (ret) {
 638                                         ret = CMD_ERROR;
 639                                         goto end;
 640                                 }
 641
 642                                 /* Name of the action */
 643                                 ret = mi_lttng_writer_write_element_string(writer,
 644                                                 config_element_name, argv[0]);
 645                                 if (ret) {
 646                                         ret = CMD_ERROR;
 647                                         goto end;
 648                                 }
 649
 650                                 /* Open output element */
 651                                 ret = mi_lttng_writer_open_element(writer,
 652                                                 mi_lttng_element_command_output);
 653                                 if (ret) {
 654                                         ret = CMD_ERROR;
 655                                         goto end;
 656                                 }
 657                         }
 658
 659                         command_ret = cmd->func(argc, argv);
 660
 661                         if (lttng_opt_mi) {
 662                                 /* Close output and action element */
 663                                 ret = mi_lttng_close_multi_element(writer, 2);
 664                                 if (ret) {
 665                                         ret = CMD_ERROR;
 666                                         goto end;
 667                                 }
 668                         }
 669                         goto end;
 670                 }
 671                 i++;
 672                 cmd = &actions[i];
 673         }
 674
 675         ret = -CMD_UNDEFINED;
 676
 677 end:
 678         /* Overwrite ret if an error occured in cmd->func() */
 679         ret = command_ret ? command_ret : ret;
 680         return ret;
 681 }
 682 /*
 683  * The 'snapshot <cmd> <options>' first level command
 684  */
 685 int cmd_snapshot(int argc, const char **argv)
 686 {
 687         int opt, ret = CMD_SUCCESS, command_ret = CMD_SUCCESS, success = 1;
 688         char *session_name = NULL;
 689         static poptContext pc;
 690
 691         pc = poptGetContext(NULL, argc, argv, snapshot_opts, 0);
 692         poptReadDefaultConfig(pc, 0);
 693
 694         /* Mi check */
 695         if (lttng_opt_mi) {
 696                 writer = mi_lttng_writer_create(fileno(stdout), lttng_opt_mi);
 697                 if (!writer) {
 698                         ret = -LTTNG_ERR_NOMEM;
 699                         goto end;
 700                 }
 701
 702                 /* Open command element */
 703                 ret = mi_lttng_writer_command_open(writer,
 704                                 mi_lttng_element_command_snapshot);
 705                 if (ret) {
 706                         ret = CMD_ERROR;
 707                         goto end;
 708                 }
 709
 710                 /* Open output element */
 711                 ret = mi_lttng_writer_open_element(writer,
 712                                 mi_lttng_element_command_output);
 713                 if (ret) {
 714                         ret = CMD_ERROR;
 715                         goto end;
 716                 }
 717         }
 718
 719         while ((opt = poptGetNextOpt(pc)) != -1) {
 720                 switch (opt) {
 721                 case OPT_HELP:
 722                         usage(stdout);
 723                         goto end;
 724                 case OPT_LIST_OPTIONS:
 725                         list_cmd_options(stdout, snapshot_opts);
 726                         goto end;
 727                 case OPT_LIST_COMMANDS:
 728                         list_commands(actions, stdout);
 729                         goto end;
 730                 case OPT_MAX_SIZE:
 731                 {
 732                         uint64_t val;
 733                         const char *opt = poptGetOptArg(pc);
 734
 735                         if (utils_parse_size_suffix((char *) opt, &val) < 0) {
 736                                 ERR("Unable to handle max-size value %s", opt);
 737                                 ret = CMD_ERROR;
 738                                 goto end;
 739                         }
 740
 741                         opt_max_size = val;
 742
 743                         break;
 744                 }
 745                 default:
 746                         usage(stderr);
 747                         ret = CMD_UNDEFINED;
 748                         goto end;
 749                 }
 750         }
 751
 752         if (!opt_session_name) {
 753                 session_name = get_session_name();
 754                 if (session_name == NULL) {
 755                         ret = CMD_ERROR;
 756                         goto end;
 757                 }
 758                 current_session_name = session_name;
 759         } else {
 760                 current_session_name = opt_session_name;
 761         }
 762
 763         command_ret = handle_command(poptGetArgs(pc));
 764         if (command_ret < 0) {
 765                 switch (-command_ret) {
 766                 case LTTNG_ERR_EPERM:
 767                         ERR("The session needs to be set in no output mode (--no-output)");
 768                         break;
 769                 case LTTNG_ERR_SNAPSHOT_NODATA:
 770                         WARN("%s", lttng_strerror(command_ret));
 771                         break;
 772                 default:
 773                         ERR("%s", lttng_strerror(command_ret));
 774                         break;
 775                 }
 776                 success = 0;
 777         }
 778
 779         if (lttng_opt_mi) {
 780                 /* Close output element */
 781                 ret = mi_lttng_writer_close_element(writer);
 782                 if (ret) {
 783                         ret = CMD_ERROR;
 784                         goto end;
 785                 }
 786
 787                 /* Success ? */
 788                 ret = mi_lttng_writer_write_element_bool(writer,
 789                                 mi_lttng_element_command_success, success);
 790                 if (ret) {
 791                         ret = CMD_ERROR;
 792                         goto end;
 793                 }
 794
 795                 /* Command element close */
 796                 ret = mi_lttng_writer_command_close(writer);
 797                 if (ret) {
 798                         ret = CMD_ERROR;
 799                         goto end;
 800                 }
 801         }
 802
 803 end:
 804         /* Mi clean-up */
 805         if (writer && mi_lttng_writer_destroy(writer)) {
 806                 /* Preserve original error code */
 807                 ret = ret ? ret : -LTTNG_ERR_MI_IO_FAIL;
 808         }
 809
 810         if (!opt_session_name) {
 811                 free(session_name);
 812         }
 813
 814         /* Overwrite ret if an error occured during handle_command */
 815         ret = command_ret ? command_ret : ret;
 816         poptFreeContext(pc);
 817         return ret;
 818 }