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