src/bin/lttng/commands/enable_channels.cpp

   1 /*
   2  * Copyright (C) 2011 EfficiOS Inc.
   3  *
   4  * SPDX-License-Identifier: GPL-2.0-only
   5  *
   6  */
   7
   8 #define _LGPL_SOURCE
   9 #include "../command.hpp"
  10 #include "../utils.hpp"
  11
  12 #include <common/mi-lttng.hpp>
  13 #include <common/sessiond-comm/sessiond-comm.hpp>
  14 #include <common/utils.hpp>
  15
  16 #include <lttng/domain-internal.hpp>
  17
  18 #include <ctype.h>
  19 #include <inttypes.h>
  20 #include <popt.h>
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <sys/stat.h>
  25 #include <sys/types.h>
  26 #include <unistd.h>
  27
  28 static struct lttng_channel chan_opts;
  29 static int opt_kernel;
  30 static char *opt_session_name;
  31 static int opt_userspace;
  32 static char *opt_output;
  33 static int opt_buffer_uid;
  34 static int opt_buffer_pid;
  35 static int opt_buffer_global;
  36 static struct {
  37         bool set;
  38         uint64_t interval;
  39 } opt_monitor_timer;
  40 static struct {
  41         bool set;
  42         int64_t value;
  43 } opt_blocking_timeout;
  44
  45 static struct mi_writer *writer;
  46
  47 #ifdef LTTNG_EMBED_HELP
  48 static const char help_msg[] =
  49 #include <lttng-enable-channel.1.h>
  50         ;
  51 #endif
  52
  53 enum {
  54         OPT_HELP = 1,
  55         OPT_DISCARD,
  56         OPT_OVERWRITE,
  57         OPT_SUBBUF_SIZE,
  58         OPT_NUM_SUBBUF,
  59         OPT_SWITCH_TIMER,
  60         OPT_MONITOR_TIMER,
  61         OPT_READ_TIMER,
  62         OPT_USERSPACE,
  63         OPT_LIST_OPTIONS,
  64         OPT_TRACEFILE_SIZE,
  65         OPT_TRACEFILE_COUNT,
  66         OPT_BLOCKING_TIMEOUT,
  67 };
  68
  69 static struct lttng_handle *handle;
  70
  71 const char *output_mmap = "mmap";
  72 const char *output_splice = "splice";
  73
  74 static struct poptOption long_options[] = {
  75         /* longName, shortName, argInfo, argPtr, value, descrip, argDesc */
  76         { "help", 'h', POPT_ARG_NONE, nullptr, OPT_HELP, nullptr, nullptr },
  77         { "session", 's', POPT_ARG_STRING, &opt_session_name, 0, nullptr, nullptr },
  78         { "kernel", 'k', POPT_ARG_VAL, &opt_kernel, 1, nullptr, nullptr },
  79         { "userspace", 'u', POPT_ARG_NONE, nullptr, OPT_USERSPACE, nullptr, nullptr },
  80         { "discard", 0, POPT_ARG_NONE, nullptr, OPT_DISCARD, nullptr, nullptr },
  81         { "overwrite", 0, POPT_ARG_NONE, nullptr, OPT_OVERWRITE, nullptr, nullptr },
  82         { "subbuf-size", 0, POPT_ARG_STRING, nullptr, OPT_SUBBUF_SIZE, nullptr, nullptr },
  83         { "num-subbuf", 0, POPT_ARG_INT, nullptr, OPT_NUM_SUBBUF, nullptr, nullptr },
  84         { "switch-timer", 0, POPT_ARG_INT, nullptr, OPT_SWITCH_TIMER, nullptr, nullptr },
  85         { "monitor-timer", 0, POPT_ARG_INT, nullptr, OPT_MONITOR_TIMER, nullptr, nullptr },
  86         { "read-timer", 0, POPT_ARG_INT, nullptr, OPT_READ_TIMER, nullptr, nullptr },
  87         { "list-options", 0, POPT_ARG_NONE, nullptr, OPT_LIST_OPTIONS, nullptr, nullptr },
  88         { "output", 0, POPT_ARG_STRING, &opt_output, 0, nullptr, nullptr },
  89         { "buffers-uid", 0, POPT_ARG_VAL, &opt_buffer_uid, 1, nullptr, nullptr },
  90         { "buffers-pid", 0, POPT_ARG_VAL, &opt_buffer_pid, 1, nullptr, nullptr },
  91         { "buffers-global", 0, POPT_ARG_VAL, &opt_buffer_global, 1, nullptr, nullptr },
  92         { "tracefile-size", 'C', POPT_ARG_INT, nullptr, OPT_TRACEFILE_SIZE, nullptr, nullptr },
  93         { "tracefile-count", 'W', POPT_ARG_INT, nullptr, OPT_TRACEFILE_COUNT, nullptr, nullptr },
  94         { "blocking-timeout", 0, POPT_ARG_INT, nullptr, OPT_BLOCKING_TIMEOUT, nullptr, nullptr },
  95         { nullptr, 0, 0, nullptr, 0, nullptr, nullptr }
  96 };
  97
  98 /*
  99  * Set default attributes depending on those already defined from the command
 100  * line.
 101  */
 102 static void set_default_attr(struct lttng_domain *dom)
 103 {
 104         struct lttng_channel_attr default_attr;
 105
 106         memset(&default_attr, 0, sizeof(default_attr));
 107
 108         /* Set attributes */
 109         lttng_channel_set_default_attr(dom, &default_attr);
 110
 111         if (chan_opts.attr.overwrite == -1) {
 112                 chan_opts.attr.overwrite = default_attr.overwrite;
 113         }
 114         if (chan_opts.attr.subbuf_size == -1) {
 115                 chan_opts.attr.subbuf_size = default_attr.subbuf_size;
 116         }
 117         if (chan_opts.attr.num_subbuf == -1) {
 118                 chan_opts.attr.num_subbuf = default_attr.num_subbuf;
 119         }
 120         if (chan_opts.attr.switch_timer_interval == -1) {
 121                 chan_opts.attr.switch_timer_interval = default_attr.switch_timer_interval;
 122         }
 123         if (chan_opts.attr.read_timer_interval == -1) {
 124                 chan_opts.attr.read_timer_interval = default_attr.read_timer_interval;
 125         }
 126         if ((int) chan_opts.attr.output == -1) {
 127                 chan_opts.attr.output = default_attr.output;
 128         }
 129         if (chan_opts.attr.tracefile_count == -1) {
 130                 chan_opts.attr.tracefile_count = default_attr.tracefile_count;
 131         }
 132         if (chan_opts.attr.tracefile_size == -1) {
 133                 chan_opts.attr.tracefile_size = default_attr.tracefile_size;
 134         }
 135 }
 136
 137 /*
 138  * Adding channel using the lttng API.
 139  */
 140 static int enable_channel(char *session_name, char *channel_list)
 141 {
 142         struct lttng_channel *channel = nullptr;
 143         int ret = CMD_SUCCESS, warn = 0, error = 0, success = 0;
 144         char *channel_name;
 145         struct lttng_domain dom;
 146
 147         memset(&dom, 0, sizeof(dom));
 148
 149         /* Validate options. */
 150         if (opt_kernel) {
 151                 if (opt_blocking_timeout.set) {
 152                         ERR("Retry timeout option not supported for kernel domain (-k)");
 153                         ret = CMD_ERROR;
 154                         goto error;
 155                 }
 156         }
 157
 158         /* Create lttng domain */
 159         if (opt_kernel) {
 160                 dom.type = LTTNG_DOMAIN_KERNEL;
 161                 dom.buf_type = LTTNG_BUFFER_GLOBAL;
 162                 if (opt_buffer_uid || opt_buffer_pid) {
 163                         ERR("Buffer type not supported for domain -k");
 164                         ret = CMD_ERROR;
 165                         goto error;
 166                 }
 167         } else if (opt_userspace) {
 168                 dom.type = LTTNG_DOMAIN_UST;
 169                 if (opt_buffer_pid) {
 170                         dom.buf_type = LTTNG_BUFFER_PER_PID;
 171                 } else {
 172                         if (opt_buffer_global) {
 173                                 ERR("Buffer type not supported for domain -u");
 174                                 ret = CMD_ERROR;
 175                                 goto error;
 176                         }
 177                         dom.buf_type = LTTNG_BUFFER_PER_UID;
 178                 }
 179         } else {
 180                 /* Checked by the caller. */
 181                 abort();
 182         }
 183
 184         set_default_attr(&dom);
 185
 186         if (chan_opts.attr.tracefile_size == 0 && chan_opts.attr.tracefile_count) {
 187                 ERR("Missing option --tracefile-size. "
 188                     "A file count without a size won't do anything.");
 189                 ret = CMD_ERROR;
 190                 goto error;
 191         }
 192
 193         if ((chan_opts.attr.tracefile_size > 0) &&
 194             (chan_opts.attr.tracefile_size < chan_opts.attr.subbuf_size)) {
 195                 WARN("Tracefile size rounded up from (%" PRIu64 ") to subbuffer size (%" PRIu64 ")",
 196                      chan_opts.attr.tracefile_size,
 197                      chan_opts.attr.subbuf_size);
 198                 chan_opts.attr.tracefile_size = chan_opts.attr.subbuf_size;
 199         }
 200
 201         /* Setting channel output */
 202         if (opt_output) {
 203                 if (!strncmp(output_mmap, opt_output, strlen(output_mmap))) {
 204                         chan_opts.attr.output = LTTNG_EVENT_MMAP;
 205                 } else if (!strncmp(output_splice, opt_output, strlen(output_splice))) {
 206                         chan_opts.attr.output = LTTNG_EVENT_SPLICE;
 207                 } else {
 208                         ERR("Unknown output type %s. Possible values are: %s, %s\n",
 209                             opt_output,
 210                             output_mmap,
 211                             output_splice);
 212                         ret = CMD_ERROR;
 213                         goto error;
 214                 }
 215         }
 216
 217         handle = lttng_create_handle(session_name, &dom);
 218         if (handle == nullptr) {
 219                 ret = -1;
 220                 goto error;
 221         }
 222
 223         /* Mi open channels element */
 224         if (lttng_opt_mi) {
 225                 LTTNG_ASSERT(writer);
 226                 ret = mi_lttng_channels_open(writer);
 227                 if (ret) {
 228                         ret = CMD_ERROR;
 229                         goto error;
 230                 }
 231         }
 232
 233         /* Strip channel list (format: chan1,chan2,...) */
 234         channel_name = strtok(channel_list, ",");
 235         while (channel_name != nullptr) {
 236                 void *extended_ptr;
 237
 238                 /* Validate channel name's length */
 239                 if (strlen(channel_name) >= sizeof(chan_opts.name)) {
 240                         ERR("Channel name is too long (max. %zu characters)",
 241                             sizeof(chan_opts.name) - 1);
 242                         error = 1;
 243                         goto skip_enable;
 244                 }
 245
 246                 /*
 247                  * A dynamically-allocated channel is used in order to allow
 248                  * the configuration of extended attributes (post-2.9).
 249                  */
 250                 channel = lttng_channel_create(&dom);
 251                 if (!channel) {
 252                         ERR("Unable to create channel object");
 253                         error = 1;
 254                         goto error;
 255                 }
 256
 257                 /* Copy channel name */
 258                 strcpy(channel->name, channel_name);
 259                 channel->enabled = 1;
 260                 extended_ptr = channel->attr.extended.ptr;
 261                 memcpy(&channel->attr, &chan_opts.attr, sizeof(chan_opts.attr));
 262                 channel->attr.extended.ptr = extended_ptr;
 263                 if (opt_monitor_timer.set) {
 264                         ret = lttng_channel_set_monitor_timer_interval(channel,
 265                                                                        opt_monitor_timer.interval);
 266                         if (ret) {
 267                                 ERR("Failed to set the channel's monitor timer interval");
 268                                 error = 1;
 269                                 goto error;
 270                         }
 271                 }
 272                 if (opt_blocking_timeout.set) {
 273                         ret = lttng_channel_set_blocking_timeout(channel,
 274                                                                  opt_blocking_timeout.value);
 275                         if (ret) {
 276                                 ERR("Failed to set the channel's blocking timeout");
 277                                 error = 1;
 278                                 goto error;
 279                         }
 280                 }
 281
 282                 DBG("Enabling channel %s", channel_name);
 283
 284                 ret = lttng_enable_channel(handle, channel);
 285                 if (ret < 0) {
 286                         success = 0;
 287                         switch (-ret) {
 288                         case LTTNG_ERR_KERN_CHAN_EXIST:
 289                         case LTTNG_ERR_UST_CHAN_EXIST:
 290                         case LTTNG_ERR_CHAN_EXIST:
 291                                 WARN("Channel %s: %s (session %s)",
 292                                      channel_name,
 293                                      lttng_strerror(ret),
 294                                      session_name);
 295                                 warn = 1;
 296                                 break;
 297                         case LTTNG_ERR_INVALID_CHANNEL_NAME:
 298                                 ERR("Invalid channel name: \"%s\". "
 299                                     "Channel names may not start with '.', and "
 300                                     "may not contain '/'.",
 301                                     channel_name);
 302                                 error = 1;
 303                                 break;
 304                         default:
 305                                 ERR("Channel %s: %s (session %s)",
 306                                     channel_name,
 307                                     lttng_strerror(ret),
 308                                     session_name);
 309                                 error = 1;
 310                                 break;
 311                         }
 312                 } else {
 313                         MSG("%s channel %s enabled for session %s",
 314                             lttng_domain_type_str(dom.type),
 315                             channel_name,
 316                             session_name);
 317                         success = 1;
 318                 }
 319
 320         skip_enable:
 321                 if (lttng_opt_mi) {
 322                         /* Mi print the channel element and leave it open */
 323                         ret = mi_lttng_channel(writer, channel, 1);
 324                         if (ret) {
 325                                 ret = CMD_ERROR;
 326                                 goto error;
 327                         }
 328
 329                         /* Individual Success ? */
 330                         ret = mi_lttng_writer_write_element_bool(
 331                                 writer, mi_lttng_element_command_success, success);
 332                         if (ret) {
 333                                 ret = CMD_ERROR;
 334                                 goto error;
 335                         }
 336
 337                         /* Close channel element */
 338                         ret = mi_lttng_writer_close_element(writer);
 339                         if (ret) {
 340                                 ret = CMD_ERROR;
 341                                 goto error;
 342                         }
 343                 }
 344
 345                 /* Next channel */
 346                 channel_name = strtok(nullptr, ",");
 347                 lttng_channel_destroy(channel);
 348                 channel = nullptr;
 349         }
 350
 351         if (lttng_opt_mi) {
 352                 /* Close channels element */
 353                 ret = mi_lttng_writer_close_element(writer);
 354                 if (ret) {
 355                         ret = CMD_ERROR;
 356                         goto error;
 357                 }
 358         }
 359
 360         ret = CMD_SUCCESS;
 361
 362 error:
 363         if (channel) {
 364                 lttng_channel_destroy(channel);
 365         }
 366         /* If more important error happen bypass the warning */
 367         if (!ret && warn) {
 368                 ret = CMD_WARNING;
 369         }
 370         /* If more important error happen bypass the warning */
 371         if (!ret && error) {
 372                 ret = CMD_ERROR;
 373         }
 374
 375         lttng_destroy_handle(handle);
 376
 377         return ret;
 378 }
 379
 380 /*
 381  * Default value for channel configuration.
 382  */
 383 static void init_channel_config()
 384 {
 385         /*
 386          * Put -1 everywhere so we can identify those set by the command line and
 387          * those needed to be set by the default values.
 388          */
 389         memset(&chan_opts.attr, -1, sizeof(chan_opts.attr));
 390         chan_opts.attr.extended.ptr = nullptr;
 391 }
 392
 393 /*
 394  * Add channel to trace session
 395  */
 396 int cmd_enable_channels(int argc, const char **argv)
 397 {
 398         int opt, ret = CMD_SUCCESS, command_ret = CMD_SUCCESS, success = 1;
 399         static poptContext pc;
 400         char *session_name = nullptr;
 401         char *channel_list = nullptr;
 402         char *opt_arg = nullptr;
 403         const char *arg_channel_list = nullptr;
 404         const char *leftover = nullptr;
 405
 406         init_channel_config();
 407
 408         pc = poptGetContext(nullptr, argc, argv, long_options, 0);
 409         poptReadDefaultConfig(pc, 0);
 410
 411         while ((opt = poptGetNextOpt(pc)) != -1) {
 412                 switch (opt) {
 413                 case OPT_HELP:
 414                         SHOW_HELP();
 415                         goto end;
 416                 case OPT_DISCARD:
 417                         chan_opts.attr.overwrite = 0;
 418                         DBG("Channel set to discard");
 419                         break;
 420                 case OPT_OVERWRITE:
 421                         chan_opts.attr.overwrite = 1;
 422                         DBG("Channel set to overwrite");
 423                         break;
 424                 case OPT_SUBBUF_SIZE:
 425                 {
 426                         uint64_t rounded_size;
 427                         int order;
 428
 429                         /* Parse the size */
 430                         opt_arg = poptGetOptArg(pc);
 431                         if (utils_parse_size_suffix(opt_arg, &chan_opts.attr.subbuf_size) < 0 ||
 432                             !chan_opts.attr.subbuf_size) {
 433                                 ERR("Wrong value in --subbuf-size parameter: %s", opt_arg);
 434                                 ret = CMD_ERROR;
 435                                 goto end;
 436                         }
 437
 438                         order = get_count_order_u64(chan_opts.attr.subbuf_size);
 439                         LTTNG_ASSERT(order >= 0);
 440                         rounded_size = 1ULL << order;
 441                         if (rounded_size < chan_opts.attr.subbuf_size) {
 442                                 ERR("The subbuf size (%" PRIu64 ") is rounded and overflows!",
 443                                     chan_opts.attr.subbuf_size);
 444                                 ret = CMD_ERROR;
 445                                 goto end;
 446                         }
 447
 448                         if (rounded_size != chan_opts.attr.subbuf_size) {
 449                                 WARN("The subbuf size (%" PRIu64
 450                                      ") is rounded to the next power of 2 (%" PRIu64 ")",
 451                                      chan_opts.attr.subbuf_size,
 452                                      rounded_size);
 453                                 chan_opts.attr.subbuf_size = rounded_size;
 454                         }
 455
 456                         /* Should now be power of 2 */
 457                         LTTNG_ASSERT(
 458                                 !((chan_opts.attr.subbuf_size - 1) & chan_opts.attr.subbuf_size));
 459
 460                         DBG("Channel subbuf size set to %" PRIu64, chan_opts.attr.subbuf_size);
 461                         break;
 462                 }
 463                 case OPT_NUM_SUBBUF:
 464                 {
 465                         uint64_t rounded_size;
 466                         int order;
 467
 468                         errno = 0;
 469                         opt_arg = poptGetOptArg(pc);
 470                         chan_opts.attr.num_subbuf = strtoull(opt_arg, nullptr, 0);
 471                         if (errno != 0 || !chan_opts.attr.num_subbuf || !isdigit(opt_arg[0])) {
 472                                 ERR("Wrong value in --num-subbuf parameter: %s", opt_arg);
 473                                 ret = CMD_ERROR;
 474                                 goto end;
 475                         }
 476
 477                         order = get_count_order_u64(chan_opts.attr.num_subbuf);
 478                         LTTNG_ASSERT(order >= 0);
 479                         rounded_size = 1ULL << order;
 480                         if (rounded_size < chan_opts.attr.num_subbuf) {
 481                                 ERR("The number of subbuffers (%" PRIu64
 482                                     ") is rounded and overflows!",
 483                                     chan_opts.attr.num_subbuf);
 484                                 ret = CMD_ERROR;
 485                                 goto end;
 486                         }
 487
 488                         if (rounded_size != chan_opts.attr.num_subbuf) {
 489                                 WARN("The number of subbuffers (%" PRIu64
 490                                      ") is rounded to the next power of 2 (%" PRIu64 ")",
 491                                      chan_opts.attr.num_subbuf,
 492                                      rounded_size);
 493                                 chan_opts.attr.num_subbuf = rounded_size;
 494                         }
 495
 496                         /* Should now be power of 2 */
 497                         LTTNG_ASSERT(
 498                                 !((chan_opts.attr.num_subbuf - 1) & chan_opts.attr.num_subbuf));
 499
 500                         DBG("Channel subbuf num set to %" PRIu64, chan_opts.attr.num_subbuf);
 501                         break;
 502                 }
 503                 case OPT_SWITCH_TIMER:
 504                 {
 505                         uint64_t v;
 506
 507                         errno = 0;
 508                         opt_arg = poptGetOptArg(pc);
 509
 510                         if (utils_parse_time_suffix(opt_arg, &v) < 0) {
 511                                 ERR("Wrong value for --switch-timer parameter: %s", opt_arg);
 512                                 ret = CMD_ERROR;
 513                                 goto end;
 514                         }
 515
 516                         if (v != (uint32_t) v) {
 517                                 ERR("32-bit overflow in --switch-timer parameter: %s", opt_arg);
 518                                 ret = CMD_ERROR;
 519                                 goto end;
 520                         }
 521                         chan_opts.attr.switch_timer_interval = (uint32_t) v;
 522                         DBG("Channel switch timer interval set to %d %s",
 523                             chan_opts.attr.switch_timer_interval,
 524                             USEC_UNIT);
 525                         break;
 526                 }
 527                 case OPT_READ_TIMER:
 528                 {
 529                         uint64_t v;
 530
 531                         errno = 0;
 532                         opt_arg = poptGetOptArg(pc);
 533
 534                         if (utils_parse_time_suffix(opt_arg, &v) < 0) {
 535                                 ERR("Wrong value for --read-timer parameter: %s", opt_arg);
 536                                 ret = CMD_ERROR;
 537                                 goto end;
 538                         }
 539
 540                         if (v != (uint32_t) v) {
 541                                 ERR("32-bit overflow in --read-timer parameter: %s", opt_arg);
 542                                 ret = CMD_ERROR;
 543                                 goto end;
 544                         }
 545                         chan_opts.attr.read_timer_interval = (uint32_t) v;
 546                         DBG("Channel read timer interval set to %d %s",
 547                             chan_opts.attr.read_timer_interval,
 548                             USEC_UNIT);
 549                         break;
 550                 }
 551                 case OPT_MONITOR_TIMER:
 552                 {
 553                         uint64_t v;
 554
 555                         errno = 0;
 556                         opt_arg = poptGetOptArg(pc);
 557
 558                         if (utils_parse_time_suffix(opt_arg, &v) < 0) {
 559                                 ERR("Wrong value for --monitor-timer parameter: %s", opt_arg);
 560                                 ret = CMD_ERROR;
 561                                 goto end;
 562                         }
 563                         opt_monitor_timer.interval = (uint64_t) v;
 564                         opt_monitor_timer.set = true;
 565                         DBG("Channel monitor timer interval set to %" PRIu64 " %s",
 566                             opt_monitor_timer.interval,
 567                             USEC_UNIT);
 568                         break;
 569                 }
 570                 case OPT_BLOCKING_TIMEOUT:
 571                 {
 572                         uint64_t v;
 573                         long long v_msec;
 574
 575                         errno = 0;
 576                         opt_arg = poptGetOptArg(pc);
 577
 578                         if (strcmp(opt_arg, "inf") == 0) {
 579                                 opt_blocking_timeout.value = (int64_t) -1;
 580                                 opt_blocking_timeout.set = true;
 581                                 DBG("Channel blocking timeout set to infinity");
 582                                 break;
 583                         }
 584
 585                         if (utils_parse_time_suffix(opt_arg, &v) < 0) {
 586                                 ERR("Wrong value for --blocking-timeout parameter: %s", opt_arg);
 587                                 ret = CMD_ERROR;
 588                                 goto end;
 589                         }
 590
 591                         /*
 592                          * While LTTng-UST and LTTng-tools will accept a
 593                          * blocking timeout expressed in µs, the current
 594                          * tracer implementation relies on poll() which
 595                          * takes an "int timeout" parameter expressed in
 596                          * msec.
 597                          *
 598                          * Since the error reporting from the tracer is
 599                          * not precise, we perform this check here to
 600                          * provide a helpful error message in case of
 601                          * overflow.
 602                          *
 603                          * The setter (liblttng-ctl) also performs an
 604                          * equivalent check.
 605                          */
 606                         v_msec = v / 1000;
 607                         if (v_msec != (int32_t) v_msec) {
 608                                 ERR("32-bit milliseconds overflow in --blocking-timeout parameter: %s",
 609                                     opt_arg);
 610                                 ret = CMD_ERROR;
 611                                 goto end;
 612                         }
 613
 614                         opt_blocking_timeout.value = (int64_t) v;
 615                         opt_blocking_timeout.set = true;
 616                         DBG("Channel blocking timeout set to %" PRId64 " %s%s",
 617                             opt_blocking_timeout.value,
 618                             USEC_UNIT,
 619                             opt_blocking_timeout.value == 0 ? " (non-blocking)" : "");
 620                         break;
 621                 }
 622                 case OPT_USERSPACE:
 623                         opt_userspace = 1;
 624                         break;
 625                 case OPT_TRACEFILE_SIZE:
 626                         opt_arg = poptGetOptArg(pc);
 627                         if (utils_parse_size_suffix(opt_arg, &chan_opts.attr.tracefile_size) < 0) {
 628                                 ERR("Wrong value in --tracefile-size parameter: %s", opt_arg);
 629                                 ret = CMD_ERROR;
 630                                 goto end;
 631                         }
 632                         DBG("Maximum tracefile size set to %" PRIu64,
 633                             chan_opts.attr.tracefile_size);
 634                         break;
 635                 case OPT_TRACEFILE_COUNT:
 636                 {
 637                         unsigned long v;
 638
 639                         errno = 0;
 640                         opt_arg = poptGetOptArg(pc);
 641                         v = strtoul(opt_arg, nullptr, 0);
 642                         if (errno != 0 || !isdigit(opt_arg[0])) {
 643                                 ERR("Wrong value in --tracefile-count parameter: %s", opt_arg);
 644                                 ret = CMD_ERROR;
 645                                 goto end;
 646                         }
 647                         if (v != (uint32_t) v) {
 648                                 ERR("32-bit overflow in --tracefile-count parameter: %s", opt_arg);
 649                                 ret = CMD_ERROR;
 650                                 goto end;
 651                         }
 652                         chan_opts.attr.tracefile_count = (uint32_t) v;
 653                         DBG("Maximum tracefile count set to %" PRIu64,
 654                             chan_opts.attr.tracefile_count);
 655                         break;
 656                 }
 657                 case OPT_LIST_OPTIONS:
 658                         list_cmd_options(stdout, long_options);
 659                         goto end;
 660                 default:
 661                         ret = CMD_UNDEFINED;
 662                         goto end;
 663                 }
 664
 665                 if (opt_arg) {
 666                         free(opt_arg);
 667                         opt_arg = nullptr;
 668                 }
 669         }
 670
 671         ret = print_missing_or_multiple_domains(opt_kernel + opt_userspace, false);
 672         if (ret) {
 673                 ret = CMD_ERROR;
 674                 goto end;
 675         }
 676
 677         if (chan_opts.attr.overwrite == 1 && opt_blocking_timeout.set &&
 678             opt_blocking_timeout.value != 0) {
 679                 ERR("You cannot specify --overwrite and --blocking-timeout=N, "
 680                     "where N is different than 0");
 681                 ret = CMD_ERROR;
 682                 goto end;
 683         }
 684
 685         /* Mi check */
 686         if (lttng_opt_mi) {
 687                 writer = mi_lttng_writer_create(fileno(stdout), lttng_opt_mi);
 688                 if (!writer) {
 689                         ret = -LTTNG_ERR_NOMEM;
 690                         goto end;
 691                 }
 692
 693                 /* Open command element */
 694                 ret = mi_lttng_writer_command_open(writer,
 695                                                    mi_lttng_element_command_enable_channels);
 696                 if (ret) {
 697                         ret = CMD_ERROR;
 698                         goto end;
 699                 }
 700
 701                 /* Open output element */
 702                 ret = mi_lttng_writer_open_element(writer, mi_lttng_element_command_output);
 703                 if (ret) {
 704                         ret = CMD_ERROR;
 705                         goto end;
 706                 }
 707         }
 708
 709         arg_channel_list = poptGetArg(pc);
 710         if (arg_channel_list == nullptr) {
 711                 ERR("Missing channel name.");
 712                 ret = CMD_ERROR;
 713                 success = 0;
 714                 goto mi_closing;
 715         }
 716
 717         channel_list = strdup(arg_channel_list);
 718         if (channel_list == nullptr) {
 719                 PERROR("Failed to copy channel name");
 720                 ret = CMD_ERROR;
 721                 success = 0;
 722                 goto mi_closing;
 723         }
 724
 725         leftover = poptGetArg(pc);
 726         if (leftover) {
 727                 ERR("Unknown argument: %s", leftover);
 728                 ret = CMD_ERROR;
 729                 success = 0;
 730                 goto mi_closing;
 731         }
 732
 733         if (!opt_session_name) {
 734                 session_name = get_session_name();
 735                 if (session_name == nullptr) {
 736                         command_ret = CMD_ERROR;
 737                         success = 0;
 738                         goto mi_closing;
 739                 }
 740         } else {
 741                 session_name = opt_session_name;
 742         }
 743
 744         command_ret = enable_channel(session_name, channel_list);
 745         if (command_ret) {
 746                 success = 0;
 747         }
 748
 749 mi_closing:
 750         /* Mi closing */
 751         if (lttng_opt_mi) {
 752                 /* Close  output element */
 753                 ret = mi_lttng_writer_close_element(writer);
 754                 if (ret) {
 755                         goto end;
 756                 }
 757
 758                 /* Success ? */
 759                 ret = mi_lttng_writer_write_element_bool(
 760                         writer, mi_lttng_element_command_success, success);
 761                 if (ret) {
 762                         goto end;
 763                 }
 764
 765                 /* Command element close */
 766                 ret = mi_lttng_writer_command_close(writer);
 767                 if (ret) {
 768                         goto end;
 769                 }
 770         }
 771
 772 end:
 773         /* Mi clean-up */
 774         if (writer && mi_lttng_writer_destroy(writer)) {
 775                 /* Preserve original error code */
 776                 ret = ret ? ret : LTTNG_ERR_MI_IO_FAIL;
 777         }
 778
 779         if (!opt_session_name && session_name) {
 780                 free(session_name);
 781         }
 782
 783         free(channel_list);
 784
 785         /* Overwrite ret if an error occurred when enable_channel */
 786         ret = command_ret ? command_ret : ret;
 787         poptFreeContext(pc);
 788         free(opt_arg);
 789         return ret;
 790 }