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/lttng-kernel.hpp>
  13 #include <common/mi-lttng.hpp>
  14 #include <common/sessiond-comm/sessiond-comm.hpp>
  15 #include <common/utils.hpp>
  16
  17 #include <lttng/domain-internal.hpp>
  18
  19 #include <ctype.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
  29 static struct lttng_channel chan_opts;
  30 static int opt_kernel;
  31 static char *opt_session_name;
  32 static int opt_userspace;
  33 static char *opt_output;
  34 static int opt_buffer_uid;
  35 static int opt_buffer_pid;
  36 static int opt_buffer_global;
  37 static struct {
  38         bool set;
  39         uint64_t interval;
  40 } opt_monitor_timer;
  41 static struct {
  42         bool set;
  43         int64_t value;
  44 } opt_blocking_timeout;
  45
  46 static struct mi_writer *writer;
  47
  48 #ifdef LTTNG_EMBED_HELP
  49 static const char help_msg[] =
  50 #include <lttng-enable-channel.1.h>
  51         ;
  52 #endif
  53
  54 enum {
  55         OPT_HELP = 1,
  56         OPT_DISCARD,
  57         OPT_OVERWRITE,
  58         OPT_SUBBUF_SIZE,
  59         OPT_NUM_SUBBUF,
  60         OPT_SWITCH_TIMER,
  61         OPT_MONITOR_TIMER,
  62         OPT_READ_TIMER,
  63         OPT_USERSPACE,
  64         OPT_LIST_OPTIONS,
  65         OPT_TRACEFILE_SIZE,
  66         OPT_TRACEFILE_COUNT,
  67         OPT_BLOCKING_TIMEOUT,
  68 };
  69
  70 static struct lttng_handle *handle;
  71
  72 const char *output_mmap = "mmap";
  73 const char *output_splice = "splice";
  74
  75 static struct poptOption long_options[] = {
  76         /* longName, shortName, argInfo, argPtr, value, descrip, argDesc */
  77         { "help", 'h', POPT_ARG_NONE, nullptr, OPT_HELP, nullptr, nullptr },
  78         { "session", 's', POPT_ARG_STRING, &opt_session_name, 0, nullptr, nullptr },
  79         { "kernel", 'k', POPT_ARG_VAL, &opt_kernel, 1, nullptr, nullptr },
  80         { "userspace", 'u', POPT_ARG_NONE, nullptr, OPT_USERSPACE, nullptr, nullptr },
  81         { "discard", 0, POPT_ARG_NONE, nullptr, OPT_DISCARD, nullptr, nullptr },
  82         { "overwrite", 0, POPT_ARG_NONE, nullptr, OPT_OVERWRITE, nullptr, nullptr },
  83         { "subbuf-size", 0, POPT_ARG_STRING, nullptr, OPT_SUBBUF_SIZE, nullptr, nullptr },
  84         { "num-subbuf", 0, POPT_ARG_INT, nullptr, OPT_NUM_SUBBUF, nullptr, nullptr },
  85         { "switch-timer", 0, POPT_ARG_INT, nullptr, OPT_SWITCH_TIMER, nullptr, nullptr },
  86         { "monitor-timer", 0, POPT_ARG_INT, nullptr, OPT_MONITOR_TIMER, nullptr, nullptr },
  87         { "read-timer", 0, POPT_ARG_INT, nullptr, OPT_READ_TIMER, nullptr, nullptr },
  88         { "list-options", 0, POPT_ARG_NONE, nullptr, OPT_LIST_OPTIONS, nullptr, nullptr },
  89         { "output", 0, POPT_ARG_STRING, &opt_output, 0, nullptr, nullptr },
  90         { "buffers-uid", 0, POPT_ARG_VAL, &opt_buffer_uid, 1, nullptr, nullptr },
  91         { "buffers-pid", 0, POPT_ARG_VAL, &opt_buffer_pid, 1, nullptr, nullptr },
  92         { "buffers-global", 0, POPT_ARG_VAL, &opt_buffer_global, 1, nullptr, nullptr },
  93         { "tracefile-size", 'C', POPT_ARG_INT, nullptr, OPT_TRACEFILE_SIZE, nullptr, nullptr },
  94         { "tracefile-count", 'W', POPT_ARG_INT, nullptr, OPT_TRACEFILE_COUNT, nullptr, nullptr },
  95         { "blocking-timeout", 0, POPT_ARG_INT, nullptr, OPT_BLOCKING_TIMEOUT, nullptr, nullptr },
  96         { nullptr, 0, 0, nullptr, 0, nullptr, nullptr }
  97 };
  98
  99 /*
 100  * Set default attributes depending on those already defined from the command
 101  * line.
 102  */
 103 static void set_default_attr(struct lttng_domain *dom)
 104 {
 105         struct lttng_channel_attr default_attr;
 106
 107         memset(&default_attr, 0, sizeof(default_attr));
 108
 109         /* Set attributes */
 110         lttng_channel_set_default_attr(dom, &default_attr);
 111
 112         if (chan_opts.attr.overwrite == -1) {
 113                 chan_opts.attr.overwrite = default_attr.overwrite;
 114         }
 115         if (chan_opts.attr.subbuf_size == -1) {
 116                 chan_opts.attr.subbuf_size = default_attr.subbuf_size;
 117         }
 118         if (chan_opts.attr.num_subbuf == -1) {
 119                 chan_opts.attr.num_subbuf = default_attr.num_subbuf;
 120         }
 121         if (chan_opts.attr.switch_timer_interval == -1) {
 122                 chan_opts.attr.switch_timer_interval = default_attr.switch_timer_interval;
 123         }
 124         if (chan_opts.attr.read_timer_interval == -1) {
 125                 chan_opts.attr.read_timer_interval = default_attr.read_timer_interval;
 126         }
 127         if ((int) chan_opts.attr.output == -1) {
 128                 chan_opts.attr.output = default_attr.output;
 129         }
 130         if (chan_opts.attr.tracefile_count == -1) {
 131                 chan_opts.attr.tracefile_count = default_attr.tracefile_count;
 132         }
 133         if (chan_opts.attr.tracefile_size == -1) {
 134                 chan_opts.attr.tracefile_size = default_attr.tracefile_size;
 135         }
 136 }
 137
 138 /*
 139  * Adding channel using the lttng API.
 140  */
 141 static int enable_channel(char *session_name, char *channel_list)
 142 {
 143         struct lttng_channel *channel = nullptr;
 144         int ret = CMD_SUCCESS, warn = 0, error = 0, success = 0;
 145         char *channel_name;
 146         struct lttng_domain dom;
 147
 148         memset(&dom, 0, sizeof(dom));
 149
 150         /* Validate options. */
 151         if (opt_kernel) {
 152                 if (opt_blocking_timeout.set) {
 153                         ERR("Retry timeout option not supported for kernel domain (-k)");
 154                         ret = CMD_ERROR;
 155                         goto error;
 156                 }
 157         }
 158
 159         /* Create lttng domain */
 160         if (opt_kernel) {
 161                 dom.type = LTTNG_DOMAIN_KERNEL;
 162                 dom.buf_type = LTTNG_BUFFER_GLOBAL;
 163                 if (opt_buffer_uid || opt_buffer_pid) {
 164                         ERR("Buffer type not supported for domain -k");
 165                         ret = CMD_ERROR;
 166                         goto error;
 167                 }
 168         } else if (opt_userspace) {
 169                 dom.type = LTTNG_DOMAIN_UST;
 170                 if (opt_buffer_pid) {
 171                         dom.buf_type = LTTNG_BUFFER_PER_PID;
 172                 } else {
 173                         if (opt_buffer_global) {
 174                                 ERR("Buffer type not supported for domain -u");
 175                                 ret = CMD_ERROR;
 176                                 goto error;
 177                         }
 178                         dom.buf_type = LTTNG_BUFFER_PER_UID;
 179                 }
 180         } else {
 181                 /* Checked by the caller. */
 182                 abort();
 183         }
 184
 185         set_default_attr(&dom);
 186
 187         if (chan_opts.attr.tracefile_size == 0 && chan_opts.attr.tracefile_count) {
 188                 ERR("Missing option --tracefile-size. "
 189                     "A file count without a size won't do anything.");
 190                 ret = CMD_ERROR;
 191                 goto error;
 192         }
 193
 194         if ((chan_opts.attr.tracefile_size > 0) &&
 195             (chan_opts.attr.tracefile_size < chan_opts.attr.subbuf_size)) {
 196                 WARN("Tracefile size rounded up from (%" PRIu64 ") to subbuffer size (%" PRIu64 ")",
 197                      chan_opts.attr.tracefile_size,
 198                      chan_opts.attr.subbuf_size);
 199                 chan_opts.attr.tracefile_size = chan_opts.attr.subbuf_size;
 200         }
 201
 202         /* Setting channel output */
 203         if (opt_output) {
 204                 if (!strncmp(output_mmap, opt_output, strlen(output_mmap))) {
 205                         chan_opts.attr.output = LTTNG_EVENT_MMAP;
 206                 } else if (!strncmp(output_splice, opt_output, strlen(output_splice))) {
 207                         chan_opts.attr.output = LTTNG_EVENT_SPLICE;
 208                 } else {
 209                         ERR("Unknown output type %s. Possible values are: %s, %s\n",
 210                             opt_output,
 211                             output_mmap,
 212                             output_splice);
 213                         ret = CMD_ERROR;
 214                         goto error;
 215                 }
 216         }
 217
 218         handle = lttng_create_handle(session_name, &dom);
 219         if (handle == nullptr) {
 220                 ret = -1;
 221                 goto error;
 222         }
 223
 224         /* Mi open channels element */
 225         if (lttng_opt_mi) {
 226                 LTTNG_ASSERT(writer);
 227                 ret = mi_lttng_channels_open(writer);
 228                 if (ret) {
 229                         ret = CMD_ERROR;
 230                         goto error;
 231                 }
 232         }
 233
 234         /* Strip channel list (format: chan1,chan2,...) */
 235         channel_name = strtok(channel_list, ",");
 236         while (channel_name != nullptr) {
 237                 void *extended_ptr;
 238
 239                 /* Validate channel name's length */
 240                 if (strlen(channel_name) >= sizeof(chan_opts.name)) {
 241                         ERR("Channel name is too long (max. %zu characters)",
 242                             sizeof(chan_opts.name) - 1);
 243                         error = 1;
 244                         goto skip_enable;
 245                 }
 246
 247                 /*
 248                  * A dynamically-allocated channel is used in order to allow
 249                  * the configuration of extended attributes (post-2.9).
 250                  */
 251                 channel = lttng_channel_create(&dom);
 252                 if (!channel) {
 253                         ERR("Unable to create channel object");
 254                         error = 1;
 255                         goto error;
 256                 }
 257
 258                 /* Copy channel name */
 259                 strcpy(channel->name, channel_name);
 260                 channel->enabled = 1;
 261                 extended_ptr = channel->attr.extended.ptr;
 262                 memcpy(&channel->attr, &chan_opts.attr, sizeof(chan_opts.attr));
 263                 channel->attr.extended.ptr = extended_ptr;
 264                 if (opt_monitor_timer.set) {
 265                         ret = lttng_channel_set_monitor_timer_interval(channel,
 266                                                                        opt_monitor_timer.interval);
 267                         if (ret) {
 268                                 ERR("Failed to set the channel's monitor timer interval");
 269                                 error = 1;
 270                                 goto error;
 271                         }
 272                 }
 273                 if (opt_blocking_timeout.set) {
 274                         ret = lttng_channel_set_blocking_timeout(channel,
 275                                                                  opt_blocking_timeout.value);
 276                         if (ret) {
 277                                 ERR("Failed to set the channel's blocking timeout");
 278                                 error = 1;
 279                                 goto error;
 280                         }
 281                 }
 282
 283                 DBG("Enabling channel %s", channel_name);
 284
 285                 ret = lttng_enable_channel(handle, channel);
 286                 if (ret < 0) {
 287                         bool msg_already_printed = false;
 288
 289                         success = 0;
 290                         switch (-ret) {
 291                         case LTTNG_ERR_KERN_CHAN_EXIST:
 292                         case LTTNG_ERR_UST_CHAN_EXIST:
 293                         case LTTNG_ERR_CHAN_EXIST:
 294                                 warn = 1;
 295                                 break;
 296                         case LTTNG_ERR_INVALID_CHANNEL_NAME:
 297                                 ERR("Invalid channel name: \"%s\". "
 298                                     "Channel names may not start with '.', and "
 299                                     "may not contain '/'.",
 300                                     channel_name);
 301                                 msg_already_printed = true;
 302                                 error = 1;
 303                                 break;
 304                         default:
 305                                 error = 1;
 306                                 break;
 307                         }
 308
 309                         if (!msg_already_printed) {
 310                                 LOG(error ? PRINT_ERR : PRINT_WARN,
 311                                     "Failed to enable channel `%s` under session `%s`: %s",
 312                                     channel_name,
 313                                     session_name,
 314                                     lttng_strerror(ret));
 315                         }
 316
 317                         if (opt_kernel) {
 318                                 print_kernel_tracer_status_error();
 319                         }
 320                 } else {
 321                         MSG("%s channel `%s` enabled for session `%s`",
 322                             lttng_domain_type_str(dom.type),
 323                             channel_name,
 324                             session_name);
 325                         success = 1;
 326                 }
 327
 328         skip_enable:
 329                 if (lttng_opt_mi) {
 330                         /* Mi print the channel element and leave it open */
 331                         ret = mi_lttng_channel(writer, channel, 1);
 332                         if (ret) {
 333                                 ret = CMD_ERROR;
 334                                 goto error;
 335                         }
 336
 337                         /* Individual Success ? */
 338                         ret = mi_lttng_writer_write_element_bool(
 339                                 writer, mi_lttng_element_command_success, success);
 340                         if (ret) {
 341                                 ret = CMD_ERROR;
 342                                 goto error;
 343                         }
 344
 345                         /* Close channel element */
 346                         ret = mi_lttng_writer_close_element(writer);
 347                         if (ret) {
 348                                 ret = CMD_ERROR;
 349                                 goto error;
 350                         }
 351                 }
 352
 353                 /* Next channel */
 354                 channel_name = strtok(nullptr, ",");
 355                 lttng_channel_destroy(channel);
 356                 channel = nullptr;
 357         }
 358
 359         if (lttng_opt_mi) {
 360                 /* Close channels element */
 361                 ret = mi_lttng_writer_close_element(writer);
 362                 if (ret) {
 363                         ret = CMD_ERROR;
 364                         goto error;
 365                 }
 366         }
 367
 368         ret = CMD_SUCCESS;
 369
 370 error:
 371         if (channel) {
 372                 lttng_channel_destroy(channel);
 373         }
 374         /* If more important error happen bypass the warning */
 375         if (!ret && warn) {
 376                 ret = CMD_WARNING;
 377         }
 378         /* If more important error happen bypass the warning */
 379         if (!ret && error) {
 380                 ret = CMD_ERROR;
 381         }
 382
 383         lttng_destroy_handle(handle);
 384
 385         return ret;
 386 }
 387
 388 /*
 389  * Default value for channel configuration.
 390  */
 391 static void init_channel_config()
 392 {
 393         /*
 394          * Put -1 everywhere so we can identify those set by the command line and
 395          * those needed to be set by the default values.
 396          */
 397         memset(&chan_opts.attr, -1, sizeof(chan_opts.attr));
 398         chan_opts.attr.extended.ptr = nullptr;
 399 }
 400
 401 /*
 402  * Add channel to trace session
 403  */
 404 int cmd_enable_channels(int argc, const char **argv)
 405 {
 406         int opt, ret = CMD_SUCCESS, command_ret = CMD_SUCCESS, success = 1;
 407         static poptContext pc;
 408         char *session_name = nullptr;
 409         char *channel_list = nullptr;
 410         char *opt_arg = nullptr;
 411         const char *arg_channel_list = nullptr;
 412         const char *leftover = nullptr;
 413
 414         init_channel_config();
 415
 416         pc = poptGetContext(nullptr, argc, argv, long_options, 0);
 417         poptReadDefaultConfig(pc, 0);
 418
 419         while ((opt = poptGetNextOpt(pc)) != -1) {
 420                 switch (opt) {
 421                 case OPT_HELP:
 422                         SHOW_HELP();
 423                         goto end;
 424                 case OPT_DISCARD:
 425                         chan_opts.attr.overwrite = 0;
 426                         DBG("Channel set to discard");
 427                         break;
 428                 case OPT_OVERWRITE:
 429                         chan_opts.attr.overwrite = 1;
 430                         DBG("Channel set to overwrite");
 431                         break;
 432                 case OPT_SUBBUF_SIZE:
 433                 {
 434                         uint64_t rounded_size;
 435                         int order;
 436
 437                         /* Parse the size */
 438                         opt_arg = poptGetOptArg(pc);
 439                         if (utils_parse_size_suffix(opt_arg, &chan_opts.attr.subbuf_size) < 0 ||
 440                             !chan_opts.attr.subbuf_size) {
 441                                 ERR("Wrong value in --subbuf-size parameter: %s", opt_arg);
 442                                 ret = CMD_ERROR;
 443                                 goto end;
 444                         }
 445
 446                         order = get_count_order_u64(chan_opts.attr.subbuf_size);
 447                         LTTNG_ASSERT(order >= 0);
 448                         rounded_size = 1ULL << order;
 449                         if (rounded_size < chan_opts.attr.subbuf_size) {
 450                                 ERR("The subbuf size (%" PRIu64 ") is rounded and overflows!",
 451                                     chan_opts.attr.subbuf_size);
 452                                 ret = CMD_ERROR;
 453                                 goto end;
 454                         }
 455
 456                         if (rounded_size != chan_opts.attr.subbuf_size) {
 457                                 WARN("The subbuf size (%" PRIu64
 458                                      ") is rounded to the next power of 2 (%" PRIu64 ")",
 459                                      chan_opts.attr.subbuf_size,
 460                                      rounded_size);
 461                                 chan_opts.attr.subbuf_size = rounded_size;
 462                         }
 463
 464                         /* Should now be power of 2 */
 465                         LTTNG_ASSERT(
 466                                 !((chan_opts.attr.subbuf_size - 1) & chan_opts.attr.subbuf_size));
 467
 468                         DBG("Channel subbuf size set to %" PRIu64, chan_opts.attr.subbuf_size);
 469                         break;
 470                 }
 471                 case OPT_NUM_SUBBUF:
 472                 {
 473                         uint64_t rounded_size;
 474                         int order;
 475
 476                         errno = 0;
 477                         opt_arg = poptGetOptArg(pc);
 478                         chan_opts.attr.num_subbuf = strtoull(opt_arg, nullptr, 0);
 479                         if (errno != 0 || !chan_opts.attr.num_subbuf || !isdigit(opt_arg[0])) {
 480                                 ERR("Wrong value in --num-subbuf parameter: %s", opt_arg);
 481                                 ret = CMD_ERROR;
 482                                 goto end;
 483                         }
 484
 485                         order = get_count_order_u64(chan_opts.attr.num_subbuf);
 486                         LTTNG_ASSERT(order >= 0);
 487                         rounded_size = 1ULL << order;
 488                         if (rounded_size < chan_opts.attr.num_subbuf) {
 489                                 ERR("The number of subbuffers (%" PRIu64
 490                                     ") is rounded and overflows!",
 491                                     chan_opts.attr.num_subbuf);
 492                                 ret = CMD_ERROR;
 493                                 goto end;
 494                         }
 495
 496                         if (rounded_size != chan_opts.attr.num_subbuf) {
 497                                 WARN("The number of subbuffers (%" PRIu64
 498                                      ") is rounded to the next power of 2 (%" PRIu64 ")",
 499                                      chan_opts.attr.num_subbuf,
 500                                      rounded_size);
 501                                 chan_opts.attr.num_subbuf = rounded_size;
 502                         }
 503
 504                         /* Should now be power of 2 */
 505                         LTTNG_ASSERT(
 506                                 !((chan_opts.attr.num_subbuf - 1) & chan_opts.attr.num_subbuf));
 507
 508                         DBG("Channel subbuf num set to %" PRIu64, chan_opts.attr.num_subbuf);
 509                         break;
 510                 }
 511                 case OPT_SWITCH_TIMER:
 512                 {
 513                         uint64_t v;
 514
 515                         errno = 0;
 516                         opt_arg = poptGetOptArg(pc);
 517
 518                         if (utils_parse_time_suffix(opt_arg, &v) < 0) {
 519                                 ERR("Wrong value for --switch-timer parameter: %s", opt_arg);
 520                                 ret = CMD_ERROR;
 521                                 goto end;
 522                         }
 523
 524                         if (v != (uint32_t) v) {
 525                                 ERR("32-bit overflow in --switch-timer parameter: %s", opt_arg);
 526                                 ret = CMD_ERROR;
 527                                 goto end;
 528                         }
 529                         chan_opts.attr.switch_timer_interval = (uint32_t) v;
 530                         DBG("Channel switch timer interval set to %d %s",
 531                             chan_opts.attr.switch_timer_interval,
 532                             USEC_UNIT);
 533                         break;
 534                 }
 535                 case OPT_READ_TIMER:
 536                 {
 537                         uint64_t v;
 538
 539                         errno = 0;
 540                         opt_arg = poptGetOptArg(pc);
 541
 542                         if (utils_parse_time_suffix(opt_arg, &v) < 0) {
 543                                 ERR("Wrong value for --read-timer parameter: %s", opt_arg);
 544                                 ret = CMD_ERROR;
 545                                 goto end;
 546                         }
 547
 548                         if (v != (uint32_t) v) {
 549                                 ERR("32-bit overflow in --read-timer parameter: %s", opt_arg);
 550                                 ret = CMD_ERROR;
 551                                 goto end;
 552                         }
 553                         chan_opts.attr.read_timer_interval = (uint32_t) v;
 554                         DBG("Channel read timer interval set to %d %s",
 555                             chan_opts.attr.read_timer_interval,
 556                             USEC_UNIT);
 557                         break;
 558                 }
 559                 case OPT_MONITOR_TIMER:
 560                 {
 561                         uint64_t v;
 562
 563                         errno = 0;
 564                         opt_arg = poptGetOptArg(pc);
 565
 566                         if (utils_parse_time_suffix(opt_arg, &v) < 0) {
 567                                 ERR("Wrong value for --monitor-timer parameter: %s", opt_arg);
 568                                 ret = CMD_ERROR;
 569                                 goto end;
 570                         }
 571                         opt_monitor_timer.interval = (uint64_t) v;
 572                         opt_monitor_timer.set = true;
 573                         DBG("Channel monitor timer interval set to %" PRIu64 " %s",
 574                             opt_monitor_timer.interval,
 575                             USEC_UNIT);
 576                         break;
 577                 }
 578                 case OPT_BLOCKING_TIMEOUT:
 579                 {
 580                         uint64_t v;
 581                         long long v_msec;
 582
 583                         errno = 0;
 584                         opt_arg = poptGetOptArg(pc);
 585
 586                         if (strcmp(opt_arg, "inf") == 0) {
 587                                 opt_blocking_timeout.value = (int64_t) -1;
 588                                 opt_blocking_timeout.set = true;
 589                                 DBG("Channel blocking timeout set to infinity");
 590                                 break;
 591                         }
 592
 593                         if (utils_parse_time_suffix(opt_arg, &v) < 0) {
 594                                 ERR("Wrong value for --blocking-timeout parameter: %s", opt_arg);
 595                                 ret = CMD_ERROR;
 596                                 goto end;
 597                         }
 598
 599                         /*
 600                          * While LTTng-UST and LTTng-tools will accept a
 601                          * blocking timeout expressed in µs, the current
 602                          * tracer implementation relies on poll() which
 603                          * takes an "int timeout" parameter expressed in
 604                          * msec.
 605                          *
 606                          * Since the error reporting from the tracer is
 607                          * not precise, we perform this check here to
 608                          * provide a helpful error message in case of
 609                          * overflow.
 610                          *
 611                          * The setter (liblttng-ctl) also performs an
 612                          * equivalent check.
 613                          */
 614                         v_msec = v / 1000;
 615                         if (v_msec != (int32_t) v_msec) {
 616                                 ERR("32-bit milliseconds overflow in --blocking-timeout parameter: %s",
 617                                     opt_arg);
 618                                 ret = CMD_ERROR;
 619                                 goto end;
 620                         }
 621
 622                         opt_blocking_timeout.value = (int64_t) v;
 623                         opt_blocking_timeout.set = true;
 624                         DBG("Channel blocking timeout set to %" PRId64 " %s%s",
 625                             opt_blocking_timeout.value,
 626                             USEC_UNIT,
 627                             opt_blocking_timeout.value == 0 ? " (non-blocking)" : "");
 628                         break;
 629                 }
 630                 case OPT_USERSPACE:
 631                         opt_userspace = 1;
 632                         break;
 633                 case OPT_TRACEFILE_SIZE:
 634                         opt_arg = poptGetOptArg(pc);
 635                         if (utils_parse_size_suffix(opt_arg, &chan_opts.attr.tracefile_size) < 0) {
 636                                 ERR("Wrong value in --tracefile-size parameter: %s", opt_arg);
 637                                 ret = CMD_ERROR;
 638                                 goto end;
 639                         }
 640                         DBG("Maximum tracefile size set to %" PRIu64,
 641                             chan_opts.attr.tracefile_size);
 642                         break;
 643                 case OPT_TRACEFILE_COUNT:
 644                 {
 645                         unsigned long v;
 646
 647                         errno = 0;
 648                         opt_arg = poptGetOptArg(pc);
 649                         v = strtoul(opt_arg, nullptr, 0);
 650                         if (errno != 0 || !isdigit(opt_arg[0])) {
 651                                 ERR("Wrong value in --tracefile-count parameter: %s", opt_arg);
 652                                 ret = CMD_ERROR;
 653                                 goto end;
 654                         }
 655                         if (v != (uint32_t) v) {
 656                                 ERR("32-bit overflow in --tracefile-count parameter: %s", opt_arg);
 657                                 ret = CMD_ERROR;
 658                                 goto end;
 659                         }
 660                         chan_opts.attr.tracefile_count = (uint32_t) v;
 661                         DBG("Maximum tracefile count set to %" PRIu64,
 662                             chan_opts.attr.tracefile_count);
 663                         break;
 664                 }
 665                 case OPT_LIST_OPTIONS:
 666                         list_cmd_options(stdout, long_options);
 667                         goto end;
 668                 default:
 669                         ret = CMD_UNDEFINED;
 670                         goto end;
 671                 }
 672
 673                 if (opt_arg) {
 674                         free(opt_arg);
 675                         opt_arg = nullptr;
 676                 }
 677         }
 678
 679         ret = print_missing_or_multiple_domains(opt_kernel + opt_userspace, false);
 680         if (ret) {
 681                 ret = CMD_ERROR;
 682                 goto end;
 683         }
 684
 685         if (chan_opts.attr.overwrite == 1 && opt_blocking_timeout.set &&
 686             opt_blocking_timeout.value != 0) {
 687                 ERR("You cannot specify --overwrite and --blocking-timeout=N, "
 688                     "where N is different than 0");
 689                 ret = CMD_ERROR;
 690                 goto end;
 691         }
 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_enable_channels);
 704                 if (ret) {
 705                         ret = CMD_ERROR;
 706                         goto end;
 707                 }
 708
 709                 /* Open output element */
 710                 ret = mi_lttng_writer_open_element(writer, mi_lttng_element_command_output);
 711                 if (ret) {
 712                         ret = CMD_ERROR;
 713                         goto end;
 714                 }
 715         }
 716
 717         arg_channel_list = poptGetArg(pc);
 718         if (arg_channel_list == nullptr) {
 719                 ERR("Missing channel name.");
 720                 ret = CMD_ERROR;
 721                 success = 0;
 722                 goto mi_closing;
 723         }
 724
 725         channel_list = strdup(arg_channel_list);
 726         if (channel_list == nullptr) {
 727                 PERROR("Failed to copy channel name");
 728                 ret = CMD_ERROR;
 729                 success = 0;
 730                 goto mi_closing;
 731         }
 732
 733         leftover = poptGetArg(pc);
 734         if (leftover) {
 735                 ERR("Unknown argument: %s", leftover);
 736                 ret = CMD_ERROR;
 737                 success = 0;
 738                 goto mi_closing;
 739         }
 740
 741         if (!opt_session_name) {
 742                 session_name = get_session_name();
 743                 if (session_name == nullptr) {
 744                         command_ret = CMD_ERROR;
 745                         success = 0;
 746                         goto mi_closing;
 747                 }
 748         } else {
 749                 session_name = opt_session_name;
 750         }
 751
 752         command_ret = enable_channel(session_name, channel_list);
 753         if (command_ret) {
 754                 success = 0;
 755         }
 756
 757 mi_closing:
 758         /* Mi closing */
 759         if (lttng_opt_mi) {
 760                 /* Close  output element */
 761                 ret = mi_lttng_writer_close_element(writer);
 762                 if (ret) {
 763                         goto end;
 764                 }
 765
 766                 /* Success ? */
 767                 ret = mi_lttng_writer_write_element_bool(
 768                         writer, mi_lttng_element_command_success, success);
 769                 if (ret) {
 770                         goto end;
 771                 }
 772
 773                 /* Command element close */
 774                 ret = mi_lttng_writer_command_close(writer);
 775                 if (ret) {
 776                         goto end;
 777                 }
 778         }
 779
 780 end:
 781         /* Mi clean-up */
 782         if (writer && mi_lttng_writer_destroy(writer)) {
 783                 /* Preserve original error code */
 784                 ret = ret ? ret : LTTNG_ERR_MI_IO_FAIL;
 785         }
 786
 787         if (!opt_session_name && session_name) {
 788                 free(session_name);
 789         }
 790
 791         free(channel_list);
 792
 793         /* Overwrite ret if an error occurred when enable_channel */
 794         ret = command_ret ? command_ret : ret;
 795         poptFreeContext(pc);
 796         free(opt_arg);
 797         return ret;
 798 }