src/common/trace-chunk.c

   1 /*
   2  * Copyright (C) 2019 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
   3  *
   4  * This library is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU Lesser General Public License, version 2.1 only,
   6  * as published by the Free Software Foundation.
   7  *
   8  * This library 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 Lesser General Public License
  11  * for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public License
  14  * along with this library; if not, write to the Free Software Foundation,
  15  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  16  */
  17
  18 #include <lttng/constant.h>
  19 #include <common/string-utils/format.h>
  20 #include <common/trace-chunk.h>
  21 #include <common/trace-chunk-registry.h>
  22 #include <common/hashtable/utils.h>
  23 #include <common/hashtable/hashtable.h>
  24 #include <common/error.h>
  25 #include <common/utils.h>
  26 #include <common/time.h>
  27 #include <common/optional.h>
  28 #include <common/compat/directory-handle.h>
  29 #include <common/credentials.h>
  30 #include <common/defaults.h>
  31 #include <common/dynamic-array.h>
  32
  33 #include <urcu/ref.h>
  34 #include <urcu/rculfhash.h>
  35 #include <sys/stat.h>
  36 #include <inttypes.h>
  37 #include <pthread.h>
  38 #include <stdio.h>
  39
  40 /*
  41  * Two ISO 8601-compatible timestamps, separated by a hypen, followed an
  42  * index, i.e. <start-iso-8601>-<end-iso-8601>-<id-uint64_t>.
  43  */
  44 #define GENERATED_CHUNK_NAME_LEN (2 * sizeof("YYYYmmddTHHMMSS+HHMM") + MAX_INT_DEC_LEN(uint64_t))
  45 #define DIR_CREATION_MODE (S_IRWXU | S_IRWXG)
  46
  47 enum trace_chunk_mode {
  48         TRACE_CHUNK_MODE_USER,
  49         TRACE_CHUNK_MODE_OWNER,
  50 };
  51
  52 /*
  53  * Callback to invoke on release of a trace chunk. Note that there is no
  54  * need to 'lock' the trace chunk during the execution of these callbacks
  55  * since only one thread may access a chunk during its destruction (the last
  56  * to release its reference to the chunk).
  57  */
  58 typedef void (*chunk_close_command)(struct lttng_trace_chunk *trace_chunk);
  59
  60 /* Move a completed trace chunk to the 'completed' trace archive folder. */
  61 static
  62 void lttng_trace_chunk_move_to_completed(struct lttng_trace_chunk *trace_chunk);
  63
  64 struct chunk_credentials {
  65         bool use_current_user;
  66         struct lttng_credentials user;
  67 };
  68
  69 struct lttng_trace_chunk {
  70         pthread_mutex_t lock;
  71         struct urcu_ref ref;
  72         LTTNG_OPTIONAL(enum trace_chunk_mode) mode;
  73         /*
  74          * First-level directories created within the trace chunk.
  75          * Elements are of type 'char *'.
  76          */
  77         struct lttng_dynamic_pointer_array top_level_directories;
  78         /* Is contained within an lttng_trace_chunk_registry_element? */
  79         bool in_registry_element;
  80         bool name_overriden;
  81         char *name;
  82         /* An unset id means the chunk is anonymous. */
  83         LTTNG_OPTIONAL(uint64_t) id;
  84         LTTNG_OPTIONAL(time_t) timestamp_creation;
  85         LTTNG_OPTIONAL(time_t) timestamp_close;
  86         LTTNG_OPTIONAL(struct chunk_credentials) credentials;
  87         LTTNG_OPTIONAL(struct lttng_directory_handle) session_output_directory;
  88         LTTNG_OPTIONAL(struct lttng_directory_handle) chunk_directory;
  89         LTTNG_OPTIONAL(enum lttng_trace_chunk_command_type) close_command;
  90 };
  91
  92 /* A trace chunk is uniquely identified by its (session id, chunk id) tuple. */
  93 struct lttng_trace_chunk_registry_element {
  94         uint64_t session_id;
  95         struct lttng_trace_chunk chunk;
  96         /* Weak and only set when added. */
  97         struct lttng_trace_chunk_registry *registry;
  98         struct cds_lfht_node trace_chunk_registry_ht_node;
  99         /* call_rcu delayed reclaim. */
 100         struct rcu_head rcu_node;
 101 };
 102
 103 struct lttng_trace_chunk_registry {
 104         struct cds_lfht *ht;
 105 };
 106
 107 const char *close_command_names[] = {
 108         [LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED] =
 109                 "move to completed chunk folder",
 110 };
 111
 112 chunk_close_command close_command_funcs[] = {
 113         [LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED] =
 114                         lttng_trace_chunk_move_to_completed,
 115 };
 116
 117 static
 118 bool lttng_trace_chunk_registry_element_equals(
 119                 const struct lttng_trace_chunk_registry_element *a,
 120                 const struct lttng_trace_chunk_registry_element *b)
 121 {
 122         if (a->session_id != b->session_id) {
 123                 goto not_equal;
 124         }
 125         if (a->chunk.id.is_set != b->chunk.id.is_set) {
 126                 goto not_equal;
 127         }
 128         if (a->chunk.id.is_set && a->chunk.id.value != b->chunk.id.value) {
 129                 goto not_equal;
 130         }
 131         return true;
 132 not_equal:
 133         return false;
 134 }
 135
 136 static
 137 int lttng_trace_chunk_registry_element_match(struct cds_lfht_node *node,
 138                 const void *key)
 139 {
 140         const struct lttng_trace_chunk_registry_element *element_a, *element_b;
 141
 142         element_a = (const struct lttng_trace_chunk_registry_element *) key;
 143         element_b = caa_container_of(node, typeof(*element_b),
 144                         trace_chunk_registry_ht_node);
 145         return lttng_trace_chunk_registry_element_equals(element_a, element_b);
 146 }
 147
 148 static
 149 unsigned long lttng_trace_chunk_registry_element_hash(
 150                 const struct lttng_trace_chunk_registry_element *element)
 151 {
 152         unsigned long hash = hash_key_u64(&element->session_id,
 153                         lttng_ht_seed);
 154
 155         if (element->chunk.id.is_set) {
 156                 hash ^= hash_key_u64(&element->chunk.id.value, lttng_ht_seed);
 157         }
 158
 159         return hash;
 160 }
 161
 162 static
 163 char *generate_chunk_name(uint64_t chunk_id, time_t creation_timestamp,
 164                 const time_t *close_timestamp)
 165 {
 166         int ret = 0;
 167         char *new_name= NULL;
 168         char start_datetime[sizeof("YYYYmmddTHHMMSS+HHMM")] = {};
 169         char end_datetime_suffix[sizeof("-YYYYmmddTHHMMSS+HHMM")] = {};
 170
 171         ret = time_to_iso8601_str(
 172                         creation_timestamp,
 173                         start_datetime, sizeof(start_datetime));
 174         if (ret) {
 175                 ERR("Failed to format trace chunk start date time");
 176                 goto error;
 177         }
 178         if (close_timestamp) {
 179                 *end_datetime_suffix = '-';
 180                 ret = time_to_iso8601_str(
 181                                 *close_timestamp,
 182                                 end_datetime_suffix + 1,
 183                                 sizeof(end_datetime_suffix));
 184                 if (ret) {
 185                         ERR("Failed to format trace chunk end date time");
 186                         goto error;
 187                 }
 188         }
 189         new_name = zmalloc(GENERATED_CHUNK_NAME_LEN);
 190         if (!new_name) {
 191                 ERR("Failed to allocate buffer for automatically-generated trace chunk name");
 192                 goto error;
 193         }
 194         ret = snprintf(new_name, GENERATED_CHUNK_NAME_LEN, "%s%s-%" PRIu64,
 195                         start_datetime, end_datetime_suffix, chunk_id);
 196         if (ret >= GENERATED_CHUNK_NAME_LEN || ret == -1) {
 197                 ERR("Failed to format trace chunk name");
 198                 goto error;
 199         }
 200
 201         return new_name;
 202 error:
 203         free(new_name);
 204         return NULL;
 205 }
 206
 207 static
 208 void lttng_trace_chunk_init(struct lttng_trace_chunk *chunk)
 209 {
 210         urcu_ref_init(&chunk->ref);
 211         pthread_mutex_init(&chunk->lock, NULL);
 212         lttng_dynamic_pointer_array_init(&chunk->top_level_directories);
 213 }
 214
 215 static
 216 void lttng_trace_chunk_fini(struct lttng_trace_chunk *chunk)
 217 {
 218         if (chunk->session_output_directory.is_set) {
 219                 lttng_directory_handle_fini(
 220                                 &chunk->session_output_directory.value);
 221         }
 222         if (chunk->chunk_directory.is_set) {
 223                 lttng_directory_handle_fini(&chunk->chunk_directory.value);
 224         }
 225         free(chunk->name);
 226         chunk->name = NULL;
 227         lttng_dynamic_pointer_array_reset(&chunk->top_level_directories, free);
 228         pthread_mutex_destroy(&chunk->lock);
 229 }
 230
 231 static
 232 struct lttng_trace_chunk *lttng_trace_chunk_allocate(void)
 233 {
 234         struct lttng_trace_chunk *chunk = NULL;
 235
 236         chunk = zmalloc(sizeof(*chunk));
 237         if (!chunk) {
 238                 ERR("Failed to allocate trace chunk");
 239                 goto end;
 240         }
 241         lttng_trace_chunk_init(chunk);
 242 end:
 243         return chunk;
 244 }
 245
 246 LTTNG_HIDDEN
 247 struct lttng_trace_chunk *lttng_trace_chunk_create_anonymous(void)
 248 {
 249         DBG("Creating anonymous trace chunk");
 250         return lttng_trace_chunk_allocate();
 251 }
 252
 253 LTTNG_HIDDEN
 254 struct lttng_trace_chunk *lttng_trace_chunk_create(
 255                 uint64_t chunk_id, time_t chunk_creation_time)
 256 {
 257         struct lttng_trace_chunk *chunk;
 258         char chunk_creation_datetime_buf[16] = {};
 259         const char *chunk_creation_datetime_str = "(formatting error)";
 260         struct tm timeinfo_buf, *timeinfo;
 261
 262         timeinfo = localtime_r(&chunk_creation_time, &timeinfo_buf);
 263         if (timeinfo) {
 264                 size_t strftime_ret;
 265
 266                 /* Don't fail because of this; it is only used for logging. */
 267                 strftime_ret = strftime(chunk_creation_datetime_buf,
 268                                 sizeof(chunk_creation_datetime_buf),
 269                                 "%Y%m%d-%H%M%S", timeinfo);
 270                 if (strftime_ret) {
 271                         chunk_creation_datetime_str =
 272                                         chunk_creation_datetime_buf;
 273                 }
 274         }
 275
 276         DBG("Creating trace chunk: chunk_id = %" PRIu64 ", creation time = %s",
 277                         chunk_id, chunk_creation_datetime_str);
 278         chunk = lttng_trace_chunk_allocate();
 279         if (!chunk) {
 280                 goto end;
 281         }
 282
 283         LTTNG_OPTIONAL_SET(&chunk->id, chunk_id);
 284         LTTNG_OPTIONAL_SET(&chunk->timestamp_creation, chunk_creation_time);
 285         if (chunk_id != 0) {
 286                 chunk->name = generate_chunk_name(chunk_id,
 287                                 chunk_creation_time, NULL);
 288                 if (!chunk->name) {
 289                         ERR("Failed to allocate trace chunk name storage");
 290                         goto error;
 291                 }
 292         }
 293
 294         DBG("Chunk name set to \"%s\"", chunk->name ? : "(none)");
 295 end:
 296         return chunk;
 297 error:
 298         lttng_trace_chunk_put(chunk);
 299         return NULL;
 300 }
 301
 302 LTTNG_HIDDEN
 303 enum lttng_trace_chunk_status lttng_trace_chunk_get_id(
 304                 struct lttng_trace_chunk *chunk, uint64_t *id)
 305 {
 306         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 307
 308         pthread_mutex_lock(&chunk->lock);
 309         if (chunk->id.is_set) {
 310                 *id = chunk->id.value;
 311         } else {
 312                 status = LTTNG_TRACE_CHUNK_STATUS_NONE;
 313         }
 314         pthread_mutex_unlock(&chunk->lock);
 315         return status;
 316 }
 317
 318 LTTNG_HIDDEN
 319 enum lttng_trace_chunk_status lttng_trace_chunk_get_creation_timestamp(
 320                 struct lttng_trace_chunk *chunk, time_t *creation_ts)
 321
 322 {
 323         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 324
 325         pthread_mutex_lock(&chunk->lock);
 326         if (chunk->timestamp_creation.is_set) {
 327                 *creation_ts = chunk->timestamp_creation.value;
 328         } else {
 329                 status = LTTNG_TRACE_CHUNK_STATUS_NONE;
 330         }
 331         pthread_mutex_unlock(&chunk->lock);
 332         return status;
 333 }
 334
 335 LTTNG_HIDDEN
 336 enum lttng_trace_chunk_status lttng_trace_chunk_get_close_timestamp(
 337                 struct lttng_trace_chunk *chunk, time_t *close_ts)
 338 {
 339         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 340
 341         pthread_mutex_lock(&chunk->lock);
 342         if (chunk->timestamp_close.is_set) {
 343                 *close_ts = chunk->timestamp_close.value;
 344         } else {
 345                 status = LTTNG_TRACE_CHUNK_STATUS_NONE;
 346         }
 347         pthread_mutex_unlock(&chunk->lock);
 348         return status;
 349 }
 350
 351 LTTNG_HIDDEN
 352 enum lttng_trace_chunk_status lttng_trace_chunk_set_close_timestamp(
 353                 struct lttng_trace_chunk *chunk, time_t close_ts)
 354 {
 355         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 356
 357         pthread_mutex_lock(&chunk->lock);
 358         if (!chunk->timestamp_creation.is_set) {
 359                 ERR("Failed to set trace chunk close timestamp: creation timestamp is unset");
 360                 status = LTTNG_TRACE_CHUNK_STATUS_INVALID_OPERATION;
 361                 goto end;
 362         }
 363         if (chunk->timestamp_creation.value > close_ts) {
 364                 ERR("Failed to set trace chunk close timestamp: close timestamp is before creation timestamp");
 365                 status = LTTNG_TRACE_CHUNK_STATUS_INVALID_ARGUMENT;
 366                 goto end;
 367         }
 368         LTTNG_OPTIONAL_SET(&chunk->timestamp_close, close_ts);
 369         free(chunk->name);
 370         chunk->name = generate_chunk_name(LTTNG_OPTIONAL_GET(chunk->id),
 371                         LTTNG_OPTIONAL_GET(chunk->timestamp_creation),
 372                         &close_ts);
 373         if (!chunk->name) {
 374                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 375         }
 376 end:
 377         pthread_mutex_unlock(&chunk->lock);
 378         return status;
 379 }
 380
 381 LTTNG_HIDDEN
 382 enum lttng_trace_chunk_status lttng_trace_chunk_get_name(
 383                 struct lttng_trace_chunk *chunk, const char **name,
 384                 bool *name_overriden)
 385 {
 386         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 387
 388         pthread_mutex_lock(&chunk->lock);
 389         if (name_overriden) {
 390                 *name_overriden = chunk->name_overriden;
 391         }
 392         if (!chunk->name) {
 393                 status = LTTNG_TRACE_CHUNK_STATUS_NONE;
 394                 goto end;
 395         }
 396         *name = chunk->name;
 397 end:
 398         pthread_mutex_unlock(&chunk->lock);
 399         return status;
 400 }
 401
 402 LTTNG_HIDDEN
 403 enum lttng_trace_chunk_status lttng_trace_chunk_override_name(
 404                 struct lttng_trace_chunk *chunk, const char *name)
 405
 406 {
 407         char *new_name;
 408         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 409
 410         if (!name || !*name || strnlen(name, LTTNG_NAME_MAX) == LTTNG_NAME_MAX) {
 411                 ERR("Attempted to set an invalid name on a trace chunk: name = %s",
 412                                 name ? : "NULL");
 413                 status = LTTNG_TRACE_CHUNK_STATUS_INVALID_ARGUMENT;
 414                 goto end;
 415         }
 416
 417         pthread_mutex_lock(&chunk->lock);
 418         if (!chunk->id.is_set) {
 419                 ERR("Attempted to set an override name on an anonymous trace chunk: name = %s",
 420                                 name);
 421                 status = LTTNG_TRACE_CHUNK_STATUS_INVALID_OPERATION;
 422                 goto end_unlock;
 423         }
 424         new_name = strdup(name);
 425         if (!new_name) {
 426                 ERR("Failed to allocate new trace chunk name");
 427                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 428                 goto end_unlock;
 429         }
 430         free(chunk->name);
 431         chunk->name = new_name;
 432         chunk->name_overriden = true;
 433 end_unlock:
 434         pthread_mutex_unlock(&chunk->lock);
 435 end:
 436         return status;
 437 }
 438
 439 LTTNG_HIDDEN
 440 enum lttng_trace_chunk_status lttng_trace_chunk_get_credentials(
 441                 struct lttng_trace_chunk *chunk,
 442                 struct lttng_credentials *credentials)
 443 {
 444         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 445
 446         pthread_mutex_lock(&chunk->lock);
 447         if (chunk->credentials.is_set) {
 448                 if (chunk->credentials.value.use_current_user) {
 449                         credentials->uid = geteuid();
 450                         credentials->gid = getegid();
 451                 } else {
 452                         *credentials = chunk->credentials.value.user;
 453                 }
 454         } else {
 455                 status = LTTNG_TRACE_CHUNK_STATUS_NONE;
 456         }
 457         pthread_mutex_unlock(&chunk->lock);
 458         return status;
 459 }
 460
 461 LTTNG_HIDDEN
 462 enum lttng_trace_chunk_status lttng_trace_chunk_set_credentials(
 463                 struct lttng_trace_chunk *chunk,
 464                 const struct lttng_credentials *user_credentials)
 465 {
 466         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 467         const struct chunk_credentials credentials = {
 468                 .user = *user_credentials,
 469                 .use_current_user = false,
 470         };
 471
 472         pthread_mutex_lock(&chunk->lock);
 473         if (chunk->credentials.is_set) {
 474                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 475                 goto end;
 476         }
 477         LTTNG_OPTIONAL_SET(&chunk->credentials, credentials);
 478 end:
 479         pthread_mutex_unlock(&chunk->lock);
 480         return status;
 481 }
 482
 483 LTTNG_HIDDEN
 484 enum lttng_trace_chunk_status lttng_trace_chunk_set_credentials_current_user(
 485                 struct lttng_trace_chunk *chunk)
 486 {
 487         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 488         const struct chunk_credentials credentials = {
 489                 .use_current_user = true,
 490         };
 491
 492         pthread_mutex_lock(&chunk->lock);
 493         if (chunk->credentials.is_set) {
 494                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 495                 goto end;
 496         }
 497         LTTNG_OPTIONAL_SET(&chunk->credentials, credentials);
 498 end:
 499         pthread_mutex_unlock(&chunk->lock);
 500         return status;
 501 }
 502
 503
 504 LTTNG_HIDDEN
 505 enum lttng_trace_chunk_status lttng_trace_chunk_set_as_owner(
 506                 struct lttng_trace_chunk *chunk,
 507                 struct lttng_directory_handle *session_output_directory)
 508 {
 509         int ret;
 510         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 511         struct lttng_directory_handle chunk_directory_handle;
 512
 513         pthread_mutex_lock(&chunk->lock);
 514         if (chunk->mode.is_set) {
 515                 status = LTTNG_TRACE_CHUNK_STATUS_INVALID_OPERATION;
 516                 goto end;
 517         }
 518         if (!chunk->credentials.is_set) {
 519                 /*
 520                  * Fatal error, credentials must be set before a
 521                  * directory is created.
 522                  */
 523                 ERR("Credentials of trace chunk are unset: refusing to set session output directory");
 524                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 525                 goto end;
 526         }
 527
 528         if (chunk->name) {
 529                 /*
 530                  * A nameless chunk does not need its own output directory.
 531                  * The session's output directory will be used.
 532                  */
 533                 ret = lttng_directory_handle_create_subdirectory_as_user(
 534                                 session_output_directory,
 535                                 chunk->name,
 536                                 DIR_CREATION_MODE,
 537                                 !chunk->credentials.value.use_current_user ?
 538                                         &chunk->credentials.value.user : NULL);
 539                 if (ret) {
 540                         PERROR("Failed to create chunk output directory \"%s\"",
 541                                 chunk->name);
 542                         status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 543                         goto end;
 544                 }
 545         }
 546         ret = lttng_directory_handle_init_from_handle(&chunk_directory_handle,
 547                         chunk->name,
 548                         session_output_directory);
 549         if (ret) {
 550                 /* The function already logs on all error paths. */
 551                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 552                 goto end;
 553         }
 554         LTTNG_OPTIONAL_SET(&chunk->session_output_directory,
 555                         lttng_directory_handle_move(session_output_directory));
 556         LTTNG_OPTIONAL_SET(&chunk->chunk_directory,
 557                         lttng_directory_handle_move(&chunk_directory_handle));
 558         LTTNG_OPTIONAL_SET(&chunk->mode, TRACE_CHUNK_MODE_OWNER);
 559 end:
 560         pthread_mutex_unlock(&chunk->lock);
 561         return status;
 562 }
 563
 564 LTTNG_HIDDEN
 565 enum lttng_trace_chunk_status lttng_trace_chunk_set_as_user(
 566                 struct lttng_trace_chunk *chunk,
 567                 struct lttng_directory_handle *chunk_directory)
 568 {
 569         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 570
 571         pthread_mutex_lock(&chunk->lock);
 572         if (chunk->mode.is_set) {
 573                 status = LTTNG_TRACE_CHUNK_STATUS_INVALID_OPERATION;
 574                 goto end;
 575         }
 576         if (!chunk->credentials.is_set) {
 577                 ERR("Credentials of trace chunk are unset: refusing to set chunk output directory");
 578                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 579                 goto end;
 580         }
 581         LTTNG_OPTIONAL_SET(&chunk->chunk_directory,
 582                         lttng_directory_handle_move(chunk_directory));
 583         LTTNG_OPTIONAL_SET(&chunk->mode, TRACE_CHUNK_MODE_USER);
 584 end:
 585         pthread_mutex_unlock(&chunk->lock);
 586         return status;
 587 }
 588
 589 LTTNG_HIDDEN
 590 enum lttng_trace_chunk_status lttng_trace_chunk_get_chunk_directory_handle(
 591                 struct lttng_trace_chunk *chunk,
 592                 const struct lttng_directory_handle **handle)
 593 {
 594         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 595
 596         pthread_mutex_lock(&chunk->lock);
 597         if (!chunk->chunk_directory.is_set) {
 598                 status = LTTNG_TRACE_CHUNK_STATUS_NONE;
 599                 goto end;
 600         }
 601
 602         *handle = &chunk->chunk_directory.value;
 603 end:
 604         pthread_mutex_unlock(&chunk->lock);
 605         return status;
 606 }
 607
 608 /* Add a top-level directory to the trace chunk if it was previously unknown. */
 609 static
 610 int add_top_level_directory_unique(struct lttng_trace_chunk *chunk,
 611                 const char *new_path)
 612 {
 613         int ret = 0;
 614         bool found = false;
 615         size_t i, count = lttng_dynamic_pointer_array_get_count(
 616                         &chunk->top_level_directories);
 617         const char *new_path_separator_pos = strchr(new_path, '/');
 618         const ptrdiff_t new_path_top_level_len = new_path_separator_pos ?
 619                         new_path_separator_pos - new_path : strlen(new_path);
 620
 621         for (i = 0; i < count; i++) {
 622                 const char *path = lttng_dynamic_pointer_array_get_pointer(
 623                                 &chunk->top_level_directories, i);
 624                 const ptrdiff_t path_top_level_len = strlen(path);
 625
 626                 if (path_top_level_len != new_path_top_level_len) {
 627                         continue;
 628                 }
 629                 if (!strncmp(path, new_path, path_top_level_len)) {
 630                         found = true;
 631                         break;
 632                 }
 633         }
 634
 635         if (!found) {
 636                 char *copy = strndup(new_path, new_path_top_level_len);
 637
 638                 DBG("Adding new top-level directory \"%s\" to trace chunk \"%s\"",
 639                                 new_path, chunk->name ? : "(unnamed)");
 640                 if (!copy) {
 641                         PERROR("Failed to copy path");
 642                         ret = -1;
 643                         goto end;
 644                 }
 645                 ret = lttng_dynamic_pointer_array_add_pointer(
 646                                 &chunk->top_level_directories, copy);
 647                 if (ret) {
 648                         ERR("Allocation failure while adding top-level directory entry to a trace chunk");
 649                         free(copy);
 650                         goto end;
 651                 }
 652         }
 653 end:
 654         return ret;
 655 }
 656
 657 LTTNG_HIDDEN
 658 enum lttng_trace_chunk_status lttng_trace_chunk_create_subdirectory(
 659                 struct lttng_trace_chunk *chunk,
 660                 const char *path)
 661 {
 662         int ret;
 663         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 664
 665         DBG("Creating trace chunk subdirectory \"%s\"", path);
 666         pthread_mutex_lock(&chunk->lock);
 667         if (!chunk->credentials.is_set) {
 668                 /*
 669                  * Fatal error, credentials must be set before a
 670                  * directory is created.
 671                  */
 672                 ERR("Credentials of trace chunk are unset: refusing to create subdirectory \"%s\"",
 673                                 path);
 674                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 675                 goto end;
 676         }
 677         if (!chunk->mode.is_set ||
 678                         chunk->mode.value != TRACE_CHUNK_MODE_OWNER) {
 679                 ERR("Attempted to create trace chunk subdirectory \"%s\" through a non-owner chunk",
 680                                 path);
 681                 status = LTTNG_TRACE_CHUNK_STATUS_INVALID_OPERATION;
 682                 goto end;
 683         }
 684         if (!chunk->chunk_directory.is_set) {
 685                 ERR("Attempted to create trace chunk subdirectory \"%s\" before setting the chunk output directory",
 686                                 path);
 687                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 688                 goto end;
 689         }
 690         if (*path == '/') {
 691                 ERR("Refusing to create absolute trace chunk directory \"%s\"",
 692                                 path);
 693                 status = LTTNG_TRACE_CHUNK_STATUS_INVALID_ARGUMENT;
 694                 goto end;
 695         }
 696         ret = lttng_directory_handle_create_subdirectory_recursive_as_user(
 697                         &chunk->chunk_directory.value, path,
 698                         DIR_CREATION_MODE,
 699                         chunk->credentials.value.use_current_user ?
 700                                         NULL : &chunk->credentials.value.user);
 701         if (ret) {
 702                 PERROR("Failed to create trace chunk subdirectory \"%s\"",
 703                                 path);
 704                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 705                 goto end;
 706         }
 707         ret = add_top_level_directory_unique(chunk, path);
 708         if (ret) {
 709                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 710                 goto end;
 711         }
 712 end:
 713         pthread_mutex_unlock(&chunk->lock);
 714         return status;
 715 }
 716
 717 LTTNG_HIDDEN
 718 enum lttng_trace_chunk_status lttng_trace_chunk_open_file(
 719                 struct lttng_trace_chunk *chunk, const char *file_path,
 720                 int flags, mode_t mode, int *out_fd)
 721 {
 722         int ret;
 723         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 724
 725         DBG("Opening trace chunk file \"%s\"", file_path);
 726         pthread_mutex_lock(&chunk->lock);
 727         if (!chunk->credentials.is_set) {
 728                 /*
 729                  * Fatal error, credentials must be set before a
 730                  * file is created.
 731                  */
 732                 ERR("Credentials of trace chunk are unset: refusing to open file \"%s\"",
 733                                 file_path);
 734                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 735                 goto end;
 736         }
 737         if (!chunk->chunk_directory.is_set) {
 738                 ERR("Attempted to open trace chunk file \"%s\" before setting the chunk output directory",
 739                                 file_path);
 740                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 741                 goto end;
 742         }
 743         ret = lttng_directory_handle_open_file_as_user(
 744                         &chunk->chunk_directory.value, file_path, flags, mode,
 745                         chunk->credentials.value.use_current_user ?
 746                                         NULL : &chunk->credentials.value.user);
 747         if (ret < 0) {
 748                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 749                 goto end;
 750         }
 751         *out_fd = ret;
 752 end:
 753         pthread_mutex_unlock(&chunk->lock);
 754         return status;
 755 }
 756
 757 LTTNG_HIDDEN
 758 int lttng_trace_chunk_unlink_file(struct lttng_trace_chunk *chunk,
 759                 const char *file_path)
 760 {
 761         int ret;
 762         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 763
 764         DBG("Unlinking trace chunk file \"%s\"", file_path);
 765         pthread_mutex_lock(&chunk->lock);
 766         if (!chunk->credentials.is_set) {
 767                 /*
 768                  * Fatal error, credentials must be set before a
 769                  * directory is created.
 770                  */
 771                 ERR("Credentials of trace chunk are unset: refusing to unlink file \"%s\"",
 772                                 file_path);
 773                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 774                 goto end;
 775         }
 776         if (!chunk->chunk_directory.is_set) {
 777                 ERR("Attempted to unlink trace chunk file \"%s\" before setting the chunk output directory",
 778                                 file_path);
 779                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 780                 goto end;
 781         }
 782         ret = lttng_directory_handle_unlink_file_as_user(
 783                         &chunk->chunk_directory.value, file_path,
 784                         chunk->credentials.value.use_current_user ?
 785                                         NULL : &chunk->credentials.value.user);
 786         if (ret < 0) {
 787                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 788                 goto end;
 789         }
 790 end:
 791         pthread_mutex_unlock(&chunk->lock);
 792         return status;
 793 }
 794
 795 static
 796 void lttng_trace_chunk_move_to_completed(struct lttng_trace_chunk *trace_chunk)
 797 {
 798         int ret;
 799         char *directory_to_rename = NULL;
 800         bool free_directory_to_rename = false;
 801         const int session_dirfd =
 802                         trace_chunk->session_output_directory.value.dirfd;
 803         char *archived_chunk_name = NULL;
 804         const uint64_t chunk_id = LTTNG_OPTIONAL_GET(trace_chunk->id);
 805         const time_t creation_timestamp =
 806                         LTTNG_OPTIONAL_GET(trace_chunk->timestamp_creation);
 807         const time_t close_timestamp =
 808                         LTTNG_OPTIONAL_GET(trace_chunk->timestamp_close);
 809         LTTNG_OPTIONAL(struct lttng_directory_handle) archived_chunks_directory;
 810
 811         assert(trace_chunk->mode.is_set);
 812         assert(trace_chunk->mode.value == TRACE_CHUNK_MODE_OWNER);
 813         assert(!trace_chunk->name_overriden);
 814
 815         /*
 816          * The fist trace chunk of a session is directly output to the
 817          * session's output folder. In this case, the top level directories
 818          * must be moved to a temporary folder before that temporary directory
 819          * is renamed to match the chunk's name.
 820          */
 821         if (chunk_id == 0) {
 822                 struct lttng_directory_handle temporary_rename_directory;
 823                 size_t i, count = lttng_dynamic_pointer_array_get_count(
 824                                 &trace_chunk->top_level_directories);
 825
 826                 ret = lttng_directory_handle_create_subdirectory_as_user(
 827                                 &trace_chunk->session_output_directory.value,
 828                                 DEFAULT_TEMPORARY_CHUNK_RENAME_DIRECTORY,
 829                                 DIR_CREATION_MODE,
 830                                 !trace_chunk->credentials.value.use_current_user ?
 831                                         &trace_chunk->credentials.value.user : NULL);
 832                 if (ret) {
 833                         PERROR("Failed to create temporary trace chunk rename directory \"%s\"",
 834                                         DEFAULT_TEMPORARY_CHUNK_RENAME_DIRECTORY);
 835                 }
 836
 837                 ret = lttng_directory_handle_init_from_handle(&temporary_rename_directory,
 838                                 DEFAULT_TEMPORARY_CHUNK_RENAME_DIRECTORY,
 839                                 &trace_chunk->session_output_directory.value);
 840                 if (ret) {
 841                         ERR("Failed to get handle to temporary trace chunk rename directory");
 842                         goto end;
 843                 }
 844
 845                 for (i = 0; i < count; i++) {
 846                         const int temp_dirfd = temporary_rename_directory.dirfd;
 847                         const char *top_level_name =
 848                                         lttng_dynamic_pointer_array_get_pointer(
 849                                                 &trace_chunk->top_level_directories, i);
 850
 851                         /*
 852                          * FIXME replace renamat() use by directory handle
 853                          * wrapper for non-POSIX 2008 systems.
 854                          */
 855                         ret = renameat(session_dirfd, top_level_name,
 856                                         temp_dirfd, top_level_name);
 857                         if (ret) {
 858                                 PERROR("Failed to move \"%s\" to temporary trace chunk rename directory",
 859                                                 top_level_name);
 860                                 lttng_directory_handle_fini(
 861                                                 &temporary_rename_directory);
 862                                 goto end;
 863                         }
 864                 }
 865                 lttng_directory_handle_fini(&temporary_rename_directory);
 866                 directory_to_rename = DEFAULT_TEMPORARY_CHUNK_RENAME_DIRECTORY;
 867                 free_directory_to_rename = false;
 868         } else {
 869                 directory_to_rename = generate_chunk_name(chunk_id,
 870                                 creation_timestamp, NULL);
 871                 if (!directory_to_rename) {
 872                         ERR("Failed to generate initial trace chunk name while renaming trace chunk");
 873                 }
 874                 free_directory_to_rename = true;
 875         }
 876
 877         archived_chunk_name = generate_chunk_name(chunk_id, creation_timestamp,
 878                         &close_timestamp);
 879         if (!archived_chunk_name) {
 880                 ERR("Failed to generate archived trace chunk name while renaming trace chunk");
 881                 goto end;
 882         }
 883
 884         ret = lttng_directory_handle_create_subdirectory_as_user(
 885                         &trace_chunk->session_output_directory.value,
 886                         DEFAULT_ARCHIVED_TRACE_CHUNKS_DIRECTORY,
 887                         DIR_CREATION_MODE,
 888                         !trace_chunk->credentials.value.use_current_user ?
 889                                         &trace_chunk->credentials.value.user :
 890                                         NULL);
 891         if (ret) {
 892                 PERROR("Failed to create \"" DEFAULT_ARCHIVED_TRACE_CHUNKS_DIRECTORY
 893                                 "\" directory for archived trace chunks");
 894                 goto end;
 895         }
 896
 897         ret = lttng_directory_handle_init_from_handle(
 898                         &archived_chunks_directory.value,
 899                         DEFAULT_ARCHIVED_TRACE_CHUNKS_DIRECTORY,
 900                         &trace_chunk->session_output_directory.value);
 901         if (ret) {
 902                 PERROR("Failed to get handle to archived trace chunks directory");
 903                 goto end;
 904         }
 905         archived_chunks_directory.is_set = true;
 906
 907         /*
 908          * FIXME replace renamat() use by directory handle
 909          * wrapper for non-POSIX 2008 systems.
 910          */
 911         ret = renameat(session_dirfd, directory_to_rename,
 912                         archived_chunks_directory.value.dirfd,
 913                         archived_chunk_name);
 914         if (ret) {
 915                 PERROR("Failed to rename folder \"%s\" to \"%s\"",
 916                                 directory_to_rename, archived_chunk_name);
 917         }
 918
 919 end:
 920         if (archived_chunks_directory.is_set) {
 921                 lttng_directory_handle_fini(&archived_chunks_directory.value);
 922         }
 923         free(archived_chunk_name);
 924         if (free_directory_to_rename) {
 925                 free(directory_to_rename);
 926         }
 927 }
 928
 929 LTTNG_HIDDEN
 930 enum lttng_trace_chunk_status lttng_trace_chunk_set_close_command(
 931                 struct lttng_trace_chunk *chunk,
 932                 enum lttng_trace_chunk_command_type close_command)
 933 {
 934         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 935
 936         if (close_command < LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED ||
 937                         close_command >= LTTNG_TRACE_CHUNK_COMMAND_TYPE_MAX) {
 938                 status = LTTNG_TRACE_CHUNK_STATUS_INVALID_ARGUMENT;
 939                 goto end_unlock;
 940         }
 941
 942         pthread_mutex_lock(&chunk->lock);
 943         if (chunk->close_command.is_set) {
 944                 DBG("Overriding trace chunk close command from \"%s\" to \"%s\"",
 945                                 close_command_names[chunk->close_command.value],
 946                                 close_command_names[close_command]);
 947         } else {
 948                 DBG("Setting trace chunk close command to \"%s\"",
 949                                 close_command_names[close_command]);
 950         }
 951         LTTNG_OPTIONAL_SET(&chunk->close_command, close_command);
 952         pthread_mutex_unlock(&chunk->lock);
 953 end_unlock:
 954         return status;
 955 }
 956
 957 LTTNG_HIDDEN
 958 bool lttng_trace_chunk_get(struct lttng_trace_chunk *chunk)
 959 {
 960         return urcu_ref_get_unless_zero(&chunk->ref);
 961 }
 962
 963 static
 964 void free_lttng_trace_chunk_registry_element(struct rcu_head *node)
 965 {
 966         struct lttng_trace_chunk_registry_element *element =
 967                         container_of(node, typeof(*element), rcu_node);
 968
 969         lttng_trace_chunk_fini(&element->chunk);
 970         free(element);
 971 }
 972
 973 static
 974 void lttng_trace_chunk_release(struct urcu_ref *ref)
 975 {
 976         struct lttng_trace_chunk *chunk = container_of(ref, typeof(*chunk),
 977                         ref);
 978
 979         if (chunk->close_command.is_set) {
 980                 close_command_funcs[chunk->close_command.value](chunk);
 981         }
 982
 983         if (chunk->in_registry_element) {
 984                 struct lttng_trace_chunk_registry_element *element;
 985
 986                 element = container_of(chunk, typeof(*element), chunk);
 987                 if (element->registry) {
 988                         rcu_read_lock();
 989                         cds_lfht_del(element->registry->ht,
 990                                         &element->trace_chunk_registry_ht_node);
 991                         rcu_read_unlock();
 992                         call_rcu(&element->rcu_node,
 993                                         free_lttng_trace_chunk_registry_element);
 994                 } else {
 995                         /* Never published, can be free'd immediately. */
 996                         free_lttng_trace_chunk_registry_element(
 997                                         &element->rcu_node);
 998                 }
 999         } else {
1000                 /* Not RCU-protected, free immediately. */
1001                 lttng_trace_chunk_fini(chunk);
1002                 free(chunk);
1003         }
1004 }
1005
1006 LTTNG_HIDDEN
1007 void lttng_trace_chunk_put(struct lttng_trace_chunk *chunk)
1008 {
1009         if (!chunk) {
1010                 return;
1011         }
1012         assert(chunk->ref.refcount);
1013         urcu_ref_put(&chunk->ref, lttng_trace_chunk_release);
1014 }
1015
1016 LTTNG_HIDDEN
1017 struct lttng_trace_chunk_registry *lttng_trace_chunk_registry_create(void)
1018 {
1019         struct lttng_trace_chunk_registry *registry;
1020
1021         registry = zmalloc(sizeof(*registry));
1022         if (!registry) {
1023                 goto end;
1024         }
1025
1026         registry->ht = cds_lfht_new(DEFAULT_HT_SIZE, 1, 0,
1027                         CDS_LFHT_AUTO_RESIZE | CDS_LFHT_ACCOUNTING, NULL);
1028         if (!registry->ht) {
1029                 goto error;
1030         }
1031 end:
1032         return registry;
1033 error:
1034         lttng_trace_chunk_registry_destroy(registry);
1035         goto end;
1036 }
1037
1038 LTTNG_HIDDEN
1039 void lttng_trace_chunk_registry_destroy(
1040                 struct lttng_trace_chunk_registry *registry)
1041 {
1042         if (!registry) {
1043                 return;
1044         }
1045         if (registry->ht) {
1046                 int ret = cds_lfht_destroy(registry->ht, NULL);
1047                 assert(!ret);
1048         }
1049         free(registry);
1050 }
1051
1052 static
1053 struct lttng_trace_chunk_registry_element *
1054 lttng_trace_chunk_registry_element_create_from_chunk(
1055                 struct lttng_trace_chunk *chunk, uint64_t session_id)
1056 {
1057         struct lttng_trace_chunk_registry_element *element =
1058                         zmalloc(sizeof(*element));
1059
1060         if (!element) {
1061                 goto end;
1062         }
1063         cds_lfht_node_init(&element->trace_chunk_registry_ht_node);
1064         element->session_id = session_id;
1065
1066         element->chunk = *chunk;
1067         lttng_trace_chunk_init(&element->chunk);
1068         if (chunk->session_output_directory.is_set) {
1069                 element->chunk.session_output_directory.value =
1070                                 lttng_directory_handle_move(
1071                                         &chunk->session_output_directory.value);
1072         }
1073         if (chunk->chunk_directory.is_set) {
1074                 element->chunk.chunk_directory.value =
1075                                 lttng_directory_handle_move(
1076                                         &chunk->chunk_directory.value);
1077         }
1078         /*
1079          * The original chunk becomes invalid; the name attribute is transferred
1080          * to the new chunk instance.
1081          */
1082         chunk->name = NULL;
1083         element->chunk.in_registry_element = true;
1084 end:
1085         return element;
1086 }
1087
1088 LTTNG_HIDDEN
1089 struct lttng_trace_chunk *
1090 lttng_trace_chunk_registry_publish_chunk(
1091                 struct lttng_trace_chunk_registry *registry,
1092                 uint64_t session_id, struct lttng_trace_chunk *chunk)
1093 {
1094         struct lttng_trace_chunk_registry_element *element;
1095         unsigned long element_hash;
1096
1097         pthread_mutex_lock(&chunk->lock);
1098         element = lttng_trace_chunk_registry_element_create_from_chunk(chunk,
1099                         session_id);
1100         pthread_mutex_unlock(&chunk->lock);
1101         if (!element) {
1102                 goto end;
1103         }
1104         /*
1105          * chunk is now invalid, the only valid operation is a 'put' from the
1106          * caller.
1107          */
1108         chunk = NULL;
1109         element_hash = lttng_trace_chunk_registry_element_hash(element);
1110
1111         rcu_read_lock();
1112         while (1) {
1113                 struct cds_lfht_node *published_node;
1114                 struct lttng_trace_chunk *published_chunk;
1115                 struct lttng_trace_chunk_registry_element *published_element;
1116
1117                 published_node = cds_lfht_add_unique(registry->ht,
1118                                 element_hash,
1119                                 lttng_trace_chunk_registry_element_match,
1120                                 element,
1121                                 &element->trace_chunk_registry_ht_node);
1122                 if (published_node == &element->trace_chunk_registry_ht_node) {
1123                         /* Successfully published the new element. */
1124                         element->registry = registry;
1125                         /* Acquire a reference for the caller. */
1126                         if (lttng_trace_chunk_get(&element->chunk)) {
1127                                 break;
1128                         } else {
1129                                 /*
1130                                  * Another thread concurrently unpublished the
1131                                  * trace chunk. This is currently unexpected.
1132                                  *
1133                                  * Re-attempt to publish.
1134                                  */
1135                                 ERR("Attemp to publish a trace chunk to the chunk registry raced with a trace chunk deletion");
1136                                 continue;
1137                         }
1138                 }
1139
1140                 /*
1141                  * An equivalent trace chunk was published before this trace
1142                  * chunk. Attempt to acquire a reference to the one that was
1143                  * already published and release the reference to the copy we
1144                  * created if successful.
1145                  */
1146                 published_element = container_of(published_node,
1147                                 typeof(*published_element),
1148                                 trace_chunk_registry_ht_node);
1149                 published_chunk = &published_element->chunk;
1150                 if (lttng_trace_chunk_get(published_chunk)) {
1151                         lttng_trace_chunk_put(&element->chunk);
1152                         element = published_element;
1153                         break;
1154                 }
1155                 /*
1156                  * A reference to the previously published trace chunk could not
1157                  * be acquired. Hence, retry to publish our copy of the trace
1158                  * chunk.
1159                  */
1160         }
1161         rcu_read_unlock();
1162 end:
1163         return element ? &element->chunk : NULL;
1164 }
1165
1166 /*
1167  * Note that the caller must be registered as an RCU thread.
1168  * However, it does not need to hold the RCU read lock. The RCU read lock is
1169  * acquired to perform the look-up in the registry's hash table and held until
1170  * after a reference to the "found" trace chunk is acquired.
1171  *
1172  * IOW, holding a reference guarantees the existence of the object for the
1173  * caller.
1174  */
1175 static
1176 struct lttng_trace_chunk *_lttng_trace_chunk_registry_find_chunk(
1177                 const struct lttng_trace_chunk_registry *registry,
1178                 uint64_t session_id, uint64_t *chunk_id)
1179 {
1180         const struct lttng_trace_chunk_registry_element target_element = {
1181                 .chunk.id.is_set = !!chunk_id,
1182                 .chunk.id.value = chunk_id ? *chunk_id : 0,
1183                 .session_id = session_id,
1184         };
1185         const unsigned long element_hash =
1186                         lttng_trace_chunk_registry_element_hash(
1187                                 &target_element);
1188         struct cds_lfht_node *published_node;
1189         struct lttng_trace_chunk_registry_element *published_element;
1190         struct lttng_trace_chunk *published_chunk = NULL;
1191         struct cds_lfht_iter iter;
1192
1193         rcu_read_lock();
1194         cds_lfht_lookup(registry->ht,
1195                         element_hash,
1196                         lttng_trace_chunk_registry_element_match,
1197                         &target_element,
1198                         &iter);
1199         published_node = cds_lfht_iter_get_node(&iter);
1200         if (!published_node) {
1201                 goto end;
1202         }
1203
1204         published_element = container_of(published_node,
1205                         typeof(*published_element),
1206                         trace_chunk_registry_ht_node);
1207         if (lttng_trace_chunk_get(&published_element->chunk)) {
1208                 published_chunk = &published_element->chunk;
1209         }
1210 end:
1211         rcu_read_unlock();
1212         return published_chunk;
1213 }
1214
1215 LTTNG_HIDDEN
1216 struct lttng_trace_chunk *
1217 lttng_trace_chunk_registry_find_chunk(
1218                 const struct lttng_trace_chunk_registry *registry,
1219                 uint64_t session_id, uint64_t chunk_id)
1220 {
1221         return _lttng_trace_chunk_registry_find_chunk(registry,
1222                         session_id, &chunk_id);
1223 }
1224
1225 LTTNG_HIDDEN
1226 struct lttng_trace_chunk *
1227 lttng_trace_chunk_registry_find_anonymous_chunk(
1228                 const struct lttng_trace_chunk_registry *registry,
1229                 uint64_t session_id)
1230 {
1231         return _lttng_trace_chunk_registry_find_chunk(registry,
1232                         session_id, NULL);
1233 }