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 /* NOTE: Make sure to update lttng_trace_chunk_copy if you modify this. */
  70 struct lttng_trace_chunk {
  71         pthread_mutex_t lock;
  72         struct urcu_ref ref;
  73         LTTNG_OPTIONAL(enum trace_chunk_mode) mode;
  74         /*
  75          * First-level directories created within the trace chunk.
  76          * Elements are of type 'char *'.
  77          *
  78          * Only used by _owner_ mode chunks.
  79          */
  80         struct lttng_dynamic_pointer_array top_level_directories;
  81         /* Is contained within an lttng_trace_chunk_registry_element? */
  82         bool in_registry_element;
  83         bool name_overridden;
  84         char *name;
  85         /* An unset id means the chunk is anonymous. */
  86         LTTNG_OPTIONAL(uint64_t) id;
  87         LTTNG_OPTIONAL(time_t) timestamp_creation;
  88         LTTNG_OPTIONAL(time_t) timestamp_close;
  89         LTTNG_OPTIONAL(struct chunk_credentials) credentials;
  90         LTTNG_OPTIONAL(struct lttng_directory_handle) session_output_directory;
  91         LTTNG_OPTIONAL(struct lttng_directory_handle) chunk_directory;
  92         LTTNG_OPTIONAL(enum lttng_trace_chunk_command_type) close_command;
  93 };
  94
  95 /* A trace chunk is uniquely identified by its (session id, chunk id) tuple. */
  96 struct lttng_trace_chunk_registry_element {
  97         struct lttng_trace_chunk chunk;
  98         uint64_t session_id;
  99         /* Weak and only set when added. */
 100         struct lttng_trace_chunk_registry *registry;
 101         struct cds_lfht_node trace_chunk_registry_ht_node;
 102         /* call_rcu delayed reclaim. */
 103         struct rcu_head rcu_node;
 104 };
 105
 106 struct lttng_trace_chunk_registry {
 107         struct cds_lfht *ht;
 108 };
 109
 110 static const
 111 char *close_command_names[] = {
 112         [LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED] =
 113                 "move to completed chunk folder",
 114 };
 115
 116 static const
 117 chunk_close_command close_command_funcs[] = {
 118         [LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED] =
 119                         lttng_trace_chunk_move_to_completed,
 120 };
 121
 122 static
 123 bool lttng_trace_chunk_registry_element_equals(
 124                 const struct lttng_trace_chunk_registry_element *a,
 125                 const struct lttng_trace_chunk_registry_element *b)
 126 {
 127         if (a->session_id != b->session_id) {
 128                 goto not_equal;
 129         }
 130         if (a->chunk.id.is_set != b->chunk.id.is_set) {
 131                 goto not_equal;
 132         }
 133         if (a->chunk.id.is_set && a->chunk.id.value != b->chunk.id.value) {
 134                 goto not_equal;
 135         }
 136         return true;
 137 not_equal:
 138         return false;
 139 }
 140
 141 static
 142 int lttng_trace_chunk_registry_element_match(struct cds_lfht_node *node,
 143                 const void *key)
 144 {
 145         const struct lttng_trace_chunk_registry_element *element_a, *element_b;
 146
 147         element_a = (const struct lttng_trace_chunk_registry_element *) key;
 148         element_b = caa_container_of(node, typeof(*element_b),
 149                         trace_chunk_registry_ht_node);
 150         return lttng_trace_chunk_registry_element_equals(element_a, element_b);
 151 }
 152
 153 static
 154 unsigned long lttng_trace_chunk_registry_element_hash(
 155                 const struct lttng_trace_chunk_registry_element *element)
 156 {
 157         unsigned long hash = hash_key_u64(&element->session_id,
 158                         lttng_ht_seed);
 159
 160         if (element->chunk.id.is_set) {
 161                 hash ^= hash_key_u64(&element->chunk.id.value, lttng_ht_seed);
 162         }
 163
 164         return hash;
 165 }
 166
 167 static
 168 char *generate_chunk_name(uint64_t chunk_id, time_t creation_timestamp,
 169                 const time_t *close_timestamp)
 170 {
 171         int ret = 0;
 172         char *new_name= NULL;
 173         char start_datetime[ISO8601_STR_LEN] = {};
 174         /* Add 1 for a '-' prefix. */
 175         char end_datetime_suffix[ISO8601_STR_LEN + 1] = {};
 176
 177         ret = time_to_iso8601_str(
 178                         creation_timestamp,
 179                         start_datetime, sizeof(start_datetime));
 180         if (ret) {
 181                 ERR("Failed to format trace chunk start date time");
 182                 goto error;
 183         }
 184         if (close_timestamp) {
 185                 *end_datetime_suffix = '-';
 186                 ret = time_to_iso8601_str(
 187                                 *close_timestamp,
 188                                 end_datetime_suffix + 1,
 189                                 sizeof(end_datetime_suffix) - 1);
 190                 if (ret) {
 191                         ERR("Failed to format trace chunk end date time");
 192                         goto error;
 193                 }
 194         }
 195         new_name = zmalloc(GENERATED_CHUNK_NAME_LEN);
 196         if (!new_name) {
 197                 ERR("Failed to allocate buffer for automatically-generated trace chunk name");
 198                 goto error;
 199         }
 200         ret = snprintf(new_name, GENERATED_CHUNK_NAME_LEN, "%s%s-%" PRIu64,
 201                         start_datetime, end_datetime_suffix, chunk_id);
 202         if (ret >= GENERATED_CHUNK_NAME_LEN || ret == -1) {
 203                 ERR("Failed to format trace chunk name");
 204                 goto error;
 205         }
 206
 207         return new_name;
 208 error:
 209         free(new_name);
 210         return NULL;
 211 }
 212
 213 static
 214 void lttng_trace_chunk_init(struct lttng_trace_chunk *chunk)
 215 {
 216         urcu_ref_init(&chunk->ref);
 217         pthread_mutex_init(&chunk->lock, NULL);
 218         lttng_dynamic_pointer_array_init(&chunk->top_level_directories, free);
 219 }
 220
 221 static
 222 void lttng_trace_chunk_fini(struct lttng_trace_chunk *chunk)
 223 {
 224         if (chunk->session_output_directory.is_set) {
 225                 lttng_directory_handle_fini(
 226                                 &chunk->session_output_directory.value);
 227         }
 228         if (chunk->chunk_directory.is_set) {
 229                 lttng_directory_handle_fini(&chunk->chunk_directory.value);
 230         }
 231         free(chunk->name);
 232         chunk->name = NULL;
 233         lttng_dynamic_pointer_array_reset(&chunk->top_level_directories);
 234         pthread_mutex_destroy(&chunk->lock);
 235 }
 236
 237 static
 238 struct lttng_trace_chunk *lttng_trace_chunk_allocate(void)
 239 {
 240         struct lttng_trace_chunk *chunk = NULL;
 241
 242         chunk = zmalloc(sizeof(*chunk));
 243         if (!chunk) {
 244                 ERR("Failed to allocate trace chunk");
 245                 goto end;
 246         }
 247         lttng_trace_chunk_init(chunk);
 248 end:
 249         return chunk;
 250 }
 251
 252 LTTNG_HIDDEN
 253 struct lttng_trace_chunk *lttng_trace_chunk_create_anonymous(void)
 254 {
 255         DBG("Creating anonymous trace chunk");
 256         return lttng_trace_chunk_allocate();
 257 }
 258
 259 LTTNG_HIDDEN
 260 struct lttng_trace_chunk *lttng_trace_chunk_create(
 261                 uint64_t chunk_id, time_t chunk_creation_time)
 262 {
 263         struct lttng_trace_chunk *chunk;
 264         char chunk_creation_datetime_buf[16] = {};
 265         const char *chunk_creation_datetime_str = "(formatting error)";
 266         struct tm timeinfo_buf, *timeinfo;
 267
 268         timeinfo = localtime_r(&chunk_creation_time, &timeinfo_buf);
 269         if (timeinfo) {
 270                 size_t strftime_ret;
 271
 272                 /* Don't fail because of this; it is only used for logging. */
 273                 strftime_ret = strftime(chunk_creation_datetime_buf,
 274                                 sizeof(chunk_creation_datetime_buf),
 275                                 "%Y%m%d-%H%M%S", timeinfo);
 276                 if (strftime_ret) {
 277                         chunk_creation_datetime_str =
 278                                         chunk_creation_datetime_buf;
 279                 }
 280         }
 281
 282         DBG("Creating trace chunk: chunk_id = %" PRIu64 ", creation time = %s",
 283                         chunk_id, chunk_creation_datetime_str);
 284         chunk = lttng_trace_chunk_allocate();
 285         if (!chunk) {
 286                 goto end;
 287         }
 288
 289         LTTNG_OPTIONAL_SET(&chunk->id, chunk_id);
 290         LTTNG_OPTIONAL_SET(&chunk->timestamp_creation, chunk_creation_time);
 291         if (chunk_id != 0) {
 292                 chunk->name = generate_chunk_name(chunk_id,
 293                                 chunk_creation_time, NULL);
 294                 if (!chunk->name) {
 295                         ERR("Failed to allocate trace chunk name storage");
 296                         goto error;
 297                 }
 298         }
 299
 300         DBG("Chunk name set to \"%s\"", chunk->name ? : "(none)");
 301 end:
 302         return chunk;
 303 error:
 304         lttng_trace_chunk_put(chunk);
 305         return NULL;
 306 }
 307
 308 LTTNG_HIDDEN
 309 struct lttng_trace_chunk *lttng_trace_chunk_copy(
 310                 struct lttng_trace_chunk *source_chunk)
 311 {
 312         struct lttng_trace_chunk *new_chunk = lttng_trace_chunk_allocate();
 313
 314         if (!new_chunk) {
 315                 goto end;
 316         }
 317
 318         pthread_mutex_lock(&source_chunk->lock);
 319         /*
 320          * A new chunk is always a user; it shall create no new trace
 321          * subdirectories.
 322          */
 323         new_chunk->mode = (typeof(new_chunk->mode)) {
 324                 .is_set = true,
 325                 .value = TRACE_CHUNK_MODE_USER,
 326         };
 327         /*
 328          * top_level_directories is not copied as it is never used
 329          * by _user_ mode chunks.
 330          */
 331         /* The new chunk is not part of a registry (yet, at least). */
 332         new_chunk->in_registry_element = false;
 333         new_chunk->name_overridden = source_chunk->name_overridden;
 334         if (source_chunk->name) {
 335                 new_chunk->name = strdup(source_chunk->name);
 336                 if (!new_chunk->name) {
 337                         ERR("Failed to copy source trace chunk name in %s()",
 338                                         __FUNCTION__);
 339                         goto error_unlock;
 340                 }
 341         }
 342         new_chunk->id = source_chunk->id;
 343         new_chunk->timestamp_creation = source_chunk->timestamp_creation;
 344         new_chunk->timestamp_close = source_chunk->timestamp_close;
 345         new_chunk->credentials = source_chunk->credentials;
 346         if (source_chunk->session_output_directory.is_set) {
 347                 if (lttng_directory_handle_copy(
 348                                 &source_chunk->session_output_directory.value,
 349                                 &new_chunk->session_output_directory.value)) {
 350                         goto error_unlock;
 351                 } else {
 352                         new_chunk->session_output_directory.is_set = true;
 353                 }
 354         }
 355         if (source_chunk->chunk_directory.is_set) {
 356                 if (lttng_directory_handle_copy(
 357                                 &source_chunk->chunk_directory.value,
 358                                 &new_chunk->chunk_directory.value)) {
 359                         goto error_unlock;
 360                 } else {
 361                         new_chunk->chunk_directory.is_set = true;
 362                 }
 363         }
 364         new_chunk->close_command = source_chunk->close_command;
 365         pthread_mutex_unlock(&source_chunk->lock);
 366 end:
 367         return new_chunk;
 368 error_unlock:
 369         pthread_mutex_unlock(&source_chunk->lock);
 370         return NULL;
 371 }
 372
 373 LTTNG_HIDDEN
 374 enum lttng_trace_chunk_status lttng_trace_chunk_get_id(
 375                 struct lttng_trace_chunk *chunk, uint64_t *id)
 376 {
 377         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 378
 379         pthread_mutex_lock(&chunk->lock);
 380         if (chunk->id.is_set) {
 381                 *id = chunk->id.value;
 382         } else {
 383                 status = LTTNG_TRACE_CHUNK_STATUS_NONE;
 384         }
 385         pthread_mutex_unlock(&chunk->lock);
 386         return status;
 387 }
 388
 389 LTTNG_HIDDEN
 390 enum lttng_trace_chunk_status lttng_trace_chunk_get_creation_timestamp(
 391                 struct lttng_trace_chunk *chunk, time_t *creation_ts)
 392
 393 {
 394         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 395
 396         pthread_mutex_lock(&chunk->lock);
 397         if (chunk->timestamp_creation.is_set) {
 398                 *creation_ts = chunk->timestamp_creation.value;
 399         } else {
 400                 status = LTTNG_TRACE_CHUNK_STATUS_NONE;
 401         }
 402         pthread_mutex_unlock(&chunk->lock);
 403         return status;
 404 }
 405
 406 LTTNG_HIDDEN
 407 enum lttng_trace_chunk_status lttng_trace_chunk_get_close_timestamp(
 408                 struct lttng_trace_chunk *chunk, time_t *close_ts)
 409 {
 410         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 411
 412         pthread_mutex_lock(&chunk->lock);
 413         if (chunk->timestamp_close.is_set) {
 414                 *close_ts = chunk->timestamp_close.value;
 415         } else {
 416                 status = LTTNG_TRACE_CHUNK_STATUS_NONE;
 417         }
 418         pthread_mutex_unlock(&chunk->lock);
 419         return status;
 420 }
 421
 422 LTTNG_HIDDEN
 423 enum lttng_trace_chunk_status lttng_trace_chunk_set_close_timestamp(
 424                 struct lttng_trace_chunk *chunk, time_t close_ts)
 425 {
 426         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 427
 428         pthread_mutex_lock(&chunk->lock);
 429         if (!chunk->timestamp_creation.is_set) {
 430                 ERR("Failed to set trace chunk close timestamp: creation timestamp is unset");
 431                 status = LTTNG_TRACE_CHUNK_STATUS_INVALID_OPERATION;
 432                 goto end;
 433         }
 434         if (chunk->timestamp_creation.value > close_ts) {
 435                 ERR("Failed to set trace chunk close timestamp: close timestamp is before creation timestamp");
 436                 status = LTTNG_TRACE_CHUNK_STATUS_INVALID_ARGUMENT;
 437                 goto end;
 438         }
 439         LTTNG_OPTIONAL_SET(&chunk->timestamp_close, close_ts);
 440         if (!chunk->name_overridden) {
 441                 free(chunk->name);
 442                 chunk->name = generate_chunk_name(LTTNG_OPTIONAL_GET(chunk->id),
 443                                 LTTNG_OPTIONAL_GET(chunk->timestamp_creation),
 444                                 &close_ts);
 445                 if (!chunk->name) {
 446                         status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 447                 }
 448         }
 449 end:
 450         pthread_mutex_unlock(&chunk->lock);
 451         return status;
 452 }
 453
 454 LTTNG_HIDDEN
 455 enum lttng_trace_chunk_status lttng_trace_chunk_get_name(
 456                 struct lttng_trace_chunk *chunk, const char **name,
 457                 bool *name_overridden)
 458 {
 459         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 460
 461         pthread_mutex_lock(&chunk->lock);
 462         if (name_overridden) {
 463                 *name_overridden = chunk->name_overridden;
 464         }
 465         if (!chunk->name) {
 466                 status = LTTNG_TRACE_CHUNK_STATUS_NONE;
 467                 goto end;
 468         }
 469         *name = chunk->name;
 470 end:
 471         pthread_mutex_unlock(&chunk->lock);
 472         return status;
 473 }
 474
 475 static
 476 bool is_valid_chunk_name(const char *name)
 477 {
 478         size_t len;
 479
 480         if (!name) {
 481                 return false;
 482         }
 483
 484         len = lttng_strnlen(name, LTTNG_NAME_MAX);
 485         if (len == 0 || len == LTTNG_NAME_MAX) {
 486                 return false;
 487         }
 488
 489         if (strchr(name, '/') || strchr(name, '.')) {
 490                 return false;
 491         }
 492
 493         return true;
 494 }
 495
 496 LTTNG_HIDDEN
 497 enum lttng_trace_chunk_status lttng_trace_chunk_override_name(
 498                 struct lttng_trace_chunk *chunk, const char *name)
 499
 500 {
 501         char *new_name;
 502         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 503
 504         if (!is_valid_chunk_name(name)) {
 505                 ERR("Attempted to set an invalid name on a trace chunk: name = %s",
 506                                 name ? : "NULL");
 507                 status = LTTNG_TRACE_CHUNK_STATUS_INVALID_ARGUMENT;
 508                 goto end;
 509         }
 510
 511         pthread_mutex_lock(&chunk->lock);
 512         if (!chunk->id.is_set) {
 513                 ERR("Attempted to set an override name on an anonymous trace chunk: name = %s",
 514                                 name);
 515                 status = LTTNG_TRACE_CHUNK_STATUS_INVALID_OPERATION;
 516                 goto end_unlock;
 517         }
 518         new_name = strdup(name);
 519         if (!new_name) {
 520                 ERR("Failed to allocate new trace chunk name");
 521                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 522                 goto end_unlock;
 523         }
 524         free(chunk->name);
 525         chunk->name = new_name;
 526         chunk->name_overridden = true;
 527 end_unlock:
 528         pthread_mutex_unlock(&chunk->lock);
 529 end:
 530         return status;
 531 }
 532
 533 LTTNG_HIDDEN
 534 enum lttng_trace_chunk_status lttng_trace_chunk_get_credentials(
 535                 struct lttng_trace_chunk *chunk,
 536                 struct lttng_credentials *credentials)
 537 {
 538         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 539
 540         pthread_mutex_lock(&chunk->lock);
 541         if (chunk->credentials.is_set) {
 542                 if (chunk->credentials.value.use_current_user) {
 543                         credentials->uid = geteuid();
 544                         credentials->gid = getegid();
 545                 } else {
 546                         *credentials = chunk->credentials.value.user;
 547                 }
 548         } else {
 549                 status = LTTNG_TRACE_CHUNK_STATUS_NONE;
 550         }
 551         pthread_mutex_unlock(&chunk->lock);
 552         return status;
 553 }
 554
 555 LTTNG_HIDDEN
 556 enum lttng_trace_chunk_status lttng_trace_chunk_set_credentials(
 557                 struct lttng_trace_chunk *chunk,
 558                 const struct lttng_credentials *user_credentials)
 559 {
 560         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 561         const struct chunk_credentials credentials = {
 562                 .user = *user_credentials,
 563                 .use_current_user = false,
 564         };
 565
 566         pthread_mutex_lock(&chunk->lock);
 567         if (chunk->credentials.is_set) {
 568                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 569                 goto end;
 570         }
 571         LTTNG_OPTIONAL_SET(&chunk->credentials, credentials);
 572 end:
 573         pthread_mutex_unlock(&chunk->lock);
 574         return status;
 575 }
 576
 577 LTTNG_HIDDEN
 578 enum lttng_trace_chunk_status lttng_trace_chunk_set_credentials_current_user(
 579                 struct lttng_trace_chunk *chunk)
 580 {
 581         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 582         const struct chunk_credentials credentials = {
 583                 .use_current_user = true,
 584         };
 585
 586         pthread_mutex_lock(&chunk->lock);
 587         if (chunk->credentials.is_set) {
 588                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 589                 goto end;
 590         }
 591         LTTNG_OPTIONAL_SET(&chunk->credentials, credentials);
 592 end:
 593         pthread_mutex_unlock(&chunk->lock);
 594         return status;
 595 }
 596
 597
 598 LTTNG_HIDDEN
 599 enum lttng_trace_chunk_status lttng_trace_chunk_set_as_owner(
 600                 struct lttng_trace_chunk *chunk,
 601                 struct lttng_directory_handle *session_output_directory)
 602 {
 603         int ret;
 604         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 605         struct lttng_directory_handle chunk_directory_handle;
 606
 607         pthread_mutex_lock(&chunk->lock);
 608         if (chunk->mode.is_set) {
 609                 status = LTTNG_TRACE_CHUNK_STATUS_INVALID_OPERATION;
 610                 goto end;
 611         }
 612         if (!chunk->credentials.is_set) {
 613                 /*
 614                  * Fatal error, credentials must be set before a
 615                  * directory is created.
 616                  */
 617                 ERR("Credentials of trace chunk are unset: refusing to set session output directory");
 618                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 619                 goto end;
 620         }
 621
 622         if (chunk->name) {
 623                 /*
 624                  * A nameless chunk does not need its own output directory.
 625                  * The session's output directory will be used.
 626                  */
 627                 ret = lttng_directory_handle_create_subdirectory_as_user(
 628                                 session_output_directory,
 629                                 chunk->name,
 630                                 DIR_CREATION_MODE,
 631                                 !chunk->credentials.value.use_current_user ?
 632                                         &chunk->credentials.value.user : NULL);
 633                 if (ret) {
 634                         PERROR("Failed to create chunk output directory \"%s\"",
 635                                 chunk->name);
 636                         status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 637                         goto end;
 638                 }
 639         }
 640         ret = lttng_directory_handle_init_from_handle(&chunk_directory_handle,
 641                         chunk->name,
 642                         session_output_directory);
 643         if (ret) {
 644                 /* The function already logs on all error paths. */
 645                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 646                 goto end;
 647         }
 648         LTTNG_OPTIONAL_SET(&chunk->session_output_directory,
 649                         lttng_directory_handle_move(session_output_directory));
 650         LTTNG_OPTIONAL_SET(&chunk->chunk_directory,
 651                         lttng_directory_handle_move(&chunk_directory_handle));
 652         LTTNG_OPTIONAL_SET(&chunk->mode, TRACE_CHUNK_MODE_OWNER);
 653 end:
 654         pthread_mutex_unlock(&chunk->lock);
 655         return status;
 656 }
 657
 658 LTTNG_HIDDEN
 659 enum lttng_trace_chunk_status lttng_trace_chunk_set_as_user(
 660                 struct lttng_trace_chunk *chunk,
 661                 struct lttng_directory_handle *chunk_directory)
 662 {
 663         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 664
 665         pthread_mutex_lock(&chunk->lock);
 666         if (chunk->mode.is_set) {
 667                 status = LTTNG_TRACE_CHUNK_STATUS_INVALID_OPERATION;
 668                 goto end;
 669         }
 670         if (!chunk->credentials.is_set) {
 671                 ERR("Credentials of trace chunk are unset: refusing to set chunk output directory");
 672                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 673                 goto end;
 674         }
 675         LTTNG_OPTIONAL_SET(&chunk->chunk_directory,
 676                         lttng_directory_handle_move(chunk_directory));
 677         LTTNG_OPTIONAL_SET(&chunk->mode, TRACE_CHUNK_MODE_USER);
 678 end:
 679         pthread_mutex_unlock(&chunk->lock);
 680         return status;
 681 }
 682
 683 LTTNG_HIDDEN
 684 enum lttng_trace_chunk_status lttng_trace_chunk_get_chunk_directory_handle(
 685                 struct lttng_trace_chunk *chunk,
 686                 const struct lttng_directory_handle **handle)
 687 {
 688         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 689
 690         pthread_mutex_lock(&chunk->lock);
 691         if (!chunk->chunk_directory.is_set) {
 692                 status = LTTNG_TRACE_CHUNK_STATUS_NONE;
 693                 goto end;
 694         }
 695
 696         *handle = &chunk->chunk_directory.value;
 697 end:
 698         pthread_mutex_unlock(&chunk->lock);
 699         return status;
 700 }
 701
 702 /* Add a top-level directory to the trace chunk if it was previously unknown. */
 703 static
 704 int add_top_level_directory_unique(struct lttng_trace_chunk *chunk,
 705                 const char *new_path)
 706 {
 707         int ret = 0;
 708         bool found = false;
 709         size_t i, count = lttng_dynamic_pointer_array_get_count(
 710                         &chunk->top_level_directories);
 711         const char *new_path_separator_pos = strchr(new_path, '/');
 712         const ptrdiff_t new_path_top_level_len = new_path_separator_pos ?
 713                         new_path_separator_pos - new_path : strlen(new_path);
 714
 715         for (i = 0; i < count; i++) {
 716                 const char *path = lttng_dynamic_pointer_array_get_pointer(
 717                                 &chunk->top_level_directories, i);
 718                 const ptrdiff_t path_top_level_len = strlen(path);
 719
 720                 if (path_top_level_len != new_path_top_level_len) {
 721                         continue;
 722                 }
 723                 if (!strncmp(path, new_path, path_top_level_len)) {
 724                         found = true;
 725                         break;
 726                 }
 727         }
 728
 729         if (!found) {
 730                 char *copy = lttng_strndup(new_path, new_path_top_level_len);
 731
 732                 DBG("Adding new top-level directory \"%s\" to trace chunk \"%s\"",
 733                                 new_path, chunk->name ? : "(unnamed)");
 734                 if (!copy) {
 735                         PERROR("Failed to copy path");
 736                         ret = -1;
 737                         goto end;
 738                 }
 739                 ret = lttng_dynamic_pointer_array_add_pointer(
 740                                 &chunk->top_level_directories, copy);
 741                 if (ret) {
 742                         ERR("Allocation failure while adding top-level directory entry to a trace chunk");
 743                         free(copy);
 744                         goto end;
 745                 }
 746         }
 747 end:
 748         return ret;
 749 }
 750
 751 LTTNG_HIDDEN
 752 enum lttng_trace_chunk_status lttng_trace_chunk_create_subdirectory(
 753                 struct lttng_trace_chunk *chunk,
 754                 const char *path)
 755 {
 756         int ret;
 757         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 758
 759         DBG("Creating trace chunk subdirectory \"%s\"", path);
 760         pthread_mutex_lock(&chunk->lock);
 761         if (!chunk->credentials.is_set) {
 762                 /*
 763                  * Fatal error, credentials must be set before a
 764                  * directory is created.
 765                  */
 766                 ERR("Credentials of trace chunk are unset: refusing to create subdirectory \"%s\"",
 767                                 path);
 768                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 769                 goto end;
 770         }
 771         if (!chunk->mode.is_set ||
 772                         chunk->mode.value != TRACE_CHUNK_MODE_OWNER) {
 773                 ERR("Attempted to create trace chunk subdirectory \"%s\" through a non-owner chunk",
 774                                 path);
 775                 status = LTTNG_TRACE_CHUNK_STATUS_INVALID_OPERATION;
 776                 goto end;
 777         }
 778         if (!chunk->chunk_directory.is_set) {
 779                 ERR("Attempted to create trace chunk subdirectory \"%s\" before setting the chunk output directory",
 780                                 path);
 781                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 782                 goto end;
 783         }
 784         if (*path == '/') {
 785                 ERR("Refusing to create absolute trace chunk directory \"%s\"",
 786                                 path);
 787                 status = LTTNG_TRACE_CHUNK_STATUS_INVALID_ARGUMENT;
 788                 goto end;
 789         }
 790         ret = lttng_directory_handle_create_subdirectory_recursive_as_user(
 791                         &chunk->chunk_directory.value, path,
 792                         DIR_CREATION_MODE,
 793                         chunk->credentials.value.use_current_user ?
 794                                         NULL : &chunk->credentials.value.user);
 795         if (ret) {
 796                 PERROR("Failed to create trace chunk subdirectory \"%s\"",
 797                                 path);
 798                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 799                 goto end;
 800         }
 801         ret = add_top_level_directory_unique(chunk, path);
 802         if (ret) {
 803                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 804                 goto end;
 805         }
 806 end:
 807         pthread_mutex_unlock(&chunk->lock);
 808         return status;
 809 }
 810
 811 LTTNG_HIDDEN
 812 enum lttng_trace_chunk_status lttng_trace_chunk_open_file(
 813                 struct lttng_trace_chunk *chunk, const char *file_path,
 814                 int flags, mode_t mode, int *out_fd)
 815 {
 816         int ret;
 817         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 818
 819         DBG("Opening trace chunk file \"%s\"", file_path);
 820         pthread_mutex_lock(&chunk->lock);
 821         if (!chunk->credentials.is_set) {
 822                 /*
 823                  * Fatal error, credentials must be set before a
 824                  * file is created.
 825                  */
 826                 ERR("Credentials of trace chunk are unset: refusing to open file \"%s\"",
 827                                 file_path);
 828                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 829                 goto end;
 830         }
 831         if (!chunk->chunk_directory.is_set) {
 832                 ERR("Attempted to open trace chunk file \"%s\" before setting the chunk output directory",
 833                                 file_path);
 834                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 835                 goto end;
 836         }
 837         ret = lttng_directory_handle_open_file_as_user(
 838                         &chunk->chunk_directory.value, file_path, flags, mode,
 839                         chunk->credentials.value.use_current_user ?
 840                                         NULL : &chunk->credentials.value.user);
 841         if (ret < 0) {
 842                 ERR("Failed to open file relative to trace chunk file_path = \"%s\", flags = %d, mode = %d",
 843                                 file_path, flags, (int) mode);
 844                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 845                 goto end;
 846         }
 847         *out_fd = ret;
 848 end:
 849         pthread_mutex_unlock(&chunk->lock);
 850         return status;
 851 }
 852
 853 LTTNG_HIDDEN
 854 int lttng_trace_chunk_unlink_file(struct lttng_trace_chunk *chunk,
 855                 const char *file_path)
 856 {
 857         int ret;
 858         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 859
 860         DBG("Unlinking trace chunk file \"%s\"", file_path);
 861         pthread_mutex_lock(&chunk->lock);
 862         if (!chunk->credentials.is_set) {
 863                 /*
 864                  * Fatal error, credentials must be set before a
 865                  * directory is created.
 866                  */
 867                 ERR("Credentials of trace chunk are unset: refusing to unlink file \"%s\"",
 868                                 file_path);
 869                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 870                 goto end;
 871         }
 872         if (!chunk->chunk_directory.is_set) {
 873                 ERR("Attempted to unlink trace chunk file \"%s\" before setting the chunk output directory",
 874                                 file_path);
 875                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 876                 goto end;
 877         }
 878         ret = lttng_directory_handle_unlink_file_as_user(
 879                         &chunk->chunk_directory.value, file_path,
 880                         chunk->credentials.value.use_current_user ?
 881                                         NULL : &chunk->credentials.value.user);
 882         if (ret < 0) {
 883                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 884                 goto end;
 885         }
 886 end:
 887         pthread_mutex_unlock(&chunk->lock);
 888         return status;
 889 }
 890
 891 static
 892 void lttng_trace_chunk_move_to_completed(struct lttng_trace_chunk *trace_chunk)
 893 {
 894         int ret;
 895         char *directory_to_rename = NULL;
 896         bool free_directory_to_rename = false;
 897         char *archived_chunk_name = NULL;
 898         const uint64_t chunk_id = LTTNG_OPTIONAL_GET(trace_chunk->id);
 899         const time_t creation_timestamp =
 900                         LTTNG_OPTIONAL_GET(trace_chunk->timestamp_creation);
 901         const time_t close_timestamp =
 902                         LTTNG_OPTIONAL_GET(trace_chunk->timestamp_close);
 903         LTTNG_OPTIONAL(struct lttng_directory_handle) archived_chunks_directory = {};
 904
 905         if (!trace_chunk->mode.is_set ||
 906                         trace_chunk->mode.value != TRACE_CHUNK_MODE_OWNER ||
 907                         !trace_chunk->session_output_directory.is_set) {
 908                 /*
 909                  * This command doesn't need to run if the output is remote
 910                  * or if the trace chunk is not owned by this process.
 911                  */
 912                 goto end;
 913         }
 914
 915         assert(trace_chunk->mode.value == TRACE_CHUNK_MODE_OWNER);
 916         assert(!trace_chunk->name_overridden);
 917
 918         /*
 919          * The fist trace chunk of a session is directly output to the
 920          * session's output folder. In this case, the top level directories
 921          * must be moved to a temporary folder before that temporary directory
 922          * is renamed to match the chunk's name.
 923          */
 924         if (chunk_id == 0) {
 925                 struct lttng_directory_handle temporary_rename_directory;
 926                 size_t i, count = lttng_dynamic_pointer_array_get_count(
 927                                 &trace_chunk->top_level_directories);
 928
 929                 ret = lttng_directory_handle_create_subdirectory_as_user(
 930                                 &trace_chunk->session_output_directory.value,
 931                                 DEFAULT_TEMPORARY_CHUNK_RENAME_DIRECTORY,
 932                                 DIR_CREATION_MODE,
 933                                 !trace_chunk->credentials.value.use_current_user ?
 934                                         &trace_chunk->credentials.value.user : NULL);
 935                 if (ret) {
 936                         PERROR("Failed to create temporary trace chunk rename directory \"%s\"",
 937                                         DEFAULT_TEMPORARY_CHUNK_RENAME_DIRECTORY);
 938                 }
 939
 940                 ret = lttng_directory_handle_init_from_handle(&temporary_rename_directory,
 941                                 DEFAULT_TEMPORARY_CHUNK_RENAME_DIRECTORY,
 942                                 &trace_chunk->session_output_directory.value);
 943                 if (ret) {
 944                         ERR("Failed to get handle to temporary trace chunk rename directory");
 945                         goto end;
 946                 }
 947
 948                 for (i = 0; i < count; i++) {
 949                         const char *top_level_name =
 950                                         lttng_dynamic_pointer_array_get_pointer(
 951                                                 &trace_chunk->top_level_directories, i);
 952
 953                         ret = lttng_directory_handle_rename_as_user(
 954                                         &trace_chunk->session_output_directory.value,
 955                                         top_level_name,
 956                                         &temporary_rename_directory,
 957                                         top_level_name,
 958                                         LTTNG_OPTIONAL_GET(trace_chunk->credentials).use_current_user ?
 959                                                 NULL :
 960                                                 &trace_chunk->credentials.value.user);
 961                         if (ret) {
 962                                 PERROR("Failed to move \"%s\" to temporary trace chunk rename directory",
 963                                                 top_level_name);
 964                                 lttng_directory_handle_fini(
 965                                                 &temporary_rename_directory);
 966                                 goto end;
 967                         }
 968                 }
 969                 lttng_directory_handle_fini(&temporary_rename_directory);
 970                 directory_to_rename = DEFAULT_TEMPORARY_CHUNK_RENAME_DIRECTORY;
 971                 free_directory_to_rename = false;
 972         } else {
 973                 directory_to_rename = generate_chunk_name(chunk_id,
 974                                 creation_timestamp, NULL);
 975                 if (!directory_to_rename) {
 976                         ERR("Failed to generate initial trace chunk name while renaming trace chunk");
 977                 }
 978                 free_directory_to_rename = true;
 979         }
 980
 981         archived_chunk_name = generate_chunk_name(chunk_id, creation_timestamp,
 982                         &close_timestamp);
 983         if (!archived_chunk_name) {
 984                 ERR("Failed to generate archived trace chunk name while renaming trace chunk");
 985                 goto end;
 986         }
 987
 988         ret = lttng_directory_handle_create_subdirectory_as_user(
 989                         &trace_chunk->session_output_directory.value,
 990                         DEFAULT_ARCHIVED_TRACE_CHUNKS_DIRECTORY,
 991                         DIR_CREATION_MODE,
 992                         !trace_chunk->credentials.value.use_current_user ?
 993                                         &trace_chunk->credentials.value.user :
 994                                         NULL);
 995         if (ret) {
 996                 PERROR("Failed to create \"" DEFAULT_ARCHIVED_TRACE_CHUNKS_DIRECTORY
 997                                 "\" directory for archived trace chunks");
 998                 goto end;
 999         }
1000
1001         ret = lttng_directory_handle_init_from_handle(
1002                         &archived_chunks_directory.value,
1003                         DEFAULT_ARCHIVED_TRACE_CHUNKS_DIRECTORY,
1004                         &trace_chunk->session_output_directory.value);
1005         if (ret) {
1006                 PERROR("Failed to get handle to archived trace chunks directory");
1007                 goto end;
1008         }
1009         archived_chunks_directory.is_set = true;
1010
1011         ret = lttng_directory_handle_rename_as_user(
1012                         &trace_chunk->session_output_directory.value,
1013                         directory_to_rename,
1014                         &archived_chunks_directory.value,
1015                         archived_chunk_name,
1016                         LTTNG_OPTIONAL_GET(trace_chunk->credentials).use_current_user ?
1017                                 NULL :
1018                                 &trace_chunk->credentials.value.user);
1019         if (ret) {
1020                 PERROR("Failed to rename folder \"%s\" to \"%s\"",
1021                                 directory_to_rename, archived_chunk_name);
1022         }
1023
1024 end:
1025         if (archived_chunks_directory.is_set) {
1026                 lttng_directory_handle_fini(&archived_chunks_directory.value);
1027         }
1028         free(archived_chunk_name);
1029         if (free_directory_to_rename) {
1030                 free(directory_to_rename);
1031         }
1032 }
1033
1034 LTTNG_HIDDEN
1035 enum lttng_trace_chunk_status lttng_trace_chunk_get_close_command(
1036                 struct lttng_trace_chunk *chunk,
1037                 enum lttng_trace_chunk_command_type *command_type)
1038 {
1039         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
1040
1041         pthread_mutex_lock(&chunk->lock);
1042         if (chunk->close_command.is_set) {
1043                 *command_type = chunk->close_command.value;
1044                 status = LTTNG_TRACE_CHUNK_STATUS_OK;
1045         } else {
1046                 status = LTTNG_TRACE_CHUNK_STATUS_NONE;
1047         }
1048         pthread_mutex_unlock(&chunk->lock);
1049         return status;
1050 }
1051
1052 LTTNG_HIDDEN
1053 enum lttng_trace_chunk_status lttng_trace_chunk_set_close_command(
1054                 struct lttng_trace_chunk *chunk,
1055                 enum lttng_trace_chunk_command_type close_command)
1056 {
1057         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
1058
1059         if (close_command < LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED ||
1060                         close_command >= LTTNG_TRACE_CHUNK_COMMAND_TYPE_MAX) {
1061                 status = LTTNG_TRACE_CHUNK_STATUS_INVALID_ARGUMENT;
1062                 goto end;
1063         }
1064
1065         pthread_mutex_lock(&chunk->lock);
1066         if (chunk->close_command.is_set) {
1067                 DBG("Overriding trace chunk close command from \"%s\" to \"%s\"",
1068                                 close_command_names[chunk->close_command.value],
1069                                 close_command_names[close_command]);
1070         } else {
1071                 DBG("Setting trace chunk close command to \"%s\"",
1072                                 close_command_names[close_command]);
1073         }
1074         LTTNG_OPTIONAL_SET(&chunk->close_command, close_command);
1075         pthread_mutex_unlock(&chunk->lock);
1076 end:
1077         return status;
1078 }
1079
1080 LTTNG_HIDDEN
1081 const char *lttng_trace_chunk_command_type_get_name(
1082                 enum lttng_trace_chunk_command_type command)
1083 {
1084         switch (command) {
1085         case LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED:
1086                 return "move to completed trace chunk folder";
1087         default:
1088                 abort();
1089         }
1090 }
1091
1092 LTTNG_HIDDEN
1093 bool lttng_trace_chunk_get(struct lttng_trace_chunk *chunk)
1094 {
1095         return urcu_ref_get_unless_zero(&chunk->ref);
1096 }
1097
1098 static
1099 void free_lttng_trace_chunk_registry_element(struct rcu_head *node)
1100 {
1101         struct lttng_trace_chunk_registry_element *element =
1102                         container_of(node, typeof(*element), rcu_node);
1103
1104         lttng_trace_chunk_fini(&element->chunk);
1105         free(element);
1106 }
1107
1108 static
1109 void lttng_trace_chunk_release(struct urcu_ref *ref)
1110 {
1111         struct lttng_trace_chunk *chunk = container_of(ref, typeof(*chunk),
1112                         ref);
1113
1114         if (chunk->close_command.is_set) {
1115                 close_command_funcs[chunk->close_command.value](chunk);
1116         }
1117
1118         if (chunk->in_registry_element) {
1119                 struct lttng_trace_chunk_registry_element *element;
1120
1121                 element = container_of(chunk, typeof(*element), chunk);
1122                 if (element->registry) {
1123                         rcu_read_lock();
1124                         cds_lfht_del(element->registry->ht,
1125                                         &element->trace_chunk_registry_ht_node);
1126                         rcu_read_unlock();
1127                         call_rcu(&element->rcu_node,
1128                                         free_lttng_trace_chunk_registry_element);
1129                 } else {
1130                         /* Never published, can be free'd immediately. */
1131                         free_lttng_trace_chunk_registry_element(
1132                                         &element->rcu_node);
1133                 }
1134         } else {
1135                 /* Not RCU-protected, free immediately. */
1136                 lttng_trace_chunk_fini(chunk);
1137                 free(chunk);
1138         }
1139 }
1140
1141 LTTNG_HIDDEN
1142 void lttng_trace_chunk_put(struct lttng_trace_chunk *chunk)
1143 {
1144         if (!chunk) {
1145                 return;
1146         }
1147         assert(chunk->ref.refcount);
1148         urcu_ref_put(&chunk->ref, lttng_trace_chunk_release);
1149 }
1150
1151 LTTNG_HIDDEN
1152 struct lttng_trace_chunk_registry *lttng_trace_chunk_registry_create(void)
1153 {
1154         struct lttng_trace_chunk_registry *registry;
1155
1156         registry = zmalloc(sizeof(*registry));
1157         if (!registry) {
1158                 goto end;
1159         }
1160
1161         registry->ht = cds_lfht_new(DEFAULT_HT_SIZE, 1, 0,
1162                         CDS_LFHT_AUTO_RESIZE | CDS_LFHT_ACCOUNTING, NULL);
1163         if (!registry->ht) {
1164                 goto error;
1165         }
1166 end:
1167         return registry;
1168 error:
1169         lttng_trace_chunk_registry_destroy(registry);
1170         return NULL;
1171 }
1172
1173 LTTNG_HIDDEN
1174 void lttng_trace_chunk_registry_destroy(
1175                 struct lttng_trace_chunk_registry *registry)
1176 {
1177         if (!registry) {
1178                 return;
1179         }
1180         if (registry->ht) {
1181                 int ret = cds_lfht_destroy(registry->ht, NULL);
1182                 assert(!ret);
1183         }
1184         free(registry);
1185 }
1186
1187 static
1188 struct lttng_trace_chunk_registry_element *
1189 lttng_trace_chunk_registry_element_create_from_chunk(
1190                 struct lttng_trace_chunk *chunk, uint64_t session_id)
1191 {
1192         struct lttng_trace_chunk_registry_element *element =
1193                         zmalloc(sizeof(*element));
1194
1195         if (!element) {
1196                 goto end;
1197         }
1198         cds_lfht_node_init(&element->trace_chunk_registry_ht_node);
1199         element->session_id = session_id;
1200
1201         element->chunk = *chunk;
1202         lttng_trace_chunk_init(&element->chunk);
1203         if (chunk->session_output_directory.is_set) {
1204                 element->chunk.session_output_directory.value =
1205                                 lttng_directory_handle_move(
1206                                         &chunk->session_output_directory.value);
1207         }
1208         if (chunk->chunk_directory.is_set) {
1209                 element->chunk.chunk_directory.value =
1210                                 lttng_directory_handle_move(
1211                                         &chunk->chunk_directory.value);
1212         }
1213         /*
1214          * The original chunk becomes invalid; the name attribute is transferred
1215          * to the new chunk instance.
1216          */
1217         chunk->name = NULL;
1218         element->chunk.in_registry_element = true;
1219 end:
1220         return element;
1221 }
1222
1223 LTTNG_HIDDEN
1224 struct lttng_trace_chunk *
1225 lttng_trace_chunk_registry_publish_chunk(
1226                 struct lttng_trace_chunk_registry *registry,
1227                 uint64_t session_id, struct lttng_trace_chunk *chunk)
1228 {
1229         struct lttng_trace_chunk_registry_element *element;
1230         unsigned long element_hash;
1231
1232         pthread_mutex_lock(&chunk->lock);
1233         element = lttng_trace_chunk_registry_element_create_from_chunk(chunk,
1234                         session_id);
1235         pthread_mutex_unlock(&chunk->lock);
1236         if (!element) {
1237                 goto end;
1238         }
1239         /*
1240          * chunk is now invalid, the only valid operation is a 'put' from the
1241          * caller.
1242          */
1243         chunk = NULL;
1244         element_hash = lttng_trace_chunk_registry_element_hash(element);
1245
1246         rcu_read_lock();
1247         while (1) {
1248                 struct cds_lfht_node *published_node;
1249                 struct lttng_trace_chunk *published_chunk;
1250                 struct lttng_trace_chunk_registry_element *published_element;
1251
1252                 published_node = cds_lfht_add_unique(registry->ht,
1253                                 element_hash,
1254                                 lttng_trace_chunk_registry_element_match,
1255                                 element,
1256                                 &element->trace_chunk_registry_ht_node);
1257                 if (published_node == &element->trace_chunk_registry_ht_node) {
1258                         /* Successfully published the new element. */
1259                         element->registry = registry;
1260                         /* Acquire a reference for the caller. */
1261                         if (lttng_trace_chunk_get(&element->chunk)) {
1262                                 break;
1263                         } else {
1264                                 /*
1265                                  * Another thread concurrently unpublished the
1266                                  * trace chunk. This is currently unexpected.
1267                                  *
1268                                  * Re-attempt to publish.
1269                                  */
1270                                 ERR("Attemp to publish a trace chunk to the chunk registry raced with a trace chunk deletion");
1271                                 continue;
1272                         }
1273                 }
1274
1275                 /*
1276                  * An equivalent trace chunk was published before this trace
1277                  * chunk. Attempt to acquire a reference to the one that was
1278                  * already published and release the reference to the copy we
1279                  * created if successful.
1280                  */
1281                 published_element = container_of(published_node,
1282                                 typeof(*published_element),
1283                                 trace_chunk_registry_ht_node);
1284                 published_chunk = &published_element->chunk;
1285                 if (lttng_trace_chunk_get(published_chunk)) {
1286                         lttng_trace_chunk_put(&element->chunk);
1287                         element = published_element;
1288                         break;
1289                 }
1290                 /*
1291                  * A reference to the previously published trace chunk could not
1292                  * be acquired. Hence, retry to publish our copy of the trace
1293                  * chunk.
1294                  */
1295         }
1296         rcu_read_unlock();
1297 end:
1298         return element ? &element->chunk : NULL;
1299 }
1300
1301 /*
1302  * Note that the caller must be registered as an RCU thread.
1303  * However, it does not need to hold the RCU read lock. The RCU read lock is
1304  * acquired to perform the look-up in the registry's hash table and held until
1305  * after a reference to the "found" trace chunk is acquired.
1306  *
1307  * IOW, holding a reference guarantees the existence of the object for the
1308  * caller.
1309  */
1310 static
1311 struct lttng_trace_chunk *_lttng_trace_chunk_registry_find_chunk(
1312                 const struct lttng_trace_chunk_registry *registry,
1313                 uint64_t session_id, uint64_t *chunk_id)
1314 {
1315         const struct lttng_trace_chunk_registry_element target_element = {
1316                 .chunk.id.is_set = !!chunk_id,
1317                 .chunk.id.value = chunk_id ? *chunk_id : 0,
1318                 .session_id = session_id,
1319         };
1320         const unsigned long element_hash =
1321                         lttng_trace_chunk_registry_element_hash(
1322                                 &target_element);
1323         struct cds_lfht_node *published_node;
1324         struct lttng_trace_chunk_registry_element *published_element;
1325         struct lttng_trace_chunk *published_chunk = NULL;
1326         struct cds_lfht_iter iter;
1327
1328         rcu_read_lock();
1329         cds_lfht_lookup(registry->ht,
1330                         element_hash,
1331                         lttng_trace_chunk_registry_element_match,
1332                         &target_element,
1333                         &iter);
1334         published_node = cds_lfht_iter_get_node(&iter);
1335         if (!published_node) {
1336                 goto end;
1337         }
1338
1339         published_element = container_of(published_node,
1340                         typeof(*published_element),
1341                         trace_chunk_registry_ht_node);
1342         if (lttng_trace_chunk_get(&published_element->chunk)) {
1343                 published_chunk = &published_element->chunk;
1344         }
1345 end:
1346         rcu_read_unlock();
1347         return published_chunk;
1348 }
1349
1350 LTTNG_HIDDEN
1351 struct lttng_trace_chunk *
1352 lttng_trace_chunk_registry_find_chunk(
1353                 const struct lttng_trace_chunk_registry *registry,
1354                 uint64_t session_id, uint64_t chunk_id)
1355 {
1356         return _lttng_trace_chunk_registry_find_chunk(registry,
1357                         session_id, &chunk_id);
1358 }
1359
1360 LTTNG_HIDDEN
1361 struct lttng_trace_chunk *
1362 lttng_trace_chunk_registry_find_anonymous_chunk(
1363                 const struct lttng_trace_chunk_registry *registry,
1364                 uint64_t session_id)
1365 {
1366         return _lttng_trace_chunk_registry_find_chunk(registry,
1367                         session_id, NULL);
1368 }
1369
1370 unsigned int lttng_trace_chunk_registry_put_each_chunk(
1371                 struct lttng_trace_chunk_registry *registry)
1372 {
1373         struct cds_lfht_iter iter;
1374         struct lttng_trace_chunk_registry_element *chunk_element;
1375         unsigned int trace_chunks_left = 0;
1376
1377         DBG("Releasing trace chunk registry to all trace chunks");
1378         rcu_read_lock();
1379         cds_lfht_for_each_entry(registry->ht,
1380                         &iter, chunk_element, trace_chunk_registry_ht_node) {
1381                 const char *chunk_id_str = "none";
1382                 char chunk_id_buf[MAX_INT_DEC_LEN(uint64_t)];
1383
1384                 pthread_mutex_lock(&chunk_element->chunk.lock);
1385                 if (chunk_element->chunk.id.is_set) {
1386                         int fmt_ret;
1387
1388                         fmt_ret = snprintf(chunk_id_buf, sizeof(chunk_id_buf),
1389                                         "%" PRIu64,
1390                                         chunk_element->chunk.id.value);
1391                         if (fmt_ret < 0 || fmt_ret >= sizeof(chunk_id_buf)) {
1392                                 chunk_id_str = "formatting error";
1393                         } else {
1394                                 chunk_id_str = chunk_id_buf;
1395                         }
1396                 }
1397
1398                 DBG("Releasing reference to trace chunk: session_id = %" PRIu64
1399                                 "chunk_id = %s, name = \"%s\", status = %s",
1400                                 chunk_element->session_id,
1401                                 chunk_id_str,
1402                                 chunk_element->chunk.name ? : "none",
1403                                 chunk_element->chunk.close_command.is_set ?
1404                                                 "open" : "closed");
1405                 pthread_mutex_unlock(&chunk_element->chunk.lock);
1406                 lttng_trace_chunk_put(&chunk_element->chunk);
1407                 trace_chunks_left++;
1408         }
1409         rcu_read_unlock();
1410         DBG("Released reference to %u trace chunks in %s()", trace_chunks_left,
1411                         __FUNCTION__);
1412
1413         return trace_chunks_left;
1414 }