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         struct lttng_directory_handle *session_output_directory;
  91         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) {
 225                 lttng_directory_handle_put(
 226                                 chunk->session_output_directory);
 227                 chunk->session_output_directory = NULL;
 228         }
 229         if (chunk->chunk_directory) {
 230                 lttng_directory_handle_put(chunk->chunk_directory);
 231                 chunk->chunk_directory = NULL;
 232         }
 233         free(chunk->name);
 234         chunk->name = NULL;
 235         lttng_dynamic_pointer_array_reset(&chunk->top_level_directories);
 236         pthread_mutex_destroy(&chunk->lock);
 237 }
 238
 239 static
 240 struct lttng_trace_chunk *lttng_trace_chunk_allocate(void)
 241 {
 242         struct lttng_trace_chunk *chunk = NULL;
 243
 244         chunk = zmalloc(sizeof(*chunk));
 245         if (!chunk) {
 246                 ERR("Failed to allocate trace chunk");
 247                 goto end;
 248         }
 249         lttng_trace_chunk_init(chunk);
 250 end:
 251         return chunk;
 252 }
 253
 254 LTTNG_HIDDEN
 255 struct lttng_trace_chunk *lttng_trace_chunk_create_anonymous(void)
 256 {
 257         DBG("Creating anonymous trace chunk");
 258         return lttng_trace_chunk_allocate();
 259 }
 260
 261 LTTNG_HIDDEN
 262 struct lttng_trace_chunk *lttng_trace_chunk_create(
 263                 uint64_t chunk_id, time_t chunk_creation_time)
 264 {
 265         struct lttng_trace_chunk *chunk;
 266         char chunk_creation_datetime_buf[16] = {};
 267         const char *chunk_creation_datetime_str = "(formatting error)";
 268         struct tm timeinfo_buf, *timeinfo;
 269
 270         timeinfo = localtime_r(&chunk_creation_time, &timeinfo_buf);
 271         if (timeinfo) {
 272                 size_t strftime_ret;
 273
 274                 /* Don't fail because of this; it is only used for logging. */
 275                 strftime_ret = strftime(chunk_creation_datetime_buf,
 276                                 sizeof(chunk_creation_datetime_buf),
 277                                 "%Y%m%d-%H%M%S", timeinfo);
 278                 if (strftime_ret) {
 279                         chunk_creation_datetime_str =
 280                                         chunk_creation_datetime_buf;
 281                 }
 282         }
 283
 284         DBG("Creating trace chunk: chunk_id = %" PRIu64 ", creation time = %s",
 285                         chunk_id, chunk_creation_datetime_str);
 286         chunk = lttng_trace_chunk_allocate();
 287         if (!chunk) {
 288                 goto end;
 289         }
 290
 291         LTTNG_OPTIONAL_SET(&chunk->id, chunk_id);
 292         LTTNG_OPTIONAL_SET(&chunk->timestamp_creation, chunk_creation_time);
 293         if (chunk_id != 0) {
 294                 chunk->name = generate_chunk_name(chunk_id,
 295                                 chunk_creation_time, NULL);
 296                 if (!chunk->name) {
 297                         ERR("Failed to allocate trace chunk name storage");
 298                         goto error;
 299                 }
 300         }
 301
 302         DBG("Chunk name set to \"%s\"", chunk->name ? : "(none)");
 303 end:
 304         return chunk;
 305 error:
 306         lttng_trace_chunk_put(chunk);
 307         return NULL;
 308 }
 309
 310 LTTNG_HIDDEN
 311 struct lttng_trace_chunk *lttng_trace_chunk_copy(
 312                 struct lttng_trace_chunk *source_chunk)
 313 {
 314         struct lttng_trace_chunk *new_chunk = lttng_trace_chunk_allocate();
 315
 316         if (!new_chunk) {
 317                 goto end;
 318         }
 319
 320         pthread_mutex_lock(&source_chunk->lock);
 321         /*
 322          * A new chunk is always a user; it shall create no new trace
 323          * subdirectories.
 324          */
 325         new_chunk->mode = (typeof(new_chunk->mode)) {
 326                 .is_set = true,
 327                 .value = TRACE_CHUNK_MODE_USER,
 328         };
 329         /*
 330          * top_level_directories is not copied as it is never used
 331          * by _user_ mode chunks.
 332          */
 333         /* The new chunk is not part of a registry (yet, at least). */
 334         new_chunk->in_registry_element = false;
 335         new_chunk->name_overridden = source_chunk->name_overridden;
 336         if (source_chunk->name) {
 337                 new_chunk->name = strdup(source_chunk->name);
 338                 if (!new_chunk->name) {
 339                         ERR("Failed to copy source trace chunk name in %s()",
 340                                         __FUNCTION__);
 341                         goto error_unlock;
 342                 }
 343         }
 344         new_chunk->id = source_chunk->id;
 345         new_chunk->timestamp_creation = source_chunk->timestamp_creation;
 346         new_chunk->timestamp_close = source_chunk->timestamp_close;
 347         new_chunk->credentials = source_chunk->credentials;
 348         if (source_chunk->session_output_directory) {
 349                 const bool reference_acquired = lttng_directory_handle_get(
 350                                 source_chunk->session_output_directory);
 351
 352                 assert(reference_acquired);
 353                 new_chunk->session_output_directory =
 354                                 source_chunk->session_output_directory;
 355         }
 356         if (source_chunk->chunk_directory) {
 357                 const bool reference_acquired = lttng_directory_handle_get(
 358                                 source_chunk->chunk_directory);
 359
 360                 assert(reference_acquired);
 361                 new_chunk->chunk_directory = source_chunk->chunk_directory;
 362         }
 363         new_chunk->close_command = source_chunk->close_command;
 364         pthread_mutex_unlock(&source_chunk->lock);
 365 end:
 366         return new_chunk;
 367 error_unlock:
 368         pthread_mutex_unlock(&source_chunk->lock);
 369         lttng_trace_chunk_put(new_chunk);
 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 = NULL;
 606         bool reference_acquired;
 607
 608         pthread_mutex_lock(&chunk->lock);
 609         if (chunk->mode.is_set) {
 610                 status = LTTNG_TRACE_CHUNK_STATUS_INVALID_OPERATION;
 611                 goto end;
 612         }
 613         if (!chunk->credentials.is_set) {
 614                 /*
 615                  * Fatal error, credentials must be set before a
 616                  * directory is created.
 617                  */
 618                 ERR("Credentials of trace chunk are unset: refusing to set session output directory");
 619                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 620                 goto end;
 621         }
 622
 623         if (chunk->name) {
 624                 /*
 625                  * A nameless chunk does not need its own output directory.
 626                  * The session's output directory will be used.
 627                  */
 628                 ret = lttng_directory_handle_create_subdirectory_as_user(
 629                                 session_output_directory,
 630                                 chunk->name,
 631                                 DIR_CREATION_MODE,
 632                                 !chunk->credentials.value.use_current_user ?
 633                                         &chunk->credentials.value.user : NULL);
 634                 if (ret) {
 635                         PERROR("Failed to create chunk output directory \"%s\"",
 636                                 chunk->name);
 637                         status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 638                         goto end;
 639                 }
 640         }
 641         chunk_directory_handle = lttng_directory_handle_create_from_handle(
 642                         chunk->name,
 643                         session_output_directory);
 644         if (!chunk_directory_handle) {
 645                 /* The function already logs on all error paths. */
 646                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 647                 goto end;
 648         }
 649         chunk->chunk_directory = chunk_directory_handle;
 650         chunk_directory_handle = NULL;
 651         reference_acquired = lttng_directory_handle_get(
 652                         session_output_directory);
 653         assert(reference_acquired);
 654         chunk->session_output_directory = session_output_directory;
 655         LTTNG_OPTIONAL_SET(&chunk->mode, TRACE_CHUNK_MODE_OWNER);
 656 end:
 657         pthread_mutex_unlock(&chunk->lock);
 658         return status;
 659 }
 660
 661 LTTNG_HIDDEN
 662 enum lttng_trace_chunk_status lttng_trace_chunk_set_as_user(
 663                 struct lttng_trace_chunk *chunk,
 664                 struct lttng_directory_handle *chunk_directory)
 665 {
 666         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 667         bool reference_acquired;
 668
 669         pthread_mutex_lock(&chunk->lock);
 670         if (chunk->mode.is_set) {
 671                 status = LTTNG_TRACE_CHUNK_STATUS_INVALID_OPERATION;
 672                 goto end;
 673         }
 674         if (!chunk->credentials.is_set) {
 675                 ERR("Credentials of trace chunk are unset: refusing to set chunk output directory");
 676                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 677                 goto end;
 678         }
 679         reference_acquired = lttng_directory_handle_get(chunk_directory);
 680         assert(reference_acquired);
 681         chunk->chunk_directory = chunk_directory;
 682         LTTNG_OPTIONAL_SET(&chunk->mode, TRACE_CHUNK_MODE_USER);
 683 end:
 684         pthread_mutex_unlock(&chunk->lock);
 685         return status;
 686 }
 687
 688 LTTNG_HIDDEN
 689 enum lttng_trace_chunk_status lttng_trace_chunk_borrow_chunk_directory_handle(
 690                 struct lttng_trace_chunk *chunk,
 691                 const struct lttng_directory_handle **handle)
 692 {
 693         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 694
 695         pthread_mutex_lock(&chunk->lock);
 696         if (!chunk->chunk_directory) {
 697                 status = LTTNG_TRACE_CHUNK_STATUS_NONE;
 698                 goto end;
 699         }
 700
 701         *handle = chunk->chunk_directory;
 702 end:
 703         pthread_mutex_unlock(&chunk->lock);
 704         return status;
 705 }
 706
 707 /* Add a top-level directory to the trace chunk if it was previously unknown. */
 708 static
 709 int add_top_level_directory_unique(struct lttng_trace_chunk *chunk,
 710                 const char *new_path)
 711 {
 712         int ret = 0;
 713         bool found = false;
 714         size_t i, count = lttng_dynamic_pointer_array_get_count(
 715                         &chunk->top_level_directories);
 716         const char *new_path_separator_pos = strchr(new_path, '/');
 717         const ptrdiff_t new_path_top_level_len = new_path_separator_pos ?
 718                         new_path_separator_pos - new_path : strlen(new_path);
 719
 720         for (i = 0; i < count; i++) {
 721                 const char *path = lttng_dynamic_pointer_array_get_pointer(
 722                                 &chunk->top_level_directories, i);
 723                 const ptrdiff_t path_top_level_len = strlen(path);
 724
 725                 if (path_top_level_len != new_path_top_level_len) {
 726                         continue;
 727                 }
 728                 if (!strncmp(path, new_path, path_top_level_len)) {
 729                         found = true;
 730                         break;
 731                 }
 732         }
 733
 734         if (!found) {
 735                 char *copy = lttng_strndup(new_path, new_path_top_level_len);
 736
 737                 DBG("Adding new top-level directory \"%s\" to trace chunk \"%s\"",
 738                                 new_path, chunk->name ? : "(unnamed)");
 739                 if (!copy) {
 740                         PERROR("Failed to copy path");
 741                         ret = -1;
 742                         goto end;
 743                 }
 744                 ret = lttng_dynamic_pointer_array_add_pointer(
 745                                 &chunk->top_level_directories, copy);
 746                 if (ret) {
 747                         ERR("Allocation failure while adding top-level directory entry to a trace chunk");
 748                         free(copy);
 749                         goto end;
 750                 }
 751         }
 752 end:
 753         return ret;
 754 }
 755
 756 LTTNG_HIDDEN
 757 enum lttng_trace_chunk_status lttng_trace_chunk_create_subdirectory(
 758                 struct lttng_trace_chunk *chunk,
 759                 const char *path)
 760 {
 761         int ret;
 762         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 763
 764         DBG("Creating trace chunk subdirectory \"%s\"", 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 create subdirectory \"%s\"",
 772                                 path);
 773                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 774                 goto end;
 775         }
 776         if (!chunk->mode.is_set ||
 777                         chunk->mode.value != TRACE_CHUNK_MODE_OWNER) {
 778                 ERR("Attempted to create trace chunk subdirectory \"%s\" through a non-owner chunk",
 779                                 path);
 780                 status = LTTNG_TRACE_CHUNK_STATUS_INVALID_OPERATION;
 781                 goto end;
 782         }
 783         if (!chunk->chunk_directory) {
 784                 ERR("Attempted to create trace chunk subdirectory \"%s\" before setting the chunk output directory",
 785                                 path);
 786                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 787                 goto end;
 788         }
 789         if (*path == '/') {
 790                 ERR("Refusing to create absolute trace chunk directory \"%s\"",
 791                                 path);
 792                 status = LTTNG_TRACE_CHUNK_STATUS_INVALID_ARGUMENT;
 793                 goto end;
 794         }
 795         ret = lttng_directory_handle_create_subdirectory_recursive_as_user(
 796                         chunk->chunk_directory, path,
 797                         DIR_CREATION_MODE,
 798                         chunk->credentials.value.use_current_user ?
 799                                         NULL : &chunk->credentials.value.user);
 800         if (ret) {
 801                 PERROR("Failed to create trace chunk subdirectory \"%s\"",
 802                                 path);
 803                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 804                 goto end;
 805         }
 806         ret = add_top_level_directory_unique(chunk, path);
 807         if (ret) {
 808                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 809                 goto end;
 810         }
 811 end:
 812         pthread_mutex_unlock(&chunk->lock);
 813         return status;
 814 }
 815
 816 LTTNG_HIDDEN
 817 enum lttng_trace_chunk_status lttng_trace_chunk_open_file(
 818                 struct lttng_trace_chunk *chunk, const char *file_path,
 819                 int flags, mode_t mode, int *out_fd)
 820 {
 821         int ret;
 822         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 823
 824         DBG("Opening trace chunk file \"%s\"", file_path);
 825         pthread_mutex_lock(&chunk->lock);
 826         if (!chunk->credentials.is_set) {
 827                 /*
 828                  * Fatal error, credentials must be set before a
 829                  * file is created.
 830                  */
 831                 ERR("Credentials of trace chunk are unset: refusing to open file \"%s\"",
 832                                 file_path);
 833                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 834                 goto end;
 835         }
 836         if (!chunk->chunk_directory) {
 837                 ERR("Attempted to open trace chunk file \"%s\" before setting the chunk output directory",
 838                                 file_path);
 839                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 840                 goto end;
 841         }
 842         ret = lttng_directory_handle_open_file_as_user(
 843                         chunk->chunk_directory, file_path, flags, mode,
 844                         chunk->credentials.value.use_current_user ?
 845                                         NULL : &chunk->credentials.value.user);
 846         if (ret < 0) {
 847                 PERROR("Failed to open file relative to trace chunk file_path = \"%s\", flags = %d, mode = %d",
 848                                 file_path, flags, (int) mode);
 849                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 850                 goto end;
 851         }
 852         *out_fd = ret;
 853 end:
 854         pthread_mutex_unlock(&chunk->lock);
 855         return status;
 856 }
 857
 858 LTTNG_HIDDEN
 859 int lttng_trace_chunk_unlink_file(struct lttng_trace_chunk *chunk,
 860                 const char *file_path)
 861 {
 862         int ret;
 863         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
 864
 865         DBG("Unlinking trace chunk file \"%s\"", file_path);
 866         pthread_mutex_lock(&chunk->lock);
 867         if (!chunk->credentials.is_set) {
 868                 /*
 869                  * Fatal error, credentials must be set before a
 870                  * directory is created.
 871                  */
 872                 ERR("Credentials of trace chunk are unset: refusing to unlink file \"%s\"",
 873                                 file_path);
 874                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 875                 goto end;
 876         }
 877         if (!chunk->chunk_directory) {
 878                 ERR("Attempted to unlink trace chunk file \"%s\" before setting the chunk output directory",
 879                                 file_path);
 880                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 881                 goto end;
 882         }
 883         ret = lttng_directory_handle_unlink_file_as_user(
 884                         chunk->chunk_directory, file_path,
 885                         chunk->credentials.value.use_current_user ?
 886                                         NULL : &chunk->credentials.value.user);
 887         if (ret < 0) {
 888                 status = LTTNG_TRACE_CHUNK_STATUS_ERROR;
 889                 goto end;
 890         }
 891 end:
 892         pthread_mutex_unlock(&chunk->lock);
 893         return status;
 894 }
 895
 896 static
 897 void lttng_trace_chunk_move_to_completed(struct lttng_trace_chunk *trace_chunk)
 898 {
 899         int ret;
 900         char *directory_to_rename = NULL;
 901         bool free_directory_to_rename = false;
 902         char *archived_chunk_name = NULL;
 903         const uint64_t chunk_id = LTTNG_OPTIONAL_GET(trace_chunk->id);
 904         const time_t creation_timestamp =
 905                         LTTNG_OPTIONAL_GET(trace_chunk->timestamp_creation);
 906         const time_t close_timestamp =
 907                         LTTNG_OPTIONAL_GET(trace_chunk->timestamp_close);
 908         struct lttng_directory_handle *archived_chunks_directory = NULL;
 909
 910         if (!trace_chunk->mode.is_set ||
 911                         trace_chunk->mode.value != TRACE_CHUNK_MODE_OWNER ||
 912                         !trace_chunk->session_output_directory) {
 913                 /*
 914                  * This command doesn't need to run if the output is remote
 915                  * or if the trace chunk is not owned by this process.
 916                  */
 917                 goto end;
 918         }
 919
 920         assert(trace_chunk->mode.value == TRACE_CHUNK_MODE_OWNER);
 921         assert(!trace_chunk->name_overridden);
 922
 923         /*
 924          * The fist trace chunk of a session is directly output to the
 925          * session's output folder. In this case, the top level directories
 926          * must be moved to a temporary folder before that temporary directory
 927          * is renamed to match the chunk's name.
 928          */
 929         if (chunk_id == 0) {
 930                 struct lttng_directory_handle *temporary_rename_directory =
 931                                 NULL;
 932                 size_t i, count = lttng_dynamic_pointer_array_get_count(
 933                                           &trace_chunk->top_level_directories);
 934
 935                 ret = lttng_directory_handle_create_subdirectory_as_user(
 936                                 trace_chunk->session_output_directory,
 937                                 DEFAULT_TEMPORARY_CHUNK_RENAME_DIRECTORY,
 938                                 DIR_CREATION_MODE,
 939                                 !trace_chunk->credentials.value.use_current_user ?
 940                                         &trace_chunk->credentials.value.user : NULL);
 941                 if (ret) {
 942                         PERROR("Failed to create temporary trace chunk rename directory \"%s\"",
 943                                         DEFAULT_TEMPORARY_CHUNK_RENAME_DIRECTORY);
 944                 }
 945
 946                 temporary_rename_directory = lttng_directory_handle_create_from_handle(
 947                                 DEFAULT_TEMPORARY_CHUNK_RENAME_DIRECTORY,
 948                                 trace_chunk->session_output_directory);
 949                 if (!temporary_rename_directory) {
 950                         ERR("Failed to get handle to temporary trace chunk rename directory");
 951                         goto end;
 952                 }
 953
 954                 for (i = 0; i < count; i++) {
 955                         const char *top_level_name =
 956                                         lttng_dynamic_pointer_array_get_pointer(
 957                                                 &trace_chunk->top_level_directories, i);
 958
 959                         ret = lttng_directory_handle_rename_as_user(
 960                                         trace_chunk->session_output_directory,
 961                                         top_level_name,
 962                                         temporary_rename_directory,
 963                                         top_level_name,
 964                                         LTTNG_OPTIONAL_GET(trace_chunk->credentials).use_current_user ?
 965                                                 NULL :
 966                                                 &trace_chunk->credentials.value.user);
 967                         if (ret) {
 968                                 PERROR("Failed to move \"%s\" to temporary trace chunk rename directory",
 969                                                 top_level_name);
 970                                 lttng_directory_handle_put(
 971                                                 temporary_rename_directory);
 972                                 goto end;
 973                         }
 974                 }
 975                 lttng_directory_handle_put(temporary_rename_directory);
 976                 directory_to_rename = DEFAULT_TEMPORARY_CHUNK_RENAME_DIRECTORY;
 977                 free_directory_to_rename = false;
 978         } else {
 979                 directory_to_rename = generate_chunk_name(chunk_id,
 980                                 creation_timestamp, NULL);
 981                 if (!directory_to_rename) {
 982                         ERR("Failed to generate initial trace chunk name while renaming trace chunk");
 983                         goto end;
 984                 }
 985                 free_directory_to_rename = true;
 986         }
 987
 988         archived_chunk_name = generate_chunk_name(chunk_id, creation_timestamp,
 989                         &close_timestamp);
 990         if (!archived_chunk_name) {
 991                 ERR("Failed to generate archived trace chunk name while renaming trace chunk");
 992                 goto end;
 993         }
 994
 995         ret = lttng_directory_handle_create_subdirectory_as_user(
 996                         trace_chunk->session_output_directory,
 997                         DEFAULT_ARCHIVED_TRACE_CHUNKS_DIRECTORY,
 998                         DIR_CREATION_MODE,
 999                         !trace_chunk->credentials.value.use_current_user ?
1000                                         &trace_chunk->credentials.value.user :
1001                                         NULL);
1002         if (ret) {
1003                 PERROR("Failed to create \"" DEFAULT_ARCHIVED_TRACE_CHUNKS_DIRECTORY
1004                                 "\" directory for archived trace chunks");
1005                 goto end;
1006         }
1007
1008         archived_chunks_directory = lttng_directory_handle_create_from_handle(
1009                         DEFAULT_ARCHIVED_TRACE_CHUNKS_DIRECTORY,
1010                         trace_chunk->session_output_directory);
1011         if (!archived_chunks_directory) {
1012                 PERROR("Failed to get handle to archived trace chunks directory");
1013                 goto end;
1014         }
1015
1016         ret = lttng_directory_handle_rename_as_user(
1017                         trace_chunk->session_output_directory,
1018                         directory_to_rename,
1019                         archived_chunks_directory,
1020                         archived_chunk_name,
1021                         LTTNG_OPTIONAL_GET(trace_chunk->credentials).use_current_user ?
1022                                 NULL :
1023                                 &trace_chunk->credentials.value.user);
1024         if (ret) {
1025                 PERROR("Failed to rename folder \"%s\" to \"%s\"",
1026                                 directory_to_rename, archived_chunk_name);
1027         }
1028
1029 end:
1030         lttng_directory_handle_put(archived_chunks_directory);
1031         free(archived_chunk_name);
1032         if (free_directory_to_rename) {
1033                 free(directory_to_rename);
1034         }
1035 }
1036
1037 LTTNG_HIDDEN
1038 enum lttng_trace_chunk_status lttng_trace_chunk_get_close_command(
1039                 struct lttng_trace_chunk *chunk,
1040                 enum lttng_trace_chunk_command_type *command_type)
1041 {
1042         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
1043
1044         pthread_mutex_lock(&chunk->lock);
1045         if (chunk->close_command.is_set) {
1046                 *command_type = chunk->close_command.value;
1047                 status = LTTNG_TRACE_CHUNK_STATUS_OK;
1048         } else {
1049                 status = LTTNG_TRACE_CHUNK_STATUS_NONE;
1050         }
1051         pthread_mutex_unlock(&chunk->lock);
1052         return status;
1053 }
1054
1055 LTTNG_HIDDEN
1056 enum lttng_trace_chunk_status lttng_trace_chunk_set_close_command(
1057                 struct lttng_trace_chunk *chunk,
1058                 enum lttng_trace_chunk_command_type close_command)
1059 {
1060         enum lttng_trace_chunk_status status = LTTNG_TRACE_CHUNK_STATUS_OK;
1061
1062         if (close_command < LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED ||
1063                         close_command >= LTTNG_TRACE_CHUNK_COMMAND_TYPE_MAX) {
1064                 status = LTTNG_TRACE_CHUNK_STATUS_INVALID_ARGUMENT;
1065                 goto end;
1066         }
1067
1068         pthread_mutex_lock(&chunk->lock);
1069         if (chunk->close_command.is_set) {
1070                 DBG("Overriding trace chunk close command from \"%s\" to \"%s\"",
1071                                 close_command_names[chunk->close_command.value],
1072                                 close_command_names[close_command]);
1073         } else {
1074                 DBG("Setting trace chunk close command to \"%s\"",
1075                                 close_command_names[close_command]);
1076         }
1077         LTTNG_OPTIONAL_SET(&chunk->close_command, close_command);
1078         pthread_mutex_unlock(&chunk->lock);
1079 end:
1080         return status;
1081 }
1082
1083 LTTNG_HIDDEN
1084 const char *lttng_trace_chunk_command_type_get_name(
1085                 enum lttng_trace_chunk_command_type command)
1086 {
1087         switch (command) {
1088         case LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED:
1089                 return "move to completed trace chunk folder";
1090         default:
1091                 abort();
1092         }
1093 }
1094
1095 LTTNG_HIDDEN
1096 bool lttng_trace_chunk_get(struct lttng_trace_chunk *chunk)
1097 {
1098         return urcu_ref_get_unless_zero(&chunk->ref);
1099 }
1100
1101 static
1102 void free_lttng_trace_chunk_registry_element(struct rcu_head *node)
1103 {
1104         struct lttng_trace_chunk_registry_element *element =
1105                         container_of(node, typeof(*element), rcu_node);
1106
1107         lttng_trace_chunk_fini(&element->chunk);
1108         free(element);
1109 }
1110
1111 static
1112 void lttng_trace_chunk_release(struct urcu_ref *ref)
1113 {
1114         struct lttng_trace_chunk *chunk = container_of(ref, typeof(*chunk),
1115                         ref);
1116
1117         if (chunk->close_command.is_set) {
1118                 close_command_funcs[chunk->close_command.value](chunk);
1119         }
1120
1121         if (chunk->in_registry_element) {
1122                 struct lttng_trace_chunk_registry_element *element;
1123
1124                 element = container_of(chunk, typeof(*element), chunk);
1125                 if (element->registry) {
1126                         rcu_read_lock();
1127                         cds_lfht_del(element->registry->ht,
1128                                         &element->trace_chunk_registry_ht_node);
1129                         rcu_read_unlock();
1130                         call_rcu(&element->rcu_node,
1131                                         free_lttng_trace_chunk_registry_element);
1132                 } else {
1133                         /* Never published, can be free'd immediately. */
1134                         free_lttng_trace_chunk_registry_element(
1135                                         &element->rcu_node);
1136                 }
1137         } else {
1138                 /* Not RCU-protected, free immediately. */
1139                 lttng_trace_chunk_fini(chunk);
1140                 free(chunk);
1141         }
1142 }
1143
1144 LTTNG_HIDDEN
1145 void lttng_trace_chunk_put(struct lttng_trace_chunk *chunk)
1146 {
1147         if (!chunk) {
1148                 return;
1149         }
1150         assert(chunk->ref.refcount);
1151         urcu_ref_put(&chunk->ref, lttng_trace_chunk_release);
1152 }
1153
1154 LTTNG_HIDDEN
1155 struct lttng_trace_chunk_registry *lttng_trace_chunk_registry_create(void)
1156 {
1157         struct lttng_trace_chunk_registry *registry;
1158
1159         registry = zmalloc(sizeof(*registry));
1160         if (!registry) {
1161                 goto end;
1162         }
1163
1164         registry->ht = cds_lfht_new(DEFAULT_HT_SIZE, 1, 0,
1165                         CDS_LFHT_AUTO_RESIZE | CDS_LFHT_ACCOUNTING, NULL);
1166         if (!registry->ht) {
1167                 goto error;
1168         }
1169 end:
1170         return registry;
1171 error:
1172         lttng_trace_chunk_registry_destroy(registry);
1173         return NULL;
1174 }
1175
1176 LTTNG_HIDDEN
1177 void lttng_trace_chunk_registry_destroy(
1178                 struct lttng_trace_chunk_registry *registry)
1179 {
1180         if (!registry) {
1181                 return;
1182         }
1183         if (registry->ht) {
1184                 int ret = cds_lfht_destroy(registry->ht, NULL);
1185                 assert(!ret);
1186         }
1187         free(registry);
1188 }
1189
1190 static
1191 struct lttng_trace_chunk_registry_element *
1192 lttng_trace_chunk_registry_element_create_from_chunk(
1193                 struct lttng_trace_chunk *chunk, uint64_t session_id)
1194 {
1195         struct lttng_trace_chunk_registry_element *element =
1196                         zmalloc(sizeof(*element));
1197
1198         if (!element) {
1199                 goto end;
1200         }
1201         cds_lfht_node_init(&element->trace_chunk_registry_ht_node);
1202         element->session_id = session_id;
1203
1204         element->chunk = *chunk;
1205         lttng_trace_chunk_init(&element->chunk);
1206         if (chunk->session_output_directory) {
1207                 /* Transferred ownership. */
1208                 element->chunk.session_output_directory =
1209                                 chunk->session_output_directory;
1210                 chunk->session_output_directory = NULL;
1211         }
1212         if (chunk->chunk_directory) {
1213                 /* Transferred ownership. */
1214                 element->chunk.chunk_directory = chunk->chunk_directory;
1215                 chunk->chunk_directory = NULL;
1216         }
1217         /*
1218          * The original chunk becomes invalid; the name attribute is transferred
1219          * to the new chunk instance.
1220          */
1221         chunk->name = NULL;
1222         element->chunk.in_registry_element = true;
1223 end:
1224         return element;
1225 }
1226
1227 LTTNG_HIDDEN
1228 struct lttng_trace_chunk *
1229 lttng_trace_chunk_registry_publish_chunk(
1230                 struct lttng_trace_chunk_registry *registry,
1231                 uint64_t session_id, struct lttng_trace_chunk *chunk)
1232 {
1233         struct lttng_trace_chunk_registry_element *element;
1234         unsigned long element_hash;
1235
1236         pthread_mutex_lock(&chunk->lock);
1237         element = lttng_trace_chunk_registry_element_create_from_chunk(chunk,
1238                         session_id);
1239         pthread_mutex_unlock(&chunk->lock);
1240         if (!element) {
1241                 goto end;
1242         }
1243         /*
1244          * chunk is now invalid, the only valid operation is a 'put' from the
1245          * caller.
1246          */
1247         chunk = NULL;
1248         element_hash = lttng_trace_chunk_registry_element_hash(element);
1249
1250         rcu_read_lock();
1251         while (1) {
1252                 struct cds_lfht_node *published_node;
1253                 struct lttng_trace_chunk *published_chunk;
1254                 struct lttng_trace_chunk_registry_element *published_element;
1255
1256                 published_node = cds_lfht_add_unique(registry->ht,
1257                                 element_hash,
1258                                 lttng_trace_chunk_registry_element_match,
1259                                 element,
1260                                 &element->trace_chunk_registry_ht_node);
1261                 if (published_node == &element->trace_chunk_registry_ht_node) {
1262                         /* Successfully published the new element. */
1263                         element->registry = registry;
1264                         /* Acquire a reference for the caller. */
1265                         if (lttng_trace_chunk_get(&element->chunk)) {
1266                                 break;
1267                         } else {
1268                                 /*
1269                                  * Another thread concurrently unpublished the
1270                                  * trace chunk. This is currently unexpected.
1271                                  *
1272                                  * Re-attempt to publish.
1273                                  */
1274                                 ERR("Attempt to publish a trace chunk to the chunk registry raced with a trace chunk deletion");
1275                                 continue;
1276                         }
1277                 }
1278
1279                 /*
1280                  * An equivalent trace chunk was published before this trace
1281                  * chunk. Attempt to acquire a reference to the one that was
1282                  * already published and release the reference to the copy we
1283                  * created if successful.
1284                  */
1285                 published_element = container_of(published_node,
1286                                 typeof(*published_element),
1287                                 trace_chunk_registry_ht_node);
1288                 published_chunk = &published_element->chunk;
1289                 if (lttng_trace_chunk_get(published_chunk)) {
1290                         lttng_trace_chunk_put(&element->chunk);
1291                         element = published_element;
1292                         break;
1293                 }
1294                 /*
1295                  * A reference to the previously published trace chunk could not
1296                  * be acquired. Hence, retry to publish our copy of the trace
1297                  * chunk.
1298                  */
1299         }
1300         rcu_read_unlock();
1301 end:
1302         return element ? &element->chunk : NULL;
1303 }
1304
1305 /*
1306  * Note that the caller must be registered as an RCU thread.
1307  * However, it does not need to hold the RCU read lock. The RCU read lock is
1308  * acquired to perform the look-up in the registry's hash table and held until
1309  * after a reference to the "found" trace chunk is acquired.
1310  *
1311  * IOW, holding a reference guarantees the existence of the object for the
1312  * caller.
1313  */
1314 static
1315 struct lttng_trace_chunk *_lttng_trace_chunk_registry_find_chunk(
1316                 const struct lttng_trace_chunk_registry *registry,
1317                 uint64_t session_id, uint64_t *chunk_id)
1318 {
1319         const struct lttng_trace_chunk_registry_element target_element = {
1320                 .chunk.id.is_set = !!chunk_id,
1321                 .chunk.id.value = chunk_id ? *chunk_id : 0,
1322                 .session_id = session_id,
1323         };
1324         const unsigned long element_hash =
1325                         lttng_trace_chunk_registry_element_hash(
1326                                 &target_element);
1327         struct cds_lfht_node *published_node;
1328         struct lttng_trace_chunk_registry_element *published_element;
1329         struct lttng_trace_chunk *published_chunk = NULL;
1330         struct cds_lfht_iter iter;
1331
1332         rcu_read_lock();
1333         cds_lfht_lookup(registry->ht,
1334                         element_hash,
1335                         lttng_trace_chunk_registry_element_match,
1336                         &target_element,
1337                         &iter);
1338         published_node = cds_lfht_iter_get_node(&iter);
1339         if (!published_node) {
1340                 goto end;
1341         }
1342
1343         published_element = container_of(published_node,
1344                         typeof(*published_element),
1345                         trace_chunk_registry_ht_node);
1346         if (lttng_trace_chunk_get(&published_element->chunk)) {
1347                 published_chunk = &published_element->chunk;
1348         }
1349 end:
1350         rcu_read_unlock();
1351         return published_chunk;
1352 }
1353
1354 LTTNG_HIDDEN
1355 struct lttng_trace_chunk *
1356 lttng_trace_chunk_registry_find_chunk(
1357                 const struct lttng_trace_chunk_registry *registry,
1358                 uint64_t session_id, uint64_t chunk_id)
1359 {
1360         return _lttng_trace_chunk_registry_find_chunk(registry,
1361                         session_id, &chunk_id);
1362 }
1363
1364 LTTNG_HIDDEN
1365 int lttng_trace_chunk_registry_chunk_exists(
1366                 const struct lttng_trace_chunk_registry *registry,
1367                 uint64_t session_id, uint64_t chunk_id, bool *chunk_exists)
1368 {
1369         int ret = 0;
1370         const struct lttng_trace_chunk_registry_element target_element = {
1371                 .chunk.id.is_set = true,
1372                 .chunk.id.value = chunk_id,
1373                 .session_id = session_id,
1374         };
1375         const unsigned long element_hash =
1376                         lttng_trace_chunk_registry_element_hash(
1377                                 &target_element);
1378         struct cds_lfht_node *published_node;
1379         struct cds_lfht_iter iter;
1380
1381         rcu_read_lock();
1382         cds_lfht_lookup(registry->ht,
1383                         element_hash,
1384                         lttng_trace_chunk_registry_element_match,
1385                         &target_element,
1386                         &iter);
1387         published_node = cds_lfht_iter_get_node(&iter);
1388         if (!published_node) {
1389                 *chunk_exists = false;
1390                 goto end;
1391         }
1392
1393         *chunk_exists = !cds_lfht_is_node_deleted(published_node);
1394 end:
1395         rcu_read_unlock();
1396         return ret;
1397 }
1398
1399 LTTNG_HIDDEN
1400 struct lttng_trace_chunk *
1401 lttng_trace_chunk_registry_find_anonymous_chunk(
1402                 const struct lttng_trace_chunk_registry *registry,
1403                 uint64_t session_id)
1404 {
1405         return _lttng_trace_chunk_registry_find_chunk(registry,
1406                         session_id, NULL);
1407 }
1408
1409 unsigned int lttng_trace_chunk_registry_put_each_chunk(
1410                 struct lttng_trace_chunk_registry *registry)
1411 {
1412         struct cds_lfht_iter iter;
1413         struct lttng_trace_chunk_registry_element *chunk_element;
1414         unsigned int trace_chunks_left = 0;
1415
1416         DBG("Releasing trace chunk registry to all trace chunks");
1417         rcu_read_lock();
1418         cds_lfht_for_each_entry(registry->ht,
1419                         &iter, chunk_element, trace_chunk_registry_ht_node) {
1420                 const char *chunk_id_str = "none";
1421                 char chunk_id_buf[MAX_INT_DEC_LEN(uint64_t)];
1422
1423                 pthread_mutex_lock(&chunk_element->chunk.lock);
1424                 if (chunk_element->chunk.id.is_set) {
1425                         int fmt_ret;
1426
1427                         fmt_ret = snprintf(chunk_id_buf, sizeof(chunk_id_buf),
1428                                         "%" PRIu64,
1429                                         chunk_element->chunk.id.value);
1430                         if (fmt_ret < 0 || fmt_ret >= sizeof(chunk_id_buf)) {
1431                                 chunk_id_str = "formatting error";
1432                         } else {
1433                                 chunk_id_str = chunk_id_buf;
1434                         }
1435                 }
1436
1437                 DBG("Releasing reference to trace chunk: session_id = %" PRIu64
1438                                 "chunk_id = %s, name = \"%s\", status = %s",
1439                                 chunk_element->session_id,
1440                                 chunk_id_str,
1441                                 chunk_element->chunk.name ? : "none",
1442                                 chunk_element->chunk.close_command.is_set ?
1443                                                 "open" : "closed");
1444                 pthread_mutex_unlock(&chunk_element->chunk.lock);
1445                 lttng_trace_chunk_put(&chunk_element->chunk);
1446                 trace_chunks_left++;
1447         }
1448         rcu_read_unlock();
1449         DBG("Released reference to %u trace chunks in %s()", trace_chunks_left,
1450                         __FUNCTION__);
1451
1452         return trace_chunks_left;
1453 }