src/bin/lttng-sessiond/session.c

   1 /*
   2  * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
   3  *
   4  * SPDX-License-Identifier: GPL-2.0-only
   5  *
   6  */
   7
   8 #define _LGPL_SOURCE
   9 #include <limits.h>
  10 #include <inttypes.h>
  11 #include <stdio.h>
  12 #include <stdlib.h>
  13 #include <string.h>
  14 #include <sys/stat.h>
  15 #include <urcu.h>
  16 #include <dirent.h>
  17 #include <sys/types.h>
  18 #include <pthread.h>
  19
  20 #include <common/common.h>
  21 #include <common/utils.h>
  22 #include <common/trace-chunk.h>
  23 #include <common/sessiond-comm/sessiond-comm.h>
  24 #include <lttng/location-internal.h>
  25 #include "lttng-sessiond.h"
  26 #include "kernel.h"
  27
  28 #include "session.h"
  29 #include "utils.h"
  30 #include "trace-ust.h"
  31 #include "timer.h"
  32 #include "cmd.h"
  33
  34 struct ltt_session_destroy_notifier_element {
  35         ltt_session_destroy_notifier notifier;
  36         void *user_data;
  37 };
  38
  39 struct ltt_session_clear_notifier_element {
  40         ltt_session_clear_notifier notifier;
  41         void *user_data;
  42 };
  43
  44 /*
  45  * NOTES:
  46  *
  47  * No ltt_session.lock is taken here because those data structure are widely
  48  * spread across the lttng-tools code base so before caling functions below
  49  * that can read/write a session, the caller MUST acquire the session lock
  50  * using session_lock() and session_unlock().
  51  */
  52
  53 /*
  54  * Init tracing session list.
  55  *
  56  * Please see session.h for more explanation and correct usage of the list.
  57  */
  58 static struct ltt_session_list ltt_session_list = {
  59         .head = CDS_LIST_HEAD_INIT(ltt_session_list.head),
  60         .lock = PTHREAD_MUTEX_INITIALIZER,
  61         .removal_cond = PTHREAD_COND_INITIALIZER,
  62         .next_uuid = 0,
  63 };
  64
  65 /* These characters are forbidden in a session name. Used by validate_name. */
  66 static const char *forbidden_name_chars = "/";
  67
  68 /* Global hash table to keep the sessions, indexed by id. */
  69 static struct lttng_ht *ltt_sessions_ht_by_id = NULL;
  70
  71 /*
  72  * Validate the session name for forbidden characters.
  73  *
  74  * Return 0 on success else -1 meaning a forbidden char. has been found.
  75  */
  76 static int validate_name(const char *name)
  77 {
  78         int ret;
  79         char *tok, *tmp_name;
  80
  81         assert(name);
  82
  83         tmp_name = strdup(name);
  84         if (!tmp_name) {
  85                 /* ENOMEM here. */
  86                 ret = -1;
  87                 goto error;
  88         }
  89
  90         tok = strpbrk(tmp_name, forbidden_name_chars);
  91         if (tok) {
  92                 DBG("Session name %s contains a forbidden character", name);
  93                 /* Forbidden character has been found. */
  94                 ret = -1;
  95                 goto error;
  96         }
  97         ret = 0;
  98
  99 error:
 100         free(tmp_name);
 101         return ret;
 102 }
 103
 104 /*
 105  * Add a ltt_session structure to the global list.
 106  *
 107  * The caller MUST acquire the session list lock before.
 108  * Returns the unique identifier for the session.
 109  */
 110 static uint64_t add_session_list(struct ltt_session *ls)
 111 {
 112         assert(ls);
 113
 114         cds_list_add(&ls->list, &ltt_session_list.head);
 115         return ltt_session_list.next_uuid++;
 116 }
 117
 118 /*
 119  * Delete a ltt_session structure to the global list.
 120  *
 121  * The caller MUST acquire the session list lock before.
 122  */
 123 static void del_session_list(struct ltt_session *ls)
 124 {
 125         assert(ls);
 126
 127         cds_list_del(&ls->list);
 128 }
 129
 130 /*
 131  * Return a pointer to the session list.
 132  */
 133 struct ltt_session_list *session_get_list(void)
 134 {
 135         return &ltt_session_list;
 136 }
 137
 138 /*
 139  * Returns once the session list is empty.
 140  */
 141 void session_list_wait_empty(void)
 142 {
 143         pthread_mutex_lock(&ltt_session_list.lock);
 144         while (!cds_list_empty(&ltt_session_list.head)) {
 145                 pthread_cond_wait(&ltt_session_list.removal_cond,
 146                                 &ltt_session_list.lock);
 147         }
 148         pthread_mutex_unlock(&ltt_session_list.lock);
 149 }
 150
 151 /*
 152  * Acquire session list lock
 153  */
 154 void session_lock_list(void)
 155 {
 156         pthread_mutex_lock(&ltt_session_list.lock);
 157 }
 158
 159 /*
 160  * Try to acquire session list lock
 161  */
 162 int session_trylock_list(void)
 163 {
 164         return pthread_mutex_trylock(&ltt_session_list.lock);
 165 }
 166
 167 /*
 168  * Release session list lock
 169  */
 170 void session_unlock_list(void)
 171 {
 172         pthread_mutex_unlock(&ltt_session_list.lock);
 173 }
 174
 175 /*
 176  * Get the session's consumer destination type.
 177  *
 178  * The caller must hold the session lock.
 179  */
 180 enum consumer_dst_type session_get_consumer_destination_type(
 181                 const struct ltt_session *session)
 182 {
 183         /*
 184          * The output information is duplicated in both of those session types.
 185          * Hence, it doesn't matter from which it is retrieved. However, it is
 186          * possible for only one of them to be set.
 187          */
 188         return session->kernel_session ?
 189                         session->kernel_session->consumer->type :
 190                         session->ust_session->consumer->type;
 191 }
 192
 193 /*
 194  * Get the session's consumer network hostname.
 195  * The caller must ensure that the destination is of type "net".
 196  *
 197  * The caller must hold the session lock.
 198  */
 199 const char *session_get_net_consumer_hostname(const struct ltt_session *session)
 200 {
 201         const char *hostname = NULL;
 202         const struct consumer_output *output;
 203
 204         output = session->kernel_session ?
 205                         session->kernel_session->consumer :
 206                         session->ust_session->consumer;
 207
 208         /*
 209          * hostname is assumed to be the same for both control and data
 210          * connections.
 211          */
 212         switch (output->dst.net.control.dtype) {
 213         case LTTNG_DST_IPV4:
 214                 hostname = output->dst.net.control.dst.ipv4;
 215                 break;
 216         case LTTNG_DST_IPV6:
 217                 hostname = output->dst.net.control.dst.ipv6;
 218                 break;
 219         default:
 220                 abort();
 221         }
 222         return hostname;
 223 }
 224
 225 /*
 226  * Get the session's consumer network control and data ports.
 227  * The caller must ensure that the destination is of type "net".
 228  *
 229  * The caller must hold the session lock.
 230  */
 231 void session_get_net_consumer_ports(const struct ltt_session *session,
 232                 uint16_t *control_port, uint16_t *data_port)
 233 {
 234         const struct consumer_output *output;
 235
 236         output = session->kernel_session ?
 237                         session->kernel_session->consumer :
 238                         session->ust_session->consumer;
 239         *control_port = output->dst.net.control.port;
 240         *data_port = output->dst.net.data.port;
 241 }
 242
 243 /*
 244  * Get the location of the latest trace archive produced by a rotation.
 245  *
 246  * The caller must hold the session lock.
 247  */
 248 struct lttng_trace_archive_location *session_get_trace_archive_location(
 249                 const struct ltt_session *session)
 250 {
 251         int ret;
 252         struct lttng_trace_archive_location *location = NULL;
 253         char *chunk_path = NULL;
 254
 255         if (session->rotation_state != LTTNG_ROTATION_STATE_COMPLETED ||
 256                         !session->last_archived_chunk_name) {
 257                 goto end;
 258         }
 259
 260         switch (session_get_consumer_destination_type(session)) {
 261         case CONSUMER_DST_LOCAL:
 262                 ret = asprintf(&chunk_path,
 263                                 "%s/" DEFAULT_ARCHIVED_TRACE_CHUNKS_DIRECTORY "/%s",
 264                                 session_get_base_path(session),
 265                                 session->last_archived_chunk_name);
 266                 if (ret == -1) {
 267                         goto end;
 268                 }
 269                 location = lttng_trace_archive_location_local_create(
 270                                 chunk_path);
 271                 break;
 272         case CONSUMER_DST_NET:
 273         {
 274                 const char *hostname;
 275                 uint16_t control_port, data_port;
 276
 277                 hostname = session_get_net_consumer_hostname(session);
 278                 session_get_net_consumer_ports(session,
 279                                 &control_port,
 280                                 &data_port);
 281                 location = lttng_trace_archive_location_relay_create(
 282                                 hostname,
 283                                 LTTNG_TRACE_ARCHIVE_LOCATION_RELAY_PROTOCOL_TYPE_TCP,
 284                                 control_port, data_port, session->last_chunk_path);
 285                 break;
 286         }
 287         default:
 288                 abort();
 289         }
 290 end:
 291         free(chunk_path);
 292         return location;
 293 }
 294
 295 /*
 296  * Allocate the ltt_sessions_ht_by_id HT.
 297  *
 298  * The session list lock must be held.
 299  */
 300 static int ltt_sessions_ht_alloc(void)
 301 {
 302         int ret = 0;
 303
 304         DBG("Allocating ltt_sessions_ht_by_id");
 305         ltt_sessions_ht_by_id = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
 306         if (!ltt_sessions_ht_by_id) {
 307                 ret = -1;
 308                 ERR("Failed to allocate ltt_sessions_ht_by_id");
 309                 goto end;
 310         }
 311 end:
 312         return ret;
 313 }
 314
 315 /*
 316  * Destroy the ltt_sessions_ht_by_id HT.
 317  *
 318  * The session list lock must be held.
 319  */
 320 static void ltt_sessions_ht_destroy(void)
 321 {
 322         if (!ltt_sessions_ht_by_id) {
 323                 return;
 324         }
 325         ht_cleanup_push(ltt_sessions_ht_by_id);
 326         ltt_sessions_ht_by_id = NULL;
 327 }
 328
 329 /*
 330  * Add a ltt_session to the ltt_sessions_ht_by_id.
 331  * If unallocated, the ltt_sessions_ht_by_id HT is allocated.
 332  * The session list lock must be held.
 333  */
 334 static void add_session_ht(struct ltt_session *ls)
 335 {
 336         int ret;
 337
 338         assert(ls);
 339
 340         if (!ltt_sessions_ht_by_id) {
 341                 ret = ltt_sessions_ht_alloc();
 342                 if (ret) {
 343                         ERR("Error allocating the sessions HT");
 344                         goto end;
 345                 }
 346         }
 347         lttng_ht_node_init_u64(&ls->node, ls->id);
 348         lttng_ht_add_unique_u64(ltt_sessions_ht_by_id, &ls->node);
 349
 350 end:
 351         return;
 352 }
 353
 354 /*
 355  * Test if ltt_sessions_ht_by_id is empty.
 356  * Return 1 if empty, 0 if not empty.
 357  * The session list lock must be held.
 358  */
 359 static int ltt_sessions_ht_empty(void)
 360 {
 361         int ret;
 362
 363         if (!ltt_sessions_ht_by_id) {
 364                 ret = 1;
 365                 goto end;
 366         }
 367
 368         ret = lttng_ht_get_count(ltt_sessions_ht_by_id) ? 0 : 1;
 369 end:
 370         return ret;
 371 }
 372
 373 /*
 374  * Remove a ltt_session from the ltt_sessions_ht_by_id.
 375  * If empty, the ltt_sessions_ht_by_id HT is freed.
 376  * The session list lock must be held.
 377  */
 378 static void del_session_ht(struct ltt_session *ls)
 379 {
 380         struct lttng_ht_iter iter;
 381         int ret;
 382
 383         assert(ls);
 384         assert(ltt_sessions_ht_by_id);
 385
 386         iter.iter.node = &ls->node.node;
 387         ret = lttng_ht_del(ltt_sessions_ht_by_id, &iter);
 388         assert(!ret);
 389
 390         if (ltt_sessions_ht_empty()) {
 391                 DBG("Empty ltt_sessions_ht_by_id, destroying it");
 392                 ltt_sessions_ht_destroy();
 393         }
 394 }
 395
 396 /*
 397  * Acquire session lock
 398  */
 399 void session_lock(struct ltt_session *session)
 400 {
 401         assert(session);
 402
 403         pthread_mutex_lock(&session->lock);
 404 }
 405
 406 /*
 407  * Release session lock
 408  */
 409 void session_unlock(struct ltt_session *session)
 410 {
 411         assert(session);
 412
 413         pthread_mutex_unlock(&session->lock);
 414 }
 415
 416 static
 417 int _session_set_trace_chunk_no_lock_check(struct ltt_session *session,
 418                 struct lttng_trace_chunk *new_trace_chunk,
 419                 struct lttng_trace_chunk **_current_trace_chunk)
 420 {
 421         int ret = 0;
 422         unsigned int i, refs_to_acquire = 0, refs_acquired = 0, refs_to_release = 0;
 423         struct cds_lfht_iter iter;
 424         struct consumer_socket *socket;
 425         struct lttng_trace_chunk *current_trace_chunk;
 426         uint64_t chunk_id;
 427         enum lttng_trace_chunk_status chunk_status;
 428
 429         rcu_read_lock();
 430         /*
 431          * Ownership of current trace chunk is transferred to
 432          * `current_trace_chunk`.
 433          */
 434         current_trace_chunk = session->current_trace_chunk;
 435         session->current_trace_chunk = NULL;
 436         if (session->ust_session) {
 437                 lttng_trace_chunk_put(
 438                                 session->ust_session->current_trace_chunk);
 439                 session->ust_session->current_trace_chunk = NULL;
 440         }
 441         if (session->kernel_session) {
 442                 lttng_trace_chunk_put(
 443                                 session->kernel_session->current_trace_chunk);
 444                 session->kernel_session->current_trace_chunk = NULL;
 445         }
 446         if (!new_trace_chunk) {
 447                 ret = 0;
 448                 goto end;
 449         }
 450         chunk_status = lttng_trace_chunk_get_id(new_trace_chunk, &chunk_id);
 451         assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
 452
 453         refs_to_acquire = 1;
 454         refs_to_acquire += !!session->ust_session;
 455         refs_to_acquire += !!session->kernel_session;
 456
 457         for (refs_acquired = 0; refs_acquired < refs_to_acquire;
 458                         refs_acquired++) {
 459                 if (!lttng_trace_chunk_get(new_trace_chunk)) {
 460                         ERR("Failed to acquire reference to new trace chunk of session \"%s\"",
 461                                         session->name);
 462                         goto error;
 463                 }
 464         }
 465
 466         if (session->ust_session) {
 467                 const uint64_t relayd_id =
 468                                 session->ust_session->consumer->net_seq_index;
 469                 const bool is_local_trace =
 470                                 session->ust_session->consumer->type ==
 471                                 CONSUMER_DST_LOCAL;
 472
 473                 session->ust_session->current_trace_chunk = new_trace_chunk;
 474                 if (is_local_trace) {
 475                         enum lttng_error_code ret_error_code;
 476
 477                         ret_error_code = ust_app_create_channel_subdirectories(
 478                                         session->ust_session);
 479                         if (ret_error_code != LTTNG_OK) {
 480                                 goto error;
 481                         }
 482                 }
 483                 cds_lfht_for_each_entry(
 484                                 session->ust_session->consumer->socks->ht,
 485                                 &iter, socket, node.node) {
 486                         pthread_mutex_lock(socket->lock);
 487                         ret = consumer_create_trace_chunk(socket,
 488                                         relayd_id,
 489                                         session->id, new_trace_chunk,
 490                                         DEFAULT_UST_TRACE_DIR);
 491                         pthread_mutex_unlock(socket->lock);
 492                         if (ret) {
 493                                 goto error;
 494                         }
 495                 }
 496         }
 497         if (session->kernel_session) {
 498                 const uint64_t relayd_id =
 499                                 session->kernel_session->consumer->net_seq_index;
 500                 const bool is_local_trace =
 501                                 session->kernel_session->consumer->type ==
 502                                 CONSUMER_DST_LOCAL;
 503
 504                 session->kernel_session->current_trace_chunk = new_trace_chunk;
 505                 if (is_local_trace) {
 506                         enum lttng_error_code ret_error_code;
 507
 508                         ret_error_code = kernel_create_channel_subdirectories(
 509                                         session->kernel_session);
 510                         if (ret_error_code != LTTNG_OK) {
 511                                 goto error;
 512                         }
 513                 }
 514                 cds_lfht_for_each_entry(
 515                                 session->kernel_session->consumer->socks->ht,
 516                                 &iter, socket, node.node) {
 517                         pthread_mutex_lock(socket->lock);
 518                         ret = consumer_create_trace_chunk(socket,
 519                                         relayd_id,
 520                                         session->id, new_trace_chunk,
 521                                         DEFAULT_KERNEL_TRACE_DIR);
 522                         pthread_mutex_unlock(socket->lock);
 523                         if (ret) {
 524                                 goto error;
 525                         }
 526                 }
 527         }
 528
 529         /*
 530          * Update local current trace chunk state last, only if all remote
 531          * creations succeeded.
 532          */
 533         session->current_trace_chunk = new_trace_chunk;
 534         LTTNG_OPTIONAL_SET(&session->most_recent_chunk_id, chunk_id);
 535 end:
 536         if (_current_trace_chunk) {
 537                 *_current_trace_chunk = current_trace_chunk;
 538                 current_trace_chunk = NULL;
 539         }
 540 end_no_move:
 541         rcu_read_unlock();
 542         lttng_trace_chunk_put(current_trace_chunk);
 543         return ret;
 544 error:
 545         if (session->ust_session) {
 546                 session->ust_session->current_trace_chunk = NULL;
 547         }
 548         if (session->kernel_session) {
 549                 session->kernel_session->current_trace_chunk = NULL;
 550         }
 551         /*
 552          * Release references taken in the case where all references could not
 553          * be acquired.
 554          */
 555         refs_to_release = refs_to_acquire - refs_acquired;
 556         for (i = 0; i < refs_to_release; i++) {
 557                 lttng_trace_chunk_put(new_trace_chunk);
 558         }
 559         ret = -1;
 560         goto end_no_move;
 561 }
 562
 563 struct lttng_trace_chunk *session_create_new_trace_chunk(
 564                 const struct ltt_session *session,
 565                 const struct consumer_output *consumer_output_override,
 566                 const char *session_base_path_override,
 567                 const char *chunk_name_override)
 568 {
 569         int ret;
 570         struct lttng_trace_chunk *trace_chunk = NULL;
 571         enum lttng_trace_chunk_status chunk_status;
 572         const time_t chunk_creation_ts = time(NULL);
 573         bool is_local_trace;
 574         const char *base_path;
 575         struct lttng_directory_handle *session_output_directory = NULL;
 576         const struct lttng_credentials session_credentials = {
 577                 .uid = LTTNG_OPTIONAL_INIT_VALUE(session->uid),
 578                 .gid = LTTNG_OPTIONAL_INIT_VALUE(session->gid),
 579         };
 580         uint64_t next_chunk_id;
 581         const struct consumer_output *output;
 582         const char *new_path;
 583
 584         if (consumer_output_override) {
 585                 output = consumer_output_override;
 586         } else {
 587                 assert(session->ust_session || session->kernel_session);
 588                 output = session->ust_session ?
 589                                          session->ust_session->consumer :
 590                                          session->kernel_session->consumer;
 591         }
 592
 593         is_local_trace = output->type == CONSUMER_DST_LOCAL;
 594         base_path = session_base_path_override ? :
 595                         consumer_output_get_base_path(output);
 596
 597         if (chunk_creation_ts == (time_t) -1) {
 598                 PERROR("Failed to sample time while creation session \"%s\" trace chunk",
 599                                 session->name);
 600                 goto error;
 601         }
 602
 603         next_chunk_id = session->most_recent_chunk_id.is_set ?
 604                         session->most_recent_chunk_id.value + 1 : 0;
 605
 606         if (session->current_trace_chunk &&
 607                         !lttng_trace_chunk_get_name_overridden(session->current_trace_chunk)) {
 608                 chunk_status = lttng_trace_chunk_rename_path(session->current_trace_chunk,
 609                                         DEFAULT_CHUNK_TMP_OLD_DIRECTORY);
 610                 if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
 611                         goto error;
 612                 }
 613         }
 614         if (!session->current_trace_chunk) {
 615                 if (!session->rotated) {
 616                         new_path = "";
 617                 } else {
 618                         new_path = NULL;
 619                 }
 620         } else {
 621                 new_path = DEFAULT_CHUNK_TMP_NEW_DIRECTORY;
 622         }
 623
 624         trace_chunk = lttng_trace_chunk_create(next_chunk_id,
 625                         chunk_creation_ts, new_path);
 626         if (!trace_chunk) {
 627                 goto error;
 628         }
 629
 630         if (chunk_name_override) {
 631                 chunk_status = lttng_trace_chunk_override_name(trace_chunk,
 632                                 chunk_name_override);
 633                 if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
 634                         goto error;
 635                 }
 636         }
 637
 638         if (!is_local_trace) {
 639                 /*
 640                  * No need to set crendentials and output directory
 641                  * for remote trace chunks.
 642                  */
 643                 goto end;
 644         }
 645
 646         chunk_status = lttng_trace_chunk_set_credentials(trace_chunk,
 647                         &session_credentials);
 648         if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
 649                 goto error;
 650         }
 651
 652         DBG("Creating base output directory of session \"%s\" at %s",
 653                         session->name, base_path);
 654         ret = utils_mkdir_recursive(base_path, S_IRWXU | S_IRWXG,
 655                         session->uid, session->gid);
 656         if (ret) {
 657                 goto error;
 658         }
 659         session_output_directory = lttng_directory_handle_create(base_path);
 660         if (!session_output_directory) {
 661                 goto error;
 662         }
 663         chunk_status = lttng_trace_chunk_set_as_owner(trace_chunk,
 664                         session_output_directory);
 665         lttng_directory_handle_put(session_output_directory);
 666         session_output_directory = NULL;
 667         if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
 668                 goto error;
 669         }
 670 end:
 671         return trace_chunk;
 672 error:
 673         lttng_directory_handle_put(session_output_directory);
 674         lttng_trace_chunk_put(trace_chunk);
 675         trace_chunk = NULL;
 676         goto end;
 677 }
 678
 679 int session_close_trace_chunk(struct ltt_session *session,
 680                 struct lttng_trace_chunk *trace_chunk,
 681                 enum lttng_trace_chunk_command_type close_command,
 682                 char *closed_trace_chunk_path)
 683 {
 684         int ret = 0;
 685         bool error_occurred = false;
 686         struct cds_lfht_iter iter;
 687         struct consumer_socket *socket;
 688         enum lttng_trace_chunk_status chunk_status;
 689         const time_t chunk_close_timestamp = time(NULL);
 690         const char *new_path;
 691
 692         chunk_status = lttng_trace_chunk_set_close_command(
 693                         trace_chunk, close_command);
 694         if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
 695                 ret = -1;
 696                 goto end;
 697         }
 698
 699         if (chunk_close_timestamp == (time_t) -1) {
 700                 ERR("Failed to sample the close timestamp of the current trace chunk of session \"%s\"",
 701                                 session->name);
 702                 ret = -1;
 703                 goto end;
 704         }
 705
 706         if (close_command == LTTNG_TRACE_CHUNK_COMMAND_TYPE_DELETE && !session->rotated) {
 707                 /* New chunk stays in session output directory. */
 708                 new_path = "";
 709         } else {
 710                 /* Use chunk name for new chunk. */
 711                 new_path = NULL;
 712         }
 713         if (session->current_trace_chunk &&
 714                         !lttng_trace_chunk_get_name_overridden(session->current_trace_chunk)) {
 715                 /* Rename new chunk path. */
 716                 chunk_status = lttng_trace_chunk_rename_path(session->current_trace_chunk,
 717                                         new_path);
 718                 if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
 719                         ret = -1;
 720                         goto end;
 721                 }
 722         }
 723         if (!lttng_trace_chunk_get_name_overridden(trace_chunk) &&
 724                         close_command == LTTNG_TRACE_CHUNK_COMMAND_TYPE_NO_OPERATION) {
 725                 const char *old_path;
 726
 727                 if (!session->rotated) {
 728                         old_path = "";
 729                 } else {
 730                         old_path = NULL;
 731                 }
 732                 /* We need to move back the .tmp_old_chunk to its rightful place. */
 733                 chunk_status = lttng_trace_chunk_rename_path(trace_chunk,
 734                                         old_path);
 735                 if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
 736                         ret = -1;
 737                         goto end;
 738                 }
 739         }
 740         if (close_command == LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED) {
 741                 session->rotated = true;
 742         }
 743         chunk_status = lttng_trace_chunk_set_close_timestamp(trace_chunk,
 744                         chunk_close_timestamp);
 745         if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
 746                 ERR("Failed to set the close timestamp of the current trace chunk of session \"%s\"",
 747                                 session->name);
 748                 ret = -1;
 749                 goto end;
 750         }
 751
 752         if (session->ust_session) {
 753                 const uint64_t relayd_id =
 754                                 session->ust_session->consumer->net_seq_index;
 755
 756                 cds_lfht_for_each_entry(
 757                                 session->ust_session->consumer->socks->ht,
 758                                 &iter, socket, node.node) {
 759                         pthread_mutex_lock(socket->lock);
 760                         ret = consumer_close_trace_chunk(socket,
 761                                         relayd_id,
 762                                         session->id,
 763                                         trace_chunk, closed_trace_chunk_path);
 764                         pthread_mutex_unlock(socket->lock);
 765                         if (ret) {
 766                                 ERR("Failed to close trace chunk on user space consumer");
 767                                 error_occurred = true;
 768                         }
 769                 }
 770         }
 771         if (session->kernel_session) {
 772                 const uint64_t relayd_id =
 773                                 session->kernel_session->consumer->net_seq_index;
 774
 775                 cds_lfht_for_each_entry(
 776                                 session->kernel_session->consumer->socks->ht,
 777                                 &iter, socket, node.node) {
 778                         pthread_mutex_lock(socket->lock);
 779                         ret = consumer_close_trace_chunk(socket,
 780                                         relayd_id,
 781                                         session->id,
 782                                         trace_chunk, closed_trace_chunk_path);
 783                         pthread_mutex_unlock(socket->lock);
 784                         if (ret) {
 785                                 ERR("Failed to close trace chunk on kernel consumer");
 786                                 error_occurred = true;
 787                         }
 788                 }
 789         }
 790         ret = error_occurred ? -1 : 0;
 791 end:
 792         return ret;
 793 }
 794
 795 /*
 796  * This function skips the metadata channel as the begin/end timestamps of a
 797  * metadata packet are useless.
 798  *
 799  * Moreover, opening a packet after a "clear" will cause problems for live
 800  * sessions as it will introduce padding that was not part of the first trace
 801  * chunk. The relay daemon expects the content of the metadata stream of
 802  * successive metadata trace chunks to be strict supersets of one another.
 803  *
 804  * For example, flushing a packet at the beginning of the metadata stream of
 805  * a trace chunk resulting from a "clear" session command will cause the
 806  * size of the metadata stream of the new trace chunk to not match the size of
 807  * the metadata stream of the original chunk. This will confuse the relay
 808  * daemon as the same "offset" in a metadata stream will no longer point
 809  * to the same content.
 810  */
 811 static
 812 enum lttng_error_code session_kernel_open_packets(struct ltt_session *session)
 813 {
 814         enum lttng_error_code ret = LTTNG_OK;
 815         struct consumer_socket *socket;
 816         struct lttng_ht_iter iter;
 817         struct cds_lfht_node *node;
 818         struct ltt_kernel_channel *chan;
 819
 820         rcu_read_lock();
 821
 822         cds_lfht_first(session->kernel_session->consumer->socks->ht, &iter.iter);
 823         node = cds_lfht_iter_get_node(&iter.iter);
 824         socket = container_of(node, typeof(*socket), node.node);
 825
 826         cds_list_for_each_entry(chan,
 827                         &session->kernel_session->channel_list.head, list) {
 828                 int open_ret;
 829
 830                 DBG("Open packet of kernel channel: channel key = %" PRIu64
 831                                 ", session name = %s, session_id = %" PRIu64,
 832                                 chan->key, session->name, session->id);
 833
 834                 open_ret = consumer_open_channel_packets(socket, chan->key);
 835                 if (open_ret < 0) {
 836                         /* General error (no known error expected). */
 837                         ret = LTTNG_ERR_UNK;
 838                         goto end;
 839                 }
 840         }
 841
 842 end:
 843         rcu_read_unlock();
 844         return ret;
 845 }
 846
 847 enum lttng_error_code session_open_packets(struct ltt_session *session)
 848 {
 849         enum lttng_error_code ret = LTTNG_OK;
 850
 851         DBG("Opening packets of session channels: session name = %s, session id = %" PRIu64,
 852                         session->name, session->id);
 853
 854         if (session->ust_session) {
 855                 ret = ust_app_open_packets(session);
 856                 if (ret != LTTNG_OK) {
 857                         goto end;
 858                 }
 859         }
 860
 861         if (session->kernel_session) {
 862                 ret = session_kernel_open_packets(session);
 863                 if (ret != LTTNG_OK) {
 864                         goto end;
 865                 }
 866         }
 867
 868 end:
 869         return ret;
 870 }
 871
 872 /*
 873  * Set a session's current trace chunk.
 874  *
 875  * Must be called with the session lock held.
 876  */
 877 int session_set_trace_chunk(struct ltt_session *session,
 878                 struct lttng_trace_chunk *new_trace_chunk,
 879                 struct lttng_trace_chunk **current_trace_chunk)
 880 {
 881         ASSERT_LOCKED(session->lock);
 882         return _session_set_trace_chunk_no_lock_check(session, new_trace_chunk,
 883                         current_trace_chunk);
 884 }
 885
 886 static
 887 void session_notify_destruction(const struct ltt_session *session)
 888 {
 889         size_t i;
 890         const size_t count = lttng_dynamic_array_get_count(
 891                         &session->destroy_notifiers);
 892
 893         for (i = 0; i < count; i++) {
 894                 const struct ltt_session_destroy_notifier_element *element =
 895                         lttng_dynamic_array_get_element(
 896                                         &session->destroy_notifiers, i);
 897
 898                 element->notifier(session, element->user_data);
 899         }
 900 }
 901
 902 /*
 903  * Fire each clear notifier once, and remove them from the array.
 904  */
 905 void session_notify_clear(struct ltt_session *session)
 906 {
 907         size_t i;
 908         const size_t count = lttng_dynamic_array_get_count(
 909                         &session->clear_notifiers);
 910
 911         for (i = 0; i < count; i++) {
 912                 const struct ltt_session_clear_notifier_element *element =
 913                         lttng_dynamic_array_get_element(
 914                                         &session->clear_notifiers, i);
 915
 916                 element->notifier(session, element->user_data);
 917         }
 918         lttng_dynamic_array_clear(&session->clear_notifiers);
 919 }
 920
 921 static
 922 void session_release(struct urcu_ref *ref)
 923 {
 924         int ret;
 925         struct ltt_ust_session *usess;
 926         struct ltt_kernel_session *ksess;
 927         struct ltt_session *session = container_of(ref, typeof(*session), ref);
 928         const bool session_published = session->published;
 929
 930         assert(!session->chunk_being_archived);
 931
 932         usess = session->ust_session;
 933         ksess = session->kernel_session;
 934
 935         /* Clean kernel session teardown, keeping data for destroy notifier. */
 936         kernel_destroy_session(ksess);
 937
 938         /* UST session teardown, keeping data for destroy notifier. */
 939         if (usess) {
 940                 /* Close any relayd session */
 941                 consumer_output_send_destroy_relayd(usess->consumer);
 942
 943                 /* Destroy every UST application related to this session. */
 944                 ret = ust_app_destroy_trace_all(usess);
 945                 if (ret) {
 946                         ERR("Error in ust_app_destroy_trace_all");
 947                 }
 948
 949                 /* Clean up the rest, keeping destroy notifier data. */
 950                 trace_ust_destroy_session(usess);
 951         }
 952
 953         /*
 954          * Must notify the kernel thread here to update it's poll set in order to
 955          * remove the channel(s)' fd just destroyed.
 956          */
 957         ret = notify_thread_pipe(kernel_poll_pipe[1]);
 958         if (ret < 0) {
 959                 PERROR("write kernel poll pipe");
 960         }
 961
 962         DBG("Destroying session %s (id %" PRIu64 ")", session->name, session->id);
 963
 964         snapshot_destroy(&session->snapshot);
 965
 966         pthread_mutex_destroy(&session->lock);
 967
 968         if (session_published) {
 969                 ASSERT_LOCKED(ltt_session_list.lock);
 970                 del_session_list(session);
 971                 del_session_ht(session);
 972         }
 973         session_notify_destruction(session);
 974
 975         consumer_output_put(session->consumer);
 976         kernel_free_session(ksess);
 977         session->kernel_session = NULL;
 978         if (usess) {
 979                 trace_ust_free_session(usess);
 980                 session->ust_session = NULL;
 981         }
 982         lttng_dynamic_array_reset(&session->destroy_notifiers);
 983         lttng_dynamic_array_reset(&session->clear_notifiers);
 984         free(session->last_archived_chunk_name);
 985         free(session->base_path);
 986         free(session);
 987         if (session_published) {
 988                 /*
 989                  * Broadcast after free-ing to ensure the memory is
 990                  * reclaimed before the main thread exits.
 991                  */
 992                 ASSERT_LOCKED(ltt_session_list.lock);
 993                 pthread_cond_broadcast(&ltt_session_list.removal_cond);
 994         }
 995 }
 996
 997 /*
 998  * Acquire a reference to a session.
 999  * This function may fail (return false); its return value must be checked.
1000  */
1001 bool session_get(struct ltt_session *session)
1002 {
1003         return urcu_ref_get_unless_zero(&session->ref);
1004 }
1005
1006 /*
1007  * Release a reference to a session.
1008  */
1009 void session_put(struct ltt_session *session)
1010 {
1011         if (!session) {
1012                 return;
1013         }
1014         /*
1015          * The session list lock must be held as any session_put()
1016          * may cause the removal of the session from the session_list.
1017          */
1018         ASSERT_LOCKED(ltt_session_list.lock);
1019         assert(session->ref.refcount);
1020         urcu_ref_put(&session->ref, session_release);
1021 }
1022
1023 /*
1024  * Destroy a session.
1025  *
1026  * This method does not immediately release/free the session as other
1027  * components may still hold a reference to the session. However,
1028  * the session should no longer be presented to the user.
1029  *
1030  * Releases the session list's reference to the session
1031  * and marks it as destroyed. Iterations on the session list should be
1032  * mindful of the "destroyed" flag.
1033  */
1034 void session_destroy(struct ltt_session *session)
1035 {
1036         assert(!session->destroyed);
1037         session->destroyed = true;
1038         session_put(session);
1039 }
1040
1041 int session_add_destroy_notifier(struct ltt_session *session,
1042                 ltt_session_destroy_notifier notifier, void *user_data)
1043 {
1044         const struct ltt_session_destroy_notifier_element element = {
1045                 .notifier = notifier,
1046                 .user_data = user_data
1047         };
1048
1049         return lttng_dynamic_array_add_element(&session->destroy_notifiers,
1050                         &element);
1051 }
1052
1053 int session_add_clear_notifier(struct ltt_session *session,
1054                 ltt_session_clear_notifier notifier, void *user_data)
1055 {
1056         const struct ltt_session_clear_notifier_element element = {
1057                 .notifier = notifier,
1058                 .user_data = user_data
1059         };
1060
1061         return lttng_dynamic_array_add_element(&session->clear_notifiers,
1062                         &element);
1063 }
1064
1065 /*
1066  * Return a ltt_session structure ptr that matches name. If no session found,
1067  * NULL is returned. This must be called with the session list lock held using
1068  * session_lock_list and session_unlock_list.
1069  * A reference to the session is implicitly acquired by this function.
1070  */
1071 struct ltt_session *session_find_by_name(const char *name)
1072 {
1073         struct ltt_session *iter;
1074
1075         assert(name);
1076         ASSERT_LOCKED(ltt_session_list.lock);
1077
1078         DBG2("Trying to find session by name %s", name);
1079
1080         cds_list_for_each_entry(iter, &ltt_session_list.head, list) {
1081                 if (!strncmp(iter->name, name, NAME_MAX) &&
1082                                 !iter->destroyed) {
1083                         goto found;
1084                 }
1085         }
1086
1087         return NULL;
1088 found:
1089         return session_get(iter) ? iter : NULL;
1090 }
1091
1092 /*
1093  * Return an ltt_session that matches the id. If no session is found,
1094  * NULL is returned. This must be called with rcu_read_lock and
1095  * session list lock held (to guarantee the lifetime of the session).
1096  */
1097 struct ltt_session *session_find_by_id(uint64_t id)
1098 {
1099         struct lttng_ht_node_u64 *node;
1100         struct lttng_ht_iter iter;
1101         struct ltt_session *ls;
1102
1103         ASSERT_LOCKED(ltt_session_list.lock);
1104
1105         if (!ltt_sessions_ht_by_id) {
1106                 goto end;
1107         }
1108
1109         lttng_ht_lookup(ltt_sessions_ht_by_id, &id, &iter);
1110         node = lttng_ht_iter_get_node_u64(&iter);
1111         if (node == NULL) {
1112                 goto end;
1113         }
1114         ls = caa_container_of(node, struct ltt_session, node);
1115
1116         DBG3("Session %" PRIu64 " found by id.", id);
1117         return session_get(ls) ? ls : NULL;
1118
1119 end:
1120         DBG3("Session %" PRIu64 " NOT found by id", id);
1121         return NULL;
1122 }
1123
1124 /*
1125  * Create a new session and add it to the session list.
1126  * Session list lock must be held by the caller.
1127  */
1128 enum lttng_error_code session_create(const char *name, uid_t uid, gid_t gid,
1129                 struct ltt_session **out_session)
1130 {
1131         int ret;
1132         enum lttng_error_code ret_code;
1133         struct ltt_session *new_session = NULL;
1134
1135         ASSERT_LOCKED(ltt_session_list.lock);
1136         if (name) {
1137                 struct ltt_session *clashing_session;
1138
1139                 clashing_session = session_find_by_name(name);
1140                 if (clashing_session) {
1141                         session_put(clashing_session);
1142                         ret_code = LTTNG_ERR_EXIST_SESS;
1143                         goto error;
1144                 }
1145         }
1146         new_session = zmalloc(sizeof(struct ltt_session));
1147         if (!new_session) {
1148                 PERROR("Failed to allocate an ltt_session structure");
1149                 ret_code = LTTNG_ERR_NOMEM;
1150                 goto error;
1151         }
1152
1153         lttng_dynamic_array_init(&new_session->destroy_notifiers,
1154                         sizeof(struct ltt_session_destroy_notifier_element),
1155                         NULL);
1156         lttng_dynamic_array_init(&new_session->clear_notifiers,
1157                         sizeof(struct ltt_session_clear_notifier_element),
1158                         NULL);
1159         urcu_ref_init(&new_session->ref);
1160         pthread_mutex_init(&new_session->lock, NULL);
1161
1162         new_session->creation_time = time(NULL);
1163         if (new_session->creation_time == (time_t) -1) {
1164                 PERROR("Failed to sample session creation time");
1165                 ret_code = LTTNG_ERR_SESSION_FAIL;
1166                 goto error;
1167         }
1168
1169         /* Create default consumer output. */
1170         new_session->consumer = consumer_create_output(CONSUMER_DST_LOCAL);
1171         if (new_session->consumer == NULL) {
1172                 ret_code = LTTNG_ERR_NOMEM;
1173                 goto error;
1174         }
1175
1176         if (name) {
1177                 ret = lttng_strncpy(new_session->name, name, sizeof(new_session->name));
1178                 if (ret) {
1179                         ret_code = LTTNG_ERR_SESSION_INVALID_CHAR;
1180                         goto error;
1181                 }
1182                 ret = validate_name(name);
1183                 if (ret < 0) {
1184                         ret_code = LTTNG_ERR_SESSION_INVALID_CHAR;
1185                         goto error;
1186                 }
1187         } else {
1188                 int i = 0;
1189                 bool found_name = false;
1190                 char datetime[16];
1191                 struct tm *timeinfo;
1192
1193                 timeinfo = localtime(&new_session->creation_time);
1194                 if (!timeinfo) {
1195                         ret_code = LTTNG_ERR_SESSION_FAIL;
1196                         goto error;
1197                 }
1198                 strftime(datetime, sizeof(datetime), "%Y%m%d-%H%M%S", timeinfo);
1199                 for (i = 0; i < INT_MAX; i++) {
1200                         struct ltt_session *clashing_session;
1201
1202                         if (i == 0) {
1203                                 ret = snprintf(new_session->name,
1204                                                 sizeof(new_session->name),
1205                                                 "%s-%s",
1206                                                 DEFAULT_SESSION_NAME,
1207                                                 datetime);
1208                         } else {
1209                                 ret = snprintf(new_session->name,
1210                                                 sizeof(new_session->name),
1211                                                 "%s%d-%s",
1212                                                 DEFAULT_SESSION_NAME, i,
1213                                                 datetime);
1214                         }
1215                         new_session->name_contains_creation_time = true;
1216                         if (ret == -1 || ret >= sizeof(new_session->name)) {
1217                                 /*
1218                                  * Null-terminate in case the name is used
1219                                  * in logging statements.
1220                                  */
1221                                 new_session->name[sizeof(new_session->name) - 1] = '\0';
1222                                 ret_code = LTTNG_ERR_SESSION_FAIL;
1223                                 goto error;
1224                         }
1225
1226                         clashing_session =
1227                                         session_find_by_name(new_session->name);
1228                         session_put(clashing_session);
1229                         if (!clashing_session) {
1230                                 found_name = true;
1231                                 break;
1232                         }
1233                 }
1234                 if (found_name) {
1235                         DBG("Generated session name \"%s\"", new_session->name);
1236                         new_session->has_auto_generated_name = true;
1237                 } else {
1238                         ERR("Failed to auto-generate a session name");
1239                         ret_code = LTTNG_ERR_SESSION_FAIL;
1240                         goto error;
1241                 }
1242         }
1243
1244         ret = gethostname(new_session->hostname, sizeof(new_session->hostname));
1245         if (ret < 0) {
1246                 if (errno == ENAMETOOLONG) {
1247                         new_session->hostname[sizeof(new_session->hostname) - 1] = '\0';
1248                         ERR("Hostname exceeds the maximal permitted length and has been truncated to %s",
1249                                         new_session->hostname);
1250                 } else {
1251                         ret_code = LTTNG_ERR_SESSION_FAIL;
1252                         goto error;
1253                 }
1254         }
1255
1256         new_session->uid = uid;
1257         new_session->gid = gid;
1258
1259         ret = snapshot_init(&new_session->snapshot);
1260         if (ret < 0) {
1261                 ret_code = LTTNG_ERR_NOMEM;
1262                 goto error;
1263         }
1264
1265         new_session->rotation_state = LTTNG_ROTATION_STATE_NO_ROTATION;
1266
1267         /* Add new session to the session list. */
1268         new_session->id = add_session_list(new_session);
1269
1270         /*
1271          * Add the new session to the ltt_sessions_ht_by_id.
1272          * No ownership is taken by the hash table; it is merely
1273          * a wrapper around the session list used for faster access
1274          * by session id.
1275          */
1276         add_session_ht(new_session);
1277         new_session->published = true;
1278
1279         /*
1280          * Consumer is left to NULL since the create_session_uri command will
1281          * set it up and, if valid, assign it to the session.
1282          */
1283         DBG("Tracing session %s created with ID %" PRIu64 " by uid = %d, gid = %d",
1284                         new_session->name, new_session->id, new_session->uid,
1285                         new_session->gid);
1286         ret_code = LTTNG_OK;
1287 end:
1288         if (new_session) {
1289                 (void) session_get(new_session);
1290                 *out_session = new_session;
1291         }
1292         return ret_code;
1293 error:
1294         session_put(new_session);
1295         new_session = NULL;
1296         goto end;
1297 }
1298
1299 /*
1300  * Check if the UID matches the session. Root user has access to all
1301  * sessions.
1302  */
1303 bool session_access_ok(struct ltt_session *session, uid_t uid)
1304 {
1305         assert(session);
1306         return (uid == session->uid) || uid == 0;
1307 }
1308
1309 /*
1310  * Set a session's rotation state and reset all associated state.
1311  *
1312  * This function resets the rotation state (check timers, pending
1313  * flags, etc.) and sets the result of the last rotation. The result
1314  * can be queries by a liblttng-ctl client.
1315  *
1316  * Be careful of the result passed to this function. For instance,
1317  * on failure to launch a rotation, a client will expect the rotation
1318  * state to be set to "NO_ROTATION". If an error occurred while the
1319  * rotation was "ONGOING", result should be set to "ERROR", which will
1320  * allow a client to report it.
1321  *
1322  * Must be called with the session and session_list locks held.
1323  */
1324 int session_reset_rotation_state(struct ltt_session *session,
1325                 enum lttng_rotation_state result)
1326 {
1327         int ret = 0;
1328
1329         ASSERT_LOCKED(ltt_session_list.lock);
1330         ASSERT_LOCKED(session->lock);
1331
1332         session->rotation_state = result;
1333         if (session->rotation_pending_check_timer_enabled) {
1334                 ret = timer_session_rotation_pending_check_stop(session);
1335         }
1336         if (session->chunk_being_archived) {
1337                 uint64_t chunk_id;
1338                 enum lttng_trace_chunk_status chunk_status;
1339
1340                 chunk_status = lttng_trace_chunk_get_id(
1341                                 session->chunk_being_archived,
1342                                 &chunk_id);
1343                 assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
1344                 LTTNG_OPTIONAL_SET(&session->last_archived_chunk_id,
1345                                 chunk_id);
1346                 lttng_trace_chunk_put(session->chunk_being_archived);
1347                 session->chunk_being_archived = NULL;
1348                 /*
1349                  * Fire the clear reply notifiers if we are completing a clear
1350                  * rotation.
1351                  */
1352                 session_notify_clear(session);
1353         }
1354         return ret;
1355 }