src/bin/lttng-sessiond/ust-registry-session.cpp

   1 /*
   2  * Copyright (C) 2022 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   3  *
   4  * SPDX-License-Identifier: GPL-2.0-only
   5  *
   6  */
   7
   8 #include "ctf2-trace-class-visitor.hpp"
   9 #include "field.hpp"
  10 #include "lttng-sessiond.hpp"
  11 #include "notification-thread-commands.hpp"
  12 #include "session.hpp"
  13 #include "trace-class.hpp"
  14 #include "tsdl-trace-class-visitor.hpp"
  15 #include "ust-app.hpp"
  16 #include "ust-field-convert.hpp"
  17 #include "ust-registry.hpp"
  18
  19 #include <common/compat/directory-handle.hpp>
  20 #include <common/error.hpp>
  21 #include <common/exception.hpp>
  22 #include <common/format.hpp>
  23 #include <common/hashtable/utils.hpp>
  24 #include <common/macros.hpp>
  25 #include <common/make-unique.hpp>
  26 #include <common/pthread-lock.hpp>
  27 #include <common/runas.hpp>
  28 #include <common/time.hpp>
  29 #include <common/urcu.hpp>
  30
  31 #include <fcntl.h>
  32 #include <functional>
  33 #include <initializer_list>
  34 #include <mutex>
  35 #include <sstream>
  36 #include <string>
  37
  38 namespace ls = lttng::sessiond;
  39 namespace lst = lttng::sessiond::trace;
  40 namespace lsu = lttng::sessiond::ust;
  41
  42 namespace {
  43 lttng_uuid generate_uuid_or_throw()
  44 {
  45         lttng_uuid new_uuid;
  46
  47         if (lttng_uuid_generate(new_uuid)) {
  48                 LTTNG_THROW_POSIX("Failed to generate UST uuid", errno);
  49         }
  50
  51         return new_uuid;
  52 }
  53
  54 int get_count_order(unsigned int count)
  55 {
  56         int order;
  57
  58         order = lttng_fls(count) - 1;
  59         if (count & (count - 1)) {
  60                 order++;
  61         }
  62
  63         LTTNG_ASSERT(order >= 0);
  64         return order;
  65 }
  66
  67 void clear_metadata_file(int fd)
  68 {
  69         const auto lseek_ret = lseek(fd, 0, SEEK_SET);
  70         if (lseek_ret < 0) {
  71                 LTTNG_THROW_POSIX(
  72                         "Failed to seek to the beginning of the metadata file while clearing it",
  73                         errno);
  74         }
  75
  76         const auto ret = ftruncate(fd, 0);
  77         if (ret < 0) {
  78                 LTTNG_THROW_POSIX("Failed to truncate the metadata file while clearing it", errno);
  79         }
  80 }
  81
  82 /*
  83  * Validate that the id has reached the maximum allowed or not.
  84  */
  85 bool is_max_channel_id(uint32_t id)
  86 {
  87         return id == UINT32_MAX;
  88 }
  89
  90 void destroy_channel_rcu(struct rcu_head *head)
  91 {
  92         DIAGNOSTIC_PUSH
  93         DIAGNOSTIC_IGNORE_INVALID_OFFSETOF
  94         lsu::registry_channel *chan =
  95                 lttng::utils::container_of(head, &lsu::registry_channel::_rcu_head);
  96         DIAGNOSTIC_POP
  97
  98         delete chan;
  99 }
 100
 101 /*
 102  * Destroy every element of the registry and free the memory. This does NOT
 103  * free the registry pointer since it might not have been allocated before so
 104  * it's the caller responsability.
 105  *
 106  * Called from ~registry_session(), must not throw.
 107  */
 108 void destroy_channel(lsu::registry_channel *chan, bool notify) noexcept
 109 {
 110         struct lttng_ht_iter iter;
 111         lttng::sessiond::ust::registry_event *event;
 112         enum lttng_error_code cmd_ret;
 113
 114         LTTNG_ASSERT(chan);
 115
 116         if (notify) {
 117                 cmd_ret = notification_thread_command_remove_channel(
 118                         the_notification_thread_handle, chan->_consumer_key, LTTNG_DOMAIN_UST);
 119                 if (cmd_ret != LTTNG_OK) {
 120                         ERR("Failed to remove channel from notification thread");
 121                 }
 122         }
 123
 124         if (chan->_events) {
 125                 lttng::urcu::read_lock_guard read_lock_guard;
 126
 127                 /* Destroy all event associated with this registry. */
 128                 DIAGNOSTIC_PUSH
 129                 DIAGNOSTIC_IGNORE_INVALID_OFFSETOF
 130                 cds_lfht_for_each_entry (chan->_events->ht, &iter.iter, event, _node) {
 131                         /* Delete the node from the ht and free it. */
 132                         ust_registry_channel_destroy_event(chan, event);
 133                 }
 134                 DIAGNOSTIC_POP
 135         }
 136
 137         call_rcu(&chan->_rcu_head, destroy_channel_rcu);
 138 }
 139
 140 void destroy_enum(lsu::registry_enum *reg_enum)
 141 {
 142         if (!reg_enum) {
 143                 return;
 144         }
 145
 146         delete reg_enum;
 147 }
 148
 149 void destroy_enum_rcu(struct rcu_head *head)
 150 {
 151         DIAGNOSTIC_PUSH
 152         DIAGNOSTIC_IGNORE_INVALID_OFFSETOF
 153         lsu::registry_enum *reg_enum =
 154                 lttng::utils::container_of(head, &lsu::registry_enum::rcu_head);
 155         DIAGNOSTIC_POP
 156
 157         destroy_enum(reg_enum);
 158 }
 159
 160 /*
 161  * Hash table match function for enumerations in the session. Match is
 162  * performed on enumeration name, and confirmed by comparing the enum
 163  * entries.
 164  */
 165 int ht_match_enum(struct cds_lfht_node *node, const void *_key)
 166 {
 167         lsu::registry_enum *_enum;
 168         const lsu::registry_enum *key;
 169
 170         LTTNG_ASSERT(node);
 171         LTTNG_ASSERT(_key);
 172
 173         DIAGNOSTIC_PUSH
 174         DIAGNOSTIC_IGNORE_INVALID_OFFSETOF
 175         _enum = caa_container_of(node, lsu::registry_enum, node.node);
 176         DIAGNOSTIC_POP
 177
 178         LTTNG_ASSERT(_enum);
 179         key = (lsu::registry_enum *) _key;
 180
 181         return *_enum == *key;
 182 }
 183
 184 /*
 185  * Hash table match function for enumerations in the session. Match is
 186  * performed by enumeration ID.
 187  */
 188 int ht_match_enum_id(struct cds_lfht_node *node, const void *_key)
 189 {
 190         lsu::registry_enum *_enum;
 191         const lsu::registry_enum *key = (lsu::registry_enum *) _key;
 192
 193         LTTNG_ASSERT(node);
 194         LTTNG_ASSERT(_key);
 195
 196         DIAGNOSTIC_PUSH
 197         DIAGNOSTIC_IGNORE_INVALID_OFFSETOF
 198         _enum = caa_container_of(node, lsu::registry_enum, node.node);
 199         DIAGNOSTIC_POP
 200
 201         LTTNG_ASSERT(_enum);
 202
 203         if (_enum->id != key->id) {
 204                 goto no_match;
 205         }
 206
 207         /* Match. */
 208         return 1;
 209
 210 no_match:
 211         return 0;
 212 }
 213
 214 /*
 215  * Hash table hash function for enumerations in the session. The
 216  * enumeration name is used for hashing.
 217  */
 218 unsigned long ht_hash_enum(void *_key, unsigned long seed)
 219 {
 220         lsu::registry_enum *key = (lsu::registry_enum *) _key;
 221
 222         LTTNG_ASSERT(key);
 223         return hash_key_str(key->name.c_str(), seed);
 224 }
 225 } /* namespace */
 226
 227 void lsu::details::locked_registry_session_release(lsu::registry_session *session)
 228 {
 229         pthread_mutex_unlock(&session->_lock);
 230 }
 231
 232 lsu::registry_session::registry_session(const struct lst::abi& in_abi,
 233                                         uint32_t major,
 234                                         uint32_t minor,
 235                                         const char *root_shm_path,
 236                                         const char *shm_path,
 237                                         uid_t euid,
 238                                         gid_t egid,
 239                                         uint64_t tracing_id) :
 240         lst::trace_class(in_abi, generate_uuid_or_throw()),
 241         _root_shm_path{ root_shm_path ? root_shm_path : "" },
 242         _shm_path{ shm_path ? shm_path : "" },
 243         _metadata_path{ _shm_path.size() > 0 ? fmt::format("{}/metadata", _shm_path) :
 244                                                std::string("") },
 245         _uid{ euid },
 246         _gid{ egid },
 247         _app_tracer_version{ .major = major, .minor = minor },
 248         _tracing_id{ tracing_id },
 249         _clock{ lttng::make_unique<lsu::clock_class>() },
 250         _metadata_generating_visitor{ lttng::make_unique<ls::tsdl::trace_class_visitor>(
 251                 abi,
 252                 [this](const std::string& fragment) { _append_metadata_fragment(fragment); }) },
 253         _packet_header{ _create_packet_header() }
 254 {
 255         pthread_mutex_init(&_lock, nullptr);
 256         if (_shm_path.size() > 0) {
 257                 if (run_as_mkdir_recursive(_shm_path.c_str(), S_IRWXU | S_IRWXG, euid, egid)) {
 258                         LTTNG_THROW_POSIX("run_as_mkdir_recursive", errno);
 259                 }
 260         }
 261
 262         if (_metadata_path.size() > 0) {
 263                 /* Create metadata file. */
 264                 const int ret = run_as_open(_metadata_path.c_str(),
 265                                             O_WRONLY | O_CREAT | O_EXCL,
 266                                             S_IRUSR | S_IWUSR,
 267                                             euid,
 268                                             egid);
 269                 if (ret < 0) {
 270                         LTTNG_THROW_POSIX(
 271                                 fmt::format(
 272                                         "Failed to open metadata file during registry session creation: path = {}",
 273                                         _metadata_path),
 274                                 errno);
 275                 }
 276
 277                 _metadata_fd = ret;
 278         }
 279
 280         _enums.reset(lttng_ht_new(0, LTTNG_HT_TYPE_STRING));
 281         if (!_enums) {
 282                 LTTNG_THROW_POSIX("Failed to create enums hash table", ENOMEM);
 283         }
 284
 285         /* hash/match functions are specified at call site. */
 286         _enums->match_fct = nullptr;
 287         _enums->hash_fct = nullptr;
 288
 289         _channels.reset(lttng_ht_new(0, LTTNG_HT_TYPE_U64));
 290         if (!_channels) {
 291                 LTTNG_THROW_POSIX("Failed to create channels hash table", ENOMEM);
 292         }
 293 }
 294
 295 lst::type::cuptr lsu::registry_session::_create_packet_header() const
 296 {
 297         lst::structure_type::fields packet_header_fields;
 298
 299         /* uint32_t magic */
 300         packet_header_fields.emplace_back(lttng::make_unique<lst::field>(
 301                 "magic",
 302                 lttng::make_unique<lst::integer_type>(
 303                         abi.uint32_t_alignment,
 304                         abi.byte_order,
 305                         32,
 306                         lst::integer_type::signedness::UNSIGNED,
 307                         lst::integer_type::base::HEXADECIMAL,
 308                         std::initializer_list<lst::integer_type::role>(
 309                                 { lst::integer_type::role::PACKET_MAGIC_NUMBER }))));
 310
 311         /* uuid */
 312         packet_header_fields.emplace_back(lttng::make_unique<lst::field>(
 313                 "uuid",
 314                 lttng::make_unique<lst::static_length_blob_type>(
 315                         0,
 316                         16,
 317                         std::initializer_list<lst::static_length_blob_type::role>(
 318                                 { lst::static_length_blob_type::role::METADATA_STREAM_UUID }))));
 319
 320         /* uint32_t stream_id */
 321         packet_header_fields.emplace_back(lttng::make_unique<lst::field>(
 322                 "stream_id",
 323                 lttng::make_unique<lst::integer_type>(
 324                         abi.uint32_t_alignment,
 325                         abi.byte_order,
 326                         32,
 327                         lst::integer_type::signedness::UNSIGNED,
 328                         lst::integer_type::base::DECIMAL,
 329                         std::initializer_list<lst::integer_type::role>(
 330                                 { lst::integer_type::role::DATA_STREAM_CLASS_ID }))));
 331
 332         /* uint64_t stream_instance_id */
 333         packet_header_fields.emplace_back(lttng::make_unique<lst::field>(
 334                 "stream_instance_id",
 335                 lttng::make_unique<lst::integer_type>(
 336                         abi.uint64_t_alignment,
 337                         abi.byte_order,
 338                         64,
 339                         lst::integer_type::signedness::UNSIGNED,
 340                         lst::integer_type::base::DECIMAL,
 341                         std::initializer_list<lst::integer_type::role>(
 342                                 { lst::integer_type::role::DATA_STREAM_ID }))));
 343
 344         return lttng::make_unique<lst::structure_type>(0, std::move(packet_header_fields));
 345 }
 346
 347 const lst::type *lsu::registry_session::packet_header() const noexcept
 348 {
 349         return _packet_header.get();
 350 }
 351
 352 /*
 353  * For a given enumeration in a registry, delete the entry and destroy
 354  * the enumeration.
 355  *
 356  * Note that this is used by ~registry_session() and must not throw.
 357  */
 358 void lsu::registry_session::_destroy_enum(lsu::registry_enum *reg_enum) noexcept
 359 {
 360         int ret;
 361         lttng::urcu::read_lock_guard read_lock_guard;
 362
 363         LTTNG_ASSERT(reg_enum);
 364         ASSERT_RCU_READ_LOCKED();
 365
 366         /* Delete the node first. */
 367         struct lttng_ht_iter iter;
 368         iter.iter.node = &reg_enum->node.node;
 369         ret = lttng_ht_del(_enums.get(), &iter);
 370         LTTNG_ASSERT(!ret);
 371         call_rcu(&reg_enum->rcu_head, destroy_enum_rcu);
 372 }
 373
 374 lsu::registry_session::~registry_session()
 375 {
 376         int ret;
 377         struct lttng_ht_iter iter;
 378         lsu::registry_channel *chan;
 379         lsu::registry_enum *reg_enum;
 380
 381         /* On error, EBUSY can be returned if lock. Code flow error. */
 382         ret = pthread_mutex_destroy(&_lock);
 383         LTTNG_ASSERT(!ret);
 384
 385         if (_channels) {
 386                 lttng::urcu::read_lock_guard read_lock_guard;
 387
 388                 /* Destroy all event associated with this registry. */
 389                 DIAGNOSTIC_PUSH
 390                 DIAGNOSTIC_IGNORE_INVALID_OFFSETOF
 391                 cds_lfht_for_each_entry (_channels->ht, &iter.iter, chan, _node.node) {
 392                         /* Delete the node from the ht and free it. */
 393                         ret = lttng_ht_del(_channels.get(), &iter);
 394                         LTTNG_ASSERT(!ret);
 395                         destroy_channel(chan, true);
 396                 }
 397                 DIAGNOSTIC_POP
 398         }
 399
 400         free(_metadata);
 401         if (_metadata_fd >= 0) {
 402                 ret = close(_metadata_fd);
 403                 if (ret) {
 404                         PERROR("close");
 405                 }
 406
 407                 ret = run_as_unlink(_metadata_path.c_str(), _uid, _gid);
 408                 if (ret) {
 409                         PERROR("unlink");
 410                 }
 411         }
 412
 413         if (_root_shm_path[0]) {
 414                 /* Try to delete the directory hierarchy. */
 415                 (void) run_as_rmdir_recursive(_root_shm_path.c_str(),
 416                                               _uid,
 417                                               _gid,
 418                                               LTTNG_DIRECTORY_HANDLE_SKIP_NON_EMPTY_FLAG);
 419         }
 420
 421         /* Destroy the enum hash table */
 422         if (_enums) {
 423                 lttng::urcu::read_lock_guard read_lock_guard;
 424
 425                 /* Destroy all enum entries associated with this registry. */
 426                 DIAGNOSTIC_PUSH
 427                 DIAGNOSTIC_IGNORE_INVALID_OFFSETOF
 428                 cds_lfht_for_each_entry (_enums->ht, &iter.iter, reg_enum, node.node) {
 429                         _destroy_enum(reg_enum);
 430                 }
 431                 DIAGNOSTIC_POP
 432         }
 433 }
 434
 435 lsu::registry_session::locked_ptr lsu::registry_session::lock() noexcept
 436 {
 437         pthread_mutex_lock(&_lock);
 438         return locked_ptr(this);
 439 }
 440
 441 /*
 442  * Initialize registry with default values.
 443  */
 444 void lsu::registry_session::add_channel(uint64_t key)
 445 {
 446         lttng::pthread::lock_guard session_lock_guard(_lock);
 447
 448         /*
 449          * Assign a channel ID right now since the event notification comes
 450          * *before* the channel notify so the ID needs to be set at this point so
 451          * the metadata can be dumped for that event.
 452          */
 453         if (is_max_channel_id(_used_channel_id)) {
 454                 LTTNG_THROW_ERROR(fmt::format(
 455                         "Failed to allocate unique id for channel under session while adding channel"));
 456         }
 457
 458         auto chan = new lsu::registry_channel(
 459                 _get_next_channel_id(),
 460                 abi,
 461                 _clock->name,
 462                 /* Registered channel listener. */
 463                 [this](const lsu::registry_channel& registered_channel) {
 464                         /*
 465                          * Channel registration completed, serialize it's layout's
 466                          * description.
 467                          */
 468                         registered_channel.accept(*_metadata_generating_visitor);
 469                 },
 470                 /* Added event listener. */
 471                 [this](const lsu::registry_channel& channel,
 472                        const lsu::registry_event& added_event) {
 473                         /*
 474                          * The channel and its event classes will be dumped at once when
 475                          * it is registered. This check prevents event classes from being
 476                          * declared before their stream class.
 477                          */
 478                         if (channel.is_registered()) {
 479                                 added_event.accept(*_metadata_generating_visitor);
 480                         }
 481                 });
 482
 483         lttng::urcu::read_lock_guard rcu_read_lock_guard;
 484         lttng_ht_node_init_u64(&chan->_node, key);
 485         lttng_ht_add_unique_u64(_channels.get(), &chan->_node);
 486 }
 487
 488 lttng::sessiond::ust::registry_channel& lsu::registry_session::channel(uint64_t channel_key) const
 489 {
 490         lttng::urcu::read_lock_guard read_lock_guard;
 491         struct lttng_ht_node_u64 *node;
 492         struct lttng_ht_iter iter;
 493
 494         ASSERT_LOCKED(_lock);
 495
 496         lttng_ht_lookup(_channels.get(), &channel_key, &iter);
 497         node = lttng_ht_iter_get_node_u64(&iter);
 498         if (!node) {
 499                 LTTNG_THROW_INVALID_ARGUMENT_ERROR(
 500                         fmt::format("Invalid channel key provided: channel key = {}", channel_key));
 501         }
 502
 503         DIAGNOSTIC_PUSH
 504         DIAGNOSTIC_IGNORE_INVALID_OFFSETOF
 505         auto chan = lttng::utils::container_of(node, &lsu::registry_channel::_node);
 506         DIAGNOSTIC_POP
 507         return *chan;
 508 }
 509
 510 void lsu::registry_session::remove_channel(uint64_t channel_key, bool notify)
 511 {
 512         struct lttng_ht_iter iter;
 513         int ret;
 514         lttng::urcu::read_lock_guard read_lock_guard;
 515
 516         ASSERT_LOCKED(_lock);
 517         auto& channel_to_remove = channel(channel_key);
 518
 519         iter.iter.node = &channel_to_remove._node.node;
 520         ret = lttng_ht_del(_channels.get(), &iter);
 521         LTTNG_ASSERT(!ret);
 522         destroy_channel(&channel_to_remove, notify);
 523 }
 524
 525 void lsu::registry_session::accept(
 526         lttng::sessiond::trace::trace_class_environment_visitor& visitor) const
 527 {
 528         ASSERT_LOCKED(_lock);
 529
 530         visitor.visit(lst::environment_field<const char *>("domain", "ust"));
 531         visitor.visit(lst::environment_field<const char *>("tracer_name", "lttng-ust"));
 532         visitor.visit(lst::environment_field<int64_t>("tracer_major", _app_tracer_version.major));
 533         visitor.visit(lst::environment_field<int64_t>("tracer_minor", _app_tracer_version.minor));
 534         visitor.visit(lst::environment_field<const char *>(
 535                 "tracer_buffering_scheme",
 536                 buffering_scheme() == LTTNG_BUFFER_PER_PID ? "pid" : "uid"));
 537         visitor.visit(lst::environment_field<int64_t>("architecture_bit_width", abi.bits_per_long));
 538
 539         {
 540                 /* The caller already holds the session and session list locks. */
 541                 ASSERT_SESSION_LIST_LOCKED();
 542                 const auto session = lttng::sessiond::find_session_by_id(_tracing_id);
 543
 544                 LTTNG_ASSERT(session);
 545                 ASSERT_LOCKED(session->lock);
 546
 547                 visitor.visit(lst::environment_field<const char *>(
 548                         "trace_name",
 549                         session->has_auto_generated_name ? DEFAULT_SESSION_NAME : session->name));
 550                 visitor.visit(lst::environment_field<std::string>(
 551                         "trace_creation_datetime",
 552                         lttng::utils::time_to_iso8601_str(session->creation_time)));
 553                 visitor.visit(lst::environment_field<const char *>("hostname", session->hostname));
 554         }
 555 }
 556
 557 void lsu::registry_session::_accept_on_clock_classes(lst::trace_class_visitor& visitor) const
 558 {
 559         ASSERT_LOCKED(_lock);
 560         _clock->accept(visitor);
 561 }
 562
 563 void lsu::registry_session::_accept_on_stream_classes(lst::trace_class_visitor& visitor) const
 564 {
 565         ASSERT_LOCKED(_lock);
 566
 567         std::vector<const lttng::sessiond::ust::registry_channel *> sorted_stream_classes;
 568
 569         {
 570                 lttng::urcu::read_lock_guard rcu_lock_guard;
 571                 const lsu::registry_channel *channel;
 572                 lttng_ht_iter channel_it;
 573
 574                 DIAGNOSTIC_PUSH
 575                 DIAGNOSTIC_IGNORE_INVALID_OFFSETOF
 576                 cds_lfht_for_each_entry (_channels->ht, &channel_it.iter, channel, _node.node) {
 577                         sorted_stream_classes.emplace_back(channel);
 578                 }
 579                 DIAGNOSTIC_POP
 580         }
 581
 582         std::sort(sorted_stream_classes.begin(),
 583                   sorted_stream_classes.end(),
 584                   [](const lttng::sessiond::ust::registry_channel *a,
 585                      const lttng::sessiond::ust::registry_channel *b) { return a->id < b->id; });
 586
 587         for (const auto stream_class : sorted_stream_classes) {
 588                 stream_class->accept(visitor);
 589         }
 590 }
 591
 592 /*
 593  * Return next available channel id and increment the used counter. The
 594  * is_max_channel_id function MUST be called before in order to validate
 595  * if the maximum number of IDs have been reached. If not, it is safe to call
 596  * this function.
 597  *
 598  * Return a unique channel ID. If max is reached, the used_channel_id counter
 599  * is returned.
 600  */
 601 uint32_t lsu::registry_session::_get_next_channel_id()
 602 {
 603         if (is_max_channel_id(_used_channel_id)) {
 604                 return _used_channel_id;
 605         }
 606
 607         _used_channel_id++;
 608         return _next_channel_id++;
 609 }
 610
 611 void lsu::registry_session::_increase_metadata_size(size_t reservation_length)
 612 {
 613         const auto new_len = _metadata_len + reservation_length;
 614         auto new_alloc_len = new_len;
 615         const auto old_alloc_len = _metadata_alloc_len;
 616
 617         /* Rounding the new allocation length to the next power of 2 would overflow. */
 618         if (new_alloc_len > (UINT32_MAX >> 1)) {
 619                 LTTNG_THROW_ERROR(
 620                         "Failed to reserve trace metadata storage as the new size would overflow");
 621         }
 622
 623         /* The current allocation length is already the largest we can afford. */
 624         if ((old_alloc_len << 1) > (UINT32_MAX >> 1)) {
 625                 LTTNG_THROW_ERROR(
 626                         "Failed to reserve trace metadata storage as the max size was already reached");
 627         }
 628
 629         if (new_alloc_len > old_alloc_len) {
 630                 new_alloc_len =
 631                         std::max<size_t>(1U << get_count_order(new_alloc_len), old_alloc_len << 1);
 632
 633                 auto newptr = (char *) realloc(_metadata, new_alloc_len);
 634                 if (!newptr) {
 635                         LTTNG_THROW_POSIX("Failed to allocate trace metadata storage", errno);
 636                 }
 637
 638                 _metadata = newptr;
 639
 640                 /* We zero directly the memory from start of allocation. */
 641                 memset(&_metadata[old_alloc_len], 0, new_alloc_len - old_alloc_len);
 642                 _metadata_alloc_len = new_alloc_len;
 643         }
 644
 645         _metadata_len += reservation_length;
 646 }
 647
 648 void lsu::registry_session::_append_metadata_fragment(const std::string& fragment)
 649 {
 650         const auto offset = _metadata_len;
 651
 652         _increase_metadata_size(fragment.size());
 653         memcpy(&_metadata[offset], fragment.c_str(), fragment.size());
 654
 655         if (_metadata_fd >= 0) {
 656                 const auto bytes_written =
 657                         lttng_write(_metadata_fd, fragment.c_str(), fragment.size());
 658
 659                 if (bytes_written != fragment.size()) {
 660                         LTTNG_THROW_POSIX("Failed to write trace metadata fragment to file", errno);
 661                 }
 662         }
 663 }
 664
 665 void lsu::registry_session::_reset_metadata()
 666 {
 667         _metadata_len_sent = 0;
 668         memset(_metadata, 0, _metadata_alloc_len);
 669         _metadata_len = 0;
 670
 671         if (_metadata_fd > 0) {
 672                 /* Clear the metadata file's content. */
 673                 clear_metadata_file(_metadata_fd);
 674         }
 675 }
 676
 677 void lsu::registry_session::_generate_metadata()
 678 {
 679         trace_class::accept(*_metadata_generating_visitor);
 680 }
 681
 682 void lsu::registry_session::regenerate_metadata()
 683 {
 684         lttng::pthread::lock_guard registry_lock(_lock);
 685
 686         /* Resample the clock */
 687         _clock = lttng::make_unique<lsu::clock_class>();
 688
 689         _metadata_version++;
 690         _reset_metadata();
 691         _generate_metadata();
 692 }
 693
 694 /*
 695  * Lookup enumeration by enum ID.
 696  *
 697  * Note that there is no need to lock the registry session as this only
 698  * performs an RCU-protected look-up. The function also return an rcu-protected
 699  * reference, which ensures that the caller keeps the RCU read lock until it
 700  * disposes of the object.
 701  */
 702 lsu::registry_enum::const_rcu_protected_reference
 703 lsu::registry_session::enumeration(const char *enum_name, uint64_t enum_id) const
 704 {
 705         lsu::registry_enum *reg_enum = nullptr;
 706         struct lttng_ht_node_str *node;
 707         struct lttng_ht_iter iter;
 708         lttng::urcu::unique_read_lock rcu_lock;
 709         /*
 710          * Hack: only the name is used for hashing; the rest of the attributes
 711          * can be fudged.
 712          */
 713         lsu::registry_signed_enum reg_enum_lookup(enum_name, nullptr, 0);
 714
 715         ASSERT_RCU_READ_LOCKED();
 716
 717         reg_enum_lookup.id = enum_id;
 718         cds_lfht_lookup(_enums->ht,
 719                         ht_hash_enum((void *) &reg_enum_lookup, lttng_ht_seed),
 720                         ht_match_enum_id,
 721                         &reg_enum_lookup,
 722                         &iter.iter);
 723         node = lttng_ht_iter_get_node_str(&iter);
 724         if (!node) {
 725                 LTTNG_THROW_PROTOCOL_ERROR(fmt::format(
 726                         "Unknown enumeration referenced by application event field: enum name = `{}`, enum id = {}",
 727                         enum_name,
 728                         enum_id));
 729         }
 730
 731         DIAGNOSTIC_PUSH
 732         DIAGNOSTIC_IGNORE_INVALID_OFFSETOF
 733         reg_enum = lttng::utils::container_of(node, &lsu::registry_enum::node);
 734         DIAGNOSTIC_POP
 735
 736         return lsu::registry_enum::const_rcu_protected_reference{ *reg_enum, std::move(rcu_lock) };
 737 }
 738
 739 /*
 740  * Lookup enumeration by name and comparing enumeration entries.
 741  * Needs to be called from RCU read-side critical section.
 742  */
 743 lsu::registry_enum *
 744 lsu::registry_session::_lookup_enum(const lsu::registry_enum *reg_enum_lookup) const
 745 {
 746         lsu::registry_enum *reg_enum = nullptr;
 747         struct lttng_ht_node_str *node;
 748         struct lttng_ht_iter iter;
 749
 750         ASSERT_RCU_READ_LOCKED();
 751
 752         cds_lfht_lookup(_enums->ht,
 753                         ht_hash_enum((void *) reg_enum_lookup, lttng_ht_seed),
 754                         ht_match_enum,
 755                         reg_enum_lookup,
 756                         &iter.iter);
 757         node = lttng_ht_iter_get_node_str(&iter);
 758         if (!node) {
 759                 goto end;
 760         }
 761
 762         DIAGNOSTIC_PUSH
 763         DIAGNOSTIC_IGNORE_INVALID_OFFSETOF
 764         reg_enum = lttng::utils::container_of(node, &lsu::registry_enum::node);
 765         DIAGNOSTIC_POP
 766
 767 end:
 768         return reg_enum;
 769 }
 770
 771 /*
 772  * Create a lsu::registry_enum from the given parameters and add it to the
 773  * registry hash table, or find it if already there.
 774  *
 775  * Should be called with session registry mutex held.
 776  *
 777  * We receive ownership of entries.
 778  */
 779 void lsu::registry_session::create_or_find_enum(int session_objd,
 780                                                 const char *enum_name,
 781                                                 struct lttng_ust_ctl_enum_entry *raw_entries,
 782                                                 size_t nr_entries,
 783                                                 uint64_t *enum_id)
 784 {
 785         struct cds_lfht_node *nodep;
 786         lsu::registry_enum *reg_enum = nullptr, *old_reg_enum;
 787         lttng::urcu::read_lock_guard read_lock_guard;
 788         auto entries =
 789                 lttng::make_unique_wrapper<lttng_ust_ctl_enum_entry, lttng::free>(raw_entries);
 790
 791         LTTNG_ASSERT(enum_name);
 792
 793         /*
 794          * This should not happen but since it comes from the UST tracer, an
 795          * external party, don't assert and simply validate values.
 796          */
 797         if (session_objd < 0) {
 798                 LTTNG_THROW_INVALID_ARGUMENT_ERROR(fmt::format(
 799                         "Invalid parameters used to create or look-up enumeration from registry session: session_objd = {}",
 800                         session_objd));
 801         }
 802         if (nr_entries == 0) {
 803                 LTTNG_THROW_INVALID_ARGUMENT_ERROR(fmt::format(
 804                         "Invalid parameters used to create or look-up enumeration from registry session: nr_entries = {}",
 805                         nr_entries));
 806         }
 807         if (lttng_strnlen(enum_name, LTTNG_UST_ABI_SYM_NAME_LEN) == LTTNG_UST_ABI_SYM_NAME_LEN) {
 808                 LTTNG_THROW_INVALID_ARGUMENT_ERROR(
 809                         "Invalid parameters used to create or look-up enumeration from registry session: enumeration name is not null terminated");
 810         }
 811
 812         if (entries->start.signedness) {
 813                 reg_enum = new lsu::registry_signed_enum(enum_name, entries.get(), nr_entries);
 814         } else {
 815                 reg_enum = new lsu::registry_unsigned_enum(enum_name, entries.get(), nr_entries);
 816         }
 817
 818         old_reg_enum = _lookup_enum(reg_enum);
 819         if (old_reg_enum) {
 820                 DBG("enum %s already in sess_objd: %u", enum_name, session_objd);
 821                 /* Fall through. Use prior enum. */
 822                 destroy_enum(reg_enum);
 823                 reg_enum = old_reg_enum;
 824         } else {
 825                 DBG("UST registry creating enum: %s, sess_objd: %u", enum_name, session_objd);
 826                 if (_next_enum_id == -1ULL) {
 827                         destroy_enum(reg_enum);
 828                         LTTNG_THROW_ERROR(
 829                                 "Failed to allocate unique enumeration ID as it would overflow");
 830                 }
 831
 832                 reg_enum->id = _next_enum_id++;
 833                 nodep = cds_lfht_add_unique(_enums->ht,
 834                                             ht_hash_enum(reg_enum, lttng_ht_seed),
 835                                             ht_match_enum_id,
 836                                             reg_enum,
 837                                             &reg_enum->node.node);
 838                 LTTNG_ASSERT(nodep == &reg_enum->node.node);
 839         }
 840
 841         DBG("UST registry reply with enum %s with id %" PRIu64 " in sess_objd: %u",
 842             enum_name,
 843             reg_enum->id,
 844             session_objd);
 845         *enum_id = reg_enum->id;
 846 }