src/common/event.cpp

   1 /*
   2  * Copyright (C) 2018 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   3  *
   4  * SPDX-License-Identifier: LGPL-2.1-only
   5  *
   6  */
   7
   8 #include <common/align.hpp>
   9 #include <common/buffer-view.hpp>
  10 #include <common/compat/string.hpp>
  11 #include <common/dynamic-array.hpp>
  12 #include <common/dynamic-buffer.hpp>
  13 #include <common/error.hpp>
  14 #include <common/macros.hpp>
  15 #include <common/sessiond-comm/sessiond-comm.hpp>
  16
  17 #include <lttng/constant.h>
  18 #include <lttng/event-internal.hpp>
  19 #include <lttng/event.h>
  20 #include <lttng/lttng-error.h>
  21 #include <lttng/userspace-probe-internal.hpp>
  22
  23 namespace {
  24 struct event_list_element {
  25         struct lttng_event *event;
  26         struct lttng_event_exclusion *exclusions;
  27         char *filter_expression;
  28 };
  29 } /* namespace */
  30
  31 static void event_list_destructor(void *ptr)
  32 {
  33         struct event_list_element *element = (struct event_list_element *) ptr;
  34
  35         free(element->filter_expression);
  36         free(element->exclusions);
  37         lttng_event_destroy(element->event);
  38         free(element);
  39 }
  40
  41 struct lttng_event *lttng_event_copy(const struct lttng_event *event)
  42 {
  43         struct lttng_event *new_event;
  44         struct lttng_event_extended *new_event_extended;
  45
  46         new_event = zmalloc<lttng_event>();
  47         if (!new_event) {
  48                 PERROR("Error allocating event structure");
  49                 goto end;
  50         }
  51
  52         /* Copy the content of the old event. */
  53         memcpy(new_event, event, sizeof(*event));
  54
  55         /*
  56          * We need to create a new extended since the previous pointer is now
  57          * invalid.
  58          */
  59         new_event_extended = zmalloc<lttng_event_extended>();
  60         if (!new_event_extended) {
  61                 PERROR("Error allocating event extended structure");
  62                 goto error;
  63         }
  64
  65         new_event->extended.ptr = new_event_extended;
  66 end:
  67         return new_event;
  68 error:
  69         free(new_event);
  70         new_event = nullptr;
  71         goto end;
  72 }
  73
  74 static int lttng_event_probe_attr_serialize(const struct lttng_event_probe_attr *probe,
  75                                             struct lttng_payload *payload)
  76 {
  77         int ret;
  78         size_t symbol_name_len;
  79         struct lttng_event_probe_attr_comm comm = {};
  80
  81         symbol_name_len = lttng_strnlen(probe->symbol_name, sizeof(probe->symbol_name));
  82         if (symbol_name_len == sizeof(probe->symbol_name)) {
  83                 /* Not null-termintated. */
  84                 ret = -1;
  85                 goto end;
  86         }
  87
  88         /* Include the null terminator. */
  89         symbol_name_len += 1;
  90
  91         comm.symbol_name_len = (uint32_t) symbol_name_len;
  92         comm.addr = probe->addr;
  93         comm.offset = probe->addr;
  94
  95         ret = lttng_dynamic_buffer_append(&payload->buffer, &comm, sizeof(comm));
  96         if (ret < 0) {
  97                 ret = -1;
  98                 goto end;
  99         }
 100
 101         ret = lttng_dynamic_buffer_append(&payload->buffer, probe->symbol_name, symbol_name_len);
 102 end:
 103         return ret;
 104 }
 105
 106 static int lttng_event_function_attr_serialize(const struct lttng_event_function_attr *function,
 107                                                struct lttng_payload *payload)
 108 {
 109         int ret;
 110         size_t symbol_name_len;
 111         struct lttng_event_function_attr_comm comm;
 112
 113         comm.symbol_name_len = 0;
 114
 115         symbol_name_len = lttng_strnlen(function->symbol_name, sizeof(function->symbol_name));
 116         if (symbol_name_len == sizeof(function->symbol_name)) {
 117                 /* Not null-termintated. */
 118                 ret = -1;
 119                 goto end;
 120         }
 121
 122         /* Include the null terminator. */
 123         symbol_name_len += 1;
 124
 125         comm.symbol_name_len = (uint32_t) symbol_name_len;
 126
 127         ret = lttng_dynamic_buffer_append(&payload->buffer, &comm, sizeof(comm));
 128         if (ret < 0) {
 129                 ret = -1;
 130                 goto end;
 131         }
 132
 133         ret = lttng_dynamic_buffer_append(&payload->buffer, function->symbol_name, symbol_name_len);
 134 end:
 135         return ret;
 136 }
 137
 138 static ssize_t
 139 lttng_event_probe_attr_create_from_payload(struct lttng_payload_view *view,
 140                                            struct lttng_event_probe_attr **probe_attr)
 141 {
 142         ssize_t ret, offset = 0;
 143         const struct lttng_event_probe_attr_comm *comm;
 144         struct lttng_event_probe_attr *local_attr = nullptr;
 145         struct lttng_payload_view comm_view =
 146                 lttng_payload_view_from_view(view, offset, sizeof(*comm));
 147
 148         if (!lttng_payload_view_is_valid(&comm_view)) {
 149                 ret = -1;
 150                 goto end;
 151         }
 152
 153         comm = (typeof(comm)) comm_view.buffer.data;
 154         offset += sizeof(*comm);
 155
 156         local_attr = zmalloc<lttng_event_probe_attr>();
 157         if (local_attr == nullptr) {
 158                 ret = -1;
 159                 goto end;
 160         }
 161
 162         local_attr->addr = comm->addr;
 163         local_attr->offset = comm->offset;
 164
 165         {
 166                 const char *name;
 167                 struct lttng_payload_view name_view =
 168                         lttng_payload_view_from_view(view, offset, comm->symbol_name_len);
 169
 170                 if (!lttng_payload_view_is_valid(&name_view)) {
 171                         ret = -1;
 172                         goto end;
 173                 }
 174
 175                 name = name_view.buffer.data;
 176
 177                 if (!lttng_buffer_view_contains_string(
 178                             &name_view.buffer, name, comm->symbol_name_len)) {
 179                         ret = -1;
 180                         goto end;
 181                 }
 182
 183                 ret = lttng_strncpy(local_attr->symbol_name, name, sizeof(local_attr->symbol_name));
 184                 if (ret) {
 185                         ret = -1;
 186                         goto end;
 187                 }
 188
 189                 offset += comm->symbol_name_len;
 190         }
 191
 192         *probe_attr = local_attr;
 193         local_attr = nullptr;
 194         ret = offset;
 195 end:
 196         free(local_attr);
 197         return ret;
 198 }
 199
 200 static ssize_t
 201 lttng_event_function_attr_create_from_payload(struct lttng_payload_view *view,
 202                                               struct lttng_event_function_attr **function_attr)
 203 {
 204         ssize_t ret, offset = 0;
 205         const struct lttng_event_function_attr_comm *comm;
 206         struct lttng_event_function_attr *local_attr = nullptr;
 207         struct lttng_payload_view comm_view =
 208                 lttng_payload_view_from_view(view, offset, sizeof(*comm));
 209
 210         if (!lttng_payload_view_is_valid(&comm_view)) {
 211                 ret = -1;
 212                 goto end;
 213         }
 214
 215         comm = (typeof(comm)) view->buffer.data;
 216         offset += sizeof(*comm);
 217
 218         local_attr = zmalloc<lttng_event_function_attr>();
 219         if (local_attr == nullptr) {
 220                 ret = -1;
 221                 goto end;
 222         }
 223
 224         {
 225                 const char *name;
 226                 struct lttng_payload_view name_view =
 227                         lttng_payload_view_from_view(view, offset, comm->symbol_name_len);
 228
 229                 if (!lttng_payload_view_is_valid(&name_view)) {
 230                         ret = -1;
 231                         goto end;
 232                 }
 233
 234                 name = name_view.buffer.data;
 235
 236                 if (!lttng_buffer_view_contains_string(
 237                             &name_view.buffer, name, comm->symbol_name_len)) {
 238                         ret = -1;
 239                         goto end;
 240                 }
 241
 242                 ret = lttng_strncpy(local_attr->symbol_name, name, sizeof(local_attr->symbol_name));
 243                 if (ret) {
 244                         ret = -1;
 245                         goto end;
 246                 }
 247
 248                 offset += comm->symbol_name_len;
 249         }
 250
 251         *function_attr = local_attr;
 252         local_attr = nullptr;
 253         ret = offset;
 254 end:
 255         free(local_attr);
 256         return ret;
 257 }
 258
 259 static ssize_t lttng_event_exclusions_create_from_payload(struct lttng_payload_view *view,
 260                                                           uint32_t count,
 261                                                           struct lttng_event_exclusion **exclusions)
 262 {
 263         ssize_t ret, offset = 0;
 264         const size_t size = (count * LTTNG_SYMBOL_NAME_LEN);
 265         uint32_t i;
 266         const struct lttng_event_exclusion_comm *comm;
 267         struct lttng_event_exclusion *local_exclusions;
 268
 269         local_exclusions =
 270                 zmalloc<lttng_event_exclusion>(sizeof(struct lttng_event_exclusion) + size);
 271         if (!local_exclusions) {
 272                 ret = -1;
 273                 goto end;
 274         }
 275
 276         local_exclusions->count = count;
 277
 278         for (i = 0; i < count; i++) {
 279                 const char *string;
 280                 struct lttng_buffer_view string_view;
 281                 const struct lttng_buffer_view comm_view =
 282                         lttng_buffer_view_from_view(&view->buffer, offset, sizeof(*comm));
 283
 284                 if (!lttng_buffer_view_is_valid(&comm_view)) {
 285                         ret = -1;
 286                         goto end;
 287                 }
 288
 289                 comm = (typeof(comm)) comm_view.data;
 290                 offset += sizeof(*comm);
 291
 292                 string_view = lttng_buffer_view_from_view(&view->buffer, offset, comm->len);
 293
 294                 if (!lttng_buffer_view_is_valid(&string_view)) {
 295                         ret = -1;
 296                         goto end;
 297                 }
 298
 299                 string = string_view.data;
 300
 301                 if (!lttng_buffer_view_contains_string(&string_view, string, comm->len)) {
 302                         ret = -1;
 303                         goto end;
 304                 }
 305
 306                 ret = lttng_strncpy(LTTNG_EVENT_EXCLUSION_NAME_AT(local_exclusions, i),
 307                                     string,
 308                                     sizeof(LTTNG_EVENT_EXCLUSION_NAME_AT(local_exclusions, i)));
 309                 if (ret) {
 310                         ret = -1;
 311                         goto end;
 312                 }
 313
 314                 offset += comm->len;
 315         }
 316
 317         *exclusions = local_exclusions;
 318         local_exclusions = nullptr;
 319         ret = offset;
 320 end:
 321         free(local_exclusions);
 322         return ret;
 323 }
 324
 325 ssize_t lttng_event_create_from_payload(struct lttng_payload_view *view,
 326                                         struct lttng_event **out_event,
 327                                         struct lttng_event_exclusion **out_exclusion,
 328                                         char **out_filter_expression,
 329                                         struct lttng_bytecode **out_bytecode)
 330 {
 331         ssize_t ret, offset = 0;
 332         struct lttng_event *local_event = nullptr;
 333         struct lttng_event_exclusion *local_exclusions = nullptr;
 334         struct lttng_bytecode *local_bytecode = nullptr;
 335         char *local_filter_expression = nullptr;
 336         const struct lttng_event_comm *event_comm;
 337         struct lttng_event_function_attr *local_function_attr = nullptr;
 338         struct lttng_event_probe_attr *local_probe_attr = nullptr;
 339         struct lttng_userspace_probe_location *local_userspace_probe_location = nullptr;
 340
 341         /*
 342          * Only event is obligatory, the other output argument are optional and
 343          * depends on what the caller is interested in.
 344          */
 345         assert(out_event);
 346         assert(view);
 347
 348         {
 349                 struct lttng_payload_view comm_view =
 350                         lttng_payload_view_from_view(view, offset, sizeof(*event_comm));
 351
 352                 if (!lttng_payload_view_is_valid(&comm_view)) {
 353                         ret = -1;
 354                         goto end;
 355                 }
 356
 357                 /* lttng_event_comm header */
 358                 event_comm = (typeof(event_comm)) comm_view.buffer.data;
 359                 offset += sizeof(*event_comm);
 360         }
 361
 362         local_event = lttng_event_create();
 363         if (local_event == nullptr) {
 364                 ret = -1;
 365                 goto end;
 366         }
 367
 368         local_event->type = (enum lttng_event_type) event_comm->event_type;
 369         local_event->loglevel_type = (enum lttng_loglevel_type) event_comm->loglevel_type;
 370         local_event->loglevel = event_comm->loglevel;
 371         local_event->enabled = !!event_comm->enabled;
 372         local_event->pid = event_comm->pid;
 373         local_event->flags = (enum lttng_event_flag) event_comm->flags;
 374
 375         {
 376                 const char *name;
 377                 const struct lttng_buffer_view name_view =
 378                         lttng_buffer_view_from_view(&view->buffer, offset, event_comm->name_len);
 379
 380                 if (!lttng_buffer_view_is_valid(&name_view)) {
 381                         ret = -1;
 382                         goto end;
 383                 }
 384
 385                 name = (const char *) name_view.data;
 386
 387                 if (!lttng_buffer_view_contains_string(&name_view, name, event_comm->name_len)) {
 388                         ret = -1;
 389                         goto end;
 390                 }
 391
 392                 ret = lttng_strncpy(local_event->name, name, sizeof(local_event->name));
 393                 if (ret) {
 394                         ret = -1;
 395                         goto end;
 396                 }
 397
 398                 offset += event_comm->name_len;
 399         }
 400
 401         /* Exclusions */
 402         if (event_comm->exclusion_count == 0) {
 403                 goto deserialize_filter_expression;
 404         }
 405
 406         {
 407                 struct lttng_payload_view exclusions_view =
 408                         lttng_payload_view_from_view(view, offset, -1);
 409
 410                 if (!lttng_payload_view_is_valid(&exclusions_view)) {
 411                         ret = -1;
 412                         goto end;
 413                 }
 414
 415                 ret = lttng_event_exclusions_create_from_payload(
 416                         &exclusions_view, event_comm->exclusion_count, &local_exclusions);
 417                 if (ret < 0) {
 418                         ret = -1;
 419                         goto end;
 420                 }
 421                 offset += ret;
 422
 423                 local_event->exclusion = 1;
 424         }
 425
 426 deserialize_filter_expression:
 427
 428         if (event_comm->filter_expression_len == 0) {
 429                 if (event_comm->bytecode_len != 0) {
 430                         /*
 431                          * This is an invalid event payload.
 432                          *
 433                          * Filter expression without bytecode is possible but
 434                          * not the other way around.
 435                          * */
 436                         ret = -1;
 437                         goto end;
 438                 }
 439                 goto deserialize_event_type_payload;
 440         }
 441
 442         {
 443                 const char *filter_expression_buffer;
 444                 struct lttng_buffer_view filter_expression_view = lttng_buffer_view_from_view(
 445                         &view->buffer, offset, event_comm->filter_expression_len);
 446
 447                 if (!lttng_buffer_view_is_valid(&filter_expression_view)) {
 448                         ret = -1;
 449                         goto end;
 450                 }
 451
 452                 filter_expression_buffer = filter_expression_view.data;
 453
 454                 if (!lttng_buffer_view_contains_string(&filter_expression_view,
 455                                                        filter_expression_buffer,
 456                                                        event_comm->filter_expression_len)) {
 457                         ret = -1;
 458                         goto end;
 459                 }
 460
 461                 local_filter_expression =
 462                         lttng_strndup(filter_expression_buffer, event_comm->filter_expression_len);
 463                 if (!local_filter_expression) {
 464                         ret = -1;
 465                         goto end;
 466                 }
 467
 468                 local_event->filter = 1;
 469
 470                 offset += event_comm->filter_expression_len;
 471         }
 472
 473         if (event_comm->bytecode_len == 0) {
 474                 /*
 475                  * Filter expression can be present but without bytecode
 476                  * when dealing with event listing.
 477                  */
 478                 goto deserialize_event_type_payload;
 479         }
 480
 481         /* Bytecode */
 482         {
 483                 struct lttng_payload_view bytecode_view =
 484                         lttng_payload_view_from_view(view, offset, event_comm->bytecode_len);
 485
 486                 if (!lttng_payload_view_is_valid(&bytecode_view)) {
 487                         ret = -1;
 488                         goto end;
 489                 }
 490
 491                 local_bytecode = zmalloc<lttng_bytecode>(event_comm->bytecode_len);
 492                 if (!local_bytecode) {
 493                         ret = -1;
 494                         goto end;
 495                 }
 496
 497                 memcpy(local_bytecode, bytecode_view.buffer.data, event_comm->bytecode_len);
 498                 if ((local_bytecode->len + sizeof(*local_bytecode)) != event_comm->bytecode_len) {
 499                         ret = -1;
 500                         goto end;
 501                 }
 502
 503                 offset += event_comm->bytecode_len;
 504         }
 505
 506 deserialize_event_type_payload:
 507         /* Event type specific payload */
 508         switch (local_event->type) {
 509         case LTTNG_EVENT_FUNCTION:
 510                 /* Fallthrough */
 511         case LTTNG_EVENT_PROBE:
 512         {
 513                 struct lttng_payload_view probe_attr_view = lttng_payload_view_from_view(
 514                         view, offset, event_comm->lttng_event_probe_attr_len);
 515
 516                 if (event_comm->lttng_event_probe_attr_len == 0) {
 517                         ret = -1;
 518                         goto end;
 519                 }
 520
 521                 if (!lttng_payload_view_is_valid(&probe_attr_view)) {
 522                         ret = -1;
 523                         goto end;
 524                 }
 525
 526                 ret = lttng_event_probe_attr_create_from_payload(&probe_attr_view,
 527                                                                  &local_probe_attr);
 528                 if (ret < 0 || ret != event_comm->lttng_event_probe_attr_len) {
 529                         ret = -1;
 530                         goto end;
 531                 }
 532
 533                 /* Copy to the local event. */
 534                 memcpy(&local_event->attr.probe, local_probe_attr, sizeof(local_event->attr.probe));
 535
 536                 offset += ret;
 537                 break;
 538         }
 539         case LTTNG_EVENT_FUNCTION_ENTRY:
 540         {
 541                 struct lttng_payload_view function_attr_view = lttng_payload_view_from_view(
 542                         view, offset, event_comm->lttng_event_function_attr_len);
 543
 544                 if (event_comm->lttng_event_function_attr_len == 0) {
 545                         ret = -1;
 546                         goto end;
 547                 }
 548
 549                 if (!lttng_payload_view_is_valid(&function_attr_view)) {
 550                         ret = -1;
 551                         goto end;
 552                 }
 553
 554                 ret = lttng_event_function_attr_create_from_payload(&function_attr_view,
 555                                                                     &local_function_attr);
 556                 if (ret < 0 || ret != event_comm->lttng_event_function_attr_len) {
 557                         ret = -1;
 558                         goto end;
 559                 }
 560
 561                 /* Copy to the local event. */
 562                 memcpy(&local_event->attr.ftrace,
 563                        local_function_attr,
 564                        sizeof(local_event->attr.ftrace));
 565
 566                 offset += ret;
 567
 568                 break;
 569         }
 570         case LTTNG_EVENT_USERSPACE_PROBE:
 571         {
 572                 struct lttng_payload_view userspace_probe_location_view =
 573                         lttng_payload_view_from_view(
 574                                 view, offset, event_comm->userspace_probe_location_len);
 575
 576                 if (event_comm->userspace_probe_location_len == 0) {
 577                         ret = -1;
 578                         goto end;
 579                 }
 580
 581                 if (!lttng_payload_view_is_valid(&userspace_probe_location_view)) {
 582                         ret = -1;
 583                         goto end;
 584                 }
 585
 586                 ret = lttng_userspace_probe_location_create_from_payload(
 587                         &userspace_probe_location_view, &local_userspace_probe_location);
 588                 if (ret < 0) {
 589                         WARN("Failed to create a userspace probe location from the received buffer");
 590                         ret = -1;
 591                         goto end;
 592                 }
 593
 594                 if (ret != event_comm->userspace_probe_location_len) {
 595                         WARN("Userspace probe location from the received buffer is not the advertised length: header length = %" PRIu32
 596                              ", payload length = %zd",
 597                              event_comm->userspace_probe_location_len,
 598                              ret);
 599                         ret = -1;
 600                         goto end;
 601                 }
 602
 603                 /* Attach the probe location to the event. */
 604                 ret = lttng_event_set_userspace_probe_location(local_event,
 605                                                                local_userspace_probe_location);
 606                 if (ret) {
 607                         ret = LTTNG_ERR_PROBE_LOCATION_INVAL;
 608                         goto end;
 609                 }
 610
 611                 /*
 612                  * Userspace probe location object ownership transfered to the
 613                  * event object.
 614                  */
 615                 local_userspace_probe_location = nullptr;
 616                 offset += event_comm->userspace_probe_location_len;
 617                 break;
 618         }
 619         case LTTNG_EVENT_TRACEPOINT:
 620                 /* Fallthrough */
 621         case LTTNG_EVENT_ALL:
 622                 /* Fallthrough */
 623         case LTTNG_EVENT_SYSCALL:
 624                 /* Fallthrough */
 625         case LTTNG_EVENT_NOOP:
 626                 /* Nothing to do here */
 627                 break;
 628         default:
 629                 ret = LTTNG_ERR_UND;
 630                 goto end;
 631                 break;
 632         }
 633
 634         /* Transfer ownership to the caller. */
 635         *out_event = local_event;
 636         local_event = nullptr;
 637
 638         if (out_bytecode) {
 639                 *out_bytecode = local_bytecode;
 640                 local_bytecode = nullptr;
 641         }
 642
 643         if (out_exclusion) {
 644                 *out_exclusion = local_exclusions;
 645                 local_exclusions = nullptr;
 646         }
 647
 648         if (out_filter_expression) {
 649                 *out_filter_expression = local_filter_expression;
 650                 local_filter_expression = nullptr;
 651         }
 652
 653         ret = offset;
 654 end:
 655         lttng_event_destroy(local_event);
 656         lttng_userspace_probe_location_destroy(local_userspace_probe_location);
 657         free(local_filter_expression);
 658         free(local_exclusions);
 659         free(local_bytecode);
 660         free(local_function_attr);
 661         free(local_probe_attr);
 662         return ret;
 663 }
 664
 665 int lttng_event_serialize(const struct lttng_event *event,
 666                           unsigned int exclusion_count,
 667                           const char *const *exclusion_list,
 668                           const char *filter_expression,
 669                           size_t bytecode_len,
 670                           struct lttng_bytecode *bytecode,
 671                           struct lttng_payload *payload)
 672 {
 673         int ret;
 674         unsigned int i;
 675         size_t header_offset, size_before_payload;
 676         size_t name_len;
 677         struct lttng_event_comm event_comm = {};
 678         struct lttng_event_comm *header;
 679
 680         assert(event);
 681         assert(payload);
 682         assert(exclusion_count == 0 || exclusion_list);
 683
 684         /* Save the header location for later in-place header update. */
 685         header_offset = payload->buffer.size;
 686
 687         name_len = lttng_strnlen(event->name, sizeof(event->name));
 688         if (name_len == sizeof(event->name)) {
 689                 /* Event name is not NULL-terminated. */
 690                 ret = -1;
 691                 goto end;
 692         }
 693
 694         /* Add null termination. */
 695         name_len += 1;
 696
 697         if (exclusion_count > UINT32_MAX) {
 698                 /* Possible overflow. */
 699                 ret = -1;
 700                 goto end;
 701         }
 702
 703         if (bytecode_len > UINT32_MAX) {
 704                 /* Possible overflow. */
 705                 ret = -1;
 706                 goto end;
 707         }
 708
 709         event_comm.name_len = (uint32_t) name_len;
 710         event_comm.event_type = (int8_t) event->type;
 711         event_comm.loglevel_type = (int8_t) event->loglevel_type;
 712         event_comm.loglevel = (int32_t) event->loglevel;
 713         event_comm.enabled = (int8_t) event->enabled;
 714         event_comm.pid = (int32_t) event->pid;
 715         event_comm.exclusion_count = (uint32_t) exclusion_count;
 716         event_comm.bytecode_len = (uint32_t) bytecode_len;
 717         event_comm.flags = (int32_t) event->flags;
 718
 719         if (filter_expression) {
 720                 event_comm.filter_expression_len = strlen(filter_expression) + 1;
 721         }
 722
 723         /* Header */
 724         ret = lttng_dynamic_buffer_append(&payload->buffer, &event_comm, sizeof(event_comm));
 725         if (ret) {
 726                 goto end;
 727         }
 728
 729         /* Event name */
 730         ret = lttng_dynamic_buffer_append(&payload->buffer, event->name, name_len);
 731         if (ret) {
 732                 goto end;
 733         }
 734
 735         /* Exclusions */
 736         for (i = 0; i < exclusion_count; i++) {
 737                 const size_t exclusion_len =
 738                         lttng_strnlen(*(exclusion_list + i), LTTNG_SYMBOL_NAME_LEN);
 739                 struct lttng_event_exclusion_comm exclusion_header = {};
 740
 741                 exclusion_header.len = (uint32_t) exclusion_len + 1;
 742
 743                 if (exclusion_len == LTTNG_SYMBOL_NAME_LEN) {
 744                         /* Exclusion is not NULL-terminated. */
 745                         ret = -1;
 746                         goto end;
 747                 }
 748
 749                 ret = lttng_dynamic_buffer_append(
 750                         &payload->buffer, &exclusion_header, sizeof(exclusion_header));
 751                 if (ret) {
 752                         goto end;
 753                 }
 754
 755                 ret = lttng_dynamic_buffer_append(
 756                         &payload->buffer, *(exclusion_list + i), exclusion_len + 1);
 757                 if (ret) {
 758                         goto end;
 759                 }
 760         }
 761
 762         /* Filter expression and its bytecode */
 763         if (filter_expression) {
 764                 ret = lttng_dynamic_buffer_append(
 765                         &payload->buffer, filter_expression, event_comm.filter_expression_len);
 766                 if (ret) {
 767                         goto end;
 768                 }
 769
 770                 /*
 771                  * Bytecode can be absent when we serialize to the client
 772                  * for listing.
 773                  */
 774                 if (bytecode) {
 775                         ret = lttng_dynamic_buffer_append(&payload->buffer, bytecode, bytecode_len);
 776                         if (ret) {
 777                                 goto end;
 778                         }
 779                 }
 780         }
 781
 782         size_before_payload = payload->buffer.size;
 783
 784         /* Event type specific payload */
 785         switch (event->type) {
 786         case LTTNG_EVENT_FUNCTION:
 787                 /* Fallthrough */
 788         case LTTNG_EVENT_PROBE:
 789                 ret = lttng_event_probe_attr_serialize(&event->attr.probe, payload);
 790                 if (ret) {
 791                         ret = -1;
 792                         goto end;
 793                 }
 794
 795                 header =
 796                         (struct lttng_event_comm *) ((char *) payload->buffer.data + header_offset);
 797                 header->lttng_event_probe_attr_len = payload->buffer.size - size_before_payload;
 798
 799                 break;
 800         case LTTNG_EVENT_FUNCTION_ENTRY:
 801                 ret = lttng_event_function_attr_serialize(&event->attr.ftrace, payload);
 802                 if (ret) {
 803                         ret = -1;
 804                         goto end;
 805                 }
 806
 807                 /* Update the lttng_event_function_attr len. */
 808                 header =
 809                         (struct lttng_event_comm *) ((char *) payload->buffer.data + header_offset);
 810                 header->lttng_event_function_attr_len = payload->buffer.size - size_before_payload;
 811
 812                 break;
 813         case LTTNG_EVENT_USERSPACE_PROBE:
 814         {
 815                 const struct lttng_event_extended *ev_ext =
 816                         (const struct lttng_event_extended *) event->extended.ptr;
 817
 818                 assert(event->extended.ptr);
 819                 assert(ev_ext->probe_location);
 820
 821                 size_before_payload = payload->buffer.size;
 822                 if (ev_ext->probe_location) {
 823                         /*
 824                          * lttng_userspace_probe_location_serialize returns the
 825                          * number of bytes that were appended to the buffer.
 826                          */
 827                         ret = lttng_userspace_probe_location_serialize(ev_ext->probe_location,
 828                                                                        payload);
 829                         if (ret < 0) {
 830                                 goto end;
 831                         }
 832
 833                         ret = 0;
 834
 835                         /* Update the userspace probe location len. */
 836                         header = (struct lttng_event_comm *) ((char *) payload->buffer.data +
 837                                                               header_offset);
 838                         header->userspace_probe_location_len =
 839                                 payload->buffer.size - size_before_payload;
 840                 }
 841                 break;
 842         }
 843         case LTTNG_EVENT_TRACEPOINT:
 844                 /* Fallthrough */
 845         case LTTNG_EVENT_ALL:
 846                 /* Fallthrough */
 847         default:
 848                 /* Nothing to do here. */
 849                 break;
 850         }
 851
 852 end:
 853         return ret;
 854 }
 855
 856 static ssize_t lttng_event_context_app_populate_from_payload(const struct lttng_payload_view *view,
 857                                                              struct lttng_event_context *event_ctx)
 858 {
 859         ssize_t ret, offset = 0;
 860         const struct lttng_event_context_app_comm *comm;
 861         char *provider_name = nullptr, *context_name = nullptr;
 862         size_t provider_name_len, context_name_len;
 863         const struct lttng_buffer_view comm_view =
 864                 lttng_buffer_view_from_view(&view->buffer, offset, sizeof(*comm));
 865
 866         assert(event_ctx->ctx == LTTNG_EVENT_CONTEXT_APP_CONTEXT);
 867
 868         if (!lttng_buffer_view_is_valid(&comm_view)) {
 869                 ret = -1;
 870                 goto end;
 871         }
 872
 873         comm = (typeof(comm)) comm_view.data;
 874         offset += sizeof(*comm);
 875
 876         provider_name_len = comm->provider_name_len;
 877         context_name_len = comm->ctx_name_len;
 878
 879         if (provider_name_len == 0 || context_name_len == 0) {
 880                 /*
 881                  * Application provider and context names MUST
 882                  * be provided.
 883                  */
 884                 ret = -1;
 885                 goto end;
 886         }
 887
 888         {
 889                 const char *name;
 890                 const struct lttng_buffer_view provider_name_view =
 891                         lttng_buffer_view_from_view(&view->buffer, offset, provider_name_len);
 892
 893                 if (!lttng_buffer_view_is_valid(&provider_name_view)) {
 894                         ret = -1;
 895                         goto end;
 896                 }
 897
 898                 name = provider_name_view.data;
 899
 900                 if (!lttng_buffer_view_contains_string(
 901                             &provider_name_view, name, provider_name_len)) {
 902                         ret = -1;
 903                         goto end;
 904                 }
 905
 906                 provider_name = lttng_strndup(name, provider_name_len);
 907                 if (!provider_name) {
 908                         ret = -1;
 909                         goto end;
 910                 }
 911
 912                 offset += provider_name_len;
 913         }
 914
 915         {
 916                 const char *name;
 917                 const struct lttng_buffer_view context_name_view =
 918                         lttng_buffer_view_from_view(&view->buffer, offset, context_name_len);
 919
 920                 if (!lttng_buffer_view_is_valid(&context_name_view)) {
 921                         ret = -1;
 922                         goto end;
 923                 }
 924
 925                 name = context_name_view.data;
 926
 927                 if (!lttng_buffer_view_contains_string(&context_name_view, name, context_name_len)) {
 928                         ret = -1;
 929                         goto end;
 930                 }
 931
 932                 context_name = lttng_strndup(name, context_name_len);
 933                 if (!context_name) {
 934                         ret = -1;
 935                         goto end;
 936                 }
 937
 938                 offset += context_name_len;
 939         }
 940
 941         /* Transfer ownership of the strings */
 942         event_ctx->u.app_ctx.provider_name = provider_name;
 943         event_ctx->u.app_ctx.ctx_name = context_name;
 944         provider_name = nullptr;
 945         context_name = nullptr;
 946
 947         ret = offset;
 948 end:
 949         free(provider_name);
 950         free(context_name);
 951
 952         return ret;
 953 }
 954
 955 static ssize_t
 956 lttng_event_context_perf_counter_populate_from_payload(const struct lttng_payload_view *view,
 957                                                        struct lttng_event_context *event_ctx)
 958 {
 959         int ret;
 960         ssize_t consumed, offset = 0;
 961         const struct lttng_event_context_perf_counter_comm *comm;
 962         size_t name_len;
 963         const struct lttng_buffer_view comm_view =
 964                 lttng_buffer_view_from_view(&view->buffer, offset, sizeof(*comm));
 965
 966         assert(event_ctx->ctx == LTTNG_EVENT_CONTEXT_PERF_COUNTER ||
 967                event_ctx->ctx == LTTNG_EVENT_CONTEXT_PERF_THREAD_COUNTER ||
 968                event_ctx->ctx == LTTNG_EVENT_CONTEXT_PERF_CPU_COUNTER);
 969
 970         if (!lttng_buffer_view_is_valid(&comm_view)) {
 971                 consumed = -1;
 972                 goto end;
 973         }
 974
 975         comm = (typeof(comm)) comm_view.data;
 976         offset += sizeof(*comm);
 977
 978         name_len = comm->name_len;
 979
 980         {
 981                 const char *name;
 982                 const struct lttng_buffer_view provider_name_view =
 983                         lttng_buffer_view_from_view(&view->buffer, offset, name_len);
 984
 985                 if (!lttng_buffer_view_is_valid(&provider_name_view)) {
 986                         consumed = -1;
 987                         goto end;
 988                 }
 989
 990                 name = provider_name_view.data;
 991
 992                 if (!lttng_buffer_view_contains_string(&provider_name_view, name, name_len)) {
 993                         consumed = -1;
 994                         goto end;
 995                 }
 996
 997                 ret = lttng_strncpy(event_ctx->u.perf_counter.name,
 998                                     name,
 999                                     sizeof(event_ctx->u.perf_counter.name));
1000                 if (ret) {
1001                         consumed = -1;
1002                         goto end;
1003                 }
1004                 offset += name_len;
1005         }
1006
1007         event_ctx->u.perf_counter.config = comm->config;
1008         event_ctx->u.perf_counter.type = comm->type;
1009
1010         consumed = offset;
1011
1012 end:
1013         return consumed;
1014 }
1015
1016 ssize_t lttng_event_context_create_from_payload(struct lttng_payload_view *view,
1017                                                 struct lttng_event_context **event_ctx)
1018 {
1019         ssize_t ret, offset = 0;
1020         const struct lttng_event_context_comm *comm;
1021         struct lttng_event_context *local_context = nullptr;
1022         struct lttng_buffer_view comm_view =
1023                 lttng_buffer_view_from_view(&view->buffer, offset, sizeof(*comm));
1024
1025         assert(event_ctx);
1026         assert(view);
1027
1028         if (!lttng_buffer_view_is_valid(&comm_view)) {
1029                 ret = -1;
1030                 goto end;
1031         }
1032
1033         comm = (typeof(comm)) comm_view.data;
1034         offset += sizeof(*comm);
1035
1036         local_context = zmalloc<lttng_event_context>();
1037         if (!local_context) {
1038                 ret = -1;
1039                 goto end;
1040         }
1041
1042         local_context->ctx = (lttng_event_context_type) comm->type;
1043
1044         {
1045                 struct lttng_payload_view subtype_view =
1046                         lttng_payload_view_from_view(view, offset, -1);
1047
1048                 switch (local_context->ctx) {
1049                 case LTTNG_EVENT_CONTEXT_APP_CONTEXT:
1050                         ret = lttng_event_context_app_populate_from_payload(&subtype_view,
1051                                                                             local_context);
1052                         break;
1053                 case LTTNG_EVENT_CONTEXT_PERF_COUNTER:
1054                 case LTTNG_EVENT_CONTEXT_PERF_THREAD_COUNTER:
1055                 case LTTNG_EVENT_CONTEXT_PERF_CPU_COUNTER:
1056                         ret = lttng_event_context_perf_counter_populate_from_payload(&subtype_view,
1057                                                                                      local_context);
1058                         break;
1059                 default:
1060                         /* Nothing else to deserialize. */
1061                         ret = 0;
1062                         break;
1063                 }
1064         }
1065
1066         if (ret < 0) {
1067                 goto end;
1068         }
1069
1070         offset += ret;
1071
1072         *event_ctx = local_context;
1073         local_context = nullptr;
1074         ret = offset;
1075
1076 end:
1077         free(local_context);
1078         return ret;
1079 }
1080
1081 static int lttng_event_context_app_serialize(struct lttng_event_context *context,
1082                                              struct lttng_payload *payload)
1083 {
1084         int ret;
1085         struct lttng_event_context_app_comm comm = {};
1086         size_t provider_len, ctx_len;
1087         const char *provider_name;
1088         const char *ctx_name;
1089
1090         assert(payload);
1091         assert(context);
1092         assert(context->ctx == LTTNG_EVENT_CONTEXT_APP_CONTEXT);
1093
1094         provider_name = context->u.app_ctx.provider_name;
1095         ctx_name = context->u.app_ctx.ctx_name;
1096
1097         if (!provider_name || !ctx_name) {
1098                 ret = -LTTNG_ERR_INVALID;
1099                 goto end;
1100         }
1101
1102         provider_len = strlen(provider_name);
1103         if (provider_len == 0) {
1104                 ret = -LTTNG_ERR_INVALID;
1105                 goto end;
1106         }
1107
1108         /* Include the null terminator. */
1109         provider_len += 1;
1110         comm.provider_name_len = provider_len;
1111
1112         ctx_len = strlen(ctx_name);
1113         if (ctx_len == 0) {
1114                 ret = -LTTNG_ERR_INVALID;
1115                 goto end;
1116         }
1117
1118         /* Include the null terminator. */
1119         ctx_len += 1;
1120         comm.ctx_name_len = ctx_len;
1121
1122         /* Header */
1123         ret = lttng_dynamic_buffer_append(&payload->buffer, &comm, sizeof(comm));
1124         if (ret) {
1125                 ret = -1;
1126                 goto end;
1127         }
1128
1129         ret = lttng_dynamic_buffer_append(&payload->buffer, provider_name, provider_len);
1130         if (ret) {
1131                 ret = -1;
1132                 goto end;
1133         }
1134
1135         ret = lttng_dynamic_buffer_append(&payload->buffer, ctx_name, ctx_len);
1136         if (ret) {
1137                 ret = -1;
1138                 goto end;
1139         }
1140
1141 end:
1142         return ret;
1143 }
1144
1145 static int lttng_event_context_perf_counter_serialize(struct lttng_event_perf_counter_ctx *context,
1146                                                       struct lttng_payload *payload)
1147 {
1148         int ret;
1149         struct lttng_event_context_perf_counter_comm comm = {};
1150
1151         assert(payload);
1152         assert(context);
1153
1154         comm.config = context->config;
1155         comm.type = context->type;
1156         comm.name_len = lttng_strnlen(context->name, sizeof(context->name));
1157
1158         if (comm.name_len == sizeof(context->name)) {
1159                 ret = -1;
1160                 goto end;
1161         }
1162
1163         /* Include the null terminator. */
1164         comm.name_len += 1;
1165
1166         /* Header */
1167         ret = lttng_dynamic_buffer_append(&payload->buffer, &comm, sizeof(comm));
1168         if (ret) {
1169                 ret = -1;
1170                 goto end;
1171         }
1172
1173         ret = lttng_dynamic_buffer_append(&payload->buffer, context->name, comm.name_len);
1174         if (ret) {
1175                 ret = -1;
1176                 goto end;
1177         }
1178
1179 end:
1180         return ret;
1181 }
1182
1183 int lttng_event_context_serialize(struct lttng_event_context *context,
1184                                   struct lttng_payload *payload)
1185 {
1186         int ret;
1187         struct lttng_event_context_comm context_comm;
1188
1189         context_comm.type = 0;
1190
1191         assert(context);
1192         assert(payload);
1193
1194         context_comm.type = (uint32_t) context->ctx;
1195
1196         /* Header */
1197         ret = lttng_dynamic_buffer_append(&payload->buffer, &context_comm, sizeof(context_comm));
1198         if (ret) {
1199                 goto end;
1200         }
1201
1202         switch (context->ctx) {
1203         case LTTNG_EVENT_CONTEXT_APP_CONTEXT:
1204                 ret = lttng_event_context_app_serialize(context, payload);
1205                 break;
1206         case LTTNG_EVENT_CONTEXT_PERF_COUNTER:
1207         case LTTNG_EVENT_CONTEXT_PERF_THREAD_COUNTER:
1208         case LTTNG_EVENT_CONTEXT_PERF_CPU_COUNTER:
1209                 ret = lttng_event_context_perf_counter_serialize(&context->u.perf_counter, payload);
1210                 break;
1211         default:
1212                 /* Nothing else to serialize. */
1213                 break;
1214         }
1215
1216         if (ret) {
1217                 goto end;
1218         }
1219
1220 end:
1221         return ret;
1222 }
1223
1224 void lttng_event_context_destroy(struct lttng_event_context *context)
1225 {
1226         if (!context) {
1227                 return;
1228         }
1229
1230         if (context->ctx == LTTNG_EVENT_CONTEXT_APP_CONTEXT) {
1231                 free(context->u.app_ctx.provider_name);
1232                 free(context->u.app_ctx.ctx_name);
1233         }
1234
1235         free(context);
1236 }
1237
1238 /*
1239  * This is a specialized populate for lttng_event_field since it ignores
1240  * the extension field of the lttng_event struct and simply copies what it can
1241  * to the internal struct lttng_event of a lttng_event_field.
1242  */
1243 static void lttng_event_field_populate_lttng_event_from_event(const struct lttng_event *src,
1244                                                               struct lttng_event *destination)
1245 {
1246         memcpy(destination, src, sizeof(*destination));
1247
1248         /* Remove all possible dynamic data from the destination event rule. */
1249         destination->extended.ptr = nullptr;
1250 }
1251
1252 ssize_t lttng_event_field_create_from_payload(struct lttng_payload_view *view,
1253                                               struct lttng_event_field **field)
1254 {
1255         ssize_t ret, offset = 0;
1256         struct lttng_event_field *local_event_field = nullptr;
1257         struct lttng_event *event = nullptr;
1258         const struct lttng_event_field_comm *comm;
1259         const char *name = nullptr;
1260
1261         assert(field);
1262         assert(view);
1263
1264         {
1265                 const struct lttng_buffer_view comm_view =
1266                         lttng_buffer_view_from_view(&view->buffer, offset, sizeof(*comm));
1267
1268                 if (!lttng_buffer_view_is_valid(&comm_view)) {
1269                         ret = -1;
1270                         goto end;
1271                 }
1272
1273                 /* lttng_event_field_comm header */
1274                 comm = (const lttng_event_field_comm *) comm_view.data;
1275                 offset += sizeof(*comm);
1276         }
1277
1278         local_event_field = zmalloc<lttng_event_field>();
1279         if (!local_event_field) {
1280                 ret = -1;
1281                 goto end;
1282         }
1283
1284         local_event_field->type = (lttng_event_field_type) comm->type;
1285         local_event_field->nowrite = comm->nowrite;
1286
1287         /* Field name */
1288         {
1289                 const struct lttng_buffer_view name_view =
1290                         lttng_buffer_view_from_view(&view->buffer, offset, comm->name_len);
1291
1292                 if (!lttng_buffer_view_is_valid(&name_view)) {
1293                         ret = -1;
1294                         goto end;
1295                 }
1296
1297                 name = name_view.data;
1298
1299                 if (!lttng_buffer_view_contains_string(&name_view, name_view.data, comm->name_len)) {
1300                         ret = -1;
1301                         goto end;
1302                 }
1303
1304                 if (comm->name_len > LTTNG_SYMBOL_NAME_LEN - 1) {
1305                         /* Name is too long.*/
1306                         ret = -1;
1307                         goto end;
1308                 }
1309
1310                 offset += comm->name_len;
1311         }
1312
1313         /* Event */
1314         {
1315                 struct lttng_payload_view event_view =
1316                         lttng_payload_view_from_view(view, offset, comm->event_len);
1317
1318                 if (!lttng_payload_view_is_valid(&event_view)) {
1319                         ret = -1;
1320                         goto end;
1321                 }
1322
1323                 ret = lttng_event_create_from_payload(
1324                         &event_view, &event, nullptr, nullptr, nullptr);
1325                 if (ret != comm->event_len) {
1326                         ret = -1;
1327                         goto end;
1328                 }
1329
1330                 offset += ret;
1331         }
1332
1333         assert(name);
1334         assert(event);
1335
1336         if (lttng_strncpy(
1337                     local_event_field->field_name, name, sizeof(local_event_field->field_name))) {
1338                 ret = -1;
1339                 goto end;
1340         }
1341
1342         lttng_event_field_populate_lttng_event_from_event(event, &local_event_field->event);
1343
1344         *field = local_event_field;
1345         local_event_field = nullptr;
1346         ret = offset;
1347 end:
1348         lttng_event_destroy(event);
1349         free(local_event_field);
1350         return ret;
1351 }
1352
1353 int lttng_event_field_serialize(const struct lttng_event_field *field,
1354                                 struct lttng_payload *payload)
1355 {
1356         int ret;
1357         size_t header_offset, size_before_event;
1358         size_t name_len;
1359         struct lttng_event_field_comm event_field_comm = {};
1360         struct lttng_event_field_comm *header;
1361
1362         assert(field);
1363         assert(payload);
1364
1365         /* Save the header location for later in-place header update. */
1366         header_offset = payload->buffer.size;
1367
1368         name_len = strnlen(field->field_name, sizeof(field->field_name));
1369         if (name_len == sizeof(field->field_name)) {
1370                 /* Event name is not NULL-terminated. */
1371                 ret = -1;
1372                 goto end;
1373         }
1374
1375         /* Add null termination. */
1376         name_len += 1;
1377
1378         event_field_comm.type = field->type;
1379         event_field_comm.nowrite = (uint8_t) field->nowrite;
1380         event_field_comm.name_len = name_len;
1381
1382         /* Header */
1383         ret = lttng_dynamic_buffer_append(
1384                 &payload->buffer, &event_field_comm, sizeof(event_field_comm));
1385         if (ret) {
1386                 goto end;
1387         }
1388
1389         /* Field name */
1390         ret = lttng_dynamic_buffer_append(&payload->buffer, field->field_name, name_len);
1391         if (ret) {
1392                 goto end;
1393         }
1394
1395         size_before_event = payload->buffer.size;
1396         ret = lttng_event_serialize(&field->event, 0, nullptr, nullptr, 0, nullptr, payload);
1397         if (ret) {
1398                 ret = -1;
1399                 goto end;
1400         }
1401
1402         /* Update the event len. */
1403         header = (struct lttng_event_field_comm *) ((char *) payload->buffer.data + header_offset);
1404         header->event_len = payload->buffer.size - size_before_event;
1405
1406 end:
1407         return ret;
1408 }
1409
1410 static enum lttng_error_code compute_flattened_size(struct lttng_dynamic_pointer_array *events,
1411                                                     size_t *size)
1412 {
1413         enum lttng_error_code ret_code;
1414         int ret = 0;
1415         size_t storage_req, event_count, i;
1416
1417         assert(size);
1418         assert(events);
1419
1420         event_count = lttng_dynamic_pointer_array_get_count(events);
1421
1422         /* The basic struct lttng_event */
1423         storage_req = event_count * sizeof(struct lttng_event);
1424
1425         /* The struct·lttng_event_extended */
1426         storage_req += event_count * sizeof(struct lttng_event_extended);
1427
1428         for (i = 0; i < event_count; i++) {
1429                 int probe_storage_req = 0;
1430                 const struct event_list_element *element =
1431                         (const struct event_list_element *) lttng_dynamic_pointer_array_get_pointer(
1432                                 events, i);
1433                 const struct lttng_userspace_probe_location *location = nullptr;
1434
1435                 location = lttng_event_get_userspace_probe_location(element->event);
1436                 if (location) {
1437                         ret = lttng_userspace_probe_location_flatten(location, nullptr);
1438                         if (ret < 0) {
1439                                 ret_code = LTTNG_ERR_PROBE_LOCATION_INVAL;
1440                                 goto end;
1441                         }
1442
1443                         probe_storage_req = ret;
1444                 }
1445
1446                 if (element->filter_expression) {
1447                         storage_req += strlen(element->filter_expression) + 1;
1448                 }
1449
1450                 if (element->exclusions) {
1451                         storage_req += element->exclusions->count * LTTNG_SYMBOL_NAME_LEN;
1452                 }
1453
1454                 /* Padding to ensure the flat probe is aligned. */
1455                 storage_req = lttng_align_ceil(storage_req, sizeof(uint64_t));
1456                 storage_req += probe_storage_req;
1457         }
1458
1459         *size = storage_req;
1460         ret_code = LTTNG_OK;
1461
1462 end:
1463         return ret_code;
1464 }
1465
1466 /*
1467  * Flatten a list of struct lttng_event.
1468  *
1469  * The buffer that is returned to the API client  must contain a "flat" version
1470  * of the events that are returned. In other words, all pointers within an
1471  * lttng_event must point to a location within the returned buffer so that the
1472  * user may free everything by simply calling free() on the returned buffer.
1473  * This is needed in order to maintain API compatibility.
1474  *
1475  * A first pass is performed to compute the size of the buffer that must be
1476  * allocated. A second pass is then performed to setup the returned events so
1477  * that their members always point within the buffer.
1478  *
1479  * The layout of the returned buffer is as follows:
1480  *   - struct lttng_event[nb_events],
1481  *   - nb_events times the following:
1482  *     - struct lttng_event_extended,
1483  *     - filter_expression
1484  *     - exclusions
1485  *     - padding to align to 64-bits
1486  *     - flattened version of userspace_probe_location
1487  */
1488 static enum lttng_error_code flatten_lttng_events(struct lttng_dynamic_pointer_array *events,
1489                                                   struct lttng_event **flattened_events)
1490 {
1491         enum lttng_error_code ret_code;
1492         int ret, i;
1493         size_t storage_req;
1494         struct lttng_dynamic_buffer local_flattened_events;
1495         int nb_events;
1496
1497         assert(events);
1498         assert(flattened_events);
1499
1500         lttng_dynamic_buffer_init(&local_flattened_events);
1501         nb_events = lttng_dynamic_pointer_array_get_count(events);
1502
1503         ret_code = compute_flattened_size(events, &storage_req);
1504         if (ret_code != LTTNG_OK) {
1505                 goto end;
1506         }
1507
1508         /*
1509          * We must ensure that "local_flattened_events" is never resized so as
1510          * to preserve the validity of the flattened objects.
1511          */
1512         ret = lttng_dynamic_buffer_set_capacity(&local_flattened_events, storage_req);
1513         if (ret) {
1514                 ret_code = LTTNG_ERR_NOMEM;
1515                 goto end;
1516         }
1517
1518         /* Start by laying the struct lttng_event */
1519         for (i = 0; i < nb_events; i++) {
1520                 const struct event_list_element *element =
1521                         (const struct event_list_element *) lttng_dynamic_pointer_array_get_pointer(
1522                                 events, i);
1523
1524                 if (!element) {
1525                         ret_code = LTTNG_ERR_FATAL;
1526                         goto end;
1527                 }
1528
1529                 ret = lttng_dynamic_buffer_append(
1530                         &local_flattened_events, element->event, sizeof(struct lttng_event));
1531                 if (ret) {
1532                         ret_code = LTTNG_ERR_NOMEM;
1533                         goto end;
1534                 }
1535         }
1536
1537         for (i = 0; i < nb_events; i++) {
1538                 const struct event_list_element *element =
1539                         (const struct event_list_element *) lttng_dynamic_pointer_array_get_pointer(
1540                                 events, i);
1541                 struct lttng_event *event =
1542                         (struct lttng_event *) (local_flattened_events.data +
1543                                                 (sizeof(struct lttng_event) * i));
1544                 struct lttng_event_extended *event_extended =
1545                         (struct lttng_event_extended *) (local_flattened_events.data +
1546                                                          local_flattened_events.size);
1547                 const struct lttng_userspace_probe_location *location = nullptr;
1548
1549                 assert(element);
1550
1551                 /* Insert struct lttng_event_extended. */
1552                 ret = lttng_dynamic_buffer_set_size(&local_flattened_events,
1553                                                     local_flattened_events.size +
1554                                                             sizeof(*event_extended));
1555                 if (ret) {
1556                         ret_code = LTTNG_ERR_NOMEM;
1557                         goto end;
1558                 }
1559                 event->extended.ptr = event_extended;
1560
1561                 /* Insert filter expression. */
1562                 if (element->filter_expression) {
1563                         const size_t len = strlen(element->filter_expression) + 1;
1564
1565                         event_extended->filter_expression =
1566                                 local_flattened_events.data + local_flattened_events.size;
1567                         ret = lttng_dynamic_buffer_append(
1568                                 &local_flattened_events, element->filter_expression, len);
1569                         if (ret) {
1570                                 ret_code = LTTNG_ERR_NOMEM;
1571                                 goto end;
1572                         }
1573                 }
1574
1575                 /* Insert exclusions. */
1576                 if (element->exclusions) {
1577                         event_extended->exclusions.count = element->exclusions->count;
1578                         event_extended->exclusions.strings =
1579                                 local_flattened_events.data + local_flattened_events.size;
1580
1581                         ret = lttng_dynamic_buffer_append(&local_flattened_events,
1582                                                           element->exclusions->names,
1583                                                           element->exclusions->count *
1584                                                                   LTTNG_SYMBOL_NAME_LEN);
1585                         if (ret) {
1586                                 ret_code = LTTNG_ERR_NOMEM;
1587                                 goto end;
1588                         }
1589                 }
1590
1591                 /* Insert padding to align to 64-bits. */
1592                 ret = lttng_dynamic_buffer_set_size(&local_flattened_events,
1593                                                     lttng_align_ceil(local_flattened_events.size,
1594                                                                      sizeof(uint64_t)));
1595                 if (ret) {
1596                         ret_code = LTTNG_ERR_NOMEM;
1597                         goto end;
1598                 }
1599
1600                 location = lttng_event_get_userspace_probe_location(element->event);
1601                 if (location) {
1602                         event_extended->probe_location = (struct lttng_userspace_probe_location
1603                                                                   *) (local_flattened_events.data +
1604                                                                       local_flattened_events.size);
1605                         ret = lttng_userspace_probe_location_flatten(location,
1606                                                                      &local_flattened_events);
1607                         if (ret < 0) {
1608                                 ret_code = LTTNG_ERR_PROBE_LOCATION_INVAL;
1609                                 goto end;
1610                         }
1611                 }
1612         }
1613
1614         /* Don't reset local_flattened_events buffer as we return its content. */
1615         *flattened_events = (struct lttng_event *) local_flattened_events.data;
1616         lttng_dynamic_buffer_init(&local_flattened_events);
1617         ret_code = LTTNG_OK;
1618 end:
1619         lttng_dynamic_buffer_reset(&local_flattened_events);
1620         return ret_code;
1621 }
1622
1623 static enum lttng_error_code
1624 event_list_create_from_payload(struct lttng_payload_view *view,
1625                                unsigned int count,
1626                                struct lttng_dynamic_pointer_array *event_list)
1627 {
1628         enum lttng_error_code ret_code;
1629         int ret;
1630         unsigned int i;
1631         int offset = 0;
1632
1633         assert(view);
1634         assert(event_list);
1635
1636         for (i = 0; i < count; i++) {
1637                 ssize_t event_size;
1638                 struct lttng_payload_view event_view =
1639                         lttng_payload_view_from_view(view, offset, -1);
1640                 struct event_list_element *element = zmalloc<event_list_element>();
1641
1642                 if (!element) {
1643                         ret_code = LTTNG_ERR_NOMEM;
1644                         goto end;
1645                 }
1646
1647                 /*
1648                  * Lifetime and management of the object is now bound to the
1649                  * array.
1650                  */
1651                 ret = lttng_dynamic_pointer_array_add_pointer(event_list, element);
1652                 if (ret) {
1653                         event_list_destructor(element);
1654                         ret_code = LTTNG_ERR_NOMEM;
1655                         goto end;
1656                 }
1657
1658                 /*
1659                  * Bytecode is not transmitted on listing in any case we do not
1660                  * care about it.
1661                  */
1662                 event_size = lttng_event_create_from_payload(&event_view,
1663                                                              &element->event,
1664                                                              &element->exclusions,
1665                                                              &element->filter_expression,
1666                                                              nullptr);
1667                 if (event_size < 0) {
1668                         ret_code = LTTNG_ERR_INVALID;
1669                         goto end;
1670                 }
1671
1672                 offset += event_size;
1673         }
1674
1675         if (view->buffer.size != offset) {
1676                 ret_code = LTTNG_ERR_INVALID_PROTOCOL;
1677                 goto end;
1678         }
1679
1680         ret_code = LTTNG_OK;
1681
1682 end:
1683         return ret_code;
1684 }
1685
1686 enum lttng_error_code lttng_events_create_and_flatten_from_payload(
1687         struct lttng_payload_view *payload, unsigned int count, struct lttng_event **events)
1688 {
1689         enum lttng_error_code ret = LTTNG_OK;
1690         struct lttng_dynamic_pointer_array local_events;
1691
1692         lttng_dynamic_pointer_array_init(&local_events, event_list_destructor);
1693
1694         /* Deserialize the events. */
1695         {
1696                 struct lttng_payload_view events_view =
1697                         lttng_payload_view_from_view(payload, 0, -1);
1698
1699                 ret = event_list_create_from_payload(&events_view, count, &local_events);
1700                 if (ret != LTTNG_OK) {
1701                         goto end;
1702                 }
1703         }
1704
1705         ret = flatten_lttng_events(&local_events, events);
1706         if (ret != LTTNG_OK) {
1707                 goto end;
1708         }
1709
1710 end:
1711         lttng_dynamic_pointer_array_reset(&local_events);
1712         return ret;
1713 }
1714
1715 static enum lttng_error_code
1716 flatten_lttng_event_fields(struct lttng_dynamic_pointer_array *event_fields,
1717                            struct lttng_event_field **flattened_event_fields)
1718 {
1719         int ret, i;
1720         enum lttng_error_code ret_code;
1721         size_t storage_req = 0;
1722         struct lttng_dynamic_buffer local_flattened_event_fields;
1723         int nb_event_field;
1724
1725         assert(event_fields);
1726         assert(flattened_event_fields);
1727
1728         lttng_dynamic_buffer_init(&local_flattened_event_fields);
1729         nb_event_field = lttng_dynamic_pointer_array_get_count(event_fields);
1730
1731         /*
1732          * Here even if the event field contains a `struct lttng_event` that
1733          * could contain dynamic data, in reality it is not the case.
1734          * Dynamic data is not present. Here the flattening is mostly a direct
1735          * memcpy. This is less than ideal but this code is still better than
1736          * direct usage of an unpacked lttng_event_field array.
1737          */
1738         storage_req += sizeof(struct lttng_event_field) * nb_event_field;
1739
1740         lttng_dynamic_buffer_init(&local_flattened_event_fields);
1741
1742         /*
1743          * We must ensure that "local_flattened_event_fields" is never resized
1744          * so as to preserve the validity of the flattened objects.
1745          */
1746         ret = lttng_dynamic_buffer_set_capacity(&local_flattened_event_fields, storage_req);
1747         if (ret) {
1748                 ret_code = LTTNG_ERR_NOMEM;
1749                 goto end;
1750         }
1751
1752         for (i = 0; i < nb_event_field; i++) {
1753                 const struct lttng_event_field *element =
1754                         (const struct lttng_event_field *) lttng_dynamic_pointer_array_get_pointer(
1755                                 event_fields, i);
1756
1757                 if (!element) {
1758                         ret_code = LTTNG_ERR_FATAL;
1759                         goto end;
1760                 }
1761                 ret = lttng_dynamic_buffer_append(
1762                         &local_flattened_event_fields, element, sizeof(struct lttng_event_field));
1763                 if (ret) {
1764                         ret_code = LTTNG_ERR_NOMEM;
1765                         goto end;
1766                 }
1767         }
1768
1769         /* Don't reset local_flattened_channels buffer as we return its content. */
1770         *flattened_event_fields = (struct lttng_event_field *) local_flattened_event_fields.data;
1771         lttng_dynamic_buffer_init(&local_flattened_event_fields);
1772         ret_code = LTTNG_OK;
1773 end:
1774         lttng_dynamic_buffer_reset(&local_flattened_event_fields);
1775         return ret_code;
1776 }
1777
1778 static enum lttng_error_code
1779 event_field_list_create_from_payload(struct lttng_payload_view *view,
1780                                      unsigned int count,
1781                                      struct lttng_dynamic_pointer_array **event_field_list)
1782 {
1783         enum lttng_error_code ret_code;
1784         int ret, offset = 0;
1785         unsigned int i;
1786         struct lttng_dynamic_pointer_array *list = nullptr;
1787
1788         assert(view);
1789         assert(event_field_list);
1790
1791         list = zmalloc<lttng_dynamic_pointer_array>();
1792         if (!list) {
1793                 ret_code = LTTNG_ERR_NOMEM;
1794                 goto end;
1795         }
1796
1797         lttng_dynamic_pointer_array_init(list, free);
1798
1799         for (i = 0; i < count; i++) {
1800                 ssize_t event_field_size;
1801                 struct lttng_event_field *field = nullptr;
1802                 struct lttng_payload_view event_field_view =
1803                         lttng_payload_view_from_view(view, offset, -1);
1804
1805                 event_field_size = lttng_event_field_create_from_payload(&event_field_view, &field);
1806                 if (event_field_size < 0) {
1807                         ret_code = LTTNG_ERR_INVALID;
1808                         goto end;
1809                 }
1810
1811                 /* Lifetime and management of the object is now bound to the array. */
1812                 ret = lttng_dynamic_pointer_array_add_pointer(list, field);
1813                 if (ret) {
1814                         free(field);
1815                         ret_code = LTTNG_ERR_NOMEM;
1816                         goto end;
1817                 }
1818
1819                 offset += event_field_size;
1820         }
1821
1822         if (view->buffer.size != offset) {
1823                 ret_code = LTTNG_ERR_INVALID;
1824                 goto end;
1825         }
1826
1827         *event_field_list = list;
1828         list = nullptr;
1829         ret_code = LTTNG_OK;
1830
1831 end:
1832         if (list) {
1833                 lttng_dynamic_pointer_array_reset(list);
1834                 free(list);
1835         }
1836
1837         return ret_code;
1838 }
1839
1840 enum lttng_error_code lttng_event_fields_create_and_flatten_from_payload(
1841         struct lttng_payload_view *view, unsigned int count, struct lttng_event_field **fields)
1842 {
1843         enum lttng_error_code ret_code;
1844         struct lttng_dynamic_pointer_array *local_event_fields = nullptr;
1845
1846         ret_code = event_field_list_create_from_payload(view, count, &local_event_fields);
1847         if (ret_code != LTTNG_OK) {
1848                 goto end;
1849         }
1850
1851         ret_code = flatten_lttng_event_fields(local_event_fields, fields);
1852         if (ret_code != LTTNG_OK) {
1853                 goto end;
1854         }
1855 end:
1856         if (local_event_fields) {
1857                 lttng_dynamic_pointer_array_reset(local_event_fields);
1858                 free(local_event_fields);
1859         }
1860
1861         return ret_code;
1862 }