src/common/event.c

   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/compat/string.h"
   9 #include "common/macros.h"
  10 #include "lttng/lttng-error.h"
  11 #include <assert.h>
  12 #include <common/buffer-view.h>
  13 #include <common/dynamic-array.h>
  14 #include <common/dynamic-buffer.h>
  15 #include <common/error.h>
  16 #include <common/sessiond-comm/sessiond-comm.h>
  17 #include <common/align.h>
  18 #include <lttng/constant.h>
  19 #include <lttng/event-internal.h>
  20 #include <lttng/event.h>
  21 #include <lttng/userspace-probe-internal.h>
  22 #include <stdint.h>
  23 #include <string.h>
  24
  25 struct event_list_element {
  26         struct lttng_event *event;
  27         struct lttng_event_exclusion *exclusions;
  28         char *filter_expression;
  29 };
  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 LTTNG_HIDDEN
  42 struct lttng_event *lttng_event_copy(const struct lttng_event *event)
  43 {
  44         struct lttng_event *new_event;
  45         struct lttng_event_extended *new_event_extended;
  46
  47         new_event = zmalloc(sizeof(*event));
  48         if (!new_event) {
  49                 PERROR("Error allocating event structure");
  50                 goto end;
  51         }
  52
  53         /* Copy the content of the old event. */
  54         memcpy(new_event, event, sizeof(*event));
  55
  56         /*
  57          * We need to create a new extended since the previous pointer is now
  58          * invalid.
  59          */
  60         new_event_extended = zmalloc(sizeof(*new_event_extended));
  61         if (!new_event_extended) {
  62                 PERROR("Error allocating event extended structure");
  63                 goto error;
  64         }
  65
  66         new_event->extended.ptr = new_event_extended;
  67 end:
  68         return new_event;
  69 error:
  70         free(new_event);
  71         new_event = NULL;
  72         goto end;
  73 }
  74
  75 static int lttng_event_probe_attr_serialize(
  76                 const struct lttng_event_probe_attr *probe,
  77                 struct lttng_payload *payload)
  78 {
  79         int ret;
  80         size_t symbol_name_len;
  81         struct lttng_event_probe_attr_comm comm = { 0 };
  82
  83         symbol_name_len = lttng_strnlen(probe->symbol_name, LTTNG_SYMBOL_NAME_LEN);
  84         if (symbol_name_len == LTTNG_SYMBOL_NAME_LEN) {
  85                 /* Not null-termintated. */
  86                 ret = -1;
  87                 goto end;
  88         }
  89
  90         /* Include the null terminator. */
  91         symbol_name_len += 1;
  92
  93         comm.symbol_name_len = (uint32_t) symbol_name_len;
  94         comm.addr = probe->addr;
  95         comm.offset = probe->addr;
  96
  97         ret = lttng_dynamic_buffer_append(
  98                         &payload->buffer, &comm, sizeof(comm));
  99         if (ret < 0) {
 100                 ret = -1;
 101                 goto end;
 102         }
 103
 104         ret = lttng_dynamic_buffer_append(
 105                         &payload->buffer, probe->symbol_name, symbol_name_len);
 106 end:
 107         return ret;
 108 }
 109
 110 static int lttng_event_function_attr_serialize(
 111                 const struct lttng_event_function_attr *function,
 112                 struct lttng_payload *payload)
 113 {
 114         int ret;
 115         size_t symbol_name_len;
 116         struct lttng_event_function_attr_comm comm = { 0 };
 117
 118         symbol_name_len = lttng_strnlen(function->symbol_name, LTTNG_SYMBOL_NAME_LEN);
 119         if (symbol_name_len == LTTNG_SYMBOL_NAME_LEN) {
 120                 /* Not null-termintated. */
 121                 ret = -1;
 122                 goto end;
 123         }
 124
 125         /* Include the null terminator. */
 126         symbol_name_len += 1;
 127
 128         comm.symbol_name_len = (uint32_t) symbol_name_len;
 129
 130         ret = lttng_dynamic_buffer_append(
 131                         &payload->buffer, &comm, sizeof(comm));
 132         if (ret < 0) {
 133                 ret = -1;
 134                 goto end;
 135         }
 136
 137         ret = lttng_dynamic_buffer_append(&payload->buffer,
 138                         function->symbol_name, symbol_name_len);
 139 end:
 140         return ret;
 141 }
 142
 143 static ssize_t lttng_event_probe_attr_create_from_payload(
 144                 struct lttng_payload_view *view,
 145                 struct lttng_event_probe_attr **probe_attr)
 146 {
 147         ssize_t ret, offset = 0;
 148         const struct lttng_event_probe_attr_comm *comm;
 149         struct lttng_event_probe_attr *local_attr = NULL;
 150         struct lttng_payload_view comm_view = lttng_payload_view_from_view(
 151                         view, offset, sizeof(*comm));
 152
 153         if (!lttng_payload_view_is_valid(&comm_view)) {
 154                 ret = -1;
 155                 goto end;
 156         }
 157
 158         comm = (typeof(comm)) comm_view.buffer.data;
 159         offset += sizeof(*comm);
 160
 161         local_attr = (struct lttng_event_probe_attr *) zmalloc(
 162                         sizeof(*local_attr));
 163         if (local_attr == NULL) {
 164                 ret = -1;
 165                 goto end;
 166         }
 167
 168         local_attr->addr = comm->addr;
 169         local_attr->offset = comm->offset;
 170
 171         {
 172                 const char *name;
 173                 struct lttng_payload_view name_view =
 174                                 lttng_payload_view_from_view(view, offset,
 175                                                 comm->symbol_name_len);
 176
 177                 if (!lttng_payload_view_is_valid(&name_view)) {
 178                         ret = -1;
 179                         goto end;
 180                 }
 181
 182                 name = name_view.buffer.data;
 183
 184                 if (!lttng_buffer_view_contains_string(&name_view.buffer, name,
 185                                     comm->symbol_name_len)) {
 186                         ret = -1;
 187                         goto end;
 188                 }
 189
 190                 ret = lttng_strncpy(local_attr->symbol_name, name,
 191                                 LTTNG_SYMBOL_NAME_LEN);
 192                 if (ret) {
 193                         ret = -1;
 194                         goto end;
 195                 }
 196
 197                 offset += comm->symbol_name_len;
 198         }
 199
 200         *probe_attr = local_attr;
 201         local_attr = NULL;
 202         ret = offset;
 203 end:
 204         return ret;
 205 }
 206
 207 static ssize_t lttng_event_function_attr_create_from_payload(
 208                 struct lttng_payload_view *view,
 209                 struct lttng_event_function_attr **function_attr)
 210 {
 211         ssize_t ret, offset = 0;
 212         const struct lttng_event_function_attr_comm *comm;
 213         struct lttng_event_function_attr *local_attr = NULL;
 214         struct lttng_payload_view comm_view = lttng_payload_view_from_view(
 215                         view, offset, sizeof(*comm));
 216
 217         if (!lttng_payload_view_is_valid(&comm_view)) {
 218                 ret = -1;
 219                 goto end;
 220         }
 221
 222         comm = (typeof(comm)) view->buffer.data;
 223         offset += sizeof(*comm);
 224
 225         local_attr = (struct lttng_event_function_attr *) zmalloc(
 226                         sizeof(*local_attr));
 227         if (local_attr == NULL) {
 228                 ret = -1;
 229                 goto end;
 230         }
 231
 232         {
 233                 const char *name;
 234                 struct lttng_payload_view name_view =
 235                                 lttng_payload_view_from_view(view, offset,
 236                                                 comm->symbol_name_len);
 237
 238                 if (!lttng_payload_view_is_valid(&name_view)) {
 239                         ret = -1;
 240                         goto end;
 241                 }
 242
 243                 name = name_view.buffer.data;
 244
 245                 if (!lttng_buffer_view_contains_string(&name_view.buffer, name,
 246                                     comm->symbol_name_len)) {
 247                         ret = -1;
 248                         goto end;
 249                 }
 250
 251                 ret = lttng_strncpy(local_attr->symbol_name, name,
 252                                 LTTNG_SYMBOL_NAME_LEN);
 253                 if (ret) {
 254                         ret = -1;
 255                         goto end;
 256                 }
 257
 258                 offset += comm->symbol_name_len;
 259         }
 260
 261         *function_attr = local_attr;
 262         local_attr = NULL;
 263         ret = offset;
 264 end:
 265         return ret;
 266 }
 267
 268 static ssize_t lttng_event_exclusions_create_from_payload(
 269                 struct lttng_payload_view *view,
 270                 uint32_t count,
 271                 struct lttng_event_exclusion **exclusions)
 272 {
 273         ssize_t ret, offset = 0;
 274         size_t size = (count * LTTNG_SYMBOL_NAME_LEN);
 275         uint32_t i;
 276         const struct lttng_event_exclusion_comm *comm;
 277         struct lttng_event_exclusion *local_exclusions;
 278
 279         local_exclusions = (struct lttng_event_exclusion *) zmalloc(
 280                         sizeof(struct lttng_event_exclusion) + size);
 281         if (!local_exclusions) {
 282                 ret = -1;
 283                 goto end;
 284         }
 285
 286         local_exclusions->count = count;
 287
 288         for (i = 0; i < count; i++) {
 289                 const char *string;
 290                 struct lttng_buffer_view string_view;
 291                 const struct lttng_buffer_view comm_view =
 292                                 lttng_buffer_view_from_view(&view->buffer,
 293                                                 offset, sizeof(*comm));
 294
 295                 if (!lttng_buffer_view_is_valid(&comm_view)) {
 296                         ret = -1;
 297                         goto end;
 298                 }
 299
 300                 comm = (typeof(comm)) comm_view.data;
 301                 offset += sizeof(*comm);
 302
 303                 string_view = lttng_buffer_view_from_view(
 304                                 &view->buffer, offset, comm->len);
 305
 306                 if (!lttng_buffer_view_is_valid(&string_view)) {
 307                         ret = -1;
 308                         goto end;
 309                 }
 310
 311                 string = string_view.data;
 312
 313                 if (!lttng_buffer_view_contains_string(
 314                                     &string_view, string, comm->len)) {
 315                         ret = -1;
 316                         goto end;
 317                 }
 318
 319                 ret = lttng_strncpy(local_exclusions->names[i],
 320                                 string, LTTNG_SYMBOL_NAME_LEN);
 321                 if (ret) {
 322                         ret = -1;
 323                         goto end;
 324                 }
 325
 326                 offset += comm->len;
 327         }
 328
 329         *exclusions = local_exclusions;
 330         local_exclusions = NULL;
 331         ret = offset;
 332 end:
 333         free(local_exclusions);
 334         return ret;
 335 }
 336
 337 ssize_t lttng_event_create_from_payload(struct lttng_payload_view *view,
 338                 struct lttng_event **out_event,
 339                 struct lttng_event_exclusion **out_exclusion,
 340                 char **out_filter_expression,
 341                 struct lttng_bytecode **out_bytecode)
 342 {
 343         ssize_t ret, offset = 0;
 344         struct lttng_event *local_event = NULL;
 345         struct lttng_event_exclusion *local_exclusions = NULL;
 346         struct lttng_bytecode *local_bytecode = NULL;
 347         char *local_filter_expression = NULL;
 348         const struct lttng_event_comm *event_comm;
 349         struct lttng_event_function_attr *local_function_attr = NULL;
 350         struct lttng_event_probe_attr *local_probe_attr = NULL;
 351         struct lttng_userspace_probe_location *local_userspace_probe_location =
 352                         NULL;
 353
 354         /*
 355          * Only event is obligatory, the other output argument are optional and
 356          * depends on what the caller is interested in.
 357          */
 358         assert(out_event);
 359         assert(view);
 360
 361         {
 362                 struct lttng_payload_view comm_view =
 363                                 lttng_payload_view_from_view(view, offset,
 364                                                 sizeof(*event_comm));
 365
 366                 if (!lttng_payload_view_is_valid(&comm_view)) {
 367                         ret = -1;
 368                         goto end;
 369                 }
 370
 371                 /* lttng_event_comm header */
 372                 event_comm = (typeof(event_comm)) comm_view.buffer.data;
 373                 offset += sizeof(*event_comm);
 374         }
 375
 376         local_event = lttng_event_create();
 377         if (local_event == NULL) {
 378                 ret = -1;
 379                 goto end;
 380         }
 381
 382         local_event->type = (enum lttng_event_type) event_comm->event_type;
 383         local_event->loglevel_type = (enum lttng_loglevel_type) event_comm->loglevel_type;
 384         local_event->loglevel = event_comm->loglevel;
 385         local_event->enabled = event_comm->enabled;
 386         local_event->pid = event_comm->pid;
 387         local_event->flags = (enum lttng_event_flag) event_comm->flags;
 388
 389         {
 390                 const char *name;
 391                 const struct lttng_buffer_view name_view =
 392                                 lttng_buffer_view_from_view(&view->buffer,
 393                                                 offset, event_comm->name_len);
 394
 395                 if (!lttng_buffer_view_is_valid(&name_view)) {
 396                         ret = -1;
 397                         goto end;
 398                 }
 399
 400                 name = (const char *) name_view.data;
 401
 402                 if (!lttng_buffer_view_contains_string(
 403                                     &name_view, name, event_comm->name_len)) {
 404                         ret = -1;
 405                         goto end;
 406                 }
 407
 408                 ret = lttng_strncpy(
 409                                 local_event->name, name, LTTNG_SYMBOL_NAME_LEN);
 410                 if (ret) {
 411                         ret = -1;
 412                         goto end;
 413                 }
 414
 415                 offset += event_comm->name_len;
 416         }
 417
 418         /* Exclusions */
 419         if (event_comm->exclusion_count == 0) {
 420                 goto deserialize_filter_expression;
 421         }
 422
 423         {
 424                 struct lttng_payload_view exclusions_view =
 425                                 lttng_payload_view_from_view(
 426                                                 view, offset, -1);
 427
 428                 if (!lttng_payload_view_is_valid(&exclusions_view)) {
 429                         ret = -1;
 430                         goto end;
 431                 }
 432
 433                 ret = lttng_event_exclusions_create_from_payload(&exclusions_view,
 434                                 event_comm->exclusion_count, &local_exclusions);
 435                 if (ret < 0) {
 436                         ret = -1;
 437                         goto end;
 438                 }
 439                 offset += ret;
 440
 441                 local_event->exclusion = 1;
 442         }
 443
 444 deserialize_filter_expression:
 445
 446         if (event_comm->filter_expression_len == 0) {
 447                 if (event_comm->bytecode_len != 0) {
 448                         /*
 449                          * This is an invalid event payload.
 450                          *
 451                          * Filter expression without bytecode is possible but
 452                          * not the other way around.
 453                          * */
 454                         ret = -1;
 455                         goto end;
 456                 }
 457                 goto deserialize_event_type_payload;
 458         }
 459
 460         {
 461                 const char *filter_expression_buffer;
 462                 struct lttng_buffer_view filter_expression_view =
 463                                 lttng_buffer_view_from_view(&view->buffer, offset,
 464                                                 event_comm->filter_expression_len);
 465
 466                 if (!lttng_buffer_view_is_valid(&filter_expression_view)) {
 467                         ret = -1;
 468                         goto end;
 469                 }
 470
 471                 filter_expression_buffer = filter_expression_view.data;
 472
 473                 if (!lttng_buffer_view_contains_string(&filter_expression_view,
 474                                     filter_expression_buffer,
 475                                     event_comm->filter_expression_len)) {
 476                         ret = -1;
 477                         goto end;
 478                 }
 479
 480                 local_filter_expression = lttng_strndup(
 481                                 filter_expression_buffer,
 482                                 event_comm->filter_expression_len);
 483                 if (!local_filter_expression) {
 484                         ret = -1;
 485                         goto end;
 486                 }
 487
 488                 local_event->filter = 1;
 489
 490                 offset += event_comm->filter_expression_len;
 491         }
 492
 493         if (event_comm->bytecode_len == 0) {
 494                 /*
 495                  * Filter expression can be present but without bytecode
 496                  * when dealing with event listing.
 497                  */
 498                 goto deserialize_event_type_payload;
 499         }
 500
 501         /* Bytecode */
 502         {
 503                 struct lttng_payload_view bytecode_view =
 504                                 lttng_payload_view_from_view(view, offset,
 505                                                 event_comm->bytecode_len);
 506
 507                 if (!lttng_payload_view_is_valid(&bytecode_view)) {
 508                         ret = -1;
 509                         goto end;
 510                 }
 511
 512                 local_bytecode = (struct lttng_bytecode *) zmalloc(
 513                                 event_comm->bytecode_len);
 514                 if (!local_bytecode) {
 515                         ret = -1;
 516                         goto end;
 517                 }
 518
 519                 memcpy(local_bytecode, bytecode_view.buffer.data,
 520                                 event_comm->bytecode_len);
 521                 if ((local_bytecode->len + sizeof(*local_bytecode)) !=
 522                                 event_comm->bytecode_len) {
 523                         ret = -1;
 524                         goto end;
 525                 }
 526
 527                 offset += event_comm->bytecode_len;
 528         }
 529
 530 deserialize_event_type_payload:
 531         /* Event type specific payload */
 532         switch (local_event->type) {
 533         case LTTNG_EVENT_FUNCTION:
 534                 /* Fallthrough */
 535         case LTTNG_EVENT_PROBE:
 536         {
 537                 struct lttng_payload_view probe_attr_view =
 538                                 lttng_payload_view_from_view(view, offset,
 539                                                 event_comm->lttng_event_probe_attr_len);
 540
 541                 if (event_comm->lttng_event_probe_attr_len == 0) {
 542                         ret = -1;
 543                         goto end;
 544                 }
 545
 546                 if (!lttng_payload_view_is_valid(&probe_attr_view)) {
 547                         ret = -1;
 548                         goto end;
 549                 }
 550
 551                 ret = lttng_event_probe_attr_create_from_payload(
 552                                 &probe_attr_view, &local_probe_attr);
 553                 if (ret < 0 || ret != event_comm->lttng_event_probe_attr_len) {
 554                         ret = -1;
 555                         goto end;
 556                 }
 557
 558                 /* Copy to the local event. */
 559                 memcpy(&local_event->attr.probe, local_probe_attr,
 560                                 sizeof(local_event->attr.probe));
 561
 562                 offset += ret;
 563                 break;
 564         }
 565         case LTTNG_EVENT_FUNCTION_ENTRY:
 566         {
 567                 struct lttng_payload_view function_attr_view =
 568                                 lttng_payload_view_from_view(view, offset,
 569                                                 event_comm->lttng_event_function_attr_len);
 570
 571                 if (event_comm->lttng_event_function_attr_len == 0) {
 572                         ret = -1;
 573                         goto end;
 574                 }
 575
 576                 if (!lttng_payload_view_is_valid(&function_attr_view)) {
 577                         ret = -1;
 578                         goto end;
 579                 }
 580
 581                 ret = lttng_event_function_attr_create_from_payload(
 582                                 &function_attr_view, &local_function_attr);
 583                 if (ret < 0 || ret != event_comm->lttng_event_function_attr_len) {
 584                         ret = -1;
 585                         goto end;
 586                 }
 587
 588                 /* Copy to the local event. */
 589                 memcpy(&local_event->attr.ftrace, local_function_attr,
 590                                 sizeof(local_event->attr.ftrace));
 591
 592                 offset += ret;
 593
 594                 break;
 595         }
 596         case LTTNG_EVENT_USERSPACE_PROBE:
 597         {
 598                 struct lttng_payload_view userspace_probe_location_view =
 599                                 lttng_payload_view_from_view(view, offset,
 600                                                 event_comm->userspace_probe_location_len);
 601
 602                 if (event_comm->userspace_probe_location_len == 0) {
 603                         ret = -1;
 604                         goto end;
 605                 }
 606
 607                 if (!lttng_payload_view_is_valid(
 608                                     &userspace_probe_location_view)) {
 609                         ret = -1;
 610                         goto end;
 611                 }
 612
 613                 ret = lttng_userspace_probe_location_create_from_payload(
 614                                 &userspace_probe_location_view,
 615                                 &local_userspace_probe_location);
 616                 if (ret < 0) {
 617                         WARN("Failed to create a userspace probe location from the received buffer");
 618                         ret = -1;
 619                         goto end;
 620                 }
 621
 622                 if (ret != event_comm->userspace_probe_location_len) {
 623                         WARN("Userspace probe location from the received buffer is not the advertised length: header length = %" PRIu32 ", payload length = %lu", event_comm->userspace_probe_location_len, ret);
 624                         ret = -1;
 625                         goto end;
 626                 }
 627
 628                 /* Attach the probe location to the event. */
 629                 ret = lttng_event_set_userspace_probe_location(
 630                                 local_event, local_userspace_probe_location);
 631                 if (ret) {
 632                         ret = LTTNG_ERR_PROBE_LOCATION_INVAL;
 633                         goto end;
 634                 }
 635
 636                 /*
 637                  * Userspace probe location object ownership transfered to the
 638                  * event object.
 639                  */
 640                 local_userspace_probe_location = NULL;
 641                 offset += event_comm->userspace_probe_location_len;
 642                 break;
 643         }
 644         case LTTNG_EVENT_TRACEPOINT:
 645                 /* Fallthrough */
 646         case LTTNG_EVENT_ALL:
 647                 /* Fallthrough */
 648         case LTTNG_EVENT_SYSCALL:
 649                 /* Fallthrough */
 650         case LTTNG_EVENT_NOOP:
 651                 /* Nothing to do here */
 652                 break;
 653         default:
 654                 ret = LTTNG_ERR_UND;
 655                 goto end;
 656                 break;
 657         }
 658
 659         /* Transfer ownership to the caller. */
 660         *out_event = local_event;
 661         local_event = NULL;
 662
 663         if (out_bytecode) {
 664                 *out_bytecode = local_bytecode;
 665                 local_bytecode = NULL;
 666         }
 667
 668         if (out_exclusion) {
 669                 *out_exclusion = local_exclusions;
 670                 local_exclusions = NULL;
 671         }
 672
 673         if (out_filter_expression) {
 674                 *out_filter_expression = local_filter_expression;
 675                 local_filter_expression = NULL;
 676         }
 677
 678         ret = offset;
 679 end:
 680         lttng_event_destroy(local_event);
 681         lttng_userspace_probe_location_destroy(local_userspace_probe_location);
 682         free(local_filter_expression);
 683         free(local_exclusions);
 684         free(local_bytecode);
 685         free(local_function_attr);
 686         free(local_probe_attr);
 687         return ret;
 688 }
 689
 690 int lttng_event_serialize(const struct lttng_event *event,
 691                 unsigned int exclusion_count,
 692                 char **exclusion_list,
 693                 char *filter_expression,
 694                 size_t bytecode_len,
 695                 struct lttng_bytecode *bytecode,
 696                 struct lttng_payload *payload)
 697 {
 698         int ret;
 699         unsigned int i;
 700         size_t header_offset, size_before_payload;
 701         size_t name_len;
 702         struct lttng_event_comm event_comm = { 0 };
 703         struct lttng_event_comm *header;
 704
 705         assert(event);
 706         assert(payload);
 707         assert(exclusion_count == 0 || exclusion_list);
 708
 709         /* Save the header location for later in-place header update. */
 710         header_offset = payload->buffer.size;
 711
 712         name_len = lttng_strnlen(event->name, LTTNG_SYMBOL_NAME_LEN);
 713         if (name_len == LTTNG_SYMBOL_NAME_LEN) {
 714                 /* Event name is not NULL-terminated. */
 715                 ret = -1;
 716                 goto end;
 717         }
 718
 719         /* Add null termination. */
 720         name_len += 1;
 721
 722         if (exclusion_count > UINT32_MAX) {
 723                 /* Possible overflow. */
 724                 ret = -1;
 725                 goto end;
 726         }
 727
 728         if (bytecode_len > UINT32_MAX) {
 729                 /* Possible overflow. */
 730                 ret = -1;
 731                 goto end;
 732         }
 733
 734         event_comm.name_len = (uint32_t) name_len;
 735         event_comm.event_type = (int8_t) event->type;
 736         event_comm.loglevel_type = (int8_t) event->loglevel_type;
 737         event_comm.loglevel = (int32_t) event->loglevel;
 738         event_comm.enabled = (int8_t) event->enabled;
 739         event_comm.pid = (int32_t) event->pid;
 740         event_comm.exclusion_count = (uint32_t) exclusion_count;
 741         event_comm.bytecode_len = (uint32_t) bytecode_len;
 742         event_comm.flags = (int32_t) event->flags;
 743
 744         if (filter_expression) {
 745                 event_comm.filter_expression_len =
 746                                 strlen(filter_expression) + 1;
 747         }
 748
 749         /* Header */
 750         ret = lttng_dynamic_buffer_append(
 751                         &payload->buffer, &event_comm, sizeof(event_comm));
 752         if (ret) {
 753                 goto end;
 754         }
 755
 756         /* Event name */
 757         ret = lttng_dynamic_buffer_append(
 758                         &payload->buffer, event->name, name_len);
 759         if (ret) {
 760                 goto end;
 761         }
 762
 763         /* Exclusions */
 764         for (i = 0; i < exclusion_count; i++) {
 765                 const size_t exclusion_len = lttng_strnlen(
 766                                 *(exclusion_list + i), LTTNG_SYMBOL_NAME_LEN);
 767                 const struct lttng_event_exclusion_comm exclusion_header = {
 768                         .len = (uint32_t) exclusion_len + 1,
 769                 };
 770
 771                 if (exclusion_len == LTTNG_SYMBOL_NAME_LEN) {
 772                         /* Exclusion is not NULL-terminated. */
 773                         ret = -1;
 774                         goto end;
 775                 }
 776
 777                 ret = lttng_dynamic_buffer_append(&payload->buffer,
 778                                 &exclusion_header, sizeof(exclusion_header));
 779                 if (ret) {
 780                         goto end;
 781                 }
 782
 783                 ret = lttng_dynamic_buffer_append(&payload->buffer,
 784                                 *(exclusion_list + i), exclusion_len + 1);
 785                 if (ret) {
 786                         goto end;
 787                 }
 788         }
 789
 790         /* Filter expression and its bytecode */
 791         if (filter_expression) {
 792                 ret = lttng_dynamic_buffer_append(&payload->buffer,
 793                                 filter_expression,
 794                                 event_comm.filter_expression_len);
 795                 if (ret) {
 796                         goto end;
 797                 }
 798
 799                 /*
 800                  * Bytecode can be absent when we serialize to the client
 801                  * for listing.
 802                  */
 803                 if (bytecode) {
 804                         ret = lttng_dynamic_buffer_append(&payload->buffer,
 805                                         bytecode, bytecode_len);
 806                         if (ret) {
 807                                 goto end;
 808                         }
 809                 }
 810         }
 811
 812         size_before_payload = payload->buffer.size;
 813
 814         /* Event type specific payload */
 815         switch (event->type) {
 816         case LTTNG_EVENT_FUNCTION:
 817                 /* Fallthrough */
 818         case LTTNG_EVENT_PROBE:
 819                 ret = lttng_event_probe_attr_serialize(&event->attr.probe, payload);
 820                 if (ret) {
 821                         ret = -1;
 822                         goto end;
 823                 }
 824
 825                 header = (struct lttng_event_comm *) ((char *) payload->buffer.data +
 826                                                       header_offset);
 827                 header->lttng_event_probe_attr_len =
 828                                 payload->buffer.size - size_before_payload;
 829
 830                 break;
 831         case LTTNG_EVENT_FUNCTION_ENTRY:
 832                 ret = lttng_event_function_attr_serialize(
 833                                 &event->attr.ftrace, payload);
 834                 if (ret) {
 835                         ret = -1;
 836                         goto end;
 837                 }
 838
 839                 /* Update the lttng_event_function_attr len. */
 840                 header = (struct lttng_event_comm *) ((char *) payload->buffer.data +
 841                                                       header_offset);
 842                 header->lttng_event_function_attr_len =
 843                                 payload->buffer.size - size_before_payload;
 844
 845                 break;
 846         case LTTNG_EVENT_USERSPACE_PROBE:
 847         {
 848                 const struct lttng_event_extended *ev_ext =
 849                                 (const struct lttng_event_extended *)
 850                                                 event->extended.ptr;
 851
 852                 assert(event->extended.ptr);
 853                 assert(ev_ext->probe_location);
 854
 855                 size_before_payload = payload->buffer.size;
 856                 if (ev_ext->probe_location) {
 857                         /*
 858                          * lttng_userspace_probe_location_serialize returns the
 859                          * number of bytes that were appended to the buffer.
 860                          */
 861                         ret = lttng_userspace_probe_location_serialize(
 862                                         ev_ext->probe_location, payload);
 863                         if (ret < 0) {
 864                                 goto end;
 865                         }
 866
 867                         ret = 0;
 868
 869                         /* Update the userspace probe location len. */
 870                         header = (struct lttng_event_comm *) ((char *) payload->buffer.data +
 871                                                               header_offset);
 872                         header->userspace_probe_location_len =
 873                                         payload->buffer.size - size_before_payload;
 874                 }
 875                 break;
 876         }
 877         case LTTNG_EVENT_TRACEPOINT:
 878                 /* Fallthrough */
 879         case LTTNG_EVENT_ALL:
 880                 /* Fallthrough */
 881         default:
 882                 /* Nothing to do here. */
 883                 break;
 884         }
 885
 886 end:
 887         return ret;
 888 }
 889
 890 static enum lttng_error_code compute_flattened_size(
 891                 struct lttng_dynamic_pointer_array *events, size_t *size)
 892 {
 893         enum lttng_error_code ret_code;
 894         int ret = 0;
 895         size_t storage_req, event_count, i;
 896
 897         assert(size);
 898         assert(events);
 899
 900         event_count = lttng_dynamic_pointer_array_get_count(events);
 901
 902         /* The basic struct lttng_event */
 903         storage_req = event_count * sizeof(struct lttng_event);
 904
 905         for (i = 0; i < event_count; i++) {
 906                 int probe_storage_req = 0;
 907                 const struct event_list_element *element = (const struct event_list_element *)
 908                                 lttng_dynamic_pointer_array_get_pointer(
 909                                                 events, i);
 910                 const struct lttng_userspace_probe_location *location = NULL;
 911
 912                 location = lttng_event_get_userspace_probe_location(
 913                                 element->event);
 914                 if (location) {
 915                         ret = lttng_userspace_probe_location_flatten(
 916                                         location, NULL);
 917                         if (ret < 0) {
 918                                 ret_code = LTTNG_ERR_PROBE_LOCATION_INVAL;
 919                                 goto end;
 920                         }
 921
 922                         probe_storage_req = ret;
 923                 }
 924
 925                 /* The struct·lttng_event_extended */
 926                 storage_req += event_count *
 927                         sizeof(struct lttng_event_extended);
 928
 929                 if (element->filter_expression) {
 930                         storage_req += strlen(element->filter_expression) + 1;
 931                 }
 932
 933                 if (element->exclusions) {
 934                         storage_req += element->exclusions->count *
 935                                 LTTNG_SYMBOL_NAME_LEN;
 936                 }
 937
 938                 /* Padding to ensure the flat probe is aligned. */
 939                 storage_req = ALIGN_TO(storage_req, sizeof(uint64_t));
 940                 storage_req += probe_storage_req;
 941         }
 942
 943         *size = storage_req;
 944         ret_code = LTTNG_OK;
 945
 946 end:
 947         return ret_code;
 948 }
 949
 950 /*
 951  * Flatten a list of struct lttng_event.
 952  *
 953  * The buffer that is returned to the API client  must contain a "flat" version
 954  * of the events that are returned. In other words, all pointers within an
 955  * lttng_event must point to a location within the returned buffer so that the
 956  * user may free everything by simply calling free() on the returned buffer.
 957  * This is needed in order to maintain API compatibility.
 958  *
 959  * A first pass is performed to compute the size of the buffer that must be
 960  * allocated. A second pass is then performed to setup the returned events so
 961  * that their members always point within the buffer.
 962  *
 963  * The layout of the returned buffer is as follows:
 964  *   - struct lttng_event[nb_events],
 965  *   - nb_events times the following:
 966  *     - struct lttng_event_extended,
 967  *     - filter_expression
 968  *     - exclusions
 969  *     - padding to align to 64-bits
 970  *     - flattened version of userspace_probe_location
 971  */
 972 static enum lttng_error_code flatten_lttng_events(
 973                 struct lttng_dynamic_pointer_array *events,
 974                 struct lttng_event **flattened_events)
 975 {
 976         enum lttng_error_code ret_code;
 977         int ret, i;
 978         size_t storage_req;
 979         struct lttng_dynamic_buffer local_flattened_events;
 980         int nb_events;
 981
 982         assert(events);
 983         assert(flattened_events);
 984
 985         lttng_dynamic_buffer_init(&local_flattened_events);
 986         nb_events = lttng_dynamic_pointer_array_get_count(events);
 987
 988         ret_code = compute_flattened_size(events, &storage_req);
 989         if (ret_code != LTTNG_OK) {
 990                 goto end;
 991         }
 992
 993         /*
 994          * We must ensure that "local_flattened_events" is never resized so as
 995          * to preserve the validity of the flattened objects.
 996          */
 997         ret = lttng_dynamic_buffer_set_capacity(
 998                         &local_flattened_events, storage_req);
 999         if (ret) {
1000                 ret_code = LTTNG_ERR_NOMEM;
1001                 goto end;
1002         }
1003
1004         /* Start by laying the struct lttng_event */
1005         for (i = 0; i < nb_events; i++) {
1006                 const struct event_list_element *element = (const struct event_list_element *)
1007                                 lttng_dynamic_pointer_array_get_pointer(
1008                                                 events, i);
1009
1010                 if (!element) {
1011                         ret_code = LTTNG_ERR_FATAL;
1012                         goto end;
1013                 }
1014
1015                 ret = lttng_dynamic_buffer_append(&local_flattened_events,
1016                                 element->event, sizeof(struct lttng_event));
1017                 if (ret) {
1018                         ret_code = LTTNG_ERR_NOMEM;
1019                         goto end;
1020                 }
1021         }
1022
1023         for (i = 0; i < nb_events; i++) {
1024                 const struct event_list_element *element = (const struct event_list_element *)
1025                                 lttng_dynamic_pointer_array_get_pointer(events, i);
1026                 struct lttng_event *event = (struct lttng_event *)
1027                         (local_flattened_events.data + (sizeof(struct lttng_event) * i));
1028                 struct lttng_event_extended *event_extended =
1029                         (struct lttng_event_extended *)
1030                                 (local_flattened_events.data + local_flattened_events.size);
1031                 const struct lttng_userspace_probe_location *location = NULL;
1032
1033                 assert(element);
1034
1035                 /* Insert struct lttng_event_extended. */
1036                 ret = lttng_dynamic_buffer_set_size(&local_flattened_events,
1037                                 local_flattened_events.size +
1038                                                 sizeof(*event_extended));
1039                 if (ret) {
1040                         ret_code = LTTNG_ERR_NOMEM;
1041                         goto end;
1042                 }
1043                 event->extended.ptr = event_extended;
1044
1045                 /* Insert filter expression. */
1046                 if (element->filter_expression) {
1047                         const size_t len = strlen(element->filter_expression) + 1;
1048
1049                         event_extended->filter_expression =
1050                                         local_flattened_events.data +
1051                                         local_flattened_events.size;
1052                         ret = lttng_dynamic_buffer_append(
1053                                         &local_flattened_events,
1054                                         element->filter_expression, len);
1055                         if (ret) {
1056                                 ret_code = LTTNG_ERR_NOMEM;
1057                                 goto end;
1058                         }
1059                 }
1060
1061                 /* Insert exclusions. */
1062                 if (element->exclusions) {
1063                         event_extended->exclusions.count =
1064                                         element->exclusions->count;
1065                         event_extended->exclusions.strings =
1066                                         local_flattened_events.data +
1067                                         local_flattened_events.size;
1068
1069                         ret = lttng_dynamic_buffer_append(
1070                                         &local_flattened_events,
1071                                         element->exclusions->names,
1072                                         element->exclusions->count *
1073                                                         LTTNG_SYMBOL_NAME_LEN);
1074                         if (ret) {
1075                                 ret_code = LTTNG_ERR_NOMEM;
1076                                 goto end;
1077                         }
1078                 }
1079
1080                 /* Insert padding to align to 64-bits. */
1081                 ret = lttng_dynamic_buffer_set_size(&local_flattened_events,
1082                                 ALIGN_TO(local_flattened_events.size,
1083                                                 sizeof(uint64_t)));
1084                 if (ret) {
1085                         ret_code = LTTNG_ERR_NOMEM;
1086                         goto end;
1087                 }
1088
1089                 location = lttng_event_get_userspace_probe_location(
1090                                 element->event);
1091                 if (location) {
1092                         event_extended->probe_location = (struct lttng_userspace_probe_location *)
1093                                         (local_flattened_events.data + local_flattened_events.size);
1094                         ret = lttng_userspace_probe_location_flatten(
1095                                         location, &local_flattened_events);
1096                         if (ret < 0) {
1097                                 ret_code = LTTNG_ERR_PROBE_LOCATION_INVAL;
1098                                 goto end;
1099                         }
1100                 }
1101         }
1102
1103         /* Don't reset local_flattened_events buffer as we return its content. */
1104         *flattened_events = (struct lttng_event *) local_flattened_events.data;
1105         lttng_dynamic_buffer_init(&local_flattened_events);
1106         ret_code = LTTNG_OK;
1107 end:
1108         lttng_dynamic_buffer_reset(&local_flattened_events);
1109         return ret_code;
1110 }
1111
1112 static enum lttng_error_code event_list_create_from_payload(
1113                 struct lttng_payload_view *view,
1114                 unsigned int count,
1115                 struct lttng_dynamic_pointer_array *event_list)
1116 {
1117         enum lttng_error_code ret_code;
1118         int ret;
1119         unsigned int i;
1120         int offset = 0;
1121
1122         assert(view);
1123         assert(event_list);
1124
1125         for (i = 0; i < count; i++) {
1126                 ssize_t event_size;
1127                 struct lttng_payload_view event_view =
1128                                 lttng_payload_view_from_view(view, offset, -1);
1129                 struct event_list_element *element =
1130                                 (struct event_list_element *) zmalloc(sizeof(*element));
1131
1132                 if (!element) {
1133                         ret_code = LTTNG_ERR_NOMEM;
1134                         goto end;
1135                 }
1136
1137                 /*
1138                  * Lifetime and management of the object is now bound to the
1139                  * array.
1140                  */
1141                 ret = lttng_dynamic_pointer_array_add_pointer(
1142                                 event_list, element);
1143                 if (ret) {
1144                         event_list_destructor(element);
1145                         ret_code = LTTNG_ERR_NOMEM;
1146                         goto end;
1147                 }
1148
1149                 /*
1150                  * Bytecode is not transmitted on listing in any case we do not
1151                  * care about it.
1152                  */
1153                 event_size = lttng_event_create_from_payload(&event_view,
1154                                 &element->event,
1155                                 &element->exclusions,
1156                                 &element->filter_expression, NULL);
1157                 if (event_size < 0) {
1158                         ret_code = LTTNG_ERR_INVALID;
1159                         goto end;
1160                 }
1161
1162                 offset += event_size;
1163         }
1164
1165         if (view->buffer.size != offset) {
1166                 ret_code = LTTNG_ERR_INVALID_PROTOCOL;
1167                 goto end;
1168         }
1169
1170         ret_code = LTTNG_OK;
1171
1172 end:
1173         return ret_code;
1174 }
1175
1176 enum lttng_error_code lttng_events_create_and_flatten_from_payload(
1177                 struct lttng_payload_view *payload,
1178                 unsigned int count,
1179                 struct lttng_event **events)
1180 {
1181         enum lttng_error_code ret = LTTNG_OK;
1182         struct lttng_dynamic_pointer_array local_events;
1183
1184         lttng_dynamic_pointer_array_init(&local_events, event_list_destructor);
1185
1186         /* Deserialize the events. */
1187         {
1188                 struct lttng_payload_view events_view =
1189                                 lttng_payload_view_from_view(payload, 0, -1);
1190
1191                 ret = event_list_create_from_payload(
1192                                 &events_view, count, &local_events);
1193                 if (ret != LTTNG_OK) {
1194                         goto end;
1195                 }
1196         }
1197
1198         ret = flatten_lttng_events(&local_events, events);
1199         if (ret != LTTNG_OK) {
1200                 goto end;
1201         }
1202
1203 end:
1204         lttng_dynamic_pointer_array_reset(&local_events);
1205         return ret;
1206 }