lib/so-info.c

   1 /*
   2  * so-info.c
   3  *
   4  * Babeltrace - Executable and Shared Object Debug Info Reader
   5  *
   6  * Copyright 2015 Antoine Busque <abusque@efficios.com>
   7  *
   8  * Author: Antoine Busque <abusque@efficios.com>
   9  *
  10  * Permission is hereby granted, free of charge, to any person obtaining a copy
  11  * of this software and associated documentation files (the "Software"), to deal
  12  * in the Software without restriction, including without limitation the rights
  13  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  14  * copies of the Software, and to permit persons to whom the Software is
  15  * furnished to do so, subject to the following conditions:
  16  *
  17  * The above copyright notice and this permission notice shall be included in
  18  * all copies or substantial portions of the Software.
  19  *
  20  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  21  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  23  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  24  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  25  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  26  * SOFTWARE.
  27  */
  28
  29 #include <fcntl.h>
  30 #include <math.h>
  31 #include <libgen.h>
  32 #include <stdio.h>
  33 #include <inttypes.h>
  34 #include <stdlib.h>
  35 #include <string.h>
  36 #include <unistd.h>
  37 #include <dwarf.h>
  38 #include <glib.h>
  39 #include <babeltrace/dwarf.h>
  40 #include <babeltrace/so-info.h>
  41 #include <babeltrace/crc32.h>
  42 #include <babeltrace/babeltrace-internal.h>
  43 #include <babeltrace/utils.h>
  44
  45 /*
  46  * An address printed in hex is at most 20 bytes (16 for 64-bits +
  47  * leading 0x + optional leading '+' if addr is an offset + null
  48  * character).
  49  */
  50 #define ADDR_STR_LEN 20
  51
  52 BT_HIDDEN
  53 int so_info_init(void)
  54 {
  55         int ret = 0;
  56
  57         if (elf_version(EV_CURRENT) == EV_NONE) {
  58                 fprintf(stderr, "ELF library initialization failed: %s\n",
  59                         elf_errmsg(-1));
  60                 ret = -1;
  61         }
  62
  63         return ret;
  64 }
  65
  66 BT_HIDDEN
  67 struct so_info *so_info_create(const char *path, uint64_t low_addr,
  68                 uint64_t memsz, bool is_pic)
  69 {
  70         struct so_info *so = NULL;
  71
  72         if (!path) {
  73                 goto error;
  74         }
  75
  76         so = g_new0(struct so_info, 1);
  77         if (!so) {
  78                 goto error;
  79         }
  80
  81         if (opt_debug_info_target_prefix) {
  82                 so->elf_path = g_build_path("/", opt_debug_info_target_prefix,
  83                                                 path, NULL);
  84         } else {
  85                 so->elf_path = strdup(path);
  86         }
  87
  88         if (!so->elf_path) {
  89                 goto error;
  90         }
  91
  92         so->is_pic = is_pic;
  93         so->memsz = memsz;
  94         so->low_addr = low_addr;
  95         so->high_addr = so->low_addr + so->memsz;
  96
  97         return so;
  98
  99 error:
 100         so_info_destroy(so);
 101         return NULL;
 102 }
 103
 104 BT_HIDDEN
 105 void so_info_destroy(struct so_info *so)
 106 {
 107         if (!so) {
 108                 return;
 109         }
 110
 111         dwarf_end(so->dwarf_info);
 112
 113         free(so->elf_path);
 114         free(so->dwarf_path);
 115         free(so->build_id);
 116         free(so->dbg_link_filename);
 117
 118         elf_end(so->elf_file);
 119
 120         close(so->elf_fd);
 121         close(so->dwarf_fd);
 122
 123         g_free(so);
 124 }
 125
 126
 127 BT_HIDDEN
 128 int so_info_set_build_id(struct so_info *so, uint8_t *build_id,
 129                 size_t build_id_len)
 130 {
 131         if (!so || !build_id) {
 132                 goto error;
 133         }
 134
 135         so->build_id = malloc(build_id_len);
 136         if (!so->build_id) {
 137                 goto error;
 138         }
 139
 140         memcpy(so->build_id, build_id, build_id_len);
 141         so->build_id_len = build_id_len;
 142
 143         /*
 144          * Reset the is_elf_only flag in case it had been set
 145          * previously, because we might find separate debug info using
 146          * the new build id information.
 147          */
 148         so->is_elf_only = false;
 149
 150         return 0;
 151
 152 error:
 153
 154         return -1;
 155 }
 156
 157 BT_HIDDEN
 158 int so_info_set_debug_link(struct so_info *so, char *filename, uint32_t crc)
 159 {
 160         if (!so || !filename) {
 161                 goto error;
 162         }
 163
 164         so->dbg_link_filename = strdup(filename);
 165         if (!so->dbg_link_filename) {
 166                 goto error;
 167         }
 168
 169         so->dbg_link_crc = crc;
 170
 171         /*
 172          * Reset the is_elf_only flag in case it had been set
 173          * previously, because we might find separate debug info using
 174          * the new build id information.
 175          */
 176         so->is_elf_only = false;
 177
 178         return 0;
 179
 180 error:
 181
 182         return -1;
 183 }
 184
 185 /**
 186  * Tries to read DWARF info from the location given by path, and
 187  * attach it to the given so_info instance if it exists.
 188  *
 189  * @param so    so_info instance for which to set DWARF info
 190  * @param path  Presumed location of the DWARF info
 191  * @returns     0 on success, -1 on failure
 192  */
 193 static
 194 int so_info_set_dwarf_info_from_path(struct so_info *so, char *path)
 195 {
 196         int fd = -1, ret = 0;
 197         struct bt_dwarf_cu *cu = NULL;
 198         Dwarf *dwarf_info = NULL;
 199
 200         if (!so || !path) {
 201                 goto error;
 202         }
 203
 204         fd = open(path, O_RDONLY);
 205         if (fd < 0) {
 206                 goto error;
 207         }
 208
 209         dwarf_info = dwarf_begin(fd, DWARF_C_READ);
 210         if (!dwarf_info) {
 211                 goto error;
 212         }
 213
 214         /*
 215          * Check if the dwarf info has any CU. If not, the SO's object
 216          * file contains no DWARF info.
 217          */
 218         cu = bt_dwarf_cu_create(dwarf_info);
 219         if (!cu) {
 220                 goto error;
 221         }
 222
 223         ret = bt_dwarf_cu_next(cu);
 224         if (ret) {
 225                 goto error;
 226         }
 227
 228         so->dwarf_fd = fd;
 229         so->dwarf_path = strdup(path);
 230         if (!so->dwarf_path) {
 231                 goto error;
 232         }
 233         so->dwarf_info = dwarf_info;
 234         free(cu);
 235
 236         return 0;
 237
 238 error:
 239         close(fd);
 240         dwarf_end(dwarf_info);
 241         g_free(dwarf_info);
 242         free(cu);
 243
 244         return -1;
 245 }
 246
 247 /**
 248  * Try to set the dwarf_info for a given so_info instance via the
 249  * build ID method.
 250  *
 251  * @param so            so_info instance for which to retrieve the
 252  *                      DWARF info via build ID
 253  * @returns             0 on success (i.e. dwarf_info set), -1 on failure
 254  */
 255 static
 256 int so_info_set_dwarf_info_build_id(struct so_info *so)
 257 {
 258         int i = 0, ret = 0;
 259         char *path = NULL, *build_id_file = NULL;
 260         const char *dbg_dir = NULL;
 261         size_t build_id_file_len;
 262
 263         if (!so || !so->build_id) {
 264                 goto error;
 265         }
 266
 267         dbg_dir = opt_debug_info_dir ? : DEFAULT_DEBUG_DIR;
 268
 269         /* 2 characters per byte printed in hex, +1 for '/' and +1 for
 270          * '\0' */
 271         build_id_file_len = (2 * so->build_id_len) + 1 +
 272                         strlen(BUILD_ID_SUFFIX) + 1;
 273         build_id_file = malloc(build_id_file_len);
 274         if (!build_id_file) {
 275                 goto error;
 276         }
 277
 278         snprintf(build_id_file, 4, "%02x/", so->build_id[0]);
 279         for (i = 1; i < so->build_id_len; ++i) {
 280                 int path_idx = 3 + 2 * (i - 1);
 281
 282                 snprintf(&build_id_file[path_idx], 3, "%02x", so->build_id[i]);
 283         }
 284         strcat(build_id_file, BUILD_ID_SUFFIX);
 285
 286         path = g_build_path("/", dbg_dir, BUILD_ID_SUBDIR, build_id_file, NULL);
 287         if (!path) {
 288                 goto error;
 289         }
 290
 291         ret = so_info_set_dwarf_info_from_path(so, path);
 292         if (ret) {
 293                 goto error;
 294         }
 295
 296         goto end;
 297
 298 error:
 299         ret = -1;
 300 end:
 301         free(build_id_file);
 302         free(path);
 303
 304         return ret;
 305 }
 306
 307 /**
 308  * Tests whether the file located at path exists and has the expected
 309  * checksum.
 310  *
 311  * This predicate is used when looking up separate debug info via the
 312  * GNU debuglink method. The expected crc can be found .gnu_debuglink
 313  * section in the original ELF file, along with the filename for the
 314  * file containing the debug info.
 315  *
 316  * @param path  Full path at which to look for the debug file
 317  * @param crc   Expected checksum for the debug file
 318  * @returns     1 if the file exists and has the correct checksum,
 319  *              0 otherwise
 320  */
 321 static
 322 int is_valid_debug_file(char *path, uint32_t crc)
 323 {
 324         int ret = 0, fd = -1;
 325         uint32_t _crc = 0;
 326
 327         if (!path) {
 328                 goto end;
 329         }
 330
 331         fd = open(path, O_RDONLY);
 332         if (fd < 0) {
 333                 goto end;
 334         }
 335
 336         ret = crc32(fd, &_crc);
 337         if (ret) {
 338                 ret = 0;
 339                 goto end;
 340         }
 341
 342         ret = (crc == _crc);
 343
 344 end:
 345         close(fd);
 346         return ret;
 347 }
 348
 349 /**
 350  * Try to set the dwarf_info for a given so_info instance via the
 351  * build ID method.
 352  *
 353  * @param so            so_info instance for which to retrieve the
 354  *                      DWARF info via debug link
 355  * @returns             0 on success (i.e. dwarf_info set), -1 on failure
 356  */
 357 static
 358 int so_info_set_dwarf_info_debug_link(struct so_info *so)
 359 {
 360         int ret = 0;
 361         const char *dbg_dir = NULL;
 362         char *dir_name = NULL, *so_dir = NULL, *path = NULL;
 363         size_t max_path_len = 0;
 364
 365         if (!so || !so->dbg_link_filename) {
 366                 goto error;
 367         }
 368
 369         dbg_dir = opt_debug_info_dir ? : DEFAULT_DEBUG_DIR;
 370
 371         dir_name = dirname(so->elf_path);
 372         if (!dir_name) {
 373                 goto error;
 374         }
 375
 376         /* so_dir is just dir_name with a trailing slash */
 377         so_dir = malloc(strlen(dir_name) + 2);
 378         if (!so_dir) {
 379                 goto error;
 380         }
 381
 382         strcpy(so_dir, dir_name);
 383         strcat(so_dir, "/");
 384
 385         max_path_len = strlen(dbg_dir) + strlen(so_dir) +
 386                         strlen(DEBUG_SUBDIR) + strlen(so->dbg_link_filename)
 387                         + 1;
 388         path = malloc(max_path_len);
 389         if (!path) {
 390                 goto error;
 391         }
 392
 393         /* First look in the SO's dir */
 394         strcpy(path, so_dir);
 395         strcat(path, so->dbg_link_filename);
 396
 397         if (is_valid_debug_file(path, so->dbg_link_crc)) {
 398                 goto found;
 399         }
 400
 401         /* If not found, look in .debug subdir */
 402         strcpy(path, so_dir);
 403         strcat(path, DEBUG_SUBDIR);
 404         strcat(path, so->dbg_link_filename);
 405
 406         if (is_valid_debug_file(path, so->dbg_link_crc)) {
 407                 goto found;
 408         }
 409
 410         /* Lastly, look under the global debug directory */
 411         strcpy(path, dbg_dir);
 412         strcat(path, so_dir);
 413         strcat(path, so->dbg_link_filename);
 414
 415         if (is_valid_debug_file(path, so->dbg_link_crc)) {
 416                 goto found;
 417         }
 418
 419 error:
 420         ret = -1;
 421 end:
 422         free(path);
 423         free(so_dir);
 424
 425         return ret;
 426
 427 found:
 428         ret = so_info_set_dwarf_info_from_path(so, path);
 429         if (ret) {
 430                 goto error;
 431         }
 432
 433         goto end;
 434 }
 435
 436 /**
 437  * Initialize the DWARF info for a given executable.
 438  *
 439  * @param so    so_info instance
 440  * @returns     0 on success, -1 on failure
 441  */
 442 static
 443 int so_info_set_dwarf_info(struct so_info *so)
 444 {
 445         int ret = 0;
 446
 447         if (!so) {
 448                 goto error;
 449         }
 450
 451         /* First try to set the DWARF info from the ELF file */
 452         ret = so_info_set_dwarf_info_from_path(so, so->elf_path);
 453         if (!ret) {
 454                 goto end;
 455         }
 456
 457         /*
 458          * If that fails, try to find separate debug info via build ID
 459          * and debug link.
 460          */
 461         ret = so_info_set_dwarf_info_build_id(so);
 462         if (!ret) {
 463                 goto end;
 464         }
 465
 466         ret = so_info_set_dwarf_info_debug_link(so);
 467         if (!ret) {
 468                 goto end;
 469         }
 470
 471 error:
 472         ret = -1;
 473 end:
 474         return ret;
 475 }
 476
 477 /**
 478  * Initialize the ELF file for a given executable.
 479  *
 480  * @param so    so_info instance
 481  * @returns     0 on success, -1 on failure
 482  */
 483 static
 484 int so_info_set_elf_file(struct so_info *so)
 485 {
 486         int elf_fd;
 487         Elf *elf_file = NULL;
 488
 489         if (!so) {
 490                 goto error;
 491         }
 492
 493         elf_fd = open(so->elf_path, O_RDONLY);
 494         if (elf_fd < 0) {
 495                 fprintf(stderr, "Failed to open %s\n", so->elf_path);
 496                 goto error;
 497         }
 498
 499         elf_file = elf_begin(elf_fd, ELF_C_READ, NULL);
 500         if (!elf_file) {
 501                 fprintf(stderr, "elf_begin failed: %s\n", elf_errmsg(-1));
 502                 goto error;
 503         }
 504
 505         if (elf_kind(elf_file) != ELF_K_ELF) {
 506                 fprintf(stderr, "Error: %s is not an ELF object\n",
 507                                 so->elf_path);
 508                 goto error;
 509         }
 510
 511         so->elf_fd = elf_fd;
 512         so->elf_file = elf_file;
 513         return 0;
 514
 515 error:
 516         close(elf_fd);
 517         elf_end(elf_file);
 518         return -1;
 519 }
 520
 521
 522 BT_HIDDEN
 523 void source_location_destroy(struct source_location *src_loc)
 524 {
 525         if (!src_loc) {
 526                 return;
 527         }
 528
 529         free(src_loc->filename);
 530         g_free(src_loc);
 531 }
 532 /**
 533  * Append a string representation of an address offset to an existing
 534  * string.
 535  *
 536  * On success, the out parameter `result` will contain the base string
 537  * followed by the offset string of the form "+0x1234". On failure,
 538  * `result` remains unchanged.
 539  *
 540  * @param base_str      The string to which to append an offset string
 541  * @param low_addr      The lower virtual memory address, the base from
 542  *                      which the offset is computed
 543  * @param high_addr     The higher virtual memory address
 544  * @param result        Out parameter, the base string followed by the
 545  *                      offset string
 546  * @returns             0 on success, -1 on failure
 547  */
 548 static
 549 int so_info_append_offset_str(const char *base_str, uint64_t low_addr,
 550                                 uint64_t high_addr, char **result)
 551 {
 552         int ret;
 553         uint64_t offset;
 554         char *_result = NULL;
 555         char offset_str[ADDR_STR_LEN];
 556
 557         if (!base_str || !result) {
 558                 goto error;
 559         }
 560
 561         offset = high_addr - low_addr;
 562
 563         _result = malloc(strlen(base_str) + ADDR_STR_LEN);
 564         if (!_result) {
 565                 goto error;
 566         }
 567
 568         ret = snprintf(offset_str, ADDR_STR_LEN, "+%#0" PRIx64, offset);
 569         if (ret < 0) {
 570                 goto error;
 571         }
 572         strcpy(_result, base_str);
 573         strcat(_result, offset_str);
 574         *result = _result;
 575
 576         return 0;
 577
 578 error:
 579         free(_result);
 580         return -1;
 581 }
 582
 583 /**
 584  * Try to find the symbol closest to an address within a given ELF
 585  * section.
 586  *
 587  * Only function symbols are taken into account. The symbol's address
 588  * must precede `addr`. A symbol with a closer address might exist
 589  * after `addr` but is irrelevant because it cannot encompass `addr`.
 590  *
 591  * On success, if found, the out parameters `sym` and `shdr` are
 592  * set. On failure or if none are found, they remain unchanged.
 593  *
 594  * @param scn           ELF section in which to look for the address
 595  * @param addr          Virtual memory address for which to find the
 596  *                      nearest function symbol
 597  * @param sym           Out parameter, the nearest function symbol
 598  * @param shdr          Out parameter, the section header for scn
 599  * @returns             0 on success, -1 on failure
 600  */
 601 static
 602 int so_info_get_nearest_symbol_from_section(Elf_Scn *scn, uint64_t addr,
 603                 GElf_Sym **sym, GElf_Shdr **shdr)
 604 {
 605         int i;
 606         size_t symbol_count;
 607         Elf_Data *data = NULL;
 608         GElf_Shdr *_shdr = NULL;
 609         GElf_Sym *nearest_sym = NULL;
 610
 611         if (!scn || !sym || !shdr) {
 612                 goto error;
 613         }
 614
 615         _shdr = g_new0(GElf_Shdr, 1);
 616         if (!_shdr) {
 617                 goto error;
 618         }
 619
 620         _shdr = gelf_getshdr(scn, _shdr);
 621         if (!_shdr) {
 622                 goto error;
 623         }
 624
 625         if (_shdr->sh_type != SHT_SYMTAB) {
 626                 /*
 627                  * We are only interested in symbol table (symtab)
 628                  * sections, skip this one.
 629                  */
 630                 goto end;
 631         }
 632
 633         data = elf_getdata(scn, NULL);
 634         if (!data) {
 635                 goto error;
 636         }
 637
 638         symbol_count = _shdr->sh_size / _shdr->sh_entsize;
 639
 640         for (i = 0; i < symbol_count; ++i) {
 641                 GElf_Sym *cur_sym = NULL;
 642
 643                 cur_sym = g_new0(GElf_Sym, 1);
 644                 if (!cur_sym) {
 645                         goto error;
 646                 }
 647                 cur_sym = gelf_getsym(data, i, cur_sym);
 648                 if (!cur_sym) {
 649                         goto error;
 650                 }
 651                 if (GELF_ST_TYPE(cur_sym->st_info) != STT_FUNC) {
 652                         /* We're only interested in the functions. */
 653                         g_free(cur_sym);
 654                         continue;
 655                 }
 656
 657                 if (cur_sym->st_value <= addr &&
 658                                 (!nearest_sym ||
 659                                 cur_sym->st_value > nearest_sym->st_value)) {
 660                         g_free(nearest_sym);
 661                         nearest_sym = cur_sym;
 662                 } else {
 663                         g_free(cur_sym);
 664                 }
 665         }
 666
 667 end:
 668         if (nearest_sym) {
 669                 *sym = nearest_sym;
 670                 *shdr = _shdr;
 671         } else {
 672                 g_free(_shdr);
 673         }
 674
 675         return 0;
 676
 677 error:
 678         g_free(nearest_sym);
 679         g_free(_shdr);
 680         return -1;
 681 }
 682
 683 /**
 684  * Get the name of the function containing a given address within an
 685  * executable using ELF symbols.
 686  *
 687  * The function name is in fact the name of the nearest ELF symbol,
 688  * followed by the offset in bytes between the address and the symbol
 689  * (in hex), separated by a '+' character.
 690  *
 691  * If found, the out parameter `func_name` is set on success. On failure,
 692  * it remains unchanged.
 693  *
 694  * @param so            so_info instance for the executable containing
 695  *                      the address
 696  * @param addr          Virtual memory address for which to find the
 697  *                      function name
 698  * @param func_name     Out parameter, the function name
 699  * @returns             0 on success, -1 on failure
 700  */
 701 static
 702 int so_info_lookup_elf_function_name(struct so_info *so, uint64_t addr,
 703                 char **func_name)
 704 {
 705         /*
 706          * TODO (possible optimisation): if an ELF has no symtab
 707          * section, it has been stripped. Therefore, it would be wise
 708          * to store a flag indicating the stripped status after the
 709          * first iteration to prevent subsequent ones.
 710          */
 711         int ret = 0;
 712         Elf_Scn *scn = NULL;
 713         GElf_Sym *sym = NULL;
 714         GElf_Shdr *shdr = NULL;
 715         char *sym_name = NULL;
 716
 717         /* Set ELF file if it hasn't been accessed yet. */
 718         if (!so->elf_file) {
 719                 ret = so_info_set_elf_file(so);
 720                 if (ret) {
 721                         /* Failed to set ELF file. */
 722                         goto error;
 723                 }
 724         }
 725
 726         scn = elf_nextscn(so->elf_file, scn);
 727         if (!scn) {
 728                 goto error;
 729         }
 730
 731         while (scn && !sym) {
 732                 ret = so_info_get_nearest_symbol_from_section(
 733                                 scn, addr, &sym, &shdr);
 734                 if (ret) {
 735                         goto error;
 736                 }
 737
 738                 scn = elf_nextscn(so->elf_file, scn);
 739         }
 740
 741         if (sym) {
 742                 sym_name = elf_strptr(so->elf_file, shdr->sh_link,
 743                                 sym->st_name);
 744                 if (!sym_name) {
 745                         goto error;
 746                 }
 747
 748                 ret = so_info_append_offset_str(sym_name, sym->st_value, addr,
 749                                                 func_name);
 750                 if (ret) {
 751                         goto error;
 752                 }
 753         }
 754
 755         g_free(shdr);
 756         g_free(sym);
 757         return 0;
 758
 759 error:
 760         g_free(shdr);
 761         g_free(sym);
 762         return -1;
 763 }
 764
 765 /**
 766  * Get the name of the function containing a given address within a
 767  * given compile unit (CU).
 768  *
 769  * If found, the out parameter `func_name` is set on success. On
 770  * failure, it remains unchanged.
 771  *
 772  * @param cu            bt_dwarf_cu instance which may contain the address
 773  * @param addr          Virtual memory address for which to find the
 774  *                      function name
 775  * @param func_name     Out parameter, the function name
 776  * @returns             0 on success, -1 on failure
 777  */
 778 static
 779 int so_info_lookup_cu_function_name(struct bt_dwarf_cu *cu, uint64_t addr,
 780                 char **func_name)
 781 {
 782         int ret = 0, found = 0;
 783         struct bt_dwarf_die *die = NULL;
 784
 785         if (!cu || !func_name) {
 786                 goto error;
 787         }
 788
 789         die = bt_dwarf_die_create(cu);
 790         if (!die) {
 791                 goto error;
 792         }
 793
 794         while (bt_dwarf_die_next(die) == 0) {
 795                 int tag;
 796
 797                 ret = bt_dwarf_die_get_tag(die, &tag);
 798                 if (ret) {
 799                         goto error;
 800                 }
 801
 802                 if (tag == DW_TAG_subprogram) {
 803                         ret = bt_dwarf_die_contains_addr(die, addr, &found);
 804                         if (ret) {
 805                                 goto error;
 806                         }
 807
 808                         if (found) {
 809                                 break;
 810                         }
 811                 }
 812         }
 813
 814         if (found) {
 815                 uint64_t low_addr = 0;
 816                 char *die_name = NULL;
 817
 818                 ret = bt_dwarf_die_get_name(die, &die_name);
 819                 if (ret) {
 820                         goto error;
 821                 }
 822
 823                 ret = dwarf_lowpc(die->dwarf_die, &low_addr);
 824                 if (ret) {
 825                         goto error;
 826                 }
 827
 828                 ret = so_info_append_offset_str(die_name, low_addr, addr,
 829                                                 func_name);
 830                 if (ret) {
 831                         goto error;
 832                 }
 833         }
 834
 835         bt_dwarf_die_destroy(die);
 836         return 0;
 837
 838 error:
 839         bt_dwarf_die_destroy(die);
 840         return -1;
 841 }
 842
 843 /**
 844  * Get the name of the function containing a given address within an
 845  * executable using DWARF debug info.
 846  *
 847  * If found, the out parameter `func_name` is set on success. On
 848  * failure, it remains unchanged.
 849  *
 850  * @param so            so_info instance for the executable containing
 851  *                      the address
 852  * @param addr          Virtual memory address for which to find the
 853  *                      function name
 854  * @param func_name     Out parameter, the function name
 855  * @returns             0 on success, -1 on failure
 856  */
 857 static
 858 int so_info_lookup_dwarf_function_name(struct so_info *so, uint64_t addr,
 859                 char **func_name)
 860 {
 861         int ret = 0;
 862         char *_func_name = NULL;
 863         struct bt_dwarf_cu *cu = NULL;
 864
 865         if (!so || !func_name) {
 866                 goto error;
 867         }
 868
 869         cu = bt_dwarf_cu_create(so->dwarf_info);
 870         if (!cu) {
 871                 goto error;
 872         }
 873
 874         while (bt_dwarf_cu_next(cu) == 0) {
 875                 ret = so_info_lookup_cu_function_name(cu, addr, &_func_name);
 876                 if (ret) {
 877                         goto error;
 878                 }
 879
 880                 if (_func_name) {
 881                         break;
 882                 }
 883         }
 884
 885         if (_func_name) {
 886                 *func_name = _func_name;
 887         }
 888
 889         bt_dwarf_cu_destroy(cu);
 890         return 0;
 891
 892 error:
 893         bt_dwarf_cu_destroy(cu);
 894         return -1;
 895 }
 896
 897 BT_HIDDEN
 898 int so_info_lookup_function_name(struct so_info *so, uint64_t addr,
 899                 char **func_name)
 900 {
 901         int ret = 0;
 902         char *_func_name = NULL;
 903
 904         if (!so || !func_name) {
 905                 goto error;
 906         }
 907
 908         /* Set DWARF info if it hasn't been accessed yet. */
 909         if (!so->dwarf_info && !so->is_elf_only) {
 910                 ret = so_info_set_dwarf_info(so);
 911                 if (ret) {
 912                         /* Failed to set DWARF info, fallback to ELF. */
 913                         so->is_elf_only = true;
 914                 }
 915         }
 916
 917         if (!so_info_has_address(so, addr)) {
 918                 goto error;
 919         }
 920
 921         /*
 922          * Addresses in ELF and DWARF are relative to base address for
 923          * PIC, so make the address argument relative too if needed.
 924          */
 925         if (so->is_pic) {
 926                 addr -= so->low_addr;
 927         }
 928
 929         if (so->is_elf_only) {
 930                 ret = so_info_lookup_elf_function_name(so, addr, &_func_name);
 931         } else {
 932                 ret = so_info_lookup_dwarf_function_name(so, addr, &_func_name);
 933         }
 934
 935         if (ret || !_func_name) {
 936                 goto error;
 937         }
 938
 939         *func_name = _func_name;
 940         return 0;
 941
 942 error:
 943         return -1;
 944 }
 945
 946 BT_HIDDEN
 947 int so_info_get_bin_loc(struct so_info *so, uint64_t addr, char **bin_loc)
 948 {
 949         int ret = 0;
 950         char *_bin_loc = NULL;
 951
 952         if (!so || !bin_loc) {
 953                 goto error;
 954         }
 955
 956         if (so->is_pic) {
 957                 addr -= so->low_addr;
 958                 ret = asprintf(&_bin_loc, "+%#0" PRIx64, addr);
 959         } else {
 960                 ret = asprintf(&_bin_loc, "@%#0" PRIx64, addr);
 961         }
 962
 963         if (ret == -1 || !_bin_loc) {
 964                 goto error;
 965         }
 966
 967         *bin_loc = _bin_loc;
 968         return 0;
 969
 970 error:
 971         return -1;
 972 }
 973
 974 /**
 975  * Predicate used to determine whether the children of a given DIE
 976  * contain a specific address.
 977  *
 978  * More specifically, the parameter `die` is expected to be a
 979  * subprogram (function) DIE, and this predicate tells whether any
 980  * subroutines are inlined within this function and would contain
 981  * `addr`.
 982  *
 983  * Do note that this function advances the position of `die`. If the
 984  * address is found within one of its children, `die` will be pointing
 985  * to that child upon returning from the function, allowing to extract
 986  * the information deemed necessary.
 987  *
 988  * @param die   The parent DIE in whose children the address will be
 989  *              looked for
 990  * @param addr  The address for which to look for in the DIEs
 991  * @returns     Returns 1 if the address was found, 0 if not
 992  */
 993 static
 994 int so_info_child_die_has_address(struct bt_dwarf_die *die, uint64_t addr)
 995 {
 996         int ret = 0, contains = 0;
 997
 998         if (!die) {
 999                 goto error;
1000         }
1001
1002         ret = bt_dwarf_die_child(die);
1003         if (ret) {
1004                 goto error;
1005         }
1006
1007         do {
1008                 int tag;
1009
1010                 ret = bt_dwarf_die_get_tag(die, &tag);
1011                 if (ret) {
1012                         goto error;
1013                 }
1014
1015                 if (tag == DW_TAG_inlined_subroutine) {
1016                         ret = bt_dwarf_die_contains_addr(die, addr, &contains);
1017                         if (ret) {
1018                                 goto error;
1019                         }
1020
1021                         if (contains) {
1022                                 ret = 1;
1023                                 goto end;
1024                         }
1025                 }
1026         } while (bt_dwarf_die_next(die) == 0);
1027
1028 end:
1029         return ret;
1030
1031 error:
1032         ret = 0;
1033         goto end;
1034 }
1035
1036 /**
1037  * Lookup the source location for a given address within a CU, making
1038  * the assumption that it is contained within an inline routine in a
1039  * function.
1040  *
1041  * @param cu            bt_dwarf_cu instance in which to look for the address
1042  * @param addr          The address for which to look for
1043  * @param src_loc       Out parameter, the source location (filename and
1044  *                      line number) for the address
1045  * @returns             0 on success, -1 on failure
1046  */
1047 static
1048 int so_info_lookup_cu_src_loc_inl(struct bt_dwarf_cu *cu, uint64_t addr,
1049                 struct source_location **src_loc)
1050 {
1051         int ret = 0, found = 0;
1052         struct bt_dwarf_die *die = NULL;
1053         struct source_location *_src_loc = NULL;
1054
1055         if (!cu || !src_loc) {
1056                 goto error;
1057         }
1058
1059         die = bt_dwarf_die_create(cu);
1060         if (!die) {
1061                 goto error;
1062         }
1063
1064         while (bt_dwarf_die_next(die) == 0) {
1065                 int tag;
1066
1067                 ret = bt_dwarf_die_get_tag(die, &tag);
1068                 if (ret) {
1069                         goto error;
1070                 }
1071
1072                 if (tag == DW_TAG_subprogram) {
1073                         int contains = 0;
1074
1075                         ret = bt_dwarf_die_contains_addr(die, addr, &contains);
1076                         if (ret) {
1077                                 goto error;
1078                         }
1079
1080                         if (contains) {
1081                                 /*
1082                                  * Try to find an inlined subroutine
1083                                  * child of this DIE containing addr.
1084                                  */
1085                                 found = so_info_child_die_has_address(
1086                                                 die, addr);
1087                                 goto end;
1088                         }
1089                 }
1090         }
1091
1092 end:
1093         if (found) {
1094                 char *filename = NULL;
1095                 uint64_t line_no;
1096
1097                 _src_loc = g_new0(struct source_location, 1);
1098                 if (!_src_loc) {
1099                         goto error;
1100                 }
1101
1102                 ret = bt_dwarf_die_get_call_file(die, &filename);
1103                 if (ret) {
1104                         goto error;
1105                 }
1106                 ret = bt_dwarf_die_get_call_line(die, &line_no);
1107                 if (ret) {
1108                         free(filename);
1109                         goto error;
1110                 }
1111
1112                 _src_loc->filename = filename;
1113                 _src_loc->line_no = line_no;
1114                 *src_loc = _src_loc;
1115         }
1116
1117         bt_dwarf_die_destroy(die);
1118         return 0;
1119
1120 error:
1121         source_location_destroy(_src_loc);
1122         bt_dwarf_die_destroy(die);
1123         return -1;
1124 }
1125
1126 /**
1127  * Lookup the source location for a given address within a CU,
1128  * assuming that it is contained within an inlined function.
1129  *
1130  * A source location can be found regardless of inlining status for
1131  * this method, but in the case of an inlined function, the returned
1132  * source location will point not to the callsite but rather to the
1133  * definition site of the inline function.
1134  *
1135  * @param cu            bt_dwarf_cu instance in which to look for the address
1136  * @param addr          The address for which to look for
1137  * @param src_loc       Out parameter, the source location (filename and
1138  *                      line number) for the address
1139  * @returns             0 on success, -1 on failure
1140  */
1141 static
1142 int so_info_lookup_cu_src_loc_no_inl(struct bt_dwarf_cu *cu, uint64_t addr,
1143                 struct source_location **src_loc)
1144 {
1145         struct source_location *_src_loc = NULL;
1146         struct bt_dwarf_die *die = NULL;
1147         const char *filename = NULL;
1148         Dwarf_Line *line = NULL;
1149         Dwarf_Addr line_addr;
1150         int ret, line_no;
1151
1152         if (!cu || !src_loc) {
1153                 goto error;
1154         }
1155
1156         die = bt_dwarf_die_create(cu);
1157         if (!die) {
1158                 goto error;
1159         }
1160
1161         line = dwarf_getsrc_die(die->dwarf_die, addr);
1162         if (!line) {
1163                 goto error;
1164         }
1165
1166         ret = dwarf_lineaddr(line, &line_addr);
1167         if (ret) {
1168                 goto error;
1169         }
1170
1171         filename = dwarf_linesrc(line, NULL, NULL);
1172         if (!filename) {
1173                 goto error;
1174         }
1175
1176         if (addr == line_addr) {
1177                 _src_loc = g_new0(struct source_location, 1);
1178                 if (!_src_loc) {
1179                         goto error;
1180                 }
1181
1182                 ret = dwarf_lineno(line, &line_no);
1183                 if (ret) {
1184                         goto error;
1185                 }
1186
1187                 _src_loc->line_no = line_no;
1188                 _src_loc->filename = strdup(filename);
1189         }
1190
1191         bt_dwarf_die_destroy(die);
1192
1193         if (_src_loc) {
1194                 *src_loc = _src_loc;
1195         }
1196
1197         return 0;
1198
1199 error:
1200         source_location_destroy(_src_loc);
1201         bt_dwarf_die_destroy(die);
1202         return -1;
1203 }
1204
1205 /**
1206  * Get the source location (file name and line number) for a given
1207  * address within a compile unit (CU).
1208  *
1209  * On success, the out parameter `src_loc` is set if found. On
1210  * failure, it remains unchanged.
1211  *
1212  * @param so            bt_dwarf_cu instance for the compile unit which
1213  *                      may contain the address
1214  * @param addr          Virtual memory address for which to find the
1215  *                      source location
1216  * @param src_loc       Out parameter, the source location
1217  * @returns             0 on success, -1 on failure
1218  */
1219 static
1220 int so_info_lookup_cu_src_loc(struct bt_dwarf_cu *cu, uint64_t addr,
1221                 struct source_location **src_loc)
1222 {
1223         int ret = 0;
1224         struct source_location *_src_loc = NULL;
1225
1226         if (!cu || !src_loc) {
1227                 goto error;
1228         }
1229
1230         ret = so_info_lookup_cu_src_loc_inl(cu, addr, &_src_loc);
1231         if (ret) {
1232                 goto error;
1233         }
1234
1235         if (_src_loc) {
1236                 goto end;
1237         }
1238
1239         ret = so_info_lookup_cu_src_loc_no_inl(cu, addr, &_src_loc);
1240         if (ret) {
1241                 goto error;
1242         }
1243
1244         if (_src_loc) {
1245                 goto end;
1246         }
1247
1248 end:
1249         if (_src_loc) {
1250                 *src_loc = _src_loc;
1251         }
1252
1253         return 0;
1254
1255 error:
1256         source_location_destroy(_src_loc);
1257         return -1;
1258 }
1259
1260 BT_HIDDEN
1261 int so_info_lookup_source_location(struct so_info *so, uint64_t addr,
1262                 struct source_location **src_loc)
1263 {
1264         struct bt_dwarf_cu *cu = NULL;
1265         struct source_location *_src_loc = NULL;
1266
1267         if (!so || !src_loc) {
1268                 goto error;
1269         }
1270
1271         /* Set DWARF info if it hasn't been accessed yet. */
1272         if (!so->dwarf_info && !so->is_elf_only) {
1273                 if (so_info_set_dwarf_info(so)) {
1274                         /* Failed to set DWARF info. */
1275                         so->is_elf_only = true;
1276                 }
1277         }
1278
1279         if (so->is_elf_only) {
1280                 /* We cannot lookup source location without DWARF info. */
1281                 goto error;
1282         }
1283
1284         if (!so_info_has_address(so, addr)) {
1285                 goto error;
1286         }
1287
1288         /*
1289          * Addresses in ELF and DWARF are relative to base address for
1290          * PIC, so make the address argument relative too if needed.
1291          */
1292         if (so->is_pic) {
1293                 addr -= so->low_addr;
1294         }
1295
1296         cu = bt_dwarf_cu_create(so->dwarf_info);
1297         if (!cu) {
1298                 goto error;
1299         }
1300
1301         while (bt_dwarf_cu_next(cu) == 0) {
1302                 int ret;
1303
1304                 ret = so_info_lookup_cu_src_loc(cu, addr, &_src_loc);
1305                 if (ret) {
1306                         goto error;
1307                 }
1308
1309                 if (_src_loc) {
1310                         break;
1311                 }
1312         }
1313
1314         bt_dwarf_cu_destroy(cu);
1315         if (_src_loc) {
1316                 *src_loc = _src_loc;
1317         }
1318
1319         return 0;
1320
1321 error:
1322         source_location_destroy(_src_loc);
1323         bt_dwarf_cu_destroy(cu);
1324         return -1;
1325 }