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