| 1 | /* Generic BFD support for file formats. |
| 2 | Copyright (C) 1990-2016 Free Software Foundation, Inc. |
| 3 | Written by Cygnus Support. |
| 4 | |
| 5 | This file is part of BFD, the Binary File Descriptor library. |
| 6 | |
| 7 | This program is free software; you can redistribute it and/or modify |
| 8 | it under the terms of the GNU General Public License as published by |
| 9 | the Free Software Foundation; either version 3 of the License, or |
| 10 | (at your option) any later version. |
| 11 | |
| 12 | This program is distributed in the hope that it will be useful, |
| 13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 15 | GNU General Public License for more details. |
| 16 | |
| 17 | You should have received a copy of the GNU General Public License |
| 18 | along with this program; if not, write to the Free Software |
| 19 | Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, |
| 20 | MA 02110-1301, USA. */ |
| 21 | |
| 22 | |
| 23 | /* |
| 24 | SECTION |
| 25 | File formats |
| 26 | |
| 27 | A format is a BFD concept of high level file contents type. The |
| 28 | formats supported by BFD are: |
| 29 | |
| 30 | o <<bfd_object>> |
| 31 | |
| 32 | The BFD may contain data, symbols, relocations and debug info. |
| 33 | |
| 34 | o <<bfd_archive>> |
| 35 | |
| 36 | The BFD contains other BFDs and an optional index. |
| 37 | |
| 38 | o <<bfd_core>> |
| 39 | |
| 40 | The BFD contains the result of an executable core dump. |
| 41 | |
| 42 | SUBSECTION |
| 43 | File format functions |
| 44 | */ |
| 45 | |
| 46 | #include "sysdep.h" |
| 47 | #include "bfd.h" |
| 48 | #include "libbfd.h" |
| 49 | |
| 50 | /* IMPORT from targets.c. */ |
| 51 | extern const size_t _bfd_target_vector_entries; |
| 52 | |
| 53 | /* |
| 54 | FUNCTION |
| 55 | bfd_check_format |
| 56 | |
| 57 | SYNOPSIS |
| 58 | bfd_boolean bfd_check_format (bfd *abfd, bfd_format format); |
| 59 | |
| 60 | DESCRIPTION |
| 61 | Verify if the file attached to the BFD @var{abfd} is compatible |
| 62 | with the format @var{format} (i.e., one of <<bfd_object>>, |
| 63 | <<bfd_archive>> or <<bfd_core>>). |
| 64 | |
| 65 | If the BFD has been set to a specific target before the |
| 66 | call, only the named target and format combination is |
| 67 | checked. If the target has not been set, or has been set to |
| 68 | <<default>>, then all the known target backends is |
| 69 | interrogated to determine a match. If the default target |
| 70 | matches, it is used. If not, exactly one target must recognize |
| 71 | the file, or an error results. |
| 72 | |
| 73 | The function returns <<TRUE>> on success, otherwise <<FALSE>> |
| 74 | with one of the following error codes: |
| 75 | |
| 76 | o <<bfd_error_invalid_operation>> - |
| 77 | if <<format>> is not one of <<bfd_object>>, <<bfd_archive>> or |
| 78 | <<bfd_core>>. |
| 79 | |
| 80 | o <<bfd_error_system_call>> - |
| 81 | if an error occured during a read - even some file mismatches |
| 82 | can cause bfd_error_system_calls. |
| 83 | |
| 84 | o <<file_not_recognised>> - |
| 85 | none of the backends recognised the file format. |
| 86 | |
| 87 | o <<bfd_error_file_ambiguously_recognized>> - |
| 88 | more than one backend recognised the file format. |
| 89 | */ |
| 90 | |
| 91 | bfd_boolean |
| 92 | bfd_check_format (bfd *abfd, bfd_format format) |
| 93 | { |
| 94 | return bfd_check_format_matches (abfd, format, NULL); |
| 95 | } |
| 96 | |
| 97 | struct bfd_preserve |
| 98 | { |
| 99 | void *marker; |
| 100 | void *tdata; |
| 101 | flagword flags; |
| 102 | const struct bfd_arch_info *arch_info; |
| 103 | struct bfd_section *sections; |
| 104 | struct bfd_section *section_last; |
| 105 | unsigned int section_count; |
| 106 | struct bfd_hash_table section_htab; |
| 107 | }; |
| 108 | |
| 109 | /* When testing an object for compatibility with a particular target |
| 110 | back-end, the back-end object_p function needs to set up certain |
| 111 | fields in the bfd on successfully recognizing the object. This |
| 112 | typically happens in a piecemeal fashion, with failures possible at |
| 113 | many points. On failure, the bfd is supposed to be restored to its |
| 114 | initial state, which is virtually impossible. However, restoring a |
| 115 | subset of the bfd state works in practice. This function stores |
| 116 | the subset. */ |
| 117 | |
| 118 | static bfd_boolean |
| 119 | bfd_preserve_save (bfd *abfd, struct bfd_preserve *preserve) |
| 120 | { |
| 121 | preserve->tdata = abfd->tdata.any; |
| 122 | preserve->arch_info = abfd->arch_info; |
| 123 | preserve->flags = abfd->flags; |
| 124 | preserve->sections = abfd->sections; |
| 125 | preserve->section_last = abfd->section_last; |
| 126 | preserve->section_count = abfd->section_count; |
| 127 | preserve->section_htab = abfd->section_htab; |
| 128 | preserve->marker = bfd_alloc (abfd, 1); |
| 129 | if (preserve->marker == NULL) |
| 130 | return FALSE; |
| 131 | |
| 132 | return bfd_hash_table_init (&abfd->section_htab, bfd_section_hash_newfunc, |
| 133 | sizeof (struct section_hash_entry)); |
| 134 | } |
| 135 | |
| 136 | /* Clear out a subset of BFD state. */ |
| 137 | |
| 138 | static void |
| 139 | bfd_reinit (bfd *abfd) |
| 140 | { |
| 141 | abfd->tdata.any = NULL; |
| 142 | abfd->arch_info = &bfd_default_arch_struct; |
| 143 | abfd->flags &= BFD_FLAGS_SAVED; |
| 144 | bfd_section_list_clear (abfd); |
| 145 | } |
| 146 | |
| 147 | /* Restores bfd state saved by bfd_preserve_save. */ |
| 148 | |
| 149 | static void |
| 150 | bfd_preserve_restore (bfd *abfd, struct bfd_preserve *preserve) |
| 151 | { |
| 152 | bfd_hash_table_free (&abfd->section_htab); |
| 153 | |
| 154 | abfd->tdata.any = preserve->tdata; |
| 155 | abfd->arch_info = preserve->arch_info; |
| 156 | abfd->flags = preserve->flags; |
| 157 | abfd->section_htab = preserve->section_htab; |
| 158 | abfd->sections = preserve->sections; |
| 159 | abfd->section_last = preserve->section_last; |
| 160 | abfd->section_count = preserve->section_count; |
| 161 | |
| 162 | /* bfd_release frees all memory more recently bfd_alloc'd than |
| 163 | its arg, as well as its arg. */ |
| 164 | bfd_release (abfd, preserve->marker); |
| 165 | preserve->marker = NULL; |
| 166 | } |
| 167 | |
| 168 | /* Called when the bfd state saved by bfd_preserve_save is no longer |
| 169 | needed. */ |
| 170 | |
| 171 | static void |
| 172 | bfd_preserve_finish (bfd *abfd ATTRIBUTE_UNUSED, struct bfd_preserve *preserve) |
| 173 | { |
| 174 | /* It would be nice to be able to free more memory here, eg. old |
| 175 | tdata, but that's not possible since these blocks are sitting |
| 176 | inside bfd_alloc'd memory. The section hash is on a separate |
| 177 | objalloc. */ |
| 178 | bfd_hash_table_free (&preserve->section_htab); |
| 179 | preserve->marker = NULL; |
| 180 | } |
| 181 | |
| 182 | /* |
| 183 | FUNCTION |
| 184 | bfd_check_format_matches |
| 185 | |
| 186 | SYNOPSIS |
| 187 | bfd_boolean bfd_check_format_matches |
| 188 | (bfd *abfd, bfd_format format, char ***matching); |
| 189 | |
| 190 | DESCRIPTION |
| 191 | Like <<bfd_check_format>>, except when it returns FALSE with |
| 192 | <<bfd_errno>> set to <<bfd_error_file_ambiguously_recognized>>. In that |
| 193 | case, if @var{matching} is not NULL, it will be filled in with |
| 194 | a NULL-terminated list of the names of the formats that matched, |
| 195 | allocated with <<malloc>>. |
| 196 | Then the user may choose a format and try again. |
| 197 | |
| 198 | When done with the list that @var{matching} points to, the caller |
| 199 | should free it. |
| 200 | */ |
| 201 | |
| 202 | bfd_boolean |
| 203 | bfd_check_format_matches (bfd *abfd, bfd_format format, char ***matching) |
| 204 | { |
| 205 | extern const bfd_target binary_vec; |
| 206 | const bfd_target * const *target; |
| 207 | const bfd_target **matching_vector = NULL; |
| 208 | const bfd_target *save_targ, *right_targ, *ar_right_targ, *match_targ; |
| 209 | int match_count, best_count, best_match; |
| 210 | int ar_match_index; |
| 211 | struct bfd_preserve preserve; |
| 212 | |
| 213 | if (matching != NULL) |
| 214 | *matching = NULL; |
| 215 | |
| 216 | if (!bfd_read_p (abfd) |
| 217 | || (unsigned int) abfd->format >= (unsigned int) bfd_type_end) |
| 218 | { |
| 219 | bfd_set_error (bfd_error_invalid_operation); |
| 220 | return FALSE; |
| 221 | } |
| 222 | |
| 223 | if (abfd->format != bfd_unknown) |
| 224 | return abfd->format == format; |
| 225 | |
| 226 | if (matching != NULL || *bfd_associated_vector != NULL) |
| 227 | { |
| 228 | bfd_size_type amt; |
| 229 | |
| 230 | amt = sizeof (*matching_vector) * 2 * _bfd_target_vector_entries; |
| 231 | matching_vector = (const bfd_target **) bfd_malloc (amt); |
| 232 | if (!matching_vector) |
| 233 | return FALSE; |
| 234 | } |
| 235 | |
| 236 | /* Presume the answer is yes. */ |
| 237 | abfd->format = format; |
| 238 | save_targ = abfd->xvec; |
| 239 | preserve.marker = NULL; |
| 240 | |
| 241 | /* If the target type was explicitly specified, just check that target. */ |
| 242 | if (!abfd->target_defaulted) |
| 243 | { |
| 244 | if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0) /* rewind! */ |
| 245 | goto err_ret; |
| 246 | |
| 247 | right_targ = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd)); |
| 248 | |
| 249 | if (right_targ) |
| 250 | goto ok_ret; |
| 251 | |
| 252 | /* For a long time the code has dropped through to check all |
| 253 | targets if the specified target was wrong. I don't know why, |
| 254 | and I'm reluctant to change it. However, in the case of an |
| 255 | archive, it can cause problems. If the specified target does |
| 256 | not permit archives (e.g., the binary target), then we should |
| 257 | not allow some other target to recognize it as an archive, but |
| 258 | should instead allow the specified target to recognize it as an |
| 259 | object. When I first made this change, it broke the PE target, |
| 260 | because the specified pei-i386 target did not recognize the |
| 261 | actual pe-i386 archive. Since there may be other problems of |
| 262 | this sort, I changed this test to check only for the binary |
| 263 | target. */ |
| 264 | if (format == bfd_archive && save_targ == &binary_vec) |
| 265 | goto err_unrecog; |
| 266 | } |
| 267 | |
| 268 | /* Since the target type was defaulted, check them all in the hope |
| 269 | that one will be uniquely recognized. */ |
| 270 | right_targ = NULL; |
| 271 | ar_right_targ = NULL; |
| 272 | match_targ = NULL; |
| 273 | best_match = 256; |
| 274 | best_count = 0; |
| 275 | match_count = 0; |
| 276 | ar_match_index = _bfd_target_vector_entries; |
| 277 | |
| 278 | for (target = bfd_target_vector; *target != NULL; target++) |
| 279 | { |
| 280 | const bfd_target *temp; |
| 281 | |
| 282 | /* Don't check the default target twice. */ |
| 283 | if (*target == &binary_vec |
| 284 | || (!abfd->target_defaulted && *target == save_targ) |
| 285 | || (*target)->match_priority > best_match) |
| 286 | continue; |
| 287 | |
| 288 | /* If we already tried a match, the bfd is modified and may |
| 289 | have sections attached, which will confuse the next |
| 290 | _bfd_check_format call. */ |
| 291 | bfd_reinit (abfd); |
| 292 | |
| 293 | /* Change BFD's target temporarily. */ |
| 294 | abfd->xvec = *target; |
| 295 | |
| 296 | if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0) |
| 297 | goto err_ret; |
| 298 | |
| 299 | /* If _bfd_check_format neglects to set bfd_error, assume |
| 300 | bfd_error_wrong_format. We didn't used to even pay any |
| 301 | attention to bfd_error, so I suspect that some |
| 302 | _bfd_check_format might have this problem. */ |
| 303 | bfd_set_error (bfd_error_wrong_format); |
| 304 | |
| 305 | temp = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd)); |
| 306 | if (temp) |
| 307 | { |
| 308 | match_targ = temp; |
| 309 | if (preserve.marker != NULL) |
| 310 | bfd_preserve_finish (abfd, &preserve); |
| 311 | |
| 312 | if (abfd->format != bfd_archive |
| 313 | || (bfd_has_map (abfd) |
| 314 | && bfd_get_error () != bfd_error_wrong_object_format)) |
| 315 | { |
| 316 | /* This format checks out as ok! */ |
| 317 | right_targ = temp; |
| 318 | |
| 319 | /* If this is the default target, accept it, even if |
| 320 | other targets might match. People who want those |
| 321 | other targets have to set the GNUTARGET variable. */ |
| 322 | if (temp == bfd_default_vector[0]) |
| 323 | goto ok_ret; |
| 324 | |
| 325 | if (matching_vector) |
| 326 | matching_vector[match_count] = temp; |
| 327 | match_count++; |
| 328 | |
| 329 | if (temp->match_priority < best_match) |
| 330 | { |
| 331 | best_match = temp->match_priority; |
| 332 | best_count = 0; |
| 333 | } |
| 334 | best_count++; |
| 335 | } |
| 336 | else |
| 337 | { |
| 338 | /* An archive with no armap or objects of the wrong |
| 339 | type. We want this target to match if we get no |
| 340 | better matches. */ |
| 341 | if (ar_right_targ != bfd_default_vector[0]) |
| 342 | ar_right_targ = *target; |
| 343 | if (matching_vector) |
| 344 | matching_vector[ar_match_index] = *target; |
| 345 | ar_match_index++; |
| 346 | } |
| 347 | |
| 348 | if (!bfd_preserve_save (abfd, &preserve)) |
| 349 | goto err_ret; |
| 350 | } |
| 351 | else if (bfd_get_error () != bfd_error_wrong_format) |
| 352 | goto err_ret; |
| 353 | } |
| 354 | |
| 355 | if (best_count == 1) |
| 356 | match_count = 1; |
| 357 | |
| 358 | if (match_count == 0) |
| 359 | { |
| 360 | /* Try partial matches. */ |
| 361 | right_targ = ar_right_targ; |
| 362 | |
| 363 | if (right_targ == bfd_default_vector[0]) |
| 364 | { |
| 365 | match_count = 1; |
| 366 | } |
| 367 | else |
| 368 | { |
| 369 | match_count = ar_match_index - _bfd_target_vector_entries; |
| 370 | |
| 371 | if (matching_vector && match_count > 1) |
| 372 | memcpy (matching_vector, |
| 373 | matching_vector + _bfd_target_vector_entries, |
| 374 | sizeof (*matching_vector) * match_count); |
| 375 | } |
| 376 | } |
| 377 | |
| 378 | /* We have more than one equally good match. If any of the best |
| 379 | matches is a target in config.bfd targ_defvec or targ_selvecs, |
| 380 | choose it. */ |
| 381 | if (match_count > 1) |
| 382 | { |
| 383 | const bfd_target * const *assoc = bfd_associated_vector; |
| 384 | |
| 385 | while ((right_targ = *assoc++) != NULL) |
| 386 | { |
| 387 | int i = match_count; |
| 388 | |
| 389 | while (--i >= 0) |
| 390 | if (matching_vector[i] == right_targ |
| 391 | && right_targ->match_priority <= best_match) |
| 392 | break; |
| 393 | |
| 394 | if (i >= 0) |
| 395 | { |
| 396 | match_count = 1; |
| 397 | break; |
| 398 | } |
| 399 | } |
| 400 | } |
| 401 | |
| 402 | /* We still have more than one equally good match, and at least some |
| 403 | of the targets support match priority. Choose the first of the |
| 404 | best matches. */ |
| 405 | if (matching_vector && match_count > 1 && best_count != match_count) |
| 406 | { |
| 407 | int i; |
| 408 | |
| 409 | for (i = 0; i < match_count; i++) |
| 410 | { |
| 411 | right_targ = matching_vector[i]; |
| 412 | if (right_targ->match_priority <= best_match) |
| 413 | break; |
| 414 | } |
| 415 | match_count = 1; |
| 416 | } |
| 417 | |
| 418 | /* There is way too much undoing of half-known state here. We |
| 419 | really shouldn't iterate on live bfd's. Note that saving the |
| 420 | whole bfd and restoring it would be even worse; the first thing |
| 421 | you notice is that the cached bfd file position gets out of sync. */ |
| 422 | if (preserve.marker != NULL) |
| 423 | bfd_preserve_restore (abfd, &preserve); |
| 424 | |
| 425 | if (match_count == 1) |
| 426 | { |
| 427 | abfd->xvec = right_targ; |
| 428 | /* If we come out of the loop knowing that the last target that |
| 429 | matched is the one we want, then ABFD should still be in a usable |
| 430 | state (except possibly for XVEC). */ |
| 431 | if (match_targ != right_targ) |
| 432 | { |
| 433 | bfd_reinit (abfd); |
| 434 | if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0) |
| 435 | goto err_ret; |
| 436 | match_targ = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd)); |
| 437 | BFD_ASSERT (match_targ != NULL); |
| 438 | } |
| 439 | |
| 440 | ok_ret: |
| 441 | /* If the file was opened for update, then `output_has_begun' |
| 442 | some time ago when the file was created. Do not recompute |
| 443 | sections sizes or alignments in _bfd_set_section_contents. |
| 444 | We can not set this flag until after checking the format, |
| 445 | because it will interfere with creation of BFD sections. */ |
| 446 | if (abfd->direction == both_direction) |
| 447 | abfd->output_has_begun = TRUE; |
| 448 | |
| 449 | if (matching_vector) |
| 450 | free (matching_vector); |
| 451 | |
| 452 | /* File position has moved, BTW. */ |
| 453 | return TRUE; |
| 454 | } |
| 455 | |
| 456 | if (match_count == 0) |
| 457 | { |
| 458 | err_unrecog: |
| 459 | bfd_set_error (bfd_error_file_not_recognized); |
| 460 | err_ret: |
| 461 | abfd->xvec = save_targ; |
| 462 | abfd->format = bfd_unknown; |
| 463 | if (matching_vector) |
| 464 | free (matching_vector); |
| 465 | if (preserve.marker != NULL) |
| 466 | bfd_preserve_restore (abfd, &preserve); |
| 467 | return FALSE; |
| 468 | } |
| 469 | |
| 470 | /* Restore original target type and format. */ |
| 471 | abfd->xvec = save_targ; |
| 472 | abfd->format = bfd_unknown; |
| 473 | bfd_set_error (bfd_error_file_ambiguously_recognized); |
| 474 | |
| 475 | if (matching) |
| 476 | { |
| 477 | *matching = (char **) matching_vector; |
| 478 | matching_vector[match_count] = NULL; |
| 479 | /* Return target names. This is a little nasty. Maybe we |
| 480 | should do another bfd_malloc? */ |
| 481 | while (--match_count >= 0) |
| 482 | { |
| 483 | const char *name = matching_vector[match_count]->name; |
| 484 | *(const char **) &matching_vector[match_count] = name; |
| 485 | } |
| 486 | } |
| 487 | return FALSE; |
| 488 | } |
| 489 | |
| 490 | /* |
| 491 | FUNCTION |
| 492 | bfd_set_format |
| 493 | |
| 494 | SYNOPSIS |
| 495 | bfd_boolean bfd_set_format (bfd *abfd, bfd_format format); |
| 496 | |
| 497 | DESCRIPTION |
| 498 | This function sets the file format of the BFD @var{abfd} to the |
| 499 | format @var{format}. If the target set in the BFD does not |
| 500 | support the format requested, the format is invalid, or the BFD |
| 501 | is not open for writing, then an error occurs. |
| 502 | */ |
| 503 | |
| 504 | bfd_boolean |
| 505 | bfd_set_format (bfd *abfd, bfd_format format) |
| 506 | { |
| 507 | if (bfd_read_p (abfd) |
| 508 | || (unsigned int) abfd->format >= (unsigned int) bfd_type_end) |
| 509 | { |
| 510 | bfd_set_error (bfd_error_invalid_operation); |
| 511 | return FALSE; |
| 512 | } |
| 513 | |
| 514 | if (abfd->format != bfd_unknown) |
| 515 | return abfd->format == format; |
| 516 | |
| 517 | /* Presume the answer is yes. */ |
| 518 | abfd->format = format; |
| 519 | |
| 520 | if (!BFD_SEND_FMT (abfd, _bfd_set_format, (abfd))) |
| 521 | { |
| 522 | abfd->format = bfd_unknown; |
| 523 | return FALSE; |
| 524 | } |
| 525 | |
| 526 | return TRUE; |
| 527 | } |
| 528 | |
| 529 | /* |
| 530 | FUNCTION |
| 531 | bfd_format_string |
| 532 | |
| 533 | SYNOPSIS |
| 534 | const char *bfd_format_string (bfd_format format); |
| 535 | |
| 536 | DESCRIPTION |
| 537 | Return a pointer to a const string |
| 538 | <<invalid>>, <<object>>, <<archive>>, <<core>>, or <<unknown>>, |
| 539 | depending upon the value of @var{format}. |
| 540 | */ |
| 541 | |
| 542 | const char * |
| 543 | bfd_format_string (bfd_format format) |
| 544 | { |
| 545 | if (((int) format < (int) bfd_unknown) |
| 546 | || ((int) format >= (int) bfd_type_end)) |
| 547 | return "invalid"; |
| 548 | |
| 549 | switch (format) |
| 550 | { |
| 551 | case bfd_object: |
| 552 | return "object"; /* Linker/assembler/compiler output. */ |
| 553 | case bfd_archive: |
| 554 | return "archive"; /* Object archive file. */ |
| 555 | case bfd_core: |
| 556 | return "core"; /* Core dump. */ |
| 557 | default: |
| 558 | return "unknown"; |
| 559 | } |
| 560 | } |