1 /* Definitions for BFD wrappers used by GDB. 2 3 Copyright (C) 2011-2013 Free Software Foundation, Inc. 4 5 This file is part of GDB. 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, see <http://www.gnu.org/licenses/>. */ 19 20 #include "defs.h" 21 #include "gdb_bfd.h" 22 #include "gdb_assert.h" 23 #include "gdb_string.h" 24 #include "ui-out.h" 25 #include "gdbcmd.h" 26 #include "hashtab.h" 27 #ifdef HAVE_ZLIB_H 28 #include <zlib.h> 29 #endif 30 #ifdef HAVE_MMAP 31 #include <sys/mman.h> 32 #ifndef MAP_FAILED 33 #define MAP_FAILED ((void *) -1) 34 #endif 35 #endif 36 37 /* An object of this type is stored in the section's user data when 38 mapping a section. */ 39 40 struct gdb_bfd_section_data 41 { 42 /* Size of the data. */ 43 bfd_size_type size; 44 /* If the data was mmapped, this is the length of the map. */ 45 bfd_size_type map_len; 46 /* The data. If NULL, the section data has not been read. */ 47 void *data; 48 /* If the data was mmapped, this is the map address. */ 49 void *map_addr; 50 }; 51 52 /* A hash table holding every BFD that gdb knows about. This is not 53 to be confused with 'gdb_bfd_cache', which is used for sharing 54 BFDs; in contrast, this hash is used just to implement 55 "maint info bfd". */ 56 57 static htab_t all_bfds; 58 59 /* See gdb_bfd.h. */ 60 61 void 62 gdb_bfd_stash_filename (struct bfd *abfd) 63 { 64 char *name = bfd_get_filename (abfd); 65 char *data; 66 67 data = bfd_alloc (abfd, strlen (name) + 1); 68 strcpy (data, name); 69 70 /* Unwarranted chumminess with BFD. */ 71 abfd->filename = data; 72 } 73 74 /* An object of this type is stored in each BFD's user data. */ 75 76 struct gdb_bfd_data 77 { 78 /* The reference count. */ 79 int refc; 80 81 /* The mtime of the BFD at the point the cache entry was made. */ 82 time_t mtime; 83 84 /* If the BFD comes from an archive, this points to the archive's 85 BFD. Otherwise, this is NULL. */ 86 bfd *archive_bfd; 87 88 /* The registry. */ 89 REGISTRY_FIELDS; 90 }; 91 92 #define GDB_BFD_DATA_ACCESSOR(ABFD) \ 93 ((struct gdb_bfd_data *) bfd_usrdata (ABFD)) 94 95 DEFINE_REGISTRY (bfd, GDB_BFD_DATA_ACCESSOR) 96 97 /* A hash table storing all the BFDs maintained in the cache. */ 98 99 static htab_t gdb_bfd_cache; 100 101 /* The type of an object being looked up in gdb_bfd_cache. We use 102 htab's capability of storing one kind of object (BFD in this case) 103 and using a different sort of object for searching. */ 104 105 struct gdb_bfd_cache_search 106 { 107 /* The filename. */ 108 const char *filename; 109 /* The mtime. */ 110 time_t mtime; 111 }; 112 113 /* A hash function for BFDs. */ 114 115 static hashval_t 116 hash_bfd (const void *b) 117 { 118 const bfd *abfd = b; 119 120 /* It is simplest to just hash the filename. */ 121 return htab_hash_string (bfd_get_filename (abfd)); 122 } 123 124 /* An equality function for BFDs. Note that this expects the caller 125 to search using struct gdb_bfd_cache_search only, not BFDs. */ 126 127 static int 128 eq_bfd (const void *a, const void *b) 129 { 130 const bfd *abfd = a; 131 const struct gdb_bfd_cache_search *s = b; 132 struct gdb_bfd_data *gdata = bfd_usrdata (abfd); 133 134 return (gdata->mtime == s->mtime 135 && strcmp (bfd_get_filename (abfd), s->filename) == 0); 136 } 137 138 /* See gdb_bfd.h. */ 139 140 struct bfd * 141 gdb_bfd_open (const char *name, const char *target, int fd) 142 { 143 hashval_t hash; 144 void **slot; 145 bfd *abfd; 146 struct gdb_bfd_cache_search search; 147 struct stat st; 148 149 if (gdb_bfd_cache == NULL) 150 gdb_bfd_cache = htab_create_alloc (1, hash_bfd, eq_bfd, NULL, 151 xcalloc, xfree); 152 153 if (fd == -1) 154 { 155 fd = open (name, O_RDONLY | O_BINARY); 156 if (fd == -1) 157 { 158 bfd_set_error (bfd_error_system_call); 159 return NULL; 160 } 161 } 162 163 search.filename = name; 164 if (fstat (fd, &st) < 0) 165 { 166 /* Weird situation here. */ 167 search.mtime = 0; 168 } 169 else 170 search.mtime = st.st_mtime; 171 172 /* Note that this must compute the same result as hash_bfd. */ 173 hash = htab_hash_string (name); 174 /* Note that we cannot use htab_find_slot_with_hash here, because 175 opening the BFD may fail; and this would violate hashtab 176 invariants. */ 177 abfd = htab_find_with_hash (gdb_bfd_cache, &search, hash); 178 if (abfd != NULL) 179 { 180 close (fd); 181 gdb_bfd_ref (abfd); 182 return abfd; 183 } 184 185 abfd = bfd_fopen (name, target, FOPEN_RB, fd); 186 if (abfd == NULL) 187 return NULL; 188 189 slot = htab_find_slot_with_hash (gdb_bfd_cache, &search, hash, INSERT); 190 gdb_assert (!*slot); 191 *slot = abfd; 192 193 gdb_bfd_stash_filename (abfd); 194 gdb_bfd_ref (abfd); 195 return abfd; 196 } 197 198 /* A helper function that releases any section data attached to the 199 BFD. */ 200 201 static void 202 free_one_bfd_section (bfd *abfd, asection *sectp, void *ignore) 203 { 204 struct gdb_bfd_section_data *sect = bfd_get_section_userdata (abfd, sectp); 205 206 if (sect != NULL && sect->data != NULL) 207 { 208 #ifdef HAVE_MMAP 209 if (sect->map_addr != NULL) 210 { 211 int res; 212 213 res = munmap (sect->map_addr, sect->map_len); 214 gdb_assert (res == 0); 215 } 216 else 217 #endif 218 xfree (sect->data); 219 } 220 } 221 222 /* Close ABFD, and warn if that fails. */ 223 224 static int 225 gdb_bfd_close_or_warn (struct bfd *abfd) 226 { 227 int ret; 228 char *name = bfd_get_filename (abfd); 229 230 bfd_map_over_sections (abfd, free_one_bfd_section, NULL); 231 232 ret = bfd_close (abfd); 233 234 if (!ret) 235 warning (_("cannot close \"%s\": %s"), 236 name, bfd_errmsg (bfd_get_error ())); 237 238 return ret; 239 } 240 241 /* See gdb_bfd.h. */ 242 243 void 244 gdb_bfd_ref (struct bfd *abfd) 245 { 246 struct gdb_bfd_data *gdata; 247 void **slot; 248 249 if (abfd == NULL) 250 return; 251 252 gdata = bfd_usrdata (abfd); 253 254 if (gdata != NULL) 255 { 256 gdata->refc += 1; 257 return; 258 } 259 260 /* Ask BFD to decompress sections in bfd_get_full_section_contents. */ 261 abfd->flags |= BFD_DECOMPRESS; 262 263 gdata = bfd_zalloc (abfd, sizeof (struct gdb_bfd_data)); 264 gdata->refc = 1; 265 gdata->mtime = bfd_get_mtime (abfd); 266 gdata->archive_bfd = NULL; 267 bfd_usrdata (abfd) = gdata; 268 269 bfd_alloc_data (abfd); 270 271 /* This is the first we've seen it, so add it to the hash table. */ 272 slot = htab_find_slot (all_bfds, abfd, INSERT); 273 gdb_assert (slot && !*slot); 274 *slot = abfd; 275 } 276 277 /* See gdb_bfd.h. */ 278 279 void 280 gdb_bfd_unref (struct bfd *abfd) 281 { 282 struct gdb_bfd_data *gdata; 283 struct gdb_bfd_cache_search search; 284 bfd *archive_bfd; 285 286 if (abfd == NULL) 287 return; 288 289 gdata = bfd_usrdata (abfd); 290 gdb_assert (gdata->refc >= 1); 291 292 gdata->refc -= 1; 293 if (gdata->refc > 0) 294 return; 295 296 archive_bfd = gdata->archive_bfd; 297 search.filename = bfd_get_filename (abfd); 298 299 if (gdb_bfd_cache && search.filename) 300 { 301 hashval_t hash = htab_hash_string (search.filename); 302 void **slot; 303 304 search.mtime = gdata->mtime; 305 slot = htab_find_slot_with_hash (gdb_bfd_cache, &search, hash, 306 NO_INSERT); 307 308 if (slot && *slot) 309 htab_clear_slot (gdb_bfd_cache, slot); 310 } 311 312 bfd_free_data (abfd); 313 bfd_usrdata (abfd) = NULL; /* Paranoia. */ 314 315 htab_remove_elt (all_bfds, abfd); 316 317 gdb_bfd_close_or_warn (abfd); 318 319 gdb_bfd_unref (archive_bfd); 320 } 321 322 /* A helper function that returns the section data descriptor 323 associated with SECTION. If no such descriptor exists, a new one 324 is allocated and cleared. */ 325 326 static struct gdb_bfd_section_data * 327 get_section_descriptor (asection *section) 328 { 329 struct gdb_bfd_section_data *result; 330 331 result = bfd_get_section_userdata (section->owner, section); 332 333 if (result == NULL) 334 { 335 result = bfd_zalloc (section->owner, sizeof (*result)); 336 bfd_set_section_userdata (section->owner, section, result); 337 } 338 339 return result; 340 } 341 342 /* See gdb_bfd.h. */ 343 344 const gdb_byte * 345 gdb_bfd_map_section (asection *sectp, bfd_size_type *size) 346 { 347 bfd *abfd; 348 struct gdb_bfd_section_data *descriptor; 349 bfd_byte *data; 350 351 gdb_assert ((sectp->flags & SEC_RELOC) == 0); 352 gdb_assert (size != NULL); 353 354 abfd = sectp->owner; 355 356 descriptor = get_section_descriptor (sectp); 357 358 /* If the data was already read for this BFD, just reuse it. */ 359 if (descriptor->data != NULL) 360 goto done; 361 362 #ifdef HAVE_MMAP 363 if (!bfd_is_section_compressed (abfd, sectp)) 364 { 365 /* The page size, used when mmapping. */ 366 static int pagesize; 367 368 if (pagesize == 0) 369 pagesize = getpagesize (); 370 371 /* Only try to mmap sections which are large enough: we don't want 372 to waste space due to fragmentation. */ 373 374 if (bfd_get_section_size (sectp) > 4 * pagesize) 375 { 376 descriptor->size = bfd_get_section_size (sectp); 377 descriptor->data = bfd_mmap (abfd, 0, descriptor->size, PROT_READ, 378 MAP_PRIVATE, sectp->filepos, 379 &descriptor->map_addr, 380 &descriptor->map_len); 381 382 if ((caddr_t)descriptor->data != MAP_FAILED) 383 { 384 #if HAVE_POSIX_MADVISE 385 posix_madvise (descriptor->map_addr, descriptor->map_len, 386 POSIX_MADV_WILLNEED); 387 #endif 388 goto done; 389 } 390 391 /* On failure, clear out the section data and try again. */ 392 memset (descriptor, 0, sizeof (*descriptor)); 393 } 394 } 395 #endif /* HAVE_MMAP */ 396 397 /* Handle compressed sections, or ordinary uncompressed sections in 398 the no-mmap case. */ 399 400 descriptor->size = bfd_get_section_size (sectp); 401 descriptor->data = NULL; 402 403 data = NULL; 404 if (!bfd_get_full_section_contents (abfd, sectp, &data)) 405 error (_("Can't read data for section '%s' in file '%s'"), 406 bfd_get_section_name (abfd, sectp), 407 bfd_get_filename (abfd)); 408 descriptor->data = data; 409 410 done: 411 gdb_assert (descriptor->data != NULL); 412 *size = descriptor->size; 413 return descriptor->data; 414 } 415 416 417 418 /* See gdb_bfd.h. */ 419 420 bfd * 421 gdb_bfd_fopen (const char *filename, const char *target, const char *mode, 422 int fd) 423 { 424 bfd *result = bfd_fopen (filename, target, mode, fd); 425 426 if (result) 427 { 428 gdb_bfd_stash_filename (result); 429 gdb_bfd_ref (result); 430 } 431 432 return result; 433 } 434 435 /* See gdb_bfd.h. */ 436 437 bfd * 438 gdb_bfd_openr (const char *filename, const char *target) 439 { 440 bfd *result = bfd_openr (filename, target); 441 442 if (result) 443 { 444 gdb_bfd_stash_filename (result); 445 gdb_bfd_ref (result); 446 } 447 448 return result; 449 } 450 451 /* See gdb_bfd.h. */ 452 453 bfd * 454 gdb_bfd_openw (const char *filename, const char *target) 455 { 456 bfd *result = bfd_openw (filename, target); 457 458 if (result) 459 { 460 gdb_bfd_stash_filename (result); 461 gdb_bfd_ref (result); 462 } 463 464 return result; 465 } 466 467 /* See gdb_bfd.h. */ 468 469 bfd * 470 gdb_bfd_openr_iovec (const char *filename, const char *target, 471 void *(*open_func) (struct bfd *nbfd, 472 void *open_closure), 473 void *open_closure, 474 file_ptr (*pread_func) (struct bfd *nbfd, 475 void *stream, 476 void *buf, 477 file_ptr nbytes, 478 file_ptr offset), 479 int (*close_func) (struct bfd *nbfd, 480 void *stream), 481 int (*stat_func) (struct bfd *abfd, 482 void *stream, 483 struct stat *sb)) 484 { 485 bfd *result = bfd_openr_iovec (filename, target, 486 open_func, open_closure, 487 pread_func, close_func, stat_func); 488 489 if (result) 490 { 491 gdb_bfd_ref (result); 492 gdb_bfd_stash_filename (result); 493 } 494 495 return result; 496 } 497 498 /* See gdb_bfd.h. */ 499 500 void 501 gdb_bfd_mark_parent (bfd *child, bfd *parent) 502 { 503 struct gdb_bfd_data *gdata; 504 505 gdb_bfd_ref (child); 506 /* No need to stash the filename here, because we also keep a 507 reference on the parent archive. */ 508 509 gdata = bfd_usrdata (child); 510 if (gdata->archive_bfd == NULL) 511 { 512 gdata->archive_bfd = parent; 513 gdb_bfd_ref (parent); 514 } 515 else 516 gdb_assert (gdata->archive_bfd == parent); 517 } 518 519 /* See gdb_bfd.h. */ 520 521 bfd * 522 gdb_bfd_openr_next_archived_file (bfd *archive, bfd *previous) 523 { 524 bfd *result = bfd_openr_next_archived_file (archive, previous); 525 526 if (result) 527 gdb_bfd_mark_parent (result, archive); 528 529 return result; 530 } 531 532 /* See gdb_bfd.h. */ 533 534 bfd * 535 gdb_bfd_fdopenr (const char *filename, const char *target, int fd) 536 { 537 bfd *result = bfd_fdopenr (filename, target, fd); 538 539 if (result) 540 { 541 gdb_bfd_ref (result); 542 gdb_bfd_stash_filename (result); 543 } 544 545 return result; 546 } 547 548 549 550 /* A callback for htab_traverse that prints a single BFD. */ 551 552 static int 553 print_one_bfd (void **slot, void *data) 554 { 555 bfd *abfd = *slot; 556 struct gdb_bfd_data *gdata = bfd_usrdata (abfd); 557 struct ui_out *uiout = data; 558 struct cleanup *inner; 559 560 inner = make_cleanup_ui_out_tuple_begin_end (uiout, NULL); 561 ui_out_field_int (uiout, "refcount", gdata->refc); 562 ui_out_field_string (uiout, "addr", host_address_to_string (abfd)); 563 ui_out_field_string (uiout, "filename", bfd_get_filename (abfd)); 564 ui_out_text (uiout, "\n"); 565 do_cleanups (inner); 566 567 return 1; 568 } 569 570 /* Implement the 'maint info bfd' command. */ 571 572 static void 573 maintenance_info_bfds (char *arg, int from_tty) 574 { 575 struct cleanup *cleanup; 576 struct ui_out *uiout = current_uiout; 577 578 cleanup = make_cleanup_ui_out_table_begin_end (uiout, 3, -1, "bfds"); 579 ui_out_table_header (uiout, 10, ui_left, "refcount", "Refcount"); 580 ui_out_table_header (uiout, 18, ui_left, "addr", "Address"); 581 ui_out_table_header (uiout, 40, ui_left, "filename", "Filename"); 582 583 ui_out_table_body (uiout); 584 htab_traverse (all_bfds, print_one_bfd, uiout); 585 586 do_cleanups (cleanup); 587 } 588 589 /* -Wmissing-prototypes */ 590 extern initialize_file_ftype _initialize_gdb_bfd; 591 592 void 593 _initialize_gdb_bfd (void) 594 { 595 all_bfds = htab_create_alloc (10, htab_hash_pointer, htab_eq_pointer, 596 NULL, xcalloc, xfree); 597 598 add_cmd ("bfds", class_maintenance, maintenance_info_bfds, _("\ 599 List the BFDs that are currently open."), 600 &maintenanceinfolist); 601 } 602