gdb/gdb_bfd.c

   1 /* Definitions for BFD wrappers used by GDB.
   2
   3    Copyright (C) 2011-2015 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 "ui-out.h"
  23 #include "gdbcmd.h"
  24 #include "hashtab.h"
  25 #include "filestuff.h"
  26 #include "vec.h"
  27 #ifdef HAVE_MMAP
  28 #include <sys/mman.h>
  29 #ifndef MAP_FAILED
  30 #define MAP_FAILED ((void *) -1)
  31 #endif
  32 #endif
  33
  34 typedef bfd *bfdp;
  35 DEF_VEC_P (bfdp);
  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 /* An object of this type is stored in each BFD's user data.  */
  60
  61 struct gdb_bfd_data
  62 {
  63   /* The reference count.  */
  64   int refc;
  65
  66   /* The mtime of the BFD at the point the cache entry was made.  */
  67   time_t mtime;
  68
  69   /* This is true if we have determined whether this BFD has any
  70      sections requiring relocation.  */
  71   unsigned int relocation_computed : 1;
  72
  73   /* This is true if any section needs relocation.  */
  74   unsigned int needs_relocations : 1;
  75
  76   /* This is true if we have successfully computed the file's CRC.  */
  77   unsigned int crc_computed : 1;
  78
  79   /* The file's CRC.  */
  80   unsigned long crc;
  81
  82   /* If the BFD comes from an archive, this points to the archive's
  83      BFD.  Otherwise, this is NULL.  */
  84   bfd *archive_bfd;
  85
  86   /* Table of all the bfds this bfd has included.  */
  87   VEC (bfdp) *included_bfds;
  88
  89   /* The registry.  */
  90   REGISTRY_FIELDS;
  91 };
  92
  93 #define GDB_BFD_DATA_ACCESSOR(ABFD) \
  94   ((struct gdb_bfd_data *) bfd_usrdata (ABFD))
  95
  96 DEFINE_REGISTRY (bfd, GDB_BFD_DATA_ACCESSOR)
  97
  98 /* A hash table storing all the BFDs maintained in the cache.  */
  99
 100 static htab_t gdb_bfd_cache;
 101
 102 /* The type of an object being looked up in gdb_bfd_cache.  We use
 103    htab's capability of storing one kind of object (BFD in this case)
 104    and using a different sort of object for searching.  */
 105
 106 struct gdb_bfd_cache_search
 107 {
 108   /* The filename.  */
 109   const char *filename;
 110   /* The mtime.  */
 111   time_t mtime;
 112 };
 113
 114 /* A hash function for BFDs.  */
 115
 116 static hashval_t
 117 hash_bfd (const void *b)
 118 {
 119   const bfd *abfd = b;
 120
 121   /* It is simplest to just hash the filename.  */
 122   return htab_hash_string (bfd_get_filename (abfd));
 123 }
 124
 125 /* An equality function for BFDs.  Note that this expects the caller
 126    to search using struct gdb_bfd_cache_search only, not BFDs.  */
 127
 128 static int
 129 eq_bfd (const void *a, const void *b)
 130 {
 131   const bfd *abfd = a;
 132   const struct gdb_bfd_cache_search *s = b;
 133   struct gdb_bfd_data *gdata = bfd_usrdata (abfd);
 134
 135   return (gdata->mtime == s->mtime
 136           && strcmp (bfd_get_filename (abfd), s->filename) == 0);
 137 }
 138
 139 /* See gdb_bfd.h.  */
 140
 141 struct bfd *
 142 gdb_bfd_open (const char *name, const char *target, int fd)
 143 {
 144   hashval_t hash;
 145   void **slot;
 146   bfd *abfd;
 147   struct gdb_bfd_cache_search search;
 148   struct stat st;
 149
 150   if (gdb_bfd_cache == NULL)
 151     gdb_bfd_cache = htab_create_alloc (1, hash_bfd, eq_bfd, NULL,
 152                                        xcalloc, xfree);
 153
 154   if (fd == -1)
 155     {
 156       fd = gdb_open_cloexec (name, O_RDONLY | O_BINARY, 0);
 157       if (fd == -1)
 158         {
 159           bfd_set_error (bfd_error_system_call);
 160           return NULL;
 161         }
 162     }
 163
 164   search.filename = name;
 165   if (fstat (fd, &st) < 0)
 166     {
 167       /* Weird situation here.  */
 168       search.mtime = 0;
 169     }
 170   else
 171     search.mtime = st.st_mtime;
 172
 173   /* Note that this must compute the same result as hash_bfd.  */
 174   hash = htab_hash_string (name);
 175   /* Note that we cannot use htab_find_slot_with_hash here, because
 176      opening the BFD may fail; and this would violate hashtab
 177      invariants.  */
 178   abfd = htab_find_with_hash (gdb_bfd_cache, &search, hash);
 179   if (abfd != NULL)
 180     {
 181       close (fd);
 182       gdb_bfd_ref (abfd);
 183       return abfd;
 184     }
 185
 186   abfd = bfd_fopen (name, target, FOPEN_RB, fd);
 187   if (abfd == NULL)
 188     return NULL;
 189
 190   slot = htab_find_slot_with_hash (gdb_bfd_cache, &search, hash, INSERT);
 191   gdb_assert (!*slot);
 192   *slot = abfd;
 193
 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   int ix;
 283   struct gdb_bfd_data *gdata;
 284   struct gdb_bfd_cache_search search;
 285   bfd *archive_bfd, *included_bfd;
 286
 287   if (abfd == NULL)
 288     return;
 289
 290   gdata = bfd_usrdata (abfd);
 291   gdb_assert (gdata->refc >= 1);
 292
 293   gdata->refc -= 1;
 294   if (gdata->refc > 0)
 295     return;
 296
 297   archive_bfd = gdata->archive_bfd;
 298   search.filename = bfd_get_filename (abfd);
 299
 300   if (gdb_bfd_cache && search.filename)
 301     {
 302       hashval_t hash = htab_hash_string (search.filename);
 303       void **slot;
 304
 305       search.mtime = gdata->mtime;
 306       slot = htab_find_slot_with_hash (gdb_bfd_cache, &search, hash,
 307                                        NO_INSERT);
 308
 309       if (slot && *slot)
 310         htab_clear_slot (gdb_bfd_cache, slot);
 311     }
 312
 313   for (ix = 0;
 314        VEC_iterate (bfdp, gdata->included_bfds, ix, included_bfd);
 315        ++ix)
 316     gdb_bfd_unref (included_bfd);
 317   VEC_free (bfdp, gdata->included_bfds);
 318
 319   bfd_free_data (abfd);
 320   bfd_usrdata (abfd) = NULL;  /* Paranoia.  */
 321
 322   htab_remove_elt (all_bfds, abfd);
 323
 324   gdb_bfd_close_or_warn (abfd);
 325
 326   gdb_bfd_unref (archive_bfd);
 327 }
 328
 329 /* A helper function that returns the section data descriptor
 330    associated with SECTION.  If no such descriptor exists, a new one
 331    is allocated and cleared.  */
 332
 333 static struct gdb_bfd_section_data *
 334 get_section_descriptor (asection *section)
 335 {
 336   struct gdb_bfd_section_data *result;
 337
 338   result = bfd_get_section_userdata (section->owner, section);
 339
 340   if (result == NULL)
 341     {
 342       result = bfd_zalloc (section->owner, sizeof (*result));
 343       bfd_set_section_userdata (section->owner, section, result);
 344     }
 345
 346   return result;
 347 }
 348
 349 /* See gdb_bfd.h.  */
 350
 351 const gdb_byte *
 352 gdb_bfd_map_section (asection *sectp, bfd_size_type *size)
 353 {
 354   bfd *abfd;
 355   struct gdb_bfd_section_data *descriptor;
 356   bfd_byte *data;
 357
 358   gdb_assert ((sectp->flags & SEC_RELOC) == 0);
 359   gdb_assert (size != NULL);
 360
 361   abfd = sectp->owner;
 362
 363   descriptor = get_section_descriptor (sectp);
 364
 365   /* If the data was already read for this BFD, just reuse it.  */
 366   if (descriptor->data != NULL)
 367     goto done;
 368
 369 #ifdef HAVE_MMAP
 370   if (!bfd_is_section_compressed (abfd, sectp))
 371     {
 372       /* The page size, used when mmapping.  */
 373       static int pagesize;
 374
 375       if (pagesize == 0)
 376         pagesize = getpagesize ();
 377
 378       /* Only try to mmap sections which are large enough: we don't want
 379          to waste space due to fragmentation.  */
 380
 381       if (bfd_get_section_size (sectp) > 4 * pagesize)
 382         {
 383           descriptor->size = bfd_get_section_size (sectp);
 384           descriptor->data = bfd_mmap (abfd, 0, descriptor->size, PROT_READ,
 385                                        MAP_PRIVATE, sectp->filepos,
 386                                        &descriptor->map_addr,
 387                                        &descriptor->map_len);
 388
 389           if ((caddr_t)descriptor->data != MAP_FAILED)
 390             {
 391 #if HAVE_POSIX_MADVISE
 392               posix_madvise (descriptor->map_addr, descriptor->map_len,
 393                              POSIX_MADV_WILLNEED);
 394 #endif
 395               goto done;
 396             }
 397
 398           /* On failure, clear out the section data and try again.  */
 399           memset (descriptor, 0, sizeof (*descriptor));
 400         }
 401     }
 402 #endif /* HAVE_MMAP */
 403
 404   /* Handle compressed sections, or ordinary uncompressed sections in
 405      the no-mmap case.  */
 406
 407   descriptor->size = bfd_get_section_size (sectp);
 408   descriptor->data = NULL;
 409
 410   data = NULL;
 411   if (!bfd_get_full_section_contents (abfd, sectp, &data))
 412     error (_("Can't read data for section '%s' in file '%s'"),
 413            bfd_get_section_name (abfd, sectp),
 414            bfd_get_filename (abfd));
 415   descriptor->data = data;
 416
 417  done:
 418   gdb_assert (descriptor->data != NULL);
 419   *size = descriptor->size;
 420   return descriptor->data;
 421 }
 422
 423 /* Return 32-bit CRC for ABFD.  If successful store it to *FILE_CRC_RETURN and
 424    return 1.  Otherwise print a warning and return 0.  ABFD seek position is
 425    not preserved.  */
 426
 427 static int
 428 get_file_crc (bfd *abfd, unsigned long *file_crc_return)
 429 {
 430   unsigned long file_crc = 0;
 431
 432   if (bfd_seek (abfd, 0, SEEK_SET) != 0)
 433     {
 434       warning (_("Problem reading \"%s\" for CRC: %s"),
 435                bfd_get_filename (abfd), bfd_errmsg (bfd_get_error ()));
 436       return 0;
 437     }
 438
 439   for (;;)
 440     {
 441       gdb_byte buffer[8 * 1024];
 442       bfd_size_type count;
 443
 444       count = bfd_bread (buffer, sizeof (buffer), abfd);
 445       if (count == (bfd_size_type) -1)
 446         {
 447           warning (_("Problem reading \"%s\" for CRC: %s"),
 448                    bfd_get_filename (abfd), bfd_errmsg (bfd_get_error ()));
 449           return 0;
 450         }
 451       if (count == 0)
 452         break;
 453       file_crc = bfd_calc_gnu_debuglink_crc32 (file_crc, buffer, count);
 454     }
 455
 456   *file_crc_return = file_crc;
 457   return 1;
 458 }
 459
 460 /* See gdb_bfd.h.  */
 461
 462 int
 463 gdb_bfd_crc (struct bfd *abfd, unsigned long *crc_out)
 464 {
 465   struct gdb_bfd_data *gdata = bfd_usrdata (abfd);
 466
 467   if (!gdata->crc_computed)
 468     gdata->crc_computed = get_file_crc (abfd, &gdata->crc);
 469
 470   if (gdata->crc_computed)
 471     *crc_out = gdata->crc;
 472   return gdata->crc_computed;
 473 }
 474
 475 \f
 476
 477 /* See gdb_bfd.h.  */
 478
 479 bfd *
 480 gdb_bfd_fopen (const char *filename, const char *target, const char *mode,
 481                int fd)
 482 {
 483   bfd *result = bfd_fopen (filename, target, mode, fd);
 484
 485   if (result)
 486     gdb_bfd_ref (result);
 487
 488   return result;
 489 }
 490
 491 /* See gdb_bfd.h.  */
 492
 493 bfd *
 494 gdb_bfd_openr (const char *filename, const char *target)
 495 {
 496   bfd *result = bfd_openr (filename, target);
 497
 498   if (result)
 499     gdb_bfd_ref (result);
 500
 501   return result;
 502 }
 503
 504 /* See gdb_bfd.h.  */
 505
 506 bfd *
 507 gdb_bfd_openw (const char *filename, const char *target)
 508 {
 509   bfd *result = bfd_openw (filename, target);
 510
 511   if (result)
 512     gdb_bfd_ref (result);
 513
 514   return result;
 515 }
 516
 517 /* See gdb_bfd.h.  */
 518
 519 bfd *
 520 gdb_bfd_openr_iovec (const char *filename, const char *target,
 521                      void *(*open_func) (struct bfd *nbfd,
 522                                          void *open_closure),
 523                      void *open_closure,
 524                      file_ptr (*pread_func) (struct bfd *nbfd,
 525                                              void *stream,
 526                                              void *buf,
 527                                              file_ptr nbytes,
 528                                              file_ptr offset),
 529                      int (*close_func) (struct bfd *nbfd,
 530                                         void *stream),
 531                      int (*stat_func) (struct bfd *abfd,
 532                                        void *stream,
 533                                        struct stat *sb))
 534 {
 535   bfd *result = bfd_openr_iovec (filename, target,
 536                                  open_func, open_closure,
 537                                  pread_func, close_func, stat_func);
 538
 539   if (result)
 540     gdb_bfd_ref (result);
 541
 542   return result;
 543 }
 544
 545 /* See gdb_bfd.h.  */
 546
 547 void
 548 gdb_bfd_mark_parent (bfd *child, bfd *parent)
 549 {
 550   struct gdb_bfd_data *gdata;
 551
 552   gdb_bfd_ref (child);
 553   /* No need to stash the filename here, because we also keep a
 554      reference on the parent archive.  */
 555
 556   gdata = bfd_usrdata (child);
 557   if (gdata->archive_bfd == NULL)
 558     {
 559       gdata->archive_bfd = parent;
 560       gdb_bfd_ref (parent);
 561     }
 562   else
 563     gdb_assert (gdata->archive_bfd == parent);
 564 }
 565
 566 /* See gdb_bfd.h.  */
 567
 568 bfd *
 569 gdb_bfd_openr_next_archived_file (bfd *archive, bfd *previous)
 570 {
 571   bfd *result = bfd_openr_next_archived_file (archive, previous);
 572
 573   if (result)
 574     gdb_bfd_mark_parent (result, archive);
 575
 576   return result;
 577 }
 578
 579 /* See gdb_bfd.h.  */
 580
 581 void
 582 gdb_bfd_record_inclusion (bfd *includer, bfd *includee)
 583 {
 584   struct gdb_bfd_data *gdata;
 585
 586   gdb_bfd_ref (includee);
 587   gdata = bfd_usrdata (includer);
 588   VEC_safe_push (bfdp, gdata->included_bfds, includee);
 589 }
 590
 591 /* See gdb_bfd.h.  */
 592
 593 bfd *
 594 gdb_bfd_fdopenr (const char *filename, const char *target, int fd)
 595 {
 596   bfd *result = bfd_fdopenr (filename, target, fd);
 597
 598   if (result)
 599     gdb_bfd_ref (result);
 600
 601   return result;
 602 }
 603
 604 \f
 605
 606 gdb_static_assert (ARRAY_SIZE (_bfd_std_section) == 4);
 607
 608 /* See gdb_bfd.h.  */
 609
 610 int
 611 gdb_bfd_section_index (bfd *abfd, asection *section)
 612 {
 613   if (section == NULL)
 614     return -1;
 615   else if (section == bfd_com_section_ptr)
 616     return bfd_count_sections (abfd);
 617   else if (section == bfd_und_section_ptr)
 618     return bfd_count_sections (abfd) + 1;
 619   else if (section == bfd_abs_section_ptr)
 620     return bfd_count_sections (abfd) + 2;
 621   else if (section == bfd_ind_section_ptr)
 622     return bfd_count_sections (abfd) + 3;
 623   return section->index;
 624 }
 625
 626 /* See gdb_bfd.h.  */
 627
 628 int
 629 gdb_bfd_count_sections (bfd *abfd)
 630 {
 631   return bfd_count_sections (abfd) + 4;
 632 }
 633
 634 /* See gdb_bfd.h.  */
 635
 636 int
 637 gdb_bfd_requires_relocations (bfd *abfd)
 638 {
 639   struct gdb_bfd_data *gdata = bfd_usrdata (abfd);
 640
 641   if (gdata->relocation_computed == 0)
 642     {
 643       asection *sect;
 644
 645       for (sect = abfd->sections; sect != NULL; sect = sect->next)
 646         if ((sect->flags & SEC_RELOC) != 0)
 647           {
 648             gdata->needs_relocations = 1;
 649             break;
 650           }
 651
 652       gdata->relocation_computed = 1;
 653     }
 654
 655   return gdata->needs_relocations;
 656 }
 657
 658 \f
 659
 660 /* A callback for htab_traverse that prints a single BFD.  */
 661
 662 static int
 663 print_one_bfd (void **slot, void *data)
 664 {
 665   bfd *abfd = *slot;
 666   struct gdb_bfd_data *gdata = bfd_usrdata (abfd);
 667   struct ui_out *uiout = data;
 668   struct cleanup *inner;
 669
 670   inner = make_cleanup_ui_out_tuple_begin_end (uiout, NULL);
 671   ui_out_field_int (uiout, "refcount", gdata->refc);
 672   ui_out_field_string (uiout, "addr", host_address_to_string (abfd));
 673   ui_out_field_string (uiout, "filename", bfd_get_filename (abfd));
 674   ui_out_text (uiout, "\n");
 675   do_cleanups (inner);
 676
 677   return 1;
 678 }
 679
 680 /* Implement the 'maint info bfd' command.  */
 681
 682 static void
 683 maintenance_info_bfds (char *arg, int from_tty)
 684 {
 685   struct cleanup *cleanup;
 686   struct ui_out *uiout = current_uiout;
 687
 688   cleanup = make_cleanup_ui_out_table_begin_end (uiout, 3, -1, "bfds");
 689   ui_out_table_header (uiout, 10, ui_left, "refcount", "Refcount");
 690   ui_out_table_header (uiout, 18, ui_left, "addr", "Address");
 691   ui_out_table_header (uiout, 40, ui_left, "filename", "Filename");
 692
 693   ui_out_table_body (uiout);
 694   htab_traverse (all_bfds, print_one_bfd, uiout);
 695
 696   do_cleanups (cleanup);
 697 }
 698
 699 /* -Wmissing-prototypes */
 700 extern initialize_file_ftype _initialize_gdb_bfd;
 701
 702 void
 703 _initialize_gdb_bfd (void)
 704 {
 705   all_bfds = htab_create_alloc (10, htab_hash_pointer, htab_eq_pointer,
 706                                 NULL, xcalloc, xfree);
 707
 708   add_cmd ("bfds", class_maintenance, maintenance_info_bfds, _("\
 709 List the BFDs that are currently open."),
 710            &maintenanceinfolist);
 711 }