gdb/gdb_bfd.c

   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 <string.h>
  24 #include "ui-out.h"
  25 #include "gdbcmd.h"
  26 #include "hashtab.h"
  27 #include "filestuff.h"
  28 #ifdef HAVE_ZLIB_H
  29 #include <zlib.h>
  30 #endif
  31 #ifdef HAVE_MMAP
  32 #include <sys/mman.h>
  33 #ifndef MAP_FAILED
  34 #define MAP_FAILED ((void *) -1)
  35 #endif
  36 #endif
  37
  38 /* An object of this type is stored in the section's user data when
  39    mapping a section.  */
  40
  41 struct gdb_bfd_section_data
  42 {
  43   /* Size of the data.  */
  44   bfd_size_type size;
  45   /* If the data was mmapped, this is the length of the map.  */
  46   bfd_size_type map_len;
  47   /* The data.  If NULL, the section data has not been read.  */
  48   void *data;
  49   /* If the data was mmapped, this is the map address.  */
  50   void *map_addr;
  51 };
  52
  53 /* A hash table holding every BFD that gdb knows about.  This is not
  54    to be confused with 'gdb_bfd_cache', which is used for sharing
  55    BFDs; in contrast, this hash is used just to implement
  56    "maint info bfd".  */
  57
  58 static htab_t all_bfds;
  59
  60 /* See gdb_bfd.h.  */
  61
  62 void
  63 gdb_bfd_stash_filename (struct bfd *abfd)
  64 {
  65   char *name = bfd_get_filename (abfd);
  66   char *data;
  67
  68   data = bfd_alloc (abfd, strlen (name) + 1);
  69   strcpy (data, name);
  70
  71   /* Unwarranted chumminess with BFD.  */
  72   abfd->filename = data;
  73 }
  74
  75 /* An object of this type is stored in each BFD's user data.  */
  76
  77 struct gdb_bfd_data
  78 {
  79   /* The reference count.  */
  80   int refc;
  81
  82   /* The mtime of the BFD at the point the cache entry was made.  */
  83   time_t mtime;
  84
  85   /* This is true if we have determined whether this BFD has any
  86      sections requiring relocation.  */
  87   unsigned int relocation_computed : 1;
  88
  89   /* This is true if any section needs relocation.  */
  90   unsigned int needs_relocations : 1;
  91
  92   /* This is true if we have successfully computed the file's CRC.  */
  93   unsigned int crc_computed : 1;
  94
  95   /* The file's CRC.  */
  96   unsigned long crc;
  97
  98   /* If the BFD comes from an archive, this points to the archive's
  99      BFD.  Otherwise, this is NULL.  */
 100   bfd *archive_bfd;
 101
 102   /* The registry.  */
 103   REGISTRY_FIELDS;
 104 };
 105
 106 #define GDB_BFD_DATA_ACCESSOR(ABFD) \
 107   ((struct gdb_bfd_data *) bfd_usrdata (ABFD))
 108
 109 DEFINE_REGISTRY (bfd, GDB_BFD_DATA_ACCESSOR)
 110
 111 /* A hash table storing all the BFDs maintained in the cache.  */
 112
 113 static htab_t gdb_bfd_cache;
 114
 115 /* The type of an object being looked up in gdb_bfd_cache.  We use
 116    htab's capability of storing one kind of object (BFD in this case)
 117    and using a different sort of object for searching.  */
 118
 119 struct gdb_bfd_cache_search
 120 {
 121   /* The filename.  */
 122   const char *filename;
 123   /* The mtime.  */
 124   time_t mtime;
 125 };
 126
 127 /* A hash function for BFDs.  */
 128
 129 static hashval_t
 130 hash_bfd (const void *b)
 131 {
 132   const bfd *abfd = b;
 133
 134   /* It is simplest to just hash the filename.  */
 135   return htab_hash_string (bfd_get_filename (abfd));
 136 }
 137
 138 /* An equality function for BFDs.  Note that this expects the caller
 139    to search using struct gdb_bfd_cache_search only, not BFDs.  */
 140
 141 static int
 142 eq_bfd (const void *a, const void *b)
 143 {
 144   const bfd *abfd = a;
 145   const struct gdb_bfd_cache_search *s = b;
 146   struct gdb_bfd_data *gdata = bfd_usrdata (abfd);
 147
 148   return (gdata->mtime == s->mtime
 149           && strcmp (bfd_get_filename (abfd), s->filename) == 0);
 150 }
 151
 152 /* See gdb_bfd.h.  */
 153
 154 struct bfd *
 155 gdb_bfd_open (const char *name, const char *target, int fd)
 156 {
 157   hashval_t hash;
 158   void **slot;
 159   bfd *abfd;
 160   struct gdb_bfd_cache_search search;
 161   struct stat st;
 162
 163   if (gdb_bfd_cache == NULL)
 164     gdb_bfd_cache = htab_create_alloc (1, hash_bfd, eq_bfd, NULL,
 165                                        xcalloc, xfree);
 166
 167   if (fd == -1)
 168     {
 169       fd = gdb_open_cloexec (name, O_RDONLY | O_BINARY, 0);
 170       if (fd == -1)
 171         {
 172           bfd_set_error (bfd_error_system_call);
 173           return NULL;
 174         }
 175     }
 176
 177   search.filename = name;
 178   if (fstat (fd, &st) < 0)
 179     {
 180       /* Weird situation here.  */
 181       search.mtime = 0;
 182     }
 183   else
 184     search.mtime = st.st_mtime;
 185
 186   /* Note that this must compute the same result as hash_bfd.  */
 187   hash = htab_hash_string (name);
 188   /* Note that we cannot use htab_find_slot_with_hash here, because
 189      opening the BFD may fail; and this would violate hashtab
 190      invariants.  */
 191   abfd = htab_find_with_hash (gdb_bfd_cache, &search, hash);
 192   if (abfd != NULL)
 193     {
 194       close (fd);
 195       gdb_bfd_ref (abfd);
 196       return abfd;
 197     }
 198
 199   abfd = bfd_fopen (name, target, FOPEN_RB, fd);
 200   if (abfd == NULL)
 201     return NULL;
 202
 203   slot = htab_find_slot_with_hash (gdb_bfd_cache, &search, hash, INSERT);
 204   gdb_assert (!*slot);
 205   *slot = abfd;
 206
 207   gdb_bfd_stash_filename (abfd);
 208   gdb_bfd_ref (abfd);
 209   return abfd;
 210 }
 211
 212 /* A helper function that releases any section data attached to the
 213    BFD.  */
 214
 215 static void
 216 free_one_bfd_section (bfd *abfd, asection *sectp, void *ignore)
 217 {
 218   struct gdb_bfd_section_data *sect = bfd_get_section_userdata (abfd, sectp);
 219
 220   if (sect != NULL && sect->data != NULL)
 221     {
 222 #ifdef HAVE_MMAP
 223       if (sect->map_addr != NULL)
 224         {
 225           int res;
 226
 227           res = munmap (sect->map_addr, sect->map_len);
 228           gdb_assert (res == 0);
 229         }
 230       else
 231 #endif
 232         xfree (sect->data);
 233     }
 234 }
 235
 236 /* Close ABFD, and warn if that fails.  */
 237
 238 static int
 239 gdb_bfd_close_or_warn (struct bfd *abfd)
 240 {
 241   int ret;
 242   char *name = bfd_get_filename (abfd);
 243
 244   bfd_map_over_sections (abfd, free_one_bfd_section, NULL);
 245
 246   ret = bfd_close (abfd);
 247
 248   if (!ret)
 249     warning (_("cannot close \"%s\": %s"),
 250              name, bfd_errmsg (bfd_get_error ()));
 251
 252   return ret;
 253 }
 254
 255 /* See gdb_bfd.h.  */
 256
 257 void
 258 gdb_bfd_ref (struct bfd *abfd)
 259 {
 260   struct gdb_bfd_data *gdata;
 261   void **slot;
 262
 263   if (abfd == NULL)
 264     return;
 265
 266   gdata = bfd_usrdata (abfd);
 267
 268   if (gdata != NULL)
 269     {
 270       gdata->refc += 1;
 271       return;
 272     }
 273
 274   /* Ask BFD to decompress sections in bfd_get_full_section_contents.  */
 275   abfd->flags |= BFD_DECOMPRESS;
 276
 277   gdata = bfd_zalloc (abfd, sizeof (struct gdb_bfd_data));
 278   gdata->refc = 1;
 279   gdata->mtime = bfd_get_mtime (abfd);
 280   gdata->archive_bfd = NULL;
 281   bfd_usrdata (abfd) = gdata;
 282
 283   bfd_alloc_data (abfd);
 284
 285   /* This is the first we've seen it, so add it to the hash table.  */
 286   slot = htab_find_slot (all_bfds, abfd, INSERT);
 287   gdb_assert (slot && !*slot);
 288   *slot = abfd;
 289 }
 290
 291 /* See gdb_bfd.h.  */
 292
 293 void
 294 gdb_bfd_unref (struct bfd *abfd)
 295 {
 296   struct gdb_bfd_data *gdata;
 297   struct gdb_bfd_cache_search search;
 298   bfd *archive_bfd;
 299
 300   if (abfd == NULL)
 301     return;
 302
 303   gdata = bfd_usrdata (abfd);
 304   gdb_assert (gdata->refc >= 1);
 305
 306   gdata->refc -= 1;
 307   if (gdata->refc > 0)
 308     return;
 309
 310   archive_bfd = gdata->archive_bfd;
 311   search.filename = bfd_get_filename (abfd);
 312
 313   if (gdb_bfd_cache && search.filename)
 314     {
 315       hashval_t hash = htab_hash_string (search.filename);
 316       void **slot;
 317
 318       search.mtime = gdata->mtime;
 319       slot = htab_find_slot_with_hash (gdb_bfd_cache, &search, hash,
 320                                        NO_INSERT);
 321
 322       if (slot && *slot)
 323         htab_clear_slot (gdb_bfd_cache, slot);
 324     }
 325
 326   bfd_free_data (abfd);
 327   bfd_usrdata (abfd) = NULL;  /* Paranoia.  */
 328
 329   htab_remove_elt (all_bfds, abfd);
 330
 331   gdb_bfd_close_or_warn (abfd);
 332
 333   gdb_bfd_unref (archive_bfd);
 334 }
 335
 336 /* A helper function that returns the section data descriptor
 337    associated with SECTION.  If no such descriptor exists, a new one
 338    is allocated and cleared.  */
 339
 340 static struct gdb_bfd_section_data *
 341 get_section_descriptor (asection *section)
 342 {
 343   struct gdb_bfd_section_data *result;
 344
 345   result = bfd_get_section_userdata (section->owner, section);
 346
 347   if (result == NULL)
 348     {
 349       result = bfd_zalloc (section->owner, sizeof (*result));
 350       bfd_set_section_userdata (section->owner, section, result);
 351     }
 352
 353   return result;
 354 }
 355
 356 /* See gdb_bfd.h.  */
 357
 358 const gdb_byte *
 359 gdb_bfd_map_section (asection *sectp, bfd_size_type *size)
 360 {
 361   bfd *abfd;
 362   struct gdb_bfd_section_data *descriptor;
 363   bfd_byte *data;
 364
 365   gdb_assert ((sectp->flags & SEC_RELOC) == 0);
 366   gdb_assert (size != NULL);
 367
 368   abfd = sectp->owner;
 369
 370   descriptor = get_section_descriptor (sectp);
 371
 372   /* If the data was already read for this BFD, just reuse it.  */
 373   if (descriptor->data != NULL)
 374     goto done;
 375
 376 #ifdef HAVE_MMAP
 377   if (!bfd_is_section_compressed (abfd, sectp))
 378     {
 379       /* The page size, used when mmapping.  */
 380       static int pagesize;
 381
 382       if (pagesize == 0)
 383         pagesize = getpagesize ();
 384
 385       /* Only try to mmap sections which are large enough: we don't want
 386          to waste space due to fragmentation.  */
 387
 388       if (bfd_get_section_size (sectp) > 4 * pagesize)
 389         {
 390           descriptor->size = bfd_get_section_size (sectp);
 391           descriptor->data = bfd_mmap (abfd, 0, descriptor->size, PROT_READ,
 392                                        MAP_PRIVATE, sectp->filepos,
 393                                        &descriptor->map_addr,
 394                                        &descriptor->map_len);
 395
 396           if ((caddr_t)descriptor->data != MAP_FAILED)
 397             {
 398 #if HAVE_POSIX_MADVISE
 399               posix_madvise (descriptor->map_addr, descriptor->map_len,
 400                              POSIX_MADV_WILLNEED);
 401 #endif
 402               goto done;
 403             }
 404
 405           /* On failure, clear out the section data and try again.  */
 406           memset (descriptor, 0, sizeof (*descriptor));
 407         }
 408     }
 409 #endif /* HAVE_MMAP */
 410
 411   /* Handle compressed sections, or ordinary uncompressed sections in
 412      the no-mmap case.  */
 413
 414   descriptor->size = bfd_get_section_size (sectp);
 415   descriptor->data = NULL;
 416
 417   data = NULL;
 418   if (!bfd_get_full_section_contents (abfd, sectp, &data))
 419     error (_("Can't read data for section '%s' in file '%s'"),
 420            bfd_get_section_name (abfd, sectp),
 421            bfd_get_filename (abfd));
 422   descriptor->data = data;
 423
 424  done:
 425   gdb_assert (descriptor->data != NULL);
 426   *size = descriptor->size;
 427   return descriptor->data;
 428 }
 429
 430 /* Return 32-bit CRC for ABFD.  If successful store it to *FILE_CRC_RETURN and
 431    return 1.  Otherwise print a warning and return 0.  ABFD seek position is
 432    not preserved.  */
 433
 434 static int
 435 get_file_crc (bfd *abfd, unsigned long *file_crc_return)
 436 {
 437   unsigned long file_crc = 0;
 438
 439   if (bfd_seek (abfd, 0, SEEK_SET) != 0)
 440     {
 441       warning (_("Problem reading \"%s\" for CRC: %s"),
 442                bfd_get_filename (abfd), bfd_errmsg (bfd_get_error ()));
 443       return 0;
 444     }
 445
 446   for (;;)
 447     {
 448       gdb_byte buffer[8 * 1024];
 449       bfd_size_type count;
 450
 451       count = bfd_bread (buffer, sizeof (buffer), abfd);
 452       if (count == (bfd_size_type) -1)
 453         {
 454           warning (_("Problem reading \"%s\" for CRC: %s"),
 455                    bfd_get_filename (abfd), bfd_errmsg (bfd_get_error ()));
 456           return 0;
 457         }
 458       if (count == 0)
 459         break;
 460       file_crc = bfd_calc_gnu_debuglink_crc32 (file_crc, buffer, count);
 461     }
 462
 463   *file_crc_return = file_crc;
 464   return 1;
 465 }
 466
 467 /* See gdb_bfd.h.  */
 468
 469 int
 470 gdb_bfd_crc (struct bfd *abfd, unsigned long *crc_out)
 471 {
 472   struct gdb_bfd_data *gdata = bfd_usrdata (abfd);
 473
 474   if (!gdata->crc_computed)
 475     gdata->crc_computed = get_file_crc (abfd, &gdata->crc);
 476
 477   if (gdata->crc_computed)
 478     *crc_out = gdata->crc;
 479   return gdata->crc_computed;
 480 }
 481
 482 \f
 483
 484 /* See gdb_bfd.h.  */
 485
 486 bfd *
 487 gdb_bfd_fopen (const char *filename, const char *target, const char *mode,
 488                int fd)
 489 {
 490   bfd *result = bfd_fopen (filename, target, mode, fd);
 491
 492   if (result)
 493     {
 494       gdb_bfd_stash_filename (result);
 495       gdb_bfd_ref (result);
 496     }
 497
 498   return result;
 499 }
 500
 501 /* See gdb_bfd.h.  */
 502
 503 bfd *
 504 gdb_bfd_openr (const char *filename, const char *target)
 505 {
 506   bfd *result = bfd_openr (filename, target);
 507
 508   if (result)
 509     {
 510       gdb_bfd_stash_filename (result);
 511       gdb_bfd_ref (result);
 512     }
 513
 514   return result;
 515 }
 516
 517 /* See gdb_bfd.h.  */
 518
 519 bfd *
 520 gdb_bfd_openw (const char *filename, const char *target)
 521 {
 522   bfd *result = bfd_openw (filename, target);
 523
 524   if (result)
 525     {
 526       gdb_bfd_stash_filename (result);
 527       gdb_bfd_ref (result);
 528     }
 529
 530   return result;
 531 }
 532
 533 /* See gdb_bfd.h.  */
 534
 535 bfd *
 536 gdb_bfd_openr_iovec (const char *filename, const char *target,
 537                      void *(*open_func) (struct bfd *nbfd,
 538                                          void *open_closure),
 539                      void *open_closure,
 540                      file_ptr (*pread_func) (struct bfd *nbfd,
 541                                              void *stream,
 542                                              void *buf,
 543                                              file_ptr nbytes,
 544                                              file_ptr offset),
 545                      int (*close_func) (struct bfd *nbfd,
 546                                         void *stream),
 547                      int (*stat_func) (struct bfd *abfd,
 548                                        void *stream,
 549                                        struct stat *sb))
 550 {
 551   bfd *result = bfd_openr_iovec (filename, target,
 552                                  open_func, open_closure,
 553                                  pread_func, close_func, stat_func);
 554
 555   if (result)
 556     {
 557       gdb_bfd_ref (result);
 558       gdb_bfd_stash_filename (result);
 559     }
 560
 561   return result;
 562 }
 563
 564 /* See gdb_bfd.h.  */
 565
 566 void
 567 gdb_bfd_mark_parent (bfd *child, bfd *parent)
 568 {
 569   struct gdb_bfd_data *gdata;
 570
 571   gdb_bfd_ref (child);
 572   /* No need to stash the filename here, because we also keep a
 573      reference on the parent archive.  */
 574
 575   gdata = bfd_usrdata (child);
 576   if (gdata->archive_bfd == NULL)
 577     {
 578       gdata->archive_bfd = parent;
 579       gdb_bfd_ref (parent);
 580     }
 581   else
 582     gdb_assert (gdata->archive_bfd == parent);
 583 }
 584
 585 /* See gdb_bfd.h.  */
 586
 587 bfd *
 588 gdb_bfd_openr_next_archived_file (bfd *archive, bfd *previous)
 589 {
 590   bfd *result = bfd_openr_next_archived_file (archive, previous);
 591
 592   if (result)
 593     gdb_bfd_mark_parent (result, archive);
 594
 595   return result;
 596 }
 597
 598 /* See gdb_bfd.h.  */
 599
 600 bfd *
 601 gdb_bfd_fdopenr (const char *filename, const char *target, int fd)
 602 {
 603   bfd *result = bfd_fdopenr (filename, target, fd);
 604
 605   if (result)
 606     {
 607       gdb_bfd_ref (result);
 608       gdb_bfd_stash_filename (result);
 609     }
 610
 611   return result;
 612 }
 613
 614 \f
 615
 616 gdb_static_assert (ARRAY_SIZE (_bfd_std_section) == 4);
 617
 618 /* See gdb_bfd.h.  */
 619
 620 int
 621 gdb_bfd_section_index (bfd *abfd, asection *section)
 622 {
 623   if (section == NULL)
 624     return -1;
 625   else if (section == bfd_com_section_ptr)
 626     return bfd_count_sections (abfd) + 1;
 627   else if (section == bfd_und_section_ptr)
 628     return bfd_count_sections (abfd) + 2;
 629   else if (section == bfd_abs_section_ptr)
 630     return bfd_count_sections (abfd) + 3;
 631   else if (section == bfd_ind_section_ptr)
 632     return bfd_count_sections (abfd) + 4;
 633   return section->index;
 634 }
 635
 636 /* See gdb_bfd.h.  */
 637
 638 int
 639 gdb_bfd_count_sections (bfd *abfd)
 640 {
 641   return bfd_count_sections (abfd) + 4;
 642 }
 643
 644 /* See gdb_bfd.h.  */
 645
 646 int
 647 gdb_bfd_requires_relocations (bfd *abfd)
 648 {
 649   struct gdb_bfd_data *gdata = bfd_usrdata (abfd);
 650
 651   if (gdata->relocation_computed == 0)
 652     {
 653       asection *sect;
 654
 655       for (sect = abfd->sections; sect != NULL; sect = sect->next)
 656         if ((sect->flags & SEC_RELOC) != 0)
 657           {
 658             gdata->needs_relocations = 1;
 659             break;
 660           }
 661
 662       gdata->relocation_computed = 1;
 663     }
 664
 665   return gdata->needs_relocations;
 666 }
 667
 668 \f
 669
 670 /* A callback for htab_traverse that prints a single BFD.  */
 671
 672 static int
 673 print_one_bfd (void **slot, void *data)
 674 {
 675   bfd *abfd = *slot;
 676   struct gdb_bfd_data *gdata = bfd_usrdata (abfd);
 677   struct ui_out *uiout = data;
 678   struct cleanup *inner;
 679
 680   inner = make_cleanup_ui_out_tuple_begin_end (uiout, NULL);
 681   ui_out_field_int (uiout, "refcount", gdata->refc);
 682   ui_out_field_string (uiout, "addr", host_address_to_string (abfd));
 683   ui_out_field_string (uiout, "filename", bfd_get_filename (abfd));
 684   ui_out_text (uiout, "\n");
 685   do_cleanups (inner);
 686
 687   return 1;
 688 }
 689
 690 /* Implement the 'maint info bfd' command.  */
 691
 692 static void
 693 maintenance_info_bfds (char *arg, int from_tty)
 694 {
 695   struct cleanup *cleanup;
 696   struct ui_out *uiout = current_uiout;
 697
 698   cleanup = make_cleanup_ui_out_table_begin_end (uiout, 3, -1, "bfds");
 699   ui_out_table_header (uiout, 10, ui_left, "refcount", "Refcount");
 700   ui_out_table_header (uiout, 18, ui_left, "addr", "Address");
 701   ui_out_table_header (uiout, 40, ui_left, "filename", "Filename");
 702
 703   ui_out_table_body (uiout);
 704   htab_traverse (all_bfds, print_one_bfd, uiout);
 705
 706   do_cleanups (cleanup);
 707 }
 708
 709 /* -Wmissing-prototypes */
 710 extern initialize_file_ftype _initialize_gdb_bfd;
 711
 712 void
 713 _initialize_gdb_bfd (void)
 714 {
 715   all_bfds = htab_create_alloc (10, htab_hash_pointer, htab_eq_pointer,
 716                                 NULL, xcalloc, xfree);
 717
 718   add_cmd ("bfds", class_maintenance, maintenance_info_bfds, _("\
 719 List the BFDs that are currently open."),
 720            &maintenanceinfolist);
 721 }