gdb/gdb_bfd.c

   1 /* Definitions for BFD wrappers used by GDB.
   2
   3    Copyright (C) 2011-2014 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 <string.h>
  23 #include "ui-out.h"
  24 #include "gdbcmd.h"
  25 #include "hashtab.h"
  26 #include "filestuff.h"
  27 #include "vec.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 typedef bfd *bfdp;
  39 DEF_VEC_P (bfdp);
  40
  41 /* An object of this type is stored in the section's user data when
  42    mapping a section.  */
  43
  44 struct gdb_bfd_section_data
  45 {
  46   /* Size of the data.  */
  47   bfd_size_type size;
  48   /* If the data was mmapped, this is the length of the map.  */
  49   bfd_size_type map_len;
  50   /* The data.  If NULL, the section data has not been read.  */
  51   void *data;
  52   /* If the data was mmapped, this is the map address.  */
  53   void *map_addr;
  54 };
  55
  56 /* A hash table holding every BFD that gdb knows about.  This is not
  57    to be confused with 'gdb_bfd_cache', which is used for sharing
  58    BFDs; in contrast, this hash is used just to implement
  59    "maint info bfd".  */
  60
  61 static htab_t all_bfds;
  62
  63 /* An object of this type is stored in each BFD's user data.  */
  64
  65 struct gdb_bfd_data
  66 {
  67   /* The reference count.  */
  68   int refc;
  69
  70   /* The mtime of the BFD at the point the cache entry was made.  */
  71   time_t mtime;
  72
  73   /* This is true if we have determined whether this BFD has any
  74      sections requiring relocation.  */
  75   unsigned int relocation_computed : 1;
  76
  77   /* This is true if any section needs relocation.  */
  78   unsigned int needs_relocations : 1;
  79
  80   /* This is true if we have successfully computed the file's CRC.  */
  81   unsigned int crc_computed : 1;
  82
  83   /* The file's CRC.  */
  84   unsigned long crc;
  85
  86   /* If the BFD comes from an archive, this points to the archive's
  87      BFD.  Otherwise, this is NULL.  */
  88   bfd *archive_bfd;
  89
  90   /* Table of all the bfds this bfd has included.  */
  91   VEC (bfdp) *included_bfds;
  92
  93   /* The registry.  */
  94   REGISTRY_FIELDS;
  95 };
  96
  97 #define GDB_BFD_DATA_ACCESSOR(ABFD) \
  98   ((struct gdb_bfd_data *) bfd_usrdata (ABFD))
  99
 100 DEFINE_REGISTRY (bfd, GDB_BFD_DATA_ACCESSOR)
 101
 102 /* A hash table storing all the BFDs maintained in the cache.  */
 103
 104 static htab_t gdb_bfd_cache;
 105
 106 /* The type of an object being looked up in gdb_bfd_cache.  We use
 107    htab's capability of storing one kind of object (BFD in this case)
 108    and using a different sort of object for searching.  */
 109
 110 struct gdb_bfd_cache_search
 111 {
 112   /* The filename.  */
 113   const char *filename;
 114   /* The mtime.  */
 115   time_t mtime;
 116 };
 117
 118 /* A hash function for BFDs.  */
 119
 120 static hashval_t
 121 hash_bfd (const void *b)
 122 {
 123   const bfd *abfd = b;
 124
 125   /* It is simplest to just hash the filename.  */
 126   return htab_hash_string (bfd_get_filename (abfd));
 127 }
 128
 129 /* An equality function for BFDs.  Note that this expects the caller
 130    to search using struct gdb_bfd_cache_search only, not BFDs.  */
 131
 132 static int
 133 eq_bfd (const void *a, const void *b)
 134 {
 135   const bfd *abfd = a;
 136   const struct gdb_bfd_cache_search *s = b;
 137   struct gdb_bfd_data *gdata = bfd_usrdata (abfd);
 138
 139   return (gdata->mtime == s->mtime
 140           && strcmp (bfd_get_filename (abfd), s->filename) == 0);
 141 }
 142
 143 /* See gdb_bfd.h.  */
 144
 145 struct bfd *
 146 gdb_bfd_open (const char *name, const char *target, int fd)
 147 {
 148   hashval_t hash;
 149   void **slot;
 150   bfd *abfd;
 151   struct gdb_bfd_cache_search search;
 152   struct stat st;
 153
 154   if (gdb_bfd_cache == NULL)
 155     gdb_bfd_cache = htab_create_alloc (1, hash_bfd, eq_bfd, NULL,
 156                                        xcalloc, xfree);
 157
 158   if (fd == -1)
 159     {
 160       fd = gdb_open_cloexec (name, O_RDONLY | O_BINARY, 0);
 161       if (fd == -1)
 162         {
 163           bfd_set_error (bfd_error_system_call);
 164           return NULL;
 165         }
 166     }
 167
 168   search.filename = name;
 169   if (fstat (fd, &st) < 0)
 170     {
 171       /* Weird situation here.  */
 172       search.mtime = 0;
 173     }
 174   else
 175     search.mtime = st.st_mtime;
 176
 177   /* Note that this must compute the same result as hash_bfd.  */
 178   hash = htab_hash_string (name);
 179   /* Note that we cannot use htab_find_slot_with_hash here, because
 180      opening the BFD may fail; and this would violate hashtab
 181      invariants.  */
 182   abfd = htab_find_with_hash (gdb_bfd_cache, &search, hash);
 183   if (abfd != NULL)
 184     {
 185       close (fd);
 186       gdb_bfd_ref (abfd);
 187       return abfd;
 188     }
 189
 190   abfd = bfd_fopen (name, target, FOPEN_RB, fd);
 191   if (abfd == NULL)
 192     return NULL;
 193
 194   slot = htab_find_slot_with_hash (gdb_bfd_cache, &search, hash, INSERT);
 195   gdb_assert (!*slot);
 196   *slot = abfd;
 197
 198   gdb_bfd_ref (abfd);
 199   return abfd;
 200 }
 201
 202 /* A helper function that releases any section data attached to the
 203    BFD.  */
 204
 205 static void
 206 free_one_bfd_section (bfd *abfd, asection *sectp, void *ignore)
 207 {
 208   struct gdb_bfd_section_data *sect = bfd_get_section_userdata (abfd, sectp);
 209
 210   if (sect != NULL && sect->data != NULL)
 211     {
 212 #ifdef HAVE_MMAP
 213       if (sect->map_addr != NULL)
 214         {
 215           int res;
 216
 217           res = munmap (sect->map_addr, sect->map_len);
 218           gdb_assert (res == 0);
 219         }
 220       else
 221 #endif
 222         xfree (sect->data);
 223     }
 224 }
 225
 226 /* Close ABFD, and warn if that fails.  */
 227
 228 static int
 229 gdb_bfd_close_or_warn (struct bfd *abfd)
 230 {
 231   int ret;
 232   char *name = bfd_get_filename (abfd);
 233
 234   bfd_map_over_sections (abfd, free_one_bfd_section, NULL);
 235
 236   ret = bfd_close (abfd);
 237
 238   if (!ret)
 239     warning (_("cannot close \"%s\": %s"),
 240              name, bfd_errmsg (bfd_get_error ()));
 241
 242   return ret;
 243 }
 244
 245 /* See gdb_bfd.h.  */
 246
 247 void
 248 gdb_bfd_ref (struct bfd *abfd)
 249 {
 250   struct gdb_bfd_data *gdata;
 251   void **slot;
 252
 253   if (abfd == NULL)
 254     return;
 255
 256   gdata = bfd_usrdata (abfd);
 257
 258   if (gdata != NULL)
 259     {
 260       gdata->refc += 1;
 261       return;
 262     }
 263
 264   /* Ask BFD to decompress sections in bfd_get_full_section_contents.  */
 265   abfd->flags |= BFD_DECOMPRESS;
 266
 267   gdata = bfd_zalloc (abfd, sizeof (struct gdb_bfd_data));
 268   gdata->refc = 1;
 269   gdata->mtime = bfd_get_mtime (abfd);
 270   gdata->archive_bfd = NULL;
 271   bfd_usrdata (abfd) = gdata;
 272
 273   bfd_alloc_data (abfd);
 274
 275   /* This is the first we've seen it, so add it to the hash table.  */
 276   slot = htab_find_slot (all_bfds, abfd, INSERT);
 277   gdb_assert (slot && !*slot);
 278   *slot = abfd;
 279 }
 280
 281 /* See gdb_bfd.h.  */
 282
 283 void
 284 gdb_bfd_unref (struct bfd *abfd)
 285 {
 286   int ix;
 287   struct gdb_bfd_data *gdata;
 288   struct gdb_bfd_cache_search search;
 289   bfd *archive_bfd, *included_bfd;
 290
 291   if (abfd == NULL)
 292     return;
 293
 294   gdata = bfd_usrdata (abfd);
 295   gdb_assert (gdata->refc >= 1);
 296
 297   gdata->refc -= 1;
 298   if (gdata->refc > 0)
 299     return;
 300
 301   archive_bfd = gdata->archive_bfd;
 302   search.filename = bfd_get_filename (abfd);
 303
 304   if (gdb_bfd_cache && search.filename)
 305     {
 306       hashval_t hash = htab_hash_string (search.filename);
 307       void **slot;
 308
 309       search.mtime = gdata->mtime;
 310       slot = htab_find_slot_with_hash (gdb_bfd_cache, &search, hash,
 311                                        NO_INSERT);
 312
 313       if (slot && *slot)
 314         htab_clear_slot (gdb_bfd_cache, slot);
 315     }
 316
 317   for (ix = 0;
 318        VEC_iterate (bfdp, gdata->included_bfds, ix, included_bfd);
 319        ++ix)
 320     gdb_bfd_unref (included_bfd);
 321   VEC_free (bfdp, gdata->included_bfds);
 322
 323   bfd_free_data (abfd);
 324   bfd_usrdata (abfd) = NULL;  /* Paranoia.  */
 325
 326   htab_remove_elt (all_bfds, abfd);
 327
 328   gdb_bfd_close_or_warn (abfd);
 329
 330   gdb_bfd_unref (archive_bfd);
 331 }
 332
 333 /* A helper function that returns the section data descriptor
 334    associated with SECTION.  If no such descriptor exists, a new one
 335    is allocated and cleared.  */
 336
 337 static struct gdb_bfd_section_data *
 338 get_section_descriptor (asection *section)
 339 {
 340   struct gdb_bfd_section_data *result;
 341
 342   result = bfd_get_section_userdata (section->owner, section);
 343
 344   if (result == NULL)
 345     {
 346       result = bfd_zalloc (section->owner, sizeof (*result));
 347       bfd_set_section_userdata (section->owner, section, result);
 348     }
 349
 350   return result;
 351 }
 352
 353 /* See gdb_bfd.h.  */
 354
 355 const gdb_byte *
 356 gdb_bfd_map_section (asection *sectp, bfd_size_type *size)
 357 {
 358   bfd *abfd;
 359   struct gdb_bfd_section_data *descriptor;
 360   bfd_byte *data;
 361
 362   gdb_assert ((sectp->flags & SEC_RELOC) == 0);
 363   gdb_assert (size != NULL);
 364
 365   abfd = sectp->owner;
 366
 367   descriptor = get_section_descriptor (sectp);
 368
 369   /* If the data was already read for this BFD, just reuse it.  */
 370   if (descriptor->data != NULL)
 371     goto done;
 372
 373 #ifdef HAVE_MMAP
 374   if (!bfd_is_section_compressed (abfd, sectp))
 375     {
 376       /* The page size, used when mmapping.  */
 377       static int pagesize;
 378
 379       if (pagesize == 0)
 380         pagesize = getpagesize ();
 381
 382       /* Only try to mmap sections which are large enough: we don't want
 383          to waste space due to fragmentation.  */
 384
 385       if (bfd_get_section_size (sectp) > 4 * pagesize)
 386         {
 387           descriptor->size = bfd_get_section_size (sectp);
 388           descriptor->data = bfd_mmap (abfd, 0, descriptor->size, PROT_READ,
 389                                        MAP_PRIVATE, sectp->filepos,
 390                                        &descriptor->map_addr,
 391                                        &descriptor->map_len);
 392
 393           if ((caddr_t)descriptor->data != MAP_FAILED)
 394             {
 395 #if HAVE_POSIX_MADVISE
 396               posix_madvise (descriptor->map_addr, descriptor->map_len,
 397                              POSIX_MADV_WILLNEED);
 398 #endif
 399               goto done;
 400             }
 401
 402           /* On failure, clear out the section data and try again.  */
 403           memset (descriptor, 0, sizeof (*descriptor));
 404         }
 405     }
 406 #endif /* HAVE_MMAP */
 407
 408   /* Handle compressed sections, or ordinary uncompressed sections in
 409      the no-mmap case.  */
 410
 411   descriptor->size = bfd_get_section_size (sectp);
 412   descriptor->data = NULL;
 413
 414   data = NULL;
 415   if (!bfd_get_full_section_contents (abfd, sectp, &data))
 416     error (_("Can't read data for section '%s' in file '%s'"),
 417            bfd_get_section_name (abfd, sectp),
 418            bfd_get_filename (abfd));
 419   descriptor->data = data;
 420
 421  done:
 422   gdb_assert (descriptor->data != NULL);
 423   *size = descriptor->size;
 424   return descriptor->data;
 425 }
 426
 427 /* Return 32-bit CRC for ABFD.  If successful store it to *FILE_CRC_RETURN and
 428    return 1.  Otherwise print a warning and return 0.  ABFD seek position is
 429    not preserved.  */
 430
 431 static int
 432 get_file_crc (bfd *abfd, unsigned long *file_crc_return)
 433 {
 434   unsigned long file_crc = 0;
 435
 436   if (bfd_seek (abfd, 0, SEEK_SET) != 0)
 437     {
 438       warning (_("Problem reading \"%s\" for CRC: %s"),
 439                bfd_get_filename (abfd), bfd_errmsg (bfd_get_error ()));
 440       return 0;
 441     }
 442
 443   for (;;)
 444     {
 445       gdb_byte buffer[8 * 1024];
 446       bfd_size_type count;
 447
 448       count = bfd_bread (buffer, sizeof (buffer), abfd);
 449       if (count == (bfd_size_type) -1)
 450         {
 451           warning (_("Problem reading \"%s\" for CRC: %s"),
 452                    bfd_get_filename (abfd), bfd_errmsg (bfd_get_error ()));
 453           return 0;
 454         }
 455       if (count == 0)
 456         break;
 457       file_crc = bfd_calc_gnu_debuglink_crc32 (file_crc, buffer, count);
 458     }
 459
 460   *file_crc_return = file_crc;
 461   return 1;
 462 }
 463
 464 /* See gdb_bfd.h.  */
 465
 466 int
 467 gdb_bfd_crc (struct bfd *abfd, unsigned long *crc_out)
 468 {
 469   struct gdb_bfd_data *gdata = bfd_usrdata (abfd);
 470
 471   if (!gdata->crc_computed)
 472     gdata->crc_computed = get_file_crc (abfd, &gdata->crc);
 473
 474   if (gdata->crc_computed)
 475     *crc_out = gdata->crc;
 476   return gdata->crc_computed;
 477 }
 478
 479 \f
 480
 481 /* See gdb_bfd.h.  */
 482
 483 bfd *
 484 gdb_bfd_fopen (const char *filename, const char *target, const char *mode,
 485                int fd)
 486 {
 487   bfd *result = bfd_fopen (filename, target, mode, fd);
 488
 489   if (result)
 490     gdb_bfd_ref (result);
 491
 492   return result;
 493 }
 494
 495 /* See gdb_bfd.h.  */
 496
 497 bfd *
 498 gdb_bfd_openr (const char *filename, const char *target)
 499 {
 500   bfd *result = bfd_openr (filename, target);
 501
 502   if (result)
 503     gdb_bfd_ref (result);
 504
 505   return result;
 506 }
 507
 508 /* See gdb_bfd.h.  */
 509
 510 bfd *
 511 gdb_bfd_openw (const char *filename, const char *target)
 512 {
 513   bfd *result = bfd_openw (filename, target);
 514
 515   if (result)
 516     gdb_bfd_ref (result);
 517
 518   return result;
 519 }
 520
 521 /* See gdb_bfd.h.  */
 522
 523 bfd *
 524 gdb_bfd_openr_iovec (const char *filename, const char *target,
 525                      void *(*open_func) (struct bfd *nbfd,
 526                                          void *open_closure),
 527                      void *open_closure,
 528                      file_ptr (*pread_func) (struct bfd *nbfd,
 529                                              void *stream,
 530                                              void *buf,
 531                                              file_ptr nbytes,
 532                                              file_ptr offset),
 533                      int (*close_func) (struct bfd *nbfd,
 534                                         void *stream),
 535                      int (*stat_func) (struct bfd *abfd,
 536                                        void *stream,
 537                                        struct stat *sb))
 538 {
 539   bfd *result = bfd_openr_iovec (filename, target,
 540                                  open_func, open_closure,
 541                                  pread_func, close_func, stat_func);
 542
 543   if (result)
 544     gdb_bfd_ref (result);
 545
 546   return result;
 547 }
 548
 549 /* See gdb_bfd.h.  */
 550
 551 void
 552 gdb_bfd_mark_parent (bfd *child, bfd *parent)
 553 {
 554   struct gdb_bfd_data *gdata;
 555
 556   gdb_bfd_ref (child);
 557   /* No need to stash the filename here, because we also keep a
 558      reference on the parent archive.  */
 559
 560   gdata = bfd_usrdata (child);
 561   if (gdata->archive_bfd == NULL)
 562     {
 563       gdata->archive_bfd = parent;
 564       gdb_bfd_ref (parent);
 565     }
 566   else
 567     gdb_assert (gdata->archive_bfd == parent);
 568 }
 569
 570 /* See gdb_bfd.h.  */
 571
 572 bfd *
 573 gdb_bfd_openr_next_archived_file (bfd *archive, bfd *previous)
 574 {
 575   bfd *result = bfd_openr_next_archived_file (archive, previous);
 576
 577   if (result)
 578     gdb_bfd_mark_parent (result, archive);
 579
 580   return result;
 581 }
 582
 583 /* See gdb_bfd.h.  */
 584
 585 void
 586 gdb_bfd_record_inclusion (bfd *includer, bfd *includee)
 587 {
 588   struct gdb_bfd_data *gdata;
 589
 590   gdb_bfd_ref (includee);
 591   gdata = bfd_usrdata (includer);
 592   VEC_safe_push (bfdp, gdata->included_bfds, includee);
 593 }
 594
 595 /* See gdb_bfd.h.  */
 596
 597 bfd *
 598 gdb_bfd_fdopenr (const char *filename, const char *target, int fd)
 599 {
 600   bfd *result = bfd_fdopenr (filename, target, fd);
 601
 602   if (result)
 603     gdb_bfd_ref (result);
 604
 605   return result;
 606 }
 607
 608 \f
 609
 610 gdb_static_assert (ARRAY_SIZE (_bfd_std_section) == 4);
 611
 612 /* See gdb_bfd.h.  */
 613
 614 int
 615 gdb_bfd_section_index (bfd *abfd, asection *section)
 616 {
 617   if (section == NULL)
 618     return -1;
 619   else if (section == bfd_com_section_ptr)
 620     return bfd_count_sections (abfd) + 1;
 621   else if (section == bfd_und_section_ptr)
 622     return bfd_count_sections (abfd) + 2;
 623   else if (section == bfd_abs_section_ptr)
 624     return bfd_count_sections (abfd) + 3;
 625   else if (section == bfd_ind_section_ptr)
 626     return bfd_count_sections (abfd) + 4;
 627   return section->index;
 628 }
 629
 630 /* See gdb_bfd.h.  */
 631
 632 int
 633 gdb_bfd_count_sections (bfd *abfd)
 634 {
 635   return bfd_count_sections (abfd) + 4;
 636 }
 637
 638 /* See gdb_bfd.h.  */
 639
 640 int
 641 gdb_bfd_requires_relocations (bfd *abfd)
 642 {
 643   struct gdb_bfd_data *gdata = bfd_usrdata (abfd);
 644
 645   if (gdata->relocation_computed == 0)
 646     {
 647       asection *sect;
 648
 649       for (sect = abfd->sections; sect != NULL; sect = sect->next)
 650         if ((sect->flags & SEC_RELOC) != 0)
 651           {
 652             gdata->needs_relocations = 1;
 653             break;
 654           }
 655
 656       gdata->relocation_computed = 1;
 657     }
 658
 659   return gdata->needs_relocations;
 660 }
 661
 662 \f
 663
 664 /* A callback for htab_traverse that prints a single BFD.  */
 665
 666 static int
 667 print_one_bfd (void **slot, void *data)
 668 {
 669   bfd *abfd = *slot;
 670   struct gdb_bfd_data *gdata = bfd_usrdata (abfd);
 671   struct ui_out *uiout = data;
 672   struct cleanup *inner;
 673
 674   inner = make_cleanup_ui_out_tuple_begin_end (uiout, NULL);
 675   ui_out_field_int (uiout, "refcount", gdata->refc);
 676   ui_out_field_string (uiout, "addr", host_address_to_string (abfd));
 677   ui_out_field_string (uiout, "filename", bfd_get_filename (abfd));
 678   ui_out_text (uiout, "\n");
 679   do_cleanups (inner);
 680
 681   return 1;
 682 }
 683
 684 /* Implement the 'maint info bfd' command.  */
 685
 686 static void
 687 maintenance_info_bfds (char *arg, int from_tty)
 688 {
 689   struct cleanup *cleanup;
 690   struct ui_out *uiout = current_uiout;
 691
 692   cleanup = make_cleanup_ui_out_table_begin_end (uiout, 3, -1, "bfds");
 693   ui_out_table_header (uiout, 10, ui_left, "refcount", "Refcount");
 694   ui_out_table_header (uiout, 18, ui_left, "addr", "Address");
 695   ui_out_table_header (uiout, 40, ui_left, "filename", "Filename");
 696
 697   ui_out_table_body (uiout);
 698   htab_traverse (all_bfds, print_one_bfd, uiout);
 699
 700   do_cleanups (cleanup);
 701 }
 702
 703 /* -Wmissing-prototypes */
 704 extern initialize_file_ftype _initialize_gdb_bfd;
 705
 706 void
 707 _initialize_gdb_bfd (void)
 708 {
 709   all_bfds = htab_create_alloc (10, htab_hash_pointer, htab_eq_pointer,
 710                                 NULL, xcalloc, xfree);
 711
 712   add_cmd ("bfds", class_maintenance, maintenance_info_bfds, _("\
 713 List the BFDs that are currently open."),
 714            &maintenanceinfolist);
 715 }