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