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 "gdb_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 successfully computed the file's CRC.  */
  86   unsigned int crc_computed : 1;
  87
  88   /* The file's CRC.  */
  89   unsigned long crc;
  90
  91   /* If the BFD comes from an archive, this points to the archive's
  92      BFD.  Otherwise, this is NULL.  */
  93   bfd *archive_bfd;
  94
  95   /* The registry.  */
  96   REGISTRY_FIELDS;
  97 };
  98
  99 #define GDB_BFD_DATA_ACCESSOR(ABFD) \
 100   ((struct gdb_bfd_data *) bfd_usrdata (ABFD))
 101
 102 DEFINE_REGISTRY (bfd, GDB_BFD_DATA_ACCESSOR)
 103
 104 /* A hash table storing all the BFDs maintained in the cache.  */
 105
 106 static htab_t gdb_bfd_cache;
 107
 108 /* The type of an object being looked up in gdb_bfd_cache.  We use
 109    htab's capability of storing one kind of object (BFD in this case)
 110    and using a different sort of object for searching.  */
 111
 112 struct gdb_bfd_cache_search
 113 {
 114   /* The filename.  */
 115   const char *filename;
 116   /* The mtime.  */
 117   time_t mtime;
 118 };
 119
 120 /* A hash function for BFDs.  */
 121
 122 static hashval_t
 123 hash_bfd (const void *b)
 124 {
 125   const bfd *abfd = b;
 126
 127   /* It is simplest to just hash the filename.  */
 128   return htab_hash_string (bfd_get_filename (abfd));
 129 }
 130
 131 /* An equality function for BFDs.  Note that this expects the caller
 132    to search using struct gdb_bfd_cache_search only, not BFDs.  */
 133
 134 static int
 135 eq_bfd (const void *a, const void *b)
 136 {
 137   const bfd *abfd = a;
 138   const struct gdb_bfd_cache_search *s = b;
 139   struct gdb_bfd_data *gdata = bfd_usrdata (abfd);
 140
 141   return (gdata->mtime == s->mtime
 142           && strcmp (bfd_get_filename (abfd), s->filename) == 0);
 143 }
 144
 145 /* See gdb_bfd.h.  */
 146
 147 struct bfd *
 148 gdb_bfd_open (const char *name, const char *target, int fd)
 149 {
 150   hashval_t hash;
 151   void **slot;
 152   bfd *abfd;
 153   struct gdb_bfd_cache_search search;
 154   struct stat st;
 155
 156   if (gdb_bfd_cache == NULL)
 157     gdb_bfd_cache = htab_create_alloc (1, hash_bfd, eq_bfd, NULL,
 158                                        xcalloc, xfree);
 159
 160   if (fd == -1)
 161     {
 162       fd = gdb_open_cloexec (name, O_RDONLY | O_BINARY, 0);
 163       if (fd == -1)
 164         {
 165           bfd_set_error (bfd_error_system_call);
 166           return NULL;
 167         }
 168     }
 169
 170   search.filename = name;
 171   if (fstat (fd, &st) < 0)
 172     {
 173       /* Weird situation here.  */
 174       search.mtime = 0;
 175     }
 176   else
 177     search.mtime = st.st_mtime;
 178
 179   /* Note that this must compute the same result as hash_bfd.  */
 180   hash = htab_hash_string (name);
 181   /* Note that we cannot use htab_find_slot_with_hash here, because
 182      opening the BFD may fail; and this would violate hashtab
 183      invariants.  */
 184   abfd = htab_find_with_hash (gdb_bfd_cache, &search, hash);
 185   if (abfd != NULL)
 186     {
 187       close (fd);
 188       gdb_bfd_ref (abfd);
 189       return abfd;
 190     }
 191
 192   abfd = bfd_fopen (name, target, FOPEN_RB, fd);
 193   if (abfd == NULL)
 194     return NULL;
 195
 196   slot = htab_find_slot_with_hash (gdb_bfd_cache, &search, hash, INSERT);
 197   gdb_assert (!*slot);
 198   *slot = abfd;
 199
 200   gdb_bfd_stash_filename (abfd);
 201   gdb_bfd_ref (abfd);
 202   return abfd;
 203 }
 204
 205 /* A helper function that releases any section data attached to the
 206    BFD.  */
 207
 208 static void
 209 free_one_bfd_section (bfd *abfd, asection *sectp, void *ignore)
 210 {
 211   struct gdb_bfd_section_data *sect = bfd_get_section_userdata (abfd, sectp);
 212
 213   if (sect != NULL && sect->data != NULL)
 214     {
 215 #ifdef HAVE_MMAP
 216       if (sect->map_addr != NULL)
 217         {
 218           int res;
 219
 220           res = munmap (sect->map_addr, sect->map_len);
 221           gdb_assert (res == 0);
 222         }
 223       else
 224 #endif
 225         xfree (sect->data);
 226     }
 227 }
 228
 229 /* Close ABFD, and warn if that fails.  */
 230
 231 static int
 232 gdb_bfd_close_or_warn (struct bfd *abfd)
 233 {
 234   int ret;
 235   char *name = bfd_get_filename (abfd);
 236
 237   bfd_map_over_sections (abfd, free_one_bfd_section, NULL);
 238
 239   ret = bfd_close (abfd);
 240
 241   if (!ret)
 242     warning (_("cannot close \"%s\": %s"),
 243              name, bfd_errmsg (bfd_get_error ()));
 244
 245   return ret;
 246 }
 247
 248 /* See gdb_bfd.h.  */
 249
 250 void
 251 gdb_bfd_ref (struct bfd *abfd)
 252 {
 253   struct gdb_bfd_data *gdata;
 254   void **slot;
 255
 256   if (abfd == NULL)
 257     return;
 258
 259   gdata = bfd_usrdata (abfd);
 260
 261   if (gdata != NULL)
 262     {
 263       gdata->refc += 1;
 264       return;
 265     }
 266
 267   /* Ask BFD to decompress sections in bfd_get_full_section_contents.  */
 268   abfd->flags |= BFD_DECOMPRESS;
 269
 270   gdata = bfd_zalloc (abfd, sizeof (struct gdb_bfd_data));
 271   gdata->refc = 1;
 272   gdata->mtime = bfd_get_mtime (abfd);
 273   gdata->archive_bfd = NULL;
 274   bfd_usrdata (abfd) = gdata;
 275
 276   bfd_alloc_data (abfd);
 277
 278   /* This is the first we've seen it, so add it to the hash table.  */
 279   slot = htab_find_slot (all_bfds, abfd, INSERT);
 280   gdb_assert (slot && !*slot);
 281   *slot = abfd;
 282 }
 283
 284 /* See gdb_bfd.h.  */
 285
 286 void
 287 gdb_bfd_unref (struct bfd *abfd)
 288 {
 289   struct gdb_bfd_data *gdata;
 290   struct gdb_bfd_cache_search search;
 291   bfd *archive_bfd;
 292
 293   if (abfd == NULL)
 294     return;
 295
 296   gdata = bfd_usrdata (abfd);
 297   gdb_assert (gdata->refc >= 1);
 298
 299   gdata->refc -= 1;
 300   if (gdata->refc > 0)
 301     return;
 302
 303   archive_bfd = gdata->archive_bfd;
 304   search.filename = bfd_get_filename (abfd);
 305
 306   if (gdb_bfd_cache && search.filename)
 307     {
 308       hashval_t hash = htab_hash_string (search.filename);
 309       void **slot;
 310
 311       search.mtime = gdata->mtime;
 312       slot = htab_find_slot_with_hash (gdb_bfd_cache, &search, hash,
 313                                        NO_INSERT);
 314
 315       if (slot && *slot)
 316         htab_clear_slot (gdb_bfd_cache, slot);
 317     }
 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     {
 487       gdb_bfd_stash_filename (result);
 488       gdb_bfd_ref (result);
 489     }
 490
 491   return result;
 492 }
 493
 494 /* See gdb_bfd.h.  */
 495
 496 bfd *
 497 gdb_bfd_openr (const char *filename, const char *target)
 498 {
 499   bfd *result = bfd_openr (filename, target);
 500
 501   if (result)
 502     {
 503       gdb_bfd_stash_filename (result);
 504       gdb_bfd_ref (result);
 505     }
 506
 507   return result;
 508 }
 509
 510 /* See gdb_bfd.h.  */
 511
 512 bfd *
 513 gdb_bfd_openw (const char *filename, const char *target)
 514 {
 515   bfd *result = bfd_openw (filename, target);
 516
 517   if (result)
 518     {
 519       gdb_bfd_stash_filename (result);
 520       gdb_bfd_ref (result);
 521     }
 522
 523   return result;
 524 }
 525
 526 /* See gdb_bfd.h.  */
 527
 528 bfd *
 529 gdb_bfd_openr_iovec (const char *filename, const char *target,
 530                      void *(*open_func) (struct bfd *nbfd,
 531                                          void *open_closure),
 532                      void *open_closure,
 533                      file_ptr (*pread_func) (struct bfd *nbfd,
 534                                              void *stream,
 535                                              void *buf,
 536                                              file_ptr nbytes,
 537                                              file_ptr offset),
 538                      int (*close_func) (struct bfd *nbfd,
 539                                         void *stream),
 540                      int (*stat_func) (struct bfd *abfd,
 541                                        void *stream,
 542                                        struct stat *sb))
 543 {
 544   bfd *result = bfd_openr_iovec (filename, target,
 545                                  open_func, open_closure,
 546                                  pread_func, close_func, stat_func);
 547
 548   if (result)
 549     {
 550       gdb_bfd_ref (result);
 551       gdb_bfd_stash_filename (result);
 552     }
 553
 554   return result;
 555 }
 556
 557 /* See gdb_bfd.h.  */
 558
 559 void
 560 gdb_bfd_mark_parent (bfd *child, bfd *parent)
 561 {
 562   struct gdb_bfd_data *gdata;
 563
 564   gdb_bfd_ref (child);
 565   /* No need to stash the filename here, because we also keep a
 566      reference on the parent archive.  */
 567
 568   gdata = bfd_usrdata (child);
 569   if (gdata->archive_bfd == NULL)
 570     {
 571       gdata->archive_bfd = parent;
 572       gdb_bfd_ref (parent);
 573     }
 574   else
 575     gdb_assert (gdata->archive_bfd == parent);
 576 }
 577
 578 /* See gdb_bfd.h.  */
 579
 580 bfd *
 581 gdb_bfd_openr_next_archived_file (bfd *archive, bfd *previous)
 582 {
 583   bfd *result = bfd_openr_next_archived_file (archive, previous);
 584
 585   if (result)
 586     gdb_bfd_mark_parent (result, archive);
 587
 588   return result;
 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     {
 600       gdb_bfd_ref (result);
 601       gdb_bfd_stash_filename (result);
 602     }
 603
 604   return result;
 605 }
 606
 607 \f
 608
 609 gdb_static_assert (ARRAY_SIZE (_bfd_std_section) == 4);
 610
 611 /* See gdb_bfd.h.  */
 612
 613 int
 614 gdb_bfd_section_index (bfd *abfd, asection *section)
 615 {
 616   if (section == NULL)
 617     return -1;
 618   else if (section == bfd_com_section_ptr)
 619     return bfd_count_sections (abfd) + 1;
 620   else if (section == bfd_und_section_ptr)
 621     return bfd_count_sections (abfd) + 2;
 622   else if (section == bfd_abs_section_ptr)
 623     return bfd_count_sections (abfd) + 3;
 624   else if (section == bfd_ind_section_ptr)
 625     return bfd_count_sections (abfd) + 4;
 626   return section->index;
 627 }
 628
 629 /* See gdb_bfd.h.  */
 630
 631 int
 632 gdb_bfd_count_sections (bfd *abfd)
 633 {
 634   return bfd_count_sections (abfd) + 4;
 635 }
 636
 637 \f
 638
 639 /* A callback for htab_traverse that prints a single BFD.  */
 640
 641 static int
 642 print_one_bfd (void **slot, void *data)
 643 {
 644   bfd *abfd = *slot;
 645   struct gdb_bfd_data *gdata = bfd_usrdata (abfd);
 646   struct ui_out *uiout = data;
 647   struct cleanup *inner;
 648
 649   inner = make_cleanup_ui_out_tuple_begin_end (uiout, NULL);
 650   ui_out_field_int (uiout, "refcount", gdata->refc);
 651   ui_out_field_string (uiout, "addr", host_address_to_string (abfd));
 652   ui_out_field_string (uiout, "filename", bfd_get_filename (abfd));
 653   ui_out_text (uiout, "\n");
 654   do_cleanups (inner);
 655
 656   return 1;
 657 }
 658
 659 /* Implement the 'maint info bfd' command.  */
 660
 661 static void
 662 maintenance_info_bfds (char *arg, int from_tty)
 663 {
 664   struct cleanup *cleanup;
 665   struct ui_out *uiout = current_uiout;
 666
 667   cleanup = make_cleanup_ui_out_table_begin_end (uiout, 3, -1, "bfds");
 668   ui_out_table_header (uiout, 10, ui_left, "refcount", "Refcount");
 669   ui_out_table_header (uiout, 18, ui_left, "addr", "Address");
 670   ui_out_table_header (uiout, 40, ui_left, "filename", "Filename");
 671
 672   ui_out_table_body (uiout);
 673   htab_traverse (all_bfds, print_one_bfd, uiout);
 674
 675   do_cleanups (cleanup);
 676 }
 677
 678 /* -Wmissing-prototypes */
 679 extern initialize_file_ftype _initialize_gdb_bfd;
 680
 681 void
 682 _initialize_gdb_bfd (void)
 683 {
 684   all_bfds = htab_create_alloc (10, htab_hash_pointer, htab_eq_pointer,
 685                                 NULL, xcalloc, xfree);
 686
 687   add_cmd ("bfds", class_maintenance, maintenance_info_bfds, _("\
 688 List the BFDs that are currently open."),
 689            &maintenanceinfolist);
 690 }