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 #ifdef HAVE_ZLIB_H
  28 #include <zlib.h>
  29 #endif
  30 #ifdef HAVE_MMAP
  31 #include <sys/mman.h>
  32 #ifndef MAP_FAILED
  33 #define MAP_FAILED ((void *) -1)
  34 #endif
  35 #endif
  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 /* See gdb_bfd.h.  */
  60
  61 void
  62 gdb_bfd_stash_filename (struct bfd *abfd)
  63 {
  64   char *name = bfd_get_filename (abfd);
  65   char *data;
  66
  67   data = bfd_alloc (abfd, strlen (name) + 1);
  68   strcpy (data, name);
  69
  70   /* Unwarranted chumminess with BFD.  */
  71   abfd->filename = data;
  72 }
  73
  74 /* An object of this type is stored in each BFD's user data.  */
  75
  76 struct gdb_bfd_data
  77 {
  78   /* The reference count.  */
  79   int refc;
  80
  81   /* The mtime of the BFD at the point the cache entry was made.  */
  82   time_t mtime;
  83
  84   /* If the BFD comes from an archive, this points to the archive's
  85      BFD.  Otherwise, this is NULL.  */
  86   bfd *archive_bfd;
  87
  88   /* The registry.  */
  89   REGISTRY_FIELDS;
  90 };
  91
  92 #define GDB_BFD_DATA_ACCESSOR(ABFD) \
  93   ((struct gdb_bfd_data *) bfd_usrdata (ABFD))
  94
  95 DEFINE_REGISTRY (bfd, GDB_BFD_DATA_ACCESSOR)
  96
  97 /* A hash table storing all the BFDs maintained in the cache.  */
  98
  99 static htab_t gdb_bfd_cache;
 100
 101 /* The type of an object being looked up in gdb_bfd_cache.  We use
 102    htab's capability of storing one kind of object (BFD in this case)
 103    and using a different sort of object for searching.  */
 104
 105 struct gdb_bfd_cache_search
 106 {
 107   /* The filename.  */
 108   const char *filename;
 109   /* The mtime.  */
 110   time_t mtime;
 111 };
 112
 113 /* A hash function for BFDs.  */
 114
 115 static hashval_t
 116 hash_bfd (const void *b)
 117 {
 118   const bfd *abfd = b;
 119
 120   /* It is simplest to just hash the filename.  */
 121   return htab_hash_string (bfd_get_filename (abfd));
 122 }
 123
 124 /* An equality function for BFDs.  Note that this expects the caller
 125    to search using struct gdb_bfd_cache_search only, not BFDs.  */
 126
 127 static int
 128 eq_bfd (const void *a, const void *b)
 129 {
 130   const bfd *abfd = a;
 131   const struct gdb_bfd_cache_search *s = b;
 132   struct gdb_bfd_data *gdata = bfd_usrdata (abfd);
 133
 134   return (gdata->mtime == s->mtime
 135           && strcmp (bfd_get_filename (abfd), s->filename) == 0);
 136 }
 137
 138 /* See gdb_bfd.h.  */
 139
 140 struct bfd *
 141 gdb_bfd_open (const char *name, const char *target, int fd)
 142 {
 143   hashval_t hash;
 144   void **slot;
 145   bfd *abfd;
 146   struct gdb_bfd_cache_search search;
 147   struct stat st;
 148
 149   if (gdb_bfd_cache == NULL)
 150     gdb_bfd_cache = htab_create_alloc (1, hash_bfd, eq_bfd, NULL,
 151                                        xcalloc, xfree);
 152
 153   if (fd == -1)
 154     {
 155       fd = open (name, O_RDONLY | O_BINARY);
 156       if (fd == -1)
 157         {
 158           bfd_set_error (bfd_error_system_call);
 159           return NULL;
 160         }
 161     }
 162
 163   search.filename = name;
 164   if (fstat (fd, &st) < 0)
 165     {
 166       /* Weird situation here.  */
 167       search.mtime = 0;
 168     }
 169   else
 170     search.mtime = st.st_mtime;
 171
 172   /* Note that this must compute the same result as hash_bfd.  */
 173   hash = htab_hash_string (name);
 174   /* Note that we cannot use htab_find_slot_with_hash here, because
 175      opening the BFD may fail; and this would violate hashtab
 176      invariants.  */
 177   abfd = htab_find_with_hash (gdb_bfd_cache, &search, hash);
 178   if (abfd != NULL)
 179     {
 180       close (fd);
 181       gdb_bfd_ref (abfd);
 182       return abfd;
 183     }
 184
 185   abfd = bfd_fopen (name, target, FOPEN_RB, fd);
 186   if (abfd == NULL)
 187     return NULL;
 188
 189   slot = htab_find_slot_with_hash (gdb_bfd_cache, &search, hash, INSERT);
 190   gdb_assert (!*slot);
 191   *slot = abfd;
 192
 193   gdb_bfd_stash_filename (abfd);
 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   struct gdb_bfd_data *gdata;
 283   struct gdb_bfd_cache_search search;
 284   bfd *archive_bfd;
 285
 286   if (abfd == NULL)
 287     return;
 288
 289   gdata = bfd_usrdata (abfd);
 290   gdb_assert (gdata->refc >= 1);
 291
 292   gdata->refc -= 1;
 293   if (gdata->refc > 0)
 294     return;
 295
 296   archive_bfd = gdata->archive_bfd;
 297   search.filename = bfd_get_filename (abfd);
 298
 299   if (gdb_bfd_cache && search.filename)
 300     {
 301       hashval_t hash = htab_hash_string (search.filename);
 302       void **slot;
 303
 304       search.mtime = gdata->mtime;
 305       slot = htab_find_slot_with_hash (gdb_bfd_cache, &search, hash,
 306                                        NO_INSERT);
 307
 308       if (slot && *slot)
 309         htab_clear_slot (gdb_bfd_cache, slot);
 310     }
 311
 312   bfd_free_data (abfd);
 313   bfd_usrdata (abfd) = NULL;  /* Paranoia.  */
 314
 315   htab_remove_elt (all_bfds, abfd);
 316
 317   gdb_bfd_close_or_warn (abfd);
 318
 319   gdb_bfd_unref (archive_bfd);
 320 }
 321
 322 /* A helper function that returns the section data descriptor
 323    associated with SECTION.  If no such descriptor exists, a new one
 324    is allocated and cleared.  */
 325
 326 static struct gdb_bfd_section_data *
 327 get_section_descriptor (asection *section)
 328 {
 329   struct gdb_bfd_section_data *result;
 330
 331   result = bfd_get_section_userdata (section->owner, section);
 332
 333   if (result == NULL)
 334     {
 335       result = bfd_zalloc (section->owner, sizeof (*result));
 336       bfd_set_section_userdata (section->owner, section, result);
 337     }
 338
 339   return result;
 340 }
 341
 342 /* See gdb_bfd.h.  */
 343
 344 const gdb_byte *
 345 gdb_bfd_map_section (asection *sectp, bfd_size_type *size)
 346 {
 347   bfd *abfd;
 348   struct gdb_bfd_section_data *descriptor;
 349   bfd_byte *data;
 350
 351   gdb_assert ((sectp->flags & SEC_RELOC) == 0);
 352   gdb_assert (size != NULL);
 353
 354   abfd = sectp->owner;
 355
 356   descriptor = get_section_descriptor (sectp);
 357
 358   /* If the data was already read for this BFD, just reuse it.  */
 359   if (descriptor->data != NULL)
 360     goto done;
 361
 362 #ifdef HAVE_MMAP
 363   if (!bfd_is_section_compressed (abfd, sectp))
 364     {
 365       /* The page size, used when mmapping.  */
 366       static int pagesize;
 367
 368       if (pagesize == 0)
 369         pagesize = getpagesize ();
 370
 371       /* Only try to mmap sections which are large enough: we don't want
 372          to waste space due to fragmentation.  */
 373
 374       if (bfd_get_section_size (sectp) > 4 * pagesize)
 375         {
 376           descriptor->size = bfd_get_section_size (sectp);
 377           descriptor->data = bfd_mmap (abfd, 0, descriptor->size, PROT_READ,
 378                                        MAP_PRIVATE, sectp->filepos,
 379                                        &descriptor->map_addr,
 380                                        &descriptor->map_len);
 381
 382           if ((caddr_t)descriptor->data != MAP_FAILED)
 383             {
 384 #if HAVE_POSIX_MADVISE
 385               posix_madvise (descriptor->map_addr, descriptor->map_len,
 386                              POSIX_MADV_WILLNEED);
 387 #endif
 388               goto done;
 389             }
 390
 391           /* On failure, clear out the section data and try again.  */
 392           memset (descriptor, 0, sizeof (*descriptor));
 393         }
 394     }
 395 #endif /* HAVE_MMAP */
 396
 397   /* Handle compressed sections, or ordinary uncompressed sections in
 398      the no-mmap case.  */
 399
 400   descriptor->size = bfd_get_section_size (sectp);
 401   descriptor->data = NULL;
 402
 403   data = NULL;
 404   if (!bfd_get_full_section_contents (abfd, sectp, &data))
 405     error (_("Can't read data for section '%s' in file '%s'"),
 406            bfd_get_section_name (abfd, sectp),
 407            bfd_get_filename (abfd));
 408   descriptor->data = data;
 409
 410  done:
 411   gdb_assert (descriptor->data != NULL);
 412   *size = descriptor->size;
 413   return descriptor->data;
 414 }
 415
 416 \f
 417
 418 /* See gdb_bfd.h.  */
 419
 420 bfd *
 421 gdb_bfd_fopen (const char *filename, const char *target, const char *mode,
 422                int fd)
 423 {
 424   bfd *result = bfd_fopen (filename, target, mode, fd);
 425
 426   if (result)
 427     {
 428       gdb_bfd_stash_filename (result);
 429       gdb_bfd_ref (result);
 430     }
 431
 432   return result;
 433 }
 434
 435 /* See gdb_bfd.h.  */
 436
 437 bfd *
 438 gdb_bfd_openr (const char *filename, const char *target)
 439 {
 440   bfd *result = bfd_openr (filename, target);
 441
 442   if (result)
 443     {
 444       gdb_bfd_stash_filename (result);
 445       gdb_bfd_ref (result);
 446     }
 447
 448   return result;
 449 }
 450
 451 /* See gdb_bfd.h.  */
 452
 453 bfd *
 454 gdb_bfd_openw (const char *filename, const char *target)
 455 {
 456   bfd *result = bfd_openw (filename, target);
 457
 458   if (result)
 459     {
 460       gdb_bfd_stash_filename (result);
 461       gdb_bfd_ref (result);
 462     }
 463
 464   return result;
 465 }
 466
 467 /* See gdb_bfd.h.  */
 468
 469 bfd *
 470 gdb_bfd_openr_iovec (const char *filename, const char *target,
 471                      void *(*open_func) (struct bfd *nbfd,
 472                                          void *open_closure),
 473                      void *open_closure,
 474                      file_ptr (*pread_func) (struct bfd *nbfd,
 475                                              void *stream,
 476                                              void *buf,
 477                                              file_ptr nbytes,
 478                                              file_ptr offset),
 479                      int (*close_func) (struct bfd *nbfd,
 480                                         void *stream),
 481                      int (*stat_func) (struct bfd *abfd,
 482                                        void *stream,
 483                                        struct stat *sb))
 484 {
 485   bfd *result = bfd_openr_iovec (filename, target,
 486                                  open_func, open_closure,
 487                                  pread_func, close_func, stat_func);
 488
 489   if (result)
 490     {
 491       gdb_bfd_ref (result);
 492       gdb_bfd_stash_filename (result);
 493     }
 494
 495   return result;
 496 }
 497
 498 /* See gdb_bfd.h.  */
 499
 500 void
 501 gdb_bfd_mark_parent (bfd *child, bfd *parent)
 502 {
 503   struct gdb_bfd_data *gdata;
 504
 505   gdb_bfd_ref (child);
 506   /* No need to stash the filename here, because we also keep a
 507      reference on the parent archive.  */
 508
 509   gdata = bfd_usrdata (child);
 510   if (gdata->archive_bfd == NULL)
 511     {
 512       gdata->archive_bfd = parent;
 513       gdb_bfd_ref (parent);
 514     }
 515   else
 516     gdb_assert (gdata->archive_bfd == parent);
 517 }
 518
 519 /* See gdb_bfd.h.  */
 520
 521 bfd *
 522 gdb_bfd_openr_next_archived_file (bfd *archive, bfd *previous)
 523 {
 524   bfd *result = bfd_openr_next_archived_file (archive, previous);
 525
 526   if (result)
 527     gdb_bfd_mark_parent (result, archive);
 528
 529   return result;
 530 }
 531
 532 /* See gdb_bfd.h.  */
 533
 534 bfd *
 535 gdb_bfd_fdopenr (const char *filename, const char *target, int fd)
 536 {
 537   bfd *result = bfd_fdopenr (filename, target, fd);
 538
 539   if (result)
 540     {
 541       gdb_bfd_ref (result);
 542       gdb_bfd_stash_filename (result);
 543     }
 544
 545   return result;
 546 }
 547
 548 \f
 549
 550 /* A callback for htab_traverse that prints a single BFD.  */
 551
 552 static int
 553 print_one_bfd (void **slot, void *data)
 554 {
 555   bfd *abfd = *slot;
 556   struct gdb_bfd_data *gdata = bfd_usrdata (abfd);
 557   struct ui_out *uiout = data;
 558   struct cleanup *inner;
 559
 560   inner = make_cleanup_ui_out_tuple_begin_end (uiout, NULL);
 561   ui_out_field_int (uiout, "refcount", gdata->refc);
 562   ui_out_field_string (uiout, "addr", host_address_to_string (abfd));
 563   ui_out_field_string (uiout, "filename", bfd_get_filename (abfd));
 564   ui_out_text (uiout, "\n");
 565   do_cleanups (inner);
 566
 567   return 1;
 568 }
 569
 570 /* Implement the 'maint info bfd' command.  */
 571
 572 static void
 573 maintenance_info_bfds (char *arg, int from_tty)
 574 {
 575   struct cleanup *cleanup;
 576   struct ui_out *uiout = current_uiout;
 577
 578   cleanup = make_cleanup_ui_out_table_begin_end (uiout, 3, -1, "bfds");
 579   ui_out_table_header (uiout, 10, ui_left, "refcount", "Refcount");
 580   ui_out_table_header (uiout, 18, ui_left, "addr", "Address");
 581   ui_out_table_header (uiout, 40, ui_left, "filename", "Filename");
 582
 583   ui_out_table_body (uiout);
 584   htab_traverse (all_bfds, print_one_bfd, uiout);
 585
 586   do_cleanups (cleanup);
 587 }
 588
 589 /* -Wmissing-prototypes */
 590 extern initialize_file_ftype _initialize_gdb_bfd;
 591
 592 void
 593 _initialize_gdb_bfd (void)
 594 {
 595   all_bfds = htab_create_alloc (10, htab_hash_pointer, htab_eq_pointer,
 596                                 NULL, xcalloc, xfree);
 597
 598   add_cmd ("bfds", class_maintenance, maintenance_info_bfds, _("\
 599 List the BFDs that are currently open."),
 600            &maintenanceinfolist);
 601 }