aboutsummaryrefslogtreecommitdiff
path: root/gdb/gdb_bfd.c
blob: f0e349b6e3af4e494d4cb39e1b7cfdbb70bf4348 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
/* Definitions for BFD wrappers used by GDB.

   Copyright (C) 2011, 2012
   Free Software Foundation, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"
#include "gdb_bfd.h"
#include "gdb_assert.h"
#include "gdb_string.h"
#include "ui-out.h"
#include "gdbcmd.h"
#include "hashtab.h"
#ifdef HAVE_ZLIB_H
#include <zlib.h>
#endif
#ifdef HAVE_MMAP
#include <sys/mman.h>
#ifndef MAP_FAILED
#define MAP_FAILED ((void *) -1)
#endif
#endif

/* An object of this type is stored in the section's user data when
   mapping a section.  */

struct gdb_bfd_section_data
{
  /* Size of the data.  */
  bfd_size_type size;
  /* If the data was mmapped, this is the length of the map.  */
  bfd_size_type map_len;
  /* The data.  If NULL, the section data has not been read.  */
  void *data;
  /* If the data was mmapped, this is the map address.  */
  void *map_addr;
};

/* A hash table holding every BFD that gdb knows about.  This is not
   to be confused with 'gdb_bfd_cache', which is used for sharing
   BFDs; in contrast, this hash is used just to implement
   "maint info bfd".  */

static htab_t all_bfds;

/* See gdb_bfd.h.  */

void
gdb_bfd_stash_filename (struct bfd *abfd)
{
  char *name = bfd_get_filename (abfd);
  char *data;

  data = bfd_alloc (abfd, strlen (name) + 1);
  strcpy (data, name);

  /* Unwarranted chumminess with BFD.  */
  abfd->filename = data;
}

/* An object of this type is stored in each BFD's user data.  */

struct gdb_bfd_data
{
  /* The reference count.  */
  int refc;

  /* The mtime of the BFD at the point the cache entry was made.  */
  time_t mtime;

  /* If the BFD comes from an archive, this points to the archive's
     BFD.  Otherwise, this is NULL.  */
  bfd *archive_bfd;

  /* The registry.  */
  REGISTRY_FIELDS;
};

#define GDB_BFD_DATA_ACCESSOR(ABFD) \
  ((struct gdb_bfd_data *) bfd_usrdata (ABFD))

DEFINE_REGISTRY (bfd, GDB_BFD_DATA_ACCESSOR)

/* A hash table storing all the BFDs maintained in the cache.  */

static htab_t gdb_bfd_cache;

/* The type of an object being looked up in gdb_bfd_cache.  We use
   htab's capability of storing one kind of object (BFD in this case)
   and using a different sort of object for searching.  */

struct gdb_bfd_cache_search
{
  /* The filename.  */
  const char *filename;
  /* The mtime.  */
  time_t mtime;
};

/* A hash function for BFDs.  */

static hashval_t
hash_bfd (const void *b)
{
  const bfd *abfd = b;

  /* It is simplest to just hash the filename.  */
  return htab_hash_string (bfd_get_filename (abfd));
}

/* An equality function for BFDs.  Note that this expects the caller
   to search using struct gdb_bfd_cache_search only, not BFDs.  */

static int
eq_bfd (const void *a, const void *b)
{
  const bfd *abfd = a;
  const struct gdb_bfd_cache_search *s = b;
  struct gdb_bfd_data *gdata = bfd_usrdata (abfd);

  return (gdata->mtime == s->mtime
	  && strcmp (bfd_get_filename (abfd), s->filename) == 0);
}

/* See gdb_bfd.h.  */

struct bfd *
gdb_bfd_open (const char *name, const char *target, int fd)
{
  hashval_t hash;
  void **slot;
  bfd *abfd;
  struct gdb_bfd_cache_search search;
  struct stat st;

  if (gdb_bfd_cache == NULL)
    gdb_bfd_cache = htab_create_alloc (1, hash_bfd, eq_bfd, NULL,
				       xcalloc, xfree);

  if (fd == -1)
    {
      fd = open (name, O_RDONLY | O_BINARY);
      if (fd == -1)
	{
	  bfd_set_error (bfd_error_system_call);
	  return NULL;
	}
    }

  search.filename = name;
  if (fstat (fd, &st) < 0)
    {
      /* Weird situation here.  */
      search.mtime = 0;
    }
  else
    search.mtime = st.st_mtime;

  /* Note that this must compute the same result as hash_bfd.  */
  hash = htab_hash_string (name);
  /* Note that we cannot use htab_find_slot_with_hash here, because
     opening the BFD may fail; and this would violate hashtab
     invariants.  */
  abfd = htab_find_with_hash (gdb_bfd_cache, &search, hash);
  if (abfd != NULL)
    {
      close (fd);
      gdb_bfd_ref (abfd);
      return abfd;
    }

  abfd = bfd_fopen (name, target, FOPEN_RB, fd);
  if (abfd == NULL)
    return NULL;

  slot = htab_find_slot_with_hash (gdb_bfd_cache, &search, hash, INSERT);
  gdb_assert (!*slot);
  *slot = abfd;

  gdb_bfd_stash_filename (abfd);
  gdb_bfd_ref (abfd);
  return abfd;
}

/* A helper function that releases any section data attached to the
   BFD.  */

static void
free_one_bfd_section (bfd *abfd, asection *sectp, void *ignore)
{
  struct gdb_bfd_section_data *sect = bfd_get_section_userdata (abfd, sectp);

  if (sect != NULL && sect->data != NULL)
    {
#ifdef HAVE_MMAP
      if (sect->map_addr != NULL)
	{
	  int res;

	  res = munmap (sect->map_addr, sect->map_len);
	  gdb_assert (res == 0);
	}
      else
#endif
	xfree (sect->data);
    }
}

/* Close ABFD, and warn if that fails.  */

static int
gdb_bfd_close_or_warn (struct bfd *abfd)
{
  int ret;
  char *name = bfd_get_filename (abfd);

  bfd_map_over_sections (abfd, free_one_bfd_section, NULL);

  ret = bfd_close (abfd);

  if (!ret)
    warning (_("cannot close \"%s\": %s"),
	     name, bfd_errmsg (bfd_get_error ()));

  return ret;
}

/* See gdb_bfd.h.  */

void
gdb_bfd_ref (struct bfd *abfd)
{
  struct gdb_bfd_data *gdata;
  void **slot;

  if (abfd == NULL)
    return;

  gdata = bfd_usrdata (abfd);

  if (gdata != NULL)
    {
      gdata->refc += 1;
      return;
    }

  /* Ask BFD to decompress sections in bfd_get_full_section_contents.  */
  abfd->flags |= BFD_DECOMPRESS;

  gdata = bfd_zalloc (abfd, sizeof (struct gdb_bfd_data));
  gdata->refc = 1;
  gdata->mtime = bfd_get_mtime (abfd);
  gdata->archive_bfd = NULL;
  bfd_usrdata (abfd) = gdata;

  bfd_alloc_data (abfd);

  /* This is the first we've seen it, so add it to the hash table.  */
  slot = htab_find_slot (all_bfds, abfd, INSERT);
  gdb_assert (slot && !*slot);
  *slot = abfd;
}

/* See gdb_bfd.h.  */

void
gdb_bfd_unref (struct bfd *abfd)
{
  struct gdb_bfd_data *gdata;
  struct gdb_bfd_cache_search search;
  bfd *archive_bfd;

  if (abfd == NULL)
    return;

  gdata = bfd_usrdata (abfd);
  gdb_assert (gdata->refc >= 1);

  gdata->refc -= 1;
  if (gdata->refc > 0)
    return;

  archive_bfd = gdata->archive_bfd;
  search.filename = bfd_get_filename (abfd);

  if (gdb_bfd_cache && search.filename)
    {
      hashval_t hash = htab_hash_string (search.filename);
      void **slot;

      search.mtime = gdata->mtime;
      slot = htab_find_slot_with_hash (gdb_bfd_cache, &search, hash,
				       NO_INSERT);

      if (slot && *slot)
	htab_clear_slot (gdb_bfd_cache, slot);
    }

  bfd_free_data (abfd);
  bfd_usrdata (abfd) = NULL;  /* Paranoia.  */

  htab_remove_elt (all_bfds, abfd);

  gdb_bfd_close_or_warn (abfd);

  gdb_bfd_unref (archive_bfd);
}

/* A helper function that returns the section data descriptor
   associated with SECTION.  If no such descriptor exists, a new one
   is allocated and cleared.  */

static struct gdb_bfd_section_data *
get_section_descriptor (asection *section)
{
  struct gdb_bfd_section_data *result;

  result = bfd_get_section_userdata (section->owner, section);

  if (result == NULL)
    {
      result = bfd_zalloc (section->owner, sizeof (*result));
      bfd_set_section_userdata (section->owner, section, result);
    }

  return result;
}

/* See gdb_bfd.h.  */

const gdb_byte *
gdb_bfd_map_section (asection *sectp, bfd_size_type *size)
{
  bfd *abfd;
  unsigned char header[4];
  struct gdb_bfd_section_data *descriptor;
  bfd_byte *data;

  gdb_assert ((sectp->flags & SEC_RELOC) == 0);
  gdb_assert (size != NULL);

  abfd = sectp->owner;

  descriptor = get_section_descriptor (sectp);

  /* If the data was already read for this BFD, just reuse it.  */
  if (descriptor->data != NULL)
    goto done;

#ifdef HAVE_MMAP
  if (!bfd_is_section_compressed (abfd, sectp))
    {
      /* The page size, used when mmapping.  */
      static int pagesize;

      if (pagesize == 0)
	pagesize = getpagesize ();

      /* Only try to mmap sections which are large enough: we don't want
	 to waste space due to fragmentation.  */

      if (bfd_get_section_size (sectp) > 4 * pagesize)
	{
	  descriptor->size = bfd_get_section_size (sectp);
	  descriptor->data = bfd_mmap (abfd, 0, descriptor->size, PROT_READ,
				       MAP_PRIVATE, sectp->filepos,
				       &descriptor->map_addr,
				       &descriptor->map_len);

	  if ((caddr_t)descriptor->data != MAP_FAILED)
	    {
#if HAVE_POSIX_MADVISE
	      posix_madvise (descriptor->map_addr, descriptor->map_len,
			     POSIX_MADV_WILLNEED);
#endif
	      goto done;
	    }

	  /* On failure, clear out the section data and try again.  */
	  memset (descriptor, 0, sizeof (*descriptor));
	}
    }
#endif /* HAVE_MMAP */

  /* Handle compressed sections, or ordinary uncompressed sections in
     the no-mmap case.  */

  descriptor->size = bfd_get_section_size (sectp);
  descriptor->data = NULL;

  data = NULL;
  if (!bfd_get_full_section_contents (abfd, sectp, &data))
    error (_("Can't read data for section '%s' in file '%s'"),
	   bfd_get_section_name (abfd, sectp),
	   bfd_get_filename (abfd));
  descriptor->data = data;

 done:
  gdb_assert (descriptor->data != NULL);
  *size = descriptor->size;
  return descriptor->data;
}



/* See gdb_bfd.h.  */

bfd *
gdb_bfd_fopen (const char *filename, const char *target, const char *mode,
	       int fd)
{
  bfd *result = bfd_fopen (filename, target, mode, fd);

  if (result)
    {
      gdb_bfd_stash_filename (result);
      gdb_bfd_ref (result);
    }

  return result;
}

/* See gdb_bfd.h.  */

bfd *
gdb_bfd_openr (const char *filename, const char *target)
{
  bfd *result = bfd_openr (filename, target);

  if (result)
    {
      gdb_bfd_stash_filename (result);
      gdb_bfd_ref (result);
    }

  return result;
}

/* See gdb_bfd.h.  */

bfd *
gdb_bfd_openw (const char *filename, const char *target)
{
  bfd *result = bfd_openw (filename, target);

  if (result)
    {
      gdb_bfd_stash_filename (result);
      gdb_bfd_ref (result);
    }

  return result;
}

/* See gdb_bfd.h.  */

bfd *
gdb_bfd_openr_iovec (const char *filename, const char *target,
		     void *(*open_func) (struct bfd *nbfd,
					 void *open_closure),
		     void *open_closure,
		     file_ptr (*pread_func) (struct bfd *nbfd,
					     void *stream,
					     void *buf,
					     file_ptr nbytes,
					     file_ptr offset),
		     int (*close_func) (struct bfd *nbfd,
					void *stream),
		     int (*stat_func) (struct bfd *abfd,
				       void *stream,
				       struct stat *sb))
{
  bfd *result = bfd_openr_iovec (filename, target,
				 open_func, open_closure,
				 pread_func, close_func, stat_func);

  if (result)
    {
      gdb_bfd_ref (result);
      gdb_bfd_stash_filename (result);
    }

  return result;
}

/* See gdb_bfd.h.  */

void
gdb_bfd_mark_parent (bfd *child, bfd *parent)
{
  struct gdb_bfd_data *gdata;

  gdb_bfd_ref (child);
  /* No need to stash the filename here, because we also keep a
     reference on the parent archive.  */

  gdata = bfd_usrdata (child);
  if (gdata->archive_bfd == NULL)
    {
      gdata->archive_bfd = parent;
      gdb_bfd_ref (parent);
    }
  else
    gdb_assert (gdata->archive_bfd == parent);
}

/* See gdb_bfd.h.  */

bfd *
gdb_bfd_openr_next_archived_file (bfd *archive, bfd *previous)
{
  bfd *result = bfd_openr_next_archived_file (archive, previous);

  if (result)
    gdb_bfd_mark_parent (result, archive);

  return result;
}

/* See gdb_bfd.h.  */

bfd *
gdb_bfd_fdopenr (const char *filename, const char *target, int fd)
{
  bfd *result = bfd_fdopenr (filename, target, fd);

  if (result)
    {
      gdb_bfd_ref (result);
      gdb_bfd_stash_filename (result);
    }

  return result;
}



/* A callback for htab_traverse that prints a single BFD.  */

static int
print_one_bfd (void **slot, void *data)
{
  bfd *abfd = *slot;
  struct gdb_bfd_data *gdata = bfd_usrdata (abfd);
  struct ui_out *uiout = data;
  struct cleanup *inner;

  inner = make_cleanup_ui_out_tuple_begin_end (uiout, NULL);
  ui_out_field_int (uiout, "refcount", gdata->refc);
  ui_out_field_string (uiout, "addr", host_address_to_string (abfd));
  ui_out_field_string (uiout, "filename", bfd_get_filename (abfd));
  ui_out_text (uiout, "\n");
  do_cleanups (inner);

  return 1;
}

/* Implement the 'maint info bfd' command.  */

static void
maintenance_info_bfds (char *arg, int from_tty)
{
  struct cleanup *cleanup;
  struct ui_out *uiout = current_uiout;

  cleanup = make_cleanup_ui_out_table_begin_end (uiout, 3, -1, "bfds");
  ui_out_table_header (uiout, 10, ui_left, "refcount", "Refcount");
  ui_out_table_header (uiout, 18, ui_left, "addr", "Address");
  ui_out_table_header (uiout, 40, ui_left, "filename", "Filename");

  ui_out_table_body (uiout);
  htab_traverse (all_bfds, print_one_bfd, uiout);

  do_cleanups (cleanup);
}

/* -Wmissing-prototypes */
extern initialize_file_ftype _initialize_gdb_bfd;

void
_initialize_gdb_bfd (void)
{
  all_bfds = htab_create_alloc (10, htab_hash_pointer, htab_eq_pointer,
				NULL, xcalloc, xfree);

  add_cmd ("bfds", class_maintenance, maintenance_info_bfds, _("\
List the BFDs that are currently open."),
	   &maintenanceinfolist);
}