1 /* Generic BFD support for file formats.
2 Copyright 1990, 1991, 1992, 1993, 1994, 1995, 1999, 2000, 2001, 2002,
3 2003, 2005, 2007, 2008, 2009 Free Software Foundation, Inc.
4 Written by Cygnus Support.
5
6 This file is part of BFD, the Binary File Descriptor library.
7
8 This program is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 3 of the License, or
11 (at your option) any later version.
12
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
17
18 You should have received a copy of the GNU General Public License
19 along with this program; if not, write to the Free Software
20 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
21 MA 02110-1301, USA. */
22
23
24 /*
25 SECTION
26 File formats
27
28 A format is a BFD concept of high level file contents type. The
29 formats supported by BFD are:
30
31 o <<bfd_object>>
32
33 The BFD may contain data, symbols, relocations and debug info.
34
35 o <<bfd_archive>>
36
37 The BFD contains other BFDs and an optional index.
38
39 o <<bfd_core>>
40
41 The BFD contains the result of an executable core dump.
42
43 SUBSECTION
44 File format functions
45 */
46
47 #include "sysdep.h"
48 #include "bfd.h"
49 #include "libbfd.h"
50
51 /* IMPORT from targets.c. */
52 extern const size_t _bfd_target_vector_entries;
53
54 /*
55 FUNCTION
56 bfd_check_format
57
58 SYNOPSIS
59 bfd_boolean bfd_check_format (bfd *abfd, bfd_format format);
60
61 DESCRIPTION
62 Verify if the file attached to the BFD @var{abfd} is compatible
63 with the format @var{format} (i.e., one of <<bfd_object>>,
64 <<bfd_archive>> or <<bfd_core>>).
65
66 If the BFD has been set to a specific target before the
67 call, only the named target and format combination is
68 checked. If the target has not been set, or has been set to
69 <<default>>, then all the known target backends is
70 interrogated to determine a match. If the default target
71 matches, it is used. If not, exactly one target must recognize
72 the file, or an error results.
73
74 The function returns <<TRUE>> on success, otherwise <<FALSE>>
75 with one of the following error codes:
76
77 o <<bfd_error_invalid_operation>> -
78 if <<format>> is not one of <<bfd_object>>, <<bfd_archive>> or
79 <<bfd_core>>.
80
81 o <<bfd_error_system_call>> -
82 if an error occured during a read - even some file mismatches
83 can cause bfd_error_system_calls.
84
85 o <<file_not_recognised>> -
86 none of the backends recognised the file format.
87
88 o <<bfd_error_file_ambiguously_recognized>> -
89 more than one backend recognised the file format.
90 */
91
92 bfd_boolean
bfd_check_format(bfd * abfd,bfd_format format)93 bfd_check_format (bfd *abfd, bfd_format format)
94 {
95 return bfd_check_format_matches (abfd, format, NULL);
96 }
97
98 struct bfd_preserve
99 {
100 void *marker;
101 void *tdata;
102 flagword flags;
103 const struct bfd_arch_info *arch_info;
104 struct bfd_section *sections;
105 struct bfd_section *section_last;
106 unsigned int section_count;
107 struct bfd_hash_table section_htab;
108 };
109
110 /* When testing an object for compatibility with a particular target
111 back-end, the back-end object_p function needs to set up certain
112 fields in the bfd on successfully recognizing the object. This
113 typically happens in a piecemeal fashion, with failures possible at
114 many points. On failure, the bfd is supposed to be restored to its
115 initial state, which is virtually impossible. However, restoring a
116 subset of the bfd state works in practice. This function stores
117 the subset. */
118
119 static bfd_boolean
bfd_preserve_save(bfd * abfd,struct bfd_preserve * preserve)120 bfd_preserve_save (bfd *abfd, struct bfd_preserve *preserve)
121 {
122 preserve->tdata = abfd->tdata.any;
123 preserve->arch_info = abfd->arch_info;
124 preserve->flags = abfd->flags;
125 preserve->sections = abfd->sections;
126 preserve->section_last = abfd->section_last;
127 preserve->section_count = abfd->section_count;
128 preserve->section_htab = abfd->section_htab;
129 preserve->marker = bfd_alloc (abfd, 1);
130 if (preserve->marker == NULL)
131 return FALSE;
132
133 return bfd_hash_table_init (&abfd->section_htab, bfd_section_hash_newfunc,
134 sizeof (struct section_hash_entry));
135 }
136
137 /* Clear out a subset of BFD state. */
138
139 static void
bfd_reinit(bfd * abfd)140 bfd_reinit (bfd *abfd)
141 {
142 abfd->tdata.any = NULL;
143 abfd->arch_info = &bfd_default_arch_struct;
144 abfd->flags &= BFD_FLAGS_SAVED;
145 bfd_section_list_clear (abfd);
146 }
147
148 /* Restores bfd state saved by bfd_preserve_save. */
149
150 static void
bfd_preserve_restore(bfd * abfd,struct bfd_preserve * preserve)151 bfd_preserve_restore (bfd *abfd, struct bfd_preserve *preserve)
152 {
153 bfd_hash_table_free (&abfd->section_htab);
154
155 abfd->tdata.any = preserve->tdata;
156 abfd->arch_info = preserve->arch_info;
157 abfd->flags = preserve->flags;
158 abfd->section_htab = preserve->section_htab;
159 abfd->sections = preserve->sections;
160 abfd->section_last = preserve->section_last;
161 abfd->section_count = preserve->section_count;
162
163 /* bfd_release frees all memory more recently bfd_alloc'd than
164 its arg, as well as its arg. */
165 bfd_release (abfd, preserve->marker);
166 preserve->marker = NULL;
167 }
168
169 /* Called when the bfd state saved by bfd_preserve_save is no longer
170 needed. */
171
172 static void
bfd_preserve_finish(bfd * abfd ATTRIBUTE_UNUSED,struct bfd_preserve * preserve)173 bfd_preserve_finish (bfd *abfd ATTRIBUTE_UNUSED, struct bfd_preserve *preserve)
174 {
175 /* It would be nice to be able to free more memory here, eg. old
176 tdata, but that's not possible since these blocks are sitting
177 inside bfd_alloc'd memory. The section hash is on a separate
178 objalloc. */
179 bfd_hash_table_free (&preserve->section_htab);
180 preserve->marker = NULL;
181 }
182
183 /*
184 FUNCTION
185 bfd_check_format_matches
186
187 SYNOPSIS
188 bfd_boolean bfd_check_format_matches
189 (bfd *abfd, bfd_format format, char ***matching);
190
191 DESCRIPTION
192 Like <<bfd_check_format>>, except when it returns FALSE with
193 <<bfd_errno>> set to <<bfd_error_file_ambiguously_recognized>>. In that
194 case, if @var{matching} is not NULL, it will be filled in with
195 a NULL-terminated list of the names of the formats that matched,
196 allocated with <<malloc>>.
197 Then the user may choose a format and try again.
198
199 When done with the list that @var{matching} points to, the caller
200 should free it.
201 */
202
203 bfd_boolean
bfd_check_format_matches(bfd * abfd,bfd_format format,char *** matching)204 bfd_check_format_matches (bfd *abfd, bfd_format format, char ***matching)
205 {
206 extern const bfd_target binary_vec;
207 const bfd_target * const *target;
208 const bfd_target **matching_vector = NULL;
209 const bfd_target *save_targ, *right_targ, *ar_right_targ, *match_targ;
210 int match_count, best_count, best_match;
211 int ar_match_index;
212 struct bfd_preserve preserve;
213
214 if (matching != NULL)
215 *matching = NULL;
216
217 if (!bfd_read_p (abfd)
218 || (unsigned int) abfd->format >= (unsigned int) bfd_type_end)
219 {
220 bfd_set_error (bfd_error_invalid_operation);
221 return FALSE;
222 }
223
224 if (abfd->format != bfd_unknown)
225 return abfd->format == format;
226
227 if (matching != NULL || *bfd_associated_vector != NULL)
228 {
229 bfd_size_type amt;
230
231 amt = sizeof (*matching_vector) * 2 * _bfd_target_vector_entries;
232 matching_vector = (const bfd_target **) bfd_malloc (amt);
233 if (!matching_vector)
234 return FALSE;
235 }
236
237 /* Presume the answer is yes. */
238 abfd->format = format;
239 save_targ = abfd->xvec;
240 preserve.marker = NULL;
241
242 /* If the target type was explicitly specified, just check that target. */
243 if (!abfd->target_defaulted)
244 {
245 if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0) /* rewind! */
246 goto err_ret;
247
248 right_targ = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
249
250 if (right_targ)
251 goto ok_ret;
252
253 /* For a long time the code has dropped through to check all
254 targets if the specified target was wrong. I don't know why,
255 and I'm reluctant to change it. However, in the case of an
256 archive, it can cause problems. If the specified target does
257 not permit archives (e.g., the binary target), then we should
258 not allow some other target to recognize it as an archive, but
259 should instead allow the specified target to recognize it as an
260 object. When I first made this change, it broke the PE target,
261 because the specified pei-i386 target did not recognize the
262 actual pe-i386 archive. Since there may be other problems of
263 this sort, I changed this test to check only for the binary
264 target. */
265 if (format == bfd_archive && save_targ == &binary_vec)
266 goto err_unrecog;
267 }
268
269 /* Since the target type was defaulted, check them all in the hope
270 that one will be uniquely recognized. */
271 right_targ = NULL;
272 ar_right_targ = NULL;
273 match_targ = NULL;
274 best_match = 256;
275 best_count = 0;
276 match_count = 0;
277 ar_match_index = _bfd_target_vector_entries;
278
279 for (target = bfd_target_vector; *target != NULL; target++)
280 {
281 const bfd_target *temp;
282
283 /* Don't check the default target twice. */
284 if (*target == &binary_vec
285 || (!abfd->target_defaulted && *target == save_targ)
286 || (*target)->match_priority > best_match)
287 continue;
288
289 /* If we already tried a match, the bfd is modified and may
290 have sections attached, which will confuse the next
291 _bfd_check_format call. */
292 bfd_reinit (abfd);
293
294 /* Change BFD's target temporarily. */
295 abfd->xvec = *target;
296
297 if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0)
298 goto err_ret;
299
300 /* If _bfd_check_format neglects to set bfd_error, assume
301 bfd_error_wrong_format. We didn't used to even pay any
302 attention to bfd_error, so I suspect that some
303 _bfd_check_format might have this problem. */
304 bfd_set_error (bfd_error_wrong_format);
305
306 temp = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
307 if (temp)
308 {
309 match_targ = temp;
310 if (preserve.marker != NULL)
311 bfd_preserve_finish (abfd, &preserve);
312
313 if (abfd->format != bfd_archive
314 || (bfd_has_map (abfd)
315 && bfd_get_error () != bfd_error_wrong_object_format))
316 {
317 /* This format checks out as ok! */
318 right_targ = temp;
319
320 /* If this is the default target, accept it, even if
321 other targets might match. People who want those
322 other targets have to set the GNUTARGET variable. */
323 if (temp == bfd_default_vector[0])
324 goto ok_ret;
325
326 if (matching_vector)
327 matching_vector[match_count] = temp;
328 match_count++;
329
330 if (temp->match_priority < best_match)
331 {
332 best_match = temp->match_priority;
333 best_count = 0;
334 }
335 best_count++;
336 }
337 else
338 {
339 /* An archive with no armap or objects of the wrong
340 type. We want this target to match if we get no
341 better matches. */
342 if (ar_right_targ != bfd_default_vector[0])
343 ar_right_targ = *target;
344 if (matching_vector)
345 matching_vector[ar_match_index] = *target;
346 ar_match_index++;
347 }
348
349 if (!bfd_preserve_save (abfd, &preserve))
350 goto err_ret;
351 }
352 else if (bfd_get_error () != bfd_error_wrong_format)
353 goto err_ret;
354 }
355
356 if (best_count == 1)
357 match_count = 1;
358
359 if (match_count == 0)
360 {
361 /* Try partial matches. */
362 right_targ = ar_right_targ;
363
364 if (right_targ == bfd_default_vector[0])
365 {
366 match_count = 1;
367 }
368 else
369 {
370 match_count = ar_match_index - _bfd_target_vector_entries;
371
372 if (matching_vector && match_count > 1)
373 memcpy (matching_vector,
374 matching_vector + _bfd_target_vector_entries,
375 sizeof (*matching_vector) * match_count);
376 }
377 }
378
379 if (match_count > 1)
380 {
381 const bfd_target * const *assoc = bfd_associated_vector;
382
383 while ((right_targ = *assoc++) != NULL)
384 {
385 int i = match_count;
386
387 while (--i >= 0)
388 if (matching_vector[i] == right_targ)
389 break;
390
391 if (i >= 0)
392 {
393 match_count = 1;
394 break;
395 }
396 }
397 }
398
399 /* There is way too much undoing of half-known state here. We
400 really shouldn't iterate on live bfd's. Note that saving the
401 whole bfd and restoring it would be even worse; the first thing
402 you notice is that the cached bfd file position gets out of sync. */
403 if (preserve.marker != NULL)
404 bfd_preserve_restore (abfd, &preserve);
405
406 if (match_count == 1)
407 {
408 abfd->xvec = right_targ;
409 /* If we come out of the loop knowing that the last target that
410 matched is the one we want, then ABFD should still be in a usable
411 state (except possibly for XVEC). */
412 if (match_targ != right_targ)
413 {
414 bfd_reinit (abfd);
415 if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0)
416 goto err_ret;
417 match_targ = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
418 BFD_ASSERT (match_targ != NULL);
419 }
420
421 ok_ret:
422 /* If the file was opened for update, then `output_has_begun'
423 some time ago when the file was created. Do not recompute
424 sections sizes or alignments in _bfd_set_section_contents.
425 We can not set this flag until after checking the format,
426 because it will interfere with creation of BFD sections. */
427 if (abfd->direction == both_direction)
428 abfd->output_has_begun = TRUE;
429
430 if (matching_vector)
431 free (matching_vector);
432
433 /* File position has moved, BTW. */
434 return TRUE;
435 }
436
437 if (match_count == 0)
438 {
439 err_unrecog:
440 bfd_set_error (bfd_error_file_not_recognized);
441 err_ret:
442 abfd->xvec = save_targ;
443 abfd->format = bfd_unknown;
444 if (matching_vector)
445 free (matching_vector);
446 if (preserve.marker != NULL)
447 bfd_preserve_restore (abfd, &preserve);
448 return FALSE;
449 }
450
451 /* Restore original target type and format. */
452 abfd->xvec = save_targ;
453 abfd->format = bfd_unknown;
454 bfd_set_error (bfd_error_file_ambiguously_recognized);
455
456 if (matching)
457 {
458 *matching = (char **) matching_vector;
459 matching_vector[match_count] = NULL;
460 /* Return target names. This is a little nasty. Maybe we
461 should do another bfd_malloc? */
462 while (--match_count >= 0)
463 {
464 const char *name = matching_vector[match_count]->name;
465 *(const char **) &matching_vector[match_count] = name;
466 }
467 }
468 return FALSE;
469 }
470
471 /*
472 FUNCTION
473 bfd_set_format
474
475 SYNOPSIS
476 bfd_boolean bfd_set_format (bfd *abfd, bfd_format format);
477
478 DESCRIPTION
479 This function sets the file format of the BFD @var{abfd} to the
480 format @var{format}. If the target set in the BFD does not
481 support the format requested, the format is invalid, or the BFD
482 is not open for writing, then an error occurs.
483 */
484
485 bfd_boolean
bfd_set_format(bfd * abfd,bfd_format format)486 bfd_set_format (bfd *abfd, bfd_format format)
487 {
488 if (bfd_read_p (abfd)
489 || (unsigned int) abfd->format >= (unsigned int) bfd_type_end)
490 {
491 bfd_set_error (bfd_error_invalid_operation);
492 return FALSE;
493 }
494
495 if (abfd->format != bfd_unknown)
496 return abfd->format == format;
497
498 /* Presume the answer is yes. */
499 abfd->format = format;
500
501 if (!BFD_SEND_FMT (abfd, _bfd_set_format, (abfd)))
502 {
503 abfd->format = bfd_unknown;
504 return FALSE;
505 }
506
507 return TRUE;
508 }
509
510 /*
511 FUNCTION
512 bfd_format_string
513
514 SYNOPSIS
515 const char *bfd_format_string (bfd_format format);
516
517 DESCRIPTION
518 Return a pointer to a const string
519 <<invalid>>, <<object>>, <<archive>>, <<core>>, or <<unknown>>,
520 depending upon the value of @var{format}.
521 */
522
523 const char *
bfd_format_string(bfd_format format)524 bfd_format_string (bfd_format format)
525 {
526 if (((int) format < (int) bfd_unknown)
527 || ((int) format >= (int) bfd_type_end))
528 return "invalid";
529
530 switch (format)
531 {
532 case bfd_object:
533 return "object"; /* Linker/assembler/compiler output. */
534 case bfd_archive:
535 return "archive"; /* Object archive file. */
536 case bfd_core:
537 return "core"; /* Core dump. */
538 default:
539 return "unknown";
540 }
541 }
542