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[binutils.git] / bfd / format.c
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1 /* Generic BFD support for file formats.
2 Copyright 1990, 1991, 1992, 1993, 1994, 1995, 1999, 2000, 2001, 2002,
3 2003, 2005 Free Software Foundation, Inc.
4 Written by Cygnus Support.
6 This file is part of BFD, the Binary File Descriptor library.
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 2 of the License, or
11 (at your option) any later version.
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.
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, MA 02110-1301, USA. */
23 SECTION
24 File formats
26 A format is a BFD concept of high level file contents type. The
27 formats supported by BFD are:
29 o <<bfd_object>>
31 The BFD may contain data, symbols, relocations and debug info.
33 o <<bfd_archive>>
35 The BFD contains other BFDs and an optional index.
37 o <<bfd_core>>
39 The BFD contains the result of an executable core dump.
43 #include "bfd.h"
44 #include "sysdep.h"
45 #include "libbfd.h"
47 /* IMPORT from targets.c. */
48 extern const size_t _bfd_target_vector_entries;
51 FUNCTION
52 bfd_check_format
54 SYNOPSIS
55 bfd_boolean bfd_check_format (bfd *abfd, bfd_format format);
57 DESCRIPTION
58 Verify if the file attached to the BFD @var{abfd} is compatible
59 with the format @var{format} (i.e., one of <<bfd_object>>,
60 <<bfd_archive>> or <<bfd_core>>).
62 If the BFD has been set to a specific target before the
63 call, only the named target and format combination is
64 checked. If the target has not been set, or has been set to
65 <<default>>, then all the known target backends is
66 interrogated to determine a match. If the default target
67 matches, it is used. If not, exactly one target must recognize
68 the file, or an error results.
70 The function returns <<TRUE>> on success, otherwise <<FALSE>>
71 with one of the following error codes:
73 o <<bfd_error_invalid_operation>> -
74 if <<format>> is not one of <<bfd_object>>, <<bfd_archive>> or
75 <<bfd_core>>.
77 o <<bfd_error_system_call>> -
78 if an error occured during a read - even some file mismatches
79 can cause bfd_error_system_calls.
81 o <<file_not_recognised>> -
82 none of the backends recognised the file format.
84 o <<bfd_error_file_ambiguously_recognized>> -
85 more than one backend recognised the file format.
88 bfd_boolean
89 bfd_check_format (bfd *abfd, bfd_format format)
91 return bfd_check_format_matches (abfd, format, NULL);
95 FUNCTION
96 bfd_check_format_matches
98 SYNOPSIS
99 bfd_boolean bfd_check_format_matches
100 (bfd *abfd, bfd_format format, char ***matching);
102 DESCRIPTION
103 Like <<bfd_check_format>>, except when it returns FALSE with
104 <<bfd_errno>> set to <<bfd_error_file_ambiguously_recognized>>. In that
105 case, if @var{matching} is not NULL, it will be filled in with
106 a NULL-terminated list of the names of the formats that matched,
107 allocated with <<malloc>>.
108 Then the user may choose a format and try again.
110 When done with the list that @var{matching} points to, the caller
111 should free it.
114 bfd_boolean
115 bfd_check_format_matches (bfd *abfd, bfd_format format, char ***matching)
117 extern const bfd_target binary_vec;
118 const bfd_target * const *target;
119 const bfd_target **matching_vector = NULL;
120 const bfd_target *save_targ, *right_targ, *ar_right_targ;
121 int match_count;
122 int ar_match_index;
124 if (!bfd_read_p (abfd)
125 || (unsigned int) abfd->format >= (unsigned int) bfd_type_end)
127 bfd_set_error (bfd_error_invalid_operation);
128 return FALSE;
131 if (abfd->format != bfd_unknown)
132 return abfd->format == format;
134 /* Since the target type was defaulted, check them
135 all in the hope that one will be uniquely recognized. */
136 save_targ = abfd->xvec;
137 match_count = 0;
138 ar_match_index = _bfd_target_vector_entries;
140 if (matching)
142 bfd_size_type amt;
144 *matching = NULL;
145 amt = sizeof (*matching_vector) * 2 * _bfd_target_vector_entries;
146 matching_vector = bfd_malloc (amt);
147 if (!matching_vector)
148 return FALSE;
151 right_targ = 0;
152 ar_right_targ = 0;
154 /* Presume the answer is yes. */
155 abfd->format = format;
157 /* If the target type was explicitly specified, just check that target. */
158 if (!abfd->target_defaulted)
160 if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0) /* rewind! */
162 if (matching)
163 free (matching_vector);
164 return FALSE;
167 right_targ = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
169 if (right_targ)
171 abfd->xvec = right_targ; /* Set the target as returned. */
173 if (matching)
174 free (matching_vector);
176 /* If the file was opened for update, then `output_has_begun'
177 some time ago when the file was created. Do not recompute
178 sections sizes or alignments in _bfd_set_section_contents.
179 We can not set this flag until after checking the format,
180 because it will interfere with creation of BFD sections. */
181 if (abfd->direction == both_direction)
182 abfd->output_has_begun = TRUE;
184 return TRUE; /* File position has moved, BTW. */
187 /* For a long time the code has dropped through to check all
188 targets if the specified target was wrong. I don't know why,
189 and I'm reluctant to change it. However, in the case of an
190 archive, it can cause problems. If the specified target does
191 not permit archives (e.g., the binary target), then we should
192 not allow some other target to recognize it as an archive, but
193 should instead allow the specified target to recognize it as an
194 object. When I first made this change, it broke the PE target,
195 because the specified pei-i386 target did not recognize the
196 actual pe-i386 archive. Since there may be other problems of
197 this sort, I changed this test to check only for the binary
198 target. */
199 if (format == bfd_archive && save_targ == &binary_vec)
201 abfd->xvec = save_targ;
202 abfd->format = bfd_unknown;
204 if (matching)
205 free (matching_vector);
207 bfd_set_error (bfd_error_file_not_recognized);
209 return FALSE;
213 for (target = bfd_target_vector; *target != NULL; target++)
215 const bfd_target *temp;
216 bfd_error_type err;
218 if (*target == &binary_vec)
219 continue;
221 abfd->xvec = *target; /* Change BFD's target temporarily. */
223 if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0)
225 if (matching)
226 free (matching_vector);
227 return FALSE;
230 /* If _bfd_check_format neglects to set bfd_error, assume
231 bfd_error_wrong_format. We didn't used to even pay any
232 attention to bfd_error, so I suspect that some
233 _bfd_check_format might have this problem. */
234 bfd_set_error (bfd_error_wrong_format);
236 temp = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
238 if (temp)
240 /* This format checks out as ok! */
241 right_targ = temp;
243 /* If this is the default target, accept it, even if other
244 targets might match. People who want those other targets
245 have to set the GNUTARGET variable. */
246 if (temp == bfd_default_vector[0])
248 match_count = 1;
249 break;
252 if (matching)
253 matching_vector[match_count] = temp;
255 match_count++;
257 else if ((err = bfd_get_error ()) == bfd_error_wrong_object_format
258 || err == bfd_error_file_ambiguously_recognized)
260 /* An archive with objects of the wrong type, or an
261 ambiguous match. We want this target to match if we get
262 no better matches. */
263 if (ar_right_targ != bfd_default_vector[0])
264 ar_right_targ = *target;
265 if (matching)
266 matching_vector[ar_match_index] = *target;
267 ar_match_index++;
269 else if (err != bfd_error_wrong_format)
271 abfd->xvec = save_targ;
272 abfd->format = bfd_unknown;
274 if (matching)
275 free (matching_vector);
277 return FALSE;
281 if (match_count == 0)
283 /* Try partial matches. */
284 right_targ = ar_right_targ;
286 if (right_targ == bfd_default_vector[0])
288 match_count = 1;
290 else
292 match_count = ar_match_index - _bfd_target_vector_entries;
294 if (matching && match_count > 1)
295 memcpy (matching_vector,
296 matching_vector + _bfd_target_vector_entries,
297 sizeof (*matching_vector) * match_count);
301 if (match_count > 1
302 && bfd_associated_vector != NULL
303 && matching)
305 const bfd_target * const *assoc = bfd_associated_vector;
307 while ((right_targ = *assoc++) != NULL)
309 int i = match_count;
311 while (--i >= 0)
312 if (matching_vector[i] == right_targ)
313 break;
315 if (i >= 0)
317 match_count = 1;
318 break;
323 if (match_count == 1)
325 abfd->xvec = right_targ; /* Change BFD's target permanently. */
327 if (matching)
328 free (matching_vector);
330 /* If the file was opened for update, then `output_has_begun'
331 some time ago when the file was created. Do not recompute
332 sections sizes or alignments in _bfd_set_section_contents.
333 We can not set this flag until after checking the format,
334 because it will interfere with creation of BFD sections. */
335 if (abfd->direction == both_direction)
336 abfd->output_has_begun = TRUE;
338 return TRUE; /* File position has moved, BTW. */
341 abfd->xvec = save_targ; /* Restore original target type. */
342 abfd->format = bfd_unknown; /* Restore original format. */
344 if (match_count == 0)
346 bfd_set_error (bfd_error_file_not_recognized);
348 if (matching)
349 free (matching_vector);
351 else
353 bfd_set_error (bfd_error_file_ambiguously_recognized);
355 if (matching)
357 *matching = (char **) matching_vector;
358 matching_vector[match_count] = NULL;
359 /* Return target names. This is a little nasty. Maybe we
360 should do another bfd_malloc? */
361 while (--match_count >= 0)
363 const char *name = matching_vector[match_count]->name;
364 *(const char **) &matching_vector[match_count] = name;
369 return FALSE;
373 FUNCTION
374 bfd_set_format
376 SYNOPSIS
377 bfd_boolean bfd_set_format (bfd *abfd, bfd_format format);
379 DESCRIPTION
380 This function sets the file format of the BFD @var{abfd} to the
381 format @var{format}. If the target set in the BFD does not
382 support the format requested, the format is invalid, or the BFD
383 is not open for writing, then an error occurs.
386 bfd_boolean
387 bfd_set_format (bfd *abfd, bfd_format format)
389 if (bfd_read_p (abfd)
390 || (unsigned int) abfd->format >= (unsigned int) bfd_type_end)
392 bfd_set_error (bfd_error_invalid_operation);
393 return FALSE;
396 if (abfd->format != bfd_unknown)
397 return abfd->format == format;
399 /* Presume the answer is yes. */
400 abfd->format = format;
402 if (!BFD_SEND_FMT (abfd, _bfd_set_format, (abfd)))
404 abfd->format = bfd_unknown;
405 return FALSE;
408 return TRUE;
412 FUNCTION
413 bfd_format_string
415 SYNOPSIS
416 const char *bfd_format_string (bfd_format format);
418 DESCRIPTION
419 Return a pointer to a const string
420 <<invalid>>, <<object>>, <<archive>>, <<core>>, or <<unknown>>,
421 depending upon the value of @var{format}.
424 const char *
425 bfd_format_string (bfd_format format)
427 if (((int) format < (int) bfd_unknown)
428 || ((int) format >= (int) bfd_type_end))
429 return "invalid";
431 switch (format)
433 case bfd_object:
434 return "object"; /* Linker/assembler/compiler output. */
435 case bfd_archive:
436 return "archive"; /* Object archive file. */
437 case bfd_core:
438 return "core"; /* Core dump. */
439 default:
440 return "unknown";