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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, 2007, 2008, 2009 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 3 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,
21 MA 02110-1301, USA. */
25 SECTION
26 File formats
28 A format is a BFD concept of high level file contents type. The
29 formats supported by BFD are:
31 o <<bfd_object>>
33 The BFD may contain data, symbols, relocations and debug info.
35 o <<bfd_archive>>
37 The BFD contains other BFDs and an optional index.
39 o <<bfd_core>>
41 The BFD contains the result of an executable core dump.
43 SUBSECTION
44 File format functions
47 #include "sysdep.h"
48 #include "bfd.h"
49 #include "libbfd.h"
51 /* IMPORT from targets.c. */
52 extern const size_t _bfd_target_vector_entries;
55 FUNCTION
56 bfd_check_format
58 SYNOPSIS
59 bfd_boolean bfd_check_format (bfd *abfd, bfd_format format);
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>>).
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.
74 The function returns <<TRUE>> on success, otherwise <<FALSE>>
75 with one of the following error codes:
77 o <<bfd_error_invalid_operation>> -
78 if <<format>> is not one of <<bfd_object>>, <<bfd_archive>> or
79 <<bfd_core>>.
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.
85 o <<file_not_recognised>> -
86 none of the backends recognised the file format.
88 o <<bfd_error_file_ambiguously_recognized>> -
89 more than one backend recognised the file format.
92 bfd_boolean
93 bfd_check_format (bfd *abfd, bfd_format format)
95 return bfd_check_format_matches (abfd, format, NULL);
99 FUNCTION
100 bfd_check_format_matches
102 SYNOPSIS
103 bfd_boolean bfd_check_format_matches
104 (bfd *abfd, bfd_format format, char ***matching);
106 DESCRIPTION
107 Like <<bfd_check_format>>, except when it returns FALSE with
108 <<bfd_errno>> set to <<bfd_error_file_ambiguously_recognized>>. In that
109 case, if @var{matching} is not NULL, it will be filled in with
110 a NULL-terminated list of the names of the formats that matched,
111 allocated with <<malloc>>.
112 Then the user may choose a format and try again.
114 When done with the list that @var{matching} points to, the caller
115 should free it.
118 bfd_boolean
119 bfd_check_format_matches (bfd *abfd, bfd_format format, char ***matching)
121 extern const bfd_target binary_vec;
122 const bfd_target * const *target;
123 const bfd_target **matching_vector = NULL;
124 const bfd_target *save_targ, *right_targ, *ar_right_targ;
125 int match_count;
126 int ar_match_index;
128 if (matching != NULL)
129 *matching = NULL;
131 if (!bfd_read_p (abfd)
132 || (unsigned int) abfd->format >= (unsigned int) bfd_type_end)
134 bfd_set_error (bfd_error_invalid_operation);
135 return FALSE;
138 if (abfd->format != bfd_unknown)
139 return abfd->format == format;
141 /* Since the target type was defaulted, check them
142 all in the hope that one will be uniquely recognized. */
143 save_targ = abfd->xvec;
144 match_count = 0;
145 ar_match_index = _bfd_target_vector_entries;
147 if (matching != NULL || *bfd_associated_vector != NULL)
149 bfd_size_type amt;
151 amt = sizeof (*matching_vector) * 2 * _bfd_target_vector_entries;
152 matching_vector = (const bfd_target **) bfd_malloc (amt);
153 if (!matching_vector)
154 return FALSE;
157 right_targ = 0;
158 ar_right_targ = 0;
160 /* Presume the answer is yes. */
161 abfd->format = format;
163 /* If the target type was explicitly specified, just check that target. */
164 if (!abfd->target_defaulted)
166 if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0) /* rewind! */
167 goto err_ret;
169 right_targ = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
171 if (right_targ)
172 goto ok_ret;
174 /* For a long time the code has dropped through to check all
175 targets if the specified target was wrong. I don't know why,
176 and I'm reluctant to change it. However, in the case of an
177 archive, it can cause problems. If the specified target does
178 not permit archives (e.g., the binary target), then we should
179 not allow some other target to recognize it as an archive, but
180 should instead allow the specified target to recognize it as an
181 object. When I first made this change, it broke the PE target,
182 because the specified pei-i386 target did not recognize the
183 actual pe-i386 archive. Since there may be other problems of
184 this sort, I changed this test to check only for the binary
185 target. */
186 if (format == bfd_archive && save_targ == &binary_vec)
187 goto err_unrecog;
190 for (target = bfd_target_vector; *target != NULL; target++)
192 const bfd_target *temp;
193 bfd_error_type err;
195 /* Don't check the default target twice. */
196 if (*target == &binary_vec
197 || (!abfd->target_defaulted && *target == save_targ))
198 continue;
200 abfd->xvec = *target; /* Change BFD's target temporarily. */
202 if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0)
203 goto err_ret;
205 /* If _bfd_check_format neglects to set bfd_error, assume
206 bfd_error_wrong_format. We didn't used to even pay any
207 attention to bfd_error, so I suspect that some
208 _bfd_check_format might have this problem. */
209 bfd_set_error (bfd_error_wrong_format);
211 temp = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
213 if (temp && (abfd->format != bfd_archive || bfd_has_map (abfd)))
215 /* This format checks out as ok! */
216 right_targ = temp;
218 /* If this is the default target, accept it, even if other
219 targets might match. People who want those other targets
220 have to set the GNUTARGET variable. */
221 if (temp == bfd_default_vector[0])
223 match_count = 1;
224 break;
227 if (matching_vector)
228 matching_vector[match_count] = temp;
229 match_count++;
231 else if (temp
232 || (err = bfd_get_error ()) == bfd_error_wrong_object_format
233 || err == bfd_error_file_ambiguously_recognized)
235 /* An archive with no armap or objects of the wrong type,
236 or an ambiguous match. We want this target to match
237 if we get no better matches. */
238 if (ar_right_targ != bfd_default_vector[0])
239 ar_right_targ = *target;
240 if (matching_vector)
241 matching_vector[ar_match_index] = *target;
242 ar_match_index++;
244 else if (err != bfd_error_wrong_format)
245 goto err_ret;
248 if (match_count == 0)
250 /* Try partial matches. */
251 right_targ = ar_right_targ;
253 if (right_targ == bfd_default_vector[0])
255 match_count = 1;
257 else
259 match_count = ar_match_index - _bfd_target_vector_entries;
261 if (matching_vector && match_count > 1)
262 memcpy (matching_vector,
263 matching_vector + _bfd_target_vector_entries,
264 sizeof (*matching_vector) * match_count);
268 if (match_count > 1)
270 const bfd_target * const *assoc = bfd_associated_vector;
272 while ((right_targ = *assoc++) != NULL)
274 int i = match_count;
276 while (--i >= 0)
277 if (matching_vector[i] == right_targ)
278 break;
280 if (i >= 0)
282 match_count = 1;
283 break;
288 if (match_count == 1)
290 ok_ret:
291 abfd->xvec = right_targ; /* Change BFD's target permanently. */
293 /* If the file was opened for update, then `output_has_begun'
294 some time ago when the file was created. Do not recompute
295 sections sizes or alignments in _bfd_set_section_contents.
296 We can not set this flag until after checking the format,
297 because it will interfere with creation of BFD sections. */
298 if (abfd->direction == both_direction)
299 abfd->output_has_begun = TRUE;
301 if (matching_vector)
302 free (matching_vector);
303 return TRUE; /* File position has moved, BTW. */
306 if (match_count == 0)
308 err_unrecog:
309 bfd_set_error (bfd_error_file_not_recognized);
310 err_ret:
311 abfd->xvec = save_targ;
312 abfd->format = bfd_unknown;
313 if (matching_vector)
314 free (matching_vector);
315 return FALSE;
318 abfd->xvec = save_targ; /* Restore original target type. */
319 abfd->format = bfd_unknown; /* Restore original format. */
320 bfd_set_error (bfd_error_file_ambiguously_recognized);
322 if (matching)
324 *matching = (char **) matching_vector;
325 matching_vector[match_count] = NULL;
326 /* Return target names. This is a little nasty. Maybe we
327 should do another bfd_malloc? */
328 while (--match_count >= 0)
330 const char *name = matching_vector[match_count]->name;
331 *(const char **) &matching_vector[match_count] = name;
334 return FALSE;
338 FUNCTION
339 bfd_set_format
341 SYNOPSIS
342 bfd_boolean bfd_set_format (bfd *abfd, bfd_format format);
344 DESCRIPTION
345 This function sets the file format of the BFD @var{abfd} to the
346 format @var{format}. If the target set in the BFD does not
347 support the format requested, the format is invalid, or the BFD
348 is not open for writing, then an error occurs.
351 bfd_boolean
352 bfd_set_format (bfd *abfd, bfd_format format)
354 if (bfd_read_p (abfd)
355 || (unsigned int) abfd->format >= (unsigned int) bfd_type_end)
357 bfd_set_error (bfd_error_invalid_operation);
358 return FALSE;
361 if (abfd->format != bfd_unknown)
362 return abfd->format == format;
364 /* Presume the answer is yes. */
365 abfd->format = format;
367 if (!BFD_SEND_FMT (abfd, _bfd_set_format, (abfd)))
369 abfd->format = bfd_unknown;
370 return FALSE;
373 return TRUE;
377 FUNCTION
378 bfd_format_string
380 SYNOPSIS
381 const char *bfd_format_string (bfd_format format);
383 DESCRIPTION
384 Return a pointer to a const string
385 <<invalid>>, <<object>>, <<archive>>, <<core>>, or <<unknown>>,
386 depending upon the value of @var{format}.
389 const char *
390 bfd_format_string (bfd_format format)
392 if (((int) format < (int) bfd_unknown)
393 || ((int) format >= (int) bfd_type_end))
394 return "invalid";
396 switch (format)
398 case bfd_object:
399 return "object"; /* Linker/assembler/compiler output. */
400 case bfd_archive:
401 return "archive"; /* Object archive file. */
402 case bfd_core:
403 return "core"; /* Core dump. */
404 default:
405 return "unknown";