bfd/format.c

   1 /* Generic BFD support for file formats.
   2    Copyright 1990, 1991, 1992, 1993, 1994, 1995, 1999, 2000, 2001, 2002
   3    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 2 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  21
  22 /*
  23 SECTION
  24         File formats
  25
  26         A format is a BFD concept of high level file contents type. The
  27         formats supported by BFD are:
  28
  29         o <<bfd_object>>
  30
  31         The BFD may contain data, symbols, relocations and debug info.
  32
  33         o <<bfd_archive>>
  34
  35         The BFD contains other BFDs and an optional index.
  36
  37         o <<bfd_core>>
  38
  39         The BFD contains the result of an executable core dump.
  40
  41 */
  42
  43 #include "bfd.h"
  44 #include "sysdep.h"
  45 #include "libbfd.h"
  46
  47 /* IMPORT from targets.c.  */
  48 extern const size_t _bfd_target_vector_entries;
  49
  50 /*
  51 FUNCTION
  52         bfd_check_format
  53
  54 SYNOPSIS
  55         bfd_boolean bfd_check_format(bfd *abfd, bfd_format format);
  56
  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>>).
  61
  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.
  69
  70         The function returns <<TRUE>> on success, otherwise <<FALSE>>
  71         with one of the following error codes:
  72
  73         o <<bfd_error_invalid_operation>> -
  74         if <<format>> is not one of <<bfd_object>>, <<bfd_archive>> or
  75         <<bfd_core>>.
  76
  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.
  80
  81         o <<file_not_recognised>> -
  82         none of the backends recognised the file format.
  83
  84         o <<bfd_error_file_ambiguously_recognized>> -
  85         more than one backend recognised the file format.
  86 */
  87
  88 bfd_boolean
  89 bfd_check_format (abfd, format)
  90      bfd *abfd;
  91      bfd_format format;
  92 {
  93   return bfd_check_format_matches (abfd, format, NULL);
  94 }
  95
  96 /*
  97 FUNCTION
  98         bfd_check_format_matches
  99
 100 SYNOPSIS
 101         bfd_boolean bfd_check_format_matches(bfd *abfd, bfd_format format, char ***matching);
 102
 103 DESCRIPTION
 104         Like <<bfd_check_format>>, except when it returns FALSE with
 105         <<bfd_errno>> set to <<bfd_error_file_ambiguously_recognized>>.  In that
 106         case, if @var{matching} is not NULL, it will be filled in with
 107         a NULL-terminated list of the names of the formats that matched,
 108         allocated with <<malloc>>.
 109         Then the user may choose a format and try again.
 110
 111         When done with the list that @var{matching} points to, the caller
 112         should free it.
 113 */
 114
 115 bfd_boolean
 116 bfd_check_format_matches (abfd, format, matching)
 117      bfd *abfd;
 118      bfd_format format;
 119      char ***matching;
 120 {
 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;
 127
 128   if (!bfd_read_p (abfd)
 129       || (unsigned int) abfd->format >= (unsigned int) bfd_type_end)
 130     {
 131       bfd_set_error (bfd_error_invalid_operation);
 132       return FALSE;
 133     }
 134
 135   if (abfd->format != bfd_unknown)
 136     return abfd->format == format;
 137
 138   /* Since the target type was defaulted, check them
 139      all in the hope that one will be uniquely recognized.  */
 140   save_targ = abfd->xvec;
 141   match_count = 0;
 142   ar_match_index = _bfd_target_vector_entries;
 143
 144   if (matching)
 145     {
 146       bfd_size_type amt;
 147
 148       *matching = NULL;
 149       amt = sizeof (*matching_vector) * 2 * _bfd_target_vector_entries;
 150       matching_vector = (const bfd_target **) bfd_malloc (amt);
 151       if (!matching_vector)
 152         return FALSE;
 153     }
 154
 155   right_targ = 0;
 156   ar_right_targ = 0;
 157
 158   /* Presume the answer is yes.  */
 159   abfd->format = format;
 160
 161   /* If the target type was explicitly specified, just check that target.  */
 162   if (!abfd->target_defaulted)
 163     {
 164       if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0) /* rewind! */
 165         return FALSE;
 166
 167       right_targ = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
 168
 169       if (right_targ)
 170         {
 171           abfd->xvec = right_targ;      /* Set the target as returned.  */
 172
 173           if (matching)
 174             free ((PTR) matching_vector);
 175
 176           return TRUE;                  /* File position has moved, BTW.  */
 177         }
 178
 179       /* For a long time the code has dropped through to check all
 180          targets if the specified target was wrong.  I don't know why,
 181          and I'm reluctant to change it.  However, in the case of an
 182          archive, it can cause problems.  If the specified target does
 183          not permit archives (e.g., the binary target), then we should
 184          not allow some other target to recognize it as an archive, but
 185          should instead allow the specified target to recognize it as an
 186          object.  When I first made this change, it broke the PE target,
 187          because the specified pei-i386 target did not recognize the
 188          actual pe-i386 archive.  Since there may be other problems of
 189          this sort, I changed this test to check only for the binary
 190          target.  */
 191       if (format == bfd_archive && save_targ == &binary_vec)
 192         {
 193           abfd->xvec = save_targ;
 194           abfd->format = bfd_unknown;
 195
 196           if (matching)
 197             free ((PTR) matching_vector);
 198
 199           bfd_set_error (bfd_error_file_not_recognized);
 200
 201           return FALSE;
 202         }
 203     }
 204
 205   for (target = bfd_target_vector; *target != NULL; target++)
 206     {
 207       const bfd_target *temp;
 208       bfd_error_type err;
 209
 210       if (*target == &binary_vec)
 211         continue;
 212
 213       abfd->xvec = *target;     /* Change BFD's target temporarily */
 214
 215       if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0)
 216         return FALSE;
 217
 218       /* If _bfd_check_format neglects to set bfd_error, assume
 219          bfd_error_wrong_format.  We didn't used to even pay any
 220          attention to bfd_error, so I suspect that some
 221          _bfd_check_format might have this problem.  */
 222       bfd_set_error (bfd_error_wrong_format);
 223
 224       temp = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
 225
 226       if (temp)
 227         {               /* This format checks out as ok!  */
 228           right_targ = temp;
 229
 230           /* If this is the default target, accept it, even if other
 231              targets might match.  People who want those other targets
 232              have to set the GNUTARGET variable.  */
 233           if (temp == bfd_default_vector[0])
 234             {
 235               match_count = 1;
 236               break;
 237             }
 238
 239           if (matching)
 240             matching_vector[match_count] = temp;
 241
 242           match_count++;
 243
 244 #ifdef GNU960
 245           /* Big- and little-endian b.out archives look the same, but it
 246              doesn't matter: there is no difference in their headers, and
 247              member file byte orders will (I hope) be handled appropriately
 248              by bfd.  Ditto for big and little coff archives.  And the 4
 249              coff/b.out object formats are unambiguous.  So accept the
 250              first match we find.  */
 251           break;
 252 #endif
 253         }
 254       else if ((err = bfd_get_error ()) == bfd_error_wrong_object_format
 255                || err == bfd_error_file_ambiguously_recognized)
 256         {
 257           /* An archive with objects of the wrong type, or an
 258              ambiguous match.  We want this target to match if we get
 259              no better matches.  */
 260           if (ar_right_targ != bfd_default_vector[0])
 261             ar_right_targ = *target;
 262           if (matching)
 263             matching_vector[ar_match_index] = *target;
 264           ar_match_index++;
 265         }
 266       else if (err != bfd_error_wrong_format)
 267         {
 268           abfd->xvec = save_targ;
 269           abfd->format = bfd_unknown;
 270
 271           if (matching)
 272             free ((PTR) matching_vector);
 273
 274           return FALSE;
 275         }
 276     }
 277
 278   if (match_count == 0)
 279     {
 280       /* Try partial matches.  */
 281       right_targ = ar_right_targ;
 282       if (right_targ == bfd_default_vector[0])
 283         {
 284           match_count = 1;
 285         }
 286       else
 287         {
 288           match_count = ar_match_index - _bfd_target_vector_entries;
 289           if (matching && match_count > 1)
 290             {
 291               memcpy (matching_vector,
 292                       matching_vector + _bfd_target_vector_entries,
 293                       sizeof (*matching_vector) * match_count);
 294             }
 295         }
 296     }
 297
 298   if (match_count > 1 && bfd_associated_vector != NULL)
 299     {
 300       const bfd_target * const *assoc = bfd_associated_vector;
 301
 302       while ((right_targ = *assoc++) != NULL)
 303         {
 304           int i = match_count;
 305
 306           while (--i >= 0)
 307             if (matching_vector[i] == right_targ)
 308               break;
 309
 310           if (i >= 0)
 311             {
 312               match_count = 1;
 313               break;
 314             }
 315         }
 316     }
 317
 318   if (match_count == 1)
 319     {
 320       abfd->xvec = right_targ;          /* Change BFD's target permanently.  */
 321
 322       if (matching)
 323         free ((PTR) matching_vector);
 324
 325       return TRUE;                      /* File position has moved, BTW.  */
 326     }
 327
 328   abfd->xvec = save_targ;               /* Restore original target type.  */
 329   abfd->format = bfd_unknown;           /* Restore original format.  */
 330
 331   if (match_count == 0)
 332     {
 333       bfd_set_error (bfd_error_file_not_recognized);
 334
 335       if (matching)
 336         free ((PTR) matching_vector);
 337     }
 338   else
 339     {
 340       bfd_set_error (bfd_error_file_ambiguously_recognized);
 341
 342       if (matching)
 343         {
 344           *matching = (char **) matching_vector;
 345           matching_vector[match_count] = NULL;
 346           /* Return target names.  This is a little nasty.  Maybe we
 347              should do another bfd_malloc?  */
 348           while (--match_count >= 0)
 349             {
 350               const char *name = matching_vector[match_count]->name;
 351               *(const char **) &matching_vector[match_count] = name;
 352             }
 353         }
 354     }
 355
 356   return FALSE;
 357 }
 358
 359 /*
 360 FUNCTION
 361         bfd_set_format
 362
 363 SYNOPSIS
 364         bfd_boolean bfd_set_format(bfd *abfd, bfd_format format);
 365
 366 DESCRIPTION
 367         This function sets the file format of the BFD @var{abfd} to the
 368         format @var{format}. If the target set in the BFD does not
 369         support the format requested, the format is invalid, or the BFD
 370         is not open for writing, then an error occurs.
 371 */
 372
 373 bfd_boolean
 374 bfd_set_format (abfd, format)
 375      bfd *abfd;
 376      bfd_format format;
 377 {
 378   if (bfd_read_p (abfd)
 379       || (unsigned int) abfd->format >= (unsigned int) bfd_type_end)
 380     {
 381       bfd_set_error (bfd_error_invalid_operation);
 382       return FALSE;
 383     }
 384
 385   if (abfd->format != bfd_unknown)
 386     return abfd->format == format;
 387
 388   /* Presume the answer is yes.  */
 389   abfd->format = format;
 390
 391   if (!BFD_SEND_FMT (abfd, _bfd_set_format, (abfd)))
 392     {
 393       abfd->format = bfd_unknown;
 394       return FALSE;
 395     }
 396
 397   return TRUE;
 398 }
 399
 400 /*
 401 FUNCTION
 402         bfd_format_string
 403
 404 SYNOPSIS
 405         const char *bfd_format_string(bfd_format format);
 406
 407 DESCRIPTION
 408         Return a pointer to a const string
 409         <<invalid>>, <<object>>, <<archive>>, <<core>>, or <<unknown>>,
 410         depending upon the value of @var{format}.
 411 */
 412
 413 const char *
 414 bfd_format_string (format)
 415      bfd_format format;
 416 {
 417   if (((int)format <(int) bfd_unknown)
 418       || ((int)format >=(int) bfd_type_end))
 419     return "invalid";
 420
 421   switch (format)
 422     {
 423     case bfd_object:
 424       return "object";          /* Linker/assember/compiler output.  */
 425     case bfd_archive:
 426       return "archive";         /* Object archive file.  */
 427     case bfd_core:
 428       return "core";            /* Core dump.  */
 429     default:
 430       return "unknown";
 431     }
 432 }