bfd/format.c

   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.
   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., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, 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 (bfd *abfd, bfd_format format)
  90 {
  91   return bfd_check_format_matches (abfd, format, NULL);
  92 }
  93
  94 /*
  95 FUNCTION
  96         bfd_check_format_matches
  97
  98 SYNOPSIS
  99         bfd_boolean bfd_check_format_matches
 100           (bfd *abfd, bfd_format format, char ***matching);
 101
 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.
 109
 110         When done with the list that @var{matching} points to, the caller
 111         should free it.
 112 */
 113
 114 bfd_boolean
 115 bfd_check_format_matches (bfd *abfd, bfd_format format, char ***matching)
 116 {
 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;
 123
 124   if (!bfd_read_p (abfd)
 125       || (unsigned int) abfd->format >= (unsigned int) bfd_type_end)
 126     {
 127       bfd_set_error (bfd_error_invalid_operation);
 128       return FALSE;
 129     }
 130
 131   if (abfd->format != bfd_unknown)
 132     return abfd->format == format;
 133
 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;
 139
 140   if (matching)
 141     {
 142       bfd_size_type amt;
 143
 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;
 149     }
 150
 151   right_targ = 0;
 152   ar_right_targ = 0;
 153
 154   /* Presume the answer is yes.  */
 155   abfd->format = format;
 156
 157   /* If the target type was explicitly specified, just check that target.  */
 158   if (!abfd->target_defaulted)
 159     {
 160       if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0) /* rewind! */
 161         {
 162           if (matching)
 163             free (matching_vector);
 164           return FALSE;
 165         }
 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 (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 (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         {
 217           if (matching)
 218             free (matching_vector);
 219           return FALSE;
 220         }
 221
 222       /* If _bfd_check_format neglects to set bfd_error, assume
 223          bfd_error_wrong_format.  We didn't used to even pay any
 224          attention to bfd_error, so I suspect that some
 225          _bfd_check_format might have this problem.  */
 226       bfd_set_error (bfd_error_wrong_format);
 227
 228       temp = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
 229
 230       if (temp)
 231         {
 232           /* This format checks out as ok!  */
 233           right_targ = temp;
 234
 235           /* If this is the default target, accept it, even if other
 236              targets might match.  People who want those other targets
 237              have to set the GNUTARGET variable.  */
 238           if (temp == bfd_default_vector[0])
 239             {
 240               match_count = 1;
 241               break;
 242             }
 243
 244           if (matching)
 245             matching_vector[match_count] = temp;
 246
 247           match_count++;
 248         }
 249       else if ((err = bfd_get_error ()) == bfd_error_wrong_object_format
 250                || err == bfd_error_file_ambiguously_recognized)
 251         {
 252           /* An archive with objects of the wrong type, or an
 253              ambiguous match.  We want this target to match if we get
 254              no better matches.  */
 255           if (ar_right_targ != bfd_default_vector[0])
 256             ar_right_targ = *target;
 257           if (matching)
 258             matching_vector[ar_match_index] = *target;
 259           ar_match_index++;
 260         }
 261       else if (err != bfd_error_wrong_format)
 262         {
 263           abfd->xvec = save_targ;
 264           abfd->format = bfd_unknown;
 265
 266           if (matching)
 267             free (matching_vector);
 268
 269           return FALSE;
 270         }
 271     }
 272
 273   if (match_count == 0)
 274     {
 275       /* Try partial matches.  */
 276       right_targ = ar_right_targ;
 277
 278       if (right_targ == bfd_default_vector[0])
 279         {
 280           match_count = 1;
 281         }
 282       else
 283         {
 284           match_count = ar_match_index - _bfd_target_vector_entries;
 285
 286           if (matching && match_count > 1)
 287             memcpy (matching_vector,
 288                     matching_vector + _bfd_target_vector_entries,
 289                     sizeof (*matching_vector) * match_count);
 290         }
 291     }
 292
 293   if (match_count > 1
 294       && bfd_associated_vector != NULL
 295       && matching)
 296     {
 297       const bfd_target * const *assoc = bfd_associated_vector;
 298
 299       while ((right_targ = *assoc++) != NULL)
 300         {
 301           int i = match_count;
 302
 303           while (--i >= 0)
 304             if (matching_vector[i] == right_targ)
 305               break;
 306
 307           if (i >= 0)
 308             {
 309               match_count = 1;
 310               break;
 311             }
 312         }
 313     }
 314
 315   if (match_count == 1)
 316     {
 317       abfd->xvec = right_targ;          /* Change BFD's target permanently.  */
 318
 319       if (matching)
 320         free (matching_vector);
 321
 322       return TRUE;                      /* File position has moved, BTW.  */
 323     }
 324
 325   abfd->xvec = save_targ;               /* Restore original target type.  */
 326   abfd->format = bfd_unknown;           /* Restore original format.  */
 327
 328   if (match_count == 0)
 329     {
 330       bfd_set_error (bfd_error_file_not_recognized);
 331
 332       if (matching)
 333         free (matching_vector);
 334     }
 335   else
 336     {
 337       bfd_set_error (bfd_error_file_ambiguously_recognized);
 338
 339       if (matching)
 340         {
 341           *matching = (char **) matching_vector;
 342           matching_vector[match_count] = NULL;
 343           /* Return target names.  This is a little nasty.  Maybe we
 344              should do another bfd_malloc?  */
 345           while (--match_count >= 0)
 346             {
 347               const char *name = matching_vector[match_count]->name;
 348               *(const char **) &matching_vector[match_count] = name;
 349             }
 350         }
 351     }
 352
 353   return FALSE;
 354 }
 355
 356 /*
 357 FUNCTION
 358         bfd_set_format
 359
 360 SYNOPSIS
 361         bfd_boolean bfd_set_format (bfd *abfd, bfd_format format);
 362
 363 DESCRIPTION
 364         This function sets the file format of the BFD @var{abfd} to the
 365         format @var{format}. If the target set in the BFD does not
 366         support the format requested, the format is invalid, or the BFD
 367         is not open for writing, then an error occurs.
 368 */
 369
 370 bfd_boolean
 371 bfd_set_format (bfd *abfd, bfd_format format)
 372 {
 373   if (bfd_read_p (abfd)
 374       || (unsigned int) abfd->format >= (unsigned int) bfd_type_end)
 375     {
 376       bfd_set_error (bfd_error_invalid_operation);
 377       return FALSE;
 378     }
 379
 380   if (abfd->format != bfd_unknown)
 381     return abfd->format == format;
 382
 383   /* Presume the answer is yes.  */
 384   abfd->format = format;
 385
 386   if (!BFD_SEND_FMT (abfd, _bfd_set_format, (abfd)))
 387     {
 388       abfd->format = bfd_unknown;
 389       return FALSE;
 390     }
 391
 392   return TRUE;
 393 }
 394
 395 /*
 396 FUNCTION
 397         bfd_format_string
 398
 399 SYNOPSIS
 400         const char *bfd_format_string (bfd_format format);
 401
 402 DESCRIPTION
 403         Return a pointer to a const string
 404         <<invalid>>, <<object>>, <<archive>>, <<core>>, or <<unknown>>,
 405         depending upon the value of @var{format}.
 406 */
 407
 408 const char *
 409 bfd_format_string (bfd_format format)
 410 {
 411   if (((int) format < (int) bfd_unknown)
 412       || ((int) format >= (int) bfd_type_end))
 413     return "invalid";
 414
 415   switch (format)
 416     {
 417     case bfd_object:
 418       return "object";          /* Linker/assembler/compiler output.  */
 419     case bfd_archive:
 420       return "archive";         /* Object archive file.  */
 421     case bfd_core:
 422       return "core";            /* Core dump.  */
 423     default:
 424       return "unknown";
 425     }
 426 }