bfd/format.c

   1 /* Generic BFD support for file formats.
   2    Copyright (C) 1990, 91, 92, 93, 94, 95, 1999 Free Software Foundation, Inc.
   3    Written by Cygnus Support.
   4
   5 This file is part of BFD, the Binary File Descriptor library.
   6
   7 This program is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2 of the License, or
  10 (at your option) any later version.
  11
  12 This program is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with this program; if not, write to the Free Software
  19 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  20
  21 /*
  22 SECTION
  23         File formats
  24
  25         A format is a BFD concept of high level file contents type. The
  26         formats supported by BFD are:
  27
  28         o <<bfd_object>>
  29
  30         The BFD may contain data, symbols, relocations and debug info.
  31
  32         o <<bfd_archive>>
  33
  34         The BFD contains other BFDs and an optional index.
  35
  36         o <<bfd_core>>
  37
  38         The BFD contains the result of an executable core dump.
  39
  40 */
  41
  42 #include "bfd.h"
  43 #include "sysdep.h"
  44 #include "libbfd.h"
  45
  46 /* IMPORT from targets.c.  */
  47 extern const size_t _bfd_target_vector_entries;
  48
  49 /*
  50 FUNCTION
  51         bfd_check_format
  52
  53 SYNOPSIS
  54         boolean bfd_check_format(bfd *abfd, bfd_format format);
  55
  56 DESCRIPTION
  57         Verify if the file attached to the BFD @var{abfd} is compatible
  58         with the format @var{format} (i.e., one of <<bfd_object>>,
  59         <<bfd_archive>> or <<bfd_core>>).
  60
  61         If the BFD has been set to a specific target before the
  62         call, only the named target and format combination is
  63         checked. If the target has not been set, or has been set to
  64         <<default>>, then all the known target backends is
  65         interrogated to determine a match.  If the default target
  66         matches, it is used.  If not, exactly one target must recognize
  67         the file, or an error results.
  68
  69         The function returns <<true>> on success, otherwise <<false>>
  70         with one of the following error codes:
  71
  72         o <<bfd_error_invalid_operation>> -
  73         if <<format>> is not one of <<bfd_object>>, <<bfd_archive>> or
  74         <<bfd_core>>.
  75
  76         o <<bfd_error_system_call>> -
  77         if an error occured during a read - even some file mismatches
  78         can cause bfd_error_system_calls.
  79
  80         o <<file_not_recognised>> -
  81         none of the backends recognised the file format.
  82
  83         o <<bfd_error_file_ambiguously_recognized>> -
  84         more than one backend recognised the file format.
  85 */
  86
  87 boolean
  88 bfd_check_format (abfd, format)
  89      bfd *abfd;
  90      bfd_format format;
  91 {
  92   return bfd_check_format_matches (abfd, format, NULL);
  93 }
  94
  95 /*
  96 FUNCTION
  97         bfd_check_format_matches
  98
  99 SYNOPSIS
 100         boolean bfd_check_format_matches(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 boolean
 115 bfd_check_format_matches (abfd, format, matching)
 116      bfd *abfd;
 117      bfd_format format;
 118      char ***matching;
 119 {
 120   extern const bfd_target binary_vec;
 121   const bfd_target * const *target, *save_targ, *right_targ;
 122   char **matching_vector = NULL;
 123   int match_count;
 124
 125   if (!bfd_read_p (abfd) ||
 126       ((int)(abfd->format) < (int)bfd_unknown) ||
 127       ((int)(abfd->format) >= (int)bfd_type_end))
 128     {
 129       bfd_set_error (bfd_error_invalid_operation);
 130       return false;
 131     }
 132
 133   if (abfd->format != bfd_unknown)
 134     return (abfd->format == format)? true: false;
 135
 136   /* Since the target type was defaulted, check them
 137      all in the hope that one will be uniquely recognized.  */
 138   save_targ = abfd->xvec;
 139   match_count = 0;
 140
 141   if (matching)
 142     {
 143       matching_vector =
 144         (char **) bfd_malloc (sizeof (char *) *
 145                               (_bfd_target_vector_entries + 1));
 146       if (!matching_vector)
 147         return false;
 148       matching_vector[0] = NULL;
 149       *matching = matching_vector;
 150     }
 151
 152   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         return false;
 162
 163       right_targ = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
 164
 165       if (right_targ)
 166         {
 167           abfd->xvec = right_targ;      /* Set the target as returned.  */
 168
 169           if (matching)
 170             free (matching_vector);
 171
 172           return true;                  /* File position has moved, BTW.  */
 173         }
 174
 175       /* For a long time the code has dropped through to check all
 176          targets if the specified target was wrong.  I don't know why,
 177          and I'm reluctant to change it.  However, in the case of an
 178          archive, it can cause problems.  If the specified target does
 179          not permit archives (e.g., the binary target), then we should
 180          not allow some other target to recognize it as an archive, but
 181          should instead allow the specified target to recognize it as an
 182          object.  When I first made this change, it broke the PE target,
 183          because the specified pei-i386 target did not recognize the
 184          actual pe-i386 archive.  Since there may be other problems of
 185          this sort, I changed this test to check only for the binary
 186          target.  */
 187       if (format == bfd_archive && save_targ == &binary_vec)
 188         {
 189           abfd->xvec = save_targ;
 190           abfd->format = bfd_unknown;
 191
 192           if (matching)
 193             free (matching_vector);
 194
 195           bfd_set_error (bfd_error_file_not_recognized);
 196
 197           return false;
 198         }
 199     }
 200
 201   for (target = bfd_target_vector; *target != NULL; target++)
 202     {
 203       const bfd_target *temp;
 204
 205       if (*target == &binary_vec)
 206         continue;
 207
 208       abfd->xvec = *target;     /* Change BFD's target temporarily */
 209
 210       if (bfd_seek (abfd, (file_ptr)0, SEEK_SET) != 0)
 211         return false;
 212
 213       /* If _bfd_check_format neglects to set bfd_error, assume
 214          bfd_error_wrong_format.  We didn't used to even pay any
 215          attention to bfd_error, so I suspect that some
 216          _bfd_check_format might have this problem.  */
 217       bfd_set_error (bfd_error_wrong_format);
 218
 219       temp = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
 220
 221       if (temp)
 222         {               /* This format checks out as ok!  */
 223           right_targ = temp;
 224
 225           if (matching)
 226             {
 227               matching_vector[match_count] = temp->name;
 228               matching_vector[match_count + 1] = NULL;
 229             }
 230
 231           match_count++;
 232
 233           /* If this is the default target, accept it, even if other
 234              targets might match.  People who want those other targets
 235              have to set the GNUTARGET variable.  */
 236           if (temp == bfd_default_vector[0])
 237             {
 238               if (matching)
 239                 {
 240                   matching_vector[0] = temp->name;
 241                   matching_vector[1] = NULL;
 242                 }
 243               match_count = 1;
 244               break;
 245             }
 246 #ifdef GNU960
 247           /* Big- and little-endian b.out archives look the same, but it
 248              doesn't matter: there is no difference in their headers, and
 249              member file byte orders will (I hope) be handled appropriately
 250              by bfd.  Ditto for big and little coff archives.  And the 4
 251              coff/b.out object formats are unambiguous.  So accept the
 252              first match we find.  */
 253           break;
 254 #endif
 255         }
 256       else if (bfd_get_error () != bfd_error_wrong_format)
 257         {
 258           abfd->xvec = save_targ;
 259           abfd->format = bfd_unknown;
 260
 261           if (matching && bfd_get_error ()
 262               != bfd_error_file_ambiguously_recognized)
 263             free (matching_vector);
 264
 265           return false;
 266         }
 267     }
 268
 269   if (match_count == 1)
 270     {
 271       abfd->xvec = right_targ;          /* Change BFD's target permanently.  */
 272
 273       if (matching)
 274         free (matching_vector);
 275
 276       return true;                      /* File position has moved, BTW.  */
 277     }
 278
 279   abfd->xvec = save_targ;               /* Restore original target type.  */
 280   abfd->format = bfd_unknown;           /* Restore original format.  */
 281
 282   if (match_count == 0)
 283     {
 284       bfd_set_error (bfd_error_file_not_recognized);
 285
 286       if (matching)
 287         free (matching_vector);
 288     }
 289   else
 290     bfd_set_error (bfd_error_file_ambiguously_recognized);
 291
 292   return false;
 293 }
 294
 295 /*
 296 FUNCTION
 297         bfd_set_format
 298
 299 SYNOPSIS
 300         boolean bfd_set_format(bfd *abfd, bfd_format format);
 301
 302 DESCRIPTION
 303         This function sets the file format of the BFD @var{abfd} to the
 304         format @var{format}. If the target set in the BFD does not
 305         support the format requested, the format is invalid, or the BFD
 306         is not open for writing, then an error occurs.
 307 */
 308
 309 boolean
 310 bfd_set_format (abfd, format)
 311      bfd *abfd;
 312      bfd_format format;
 313 {
 314   if (bfd_read_p (abfd) ||
 315       ((int)abfd->format < (int)bfd_unknown) ||
 316       ((int)abfd->format >= (int)bfd_type_end))
 317     {
 318       bfd_set_error (bfd_error_invalid_operation);
 319       return false;
 320     }
 321
 322   if (abfd->format != bfd_unknown)
 323     return (abfd->format == format) ? true : false;
 324
 325   /* Presume the answer is yes.  */
 326   abfd->format = format;
 327
 328   if (!BFD_SEND_FMT (abfd, _bfd_set_format, (abfd)))
 329     {
 330       abfd->format = bfd_unknown;
 331       return false;
 332     }
 333
 334   return true;
 335 }
 336
 337 /*
 338 FUNCTION
 339         bfd_format_string
 340
 341 SYNOPSIS
 342         CONST char *bfd_format_string(bfd_format format);
 343
 344 DESCRIPTION
 345         Return a pointer to a const string
 346         <<invalid>>, <<object>>, <<archive>>, <<core>>, or <<unknown>>,
 347         depending upon the value of @var{format}.
 348 */
 349
 350 CONST char *
 351 bfd_format_string (format)
 352      bfd_format format;
 353 {
 354   if (((int)format <(int) bfd_unknown)
 355       || ((int)format >=(int) bfd_type_end))
 356     return "invalid";
 357
 358   switch (format)
 359     {
 360     case bfd_object:
 361       return "object";          /* Linker/assember/compiler output.  */
 362     case bfd_archive:
 363       return "archive";         /* Object archive file.  */
 364     case bfd_core:
 365       return "core";            /* Core dump.  */
 366     default:
 367       return "unknown";
 368     }
 369 }