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
  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         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 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         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 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, *save_targ, *right_targ;
 123   char **matching_vector = NULL;
 124   int match_count;
 125
 126   if (!bfd_read_p (abfd) ||
 127       ((int)(abfd->format) < (int)bfd_unknown) ||
 128       ((int)(abfd->format) >= (int)bfd_type_end))
 129     {
 130       bfd_set_error (bfd_error_invalid_operation);
 131       return false;
 132     }
 133
 134   if (abfd->format != bfd_unknown)
 135     return (abfd->format == format)? true: false;
 136
 137   /* Since the target type was defaulted, check them
 138      all in the hope that one will be uniquely recognized.  */
 139   save_targ = abfd->xvec;
 140   match_count = 0;
 141
 142   if (matching)
 143     {
 144       matching_vector =
 145         (char **) bfd_malloc (sizeof (char *) *
 146                               (_bfd_target_vector_entries + 1));
 147       if (!matching_vector)
 148         return false;
 149       matching_vector[0] = NULL;
 150       *matching = matching_vector;
 151     }
 152
 153   right_targ = 0;
 154
 155   /* Presume the answer is yes.  */
 156   abfd->format = format;
 157
 158   /* If the target type was explicitly specified, just check that target.  */
 159   if (!abfd->target_defaulted)
 160     {
 161       if (bfd_seek (abfd, (file_ptr)0, SEEK_SET) != 0)  /* rewind! */
 162         return false;
 163
 164       right_targ = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
 165
 166       if (right_targ)
 167         {
 168           abfd->xvec = right_targ;      /* Set the target as returned.  */
 169
 170           if (matching)
 171             free (matching_vector);
 172
 173           return true;                  /* File position has moved, BTW.  */
 174         }
 175
 176       /* For a long time the code has dropped through to check all
 177          targets if the specified target was wrong.  I don't know why,
 178          and I'm reluctant to change it.  However, in the case of an
 179          archive, it can cause problems.  If the specified target does
 180          not permit archives (e.g., the binary target), then we should
 181          not allow some other target to recognize it as an archive, but
 182          should instead allow the specified target to recognize it as an
 183          object.  When I first made this change, it broke the PE target,
 184          because the specified pei-i386 target did not recognize the
 185          actual pe-i386 archive.  Since there may be other problems of
 186          this sort, I changed this test to check only for the binary
 187          target.  */
 188       if (format == bfd_archive && save_targ == &binary_vec)
 189         {
 190           abfd->xvec = save_targ;
 191           abfd->format = bfd_unknown;
 192
 193           if (matching)
 194             free (matching_vector);
 195
 196           bfd_set_error (bfd_error_file_not_recognized);
 197
 198           return false;
 199         }
 200     }
 201
 202   for (target = bfd_target_vector; *target != NULL; target++)
 203     {
 204       const bfd_target *temp;
 205
 206       if (*target == &binary_vec)
 207         continue;
 208
 209       abfd->xvec = *target;     /* Change BFD's target temporarily */
 210
 211       if (bfd_seek (abfd, (file_ptr)0, SEEK_SET) != 0)
 212         return false;
 213
 214       /* If _bfd_check_format neglects to set bfd_error, assume
 215          bfd_error_wrong_format.  We didn't used to even pay any
 216          attention to bfd_error, so I suspect that some
 217          _bfd_check_format might have this problem.  */
 218       bfd_set_error (bfd_error_wrong_format);
 219
 220       temp = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
 221
 222       if (temp)
 223         {               /* This format checks out as ok!  */
 224           right_targ = temp;
 225
 226           if (matching)
 227             {
 228               matching_vector[match_count] = temp->name;
 229               matching_vector[match_count + 1] = NULL;
 230             }
 231
 232           match_count++;
 233
 234           /* If this is the default target, accept it, even if other
 235              targets might match.  People who want those other targets
 236              have to set the GNUTARGET variable.  */
 237           if (temp == bfd_default_vector[0])
 238             {
 239               if (matching)
 240                 {
 241                   matching_vector[0] = temp->name;
 242                   matching_vector[1] = NULL;
 243                 }
 244               match_count = 1;
 245               break;
 246             }
 247 #ifdef GNU960
 248           /* Big- and little-endian b.out archives look the same, but it
 249              doesn't matter: there is no difference in their headers, and
 250              member file byte orders will (I hope) be handled appropriately
 251              by bfd.  Ditto for big and little coff archives.  And the 4
 252              coff/b.out object formats are unambiguous.  So accept the
 253              first match we find.  */
 254           break;
 255 #endif
 256         }
 257       else if (bfd_get_error () != bfd_error_wrong_format)
 258         {
 259           abfd->xvec = save_targ;
 260           abfd->format = bfd_unknown;
 261
 262           if (matching && bfd_get_error ()
 263               != bfd_error_file_ambiguously_recognized)
 264             free (matching_vector);
 265
 266           return false;
 267         }
 268     }
 269
 270   if (match_count == 1)
 271     {
 272       abfd->xvec = right_targ;          /* Change BFD's target permanently.  */
 273
 274       if (matching)
 275         free (matching_vector);
 276
 277       return true;                      /* File position has moved, BTW.  */
 278     }
 279
 280   abfd->xvec = save_targ;               /* Restore original target type.  */
 281   abfd->format = bfd_unknown;           /* Restore original format.  */
 282
 283   if (match_count == 0)
 284     {
 285       bfd_set_error (bfd_error_file_not_recognized);
 286
 287       if (matching)
 288         free (matching_vector);
 289     }
 290   else
 291     bfd_set_error (bfd_error_file_ambiguously_recognized);
 292
 293   return false;
 294 }
 295
 296 /*
 297 FUNCTION
 298         bfd_set_format
 299
 300 SYNOPSIS
 301         boolean bfd_set_format(bfd *abfd, bfd_format format);
 302
 303 DESCRIPTION
 304         This function sets the file format of the BFD @var{abfd} to the
 305         format @var{format}. If the target set in the BFD does not
 306         support the format requested, the format is invalid, or the BFD
 307         is not open for writing, then an error occurs.
 308 */
 309
 310 boolean
 311 bfd_set_format (abfd, format)
 312      bfd *abfd;
 313      bfd_format format;
 314 {
 315   if (bfd_read_p (abfd) ||
 316       ((int)abfd->format < (int)bfd_unknown) ||
 317       ((int)abfd->format >= (int)bfd_type_end))
 318     {
 319       bfd_set_error (bfd_error_invalid_operation);
 320       return false;
 321     }
 322
 323   if (abfd->format != bfd_unknown)
 324     return (abfd->format == format) ? true : false;
 325
 326   /* Presume the answer is yes.  */
 327   abfd->format = format;
 328
 329   if (!BFD_SEND_FMT (abfd, _bfd_set_format, (abfd)))
 330     {
 331       abfd->format = bfd_unknown;
 332       return false;
 333     }
 334
 335   return true;
 336 }
 337
 338
 339 /*
 340 FUNCTION
 341         bfd_format_string
 342
 343 SYNOPSIS
 344         CONST char *bfd_format_string(bfd_format format);
 345
 346 DESCRIPTION
 347         Return a pointer to a const string
 348         <<invalid>>, <<object>>, <<archive>>, <<core>>, or <<unknown>>,
 349         depending upon the value of @var{format}.
 350 */
 351
 352 CONST char *
 353 bfd_format_string (format)
 354      bfd_format format;
 355 {
 356   if (((int)format <(int) bfd_unknown)
 357       || ((int)format >=(int) bfd_type_end))
 358     return "invalid";
 359
 360   switch (format)
 361     {
 362     case bfd_object:
 363       return "object";          /* Linker/assember/compiler output.  */
 364     case bfd_archive:
 365       return "archive";         /* Object archive file.  */
 366     case bfd_core:
 367       return "core";            /* Core dump.  */
 368     default:
 369       return "unknown";
 370     }
 371 }