bfd/format.c

   1 /* Generic BFD support for file formats.
   2    Copyright 1990, 1991, 1992, 1993, 1994, 1995, 1999, 2000, 2001, 2002, 2003
   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 (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 #ifdef GNU960
 250           /* Big- and little-endian b.out archives look the same, but it
 251              doesn't matter: there is no difference in their headers, and
 252              member file byte orders will (I hope) be handled appropriately
 253              by bfd.  Ditto for big and little coff archives.  And the 4
 254              coff/b.out object formats are unambiguous.  So accept the
 255              first match we find.  */
 256           break;
 257 #endif
 258         }
 259       else if ((err = bfd_get_error ()) == bfd_error_wrong_object_format
 260                || err == bfd_error_file_ambiguously_recognized)
 261         {
 262           /* An archive with objects of the wrong type, or an
 263              ambiguous match.  We want this target to match if we get
 264              no better matches.  */
 265           if (ar_right_targ != bfd_default_vector[0])
 266             ar_right_targ = *target;
 267           if (matching)
 268             matching_vector[ar_match_index] = *target;
 269           ar_match_index++;
 270         }
 271       else if (err != bfd_error_wrong_format)
 272         {
 273           abfd->xvec = save_targ;
 274           abfd->format = bfd_unknown;
 275
 276           if (matching)
 277             free (matching_vector);
 278
 279           return FALSE;
 280         }
 281     }
 282
 283   if (match_count == 0)
 284     {
 285       /* Try partial matches.  */
 286       right_targ = ar_right_targ;
 287
 288       if (right_targ == bfd_default_vector[0])
 289         {
 290           match_count = 1;
 291         }
 292       else
 293         {
 294           match_count = ar_match_index - _bfd_target_vector_entries;
 295
 296           if (matching && match_count > 1)
 297             memcpy (matching_vector,
 298                     matching_vector + _bfd_target_vector_entries,
 299                     sizeof (*matching_vector) * match_count);
 300         }
 301     }
 302
 303   if (match_count > 1
 304       && bfd_associated_vector != NULL
 305       && matching)
 306     {
 307       const bfd_target * const *assoc = bfd_associated_vector;
 308
 309       while ((right_targ = *assoc++) != NULL)
 310         {
 311           int i = match_count;
 312
 313           while (--i >= 0)
 314             if (matching_vector[i] == right_targ)
 315               break;
 316
 317           if (i >= 0)
 318             {
 319               match_count = 1;
 320               break;
 321             }
 322         }
 323     }
 324
 325   if (match_count == 1)
 326     {
 327       abfd->xvec = right_targ;          /* Change BFD's target permanently.  */
 328
 329       if (matching)
 330         free (matching_vector);
 331
 332       return TRUE;                      /* File position has moved, BTW.  */
 333     }
 334
 335   abfd->xvec = save_targ;               /* Restore original target type.  */
 336   abfd->format = bfd_unknown;           /* Restore original format.  */
 337
 338   if (match_count == 0)
 339     {
 340       bfd_set_error (bfd_error_file_not_recognized);
 341
 342       if (matching)
 343         free (matching_vector);
 344     }
 345   else
 346     {
 347       bfd_set_error (bfd_error_file_ambiguously_recognized);
 348
 349       if (matching)
 350         {
 351           *matching = (char **) matching_vector;
 352           matching_vector[match_count] = NULL;
 353           /* Return target names.  This is a little nasty.  Maybe we
 354              should do another bfd_malloc?  */
 355           while (--match_count >= 0)
 356             {
 357               const char *name = matching_vector[match_count]->name;
 358               *(const char **) &matching_vector[match_count] = name;
 359             }
 360         }
 361     }
 362
 363   return FALSE;
 364 }
 365
 366 /*
 367 FUNCTION
 368         bfd_set_format
 369
 370 SYNOPSIS
 371         bfd_boolean bfd_set_format (bfd *abfd, bfd_format format);
 372
 373 DESCRIPTION
 374         This function sets the file format of the BFD @var{abfd} to the
 375         format @var{format}. If the target set in the BFD does not
 376         support the format requested, the format is invalid, or the BFD
 377         is not open for writing, then an error occurs.
 378 */
 379
 380 bfd_boolean
 381 bfd_set_format (bfd *abfd, bfd_format format)
 382 {
 383   if (bfd_read_p (abfd)
 384       || (unsigned int) abfd->format >= (unsigned int) bfd_type_end)
 385     {
 386       bfd_set_error (bfd_error_invalid_operation);
 387       return FALSE;
 388     }
 389
 390   if (abfd->format != bfd_unknown)
 391     return abfd->format == format;
 392
 393   /* Presume the answer is yes.  */
 394   abfd->format = format;
 395
 396   if (!BFD_SEND_FMT (abfd, _bfd_set_format, (abfd)))
 397     {
 398       abfd->format = bfd_unknown;
 399       return FALSE;
 400     }
 401
 402   return TRUE;
 403 }
 404
 405 /*
 406 FUNCTION
 407         bfd_format_string
 408
 409 SYNOPSIS
 410         const char *bfd_format_string (bfd_format format);
 411
 412 DESCRIPTION
 413         Return a pointer to a const string
 414         <<invalid>>, <<object>>, <<archive>>, <<core>>, or <<unknown>>,
 415         depending upon the value of @var{format}.
 416 */
 417
 418 const char *
 419 bfd_format_string (bfd_format format)
 420 {
 421   if (((int) format < (int) bfd_unknown)
 422       || ((int) format >= (int) bfd_type_end))
 423     return "invalid";
 424
 425   switch (format)
 426     {
 427     case bfd_object:
 428       return "object";          /* Linker/assember/compiler output.  */
 429     case bfd_archive:
 430       return "archive";         /* Object archive file.  */
 431     case bfd_core:
 432       return "core";            /* Core dump.  */
 433     default:
 434       return "unknown";
 435     }
 436 }