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         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, *ar_right_targ;
 123   char **matching_vector = NULL;
 124   int match_count;
 125   int ar_match_index;
 126
 127   if (!bfd_read_p (abfd)
 128       || (unsigned int) abfd->format >= (unsigned 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 (boolean) (abfd->format == format);
 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   ar_match_index = _bfd_target_vector_entries;
 142
 143   if (matching)
 144     {
 145       bfd_size_type amt;
 146
 147       *matching = NULL;
 148       amt = sizeof (char *) * 2 * _bfd_target_vector_entries;
 149       matching_vector = (char **) bfd_malloc (amt);
 150       if (!matching_vector)
 151         return false;
 152     }
 153
 154   right_targ = 0;
 155   ar_right_targ = 0;
 156
 157   /* Presume the answer is yes.  */
 158   abfd->format = format;
 159
 160   /* If the target type was explicitly specified, just check that target.  */
 161   if (!abfd->target_defaulted)
 162     {
 163       if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0) /* rewind! */
 164         return false;
 165
 166       right_targ = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
 167
 168       if (right_targ)
 169         {
 170           abfd->xvec = right_targ;      /* Set the target as returned.  */
 171
 172           if (matching)
 173             free (matching_vector);
 174
 175           return true;                  /* File position has moved, BTW.  */
 176         }
 177
 178       /* For a long time the code has dropped through to check all
 179          targets if the specified target was wrong.  I don't know why,
 180          and I'm reluctant to change it.  However, in the case of an
 181          archive, it can cause problems.  If the specified target does
 182          not permit archives (e.g., the binary target), then we should
 183          not allow some other target to recognize it as an archive, but
 184          should instead allow the specified target to recognize it as an
 185          object.  When I first made this change, it broke the PE target,
 186          because the specified pei-i386 target did not recognize the
 187          actual pe-i386 archive.  Since there may be other problems of
 188          this sort, I changed this test to check only for the binary
 189          target.  */
 190       if (format == bfd_archive && save_targ == &binary_vec)
 191         {
 192           abfd->xvec = save_targ;
 193           abfd->format = bfd_unknown;
 194
 195           if (matching)
 196             free (matching_vector);
 197
 198           bfd_set_error (bfd_error_file_not_recognized);
 199
 200           return false;
 201         }
 202     }
 203
 204   for (target = bfd_target_vector; *target != NULL; target++)
 205     {
 206       const bfd_target *temp;
 207       bfd_error_type err;
 208
 209       if (*target == &binary_vec)
 210         continue;
 211
 212       abfd->xvec = *target;     /* Change BFD's target temporarily */
 213
 214       if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0)
 215         return false;
 216
 217       /* If _bfd_check_format neglects to set bfd_error, assume
 218          bfd_error_wrong_format.  We didn't used to even pay any
 219          attention to bfd_error, so I suspect that some
 220          _bfd_check_format might have this problem.  */
 221       bfd_set_error (bfd_error_wrong_format);
 222
 223       temp = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
 224
 225       if (temp)
 226         {               /* This format checks out as ok!  */
 227           right_targ = temp;
 228
 229           /* If this is the default target, accept it, even if other
 230              targets might match.  People who want those other targets
 231              have to set the GNUTARGET variable.  */
 232           if (temp == bfd_default_vector[0])
 233             {
 234               match_count = 1;
 235               break;
 236             }
 237
 238           if (matching)
 239             matching_vector[match_count] = temp->name;
 240
 241           match_count++;
 242
 243 #ifdef GNU960
 244           /* Big- and little-endian b.out archives look the same, but it
 245              doesn't matter: there is no difference in their headers, and
 246              member file byte orders will (I hope) be handled appropriately
 247              by bfd.  Ditto for big and little coff archives.  And the 4
 248              coff/b.out object formats are unambiguous.  So accept the
 249              first match we find.  */
 250           break;
 251 #endif
 252         }
 253       else if ((err = bfd_get_error ()) == bfd_error_wrong_object_format
 254                || err == bfd_error_file_ambiguously_recognized)
 255         {
 256           /* An archive with objects of the wrong type, or an
 257              ambiguous match.  We want this target to match if we get
 258              no better matches.  */
 259           if (ar_right_targ != bfd_default_vector[0])
 260             ar_right_targ = *target;
 261           if (matching)
 262             matching_vector[ar_match_index] = (*target)->name;
 263           ar_match_index++;
 264         }
 265       else if (err != bfd_error_wrong_format)
 266         {
 267           abfd->xvec = save_targ;
 268           abfd->format = bfd_unknown;
 269
 270           if (matching)
 271             free (matching_vector);
 272
 273           return false;
 274         }
 275     }
 276
 277   if (match_count == 0)
 278     {
 279       /* Try partial matches.  */
 280       right_targ = ar_right_targ;
 281       if (right_targ == bfd_default_vector[0])
 282         {
 283           match_count = 1;
 284         }
 285       else
 286         {
 287           match_count = ar_match_index - _bfd_target_vector_entries;
 288           if (matching && match_count > 1)
 289             {
 290               memcpy (matching_vector,
 291                       matching_vector + _bfd_target_vector_entries,
 292                       sizeof (char *) * match_count);
 293             }
 294         }
 295     }
 296
 297   if (match_count == 1)
 298     {
 299       abfd->xvec = right_targ;          /* Change BFD's target permanently.  */
 300
 301       if (matching)
 302         free (matching_vector);
 303
 304       return true;                      /* File position has moved, BTW.  */
 305     }
 306
 307   abfd->xvec = save_targ;               /* Restore original target type.  */
 308   abfd->format = bfd_unknown;           /* Restore original format.  */
 309
 310   if (match_count == 0)
 311     {
 312       bfd_set_error (bfd_error_file_not_recognized);
 313
 314       if (matching)
 315         free (matching_vector);
 316     }
 317   else
 318     {
 319       bfd_set_error (bfd_error_file_ambiguously_recognized);
 320
 321       if (matching)
 322         {
 323           *matching = matching_vector;
 324           matching_vector[match_count] = NULL;
 325         }
 326     }
 327
 328   return false;
 329 }
 330
 331 /*
 332 FUNCTION
 333         bfd_set_format
 334
 335 SYNOPSIS
 336         boolean bfd_set_format(bfd *abfd, bfd_format format);
 337
 338 DESCRIPTION
 339         This function sets the file format of the BFD @var{abfd} to the
 340         format @var{format}. If the target set in the BFD does not
 341         support the format requested, the format is invalid, or the BFD
 342         is not open for writing, then an error occurs.
 343 */
 344
 345 boolean
 346 bfd_set_format (abfd, format)
 347      bfd *abfd;
 348      bfd_format format;
 349 {
 350   if (bfd_read_p (abfd)
 351       || (unsigned int) abfd->format >= (unsigned int) bfd_type_end)
 352     {
 353       bfd_set_error (bfd_error_invalid_operation);
 354       return false;
 355     }
 356
 357   if (abfd->format != bfd_unknown)
 358     return (boolean) (abfd->format == format);
 359
 360   /* Presume the answer is yes.  */
 361   abfd->format = format;
 362
 363   if (!BFD_SEND_FMT (abfd, _bfd_set_format, (abfd)))
 364     {
 365       abfd->format = bfd_unknown;
 366       return false;
 367     }
 368
 369   return true;
 370 }
 371
 372 /*
 373 FUNCTION
 374         bfd_format_string
 375
 376 SYNOPSIS
 377         const char *bfd_format_string(bfd_format format);
 378
 379 DESCRIPTION
 380         Return a pointer to a const string
 381         <<invalid>>, <<object>>, <<archive>>, <<core>>, or <<unknown>>,
 382         depending upon the value of @var{format}.
 383 */
 384
 385 const char *
 386 bfd_format_string (format)
 387      bfd_format format;
 388 {
 389   if (((int)format <(int) bfd_unknown)
 390       || ((int)format >=(int) bfd_type_end))
 391     return "invalid";
 392
 393   switch (format)
 394     {
 395     case bfd_object:
 396       return "object";          /* Linker/assember/compiler output.  */
 397     case bfd_archive:
 398       return "archive";         /* Object archive file.  */
 399     case bfd_core:
 400       return "core";            /* Core dump.  */
 401     default:
 402       return "unknown";
 403     }
 404 }