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