bfd/format.c

   1 /* Generic BFD support for file formats.
   2    Copyright (C) 1990-1991 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., 675 Mass Ave, Cambridge, MA 02139, 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 char *matching_vector[];
  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 <<invalid_operation>> -
  74         if <<format>> is not one of <<bfd_object>>, <<bfd_archive>> or
  75         <<bfd_core>>.
  76
  77         o <<system_call_error>> -
  78         if an error occured during a read - even some file mismatches
  79         can cause system_call_errors.
  80
  81         o <<file_not_recognised>> -
  82         none of the backends recognised the file format.
  83
  84         o <<file_ambiguously_recognized>> -
  85         more than one backend recognised the file format.
  86
  87 */
  88
  89 boolean
  90 DEFUN(bfd_check_format,(abfd, format),
  91       bfd *abfd AND
  92       bfd_format format)
  93 {
  94   bfd_target **target, *save_targ, *right_targ;
  95   int match_count;
  96
  97   if (!bfd_read_p (abfd) ||
  98       ((int)(abfd->format) < (int)bfd_unknown) ||
  99       ((int)(abfd->format) >= (int)bfd_type_end)) {
 100     bfd_error = invalid_operation;
 101     return false;
 102   }
 103
 104   if (abfd->format != bfd_unknown)
 105     return (abfd->format == format)? true: false;
 106
 107
 108   /* Since the target type was defaulted, check them
 109      all in the hope that one will be uniquely recognized.  */
 110
 111   save_targ = abfd->xvec;
 112   match_count = 0;
 113   matching_vector[0] = NULL;
 114   right_targ = 0;
 115
 116
 117   /* presume the answer is yes */
 118   abfd->format = format;
 119
 120   /* If the target type was explicitly specified, just check that target.  */
 121
 122   if (!abfd->target_defaulted) {
 123     bfd_seek (abfd, (file_ptr)0, SEEK_SET);     /* rewind! */
 124
 125     right_targ = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
 126     if (right_targ) {
 127       abfd->xvec = right_targ;          /* Set the target as returned */
 128       return true;                      /* File position has moved, BTW */
 129     }
 130   }
 131
 132   for (target = target_vector; *target != NULL; target++) {
 133     bfd_target *temp;
 134
 135     abfd->xvec = *target;       /* Change BFD's target temporarily */
 136     bfd_seek (abfd, (file_ptr)0, SEEK_SET);
 137     /* If _bfd_check_format neglects to set bfd_error, assume wrong_format.
 138        We didn't used to even pay any attention to bfd_error, so I suspect
 139        that some _bfd_check_format might have this problem.  */
 140     bfd_error = wrong_format;
 141     temp = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
 142     if (temp) {                         /* This format checks out as ok! */
 143       right_targ = temp;
 144       matching_vector[match_count++] = temp->name;
 145       matching_vector[match_count] = NULL;
 146       /* If this is the default target, accept it, even if other targets
 147          might match.  People who want those other targets have to set
 148          the GNUTARGET variable.  */
 149       if (temp == default_vector[0])
 150         {
 151           match_count = 1;
 152           matching_vector[0] = temp->name;
 153           matching_vector[1] = NULL;
 154           break;
 155         }
 156 #ifdef GNU960
 157       /* Big- and little-endian b.out archives look the same, but it doesn't
 158        * matter: there is no difference in their headers, and member file byte
 159        * orders will (I hope) be handled appropriately by bfd.  Ditto for big
 160        * and little coff archives.  And the 4 coff/b.out object formats are
 161        * unambiguous.  So accept the first match we find.
 162        */
 163       break;
 164 #endif
 165     } else if (bfd_error != wrong_format) {
 166       abfd->xvec = save_targ;
 167       abfd->format = bfd_unknown;
 168       return false;
 169     }
 170   }
 171
 172   if (match_count == 1) {
 173     abfd->xvec = right_targ;            /* Change BFD's target permanently */
 174     return true;                        /* File position has moved, BTW */
 175   }
 176
 177   abfd->xvec = save_targ;               /* Restore original target type */
 178   abfd->format = bfd_unknown;           /* Restore original format */
 179   bfd_error = ((match_count == 0) ? file_not_recognized :
 180                file_ambiguously_recognized);
 181   return false;
 182 }
 183
 184 /*
 185 FUNCTION
 186         bfd_matching_formats
 187
 188 SYNOPSIS
 189         char **bfd_matching_formats();
 190
 191 DESCRIPTION
 192         If a call to <<bfd_check_format>> returns
 193         <<file_ambiguously_recognized>>, you can call this function
 194         afterward to return a NULL-terminated list of the names of
 195         the formats that matched.
 196         Then you can choose one and try again.  */
 197
 198 char **
 199 bfd_matching_formats ()
 200 {
 201   return &matching_vector[0];
 202 }
 203
 204 /*
 205 FUNCTION
 206         bfd_set_format
 207
 208 SYNOPSIS
 209         boolean bfd_set_format(bfd *abfd, bfd_format format);
 210
 211 DESCRIPTION
 212         This function sets the file format of the BFD @var{abfd} to the
 213         format @var{format}. If the target set in the BFD does not
 214         support the format requested, the format is invalid, or the BFD
 215         is not open for writing, then an error occurs.
 216
 217 */
 218
 219 boolean
 220 DEFUN(bfd_set_format,(abfd, format),
 221       bfd *abfd AND
 222       bfd_format format)
 223 {
 224
 225   if (bfd_read_p (abfd) ||
 226       ((int)abfd->format < (int)bfd_unknown) ||
 227       ((int)abfd->format >= (int)bfd_type_end)) {
 228     bfd_error = invalid_operation;
 229     return false;
 230   }
 231
 232   if (abfd->format != bfd_unknown)
 233     return (abfd->format == format) ? true:false;
 234
 235   /* presume the answer is yes */
 236   abfd->format = format;
 237
 238   if (!BFD_SEND_FMT (abfd, _bfd_set_format, (abfd))) {
 239     abfd->format = bfd_unknown;
 240     return false;
 241   }
 242
 243   return true;
 244 }
 245
 246
 247 /*
 248 FUNCTION
 249         bfd_format_string
 250
 251 SYNOPSIS
 252         CONST char *bfd_format_string(bfd_format format);
 253
 254 DESCRIPTION
 255         Return a pointer to a const string
 256         <<invalid>>, <<object>>, <<archive>>, <<core>>, or <<unknown>>,
 257         depending upon the value of @var{format}.
 258 */
 259
 260 CONST char *
 261 DEFUN(bfd_format_string,(format),
 262      bfd_format format)
 263 {
 264   if (((int)format <(int) bfd_unknown)
 265       || ((int)format >=(int) bfd_type_end))
 266     return "invalid";
 267
 268   switch (format) {
 269   case bfd_object:
 270     return "object";            /* linker/assember/compiler output */
 271   case bfd_archive:
 272     return "archive";           /* object archive file */
 273   case bfd_core:
 274     return "core";              /* core dump */
 275   default:
 276     return "unknown";
 277   }
 278 }