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 /*doc*
  22 @section File Formats
  23 A format is a BFD concept of high level file contents. The
  24 formats supported by BFD are:
  25 @table @code
  26 @item bfd_object
  27 The BFD may contain data, symbols, relocations and debug info.
  28 @item bfd_archive
  29 The BFD contains other BFDs and an optional index.
  30 @item bfd_core
  31 The BFD contains the result of an executable core dump.
  32 @end table
  33 */
  34 #include "sysdep.h"
  35 #include "bfd.h"
  36 #include "libbfd.h"
  37
  38
  39 extern bfd_target *target_vector[];
  40 extern bfd_target *default_vector[];
  41
  42
  43 /*proto*
  44 *i bfd_check_format
  45 This routine is supplied a BFD and a format. It attempts to verify if
  46 the file attatched to the BFD is indeed compatible with the format
  47 specified (ie, one of @code{bfd_object}, @code{bfd_archive} or
  48 @code{bfd_core}).
  49
  50 If the BFD has been set to a specific @var{target} before the call,
  51 only the named target and format combination will be checked. If the
  52 target has not been set, or has been set to @code{default} then all
  53 the known target backends will be interrogated to determine a match.
  54
  55 The function returns @code{true} on success, otherwise @code{false}
  56 with one of the following error codes:
  57 @table @code
  58 @item
  59 invalid_operation
  60 if @code{format} is not one of @code{bfd_object}, @code{bfd_archive}
  61 or @code{bfd_core}.
  62 @item system_call_error
  63 if an error occured during a read -  even some file mismatches can
  64 cause system_call_errros
  65 @item file_not_recognised
  66 none of the backends recognised the file format
  67 @item file_ambiguously_recognized
  68 more than one backend recognised the file format.
  69 @end table
  70 *; PROTO(boolean, bfd_check_format, (bfd *abfd, bfd_format format));
  71 *-*/
  72
  73 boolean
  74 DEFUN(bfd_check_format,(abfd, format),
  75       bfd *abfd AND
  76       bfd_format format)
  77 {
  78   bfd_target **target, *save_targ, *right_targ;
  79   int match_count;
  80
  81   if (!bfd_read_p (abfd) ||
  82       ((int)(abfd->format) < (int)bfd_unknown) ||
  83       ((int)(abfd->format) >= (int)bfd_type_end)) {
  84     bfd_error = invalid_operation;
  85     return false;
  86   }
  87
  88   if (abfd->format != bfd_unknown)
  89     return (abfd->format == format)? true: false;
  90
  91   /* presume the answer is yes */
  92   abfd->format = format;
  93
  94   /* If the target type was explicitly specified, just check that target.  */
  95
  96   if (!abfd->target_defaulted) {
  97     bfd_seek (abfd, (file_ptr)0, SEEK_SET);     /* rewind! */
  98
  99     right_targ = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
 100     if (right_targ) {
 101       abfd->xvec = right_targ;          /* Set the target as returned */
 102       return true;                      /* File position has moved, BTW */
 103     }
 104     abfd->format = bfd_unknown;
 105     return false;                       /* Specified target is not right */
 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   right_targ = 0;
 114
 115   for (target = target_vector; *target != NULL; target++) {
 116     bfd_target *temp;
 117
 118     abfd->xvec = *target;       /* Change BFD's target temporarily */
 119     bfd_seek (abfd, (file_ptr)0, SEEK_SET);
 120     temp = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
 121     if (temp) {                         /* This format checks out as ok! */
 122       right_targ = temp;
 123       match_count++;
 124       /* If this is the default target, accept it, even if other targets
 125          might match.  People who want those other targets have to set
 126          the GNUTARGET variable.  */
 127       if (temp == default_vector[0])
 128         break;
 129 #ifdef GNU960
 130       /* Big- and little-endian b.out archives look the same, but it doesn't
 131        * matter: there is no difference in their headers, and member file byte
 132        * orders will (I hope) be handled appropriately by bfd.  Ditto for big
 133        * and little coff archives.  And the 4 coff/b.out object formats are
 134        * unambiguous.  So accept the first match we find.
 135        */
 136       break;
 137 #endif
 138     }
 139   }
 140
 141   if (match_count == 1) {
 142     abfd->xvec = right_targ;            /* Change BFD's target permanently */
 143     return true;                        /* File position has moved, BTW */
 144   }
 145
 146   abfd->xvec = save_targ;               /* Restore original target type */
 147   abfd->format = bfd_unknown;           /* Restore original format */
 148   bfd_error = ((match_count == 0) ? file_not_recognized :
 149                file_ambiguously_recognized);
 150   return false;
 151 }
 152 /*proto*
 153 *i bfd_set_format
 154 This function sets the file format of the supplied BFD to the format
 155 requested. If the target set in the BFD does not support the format
 156 requested, the format is illegal or the BFD is not open for writing
 157 than an error occurs.
 158 *; PROTO(boolean,bfd_set_format,(bfd *, bfd_format));
 159 *-*/
 160 boolean
 161 DEFUN(bfd_set_format,(abfd, format),
 162       bfd *abfd AND
 163       bfd_format format)
 164 {
 165
 166   if (bfd_read_p (abfd) ||
 167       ((int)abfd->format < (int)bfd_unknown) ||
 168       ((int)abfd->format >= (int)bfd_type_end)) {
 169     bfd_error = invalid_operation;
 170     return false;
 171   }
 172
 173   if (abfd->format != bfd_unknown)
 174     return (abfd->format == format) ? true:false;
 175
 176   /* presume the answer is yes */
 177   abfd->format = format;
 178
 179   if (!BFD_SEND_FMT (abfd, _bfd_set_format, (abfd))) {
 180     abfd->format = bfd_unknown;
 181     return false;
 182   }
 183
 184   return true;
 185 }
 186
 187
 188 /*proto*
 189 *i bfd_format_string
 190 This function takes one argument, and enumerated type (bfd_format) and
 191 returns a pointer to a const string "invalid", "object", "archive",
 192 "core" or "unknown" depending upon the value of the enumeration.
 193 *; PROTO(CONST char *, bfd_format_string, (bfd_format));
 194 *-*/
 195
 196 CONST char *
 197 DEFUN(bfd_format_string,(format),
 198      bfd_format format)
 199 {
 200   if (((int)format <(int) bfd_unknown)
 201       || ((int)format >=(int) bfd_type_end))
 202     return "invalid";
 203
 204   switch (format) {
 205   case bfd_object:
 206     return "object";            /* linker/assember/compiler output */
 207   case bfd_archive:
 208     return "archive";           /* object archive file */
 209   case bfd_core:
 210     return "core";              /* core dump */
 211   default:
 212     return "unknown";
 213   }
 214 }