bfd/format.c

   1 /* Generic BFD support for file formats.
   2    Copyright (C) 1990, 91, 92, 93, 94 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 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 <<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 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 <<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   bfd_target **target, *save_targ, *right_targ;
 122   char **matching_vector;
 123   int match_count;
 124
 125   if (!bfd_read_p (abfd) ||
 126       ((int)(abfd->format) < (int)bfd_unknown) ||
 127       ((int)(abfd->format) >= (int)bfd_type_end)) {
 128     bfd_error = invalid_operation;
 129     return false;
 130   }
 131
 132   if (abfd->format != bfd_unknown)
 133     return (abfd->format == format)? true: false;
 134
 135
 136   /* Since the target type was defaulted, check them
 137      all in the hope that one will be uniquely recognized.  */
 138
 139   save_targ = abfd->xvec;
 140   match_count = 0;
 141   if (matching)
 142     {
 143       *matching = matching_vector =
 144         (char **) bfd_xmalloc_by_size_t (sizeof (char *) *
 145                                          (_bfd_target_vector_entries + 1));
 146       matching_vector[0] = NULL;
 147     }
 148   right_targ = 0;
 149
 150
 151   /* presume the answer is yes */
 152   abfd->format = format;
 153
 154   /* If the target type was explicitly specified, just check that target.  */
 155
 156   if (!abfd->target_defaulted) {
 157     bfd_seek (abfd, (file_ptr)0, SEEK_SET);     /* rewind! */
 158
 159     right_targ = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
 160     if (right_targ) {
 161       abfd->xvec = right_targ;          /* Set the target as returned */
 162       if (matching)
 163         free (matching_vector);
 164       return true;                      /* File position has moved, BTW */
 165     }
 166   }
 167
 168   for (target = bfd_target_vector; *target != NULL; target++) {
 169     bfd_target *temp;
 170
 171     abfd->xvec = *target;       /* Change BFD's target temporarily */
 172     bfd_seek (abfd, (file_ptr)0, SEEK_SET);
 173     /* If _bfd_check_format neglects to set bfd_error, assume wrong_format.
 174        We didn't used to even pay any attention to bfd_error, so I suspect
 175        that some _bfd_check_format might have this problem.  */
 176     bfd_error = wrong_format;
 177     temp = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
 178     if (temp) {                         /* This format checks out as ok! */
 179       right_targ = temp;
 180       if (matching)
 181         {
 182           matching_vector[match_count] = temp->name;
 183           matching_vector[match_count + 1] = NULL;
 184         }
 185       match_count++;
 186       /* If this is the default target, accept it, even if other targets
 187          might match.  People who want those other targets have to set
 188          the GNUTARGET variable.  */
 189       if (temp == bfd_default_vector[0])
 190         {
 191           if (matching)
 192             {
 193               matching_vector[0] = temp->name;
 194               matching_vector[1] = NULL;
 195             }
 196           match_count = 1;
 197           break;
 198         }
 199 #ifdef GNU960
 200       /* Big- and little-endian b.out archives look the same, but it doesn't
 201        * matter: there is no difference in their headers, and member file byte
 202        * orders will (I hope) be handled appropriately by bfd.  Ditto for big
 203        * and little coff archives.  And the 4 coff/b.out object formats are
 204        * unambiguous.  So accept the first match we find.
 205        */
 206       break;
 207 #endif
 208     } else if (bfd_error != wrong_format) {
 209       abfd->xvec = save_targ;
 210       abfd->format = bfd_unknown;
 211       if (matching && bfd_error != file_ambiguously_recognized)
 212         free (matching_vector);
 213       return false;
 214     }
 215   }
 216
 217   if (match_count == 1) {
 218     abfd->xvec = right_targ;            /* Change BFD's target permanently */
 219     if (matching)
 220       free (matching_vector);
 221     return true;                        /* File position has moved, BTW */
 222   }
 223
 224   abfd->xvec = save_targ;               /* Restore original target type */
 225   abfd->format = bfd_unknown;           /* Restore original format */
 226   if (match_count == 0)
 227     {
 228       bfd_error = file_not_recognized;
 229       if (matching)
 230         free (matching_vector);
 231     }
 232   else
 233     bfd_error = file_ambiguously_recognized;
 234   return false;
 235 }
 236
 237 /*
 238 FUNCTION
 239         bfd_set_format
 240
 241 SYNOPSIS
 242         boolean bfd_set_format(bfd *abfd, bfd_format format);
 243
 244 DESCRIPTION
 245         This function sets the file format of the BFD @var{abfd} to the
 246         format @var{format}. If the target set in the BFD does not
 247         support the format requested, the format is invalid, or the BFD
 248         is not open for writing, then an error occurs.
 249
 250 */
 251
 252 boolean
 253 bfd_set_format (abfd, format)
 254      bfd *abfd;
 255      bfd_format format;
 256 {
 257
 258   if (bfd_read_p (abfd) ||
 259       ((int)abfd->format < (int)bfd_unknown) ||
 260       ((int)abfd->format >= (int)bfd_type_end)) {
 261     bfd_error = invalid_operation;
 262     return false;
 263   }
 264
 265   if (abfd->format != bfd_unknown)
 266     return (abfd->format == format) ? true:false;
 267
 268   /* presume the answer is yes */
 269   abfd->format = format;
 270
 271   if (!BFD_SEND_FMT (abfd, _bfd_set_format, (abfd))) {
 272     abfd->format = bfd_unknown;
 273     return false;
 274   }
 275
 276   return true;
 277 }
 278
 279
 280 /*
 281 FUNCTION
 282         bfd_format_string
 283
 284 SYNOPSIS
 285         CONST char *bfd_format_string(bfd_format format);
 286
 287 DESCRIPTION
 288         Return a pointer to a const string
 289         <<invalid>>, <<object>>, <<archive>>, <<core>>, or <<unknown>>,
 290         depending upon the value of @var{format}.
 291 */
 292
 293 CONST char *
 294 bfd_format_string (format)
 295      bfd_format format;
 296 {
 297   if (((int)format <(int) bfd_unknown)
 298       || ((int)format >=(int) bfd_type_end))
 299     return "invalid";
 300
 301   switch (format) {
 302   case bfd_object:
 303     return "object";            /* linker/assember/compiler output */
 304   case bfd_archive:
 305     return "archive";           /* object archive file */
 306   case bfd_core:
 307     return "core";              /* core dump */
 308   default:
 309     return "unknown";
 310   }
 311 }