bfd/format.c

   1 /* Generic BFD support for file formats.
   2    Copyright 1990, 1991, 1992, 1993, 1994, 1995, 1999, 2000, 2001, 2002,
   3    2003, 2005 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., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, 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         bfd_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 bfd_boolean
  89 bfd_check_format (bfd *abfd, bfd_format format)
  90 {
  91   return bfd_check_format_matches (abfd, format, NULL);
  92 }
  93
  94 /*
  95 FUNCTION
  96         bfd_check_format_matches
  97
  98 SYNOPSIS
  99         bfd_boolean bfd_check_format_matches
 100           (bfd *abfd, bfd_format format, char ***matching);
 101
 102 DESCRIPTION
 103         Like <<bfd_check_format>>, except when it returns FALSE with
 104         <<bfd_errno>> set to <<bfd_error_file_ambiguously_recognized>>.  In that
 105         case, if @var{matching} is not NULL, it will be filled in with
 106         a NULL-terminated list of the names of the formats that matched,
 107         allocated with <<malloc>>.
 108         Then the user may choose a format and try again.
 109
 110         When done with the list that @var{matching} points to, the caller
 111         should free it.
 112 */
 113
 114 bfd_boolean
 115 bfd_check_format_matches (bfd *abfd, bfd_format format, char ***matching)
 116 {
 117   extern const bfd_target binary_vec;
 118   const bfd_target * const *target;
 119   const bfd_target **matching_vector = NULL;
 120   const bfd_target *save_targ, *right_targ, *ar_right_targ;
 121   int match_count;
 122   int ar_match_index;
 123
 124   if (!bfd_read_p (abfd)
 125       || (unsigned int) abfd->format >= (unsigned int) bfd_type_end)
 126     {
 127       bfd_set_error (bfd_error_invalid_operation);
 128       return FALSE;
 129     }
 130
 131   if (abfd->format != bfd_unknown)
 132     return abfd->format == format;
 133
 134   /* Since the target type was defaulted, check them
 135      all in the hope that one will be uniquely recognized.  */
 136   save_targ = abfd->xvec;
 137   match_count = 0;
 138   ar_match_index = _bfd_target_vector_entries;
 139
 140   if (matching)
 141     {
 142       bfd_size_type amt;
 143
 144       *matching = NULL;
 145       amt = sizeof (*matching_vector) * 2 * _bfd_target_vector_entries;
 146       matching_vector = bfd_malloc (amt);
 147       if (!matching_vector)
 148         return FALSE;
 149     }
 150
 151   right_targ = 0;
 152   ar_right_targ = 0;
 153
 154   /* Presume the answer is yes.  */
 155   abfd->format = format;
 156
 157   /* If the target type was explicitly specified, just check that target.  */
 158   if (!abfd->target_defaulted)
 159     {
 160       if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0) /* rewind! */
 161         {
 162           if (matching)
 163             free (matching_vector);
 164           return FALSE;
 165         }
 166
 167       right_targ = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
 168
 169       if (right_targ)
 170         {
 171           abfd->xvec = right_targ;      /* Set the target as returned.  */
 172
 173           if (matching)
 174             free (matching_vector);
 175
 176           /* If the file was opened for update, then `output_has_begun'
 177              some time ago when the file was created.  Do not recompute
 178              sections sizes or alignments in _bfd_set_section_contents.
 179              We can not set this flag until after checking the format,
 180              because it will interfere with creation of BFD sections.  */
 181           if (abfd->direction == both_direction)
 182             abfd->output_has_begun = TRUE;
 183
 184           return TRUE;                  /* File position has moved, BTW.  */
 185         }
 186
 187       /* For a long time the code has dropped through to check all
 188          targets if the specified target was wrong.  I don't know why,
 189          and I'm reluctant to change it.  However, in the case of an
 190          archive, it can cause problems.  If the specified target does
 191          not permit archives (e.g., the binary target), then we should
 192          not allow some other target to recognize it as an archive, but
 193          should instead allow the specified target to recognize it as an
 194          object.  When I first made this change, it broke the PE target,
 195          because the specified pei-i386 target did not recognize the
 196          actual pe-i386 archive.  Since there may be other problems of
 197          this sort, I changed this test to check only for the binary
 198          target.  */
 199       if (format == bfd_archive && save_targ == &binary_vec)
 200         {
 201           abfd->xvec = save_targ;
 202           abfd->format = bfd_unknown;
 203
 204           if (matching)
 205             free (matching_vector);
 206
 207           bfd_set_error (bfd_error_file_not_recognized);
 208
 209           return FALSE;
 210         }
 211     }
 212
 213   for (target = bfd_target_vector; *target != NULL; target++)
 214     {
 215       const bfd_target *temp;
 216       bfd_error_type err;
 217
 218       if (*target == &binary_vec)
 219         continue;
 220
 221       abfd->xvec = *target;     /* Change BFD's target temporarily.  */
 222
 223       if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0)
 224         {
 225           if (matching)
 226             free (matching_vector);
 227           return FALSE;
 228         }
 229
 230       /* If _bfd_check_format neglects to set bfd_error, assume
 231          bfd_error_wrong_format.  We didn't used to even pay any
 232          attention to bfd_error, so I suspect that some
 233          _bfd_check_format might have this problem.  */
 234       bfd_set_error (bfd_error_wrong_format);
 235
 236       temp = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
 237
 238       if (temp)
 239         {
 240           /* This format checks out as ok!  */
 241           right_targ = temp;
 242
 243           /* If this is the default target, accept it, even if other
 244              targets might match.  People who want those other targets
 245              have to set the GNUTARGET variable.  */
 246           if (temp == bfd_default_vector[0])
 247             {
 248               match_count = 1;
 249               break;
 250             }
 251
 252           if (matching)
 253             matching_vector[match_count] = temp;
 254
 255           match_count++;
 256         }
 257       else if ((err = bfd_get_error ()) == bfd_error_wrong_object_format
 258                || err == bfd_error_file_ambiguously_recognized)
 259         {
 260           /* An archive with objects of the wrong type, or an
 261              ambiguous match.  We want this target to match if we get
 262              no better matches.  */
 263           if (ar_right_targ != bfd_default_vector[0])
 264             ar_right_targ = *target;
 265           if (matching)
 266             matching_vector[ar_match_index] = *target;
 267           ar_match_index++;
 268         }
 269       else if (err != bfd_error_wrong_format)
 270         {
 271           abfd->xvec = save_targ;
 272           abfd->format = bfd_unknown;
 273
 274           if (matching)
 275             free (matching_vector);
 276
 277           return FALSE;
 278         }
 279     }
 280
 281   if (match_count == 0)
 282     {
 283       /* Try partial matches.  */
 284       right_targ = ar_right_targ;
 285
 286       if (right_targ == bfd_default_vector[0])
 287         {
 288           match_count = 1;
 289         }
 290       else
 291         {
 292           match_count = ar_match_index - _bfd_target_vector_entries;
 293
 294           if (matching && match_count > 1)
 295             memcpy (matching_vector,
 296                     matching_vector + _bfd_target_vector_entries,
 297                     sizeof (*matching_vector) * match_count);
 298         }
 299     }
 300
 301   if (match_count > 1
 302       && bfd_associated_vector != NULL
 303       && matching)
 304     {
 305       const bfd_target * const *assoc = bfd_associated_vector;
 306
 307       while ((right_targ = *assoc++) != NULL)
 308         {
 309           int i = match_count;
 310
 311           while (--i >= 0)
 312             if (matching_vector[i] == right_targ)
 313               break;
 314
 315           if (i >= 0)
 316             {
 317               match_count = 1;
 318               break;
 319             }
 320         }
 321     }
 322
 323   if (match_count == 1)
 324     {
 325       abfd->xvec = right_targ;          /* Change BFD's target permanently.  */
 326
 327       if (matching)
 328         free (matching_vector);
 329
 330       /* If the file was opened for update, then `output_has_begun'
 331          some time ago when the file was created.  Do not recompute
 332          sections sizes or alignments in _bfd_set_section_contents.
 333          We can not set this flag until after checking the format,
 334          because it will interfere with creation of BFD sections.  */
 335       if (abfd->direction == both_direction)
 336         abfd->output_has_begun = TRUE;
 337
 338       return TRUE;                      /* File position has moved, BTW.  */
 339     }
 340
 341   abfd->xvec = save_targ;               /* Restore original target type.  */
 342   abfd->format = bfd_unknown;           /* Restore original format.  */
 343
 344   if (match_count == 0)
 345     {
 346       bfd_set_error (bfd_error_file_not_recognized);
 347
 348       if (matching)
 349         free (matching_vector);
 350     }
 351   else
 352     {
 353       bfd_set_error (bfd_error_file_ambiguously_recognized);
 354
 355       if (matching)
 356         {
 357           *matching = (char **) matching_vector;
 358           matching_vector[match_count] = NULL;
 359           /* Return target names.  This is a little nasty.  Maybe we
 360              should do another bfd_malloc?  */
 361           while (--match_count >= 0)
 362             {
 363               const char *name = matching_vector[match_count]->name;
 364               *(const char **) &matching_vector[match_count] = name;
 365             }
 366         }
 367     }
 368
 369   return FALSE;
 370 }
 371
 372 /*
 373 FUNCTION
 374         bfd_set_format
 375
 376 SYNOPSIS
 377         bfd_boolean bfd_set_format (bfd *abfd, bfd_format format);
 378
 379 DESCRIPTION
 380         This function sets the file format of the BFD @var{abfd} to the
 381         format @var{format}. If the target set in the BFD does not
 382         support the format requested, the format is invalid, or the BFD
 383         is not open for writing, then an error occurs.
 384 */
 385
 386 bfd_boolean
 387 bfd_set_format (bfd *abfd, bfd_format format)
 388 {
 389   if (bfd_read_p (abfd)
 390       || (unsigned int) abfd->format >= (unsigned int) bfd_type_end)
 391     {
 392       bfd_set_error (bfd_error_invalid_operation);
 393       return FALSE;
 394     }
 395
 396   if (abfd->format != bfd_unknown)
 397     return abfd->format == format;
 398
 399   /* Presume the answer is yes.  */
 400   abfd->format = format;
 401
 402   if (!BFD_SEND_FMT (abfd, _bfd_set_format, (abfd)))
 403     {
 404       abfd->format = bfd_unknown;
 405       return FALSE;
 406     }
 407
 408   return TRUE;
 409 }
 410
 411 /*
 412 FUNCTION
 413         bfd_format_string
 414
 415 SYNOPSIS
 416         const char *bfd_format_string (bfd_format format);
 417
 418 DESCRIPTION
 419         Return a pointer to a const string
 420         <<invalid>>, <<object>>, <<archive>>, <<core>>, or <<unknown>>,
 421         depending upon the value of @var{format}.
 422 */
 423
 424 const char *
 425 bfd_format_string (bfd_format format)
 426 {
 427   if (((int) format < (int) bfd_unknown)
 428       || ((int) format >= (int) bfd_type_end))
 429     return "invalid";
 430
 431   switch (format)
 432     {
 433     case bfd_object:
 434       return "object";          /* Linker/assembler/compiler output.  */
 435     case bfd_archive:
 436       return "archive";         /* Object archive file.  */
 437     case bfd_core:
 438       return "core";            /* Core dump.  */
 439     default:
 440       return "unknown";
 441     }
 442 }