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, 2007, 2008 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 3 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,
  21    MA 02110-1301, USA.  */
  22
  23
  24 /*
  25 SECTION
  26         File formats
  27
  28         A format is a BFD concept of high level file contents type. The
  29         formats supported by BFD are:
  30
  31         o <<bfd_object>>
  32
  33         The BFD may contain data, symbols, relocations and debug info.
  34
  35         o <<bfd_archive>>
  36
  37         The BFD contains other BFDs and an optional index.
  38
  39         o <<bfd_core>>
  40
  41         The BFD contains the result of an executable core dump.
  42
  43 SUBSECTION
  44         File format functions
  45 */
  46
  47 #include "sysdep.h"
  48 #include "bfd.h"
  49 #include "libbfd.h"
  50
  51 /* IMPORT from targets.c.  */
  52 extern const size_t _bfd_target_vector_entries;
  53
  54 /*
  55 FUNCTION
  56         bfd_check_format
  57
  58 SYNOPSIS
  59         bfd_boolean bfd_check_format (bfd *abfd, bfd_format format);
  60
  61 DESCRIPTION
  62         Verify if the file attached to the BFD @var{abfd} is compatible
  63         with the format @var{format} (i.e., one of <<bfd_object>>,
  64         <<bfd_archive>> or <<bfd_core>>).
  65
  66         If the BFD has been set to a specific target before the
  67         call, only the named target and format combination is
  68         checked. If the target has not been set, or has been set to
  69         <<default>>, then all the known target backends is
  70         interrogated to determine a match.  If the default target
  71         matches, it is used.  If not, exactly one target must recognize
  72         the file, or an error results.
  73
  74         The function returns <<TRUE>> on success, otherwise <<FALSE>>
  75         with one of the following error codes:
  76
  77         o <<bfd_error_invalid_operation>> -
  78         if <<format>> is not one of <<bfd_object>>, <<bfd_archive>> or
  79         <<bfd_core>>.
  80
  81         o <<bfd_error_system_call>> -
  82         if an error occured during a read - even some file mismatches
  83         can cause bfd_error_system_calls.
  84
  85         o <<file_not_recognised>> -
  86         none of the backends recognised the file format.
  87
  88         o <<bfd_error_file_ambiguously_recognized>> -
  89         more than one backend recognised the file format.
  90 */
  91
  92 bfd_boolean
  93 bfd_check_format (bfd *abfd, bfd_format format)
  94 {
  95   return bfd_check_format_matches (abfd, format, NULL);
  96 }
  97
  98 /*
  99 FUNCTION
 100         bfd_check_format_matches
 101
 102 SYNOPSIS
 103         bfd_boolean bfd_check_format_matches
 104           (bfd *abfd, bfd_format format, char ***matching);
 105
 106 DESCRIPTION
 107         Like <<bfd_check_format>>, except when it returns FALSE with
 108         <<bfd_errno>> set to <<bfd_error_file_ambiguously_recognized>>.  In that
 109         case, if @var{matching} is not NULL, it will be filled in with
 110         a NULL-terminated list of the names of the formats that matched,
 111         allocated with <<malloc>>.
 112         Then the user may choose a format and try again.
 113
 114         When done with the list that @var{matching} points to, the caller
 115         should free it.
 116 */
 117
 118 bfd_boolean
 119 bfd_check_format_matches (bfd *abfd, bfd_format format, char ***matching)
 120 {
 121   extern const bfd_target binary_vec;
 122   const bfd_target * const *target;
 123   const bfd_target **matching_vector = NULL;
 124   const bfd_target *save_targ, *right_targ, *ar_right_targ;
 125   int match_count;
 126   int ar_match_index;
 127
 128   if (matching != NULL)
 129     *matching = NULL;
 130
 131   if (!bfd_read_p (abfd)
 132       || (unsigned int) abfd->format >= (unsigned int) bfd_type_end)
 133     {
 134       bfd_set_error (bfd_error_invalid_operation);
 135       return FALSE;
 136     }
 137
 138   if (abfd->format != bfd_unknown)
 139     return abfd->format == format;
 140
 141   /* Since the target type was defaulted, check them
 142      all in the hope that one will be uniquely recognized.  */
 143   save_targ = abfd->xvec;
 144   match_count = 0;
 145   ar_match_index = _bfd_target_vector_entries;
 146
 147   if (matching != NULL || *bfd_associated_vector != NULL)
 148     {
 149       bfd_size_type amt;
 150
 151       amt = sizeof (*matching_vector) * 2 * _bfd_target_vector_entries;
 152       matching_vector = bfd_malloc (amt);
 153       if (!matching_vector)
 154         return FALSE;
 155     }
 156
 157   right_targ = 0;
 158   ar_right_targ = 0;
 159
 160   /* Presume the answer is yes.  */
 161   abfd->format = format;
 162
 163   /* If the target type was explicitly specified, just check that target.  */
 164   if (!abfd->target_defaulted)
 165     {
 166       if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0) /* rewind! */
 167         goto err_ret;
 168
 169       right_targ = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
 170
 171       if (right_targ)
 172         goto ok_ret;
 173
 174       /* For a long time the code has dropped through to check all
 175          targets if the specified target was wrong.  I don't know why,
 176          and I'm reluctant to change it.  However, in the case of an
 177          archive, it can cause problems.  If the specified target does
 178          not permit archives (e.g., the binary target), then we should
 179          not allow some other target to recognize it as an archive, but
 180          should instead allow the specified target to recognize it as an
 181          object.  When I first made this change, it broke the PE target,
 182          because the specified pei-i386 target did not recognize the
 183          actual pe-i386 archive.  Since there may be other problems of
 184          this sort, I changed this test to check only for the binary
 185          target.  */
 186       if (format == bfd_archive && save_targ == &binary_vec)
 187         goto err_unrecog;
 188     }
 189
 190   for (target = bfd_target_vector; *target != NULL; target++)
 191     {
 192       const bfd_target *temp;
 193       bfd_error_type err;
 194
 195       /* Don't check the default target twice.  */
 196       if (*target == &binary_vec
 197           || (!abfd->target_defaulted && *target == save_targ))
 198         continue;
 199
 200       abfd->xvec = *target;     /* Change BFD's target temporarily.  */
 201
 202       if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0)
 203         goto err_ret;
 204
 205       /* If _bfd_check_format neglects to set bfd_error, assume
 206          bfd_error_wrong_format.  We didn't used to even pay any
 207          attention to bfd_error, so I suspect that some
 208          _bfd_check_format might have this problem.  */
 209       bfd_set_error (bfd_error_wrong_format);
 210
 211       temp = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
 212
 213       if (temp && (abfd->format != bfd_archive || bfd_has_map (abfd)))
 214         {
 215           /* This format checks out as ok!  */
 216           right_targ = temp;
 217
 218           /* If this is the default target, accept it, even if other
 219              targets might match.  People who want those other targets
 220              have to set the GNUTARGET variable.  */
 221           if (temp == bfd_default_vector[0])
 222             {
 223               match_count = 1;
 224               break;
 225             }
 226
 227           if (matching_vector)
 228             matching_vector[match_count] = temp;
 229           match_count++;
 230         }
 231       else if (temp
 232                || (err = bfd_get_error ()) == bfd_error_wrong_object_format
 233                || err == bfd_error_file_ambiguously_recognized)
 234         {
 235           /* An archive with no armap or objects of the wrong type,
 236              or an ambiguous match.  We want this target to match
 237              if we get no better matches.  */
 238           if (ar_right_targ != bfd_default_vector[0])
 239             ar_right_targ = *target;
 240           if (matching_vector)
 241             matching_vector[ar_match_index] = *target;
 242           ar_match_index++;
 243         }
 244       else if (err != bfd_error_wrong_format)
 245         goto err_ret;
 246     }
 247
 248   if (match_count == 0)
 249     {
 250       /* Try partial matches.  */
 251       right_targ = ar_right_targ;
 252
 253       if (right_targ == bfd_default_vector[0])
 254         {
 255           match_count = 1;
 256         }
 257       else
 258         {
 259           match_count = ar_match_index - _bfd_target_vector_entries;
 260
 261           if (matching_vector && match_count > 1)
 262             memcpy (matching_vector,
 263                     matching_vector + _bfd_target_vector_entries,
 264                     sizeof (*matching_vector) * match_count);
 265         }
 266     }
 267
 268   if (match_count > 1)
 269     {
 270       const bfd_target * const *assoc = bfd_associated_vector;
 271
 272       while ((right_targ = *assoc++) != NULL)
 273         {
 274           int i = match_count;
 275
 276           while (--i >= 0)
 277             if (matching_vector[i] == right_targ)
 278               break;
 279
 280           if (i >= 0)
 281             {
 282               match_count = 1;
 283               break;
 284             }
 285         }
 286     }
 287
 288   if (match_count == 1)
 289     {
 290     ok_ret:
 291       abfd->xvec = right_targ;          /* Change BFD's target permanently.  */
 292
 293       /* If the file was opened for update, then `output_has_begun'
 294          some time ago when the file was created.  Do not recompute
 295          sections sizes or alignments in _bfd_set_section_contents.
 296          We can not set this flag until after checking the format,
 297          because it will interfere with creation of BFD sections.  */
 298       if (abfd->direction == both_direction)
 299         abfd->output_has_begun = TRUE;
 300
 301       if (matching_vector)
 302         free (matching_vector);
 303       return TRUE;                      /* File position has moved, BTW.  */
 304     }
 305
 306   if (match_count == 0)
 307     {
 308     err_unrecog:
 309       bfd_set_error (bfd_error_file_not_recognized);
 310     err_ret:
 311       abfd->xvec = save_targ;
 312       abfd->format = bfd_unknown;
 313       if (matching_vector)
 314         free (matching_vector);
 315       return FALSE;
 316     }
 317
 318   abfd->xvec = save_targ;               /* Restore original target type.  */
 319   abfd->format = bfd_unknown;           /* Restore original format.  */
 320   bfd_set_error (bfd_error_file_ambiguously_recognized);
 321
 322   if (matching)
 323     {
 324       *matching = (char **) matching_vector;
 325       matching_vector[match_count] = NULL;
 326       /* Return target names.  This is a little nasty.  Maybe we
 327          should do another bfd_malloc?  */
 328       while (--match_count >= 0)
 329         {
 330           const char *name = matching_vector[match_count]->name;
 331           *(const char **) &matching_vector[match_count] = name;
 332         }
 333     }
 334   return FALSE;
 335 }
 336
 337 /*
 338 FUNCTION
 339         bfd_set_format
 340
 341 SYNOPSIS
 342         bfd_boolean bfd_set_format (bfd *abfd, bfd_format format);
 343
 344 DESCRIPTION
 345         This function sets the file format of the BFD @var{abfd} to the
 346         format @var{format}. If the target set in the BFD does not
 347         support the format requested, the format is invalid, or the BFD
 348         is not open for writing, then an error occurs.
 349 */
 350
 351 bfd_boolean
 352 bfd_set_format (bfd *abfd, bfd_format format)
 353 {
 354   if (bfd_read_p (abfd)
 355       || (unsigned int) abfd->format >= (unsigned int) bfd_type_end)
 356     {
 357       bfd_set_error (bfd_error_invalid_operation);
 358       return FALSE;
 359     }
 360
 361   if (abfd->format != bfd_unknown)
 362     return abfd->format == format;
 363
 364   /* Presume the answer is yes.  */
 365   abfd->format = format;
 366
 367   if (!BFD_SEND_FMT (abfd, _bfd_set_format, (abfd)))
 368     {
 369       abfd->format = bfd_unknown;
 370       return FALSE;
 371     }
 372
 373   return TRUE;
 374 }
 375
 376 /*
 377 FUNCTION
 378         bfd_format_string
 379
 380 SYNOPSIS
 381         const char *bfd_format_string (bfd_format format);
 382
 383 DESCRIPTION
 384         Return a pointer to a const string
 385         <<invalid>>, <<object>>, <<archive>>, <<core>>, or <<unknown>>,
 386         depending upon the value of @var{format}.
 387 */
 388
 389 const char *
 390 bfd_format_string (bfd_format format)
 391 {
 392   if (((int) format < (int) bfd_unknown)
 393       || ((int) format >= (int) bfd_type_end))
 394     return "invalid";
 395
 396   switch (format)
 397     {
 398     case bfd_object:
 399       return "object";          /* Linker/assembler/compiler output.  */
 400     case bfd_archive:
 401       return "archive";         /* Object archive file.  */
 402     case bfd_core:
 403       return "core";            /* Core dump.  */
 404     default:
 405       return "unknown";
 406     }
 407 }